Evapotranspiration sensitivity to air temperature across a snow-influenced watershed: Space-for-time substitution versus integrated watershed modeling

NASA Astrophysics Data System (ADS)

Jepsen, S. M.; Harmon, T. C.; Ficklin, D. L.; Molotch, N. P.; Guan, B.

2018-01-01

Changes in long-term, montane actual evapotranspiration (ET) in response to climate change could impact future water supplies and forest species composition. For scenarios of atmospheric warming, predicted changes in long-term ET tend to differ between studies using space-for-time substitution (STS) models and integrated watershed models, and the influence of spatially varying factors on these differences is unclear. To examine this, we compared warming-induced (+2 to +6 °C) changes in ET simulated by an STS model and an integrated watershed model across zones of elevation, substrate available water capacity, and slope in the snow-influenced upper San Joaquin River watershed, Sierra Nevada, USA. We used the Soil Water and Assessment Tool (SWAT) for the watershed modeling and a Budyko-type relationship for the STS modeling. Spatially averaged increases in ET from the STS model increasingly surpassed those from the SWAT model in the higher elevation zones of the watershed, resulting in 2.3-2.6 times greater values from the STS model at the watershed scale. In sparse, deep colluvium or glacial soils on gentle slopes, the SWAT model produced ET increases exceeding those from the STS model. However, watershed areas associated with these conditions were too localized for SWAT to produce spatially averaged ET-gains comparable to the STS model. The SWAT model results nevertheless demonstrate that such soils on high-elevation, gentle slopes will form ET "hot spots" exhibiting disproportionately large increases in ET, and concomitant reductions in runoff yield, in response to warming. Predicted ET responses to warming from STS models and integrated watershed models may, in general, substantially differ (e.g., factor of 2-3) for snow-influenced watersheds exhibiting an elevational gradient in substrate water holding capacity and slope. Long-term water supplies in these settings may therefore be more resilient to warming than STS model predictions would suggest.

A reactive transport modelling approach to assess the leaching potential of hydraulic fracturing fluids associated with coal seam gas extraction

NASA Astrophysics Data System (ADS)

Mallants, Dirk; Simunek, Jirka; Gerke, Kirill

2015-04-01

Coal Seam Gas production generates large volumes of "produced" water that may contain compounds originating from the use of hydraulic fracturing fluids. Such produced water also contains elevated concentrations of naturally occurring inorganic and organic compounds, and usually has a high salinity. Leaching of produced water from storage ponds may occur as a result of flooding or containment failure. Some produced water is used for irrigation of specific crops tolerant to elevated salt levels. These chemicals may potentially contaminate soil, shallow groundwater, and groundwater, as well as receiving surface waters. This paper presents an application of scenario modelling using the reactive transport model for variably-saturated media HP1 (coupled HYDRUS-1D and PHREEQC). We evaluate the fate of hydraulic fracturing chemicals and naturally occurring chemicals in soil as a result of unintentional release from storage ponds or when produced water from Coal Seam Gas operations is used in irrigation practices. We present a review of exposure pathways and relevant hydro-bio-geo-chemical processes, a collation of physico-chemical properties of organic/inorganic contaminants as input to a set of generic simulations of transport and attenuation in variably saturated soil profiles. We demonstrate the ability to model the coupled processes of flow and transport in soil of contaminants associated with hydraulic fracturing fluids and naturally occurring contaminants.

The use of UAV to document sloping landscapes to produce digital elevation models to examine environmental degradation

NASA Astrophysics Data System (ADS)

Themistocleous, K.; Agapiou, A.; Papadavid, G.; Christoforou, M.; Hadjimitsis, D. G.

2015-10-01

This paper focuses on the use of Unmanned Aerial Vehicles (UAVs) over the study area of Pissouri in Cyprus to document the sloping landscapes of the area. The study area has been affected by overgrazing, which has led to shifts in the vegetation patterns and changing microtopography of the soil. The UAV images were used to generate digital elevation models (DEMs) to examine the changes in microtopography. Next to that orthophotos were used to detect changes in vegetation patterns. The combined data of the digital elevation models and the orthophotos will be used to detect the occurrence of catastrophic shifts and mechanisms for desertification in the study area due to overgrazing. This study is part of the "CASCADE- Catastrophic shifts in dryland" project.

Towards the Crowdsourcing of Massive Smartphone Assisted-GPS Sensor Ground Observations for the Production of Digital Terrain Models

PubMed Central

Massad, Ido

2018-01-01

Digital Terrain Models (DTMs) used for the representation of the bare earth are produced from elevation data obtained using high-end mapping platforms and technologies. These require the handling of complex post-processing performed by authoritative and commercial mapping agencies. In this research, we aim to exploit user-generated data to produce DTMs by handling massive volumes of position and elevation data collected using ubiquitous smartphone devices equipped with Assisted-GPS sensors. As massive position and elevation data are collected passively and straightforwardly by pedestrians, cyclists, and drivers, it can be transformed into valuable topographic information. Specifically, in dense and concealed built and vegetated areas, where other technologies fail, handheld devices have an advantage. Still, Assisted-GPS measurements are not as accurate as high-end technologies, requiring pre- and post-processing of observations. We propose the development and implementation of a 2D Kalman filter and smoothing on the acquired crowdsourced observations for topographic representation production. When compared to an authoritative DTM, results obtained are very promising in producing good elevation values. Today, open-source mapping infrastructures, such as OpenStreetMap, rely primarily on the global authoritative SRTM (Shuttle Radar Topography Mission), which shows similar accuracy but inferior resolution when compared to the results obtained in this research. Accordingly, our crowdsourced methodology has the capacity for reliable topographic representation production that is based on ubiquitous volunteered user-generated data. PMID:29562627

Combining slope stability and groundwater flow models to assess stratovolcano collapse hazard

NASA Astrophysics Data System (ADS)

Ball, J. L.; Taron, J.; Reid, M. E.; Hurwitz, S.; Finn, C.; Bedrosian, P.

2016-12-01

Flank collapses are a well-documented hazard at volcanoes. Elevated pore-fluid pressures and hydrothermal alteration are invoked as potential causes for the instability in many of these collapses. Because pore pressure is linked to water saturation and permeability of volcanic deposits, hydrothermal alteration is often suggested as a means of creating low-permeability zones in volcanoes. Here, we seek to address the question: What alteration geometries will produce elevated pore pressures in a stratovolcano, and what are the effects of these elevated pressures on slope stability? We initially use a finite element groundwater flow model (a modified version of OpenGeoSys) to simulate `generic' stratovolcano geometries that produce elevated pore pressures. We then input these results into the USGS slope-stability code Scoops3D to investigate the effects of alteration and magmatic intrusion on potential flank failure. This approach integrates geophysical data about subsurface alteration, water saturation and rock mechanical properties with data about precipitation and heat influx at Cascade stratovolcanoes. Our simulations show that it is possible to maintain high-elevation water tables in stratovolcanoes given specific ranges of edifice permeability (ideally between 10-15 and 10-16 m2). Low-permeability layers (10-17 m2, representing altered pyroclastic deposits or altered breccias) in the volcanoes can localize saturated regions close to the surface, but they may actually reduce saturation, pore pressures, and water table levels in the core of the volcano. These conditions produce universally lower factor-of-safety (F) values than at an equivalent dry edifice with the same material properties (lower values of F indicate a higher likelihood of collapse). When magmatic intrusions into the base of the cone are added, near-surface pore pressures increase and F decreases exponentially with time ( 7-8% in the first year). However, while near-surface impermeable layers create elevated water tables and pore pressures, they do not necessarily produce the largest or deepest collapses. This suggests that mechanical properties of both the edifice and layers still exert a significant control, and collapse volumes depend on a complex interplay of mechanical factors and layering.

Adjusting lidar-derived digital terrain models in coastal marshes based on estimated aboveground biomass density

DOE PAGES

Medeiros, Stephen; Hagen, Scott; Weishampel, John; ...

2015-03-25

Digital elevation models (DEMs) derived from airborne lidar are traditionally unreliable in coastal salt marshes due to the inability of the laser to penetrate the dense grasses and reach the underlying soil. To that end, we present a novel processing methodology that uses ASTER Band 2 (visible red), an interferometric SAR (IfSAR) digital surface model, and lidar-derived canopy height to classify biomass density using both a three-class scheme (high, medium and low) and a two-class scheme (high and low). Elevation adjustments associated with these classes using both median and quartile approaches were applied to adjust lidar-derived elevation values closer tomore » true bare earth elevation. The performance of the method was tested on 229 elevation points in the lower Apalachicola River Marsh. The two-class quartile-based adjusted DEM produced the best results, reducing the RMS error in elevation from 0.65 m to 0.40 m, a 38% improvement. The raw mean errors for the lidar DEM and the adjusted DEM were 0.61 ± 0.24 m and 0.32 ± 0.24 m, respectively, thereby reducing the high bias by approximately 49%.« less

Estimating net solar radiation using Landsat Thematic Mapper and digital elevation data

NASA Technical Reports Server (NTRS)

Dubayah, R.

1992-01-01

A radiative transfer algorithm is combined with digital elevation and satellite reflectance data to model spatial variability in net solar radiation at fine spatial resolution. The method is applied to the tall-grass prairie of the 16 x 16 sq km FIFE site (First ISLSCP Field Experiment) of the International Satellite Land Surface Climatology Project. Spectral reflectances as measured by the Landsat Thematic Mapper (TM) are corrected for atmospheric and topographic effects using field measurements and accurate 30-m digital elevation data in a detailed model of atmosphere-surface interaction. The spectral reflectances are then integrated to produce estimates of surface albedo in the range 0.3-3.0 microns. This map of albedo is used in an atmospheric and topographic radiative transfer model to produce a map of net solar radiation. A map of apparent net solar radiation is also derived using only the TM reflectance data, uncorrected for topography, and the average field-measured downwelling solar irradiance. Comparison with field measurements at 10 sites on the prairie shows that the topographically derived radiation map accurately captures the spatial variability in net solar radiation, but the apparent map does not.

Methods for Combination of GRACE Gravimetry and ICESat Altimetry over Antarctica on Monthly Timescales

NASA Astrophysics Data System (ADS)

Hardy, R. A.; Nerem, R. S.; Wiese, D. N.

2017-12-01

Gravity and surface elevation change data altimetry provide different perspectives on mass variability in Antarctica. In anticipation of the concurrent operation of the successors of GRACE and ICESat, GRACE Follow-On and ICESat-2, we approach the problem of combining these data for enhanced spatial resolution and disaggregation of Antarctica's major mass transport processes. Using elevation changes gathered from over 500 million overlapping ICESat laser shot pairs between 2003 and 2009, we construct gridded models of Antarctic elevation change for each ICESat operational period. Comparing these elevation grids with temporally registered JPL RL05M mascon solutions, we exploit the relationship between surface mass flux and elevation change to inform estimates of effective surface density. These density estimates enable solutions for glacial isostatic adjustment and monthly estimates of surface mass change. These are used alongside spatial statistics from both the data and models of surface mass balance to produce enhanced estimates of Antarctic mass balance. We validate our solutions by modeling the effects of elastic loading and GIA from these solutions on the vertical motion of Antarctica's GNSS sites.

Initial Everglades Depth Estimation Network (EDEN) Digital Elevation Model Research and Development

USGS Publications Warehouse

Jones, John W.; Price, Susan D.

2007-01-01

Introduction The Everglades Depth Estimation Network (EDEN) offers a consistent and documented dataset that can be used to guide large-scale field operations, to integrate hydrologic and ecological responses, and to support biological and ecological assessments that measure ecosystem responses to the Comprehensive Everglades Restoration Plan (Telis, 2006). To produce historic and near-real time maps of water depths, the EDEN requires a system-wide digital elevation model (DEM) of the ground surface. Accurate Everglades wetland ground surface elevation data were non-existent before the U.S. Geological Survey (USGS) undertook the collection of highly accurate surface elevations at the regional scale. These form the foundation for EDEN DEM development. This development process is iterative as additional high accuracy elevation data (HAED) are collected, water surfacing algorithms improve, and additional ground-based ancillary data become available. Models are tested using withheld HAED and independently measured water depth data, and by using DEM data in EDEN adaptive management applications. Here the collection of HAED is briefly described before the approach to DEM development and the current EDEN DEM are detailed. Finally future research directions for continued model development, testing, and refinement are provided.

Lunar Pole Illumination and Communications Maps Computed from GSSR Elevation Data

NASA Technical Reports Server (NTRS)

Bryant, Scott

2009-01-01

A Digital Elevation Model of the lunar south pole was produced using Goldstone Solar System RADAR (GSSR) data obtained in 2006.12 This model has 40-meter horizontal resolution and about 5-meter relative vertical accuracy. This Digital Elevation Model was used to compute average solar illumination and Earth visibility with 100 kilometers of the lunar south pole. The elevation data were converted into local terrain horizon masks, then converted into lunar-centric latitude and longitude coordinates. The horizon masks were compared to latitude, longitude regions bounding the maximum Sun and Earth motions relative to the moon. Estimates of Earth visibility were computed by integrating the area of the region bounding the Earth's motion that was below the horizon mask. Solar illumination and other metrics were computed similarly. Proposed lunar south pole base sites were examined in detail, with the best site showing yearly solar power availability of 92 percent and Direct-To-Earth (DTE) communication availability of about 50 percent. Similar analysis of the lunar south pole used an older GSSR Digital Elevation Model with 600-meter horizontal resolution. The paper also explores using a heliostat to reduce the photovoltaic power system mass and complexity.

Systemic Approach to Elevation Data Acquisition for Geophysical Survey Alignments in Hilly Terrains Using UAVs

NASA Astrophysics Data System (ADS)

Ismail, M. A. M.; Kumar, N. S.; Abidin, M. H. Z.; Madun, A.

2018-04-01

This study is about systematic approach to photogrammetric survey that is applicable in the extraction of elevation data for geophysical surveys in hilly terrains using Unmanned Aerial Vehicles (UAVs). The outcome will be to acquire high-quality geophysical data from areas where elevations vary by locating the best survey lines. The study area is located at the proposed construction site for the development of a water reservoir and related infrastructure in Kampus Pauh Putra, Universiti Malaysia Perlis. Seismic refraction surveys were carried out for the modelling of the subsurface for detailed site investigations. Study were carried out to identify the accuracy of the digital elevation model (DEM) produced from an UAV. At 100 m altitude (flying height), over 135 overlapping images were acquired using a DJI Phantom 3 quadcopter. All acquired images were processed for automatic 3D photo-reconstruction using Agisoft PhotoScan digital photogrammetric software, which was applied to all photogrammetric stages. The products generated included a 3D model, dense point cloud, mesh surface, digital orthophoto, and DEM. In validating the accuracy of the produced DEM, the coordinates of the selected ground control point (GCP) of the survey line in the imaging area were extracted from the generated DEM with the aid of Global Mapper software. These coordinates were compared with the GCPs obtained using a real-time kinematic global positioning system. The maximum percentage of difference between GCP’s and photogrammetry survey is 13.3 %. UAVs are suitable for acquiring elevation data for geophysical surveys which can save time and cost.

National Hydrography Dataset Plus (NHDPlus)

EPA Pesticide Factsheets

The NHDPlus Version 1.0 is an integrated suite of application-ready geospatial data sets that incorporate many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,000-scale NHD), improved networking, naming, and value-added attributes (VAA's). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainageenforcement technique first broadly applied in New England, and thus dubbed The New-England Method. This technique involves burning-in the 1:100,000-scale NHD and when available building walls using the national WatershedBoundary Dataset (WBD). The resulting modified digital elevation model(HydroDEM) is used to produce hydrologic derivatives that agree with the NHDand WBD. An interdisciplinary team from the U. S. Geological Survey (USGS), U.S. Environmental Protection Agency (USEPA), and contractors, over the lasttwo years has found this method to produce the best quality NHD catchments using an automated process.The VAAs include greatly enhanced capabilities for upstream and downstream navigation, analysis and modeling. Examples include: retrieve all flowlines (predominantly confluence-to-confluence stream segments) and catchments upstream of a given flowline using queries rather than by slower flowline-by flowline navigation; retrieve flowlines by stream order; subset a stream level path sorted in hydrologic order for st

Inability to produce a model of dialysis encephalopathy in the rat by aluminum administration.

PubMed

Perry, T L; Yong, V W; Godolphin, W J; Sutter, M; Hansen, S; Kish, S J; Foulks, J G; Ito, M

1987-04-01

We attempted to produce a rat model of brain aluminum toxicity in order to explore whether or not aluminum accumulation produces the neurochemical changes observed in brains of patients who die with dialysis encephalopathy. Daily subcutaneous injection of Al(OH)3 caused marked elevation of serum aluminum concentrations, but did not increase brain aluminum contents, either in rats with normal renal function, or in rats with unilateral or 5/6 nephrectomies. LiCl pretreatment, which has been reported to cause irreversible renal failure, did not impair renal function nor aid in achieving elevated brain aluminum contents. No reductions in brain contents of gamma-aminobutyric acid (GABA) or in glutamic acid decarboxylase (GAD, E.C.4.1.1.15) and choline acetyltransferase (ChAT, E.C.2.3.1.6) activities were observed in aluminum-treated rats. We conclude that the rat is not a suitable laboratory animal to explore the role of aluminum toxicity in causing the GABA and ChAT deficits present in brains of hemodialyzed human patients.

The Aerodynamic Forces and Moments Exerted on a Spinning Model of the NY-1 Airplane as Measured by the Spinning Balance

NASA Technical Reports Server (NTRS)

Bamber, M J; Zimmerm, N, C h

1934-01-01

A preliminary investigation of the effects of changes in the elevator and rudder settings and of small changes in attitude upon the aerodynamic forces and moments exerted upon a spinning airplane was undertaken with the spinning balance in the 5-foot vertical tunnel of the National Advisory Committee for Aeronautics. The tests were made on a 1/12-scale model of the ny-1 airplane. Data by which to fix the attitude, the radius of spin, and the rotational and air velocities were taken from recorded spins of the full-scale airplane. Two spinning conditions were investigated. All six components of the aerodynamic reaction were measured and are presented in coefficient form refereed to airplane axes. The results indicate that the change in yawing moment produced by the rudder with the elevator up was the only component of force or moment produced by the elevator and rudder that could not have been balanced in an actual spin by small changes in attitude and angular velocity.

Robust Mosaicking of Stereo Digital Elevation Models from the Ames Stereo Pipeline

NASA Technical Reports Server (NTRS)

Kim, Tae Min; Moratto, Zachary M.; Nefian, Ara Victor

2010-01-01

Robust estimation method is proposed to combine multiple observations and create consistent, accurate, dense Digital Elevation Models (DEMs) from lunar orbital imagery. The NASA Ames Intelligent Robotics Group (IRG) aims to produce higher-quality terrain reconstructions of the Moon from Apollo Metric Camera (AMC) data than is currently possible. In particular, IRG makes use of a stereo vision process, the Ames Stereo Pipeline (ASP), to automatically generate DEMs from consecutive AMC image pairs. However, the DEMs currently produced by the ASP often contain errors and inconsistencies due to image noise, shadows, etc. The proposed method addresses this problem by making use of multiple observations and by considering their goodness of fit to improve both the accuracy and robustness of the estimate. The stepwise regression method is applied to estimate the relaxed weight of each observation.

Simulating certain aspects of hypogravity: Effects on the mandibular incisors of suspended rats (PULEH model)

NASA Technical Reports Server (NTRS)

Simmons, D. J.; Winter, F.; Morey-Holton, E. R.

1984-01-01

The effect of a hypogravity simulating model on the rate of mandibular incisor formation, dentinogenesis and, amelogenesis in laboratory rats was studied. The model is the partial unloading by elevating the hindquarters. In this system, rat hindquarters are elevated 30 to 40 deg from the cage floors to completely unload the hindlimbs, but the animals are free to move about using their forelimbs. This model replicates the fluid sift changes which occur during the weightlessness of spaceflight and produces an osteopenia in the weight bearing skeletons. The histogenesis and/or mineralization rates of the mandibular incisor during the first 19d of PULEH in young growing rats are recorded.

Light Levels, Refractive Development, and Myopia – a Speculative Review

PubMed Central

Norton, Thomas T.; Siegwart, John T.

2013-01-01

Recent epidemiological evidence in children indicates that time spent outdoors is protective against myopia. Studies in animal models (chick, macaque, tree shrew) have found that light levels (similar to being in the shade outdoors) that are mildly elevated compared to indoor levels, slow form-deprivation myopia and (in chick and tree shrew) lens-induced myopia. Normal chicks raised in low light levels (50 lux) with a circadian light on/off cycle often develop spontaneous myopia. We propose a model in which the ambient illuminance levels produce a continuum of effects on normal refractive development and the response to myopiagenic stimuli such that low light levels favor myopia development and elevated levels are protective. Among possible mechanisms, elevation of retinal dopamine activity seems the most likely. Inputs from intrinsically-photosensitive retinal ganglion cells (ipRGCs) at elevated light levels may be involved, providing additional activation of retinal dopaminergic pathways. PMID:23680160

Biogeographical Interpretation of Elevational Patterns of Genus Diversity of Seed Plants in Nepal

PubMed Central

Li, Miao; Feng, Jianmeng

2015-01-01

This study tests if the biogeographical affinities of genera are relevant for explaining elevational plant diversity patterns in Nepal. We used simultaneous autoregressive (SAR) models to investigate the explanatory power of several predictors in explaining the diversity-elevation relationships shown in genera with different biogeographical affinities. Delta akaike information criterion (ΔAIC) was used for multi-model inferences and selections. Our results showed that both the total and tropical genus diversity peaked below the mid-point of the elevational gradient, whereas that of temperate genera had a nearly symmetrical, unimodal relationship with elevation. The proportion of temperate genera increased markedly with elevation, while that of tropical genera declined. Compared to tropical genera, temperate genera had wider elevational ranges and were observed at higher elevations. Water-related variables, rather than mid-domain effects (MDE), were the most significant predictors of elevational patterns of tropical genus diversity. The temperate genus diversity was influenced by energy availability, but only in quadratic terms of the models. Though climatic factors and mid-domain effects jointly explained most of the variation in the diversity of temperate genera with elevation, the former played stronger roles. Total genus diversity was most strongly influenced by climate and the floristic overlap of tropical and temperate floras, while the influences of mid-domain effects were relatively weak. The influences of water-related and energy-related variables may vary with biogeographical affinities. The elevational patterns may be most closely related to climatic factors, while MDE may somewhat modify the patterns. Caution is needed when investigating the causal factors underlying diversity patterns for large taxonomic groups composed of taxa of different biogeographical affinities. Right-skewed diversity-elevation patterns may be produced by the differential response of taxa with varying biogeographical affinities to climatic factors and MDE. PMID:26488164

Biogeographical Interpretation of Elevational Patterns of Genus Diversity of Seed Plants in Nepal.

PubMed

Li, Miao; Feng, Jianmeng

2015-01-01

This study tests if the biogeographical affinities of genera are relevant for explaining elevational plant diversity patterns in Nepal. We used simultaneous autoregressive (SAR) models to investigate the explanatory power of several predictors in explaining the diversity-elevation relationships shown in genera with different biogeographical affinities. Delta akaike information criterion (ΔAIC) was used for multi-model inferences and selections. Our results showed that both the total and tropical genus diversity peaked below the mid-point of the elevational gradient, whereas that of temperate genera had a nearly symmetrical, unimodal relationship with elevation. The proportion of temperate genera increased markedly with elevation, while that of tropical genera declined. Compared to tropical genera, temperate genera had wider elevational ranges and were observed at higher elevations. Water-related variables, rather than mid-domain effects (MDE), were the most significant predictors of elevational patterns of tropical genus diversity. The temperate genus diversity was influenced by energy availability, but only in quadratic terms of the models. Though climatic factors and mid-domain effects jointly explained most of the variation in the diversity of temperate genera with elevation, the former played stronger roles. Total genus diversity was most strongly influenced by climate and the floristic overlap of tropical and temperate floras, while the influences of mid-domain effects were relatively weak. The influences of water-related and energy-related variables may vary with biogeographical affinities. The elevational patterns may be most closely related to climatic factors, while MDE may somewhat modify the patterns. Caution is needed when investigating the causal factors underlying diversity patterns for large taxonomic groups composed of taxa of different biogeographical affinities. Right-skewed diversity-elevation patterns may be produced by the differential response of taxa with varying biogeographical affinities to climatic factors and MDE.

Generation of a precise DEM by interactive synthesis of multi-temporal elevation datasets: a case study of Schirmacher Oasis, East Antarctica

NASA Astrophysics Data System (ADS)

Jawak, Shridhar D.; Luis, Alvarinho J.

2016-05-01

Digital elevation model (DEM) is indispensable for analysis such as topographic feature extraction, ice sheet melting, slope stability analysis, landscape analysis and so on. Such analysis requires a highly accurate DEM. Available DEMs of Antarctic region compiled by using radar altimetry and the Antarctic digital database indicate elevation variations of up to hundreds of meters, which necessitates the generation of local improved DEM. An improved DEM of the Schirmacher Oasis, East Antarctica has been generated by synergistically fusing satellite-derived laser altimetry data from Geoscience Laser Altimetry System (GLAS), Radarsat Antarctic Mapping Project (RAMP) elevation data and Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global elevation data (GDEM). This is a characteristic attempt to generate a DEM of any part of Antarctica by fusing multiple elevation datasets, which is essential to model the ice elevation change and address the ice mass balance. We analyzed a suite of interpolation techniques for constructing a DEM from GLAS, RAMP and ASTER DEM-based point elevation datasets, in order to determine the level of confidence with which the interpolation techniques can generate a better interpolated continuous surface, and eventually improve the elevation accuracy of DEM from synergistically fused RAMP, GLAS and ASTER point elevation datasets. The DEM presented in this work has a vertical accuracy (≈ 23 m) better than RAMP DEM (≈ 57 m) and ASTER DEM (≈ 64 m) individually. The RAMP DEM and ASTER DEM elevations were corrected using differential GPS elevations as ground reference data, and the accuracy obtained after fusing multitemporal datasets is found to be improved than that of existing DEMs constructed by using RAMP or ASTER alone. This is our second attempt of fusing multitemporal, multisensory and multisource elevation data to generate a DEM of Antarctica, in order to address the ice elevation change and address the ice mass balance. Our approach focuses on the strengths of each elevation data source to produce an accurate elevation model.

Dam-breach analysis and flood-inundation mapping for selected dams in Oklahoma City, Oklahoma, and near Atoka, Oklahoma

USGS Publications Warehouse

Shivers, Molly J.; Smith, S. Jerrod; Grout, Trevor S.; Lewis, Jason M.

2015-01-01

Digital-elevation models, field survey measurements, hydraulic data, and hydrologic data (U.S. Geological Survey streamflow-gaging stations North Canadian River below Lake Overholser near Oklahoma City, Okla. [07241000], and North Canadian River at Britton Road at Oklahoma City, Okla. [07241520]), were used as inputs for the one-dimensional dynamic (unsteady-flow) models using Hydrologic Engineering Centers River Analysis System (HEC–RAS) software. The modeled flood elevations were exported to a geographic information system to produce flood-inundation maps. Water-surface profiles were developed for a 75-percent probable maximum flood dam-breach scenario and a sunny-day dam-breach scenario, as well as for maximum flood-inundation elevations and flood-wave arrival times at selected bridge crossings. Points of interest such as community-services offices, recreational areas, water-treatment plants, and wastewater-treatment plants were identified on the flood-inundation maps.

Estimating Coastal Digital Elevation Model (DEM) Uncertainty

NASA Astrophysics Data System (ADS)

Amante, C.; Mesick, S.

2017-12-01

Integrated bathymetric-topographic digital elevation models (DEMs) are representations of the Earth's solid surface and are fundamental to the modeling of coastal processes, including tsunami, storm surge, and sea-level rise inundation. Deviations in elevation values from the actual seabed or land surface constitute errors in DEMs, which originate from numerous sources, including: (i) the source elevation measurements (e.g., multibeam sonar, lidar), (ii) the interpolative gridding technique (e.g., spline, kriging) used to estimate elevations in areas unconstrained by source measurements, and (iii) the datum transformation used to convert bathymetric and topographic data to common vertical reference systems. The magnitude and spatial distribution of the errors from these sources are typically unknown, and the lack of knowledge regarding these errors represents the vertical uncertainty in the DEM. The National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Information (NCEI) has developed DEMs for more than 200 coastal communities. This study presents a methodology developed at NOAA NCEI to derive accompanying uncertainty surfaces that estimate DEM errors at the individual cell-level. The development of high-resolution (1/9th arc-second), integrated bathymetric-topographic DEMs along the southwest coast of Florida serves as the case study for deriving uncertainty surfaces. The estimated uncertainty can then be propagated into the modeling of coastal processes that utilize DEMs. Incorporating the uncertainty produces more reliable modeling results, and in turn, better-informed coastal management decisions.

A hydroclimatological approach to predicting regional landslide probability using Landlab

NASA Astrophysics Data System (ADS)

Strauch, Ronda; Istanbulluoglu, Erkan; Nudurupati, Sai Siddhartha; Bandaragoda, Christina; Gasparini, Nicole M.; Tucker, Gregory E.

2018-02-01

We develop a hydroclimatological approach to the modeling of regional shallow landslide initiation that integrates spatial and temporal dimensions of parameter uncertainty to estimate an annual probability of landslide initiation based on Monte Carlo simulations. The physically based model couples the infinite-slope stability model with a steady-state subsurface flow representation and operates in a digital elevation model. Spatially distributed gridded data for soil properties and vegetation classification are used for parameter estimation of probability distributions that characterize model input uncertainty. Hydrologic forcing to the model is through annual maximum daily recharge to subsurface flow obtained from a macroscale hydrologic model. We demonstrate the model in a steep mountainous region in northern Washington, USA, over 2700 km2. The influence of soil depth on the probability of landslide initiation is investigated through comparisons among model output produced using three different soil depth scenarios reflecting the uncertainty of soil depth and its potential long-term variability. We found elevation-dependent patterns in probability of landslide initiation that showed the stabilizing effects of forests at low elevations, an increased landslide probability with forest decline at mid-elevations (1400 to 2400 m), and soil limitation and steep topographic controls at high alpine elevations and in post-glacial landscapes. These dominant controls manifest themselves in a bimodal distribution of spatial annual landslide probability. Model testing with limited observations revealed similarly moderate model confidence for the three hazard maps, suggesting suitable use as relative hazard products. The model is available as a component in Landlab, an open-source, Python-based landscape earth systems modeling environment, and is designed to be easily reproduced utilizing HydroShare cyberinfrastructure.

Modeling the impact of changing patient transportation systems on peri-operative process performance in a large hospital: insights from a computer simulation study.

PubMed

Segev, Danny; Levi, Retsef; Dunn, Peter F; Sandberg, Warren S

2012-06-01

Transportation of patients is a key hospital operational activity. During a large construction project, our patient admission and prep area will relocate from immediately adjacent to the operating room suite to another floor of a different building. Transportation will require extra distance and elevator trips to deliver patients and recycle transporters (specifically: personnel who transport patients). Management intuition suggested that starting all 52 first cases simultaneously would require many of the 18 available elevators. To test this, we developed a data-driven simulation tool to allow decision makers to simultaneously address planning and evaluation questions about patient transportation. We coded a stochastic simulation tool for a generalized model treating all factors contributing to the process as JAVA objects. The model includes elevator steps, explicitly accounting for transporter speed and distance to be covered. We used the model for sensitivity analyses of the number of dedicated elevators, dedicated transporters, transporter speed and the planned process start time on lateness of OR starts and the number of cases with serious delays (i.e., more than 15 min). Allocating two of the 18 elevators and 7 transporters reduced lateness and the number of cases with serious delays. Additional elevators and/or transporters yielded little additional benefit. If the admission process produced ready-for-transport patients 20 min earlier, almost all delays would be eliminated. Modeling results contradicted clinical managers' intuition that starting all first cases on time requires many dedicated elevators. This is explained by the principle of decreasing marginal returns for increasing capacity when there are other limiting constraints in the system.

Optimized Global Digital Elevation Data Records (Invited)

NASA Astrophysics Data System (ADS)

Kobrick, M.; Farr, T.; Crippen, R. E.

2009-12-01

The Shuttle Radar Topography Mission (SRTM) used radar interferometry to map the Earth's topography between ±60° latitude - representing 80% of the land surface. The resulting digital elevation models bettered existing topographic data sets (including restricted military data) in accuracy, areal coverage and uniformity by several orders of magnitude, and the resulting data records have found broad application in most of the geosciences, military operations, even Google Earth. Despite their popularity the SRTM data have several limitations, including lack of coverage in polar regions and occasional small voids, or areas of no data in regions of high slope of low radar backscatter. Fortunately additional data sets have become available that, although lacking SRTM's data quality, are sufficient to mitigate many of these limitations. Primary among these is the Global Digital Elevation Model (GDEM) produced from ASTER stereo pairs. The MEaSUREs program is sponsoring an effort to merge these sets to produce and distribute an improved collection of data records that will optimize the topographic data, as well as make available additional non-topographic data products from the SRTM mission. There are four main areas of effort: (1) A systematic program to combine SRTM elevation data with those from other sensors, principally GDEM but also including SPOT stereo, the USGS’s National Elevation Data Set and others, to fill voids in the DEMs according to a prioritized plan, as well as extend the coverage beyond the current 60° latitude limit. (2) Combine the topographic data records with ICESat laser altimeter topography profiles to produce and distribute data records with enhanced ground control. (3) Document the existing SRTM radar image and ancillary data records, as well as generate image mosaics at multiple scales and distribute them via the world wide web. (4) Generate, document and distribute a standard and representative set of SRTM raw radar echo data, along with the appropriate ancillary tracking and pointing data necessary to process the echoes into DEMS using improved algorithms or

Orthographic Stereo Correlator on the Terrain Model for Apollo Metric Images

NASA Technical Reports Server (NTRS)

Kim, Taemin; Husmann, Kyle; Moratto, Zachary; Nefian, Ara V.

2011-01-01

A stereo correlation method on the object domain is proposed to generate the accurate and dense Digital Elevation Models (DEMs) from lunar orbital imagery. The NASA Ames Intelligent Robotics Group (IRG) aims to produce high-quality terrain reconstructions of the Moon from Apollo Metric Camera (AMC) data. In particular, IRG makes use of a stereo vision process, the Ames Stereo Pipeline (ASP), to automatically generate DEMs from consecutive AMC image pairs. Given camera parameters of an image pair from bundle adjustment in ASP, a correlation window is defined on the terrain with the predefined surface normal of a post rather than image domain. The squared error of back-projected images on the local terrain is minimized with respect to the post elevation. This single dimensional optimization is solved efficiently and improves the accuracy of the elevation estimate.

Action of acetylstrophanthidin on experimental myocardial infarction.

NASA Technical Reports Server (NTRS)

Nola, G. T.; Pope, S. E.; Harrison, D. C.

1972-01-01

An experimental animal model with acute myocardial infarction of a size insufficient to produce profound heart failure or shock was used to study the effects of acute infarction on digitalis tolerance and the hemodynamic changes produced by moderate and large doses of acetylstrophanthidin. With acute myocardial infarction, digitalis toxic arrhythmias could be precipitated with significantly lower doses of digitalis than in animals without myocardial infarction. There was no precise correlation between the size of infarction and the toxic dose of glycoside. Coronary artery ligation produced a stable but relatively depressed circulatory state, as evidenced by lowered cardiac output and stroke volume and elevated systemic vascular resistance and left atrial mean pressure. When digitalis was infused, the following significant changes were observed at nontoxic doses: (1) elevation of aortic and left ventricular pressures; (2) further decline in cardiac output; and (3) decreased left atrial mean pressure.

Surface mass balance model evaluation from satellite and airborne lidar mapping

NASA Astrophysics Data System (ADS)

Sutterley, T. C.; Velicogna, I.; Fettweis, X.; van den Broeke, M. R.

2016-12-01

We present estimates of Greenland Ice Sheet (GrIS) surface elevation change from a novel combination of satellite and airborne laser altimetry measurements. Our method combines measurements from the Airborne Topographic Mapper (ATM), the Land, Vegetation and Ice Sensor (LVIS) and ICESat-1 to generate elevation change rates at high spatial resolution. This method allows to extend the records of each instrument, increases the overall spatial coverage compared to a single instrument, and produces high-quality, coherent maps of surface elevation change. In addition by combining the lidar datasets, we are able to investigate seasonal and interannual surface elevation change for years where Spring and Fall Operation IceBridge campaigns are available. We validate our method by comparing with the standard NSIDC elevation change product calculated using overlapping Level-1B ATM data. We use the altimetry-derived mass changes to evaluate the uncertainty in surface mass balance, particularly in the runoff component, from two Regional Climate Models (RCM's), the Regional Atmospheric Climate Model (RACMO) and the Modéle Atmosphérique Régional (MAR), and one Global Climate Model (GCM), MERRA2/GEOS-5. We investigate locations with low ice sheet surface velocities that are within the estimated ablation zones of each regional climate model. We find that the surface mass balance outputs from RACMO and MAR show good correspondence with mass changes derived from surface elevation changes over long periods. At two sites in Northeast Greenland (NEGIS), the MAR model has better correspondence with the altimetry estimate. We find that the differences at these locations are primarily due to the characterization of meltwater refreeze within the ice sheet.

Alpine Fault, New Zealand, SRTM Shaded Relief and Colored Height

NASA Image and Video Library

2005-01-06

The Alpine fault runs parallel to, and just inland of, much of the west coast of New Zealand South Island. This view was created from the near-global digital elevation model produced by NASA Shuttle Radar Topography Mission SRTM.

Integrating statistical and process-based models to produce probabilistic landslide hazard at regional scale

NASA Astrophysics Data System (ADS)

Strauch, R. L.; Istanbulluoglu, E.

2017-12-01

We develop a landslide hazard modeling approach that integrates a data-driven statistical model and a probabilistic process-based shallow landslide model for mapping probability of landslide initiation, transport, and deposition at regional scales. The empirical model integrates the influence of seven site attribute (SA) classes: elevation, slope, curvature, aspect, land use-land cover, lithology, and topographic wetness index, on over 1,600 observed landslides using a frequency ratio (FR) approach. A susceptibility index is calculated by adding FRs for each SA on a grid-cell basis. Using landslide observations we relate susceptibility index to an empirically-derived probability of landslide impact. This probability is combined with results from a physically-based model to produce an integrated probabilistic map. Slope was key in landslide initiation while deposition was linked to lithology and elevation. Vegetation transition from forest to alpine vegetation and barren land cover with lower root cohesion leads to higher frequency of initiation. Aspect effects are likely linked to differences in root cohesion and moisture controlled by solar insulation and snow. We demonstrate the model in the North Cascades of Washington, USA and identify locations of high and low probability of landslide impacts that can be used by land managers in their design, planning, and maintenance.

Echolocation with bat buzz emissions: model and biomimetic sonar for elevation estimation.

PubMed

Kuc, Roman

2012-01-01

Just prior to capture the Buzz II emissions of some mouth-emitting bats, such as Eptesicus fuscus, are observed to exhibit spectra having multiple peaks. This paper proposes an echolocation strategy that uses such spectra with energy concentrated in specific frequency bands for determining target elevation. A biomimetic sonar was implemented to produce a tri-modal spectrum by driving a speaker with a signal rich in harmonics. The emission magnitudes at these harmonic frequencies measured as a function of elevation in the zero-azimuth plane form distinct beams. A template was formed from the ratio of the first harmonic and fundamental magnitudes to determine elevation. The elevation estimator exhibited a sub-degree accuracy (SD = 0.4° over a 20° interval centered at the elevation at which these two beams intersect in the zero-azimuth plane. Spectral cues from -40° to +10° elevation allow a qualitative non-linear control of sonar orientation to drive the target to the beam-intersection point where quantitative elevation estimates are available. © 2012 Acoustical Society of America.

Tsunami Inundation, North of Phuket, ThailandASTER Images and SRTM Elevation Model

NASA Image and Video Library

2005-01-14

This image from NASA Terra spacecraft shows the Indian Ocean coastline north of Phuket, Thailand is a major tourist destination that was in the path of the tsunami produced by a giant offshore earthquake on December 26, 2004.

The effect of intraocular gas and fluid volumes on intraocular pressure.

PubMed

Simone, J N; Whitacre, M M

1990-02-01

Large increases in the intraocular pressure (IOP) of postoperative gas-containing eyes may require the removal of gas or fluid to reduce the IOP to the normal range. Application of the ideal gas law to Friedenwald's equation provides a mathematical model of the relationship between IOP, intraocular gas and fluid volumes, and the coefficient of scleral rigidity. This mathematic model shows that removal of a given volume of gas or fluid produces an identical decrease in IOP and that the more gas an eye contains, the greater the volume reduction necessary to reduce the pressure. Application of the model shows that the effective coefficient of scleral rigidity is low (mean K, 0.0021) in eyes with elevated IOP that have undergone vitrectomy and retinal cryopexy and very low (mean K, 0.0013) in eyes with elevated IOP that have undergone placement of a scleral buckle and band. By using the appropriate mean coefficient of rigidity, the volume of material to be aspirated to produce a given decrease in IOP can be predicted with clinically useful accuracy.

Channel mapping river miles 29–62 of the Colorado River in Grand Canyon National Park, Arizona, May 2009

USGS Publications Warehouse

Kaplinski, Matt; Hazel, Joseph E.; Grams, Paul E.; Kohl, Keith; Buscombe, Daniel D.; Tusso, Robert B.

2017-03-23

Bathymetric, topographic, and grain-size data were collected in May 2009 along a 33-mi reach of the Colorado River in Grand Canyon National Park, Arizona. The study reach is located from river miles 29 to 62 at the confluence of the Colorado and Little Colorado Rivers. Channel bathymetry was mapped using multibeam and singlebeam echosounders, subaerial topography was mapped using ground-based total-stations, and bed-sediment grain-size data were collected using an underwater digital microscope system. These data were combined to produce digital elevation models, spatially variable estimates of digital elevation model uncertainty, georeferenced grain-size data, and bed-sediment distribution maps. This project is a component of a larger effort to monitor the status and trends of sand storage along the Colorado River in Grand Canyon National Park. This report documents the survey methods and post-processing procedures, digital elevation model production and uncertainty assessment, and procedures for bed-sediment classification, and presents the datasets resulting from this study.

Elliptical storm cell modeling of digital radar data

NASA Technical Reports Server (NTRS)

Altman, F. J.

1972-01-01

A model for spatial distributions of reflectivity in storm cells was fitted to digital radar data. The data were taken with a modified WSR-57 weather radar with 2.6-km resolution. The data consisted of modified B-scan records on magnetic tape of storm cells tracked at 0 deg elevation for several hours. The MIT L-band radar with 0.8-km resolution produced cross-section data on several cells at 1/2 deg elevation intervals. The model developed uses ellipses for contours of constant effective-reflectivity factor Z with constant orientation and eccentricity within a horizontal cell cross section at a given time and elevation. The centers of the ellipses are assumed to be uniformly spaced on a straight line, with areas linearly related to log Z. All cross sections are similar at different heights (except for cell tops, bottoms, and splitting cells), especially for the highest reflectivities; wind shear causes some translation and rotation between levels. Goodness-of-fit measures and parameters of interest for 204 ellipses are considered.

Countrywide digital elevation models for the Islamic Republic of Mauritania—SRTM and ASTER (phase V, deliverable 65): Chapter F in Second projet de renforcement institutionnel du secteur minier de la République Islamique de Mauritanie (PRISM-II)

USGS Publications Warehouse

Lee, Gregory K.

2015-01-01

A digital elevation model (DEM) of the entire country of the Islamic Republic of Mauritania was produced using Shuttle Radar Topography Mission (SRTM) data as required for deliverable 65 of the contract. In addition, because of significant recent advancements of availability, seamlessness, and validity of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) global elevation data, the U.S. Geological Survey (USGS) extended its efforts to include a higher resolution countrywide ASTER DEM as value added to the required Deliverable 63, which was limited to five areas within the country. Both SRTM and ASTER countrywide DEMs have been provided in ERDAS Imagine (.img) format that is also directly compatible with ESRI ArcMap, ArcGIS Explorer, and other GIS applications.

Exposure of pregnant rats to diverse chemicals during pregnancy causes elevated blood pressure in offspring

EPA Science Inventory

Objective: Global undernutrition, low protein diet or dexamethasone treatment during pregnancy has been demonstrated in animal models to result in adverse health effects including hypertension and insulln resistance in adult offspring. Most protocols that produce these effects ca...

Probability of detecting atrazine/desethyl-atrazine and elevated concentrations of nitrate plus nitrate as nitrogen in ground water in the Idaho part of the western Snake River Plain

USGS Publications Warehouse

Donato, Mary M.

2000-01-01

As ground water continues to provide an ever-growing proportion of Idaho?s drinking water, concerns about the quality of that resource are increasing. Pesticides (most commonly, atrazine/desethyl-atrazine, hereafter referred to as atrazine) and nitrite plus nitrate as nitrogen (hereafter referred to as nitrate) have been detected in many aquifers in the State. To provide a sound hydrogeologic basis for atrazine and nitrate management in southern Idaho—the largest region of land and water use in the State—the U.S. Geological Survey produced maps showing the probability of detecting these contaminants in ground water in the upper Snake River Basin (published in a 1998 report) and the western Snake River Plain (published in this report). The atrazine probability map for the western Snake River Plain was constructed by overlaying ground-water quality data with hydrogeologic and anthropogenic data in a geographic information system (GIS). A data set was produced in which each well had corresponding information on land use, geology, precipitation, soil characteristics, regional depth to ground water, well depth, water level, and atrazine use. These data were analyzed by logistic regression using a statistical software package. Several preliminary multivariate models were developed and those that best predicted the detection of atrazine were selected. The multivariate models then were entered into a GIS and the probability maps were produced. Land use, precipitation, soil hydrologic group, and well depth were significantly correlated with atrazine detections in the western Snake River Plain. These variables also were important in the 1998 probability study of the upper Snake River Basin. The effectiveness of the probability models for atrazine might be improved if more detailed data were available for atrazine application. A preliminary atrazine probability map for the entire Snake River Plain in Idaho, based on a data set representing that region, also was produced. In areas where this map overlaps the 1998 map of the upper Snake River Basin, the two maps show broadly similar probabilities of detecting atrazine. Logistic regression also was used to develop a preliminary statistical model that predicts the probability of detecting elevated nitrate in the western Snake River Plain. A nitrate probability map was produced from this model. Results showed that elevated nitrate concentrations were correlated with land use, soil organic content, well depth, and water level. Detailed information on nitrate input, specifically fertilizer application, might have improved the effectiveness of this model.

A Seamless, High-Resolution, Coastal Digital Elevation Model (DEM) for Southern California

USGS Publications Warehouse

Barnard, Patrick L.; Hoover, Daniel

2010-01-01

A seamless, 3-meter digital elevation model (DEM) was constructed for the entire Southern California coastal zone, extending 473 km from Point Conception to the Mexican border. The goal was to integrate the most recent, high-resolution datasets available (for example, Light Detection and Ranging (Lidar) topography, multibeam and single beam sonar bathymetry, and Interferometric Synthetic Aperture Radar (IfSAR) topography) into a continuous surface from at least the 20-m isobath to the 20-m elevation contour. This dataset was produced to provide critical boundary conditions (bathymetry and topography) for a modeling effort designed to predict the impacts of severe winter storms on the Southern California coast (Barnard and others, 2009). The hazards model, run in real-time or with prescribed scenarios, incorporates atmospheric information (wind and pressure fields) with a suite of state-of-the-art physical process models (tide, surge, and wave) to enable detailed prediction of water levels, run-up, wave heights, and currents. Research-grade predictions of coastal flooding, inundation, erosion, and cliff failure are also included. The DEM was constructed to define the general shape of nearshore, beach and cliff surfaces as accurately as possible, with less emphasis on the detailed variations in elevation inland of the coast and on bathymetry inside harbors. As a result this DEM should not be used for navigation purposes.

Evaluating coastal landscape response to sea-level rise in the northeastern United States: approach and methods

USGS Publications Warehouse

Lentz, Erika E.; Stippa, Sawyer R.; Thieler, E. Robert; Plant, Nathaniel G.; Gesch, Dean B.; Horton, Radley M.

2014-02-13

The U.S. Geological Survey is examining effects of future sea-level rise on the coastal landscape from Maine to Virginia by producing spatially explicit, probabilistic predictions using sea-level projections, vertical land movement rates (due to isostacy), elevation data, and land-cover data. Sea-level-rise scenarios used as model inputs are generated by using multiple sources of information, including Coupled Model Intercomparison Project Phase 5 models following representative concentration pathways 4.5 and 8.5 in the Intergovernmental Panel on Climate Change Fifth Assessment Report. A Bayesian network is used to develop a predictive coastal response model that integrates the sea-level, elevation, and land-cover data with assigned probabilities that account for interactions with coastal geomorphology as well as the corresponding ecological and societal systems it supports. The effects of sea-level rise are presented as (1) level of landscape submergence and (2) coastal response type characterized as either static (that is, inundation) or dynamic (that is, landform or landscape change). Results are produced at a spatial scale of 30 meters for four decades (the 2020s, 2030s, 2050s, and 2080s). The probabilistic predictions can be applied to landscape management decisions based on sea-level-rise effects as well as on assessments of the prediction uncertainty and need for improved data or fundamental understanding. This report describes the methods used to produce predictions, including information on input datasets; the modeling approach; model outputs; data-quality-control procedures; and information on how to access the data and metadata online.

Evaluating Coastal Landscape Response to Sea-Level Rise in the Northeastern United States - Approach and Methods

NASA Technical Reports Server (NTRS)

Lentz, Erika E.; Stippa, Sawyer R.; Thieler, E. Robert; Plant, Nathaniel G.; Gesch, Dean B.; Horton, Radley M.

2015-01-01

The U.S. Geological Survey is examining effects of future sea-level rise on the coastal landscape from Maine to Virginia by producing spatially explicit, probabilistic predictions using sea-level projections, vertical land movement rates (due to isostacy), elevation data, and land-cover data. Sea-level-rise scenarios used as model inputs are generated by using multiple sources of information, including Coupled Model Intercomparison Project Phase 5 models following representative concentration pathways 4.5 and 8.5 in the Intergovernmental Panel on Climate Change Fifth Assessment Report. A Bayesian network is used to develop a predictive coastal response model that integrates the sea-level, elevation, and land-cover data with assigned probabilities that account for interactions with coastal geomorphology as well as the corresponding ecological and societal systems it supports. The effects of sea-level rise are presented as (1) level of landscape submergence and (2) coastal response type characterized as either static (that is, inundation) or dynamic (that is, landform or landscape change). Results are produced at a spatial scale of 30 meters for four decades (the 2020s, 2030s, 2050s, and 2080s). The probabilistic predictions can be applied to landscape management decisions based on sea-level-rise effects as well as on assessments of the prediction uncertainty and need for improved data or fundamental understanding. This report describes the methods used to produce predictions, including information on input datasets; the modeling approach; model outputs; data-quality-control procedures; and information on how to access the data and metadata online.

Effects of Reduced Terrestrial LiDAR Point Density on High-Resolution Grain Crop Surface Models in Precision Agriculture

PubMed Central

Hämmerle, Martin; Höfle, Bernhard

2014-01-01

3D geodata play an increasingly important role in precision agriculture, e.g., for modeling in-field variations of grain crop features such as height or biomass. A common data capturing method is LiDAR, which often requires expensive equipment and produces large datasets. This study contributes to the improvement of 3D geodata capturing efficiency by assessing the effect of reduced scanning resolution on crop surface models (CSMs). The analysis is based on high-end LiDAR point clouds of grain crop fields of different varieties (rye and wheat) and nitrogen fertilization stages (100%, 50%, 10%). Lower scanning resolutions are simulated by keeping every n-th laser beam with increasing step widths n. For each iteration step, high-resolution CSMs (0.01 m2 cells) are derived and assessed regarding their coverage relative to a seamless CSM derived from the original point cloud, standard deviation of elevation and mean elevation. Reducing the resolution to, e.g., 25% still leads to a coverage of >90% and a mean CSM elevation of >96% of measured crop height. CSM types (maximum elevation or 90th-percentile elevation) react differently to reduced scanning resolutions in different crops (variety, density). The results can help to assess the trade-off between CSM quality and minimum requirements regarding equipment and capturing set-up. PMID:25521383

Daily air temperature interpolated at high spatial resolution over a large mountainous region

USGS Publications Warehouse

Dodson, R.; Marks, D.

1997-01-01

Two methods are investigated for interpolating daily minimum and maximum air temperatures (Tmin and Tmax) at a 1 km spatial resolution over a large mountainous region (830 000 km2) in the U.S. Pacific Northwest. The methods were selected because of their ability to (1) account for the effect of elevation on temperature and (2) efficiently handle large volumes of data. The first method, the neutral stability algorithm (NSA), used the hydrostatic and potential temperature equations to convert measured temperatures and elevations to sea-level potential temperatures. The potential temperatures were spatially interpolated using an inverse-squared-distance algorithm and then mapped to the elevation surface of a digital elevation model (DEM). The second method, linear lapse rate adjustment (LLRA), involved the same basic procedure as the NSA, but used a constant linear lapse rate instead of the potential temperature equation. Cross-validation analyses were performed using the NSA and LLRA methods to interpolate Tmin and Tmax each day for the 1990 water year, and the methods were evaluated based on mean annual interpolation error (IE). The NSA method showed considerable bias for sites associated with vertical extrapolation. A correction based on climate station/grid cell elevation differences was developed and found to successfully remove the bias. The LLRA method was tested using 3 lapse rates, none of which produced a serious extrapolation bias. The bias-adjusted NSA and the 3 LLRA methods produced almost identical levels of accuracy (mean absolute errors between 1.2 and 1.3??C), and produced very similar temperature surfaces based on image difference statistics. In terms of accuracy, speed, and ease of implementation, LLRA was chosen as the best of the methods tested.

Accuracy of a high-resolution lidar terrain model under a conifer forest canopy

Treesearch

S.E. Reutebuch; R.J. McGaughey; H.-E. Andersen; W.W. Carson

2003-01-01

Airborne laser scanning systems can provide terrain elevation data for open areas with a vertical accuracy of 15 cm. In this study, a high-resolution digital terrain model (DTM) was produced from high-density lidar data. Vegetation in the 500-ha mountainous study area varied from bare ground to dense 70-year-old conifer forest. Conventional ground survey methods were...

[Modeling of experimental hypertension by chronic salt loading combined with a low-protein diet in Wistar rats].

PubMed

Strekalova, V V; Khachirov, D G; Dedenkov, A N; Suvorov, Iu I; Shvatsabaia, I K

1989-01-01

Combination of chronic salt loading with protein-poor diet produces experimental hypertension with natrium consumption near to physiological. The present model is characterized, compared to the existing one, by stage development, moderate arterial blood pressure elevation and absence of "salt toxicosis" and may be thus considered more adequate for experimental investigation of primary arterial hypertension pathophysiology.

Evaluation of the Global Multi-Resolution Terrain Elevation Data 2010 (GMTED2010) using ICESat geodetic control

USGS Publications Warehouse

Carabajal, C.C.; Harding, D.J.; Boy, J.-P.; Danielson, Jeffrey J.; Gesch, D.B.; Suchdeo, V.P.

2011-01-01

Supported by NASA's Earth Surface and Interior (ESI) Program, we are producing a global set of Ground Control Points (GCPs) derived from the Ice, Cloud and land Elevation Satellite (ICESat) altimetry data. From February of 2003, to October of 2009, ICESat obtained nearly global measurements of land topography (?? 86?? latitudes) with unprecedented accuracy, sampling the Earth's surface at discrete ???50 m diameter laser footprints spaced 170 m along the altimetry profiles. We apply stringent editing to select the highest quality elevations, and use these GCPs to characterize and quantify spatially varying elevation biases in Digital Elevation Models (DEMs). In this paper, we present an evaluation of the soon to be released Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010). Elevation biases and error statistics have been analyzed as a function of land cover and relief. The GMTED2010 products are a large improvement over previous sources of elevation data at comparable resolutions. RMSEs for all products and terrain conditions are below 7 m and typically are about 4 m. The GMTED2010 products are biased upward with respect to the ICESat GCPs on average by approximately 3 m. ?? 2011 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).

Evaluation of the Global Multi-Resolution Terrain Elevation Data 2010 (GMTED2010) Using ICESat Geodetic Control

NASA Technical Reports Server (NTRS)

Carabajal, Claudia C.; Harding, David J.; Boy, Jean-Paul; Danielson, Jeffrey J.; Gesch, Dean B.; Suchdeo, Vijay P.

2011-01-01

Supported by NASA's Earth Surface and Interior (ESI) Program, we are producing a global set of Ground Control Points (GCPs) derived from the Ice, Cloud and land Elevation Satellite (ICESat) altimetry data. From February of 2003, to October of 2009, ICESat obtained nearly global measurements of land topography (+/- 86deg latitudes) with unprecedented accuracy, sampling the Earth's surface at discrete approx.50 m diameter laser footprints spaced 170 m along the altimetry profiles. We apply stringent editing to select the highest quality elevations, and use these GCPs to characterize and quantify spatially varying elevation biases in Digital Elevation Models (DEMs). In this paper, we present an evaluation of the soon to be released Global Multi-resolution Terrain Elevation Data 2010 (GMTED2010). Elevation biases and error statistics have been analyzed as a function of land cover and relief. The GMTED2010 products are a large improvement over previous sources of elevation data at comparable resolutions. RMSEs for all products and terrain conditions are below 7 m and typically are about 4 m. The GMTED2010 products are biased upward with respect to the ICESat GCPs on average by approximately 3 m.

High-Speed Wind-Tunnel Tests of a Model of the Lockheed YP-80A Airplane Including Correlation with Flight Tests and Tests of Dive-Recovery Flaps

NASA Technical Reports Server (NTRS)

Cleary, Joseph W.; Gray, Lyle J.

1947-01-01

This report contains the results of tests of a 1/3-scale model of the Lockheed YP-90A "Shooting Star" airplane and a comparison of drag, maximum lift coefficient, and elevator angle required for level flight as measured in the wind tunnel and in flight. Included in the report are the general aerodynamic characteristics of the model and of two types of dive-recovery flaps, one at several positions along the chord on the lower surface of the wing and the other on the lower surface of the fuselage. The results show good agreement between the flight and wind-tunnel measurements at all Mach numbers. The results indicate that the YP-80A is controllable in pitch by the elevators to a Mach number of at least 0.85. The fuselage dive-recovery flaps are effective for producing a climbing moment and increasing the drag at Mach numbers up to at least 0.8. The wing dive-recovery flaps are most effective for producing a climbing moment at 0.75 Mach number. At 0.85 Mach number, their effectiveness is approximately 50 percent of the maximum. The optimum position for the wing dive-recovery flaps to produce a climbing moment is at approximately 35 percent of the chord.

Nonresidential Crime Attractors and Generators Elevate Perceived Neighborhood Crime and Incivilities

ERIC Educational Resources Information Center

McCord, Eric S.; Ratcliffe, Jerry H.; Garcia, R. Marie; Taylor, Ralph B.

2007-01-01

Recent studies have produced conflicting findings about the impacts of local nonresidential land uses on perceived incivilities. This study advances work in this area by developing a land-use perspective theoretically grounded in Brantingham and Brantingham's geometry of crime model in environmental criminology. That focus directs attention to…

THE EFFECTS OF HABITAT RESOLUTION ON MODELS OF AVIAN DIVERSITY AND DISTRIBUTIONS: A COMPARISON OF TWO LAND-COVER CLASSIFICATIONS

EPA Science Inventory

The quantification of pattern is a key element of landscape analyses. One aspect of this quantification of particular importance to landscape ecologists regards the classification of continuous variables to produce categorical variables such as land-cover type or elevation strat...

A System of Conservative Regridding for Ice-Atmosphere Coupling in a General Circulation Model (GCM)

NASA Technical Reports Server (NTRS)

Fischer, R.; Nowicki, S.; Kelley, M.; Schmidt, G. A.

2014-01-01

The method of elevation classes, in which the ice surface model is run at multiple elevations within each grid cell, has proven to be a useful way for a low-resolution atmosphere inside a general circulation model (GCM) to produce high-resolution downscaled surface mass balance fields for use in one-way studies coupling atmospheres and ice flow models. Past uses of elevation classes have failed to conserve mass and energy because the transformation used to regrid to the atmosphere was inconsistent with the transformation used to downscale to the ice model. This would cause problems for two-way coupling. A strategy that resolves this conservation issue has been designed and is presented here. The approach identifies three grids between which data must be regridded and five transformations between those grids required by a typical coupled atmosphere-ice flow model. This paper develops a theoretical framework for the problem and shows how each of these transformations may be achieved in a consistent, conservative manner. These transformations are implemented in Glint2, a library used to couple atmosphere models with ice models. Source code and documentation are available for download. Confounding real-world issues are discussed, including the use of projections for ice modeling, how to handle dynamically changing ice geometry, and modifications required for finite element ice models.

Evaluation of wintertime precipitation forecasts over the Australian Snowy Mountains

NASA Astrophysics Data System (ADS)

Huang, Yi; Chubb, Thomas; Sarmadi, Fahimeh; Siems, Steven T.; Manton, Michael J.; Franklin, Charmaine N.; Ebert, Elizabeth

2018-07-01

This study evaluates the Australian Community Climate and Earth-System Simulator (ACCESS) Numerical Weather Prediction system in forecasting precipitation across the Australian Snowy Mountains for two cool seasons. Metrics based on seasonal accumulated and daily precipitation show that the model is able to reproduce the observed domain-mean accumulated precipitation reasonably well (with a slight overestimation), but this is, in part, due to a compensation of various errors. Both the frequency and intensity of the heavy precipitation days (domain-mean daily precipitation >5 mm day-1) are overrepresented, particularly over the complex terrain and high-elevation areas, whereas the frequency of the very light precipitation days (domain-mean daily precipitation <1 mm day-1) is underestimated, primarily over lower-elevation areas both upwind and downwind of the mountains. Most of the precipitation is forecasted by the grid-scale precipitation scheme, with appreciable snowfalls predicted over the high elevations. The model also demonstrates appreciable skill in reproducing the synoptic regimes. The proportion of the forecast precipitation for each regime is comparable to the observations, although the orographic enhancement over the western slopes of the mountains is more pronounced in the forecasts, particularly for the wetter regimes. An examination on the effect of the lower-atmosphere stability suggests that most of the precipitation (50-70% over the high elevations) is produced under the "unblocked" condition, which is diagnosed 31% of the time. The remainder is produced under the "blocked" condition. Combined with a case study, potential sources of error associated with the forecast precipitation biases are also discussed.

The Shuttle Radar Topography Mission: A Global DEM

NASA Technical Reports Server (NTRS)

Farr, Tom G.; Kobrick, Mike

2000-01-01

Digital topographic data are critical for a variety of civilian, commercial, and military applications. Scientists use Digital Elevation Models (DEM) to map drainage patterns and ecosystems, and to monitor land surface changes over time. The mountain-building effects of tectonics and the climatic effects of erosion can also be modeled with DEW The data's military applications include mission planning and rehearsal, modeling and simulation. Commercial applications include determining locations for cellular phone towers, enhanced ground proximity warning systems for aircraft, and improved maps for backpackers. The Shuttle Radar Topography Mission (SRTM) (Fig. 1), is a cooperative project between NASA and the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense. The mission is designed to use a single-pass radar interferometer to produce a digital elevation model of the Earth's land surface between about 60 degrees north and south latitude. The DEM will have 30 m pixel spacing and about 15 m vertical errors.

Earth elevation map production and high resolution sensing camera imaging analysis

NASA Astrophysics Data System (ADS)

Yang, Xiubin; Jin, Guang; Jiang, Li; Dai, Lu; Xu, Kai

2010-11-01

The Earth's digital elevation which impacts space camera imaging has prepared and imaging has analysed. Based on matching error that TDI CCD integral series request of the speed of image motion, statistical experimental methods-Monte Carlo method is used to calculate the distribution histogram of Earth's elevation in image motion compensated model which includes satellite attitude changes, orbital angular rate changes, latitude, longitude and the orbital inclination changes. And then, elevation information of the earth's surface from SRTM is read. Earth elevation map which produced for aerospace electronic cameras is compressed and spliced. It can get elevation data from flash according to the shooting point of latitude and longitude. If elevation data between two data, the ways of searching data uses linear interpolation. Linear interpolation can better meet the rugged mountains and hills changing requests. At last, the deviant framework and camera controller are used to test the character of deviant angle errors, TDI CCD camera simulation system with the material point corresponding to imaging point model is used to analyze the imaging's MTF and mutual correlation similarity measure, simulation system use adding cumulation which TDI CCD imaging exceeded the corresponding pixel horizontal and vertical offset to simulate camera imaging when stability of satellite attitude changes. This process is practicality. It can effectively control the camera memory space, and meet a very good precision TDI CCD camera in the request matches the speed of image motion and imaging.

Modeling global Hammond landform regions from 250-m elevation data

USGS Publications Warehouse

Karagulle, Deniz; Frye, Charlie; Sayre, Roger; Breyer, Sean P.; Aniello, Peter; Vaughan, Randy; Wright, Dawn J.

2017-01-01

In 1964, E.H. Hammond proposed criteria for classifying and mapping physiographic regions of the United States. Hammond produced a map entitled “Classes of Land Surface Form in the Forty-Eight States, USA”, which is regarded as a pioneering and rigorous treatment of regional physiography. Several researchers automated Hammond?s model in GIS. However, these were local or regional in application, and resulted in inadequate characterization of tablelands. We used a global 250 m DEM to produce a new characterization of global Hammond landform regions. The improved algorithm we developed for the regional landform modeling: (1) incorporated a profile parameter for the delineation of tablelands; (2) accommodated negative elevation data values; (3) allowed neighborhood analysis window (NAW) size to vary between parameters; (4) more accurately bounded plains regions; and (5) mapped landform regions as opposed to discrete landform features. The new global Hammond landform regions product builds on an existing global Hammond landform features product developed by the U.S. Geological Survey, which, while globally comprehensive, did not include tablelands, used a fixed NAW size, and essentially classified pixels rather than regions. Our algorithm also permits the disaggregation of “mixed” Hammond types (e.g. plains with high mountains) into their component parts.

Martian particle size based on thermal inertia corrected for elevation-dependent atmospheric properties

NASA Technical Reports Server (NTRS)

Bridges, N. T.

1993-01-01

Thermal inertia is commonly used to derive physical properties of the Martian surface. If the surface is composed of loosely consolidated grains, then the thermal conductivity derived from the inertia can theoretically be used to compute the particle size. However, one persistent difficulty associated with the interpretation of thermal inertia and the derivation of particle size from it has been the degree to which atmospheric properties affect both the radiation balance at the surface and the gas conductivity. These factors vary with atmospheric pressure so that derived thermal inertias and particle sizes are a function of elevation. By utilizing currently available thermal models and laboratory information, a fine component thermal inertia map was convolved with digital topography to produce particle size maps of the Martian surface corrected for these elevation-dependent effects. Such an approach is especially applicable for the highest elevations on Mars, where atmospheric back radiation and gas conductivity are low.

High Resolution Topography of Polar Regions from Commercial Satellite Imagery, Petascale Computing and Open Source Software

NASA Astrophysics Data System (ADS)

Morin, Paul; Porter, Claire; Cloutier, Michael; Howat, Ian; Noh, Myoung-Jong; Willis, Michael; Kramer, WIlliam; Bauer, Greg; Bates, Brian; Williamson, Cathleen

2017-04-01

Surface topography is among the most fundamental data sets for geosciences, essential for disciplines ranging from glaciology to geodynamics. Two new projects are using sub-meter, commercial imagery licensed by the National Geospatial-Intelligence Agency and open source photogrammetry software to produce a time-tagged 2m posting elevation model of the Arctic and an 8m posting reference elevation model for the Antarctic. When complete, this publically available data will be at higher resolution than any elevation models that cover the entirety of the Western United States. These two polar projects are made possible due to three equally important factors: 1) open-source photogrammetry software, 2) petascale computing, and 3) sub-meter imagery licensed to the United States Government. Our talk will detail the technical challenges of using automated photogrammetry software; the rapid workflow evolution to allow DEM production; the task of deploying the workflow on one of the world's largest supercomputers; the trials of moving massive amounts of data, and the management strategies the team needed to solve in order to meet deadlines. Finally, we will discuss the implications of this type of collaboration for future multi-team use of leadership-class systems such as Blue Waters, and for further elevation mapping.

Midpoint attractors and species richness: Modelling the interaction between environmental drivers and geometric constraints.

PubMed

Colwell, Robert K; Gotelli, Nicholas J; Ashton, Louise A; Beck, Jan; Brehm, Gunnar; Fayle, Tom M; Fiedler, Konrad; Forister, Matthew L; Kessler, Michael; Kitching, Roger L; Klimes, Petr; Kluge, Jürgen; Longino, John T; Maunsell, Sarah C; McCain, Christy M; Moses, Jimmy; Noben, Sarah; Sam, Katerina; Sam, Legi; Shapiro, Arthur M; Wang, Xiangping; Novotny, Vojtech

2016-09-01

We introduce a novel framework for conceptualising, quantifying and unifying discordant patterns of species richness along geographical gradients. While not itself explicitly mechanistic, this approach offers a path towards understanding mechanisms. In this study, we focused on the diverse patterns of species richness on mountainsides. We conjectured that elevational range midpoints of species may be drawn towards a single midpoint attractor - a unimodal gradient of environmental favourability. The midpoint attractor interacts with geometric constraints imposed by sea level and the mountaintop to produce taxon-specific patterns of species richness. We developed a Bayesian simulation model to estimate the location and strength of the midpoint attractor from species occurrence data sampled along mountainsides. We also constructed midpoint predictor models to test whether environmental variables could directly account for the observed patterns of species range midpoints. We challenged these models with 16 elevational data sets, comprising 4500 species of insects, vertebrates and plants. The midpoint predictor models generally failed to predict the pattern of species midpoints. In contrast, the midpoint attractor model closely reproduced empirical spatial patterns of species richness and range midpoints. Gradients of environmental favourability, subject to geometric constraints, may parsimoniously account for elevational and other patterns of species richness. © 2016 John Wiley & Sons Ltd/CNRS.

Inevitable end-of-21st-century trends toward earlier surface runoff timing in California's Sierra Nevada Mountains

NASA Astrophysics Data System (ADS)

Schwartz, M. A.; Hall, A. D.; Sun, F.; Walton, D.; Berg, N.

2015-12-01

Hybrid dynamical-statistical downscaling is used to produce surface runoff timing projections for California's Sierra Nevada, a high-elevation mountain range with significant seasonal snow cover. First, future climate change projections (RCP8.5 forcing scenario, 2081-2100 period) from five CMIP5 global climate models (GCMs) are dynamically downscaled. These projections reveal that future warming leads to a shift toward earlier snowmelt and surface runoff timing throughout the Sierra Nevada region. Relationships between warming and surface runoff timing from the dynamical simulations are used to build a simple statistical model that mimics the dynamical model's projected surface runoff timing changes given GCM input or other statistically-downscaled input. This statistical model can be used to produce surface runoff timing projections for other GCMs, periods, and forcing scenarios to quantify ensemble-mean changes, uncertainty due to intermodel variability and consequences stemming from choice of forcing scenario. For all CMIP5 GCMs and forcing scenarios, significant trends toward earlier surface runoff timing occur at elevations below 2500m. Thus, we conclude that trends toward earlier surface runoff timing by the end-of-the-21st century are inevitable. The changes to surface runoff timing diagnosed in this study have implications for many dimensions of climate change, including impacts on surface hydrology, water resources, and ecosystems.

Spin-tunnel investigation of a 1/15-scale model of an Australian trainer airplane

NASA Technical Reports Server (NTRS)

Bowman, James S., Jr.; Whipple, Raymond D.; White, William L.

1987-01-01

An investigation was conducted in the Langley Spin Tunnel of the spin and spin-recovery characteristics of a 1/15-scale model of an Australian trainer airplane. The invesigation included erect and inverted spins; configuration variables such as a long tail, fuselage strakes, 20 deg. elevator cutouts, and rudder modifications; and determination of the parachute size for emergency spin recovery. Also included in the investigation were wing leading-edge modifications to evaluate Reynolds number effects. Results indicate that the basic configuration will spin erect at an angle of attack of about 63 deg. at about 2 to 2.3 seconds per turn. Recovery from this spin was unsatisfactory by rudder reversal or by rudder reversal and ailerons deflected to full with the spin. The elevators had a pronounced effect on the recovery characteristics. The elevators-down position was very adverse to recoveries, whereas the elevators-up position provided favorable recovery effects. Moving the vertical tail aft (producing a long tail configuration) improved the spin characteristics, but the recoveries were still considered marginal. An extension to the basic rudder chord and length made a significant improvement in the spin and recovery characteristics. Satisfactory recoveries were obtained by deflecting the rudder to full against the spin and the elevators and ailerons to neutral.

A New Era in Geodesy and Cartography: Implications for Landing Site Operations

NASA Technical Reports Server (NTRS)

Duxbury, T. C.

2001-01-01

The Mars Global Surveyor (MGS) Mars Orbiter Laser Altimeter (MOLA) global dataset has ushered in a new era for Mars local and global geodesy and cartography. These data include the global digital terrain model (Digital Terrain Model (DTM) radii), the global digital elevation model (Digital Elevation Model (DEM) elevation with respect to the geoid), and the higher spatial resolution individual MOLA ground tracks. Currently there are about 500,000,000 MOLA points and this number continues to grow as MOLA continues successful operations in orbit about Mars, the combined processing of radiometric X-band Doppler and ranging tracking of MGS together with millions of MOLA orbital crossover points has produced global geodetic and cartographic control having a spatial (latitude/longitude) accuracy of a few meters and a topographic accuracy of less than 1 meter. This means that the position of an individual MOLA point with respect to the center-of-mass of Mars is know to an absolute accuracy of a few meters. The positional accuracy of this point in inertial space over time is controlled by the spin rate uncertainty of Mars which is less than 1 km over 10 years that will be improved significantly with the next landed mission.

Summary of results of January climate simulations with the GISS coarse-mesh model

NASA Technical Reports Server (NTRS)

Spar, J.; Cohen, C.; Wu, P.

1981-01-01

The large scale climates generated by extended runs of the model are relatively independent of the initial atmospheric conditions, if the first few months of each simulation are discarded. The perpetual January simulations with a specified SST field produced excessive snow accumulation over the continents of the Northern Hemisphere. Mass exchanges between the cold (warm) continents and the warm (cold) adjacent oceans produced significant surface pressure changes over the oceans as well as over the land. The effect of terrain and terrain elevation on the amount of precipitation was examined. The evaporation of continental moisture was calculated to cause large increases in precipitation over the continents.

Digital Elevation Models

USGS Publications Warehouse

,

1993-01-01

The Earth Science Information Center (ESIC) distributes digital cartographic/geographic data files produced by the U.S. Geological Survey (USGS) as part of the National Mapping Program. Digital cartographic data files may be grouped into four basic types. The first of these, called a Digital Line Graph (DLG), is the line map information in digital form. These data files include information on base data categories, such as transportation, hypsography, hydrography, and boundaries. The second type, called a Digital Elevation Model (DEM), consists of a sampled array of elevations for a number of ground positions at regularly spaced intervals. The third type is Land Use and Land Cover digital data which provides information on nine major classes of land use such as urban, agricultural, or forest as well as associated map data such as political units and Federal land ownership. The fourth type, the Geographic Names Information System, provides primary information for all known places, features, and areas in the United States identified by a proper name.

MAGSAT anomaly field data of the crustal properties of Australia

NASA Technical Reports Server (NTRS)

1983-01-01

Progress is reported in producing maps of Australia showing; crustal magnetic anomalies at constant elevation; bulk surface magnetization; and the geomagnetic field intensity, inclination and declination for the Australian region from global models of the geomagnetic field derived from MAGSAT data. The development of a data base management system is also considered.

Using satellite remote sensing to model and map the distribution of Bicknell's thrush (Catharus bicknelli) in the White Mountains of New Hampshire

NASA Astrophysics Data System (ADS)

Hale, Stephen Roy

Landsat-7 Enhanced Thematic Mapper satellite imagery was used to model Bicknell's Thrush (Catharus bicknelli) distribution in the White Mountains of New Hampshire. The proof-of-concept was established for using satellite imagery in species-habitat modeling, where for the first time imagery spectral features were used to estimate a species-habitat model variable. The model predicted rising probabilities of thrush presence with decreasing dominant vegetation height, increasing elevation, and decreasing distance to nearest Fir Sapling cover type. To solve the model at all locations required regressor estimates at every pixel, which were not available for the dominant vegetation height and elevation variables. Topographically normalized imagery features Normalized Difference Vegetation Index and Band 1 (blue) were used to estimate dominant vegetation height using multiple linear regression; and a Digital Elevation Model was used to estimate elevation. Distance to nearest Fir Sapling cover type was obtained for each pixel from a land cover map specifically constructed for this project. The Bicknell's Thrush habitat model was derived using logistic regression, which produced the probability of detecting a singing male based on the pattern of model covariates. Model validation using Bicknell's Thrush data not used in model calibration, revealed that the model accurately estimated thrush presence at probabilities ranging from 0 to <0.40 and from 0.50 to <0.60. Probabilities from 0.40 to <0.50 and greater than 0.60 significantly underestimated and overestimated presence, respectively. Applying the model to the study area illuminated an important implication for Bicknell's Thrush conservation. The model predicted increasing numbers of presences and increasing relative density with rising elevation, with which exists a concomitant decrease in land area. Greater land area of lower density habitats may account for more total individuals and reproductive output than higher density less abundant land area. Efforts to conserve areas of highest individual density under the assumption that density reflects habitat quality could target the smallest fraction of the total population.

Brugada syndrome and ischemia-induced ST-segment elevation. Similarities and differences#

PubMed Central

Di Diego, José M.; Fish, Jeffrey M.; Antzelevitch, Charles

2006-01-01

Introduction ST-Segment elevation is a common electrocardiogram (ECG) manifestation of acute transmural myocardial ischemia in leads facing the injury. Acute myocardial ischemia involving the right-ventricular (RV) outflow tract is known to induce a Brugada-like ECG. In this paper, we examined the electrophysiological bases for the similarities between the ECG characteristics of the Brugada syndrome model induced by terfenadine (5 μmol/L) and the ECG manifestations of the acute transmural no-flow ischemia model. Methods For both experimental simulations, we used isolated arterially perfused canine RV wedge preparations to record transmembrane action potentials (AP) from endocardium and epicardium together with a transmural pseudo-ECG (ECG); basic cycle length = 400 to 2000 ms. Results In the presence of a prominent Ito-mediated AP notch, no-flow ischemia causes true ST-segment elevation because of selective depression and loss of the AP dome at some epicardial sites. In the absence of a prominent AP notch, ischemia ultimately produces an apparent ST-segment elevation, which is secondary to a prolongation of the R wave caused by marked transmural conduction delays. Similarly, in the Brugada syndrome model generated in preparations displaying a large epicardial Ito, ST-segment elevation was due to loss of the epicardial AP dome at some sites but not at others. Transmural conduction delay giving the appearance of ST-segment elevation is also observed in the Brugada model in preparations exhibiting smaller AP notch. In both models, propagation of the dome from the site at which it is maintained to a site at which it is lost may result in closely coupled phase 2 reentrant extrasystoles. Conclusion Our results suggest that Ito can modulate the electrocardiographic manifestation of acute ischemia as well as that of the Brugada syndrome, and that both clinical entities are the result of a similar electrophysiological substrate. PMID:16226068

The application of geostationary propagation models to non-geostationary propagation measurements

NASA Astrophysics Data System (ADS)

Haddock, Paul Christopher

Atmospheric attenuation becomes evident above 10 GHz due to the absorption of microwave energy from the molecular motion of the atmospheric constituents. Atmospheric effects on satellite communications systems operating at frequencies greater than 10 GHz become more pronounced. Most geostationary (GEO) climate models, which predict the fading statistics for earth-space telecommunications, have satellite elevation angle as one of the input parameters. There has been an interest in the industry to apply the propagation models developed for the GEO satellites to the non-geostationary (NGO) satellite case. With the NGO satellites, the elevation angle to the satellite is time-variable, and as a result the earth-space propagation medium is time varying. We can calculate the expected probability that a satellite, in a given orbit, will be found at a given elevation angle as a percentage of the year based on the satellite orbital elements, the minimum elevation angle allowed in the constellation operation plan, and the constellation configuration. From this calculation, we can develop an empirical fit to a given probability density function (PDF) to account for the distribution of elevation angles. This PDF serves as a weighting function for the elevation input into the GEO climate model to produce the overall fading statistics for the NGO case. In this research, a Ka-band total power radiometer was developed to measure the down-dwelling incoherent radiant electromagnetic energy from the atmosphere. This whole sky sampling radiometer collected 1 year of radiometric measurements. These observations occurred at varying elevation and azimuthal angles, in close proximity to a weak water vapor absorption line. By referencing the output power of the radiometer to known radiometric emissions and by performing frequent internal calibrations, the developed radiometer provided long term highly accurate and stable low-level derived attenuation measurements. By correlating the 1 year of atmospheric measurements to the modified GEO climate model, the hypothesis is tested. That by application of the proper elevation weighting factors, the GEO model is applicable to the NGO case, where the time-varying angle changes are occurring on a short-time period. Finally, we look at the joint statistics of multiple link failures. Using the 1 year of observed attenuations for multiple sky sections, we show that for a given sky section what the probability is that its attenuation level will be equaled or exceeded for each of the remaining sky sections.

Species data: National inventory of range maps and distribution models

USGS Publications Warehouse

Gergely, Kevin J.; McKerrow, Alexa

2013-01-01

The Gap Analysis Program (GAP) produces data and tools that help meet critical national challenges such as biodiversity conservation, renewable energy development, climate change adaptation, and infrastructure investment. The GAP species data includes vertebrate range maps and distribution models for the continental United States, as well as Alaska, Hawaii, Puerto Rico, and U.S. Virgin Islands. The vertebrate species include amphibians, birds, mammals, and reptiles. Furthermore, data used to create the distribution models (for example, percent canopy cover, elevation, and so forth) also are available.

Characterization of the ZDSD Rat: A Translational Model for the Study of Metabolic Syndrome and Type 2 Diabetes

PubMed Central

Peterson, Richard G.; de Winter, Willem; Huebert, Norman; Hansen, Michael K.

2015-01-01

Metabolic syndrome and T2D produce significant health and economic issues. Many available animal models have monogenic leptin pathway mutations that are absent in the human population. Development of the ZDSD rat model was undertaken to produce a model that expresses polygenic obesity and diabetes with an intact leptin pathway. A lean ZDF rat with the propensity for beta-cell failure was crossed with a polygenetically obese Crl:CD (SD) rat. Offspring were selectively inbred for obesity and diabetes for >30 generations. In the current study, ZDSD rats were followed for 6 months; routine clinical metabolic endpoints were included throughout the study. In the prediabetic metabolic syndrome phase, ZDSD rats exhibited obesity with increased body fat, hyperglycemia, insulin resistance, dyslipidemia, glucose intolerance, and elevated HbA1c. As disease progressed to overt diabetes, ZDSD rats demonstrated elevated glucose levels, abnormal oral glucose tolerance, increases in HbA1c levels, reductions in body weight, increased insulin resistance with decreasing insulin levels, and dyslipidemia. The ZDSD rat develops prediabetic metabolic syndrome and T2D in a manner that mirrors the development of metabolic syndrome and T2D in humans. ZDSD rats will provide a novel, translational animal model for the study of human metabolic diseases and for the development of new therapies. PMID:25961053

NASADEM Global Elevation Model of Earth: Methods for the Refinement and Merger of SRTM and ASTER GDEM

NASA Astrophysics Data System (ADS)

Crippen, R. E.; Buckley, S.; Agram, P. S.; Belz, J. E.; Gurrola, E. M.; Hensley, S.; Kobrick, M.; Lavalle, M.; Martin, J. M.; Neumann, M.; Nguyen, Q.; Rosen, P. A.; Shimada, J.; Simard, M.; Tung, W.

2016-12-01

NASADEM is a near-global elevation model that is being produced primarily by completely reprocessing the Shuttle Radar Topography Mission (SRTM) radar data and then merging it with refined ASTER GDEM elevations. The new and improved SRTM elevations in NASADEM result from better vertical control of each SRTM data swath via reference to ICESat elevations and from SRTM void reductions using advanced interferometric unwrapping algorithms. Errors in SRTM (due to incorrect interferometric unwrapping) are rare but can be found and removed via a detector that relies upon pattern analysis within synergistic comparisons of SRTM and GDEM. Remnant voids in SRTM are filled primarily by GDEM3, but with removal of GDEM glitches that are mostly related to clouds. GDEM glitch removal uses a measure of curvature and then spatial filtering to detect, isolate, and delete anomalous spikes and pits that are uncharacteristic of natural topography. Water masking uses the original SRTM Water Body Dataset (SWBD), but with errors corrected via a new ASTER Water Body Database. The improved SRTM, GDEM, and water body databases will be made available individually in addition to our merged product, which is particularly important for the SRTM dataset, which stands as a February 2000 baseline for many topographic change studies. New and forthcoming freely available elevation data (at reduced resolutions) from the ALOS PRISM World 3D and TanDEM-X projects will contribute to the critical but not yet reached goal of a complete, high-quality elevation model of Earth, and they are expected to provide additional validation for NASADEM. Indeed, cross validation among all of these datasets is a vital part of reaching that goal. The value of elevation data is difficult to overstate. These data are used in nearly all types of geophysical study conducted at or near Earth's surface.

Topography- and nightlight-based national flood risk assessment in Canada

NASA Astrophysics Data System (ADS)

Elshorbagy, Amin; Bharath, Raja; Lakhanpal, Anchit; Ceola, Serena; Montanari, Alberto; Lindenschmidt, Karl-Erich

2017-04-01

In Canada, flood analysis and water resource management, in general, are tasks conducted at the provincial level; therefore, unified national-scale approaches to water-related problems are uncommon. In this study, a national-scale flood risk assessment approach is proposed and developed. The study focuses on using global and national datasets available with various resolutions to create flood risk maps. First, a flood hazard map of Canada is developed using topography-based parameters derived from digital elevation models, namely, elevation above nearest drainage (EAND) and distance from nearest drainage (DFND). This flood hazard mapping method is tested on a smaller area around the city of Calgary, Alberta, against a flood inundation map produced by the city using hydraulic modelling. Second, a flood exposure map of Canada is developed using a land-use map and the satellite-based nightlight luminosity data as two exposure parameters. Third, an economic flood risk map is produced, and subsequently overlaid with population density information to produce a socioeconomic flood risk map for Canada. All three maps of hazard, exposure, and risk are classified into five classes, ranging from very low to severe. A simple way to include flood protection measures in hazard estimation is also demonstrated using the example of the city of Winnipeg, Manitoba. This could be done for the entire country if information on flood protection across Canada were available. The evaluation of the flood hazard map shows that the topography-based method adopted in this study is both practical and reliable for large-scale analysis. Sensitivity analysis regarding the resolution of the digital elevation model is needed to identify the resolution that is fine enough for reliable hazard mapping, but coarse enough for computational tractability. The nightlight data are found to be useful for exposure and risk mapping in Canada; however, uncertainty analysis should be conducted to investigate the effect of the overglow phenomenon on flood risk mapping.

Development of status epilepticus, sustained calcium elevations and neuronal injury in a rat survival model of lethal paraoxon intoxication

PubMed Central

Deshpande, Laxmikant S.; Carter, Dawn S.; Phillips, Kristin F.; Blair, Robert E.; DeLorenzo, Robert J.

2014-01-01

Paraoxon (POX) is an active metabolite of organophosphate (OP) pesticide parathion that has been weaponized and used against civilian populations. Exposure to POX produces high mortality. OP poisoning is often associated with chronic neurological disorders. In this study, we optimize a rat survival model of lethal POX exposures in order to mimic both acute and long-term effects of POX intoxication. Male Sprague-Dawley rats injected with POX (4 mg/kg, ice-cold PBS, s.c.) produced a rapid cholinergic crisis that evolved into status epilepticus (SE) and death within 6–8 min. The EEG profile for POX induced SE was characterized and showed clinical and electrographic seizures with 7–10 Hz spike activity. Treatment of 100% lethal POX intoxication with an optimized three drug regimen (atropine, 2 mg/kg, i.p., 2-PAM, 25 mg/kg, i.m. and diazepam, 5 mg/kg, i.p.) promptly stopped SE and reduced acute mortality to 12% and chronic mortality to 18%. This model is ideally suited to test effective countermeasures against lethal POX exposure. Animals that survived the POX SE manifested prolonged elevations in hippocampal [Ca2+]i (Ca2+ plateau) and significant multifocal neuronal injury. POX SE induced Ca2+ plateau had its origin in Ca2+ release from intracellular Ca2+ stores since inhibition of ryanodine/ IP3 receptor lowered elevated Ca2+ levels post SE. POX SE induced neuronal injury and alterations in Ca2+ dynamics may underlie some of the long term morbidity associated with OP toxicity. PMID:24785379

Histamine H3R receptor activation in the dorsal striatum triggers stereotypies in a mouse model of tic disorders

PubMed Central

Rapanelli, M; Frick, L; Pogorelov, V; Ohtsu, H; Bito, H; Pittenger, C

2017-01-01

Tic disorders affect ~5% of the population and are frequently comorbid with obsessive-compulsive disorder, autism, and attention deficit disorder. Histamine dysregulation has been identified as a rare genetic cause of tic disorders; mice with a knockout of the histidine decarboxylase (Hdc) gene represent a promising pathophysiologically grounded model. How alterations in the histamine system lead to tics and other neuropsychiatric pathology, however, remains unclear. We found elevated expression of the histamine H3 receptor in the striatum of Hdc knockout mice. The H3 receptor has significant basal activity even in the absence of ligand and thus may modulate striatal function in this knockout model. We probed H3R function using specific agonists. The H3 agonists R-aminomethylhistamine (RAMH) and immepip produced behavioral stereotypies in KO mice, but not in controls. H3 agonist treatment elevated intra-striatal dopamine in KO mice, but not in controls. This was associated with elevations in phosphorylation of rpS6, a sensitive marker of neural activity, in the dorsal striatum. We used a novel chemogenetic strategy to demonstrate that this dorsal striatal activity is necessary and sufficient for the development of stereotypy: when RAMH-activated cells in the dorsal striatum were chemogenetically activated (in the absence of RAMH), stereotypy was recapitulated in KO animals, and when they were silenced the ability of RAMH to produce stereotypy was blocked. These results identify the H3 receptor in the dorsal striatum as a contributor to repetitive behavioral pathology. PMID:28117842

Ammonia-induced brain swelling and neurotoxicity in an organotypic slice model

PubMed Central

Back, Adam; Tupper, Kelsey Y.; Bai, Tao; Chiranand, Paulpoj; Goldenberg, Fernando D.; Frank, Jeffrey I.; Brorson, James R.

2013-01-01

Objectives Acute liver failure produces cerebral dysfunction and edema, mediated in part by elevated ammonia concentrations, often leading to coma and death. The pathophysiology of cerebral edema in acute liver failure is incompletely understood. In vitro models of the cerebral effects of acute liver failure have predominately consisted of dissociated astrocyte cultures or acute brain slices. We describe a stable long-term culture model incorporating both neural and glial elements in a three-dimensional tissue structure offering significant advantages to the study of astrocytic-neuronal interactions in the pathophysiology of cerebral edema and dysfunction in acute liver failure. Methods We utilized chronic organotypic slice cultures from mouse forebrain, applying ammonium acetate in iso-osmolar fashion for 72 hours. Imaging of slice thickness to assess for tissue swelling was accomplished in living slices with optical coherence tomography, and confocal microscopy of fluorescence immunochemical and histochemical staining served to assess astrocyte and neuronal numbers, morphology, and volume in the fixed brain slices. Results Ammonia exposure at 1–10 mM produced swelling of immunochemically-identified astrocytes, and at 10 mM resulted in macroscopic tissue swelling, with slice thickness increasing by about 30%. Astrocytes were unchanged in number. In contrast, 10 mM ammonia treatment severely disrupted neuronal morphology and reduced neuronal survival at 72 hours by one-half. Discussion Elevated ammonia produces astrocytic swelling, tissue swelling, and neuronal toxicity in cerebral tissues. Ammonia-treated organotypic brain slice cultures provide an in vitro model of cerebral effects of conditions relevant to acute liver failure, applicable to pathophysiological investigations. PMID:22196764

A combined surface/volume scattering retracking algorithm for ice sheet satellite altimetry

NASA Technical Reports Server (NTRS)

Davis, Curt H.

1992-01-01

An algorithm that is based upon a combined surface-volume scattering model is developed. It can be used to retrack individual altimeter waveforms over ice sheets. An iterative least-squares procedure is used to fit the combined model to the return waveforms. The retracking algorithm comprises two distinct sections. The first generates initial model parameter estimates from a filtered altimeter waveform. The second uses the initial estimates, the theoretical model, and the waveform data to generate corrected parameter estimates. This retracking algorithm can be used to assess the accuracy of elevations produced from current retracking algorithms when subsurface volume scattering is present. This is extremely important so that repeated altimeter elevation measurements can be used to accurately detect changes in the mass balance of the ice sheets. By analyzing the distribution of the model parameters over large portions of the ice sheet, regional and seasonal variations in the near-surface properties of the snowpack can be quantified.

Satellite techniques for determining the geopotential for sea-surface elevations

NASA Technical Reports Server (NTRS)

Pisacane, V. L.

1984-01-01

Spaceborne altimetry with measurement accuracies of a few centimeters which has the potential to determine sea surface elevations necessary to compute accurate three-dimensonal geostrophic currents from traditional hydrographic observation is discussed. The limitation in this approach is the uncertainties in knowledge of the global and ocean geopotentials which produce satellite and height uncertainties about an order of magnitude larger than the goal of about 10 cm. The quantative effects of geopotential uncertainties on processing altimetry data are described. Potential near term improvements, not requiring additional spacecraft, are discussed. Even though there is substantial improvements at the longer wavelengths, the oceanographic goal will be achieved. The geopotential research mission (GRM) is described which should produce goepotential models that are capable of defining the ocean geid to 10 cm and near-Earth satellite position. The state of the art and the potential of spaceborne gravimetry is described as an alternative approach to improve our knowledge of the geopotential.

Preparation of the Digital Elevation Model for Orthophoto CR Production

NASA Astrophysics Data System (ADS)

Švec, Z.; Pavelka, K.

2016-06-01

The Orthophoto CR is produced in co-operation with the Land Survey Office and the Military Geographical and Hydrometeorological Office. The product serves to ensure a defence of the state, integrated crisis management, civilian tasks in support of the state administration and the local self-government of the Czech Republic as well. It covers the whole area of the Republic and for ensuring its up-to-datedness is reproduced in the biennial period. As the project is countrywide, it keeps the project within the same parameters in urban and rural areas as well. Due to economic reasons it cańt be produced as a true ortophoto because it requires large side and forward overlaps of the aerial photographs and a preparation of the digital surface model instead of the digital terrain model. Use of DTM without some objects of DSM for orthogonalization purposes cause undesirable image deformations in the Orthophoto. There are a few data sets available for forming a suitable elevation model. The principal source should represent DTMs made from data acquired by the airborne laser scanning of the entire area of the Czech Republic that was carried out in the years 2009-2013, the DMR4G in the grid form and the DMR5G in TIN form respectively. It can be replenished by some vector objects (bridges, dams, etc.) taken from the geographic base data of the Czech Republic or obtained by new stereo plotting. It has to be taken into account that the option of applying DSM made from image correlation is also available. The article focuses on the possibilities of DTM supplement for ortogonalization. It looks back to the recent transition from grid to hybrid elevation models, problems that occurred, its solution and getting some practical remarks. Afterwards it assesses the current state and deals with the options for updating the model. Some accuracy analysis are included.

Topogrid Derived 10 Meter Resolution Digital Elevation Model of the Shenandoah National Park and Surrounding Region, Virginia

USGS Publications Warehouse

Chirico, Peter G.; Tanner, Seth D.

2004-01-01

Explanation The purpose of developing a new 10m resolution DEM of the Shenandoah National Park Region was to more accurately depict geologic structure, surfical geology, and landforms of the Shenandoah National Park Region in preparation for automated landform classification. Previously, only a 30m resolution DEM was available through the National Elevation Dataset (NED). During production of the Shenandoah10m DEM of the Park the Geography Discipline of the USGS completed a revised 10m DEM to be included into the NED. However, different methodologies were used to produce the two similar DEMs. The ANUDEM algorithm was used to develop the Shenadoah DEM data. This algorithm allows for the inclusion of contours, streams, rivers, lake and water body polygons as well as spot height data to control the elevation model. A statistical analysis using over 800 National Geodetic Survey (NGS) first and second order vertical control points reveals that the Shenandoah10m DEM, produced as a part of the Appalachian Blue Ridge Landscape project, has a vertical accuracy of ?4.87 meters. The metadata for the 10m NED data reports a vertical accuracy of ?7m. A table listing the NGS control points, the elevation comparison, and the RMSE for the Shenandoah10m DEM is provided. The process of automated terrain classification involves developing statistical signatures from the DEM for each type of surficial deposit and landform type. The signature will be a measure of several characteristics derived from the elevation data including slope, aspect, planform curvature, and profile curvature. The quality of the DEM is of critical importance when extracting terrain signatures. The highest possible horizontal and vertical accuracy is required. The more accurate Shenandoah 10m DEM can now be analyzed and integrated with the geologic observations to yield statistical correlations between the two in the development of landform and surface geology mapping projects.

Selective activation of the K(+)(ATP) channel is a mechanism by which sudden death is produced by low-energy chest-wall impact (Commotio cordis).

PubMed

Link, M S; Wang, P J; VanderBrink, B A; Avelar, E; Pandian, N G; Maron, B J; Estes, N A

1999-07-27

Sudden death due to relatively innocent chest-wall impact has been described in young individuals (commotio cordis). In our previously reported swine model of commotio cordis, ventricular fibrillation (with T-wave strikes) and ST-segment elevation (with QRS strikes) were produced by 30-mph baseball impacts to the precordium. Because activation of the K(+)(ATP) channel has been implicated in the pathogenesis of ST elevation and ventricular fibrillation in myocardial ischemia, we hypothesized that this channel could be responsible for the electrophysiologic findings in our experimental model and in victims of commotio cordis. In the initial experiment, 6 juvenile swine were given 0.5 mg/kg IV glibenclamide, a selective inhibitor of the K(+)(ATP) channel, and chest impact was given on the QRS. The results of these strikes were compared with animals in which no glibenclamide was given. In the second phase, 20 swine were randomized to receive glibenclamide or a control vehicle (in a double-blind fashion), with chest impact delivered just before the T-wave peak. With QRS impacts, the maximal ST elevation was significantly less in those animals given glibenclamide (0.16+/-0.10 mV) than in controls (0.35+/-0.20 mV; P=0.004). With T-wave impacts, the animals that received glibenclamide had significantly fewer occurrences of ventricular fibrillation (1 episode in 27 impacts; 4%) than controls (6 episodes in 18 impacts; 33%; P=0.01). In this experimental model of commotio cordis, blockade of the K(+)(ATP) channel reduced the incidence of ventricular fibrillation and the magnitude of ST-segment elevation. Therefore, selective K(+)(ATP) channel activation may be a pivotal mechanism in sudden death resulting from low-energy chest-wall trauma in young people during sporting activities.

Analysis of lidar elevation data for improved identification and delineation of lands vulnerable to sea-level rise

USGS Publications Warehouse

Gesch, Dean B.

2009-01-01

The importance of sea-level rise in shaping coastal landscapes is well recognized within the earth science community, but as with many natural hazards, communicating the risks associated with sea-level rise remains a challenge. Topography is a key parameter that influences many of the processes involved in coastal change, and thus, up-to-date, high-resolution, high-accuracy elevation data are required to model the coastal environment. Maps of areas subject to potential inundation have great utility to planners and managers concerned with the effects of sea-level rise. However, most of the maps produced to date are simplistic representations derived from older, coarse elevation data. In the last several years, vast amounts of high quality elevation data derived from lidar have become available. Because of their high vertical accuracy and spatial resolution, these lidar data are an excellent source of up-to-date information from which to improve identification and delineation of vulnerable lands. Four elevation datasets of varying resolution and accuracy were processed to demonstrate that the improved quality of lidar data leads to more precise delineation of coastal lands vulnerable to inundation. A key component of the comparison was to calculate and account for the vertical uncertainty of the elevation datasets. This comparison shows that lidar allows for a much more detailed delineation of the potential inundation zone when compared to other types of elevation models. It also shows how the certainty of the delineation of lands vulnerable to a given sea-level rise scenario is much improved when derived from higher resolution lidar data.

Deriving flow directions for coarse-resolution (1-4 km) gridded hydrologic modeling

NASA Astrophysics Data System (ADS)

Reed, Seann M.

2003-09-01

The National Weather Service Hydrology Laboratory (NWS-HL) is currently testing a grid-based distributed hydrologic model at a resolution (4 km) commensurate with operational, radar-based precipitation products. To implement distributed routing algorithms in this framework, a flow direction must be assigned to each model cell. A new algorithm, referred to as cell outlet tracing with an area threshold (COTAT) has been developed to automatically, accurately, and efficiently assign flow directions to any coarse-resolution grid cells using information from any higher-resolution digital elevation model. Although similar to previously published algorithms, this approach offers some advantages. Use of an area threshold allows more control over the tendency for producing diagonal flow directions. Analyses of results at different output resolutions ranging from 300 m to 4000 m indicate that it is possible to choose an area threshold that will produce minimal differences in average network flow lengths across this range of scales. Flow direction grids at a 4 km resolution have been produced for the conterminous United States.

ICESat Lidar and Global Digital Elevation Models: Application to DESDynI

NASA Technical Reports Server (NTRS)

Carabajal, Claudia C.; Harding, David J.; Suchdeo, Vijay P.

2010-01-01

Geodetic control is extremely important in the production and quality control of topographic data sets, enabling elevation results to be referenced to an absolute vertical datum. Global topographic data with improved geodetic accuracy achieved using global Ground Control Point (GCP) databases enable more accurate characterization of land topography and its change related to solid Earth processes, natural hazards and climate change. The multiple-beam lidar instrument that will be part of the NASA Deformation, Ecosystem Structure and Dynamics of Ice (DESDynI) mission will provide a comprehensive, global data set that can be used for geodetic control purposes. Here we illustrate that potential using data acquired by NASA's Ice, Cloud and land Elevation Satellite (ICEsat) that has acquired single-beam, globally distributed laser altimeter profiles (+/-86deg) since February of 2003 [1, 2]. The profiles provide a consistently referenced elevation data set with unprecedented accuracy and quantified measurement errors that can be used to generate GCPs with sub-decimeter vertical accuracy and better than 10 m horizontal accuracy. Like the planned capability for DESDynI, ICESat records a waveform that is the elevation distribution of energy reflected within the laser footprint from vegetation, where present, and the ground where illuminated through gaps in any vegetation cover [3]. The waveform enables assessment of Digital Elevation Models (DEMs) with respect to the highest, centroid, and lowest elevations observed by ICESat and in some cases with respect to the ground identified beneath vegetation cover. Using the ICESat altimetry data we are developing a comprehensive database of consistent, global, geodetic ground control that will enhance the quality of a variety of regional to global DEMs. Here we illustrate the accuracy assessment of the Shuttle Radar Topography Mission (SRTM) DEM produced for Australia, documenting spatially varying elevation biases of several meters in magnitude.

User's Guide for the Agricultural Non-Point Source (AGNPS) Pollution Model Data Generator

USGS Publications Warehouse

Finn, Michael P.; Scheidt, Douglas J.; Jaromack, Gregory M.

2003-01-01

BACKGROUND Throughout this user guide, we refer to datasets that we used in conjunction with developing of this software for supporting cartographic research and producing the datasets to conduct research. However, this software can be used with these datasets or with more 'generic' versions of data of the appropriate type. For example, throughout the guide, we refer to national land cover data (NLCD) and digital elevation model (DEM) data from the U.S. Geological Survey (USGS) at a 30-m resolution, but any digital terrain model or land cover data at any appropriate resolution will produce results. Another key point to keep in mind is to use a consistent data resolution for all the datasets per model run. The U.S. Department of Agriculture (USDA) developed the Agricultural Nonpoint Source (AGNPS) pollution model of watershed hydrology in response to the complex problem of managing nonpoint sources of pollution. AGNPS simulates the behavior of runoff, sediment, and nutrient transport from watersheds that have agriculture as their prime use. The model operates on a cell basis and is a distributed parameter, event-based model. The model requires 22 input parameters. Output parameters are grouped primarily by hydrology, sediment, and chemical output (Young and others, 1995.) Elevation, land cover, and soil are the base data from which to extract the 22 input parameters required by the AGNPS. For automatic parameter extraction, follow the general process described in this guide of extraction from the geospatial data through the AGNPS Data Generator to generate input parameters required by the pollution model (Finn and others, 2002.)

Assessing uncertainty in SRTM elevations for global flood modelling

NASA Astrophysics Data System (ADS)

Hawker, L. P.; Rougier, J.; Neal, J. C.; Bates, P. D.

2017-12-01

The SRTM DEM is widely used as the topography input to flood models in data-sparse locations. Understanding spatial error in the SRTM product is crucial in constraining uncertainty about elevations and assessing the impact of these upon flood prediction. Assessment of SRTM error was carried out by Rodriguez et al (2006), but this did not explicitly quantify the spatial structure of vertical errors in the DEM, and nor did it distinguish between errors over different types of landscape. As a result, there is a lack of information about spatial structure of vertical errors of the SRTM in the landscape that matters most to flood models - the floodplain. Therefore, this study attempts this task by comparing SRTM, an error corrected SRTM product (The MERIT DEM of Yamazaki et al., 2017) and near truth LIDAR elevations for 3 deltaic floodplains (Mississippi, Po, Wax Lake) and a large lowland region (the Fens, UK). Using the error covariance function, calculated by comparing SRTM elevations to the near truth LIDAR, perturbations of the 90m SRTM DEM were generated, producing a catalogue of plausible DEMs. This allows modellers to simulate a suite of plausible DEMs at any aggregated block size above native SRTM resolution. Finally, the generated DEM's were input into a hydrodynamic model of the Mekong Delta, built using the LISFLOOD-FP hydrodynamic model, to assess how DEM error affects the hydrodynamics and inundation extent across the domain. The end product of this is an inundation map with the probability of each pixel being flooded based on the catalogue of DEMs. In a world of increasing computer power, but a lack of detailed datasets, this powerful approach can be used throughout natural hazard modelling to understand how errors in the SRTM DEM can impact the hazard assessment.

Effects of free-air CO2 and temperature enrichment on soybean growth and development

NASA Astrophysics Data System (ADS)

Ruiz Vera, U. M.; Bernacchi, C. J.

2012-12-01

According to the growing degree days approach, the progression of plant developmental stages requires certain accumulation of heat; therefore greenhouse gas-induced warming of the atmosphere could contribute to more rapid plant development. However, the influence of rising carbon dioxide concentration ([CO2]) on development of crops is uncertain, accelerating and other times delaying certain developmental stages. In soybean, the increase of [CO2] is shown to delay reproductive development, which is attributed to a higher investment of resources into extra nodes. The combined effects of elevated temperature and [CO2] can have significant changes in the progression through development that can influence on total grain production, carbon uptake, and susceptibility to early end-of-season frosts. We designed the Temperature by Free Air CO2 Enrichment (T-FACE) experiment to test over two growing seasons (2009 and 2011) and under field conditions the impact of increased temperature and/or [CO2] on soybean. The heated T-FACE subplots were situated in the larger FACE plots at 385 or 585 ppm of [CO2] and subjected to either ambient or heated (+~3.5°C) temperatures. The experiment is full factorial with ambient temperature and [CO2] (control), elevated temperature (eT), elevated [CO2] (eC) and combined (eT+eC) treatments. We hypothesized that soybean grown (1) under elevated [CO2] will produce more nodes than control, (2) under high temperature will produce nodes faster than control and (3) under both elevated temperature and [CO2] will produce more nodes in less time than control. For reproductive development, we hypothesized that (1) reproductive development will initiate simultaneously regardless of increased [CO2] or temperature because soybean reproduction is triggered by day length, (2) elevated temperature will accelerate the progression through key reproductive stages and (3) the delay in soybean reproductive development by elevated [CO2] will be ameliorated by the raise in temperature. Soybean developmental stages were recorded on six plants per subplot three times per week from emergence to senescence. In 2009, no temperature effect was detected on the vegetative development, but in 2011 temperature accelerates node formation. Elevated [CO2] was not significant on vegetative development, however plants under this effect produced more nodes than control. Reproductive development was delayed by elevated [CO2]. High temperature accelerated reproductive stages only in 2009, ameliorating the effect of elevated [CO2] in eT+eC. In 2011 elevated temperature delayed reproductive stages, a response that could be related with stress imposed by the weather conditions of that season. In the Midwest, the soybean cultivars generally mature before the first frost of the year avoiding seed damage. The delayed in soybean maturation by the increasing of [CO2] could potentially reduce yield; however the increase of temperature could diminish this risk by mitigating this delay. Alternatively, the more rapid progression through the reproductive stages could decrease the translocation of resources to pods, thereby negatively impacting yields. Using soybean as a model for leguminous C3 species suggested implications could arise for yield in crop plants and reproductive fitness in native vegetation.

Uncertainty of Wheat Water Use: Simulated Patterns and Sensitivity to Temperature and CO2

NASA Technical Reports Server (NTRS)

Cammarano, Davide; Roetter, Reimund P.; Asseng, Senthold; Ewert, Frank; Wallach, Daniel; Martre, Pierre; Hatfield, Jerry L.; Jones, James W.; Rosenzweig, Cynthia E.; Ruane, Alex C.;

Effects of forest cover, topography, and sampling extent on the measured density of shallow, translational landslides.

Treesearch

D.J. Miller; K.M. Burnett

2007-01-01

We use regionally available digital elevation models and land-cover data, calibrated with ground- and photo-based landslide inventories, to produce spatially distributed estimates of shallow, translational landslide density (number/unit area) for the Oregon Coast Range. We resolve relationships between landslide density and forest cover. We account for topographic...

Evidence for sustained elevation of IL-6 in the CNS as a key contributor of depressive-like phenotypes

PubMed Central

Sukoff Rizzo, S J; Neal, S J; Hughes, Z A; Beyna, M; Rosenzweig-Lipson, S; Moss, S J; Brandon, N J

2012-01-01

There is compelling clinical literature implicating a role for cytokines in the pathophysiology of major depressive disorder (MDD). Interleukin-6 (IL-6) and interleukin-1β (IL-1β) are pleiotropic inflammatory cytokines that have been reported to be elevated in patients with MDD. The present studies were undertaken to investigate the relationship between IL-6 and IL-1β in animal models of depressive-like behavior. Analysis of brain tissue homogenates in the cortex of rats subjected to chronic stress paradigms revealed elevated levels of IL-6 protein in the absence of elevations in IL-1β. Central administration of recombinant mouse IL-6 produced depressive-like phenotypes in mice, which were not accompanied by IL-1β-induced increases in the brain tissue or IL-1β-related sickness behavior typical of a general central nervous system inflammatory response. Systemic administration of fluoxetine in the presence of centrally administered IL-6 failed to produce the expected antidepressant-like response in mice relative to sham-infused controls. Further, administration of fluoxetine to mice with endogenous overexpression of brain IL-6 (MRL/MpJ-FasLPR/LPR (LPR mice)) failed to produce the expected antidepressant-like effect relative to fluoxetine-treated control mice (MRL/MpJ+/+). Interestingly, blockade of IL-6 trans-signaling by coadministration of a gp130/Fc monomer or an anti-mouse IL-6 antibody with IL-6 prevented the IL-6-induced increases in immobility time as well as attenuated IL-6-induced increases of protein in the cortex. Taken together, these data indicate that elevations in IL-6 may have a pathophysiological role underlying depression and more specifically resistance to current classes of antidepressant medications and suggest that modulation of the IL-6 signaling pathway may have therapeutic potential for treatment-resistant depression. PMID:23212583

Elevation correction factor for absolute pressure measurements

NASA Technical Reports Server (NTRS)

Panek, Joseph W.; Sorrells, Mark R.

1996-01-01

With the arrival of highly accurate multi-port pressure measurement systems, conditions that previously did not affect overall system accuracy must now be scrutinized closely. Errors caused by elevation differences between pressure sensing elements and model pressure taps can be quantified and corrected. With multi-port pressure measurement systems, the sensing elements are connected to pressure taps that may be many feet away. The measurement system may be at a different elevation than the pressure taps due to laboratory space or test article constraints. This difference produces a pressure gradient that is inversely proportional to height within the interface tube. The pressure at the bottom of the tube will be higher than the pressure at the top due to the weight of the tube's column of air. Tubes with higher pressures will exhibit larger absolute errors due to the higher air density. The above effect is well documented but has generally been taken into account with large elevations only. With error analysis techniques, the loss in accuracy from elevation can be easily quantified. Correction factors can be applied to maintain the high accuracies of new pressure measurement systems.

Digital Elevation Models of the Earth derived from space-based observations: Advances and potential for geomorphological studies

NASA Astrophysics Data System (ADS)

Mouratidis, Antonios

2013-04-01

Digital Elevation Models (DEMs) are an inherently interdisciplinary topic, both due to their production and validation methods, as well as their significance for numerous disciplines. The most utilized contemporary topographic datasets worldwide are those of global DEMs. Several space-based sources have been used for the production of (almost) global DEMs, namely satellite Synthetic Aperture Radar (SAR) Interferometry/InSAR, stereoscopy of multispectral satellite images and altimetry, producing several versions of autonomous or mixed products (i.e. SRTM, ACE, ASTER-GDEM). Complementary space-based observations, such as those of Global Navigation Satellite Systems (GNSS), are also used, mainly for validation purposes. The apparent positive impact of these elevation datasets so far has been consolidated by the plethora of related scientific, civil and military applications. Topography is a prominent element for almost all Earth sciences, but in Geomorphology it is even more fundamental. In geomorphological studies, elevation data and thus DEMs can be extensively used for the extraction of both qualitative and quantitative information, such as relief classification, determination of slope and slope orientation, delineation of drainage basins, extraction of drainage networks and much more. Global DEMs are constantly becoming finer, i.e. of higher spatial resolution and more "sensitive" to elevation changes, i.e. of higher vertical accuracy and these progresses are undoubtedly considered as a major breakthrough, each time a new improved global DEM is released. Nevertheless, for Geomorphology in particular, if not already there, we are close to the point in time, where the need for discrimination between DSM (Digital Surface Model) and DTM (Digital Terrain Model) is becoming critical; if the distinction between vegetation and man-made structures on one side (DSM), and actual terrain elevation on the other side (DTM) cannot be made, then, in many cases, any further increase of elevation accuracy in DEMs will have little impact on geomorphological studies. After shortly reviewing the evolution of satellite-based global DEMs, the purpose of this paper is to address their current limitations and challenges from the perspective of a geomorphologist. Subsequently, the implications for geomorphological studies are discussed, with respect to the expected near-future advances in the field, such as the TanDEM-X Global Digital Elevation Model ("WorldDEM", 2014), as well as spaceborne LIDAR (Light Detection and Ranging) approaches (e.g. Lidar Surface Topography/LIST mission, 2016-2020).

Assessment of the most recent satellite based digital elevation models of Egypt

NASA Astrophysics Data System (ADS)

Rabah, Mostafa; El-Hattab, Ahmed; Abdallah, Mohamed

2017-12-01

Digital Elevation Model (DEM) is crucial to a wide range of surveying and civil engineering applications worldwide. Some of the DEMs such as ASTER, SRTM1 and SRTM3 are freely available open source products. In order to evaluate the three DEMs, the contribution of EGM96 are removed and all DEMs heights are becoming ellipsoidal height. This step was done to avoid the errors occurred due to EGM96. 601 points of observed ellipsoidal heights compared with the three DEMs, the results show that the SRTM1 is the most accurate one, that produces mean height difference and standard deviations equal 2.89 and ±8.65 m respectively. In order to increase the accuracy of SRTM1 in EGYPT, a precise Global Geopotential Model (GGM) is needed to convert the SRTM1 ellipsoidal height to orthometric height, so that, we quantify the precision of most-recent released GGM (five models). The results show that, the GECO model is the best fit global models over Egypt, which produces a standard deviation of geoid undulation differences equals ±0.42 m over observed 17 HARN GPS/leveling stations. To confirm an enhanced DEM in EGYPT, the two orthometric height models (SRTM1 ellipsoidal height + EGM96) and (SRTM1 ellipsoidal height + GECO) are assessment with 17 GPS/leveling stations and 112 orthometric height stations, the results show that the estimated height differences between the SRTM1 before improvements and the enhanced model are at rate of 0.44 m and 0.06 m respectively.

Creating Orthographically Rectified Satellite Multi-Spectral Imagery with High Resolution Digital Elevation Model from LiDAR: A Tutorial

DTIC Science & Technology

2014-08-15

challenges. ERDC develops innovative solutions in civil and military engineering, geospatial sciences, water resources, and environmental sciences for...GRL TR-14-1 iv Abstract Orthoimages are used to produce image- map products for navigation and planning, and serve as source data for advanced...resulting mosaic covers a wider area and contains less visible seams, which makes the map easier to understand. RPC replace the actual sensor model while

A study of areas of low radio-thermal emissivity on Venus

NASA Astrophysics Data System (ADS)

Wilt, Robert Joseph

1992-01-01

Observations performed by the Magellan radiometer experiment have confirmed previous findings that a few regions on Venus, primarily at higher elevations, possess unexpectedly low values of radiothermal emissivity, occasionally reaching as low as 0.3. Values of emissivity below 0.7 occur over about 1.5 percent of the surface, and are associated with several types of features, including highlands, volcanoes, tectonically uplifted terrain, and impact craters. There is a strong correlation of low emissivity and high elevation, but rather than decreasing gradually with elevation, the emissivity drops rapidly in a small altitude range above a certain 'critical radius'. The altitude at which the change in emissive properties occurs varies from feature to feature; on average, it lies at a planetary radius of about 6054 km. Notable exceptions to the association of low emissivity and high elevation exist; for example, Lakshmi Planum, Maat Mons, and the summits of many volcanoes display high emissivities at high elevations, while in some impact craters and plains areas we find low emissivities at low elevations. Two possible explanations for low emissivities have been advanced: (1) emission from a highly reflective single interface between the atmosphere and a surface material having a bulk dielectric constant of order 80 ('high-dielectric' model); and (2) emission from the surface of a low-loss soil having a more usual permittivity (of order 2) which contains subsurface scatterers composed of ordinary rock materials ('volume scattering' model). Theoretical results and Monte Carlo simulations are used to show that the previously proposed volume scattering model cannot account for the observed emissivities; however, scattering from a material with very low loss (loss factor of order 10-3 or less) containing subsurface voids could produce the observed results. Consideration of the two models in light of the Magellan observations leads us to believe that the low emissivities on Venus result from the creation of a high-dielectic material by surface-atmosphere interaction, probably a loaded dielectric containing a conductive mineral.

A Control Model: Interpretation of Fitts' Law

NASA Technical Reports Server (NTRS)

Connelly, E. M.

1984-01-01

The analytical results for several models are given: a first order model where it is assumed that the hand velocity can be directly controlled, and a second order model where it is assumed that the hand acceleration can be directly controlled. Two different types of control-laws are investigated. One is linear function of the hand error and error rate; the other is the time-optimal control law. Results show that the first and second order models with the linear control-law produce a movement time (MT) function with the exact form of the Fitts' Law. The control-law interpretation implies that the effect of target width on MT must be a result of the vertical motion which elevates the hand from the starting point and drops it on the target at the target edge. The time optimal control law did not produce a movement-time formula simular to Fitt's Law.

An Imaging System for Satellite Hypervelocity Impact Debris Characterization

NASA Astrophysics Data System (ADS)

Moraguez, M.; Liou, J.; Fitz-Coy, N.; Patankar, K.; Cowardin, H.

This paper discusses the design of an automated imaging system for size characterization of debris produced by the DebriSat hypervelocity impact test. The goal of the DebriSat project is to update satellite breakup models. A representative LEO satellite, DebriSat, was constructed and subjected to a hypervelocity impact test. The impact produced an estimated 85,000 debris fragments. The size distribution of these fragments is required to update the current satellite breakup models. An automated imaging system was developed for the size characterization of the debris fragments. The system uses images taken from various azimuth and elevation angles around the object to produce a 3D representation of the fragment via a space carving algorithm. The system consists of N point-and-shoot cameras attached to a rigid support structure that defines the elevation angle for each camera. The debris fragment is placed on a turntable that is incrementally rotated to desired azimuth angles. The number of images acquired can be varied based on the desired resolution. Appropriate background and lighting is used for ease of object detection. The system calibration and image acquisition process are automated to result in push-button operations. However, for quality assurance reasons, the system is semi-autonomous by design to ensure operator involvement. This paper describes the imaging system setup, calibration procedure, repeatability analysis, and the results of the debris characterization.

An Imaging System for Satellite Hypervelocity Impact Debris Characterization

NASA Technical Reports Server (NTRS)

Moraguez, Matthew; Patankar, Kunal; Fitz-Coy, Norman; Liou, J.-C.; Cowardin, Heather

2015-01-01

This paper discusses the design of an automated imaging system for size characterization of debris produced by the DebriSat hypervelocity impact test. The goal of the DebriSat project is to update satellite breakup models. A representative LEO satellite, DebriSat, was constructed and subjected to a hypervelocity impact test. The impact produced an estimated 85,000 debris fragments. The size distribution of these fragments is required to update the current satellite breakup models. An automated imaging system was developed for the size characterization of the debris fragments. The system uses images taken from various azimuth and elevation angles around the object to produce a 3D representation of the fragment via a space carving algorithm. The system consists of N point-and-shoot cameras attached to a rigid support structure that defines the elevation angle for each camera. The debris fragment is placed on a turntable that is incrementally rotated to desired azimuth angles. The number of images acquired can be varied based on the desired resolution. Appropriate background and lighting is used for ease of object detection. The system calibration and image acquisition process are automated to result in push-button operations. However, for quality assurance reasons, the system is semi-autonomous by design to ensure operator involvement. This paper describes the imaging system setup, calibration procedure, repeatability analysis, and the results of the debris characterization.

Mapping and monitoring Mount Graham red squirrel habitat with Lidar and Landsat imagery

USGS Publications Warehouse

Hatten, James R.

2014-01-01

The Mount Graham red squirrel (Tamiasciurus hudsonicus grahamensis) is an endemic subspecies located in the Pinaleño Mountains of southeast Arizona. Living in a conifer forest on a sky-island surrounded by desert, the Mount Graham red squirrel is one of the rarest mammals in North America. Over the last two decades, drought, insect infestations, and fire destroyed much of its habitat. A federal recovery team is working on a plan to recover the squirrel and detailed information is necessary on its habitat requirements and population dynamics. Toward that goal I developed and compared three probabilistic models of Mount Graham red squirrel habitat with a geographic information system and logistic regression. Each model contained the same topographic variables (slope, aspect, elevation), but the Landsat model contained a greenness variable (Normalized Difference Vegetation Index) extracted from Landsat, the Lidar model contained three forest-inventory variables extracted from lidar, while the Hybrid model contained Landsat and lidar variables. The Hybrid model produced the best habitat classification accuracy, followed by the Landsat and Lidar models, respectively. Landsat-derived forest greenness was the best predictor of habitat, followed by topographic (elevation, slope, aspect) and lidar (tree height, canopy bulk density, and live basal area) variables, respectively. The Landsat model's probabilities were significantly correlated with all 12 lidar variables, indicating its utility for habitat mapping. While the Hybrid model produced the best classification results, only the Landsat model was suitable for creating a habitat time series or habitat–population function between 1986 and 2013. The techniques I highlight should prove valuable in the development of Landsat- or lidar-based habitat models range wide.

Digital Elevation Model, 0.25 m, Barrow Environmental Observatory, Alaska, 2013

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cathy Wilson; Garrett Altmann

This 0.25m horizontal resolution digital elevation model, DEM, was developed from Airborne Laser Altimetry flown by Aerometric Inc, now known as Quantum Spatial, Inc. on 12 July, 2013. One Mission was flown and the data jointly processed with LANL personnel to produce a 0.25m DEM covering a region approximately 2.8km wide and 12.4km long extending from the coast above North Salt Lagoon to south of Gas Well Road. This DEM encompasses a diverse range of hydrologic, geomorphic, geophysical and biological features typical of the Barrow Peninsula. Vertical accuracy at the 95% confidence interval was computed as 0.143m. The coordinate system,more » datum, and geoid for this DEM are UTM Zone 4N, NAD83 (2011), NAVD88 (GEOID09).« less

Anomalous elevated radiocarbon measurements of PM2.5

NASA Astrophysics Data System (ADS)

Buchholz, Bruce A.; Fallon, Stewart J.; Zermeño, Paula; Bench, Graham; Schichtel, Bret A.

2013-01-01

Two-component models are often used to determine the contributions made by fossil fuel and natural sources of carbon in airborne particulate matter (PM). The models reduce thousands of actual sources to two end members based on isotopic signature. Combustion of fossil fuels produces PM free of carbon-14 (14C). Wood or charcoal smoke, restaurant fryer emissions, and natural emissions from plants produce PM with the contemporary concentration of 14C approximately 1.2 × 10-1214C/C. Such data can be used to estimate the relative contributions of fossil fuels and biogenic aerosols to the total aerosol loading and radiocarbon analysis is becoming a popular source apportionment method. Emissions from incinerators combusting medical or biological wastes containing tracer 14C can skew the 14C/C ratio of PM, however, so critical analysis of sampling sites for possible sources of elevated PM needs to be completed prior to embarking on sampling campaigns. Results are presented for two ambient monitoring sites in different areas of the United States where 14C contamination is apparent. Our experience suggests that such contamination is uncommon but is also not rare (∼10%) for PM sampling sites.

The impact of lidar elevation uncertainty on mapping intertidal habitats on barrier islands

USGS Publications Warehouse

Enwright, Nicholas M.; Wang, Lei; Borchert, Sinéad M.; Day, Richard H.; Feher, Laura C.; Osland, Michael J.

2018-01-01

While airborne lidar data have revolutionized the spatial resolution that elevations can be realized, data limitations are often magnified in coastal settings. Researchers have found that airborne lidar can have a vertical error as high as 60 cm in densely vegetated intertidal areas. The uncertainty of digital elevation models is often left unaddressed; however, in low-relief environments, such as barrier islands, centimeter differences in elevation can affect exposure to physically demanding abiotic conditions, which greatly influence ecosystem structure and function. In this study, we used airborne lidar elevation data, in situ elevation observations, lidar metadata, and tide gauge information to delineate low-lying lands and the intertidal wetlands on Dauphin Island, a barrier island along the coast of Alabama, USA. We compared three different elevation error treatments, which included leaving error untreated and treatments that used Monte Carlo simulations to incorporate elevation vertical uncertainty using general information from lidar metadata and site-specific Real-Time Kinematic Global Position System data, respectively. To aid researchers in instances where limited information is available for error propagation, we conducted a sensitivity test to assess the effect of minor changes to error and bias. Treatment of error with site-specific observations produced the fewest omission errors, although the treatment using the lidar metadata had the most well-balanced results. The percent coverage of intertidal wetlands was increased by up to 80% when treating the vertical error of the digital elevation models. Based on the results from the sensitivity analysis, it could be reasonable to use error and positive bias values from literature for similar environments, conditions, and lidar acquisition characteristics in the event that collection of site-specific data is not feasible and information in the lidar metadata is insufficient. The methodology presented in this study should increase efficiency and enhance results for habitat mapping and analyses in dynamic, low-relief coastal environments.

Integrating remote sensing and terrain data in forest fire modeling

NASA Astrophysics Data System (ADS)

Medler, Michael Johns

Forest fire policies are changing. Managers now face conflicting imperatives to re-establish pre-suppression fire regimes, while simultaneously preventing resource destruction. They must, therefore, understand the spatial patterns of fires. Geographers can facilitate this understanding by developing new techniques for mapping fire behavior. This dissertation develops such techniques for mapping recent fires and using these maps to calibrate models of potential fire hazards. In so doing, it features techniques that strive to address the inherent complexity of modeling the combinations of variables found in most ecological systems. Image processing techniques were used to stratify the elements of terrain, slope, elevation, and aspect. These stratification images were used to assure sample placement considered the role of terrain in fire behavior. Examination of multiple stratification images indicated samples were placed representatively across a controlled range of scales. The incorporation of terrain data also improved preliminary fire hazard classification accuracy by 40%, compared with remotely sensed data alone. A Kauth-Thomas transformation (KT) of pre-fire and post-fire Thematic Mapper (TM) remotely sensed data produced brightness, greenness, and wetness images. Image subtraction indicated fire induced change in brightness, greenness, and wetness. Field data guided a fuzzy classification of these change images. Because fuzzy classification can characterize a continuum of a phenomena where discrete classification may produce artificial borders, fuzzy classification was found to offer a range of fire severity information unavailable with discrete classification. These mapped fire patterns were used to calibrate a model of fire hazards for the entire mountain range. Pre-fire TM, and a digital elevation model produced a set of co-registered images. Training statistics were developed from 30 polygons associated with the previously mapped fire severity. Fuzzy classifications of potential burn patterns were produced from these images. Observed field data values were displayed over the hazard imagery to indicate the effectiveness of the model. Areas that burned without suppression during maximum fire severity are predicted best. Areas with widely spaced trees and grassy understory appear to be misrepresented, perhaps as a consequence of inaccuracies in the initial fire mapping.

An automated system to simulate the River discharge in Kyushu Island using the H08 model

NASA Astrophysics Data System (ADS)

Maji, A.; Jeon, J.; Seto, S.

2015-12-01

Kyushu Island is located in southwestern part of Japan, and it is often affected by typhoons and a Baiu front. There have been severe water-related disasters recorded in Kyushu Island. On the other hand, because of high population density and for crop growth, water resource is an important issue of Kyushu Island.The simulation of river discharge is important for water resource management and early warning of water-related disasters. This study attempts to apply H08 model to simulate river discharge in Kyushu Island. Geospatial meteorological and topographical data were obtained from Japanese Ministry of Land, Infrastructure, Transport and Tourism (MLIT) and Automated Meteorological Data Acquisition System (AMeDAS) of Japan Meteorological Agency (JMA). The number of the observation stations of AMeDAS is limited and is not quite satisfactory for the application of water resources models in Kyushu. It is necessary to spatially interpolate the point data to produce grid dataset. Meteorological grid dataset is produced by considering elevation dependence. Solar radiation is estimated from hourly sunshine duration by a conventional formula. We successfully improved the accuracy of interpolated data just by considering elevation dependence and found out that the bias is related to geographical location. The rain/snow classification is done by H08 model and is validated by comparing estimated and observed snow rate. The estimates tend to be larger than the corresponding observed values. A system to automatically produce daily meteorological grid dataset is being constructed.The geospatial river network data were produced by ArcGIS and they were utilized in the H08 model to simulate the river discharge. Firstly, this research is to compare simulated and measured specific discharge, which is the ratio of discharge to watershed area. Significant error between simulated and measured data were seen in some rivers. Secondly, the outputs by the coupled model including crop growth module and reservoir operation module were analyzed. However, there are differences between the simulated value and measured value. We need to improve dam operation, artificial water intake, and parameters such as depth of the soil and flow velocity in the river.

Improving Frozen Precipitation Density Estimation in Land Surface Modeling

NASA Astrophysics Data System (ADS)

Sparrow, K.; Fall, G. M.

2017-12-01

The Office of Water Prediction (OWP) produces high-value water supply and flood risk planning information through the use of operational land surface modeling. Improvements in diagnosing frozen precipitation density will benefit the NWS's meteorological and hydrological services by refining estimates of a significant and vital input into land surface models. A current common practice for handling the density of snow accumulation in a land surface model is to use a standard 10:1 snow-to-liquid-equivalent ratio (SLR). Our research findings suggest the possibility of a more skillful approach for assessing the spatial variability of precipitation density. We developed a 30-year SLR climatology for the coterminous US from version 3.22 of the Daily Global Historical Climatology Network - Daily (GHCN-D) dataset. Our methods followed the approach described by Baxter (2005) to estimate mean climatological SLR values at GHCN-D sites in the US, Canada, and Mexico for the years 1986-2015. In addition to the Baxter criteria, the following refinements were made: tests were performed to eliminate SLR outliers and frequent reports of SLR = 10, a linear SLR vs. elevation trend was fitted to station SLR mean values to remove the elevation trend from the data, and detrended SLR residuals were interpolated using ordinary kriging with a spherical semivariogram model. The elevation values of each station were based on the GMTED 2010 digital elevation model and the elevation trend in the data was established via linear least squares approximation. The ordinary kriging procedure was used to interpolate the data into gridded climatological SLR estimates for each calendar month at a 0.125 degree resolution. To assess the skill of this climatology, we compared estimates from our SLR climatology with observations from the GHCN-D dataset to consider the potential use of this climatology as a first guess of frozen precipitation density in an operational land surface model. The difference in model derived estimates and GHCN-D observations were assessed using time-series graphs of 2016-2017 winter season SLR observations and climatological estimates, as well as calculating RMSE and variance between estimated and observed values.

A Preliminary Analysis of the Flying Qualities of the Consolidated Vultee MX-813 Delta-Wing Airplane Configuration at Transonic and Low Supersonic Speeds as Determined from Flights of Rocket-Powered Models

NASA Technical Reports Server (NTRS)

Mitcham, Grady L.

1949-01-01

A preliminary analysis of the flying qualities of the Consolidated Vultee MX-813 delta-wing airplane configuration has been made based on the results obtained from the first two 1/8 scale models flown at the NACA Pilotless Aircraft Research Station, Wallop's Island, VA. The Mach number range covered in the tests was from 0.9 to 1.2. The analysis indicates adequate elevator control for trim in level flight over the speed range investigated. Through the transonic range there is a mild trim change with a slight tucking-under tendency. The elevator control effectiveness in the supersonic range is reduced to about one-half the subsonic value although sufficient control for maneuvering is available as indicated by the fact that 10 deg elevator deflection produced 5g acceleration at Mach number of 1.2 at 40,000 feet.The elevator control forces are high and indicate the power required of the boost system. The damping. of the short-period oscillation is adequate at sea-level but is reduced at 40,000 feet. The directional stability appears adequate for the speed range and angles of attack covered.

A spectroscopic experimental and computer-assisted empirical model for the production and energetics of excited oxygen molecules formed by atom recombination on shuttle tile surfaces

NASA Technical Reports Server (NTRS)

Owan, D. A.

1981-01-01

A visible emission spectroscopic method was developed. The amounts of excited singlet and triplet oxygen molecules produced by recombination on the Space Shuttle Orbiter thermal protective tiles at elevated temperatures are determined. Rate constants and energetics of the extremely exothermic reaction are evaluated in terms of a chemical and mathematical model. Implications for potential contribution to Shuttle surface reentry heating fluxes are outlined.

a New High-Resolution Elevation Model of Greenland Derived from Tandem-X

NASA Astrophysics Data System (ADS)

Wessel, B.; Bertram, A.; Gruber, A.; Bemm, S.; Dech, S.

2016-06-01

In this paper we present for the first time the new digital elevation model (DEM) for Greenland produced by the TanDEM-X (TerraSAR add-on for digital elevation measurement) mission. The new, full coverage DEM of Greenland has a resolution of 0.4 arc seconds corresponding to 12 m. It is composed of more than 7.000 interferometric synthetic aperture radar (InSAR) DEM scenes. X-Band SAR penetrates the snow and ice pack by several meters depending on the structures within the snow, the acquisition parameters, and the dielectricity constant of the medium. Hence, the resulting SAR measurements do not represent the surface but the elevation of the mean phase center of the backscattered signal. Special adaptations on the nominal TanDEM-X DEM generation are conducted to maintain these characteristics and not to raise or even deform the DEM to surface reference data. For the block adjustment, only on the outer coastal regions ICESat (Ice, Cloud, and land Elevation Satellite) elevations as ground control points (GCPs) are used where mostly rock and surface scattering predominates. Comparisons with ICESat data and snow facies are performed. In the inner ice and snow pack, the final X-Band InSAR DEM of Greenland lies up to 10 m below the ICESat measurements. At the outer coastal regions it corresponds well with the GCPs. The resulting DEM is outstanding due to its resolution, accuracy and full coverage. It provides a high resolution dataset as basis for research on climate change in the arctic.

The Use of Sun Elevation Angle for Stereogrammetric Boreal Forest Height in Open Canopies

NASA Technical Reports Server (NTRS)

Montesano, Paul M.; Neigh, Christopher; Sun, Guoqing; Duncanson, Laura Innice; Van Den Hoek, Jamon; Ranson, Kenneth Jon

2017-01-01

Stereogrammetry applied to globally available high resolution spaceborne imagery (HRSI; less than 5 m spatial resolution) yields fine-scaled digital surface models (DSMs) of elevation. These DSMs may represent elevations that range from the ground to the vegetation canopy surface, are produced from stereoscopic image pairs (stereo pairs) that have a variety of acquisition characteristics, and have been coupled with lidar data of forest structure and ground surface elevation to examine forest height. This work explores surface elevations from HRSI DSMs derived from two types of acquisitions in open canopy forests. We (1) apply an automated mass-production stereogrammetry workflow to along-track HRSI stereo pairs, (2) identify multiple spatially coincident DSMs whose stereo pairs were acquired under different solar geometry, (3) vertically co-register these DSMs using coincident spaceborne lidar footprints (from ICESat-GLAS) as reference, and(4) examine differences in surface elevations between the reference lidar and the co-registered HRSI DSMs associated with two general types of acquisitions (DSM types) from different sun elevation angles. We find that these DSM types, distinguished by sun elevation angle at the time of stereo pair acquisition, are associated with different surface elevations estimated from automated stereogrammetry in open canopy forests. For DSM values with corresponding reference ground surface elevation from spaceborne lidar footprints in open canopy northern Siberian Larix forests with slopes less than10, our results show that HRSI DSM acquired with sun elevation angles greater than 35deg and less than 25deg (during snow-free conditions) produced characteristic and consistently distinct distributions of elevation differences from reference lidar. The former include DSMs of near-ground surfaces with root mean square errors less than 0.68 m relative to lidar. The latter, particularly those with angles less than 10deg, show distributions with larger differences from lidar that are associated with open canopy forests whose vegetation surface elevations are captured. Terrain aspect did not have a strong effect on the distribution of vegetation surfaces. Using the two DSM types together, the distribution of DSM-differenced heights in forests (6.0 m, sigma = 1.4 m) was consistent with the distribution of plot-level mean tree heights (6.5m, sigma = 1.2 m). We conclude that the variation in sun elevation angle at time of stereo pair acquisition can create illumination conditions conducive for capturing elevations of surfaces either near the ground or associated with vegetation canopy. Knowledge of HRSI acquisition solar geometry and snow cover can be used to understand and combine stereogrammetric surface elevation estimates to co-register rand difference overlapping DSMs, providing a means to map forest height at fine scales, resolving the vertical structure of groups of trees from spaceborne platforms in open canopy forests.

Automating the implementation of an equilibrium profile model for glacier reconstruction in a GIS environment

NASA Astrophysics Data System (ADS)

Frew, Craig R.; Pellitero, Ramón; Rea, Brice R.; Spagnolo, Matteo; Bakke, Jostein; Hughes, Philip D.; Ivy-Ochs, Susan; Lukas, Sven; Renssen, Hans; Ribolini, Adriano

2014-05-01

Reconstruction of glacier equilibrium line altitudes (ELAs) associated with advance stages of former ice masses is widely used as a tool for palaeoclimatic reconstruction. This requires an accurate reconstruction of palaeo-glacier surface hypsometry, based on mapping of available ice-marginal landform evidence. Classically, the approach used to define ice-surface elevations, using such evidence, follows the 'cartographic method', whereby contours are estimated based on an 'understanding' of the typical surface form of contemporary ice masses. This method introduces inherent uncertainties in the palaeoclimatic interpretation of reconstructed ELAs, especially where the upper limits of glaciation are less well constrained and/or the age of such features in relation to terminal moraine sequences is unknown. An alternative approach is to use equilibrium profile models to define ice surface elevations. Such models are tuned, generally using basal shear stress, in order to generate an ice surface that reaches 'target elevations' defined by geomorphology. In areas where there are no geomorphological constraints for the former ice surface, the reconstruction is undertaken using glaciologiaclly representative values for basal shear stress. Numerical reconstructions have been shown to produce glaciologically "realistic" ice surface geometries, allowing for more objective and robust comparative studies at local to regional scales. User-friendly tools for the calculation of equilibrium profiles are presently available in the literature. Despite this, their use is not yet widespread, perhaps owing to the difficult and time consuming nature of acquiring the necessary inputs from contour maps or digital elevation models. Here we describe a tool for automatically reconstructing palaeo-glacier surface geometry using an equilibrium profile equation implemented in ArcGIS. The only necessary inputs for this tool are 1) a suitable digital elevation model and 2) mapped outlines of the former glacier terminus position (usually a frontal moraine system) and any relevant geomorphological constraints on ice surface elevation (e.g. lateral moraines, trimlines etc.). This provides a standardised method for glacier reconstruction that can be applied rapidly and systematically to large geomorphological datasets.

Wind-Tunnel Investigation of the Low-Speed Static Stability and Control Characteristics of a Model of the Bell MX-776 (RASCAL) in Combined Angle of Attack and Sideslip

NASA Technical Reports Server (NTRS)

Letko, William

1949-01-01

An investigation has been made in the Langley stability tunnel to determine the low-speed static stability and control characteristics of a model of the Bell MX-776. The results show the model to be longitudinally unstable in the angle-of-attack range around zero angle of attack and to become stable at moderate angles of attack. The results of the present investigation agree reasonably well with results obtained in other facilities at low speed. The present pitching-moment results at low Mach numbers also agree reasonably well with unpublished results of tests of the model at supersonic Mach numbers (up to Mach number 1.86). Unpublished results at moderate and high subsonic speeds, however, indicate considerably greater instability at low angles of attack than is indicated by low-speed results. The results of the present tests also showed that the pitching-moment coefficients for angles of attack up to 12deg remained fairly constant with sideslip angle up to 12deg. The elevators tested produced relatively large pitching moments at zero angle of attack but, as the angle of attack was increased, the elevator effectiveness decreased. The rate of decrease of elevator effectiveness with angle of attack was less for 8deg than for 20deg elevator deflection. Therefore although 8deg deflection caused an appreciable change in longitudinal trim angle and trim lift coefficient a deflection of 20deg caused only a small additional increase in trim angle and trim lift coefficient.

An investigation of Digital Elevation Model (DEM) structure influence on flood modelling

NASA Astrophysics Data System (ADS)

Sahid; Nurrohman, A. W.; Hadi, M. P.

2018-04-01

Flood is one of the natural calamities that cause huge losses and damages. Flood hazard zonation has been widely produced to face the impact of the disaster. DEM as the primary data to construct the earth surface has been developed from rough to fine resolution. Aster GDEM v.2 within 1arc spatial resolution has an ability to derived DEM and TIN data as bases river geometrics data. Maximum daily peak discharges used to calculate flood peak discharge. Furthermore, steady flow analysis has been used to produce flood inundation model based on four scenarios with return periods 5yr, 10yr, 50yr, and 100yr. The model results have been validated using UAV flood map in 2016 by means of pixel by pixel operation and the result shows that the vertical variance between grid DEM and TIN data about 0.3 m.

Investigating broadband variability of the TeV blazar 1ES 1959+650

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aliu, E.; Archambault, S.; Arlen, T.

We summarize broadband observations of the TeV-emitting blazar 1ES 1959 650, including optical R-band observations by the robotic telescopes Super-LOTIS and iTelescope, UV observations by Swift UVOT, X-ray observations by the Swift X-ray Telescope, high-energy gamma-ray observations with the Fermi Large Area Telescope, and very-high-energy (VHE) gamma-ray observations by VERITAS above 315 GeV, all taken between 2012 April 17 and 2012 June 1 (MJD 56034 and 56079). The contemporaneous variability of the broadband spectral energy distribution is explored in the context of a simple synchrotron self Compton (SSC) model. In the SSC emission scenario, we find that the parameters requiredmore » to represent the high state are significantly different than those in the low state. Motivated by possible evidence of gas in the vicinity of the blazar, we also investigate a reflected emission model to describe the observed variability pattern. This model assumes that the non-thermal emission from the jet is reflected by a nearby cloud of gas, allowing the reflected emission to re-enter the blob and produce an elevated gamma-ray state with no simultaneous elevated synchrotron flux. The model applied here, although not required to explain the observed variability pattern, represents one possible scenario which can describe the observations. As applied to an elevated VHE state of 66% of the Crab Nebula flux, observed on a single night during the observation period, the reflected emission scenario does not support a purely leptonic non-thermal emission mechanism. The reflected model does, however, predict a reflected photon field with sufficient energy to enable elevated gamma-ray emission via pion production with protons of energies between 10 and 100 TeV.« less

INVESTIGATING BROADBAND VARIABILITY OF THE TeV BLAZAR 1ES 1959+650

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aliu, E.; Archambault, S.; Arlen, T.

We summarize broadband observations of the TeV-emitting blazar 1ES 1959+650, including optical R-band observations by the robotic telescopes Super-LOTIS and iTelescope, UV observations by Swift Ultraviolet and Optical Telescope, X-ray observations by the Swift X-ray Telescope, high-energy gamma-ray observations with the Fermi Large Area Telescope, and very-high-energy (VHE) gamma-ray observations by VERITAS above 315 GeV, all taken between 2012 April 17 and 2012 June 1 (MJD 56034 and 56079). The contemporaneous variability of the broadband spectral energy distribution is explored in the context of a simple synchrotron self Compton (SSC) model. In the SSC emission scenario, we find that themore » parameters required to represent the high state are significantly different than those in the low state. Motivated by possible evidence of gas in the vicinity of the blazar, we also investigate a reflected emission model to describe the observed variability pattern. This model assumes that the non-thermal emission from the jet is reflected by a nearby cloud of gas, allowing the reflected emission to re-enter the blob and produce an elevated gamma-ray state with no simultaneous elevated synchrotron flux. The model applied here, although not required to explain the observed variability pattern, represents one possible scenario which can describe the observations. As applied to an elevated VHE state of 66% of the Crab Nebula flux, observed on a single night during the observation period, the reflected emission scenario does not support a purely leptonic non-thermal emission mechanism. The reflected emission model does, however, predict a reflected photon field with sufficient energy to enable elevated gamma-ray emission via pion production with protons of energies between 10 and 100 TeV.« less

INVESTIGATING BROADBAND VARIABILITY OF THE TeV BLAZAR 1ES 1959+650

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aliu, E.; Archambault, S.; Arlen, T.

We summarize broadband observations of the TeV-emitting blazar 1ES 1959+650, including optical R-band observations by the robotic telescopes Super-LOTIS and iTelescope, UV observations by Swift Ultraviolet and Optical Telescope, X-ray observations by the Swift X-ray Telescope, high-energy gamma-ray observations with the Fermi Large Area Telescope, and very-high-energy (VHE) gamma-ray observations by VERITAS above 315 GeV, all taken between 2012 April 17 and 2012 June 1 (MJD 56034 and 56079). The contemporaneous variability of the broadband spectral energy distribution is explored in the context of a simple synchrotron self Compton (SSC) model. In the SSC emission scenario, we find that themore » parameters required to represent the high state are significantly different than those in the low state. Motivated by possible evidence of gas in the vicinity of the blazar, we also investigate a reflected emission model to describe the observed variability pattern. This model assumes that the non-thermal emission from the jet is reflected by a nearby cloud of gas, allowing the reflected emission to re-enter the blob and produce an elevated gamma-ray state with no simultaneous elevated synchrotron flux. The model applied here, although not required to explain the observed variability pattern, represents one possible scenario which can describe the observations. As applied to an elevated VHE state of 66% of the Crab Nebula flux, observed on a single night during the observation period, the reflected emission scenario does not support a purely leptonic non-thermal emission mechanism. The reflected emission model does, however, predict a reflected photon field with sufficient energy to enable elevated gamma-ray emission via pion production with protons of energies between 10 and 100 TeV.« less

Investigating broadband variability of the TeV blazar 1ES 1959+650

DOE PAGES

Aliu, E.; Archambault, S.; Arlen, T.; ...

2014-12-03

We summarize broadband observations of the TeV-emitting blazar 1ES 1959 650, including optical R-band observations by the robotic telescopes Super-LOTIS and iTelescope, UV observations by Swift UVOT, X-ray observations by the Swift X-ray Telescope, high-energy gamma-ray observations with the Fermi Large Area Telescope, and very-high-energy (VHE) gamma-ray observations by VERITAS above 315 GeV, all taken between 2012 April 17 and 2012 June 1 (MJD 56034 and 56079). The contemporaneous variability of the broadband spectral energy distribution is explored in the context of a simple synchrotron self Compton (SSC) model. In the SSC emission scenario, we find that the parameters requiredmore » to represent the high state are significantly different than those in the low state. Motivated by possible evidence of gas in the vicinity of the blazar, we also investigate a reflected emission model to describe the observed variability pattern. This model assumes that the non-thermal emission from the jet is reflected by a nearby cloud of gas, allowing the reflected emission to re-enter the blob and produce an elevated gamma-ray state with no simultaneous elevated synchrotron flux. The model applied here, although not required to explain the observed variability pattern, represents one possible scenario which can describe the observations. As applied to an elevated VHE state of 66% of the Crab Nebula flux, observed on a single night during the observation period, the reflected emission scenario does not support a purely leptonic non-thermal emission mechanism. The reflected model does, however, predict a reflected photon field with sufficient energy to enable elevated gamma-ray emission via pion production with protons of energies between 10 and 100 TeV.« less

The National Map - Elevation

USGS Publications Warehouse

Gesch, Dean; Evans, Gayla; Mauck, James; Hutchinson, John; Carswell, William J.

2009-01-01

The National Elevation Dataset (NED) is the primary elevation data product produced and distributed by the USGS. The NED provides seamless raster elevation data of the conterminous United States, Alaska, Hawaii, and the island territories. The NED is derived from diverse source data sets that are processed to a specification with a consistent resolution, coordinate system, elevation units, and horizontal and vertical datums. The NED is the logical result of the maturation of the long-standing USGS elevation program, which for many years concentrated on production of topographic map quadrangle-based digital elevation models. The NED serves as the elevation layer of The National Map, and provides basic elevation information for earth science studies and mapping applications in the United States. The NED is a multi-resolution dataset that is updated bimonthly to integrate newly available, improved elevation source data. NED data are available nationally at grid spacings of 1 arc-second (approximately 30 meters) for the conterminous United States, and at 1/3 and 1/9 arc-seconds (approximately 10 and 3 meters, respectively) for parts of the United States. Most of the NED for Alaska is available at 2-arc-second (about 60 meters) grid spacing, where only lower resolution source data exist. Part of Alaska is available at the 1/3-arc-second resolution, and plans are in development for a significant upgrade in elevation data coverage of the State over the next 5 years. Specifications for the NED include the following: *Coordinate system: Geographic (decimal degrees of latitude and longitude), *Horizontal datum: North American Datum of 1983 (NAD 83), *Vertical datum: North American Vertical Datum of 1988 (NAVD 88) over the conterminous United States and varies in other areas, and *Elevation units: Decimal meters.

Identification of glutathione adducts of α-chlorofatty aldehydes produced in activated neutrophils

PubMed Central

Duerr, Mark A.; Aurora, Rajeev; Ford, David A.

2015-01-01

α-Chlorofatty aldehydes (α-ClFALDs) are produced by hypochlorous acid targeting plasmalogens during neutrophil activation. This study investigated the reaction of the α-chlorinated carbon of α-ClFALD with the nucleophile, GSH. Utilizing ESI/MS/MS, the reaction product of GSH and the 16-carbon α-ClFALD, 2-chlorohexadecanal (2-ClHDA), was characterized. The resulting conjugate of 2-ClHDA and GSH (HDA-GSH) has an intact free aldehyde, and the chlorine at the α-carbon is ejected. Stable isotope-labeled [d4]HDA-GSH was synthesized, which further confirmed the structure, and was used to quantify natural α-ClFALD conjugates of GSH (FALD-GSH) using reverse-phase LC with detection by ESI/MS/MS using selected reaction monitoring. HDA-GSH is elevated in RAW 264.7 cells treated with physiologically relevant concentrations of exogenous 2-ClHDA. Furthermore, PMA-treated primary human neutrophils have elevated levels of HDA-GSH and the conjugate of 2-chlorooctadecanal (2-ClODA) and GSH (ODA-GSH), as well as elevated levels of 2-ClHDA and 2-ClODA. Production of both conjugates in PMA-stimulated neutrophils was reduced by 3-aminotriazole pretreatment, which also blocks endogenous α-ClFALD production. Additionally, plasma FALD-GSH levels were elevated in the K/BxN mouse arthritis model. Taken together, these studies demonstrate novel peptidoaldehydes derived from GSH and α-ClFALD in activated human neutrophils and in vivo in K/BxN mice. PMID:25814023

Multi-decadal elevation changes on Bagley Ice Valley and Malaspina Glacier, Alaska

NASA Astrophysics Data System (ADS)

Muskett, Reginald R.; Lingle, Craig S.; Tangborn, Wendell V.; Rabus, Bernhard T.

2003-08-01

Digital elevation models (DEMs) of Bagley Ice Valley and Malaspina Glacier produced by (i) Intermap Technologies, Inc. (ITI) from airborne interferometric synthetic aperture radar (InSAR) data acquired 4-13 September 2000, (ii) the German Aerospace Center (DRL) from spaceborne InSAR data acquired by the Shuttle Radar Topography Mission (SRTM) 11-22 February 2000, and (iii) the US Geological Survey (USGS) from aerial photographs acquired in 1972/73, were differenced to estimate glacier surface elevation changes from 1972 to 2000. Spatially non-uniform thickening, 10 +/- 7 m on average, is observed on Bagley Ice Valley (accumulation area) while non-uniform thinning, 47 +/- 5 m on average, is observed on the glaciers of the Malaspina complex (mostly ablation area). Even larger thinning is observed on the retreating tidewater Tyndall Glacier. These changes have resulted from increased temperature and precipitation associated with climate warming, and rapid tidewater retreat.

3D Lunar Terrain Reconstruction from Apollo Images

NASA Technical Reports Server (NTRS)

Broxton, Michael J.; Nefian, Ara V.; Moratto, Zachary; Kim, Taemin; Lundy, Michael; Segal, Alkeksandr V.

2009-01-01

Generating accurate three dimensional planetary models is becoming increasingly important as NASA plans manned missions to return to the Moon in the next decade. This paper describes a 3D surface reconstruction system called the Ames Stereo Pipeline that is designed to produce such models automatically by processing orbital stereo imagery. We discuss two important core aspects of this system: (1) refinement of satellite station positions and pose estimates through least squares bundle adjustment; and (2) a stochastic plane fitting algorithm that generalizes the Lucas-Kanade method for optimal matching between stereo pair images.. These techniques allow us to automatically produce seamless, highly accurate digital elevation models from multiple stereo image pairs while significantly reducing the influence of image noise. Our technique is demonstrated on a set of 71 high resolution scanned images from the Apollo 15 mission

Molecular and functional assessment of multicellular cancer spheroids produced in double emulsions enabled by efficient airway resistance based selective surface treatment

NASA Astrophysics Data System (ADS)

Ma, Xiao; Leth Jepsen, Morten; Ivarsen, Anne Kathrine R.; Knudsen, Birgitta R.; Ho, Yi-Ping

2017-09-01

Multicellular spheroids have garnered significant attention as an in vitro three-dimensional cancer model which can mimick the in vivo microenvironmental features. While microfluidics generated double emulsions have become a potential method to generate spheroids, challenges remain on the tedious procedures. Enabled by a novel ‘airway resistance’ based selective surface treatment, this study presents an easy and facile generation of double emulsions for the initiation and cultivation of multicellular spheroids in a scaffold-free format. Combining with our previously developed DNA nanosensors, intestinal spheroids produced in the double emulsions have shown an elevated activities of an essential DNA modifying enzyme, the topoisomerase I. The observed molecular and functional characteristics of spheroids produced in double emulsions are similar to the counterparts produced by the commercially available ultra-low attachment plates. However, the double emulsions excel for their improved uniformity, and the consistency of the results obtained by subsequent analysis of the spheroids. The presented technique is expected to ease the burden of producing spheroids and to promote the spheroids model for cancer or stem cell study.

Diadenosine tetraphosphate as a potential therapeutic nucleotide to treat glaucoma.

PubMed

Fonseca, Begoña; Martínez-Águila, Alejandro; de Lara, María J Pérez; Pintor, Jesús

2017-06-01

Glaucoma is a neurodegenerative disease that produces blindness. The main factor associated with this disease is an abnormally elevated intraocular pressure (IOP). To date, some attempts have been made to demonstrate the role of nucleotides modulating IOP, but never in a model of glaucoma. The DBA/2J mouse is an animal that develops the pathology spontaneously, starting from the typical rise in IOP at 9 months of age. Using this animal model, together with a control mouse, C57BL/6J, it has been possible to monitor the elevation in IOP in the glaucomatous mice and to check the ability of the dinucleotide diadenosine tetraphosphate AKA Ap 4 A to reduce IOP. The topical application of Ap 4 A when IOP is maximal (9-12 months) reduced IOP 30.6 ± 6.6% in the DBA/2J and 17.9 ± 4.0% in the C57BL/6J mice. Concentration response curves in both animal strains produced similar pD2 values; these being 4.9 ± 0.5 and 5.1 ± 0.4 for the normotensive C57BL/6J and the glaucomatous DBA/2J respectively. Antagonist studies showed differences between the control and the glaucomatous animals. In particular, the main receptor reducing IOP in the control animal was the P2Y 1 receptor and in the glaucomatous model the P2Y 6 , although the participation of other P2 receptors cannot be ruled out. The long-term effect of Ap 4 A applied three times a week for 3 months showed a clear stop in the elevation of IOP in the glaucomatous model, thus indicating the possibility of using Ap 4 A as an effective compound for the treatment of glaucoma.

Effects of Cultivar and Maternal Environment on Seed Quality in Vicia sativa

PubMed Central

Li, Rong; Chen, Lijun; Wu, Yanpei; Zhang, Rui; Baskin, Carol C.; Baskin, Jerry M.; Hu, Xiaowen

2017-01-01

Production of high quality seeds is of fundamental importance for successful crop production. However, knowledge of the effects of increased temperature resulting from global warming on seed quality of alpine species is limited. We investigated the effect of maternal environment on seed quality of three cultivars of the leguminous forage species Vicia sativa, giving particular attention to temperature. Plants of each cultivar were grown at 1700 and 3000 m a.s.l., and mass, germination, electrical conductivity (EC) of leakage and longevity were determined for mature seeds. Seeds of all three cultivars produced at the low elevation had a significantly lower mass and longevity but higher EC of leachate than those produced at the high elevation, suggesting that increased temperatures decreased seed quality. However, seed viability did not differ between elevations. The effects of maternal environment on seed germination strongly depended on cultivar and germination temperature. At 10 and 15°C, seeds of “Lanjian 3” produced at high elevation germinated to higher percentages and rates than those produced at low elevation, but the opposite trend was observed at 20°C. However, for seeds of “Lanjian 1” and “Lanjian 2,” no significant effect of elevation was observed in germination percentage. Our results indicate that the best environment for the production of high quality seeds (e.g., high seed mass, low EC, high seed longevity) of V. sativa is one in which temperatures are relatively low during seed development. PMID:28861096

Atmospheric CO2 enrichment alters energy assimilation, investment and allocation in Xanthium strumarium.

PubMed

Nagel, Jennifer M; Wang, Xianzhong; Lewis, James D; Fung, Howard A; Tissue, David T; Griffin, Kevin L

2005-05-01

Energy-use efficiency and energy assimilation, investment and allocation patterns are likely to influence plant growth responses to increasing atmospheric CO2 concentration ([CO2]). Here, we describe the influence of elevated [CO2] on energetic properties as a mechanism of growth responses in Xanthium strumarium. Individuals of X. strumarium were grown at ambient or elevated [CO2] and harvested. Total biomass and energetic construction costs (CC) of leaves, stems, roots and fruits and percentage of total biomass and energy allocated to these components were determined. Photosynthetic energy-use efficiency (PEUE) was calculated as the ratio of total energy gained via photosynthetic activity (Atotal) to leaf CC. Elevated [CO2] increased leaf Atotal, but decreased CC per unit mass of leaves and roots. Consequently, X. strumarium individuals produced more leaf and root biomass at elevated [CO2] without increasing total energy investment in these structures (CCtotal). Whole-plant biomass was associated positively with PEUE. Whole-plant construction required 16.1% less energy than modeled whole-plant energy investment had CC not responded to increased [CO2]. As a physiological mechanism affecting growth, altered energetic properties could positively influence productivity of X. strumarium, and potentially other species, at elevated [CO2].

Wildland inventory and resource modeling for Douglas and Carson City Counties, Nevada, using LANDSAT and digital terrain data

NASA Technical Reports Server (NTRS)

Brass, J. A.; Likens, W. C.; Thornhill, R. R.

1983-01-01

The potential of using LANDSAT satellite imagery to map and inventory pinyon-juniper desert forest types in Douglas and Carson City Counties, Nevada was demonstrated. Specific map and statistical products produced include land cover, mechanical operations capability, big game winter range habitat, fire hazard, and forest harvestability. The Nevada Division of Forestry determined that LANDSAT can produce a reliable and low-cost resource data. Added benefits become apparent when the data are linked to a geographical information system (GIS) containing existing ownership, planning, elevation, slope, and aspect information.

Susceptibility to traumatic stress sensitizes the dopaminergic response to cocaine and increases motivation for cocaine.

PubMed

Brodnik, Zachary D; Black, Emily M; Clark, Meagan J; Kornsey, Kristen N; Snyder, Nathaniel W; España, Rodrigo A

2017-10-01

Patients with post-traumatic stress disorder have a heightened vulnerability to developing substance use disorders; however, the biological underpinnings of this vulnerability remain unresolved. We used the predator odor stress model of post-traumatic stress disorder with segregation of subjects as susceptible or resilient based on elevated plus maze behavior and context avoidance. We then determined behavioral and neurochemical differences across susceptible, resilient, and control populations using a panel of behavioral and neurochemical assays. Susceptible subjects showed a significant increase in the motoric and dopaminergic effects of cocaine, and this corresponded with heightened motivation to self-administer cocaine. Resilient subjects did not show differences in the motoric effects of cocaine, in dopamine signaling in vivo, or in any measure of cocaine self-administration. Nonetheless, we found that these animals displayed elevations in both the dopamine release-promoting effects of cocaine and dopamine autoreceptor sensitivity ex vivo. Our results suggest that the experience of traumatic stress may produce alterations in dopamine systems that drive elevations in cocaine self-administration behavior in susceptible subjects, but may also produce both active and passive forms of resilience that function to prevent gross changes in cocaine's reinforcing efficacy in resilient subjects. Copyright © 2017 Elsevier Ltd. All rights reserved.

Comparison of ArcGIS and SAS Geostatistical Analyst to Estimate Population-Weighted Monthly Temperature for US Counties.

PubMed

Xiaopeng, Q I; Liang, Wei; Barker, Laurie; Lekiachvili, Akaki; Xingyou, Zhang

Temperature changes are known to have significant impacts on human health. Accurate estimates of population-weighted average monthly air temperature for US counties are needed to evaluate temperature's association with health behaviours and disease, which are sampled or reported at the county level and measured on a monthly-or 30-day-basis. Most reported temperature estimates were calculated using ArcGIS, relatively few used SAS. We compared the performance of geostatistical models to estimate population-weighted average temperature in each month for counties in 48 states using ArcGIS v9.3 and SAS v 9.2 on a CITGO platform. Monthly average temperature for Jan-Dec 2007 and elevation from 5435 weather stations were used to estimate the temperature at county population centroids. County estimates were produced with elevation as a covariate. Performance of models was assessed by comparing adjusted R 2 , mean squared error, root mean squared error, and processing time. Prediction accuracy for split validation was above 90% for 11 months in ArcGIS and all 12 months in SAS. Cokriging in SAS achieved higher prediction accuracy and lower estimation bias as compared to cokriging in ArcGIS. County-level estimates produced by both packages were positively correlated (adjusted R 2 range=0.95 to 0.99); accuracy and precision improved with elevation as a covariate. Both methods from ArcGIS and SAS are reliable for U.S. county-level temperature estimates; However, ArcGIS's merits in spatial data pre-processing and processing time may be important considerations for software selection, especially for multi-year or multi-state projects.

Evaluation of Elevation, Slope and Stream Network Quality of SPOT Dems

NASA Astrophysics Data System (ADS)

El Hage, M.; Simonetto, E.; Faour, G.; Polidori, L.

2012-07-01

Digital elevation models are considered the most useful data for dealing with geomorphology. The quality of these models is an important issue for users. This quality concerns position and shape. Vertical accuracy is the most assessed in many studies and shape quality is often neglected. However, both of them have an impact on the quality of the final results for a particular application. For instance, the elevation accuracy is required for orthorectification and the shape quality for geomorphology and hydrology. In this study, we deal with photogrammetric DEMs and show the importance of the quality assessment of both elevation and shape. For this purpose, we produce several SPOT HRV DEMs with the same dataset but with different template size, that is one of the production parameters from optical images. Then, we evaluate both elevation and shape quality. The shape quality is assessed with in situ measurements and analysis of slopes as an elementary shape and stream networks as a complex shape. We use the fractal dimension and sinuosity to evaluate the stream network shape. The results show that the elevation accuracy as well as the slope accuracy are affected by the template size. Indeed, an improvement of 1 m in the elevation accuracy and of 5 degrees in the slope accuracy has been obtained while changing this parameter. The elevation RMSE ranges from 7.6 to 8.6 m, which is smaller than the pixel size (10 m). For slope, the RMSE depends on the sampling distance. With a distance of 10 m, the minimum slope RMSE is 11.4 degrees. The stream networks extracted from these DEMs present a higher fractal dimension than the reference river. Moreover, the fractal dimension of the extracted networks has a negligible change according to the template size. Finally, the sinuosity of the stream networks is slightly affected by the change of the template size.

The pyramid system for multiscale raster analysis

USGS Publications Warehouse

De Cola, L.; Montagne, N.

1993-01-01

Geographical research requires the management and analysis of spatial data at multiple scales. As part of the U.S. Geological Survey's global change research program a software system has been developed that reads raster data (such as an image or digital elevation model) and produces a pyramid of aggregated lattices as well as various measurements of spatial complexity. For a given raster dataset the system uses the pyramid to report: (1) mean, (2) variance, (3) a spatial autocorrelation parameter based on multiscale analysis of variance, and (4) a monofractal scaling parameter based on the analysis of isoline lengths. The system is applied to 1-km digital elevation model (DEM) data for a 256-km2 region of central California, as well as to 64 partitions of the region. PYRAMID, which offers robust descriptions of data complexity, also is used to describe the behavior of topographic aspect with scale. ?? 1993.

Digital elevation model generation from satellite interferometric synthetic aperture radar: Chapter 5

USGS Publications Warehouse

Lu, Zhong; Dzurisin, Daniel; Jung, Hyung-Sup; Zhang, Lei; Lee, Wonjin; Lee, Chang-Wook

2012-01-01

An accurate digital elevation model (DEM) is a critical data set for characterizing the natural landscape, monitoring natural hazards, and georeferencing satellite imagery. The ideal interferometric synthetic aperture radar (InSAR) configuration for DEM production is a single-pass two-antenna system. Repeat-pass single-antenna satellite InSAR imagery, however, also can be used to produce useful DEMs. DEM generation from InSAR is advantageous in remote areas where the photogrammetric approach to DEM generation is hindered by inclement weather conditions. There are many sources of errors in DEM generation from repeat-pass InSAR imagery, for example, inaccurate determination of the InSAR baseline, atmospheric delay anomalies, and possible surface deformation because of tectonic, volcanic, or other sources during the time interval spanned by the images. This chapter presents practical solutions to identify and remove various artifacts in repeat-pass satellite InSAR images to generate a high-quality DEM.

Evaluating the Analgesic Effect of the GLS Inhibitor 6-Diazo-5-Oxo-L-Norleucine in Vivo

PubMed Central

Crosby, Heith A; Miller, Kenneth E

2018-01-01

Glutamate is an excitatory neurotransmitter, produced by its synthetic enzyme, glutaminase (GLS), and packaged by vesicular transporters (VGluT2) into synaptic vesicles. Primary sensory peripheral nerve and spinal synaptic terminals release glutamate during nociceptive (pain) signaling. In post-incisional and inflammation models in rats, GLS and VGluT2 production is elevated in dorsal root ganglion neuronal cell bodies and transported to peripheral and spinal terminals for increased glutamate synthesis and release. 6-Diazo-5-oxo-l-norleucine (DON) is a GLS inhibitor that produces long lasting pain relief when applied to the inflamed paw of arthritic rats, but its effect in a post-incisional model has not been evaluated. In this study, we examined the analgesic efficacy of DON in a surgical incision model by measuring thermal latency and mechanical allodynia. Following behavioral evaluation, we examined the skin for VGluT2, GLS and glutamate immunoreactivity (ir). Our findings revealed that VGluT2-ir is elevated in the stratum lucidum by approximately 19%, 64 hours post-surgical incision and attenuated by approximately 5.4% after the administration of DON. During that same period GLS-ir was elevated in dermal nerve fibers by 52% and was attenuated by approximately 27.9% after the application of DON. Additionally, glutamate-ir was elevated in epidermal nerve fibers by 35% after incision and attenuated by approximately 23% after the administration of DON. Behavioral testing 24 and 48 hours after a single local administration of DON showed five out of six animals having an analgesic response to mechanical allodynia, but not to thermal hyperalgesia. Following a surgical incision, the area of injury shows increased VGluT2-, GLS-, glutamate-ir, mechanical allodynia and no change in thermal latency. After the application of the GLS inhibitor, DON, nerve fiber of the skin showed decreased VGluT2, GLS, and glutamate-ir. Furthermore, post-incision DON treated animals exhibited decreased mechanical allodynia with no change in thermal latency when compared to control animals. PMID:29888760

Vertical normal modes of a mesoscale model using a scaled height coordinate

NASA Technical Reports Server (NTRS)

Lipton, A. E.; Pielke, R. A.

1986-01-01

Vertical modes were derived for a version of the Colorado State Regional Atmospheric Mesoscale Modeling System. The impacts of three options for dealing with the upper boundary of the model were studied. The standard model formulation holds pressure constant at a fixed altitude near the model top, and produces a fastest mode with a speed of about 90 m/sec. An alternative formulation, which allows for an external mode, could require recomputation of vertical modes for every surface elevation on the horizontal grid unless the modes are derived in a particular way. These results have bearing on the feasibility of applying vertical mode initialization to models with scaled height coordinates.

Water Futures for Cold Mountain Ecohydrology under Climate Change - Results from the North American Cordilleran Transect

NASA Astrophysics Data System (ADS)

Rasouli, K.; Pomeroy, J. W.; Fang, X.; Whitfield, P. H.; Marks, D. G.; Janowicz, J. R.

2017-12-01

A transect comprising three intensively researched mountain headwater catchments stretching from the northern US to northern Canada provides the basis to downscale climate models outputs for mountain hydrology and insight for an assessment of water futures under changing climate and vegetation using a physically based hydrological model. Reynolds Mountain East, Idaho; Marmot Creek, Alberta and Wolf Creek, Yukon are high mountain catchments dominated by forests and alpine shrub and grass vegetation with long-term snow, hydrometric and meteorological observations and extensive ecohydrological process studies. The physically based, modular, flexible and object-oriented Cold Regions Hydrological Modelling Platform (CRHM) was used to create custom spatially distributed hydrological models for these three catchments. Model parameterisations were based on knowledge of hydrological processes, basin physiography, soils and vegetation with minimal or no calibration from streamflow measurements. The models were run over multidecadal periods using high-elevation meteorological observations to assess the recent ecohydrological functioning of these catchments. The results showed unique features in each catchment, from snowdrift-fed aspen pocket forests in Reynolds Mountain East, to deep late-lying snowdrifts at treeline larch forests in Marmot Creek, and snow-trapping shrub tundra overlying discontinuous permafrost in Wolf Creek. The meteorological observations were then perturbed using the changes in monthly temperature and precipitation predicted by the NARCCAP modelling outputs for the mid-21st C. In all catchments there is a dramatic decline in snow redistribution and sublimation by wind and of snow interception by and sublimation from evergreen canopies that is associated with warmer winters. Reduced sublimation loss only partially compensated for greater rainfall fractions of precipitation. Under climate change, snowmelt was earlier and slower and at the lowest elevations and latitudes produced less proportion of runoff from snowmelt. Transient vegetation changes counteracted increasing streamflow yields from climate change partly due to increased snow retention by enhanced vegetation heights at high elevations and reduced vegetation canopy coverage at low elevations.

Assessing the quality of digital elevation models obtained from mini unmanned aerial vehicles for overland flow modelling in urban areas

NASA Astrophysics Data System (ADS)

Leitão, João P.; Moy de Vitry, Matthew; Scheidegger, Andreas; Rieckermann, Jörg

2016-04-01

Precise and detailed digital elevation models (DEMs) are essential to accurately predict overland flow in urban areas. Unfortunately, traditional sources of DEM, such as airplane light detection and ranging (lidar) DEMs and point and contour maps, remain a bottleneck for detailed and reliable overland flow models, because the resulting DEMs are too coarse to provide DEMs of sufficient detail to inform urban overland flows. Interestingly, technological developments of unmanned aerial vehicles (UAVs) suggest that they have matured enough to be a competitive alternative to satellites or airplanes. However, this has not been tested so far. In this study we therefore evaluated whether DEMs generated from UAV imagery are suitable for urban drainage overland flow modelling. Specifically, 14 UAV flights were conducted to assess the influence of four different flight parameters on the quality of generated DEMs: (i) flight altitude, (ii) image overlapping, (iii) camera pitch, and (iv) weather conditions. In addition, we compared the best-quality UAV DEM to a conventional lidar-based DEM. To evaluate both the quality of the UAV DEMs and the comparison to lidar-based DEMs, we performed regression analysis on several qualitative and quantitative metrics, such as elevation accuracy, quality of object representation (e.g. buildings, walls and trees) in the DEM, which were specifically tailored to assess overland flow modelling performance, using the flight parameters as explanatory variables. Our results suggested that, first, as expected, flight altitude influenced the DEM quality most, where lower flights produce better DEMs; in a similar fashion, overcast weather conditions are preferable, but weather conditions and other factors influence DEM quality much less. Second, we found that for urban overland flow modelling, the UAV DEMs performed competitively in comparison to a traditional lidar-based DEM. An important advantage of using UAVs to generate DEMs in urban areas is their flexibility that enables more frequent, local, and affordable elevation data updates, allowing, for example, to capture different tree foliage conditions.

Trigeminal Inflammatory Compression (TIC) Injury Induces Chronic Facial Pain and Susceptibility to Anxiety-Related Behaviors

PubMed Central

Lyons, Danielle N.; Kniffin, Tracey C.; Zhang, Liping; Danaher, Robert J.; Miller, Craig S.; Bocanegra, Jose L.; Carlson, Charles R.; Westlund, Karin N.

2015-01-01

Our laboratory previously developed a novel neuropathic and inflammatory facial pain model for mice referred to as the Trigeminal Inflammatory Compression (TIC) model. Rather than inducing whole nerve ischemia and neuronal loss, this injury induces only slight peripheral nerve demyelination triggering long-term mechanical allodynia and cold hypersensitivity on the ipsilateral whisker pad. The aim of the present study is to further characterize the phenotype of the TIC injury model using specific behavioral assays (i.e. light-dark box, open field exploratory activity, and elevated plus maze) to explore pain- and anxiety-like behaviors associated with this model. Our findings determined that the TIC injury produces hypersensitivity 100% of the time after surgery that persists at least 21 weeks post injury (until the animals are euthanized). Three receptive field sensitivity pattern variations in mice with TIC injury are specified. Animals with TIC injury begin displaying anxiety-like behavior in the light-dark box preference and open field exploratory tests at week 8 post injury as compared to sham and naïve animals. Panic anxiety-like behavior was shown in the elevated plus maze in mice with TIC injury if the test was preceded with acoustic startle. Thus, in addition to mechanical and cold hypersensitivity, the present study identified significant anxiety-like behaviors in mice with TIC injury which resembling the clinical symptomatology and psychosocial impairments of patients with chronic facial pain. Overall, the TIC injury model’s chronicity, reproducibility, and reliability in producing pain- and anxiety-like behaviors demonstrate its usefulness as a chronic neuropathic facial pain model. PMID:25818051

Test anxiety and cardiovascular responses to daily academic stressors.

PubMed

Conley, Kristen M; Lehman, Barbara J

2012-02-01

Routine academic events may cause stress and produce temporary elevations in blood pressure. Students who experience test anxiety may be especially prone to cardiovascular activation in response to academic stress. This study drew on self-reported stress and ambulatory blood pressure measurements provided by 99 undergraduate participants (30% men, mean age=21 years) who participated over 4 days. Posture, activity level, recent consumption and the previous same-day reading were considered as covariates in a series of hierarchical linear models. Results indicate elevations in systolic blood pressure at times of acute academic stressors; neither diastolic blood pressure nor heart rate was linked with academic stress. In addition, those participants higher in test anxiety exhibited especially pronounced elevations in systolic blood pressure during times of acute academic stress. This research suggests that everyday academic stressors are linked with temporary increases in blood pressure and that test anxiety may contribute to these elevations. Test anxiety has implications for future academic and job success, and cardiovascular responses to everyday stress may contribute to health problems later in life. Copyright © 2011 John Wiley & Sons, Ltd.

Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987.

PubMed

Korsgaard, Niels J; Nuth, Christopher; Khan, Shfaqat A; Kjeldsen, Kristian K; Bjørk, Anders A; Schomacker, Anders; Kjær, Kurt H

2016-05-10

Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978-1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25 m gridded DEM and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps.

Digital elevation model and orthophotographs of Greenland based on aerial photographs from 1978-1987

NASA Astrophysics Data System (ADS)

Korsgaard, Niels J.; Nuth, Christopher; Khan, Shfaqat A.; Kjeldsen, Kristian K.; Bjørk, Anders A.; Schomacker, Anders; Kjær, Kurt H.

2016-05-01

Digital Elevation Models (DEMs) play a prominent role in glaciological studies for the mass balance of glaciers and ice sheets. By providing a time snapshot of glacier geometry, DEMs are crucial for most glacier evolution modelling studies, but are also important for cryospheric modelling in general. We present a historical medium-resolution DEM and orthophotographs that consistently cover the entire surroundings and margins of the Greenland Ice Sheet 1978-1987. About 3,500 aerial photographs of Greenland are combined with field surveyed geodetic ground control to produce a 25 m gridded DEM and a 2 m black-and-white digital orthophotograph. Supporting data consist of a reliability mask and a photo footprint coverage with recording dates. Through one internal and two external validation tests, this DEM shows an accuracy better than 10 m horizontally and 6 m vertically while the precision is better than 4 m. This dataset proved successful for topographical mapping and geodetic mass balance. Other uses include control and calibration of remotely sensed data such as imagery or InSAR velocity maps.

California's Snow Gun and its implications for mass balance predictions under greenhouse warming

NASA Astrophysics Data System (ADS)

Howat, I.; Snyder, M.; Tulaczyk, S.; Sloan, L.

2003-12-01

Precipitation has received limited treatment in glacier and snowpack mass balance models, largely due to the poor resolution and confidence of precipitation predictions relative to temperature predictions derived from atmospheric models. Most snow and glacier mass balance models rely on statistical or lapse rate-based downscaling of general or regional circulation models (GCM's and RCM's), essentially decoupling sub-grid scale, orographically-driven evolution of atmospheric heat and moisture. Such models invariably predict large losses in the snow and ice volume under greenhouse warming. However, positive trends in the mass balance of glaciers in some warming maritime climates, as well as at high elevations of the Greenland Ice Sheet, suggest that increased precipitation may play an important role in snow- and glacier-climate interactions. Here, we present a half century of April snowpack data from the Sierra Nevada and Cascade mountains of California, USA. This high-density network of snow-course data indicates that a gain in winter snow accumulation at higher elevations has compensated loss in snow volume at lower elevations by over 50% and has led to glacier expansion on Mt. Shasta. These trends are concurrent with a region-wide increase in winter temperatures up to 2° C. They result from the orographic lifting and saturation of warmer, more humid air leading to increased precipitation at higher elevations. Previous studies have invoked such a "Snow Gun" effect to explain contemporaneous records of Tertiary ocean warming and rapid glacial expansion. A climatological context of the California's "snow gun" effect is elucidated by correlation between the elevation distribution of April SWE observations and the phase of the Pacific Decadal Oscillation and the El Nino Southern Oscillation, both controlling the heat and moisture delivered to the U.S. Pacific coast. The existence of a significant "Snow Gun" effect presents two challenges to snow and glacier mass balance modeling. Firstly, the link between amplification of orographic precipitation and the temporal evolution of ocean-climate oscillations indicates that prediction of future mass balance trends requires consideration of the timing and amplitude of such oscillations. Only recently have ocean-atmosphere models begun to realistically produce such temporal variability. Secondly, the steepening snow mass-balance elevation-gradient associated with the "Snow Gun" implies greater spatial variability in balance with warming. In a warming climate, orographic processes at a scale finer that the highest resolution RCM (>20km grid) become increasingly important and predictions based on lower elevations become increasingly inaccurate for higher elevations. Therefore, thermodynamic interaction between atmospheric heat, moisture and topography must be included in downscaling techniques. In order to demonstrate the importance of the thermodynamic downscaling in mass balance predictions, we nest a high-resolution (100m grid), coupled Orographic Precipitation and Surface Energy balance Model (OPSEM) into the RegC2.5 RCM (40 km grid) and compare results. We apply this nesting technique to Mt. Shasta, California, an area of high topography (~4000m) relative to its RegCM2.5 grid elevation (1289m). These models compute average April snow volume under present and doubled-present Atmospheric CO2 concentrations. While the RegCM2.5 regional model predicts an 83% decrease in April SWE, OPSEM predicts a 16% increase. These results indicate that thermodynamic interactions between the atmosphere and topography at sub- RCM grid resolution must be considered in mass balance models.

Elevated carbon dioxide alters the relative fitness of Taraxacum officinale genotypes

USDA-ARS?s Scientific Manuscript database

I tested whether elevated carbon dioxide concentration differentially affected which genotypes of the apomictic species dandelion produced the largest number of viable seeds in two different field experiments, and identified morphological and physiological traits associated with fitness at elevated ...

Supersonic aerodynamic characteristics of a circular body Earth-to-Orbit vehicle

NASA Technical Reports Server (NTRS)

Ware, George M.; Engelund, Walter C.; Macconochie, Ian O.

1994-01-01

The circular body configuration is a generic single- or multi-stage reusable Earth-to-orbit transport. A thick clipped-delta wing is the major lifting surface. For directional control, three different vertical fin arrangements were investigated: a conventional aft-mounted center fin, wingtip fins, and a nose-mounted fin. The tests were conducted in the Langley Unitary Plan Wind Tunnel. The configuration is longitudinally stable about the estimated center of gravity of 0.72 body length up to a Mach number of about 3.0. Above Mach 3.0, the model is longitudinally unstable at low angles of attack but has a stable secondary trim point at angles of attack above 30 deg. The model has sufficient pitch control authority with elevator and body flap to produce stable trim over the test range. The model with the center fin is directionally stable at low angles of attack up to a Mach number of 3.90. The rudder-like surfaces on the tip fins and the all-movable nose fin are designed as active controls to produce artificial directional stability and are effective in producing yawing moment. The wing trailing-edge aileron surfaces are effective in producing rolling moment, but they also produce large adverse yawing moment.

Fewer not more leaves - Key to obtaining the needed jump in crop yield potential and water use efficiency

NASA Astrophysics Data System (ADS)

Srinivasan, V.; Kumar, P.; Long, S.

2013-12-01

Word food and feed supply needs to increase by 75% by 2050 to meet the increasing demands of our growing population. Soybean which is the world`s fourth most important crop in terms of total production at 250 million Mt/yr is a key protein source, and together with rice and wheat, are experiencing declining global yield increases year on year. At present rates of improvement, 2050 targets cannot be reached without new innovations. In this study we demonstrate an innovative approach that could provide a yield jump. While, natural selection favors individual plants to maximize leaf production to maximize light interception and shade competitors, the presence of this trait in domestic crops could be disadvantageous. In addition, rising CO2 causes increased leaf production further exacerbating the problem. Here, we show by mathematical model and field experiment that, a modern cultivar growing at the center of US soy cultivation produces too many leaves and reduction to an optimal level would increase yield. Our model results indicate that an LAI of 3.5 and 3.8 produces maximal rates of net canopy assimilation under ambient and elevated CO2 conditions respectively. However, observed peak LAI values are 6.9 and 7.5 under ambient and elevated CO2 conditions respectively. This results in a NPP loss of 30% and 20% under ambient and elevated CO2 conditions respectively. Furthermore, the optimal LAI results in a decreased transpiration of up to 30% thus increasing water use efficiency. We show that as LAI increases, the tradeoffs between diminishing day time gains in NPP, and increasing losses in respiration is responsible for this effect. By designing a more optimum canopy, we can increase NPP and this potentially translates to increased seed yield. To test this model result, we perform canopy manipulation experiments on soybean plants, where we artificially decrease LAI by periodically removing young and emerging leaves throughout the growing season (after pod onset), and measure the seed yield under ambient and elevated CO2 conditions. Our experimental results show that an LAI reduction of 0.5 results in an increased seed yield of 8.1% validating our model results. We propose that, by achieving a stronger LAI reduction, we can improve seed yields by up to 24% providing the much needed jump in yield to achieve future food security.

Detection of ingested nitromethane and reliable creatinine assessment using multiple common analytical methods.

PubMed

Murphy, Christine M; Devlin, John J; Beuhler, Michael C; Cheifetz, Paul; Maynard, Susan; Schwartz, Michael D; Kacinko, Sherri

2018-04-01

Nitromethane, found in fuels used for short distance racing, model cars, and model airplanes, produces a falsely elevated serum creatinine with standard creatinine analysis via the Jaffé method. Erroneous creatinine elevation often triggers extensive testing, leads to inaccurate diagnoses, and delayed or inappropriate medical interventions. Multiple reports in the literature identify "enzymatic assays" as an alternative method to detect the true value of creatinine, but this ambiguity does not help providers translate what type of enzymatic assay testing can be done in real time to determine if there is indeed false elevation. We report seven cases of ingested nitromethane where creatinine was determined via Beckman Coulter ® analyser using the Jaffé method, Vitros ® analyser, or i-Stat ® point-of-care testing. Nitromethane was detected and semi-quantified using a common clinical toxic alcohol analysis method, and quantified by headspace-gas chromatography-mass spectrometry. When creatinine was determined using i-Stat ® point-of-care testing or a Vitros ® analyser, levels were within the normal range. Comparatively, all initial creatinine levels obtained via the Jaffé method were elevated. Nitromethane concentrations ranged from 42 to 310 μg/mL. These cases demonstrate reliable assessment of creatinine through other enzymatic methods using a Vitros ® analyser or i-STAT ® . Additionally, nitromethane is detectable and quantifiable using routine alcohols gas chromatography analysis and by headspace-gas chromatography-mass spectrometry.

Geometric correction and digital elevation extraction using multiple MTI datasets

USGS Publications Warehouse

Mercier, Jeffrey A.; Schowengerdt, Robert A.; Storey, James C.; Smith, Jody L.

2007-01-01

Digital Elevation Models (DEMs) are traditionally acquired from a stereo pair of aerial photographs sequentially captured by an airborne metric camera. Standard DEM extraction techniques can be naturally extended to satellite imagery, but the particular characteristics of satellite imaging can cause difficulties. The spacecraft ephemeris with respect to the ground site during image collects is the most important factor in the elevation extraction process. When the angle of separation between the stereo images is small, the extraction process typically produces measurements with low accuracy, while a large angle of separation can cause an excessive number of erroneous points in the DEM from occlusion of ground areas. The use of three or more images registered to the same ground area can potentially reduce these problems and improve the accuracy of the extracted DEM. The pointing capability of some sensors, such as the Multispectral Thermal Imager (MTI), allows for multiple collects of the same area from different perspectives. This functionality of MTI makes it a good candidate for the implementation of a DEM extraction algorithm using multiple images for improved accuracy. Evaluation of this capability and development of algorithms to geometrically model the MTI sensor and extract DEMs from multi-look MTI imagery are described in this paper. An RMS elevation error of 6.3-meters is achieved using 11 ground test points, while the MTI band has a 5-meter ground sample distance.

Sensitivity of potential evapotranspiration and simulated flow to varying meteorological inputs, Salt Creek watershed, DuPage County, Illinois

USGS Publications Warehouse

Whitbeck, David E.

2006-01-01

The Lamoreux Potential Evapotranspiration (LXPET) Program computes potential evapotranspiration (PET) using inputs from four different meteorological sources: temperature, dewpoint, wind speed, and solar radiation. PET and the same four meteorological inputs are used with precipitation data in the Hydrological Simulation Program-Fortran (HSPF) to simulate streamflow in the Salt Creek watershed, DuPage County, Illinois. Streamflows from HSPF are routed with the Full Equations (FEQ) model to determine water-surface elevations. Consequently, variations in meteorological inputs have potential to propagate through many calculations. Sensitivity of PET to variation was simulated by increasing the meteorological input values by 20, 40, and 60 percent and evaluating the change in the calculated PET. Increases in temperatures produced the greatest percent changes, followed by increases in solar radiation, dewpoint, and then wind speed. Additional sensitivity of PET was considered for shifts in input temperatures and dewpoints by absolute differences of ?10, ?20, and ?30 degrees Fahrenheit (degF). Again, changes in input temperatures produced the greatest differences in PET. Sensitivity of streamflow simulated by HSPF was evaluated for 20-percent increases in meteorological inputs. These simulations showed that increases in temperature produced the greatest change in flow. Finally, peak water-surface elevations for nine storm events were compared among unmodified meteorological inputs and inputs with values predicted 6, 24, and 48 hours preceding the simulated peak. Results of this study can be applied to determine how errors specific to a hydrologic system will affect computations of system streamflow and water-surface elevations.

An application of the MPP to the interactive manipulation of stereo images of digital terrain models

NASA Technical Reports Server (NTRS)

Pol, Sanjay; Mcallister, David; Davis, Edward

1987-01-01

Massively Parallel Processor algorithms were developed for the interactive manipulation of flat shaded digital terrain models defined over grids. The emphasis is on real time manipulation of stereo images. Standard graphics transformations are applied to a 128 x 128 grid of elevations followed by shading and a perspective projection to produce the right eye image. The surface is then rendered using a simple painter's algorithm for hidden surface removal. The left eye image is produced by rotating the surface 6 degs about the viewer's y axis followed by a perspective projection and rendering of the image as described above. The left and right eye images are then presented on a graphics device using standard stereo technology. Performance evaluations and comparisons are presented.

Mapping of Polar Areas Based on High-Resolution Satellite Images: The Example of the Henryk Arctowski Polish Antarctic Station

NASA Astrophysics Data System (ADS)

Kurczyński, Zdzisław; Różycki, Sebastian; Bylina, Paweł

2017-12-01

To produce orthophotomaps or digital elevation models, the most commonly used method is photogrammetric measurement. However, the use of aerial images is not easy in polar regions for logistical reasons. In these areas, remote sensing data acquired from satellite systems is much more useful. This paper presents the basic technical requirements of different products which can be obtain (in particular orthoimages and digital elevation model (DEM)) using Very-High-Resolution Satellite (VHRS) images. The study area was situated in the vicinity of the Henryk Arctowski Polish Antarctic Station on the Western Shore of Admiralty Bay, King George Island, Western Antarctic. Image processing was applied on two triplets of images acquired by the Pléiades 1A and 1B in March 2013. The results of the generation of orthoimages from the Pléiades systems without control points showed that the proposed method can achieve Root Mean Squared Error (RMSE) of 3-9 m. The presented Pléiades images are useful for thematic remote sensing analysis and processing of measurements. Using satellite images to produce remote sensing products for polar regions is highly beneficial and reliable and compares well with more expensive airborne photographs or field surveys.

Thermodynamic sensitivities in observed and simulated extreme-rain-producing mesoscale convective systems

NASA Astrophysics Data System (ADS)

Schumacher, R. S.; Peters, J. M.

2015-12-01

Mesoscale convective systems (MCSs) are responsible for a large fraction of warm-season extreme rainfall events over the continental United States, as well as other midlatitude regions globally. The rainfall production in these MCSs is determined by numerous factors, including the large-scale forcing for ascent, the organization of the convection, cloud microphysical processes, and the surrounding thermodynamic and kinematic environment. Furthermore, heavy-rain-producing MCSs are most common at night, which means that well-studied mechanisms for MCS maintenance and organization such as cold pools (gravity currents) are not always at work. In this study, we use numerical model simulations and recent field observations to investigate the sensitivity of low-level MCS structures, and their influences on rainfall, to the details of the thermodynamic environment. In particular, small alterations to the initial conditions in idealized and semi-idealized simulations result in comparatively large precipitation changes, both in terms of the intensity and the spatial distribution. The uncertainties in the thermodynamic enviroments in the model simulations will be compared with high-resolution observations from the Plains Elevated Convection At Night (PECAN) field experiment in 2015. The results have implications for the paradigms of "surface-based" versus "elevated" convection, as well as for the predictability of warm-season convective rainfall.

Trigeminal Inflammatory Compression (TIC) injury induces chronic facial pain and susceptibility to anxiety-related behaviors.

PubMed

Lyons, D N; Kniffin, T C; Zhang, L P; Danaher, R J; Miller, C S; Bocanegra, J L; Carlson, C R; Westlund, K N

2015-06-04

Our laboratory previously developed a novel neuropathic and inflammatory facial pain model for mice referred to as the Trigeminal Inflammatory Compression (TIC) model. Rather than inducing whole nerve ischemia and neuronal loss, this injury induces only slight peripheral nerve demyelination triggering long-term mechanical allodynia and cold hypersensitivity on the ipsilateral whisker pad. The aim of the present study is to further characterize the phenotype of the TIC injury model using specific behavioral assays (i.e. light-dark box, open field exploratory activity, and elevated plus maze) to explore pain- and anxiety-like behaviors associated with this model. Our findings determined that the TIC injury produces hypersensitivity 100% of the time after surgery that persists at least 21 weeks post injury (until the animals are euthanized). Three receptive field sensitivity pattern variations in mice with TIC injury are specified. Animals with TIC injury begin displaying anxiety-like behavior in the light-dark box preference and open field exploratory tests at week eight post injury as compared to sham and naïve animals. Panic anxiety-like behavior was shown in the elevated plus maze in mice with TIC injury if the test was preceded with acoustic startle. Thus, in addition to mechanical and cold hypersensitivity, the present study identified significant anxiety-like behaviors in mice with TIC injury resembling the clinical symptomatology and psychosocial impairments of patients with chronic facial pain. Overall, the TIC injury model's chronicity, reproducibility, and reliability in producing pain- and anxiety-like behaviors demonstrate its usefulness as a chronic neuropathic facial pain model. Copyright © 2015 IBRO. Published by Elsevier Ltd. All rights reserved.

Base of the upper layer of the phase-three Elkhorn-Loup groundwater-flow model, north-central Nebraska

USGS Publications Warehouse

Stanton, Jennifer S.

2013-01-01

The Elkhorn and Loup Rivers in Nebraska provide water for irrigation, recreation, hydropower produc­tion, aquatic life, and municipal water systems for the Omaha and Lincoln metropolitan areas. Groundwater is another important resource in the region and is extracted primarily for agricultural irrigation. Water managers of the area are interested in balancing and sustaining the long-term uses of these essential surface-water and groundwater resources. Thus, a cooperative study was established in 2006 to compile reliable data describing hydrogeologic properties and water-budget components and to improve the understanding of stream-aquifer interactions in the Elkhorn and Loup River Basins. A groundwater-flow model was constructed as part of the first two phases of that study as a tool for under­standing the effect of groundwater pumpage on stream base flow and the effects of management strategies on hydrologically connected groundwater and surface-water supplies. The third phase of the study was implemented to gain additional geologic knowledge and update the ELM with enhanced water-budget information and refined discretization of the model grid and stress periods. As part of that effort, the ELM is being reconstructed to include two vertical model layers, whereas phase-one and phase-two simulations represented the aquifer system using one vertical model layer. This report presents a map of and methods for developing the elevation of the base of the upper model layer for the phase-three ELM. Digital geospatial data of elevation contours and geologic log sites used to esti­mate elevation contours are available as part of this report.

Potential indirect effects of aerosol on tropical cyclone development

NASA Astrophysics Data System (ADS)

Krall, Geoffrey

Observational and model evidence suggest that a 2008 Western Pacific typhoon (NURI) came into contact with and ingested elevated concentrations of aerosol as it neared the Chinese coast. This study uses a regional model with two-moment bin emulating microphysics to simulate the typhoon as it enters the field of elevated aerosol concentration. A continental field of cloud condensation nuclei (CCN) was prescribed based on satellite and global aerosol model output, then increased for further sensitivity tests. The typhoon was simulated for 96 hours beginning 17 August 2008, the final 60 of which were under varying CCN concentrations as it neared the Philippines and coastal China. The model was initialized with both global reanalysis model data and irregularly spaced dropsonde data from a 2008 observational campaign using an objective analysis routine. At 36 hours, the internal nudging of the model was switched off and allowed to evolve on its own. As the typhoon entered the field of elevated CCN in the sensitivity tests, the presence of additional CCN resulted in a significant perturbation of windspeed, convective fluxes, and hydrometeor species behavior. Initially ingested in the outer rainbands of the storm, the additional CCN resulted in an initial damping and subsequent invigoration of convection. The increase in convective fluxes strongly lag-correlates with increased amounts of supercooled liquid water within the storm domain. As the convection intensified in the outer rainbands the storm drifted over the developing cold-pools, affecting the inflow of air into the convective towers of the typhoon. Changes in the timing and amount of rain produced in each simulation resulted in differing cold-pool strengths and size. The presence of additional CCN increased resulted in an amplification of convection within the storm, except for the extremely high CCN concentration simulation, which showed a damped convection due to the advection of pristine ice away from the storm. This study examines the physical mechanisms that could potentially alter a tropical cyclone (TC) in intensity and dynamics upon ingesting elevated levels of CCN.

Identification of glutathione adducts of α-chlorofatty aldehydes produced in activated neutrophils.

PubMed

Duerr, Mark A; Aurora, Rajeev; Ford, David A

2015-05-01

α-Chlorofatty aldehydes (α-ClFALDs) are produced by hypochlorous acid targeting plasmalogens during neutrophil activation. This study investigated the reaction of the α-chlorinated carbon of α-ClFALD with the nucleophile, GSH. Utilizing ESI/MS/MS, the reaction product of GSH and the 16-carbon α-ClFALD, 2-chlorohexadecanal (2-ClHDA), was characterized. The resulting conjugate of 2-ClHDA and GSH (HDA-GSH) has an intact free aldehyde, and the chlorine at the α-carbon is ejected. Stable isotope-labeled [d4]HDA-GSH was synthesized, which further confirmed the structure, and was used to quantify natural α-ClFALD conjugates of GSH (FALD-GSH) using reverse-phase LC with detection by ESI/MS/MS using selected reaction monitoring. HDA-GSH is elevated in RAW 264.7 cells treated with physiologically relevant concentrations of exogenous 2-ClHDA. Furthermore, PMA-treated primary human neutrophils have elevated levels of HDA-GSH and the conjugate of 2-chlorooctadecanal (2-ClODA) and GSH (ODA-GSH), as well as elevated levels of 2-ClHDA and 2-ClODA. Production of both conjugates in PMA-stimulated neutrophils was reduced by 3-aminotriazole pretreatment, which also blocks endogenous α-ClFALD production. Additionally, plasma FALD-GSH levels were elevated in the K/BxN mouse arthritis model. Taken together, these studies demonstrate novel peptidoaldehydes derived from GSH and α-ClFALD in activated human neutrophils and in vivo in K/BxN mice. Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.

Snowmelt response to simulated warming across a large elevation gradient, southern Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Musselman, Keith N.; Molotch, Noah P.; Margulis, Steven A.

2017-12-01

In a warmer climate, the fraction of annual meltwater produced at high melt rates in mountainous areas is projected to decline due to a contraction of the snow-cover season, causing melt to occur earlier and under lower energy conditions. How snowmelt rates, including extreme events relevant to flood risk, may respond to a range of warming over a mountain front is poorly known. We present a model sensitivity study of snowmelt response to warming across a 3600 m elevation gradient in the southern Sierra Nevada, USA. A snow model was run for three distinct years and verified against extensive ground observations. To simulate the impact of climate warming on meltwater production, measured meteorological conditions were modified by +1 to +6 °C. The total annual snow water volume exhibited linear reductions (-10 % °C-1) consistent with previous studies. However, the sensitivity of snowmelt rates to successive degrees of warming varied nonlinearly with elevation. Middle elevations and years with more snowfall were prone to the largest reductions in snowmelt rates, with lesser changes simulated at higher elevations. Importantly, simulated warming causes extreme daily snowmelt (99th percentiles) to increase in spatial extent and intensity, and shift from spring to winter. The results offer insight into the sensitivity of mountain snow water resources and how the rate and timing of water availability may change in a warmer climate. The identification of future climate conditions that may increase extreme melt events is needed to address the climate resilience of regional flood control systems.

An Experimental Real-Time Ocean Nowcast/Forecast System for Intra America Seas

NASA Astrophysics Data System (ADS)

Ko, D. S.; Preller, R. H.; Martin, P. J.

2003-04-01

An experimental real-time Ocean Nowcast/Forecast System has been developed for the Intra America Seas (IASNFS). The area of coverage includes the Caribbean Sea, the Gulf of Mexico and the Straits of Florida. The system produces nowcast and up to 72 hours forecast the sea level variation, 3D ocean current, temperature and salinity fields. IASNFS consists an 1/24 degree (~5 km), 41-level sigma-z data-assimilating ocean model based on NCOM. For daily nowcast/forecast the model is restarted from previous nowcast. Once model is restarted it continuously assimilates the synthetic temperature/salinity profiles generated by a data analysis model called MODAS to produce nowcast. Real-time data come from satellite altimeter (GFO, TOPEX/Poseidon, ERS-2) sea surface height anomaly and AVHRR sea surface temperature. Three hourly surface heat fluxes, including solar radiation, wind stresses and sea level air pressure from NOGAPS/FNMOC are applied for surface forcing. Forecasts are produced with available NOGAPS forecasts. Once the nowcast/forecast are produced they are distributed through the Internet via the updated web pages. The open boundary conditions including sea surface elevation, transport, temperature, salinity and currents are provided by the NRL 1/8 degree Global NCOM which is operated daily. An one way coupling scheme is used to ingest those boundary conditions into the IAS model. There are 41 rivers with monthly discharges included in the IASNFS.

Generating High-Resolution Lake Bathymetry over Lake Mead using the ICESat-2 Airborne Simulator

NASA Astrophysics Data System (ADS)

Li, Y.; Gao, H.; Jasinski, M. F.; Zhang, S.; Stoll, J.

2017-12-01

Precise lake bathymetry (i.e., elevation/contour) mapping is essential for optimal decision making in water resources management. Although the advancement of remote sensing has made it possible to monitor global reservoirs from space, most of the existing studies focus on estimating the elevation, area, and storage of reservoirs—and not on estimating the bathymetry. This limitation is attributed to the low spatial resolution of satellite altimeters. With the significant enhancement of ICESat-2—the Ice, Cloud & Land Elevation Satellite #2, which is scheduled to launch in 2018—producing satellite-based bathymetry becomes feasible. Here we present a pilot study for deriving the bathymetry of Lake Mead by combining Landsat area estimations with airborne elevation data using the prototype of ICESat-2—the Multiple Altimeter Beam Experimental Lidar (MABEL). First, an ISODATA classifier was adopted to extract the lake area from Landsat images during the period from 1982 to 2017. Then the lake area classifications were paired with MABEL elevations to establish an Area-Elevation (AE) relationship, which in turn was applied to the classification contour map to obtain the bathymetry. Finally, the Lake Mead bathymetry image was embedded onto the Shuttle Radar Topography Mission (SRTM) Digital Elevation Model (DEM), to replace the existing constant values. Validation against sediment survey data indicates that the bathymetry derived from this study is reliable. This algorithm has the potential for generating global lake bathymetry when ICESat-2 data become available after next year's launch.

Collapse susceptibility mapping in karstified gypsum terrain (Sivas basin - Turkey) by conditional probability, logistic regression, artificial neural network models

NASA Astrophysics Data System (ADS)

Yilmaz, Isik; Keskin, Inan; Marschalko, Marian; Bednarik, Martin

2010-05-01

This study compares the GIS based collapse susceptibility mapping methods such as; conditional probability (CP), logistic regression (LR) and artificial neural networks (ANN) applied in gypsum rock masses in Sivas basin (Turkey). Digital Elevation Model (DEM) was first constructed using GIS software. Collapse-related factors, directly or indirectly related to the causes of collapse occurrence, such as distance from faults, slope angle and aspect, topographical elevation, distance from drainage, topographic wetness index- TWI, stream power index- SPI, Normalized Difference Vegetation Index (NDVI) by means of vegetation cover, distance from roads and settlements were used in the collapse susceptibility analyses. In the last stage of the analyses, collapse susceptibility maps were produced from CP, LR and ANN models, and they were then compared by means of their validations. Area Under Curve (AUC) values obtained from all three methodologies showed that the map obtained from ANN model looks like more accurate than the other models, and the results also showed that the artificial neural networks is a usefull tool in preparation of collapse susceptibility map and highly compatible with GIS operating features. Key words: Collapse; doline; susceptibility map; gypsum; GIS; conditional probability; logistic regression; artificial neural networks.

Improvements to a global-scale groundwater model to estimate the water table across New Zealand

NASA Astrophysics Data System (ADS)

Westerhoff, Rogier; Miguez-Macho, Gonzalo; White, Paul

2017-04-01

Groundwater models at the global scale have become increasingly important in recent years to assess the effects of climate change and groundwater depletion. However, these global-scale models are typically not used for studies at the catchment scale, because they are simplified and too spatially coarse. In this study, we improved the global-scale Equilibrium Water Table (EWT) model, so it could better assess water table depth and water table elevation at the national scale for New Zealand. The resulting National Water Table (NWT) model used improved input data (i.e., national input data of terrain, geology, and recharge) and model equations (e.g., a hydraulic conductivity - depth relation). The NWT model produced maps of the water table that identified the main alluvial aquifers with fine spatial detail. Two regional case studies at the catchment scale demonstrated excellent correlation between the water table elevation and observations of hydraulic head. The NWT water tables are an improved water table estimation over the EWT model. In two case studies the NWT model provided a better approximation to observed water table for deep aquifers and the improved resolution of the model provided the capability to fill the gaps in data-sparse areas. This national model calculated water table depth and elevation across regional jurisdictions. Therefore, the model is relevant where trans-boundary issues, such as source protection and catchment boundary definition, occur. The NWT model also has the potential to constrain the uncertainty of catchment-scale models, particularly where data are sparse. Shortcomings of the NWT model are caused by the inaccuracy of input data and the simplified model properties. Future research should focus on improved estimation of input data (e.g., hydraulic conductivity and terrain). However, more advanced catchment-scale groundwater models should be used where groundwater flow is dominated by confining layers and fractures.

Developing flood-inundation maps for Johnson Creek, Portland, Oregon

USGS Publications Warehouse

Stonewall, Adam J.; Beal, Benjamin A.

2017-04-14

Digital flood-inundation maps were created for a 12.9‑mile reach of Johnson Creek by the U.S. Geological Survey (USGS). The flood-inundation maps depict estimates of water depth and areal extent of flooding from the mouth of Johnson Creek to just upstream of Southeast 174th Avenue in Portland, Oregon. Each flood-inundation map is based on a specific water level and associated streamflow at the USGS streamgage, Johnson Creek at Sycamore, Oregon (14211500), which is located near the upstream boundary of the maps. The maps produced by the USGS, and the forecasted flood hydrographs produced by National Weather Service River Forecast Center can be accessed through the USGS Flood Inundation Mapper Web site (http://wimcloud.usgs.gov/apps/FIM/FloodInundationMapper.html).Water-surface elevations were computed for Johnson Creek using a combined one-dimensional and two‑dimensional unsteady hydraulic flow model. The model was calibrated using data collected from the flood of December 2015 (including the calculated streamflows at two USGS streamgages on Johnson Creek) and validated with data from the flood of January 2009. Results were typically within 0.6 foot (ft) of recorded or measured water-surface elevations from the December 2015 flood, and within 0.8 ft from the January 2009 flood. Output from the hydraulic model was used to create eight flood inundation maps ranging in stage from 9 to 16 ft. Boundary condition hydrographs were identical in shape to those from the December 2015 flood event, but were scaled up or down to produce the amount of streamflow corresponding to a specific water-surface elevation at the Sycamore streamgage (14211500). Sensitivity analyses using other hydrograph shapes, and a version of the model in which the peak flow is maintained for an extended period of time, showed minimal variation, except for overbank areas near the Foster Floodplain Natural Area.Simulated water-surface profiles were combined with light detection and ranging (lidar) data collected in 2014 to delineate water-surface extents for each of the eight modeled stages. The availability of flood-inundation maps in conjunction with real-time data from the USGS streamgages along Johnson Creek and forecasted hydrographs from the National Weather Service Northwest River Forecast Center will provide residents of the watershed and emergency management personnel with valuable information that may aid in flood response, including potential evacuations, road closures, and mitigation efforts. In addition, these maps may be used for post-flood recovery efforts.

On the origin of the marine zinc-silicon correlation

NASA Astrophysics Data System (ADS)

de Souza, Gregory F.; Khatiwala, Samar P.; Hain, Mathis P.; Little, Susan H.; Vance, Derek

2018-06-01

The close linear correlation between the distributions of dissolved zinc (Zn) and silicon (Si) in seawater has puzzled chemical oceanographers since its discovery almost forty years ago, due to the apparent lack of a mechanism for coupling these two nutrient elements. Recent research has shown that such a correlation can be produced in an ocean model without any explicit coupling between Zn and Si, via the export of Zn-rich biogenic particles in the Southern Ocean, consistent with the observation of elevated Zn quotas in Southern Ocean diatoms. Here, we investigate the physical and biological mechanisms by which Southern Ocean uptake and export control the large-scale marine Zn distribution, using suites of sensitivity simulations in an ocean general circulation model (OGCM) and a box-model ensemble. These simulations focus on the sensitivity of the Zn distribution to the stoichiometry of Zn uptake relative to phosphate (PO4), drawing directly on observations in culture. Our analysis reveals that OGCM model variants that produce a well-defined step between relatively constant, high Zn:PO4 uptake ratios in the Southern Ocean and low Zn:PO4 ratios at lower latitudes fare best in reproducing the marine Zn-Si correlation at both the global and the regional Southern Ocean scale, suggesting the presence of distinct Zn-biogeochemical regimes in the high- and low-latitude oceans that may relate to differences in physiology, ecology or (micro-)nutrient status. Furthermore, a study of the systematics of both the box model and the OGCM reveals that regional Southern Ocean Zn uptake exerts control over the global Zn distribution via its modulation of the biogeochemical characteristics of the surface Southern Ocean. Specifically, model variants with elevated Southern Ocean Zn:PO4 uptake ratios produce near-complete Zn depletion in the Si-poor surface Subantarctic Zone, where upper-ocean water masses with key roles in the global oceanic circulation are formed. By setting the main preformed covariation trend within the ocean interior, the subduction of these Zn- and Si-poor water masses produces a close correlation between the Zn and Si distributions that is barely altered by their differential remineralisation during low-latitude cycling. We speculate that analogous processes in the high-latitude oceans may operate for other trace metal micronutrients as well, splitting the ocean into two fundamentally different biogeochemical, and thus biogeographic, regimes.

Skeletal unloading induces resistance to insulin-like growth factor I

NASA Technical Reports Server (NTRS)

Bikle, D. D.; Harris, J.; Halloran, B. P.; Morey-Holton, E. R.

1994-01-01

In previous studies with a hindlimb elevation model, we demonstrated that skeletal unloading transiently inhibits bone formation. This effect is limited to the unloaded bones (the normally loaded humerus does not cease growing), suggesting that local factors are of prime importance. IGF-I is one such factor; it is produced in bone and stimulates bone formation. To determine the impact of skeletal unloading on IGF-I production and function, we assessed the mRNA levels of IGF-I and its receptor (IGF-IR) in the proximal tibia and distal femur of growing rats during 2 weeks of hindlimb elevation. The mRNA levels for IGF-I and IGF-IR rose during hindlimb elevation, returning toward control values during recovery. This was accompanied by a 77% increase in IGF-I levels in the bone, peaking at day 10 of unloading. Changes in IGF binding protein levels were not observed. Infusion of IGF-I (200 micrograms/day) during 1 week of hindlimb elevation doubled the increase in bone mass of the control animals but failed to reverse the cessation of bone growth in the hindlimb-elevated animals. We conclude that skeletal unloading induces resistance to IGF-I, which may result secondarily in increased local production of IGF-I.

The influence of plantation and seed-source elevation on wood specific gravity of 29-year-old ponderosa pines

Treesearch

R. M. Echols; M. T. Conkle

1971-01-01

Genetic, environmental, and age effects were found in 29-yr-old ponderosa pine progenies from different elevational sources, when they were grown at 960, 2730, and 5650 ft elevation in the Sierra Nevada of California. Wood specific gravity decreased as elevation of seed parents increased, and all genotypes produced significantly lower specific gravity wood in the high-...

Mediterranean summer climate and the importance of Middle-East Topography

NASA Astrophysics Data System (ADS)

Simpson, Isla; Seager, Richard; Shaw, Tiffany; Ting, Mingfang

2015-04-01

In summer, the atmospheric circulation over the Mediterranean is characterized by localized intense subsidence and low level northerlies over the central- to eastern portion of the basin. Here, simulations with the Community Atmosphere Model, version 5 are used to investigate the influence of the elevated terrain of North Africa and the Middle East on this summertime circulation. This builds on previous work that recognized a role for North African topography in localizing the Mediterranean subsidence. By flattening the two regions of elevated terrain in the model it is demonstrated that, while they both conspire to produce about 30% of the summertime subsidence, contrary to previous work, the mountains of the Middle-East dominate in this topographic contribution by far. This topography, consisting primarily of the Zagros Mountain range, alters the circulation throughout the depth of the troposphere over the Mediterranean, and further East. The model results suggest that about 20% of the Mediterranean summertime moisture deficit can be attributed to this mountain induced circulation. This topography, therefore, plays an important role in the climate of the Mediterranean and the large scale circulation over the rest of Eurasia during the summer. Further stationary wave modelling reveals that the mountain influence is produced via mechanical forcing of the flow. The greatest influence of the topography occurs when the low level incident flow is easterly, as happens during the summer, primarily due to the presence of condensational heating over Asia. During other seasons, when the low level incident flow is westerly, the influence of Middle-East topography on the Mediterranean is negligible.

Inflammatory Biomarkers Predict Airflow Obstruction After Exposure to World Trade Center Dust

PubMed Central

Nolan, Anna; Naveed, Bushra; Comfort, Ashley L.; Ferrier, Natalia; Hall, Charles B.; Kwon, Sophia; Kasturiarachchi, Kusali J.; Cohen, Hillel W.; Zeig-Owens, Rachel; Glaser, Michelle S.; Webber, Mayris P.; Aldrich, Thomas K.; Rom, William N.; Kelly, Kerry; Prezant, David J.

2012-01-01

Background: The World Trade Center (WTC) collapse on September 11, 2001, produced airflow obstruction in a majority of firefighters receiving subspecialty pulmonary evaluation (SPE) within 6.5 years post-September 11, 2001. Methods: In a cohort of 801 never smokers with normal pre-September 11, 2001, FEV1, we correlated inflammatory biomarkers and CBC counts at monitoring entry within 6 months of September 11, 2001, with a median FEV1 at SPE (34 months; interquartile range, 25-57). Cases of airflow obstruction had FEV1 less than the lower limit of normal (LLN) (100 of 801; 70 of 100 had serum), whereas control subjects had FEV1 greater than or equal to LLN (153 of 801; 124 of 153 had serum). Results: From monitoring entry to SPE years later, FEV1 declined 12% in cases and increased 3% in control subjects. Case subjects had elevated serum macrophage derived chemokine (MDC), granulocyte-macrophage colony-stimulating factor (GM-CSF), granulocyte colony-stimulating factor, and interferon inducible protein-10 levels. Elevated GM-CSF and MDC increased the risk for subsequent FEV1 less than LLN by 2.5-fold (95% CI, 1.2-5.3) and 3.0-fold (95% CI, 1.4-6.1) in a logistic model adjusted for exposure, BMI, age on September 11, 2001, and polymorphonuclear neutrophils. The model had sensitivity of 38% (95% CI, 27-51) and specificity of 88% (95% CI, 80-93). Conclusions: Inflammatory biomarkers can be risk factors for airflow obstruction following dust and smoke exposure. Elevated serum GM-CSF and MDC levels soon after WTC exposure were associated with increased risk of airflow obstruction in subsequent years. Biomarkers of inflammation may help identify pathways producing obstruction after irritant exposure. PMID:21998260

Differential effects of sertraline in a predator exposure animal model of post-traumatic stress disorder.

PubMed

Wilson, C Brad; McLaughlin, Leslie D; Ebenezer, Philip J; Nair, Anand R; Dange, Rahul; Harre, Joseph G; Shaak, Thomas L; Diamond, David M; Francis, Joseph

2014-01-01

Serotonin (5-HT), norepinephrine (NE), and other neurotransmitters are modulated in post-traumatic stress disorder (PTSD). In addition, pro-inflammatory cytokines (PIC) are elevated during the progression of the disorder. Currently, the only approved pharmacologic treatments for PTSD are the selective-serotonin reuptake inhibitors (SSRI) sertraline and paroxetine, but their efficacy in treating PTSD is marginal at best. In combat-related PTSD, SSRIs are of limited effectiveness. Thus, this study sought to analyze the effects of the SSRI sertraline on inflammation and neurotransmitter modulation via a predator exposure/psychosocial stress animal model of PTSD. We hypothesized that sertraline would diminish inflammatory components and increase 5-HT but might also affect levels of other neurotransmitters, particularly NE. PTSD-like effects were induced in male Sprague-Dawley rats (n = 6/group × 4 groups). The rats were secured in Plexiglas cylinders and placed in a cage with a cat for 1 h on days 1 and 11 of a 31-day stress regimen. PTSD rats were also subjected to psychosocial stress via daily cage cohort changes. At the conclusion of the stress regimen, treatment group animals were injected intraperitoneally (i.p.) with sertraline HCl at 10 mg/kg for 7 consecutive days, while controls received i.p. vehicle. The animals were subsequently sacrificed on day 8. Sertraline attenuated inflammatory markers and normalized 5-HT levels in the central nervous system (CNS). In contrast, sertraline produced elevations in NE in the CNS and systemic circulation of SSRI treated PTSD and control groups. This increase in NE suggests SSRIs produce a heightened noradrenergic response, which might elevate anxiety in a clinical setting.

Comparison of ArcGIS and SAS Geostatistical Analyst to Estimate Population-Weighted Monthly Temperature for US Counties

PubMed Central

Xiaopeng, QI; Liang, WEI; BARKER, Laurie; LEKIACHVILI, Akaki; Xingyou, ZHANG

2015-01-01

Temperature changes are known to have significant impacts on human health. Accurate estimates of population-weighted average monthly air temperature for US counties are needed to evaluate temperature’s association with health behaviours and disease, which are sampled or reported at the county level and measured on a monthly—or 30-day—basis. Most reported temperature estimates were calculated using ArcGIS, relatively few used SAS. We compared the performance of geostatistical models to estimate population-weighted average temperature in each month for counties in 48 states using ArcGIS v9.3 and SAS v 9.2 on a CITGO platform. Monthly average temperature for Jan-Dec 2007 and elevation from 5435 weather stations were used to estimate the temperature at county population centroids. County estimates were produced with elevation as a covariate. Performance of models was assessed by comparing adjusted R2, mean squared error, root mean squared error, and processing time. Prediction accuracy for split validation was above 90% for 11 months in ArcGIS and all 12 months in SAS. Cokriging in SAS achieved higher prediction accuracy and lower estimation bias as compared to cokriging in ArcGIS. County-level estimates produced by both packages were positively correlated (adjusted R2 range=0.95 to 0.99); accuracy and precision improved with elevation as a covariate. Both methods from ArcGIS and SAS are reliable for U.S. county-level temperature estimates; However, ArcGIS’s merits in spatial data pre-processing and processing time may be important considerations for software selection, especially for multi-year or multi-state projects. PMID:26167169

System Identification of a Heaving Point Absorber: Design of Experiment and Device Modeling

DOE PAGES

Bacelli, Giorgio; Coe, Ryan; Patterson, David; ...

2017-04-01

Empirically based modeling is an essential aspect of design for a wave energy converter. These models are used in structural, mechanical and control design processes, as well as for performance prediction. The design of experiments and methods used to produce models from collected data have a strong impact on the quality of the model. This study considers the system identification and model validation process based on data collected from a wave tank test of a model-scale wave energy converter. Experimental design and data processing techniques based on general system identification procedures are discussed and compared with the practices often followedmore » for wave tank testing. The general system identification processes are shown to have a number of advantages. The experimental data is then used to produce multiple models for the dynamics of the device. These models are validated and their performance is compared against one and other. Furthermore, while most models of wave energy converters use a formulation with wave elevation as an input, this study shows that a model using a hull pressure sensor to incorporate the wave excitation phenomenon has better accuracy.« less

System Identification of a Heaving Point Absorber: Design of Experiment and Device Modeling

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bacelli, Giorgio; Coe, Ryan; Patterson, David

Empirically based modeling is an essential aspect of design for a wave energy converter. These models are used in structural, mechanical and control design processes, as well as for performance prediction. The design of experiments and methods used to produce models from collected data have a strong impact on the quality of the model. This study considers the system identification and model validation process based on data collected from a wave tank test of a model-scale wave energy converter. Experimental design and data processing techniques based on general system identification procedures are discussed and compared with the practices often followedmore » for wave tank testing. The general system identification processes are shown to have a number of advantages. The experimental data is then used to produce multiple models for the dynamics of the device. These models are validated and their performance is compared against one and other. Furthermore, while most models of wave energy converters use a formulation with wave elevation as an input, this study shows that a model using a hull pressure sensor to incorporate the wave excitation phenomenon has better accuracy.« less

Photoresponsive polymer design for solar concentrator self-steering heliostats

NASA Astrophysics Data System (ADS)

Barker, Jessica; Basnet, Amod; Bhaduri, Moinak; Burch, Caroline; Chow, Amenda; Li, Xue; Oates, William S.; Massad, Jordan E.; Smith, Ralph

2014-03-01

Concentrating solar energy and transforming it into electricity is clean, economical and renewable. One design of solar power plants consists of an array of heliostats which redirects sunlight to a fixed receiver tower and the generated heat is converted into electricity. Currently, the angles of elevation of heliostats are controlled by motors and drives that are costly and require diverting power that can otherwise be used for producing electricity. We consider replacing the motor and drive system of the heliostat with a photosensitive polymer design that can tilt the mirror using the ability of the polymer to deform when subjected to light. The light causes the underlying molecular structure to change and subsequently, the polymer deforms. The deformation of the polymer is quantified in terms of photostrictive constitutive relations. A mathematical model is derived governing the behaviour of the angle of elevation as the photostrain varies. Photostrain depends on the composition of the polymer, intensity and temperature of light and angle of light polarization. Preliminary findings show a photomechanical rod structural design can provide 60° elevation for temperatures of about 40°C. A photomechanical beam structural design can generate more tilt at lower temperatures. The mathematical analysis illustrates that photostrains on the order of 1% to 10% are desired for both rod and beam designs to produce sufficient tilt under most heliostat field conditions.

UAS-SfM for coastal research: Geomorphic feature extraction and land cover classification from high-resolution elevation and optical imagery

USGS Publications Warehouse

Sturdivant, Emily; Lentz, Erika; Thieler, E. Robert; Farris, Amy; Weber, Kathryn; Remsen, David P.; Miner, Simon; Henderson, Rachel

2017-01-01

The vulnerability of coastal systems to hazards such as storms and sea-level rise is typically characterized using a combination of ground and manned airborne systems that have limited spatial or temporal scales. Structure-from-motion (SfM) photogrammetry applied to imagery acquired by unmanned aerial systems (UAS) offers a rapid and inexpensive means to produce high-resolution topographic and visual reflectance datasets that rival existing lidar and imagery standards. Here, we use SfM to produce an elevation point cloud, an orthomosaic, and a digital elevation model (DEM) from data collected by UAS at a beach and wetland site in Massachusetts, USA. We apply existing methods to (a) determine the position of shorelines and foredunes using a feature extraction routine developed for lidar point clouds and (b) map land cover from the rasterized surfaces using a supervised classification routine. In both analyses, we experimentally vary the input datasets to understand the benefits and limitations of UAS-SfM for coastal vulnerability assessment. We find that (a) geomorphic features are extracted from the SfM point cloud with near-continuous coverage and sub-meter precision, better than was possible from a recent lidar dataset covering the same area; and (b) land cover classification is greatly improved by including topographic data with visual reflectance, but changes to resolution (when <50 cm) have little influence on the classification accuracy.

Logistic regression modeling to assess groundwater vulnerability to contamination in Hawaii, USA

NASA Astrophysics Data System (ADS)

Mair, Alan; El-Kadi, Aly I.

2013-10-01

Capture zone analysis combined with a subjective susceptibility index is currently used in Hawaii to assess vulnerability to contamination of drinking water sources derived from groundwater. In this study, we developed an alternative objective approach that combines well capture zones with multiple-variable logistic regression (LR) modeling and applied it to the highly-utilized Pearl Harbor and Honolulu aquifers on the island of Oahu, Hawaii. Input for the LR models utilized explanatory variables based on hydrogeology, land use, and well geometry/location. A suite of 11 target contaminants detected in the region, including elevated nitrate (> 1 mg/L), four chlorinated solvents, four agricultural fumigants, and two pesticides, was used to develop the models. We then tested the ability of the new approach to accurately separate groups of wells with low and high vulnerability, and the suitability of nitrate as an indicator of other types of contamination. Our results produced contaminant-specific LR models that accurately identified groups of wells with the lowest/highest reported detections and the lowest/highest nitrate concentrations. Current and former agricultural land uses were identified as significant explanatory variables for eight of the 11 target contaminants, while elevated nitrate was a significant variable for five contaminants. The utility of the combined approach is contingent on the availability of hydrologic and chemical monitoring data for calibrating groundwater and LR models. Application of the approach using a reference site with sufficient data could help identify key variables in areas with similar hydrogeology and land use but limited data. In addition, elevated nitrate may also be a suitable indicator of groundwater contamination in areas with limited data. The objective LR modeling approach developed in this study is flexible enough to address a wide range of contaminants and represents a suitable addition to the current subjective approach.

Insulin signaling misregulation underlies circadian and cognitive deficits in a Drosophila fragile X model.

PubMed

Monyak, R E; Emerson, D; Schoenfeld, B P; Zheng, X; Chambers, D B; Rosenfelt, C; Langer, S; Hinchey, P; Choi, C H; McDonald, T V; Bolduc, F V; Sehgal, A; McBride, S M J; Jongens, T A

2017-08-01

Fragile X syndrome (FXS) is an undertreated neurodevelopmental disorder characterized by low intelligence quotent and a wide range of other symptoms including disordered sleep and autism. Although FXS is the most prevalent inherited cause of intellectual disability, its mechanistic underpinnings are not well understood. Using Drosophila as a model of FXS, we showed that select expression of dfmr1 in the insulin-producing cells (IPCs) of the brain was sufficient to restore normal circadian behavior and to rescue the memory deficits in the fragile X mutant fly. Examination of the insulin signaling (IS) pathway revealed elevated levels of Drosophila insulin-like peptide 2 (Dilp2) in the IPCs and elevated IS in the dfmr1 mutant brain. Consistent with a causal role for elevated IS in dfmr1 mutant phenotypes, the expression of dfmr1 specifically in the IPCs reduced IS, and genetic reduction of the insulin pathway also led to amelioration of circadian and memory defects. Furthermore, we showed that treatment with the FDA-approved drug metformin also rescued memory. Finally, we showed that reduction of IS is required at different time points to rescue circadian behavior and memory. Our results indicate that insulin misregulation underlies the circadian and cognitive phenotypes displayed by the Drosophila fragile X model, and thus reveal a metabolic pathway that can be targeted by new and already approved drugs to treat fragile X patients.

Modeling regional variation in riverine fish biodiversity in the Arkansas-White-Red River basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schweizer, Peter E; Jager, Yetta

The patterns of biodiversity in freshwater systems are shaped by biogeography, environmental gradients, and human-induced factors. In this study, we developed empirical models to explain fish species richness in subbasins of the Arkansas White Red River basin as a function of discharge, elevation, climate, land cover, water quality, dams, and longitudinal position. We used information-theoretic criteria to compare generalized linear mixed models and identified well-supported models. Subbasin attributes that were retained as predictors included discharge, elevation, number of downstream dams, percent forest, percent shrubland, nitrate, total phosphorus, and sediment. The random component of our models, which assumed a negative binomialmore » distribution, included spatial correlation within larger river basins and overdispersed residual variance. This study differs from previous biodiversity modeling efforts in several ways. First, obtaining likelihoods for negative binomial mixed models, and thereby avoiding reliance on quasi-likelihoods, has only recently become practical. We found the ranking of models based on these likelihood estimates to be more believable than that produced using quasi-likelihoods. Second, because we had access to a regional-scale watershed model for this river basin, we were able to include model-estimated water quality attributes as predictors. Thus, the resulting models have potential value as tools with which to evaluate the benefits of water quality improvements to fish.« less

Proximal metatarsal osteotomies: a comparative geometric analysis conducted on sawbone models.

PubMed

Nyska, Meir; Trnka, Hans-Jörg; Parks, Brent G; Myerson, Mark S

2002-10-01

We evaluated the change in position of the first metatarsal head using a three-dimensional digitizer on sawbone models. Crescentic, closing wedge, oblique shaft (Ludloff 8 degrees and 16 degrees), reverse oblique shaft (Mau 8 degrees and 16 degrees), rotational "Z" (Scarf), and proximal chevron osteotomies were performed and secured using 3-mm screws. The 16 degrees Ludloff provided the most lateral shift (9.5 mm) and angular correction (14.5 degrees) but also produced the most elevation (1.4 mm) and shortening (2.9 mm). The 8 degrees Ludloff provided lateral and angular corrections similar to those of the crescentic and closing wedge osteotomies with less elevation and shortening. Because the displacement osteotomies (Scarf, proximal chevron) provided less angular correction, the same lateral displacement, and less shortening than the basilar angular osteotomies, based upon this model they can be more reliably used for a patient with a mild to moderate deformity, a short first metatarsal, or an intermediate deformity with a large distal metatarsal articular angle. These results can serve as recommendations for selecting the optimal osteotomy with which to correct a deformation.

National Elevation Dataset

USGS Publications Warehouse

,

2002-01-01

The National Elevation Dataset (NED) is a new raster product assembled by the U.S. Geological Survey. NED is designed to provide National elevation data in a seamless form with a consistent datum, elevation unit, and projection. Data corrections were made in the NED assembly process to minimize artifacts, perform edge matching, and fill sliver areas of missing data. NED has a resolution of one arc-second (approximately 30 meters) for the conterminous United States, Hawaii, Puerto Rico and the island territories and a resolution of two arc-seconds for Alaska. NED data sources have a variety of elevation units, horizontal datums, and map projections. In the NED assembly process the elevation values are converted to decimal meters as a consistent unit of measure, NAD83 is consistently used as horizontal datum, and all the data are recast in a geographic projection. Older DEM's produced by methods that are now obsolete have been filtered during the NED assembly process to minimize artifacts that are commonly found in data produced by these methods. Artifact removal greatly improves the quality of the slope, shaded-relief, and synthetic drainage information that can be derived from the elevation data. Figure 2 illustrates the results of this artifact removal filtering. NED processing also includes steps to adjust values where adjacent DEM's do not match well, and to fill sliver areas of missing data between DEM's. These processing steps ensure that NED has no void areas and artificial discontinuities have been minimized. The artifact removal filtering process does not eliminate all of the artifacts. In areas where the only available DEM is produced by older methods, then "striping" may still occur.

Forest canopy height estimation using double-frequency repeat pass interferometry

NASA Astrophysics Data System (ADS)

Karamvasis, Kleanthis; Karathanassi, Vassilia

2015-06-01

In recent years, many efforts have been made in order to assess forest stand parameters from remote sensing data, as a mean to estimate the above-ground carbon stock of forests in the context of the Kyoto protocol. Synthetic aperture radar interferometry (InSAR) techniques have gained traction in last decade as a viable technology for vegetation parameter estimation. Many works have shown that forest canopy height, which is a critical parameter for quantifying the terrestrial carbon cycle, can be estimated with InSAR. However, research is still needed to understand further the interaction of SAR signals with forest canopy and to develop an operational method for forestry applications. This work discusses the use of repeat pass interferometry with ALOS PALSAR (L band) HH polarized and COSMO Skymed (X band) HH polarized acquisitions over the Taxiarchis forest (Chalkidiki, Greece), in order to produce accurate digital elevation models (DEMs) and estimate canopy height with interferometric processing. The effect of wavelength-dependent penetration depth into the canopy is known to be strong, and could potentially lead to forest canopy height mapping using dual-wavelength SAR interferometry at X- and L-band. The method is based on scattering phase center separation at different wavelengths. It involves the generation of a terrain elevation model underneath the forest canopy from repeat-pass L-band InSAR data as well as the generation of a canopy surface elevation model from repeat pass X-band InSAR data. The terrain model is then used to remove the terrain component from the repeat pass interferometric X-band elevation model, so as to enable the forest canopy height estimation. The canopy height results were compared to a field survey with 6.9 m root mean square error (RMSE). The effects of vegetation characteristics, SAR incidence angle and view geometry, and terrain slope on the accuracy of the results have also been studied in this work.

Insights into the subsurface transport of As(V) and Se(VI) in produced water from hydraulic fracturing using soil samples from Qingshankou Formation, Songliao Basin, China.

PubMed

Chen, Season S; Sun, Yuqing; Tsang, Daniel C W; Graham, Nigel J D; Ok, Yong Sik; Feng, Yujie; Li, Xiang-Dong

2017-04-01

Produced water is a type of wastewater generated from hydraulic fracturing, which may pose a risk to the environment and humans due to its high ionic strength and the presence of elevated concentrations of metals/metalloids that exceed maximum contamination levels. The mobilization of As(V) and Se(VI) in produced water and selected soils from Qingshankou Formation in the Songliao Basin in China were investigated using column experiments and synthetic produced water whose quality was representative of waters arising at different times after well creation. Temporal effects of produced water on metal/metalloid transport and sorption/desorption were investigated by using HYDRUS-1D transport modelling. Rapid breakthrough and long tailings of As(V) and Se(VI) transport were observed in Day 1 and Day 14 solutions, but were reduced in Day 90 solution probably due to the elevated ionic strength. The influence of produced water on the hydrogeological conditions (i.e., change between equilibrium and non-equilibrium transport) was evidenced by the change of tracer breakthrough curves before and after the leaching of produced water. This possibly resulted from the sorption of polyacrylamide (PAM (-CH 2 CHCONH 2 -) n ) onto soil surfaces, through its use as a friction reducer in fracturing solutions. The sorption was found to be reversible in this study. Minimal amounts of sorbed As(V) were desorbed whereas the majority of sorbed Se(VI) was readily leached out, to an extent which varied with the composition of the produced water. These results showed that the mobilization of As(V) and Se(VI) in soil largely depended on the solution pH and ionic strength. Understanding the differences in metal/metalloid transport in produced water is important for proper risk management. Copyright © 2017 Elsevier Ltd. All rights reserved.

Debris flow initiation in proglacial gullies on Mount Rainier, Washington

NASA Astrophysics Data System (ADS)

Legg, Nicholas T.; Meigs, Andrew J.; Grant, Gordon E.; Kennard, Paul

2014-12-01

Effects of climate change, retreating glaciers, and changing storm patterns on debris flow hazards concern managers in the Cascade Range (USA) and mountainous areas worldwide. During an intense rainstorm in November 2006, seven debris flows initiated from proglacial gullies of separate basins on the flanks of Mount Rainier. Gully heads at glacier termini and widespread failure of gully walls imply that overland flow was transformed into debris flow along gullies. We characterized gully change and morphology, and assessed spatial distributions of debris flows to infer the processes and conditions for debris flow initiation. Slopes at gully heads were greater than ~ 0.35 m m- 1 (19°) and exhibited a significant negative relationship with drainage area. A break in slope-drainage area trends among debris flow gullies also occurs at ~ 0.35 m m- 1, representing a possible transition to fluvial sediment transport and erosion. An interpreted hybrid model of debris flow initiation involves bed failure near gully heads followed by sediment recruitment from gully walls along gully lengths. Estimates of sediment volume loss from gully walls demonstrate the importance of sediment inputs along gullies for increasing debris flow volumes. Basin comparisons revealed significantly steeper drainage networks and higher elevations in debris flow-producing than non-debris flow-producing proglacial areas. The high slopes and elevations of debris flow-producing proglacial areas reflect positive slope-elevation trends for the Mount Rainier volcano. Glacier extent therefore controls the slope distribution in proglacial areas, and thus potential for debris flow generation. As a result, debris flow activity may increase as glacier termini retreat onto slopes inclined at angles above debris flow initiation thresholds.

Comparison of two vertical condensation obturation techniques: Touch 'n Heat modified and System B.

PubMed

Silver, G K; Love, R M; Purton, D G

1999-08-01

The aims of this study were firstly to compare the area of canal occupied by gutta-percha, sealer or voids using the System B heating device with that obtained by a modified vertical condensation technique using the Touch 'n Heat: and secondly to compare the temperature changes at the root canal wall and external root surface during obturation with the above techniques. Forty-five resin blocks, each with a standardized, simulated, prepared main root canal and five lateral canals, were assigned to three equal experimental groups. The canals were obturated using either the System B technique at two different temperature settings, or vertical condensation with a Touch 'n Heat instrument as the heat source. A heat transfer model was used to simultaneously record internal and external root surface temperature elevations during obturation by the three techniques. Data were analysed using unpaired Student's t-test and Mann-Whitney U-test. Both obturation techniques produced root fillings consisting of over 90% gutta-percha at most levels, although the percentages of sealer and voids 2-3 mm from the working length following System B obturation were higher than those found following modified vertical condensation. Modified vertical condensation resulted in more gutta-percha in lateral canals. Obturation was accomplished more quickly using the System B, and temperature elevations produced during obturation with the System B were significantly less (P < 0.001) than with vertical condensation. An elevation of external root surface temperature by more than 10 degrees C occurred during vertical condensation. The results suggest that the System B may produce an acceptable obturation and that the use of a Touch 'n Heat source during vertical condensation may result in damage to the periodontium.

Heat induced temperature dysregulation and seizures in Dravet Syndrome/GEFS+ Gabrg2+/Q390X mice.

PubMed

Warner, Timothy A; Liu, Zhong; Macdonald, Robert L; Kang, Jing-Qiong

2017-08-01

It has been established that febrile seizures and its extended syndromes like generalized epilepsy with febrile seizures (FS) plus (GEFS+) and Dravet syndrome have been associated with mutations especially in SCN1A and GABRG2 genes. In patients, the onset of FS is likely due to the combined effect of temperature and inflammation in genetically vulnerable individuals because fever is often associated with infection. Much effort has been spent to understand the mechanisms underlying fever induction of seizures. In addition to the role of cytokines in FS, previous studies in Scn1a +/- knockout mice, a model of Dravet syndrome, indicated that temperature elevation alone could result in seizure generation, and the effect of elevated temperature inducing seizures was age-dependent. Here, we report the thermal effect in a different mouse model of Dravet syndrome, the Gabrg2 +/Q390X knockin mouse. We demonstrated age-dependent dysregulated temperature control and that temperature elevation produced myoclonic jerks, generalized tonic clonic seizures (GTCSs) and heightened anxiety-like symptoms in Gabrg2 +/Q390X mice. The study indicated that regardless of other inflammatory factors, brief heat alone increased brain excitability and induced multiple types of seizures in Gabrg2 +/Q390X mice, suggesting that mutations like GABRG2(Q390X) may alter brain thermal regulation and precipitate seizures during temperature elevations. Copyright © 2017 Elsevier B.V. All rights reserved.

Assessment of Reference Height Models on Quality of Tandem-X dem

NASA Astrophysics Data System (ADS)

Mirzaee, S.; Motagh, M.; Arefi, H.

2015-12-01

The aim of this study is to investigate the effect of various Global Digital Elevation Models (GDEMs) in producing high-resolution topography model using TanDEM-X (TDX) Coregistered Single Look Slant Range Complex (CoSSC) images. We selected an image acquired on Jun 12th, 2012 over Doroud region in Lorestan, west of Iran and used 4 external digital elevation models in our processing including DLR/ASI X-SAR DEM (SRTM-X, 30m resolution), ASTER GDEM Version 2 (ASTER-GDEMV2, 30m resolution), NASA SRTM Version 4 (SRTM-V4, 90m resolution), and a local photogrammetry-based DEM prepared by National Cartographic Center (NCC DEM, 10m resolution) of Iran. InSAR procedure for DEM generation was repeated four times with each of the four external height references. The quality of each external DEM was initially assessed using ICESat filtered points. Then, the quality of, each TDX-based DEM was assessed using the more precise external DEM selected in the previous step. Results showed that both local (NCC) DEM and SRTM X-band performed the best (RMSE< 9m) for TDX-DEM generation. In contrast, ASTER GDEM v2 and SRTM C-band v4 showed poorer quality.

NASA's Earth Science Use of Commercially Availiable Remote Sensing Datasets: Cover Image

NASA Technical Reports Server (NTRS)

Underwood, Lauren W.; Goward, Samuel N.; Fearon, Matthew G.; Fletcher, Rose; Garvin, Jim; Hurtt, George

2008-01-01

The cover image incorporates high resolution stereo pairs acquired from the DigitalGlobe(R) QuickBird sensor. It shows a digital elevation model of Meteor Crater, Arizona at approximately 1.3 meter point-spacing. Image analysts used the Leica Photogrammetry Suite to produce the DEM. The outside portion was computed from two QuickBird panchromatic scenes acquired October 2006, while an Optech laser scan dataset was used for the crater s interior elevations. The crater s terrain model and image drape were created in a NASA Constellation Program project focused on simulating lunar surface environments for prototyping and testing lunar surface mission analysis and planning tools. This work exemplifies NASA s Scientific Data Purchase legacy and commercial high resolution imagery applications, as scientists use commercial high resolution data to examine lunar analog Earth landscapes for advanced planning and trade studies for future lunar surface activities. Other applications include landscape dynamics related to volcanism, hydrologic events, climate change, and ice movement.

The Investigation and Semi-Empirical Modeling of Thermoacoustic Phase Relationships in a Lean Premixed Prevapourized Combustor at Elevated Pressure

NASA Astrophysics Data System (ADS)

Cirtwill, Joseph Daniel Maxim

This document presents an investigation of the self-excited coupling mechanisms that occur to produce both low-amplitude intermittent, as well as high-amplitude limit-cycle pressure oscillations in an aeronautical gas turbine combustor. Measurements of a lean premixed prevapourized combustor at elevated pressure were conducted using OH* chemiluminescence, pressure transducers, stereoscopic particle image velocimetry and droplet laser scattering. Analysis of the spectra and phase relationships between the measured variables is performed to determine and describe the coupling mechanisms. A semi-empirical model is presented to explain differences in the limit-cycle pressure amplitudes observed under nominally identical operating conditions. Evidence suggests that an oscillating flux of fuel into the combustor is responsible for both intermittent and limit-cycle oscillations, though different coupling relationships are observed in each case. The final amplitude of limit-cycle oscillations is shown to be correlated with changes in the phase difference between the fuel oscillations and the pressure.

Global detection of large lunar craters based on the CE-1 digital elevation model

NASA Astrophysics Data System (ADS)

Luo, Lei; Mu, Lingli; Wang, Xinyuan; Li, Chao; Ji, Wei; Zhao, Jinjin; Cai, Heng

2013-12-01

Craters, one of the most significant features of the lunar surface, have been widely researched because they offer us the relative age of the surface unit as well as crucial geological information. Research on crater detection algorithms (CDAs) of the Moon and other planetary bodies has concentrated on detecting them from imagery data, but the computational cost of detecting large craters using images makes these CDAs impractical. This paper presents a new approach to crater detection that utilizes a digital elevation model instead of images; this enables fully automatic global detection of large craters. Craters were delineated by terrain attributes, and then thresholding maps of terrain attributes were used to transform topographic data into a binary image, finally craters were detected by using the Hough Transform from the binary image. By using the proposed algorithm, we produced a catalog of all craters ⩾10 km in diameter on the lunar surface and analyzed their distribution and population characteristics.

LiDAR-Derived Flood-Inundation Maps for Real-Time Flood-Mapping Applications, Tar River Basin, North Carolina

USGS Publications Warehouse

Bales, Jerad D.; Wagner, Chad R.; Tighe, Kirsten C.; Terziotti, Silvia

2007-01-01

Flood-inundation maps were created for selected streamgage sites in the North Carolina Tar River basin. Light detection and ranging (LiDAR) data with a vertical accuracy of about 20 centimeters, provided by the Floodplain Mapping Information System of the North Carolina Floodplain Mapping Program, were processed to produce topographic data for the inundation maps. Bare-earth mass point LiDAR data were reprocessed into a digital elevation model with regularly spaced 1.5-meter by 1.5-meter cells. A tool was developed as part of this project to connect flow paths, or streams, that were inappropriately disconnected in the digital elevation model by such features as a bridge or road crossing. The Hydraulic Engineering Center-River Analysis System (HEC-RAS) model, developed by the U.S. Army Corps of Engineers, was used for hydraulic modeling at each of the study sites. Eleven individual hydraulic models were developed for the Tar River basin sites. Seven models were developed for reaches with a single gage, and four models were developed for reaches of the Tar River main stem that receive flow from major gaged tributaries, or reaches in which multiple gages were near one another. Combined, the Tar River hydraulic models included 272 kilometers of streams in the basin, including about 162 kilometers on the Tar River main stem. The hydraulic models were calibrated to the most current stage-discharge relations at 11 long-term streamgages where rating curves were available. Medium- to high-flow discharge measurements were made at some of the sites without rating curves, and high-water marks from Hurricanes Fran and Floyd were available for high-stage calibration. Simulated rating curves matched measured curves over the full range of flows. Differences between measured and simulated water levels for a specified flow were no more than 0.44 meter and typically were less. The calibrated models were used to generate a set of water-surface profiles for each of the 11 modeled reaches at 0.305-meter increments for water levels ranging from bankfull to approximately the highest recorded water level at the downstream-most gage in each modeled reach. Inundated areas were identified by subtracting the water-surface elevation in each 1.5-meter by 1.5-meter grid cell from the land-surface elevation in the cell through an automated routine that was developed to identify all inundated cells hydraulically connected to the cell at the downstream-most gage in the model domain. Inundation maps showing transportation networks and orthoimagery were prepared for display on the Internet. These maps also are linked to the U.S. Geological Survey North Carolina Water Science Center real-time streamflow website. Hence, a user can determine the near real-time stage and water-surface elevation at a U.S. Geological Survey streamgage site in the Tar River basin and link directly to the flood-inundation maps for a depiction of the estimated inundated area at the current water level. Although the flood-inundation maps represent distinct boundaries of inundated areas, some uncertainties are associated with these maps. These are uncertainties in the topographic data for the hydraulic model computational grid and inundation maps, effective friction values (Manning's n), model-validation data, and forecast hydrographs, if used. The Tar River flood-inundation maps were developed by using a steady-flow hydraulic model. This assumption clearly has less of an effect on inundation maps produced for low flows than for high flows when it typically takes more time to inundate areas. A flood in which water levels peak and fall slowly most likely will result in more inundation than a similar flood in which water levels peak and fall quickly. Limitations associated with the steady-flow assumption for hydraulic modeling vary from site to site. The one-dimensional modeling approach used in this study resulted in good agreement between measurements and simulations. T

Extraction of topography from side-looking satellite systems - A case study with SPOT simulation data

NASA Technical Reports Server (NTRS)

Ungar, Stephen G.; Merry, Carolyn J.; Mckim, Harlan L.; Irish, Richard; Miller, Michael S.

1988-01-01

A simulated data set was used to evaluate techniques for extracting topography from side-looking satellite systems for an area of northwest Washington state. A negative transparency orthophotoquad was digitized at a spacing of 85 microns, resulting in an equivalent ground distance of 9.86 m between pixels and a radiometric resolution of 256 levels. A bilinear interpolation was performed on digital elevation model data to generate elevation data at a 9.86-m resolution. The nominal orbital characteristics and geometry of the SPOT satellite were convoluted with the data to produce simulated panchromatic HRV digital stereo imagery for three different orbital paths and techniques for reconstructing topographic data were developed. Analyses with the simulated HRV data and other data sets show that the method is effective.

Network global navigation satellite system survey to harmonize water-surface elevation data for the Rainy River Basin

USGS Publications Warehouse

Ziegeweid, Jeffrey R.; Silliker, R. Jason; Densmore, Brenda K.; Krahulik, Justin

2016-08-15

Continuously recording water-level streamgages in Rainy Lake and Namakan Reservoir are used to regulate water levels according to rule curves established in 2000 by the International Joint Commission; however, water levels at streamgages were referenced to a variety of vertical datums, confounding efforts to model the flow of water through the system, regulate water levels during periods of high inflow, and evaluate the effectiveness of the rule curves. In October 2014, the U.S. Geological Survey, Natural Resources Canada, International Joint Commission, and National Park Service began a joint field study with the goal of obtaining precise elevations referenced to a uniform vertical datum for all reference marks used to set water levels at streamgages throughout Rainy Lake and Namakan Reservoir. This report was prepared by the U.S. Geological Survey in cooperation with Natural Resources Canada, International Joint Commission, and National Park Service.Three field crews deployed Global Navigation Satellite System receivers statically over 16 reference marks colocated with active and discontinued water-level streamgages throughout Rainy River, Rainy Lake, Namakan Reservoir, and select tributaries of Rainy Lake and Namakan Reservoir. A Global Navigation Satellite System receiver also was deployed statically over a National Geodetic Survey cooperative base network control station for use as a quality-control reference mark. Satellite data were collected simultaneously during a 5-day period and processed independently by the U.S. Geological Survey and Natural Resources Canada to obtain accurate positioning and elevations for the 17 surveyed reference marks. Processed satellite data were used to convert published water levels to elevations above sea level referenced to the Canadian Geodetic Vertical Datum of 2013 in order to compare water-surface elevations referenced to a uniform vertical datum throughout the study area. In this report, an “offset” refers to the correction applied to published data from a particular streamgage to produce elevation data referenced to a specified vertical datum.Offsets were applied to water-level data from surveyed streamgages to further evaluate the accuracy and utility of updated reference mark elevations presented in this report. Daily mean water levels from active streamgages surveyed in this study were converted to water-surface elevations referenced to the Canadian Geodetic Vertical Datum of 2013. Graphical comparisons of water-surface elevations for streamgages in Namakan Reservoir, Rainy Lake, and selected rivers are presented (referencing the Canadian Geodetic Vertical Datum of 2013). Offsets presented in this report can be used in the evaluation of rule curves and in flood damage curves that fully assess the benefits of one regulation approach over another. In addition, offsets may be used to calibrate hydraulic models developed for four narrows that connect lakes of Namakan Reservoir, refine digital elevation models, and support modeling studies designed to assess the effects of rule curves on aquatic vegetation, benthic invertebrates, northern pike, and walleye.

A prototype data assimilation framework for generating spatiotemporally continuous SWOT data products

NASA Astrophysics Data System (ADS)

Andreadis, K.; Margulis, S. A.; Li, D.; Lettenmaier, D. P.

2017-12-01

The Surface Water and Ocean Topography (SWOT) satellite will provide critical surface water observations for the hydrologic community. However, production of key SWOT variables, such as river discharge and surface inundation, as well as lake, reservoir, and wetland storage change will be complicated by the discontinuity of the observations in space and time. A methodology that generates products with spatially and temporally continuous fields based on SWOT observables would be highly desirable. Data assimilation provides a mechanism for merging observations from SWOT with model predictions in order to produce estimates of quantities such as river discharge, storage change, and water heights for locations and times when there is no satellite overpass or other constraints (such as layover) render the measurement unusable. We describe here a prototype assimilation system with application to the Upper Mississippi basin, implemented using synthetic SWOT observations. We use a hydrologic model (VIC) coupled with a hydrodynamic model (LISFLOOD-FP) which generates "true" fields of surface water variables. The true fields are then used to generate synthetic SWOT observations using the SWOT Instrument Simulator. We also perform a "first-guess" (or open-loop) simulation with the coupled model using a configuration that contains errors representative of the imperfect knowledge of parameters and input data, including channel topography, bankfull widths and depths, and inflows, to create an ensemble of 20 model trajectories. Subsequently we assimilate the synthetic SWOT observations into the open-loop model results to estimate water surface elevation, discharge, and storage change. Our preliminary results using three data assimilation strategies show that all improve the water surface elevation estimate accuracy by 25% - 35% for a river reach of the upper Mississippi River. Ongoing work is examining whether the improved water surface elevation estimates propagate to improvements in river discharge.

Estimating the Probability of Elevated Nitrate Concentrations in Ground Water in Washington State

USGS Publications Warehouse

Frans, Lonna M.

2008-01-01

Logistic regression was used to relate anthropogenic (manmade) and natural variables to the occurrence of elevated nitrate concentrations in ground water in Washington State. Variables that were analyzed included well depth, ground-water recharge rate, precipitation, population density, fertilizer application amounts, soil characteristics, hydrogeomorphic regions, and land-use types. Two models were developed: one with and one without the hydrogeomorphic regions variable. The variables in both models that best explained the occurrence of elevated nitrate concentrations (defined as concentrations of nitrite plus nitrate as nitrogen greater than 2 milligrams per liter) were the percentage of agricultural land use in a 4-kilometer radius of a well, population density, precipitation, soil drainage class, and well depth. Based on the relations between these variables and measured nitrate concentrations, logistic regression models were developed to estimate the probability of nitrate concentrations in ground water exceeding 2 milligrams per liter. Maps of Washington State were produced that illustrate these estimated probabilities for wells drilled to 145 feet below land surface (median well depth) and the estimated depth to which wells would need to be drilled to have a 90-percent probability of drawing water with a nitrate concentration less than 2 milligrams per liter. Maps showing the estimated probability of elevated nitrate concentrations indicated that the agricultural regions are most at risk followed by urban areas. The estimated depths to which wells would need to be drilled to have a 90-percent probability of obtaining water with nitrate concentrations less than 2 milligrams per liter exceeded 1,000 feet in the agricultural regions; whereas, wells in urban areas generally would need to be drilled to depths in excess of 400 feet.

Increased homocysteine levels impair reference memory and reduce cortical levels of acetylcholine in a mouse model of vascular cognitive impairment.

PubMed

Dam, Kevin; Füchtemeier, Martina; Farr, Tracy D; Boehm-Sturm, Philipp; Foddis, Marco; Dirnagl, Ulrich; Malysheva, Olga; Caudill, Marie A; Jadavji, Nafisa M

2017-03-15

Folates are B-vitamins that are vital for normal brain function. Deficiencies in folates either genetic (methylenetetrahydrofolate reductase, MTHFR) or dietary intake of folic acid result in elevated levels of homocysteine. Clinical studies have shown that elevated levels of homocysteine (Hcy) may be associated with the development of dementia, however this link remains unclear. The purpose of this study was to evaluate the impact of increased Hcy levels on a mouse model of vascular cognitive impairment (VCI) produced by chronic hypoperfusion. Male and female Mthfr +/+ and Mthfr +/- mice were placed on either control (CD) or folic acid deficient (FADD) diets after which all animals underwent microcoil implantation around each common carotid artery or a sham procedure. Post-operatively animals were tested on the Morris water maze (MWM), y-maze, and rotarod. Animals had no motor impairments on the rotarod, y-maze, and could learn the location of the platform on the MWM. However, on day 8 of testing of MWM testing during the probe trial, Mthfr +/- FADD microcoil mice spent significantly less time in the target quadrant when compared to Mthfr +/- CD sham mice, suggesting impaired reference memory. All FADD mice had elevated levels of plasma homocysteine. MRI analysis revealed arterial remodeling was present in Mthfr +/- microcoil mice not Mthfr +/+ mice. Acetylcholine and related metabolites were reduced in cortical tissue because of microcoil implantation and elevated levels of homocysteine. Deficiencies in folate metabolism resulting in increased Hcy levels yield a metabolic profile that increases susceptibility to neurodegeneration in a mouse model of VCI. Copyright © 2017 Elsevier B.V. All rights reserved.

The effects of MDMA pretreatment on the behavioural effects of other drugs of abuse in the rat elevated plus-maze test.

PubMed

Sumnall, H R; O'Shea, E; Marsden, C A; Cole, J C

2004-04-01

Few preclinical studies have found long-term behavioural consequences of the serotonergic neurotoxicity produced by 3,4-methylenedioxymethamphetamine (MDMA). This study investigated whether pretreatment with MDMA altered the behavioural effects of other drugs of abuse. Adult male Lister hooded rats (n=10/group) were pretreated with 10 mg/kg MDMA or 1 ml/kg saline vehicle intraperitoneally every 2 h for 6 h. Fourteen days later, the behavioural effects of d-amphetamine (2 mg/kg), cocaine (10 mg/kg), ethanol (2.0 g/kg), heroin (0.5 mg/kg), or MDMA (10 mg/kg) were assessed in the elevated plus-maze test. MDMA pretreatment produced approximately 20-25% decrease in hippocampal 5-HT and 5-HIAA concentrations, and [(3)H]paroxetine binding when analysed 2 weeks later. Despite inducing neurotoxicity, this regimen had no effect upon the plus-maze behaviour induced by ethanol, heroin, and MDMA. Acutely, and independent of neurotoxic pretreatment, MDMA produced a clear anxiogenic-like behavioural profile with a reduction of open arm entries and suppression of explorative behaviours. Despite being acutely anxiogenic, pretreatment with a neurotoxic regimen of MDMA has little effect on the anxiety-related effects of other drugs of abuse. It is possible that extended time points would produce significant changes, although the available evidence suggests that the plus-maze may not be a suitable model for detection of behavioural dysfunction after neurotoxic MDMA.

Acute high dose of chlorpyrifos alters performance of rats in the elevated plus-maze and the elevated T-maze.

PubMed

López-Crespo, G A; Flores, P; Sánchez-Santed, F; Sánchez-Amate, M C

2009-11-01

Chlorpyrifos (CPF) is a broad spectrum organophosphate (OP) pesticide widely used in agriculture, industry and household. Several animal studies indicate emotional disturbances after CPF exposure, although the results are sometimes puzzling. Thus, both anxiolytic and anxiogenic effects of CPF have been reported in different animal models of anxiety [Sánchez-Amate MC, Flores P, Sánchez-Santed F. Effects of chlorpyrifos in the plus-maze model of anxiety. Behav Pharmacol 2001;12:285-92; Sánchez-Amate MC, Dávila E, Cañadas F, Flores P, Sánchez-Santed F. Chlorpyrifos shares stimulus properties with pentilenetetrazol as evaluated by and operant drug discrimination task. Neurotoxicology 2002;23:795-803; López-Crespo G, Carvajal F, Flores P, Sánchez-Santed F, Sánchez-Amate MC. Time-course of biochemical and behavioural effects of a single high dose of chlorpyrifos. Neurotoxicology 2007;28:541-7]. On the other hand, other behavioural effects of CPF are time-dependent [López-Crespo G, Carvajal F, Flores P, Sánchez-Santed F, Sánchez-Amate MC. Time-course of biochemical and behavioural effects of a single high dose of chlorpyrifos. Neurotoxicology 2007;28:541-7], raising the question that the effects of CPF could be task and post-administration time dependent. To test this hypothesis, three groups of rats were treated with a single high dose of CPF (250 mg/kg); one of the groups was tested on day 5 on the elevated plus-maze, to complete our previous study on day 2 [Sánchez-Amate MC, Flores P, Sánchez-Santed F. Effects of chlorpyrifos in the plus-maze model of anxiety. Behav Pharmacol 2001;12:285-92]. The remaining groups were tested on the elevated T-maze on days 2 and 5. CPF produced an increased open arm activity on the elevated plus-maze on day 5, an increased escape latency on the elevated T-maze on day 2 and an impaired inhibitory avoidance on day 5. Data are discussed taking together all studies carried out in our laboratory, confirming that CPF effects on emotional behaviour are dependent on both task contingencies and post-administration time.

Snow cover distribution over elevation zones in a mountainous catchment

NASA Astrophysics Data System (ADS)

Panagoulia, D.; Panagopoulos, Y.

2009-04-01

A good understanding of the elevetional distribution of snow cover is necessary to predict the timing and volume of runoff. In a complex mountainous terrain the snow cover distribution within a watershed is highly variable in time and space and is dependent on elevation, slope, aspect, vegetation type, surface roughness, radiation load, and energy exchange at the snow-air interface. Decreases in snowpack due to climate change could disrupt the downstream urban and agricultural water supplies, while increases could lead to seasonal flooding. Solar and longwave radiation are dominant energy inputs driving the ablation process. Turbulent energy exchange at the snow cover surface is important during the snow season. The evaporation of blowing and drifting snow is strongly dependent upon wind speed. Much of the spatial heterogeneity of snow cover is the result of snow redistribution by wind. Elevation is important in determining temperature and precipitation gradients along hillslopes, while the temperature gradients determine where precipitation falls as rain and snow and contribute to variable melt rates within the hillslope. Under these premises, the snow accumulation and ablation (SAA) model of the US National Weather Service (US NWS) was applied to implement the snow cover extent over elevation zones of a mountainous catchment (the Mesochora catchment in Western-Central Greece), taking also into account the indirectly included processes of sublimation, interception, and snow redistribution. The catchment hydrology is controlled by snowfall and snowmelt and the simulated discharge was computed from the soil moisture accounting (SMA) model of the US NWS and compared to the measured discharge. The elevationally distributed snow cover extent presented different patterns with different time of maximization, extinction and return during the year, producing different timing of discharge that is a crucial factor for the control and management of water resources systems.

Comparing and evaluating model estimates of background ozone in surface air over North America

NASA Astrophysics Data System (ADS)

Oberman, J.; Fiore, A. M.; Lin, M.; Zhang, L.; Jacob, D. J.; Naik, V.; Horowitz, L. W.

2011-12-01

Tropospheric ozone adversely affects human health and vegetation, and is thus a criteria pollutant regulated by the U.S. Environmental Protection Agency (EPA) under the National Ambient Air Quality Standard (NAAQS). Ozone is produced in the atmosphere via photo-oxidation of volatile organic compounds (VOCs) and carbon monoxide (CO) in the presence of nitrogen oxides (NOx). The present EPA approach considers health risks associated with exposure to ozone enhancement above the policy-relevant background (PRB), which is currently defined as the surface concentration of ozone that would exist without North American anthropogenic emissions. PRB thus includes production by natural precursors, production by precursors emitted on foreign continents, and transport of stratospheric ozone into surface air. As PRB is not an observable quantity, it must be estimated using numerical models. We compare PRB estimates for the year 2006 from the GFDL Atmospheric Model 3 (AM3) chemistry-climate model (CCM) and the GEOS-Chem (GC) chemical transport model (CTM). We evaluate the skill of the models in reproducing total surface ozone observed at the U.S. Clean Air Status and Trends Network (CASTNet), dividing the stations into low-elevation (< 1.5 km in altitude, primarily eastern) and high-elevation (> 1.5 km in altitude, all western) subgroups. At the low-elevation sites AM3 estimates of PRB (38±9 ppbv in spring, 27±9 ppbv in summer) are higher than GC (27±7 ppbv in spring, 21±8 ppbv in summer) in both seasons. Analysis at these sites is complicated by a positive bias in AM3 total ozone with respect to the observed total ozone, the source of which is yet unclear. At high-elevation sites, AM3 PRB is higher in the spring (47±8 ppbv) than in the summer (33±8 ppbv). In contrast, GC simulates little seasonal variation at high elevation sites (39±5 ppbv in spring vs. 38±7 ppbv in summer). Seasonal average total ozone at these sites was within 4 ppbv of the observations for both spring and summer in both models. The high elevation springtime maximum in PRB predicted by AM3 likely reflects stronger exchange between the surface and the free troposphere relative to GC, including a larger influence of stratospheric ozone. Higher summertime PRB in GC may be associated with differences in how the models treat the lightning NOx source (~10 times higher in GC over the Southwest U.S.). Biomass burning emissions (treated differently in the two models) contribute to episodic PRB enhancements in AM3 over the Midwest and East Coast. We conclude that further multi-model studies, including additional models, could provide the EPA with a more robust estimate of PRB, particularly if designed to isolate the relative roles of emissions, chemistry and transport, and evaluated with observation-based constraints wherever possible.

BOREAS Regional DEM in Raster Format and AEAC Projection

NASA Technical Reports Server (NTRS)

Knapp, David; Verdin, Kristine; Hall, Forrest G. (Editor)

2000-01-01

This data set is based on the GTOPO30 Digital Elevation Model (DEM) produced by the United States Geological Survey EROS Data Center (USGS EDC). The BOReal Ecosystem-Atmosphere Study (BOREAS) region (1,000 km x 1000 km) was extracted from the GTOPO30 data and reprojected by BOREAS staff into the Albers Equal-Area Conic (AEAC) projection. The pixel size of these data is 1 km. The data are stored in binary, image format files.

Cumulative mtDNA damage and mutations contribute to the progressive loss of RGCs in a rat model of glaucoma

PubMed Central

Nickerson, John M.; Gao, Feng-juan; Sun, Zhongmou; Chen, Xin-ya; Zhang, Shu-jie; Gao, Feng; Chen, Jun-yi; Luo, Yi; Wang, Yan; Sun, Xing-huai

2015-01-01

Glaucoma is a chronic neurodegenerative disease characterized by the progressive loss of retinal ganglion cells (RGCs). Mitochondrial DNA (mtDNA) alterations have been documented as a key component of many neurodegenerative disorders. However, whether mtDNA alterations contribute to the progressive loss of RGCs and the mechanism whereby this phenomenon could occur are poorly understood. We investigated mtDNA alterations in RGCs using a rat model of chronic intraocular hypertension and explored the mechanisms underlying progressive RGC loss. We demonstrate that the mtDNA damage and mutations triggered by intraocular pressure (IOP) elevation are initiating, crucial events in a cascade leading to progressive RGC loss. Damage to and mutation of mtDNA, mitochondrial dysfunction, reduced levels of mtDNA repair/replication enzymes, and elevated reactive oxygen species form a positive feedback loop that produces irreversible mtDNA damage and mutation and contributes to progressive RGC loss, which occurs even after a return to normal IOP. Furthermore, we demonstrate that mtDNA damage and mutations increase the vulnerability of RGCs to elevated IOP and glutamate levels, which are among the most common glaucoma insults. This study suggests that therapeutic approaches that target mtDNA maintenance and repair and that promote energy production may prevent the progressive death of RGCs. PMID:25478814

A continuous scale-space method for the automated placement of spot heights on maps

NASA Astrophysics Data System (ADS)

Rocca, Luigi; Jenny, Bernhard; Puppo, Enrico

2017-12-01

Spot heights and soundings explicitly indicate terrain elevation on cartographic maps. Cartographers have developed design principles for the manual selection, placement, labeling, and generalization of spot height locations, but these processes are work-intensive and expensive. Finding an algorithmic criterion that matches the cartographers' judgment in ranking the significance of features on a terrain is a difficult endeavor. This article proposes a method for the automated selection of spot heights locations representing natural features such as peaks, saddles and depressions. A lifespan of critical points in a continuous scale-space model is employed as the main measure of the importance of features, and an algorithm and a data structure for its computation are described. We also introduce a method for the comparison of algorithmically computed spot height locations with manually produced reference compilations. The new method is compared with two known techniques from the literature. Results show spot height locations that are closer to reference spot heights produced manually by swisstopo cartographers, compared to previous techniques. The introduced method can be applied to elevation models for the creation of topographic and bathymetric maps. It also ranks the importance of extracted spot height locations, which allows for a variation in the size of symbols and labels according to the significance of represented features. The importance ranking could also be useful for adjusting spot height density of zoomable maps in real time.

A laboratory study of the electromagnetic bias of rough surface scattering by water waves

NASA Technical Reports Server (NTRS)

Parsons, Chester L.; Miller, Lee S.

1990-01-01

The design, development, and use of a focused-beam radar to measure the electromagnetic bias introduced by the scattering of radar waves by a roughened water surface are discussed. The bias measurements were made over wide ranges of environmental conditions in a wavetank laboratory. Wave-elevation data were provided by standard laboratory capacitance probes. Backscattered radar power measurements coincident in time and space with the elevation data were produced by the radar. The two data sets are histogrammed to produce probability density functions for elevation and radar reflectivity, from which the electromagnetic bias is computed. The experimental results demonstrate that the electromagnetic bias is quite variable over the wide range of environmental conditions that can be produced in the laboratory. The data suggest that the bias is dependent upon the local wind field and on the amplitude and frequency of any background wave field that is present.

Comparison of Probabilistic Coastal Inundation Maps Based on Historical Storms and Statistically Modeled Storm Ensemble

NASA Astrophysics Data System (ADS)

Feng, X.; Sheng, Y.; Condon, A. J.; Paramygin, V. A.; Hall, T.

2012-12-01

A cost effective method, JPM-OS (Joint Probability Method with Optimal Sampling), for determining storm response and inundation return frequencies was developed and applied to quantify the hazard of hurricane storm surges and inundation along the Southwest FL,US coast (Condon and Sheng 2012). The JPM-OS uses piecewise multivariate regression splines coupled with dimension adaptive sparse grids to enable the generation of a base flood elevation (BFE) map. Storms are characterized by their landfall characteristics (pressure deficit, radius to maximum winds, forward speed, heading, and landfall location) and a sparse grid algorithm determines the optimal set of storm parameter combinations so that the inundation from any other storm parameter combination can be determined. The end result is a sample of a few hundred (197 for SW FL) optimal storms which are simulated using a dynamically coupled storm surge / wave modeling system CH3D-SSMS (Sheng et al. 2010). The limited historical climatology (1940 - 2009) is explored to develop probabilistic characterizations of the five storm parameters. The probability distributions are discretized and the inundation response of all parameter combinations is determined by the interpolation in five-dimensional space of the optimal storms. The surge response and the associated joint probability of the parameter combination is used to determine the flood elevation with a 1% annual probability of occurrence. The limited historical data constrains the accuracy of the PDFs of the hurricane characteristics, which in turn affect the accuracy of the BFE maps calculated. To offset the deficiency of limited historical dataset, this study presents a different method for producing coastal inundation maps. Instead of using the historical storm data, here we adopt 33,731 tracks that can represent the storm climatology in North Atlantic basin and SW Florida coasts. This large quantity of hurricane tracks is generated from a new statistical model which had been used for Western North Pacific (WNP) tropical cyclone (TC) genesis (Hall 2011) as well as North Atlantic tropical cyclone genesis (Hall and Jewson 2007). The introduction of these tracks complements the shortage of the historical samples and allows for more reliable PDFs required for implementation of JPM-OS. Using the 33,731 tracks and JPM-OS, an optimal storm ensemble is determined. This approach results in different storms/winds for storm surge and inundation modeling, and produces different Base Flood Elevation maps for coastal regions. Coastal inundation maps produced by the two different methods will be discussed in detail in the poster paper.

A dynamic model of the marriage market-Part 2: simulation of marital states and application to empirical data.

PubMed

Matthews, A P; Garenne, M L

2013-09-01

A dynamic, two-sex, age-structured marriage model is presented. Part 1 focused on first marriage only and described a marriage market matching algorithm. In Part 2 the model is extended to include divorce, widowing, and remarriage. The model produces a self-consistent set of marital states distributed by age and sex in a stable population by means of a gender-symmetric numerical method. The model is compared with empirical data for the case of Zambia. Furthermore, a dynamic marriage function for a changing population is demonstrated in simulations of three hypothetical scenarios of elevated mortality in young to middle adulthood. The marriage model has its primary application to simulation of HIV-AIDS epidemics in African countries. Copyright © 2013 Elsevier Inc. All rights reserved.

Influence of Elevation Data Source on 2D Hydraulic Modelling

NASA Astrophysics Data System (ADS)

Bakuła, Krzysztof; StĘpnik, Mateusz; Kurczyński, Zdzisław

2016-08-01

The aim of this paper is to analyse the influence of the source of various elevation data on hydraulic modelling in open channels. In the research, digital terrain models from different datasets were evaluated and used in two-dimensional hydraulic models. The following aerial and satellite elevation data were used to create the representation of terrain-digital terrain model: airborne laser scanning, image matching, elevation data collected in the LPIS, EuroDEM, and ASTER GDEM. From the results of five 2D hydrodynamic models with different input elevation data, the maximum depth and flow velocity of water were derived and compared with the results of the most accurate ALS data. For such an analysis a statistical evaluation and differences between hydraulic modelling results were prepared. The presented research proved the importance of the quality of elevation data in hydraulic modelling and showed that only ALS and photogrammetric data can be the most reliable elevation data source in accurate 2D hydraulic modelling.

Two Preliminary SRTM DEMs Within the Amazon Basin

NASA Astrophysics Data System (ADS)

Alsdorf, D.; Hess, L.; Melack, J.; Dunne, T.; Mertes, L.; Ballantine, A.; Biggs, T.; Holmes, K.; Sheng, Y.; Hendricks, G.

2002-12-01

Digital topography provides important measures, such as hillslope lengths and flow path networks, for understanding hydrologic and geomorphic processes (e.g., runoff response to land use change and floodplain inundation volume). Two preliminary Shuttle Radar Topography Mission digital elevation models of Manaus (1S to 5S and 59W to 63W) and Rondonia (9S to 12S and 61W to 64W) were received from NASA JPL in August 2002. The "PI Processor" produced these initial DEM segments and we are using them to assess the initial accuracy of the interferometrically derived heights and for hydrologic research. The preliminary SRTM derived absolute elevations across the Amazon floodplain in the Cabaliana region generally range from 5 to 15 m with reported errors of 1 to 3 m. This region also includes some preliminary elevations that are erroneously negative. However, topographic contours on 1:100,000 scale quadrangles of 1978 to 1980 vintage indicate elevations of 20 to 30 m. Because double-bounce travel paths are possible over the sparsely vegetated and very-flat 2400 sq-km water surface of the Balbina reservoir near Manaus, it serves to identify the relative accuracy of the SRTM heights. Here, cell-to-cell height changes are generally 0 to 1 m and changes across a ~100 km transect rarely exceed 3 m. Reported errors throughout the transect range from 1 to 2 m with some errors up to 5 m. Deforestation in Rondonia is remarkably clear in the C-band DEM where elevations are recorded from the canopy rather than bare earth. Here, elevation changes are ~30 m (with reported 1 to 2 m errors) across clear-cut areas. Field derived canopy heights are in agreement with this change. Presently, we are deriving stream networks in the Amazon floodplain for comparison with our previous network extraction from JERS-1 SAR mosaics and for hydrologic modeling.

Forecasted Flood Depth Grids Providing Early Situational Awareness to FEMA during the 2017 Atlantic Hurricane Season

NASA Astrophysics Data System (ADS)

Jones, M.; Longenecker, H. E., III

2017-12-01

The 2017 hurricane season brought the unprecedented landfall of three Category 4 hurricanes (Harvey, Irma and Maria). FEMA is responsible for coordinating the federal response and recovery efforts for large disasters such as these. FEMA depends on timely and accurate depth grids to estimate hazard exposure, model damage assessments, plan flight paths for imagery acquisition, and prioritize response efforts. In order to produce riverine or coastal depth grids based on observed flooding, the methodology requires peak crest water levels at stream gauges, tide gauges, high water marks, and best-available elevation data. Because peak crest data isn't available until the apex of a flooding event and high water marks may take up to several weeks for field teams to collect for a large-scale flooding event, final observed depth grids are not available to FEMA until several days after a flood has begun to subside. Within the last decade NOAA's National Weather Service (NWS) has implemented the Advanced Hydrologic Prediction Service (AHPS), a web-based suite of accurate forecast products that provide hydrograph forecasts at over 3,500 stream gauge locations across the United States. These forecasts have been newly implemented into an automated depth grid script tool, using predicted instead of observed water levels, allowing FEMA access to flood hazard information up to 3 days prior to a flooding event. Water depths are calculated from the AHPS predicted flood stages and are interpolated at 100m spacing along NHD hydrolines within the basin of interest. A water surface elevation raster is generated from these water depths using an Inverse Distance Weighted interpolation. Then, elevation (USGS NED 30m) is subtracted from the water surface elevation raster so that the remaining values represent the depth of predicted flooding above the ground surface. This automated process requires minimal user input and produced forecasted depth grids that were comparable to post-event observed depth grids and remote sensing-derived flood extents for the 2017 hurricane season. These newly available forecasted models were used for pre-event response planning and early estimated hazard exposure counts, allowing FEMA to plan for and stand up operations several days sooner than previously possible.

Sediment transport dynamics linked to morphological evolution of the Selenga River delta, Lake Baikal, Russia

NASA Astrophysics Data System (ADS)

Dong, T. Y.; Nittrouer, J.; McElroy, B. J.; Czapiga, M. J.; Il'icheva, E.; Pavolv, M.; Parker, G.

2014-12-01

The Selenga River delta, Lake Baikal, Russia, is approximately 700 km2 in size and contains three active lobes that receive varying amounts of water and sediment discharge. This delta represents a unique end-member in so far that the system is positioned along the deep-water (~1500 m) margin of Lake Baikal and therefore exists as a shelf-edge delta. In order to evaluate the morphological dynamics of the Selenga delta, field expeditions were undertaken during July 2013 and 2014, to investigate the morphologic, sedimentologic, and hydraulic nature of this delta system. Single-beam bathymetry data, sidescan sonar data, sediment samples, and aerial survey data were collected and analyzed to constrain: 1) channel geometries within the delta, 2) bedform sizes and spatial distributions, 3) grain size composition of channel bed sediment as well as bank sediment, collected from both major and minor distributary channels, and 4) elevation range of the subaerial portion of the delta. Our data indicate that the delta possesses downstream sediment fining, ranging from predominantly gravel and sand near the delta apex to silt and sand at the delta-lake interface. Field surveys also indicate that the Selenga delta has both eroding and aggrading banks, and that the delta is actively incising into some banks that consist of terraces, which are defined as regions that are not inundated by typical 2- to 4-year flood discharge events. Therefore the terraces are distinct from the actively accreting regions of the delta that receive sedimentation via water inundation during regular river floods. We spatially constrain the regions of the Selenga delta that are inundated during floods versus terraced using a 1-D water-surface hydrodynamic model that produces estimates of stage for flood water discharges, whereby local water surface elevations produced with the model are compared to the measured terrestrial elevations. Our analyses show that terrace elevations steadily decrease downstream for all lobes, and that the delta is undergoing an active phase of erosion, characterized by channel incision and extensive lateral erosion of terraces; this process of delta 'self-cannibalization' contributes to the downstream sediment flux and morphological evolution of the delta.

Genetic evidence in the mouse solidifies the calcium hypothesis of myofiber death in muscular dystrophy

PubMed Central

Burr, A R; Molkentin, J D

2015-01-01

Muscular dystrophy (MD) refers to a clinically and genetically heterogeneous group of degenerative muscle disorders characterized by progressive muscle wasting and often premature death. Although the primary defect underlying most forms of MD typically results from a loss of sarcolemmal integrity, the secondary molecular mechanisms leading to muscle degeneration and myofiber necrosis is debated. One hypothesis suggests that elevated or dysregulated cytosolic calcium is the common transducing event, resulting in myofiber necrosis in MD. Previous measurements of resting calcium levels in myofibers from dystrophic animal models or humans produced equivocal results. However, recent studies in genetically altered mouse models have largely solidified the calcium hypothesis of MD, such that models with artificially elevated calcium in skeletal muscle manifest fulminant dystrophic-like disease, whereas models with enhanced calcium clearance or inhibited calcium influx are resistant to myofiber death and MD. Here, we will review the field and the recent cadre of data from genetically altered mouse models, which we propose have collectively mostly proven the hypothesis that calcium is the primary effector of myofiber necrosis in MD. This new consensus on calcium should guide future selection of drugs to be evaluated in clinical trials as well as gene therapy-based approaches. PMID:26088163

Susceptibility assessment of earthquake-triggered landslides in El Salvador using logistic regression

NASA Astrophysics Data System (ADS)

García-Rodríguez, M. J.; Malpica, J. A.; Benito, B.; Díaz, M.

2008-03-01

This work has evaluated the probability of earthquake-triggered landslide occurrence in the whole of El Salvador, with a Geographic Information System (GIS) and a logistic regression model. Slope gradient, elevation, aspect, mean annual precipitation, lithology, land use, and terrain roughness are the predictor variables used to determine the dependent variable of occurrence or non-occurrence of landslides within an individual grid cell. The results illustrate the importance of terrain roughness and soil type as key factors within the model — using only these two variables the analysis returned a significance level of 89.4%. The results obtained from the model within the GIS were then used to produce a map of relative landslide susceptibility.

Modelling and restoration of ultrasonic phased-array B-scan images.

PubMed

Ardouin, J P; Venetsanopoulos, A N

1985-10-01

A model is presented for the radio-frequency image produced by a B-scan (pulse-echo) ultrasound imaging system using a phased-array transducer. This type of scanner is widely used for real-time heart imaging. The model allows for dynamic focusing as well as an acoustic lens focusing the beam in the elevation plane. A result of the model is an expression to compute the space-variant point spread function (PSF) of the system. This is made possible by the use of a combination of Fresnel and Fraunhoffer approximations which are valid in the range of interest for practical applications. The PSF is used to design restoration filters in order to improve image resolution. The filters are then applied to experimental images of wires.

Molecular Characterization of Growth Hormone-producing Tumors in the GC Rat Model of Acromegaly.

PubMed

Martín-Rodríguez, Juan F; Muñoz-Bravo, Jose L; Ibañez-Costa, Alejandro; Fernandez-Maza, Laura; Balcerzyk, Marcin; Leal-Campanario, Rocío; Luque, Raúl M; Castaño, Justo P; Venegas-Moreno, Eva; Soto-Moreno, Alfonso; Leal-Cerro, Alfonso; Cano, David A

2015-11-09

Acromegaly is a disorder resulting from excessive production of growth hormone (GH) and consequent increase of insulin-like growth factor 1 (IGF-I), most frequently caused by pituitary adenomas. Elevated GH and IGF-I levels results in wide range of somatic, cardiovascular, endocrine, metabolic, and gastrointestinal morbidities. Subcutaneous implantation of the GH-secreting GC cell line in rats leads to the formation of tumors. GC tumor-bearing rats develop characteristics that resemble human acromegaly including gigantism and visceromegaly. However, GC tumors remain poorly characterized at a molecular level. In the present work, we report a detailed histological and molecular characterization of GC tumors using immunohistochemistry, molecular biology and imaging techniques. GC tumors display histopathological and molecular features of human GH-producing tumors, including hormone production, cell architecture, senescence activation and alterations in cell cycle gene expression. Furthermore, GC tumors cells displayed sensitivity to somatostatin analogues, drugs that are currently used in the treatment of human GH-producing adenomas, thus supporting the GC tumor model as a translational tool to evaluate therapeutic agents. The information obtained would help to maximize the usefulness of the GC rat model for research and preclinical studies in GH-secreting tumors.

Molecular Characterization of Growth Hormone-producing Tumors in the GC Rat Model of Acromegaly

PubMed Central

Martín-Rodríguez, Juan F.; Muñoz-Bravo, Jose L.; Ibañez-Costa, Alejandro; Fernandez-Maza, Laura; Balcerzyk, Marcin; Leal-Campanario, Rocío; Luque, Raúl M.; Castaño, Justo P.; Venegas-Moreno, Eva; Soto-Moreno, Alfonso; Leal-Cerro, Alfonso; Cano, David A.

2015-01-01

Acromegaly is a disorder resulting from excessive production of growth hormone (GH) and consequent increase of insulin-like growth factor 1 (IGF-I), most frequently caused by pituitary adenomas. Elevated GH and IGF-I levels results in wide range of somatic, cardiovascular, endocrine, metabolic, and gastrointestinal morbidities. Subcutaneous implantation of the GH-secreting GC cell line in rats leads to the formation of tumors. GC tumor-bearing rats develop characteristics that resemble human acromegaly including gigantism and visceromegaly. However, GC tumors remain poorly characterized at a molecular level. In the present work, we report a detailed histological and molecular characterization of GC tumors using immunohistochemistry, molecular biology and imaging techniques. GC tumors display histopathological and molecular features of human GH-producing tumors, including hormone production, cell architecture, senescence activation and alterations in cell cycle gene expression. Furthermore, GC tumors cells displayed sensitivity to somatostatin analogues, drugs that are currently used in the treatment of human GH-producing adenomas, thus supporting the GC tumor model as a translational tool to evaluate therapeutic agents. The information obtained would help to maximize the usefulness of the GC rat model for research and preclinical studies in GH-secreting tumors. PMID:26549306

Linking occupancy surveys with habitat characteristics to estimate abundance and distribution in an endangered cryptic bird

USGS Publications Warehouse

Crampton, Lisa H.; Brinck, Kevin W.; Pias, Kyle E.; Heindl, Barbara A. P.; Savre, Thomas; Diegmann, Julia S.; Paxton, Eben H.

2017-01-01

Accurate estimates of the distribution and abundance of endangered species are crucial to determine their status and plan recovery options, but such estimates are often difficult to obtain for species with low detection probabilities or that occur in inaccessible habitats. The Puaiohi (Myadestes palmeri) is a cryptic species endemic to Kauaʻi, Hawai‘i, and restricted to high elevation ravines that are largely inaccessible. To improve current population estimates, we developed an approach to model distribution and abundance of Puaiohi across their range by linking occupancy surveys to habitat characteristics, territory density, and landscape attributes. Occupancy per station ranged from 0.17 to 0.82, and was best predicted by the number and vertical extent of cliffs, cliff slope, stream width, and elevation. To link occupancy estimates with abundance, we used territory mapping data to estimate the average number of territories per survey station (0.44 and 0.66 territories per station in low and high occupancy streams, respectively), and the average number of individuals per territory (1.9). We then modeled Puaiohi occupancy as a function of two remote-sensed measures of habitat (stream sinuosity and elevation) to predict occupancy across its entire range. We combined predicted occupancy with estimates of birds per station to produce a global population estimate of 494 (95% CI 414–580) individuals. Our approach is a model for using multiple independent sources of information to accurately track population trends, and we discuss future directions for modeling abundance of this, and other, rare species.

Predicting the Geothermal Heat Flux in Greenland: A Machine Learning Approach

NASA Astrophysics Data System (ADS)

Rezvanbehbahani, Soroush; Stearns, Leigh A.; Kadivar, Amir; Walker, J. Doug; van der Veen, C. J.

2017-12-01

Geothermal heat flux (GHF) is a crucial boundary condition for making accurate predictions of ice sheet mass loss, yet it is poorly known in Greenland due to inaccessibility of the bedrock. Here we use a machine learning algorithm on a large collection of relevant geologic features and global GHF measurements and produce a GHF map of Greenland that we argue is within ˜15% accuracy. The main features of our predicted GHF map include a large region with high GHF in central-north Greenland surrounding the NorthGRIP ice core site, and hot spots in the Jakobshavn Isbræ catchment, upstream of Petermann Gletscher, and near the terminus of Nioghalvfjerdsfjorden glacier. Our model also captures the trajectory of Greenland movement over the Icelandic plume by predicting a stripe of elevated GHF in central-east Greenland. Finally, we show that our model can produce substantially more accurate predictions if additional measurements of GHF in Greenland are provided.

Evaluating the perennial stream using logistic regression in central Taiwan

NASA Astrophysics Data System (ADS)

Ruljigaljig, T.; Cheng, Y. S.; Lin, H. I.; Lee, C. H.; Yu, T. T.

2014-12-01

This study produces a perennial stream head potential map, based on a logistic regression method with a Geographic Information System (GIS). Perennial stream initiation locations, indicates the location of the groundwater and surface contact, were identified in the study area from field survey. The perennial stream potential map in central Taiwan was constructed using the relationship between perennial stream and their causative factors, such as Catchment area, slope gradient, aspect, elevation, groundwater recharge and precipitation. Here, the field surveys of 272 streams were determined in the study area. The areas under the curve for logistic regression methods were calculated as 0.87. The results illustrate the importance of catchment area and groundwater recharge as key factors within the model. The results obtained from the model within the GIS were then used to produce a map of perennial stream and estimate the location of perennial stream head.

Anti-anxiety activity of Coriandrum sativum assessed using different experimental anxiety models

PubMed Central

Mahendra, Poonam; Bisht, Shradha

2011-01-01

Interest in alternative medicine and plant-derived medications that affect the “mind” is growing. The aim of present study was to explore the anti-anxiety activity of hydroalcoholic extract of Coriandrum sativum (Linn.) using different animal models (elevated plus maze, open field test, light and dark test and social interaction test) of anxiety in mice. Diazepam (0.5 mg/kg) was used as the standard and dose of hydroalcoholic extract of C. sativum fruit (50, 100 and 200 mg/kg) was selected as per OECD guidelines. Results suggested that extract of C. sativum at 100 and 200 mg/kg dose produced anti-anxiety effects almost similar to diazepam, and at 50 mg/kg dose did not produce anti-anxiety activity on any of the paradigm used. Further studies are needed to identify the anxiolytic mechanism(s) and the phytoconstituents responsible for the observed central effects of the hydroalcoholic extract of C. sativum. PMID:22022003

Integration of coastal inundation modeling from storm tides to individual waves

NASA Astrophysics Data System (ADS)

Li, Ning; Roeber, Volker; Yamazaki, Yoshiki; Heitmann, Troy W.; Bai, Yefei; Cheung, Kwok Fai

2014-11-01

Modeling of storm-induced coastal inundation has primarily focused on the surge generated by atmospheric pressure and surface winds with phase-averaged effects of the waves as setup. Through an interoperable model package, we investigate the role of phase-resolving wave processes in simulation of coastal flood hazards. A spectral ocean wave model describes generation and propagation of storm waves from deep to intermediate water, while a non-hydrostatic storm-tide model has the option to couple with a spectral coastal wave model for computation of phase-averaged processes in a near-shore region. The ocean wave and storm-tide models can alternatively provide the wave spectrum and the surface elevation as the boundary and initial conditions for a nested Boussinesq model. Additional surface-gradient terms in the Boussinesq equations maintain the quasi-steady, non-uniform storm tide for modeling of phase-resolving surf and swash-zone processes as well as combined tide, surge, and wave inundation. The two nesting schemes are demonstrated through a case study of Hurricane Iniki, which made landfall on the Hawaiian Island of Kauai in 1992. With input from a parametric hurricane model and global reanalysis and tidal datasets, the two approaches produce comparable significant wave heights and phase-averaged surface elevations in the surf zone. The nesting of the Boussinesq model provides a seamless approach to augment the inundation due to the individual waves in matching the recorded debris line along the coast.

Differential levels of brain amino acids in rat models presenting learned helplessness or non-learned helplessness.

PubMed

Muneoka, Katsumasa; Shirayama, Yukihiko; Horio, Mao; Iyo, Masaomi; Hashimoto, Kenji

2013-09-01

Glutamatergic and γ-aminobutyric acid (GABA)ergic abnormalities have recently been proposed to contribute to depression. The learned helplessness (LH) paradigm produces a reliable animal model of depression that expresses a deficit in escape behavior (LH model); an alternative phenotype that does not exhibit LH is a model of resilience to depression (non-LH model). We measured the contents of amino acids in the brain to investigate the mechanisms involved in the pathology of depression. LH and non-LH models were subjected to inescapable electric footshocks at random intervals following a conditioned avoidance test to determine acquirement of predicted escape deficits. Tissue amino acid contents in eight brain regions were measured via high-performance liquid chromatography. The non-LH model showed increased GABA levels in the dentate gyrus and nucleus accumbens and increased glutamine levels in the dentate gyrus and the orbitofrontal cortex. The LH model had reduced glutamine levels in the medial prefrontal cortex. Changes in the ratios of GABA, glutamine, and glutamate were detected in the non-LH model, but not in the LH model. Reductions in threonine levels occurred in the medial prefrontal cortex in both models, whereas elevated alanine levels were detected in the medial prefrontal cortex in non-LH animals. The present study demonstrates region-specific compensatory elevations in GABA levels in the dentate gyrus and nucleus accumbens of non-LH animals, supporting the implication of the GABAergic system in the recovery of depression.

Modelling study of sea breezes in a complex coastal environment

NASA Astrophysics Data System (ADS)

Cai, X.-M.; Steyn, D. G.

This study investigates a mesoscale modelling of sea breezes blowing from a narrow strait into the lower Fraser valley (LFV), British Columbia, Canada, during the period of 17-20 July, 1985. Without a nudging scheme in the inner grid, the CSU-RAMS model produces satisfactory wind and temperature fields during the daytime. In comparison with observation, the agreement indices for surface wind and temperature during daytime reach about 0.6 and 0.95, respectively, while the agreement indices drop to 0.4 at night. In the vertical, profiles of modelled wind and temperature generally agree with tethersonde data collected on 17 and 19 July. The study demonstrates that in late afternoon, the model does not capture the advection of an elevated warm layer which originated from land surfaces outside of the inner grid. Mixed layer depth (MLD) is calculated from model output of turbulent kinetic energy field. Comparison of MLD results with observation shows that the method generates a reliable MLD during the daytime, and that accurate estimates of MLD near the coast require the correct simulation of wind conditions over the sea. The study has shown that for a complex coast environment like the LFV, a reliable modelling study depends not only on local surface fluxes but also on elevated layers transported from remote land surfaces. This dependence is especially important when local forcings are weak, for example, during late afternoon and at night.

Carbothermic reduction and prereduced charge for producing aluminum-silicon alloys

DOEpatents

Stevenson, David T.; Troup, Robert L.

1985-01-01

Disclosed is a method for the carbothermic reduction of aluminum oxide to form an aluminum alloy including producing silicon carbide by heating a first mix of carbon and silicon oxide in a combustion reactor to an elevated temperature sufficient to produce silicon carbide at an accelerated rate, the heating being provided by an in situ combustion with oxygen gas, and then admixing the silicon carbide with carbon and aluminum oxide to form a second mix and heating the second mix in a second reactor to an elevated metal-forming temperature sufficient to produce aluminum-silicon alloy. The prereduction step includes holding aluminum oxide substantially absent from the combustion reactor. The metal-forming step includes feeding silicon oxide in a preferred ratio with silicon carbide.

Antisense oligonucleotide inhibition of apolipoprotein C-III reduces plasma triglycerides in rodents, nonhuman primates, and humans.

PubMed

Graham, Mark J; Lee, Richard G; Bell, Thomas A; Fu, Wuxia; Mullick, Adam E; Alexander, Veronica J; Singleton, Walter; Viney, Nick; Geary, Richard; Su, John; Baker, Brenda F; Burkey, Jennifer; Crooke, Stanley T; Crooke, Rosanne M

2013-05-24

Elevated plasma triglyceride levels have been recognized as a risk factor for the development of coronary heart disease. Apolipoprotein C-III (apoC-III) represents both an independent risk factor and a key regulatory factor of plasma triglyceride concentrations. Furthermore, elevated apoC-III levels have been associated with metabolic syndrome and type 2 diabetes mellitus. To date, no selective apoC-III therapeutic agent has been evaluated in the clinic. To test the hypothesis that selective inhibition of apoC-III with antisense drugs in preclinical models and in healthy volunteers would reduce plasma apoC-III and triglyceride levels. Rodent- and human-specific second-generation antisense oligonucleotides were identified and evaluated in preclinical models, including rats, mice, human apoC-III transgenic mice, and nonhuman primates. We demonstrated the selective reduction of both apoC-III and triglyceride in all preclinical pharmacological evaluations. We also showed that inhibition of apoC-III was well tolerated and not associated with increased liver triglyceride deposition or hepatotoxicity. A double-blind, placebo-controlled, phase I clinical study was performed in healthy subjects. Administration of the human apoC-III antisense drug resulted in dose-dependent reductions in plasma apoC-III, concomitant lowering of triglyceride levels, and produced no clinically meaningful signals in the safety evaluations. Antisense inhibition of apoC-III in preclinical models and in a phase I clinical trial with healthy subjects produced potent, selective reductions in plasma apoC-III and triglyceride, 2 known risk factors for cardiovascular disease. This compelling pharmacological profile supports further clinical investigations in hypertriglyceridemic subjects.

No Substitute for Going to the Field: Correcting Lidar DEMs in Salt Marshes

NASA Astrophysics Data System (ADS)

Renken, K.; Morris, J. T.; Lynch, J.; Bayley, H.; Neil, A.; Rasmussen, S.; Tyrrell, M.; Tanis, M.

2016-12-01

Models that forecast the response of salt marshes to current and future trends in sea level rise increasingly are used to guide management of these vulnerable ecosystems. Lidar-derived DEMs serve as the foundation for modeling landform change. However, caution is advised when using these DEMs as the starting point for models of salt marsh evolution. While broad vegetation class (i.e., young forest, old forest, grasslands, desert, etc.) has proven to be a significant predictor of vertical displacement error in terrestrial environments, differentiating error among different species or community types within the same ecosystem has received less attention. Salt marshes are dominated by monocultures of grass species and thus are an ideal environment to examine the within-species effect on lidar DEM error. We analyzed error of lidar DEMs using elevations from real-time kinematic (RTK) surveys in saltmarshes in multiple national parks and wildlife refuge areas from the mouth of the Chesapeake Bay to Massachusetts. Error of the lidar DEMs was sometimes large, on the order of 0.25 m, and varied significantly between sites because vegetation cover varies seasonally and lidar data was not always collected in the same season for each park. Vegetation cover and composition were used to explain differences between RTK elevations and lidar DEMs. This research underscores the importance of collecting RTK elevation data and vegetation cover data coincident with lidar data to produce correction factors specific to individual salt marsh sites.

Digital data sets that describe aquifer characteristics of the alluvial and terrace deposits along the Cimarron River from Freedom to Guthrie in northwestern Oklahoma

USGS Publications Warehouse

Adams, G.P.; Runkle, Donna; Rea, Alan; Cederstrand, J.R.

1997-01-01

ARC/INFO export and nonproprietary format files This diskette contains digitized aquifer boundaries, maps of hydraulic conductivity, recharge, and ground-water level elevation contours for the alluvial and terrace deposits along the Cimarron River from Freedom to Guthrie in northwestern Oklahoma. Ground water in 1,305 square miles of Quaternary-age alluvial and terrace deposits along the the Cimarron River from Freedom to Guthrie is an important source of water for irrigation, industrial, municipal, stock, and domestic supplies. Alluvial and terrace deposits are composed of interfingering lenses of clay, sandy clay, and cross-bedded poorly sorted sand and gravel. The aquifer is composed of hydraulically connected alluvial and terrace deposits that unconformably overlie the Permian-age Formations. The aquifer boundaries are from a ground-water modeling report on the alluvial and terrace aquifer along the Cimarron River from Freedom to Guthrie in northwestern Oklahoma and published digital surficial geology data sets. The aquifer boundary data set was created from digital geologic data sets from maps published at a scale of 1:250,000. The hydraulic conductivity values, recharge rates, and ground-water level elevation contours are from the ground-water modeling report. Water-level elevation contours were digitized from a map at a scale of 1:250,000. The maps were published at a scale of 1:900,000. Ground-water flow models are numerical representations that simplify and aggregate natural systems. Models are not unique; different combinations of aquifer characteristics may produce similar results. Therefore, values of hydraulic conductivity and recharge used in the model and presented in this data set are not precise, but are within a reasonable range when compared to independently collected data.

ArcticDEM Year 3; Improving Coverage, Repetition and Resolution

NASA Astrophysics Data System (ADS)

Morin, P. J.; Porter, C. C.; Cloutier, M.; Howat, I.; Noh, M. J.; Willis, M. J.; Candela, S. G.; Bauer, G.; Kramer, W.; Bates, B.; Williamson, C.

2017-12-01

Surface topography is among the most fundamental data sets for geosciences, essential for disciplines ranging from glaciology to geodynamics. The ArcticDEM project is using sub-meter, commercial imagery licensed by the National Geospatial-Intelligence Agency, petascale computing, and open source photogrammetry software to produce a time-tagged 2m posting elevation model and a 5m posting mosaic of the entire Arctic region. As ArcticDEM enters its third year, the region has gone from having some of the sparsest and poorest elevation data to some of the most precise and complete data of any region on the globe. To date, we have produced and released over 80,000,000 km2 as 57,000 - 2m posting, time-stamped DEMs. The Arctic, on average, is covered four times though there are hotspots with more than 100 DEMs. In addition, the version 1 release includes a 5m posting mosaic covering the entire 20,000,000 km2 region. All products are publically available through arctidem.org, ESRI web services, and a web viewer. The final year of the project will consist of a complete refiltering of clouds/water and re-mosaicing of all elevation data. Since inception of the project, post-processing techniques have improved significantly, resulting in fewer voids, better registration, sharper coastlines, and fewer inaccuracies due to clouds. All ArcticDEM data will be released in 2018. Data, documentation, web services and web viewer are available at arcticdem.org

Simulating the meteorology and PM10 concentrations in Arizona dust storms using the Weather Research and Forecasting model with Chemistry (Wrf-Chem).

PubMed

Hyde, Peter; Mahalov, Alex; Li, Jialun

2018-03-01

Nine dust storms in south-central Arizona were simulated with the Weather Research and Forecasting with Chemistry model (WRF-Chem) at 2 km resolution. The windblown dust emission algorithm was the Air Force Weather Agency model. In comparison with ground-based PM 10 observations, the model unevenly reproduces the dust-storm events. The model adequately estimates the location and timing of the events, but it is unable to precisely replicate the magnitude and timing of the elevated hourly concentrations of particles 10 µm and smaller ([PM 10 ]).Furthermore, the model underestimated [PM 10 ] in highly agricultural Pinal County because it underestimated surface wind speeds and because the model's erodible fractions of the land surface data were too coarse to effectively resolve the active and abandoned agricultural lands. In contrast, the model overestimated [PM 10 ] in western Arizona along the Colorado River because it generated daytime sea breezes (from the nearby Gulf of California) for which the surface-layer speeds were too strong. In Phoenix, AZ, the model's performance depended on the event, with both under- and overestimations partly due to incorrect representation of urban features. Sensitivity tests indicate that [PM 10 ] highly relies on meteorological forcing. Increasing the fraction of erodible surfaces in the Pinal County agricultural areas improved the simulation of [PM 10 ] in that region. Both 24-hr and 1-hr measured [PM 10 ] were, for the most part, and especially in Pinal County, extremely elevated, with the former exceeding the health standard by as much as 10-fold and the latter exceeding health-based guidelines by as much as 70-fold. Monsoonal thunderstorms not only produce elevated [PM 10 ], but also cause urban flash floods and disrupt water resource deliveries. Given the severity and frequency of these dust storms, and conceding that the modeling system applied in this work did not produce the desired agreement between simulations and observations, additional research in both the windblown dust emissions model and the weather research/physicochemical model is called for. While many dust storms can be considered to be natural, in semi-arid climates such storms often have an anthropogenic component in their sources of dust. Applying the natural, exceptional events policy to these storms with strong signatures of anthropogenic sources would appear not only to be misguided but also to stifle genuine regulatory efforts at remediation. Those dust storms that have resulted, in part, from passage over abandoned farm land should no longer be considered "natural"; policymakers and lawmakers need to compel the owners of such land to reduce its potential for windblown dust.

Topography of the Moon from the Clementine Lidar

NASA Technical Reports Server (NTRS)

Smith, David E.; Zuber, Maria T.; Neumann, Gregory A.; Lemoine, Frank G.

1997-01-01

Range measurements from the lidar instrument carried aboard the Clementine spacecraft have been used to produce an accurate global topographic model of the Moon. This paper discusses the function of the lidar; the acquisition, processing, and filtering of observations to produce a global topographic model; and the determination of parameters that define the fundamental shape of the Moon. Our topographic model: a 72nd degree and order spherical harmonic expansion of lunar radii, is designated Goddard Lunar Topography Model 2 (GLTM 2). This topographic field has an absolute vertical accuracy of approximately 100 m and a spatial resolution of 2.5 deg. The field shows that the Moon can be described as a sphere with maximum positive and negative deviations of approx. 8 km, both occurring on the farside, in the areas of the Korolev and South Pole-Aitken (S.P.-Aitken) basins. The amplitude spectrum of the topography shows more power at longer wavelengths as compared to previous models, owing to more complete sampling of the surface, particularly the farside. A comparison of elevations derived from the Clementine lidar to control point elevations from the Apollo laser altimeters indicates that measured relative topographic heights generally agree to within approx. 200 in over the maria. While the major axis of the lunar gravity field is aligned in the Earth-Moon direction, the major axis of topography is displaced from this line by approximately 10 deg to the cast and intersects the farside 24 deg north of the equator. The magnitude of impact basin topography is greater than the lunar flattening (approx. 2 km) and equatorial ellipticity (approx. 800 m), which imposes a significant challenge to interpreting the lunar figure. The floors of mare basins are shown to lie close to an equipotential surface, while the floors of unflooded large basins, except for S.P.-Aitken, lie above this equipotential. The radii of basin floors are thus consistent with a hydrostatic mechanism for the absence of significant farside maria except for S.P.-Aitken, whose depth and lack of mare require significant internal compositional and/or thermal heterogeneity. A macroscale surface roughness map shows that roughness at length scales of 10(exp 1) - 10(exp 2) km correlates with elevation and surface age.

Process for producing amorphous and crystalline silicon nitride

DOEpatents

Morgan, P.E.D.; Pugar, E.A.

1985-11-12

A process for producing amorphous or crystalline silicon nitride is disclosed which comprises reacting silicon disulfide ammonia gas at elevated temperature. In a preferred embodiment silicon disulfide in the form of whiskers'' or needles is heated at temperature ranging from about 900 C to about 1,200 C to produce silicon nitride which retains the whisker or needle morphological characteristics of the silicon disulfide. Silicon carbide, e.g. in the form of whiskers, also can be prepared by reacting substituted ammonia, e.g. methylamine, or a hydrocarbon containing active hydrogen-containing groups, such as ethylene, with silicon disulfide, at elevated temperature, e.g. 900 C. 6 figs.

Process for producing amorphous and crystalline silicon nitride

DOEpatents

Morgan, Peter E. D.; Pugar, Eloise A.

1985-01-01

A process for producing amorphous or crystalline silicon nitride is disclosed which comprises reacting silicon disulfide ammonia gas at elevated temperature. In a preferred embodiment silicon disulfide in the form of "whiskers" or needles is heated at temperature ranging from about 900.degree. C. to about 1200.degree. C. to produce silicon nitride which retains the whisker or needle morphological characteristics of the silicon disulfide. Silicon carbide, e.g. in the form of whiskers, also can be prepared by reacting substituted ammonia, e.g. methylamine, or a hydrocarbon containing active hydrogen-containing groups, such as ethylene, with silicon disulfide, at elevated temperature, e.g. 900.degree. C.

Dam-breach analysis and flood-inundation mapping for Lakes Ellsworth and Lawtonka near Lawton, Oklahoma

USGS Publications Warehouse

Rendon, Samuel H.; Ashworth, Chad E.; Smith, S. Jerrod

2012-01-01

Dams provide beneficial functions such as flood control, recreation, and reliable water supplies, but they also entail risk: dam breaches and resultant floods can cause substantial property damage and loss of life. The State of Oklahoma requires each owner of a high-hazard dam, which the Federal Emergency Management Agency defines as dams for which failure or misoperation probably will cause loss of human life, to develop an emergency action plan specific to that dam. Components of an emergency action plan are to simulate a flood resulting from a possible dam breach and map the resulting downstream flood-inundation areas. The resulting flood-inundation maps can provide valuable information to city officials, emergency managers, and local residents for planning the emergency response if a dam breach occurs. Accurate topographic data are vital for developing flood-inundation maps. This report presents results of a cooperative study by the city of Lawton, Oklahoma, and the U.S. Geological Survey (USGS) to model dam-breach scenarios at Lakes Ellsworth and Lawtonka near Lawton and to map the potential flood-inundation areas of such dam breaches. To assist the city of Lawton with completion of the emergency action plans for Lakes Ellsworth and Lawtonka Dams, the USGS collected light detection and ranging (lidar) data that were used to develop a high-resolution digital elevation model and a 1-foot contour elevation map for the flood plains downstream from Lakes Ellsworth and Lawtonka. This digital elevation model and field measurements, streamflow-gaging station data (USGS streamflow-gaging station 07311000, East Cache Creek near Walters, Okla.), and hydraulic values were used as inputs for the dynamic (unsteady-flow) model, Hydrologic Engineering Center's River Analysis System (HEC-RAS). The modeled flood elevations were exported to a geographic information system to produce flood-inundation maps. Water-surface profiles were developed for a 75-percent probable maximum flood scenario and a sunny-day dam-breach scenario, as well as for maximum flood-inundation elevations and flood-wave arrival times for selected bridge crossings. Some areas of concern near the city of Lawton, if a dam breach occurs at Lakes Ellsworth or Lawtonka, include water treatment plants, wastewater treatment plants, recreational areas, and community-services offices.

Optimization of the resolution of remotely sensed digital elevation model to facilitate the simulation and spatial propagation of flood events in flat areas

NASA Astrophysics Data System (ADS)

Karapetsas, Nikolaos; Skoulikaris, Charalampos; Katsogiannos, Fotis; Zalidis, George; Alexandridis, Thomas

2013-04-01

The use of satellite remote sensing products, such as Digital Elevation Models (DEMs), under specific computational interfaces of Geographic Information Systems (GIS) has fostered and facilitated the acquisition of data on specific hydrologic features, such as slope, flow direction and flow accumulation, which are crucial inputs to hydrology or hydraulic models at the river basin scale. However, even though DEMs of different resolution varying from a few km up to 20m are freely available for the European continent, these remotely sensed elevation data are rather coarse in cases where large flat areas are dominant inside a watershed, resulting in an unsatisfactory representation of the terrain characteristics. This scientific work aims at implementing a combing interpolation technique for the amelioration of the analysis of a DEM in order to be used as the input ground model to a hydraulic model for the assessment of potential flood events propagation in plains. More specifically, the second version of the ASTER Global Digital Elevation Model (GDEM2), which has an overall accuracy of around 20 meters, was interpolated with a vast number of aerial control points available from the Hellenic Mapping and Cadastral Organization (HMCO). The uncertainty that was inherent in both the available datasets (ASTER & HMCO) and the appearance of uncorrelated errors and artifacts was minimized by incorporating geostatistical filtering. The resolution of the produced DEM was approximately 10 meters and its validation was conducted with the use of an external dataset of 220 geodetic survey points. The derived DEM was then used as an input to the hydraulic model InfoWorks RS, whose operation is based on the relief characteristics contained in the ground model, for defining, in an automated way, the cross section parameters and simulating the flood spatial distribution. The plain of Serres, which is located in the downstream part of the Struma/Strymon transboundary river basin shared by Bulgaria and Greece, was selected as the case study area, because of its importance to the regional and national economy of Greece and because of the numerous flood events recorded in the past. The results of the simulation processing demonstrated the importance of high resolution relief models for estimating the potential flood hazard zones in order to mitigate the catastrophe caused, both in economic and environmental terms, by this type of extreme event.

Risk of fire occurrence in arid and semi-arid ecosystems of Iran: an investigation using Bayesian belief networks.

PubMed

Bashari, Hossein; Naghipour, Ali Asghar; Khajeddin, Seyed Jamaleddin; Sangoony, Hamed; Tahmasebi, Pejman

2016-09-01

Identifying areas that have a high risk of burning is a main component of fire management planning. Although the available tools can predict the fire risks, these are poor in accommodating uncertainties in their predictions. In this study, we accommodated uncertainty in wildfire prediction using Bayesian belief networks (BBNs). An influence diagram was developed to identify the factors influencing wildfire in arid and semi-arid areas of Iran, and it was populated with probabilities to produce a BBNs model. The behavior of the model was tested using scenario and sensitivity analysis. Land cover/use, mean annual rainfall, mean annual temperature, elevation, and livestock density were recognized as the main variables determining wildfire occurrence. The produced model had good accuracy as its ROC area under the curve was 0.986. The model could be applied in both predictive and diagnostic analysis for answering "what if" and "how" questions. The probabilistic relationships within the model can be updated over time using observation and monitoring data. The wildfire BBN model may be updated as new knowledge emerges; hence, it can be used to support the process of adaptive management.

Effects of Long-Term Thermal Exposure on Commercially Pure Titanium Grade 2 Elevated-Temperature Tensile Properties

NASA Technical Reports Server (NTRS)

Ellis, David L.

2012-01-01

Elevated-temperature tensile testing of commercially pure titanium (CP Ti) Grade 2 was conducted for as-received commercially produced sheet and following thermal exposure at 550 and 650 K (531 and 711 F) for times up to 5000 h. The tensile testing revealed some statistical differences between the 11 thermal treatments, but most thermal treatments were statistically equivalent. Previous data from room temperature tensile testing was combined with the new data to allow regression and development of mathematical models relating tensile properties to temperature and thermal exposure. The results indicate that thermal exposure temperature has a very small effect, whereas the thermal exposure duration has no statistically significant effects on the tensile properties. These results indicate that CP Ti Grade 2 will be thermally stable and suitable for long-duration space missions.

A Comparative Study of Radar Stereo and Interferometry for DEM Generation

NASA Astrophysics Data System (ADS)

Gelautz, M.; Paillou, P.; Chen, C. W.; Zebker, H. A.

2004-06-01

In this experiment, we derive and compare radar stereo and interferometric elevation models (DEMs) of a study site in Djibouti, East Africa. As test data, we use a Radarsat stereo pair and ERS-2 and Radarsat interferometric data. Comparison of the reconstructed DEMs with a SPOT reference DEM shows that in regions of high coherence the DEMs produced by interferometry are of much better quality than the stereo result. However, the interferometric error histograms also show some pronounced outliers due to decorrelation and phase unwrapping problems on forested mountain slopes. The more robust stereo result is able to capture the general terrain shape, but finer surface details are lost. A fusion experiment demonstrates that merging the stereoscopic and interferometric DEMs by utilizing coherence- derived weights can significantly improve the accuracy of the computed elevation maps.

"Modeled and measured carbon cycling in Mojave Desert soils: toward present and projected greenhouse gas budgets for arid regions

NASA Astrophysics Data System (ADS)

Maurer, G. E.; Amundson, R.; Lammers, L. N.; Mills, J.; Oerter, E.

2017-12-01

Drylands comprise roughly 35% of the Earth's surface, store globally significant amounts of carbon, and cycle this carbon at rates that vary greatly from year to year. Consequently, drylands are thought to contribute to inter-annual changes in the global atmospheric CO2 budget. Sparse measurements and limited process-based modeling have made quantifying dryland carbon cycling at regional or larger scales a major challenge. We parameterized and ran the DayCent model, an ecosystem model that simulates soil C and N cycling and greenhouse gas (GHG) fluxes, using long-term regional climate, soil, and vegetation data for the Mojave Desert region (southwest USA). DayCent predicted somewhat greater soil organic C than was observed in a database of 186 measured Mojave soil survey samples, but successfully recreated climate-driven patterns in soil carbon storage across the landscape. Modeled soil organic carbon storage increased by between 4.1 and 5.1 kg/m2 per km of elevation gained, while Mojave soil survey data indicated an increase of 4.6 kg/m2. Model predictions of soil CO2 flux were validated and calibrated against field observations from ten Mojave soil gas profile studies sampled intermittently between 1986 and the present. DayCent had a tendency to overestimate soil respiration measured at some sites by up to 600% compared to profile measurements. Modeled soil CO2 fluxes increased by between 1280 and 4141 kg/ha/yr per km of elevation gained.This elevational pattern did not match well with landscape-level changes in observed soil profile CO2 flux data, indicating further calibration of DayCent will be needed to produce regional estimates of GHG flux. This ongoing synthesis of modeling and measurements extends the current knowledge of the Mojave's contribution to the global GHG budget and will provide a basis from which to project future emissions from the Mojave and other dryland regions.

Differential Effects of IL6 and Activin A in the Development of Cancer-Associated Cachexia.

PubMed

Chen, Justin L; Walton, Kelly L; Qian, Hongwei; Colgan, Timothy D; Hagg, Adam; Watt, Matthew J; Harrison, Craig A; Gregorevic, Paul

2016-09-15

Cachexia is a life-threatening wasting syndrome lacking effective treatment, which arises in many cancer patients. Although ostensibly induced by multiple tumor-produced cytokines (tumorkines), their functional contribution to initiation and progression of this syndrome has proven difficult to determine. In this study, we used adeno-associated viral vectors to elevate circulating levels of the tumorkines IL6 and/or activin A in animals in the absence of tumors as a tactic to evaluate hypothesized roles in cachexia development. Mice with elevated levels of IL6 exhibited 8.1% weight loss after 9 weeks, whereas mice with elevated levels of activin A lost 11% of their body weight. Co-elevation of both tumorkines to levels approximating those observed in cancer cachexia models induced a more rapid and profound body weight loss of 15.4%. Analysis of body composition revealed that activin A primarily triggered loss of lean mass, whereas IL6 was a major mediator of fat loss. Histologic and transcriptional analysis of affected organs/tissues (skeletal muscle, fat, and liver) identified interactions between the activin A and IL6 signaling pathways. For example, IL6 exacerbated the detrimental effects of activin A in skeletal muscle, whereas activin A curbed the IL6-induced acute-phase response in liver. This study presents a useful model to deconstruct cachexia, opening a pathway to determining which tumorkines are best targeted to slow/reverse this devastating condition in cancer patients. Cancer Res; 76(18); 5372-82. ©2016 AACR. ©2016 American Association for Cancer Research.

Surface topography of the Greenland Ice Sheet from satellite radar altimetry

NASA Technical Reports Server (NTRS)

Bindschadler, Robert A.; Zwally, H. Jay; Major, Judith A.; Brenner, Anita C.

1989-01-01

Surface elevation maps of the southern half of the Greenland subcontinent are produced from radar altimeter data acquired by the Seasat satellite. A summary of the processing procedure and examples of return waveform data are given. The elevation data are used to generate a regular grid which is then computer contoured to provide an elevation contour map. Ancillary maps show the statistical quality of the elevation data and various characteristics of the surface. The elevation map is used to define ice flow directions and delineate the major drainage basins. Regular maps of the Jakobshavns Glacier drainage basin and the ice divide in the vicinity of Crete Station are presented. Altimeter derived elevations are compared with elevations measured both by satellite geoceivers and optical surveying.

Global transcriptomic profiling of aspen trees under elevated [CO2] to identify potential molecular mechanisms responsible for enhanced radial growth.

PubMed

Wei, Hairong; Gou, Jiqing; Yordanov, Yordan; Zhang, Huaxin; Thakur, Ramesh; Jones, Wendy; Burton, Andrew

2013-03-01

Aspen (Populus tremuloides) trees growing under elevated [CO(2)] at a free-air CO(2) enrichment (FACE) site produced significantly more biomass than control trees. We investigated the molecular mechanisms underlying the observed increase in biomass by producing transcriptomic profiles of the vascular cambium zone (VCZ) and leaves, and then performed a comparative study to identify significantly changed genes and pathways after 12 years exposure to elevated [CO(2)]. In leaves, elevated [CO(2)] enhanced expression of genes related to Calvin cycle activity and linked pathways. In the VCZ, the pathways involved in cell growth, cell division, hormone metabolism, and secondary cell wall formation were altered while auxin conjugation, ABA synthesis, and cytokinin glucosylation and degradation were inhibited. Similarly, the genes involved in hemicellulose and pectin biosynthesis were enhanced, but some genes that catalyze important steps in lignin biosynthesis pathway were inhibited. Evidence from systemic analysis supported the functioning of multiple molecular mechanisms that underpin the enhanced radial growth in response to elevated [CO(2)].

Radar imaging using electromagnetic wave carrying orbital angular momentum

NASA Astrophysics Data System (ADS)

Yuan, Tiezhu; Cheng, Yongqiang; Wang, Hongqiang; Qin, Yuliang; Fan, Bo

2017-03-01

The concept of radar imaging based on orbital angular momentum (OAM) modulation, which has the ability of azimuthal resolution without relative motion, has recently been proposed. We investigate this imaging technique further in greater detail. We first analyze the principle of the technique, accounting for its resolving ability physically. The phase and intensity distributions of the OAM-carrying fields produced by phased uniform circular array antenna, which have significant effects on the imaging results, are investigated. The imaging model shows that the received signal has the form of inverse discrete Fourier transform with the use of OAM and frequency diversities. The two-dimensional Fourier transform is employed to reconstruct the target images in the case of large and small elevation angles. Due to the peculiar phase and intensity characteristics, the small elevation is more suitable for practical application than the large one. The minimum elevation angle is then obtained given the array parameters. The imaging capability is analyzed by means of the point spread function. All results are verified through numerical simulations. The proposed staring imaging technique can achieve extremely high azimuthal resolution with the use of plentiful OAM modes.

Orogenic plateau growth: Expansion of the Turkish-Iranian Plateau across the Zagros fold-and-thrust belt

NASA Astrophysics Data System (ADS)

Allen, M. B.; Saville, C.; Blanc, E. J.-P.; Talebian, M.; Nissen, E.

2013-03-01

This paper shows how the Turkish-Iranian Plateau grows laterally by incrementally incorporating adjacent parts of the Zagros fold-and-thrust belt. The limit of significant, seismogenic, thrusting in the Zagros (Mw > 5) occurs close to the regional 1250 m elevation contour. The seismicity cutoff is not a significant bedrock geology boundary. Elevations increase northward, toward regional plateau elevations of 2 km, implying that another process produced the extra elevation. Between the seismogenic limit of thrusting and the suture, this process is a plausibly ductile thickening of the basement, suggesting depth-dependent strain during compression. Similar depth-dependant crustal strain may explain why the Tibetan plateau has regional elevations 1500 m greater than the elevation limit of seismogenic thrusting at its margins. We estimate 68 km shortening across the Zagros Simply Folded Belt in the Fars region, and 120 km total shortening of the Arabian plate. The Dezful Embayment is a low strain zone in the western Zagros. Deformation is more intense to its northeast, in the Bakhtyari Culmination. The orogenic taper (across strike topographic gradient) across the Dezful Embayment is 0.0004, and across the Bakhtyari Culmination, 0.022. Lateral plateau growth is more pronounced farther east (Fars), where a more uniform structure has a taper of 0.010 up to elevations of 1750 m. A >100 km wide region of the Zagros further northeast has a taper of 0.002 and is effectively part of the Turkish-Iranian Plateau. Internal drainage enhances plateau development but is not a pre-requisite. Aspects of the seismicity, structure, and geomorphology of the Zagros do not support critical taper models for fold-and-thrust belts.

Elevated carboxyhemoglobin in a marine mammal, the northern elephant seal

PubMed Central

Tift, Michael S.; Ponganis, Paul J.; Crocker, Daniel E.

2014-01-01

Low concentrations of endogenous carbon monoxide (CO), generated primarily through degradation of heme from heme-proteins, have been shown to maintain physiological function of organs and to exert cytoprotective effects. However, high concentrations of carboxyhemoglobin (COHb), formed by CO binding to hemoglobin, potentially prevent adequate O2 delivery to tissues by lowering arterial O2 content. Elevated heme-protein concentrations, as found in marine mammals, are likely associated with greater heme degradation, more endogenous CO production and, consequently, elevated COHb concentrations. Therefore, we measured COHb in elephant seals, a species with large blood volumes and elevated hemoglobin and myoglobin concentrations. The levels of COHb were positively related to the total hemoglobin concentration. The maximum COHb value was 10.4% of total hemoglobin concentration. The mean (±s.e.m.) value in adult seals was 8.7±0.3% (N=6), while juveniles and pups (with lower heme-protein contents) had lower mean COHb values of 7.6±0.2% and 7.1±0.3%, respectively (N=9 and N=9, respectively). Serial samples over several hours revealed little to no fluctuation in COHb values. This consistent elevation in COHb suggests that the magnitude and/or rate of heme-protein turnover is much higher than in terrestrial mammals. The maximum COHb values from this study decrease total body O2 stores by 7%, thereby reducing the calculated aerobic dive limit for this species. However, the constant presence of elevated CO in blood may also protect against potential ischemia–reperfusion injury associated with the extreme breath-holds of elephant seals. We suggest the elephant seal represents an ideal model for understanding the potential cytoprotective effects, mechanisms of action and evolutionary adaptation associated with chronically elevated concentrations of endogenously produced CO. PMID:24829326

Elevated carboxyhemoglobin in a marine mammal, the northern elephant seal.

PubMed

Tift, Michael S; Ponganis, Paul J; Crocker, Daniel E

2014-05-15

Low concentrations of endogenous carbon monoxide (CO), generated primarily through degradation of heme from heme-proteins, have been shown to maintain physiological function of organs and to exert cytoprotective effects. However, high concentrations of carboxyhemoglobin (COHb), formed by CO binding to hemoglobin, potentially prevent adequate O2 delivery to tissues by lowering arterial O2 content. Elevated heme-protein concentrations, as found in marine mammals, are likely associated with greater heme degradation, more endogenous CO production and, consequently, elevated COHb concentrations. Therefore, we measured COHb in elephant seals, a species with large blood volumes and elevated hemoglobin and myoglobin concentrations. The levels of COHb were positively related to the total hemoglobin concentration. The maximum COHb value was 10.4% of total hemoglobin concentration. The mean (± s.e.m.) value in adult seals was 8.7 ± 0.3% (N=6), while juveniles and pups (with lower heme-protein contents) had lower mean COHb values of 7.6 ± 0.2% and 7.1 ± 0.3%, respectively (N=9 and N=9, respectively). Serial samples over several hours revealed little to no fluctuation in COHb values. This consistent elevation in COHb suggests that the magnitude and/or rate of heme-protein turnover is much higher than in terrestrial mammals. The maximum COHb values from this study decrease total body O2 stores by 7%, thereby reducing the calculated aerobic dive limit for this species. However, the constant presence of elevated CO in blood may also protect against potential ischemia-reperfusion injury associated with the extreme breath-holds of elephant seals. We suggest the elephant seal represents an ideal model for understanding the potential cytoprotective effects, mechanisms of action and evolutionary adaptation associated with chronically elevated concentrations of endogenously produced CO. © 2014. Published by The Company of Biologists Ltd.

Hydraulic analysis of the Schoharie Creek bridge

USGS Publications Warehouse

Froehlich, David C.; Trent, Roy E.

1989-01-01

Ten people died on April 5, 1987 as a result of the collapse of two spans of a New York State Thruway bridge into the floodwaters of Schoharie Creek. The cause of the bridge failure was determined to be scour of bed material from under the foundations of piers supporting the bridge. To evaluate the hydraulic conditions that produced the scour, a two-dimensional finite element surface-water flow model was constructed. The model was used to obtain a detailed description of water-surface elevations and depth-averaged velocities within a reach that extends from about 4000 ft downstream of the bridge to about 6000 ft upstream of the bridge.

Exploring the genetic basis of adaptation to high elevations in reptiles: a comparative transcriptome analysis of two toad-headed agamas (genus Phrynocephalus).

PubMed

Yang, Weizhao; Qi, Yin; Fu, Jinzhong

2014-01-01

High elevation adaptation offers an excellent study system to understand the genetic basis of adaptive evolution. We acquired transcriptome sequences of two closely related lizards, Phrynocephalus przewalskii from low elevations and P. vlangalii from high elevations. Within a phylogenetic framework, we compared their genomic data along with green anole, chicken and Chinese softshell turtle, and identified candidate genes and functional categories that are potentially linked to adaptation to high elevation environments. More than 100 million sequence reads were generated for each species via Illumina sequencing. A de novo assembly produced 70,919 and 62,118 transcripts for P. przewalskii and P. vlangalii, respectively. Based on a well-established reptile phylogeny, we detected 143 positively selected genes (PSGs) along the P. vlangalii lineage from the 7,012 putative orthologs using a branch-site model. Furthermore, ten GO categories and one KEGG pathway that are over-represented by PSGs were recognized. In addition, 58 GO categories were revealed to have elevated evolutionary rates along the P. vlangalii lineage relative to P. przewalskii. These functional analyses further filter out PSGs that are most likely involved in the adaptation process to high elevations. Among them, ADAM17, MD, and HSP90B1 likely contributed to response to hypoxia, and POLK likely contributed to DNA repair. Many other candidate genes involved in gene expression and metabolism were also identified. Genome-wide scan for candidate genes may serve as the first step to explore the genetic basis of high elevation adaptation. Detailed comparative study and functional verification are needed to solidify any conclusions. High elevation adaptation requires coordinated changes in multiple genes that involve various physiological and biochemical pathways; we hope that our genetic studies will provide useful directions for future physiological or molecular studies in reptiles as well as other poikilothermic species.

Exploring the Genetic Basis of Adaptation to High Elevations in Reptiles: A Comparative Transcriptome Analysis of Two Toad-Headed Agamas (Genus Phrynocephalus)

PubMed Central

Yang, Weizhao; Qi, Yin; Fu, Jinzhong

2014-01-01

High elevation adaptation offers an excellent study system to understand the genetic basis of adaptive evolution. We acquired transcriptome sequences of two closely related lizards, Phrynocephalus przewalskii from low elevations and P. vlangalii from high elevations. Within a phylogenetic framework, we compared their genomic data along with green anole, chicken and Chinese softshell turtle, and identified candidate genes and functional categories that are potentially linked to adaptation to high elevation environments. More than 100 million sequence reads were generated for each species via Illumina sequencing. A de novo assembly produced 70,919 and 62,118 transcripts for P. przewalskii and P. vlangalii, respectively. Based on a well-established reptile phylogeny, we detected 143 positively selected genes (PSGs) along the P. vlangalii lineage from the 7,012 putative orthologs using a branch-site model. Furthermore, ten GO categories and one KEGG pathway that are over-represented by PSGs were recognized. In addition, 58 GO categories were revealed to have elevated evolutionary rates along the P. vlangalii lineage relative to P. przewalskii. These functional analyses further filter out PSGs that are most likely involved in the adaptation process to high elevations. Among them, ADAM17, MD, and HSP90B1 likely contributed to response to hypoxia, and POLK likely contributed to DNA repair. Many other candidate genes involved in gene expression and metabolism were also identified. Genome-wide scan for candidate genes may serve as the first step to explore the genetic basis of high elevation adaptation. Detailed comparative study and functional verification are needed to solidify any conclusions. High elevation adaptation requires coordinated changes in multiple genes that involve various physiological and biochemical pathways; we hope that our genetic studies will provide useful directions for future physiological or molecular studies in reptiles as well as other poikilothermic species. PMID:25386640

Modeling sediment transport after ditch network maintenance of a forested peatland

NASA Astrophysics Data System (ADS)

Haahti, K.; Marttila, H.; Warsta, L.; Kokkonen, T.; Finér, L.; Koivusalo, H.

2016-11-01

Elevated suspended sediment (SS) loads released from peatlands after drainage operations and the resulting negative effect on the ecological status of the receiving water bodies have been widely recognized. Understanding the processes controlling erosion and sediment transport within the ditch network forms a prerequisite for adequate sediment control. While numerous experimental studies have been reported in this field, model based assessments are rare. This study presents a modeling approach to investigate sediment transport in a peatland ditch network. The transport model describes bed erosion, rain-induced bank erosion, floc deposition, and consolidation of the bed. Coupled to a distributed hydrological model, sediment transport was simulated in a 5.2 ha forestry-drained peatland catchment for 2 years after ditch cleaning. Comparing simulation results to measured SS concentrations suggested that the loose peat material, produced during excavation, contributed markedly to elevated SS concentrations immediately after ditch cleaning. Both snowmelt and summer rainstorms contributed critically to annual loads. Springtime peat erosion during snowmelt was driven by ditch flow whereas during summer rainfalls, bank erosion by raindrop impact was identified as an important process. Relating modeling results to observed spatial topographic changes in the ditch network was challenging and the results were difficult to verify. Nevertheless, the model has potential to identify risk areas for erosion. The results demonstrate that modeling is effective in separating the importance of different processes and complements pure experimental approaches. Modeling results can aid planning and designing efficient sediment control measures and guide the focus of experimental studies.

Glucocorticoid effects on immune cell activation by staphylococcal exotoxins and lipopolysaccharide

NASA Technical Reports Server (NTRS)

Chapes, S. K.; Kopydlowski, K. M.; Fleming, S. D.; Iandolo, J. J.; Spooner, B. S. (Principal Investigator)

1992-01-01

Experiments were conducted to determine the effects of physiologically elevated corticosterone on the activation of macrophages and T cells. These studies find that the elevation of corticosterone does not affect the expression of membrane receptors on macrophages and does not affect the activation of macrophages to produce cytokines. In contrast, elevated corticosterone levels correlate with enhanced T cell proliferation to both mitogens and superantigens.

Galectin-1 Protein Therapy Prevents Pathology and Improves Muscle Function in the mdx Mouse Model of Duchenne Muscular Dystrophy.

PubMed

Van Ry, Pam M; Wuebbles, Ryan D; Key, Megan; Burkin, Dean J

2015-08-01

Duchenne muscular dystrophy (DMD) is a fatal neuromuscular disease caused by mutations in the dystrophin gene, leading to the loss of a critical component of the sarcolemmal dystrophin glycoprotein complex. Galectin-1 is a small 14 kDa protein normally found in skeletal muscle and has been shown to be a modifier of immune response, muscle repair, and apoptosis. Galectin-1 levels are elevated in the muscle of mouse and dog models of DMD. Together, these findings led us to hypothesize that Galectin-1 may serve as a modifier of disease progression in DMD. To test this hypothesis, recombinant mouse Galectin-1 was produced and used to treat myogenic cells and the mdx mouse model of DMD. Here we show that intramuscular and intraperitoneal injections of Galectin-1 into mdx mice prevented pathology and improved muscle function in skeletal muscle. These improvements were a result of enhanced sarcolemmal stability mediated by elevated utrophin and α7β1 integrin protein levels. Together our results demonstrate for the first time that Galectin-1 may serve as an exciting new protein therapeutic for the treatment of DMD.

Mars digital terrain model

NASA Technical Reports Server (NTRS)

Wu, Sherman S. C.; Howington, Annie-Elpis

1987-01-01

The Mars Digital Terrain Model (DTM) is the result of a new project to: (1) digitize the series of 1:2,000,000-scale topographic maps of Mars, which are being derived photogrammetically under a separate project, and (2) reformat the digital contour information into rasters of elevation that can be readily registered with the Digital Image Model (DIM) of Mars. Derivation of DTM's involves interpolation of elevation values into 1/64-degree resolution and transformation of them to a sinusoidal equal-area projection. Digital data are produced in blocks corresponding with the coordinates of the original 1:2,000,000-scale maps, i.e., the dimensions of each block in the equatorial belt are 22.5 deg of longitude and 15 deg of latitude. This DTM is not only compatible with the DIM, but it can also be registered with other data such as geologic units or gravity. It will be the most comprehensive record of topographic information yet compiled for the Martian surface. Once the DTM's are established, any enhancement of Mars topographic information made with updated data, such as data from the planned Mars Observer Mission, will be by mathematical transformation of the DTM's, eliminating the need for recompilation.

Arsenic concentrations, related environmental factors, and the predicted probability of elevated arsenic in groundwater in Pennsylvania

USGS Publications Warehouse

Gross, Eliza L.; Low, Dennis J.

2013-01-01

Logistic regression models were created to predict and map the probability of elevated arsenic concentrations in groundwater statewide in Pennsylvania and in three intrastate regions to further improve predictions for those three regions (glacial aquifer system, Gettysburg Basin, Newark Basin). Although the Pennsylvania and regional predictive models retained some different variables, they have common characteristics that can be grouped by (1) geologic and soils variables describing arsenic sources and mobilizers, (2) geochemical variables describing the geochemical environment of the groundwater, and (3) locally specific variables that are unique to each of the three regions studied and not applicable to statewide analysis. Maps of Pennsylvania and the three intrastate regions were produced that illustrate that areas most at risk are those with geology and soils capable of functioning as an arsenic source or mobilizer and geochemical groundwater conditions able to facilitate redox reactions. The models have limitations because they may not characterize areas that have localized controls on arsenic mobility. The probability maps associated with this report are intended for regional-scale use and may not be accurate for use at the field scale or when considering individual wells.

Elevation Control on Vegetation Organization in a Semiarid Ecosystem in Central New Mexico

NASA Astrophysics Data System (ADS)

Nudurupati, S. S.; Istanbulluoglu, E.; Adams, J. M.; Hobley, D. E. J.; Gasparini, N. M.; Tucker, G. E.; Hutton, E. W. H.

2015-12-01

Many semiarid and desert ecosystems are characterized by patchy and dynamic vegetation. Topography plays a commanding role on vegetation patterns. It is observed that plant biomes and biodiversity vary systematically with slope and aspect, from shrublands in low desert elevations, to mixed grass/shrublands in mid elevations, and forests at high elevations. In this study, we investigate the role of elevation dependent climatology on vegetation organization in a semiarid New Mexico catchment where elevation and hillslope aspect play a defining role on plant types. An ecohydrologic cellular automaton model developed within Landlab (component based modeling framework) is used. The model couples local vegetation dynamics (that simulate biomass production based on local soil moisture and potential evapotranspiration) and plant establishment and mortality based on competition for resources and space. This model is driven by elevation dependent rainfall pulses and solar radiation. The domain is initialized with randomly assigned plant types and the model parameters that couple plant response with soil moisture are systematically changed. Climate perturbation experiments are conducted to examine spatial vegetation organization and associated timescales. Model results reproduce elevation and aspect controls on observed vegetation patterns indicating that this model captures necessary and sufficient conditions that explain these observed ecohydrological patterns.

Carbothermic reduction and prereduced charge for producing aluminum-silicon alloys

DOEpatents

Stevenson, D.T.; Troup, R.L.

1985-01-01

Disclosed is a method for the carbothermic reduction of aluminum oxide to form an aluminum alloy including producing silicon carbide by heating a first mix of carbon and silicon oxide in a combustion reactor to an elevated temperature sufficient to produce silicon carbide at an accelerated rate, the heating being provided by an in situ combustion with oxygen gas, and then admixing the silicon carbide with carbon and aluminum oxide to form a second mix and heating the second mix in a second reactor to an elevated metal-forming temperature sufficient to produce aluminum-silicon alloy. The prereduction step includes holding aluminum oxide substantially absent from the combustion reactor. The metal-forming step includes feeding silicon oxide in a preferred ratio with silicon carbide. 1 fig.

Wetland Accretion Rate Model of Ecosystem Resilience (WARMER) and its application to habitat sustainability for endangered species in the San Francisco Estuary

USGS Publications Warehouse

Swanson, Kathleen M.; Drexler, Judith Z.; Schoellhamer, David H.; Thorne, Karen M.; Casazza, Michael L.; Overton, Cory T.; Callaway, John C.; Takekawa, John Y.

2014-01-01

Salt marsh faunas are constrained by specific habitat requirements for marsh elevation relative to sea level and tidal range. As sea level rises, changes in relative elevation of the marsh plain will have differing impacts on the availability of habitat for marsh obligate species. The Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) is a 1-D model of elevation that incorporates both biological and physical processes of vertical marsh accretion. Here, we use WARMER to evaluate changes in marsh surface elevation and the impact of these elevation changes on marsh habitat for specific species of concern. Model results were compared to elevation-based habitat criteria developed for marsh vegetation, the endangered California clapper rail (Rallus longirostris obsoletus), and the endangered salt marsh harvest mouse (Reithrodontomys raviventris) to determine the response of marsh habitat for each species to predicted >1-m sea-level rise by 2100. Feedback between vertical accretion mechanisms and elevation reduced the effect of initial elevation in the modeled scenarios. Elevation decreased nonlinearly with larger changes in elevation during the latter half of the century when the rate of sea-level rise increased. Model scenarios indicated that changes in elevation will degrade habitat quality within salt marshes in the San Francisco Estuary, and degradation will accelerate in the latter half of the century as the rate of sea-level rise accelerates. A sensitivity analysis of the model results showed that inorganic sediment accumulation and the rate of sea-level rise had the greatest influence over salt marsh sustainability.

Logistic regression modeling to assess groundwater vulnerability to contamination in Hawaii, USA.

PubMed

Mair, Alan; El-Kadi, Aly I

2013-10-01

Capture zone analysis combined with a subjective susceptibility index is currently used in Hawaii to assess vulnerability to contamination of drinking water sources derived from groundwater. In this study, we developed an alternative objective approach that combines well capture zones with multiple-variable logistic regression (LR) modeling and applied it to the highly-utilized Pearl Harbor and Honolulu aquifers on the island of Oahu, Hawaii. Input for the LR models utilized explanatory variables based on hydrogeology, land use, and well geometry/location. A suite of 11 target contaminants detected in the region, including elevated nitrate (>1 mg/L), four chlorinated solvents, four agricultural fumigants, and two pesticides, was used to develop the models. We then tested the ability of the new approach to accurately separate groups of wells with low and high vulnerability, and the suitability of nitrate as an indicator of other types of contamination. Our results produced contaminant-specific LR models that accurately identified groups of wells with the lowest/highest reported detections and the lowest/highest nitrate concentrations. Current and former agricultural land uses were identified as significant explanatory variables for eight of the 11 target contaminants, while elevated nitrate was a significant variable for five contaminants. The utility of the combined approach is contingent on the availability of hydrologic and chemical monitoring data for calibrating groundwater and LR models. Application of the approach using a reference site with sufficient data could help identify key variables in areas with similar hydrogeology and land use but limited data. In addition, elevated nitrate may also be a suitable indicator of groundwater contamination in areas with limited data. The objective LR modeling approach developed in this study is flexible enough to address a wide range of contaminants and represents a suitable addition to the current subjective approach. © 2013 Elsevier B.V. All rights reserved.

Advanced composite elevator for Boeing 727 aircraft

NASA Technical Reports Server (NTRS)

1978-01-01

Detail design activities are reported for a program to develop an advanced composites elevator for the Boeing 727 commercial transport. Design activities include discussion and results of the ancillary test programs, sustaining efforts, weight status, manufacturing producibility studies, quality assurance development, and production status.

Understanding Coastal Wetland Vulnerability to Sea-Level Rise Enhanced Inundation Using Real-Time Stage Monitoring, LiDAR, and Monte Carlo Simulation in Everglades National Park

NASA Astrophysics Data System (ADS)

Cooper, H.; Zhang, C.

2017-12-01

Coastal wetlands are one of the most productive ecological systems in the world, providing critical habitat area and valuable ecosystem services such as carbon sequestration. However, due to their location in low lying areas, coastal wetlands are particularly vulnerable to sea-level rise (SLR). Everglades National Park (ENP) encompasses the southern-most portion of the Greater Everglades Ecosystem, and is the largest subtropical wetland in the USA. Water depths have shown to have a significant relationship to vegetation community composition and organization while also playing a crucial role in vegetation health throughout the Everglades. Live plants play a vital role in maintaining soil structure (i.e. elevation), and decreases in vegetation health can cause peat collapse or wetland loss resulting in dramatic habitat, organic soil, and elevation loss posing concerns for Everglades management and restoration. One suspected mechanism for peat collapse is enhanced inundation due to SLR, thus mapping and modeling water depths is a critical component to understanding the potential impacts of future SLR. Previous research in the Everglades focused on a conventional Water Depth Model (WDM) approach where a Digital Elevation Model (DEM) is subtracted from a Water Table Elevation Model (WTEM). In this study, the conventional WDM approach is extended to a more rigorous WDM technique so that the accuracy and precision of the underlying data may be considered. Monte Carlo simulation is used to propagate probability distributions through our SLR depth model using our Random Forest-based LiDAR DEM, Empirical Bayesian Kriging-based WTEMs, uncertainties in vertical datums, soil accretion projections, and regional sea-level rise projections. Water depth maps were produced for the wet and dry seasons in April and October, which successfully revealed the potential spatial and temporal water depth variations due to future SLR. It is concluded that a more rigorous WDM technique helps to increase the integrity of derived products used to support and guide coastal restoration managers and planners under the challenge of rising seas.

Cumulative mtDNA damage and mutations contribute to the progressive loss of RGCs in a rat model of glaucoma.

PubMed

Wu, Ji-Hong; Zhang, Sheng-Hai; Nickerson, John M; Gao, Feng-Juan; Sun, Zhongmou; Chen, Xin-Ya; Zhang, Shu-Jie; Gao, Feng; Chen, Jun-Yi; Luo, Yi; Wang, Yan; Sun, Xing-Huai

2015-02-01

Glaucoma is a chronic neurodegenerative disease characterized by the progressive loss of retinal ganglion cells (RGCs). Mitochondrial DNA (mtDNA) alterations have been documented as a key component of many neurodegenerative disorders. However, whether mtDNA alterations contribute to the progressive loss of RGCs and the mechanism whereby this phenomenon could occur are poorly understood. We investigated mtDNA alterations in RGCs using a rat model of chronic intraocular hypertension and explored the mechanisms underlying progressive RGC loss. We demonstrate that the mtDNA damage and mutations triggered by intraocular pressure (IOP) elevation are initiating, crucial events in a cascade leading to progressive RGC loss. Damage to and mutation of mtDNA, mitochondrial dysfunction, reduced levels of mtDNA repair/replication enzymes, and elevated reactive oxygen species form a positive feedback loop that produces irreversible mtDNA damage and mutation and contributes to progressive RGC loss, which occurs even after a return to normal IOP. Furthermore, we demonstrate that mtDNA damage and mutations increase the vulnerability of RGCs to elevated IOP and glutamate levels, which are among the most common glaucoma insults. This study suggests that therapeutic approaches that target mtDNA maintenance and repair and that promote energy production may prevent the progressive death of RGCs. Copyright © 2014 Elsevier Inc. All rights reserved.

Improving xylitol production at elevated temperature with engineered Kluyveromyces marxianus through over-expressing transporters.

PubMed

Zhang, Jia; Zhang, Biao; Wang, Dongmei; Gao, Xiaolian; Hong, Jiong

2015-01-01

Three transporter genes including Kluyveromyces marxianus aquaglyceroporin gene (KmFPS1), Candida intermedia glucose/xylose facilitator gene (CiGXF1) or glucose/xylose symporter gene (CiGXS1) were over-expressed in K. marxianus YZJ017 to improve xylitol production at elevated temperatures. The xylitol production of YZJ074 that harbored CiGXF1 was improved to 147.62g/L in Erlenmeyer flask at 42°C. In fermenter, 99.29 and 149.60g/L xylitol were produced from 99.55 and 151.91g/L xylose with productivity of 4.14 and 3.40g/L/h respectively at 42°C. Even at 45°C, YZJ074 could produce 101.30g/L xylitol from 101.41g/L xylose with productivity of 2.81g/L/h. Using fed-batch fermentation through repeatedly adding non-sterilized substrate directly, YZJ074 could produce 312.05g/L xylitol which is the highest yield reported to date. The engineered strains YZJ074 which can produce xylitol at elevated temperatures is an excellent foundation for xylitol bioconversion. Copyright © 2014 Elsevier Ltd. All rights reserved.

Boosted food web productivity through ocean acidification collapses under warming.

PubMed

Goldenberg, Silvan U; Nagelkerken, Ivan; Ferreira, Camilo M; Ullah, Hadayet; Connell, Sean D

2017-10-01

Future climate is forecast to drive bottom-up (resource driven) and top-down (consumer driven) change to food web dynamics and community structure. Yet, our predictive understanding of these changes is hampered by an over-reliance on simplified laboratory systems centred on single trophic levels. Using a large mesocosm experiment, we reveal how future ocean acidification and warming modify trophic linkages across a three-level food web: that is, primary (algae), secondary (herbivorous invertebrates) and tertiary (predatory fish) producers. Both elevated CO 2 and elevated temperature boosted primary production. Under elevated CO 2 , the enhanced bottom-up forcing propagated through all trophic levels. Elevated temperature, however, negated the benefits of elevated CO 2 by stalling secondary production. This imbalance caused secondary producer populations to decline as elevated temperature drove predators to consume their prey more rapidly in the face of higher metabolic demand. Our findings demonstrate how anthropogenic CO 2 can function as a resource that boosts productivity throughout food webs, and how warming can reverse this effect by acting as a stressor to trophic interactions. Understanding the shifting balance between the propagation of resource enrichment and its consumption across trophic levels provides a predictive understanding of future dynamics of stability and collapse in food webs and fisheries production. © 2017 John Wiley & Sons Ltd.

Plant growth in elevated CO2 alters mitochondrial number and chloroplast fine structure

PubMed Central

Griffin, Kevin L.; Anderson, O. Roger; Gastrich, Mary D.; Lewis, James D.; Lin, Guanghui; Schuster, William; Seemann, Jeffrey R.; Tissue, David T.; Turnbull, Matthew H.; Whitehead, David

2001-01-01

With increasing interest in the effects of elevated atmospheric CO2 on plant growth and the global carbon balance, there is a need for greater understanding of how plants respond to variations in atmospheric partial pressure of CO2. Our research shows that elevated CO2 produces significant fine structural changes in major cellular organelles that appear to be an important component of the metabolic responses of plants to this global change. Nine species (representing seven plant families) in several experimental facilities with different CO2-dosing technologies were examined. Growth in elevated CO2 increased numbers of mitochondria per unit cell area by 1.3–2.4 times the number in control plants grown in lower CO2 and produced a statistically significant increase in the amount of chloroplast stroma (nonappressed) thylakoid membranes compared with those in lower CO2 treatments. There was no observable change in size of the mitochondria. However, in contrast to the CO2 effect on mitochondrial number, elevated CO2 promoted a decrease in the rate of mass-based dark respiration. These changes may reflect a major shift in plant metabolism and energy balance that may help to explain enhanced plant productivity in response to elevated atmospheric CO2 concentrations. PMID:11226263

Status report for the 3D Elevation Program, 2013-2014

USGS Publications Warehouse

Lukas, Vicki; Eldridge, Diane F.; Jason, Allyson L.; Saghy, David L.; Steigerwald, Pamela R.; Stoker, Jason M.; Sugarbaker, Larry J.; Thunen, Diana R.

2015-09-25

The 3D Elevation Program (3DEP) goal is to acquire, manage, and distribute enhanced three-dimensional elevation data for the Nation and U.S. territories by 2023. This status report covers implementation activities during 2013–2014 to include meeting funding objectives, developing a management structure, modernizing systems, and collecting and producing initial 3DEP data and products. The Nation will not have complete coverage of 3DEP quality data until 2023 assuming that sufficient funding is available. In spite of the overall condition of government budgets, the 3DEP initiative has gained widespread support and had incremental budget success to include supplemental funding resulting from natural disasters. The 3DEP Executive Forum and a wide range of professional organizations are actively working to maintain support for the program. The systems that have been developed to support increasing acquisition and processing levels are largely in place. The first 3DEP quality datasets were released to the public in late 2014. In addition, light detection and ranging (lidar), interferometric synthetic aperture radar (ifsar), and digital elevation models (DEMs) acquired before 2014 are all supported within the new infrastructure and available for download. Research is ongoing to expand the suite of products and services, and to increase overall throughput and data management efficiency. Emerging technologies may result in lower acquisition costs in the future. Elevation data acquired by 3DEP partnerships will be available through The National Map representing one of the largest and most comprehensive databases publicly available for the United States. 

I/O efficient algorithms and applications in geographic information systems

NASA Astrophysics Data System (ADS)

Danner, Andrew

Modern remote sensing methods such a laser altimetry (lidar) and Interferometric Synthetic Aperture Radar (IfSAR) produce georeferenced elevation data at unprecedented rates. Many Geographic Information System (GIS) algorithms designed for terrain modelling applications cannot process these massive data sets. The primary problem is that these data sets are too large to fit in the main internal memory of modern computers and must therefore reside on larger, but considerably slower disks. In these applications, the transfer of data between disk and main memory, or I/O, becomes the primary bottleneck. Working in a theoretical model that more accurately represents this two level memory hierarchy, we can develop algorithms that are I/O-efficient and reduce the amount of disk I/O needed to solve a problem. In this thesis we aim to modernize GIS algorithms and develop a number of I/O-efficient algorithms for processing geographic data derived from massive elevation data sets. For each application, we convert a geographic question to an algorithmic question, develop an I/O-efficient algorithm that is theoretically efficient, implement our approach and verify its performance using real-world data. The applications we consider include constructing a gridded digital elevation model (DEM) from an irregularly spaced point cloud, removing topological noise from a DEM, modeling surface water flow over a terrain, extracting river networks and watershed hierarchies from the terrain, and locating polygons containing query points in a planar subdivision. We initially developed solutions to each of these applications individually. However, we also show how to combine individual solutions to form a scalable geo-processing pipeline that seamlessly solves a sequence of sub-problems with little or no manual intervention. We present experimental results that demonstrate orders of magnitude improvement over previously known algorithms.

Past and Future Climate Change Impacts on Mountain Forests on the Olympic Peninsula (Washington, USA)

NASA Astrophysics Data System (ADS)

Schwörer, C.; Fisher, D. M.; Gavin, D. G.; Temperli, C.; Bartlein, P. J.

2015-12-01

Mountain forest composition and distribution is strongly affected by temperature and is expected to shift to higher elevations with climate change. However, warmer winters will also lead to an upward shift of the snowline and a decrease in snowpack at lower and intermediate elevations. In the mountain ranges of Western North America, snowpack plays an important role in providing additional moisture during the dry summer months. It is therefore unclear if the projected climate change will lead to a rise of subalpine forest due to a longer growing season or a contraction due to drought stress. Since forest succession processes take place over decades and centuries we use LandClim, a dynamic vegetation model, to assess the impact of climate change on mountain forests on the Olympic Peninsula (Washington, USA). As a reality check we first simulate vegetation dynamics since the last Ice Age and compare model output with paleobotanical data from five natural archives that span the topographic and climatic gradients on the Peninsula. LandClim produces realistic present-day species compositions with respect to elevation and precipitation gradients. Moreover, the simulations of forest dynamics for the last 16,000 years generally agree with the pollen and macrofossil data. We then simulated mountain forests under future climate projections. As a result, our model indicates drastic changes in species composition with a replacement of mountain hemlock (Tsuga mertensiana) by more drought-resistant species such as subalpine fir (Abies lasiocarpa). On the drier, eastern side of the Peninsula, the model even suggests a lowering of timberline due to insufficient moisture availability in shallow alpine soils. Our results have important implications for ecosystem managers and stress the urgency of climate change mitigation.

Generation of High Resolution Water Vapour Fields from GPS Observations and Integration With ECMWF and MODIS

NASA Astrophysics Data System (ADS)

Yu, C.; Li, Z.; Penna, N. T.

2016-12-01

Precipitable water vapour (PWV) can be routinely retrieved from ground-based GPS arrays in all-weather conditions and also in real-time. But to provide dense spatial coverage maps, for example for calibrating SAR images, for correcting atmospheric effects in Network RTK GPS positioning and which may be used for numerical weather prediction, the pointwise GPS PWV measurements must be interpolated. Several previous interpolation studies have addressed the importance of the elevation dependency of water vapour, but it is often a challenge to separate elevation-dependent tropospheric delays from turbulent components. We present a tropospheric turbulence iterative decomposition model that decouples the total PWV into (i) a stratified component highly correlated with topography which therefore delineates the vertical troposphere profile, and (ii) a turbulent component resulting from disturbance processes (e.g., severe weather) in the troposphere which trigger uncertain patterns in space and time. We will demonstrate that the iterative decoupled interpolation model generates improved dense tropospheric water vapour fields compared with elevation dependent models, with similar accuracies obtained over both flat and mountainous terrain, as well as for both inland and coastal areas. We will also show that our GPS-based model may be enhanced with ECMWF zenith tropospheric delay and MODIS PWV, producing multi-data sources high temporal-spatial resolution PWV fields. These fields were applied to Sentinel-1 SAR interferograms over the Los Angeles region, for which a maximum noise reduction due to atmosphere artifacts reached 85%. The results reveal that the turbulent troposphere noise, especially those in a SAR image, often occupy more than 50% of the total zenith tropospheric delay and exert systematic, rather than random patterns.

Updating flood maps efficiently using existing hydraulic models, very-high-accuracy elevation data, and a geographic information system; a pilot study on the Nisqually River, Washington

USGS Publications Warehouse

Jones, Joseph L.; Haluska, Tana L.; Kresch, David L.

2001-01-01

A method of updating flood inundation maps at a fraction of the expense of using traditional methods was piloted in Washington State as part of the U.S. Geological Survey Urban Geologic and Hydrologic Hazards Initiative. Large savings in expense may be achieved by building upon previous Flood Insurance Studies and automating the process of flood delineation with a Geographic Information System (GIS); increases in accuracy and detail result from the use of very-high-accuracy elevation data and automated delineation; and the resulting digital data sets contain valuable ancillary information such as flood depth, as well as greatly facilitating map storage and utility. The method consists of creating stage-discharge relations from the archived output of the existing hydraulic model, using these relations to create updated flood stages for recalculated flood discharges, and using a GIS to automate the map generation process. Many of the effective flood maps were created in the late 1970?s and early 1980?s, and suffer from a number of well recognized deficiencies such as out-of-date or inaccurate estimates of discharges for selected recurrence intervals, changes in basin characteristics, and relatively low quality elevation data used for flood delineation. FEMA estimates that 45 percent of effective maps are over 10 years old (FEMA, 1997). Consequently, Congress has mandated the updating and periodic review of existing maps, which have cost the Nation almost 3 billion (1997) dollars. The need to update maps and the cost of doing so were the primary motivations for piloting a more cost-effective and efficient updating method. New technologies such as Geographic Information Systems and LIDAR (Light Detection and Ranging) elevation mapping are key to improving the efficiency of flood map updating, but they also improve the accuracy, detail, and usefulness of the resulting digital flood maps. GISs produce digital maps without manual estimation of inundated areas between cross sections, and can generate working maps across a broad range of scales, for any selected area, and overlayed with easily updated cultural features. Local governments are aggressively collecting very-high-accuracy elevation data for numerous reasons; this not only lowers the cost and increases accuracy of flood maps, but also inherently boosts the level of community involvement in the mapping process. These elevation data are also ideal for hydraulic modeling, should an existing model be judged inadequate.

Topographic Structure from Motion

NASA Astrophysics Data System (ADS)

Fonstad, M. A.; Dietrich, J. T.; Courville, B. C.; Jensen, J.; Carbonneau, P.

2011-12-01

The production of high-resolution topographic datasets is of increasing concern and application throughout the geomorphic sciences, and river science is no exception. Consequently, a wide range of topographic measurement methods have evolved. Despite the range of available methods, the production of high resolution, high quality digital elevation models (DEMs) generally requires a significant investment in personnel time, hardware and/or software. However, image-based methods such as digital photogrammetry have steadily been decreasing in costs. Initially developed for the purpose of rapid, inexpensive and easy three dimensional surveys of buildings or small objects, the "structure from motion" photogrammetric approach (SfM) is a purely image based method which could deliver a step-change if transferred to river remote sensing, and requires very little training and is extremely inexpensive. Using the online SfM program Microsoft Photosynth, we have created high-resolution digital elevation models (DEM) of rivers from ordinary photographs produced from a multi-step workflow that takes advantage of free and open source software. This process reconstructs real world scenes from SfM algorithms based on the derived positions of the photographs in three-dimensional space. One of the products of the SfM process is a three-dimensional point cloud of features present in the input photographs. This point cloud can be georeferenced from a small number of ground control points collected via GPS in the field. The georeferenced point cloud can then be used to create a variety of digital elevation model products. Among several study sites, we examine the applicability of SfM in the Pedernales River in Texas (USA), where several hundred images taken from a hand-held helikite are used to produce DEMs of the fluvial topographic environment. This test shows that SfM and low-altitude platforms can produce point clouds with point densities considerably better than airborne LiDAR, with horizontal and vertical precision in the centimeter range, and with very low capital and labor costs and low expertise levels. Advanced structure from motion software (such as Bundler and OpenSynther) are currently under development and should increase the density of topographic points rivaling those of terrestrial laser scanning when using images shot from low altitude platforms such as helikites, poles, remote-controlled aircraft and rotocraft, and low-flying manned aircraft. Clearly, the development of this set of inexpensive and low-required-expertise tools has the potential to fundamentally shift the production of digital fluvial topography from a capital-intensive enterprise of a low number of researchers to a low-cost exercise of many river researchers.

Impacts of snow cover fraction data assimilation on modeled energy and moisture budgets

NASA Astrophysics Data System (ADS)

Arsenault, Kristi R.; Houser, Paul R.; De Lannoy, Gabriëlle J. M.; Dirmeyer, Paul A.

2013-07-01

Two data assimilation (DA) methods, a simple rule-based direct insertion (DI) approach and a one-dimensional ensemble Kalman filter (EnKF) method, are evaluated by assimilating snow cover fraction observations into the Community Land surface Model. The ensemble perturbation needed for the EnKF resulted in negative snowpack biases. Therefore, a correction is made to the ensemble bias using an approach that constrains the ensemble forecasts with a single unperturbed deterministic LSM run. This is shown to improve the final snow state analyses. The EnKF method produces slightly better results in higher elevation locations, whereas results indicate that the DI method has a performance advantage in lower elevation regions. In addition, the two DA methods are evaluated in terms of their overall impacts on the other land surface state variables (e.g., soil moisture) and fluxes (e.g., latent heat flux). The EnKF method is shown to have less impact overall than the DI method and causes less distortion of the hydrological budget. However, the land surface model adjusts more slowly to the smaller EnKF increments, which leads to smaller but slightly more persistent moisture budget errors than found with the DI updates. The DI method can remove almost instantly much of the modeled snowpack, but this also allows the model system to quickly revert to hydrological balance for nonsnowpack conditions.

Lithospheric buoyancy and continental intraplate stresses

USGS Publications Warehouse

Zoback, M.L.; Mooney, W.D.

2003-01-01

Lithospheric buoyancy, the product of lithospheric density and thickness, is an important physical property that influences both the long-term stability of continents and their state of stress. We have determined lithospheric buoyancy by applying the simple isostatic model of Lachenbruch and Morgan (1990). We determine the crustal portion of lithospheric buoyancy using the USGS global database of more than 1700 crustal structure determinations (Mooney et al., 2002), which demonstrates that a simple relationship between crustal thickness and surface elevation does not exist. In fact, major regions of the crust at or near sea level (0-200 m elevation) have crustal thicknesses that vary between 25 and 55 km. Predicted elevations due to the crustal component of buoyancy in the model exceed observed elevations in nearly all cases (97% of the data), consistent with the existence of a cool lithospheric mantle lid that is denser than the asthenosphere on which it floats. The difference between the observed and predicted crustal elevation is assumed to be equal to the decrease in elevation produced by the negative buoyancy of the mantle lid. Mantle lid thickness was first estimated from the mantle buoyancy and a mean lid density computed using a basal crust temperature determined from extrapolation of surface heat flow, assuming a linear thermal gradient in the mantle lid. The resulting values of total lithosphere thickness are in good agreement with thicknesses estimated from seismic data, except beneath cratonic regions where they are only 40-60% of the typical estimates (200-350 km) derived from seismic data. This inconsistency is compatible with petrologic data and tomography and geoid analyses that have suggested that cratonic mantle lids are ??? 1% less dense than mantle lids elsewhere. By lowering the thermally determined mean mantle lid density in cratons by 1%, our model reproduces the observed 200-350+ km cratonic lithospheric thickness. We then computed gravitational potential energy by taking a vertical integral over the computed lithosphere density. Our computed values suggest that the thick roots beneath cratons lead to strong negative potential energy differences relative to surrounding regions, and hence exert compressive stresses superimposed on the intraplate stresses derived from plate boundary forces. Forces related to this lithosphere structure thus may explain the dominance of reverse-faulting earthquakes in cratons. Areas of high elevation and a thin mantle lid (e.g., western U.S. Basin and Range, East African rift, and Baikal rift) are predicted to be in extension, consistent with the observed stress regime in these areas.

TouchTerrain: A simple web-tool for creating 3D-printable topographic models

NASA Astrophysics Data System (ADS)

Hasiuk, Franciszek J.; Harding, Chris; Renner, Alex Raymond; Winer, Eliot

2017-12-01

An open-source web-application, TouchTerrain, was developed to simplify the production of 3D-printable terrain models. Direct Digital Manufacturing (DDM) using 3D Printers can change how geoscientists, students, and stakeholders interact with 3D data, with the potential to improve geoscience communication and environmental literacy. No other manufacturing technology can convert digital data into tangible objects quickly at relatively low cost; however, the expertise necessary to produce a 3D-printed terrain model can be a substantial burden: knowledge of geographical information systems, computer aided design (CAD) software, and 3D printers may all be required. Furthermore, printing models larger than the build volume of a 3D printer can pose further technical hurdles. The TouchTerrain web-application simplifies DDM for elevation data by generating digital 3D models customized for a specific 3D printer's capabilities. The only required user input is the selection of a region-of-interest using the provided web-application with a Google Maps-style interface. Publically available digital elevation data is processed via the Google Earth Engine API. To allow the manufacture of 3D terrain models larger than a 3D printer's build volume the selected area can be split into multiple tiles without third-party software. This application significantly reduces the time and effort required for a non-expert like an educator to obtain 3D terrain models for use in class. The web application is deployed at http://touchterrain.geol.iastate.edu/.

Addition polymers from 1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene and Bis-dienes. 2: Evidence for thermal dehydration occurring in the cure process

NASA Technical Reports Server (NTRS)

Meador, Mary Ann B.; Olshavsky, Michael A.; Meador, Michael A.; Ahn, Myong-Ku

1988-01-01

Diels-Alder cycloaddition copolymers from 1,4,5,8-tetrahydro-1,4;5,8-diepoxyanthracene and anthracene end-capped polyimide oligomers appear, by thermogravimetric analysis (TGA), to undergo dehydration at elevated temperatures. This would produce thermally stable pentiptycene units along the polymer backbone, and render the polymers incapable of unzipping through a retro-Diels-Alder pathway. High resolution solid 13C nuclear magnetic resonance (NMR) of one formulation of the polymer system before and after heating at elevated temperatures, shows this to indeed be the case. NMR spectra of solid samples of the polymer before and after heating correlated well with those of the parent pentiptycene model compound before and after acid-catalyzed dehydration. Isothermal gravimetric analyses and viscosities of the polymer before and after heat treatment support dehydration as a mechanism for the cure reaction.

Structure-property relationships in oxide-dispersed iron-beryllia alloys

NASA Technical Reports Server (NTRS)

Wolf, S.; Grant, N. J.

1977-01-01

Two BeO dispersed iron alloys containing about 2.5 and 5.5 v/o dispersoid were produced by attritting, internally oxidizing, and extruding dilute, prealloyed Fe-Be powders. As-extruded alloys were given various thermomechanical treatments involving room temperature swaging and annealing above and below the allotropic transformation temperature. The elevated temperature rupture strengths were measured and correlated with changes in structure; strengthening trends were examined in the light of proposed models for such strengthening. The results obtained showed that the elevated temperature strength was determined by the oxide interparticle spacing (IPS) in recrystallized material and IPS as well as prior deformation in swaged specimens. In fact, a parametric correlation was found between rupture strength values in the longitudinal direction with prestrain during swaging. The overall pattern in strength and microstructural observations were more consistent with a strength-stored energy (substructure) dependence than a strength-grain shape (grain aspect ratio) relation.

Continental and oceanic magnetic anomalies: Enhancement through GRM

NASA Technical Reports Server (NTRS)

Vonfrese, R. R. B.; Hinze, W. J.

1985-01-01

In contrast to the POGO and MAGSAT satellites, the Geopotential Research Mission (GRM) satellite system will orbit at a minimum elevation to provide significantly better resolved lithospheric magnetic anomalies for more detailed and improved geologic analysis. In addition, GRM will measure corresponding gravity anomalies to enhance our understanding of the gravity field for vast regions of the Earth which are largely inaccessible to more conventional surface mapping. Crustal studies will greatly benefit from the dual data sets as modeling has shown that lithospheric sources of long wavelength magnetic anomalies frequently involve density variations which may produce detectable gravity anomalies at satellite elevations. Furthermore, GRM will provide an important replication of lithospheric magnetic anomalies as an aid to identifying and extracting these anomalies from satellite magnetic measurements. The potential benefits to the study of the origin and characterization of the continents and oceans, that may result from the increased GRM resolution are examined.

Novel electrical energy storage system based on reversible solid oxide cells: System design and operating conditions

NASA Astrophysics Data System (ADS)

Wendel, C. H.; Kazempoor, P.; Braun, R. J.

2015-02-01

Electrical energy storage (EES) is an important component of the future electric grid. Given that no other widely available technology meets all the EES requirements, reversible (or regenerative) solid oxide cells (ReSOCs) working in both fuel cell (power producing) and electrolysis (fuel producing) modes are envisioned as a technology capable of providing highly efficient and cost-effective EES. However, there are still many challenges and questions from cell materials development to system level operation of ReSOCs that should be addressed before widespread application. This paper presents a novel system based on ReSOCs that employ a thermal management strategy of promoting exothermic methanation within the ReSOC cell-stack to provide thermal energy for the endothermic steam/CO2 electrolysis reactions during charging mode (fuel producing). This approach also serves to enhance the energy density of the stored gases. Modeling and parametric analysis of an energy storage concept is performed using a physically based ReSOC stack model coupled with thermodynamic system component models. Results indicate that roundtrip efficiencies greater than 70% can be achieved at intermediate stack temperature (680 °C) and elevated stack pressure (20 bar). The optimal operating condition arises from a tradeoff between stack efficiency and auxiliary power requirements from balance of plant hardware.

Dynamic modeling and experiments on the coupled vibrations of building and elevator ropes

NASA Astrophysics Data System (ADS)

Yang, Dong-Ho; Kim, Ki-Young; Kwak, Moon K.; Lee, Seungjun

2017-03-01

This study is concerned with the theoretical modelling and experimental verification of the coupled vibrations of building and elevator ropes. The elevator ropes consist of a main rope which supports the cage and the compensation rope which is connected to the compensation sheave. The elevator rope is a flexible wire with a low damping, so it is prone to vibrations. In the case of a high-rise building, the rope length also increases significantly, so that the fundamental frequency of the elevator rope approaches the fundamental frequency of the building thus increasing the possibility of resonance. In this study, the dynamic model for the analysis of coupled vibrations of building and elevator ropes was derived by using Hamilton's principle, where the cage motion was also considered. An experimental testbed was built to validate the proposed dynamic model. It was found that the experimental results are in good agreement with the theoretical predictions thus validating the proposed dynamic model. The proposed model was then used to predict the vibrations of real building and elevator ropes.

Repeated, but Not Acute, Stress Suppresses Inflammatory Plasma Extravasation

NASA Astrophysics Data System (ADS)

Strausbaugh, Holly J.; Dallman, Mary F.; Levine, Jon D.

1999-12-01

Clinical findings suggest that inflammatory disease symptoms are aggravated by ongoing, repeated stress, but not by acute stress. We hypothesized that, compared with single acute stressors, chronic repeated stress may engage different physiological mechanisms that exert qualitatively different effects on the inflammatory response. Because inhibition of plasma extravasation, a critical component of the inflammatory response, has been associated with increased disease severity in experimental arthritis, we tested for a potential repeated stress-induced inhibition of plasma extravasation. Repeated, but not single, exposures to restraint stress produced a profound inhibition of bradykinin-induced synovial plasma extravasation in the rat. Experiments examining the mechanism of inhibition showed that the effect of repeated stress was blocked by adrenalectomy, but not by adrenal medullae denervation, suggesting that the adrenal cortex mediates this effect. Consistent with known effects of stress and with mediation by the adrenal cortex, restraint stress evoked repeated transient elevations of plasma corticosterone levels. This elevated corticosterone was necessary and sufficient to produce inhibition of plasma extravasation because the stress-induced inhibition was blocked by preventing corticosterone synthesis and, conversely, induction of repeated transient elevations in plasma corticosterone levels mimicked the effects of repeated stress. These data suggest that repetition of a mild stressor can induce changes in the physiological state of the animal that enable a previously innocuous stressor to inhibit the inflammatory response. These findings provide a potential explanation for the clinical association between repeated stress and aggravation of inflammatory disease symptoms and provide a model for study of the biological mechanisms underlying the stress-induced aggravation of chronic inflammatory diseases.

Applications of UAS-SfM for coastal vulnerability assessment: Geomorphic feature extraction and land cover classification from fine-scale elevation and imagery data

NASA Astrophysics Data System (ADS)

Sturdivant, E. J.; Lentz, E. E.; Thieler, E. R.; Remsen, D.; Miner, S.

2016-12-01

Characterizing the vulnerability of coastal systems to storm events, chronic change and sea-level rise can be improved with high-resolution data that capture timely snapshots of biogeomorphology. Imagery acquired with unmanned aerial systems (UAS) coupled with structure from motion (SfM) photogrammetry can produce high-resolution topographic and visual reflectance datasets that rival or exceed lidar and orthoimagery. Here we compare SfM-derived data to lidar and visual imagery for their utility in a) geomorphic feature extraction and b) land cover classification for coastal habitat assessment. At a beach and wetland site on Cape Cod, Massachusetts, we used UAS to capture photographs over a 15-hectare coastal area with a resulting pixel resolution of 2.5 cm. We used standard SfM processing in Agisoft PhotoScan to produce an elevation point cloud, an orthomosaic, and a digital elevation model (DEM). The SfM-derived products have a horizontal uncertainty of +/- 2.8 cm. Using the point cloud in an extraction routine developed for lidar data, we determined the position of shorelines, dune crests, and dune toes. We used the output imagery and DEM to map land cover with a pixel-based supervised classification. The dense and highly precise SfM point cloud enabled extraction of geomorphic features with greater detail than with lidar. The feature positions are reported with near-continuous coverage and sub-meter accuracy. The orthomosaic image produced with SfM provides visual reflectance with higher resolution than those available from aerial flight surveys, which enables visual identification of small features and thus aids the training and validation of the automated classification. We find that the high-resolution and correspondingly high density of UAS data requires some simple modifications to existing measurement techniques and processing workflows, and that the types of data and the quality provided is equivalent to, and in some cases surpasses, that of data collected using other methods.

Effects of elevated atmospheric CO2 on competition between the mosquitoes Aedes albopictus and Ae. triseriatus via changes in litter quality and production.

PubMed

Smith, C; Baldwin, A H; Sullivan, J; Leisnham, P T

2013-05-01

Elevated atmospheric CO2 can alter aquatic communities via changes in allochthonous litter inputs. We tested effects of atmospheric CO2 on the invasive Aedes albopictus (Skuse) and native Aedes triseriatus (Say) (Diptera: Culicidae) via changes in competition for microbial food or resource inhibition/toxicity. Quercus alba L. litter was produced under elevated (879 ppm) and ambient (388 ppm) atmospheric CO2. Saplings grown at elevated CO2 produced greater litter biomass, which decayed faster and leached more tannins than saplings at ambient CO2. Competition was tested by raising larvae in different species and density combinations provisioned with elevated- or ambient-CO2 litter. Species-specific performance to water conditions was tested by providing single-species larval cohorts with increasing amounts of elevated- or ambient-CO2 litter, or increasing concentrations of tannic acid. Larval densities affected some fitness parameters of Ae. albopictus and Ae. triseriatus, but elevated-CO2 litter did not modify the effects of competition on population growth rates or any fitness parameters. Population growth rates and survival of each species generally were affected negatively by increasing amounts of both elevated- and ambient-CO2 litter from 0.252 to 2.016 g/liter, and tannic acid concentrations above 100 mg/liter were entirely lethal to both species. Aedes albopictus had consistently higher population growth rates than Ae. triseriatus. These results suggest that changes to litter production and chemistry from elevated CO2 are unlikely to affect the competitive outcome between Ae. albopictus and Ae. triseriatus, but that moderate increases in litter production increase population growth rates of both species until a threshold is exceeded that results in resource inhibition and toxicity.

Preliminary Development of a Unified Viscoplastic Constitutive Model for Alloy 617 with Special Reference to Long Term Creep Behavior

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sham, Sam; Walker, Kevin P.

The expected service life of the Next Generation Nuclear Plant is 60 years. Structural analyses of the Intermediate Heat Exchanger (IHX) will require the development of unified viscoplastic constitutive models that address the material behavior of Alloy 617, a construction material of choice, over a wide range of strain rates. Many unified constitutive models employ a yield stress state variable which is used to account for cyclic hardening and softening of the material. For low stress values below the yield stress state variable these constitutive models predict that no inelastic deformation takes place which is contrary to experimental results. Themore » ability to model creep deformation at low stresses for the IHX application is very important as the IHX operational stresses are restricted to very small values due to the low creep strengths at elevated temperatures and long design lifetime. This paper presents some preliminary work in modeling the unified viscoplastic constitutive behavior of Alloy 617 which accounts for the long term, low stress, creep behavior and the hysteretic behavior of the material at elevated temperatures. The preliminary model is presented in one-dimensional form for ease of understanding, but the intent of the present work is to produce a three-dimensional model suitable for inclusion in the user subroutines UMAT and USERPL of the ABAQUS and ANSYS nonlinear finite element codes. Further experiments and constitutive modeling efforts are planned to model the material behavior of Alloy 617 in more detail.« less

Effects of uncertain topographic input data on two-dimensional flow modeling in a gravel-bed river

USGS Publications Warehouse

Legleiter, C.J.; Kyriakidis, P.C.; McDonald, R.R.; Nelson, J.M.

2011-01-01

Many applications in river research and management rely upon two-dimensional (2D) numerical models to characterize flow fields, assess habitat conditions, and evaluate channel stability. Predictions from such models are potentially highly uncertain due to the uncertainty associated with the topographic data provided as input. This study used a spatial stochastic simulation strategy to examine the effects of topographic uncertainty on flow modeling. Many, equally likely bed elevation realizations for a simple meander bend were generated and propagated through a typical 2D model to produce distributions of water-surface elevation, depth, velocity, and boundary shear stress at each node of the model's computational grid. Ensemble summary statistics were used to characterize the uncertainty associated with these predictions and to examine the spatial structure of this uncertainty in relation to channel morphology. Simulations conditioned to different data configurations indicated that model predictions became increasingly uncertain as the spacing between surveyed cross sections increased. Model sensitivity to topographic uncertainty was greater for base flow conditions than for a higher, subbankfull flow (75% of bankfull discharge). The degree of sensitivity also varied spatially throughout the bend, with the greatest uncertainty occurring over the point bar where the flow field was influenced by topographic steering effects. Uncertain topography can therefore introduce significant uncertainty to analyses of habitat suitability and bed mobility based on flow model output. In the presence of such uncertainty, the results of these studies are most appropriately represented in probabilistic terms using distributions of model predictions derived from a series of topographic realizations. Copyright 2011 by the American Geophysical Union.

Process development of two high strength tantalum base alloys (ASTAR-1211C and ASTAR-1511C)

NASA Technical Reports Server (NTRS)

Ammon, R. L.

1974-01-01

Two tantalum base alloys, Ta-12W-1.0Re-0.7Hf-0.025C(ASTAR-1211C) and Ta-15W-1.0Re-0.7Hf-0.025C(ASTAR-1511C), were cast as 12.5 cm (5 inch) diameter ingots and processed to swaged rod, sheet, forged plate, and tubing. Swaged rod was evaluated with respect to low temperature ductility, elevated temperature tensile properties, and elevated temperature creep behavior. A standard swaging process and final annealing schedule were determined. Elevated temperature tensile properties, low temperature impact properties, low temperature DBTT behavior, and extended elevated temperature creep properties were determined. A process for producing ASTAR-1211C and ASTAR-1511C sheet were developed. The DBTT properties of GTA and EB weld sheet given post-weld anneal and thermal aging treatments were determined using bend and tensile specimens. High and low temperature mechanical properties of forging ASTAR-1211C and ASTAR-1511C plate were determined as well as elevated temperature creep properties. Attempts to produce ASTAR-1211C tubing were partially successful while attempts to make ASTAR-1511C tubing were completely unsuccessful.

Impacts of Elevated Atmospheric CO 2 and O 3 on Paper Birch ( Betula papyrifera ): Reproductive Fitness

DOE PAGES

Darbah, Joseph N. T.; Kubiske, Mark E.; Nelson, Neil; ...

2007-01-01

Atmospheric CO 2 and tropospheric O 3 are rising in many regions of the world. Little is known about how these two commonly co-occurring gases will affect reproductive fitness of important forest tree species. Here, we report on the long-term effects of CO 3 and O 3 for paper birch seedlings exposed for nearly their entire life history at the Aspen FACE (Free Air Carbon Dioxide Enrichment) site in Rhinelander, WI. Elevated CO 2 increased both male and female flower production, while elevated O 3 increased female flower production compared to trees in control rings. Interestingly, very little flowering hasmore » yet occurred in combined treatment. Elevated CO 2 had significant positive effect on birch catkin size, weight, and germination success rate (elevated CO 2 increased germination rate of birch by 110% compared to ambient CO 2 concentrations, decreased seedling mortality by 73%, increased seed weight by 17%, increased root length by 59%, and root-to-shoot ratio was significantly decreased, all at 3 weeks after germination), while the opposite was true of elevated O 3 (elevated O 3 decreased the germination rate of birch by 62%, decreased seed weight by 25%, and increased root length by 15%). Under elevated CO 2 , plant dry mass increased by 9 and 78% at the end of 3 and 14 weeks, respectively. Also, the root and shoot lengths, as well as the biomass of the seedlings, were increased for seeds produced under elevated CO 2 , while the reverse was true for seedlings from seeds produced under the elevated O 3 . Similar trends in treatment differences were observed in seed characteristics, germination, and seedling development for seeds collected in both 2004 and 2005. Our results suggest that elevated CO 2 and O 3 can dramatically affect flowering, seed production, and seed quality of paper birch, affecting reproductive fitness of this species.« less

Impacts of elevated atmospheric CO2 and O3 on paper birch (Betula papyrifera): reproductive fitness.

PubMed

Darbah, Joseph N T; Kubiske, Mark E; Nelson, Neil; Oksanen, Elina; Vaapavuori, Elina; Karnosky, David F

2007-03-21

Atmospheric CO2 and tropospheric O3 are rising in many regions of the world. Little is known about how these two commonly co-occurring gases will affect reproductive fitness of important forest tree species. Here, we report on the long-term effects of CO2 and O3 for paper birch seedlings exposed for nearly their entire life history at the Aspen FACE (Free Air Carbon Dioxide Enrichment) site in Rhinelander, WI. Elevated CO2 increased both male and female flower production, while elevated O3 increased female flower production compared to trees in control rings. Interestingly, very little flowering has yet occurred in combined treatment. Elevated CO2 had significant positive effect on birch catkin size, weight, and germination success rate (elevated CO2 increased germination rate of birch by 110% compared to ambient CO2 concentrations, decreased seedling mortality by 73%, increased seed weight by 17%, increased root length by 59%, and root-to-shoot ratio was significantly decreased, all at 3 weeks after germination), while the opposite was true of elevated O3 (elevated O3 decreased the germination rate of birch by 62%, decreased seed weight by 25%, and increased root length by 15%). Under elevated CO2, plant dry mass increased by 9 and 78% at the end of 3 and 14 weeks, respectively. Also, the root and shoot lengths, as well as the biomass of the seedlings, were increased for seeds produced under elevated CO2, while the reverse was true for seedlings from seeds produced under the elevated O3. Similar trends in treatment differences were observed in seed characteristics, germination, and seedling development for seeds collected in both 2004 and 2005. Our results suggest that elevated CO2 and O3 can dramatically affect flowering, seed production, and seed quality of paper birch, affecting reproductive fitness of this species.

Examination of elevation dependency in observed and projected temperature change in the Upper Indus Basin and Western Himalaya

NASA Astrophysics Data System (ADS)

Fowler, H. J.; Forsythe, N. D.; Blenkinsop, S.; Archer, D.; Hardy, A.; Janes, T.; Jones, R. G.; Holderness, T.

2013-12-01

We present results of two distinct, complementary analyses to assess evidence of elevation dependency in temperature change in the UIB (Karakoram, Eastern Hindu Kush) and wider WH. The first analysis component examines historical remotely-sensed land surface temperature (LST) from the second and third generation of the Advanced Very High Resolution Radiometer (AVHRR/2, AVHRR/3) instrument flown on NOAA satellite platforms since the mid-1980s through present day. The high spatial resolution (<4km) from AVHRR instrument enables precise consideration of the relationship between estimated LST and surface topography. The LST data product was developed as part of initiative to produce continuous time-series for key remotely sensed spatial products (LST, snow covered area, cloud cover, NDVI) extending as far back into the historical record as feasible. Context for the AVHRR LST data product is provided by results of bias assessment and validation procedures against both available local observations, both manned and automatic weather stations. Local observations provide meaningful validation and bias assessment of the vertical gradients found in the AVHRR LST as the elevation range from the lowest manned meteorological station (at 1460m asl) to the highest automatic weather station (4733m asl) covers much of the key range yielding runoff from seasonal snowmelt. Furthermore the common available record period of these stations (1995 to 2007) enables assessment not only of the AVHRR LST but also performance comparisons with the more recent MODIS LST data product. A range of spatial aggregations (from minor tributary catchments to primary basin headwaters) is performed to assess regional homogeneity and identify potential latitudinal or longitudinal gradients in elevation dependency. The second analysis component investigates elevation dependency, including its uncertainty, in projected temperature change trajectories in the downscaling of a seventeen member Global Climate Model (GCM) perturbed physics ensemble (PPE) of transient (130-year) simulations using a moderate resolution (25km) regional climate model (RCM). The GCM ensemble is the17-member QUMP (Quantifying Uncertainty in Model Projections) ensemble and the downscaling is done using HadRM3P, part of the PRECIS regional climate modelling system. Both the RCM and GCMs are models developed the UK Met Office Hadley Centre and are based on the HadCM3 GCM. Use of the multi-member PPE enables quantification of uncertainty in projected temperature change while the spatial resolution of RCM improves insight into the role of elevation in projected rates of change. Furthermore comparison with the results of the remote sensing analysis component - considered to provide an 'observed climatology' - permits evaluation of individual ensemble members with regards to biases in spatial gradients in temperature as well timing and magnitude of annual cycles.

Digital Elevation Models of Greenland based on combined radar and laser altimetry as well as high-resolution stereoscopic imagery

NASA Astrophysics Data System (ADS)

Levinsen, J. F.; Smith, B. E.; Sandberg Sorensen, L.; Khvorostovsky, K.; Simonsen, S. B.; Forsberg, R.

2015-12-01

A number of Digital Elevation Models (DEMs) of Greenland exist, each of which are applicable for different purposes. This study presents two such DEMs: One developed by merging contemporary radar and laser altimeter data, and one derived from high-resolution stereoscopic imagery. All products are made freely available. The former DEM covers the entire Greenland. It is specific to the year 2010, providing it with an advantage over previous models suffering from either a reduced spatial/ temporal data coverage or errors from surface elevation changes (SEC) occurring during data acquisition. Radar data are acquired with Envisat and CryoSat-2, and laser data with the Ice, Cloud, and land Elevation Satellite, the Land, Vegetation, and Ice Sensor, and the Airborne Topographic Mapper. Correcting radar data for errors from slope effects and surface penetration of the echoes, and merging these with laser data, yields a DEM capable of resolving both surface depressions as well as topographic features at higher altitudes. The spatial resolution is 2 x 2 km, making the DEM ideal for application in surface mass balance studies, SEC detection from radar altimetry, or for correcting such data for slope-induced errors. The other DEM is developed in a pilot study building the expertise to map all ice-free parts of Greenland. The work combines WorldView-2 and -3 as well as GeoEye1 imagery from 2014 and 2015 over the Disko, Narsaq, Tassilaq, and Zackenberg regions. The novelty of the work is the determination of the product specifications after elaborate discussions with interested parties from government institutions, the tourist industry, etc. Thus, a 10 m DEM, 1.5 m orthophotos, and vector maps are produced. This opens to the possibility of using orthophotos with up-to-date contour lines or for deriving updated coastlines to aid, e.g., emergency management. This allows for a product development directly in line with the needs of parties with specific interests in Greenland.

Natural selection and genetic variation for reproductive reaction norms in a wild bird population.

PubMed

Brommer, Jon E; Merilä, Juha; Sheldon, Ben C; Gustafsson, Lars

2005-06-01

Many morphological and life-history traits show phenotypic plasticity that can be described by reaction norms, but few studies have attempted individual-level analyses of reaction norms in the wild. We analyzed variation in individual reaction norms between laying date and three climatic variables (local temperature, local rainfall, and North Atlantic Oscillation) of 1126 female collared flycatchers (Ficedula albicollis) with a restricted maximum likehood linear mixed model approach using random-effect best linear unbiased predictor estimates for the elevation (i.e., expected laying date in the average environment) and slope (i.e., adjustment in laying date as a function of environment) of females' reaction norms. Variation in laying date was best explained by local temperature, and individual females differed in both the elevation and the slope of their laying date-temperature reaction norms. As revealed by animal model analyses, there was weak evidence for additive genetic variance of elevation (h2 +/- SE = 0.09 +/- 0.09), whereas there was no evidence for heritability of slope (h2 +/- SE = 0.00 +/- 0.01). Selection analysis, using a female's lifetime production of fledglings or recruits as an estimate of her fitness, revealed significant selection for a lower phenotypic value and breeding value for elevation (i.e., earlier laying date at the average temperature). There was selection for steeper phenotypic values of slope (i.e., greater plasticity in the adjustment of laying date to temperature), but no significant selection on the breeding values of slope. Although these results suggest that phenotypic laying date is influenced by additive genetic factors, as well as by an interaction with the environment, selection on plasticity would not produce an evolutionary response.

Object-oriented classification of drumlins from digital elevation models

NASA Astrophysics Data System (ADS)

Saha, Kakoli

Drumlins are common elements of glaciated landscapes which are easily identified by their distinct morphometric characteristics including shape, length/width ratio, elongation ratio, and uniform direction. To date, most researchers have mapped drumlins by tracing contours on maps, or through on-screen digitization directly on top of hillshaded digital elevation models (DEMs). This paper seeks to utilize the unique morphometric characteristics of drumlins and investigates automated extraction of the landforms as objects from DEMs by Definiens Developer software (V.7), using the 30 m United States Geological Survey National Elevation Dataset DEM as input. The Chautauqua drumlin field in Pennsylvania and upstate New York, USA was chosen as a study area. As the study area is huge (approximately covers 2500 sq.km. of area), small test areas were selected for initial testing of the method. Individual polygons representing the drumlins were extracted from the elevation data set by automated recognition, using Definiens' Multiresolution Segmentation tool, followed by rule-based classification. Subsequently parameters such as length, width and length-width ratio, perimeter and area were measured automatically. To test the accuracy of the method, a second base map was produced by manual on-screen digitization of drumlins from topographic maps and the same morphometric parameters were extracted from the mapped landforms using Definiens Developer. Statistical comparison showed a high agreement between the two methods confirming that object-oriented classification for extraction of drumlins can be used for mapping these landforms. The proposed method represents an attempt to solve the problem by providing a generalized rule-set for mass extraction of drumlins. To check that the automated extraction process was next applied to a larger area. Results showed that the proposed method is as successful for the bigger area as it was for the smaller test areas.

Pleiotropic effects of fenofibrate therapy on rats with hypertriglycemia.

PubMed

Sun, Bing; Xie, Yuan; Jiang, Jinfa; Wang, Yiping; Xu, Xiaolin; Zhao, Cuimei; Huang, Feifei

2015-04-14

Cardio-protective effect of fibrate therapy is controversial and current research is to evaluate the effect of fenofibrate therapy on rats with hypertriglycemia. Rats with hypertriglycemia were produced by 10% fructose administration (10 ml daily) for 4 weeks. After model has been successfully produced as reflected by increased triglyceride level, different doses of fenofibrate, namely low dose (50 mg/kg body weight) and high dose (100 mg/kg body weight), were orally prescribed for 2 weeks. At baseline, 4 weeks of fructose administration and 2 weeks of fenofibrate therapy, parameters of interest were evaluated and compared. At baseline, no significant differences of parameter were observed between groups. After 4 weeks of fructose prescription, triglyceride level increased in company with high density lipoprotein cholesterol (HDL-C) and apoprotein A1 (ApoA1) decreased. C-reactive protein (CRP) and malondialdehyde (MDA) levels were also elevated. Endothelial function was impaired as reflected by reduced nitric oxide (NO) production and elevated serum asymmetric dimethylarginine (ADMA) level. All these changes were significant as compared to the control group (P<0.05), suggesting that short-term of triglyceride elevation could potently initiate atherosclerosis. With 2 weeks of fenofibrate therapy, in comparison to un-treated group, triglyceride level was significantly reduced in parallel with HDL-C and ApoA1 elevation. Inflammation and oxidation were also profoundly ameliorated as reflected by CRP and MDA reduction. Notably, NO production was enhanced in company with serum ADMA level decrease. Overall, these improvements manifested in a dose-dependent manner, which was supported by multivariate regression analysis showing that after adjusted to other variables, the dose of fenofibrate therapy remained significantly associated with NO production and serum ADMA level, with OR of 1.042 (high-dose versus low-dose, 95% CI 1.028-1.055, P<0.05). Fenofibrate therapy not only could reduce triglyceride level but also confer pleiotropic effects in terms of endothelium-protection and amelioration of inflammation and oxidation in a dose-dependent manner.

Cockpit control system conceptual design

NASA Technical Reports Server (NTRS)

Meholic, Greg; Brown, Rhonda; Hall, Melissa; Harvey, Robert; Singer, Michael; Tella, Gustavo

1993-01-01

The purpose of this project was to provide a means for operating the ailerons, elevator, elevator trim, rudder, nosewheel steering, and brakes in the Triton primary flight trainer. The main design goals under consideration were to illustrate system and subsystem integration, control function ability, and producibility. Weight and maintenance goals were addressed.

Elevated expression of glutathione peroxidase in PC12 cells results in protection against methamphetamine but not MPTP toxicity.

PubMed

Hom, D G; Jiang, D; Hong, E J; Mo, J Q; Andersen, J K

1997-06-01

In vivo administration of either 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) or methamphetamine (MA) produces damage to the dopaminergic nervous system which may be due in part to the generation of reactive oxygen species (ROS). The resistance of superoxide dismutase (SOD) over-expressing transgenic mice to the effects of both MPTP and MA suggests the involvement of superoxide in the resulting neurotoxicity of both compounds. Superoxide can be converted by SOD to hydrogen peroxide, which itself can cause cellular degeneration by reacting with free iron to produce highly reactive hydroxyl radicals resulting in damage to proteins, nucleic acids and membrane phospholipids. Hydrogen peroxide has also been reported to be produced via inhibition of NADH dehydrogenase by MPP + formed during oxidation of MPTP by MAO-B and by dopamine auto-oxidation following MA-induced dopamine release from synaptic vesicles within nerve terminals. To test whether hydrogen peroxide is an important factor in the toxicity of either of these two neurotoxins, we created clonal PC12 lines expressing elevated levels of the hydrogen peroxide-reducing enzyme glutathione peroxidase (GSHPx). Elevation of GSHPx levels in PC12 was found to diminish the rise in ROS levels and lipid peroxidation resulting from MA but not MPTP treatment. Elevated levels of GSHPx also appeared to prevent decreases in transport-mediated dopamine uptake produced via MA administration as well as to attenuate toxin-induced cell loss as measured by either MTT reduction or LDH release. Our data, therefore, suggest that hydrogen peroxide production likely contributes to MA toxicity in dopaminergic neurons.

Anxiolytic effects of a semipurified constituent of guaraná seeds on rats in the elevated T-maze test.

PubMed

Roncon, Camila Marroni; Biesdorf de Almeida, Camila; Klein, Traudi; de Mello, João Carlos Palazzo; Audi, Elisabeth Aparecida

2011-02-01

The objective of this study was to investigate the effects of chronic administration of a semi-purified extract (Purified Extract A--PEA; 4, 8, or 16 mg/kg) of PAULLINIA CUPANA (guaraná) seeds on rats submitted to the elevated T-maze (ETM) model of generalized anxiety and panic disorders. The selective serotonin (5-HT) reuptake inhibitor (SSRI) paroxetine (PAR; 3 mg/kg), was used as a positive control. To evaluate possible serotonergic and dopaminergic neurotransmission involvement in the action of PEA during the ETM test, ineffective doses of metergoline (MET; 5-HT (2A/2C) antagonist receptor) or sulpiride (SUL; dopaminergic receptor antagonist) were acutely administered together with the PEA. The locomotion of the rats was assessed in a circular arena following each drug treatment. Both PEA (8 and 16 mg/kg) and PAR (3 mg/kg) increased one-way escape latencies from the open arm of the ETM, indicating a panicolytic effect compared to the control group. MET, in higher doses (1, 2 or 3 mg/kg), produced a panicolytic effect in the ETM test, whereas SUL did not (10, 20 or 40 mg/kg). The panicolytic effect produced by PEA (8 mg/kg) was blocked by both MET (2 mg/kg) and SUL (20 mg/kg), whereas the panicolytic effect produced by PAR (3 mg/kg) was blocked only by MET (2 mg/kg). These results show that chronic treatment with PEA produces a panicolytic effect during the ETM test, and that the dopaminergic and the serotonergic neurotransmission systems are involved in this effect. © Georg Thieme Verlag KG Stuttgart · New York.

Internalized elevation perception of simple stimuli in cochlear-implant and normal-hearing listeners

PubMed Central

Thakkar, Tanvi; Goupell, Matthew J.

2014-01-01

In normal-hearing (NH) listeners, elevation perception is produced by the spectral cues imposed by the pinna, head, and torso. Elevation perception in cochlear-implant (CI) listeners appears to be non-existent; this may be a result of poorly encoded spectral cues. In this study, an analog of elevation perception was investigated by having 15 CI and 8 NH listeners report the intracranial location of spectrally simple signals (single-electrode or bandlimited acoustic stimuli, respectively) in both horizontal and vertical dimensions. Thirteen CI listeners and all of the NH listeners showed an association between place of stimulation (i.e., stimulus frequency) and perceived elevation, generally responding with higher elevations for more basal stimulation. This association persisted in the presence of a randomized temporal pitch, suggesting that listeners were not associating pitch with elevation. These data provide evidence that CI listeners might perceive changes in elevation if they were presented stimuli with sufficiently salient elevation cues. PMID:25096117

Elevation and igneous crater modification on Venus: Implications for magmatic volatile content

NASA Technical Reports Server (NTRS)

Wichman, R. W.

1993-01-01

Although most impact craters on Venus preserve nearly pristine crater rim and ejecta features, a small number of craters have been identified showing clear evidence of either igneous intrusion emplacement (floor-fracturing) beneath the crater floor or of volcanically embayed exterior ejecta deposits. Since the volcanically embayed craters consistently occur at higher elevations than the identified floor-fractured craters, this report proposes that igneous crater modification on Venus is elevation dependent. This report describes how regional variations in magmatic neutral buoyancy could produce such elevation dependent crater modification and considers the implications for typical magmatic volatile contents on Venus.

On using scatterometer and altimeter data to improve storm surge forecasting in the Adriatic Sea

NASA Astrophysics Data System (ADS)

Bajo, Marco; Umgiesser, Georg; De Biasio, Francesco; Vignudelli, Stefano; Zecchetto, Stefano

2017-04-01

Satellite data are seldom used in storm surge forecasting. Among the most important issues related to the storm surge forecasting are the quality of the model wind forcing and the initial condition of the sea surface elevation. In this work, focused on storm surge forecasting in the Adriatic Sea, satellite scatterometer wind data are used to correct the wind speed and direction biases of the ECMWF global atmospheric model by tuning the spatial fields, as an alternative to data assimilation. The capability of such an unbiased wind is tested against that of a high resolution wind, produced by a regional non-hydrostatic model. On the other hand, altimeter Total Water Level Envelope (TWLE) data, which provide the sea level elevation, are used to improve the accuracy of the initial state of the model simulations. This is done by assimilating into a storm surge model the TWLE obtained by the altimeter observations along ground tracks, after subtraction of the tidal components. In order to test the methodology, eleven storm surge events recorded in Venice, from 2008 to 2012, have been simulated using different configurations of forcing wind and altimeter data assimilation. Results show that the relative error on the estimation of the maximum surge peak, averaged over the cases considered, decreases from 13% to 7% using both the unbiased wind and the altimeter data assimilation, while forcing the hydrodynamic model with the high resolution wind (no tuning), the altimeter data assimilation reduces the error from 9% to 6%.

Combining binary decision tree and geostatistical methods to estimate snow distribution in a mountain watershed

USGS Publications Warehouse

Balk, Benjamin; Elder, Kelly

2000-01-01

We model the spatial distribution of snow across a mountain basin using an approach that combines binary decision tree and geostatistical techniques. In April 1997 and 1998, intensive snow surveys were conducted in the 6.9‐km2 Loch Vale watershed (LVWS), Rocky Mountain National Park, Colorado. Binary decision trees were used to model the large‐scale variations in snow depth, while the small‐scale variations were modeled through kriging interpolation methods. Binary decision trees related depth to the physically based independent variables of net solar radiation, elevation, slope, and vegetation cover type. These decision tree models explained 54–65% of the observed variance in the depth measurements. The tree‐based modeled depths were then subtracted from the measured depths, and the resulting residuals were spatially distributed across LVWS through kriging techniques. The kriged estimates of the residuals were added to the tree‐based modeled depths to produce a combined depth model. The combined depth estimates explained 60–85% of the variance in the measured depths. Snow densities were mapped across LVWS using regression analysis. Snow‐covered area was determined from high‐resolution aerial photographs. Combining the modeled depths and densities with a snow cover map produced estimates of the spatial distribution of snow water equivalence (SWE). This modeling approach offers improvement over previous methods of estimating SWE distribution in mountain basins.

Neural Flight Control System

NASA Technical Reports Server (NTRS)

Gundy-Burlet, Karen

2003-01-01

The Neural Flight Control System (NFCS) was developed to address the need for control systems that can be produced and tested at lower cost, easily adapted to prototype vehicles and for flight systems that can accommodate damaged control surfaces or changes to aircraft stability and control characteristics resulting from failures or accidents. NFCS utilizes on a neural network-based flight control algorithm which automatically compensates for a broad spectrum of unanticipated damage or failures of an aircraft in flight. Pilot stick and rudder pedal inputs are fed into a reference model which produces pitch, roll and yaw rate commands. The reference model frequencies and gains can be set to provide handling quality characteristics suitable for the aircraft of interest. The rate commands are used in conjunction with estimates of the aircraft s stability and control (S&C) derivatives by a simplified Dynamic Inverse controller to produce virtual elevator, aileron and rudder commands. These virtual surface deflection commands are optimally distributed across the aircraft s available control surfaces using linear programming theory. Sensor data is compared with the reference model rate commands to produce an error signal. A Proportional/Integral (PI) error controller "winds up" on the error signal and adds an augmented command to the reference model output with the effect of zeroing the error signal. In order to provide more consistent handling qualities for the pilot, neural networks learn the behavior of the error controller and add in the augmented command before the integrator winds up. In the case of damage sufficient to affect the handling qualities of the aircraft, an Adaptive Critic is utilized to reduce the reference model frequencies and gains to stay within a flyable envelope of the aircraft.

Estimation of VOC emissions from produced-water treatment ponds in Uintah Basin oil and gas field using modeling techniques

NASA Astrophysics Data System (ADS)

Tran, H.; Mansfield, M. L.; Lyman, S. N.; O'Neil, T.; Jones, C. P.

2015-12-01

Emissions from produced-water treatment ponds are poorly characterized sources in oil and gas emission inventories that play a critical role in studying elevated winter ozone events in the Uintah Basin, Utah, U.S. Information gaps include un-quantified amounts and compositions of gases emitted from these facilities. The emitted gases are often known as volatile organic compounds (VOCs) which, beside nitrogen oxides (NOX), are major precursors for ozone formation in the near-surface layer. Field measurement campaigns using the flux-chamber technique have been performed to measure VOC emissions from a limited number of produced water ponds in the Uintah Basin of eastern Utah. Although the flux chamber provides accurate measurements at the point of sampling, it covers just a limited area of the ponds and is prone to altering environmental conditions (e.g., temperature, pressure). This fact raises the need to validate flux chamber measurements. In this study, we apply an inverse-dispersion modeling technique with evacuated canister sampling to validate the flux-chamber measurements. This modeling technique applies an initial and arbitrary emission rate to estimate pollutant concentrations at pre-defined receptors, and adjusts the emission rate until the estimated pollutant concentrations approximates measured concentrations at the receptors. The derived emission rates are then compared with flux-chamber measurements and differences are analyzed. Additionally, we investigate the applicability of the WATER9 wastewater emission model for the estimation of VOC emissions from produced-water ponds in the Uintah Basin. WATER9 estimates the emission of each gas based on properties of the gas, its concentration in the waste water, and the characteristics of the influent and treatment units. Results of VOC emission estimations using inverse-dispersion and WATER9 modeling techniques will be reported.

Creating Digital Elevation Model Using a Mobile Device

NASA Astrophysics Data System (ADS)

Durmaz, A. İ.

2017-11-01

DEM (Digital Elevation Models) is the best way to interpret topography on the ground. In recent years, lidar technology allows to create more accurate elevation models. However, the problem is this technology is not common all over the world. Also if Lidar data are not provided by government agencies freely, people have to pay lots of money to reach these point clouds. In this article, we will discuss how we can create digital elevation model from less accurate mobile devices' GPS data. Moreover, we will evaluate these data on the same mobile device which we collected data to reduce cost of this modeling.

Digital elevation modeling via curvature interpolation for lidar data

USDA-ARS?s Scientific Manuscript database

Digital elevation model (DEM) is a three-dimensional (3D) representation of a terrain's surface - for a planet (including Earth), moon, or asteroid - created from point cloud data which measure terrain elevation. Its modeling requires surface reconstruction for the scattered data, which is an ill-p...

Potential indirect effects of aerosol on tropical cyclone intensity: convective fluxes and cold-pool activity

NASA Astrophysics Data System (ADS)

Krall, G. M.; Cottom, W. R.

2012-01-01

Observational and model evidence suggest that a 2008 Western Pacific typhoon (NURI) ingested elevated concentrations of aerosol as it neared the Chinese coast. This study uses a regional model with two-moment bin-emulating microphysics to simulate the typhoon as it enters the field of elevated aerosol concentrations. A clean maritime field of cloud condensation nuclei (CCN) was prescribed as marine background CCN concentrations and then based on satellite and global aerosol model output, increased to pollution levels and further enhanced in sensitivity tests. The typhoon was simulated for 96 h beginning 17 August 2008. During the final 60 h CCN concentrations were enhanced as it neared the Philippines and coastal China. The model was initialized with both global reanalysis model data and irregularly spaced dropsonde data from the 2008 T-PARC observational campaign using an objective analysis routine. At 36 h, the internal nudging of the model was switched off and allowed to freely evolve on its own. As the typhoon encountered the elevated CCN in the sensitivity tests, a significant perturbation of windspeed, convective fluxes, and hydrometeor species behavior was simulated. Early during the ingestion of enhanced CCN, precipitation was reduced due to suppressed collision and coalescence, and storm winds increased in strength. Subsequently, owing to reduced fall speeds of the smaller drops, greater amounts of condensate were thrust into supercooled levels where the drops froze releasing greater amounts of latent heat of freezing. Convection thereby intensified which resulted in enhanced rainfall and more vigorous convectively-produced downdrafts. As the convection intensified in the outer rainbands the storm drifted over the developing cold-pools. The enhanced cold-pools blocked the inflow of warm, moist air into the core of the typhoon which led to a weakening of the typhoon with significantly reduced low level wind speeds. The very high amounts of pollution aerosols resulted in large amounts of condensate being thrust into the storm anvil which weakened convective downdrafts and cold-pools, yet the system did show reductions in windspeed (although weaker) compared with the clean control run. This study suggests that ingestion of elevated amounts of CCN into a tropical cyclone (TC) can appreciably alter the intensity of the storm. This implies that intensity prediction of TCs would be improved by including indirect aerosol affects. However, the pollution aerosols have very little impact on the storm track.

Quantitative fractography by digital image processing: NIH Image macro tools for stereo pair analysis and 3-D reconstruction.

PubMed

Hein, L R

2001-10-01

A set of NIH Image macro programs was developed to make qualitative and quantitative analyses from digital stereo pictures produced by scanning electron microscopes. These tools were designed for image alignment, anaglyph representation, animation, reconstruction of true elevation surfaces, reconstruction of elevation profiles, true-scale elevation mapping and, for the quantitative approach, surface area and roughness calculations. Limitations on time processing, scanning techniques and programming concepts are also discussed.

Evaluation of Aster Gdem v3 Using Icesat Laser Altimetry

NASA Astrophysics Data System (ADS)

Carabajal, C. C.; Boy, J.-P.

2016-06-01

We have used a set of Ground Control Points (GCPs) derived from altimetry measurements from the Ice, Cloud and land Elevation Satellite (ICESat) to evaluate the quality of the 30 m posting ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) Global Digital Elevation Model (GDEM) V3 elevation products produced by NASA/METI for Greenland and Antarctica. These data represent the highest quality globally distributed altimetry measurements that can be used for geodetic ground control, selected by applying rigorous editing criteria, useful at high latitudes, where other topographic control is scarce. Even if large outliers still remain in all ASTER GDEM V3 data for both, Greenland and Antarctica, they are significantly reduced when editing ASTER by number of scenes (N≥5) included in the elevation processing. For 667,354 GCPs in Greenland, differences show a mean of 13.74 m, a median of -6.37 m, with an RMSE of 109.65 m. For Antarctica, 6,976,703 GCPs show a mean of 0.41 m, with a median of -4.66 m, and a 54.85 m RMSE, displaying smaller means, similar medians, and less scatter than GDEM V2. Mean and median differences between ASTER and ICESat are lower than 10 m, and RMSEs lower than 10 m for Greenland, and 20 m for Antarctica when only 9 to 31 scenes are included.

A simple methodology to produce flood risk maps consistent with FEMA's base flood elevation maps: Implementation and validation over the entire contiguous United States

NASA Astrophysics Data System (ADS)

Goteti, G.; Kaheil, Y. H.; Katz, B. G.; Li, S.; Lohmann, D.

2011-12-01

In the United States, government agencies as well as the National Flood Insurance Program (NFIP) use flood inundation maps associated with the 100-year return period (base flood elevation, BFE), produced by the Federal Emergency Management Agency (FEMA), as the basis for flood insurance. A credibility check of the flood risk hydraulic models, often employed by insurance companies, is their ability to reasonably reproduce FEMA's BFE maps. We present results from the implementation of a flood modeling methodology aimed towards reproducing FEMA's BFE maps at a very fine spatial resolution using a computationally parsimonious, yet robust, hydraulic model. The hydraulic model used in this study has two components: one for simulating flooding of the river channel and adjacent floodplain, and the other for simulating flooding in the remainder of the catchment. The first component is based on a 1-D wave propagation model, while the second component is based on a 2-D diffusive wave model. The 1-D component captures the flooding from large-scale river transport (including upstream effects), while the 2-D component captures the flooding from local rainfall. The study domain consists of the contiguous United States, hydrologically subdivided into catchments averaging about 500 km2 in area, at a spatial resolution of 30 meters. Using historical daily precipitation data from the Climate Prediction Center (CPC), the precipitation associated with the 100-year return period event was computed for each catchment and was input to the hydraulic model. Flood extent from the FEMA BFE maps is reasonably replicated by the 1-D component of the model (riverine flooding). FEMA's BFE maps only represent the riverine flooding component and are unavailable for many regions of the USA. However, this modeling methodology (1-D and 2-D components together) covers the entire contiguous USA. This study is part of a larger modeling effort from Risk Management Solutions° (RMS) to estimate flood risk associated with extreme precipitation events in the USA. Towards this greater objective, state-of-the-art models of flood hazard and stochastic precipitation are being implemented over the contiguous United States. Results from the successful implementation of the modeling methodology will be presented.

Parametric Study of Wall Shear Stress in Idealized Avian Airways

NASA Astrophysics Data System (ADS)

Farnsworth, Michael S.; Riede, Tobias; Thomson, Scott L.

2017-11-01

Because wall shear stress (WSS) affects cell response, WSS patterns in avian respiratory airways may be related to the origin of the syrinx and corresponding voice-producing tissue structures (e.g., membranes or vocal folds) in birds. To explore possible linkages between WSS patterns and the locations of avian voice-producing structures, a computational model of flow through an idealized portion of the avian respiratory airway, including trachea and primary bronchi sections, has been developed. The flow is governed by the Navier-Stokes equations, with velocity boundary conditions derived from pressure-flow data in an adult zebra finch during quiet respiration. Geometric parameters such as tracheal/bronchial diameter and length, as well as bronchial branching angle, are parametrically varied based on data for different avian species. Simulation results predict elevated WSS in the vicinity of the tracheobronchial juncture, the location at which voice-producing tissues are found in avian species. In this presentation, the model will be described and spatial distributions of WSS during inspiration and expiration will be presented and compared for different geometric configurations and respiration rates and waveforms. Funding for this project from the Gordon and Betty Moore Foundation (Grant 4498) is gratefully acknowledged.

Reducing expression of synapse-restricting protein Ephexin5 ameliorates Alzheimer’s-like impairment in mice

PubMed Central

Sell, Gabrielle L.; Schaffer, Thomas B.; Margolis, Seth S.

2017-01-01

Accumulation of amyloid-β (Aβ) protein may cause synapse degeneration and cognitive impairment in Alzheimer’s disease (AD) by reactivating expression of the developmental synapse repressor protein Ephexin5 (also known as ARHGEF15). Here, we have reported that Aβ is sufficient to acutely promote the production of Ephexin5 in mature hippocampal neurons and in mice expressing human amyloid precursor protein (hAPP mice), a model for familial AD that produces high brain levels of Aβ. Ephexin5 expression was highly elevated in the hippocampi of human AD patients, indicating its potential relevance to AD. We also observed elevated Ephexin5 expression in the hippocampi of hAPP mice. Removal of Ephexin5 expression eliminated hippocampal dendritic spine loss and rescued AD-associated behavioral deficits in the hAPP mice. Furthermore, selective reduction of Ephexin5 expression using shRNA in the dentate gyrus of presymptomatic adolescent hAPP mice was sufficient to protect these mice from developing cognitive impairment. Thus, pathological elevation of Ephexin5 expression critically drives Aβ-induced memory impairment, and strategies aimed at reducing Ephexin5 levels may represent an effective approach to treating AD. PMID:28346227

Insulin resistance and diabetes mellitus in transgenic mice expressing nuclear SREBP-1c in adipose tissue: model for congenital generalized lipodystrophy

PubMed Central

Shimomura, Iichiro; Hammer, Robert E.; Richardson, James A.; Ikemoto, Shinji; Bashmakov, Yuriy; Goldstein, Joseph L.; Brown, Michael S.

1998-01-01

Overexpression of the nuclear form of sterol regulatory element-binding protein-1c (nSREBP-1c/ADD1) in cultured 3T3-L1 preadipocytes was shown previously to promote adipocyte differentiation. Here, we produced transgenic mice that overexpress nSREBP-1c in adipose tissue under the control of the adipocyte-specific aP2 enhancer/promoter. A syndrome with the following features was observed: (1) Disordered differentiation of adipose tissue. White fat failed to differentiate fully, and the size of white fat depots was markedly decreased. Brown fat was hypertrophic and contained fat-laden cells resembling immature white fat. Levels of mRNA encoding adipocyte differentiation markers (C/EBPα, PPARγ, adipsin, leptin, UCP1) were reduced, but levels of Pref-1 and TNFα were increased. (2) Marked insulin resistance with 60-fold elevation in plasma insulin. (3) Diabetes mellitus with elevated blood glucose (>300 mg/dl) that failed to decline when insulin was injected. (4) Fatty liver from birth and elevated plasma triglyceride levels later in life. These mice exhibit many of the features of congenital generalized lipodystrophy (CGL), an autosomal recessive disorder in humans. PMID:9784493

Alpha-fetoprotein-producing esophageal adenocarcinoma: a mimicker of hepatocellular carcinoma.

PubMed

Wang, Jeremy; Liu, Wendy; Parikh, Keyur; Post, Anthony Benjamin

2017-02-01

Alpha-fetoprotein (AFP)-producing esophageal adenocarcinoma (EAC) is a rare occurrence. Elevation of serum AFP is commonly associated with hepatocellular carcinoma and yolk sac tumors, but rarely with esophageal carcinoma. Here, we report a rare case of AFP-producing EAC. A 51-year-old man presented with two weeks of acid reflux and a 35-lb weight loss. Laboratory data were notable for transaminitis and AFP was 2524 ng/mL. Computed tomography of the abdomen revealed abnormal thickening of the esophagus and multiple metastatic masses throughout the liver. Biopsy of one of the masses revealed adenocarcinoma of gastrointestinal origin. Subsequent upper endoscopy revealed an esophageal mass with biopsy notable for ulcerated dysplastic glandular mucosa with likely underlying malignancy. The patient underwent palliative esophageal stent placement but died two months later. Elevated AFP levels are an unusual occurrence in EAC. Prognosis is poor given its advanced presenting stage and high metastatic potential. Most cases are unsuccessfully treated with surgery and chemotherapy. Serial measurement of serum AFP may be useful for monitoring clinical status and treatment response. Clinicians should consider AFP-producing EAC in their differential diagnosis in the work-up of a liver mass in the setting of elevated AFP or liver function impairment, especially in the absence of chronic liver disease.

On neutral metacommunity patterns of river basins at different scales of aggregation

NASA Astrophysics Data System (ADS)

Convertino, Matteo; Muneepeerakul, Rachata; Azaele, Sandro; Bertuzzo, Enrico; Rinaldo, Andrea; Rodriguez-Iturbe, Ignacio

2009-08-01

Neutral metacommunity models for spatial biodiversity patterns are implemented on river networks acting as ecological corridors at different resolution. Coarse-graining elevation fields (under the constraint of preserving the basin mean elevation) produce a set of reconfigured drainage networks. The hydrologic assumption made implies uniform runoff production such that each link has the same habitat capacity. Despite the universal scaling properties shown by river basins regardless of size, climate, vegetation, or exposed lithology, we find that species richness at local and regional scales exhibits resolution-dependent behavior. In addition, we investigate species-area relationships and rank-abundance patterns. The slopes of the species-area relationships, which are consistent over coarse-graining resolutions, match those found in real landscapes in the case of long-distance dispersal. The rank-abundance patterns are independent of the resolution over a broad range of dispersal length. Our results confirm that strong interactions occur between network structure and the dispersal of species and that under the assumption of neutral dynamics, these interactions produce resolution-dependent biodiversity patterns that diverge from expectations following from universal geomorphic scaling laws. Both in theoretical and in applied ecology studying how patterns change in resolution is relevant for understanding how ecological dynamics work in fragmented landscape and for sampling and biodiversity management campaigns, especially in consideration of climate change.

a Near-Global Bare-Earth dem from Srtm

NASA Astrophysics Data System (ADS)

Gallant, J. C.; Read, A. M.

2016-06-01

The near-global elevation product from NASA's Shuttle Radar Topographic Mission (SRTM) has been widely used since its release in 2005 at 3 arcsecond resolution and the release of the 1 arcsecond version in late 2014 means that the full potential of the SRTM DEM can now be realised. However the routine use of SRTM for analytical purposes such as catchment hydrology, flood inundation, habitat mapping and soil mapping is still seriously impeded by the presence of artefacts in the data, primarily the offsets due to tree cover and the random noise. This paper describes the algorithms being developed to remove those offsets, based on the methods developed to produce the Australian national elevation model from SRTM data. The offsets due to trees are estimated using the GlobeLand30 (National Geomatics Center of China) and Global Forest Change (University of Maryland) products derived from Landsat, along with the ALOS PALSAR radar image data (JAXA) and the global forest canopy height map (NASA). The offsets are estimated using several processes and combined to produce a single continuous tree offset layer that is subtracted from the SRTM data. The DEM products will be made freely available on completion of the first draft product, and the assessment of that product is expected to drive further improvements to the methods.

Hydrologic connectivity: Quantitative assessments of hydrologic-enforced drainage structures in an elevation model

USGS Publications Warehouse

Poppenga, Sandra K.; Worstell, Bruce B.

2016-01-01

Elevation data derived from light detection and ranging present challenges for hydrologic modeling as the elevation surface includes bridge decks and elevated road features overlaying culvert drainage structures. In reality, water is carried through these structures; however, in the elevation surface these features impede modeled overland surface flow. Thus, a hydrologically-enforced elevation surface is needed for hydrodynamic modeling. In the Delaware River Basin, hydrologic-enforcement techniques were used to modify elevations to simulate how constructed drainage structures allow overland surface flow. By calculating residuals between unfilled and filled elevation surfaces, artificially pooled depressions that formed upstream of constructed drainage structure features were defined, and elevation values were adjusted by generating transects at the location of the drainage structures. An assessment of each hydrologically-enforced drainage structure was conducted using field-surveyed culvert and bridge coordinates obtained from numerous public agencies, but it was discovered the disparate drainage structure datasets were not comprehensive enough to assess all remotely located depressions in need of hydrologic-enforcement. Alternatively, orthoimagery was interpreted to define drainage structures near each depression, and these locations were used as reference points for a quantitative hydrologic-enforcement assessment. The orthoimagery-interpreted reference points resulted in a larger corresponding sample size than the assessment between hydrologic-enforced transects and field-surveyed data. This assessment demonstrates the viability of rules-based hydrologic-enforcement that is needed to achieve hydrologic connectivity, which is valuable for hydrodynamic models in sensitive coastal regions. Hydrologic-enforced elevation data are also essential for merging with topographic/bathymetric elevation data that extend over vulnerable urbanized areas and dynamic coastal regions.

Dynamics of sea level rise and coastal flooding on a changing landscape

NASA Astrophysics Data System (ADS)

Bilskie, M. V.; Hagen, S. C.; Medeiros, S. C.; Passeri, D. L.

2014-02-01

Standard approaches to determining the impacts of sea level rise (SLR) on storm surge flooding employ numerical models reflecting present conditions with modified sea states for a given SLR scenario. In this study, we advance this paradigm by adjusting the model framework so that it reflects not only a change in sea state but also variations to the landscape (morphologic changes and urbanization of coastal cities). We utilize a numerical model of the Mississippi and Alabama coast to simulate the response of hurricane storm surge to changes in sea level, land use/land cover, and land surface elevation for past (1960), present (2005), and future (2050) conditions. The results show that the storm surge response to SLR is dynamic and sensitive to changes in the landscape. We introduce a new modeling framework that includes modification of the landscape when producing storm surge models for future conditions.

The browning value changes and spectral analysis on the Maillard reaction product from glucose and methionine model system

NASA Astrophysics Data System (ADS)

Al-Baarri, A. N.; Legowo, A. M.; Widayat

2018-01-01

D-glucose has been understood to provide the various effect on the reactivity in Maillard reaction resulting in the changes in physical performance of food product. Therefore this research was done to analyse physical appearance of Maillard reaction product made of D-glucose and methionine as a model system. The changes in browning value and spectral analysis model system were determined. The glucose-methionine model system was produced through the heating treatment at 50°C and RH 70% for 24 hours. The data were collected for every three hour using spectrophotometer. As result, browning value was elevated with the increase of heating time and remarkably high if compare to the D-glucose only. Furthermore, the spectral analysis showed that methionine turned the pattern of peak appearance. As conclusion, methionine raised the browning value and changed the pattern of spectral analysis in Maillard reaction model system.

Simulated Impact of Climate Change on Fremont Native American Maize Farming in Utah at the MCA-LIA Transition, ca. 12-14th c. CE

NASA Astrophysics Data System (ADS)

Thomson, M. J.; MacDonald, G. M.

2016-12-01

We present the results of a computational crop modeling experiment for ancient Fremont Native American Zea mays farming in the Uinta Basin, Utah, at the Medieval Climate Anomaly to Little Ice Age (MCA-LIA) transition, ca. 850-1450 CE. This period coincides with the rapid disappearance of complex Native American cultures from the American Southwest. The crop model (the Environment Policy Impact Calculator, EPIC) was driven by statistically downscaled precipitation, temperature and shortwave radiative flux from the Community Earth System Model Last Millennium Ensemble (CESM LME). We found that maize yield responded to changes in the model-reconstructed temperature and precipitation; and periods of reduced maize yields corresponded to the abandonment of higher elevation Fremont 14C-dated archaeological sites. EPIC produces good agreement between modeled and historically reported maize yields for the 19th century.

Development of a finite element model of female foot for high-heeled shoe design.

PubMed

Yu, Jia; Cheung, Jason Tak-Man; Fan, Yubo; Zhang, Yan; Leung, Aaron Kam-Lun; Zhang, Ming

2008-01-01

Wearing high-heeled shoes may produce deleterious effects on the musculoskeletal system while elevation of the shoe heel with arch insole insert is used as a treatment strategy for plantar fasciitis. Due to limitations of the experimental approaches, direct measurements of internal stress/strain of the foot are impossible or invasive. This study aims at developing a finite element model for evaluating the biomechanical effects of high-heeled support on the ankle-foot complex. A 3D anatomically detailed FE model of the female foot and ankle together with a high-heeled support was developed and used to investigate the plantar contact pressure and internal loading responses of the bony and soft tissue structures of the foot with varying heel heights during simulated balanced standing. In the balanced standing position with high-heeled support, a pronounced increase in von Mises stress at the first metatarsophalangeal (MTP) joint was predicted. The strain on plantar fascia decreased compared to the flat horizontal support and valgus deformity of the hallux was not significant. The increased stress in forefoot especially at the first MTP segment during prolonged high-heeled standing may contribute to progressive hallux valgus (HV) deformity. However, the reduced tensile strain in the plantar fascia with heel elevation may help relieve plantar fasciitis related pain and inflammation.

Greenland annual accumulation along the EGIG line, 1959-2004, from ASIRAS airborne radar and neutron-probe density measurements

NASA Astrophysics Data System (ADS)

Overly, Thomas B.; Hawley, Robert L.; Helm, Veit; Morris, Elizabeth M.; Chaudhary, Rohan N.

2016-08-01

We report annual snow accumulation rates from 1959 to 2004 along a 250 km segment of the Expéditions Glaciologiques Internationales au Groenland (EGIG) line across central Greenland using Airborne SAR/Interferometric Radar Altimeter System (ASIRAS) radar layers and high resolution neutron-probe (NP) density profiles. ASIRAS-NP-derived accumulation rates are not statistically different (95 % confidence interval) from in situ EGIG accumulation measurements from 1985 to 2004. ASIRAS-NP-derived accumulation increases by 20 % below 3000 m elevation, and increases by 13 % above 3000 m elevation for the period 1995 to 2004 compared to 1985 to 1994. Three Regional Climate Models (PolarMM5, RACMO2.3, MAR) underestimate snow accumulation below 3000 m by 16-20 % compared to ASIRAS-NP from 1985 to 2004. We test radar-derived accumulation rates sensitivity to density using modeled density profiles in place of NP densities. ASIRAS radar layers combined with Herron and Langway (1980) model density profiles (ASIRAS-HL) produce accumulation rates within 3.5 % of ASIRAS-NP estimates in the dry snow region. We suggest using Herron and Langway (1980) density profiles to calibrate radar layers detected in dry snow regions of ice sheets lacking detailed in situ density measurements, such as those observed by the Operation IceBridge campaign.

Landslide susceptibility mapping using frequency ratio, logistic regression, artificial neural networks and their comparison: A case study from Kat landslides (Tokat—Turkey)

NASA Astrophysics Data System (ADS)

Yilmaz, Işık

2009-06-01

The purpose of this study is to compare the landslide susceptibility mapping methods of frequency ratio (FR), logistic regression and artificial neural networks (ANN) applied in the Kat County (Tokat—Turkey). Digital elevation model (DEM) was first constructed using GIS software. Landslide-related factors such as geology, faults, drainage system, topographical elevation, slope angle, slope aspect, topographic wetness index (TWI) and stream power index (SPI) were used in the landslide susceptibility analyses. Landslide susceptibility maps were produced from the frequency ratio, logistic regression and neural networks models, and they were then compared by means of their validations. The higher accuracies of the susceptibility maps for all three models were obtained from the comparison of the landslide susceptibility maps with the known landslide locations. However, respective area under curve (AUC) values of 0.826, 0.842 and 0.852 for frequency ratio, logistic regression and artificial neural networks showed that the map obtained from ANN model is more accurate than the other models, accuracies of all models can be evaluated relatively similar. The results obtained in this study also showed that the frequency ratio model can be used as a simple tool in assessment of landslide susceptibility when a sufficient number of data were obtained. Input process, calculations and output process are very simple and can be readily understood in the frequency ratio model, however logistic regression and neural networks require the conversion of data to ASCII or other formats. Moreover, it is also very hard to process the large amount of data in the statistical package.

Assessing model sensitivity and uncertainty across multiple Free-Air CO2 Enrichment experiments.

NASA Astrophysics Data System (ADS)

Cowdery, E.; Dietze, M.

2015-12-01

As atmospheric levels of carbon dioxide levels continue to increase, it is critical that terrestrial ecosystem models can accurately predict ecological responses to the changing environment. Current predictions of net primary productivity (NPP) in response to elevated atmospheric CO2 concentrations are highly variable and contain a considerable amount of uncertainty. It is necessary that we understand which factors are driving this uncertainty. The Free-Air CO2 Enrichment (FACE) experiments have equipped us with a rich data source that can be used to calibrate and validate these model predictions. To identify and evaluate the assumptions causing inter-model differences we performed model sensitivity and uncertainty analysis across ambient and elevated CO2 treatments using the Data Assimilation Linked Ecosystem Carbon (DALEC) model and the Ecosystem Demography Model (ED2), two process-based models ranging from low to high complexity respectively. These modeled process responses were compared to experimental data from the Kennedy Space Center Open Top Chamber Experiment, the Nevada Desert Free Air CO2 Enrichment Facility, the Rhinelander FACE experiment, the Wyoming Prairie Heating and CO2 Enrichment Experiment, the Duke Forest Face experiment and the Oak Ridge Experiment on CO2 Enrichment. By leveraging data access proxy and data tilling services provided by the BrownDog data curation project alongside analysis modules available in the Predictive Ecosystem Analyzer (PEcAn), we produced automated, repeatable benchmarking workflows that are generalized to incorporate different sites and ecological models. Combining the observed patterns of uncertainty between the two models with results of the recent FACE-model data synthesis project (FACE-MDS) can help identify which processes need further study and additional data constraints. These findings can be used to inform future experimental design and in turn can provide informative starting point for data assimilation.

Building Daily 30-meter Spatial Resolution Maps of Surface Water Bodies from MODIS Data Using a Novel Technique for Transferring Information Across Space and Time

NASA Astrophysics Data System (ADS)

Khandelwal, A.; Karpatne, A.; Kumar, V.

2017-12-01

In this paper, we present novel methods for producing surface water maps at 30 meter spatial resolution at a daily temporal resolution. These new methods will make use of the MODIS spectral data from Terra (available daily since 2000) to produce daily maps at 250 meter and 500 meter resolution, and then refine them using the relative elevation ordering of pixels at 30 meter resolution. The key component of these methods is the use of elevation structure (relative elevation ordering) of a water body. Elevation structure is not explicitly available at desired resolution for most water bodies in the world and hence it will be estimated using our previous work that uses the history of imperfect labels. In this paper, we will present a new technique that uses elevation structure (unlike existing pixel based methods) to enforce temporal consistency in surface water extents (lake area on nearby dates is likely to be very similar). This will greatly improve the quality of the MODIS scale land/water labels since daily MODIS data can have a large amount of missing (or poor quality) data due to clouds and other factors. The quality of these maps will be further improved using elevation based resolution refinement approach that will make use of elevation structure estimated at Landsat scale. With the assumption that elevation structure does not change over time, it provides a very effective way to transfer information between datasets even when they are not observed concurrently. In this work, we will derive elevation structure at Landsat scale from monthly water extent maps spanning 1984-2015, publicly available through a joint effort of Google Earth Engine and the European Commission's Joint Research Centre (JRC). This elevation structure will then be used to refine spatial resolution of Modis scale maps from 2000 onwards. We will present the analysis of these methods on a large and diverse set of water bodies across the world.

Elevated CO2 increases glomalin-related soil protein (GRSP) in the rhizosphere of Robinia pseudoacacia L. seedlings in Pb- and Cd-contaminated soils.

PubMed

Jia, Xia; Zhao, Yonghua; Liu, Tuo; Huang, Shuping; Chang, Yafei

2016-11-01

Glomalin-related soil protein (GRSP), which contains glycoproteins produced by arbuscular mycorrhizal fungi (AMF), as well as non-mycorrhizal-related heat-stable proteins, lipids, and humic materials, is generally categorized into two fractions: easily extractable GRSP (EE-GRSP) and total GRSP (T-GRSP). GRSP plays an important role in soil carbon (C) sequestration and can stabilize heavy metals such as lead (Pb), cadmium (Cd), and manganese (Mn). Soil contamination by heavy metals is occurring in conjunction with rising atmospheric CO 2 in natural ecosystems due to human activities. However, the response of GRSP to elevated CO 2 combined with heavy metal contamination has not been widely reported. Here, we investigated the response of GRSP to elevated CO 2 in the rhizosphere of Robinia pseudoacacia L. seedlings in Pb- and Cd-contaminated soils. Elevated CO 2 (700 μmol mol -1 ) significantly increased T- and EE- GRSP concentrations in soils contaminated with Cd, Pb or Cd + Pb. GRSP contributed more carbon to the rhizosphere soil organic carbon pool under elevated CO 2  + heavy metals than under ambient CO 2 . The amount of Cd and Pb bound to GRSP was significantly higher under elevated (compared to ambient) CO 2 ; and elevated CO 2 increased the ratio of GRSP-bound Cd and Pb to total Cd and Pb. However, available Cd and Pb in rhizosphere soil under increased elevated CO 2 compared to ambient CO 2 . The combination of both metals and elevated CO 2 led to a significant increase in available Pb in rhizosphere soil compared to the Pb treatment alone. In conclusion, increased GRSP produced under elevated CO 2 could contribute to sequestration of soil pollutants by adsorption of Cd and Pb. Copyright © 2016 Elsevier Ltd. All rights reserved.

Modeling the 2012-2013 lava flows of Tolbachik, Russia using thermal infrared satellite data and PyFLOWGO

NASA Astrophysics Data System (ADS)

Ramsey, M. S.; Chevrel, O.; Harris, A. J. L.

2017-12-01

Satellite-based thermal infrared (TIR) observations of new volcanic activity and ongoing lava flow emplacement become increasingly more detailed with improved spatial, spectral and/or temporal resolution data. The cooling of the glassy surface is directly imaged by TIR instruments in order to determine temperature, which is then used to initiate thermo-rheological-based models. Higher temporal resolution data (i.e., minutes to hours), are used to detect new eruptions and determine the time-averaged discharge rate (TADR). Calculation of the TADR along with new observations later in time and accurate digital elevation models (DEMs) enable modeling of the advancing flow's down-slope inundation area. Better spectral and spatial resolution data, on the other hand, allow the flow's composition, small-scale morphological changes and real-time DEMs to be determined, in addition to confirming prior model predictions. Combined, these data help improve the accuracy of models such as FLOWGO. A new adaptation of this model in python (PyFLOWGO) has been used to produce the best fit eruptive conditions to the final flow morphology for the 2012-2013 eruption of Tolbachik volcano, Russia. This was the largest and most thermally-intense flow-forming eruption in the past 50 years, producing longer lava flows than that of typical Kilauea or Etna eruptions. The progress of these flows were imaged by a multiple TIR sensors at various spatial, spectral and temporal scales throughout the flow field emplacement. We have refined the model based on the high resolution data to determine the TADR and make improved estimates of cooling, viscosity, velocity and crystallinity with distance. Understanding the cooling and dynamics of basaltic surfaces ultimately produces an improved hazard forecast capability. In addition, the direct connection of the final flow morphology to the specific eruption conditions that produced it allows the eruptive conditions of older flows to be estimated.

Antarctic surface elevation and slope from multi-mission lidar mapping

NASA Astrophysics Data System (ADS)

Sutterley, T. C.; Velicogna, I.; Neumann, T.; Markus, T.

2017-12-01

We present integrated estimates of surface elevation change and slope for the Antarctic Ice Sheet from a combination of measurements from the Airborne Topographic Mapper (ATM), the Land, Vegetation and Ice Sensor (LVIS) and the Ice Cloud and land Elevation Satellite (ICESat-1). This technique is a data-driven approach that calculates elevation differentials on a shot-by-shot basis. Our method extends the records of each instrument, increases the overall spatial coverage compared to a single instrument and produces high-quality, integrated maps of surface elevation, surface elevation change and slope. We use our estimates of elevation change to assess the current state of major outlet glaciers in the Bellinghausen Sea, Amundsen Sea and Getz regions of West Antarctica (WAIS). In the Amundsen Sea, we find that thinning rates of Pine Island Glacier have decreased after 2011 while thinning rates of Smith and Kohler glaciers have increased unabated.

Modeling tidal marsh distribution with sea-level rise: evaluating the role of vegetation, sediment, and upland habitat in marsh resiliency.

PubMed

Schile, Lisa M; Callaway, John C; Morris, James T; Stralberg, Diana; Parker, V Thomas; Kelly, Maggi

2014-01-01

Tidal marshes maintain elevation relative to sea level through accumulation of mineral and organic matter, yet this dynamic accumulation feedback mechanism has not been modeled widely in the context of accelerated sea-level rise. Uncertainties exist about tidal marsh resiliency to accelerated sea-level rise, reduced sediment supply, reduced plant productivity under increased inundation, and limited upland habitat for marsh migration. We examined marsh resiliency under these uncertainties using the Marsh Equilibrium Model, a mechanistic, elevation-based soil cohort model, using a rich data set of plant productivity and physical properties from sites across the estuarine salinity gradient. Four tidal marshes were chosen along this gradient: two islands and two with adjacent uplands. Varying century sea-level rise (52, 100, 165, 180 cm) and suspended sediment concentrations (100%, 50%, and 25% of current concentrations), we simulated marsh accretion across vegetated elevations for 100 years, applying the results to high spatial resolution digital elevation models to quantify potential changes in marsh distributions. At low rates of sea-level rise and mid-high sediment concentrations, all marshes maintained vegetated elevations indicative of mid/high marsh habitat. With century sea-level rise at 100 and 165 cm, marshes shifted to low marsh elevations; mid/high marsh elevations were found only in former uplands. At the highest century sea-level rise and lowest sediment concentrations, the island marshes became dominated by mudflat elevations. Under the same sediment concentrations, low salinity brackish marshes containing highly productive vegetation had slower elevation loss compared to more saline sites with lower productivity. A similar trend was documented when comparing against a marsh accretion model that did not model vegetation feedbacks. Elevation predictions using the Marsh Equilibrium Model highlight the importance of including vegetation responses to sea-level rise. These results also emphasize the importance of adjacent uplands for long-term marsh survival and incorporating such areas in conservation planning efforts.

Method of making permanent magnets

DOEpatents

McCallum, R.W.; Dennis, K.W.; Lograsso, B.K.; Anderson, I.E.

1993-09-07

A method for making an isotropic permanent magnet comprises atomizing a melt of a rare earth-transition metal alloy (e.g., an Nd--Fe--B alloy enriched in Nd and B) under conditions to produce protectively coated, rapidly solidified, generally spherical alloy particles. Wherein a majority of the particles are produced/size classified within a given size fraction (e.g., 5 to 40 microns diameter) exhibiting optimum as-atomized magnetic properties and subjecting the particles to concurrent elevated temperature and elevated isotropic pressure for a time effective to yield a densified, magnetically isotropic magnet compact having enhanced magnetic properties and mechanical properties. 13 figures.

Method of making permanent magnets

DOEpatents

McCallum, R. William; Dennis, Kevin W.; Lograsso, Barbara K.; Anderson, Iver E.

1993-09-07

A method for making an isotropic permanent magnet comprises atomizing a melt of a rare earth-transition metal alloy (e.g., an Nd--Fe--B alloy enriched in Nd and B) under conditions to produce protectively coated, rapidly solidified, generally spherical alloy particles wherein a majority of the particles are produced/size classified within a given size fraction (e.g., 5 to 40 microns diameter) exhibiting optimum as-atomized magnetic properties and subjecting the particles to concurrent elevated temperature and elevated isotropic pressure for a time effective to yield a densified, magnetically isotropic magnet compact having enhanced magnetic properties and mechanical properties.

Improving stability of regional numerical ocean models

NASA Astrophysics Data System (ADS)

Herzfeld, Mike

2009-02-01

An operational limited-area ocean modelling system was developed to supply forecasts of ocean state out to 3 days. This system is designed to allow non-specialist users to locate the model domain anywhere within the Australasian region with minimum user input. The model is required to produce a stable simulation every time it is invoked. This paper outlines the methodology used to ensure the model remains stable over the wide range of circumstances it might encounter. Central to the model configuration is an alternative approach to implementing open boundary conditions in a one-way nesting environment. Approximately 170 simulations were performed on limited areas in the Australasian region to assess the model stability; of these, 130 ran successfully with a static model parameterisation allowing a statistical estimate of the model’s approach toward instability to be determined. Based on this, when the model was deemed to be approaching instability a strategy of adaptive intervention in the form of constraint on velocity and elevation was invoked to maintain stability.

High-resolution Monthly Satellite Precipitation Product over the Conterminous United States

NASA Astrophysics Data System (ADS)

Hashemi, H.; Fayne, J.; Knight, R. J.; Lakshmi, V.

2017-12-01

We present a data set that enhanced the Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA) monthly product 3B43 in its accuracy and spatial resolution. For this, we developed a correction function to improve the accuracy of TRMM 3B43, spatial resolution of 25 km, by estimating and removing the bias in the satellite data using a ground-based precipitation data set. We observed a strong relationship between the bias and land surface elevation; TRMM 3B43 tends to underestimate the ground-based product at elevations above 1500 m above mean sea level (m.amsl) over the conterminous United States. A relationship was developed between satellite bias and elevation. We then resampled TRMM 3B43 to the Digital Elevation Model (DEM) data set at a spatial resolution of 30 arc second ( 1 km on the ground). The produced high-resolution satellite-based data set was corrected using the developed correction function based on the bias-elevation relationship. Assuming that each rain gauge represents an area of 1 km2, we verified our product against 9,200 rain gauges across the conterminous United States. The new product was compared with the gauges, which have 50, 60, 70, 80, 90, and 100% temporal coverage within the TRMM period of 1998 to 2015. Comparisons between the high-resolution corrected satellite-based data and gauges showed an excellent agreement. The new product captured more detail in the changes in precipitation over the mountainous region than the original TRMM 3B43.

CESM-simulated 21st Century Changes in Large Scale Crop Water Requirements and Yields

NASA Astrophysics Data System (ADS)

Levis, S.; Badger, A.; Drewniak, B. A.; O'Neill, B. C.; Ren, X.

2014-12-01

We assess potential changes in crop water requirements and corresponding yields relative to the late 20th century in major crop producing regions of the world by using the Community Land Model (CLM) driven with 21st century meteorology from RCP8.5 and RCP4.5 Community Earth System Model (CESM) simulations. The RCP4.5 simulation allows us to explore the potential for averted societal impacts when compared to the RCP8.5 simulation. We consider the possibility for increased yields and improved water use efficiency under conditions of elevated atmospheric CO2 due to the CO2 fertilization effect (also known as concentration-carbon feedback). We address uncertainty in the current understanding of plant CO2 fertilization by repeating the simulations with and without the CO2 fertilization effect. Simulations without CO2 fertilization represent the radiative effect of elevated CO2 (i.e., warming) without representing the physiological effect of elevated CO2 (enhanced carbon uptake and increased water use efficiency by plants during photosynthesis). Preliminary results suggest that some plants may suffer from increasing heat and drought in much of the world without the CO2 fertilization effect. On the other hand plants (especially C3) tend to grow more with less water when models include the CO2 fertilization effect. Performing 21st century simulations with and without the CO2 fertilization effect brackets the potential range of outcomes. In this work we use the CLM crop model, which includes specific crop types that differ from the model's default plant functional types in that the crops get planted, harvested, and potentially fertilized and irrigated according to algorithms that attempt to capture human management decisions. We use an updated version of the CLM4.5 that includes cotton, rice, and sugarcane, spring wheat, spring barley, and spring rye, as well as temperate and tropical maize and soybean.

TopoSCALE v.1.0: downscaling gridded climate data in complex terrain

NASA Astrophysics Data System (ADS)

Fiddes, J.; Gruber, S.

2014-02-01

Simulation of land surface processes is problematic in heterogeneous terrain due to the the high resolution required of model grids to capture strong lateral variability caused by, for example, topography, and the lack of accurate meteorological forcing data at the site or scale it is required. Gridded data products produced by atmospheric models can fill this gap, however, often not at an appropriate spatial resolution to drive land-surface simulations. In this study we describe a method that uses the well-resolved description of the atmospheric column provided by climate models, together with high-resolution digital elevation models (DEMs), to downscale coarse-grid climate variables to a fine-scale subgrid. The main aim of this approach is to provide high-resolution driving data for a land-surface model (LSM). The method makes use of an interpolation of pressure-level data according to topographic height of the subgrid. An elevation and topography correction is used to downscale short-wave radiation. Long-wave radiation is downscaled by deriving a cloud-component of all-sky emissivity at grid level and using downscaled temperature and relative humidity fields to describe variability with elevation. Precipitation is downscaled with a simple non-linear lapse and optionally disaggregated using a climatology approach. We test the method in comparison with unscaled grid-level data and a set of reference methods, against a large evaluation dataset (up to 210 stations per variable) in the Swiss Alps. We demonstrate that the method can be used to derive meteorological inputs in complex terrain, with most significant improvements (with respect to reference methods) seen in variables derived from pressure levels: air temperature, relative humidity, wind speed and incoming long-wave radiation. This method may be of use in improving inputs to numerical simulations in heterogeneous and/or remote terrain, especially when statistical methods are not possible, due to lack of observations (i.e. remote areas or future periods).

Analysis of floods, including the tropical storm Irene inundation, of the Ottauquechee River in Woodstock, Bridgewater, and Killington and of Reservoir Brook in Bridgewater and Plymouth, Vermont

USGS Publications Warehouse

Flynn, Robert H.

2014-01-01

In addition to the two digital flood inundation maps, flood profiles were created that depict the study reach flood elevation of tropical storm Irene of August 2011 and the 10-, 2-, 1-, and 0.2-percent AEP floods, also known as the 10-, 50-, 100-, and 500-year floods, respectively. The 10-, 2-, 1-, and 0.2-percent AEP flood discharges were determined using annual peak flow data from the USGS Ottauquechee River near West Bridgewater, Vt. streamgage (station 01150900). Flood profiles were computed for the Ottauquechee River and Reservoir Brook by means of a one-dimensional step-backwater model. The model was calibrated using documented high-water marks of the peak of the tropical storm Irene flood of August 2011 as well as stage discharge data as determined for USGS Ottauquechee River near West Bridgewater, Vt. streamgage (station 01150900). The simulated water-surface profiles were combined with a digital elevation model within a geographic information system to delineate the areas flooded during tropical storm Irene and for the 1-percent AEP water-surface profile. The digital elevation model data were derived from light detection and ranging (lidar) data obtained for a 3,281-foot (1,000-meter) corridor along the Ottauquechee River study reach and were augmented with 33-foot (10- meter) contour interval data in the modeled flood-inundation areas outside the lidar corridor. The 33-foot (10-meter) contour interval USGS 15-minute quadrangle topographic digital raster graphics map used to augment lidar data was produced at a scale of 1:24,000. The digital flood inundation maps and flood profiles along with information regarding current stage from USGS streamgages on the Internet provide emergency management personnel and residents with information that is critical for flood response activities, such as evacuations and road closures, as well as for post-flood recovery efforts.

Categorical likelihood method for combining NDVI and elevation information for cotton precision agricultural applications

USDA-ARS?s Scientific Manuscript database

This presentation investigates an algorithm to fuse the Normalized Difference Vegetation Index (NDVI) with LiDAR elevation data to produce a map useful for the site-specific scouting and pest management (Willers et al. 1999; 2005; 2009) of the cotton insect pests, the tarnished plant bug (Lygus lin...

Integrating Biodiversity into Biosphere-Atmosphere Interactions Using Individual-Based Models (IBM)

NASA Astrophysics Data System (ADS)

Wang, B.; Shugart, H. H., Jr.; Lerdau, M.

2017-12-01

A key component regulating complex, nonlinear, and dynamic biosphere-atmosphere interactions is the inherent diversity of biological systems. The model frameworks currently widely used, i.e., Plant Functional Type models) do not even begin to capture the metabolic and taxonomic diversity found in many terrestrial systems. We propose that a transition from PFT-based to individual-based modeling approaches (hereafter referred to as IBM) is essential for integrating biodiversity into research on biosphere-atmosphere interactions. The proposal emerges from our studying the interactions of forests with atmospheric processes in the context of climate change using an individual-based forest volatile organic compounds model, UVAFME-VOC. This individual-based model can explicitly simulate VOC emissions based on an explicit modelling of forest dynamics by computing the growth, death, and regeneration of each individual tree of different species and their competition for light, moisture, and nutrient, from which system-level VOC emissions are simulated by explicitly computing and summing up each individual's emissions. We found that elevated O3 significantly altered the forest dynamics by favoring species that are O3-resistant, which, meanwhile, are producers of isoprene. Such compositional changes, on the one hand, resulted in unsuppressed forest productivity and carbon stock because of the compensation by O3-resistant species. On the other hand, with more isoprene produced arising from increased producers, a possible positive feedback loop between tropospheric O3 and forest thereby emerged. We also found that climate warming will not always stimulate isoprene emissions because warming simultaneously reduces isoprene emissions by causing a decline in the abundance of isoprene-emitting species. These results suggest that species diversity is of great significance and that individual-based modelling strategies should be applied in studying biosphere-atmosphere interactions.

Understanding Biogenic and Anthropogenic Trace Gas Variations Measured Near Cool, CA in June 2010

NASA Astrophysics Data System (ADS)

Klein, B. Z.; Flowers, B. A.; Gorkowski, K.; Dubey, M. K.; Knighton, W. B.; Floerchinger, C.; Herndon, S. C.; Fast, J. D.; Zaveri, R. A.

2011-12-01

Trace gas signatures produced by forested and urban areas differ greatly. Forested areas are dominated by gases produced during photosynthesis and respiration: CO2 and volatile organic compounds (VOCs) including terpenes and isoprene. Urban areas are heavily influenced by vehicle exhaust emissions and have elevated levels of CO, NOx and aromatic hydrocarbons such as benzene. Ozone is produced as a byproduct of both of these sources; it is produced when NOx from urban areas reacts with either anthropogenic or biogenic hydrocarbons. The Carbonaceous Aerosol and Radiative Effects Study (CARES) campaign was conducted during June 2010, in part to observe the evolution of urban air masses as they mix into rural locations and to better understand anthropogenic-biogenic photochemical interactions. The campaign included two ground-based sampling sites, one in Sacramento, CA (T0) and one downwind, approximately 70km NE, rurally located near Cool, CA (T1). In situ measurements of CO2, CO, O3, NO and multiple different VOCs were performed at the T1 site during the study, and are analyzed here to gain insights into the chemistry and transport of these trace gases. Comparisons between these trace gases coupled with transport modeling is used to delineate biogenic and anthropogenic sources. Additionally, comparisons between trace gases produced predominately by biogenic sources provide valuable information on how meteorology affects their production. Two atmospheric models (HYSPLIT back-trajectories and WRF forecasts) are used to predict transport episodes, where polluted air masses from the Sacramento or more distant San Francisco areas are transported to Cool. The two models display significant overlap for eleven different transport episodes during the study period. Both models also agree on two transport-free multiple-day periods. By examining the periods during which the models are in agreement, we are able to characterize with high certainty the trace gas signatures of local biogenic sources and also the significance of short-range transported anthropogenic trace gases.

Discharges of produced waters from oil and gas extraction via wastewater treatment plants are sources of disinfection by-products to receiving streams

USGS Publications Warehouse

Hladik, Michelle; Focazio, Michael J.; Engle, Mark

2014-01-01

Fluids co-produced with oil and gas production (produced waters) are often brines that contain elevated concentrations of bromide. Bromide is an important precursor of several toxic disinfection by-products (DBPs) and the treatment of produced water may lead to more brominated DBPs. To determine if wastewater treatment plants that accept produced waters discharge greater amounts of brominated DBPs, water samples were collected in Pennsylvania from four sites along a large river including an upstream site, a site below a publicly owned wastewater treatment plant (POTW) outfall (does not accept produced water), a site below an oil and gas commercial wastewater treatment plant (CWT) outfall, and downstream of the POTW and CWT. Of 29 DBPs analyzed, the site at the POTW outfall had the highest number detected (six) ranging in concentration from 0.01 to 0.09 μg L− 1 with a similar mixture of DBPs that have been detected at POTW outfalls elsewhere in the United States. The DBP profile at the CWT outfall was much different, although only two DBPs, dibromochloronitromethane (DBCNM) and chloroform, were detected, DBCNM was found at relatively high concentrations (up to 8.5 μg L− 1). The water at the CWT outfall also had a mixture of inorganic and organic precursors including elevated concentrations of bromide (75 mg L− 1) and other organic DBP precursors (phenol at 15 μg L− 1). To corroborate these DBP results, samples were collected in Pennsylvania from additional POTW and CWT outfalls that accept produced waters. The additional CWT also had high concentrations of DBCNM (3.1 μg L− 1) while the POTWs that accept produced waters had elevated numbers (up to 15) and concentrations of DBPs, especially brominated and iodinated THMs (up to 12 μg L− 1 total THM concentration). Therefore, produced water brines that have been disinfected are potential sources of DBPs along with DBP precursors to streams wherever these wastewaters are discharged.

[The expression of p53, MDM2 and Ref1 gene in cultured retina neurons of SD rats treated with vitamin B1 and/or elevated pressure].

PubMed

Yang, Zhikuan; Ge, Jian; Yin, Wei; Shen, Huangxuan; Liu, Haiquan; Guo, Yan

2004-12-01

To investigate the expression of p53, MDM2 and Ref1 gene in cultured retina neurons of SD rats treated with Vitamin B1 and (or) elevated pressure. The retinal neuron of postnatal SD rats were cultured in vivo, the elevated pressure was produced after 7 days, and the total RNA was extracted after another 2 days, expression of p53, MDM2 and Ref1 gene were analyzed with RT-PCR. The expression level of p53 and MDM2 gene were increased in elevated pressure group, normal with Ref1 gene expression. But the expression of p53 and MDM2 gene were decreased significantly in elevated pressure group treated with vitamine B1 compare to the elevated group. Apoptosis seem to be a mechanism of cell death in retinal neurons of SD rats with elevated pressure.Vitamine B1 have protect effects against elevated pressure.

Basin-Wide Amazon Forest Tree Mortality From a Large 2005 Storm

NASA Astrophysics Data System (ADS)

Negron Juarez, R. I.; Chambers, J. Q.; Guimaraes, G.; Zeng, H.; Raupp, C.; Marra, D. M.; Ribeiro, G.; Saatchi, S. S.; Higuchi, N.

2010-12-01

Blowdowns are a recurrent characteristic of Amazon forests and are produced, among others, by squall lines. Squall lines are aligned clusters (typical length of 1000 km, width of 200 km) of deep convective cells that produce heavy rainfall during the dry season and significant rainfall during the wet season. These squall lines (accompanied by intense downbursts from convective cells) have been associated with large blowdowns characterized by uprooted, snapped trees, and trees being dragged down by other falling trees. Most squall lines in Amazonia form along the northeastern coast of South America as sea breeze-induced instability lines and propagate inside the continent. They occur frequently (~4 times per month), and can reach the central and even extreme western parts of Amazonia. Squall lines can also be generated inside the Amazon and propagate toward the equator. In January 2005 a squall line propagated from south to north across the entire Amazon basin producing widespread forest tree mortality and contributed to the elevated mortality observed that year. Over the Manaus region (3.4 x104 km2), disturbed forest patches generated by the squall produced a mortality of 0.3-0.5 million trees, equivalent to 30% of the observed annual deforestation reported in 2005 over the same area. The elevated mortality observed in the Central Amazon in 2005 is unlikely to be related to the 2005 Amazon drought since drought did not affect Central or Eastern Amazonia. Assuming a similar rate of forest mortality across the basin, the squall line could have potentially produced tree mortality estimated at 542 ± 121 million trees, equivalent to 23% of the mean annual biomass accumulation estimated for these forests. Our results highlight the vulnerability of Amazon trees to wind-driven mortality associated with convective storms. This vulnerability is likely to increase in a warming climate with models projecting an increase in storm intensity.

Examining the intersection of sex and stress in modelling neuropsychiatric disorders.

PubMed

Goel, N; Bale, T L

2009-03-01

Sex-biased neuropsychiatric disorders, including major depressive disorder and schizophrenia, are the major cause of disability in the developed world. Elevated stress sensitivity has been proposed as a key underlying factor in disease onset. Sex differences in stress sensitivity are associated with corticotrophin-releasing factor (CRF) and serotonin neurotransmission, which are important central regulators of mood and coping responses. To elucidate the underlying neurobiology of stress-related disease predisposition, it is critical to develop appropriate animal models of stress pathway dysregulation. Furthermore, the inclusion of sex difference comparisons in stress responsive behaviours, physiology and central stress pathway maturation in these models is essential. Recent studies by our laboratory and others have begun to investigate the intersection of stress and sex where the development of mouse models of stress pathway dysregulation via prenatal stress experience or early-life manipulations has provided insight into points of developmental vulnerability. In addition, examination of the maturation of these pathways, including the functional importance of the organisational and activational effects of gonadal hormones on stress responsivity, is essential for determination of when sex differences in stress sensitivity may begin. In such studies, we have detected distinct sex differences in stress coping strategies where activational effects of testosterone produced females that displayed male-like strategies in tests of passive coping, but were similar to females in tests of active coping. In a second model of elevated stress sensitivity, male mice experiencing prenatal stress early in gestation showed feminised physiological and behavioural stress responses, and were highly sensitive to a low dose of selective serotonin reuptake inhibitors. Analyses of expression and epigenetic patterns revealed changes in CRF and glucocorticoid receptor genes in these mice. Mechanistically, stress early in pregnancy produced a significant sex-dependent effect on placental gene expression that was supportive of altered foetal transport of key growth factors and nutrients. These mouse models examining alterations and hormonal effects on development of stress pathways provide necessary insight into how specific stress responses can be reprogrammed early in development resulting in sex differences in stress sensitivity and neuropsychiatric disease vulnerability.

Examining the intersection of sex and stress in modeling neuropsychiatric disorders

PubMed Central

Goel, Nirupa; Bale, Tracy L.

2009-01-01

Sex-biased neuropsychiatric disorders, including major depressive disorder and schizophrenia, are the major cause of disability in the developed world. Elevated stress sensitivity has been proposed as a key underlying factor in disease onset. Sex differences in stress sensitivity are associated with CRF and serotonin neurotransmission, important central regulators of mood and coping responses. To elucidate the underlying neurobiology of stress-related disease predisposition, it is critical to develop appropriate animal models of stress pathway dysregulation. Further, the inclusion of sex difference comparisons in stress responsive behaviors, physiology, and central stress pathway maturation in these models is essential. Recent studies by our lab and others have begun to investigate the intersection of stress and sex where the development of mouse models of stress pathway dysregulation via prenatal stress experience or early life manipulations has provided insight into points of developmental vulnerability. In addition, examination of the maturation of these pathways including the functional importance of the organizational and activational effects of gonadal hormones on stress responsivity is essential for determination of when sex differences in stress sensitivity may begin. In such studies, we have detected distinct sex differences in stress coping strategies where activational effects of testosterone produced females that displayed male-like strategies in tests of passive coping, but were similar to females in tests of active coping. In a second model of elevated stress sensitivity, male mice experiencing prenatal stress early in gestation showed feminized physiological and behavioral stress responses, and were highly sensitive to a low dose of SSRI. Analyses of expression and epigenetic patterns revealed changes in CRF and glucocorticoid receptor genes in these mice. Mechanistically, stress early in pregnancy produced a significant sex-dependent effect on placental gene expression supportive of altered fetal transport of key growth factors and nutrients. These mouse models examining alterations and hormonal effects on development of stress pathways provide necessary insight into how specific stress responses can be reprogrammed early in development resulting in sex differences in stress sensitivity and neuropsychiatric disease vulnerability. PMID:19187468

Topogrid Derived 10 Meter Resolution Digital Elevation Model of Charleston, and Parts of Berkeley, Colleton, Dorchester and Georgetown Counties, South Carolina

USGS Publications Warehouse

Chirico, Peter G.

2005-01-01

EXPLANATION The purpose of developing a new 10m resolution digital elevation model (DEM) of the Charleston Region was to more accurately depict geologic structure, surfical geology, and landforms of the Charleston County Region. Previously, many areas northeast and southwest of Charleston were originally mapped with a 20 foot contour interval. As a result, large areas within the National Elevation Dataset (NED) depict flat terraced topography where there was a lack of higher resolution elevation data. To overcome these data voids, the new DEM is supplemented with additional elevation data and break-lines derived from aerial photography and topographic maps. The resultant DEM is stored as a raster grid at uniform 10m horizontal resolution. The elevation model contained in this publication was prodcued utilizing the ANUDEM algorthim. ANUDEM allows for the inclusion of contours, streams, rivers, lake and water body polygons as well as spot height data to control the development of the elevation model. A preliminary statistical analysis using over 788 vertical elevation check points, primarily located in the northeastern part of the study area, derived from USGS 7.5 Minute Topographic maps reveals that the final DEM, has a vertical accuracy of ?3.27 meters. A table listing the elevation comparison between the elevation check points and the final DEM is provided.

The orexin-1 receptor antagonist SB-334867 attenuates anxiety in rats exposed to cat odor but not the elevated plus maze: an investigation of Trial 1 and Trial 2 effects.

PubMed

Staples, Lauren G; Cornish, Jennifer L

2014-03-01

The orexins are hypothalamic neuropeptides most well known for their roles in regulating feeding and sleeping behaviors. Recent findings suggest that orexin-A may also modulate anxiety, although how and when the orexin system is involved remains unclear. To address this, we investigated the dose-dependent effects of the orexin-1 receptor antagonist SB-334867 in two rodent models of anxiety: the cat odor avoidance model and the elevated plus maze. In both models we tested the effects of SB-334867 when anxiety is novel (Trial 1) and familiar (Trial 2). In the first experiment, Wistar rats were treated with vehicle or SB-334867 (5, 10 or 20mg/kg, i.p.) prior to their first or second exposure to cat odor. During Trial 1, rats treated with 10mg/kg of SB-334867 approached the cat odor stimulus more than vehicle-treated rats. During Trial 2 the effects were more marked, with 10mg/kg of SB-334867 increasing approach times, increasing the number of times rats exited the hide box to engage in exploratory behavior, and decreasing overall hide times. In addition, the 20mg/kg dose decreased general activity during Trial 2. In the second experiment, the effects of SB-334867 (10 and 20mg/kg) were tested in the elevated plus maze. There were no significant differences produced by drug treatment during either Trial 1 or Trial 2. Results suggest that SB-334867 decreases anxiety induced by some, but not all, stressors. Crown Copyright © 2014. Published by Elsevier Inc. All rights reserved.

Plants Regulate Soil Organic Matter Decomposition in Response to Sea Level Rise

NASA Astrophysics Data System (ADS)

Megonigal, P.; Mueller, P.; Jensen, K.

2014-12-01

Tidal wetlands have a large capacity for producing and storing organic matter, making their role in the global carbon budget disproportionate to their land area. Most of the organic matter stored in these systems is in soils where it contributes 2-5 times more to surface accretion than an equal mass of minerals. Soil organic matter (SOM) sequestration is the primary process by which tidal wetlands become perched high in the tidal frame, decreasing their vulnerability to accelerated sea level rise. Plant growth responses to sea level rise are well understood and represented in century-scale forecast models of soil surface elevation change. We understand far less about the response of soil organic matter decomposition to rapid sea level rise. Here we quantified the effects of sea level on SOM decomposition rates by exposing planted and unplanted tidal marsh monoliths to experimentally manipulated flood duration. The study was performed in a field-based mesocosm facility at the Smithsonian's Global Change Research Wetland. SOM decomposition rate was quantified as CO2 efflux, with plant- and SOM-derived CO2 separated with a two end-member δ13C-CO2 model. Despite the dogma that decomposition rates are inversely related to flooding, SOM mineralization was not sensitive to flood duration over a 35 cm range in soil surface elevation. However, decomposition rates were strongly and positively related to aboveground biomass (R2≥0.59, p≤0.01). We conclude that soil carbon loss through decomposition is driven by plant responses to sea level in this intensively studied tidal marsh. If this result applies more generally to tidal wetlands, it has important implications for modeling soil organic matter and surface elevation change in response to accelerated sea level rise.

Modeled Seasonal Variations of Firn Density Induced by Steady State Surface Air Temperature Cycle

NASA Technical Reports Server (NTRS)

Jun, Li; Zwally, H. Jay; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

Seasonal variations of firn density in ice-sheet firn layers have been attributed to variations in deposition processes or other processes within the upper firn. A recent high-resolution (mm scale) density profile, measured along a 181 m core from Antarctica, showed small-scale density variations with a clear seasonal cycle that apparently was not-related to seasonal variations in deposition or known near-surface processes (Gerland and others 1999). A recent model of surface elevation changes (Zwally and Li, submitted) produced a seasonal variation in firn densification, and explained the seasonal surface elevation changes observed by satellite radar altimeters. In this study, we apply our 1-D time-dependent numerical model of firn densification that includes a temperature-dependent formulation of firn densification based on laboratory measurements of grain growth. The model is driven by a steady-state seasonal surface temperature and a constant accumulation rate appropriate for the measured Antarctic ice core. The modeled seasonal variations in firn density show that the layers of snow deposited during spring to mid-summer with the highest temperature history compress to the highest density, and the layers deposited during later summer to autumn with the lowest temperature history compress to the lowest density. The initial amplitude of the seasonal difference of about 0.13 reduces to about 0.09 in five years and asymptotically to 0.92 at depth, which is consistent with the core measurements.

Tungsten-nickel-cobalt alloy and method of producing same

DOEpatents

Dickinson, James M.; Riley, Robert E.

1977-03-15

An improved tungsten alloy having a tungsten content of approximately 95 weight percent, a nickel content of about 3 weight percent, and the balance being cobalt of about 2 weight percent is described. A method for producing said tungsten-nickel-cobalt alloy is further described and comprises (a) coating the tungsten particles with a nickel-cobalt alloy, (b) pressing the coated particles into a compact shape, (c) heating said compact in hydrogen to a temperature in the range of 1400.degree. C and holding at this elevated temperature for a period of about 2 hours, (d) increasing this elevated temperature to about 1500.degree. C and holding for 1 hour at this temperature, (e) cooling to about 1200.degree. C and replacing the hydrogen atmosphere with an inert argon atmosphere while maintaining this elevated temperature for a period of about 1/2 hour, and (f) cooling the resulting alloy to room temperature in this argon atmosphere.

Advanced composite elevator for Boeing 727 aircraft, volume 2

NASA Technical Reports Server (NTRS)

Chovil, D. V.; Grant, W. D.; Jamison, E. S.; Syder, H.; Desper, O. E.; Harvey, S. T.; Mccarty, J. E.

1980-01-01

Preliminary design activity consisted of developing and analyzing alternate design concepts and selecting the optimum elevator configuration. This included trade studies in which durability, inspectability, producibility, repairability, and customer acceptance were evaluated. Preliminary development efforts consisted of evaluating and selecting material, identifying ancillary structural development test requirements, and defining full scale ground and flight test requirements necessary to obtain Federal Aviation Administration (FAA) certification. After selection of the optimum elevator configuration, detail design was begun and included basic configuration design improvements resulting from manufacturing verification hardware, the ancillary test program, weight analysis, and structural analysis. Detail and assembly tools were designed and fabricated to support a full-scope production program, rather than a limited run. The producibility development programs were used to verify tooling approaches, fabrication processes, and inspection methods for the production mode. Quality parts were readily fabricated and assembled with a minimum rejection rate, using prior inspection methods.

Impact of earthquake source complexity and land elevation data resolution on tsunami hazard assessment and fatality estimation

NASA Astrophysics Data System (ADS)

Muhammad, Ario; Goda, Katsuichiro

2018-03-01

This study investigates the impact of model complexity in source characterization and digital elevation model (DEM) resolution on the accuracy of tsunami hazard assessment and fatality estimation through a case study in Padang, Indonesia. Two types of earthquake source models, i.e. complex and uniform slip models, are adopted by considering three resolutions of DEMs, i.e. 150 m, 50 m, and 10 m. For each of the three grid resolutions, 300 complex source models are generated using new statistical prediction models of earthquake source parameters developed from extensive finite-fault models of past subduction earthquakes, whilst 100 uniform slip models are constructed with variable fault geometry without slip heterogeneity. The results highlight that significant changes to tsunami hazard and fatality estimates are observed with regard to earthquake source complexity and grid resolution. Coarse resolution (i.e. 150 m) leads to inaccurate tsunami hazard prediction and fatality estimation, whilst 50-m and 10-m resolutions produce similar results. However, velocity and momentum flux are sensitive to the grid resolution and hence, at least 10-m grid resolution needs to be implemented when considering flow-based parameters for tsunami hazard and risk assessments. In addition, the results indicate that the tsunami hazard parameters and fatality number are more sensitive to the complexity of earthquake source characterization than the grid resolution. Thus, the uniform models are not recommended for probabilistic tsunami hazard and risk assessments. Finally, the findings confirm that uncertainties of tsunami hazard level and fatality in terms of depth, velocity and momentum flux can be captured and visualized through the complex source modeling approach. From tsunami risk management perspectives, this indeed creates big data, which are useful for making effective and robust decisions.

An analysis of cropland mask choice and ancillary data for annual corn yield forecasting using MODIS data

NASA Astrophysics Data System (ADS)

Shao, Yang; Campbell, James B.; Taff, Gregory N.; Zheng, Baojuan

2015-06-01

The Midwestern United States is one of the world's most important corn-producing regions. Monitoring and forecasting of corn yields in this intensive agricultural region are important activities to support food security, commodity markets, bioenergy industries, and formation of national policies. This study aims to develop forecasting models that have the capability to provide mid-season prediction of county-level corn yields for the entire Midwestern United States. We used multi-temporal MODIS NDVI (normalized difference vegetation index) 16-day composite data as the primary input, with digital elevation model (DEM) and parameter-elevation relationships on independent slopes model (PRISM) climate data as additional inputs. The DEM and PRISM data, along with three types of cropland masks were tested and compared to evaluate their impacts on model predictive accuracy. Our results suggested that the use of general cropland masks (e.g., summer crop or cultivated crops) generated similar results compared with use of an annual corn-specific mask. Leave-one-year-out cross-validation resulted in an average R2 of 0.75 and RMSE value of 1.10 t/ha. Using a DEM as an additional model input slightly improved performance, while inclusion of PRISM climate data appeared not to be important for our regional corn-yield model. Furthermore, our model has potential for real-time/early prediction. Our corn yield esitmates are available as early as late July, which is an improvement upon previous corn-yield prediction models. In addition to annual corn yield forecasting, we examined model uncertainties through spatial and temporal analysis of the model's predictive error distribution. The magnitude of predictive error (by county) appears to be associated with the spatial patterns of corn fields in the study area.

75 FR 43395 - Airworthiness Directives; Aircraft Industries a.s. Model L 23 Super Blanik Gliders

Federal Register 2010, 2011, 2012, 2013, 2014

2010-07-26

... elevator in place and in jamming of the Pilot's elevator control system, and subsequent loss of elevator... elevator in place and in jamming of the Pilot's elevator control system, and subsequent loss of elevator... retaining the elevator in place and in jamming of the Pilot's elevator control system, and subsequent loss...

Relationship between ketamine-induced developmental neurotoxicity and NMDA receptor-mediated calcium influx in neural stem cell-derived neurons.

PubMed

Wang, Cheng; Liu, Fang; Patterson, Tucker A; Paule, Merle G; Slikker, William

2017-05-01

Ketamine, a noncompetitive NMDA receptor antagonist, is used as a general anesthetic and recent data suggest that general anesthetics can cause neuronal damage when exposure occurs during early brain development. To elucidate the underlying mechanisms associated with ketamine-induced neurotoxicity, stem cell-derived models, such as rodent neural stem cells harvested from rat fetuses and/or neural stem cells derived from human induced pluripotent stem cells (iPSC) can be utilized. Prolonged exposure of rodent neural stem cells to clinically-relevant concentrations of ketamine resulted in elevated NMDA receptor levels as indicated by NR1subunit over-expression in neurons. This was associated with enhanced damage in neurons. In contrast, the viability and proliferation rate of undifferentiated neural stem cells were not significantly affected after ketamine exposure. Calcium imaging data indicated that 50μM NMDA did not cause a significant influx of calcium in typical undifferentiated neural stem cells; however, it did produce an immediate elevation of intracellular free Ca 2+ [Ca 2+ ] i in differentiated neurons derived from the same neural stem cells. This paper reviews the literature on this subject and previous findings suggest that prolonged exposure of developing neurons to ketamine produces an increase in NMDA receptor expression (compensatory up-regulation) which allows for a higher/toxic influx of calcium into neurons once ketamine is removed from the system, leading to neuronal cell death likely due to elevated reactive oxygen species generation. The absence of functional NMDA receptors in cultured neural stem cells likely explains why clinically-relevant concentrations of ketamine did not affect undifferentiated neural stem cell viability. Published by Elsevier B.V.

Geospatial Analysis and Seasonal Distribution of West Nile Virus Vectors (Diptera: Culicidae) in Southern Ontario, Canada

PubMed Central

Turner, Kevin W.; Hunter, Fiona F.

2018-01-01

The purpose of this study was to establish geospatial and seasonal distributions of West Nile virus vectors in southern Ontario, Canada using historical surveillance data from 2002 to 2014. We set out to produce mosquito abundance prediction surfaces for each of Ontario’s thirteen West Nile virus vectors. We also set out to determine whether elevation and proximity to conservation areas and provincial parks, wetlands, and population centres could be used to improve our model. Our results indicated that the data sets for Anopheles quadrimaculatus, Anopheles punctipennis, Anopheles walkeri, Culex salinarius, Culex tarsalis, Ochlerotatus stimulans, and Ochlerotatus triseriatus were not suitable for geospatial modelling because they are randomly distributed throughout Ontario. Spatial prediction surfaces were created for Aedes japonicus and proximity to wetlands, Aedes vexans and proximity to population centres, Culex pipiens/restuans and proximity to population centres, Ochlerotatus canadensis and elevation, and Ochlerotatus trivittatus and proximity to population centres using kriging. Seasonal distributions are presented for all thirteen species. We have identified both when and where vector species are most abundant in southern Ontario. These data have the potential to contribute to a more efficient and focused larvicide program and West Nile virus awareness campaigns. PMID:29597256

Topography and Landforms of Ecuador

USGS Publications Warehouse

Chirico, Peter G.; Warner, Michael B.

2005-01-01

EXPLANATION The digital elevation model of Ecuador represented in this data set was produced from over 40 individual tiles of elevation data from the Shuttle Radar Topography Mission (SRTM). Each tile was downloaded, converted from its native Height file format (.hgt), and imported into a geographic information system (GIS) for additional processing. Processing of the data included data gap filling, mosaicking, and re-projection of the tiles to form one single seamless digital elevation model. For 11 days in February of 2000, NASA, the National Geospatial-Intelligence Agency (NGA), the German Aerospace Center (DLR), and the Italian Space Agency (ASI) flew X-band and C-band radar interferometry onboard the Space Shuttle Endeavor. The mission covered the Earth between 60?N and 57?S and will provide interferometric digital elevation models (DEMs) of approximately 80% of the Earth's land mass when processing is complete. The radar-pointing angle was approximately 55? at scene center. Ascending and descending orbital passes generated multiple interferometric data scenes for nearly all areas. Up to eight passes of data were merged to form the final processed SRTM DEMs. The effect of merging scenes averages elevation values recorded in coincident scenes and reduces, but does not completely eliminate, the amount of area with layover and terrain shadow effects. The most significant form of data processing for the Ecuador DEM was gap-filling areas where the SRTM data contained a data void. These void areas are a result of radar shadow, layover, standing water, and other effects of terrain, as well as technical radar interferometry phase unwrapping issues. To fill these gaps, topographic contours were digitized from 1:50,000 - scale topographic maps which date from the mid-late 1980's (Souris, 2001). Digital contours were gridded to form elevation models for void areas and subsequently were merged with the SRTM data through GIS and remote sensing image-processing techniques. The data contained in this publication includes a gap filled, countrywide SRTM DEM of Ecuador projected in Universal Transverse Mercator (UTM) Zone 17 North projection, Provisional South American, 1956, Ecuador datum and a non gap filled SRTM DEM of the Galapagos Islands projected in UTM Zone 15 North projection. Both the Ecuador and Galapagos Islands DEMs are available as an ESRI Grid, stored as ArcInfo Export files (.e00), and in Erdas Imagine (IMG) file formats with a 90 meter pixel resolution. Also included in this publication are high and low resolution Adobe Acrobat (PDF) files of topography and landforms maps in Ecuador. The high resolution map should be used for printing and display, while the lower resolution map can be used for quick viewing and reference purposes.

Development and evaluation of a reservoir model for the Chain of Lakes in Illinois

USGS Publications Warehouse

Domanski, Marian M.

2017-01-27

Forecasts of flows entering and leaving the Chain of Lakes reservoir on the Fox River in northeastern Illinois are critical information to water-resource managers who determine the optimal operation of the dam at McHenry, Illinois, to help minimize damages to property and loss of life because of flooding on the Fox River. In 2014, the U.S. Geological Survey; the Illinois Department of Natural Resources, Office of Water Resources; and National Weather Service, North Central River Forecast Center began a cooperative study to develop a system to enable engineers and planners to simulate and communicate flows and to prepare proactively for precipitation events in near real time in the upper Fox River watershed. The purpose of this report is to document the development and evaluation of the Chain of Lakes reservoir model developed in this study.The reservoir model for the Chain of Lakes was developed using the Hydrologic Engineering Center–Reservoir System Simulation program. Because of the complex relation between the dam headwater and reservoir pool elevations, the reservoir model uses a linear regression model that relates dam headwater elevation to reservoir pool elevation. The linear regression model was developed using 17 U.S. Geological Survey streamflow measurements, along with the gage height in the reservoir pool and the gage height at the dam headwater. The Nash-Sutcliffe model efficiency coefficients for all three linear regression model variables ranged from 0.90 to 0.98.The reservoir model performance was evaluated by graphically comparing simulated and observed reservoir pool elevation time series during nine periods of high pool elevation. In addition, the peak elevations during these time periods were graphically compared to the closest-in-time observed pool elevation peak. The mean difference in the simulated and observed peak elevations was -0.03 feet, with a standard deviation of 0.19 feet. The Nash-Sutcliffe coefficient for peak prediction was calculated as 0.94. Evaluation of the model based on accuracy of peak prediction and the ability to simulate an elevation time series showed the performance of the model was satisfactory.

Evaluation Digital Elevation Model Generated by Synthetic Aperture Radar Data

NASA Astrophysics Data System (ADS)

Makineci, H. B.; Karabörk, H.

2016-06-01

Digital elevation model, showing the physical and topographical situation of the earth, is defined a tree-dimensional digital model obtained from the elevation of the surface by using of selected an appropriate interpolation method. DEMs are used in many areas such as management of natural resources, engineering and infrastructure projects, disaster and risk analysis, archaeology, security, aviation, forestry, energy, topographic mapping, landslide and flood analysis, Geographic Information Systems (GIS). Digital elevation models, which are the fundamental components of cartography, is calculated by many methods. Digital elevation models can be obtained terrestrial methods or data obtained by digitization of maps by processing the digital platform in general. Today, Digital elevation model data is generated by the processing of stereo optical satellite images, radar images (radargrammetry, interferometry) and lidar data using remote sensing and photogrammetric techniques with the help of improving technology. One of the fundamental components of remote sensing radar technology is very advanced nowadays. In response to this progress it began to be used more frequently in various fields. Determining the shape of topography and creating digital elevation model comes the beginning topics of these areas. It is aimed in this work , the differences of evaluation of quality between Sentinel-1A SAR image ,which is sent by European Space Agency ESA and Interferometry Wide Swath imaging mode and C band type , and DTED-2 (Digital Terrain Elevation Data) and application between them. The application includes RMS static method for detecting precision of data. Results show us to variance of points make a high decrease from mountain area to plane area.

Global Paleobathymetry Reconstruction with Realistic Shelf-Slope and Sediment Wedge

NASA Astrophysics Data System (ADS)

Goswami, A.; Hinnov, L. A.; Gnanadesikan, A.; Olson, P.

2013-12-01

We present paleo-ocean bathymetry reconstructions in a 0.1°x0.1° resolution, using simple geophysical models (Plate Model Equation for oceanic lithosphere), published ages of the ocean floor (Müller et al. 2008), and modern world sediment thickness data (Divins 2003). The motivation is to create realistic paleobathymetry to understand the effect of ocean floor roughness on tides and heat transport in paleoclimate simulations. The values for the parameters in the Plate Model Equation are deduced from Crosby et al. (2006) and are used together with ocean floor age to model Depth to Basement. On top of the Depth to Basement, we added an isostatically adjusted multilayer sediment layer, as indicated from sediment thickness data of the modern oceans and marginal seas (Divins 2003). We also created another version of the sediment layer from the Müller et al. dataset. The Depth to Basement with the appropriate sediment layer together represent a realistic paleobathymetry. A Sediment Wedge was modeled to complement the reconstructed paleobathymetry by extending it to the coastlines. In this process we added a modeled Continental Shelf and Continental Slope to match the extent of the reconstructed paleobathymetry. The Sediment Wedge was prepared by studying the modern ocean where a complete history of seafloor spreading is preserved (north, south and central Atlantic Ocean, Southern Ocean between Australia-Antarctica, and the Pacific Ocean off the west coast of South America). The model takes into account the modern continental shelf-slope structure (as evident from ETOPO1/ETOPO5), tectonic margin type (active vs. passive margin) and age of the latest tectonic activity (USGS & CGMW). Once the complete ocean bathymetry is modeled, we combine it with PALEOMAP (Scotese, 2011) continental reconstructions to produce global paleoworld elevation-bathymetry maps. Modern time (00 Ma) was assumed as a test case. Using the above-described methodology we reconstructed modern ocean bathymetry, starting with age of the oceanic crust. We then reconstructed paleobathymetry for PETM (55 Ma) and Cenomanian-Turonian (90 Ma) times. For each case, the final products are: a) a global depth to basement measurement map based on plate model and EarthByte published age of the ocean crust for modern world; b) global oceanic crust bathymetry maps with a multilayer sediment layer (two versions with two types of sediment layers based on: i) observed total sediment thickness of the modern oceans and marginal seas, and ii) EarthByte-estimated global sediment data for 00 Ma); c) global oceanic bathymetry maps (two versions with two types of sediment layers) with reconstructed shelf and slope; and d) global elevation-bathymetry maps (two versions with two types of sediment layers) with continental elevations (PALEOMAP) and ocean bathymetry. Similar maps for other geological times can be produced using this method provided that ocean crustal age is known.

Noise Prediction Models for Elevated Rail Transit Structures

DOT National Transportation Integrated Search

1975-08-01

The report presents the theoretical development of a model for the prediction of noise radiated by elevated structures on rail transit lines. In particular it deals with noise and vibration control for urban rail transit track and elevated noise and ...

Accuracy assessment of the U.S. Geological Survey National Elevation Dataset, and comparison with other large-area elevation datasets: SRTM and ASTER

USGS Publications Warehouse

Gesch, Dean B.; Oimoen, Michael J.; Evans, Gayla A.

2014-01-01

The National Elevation Dataset (NED) is the primary elevation data product produced and distributed by the U.S. Geological Survey. The NED provides seamless raster elevation data of the conterminous United States, Alaska, Hawaii, U.S. island territories, Mexico, and Canada. The NED is derived from diverse source datasets that are processed to a specification with consistent resolutions, coordinate system, elevation units, and horizontal and vertical datums. The NED serves as the elevation layer of The National Map, and it provides basic elevation information for earth science studies and mapping applications in the United States and most of North America. An important part of supporting scientific and operational use of the NED is provision of thorough dataset documentation including data quality and accuracy metrics. The focus of this report is on the vertical accuracy of the NED and on comparison of the NED with other similar large-area elevation datasets, namely data from the Shuttle Radar Topography Mission (SRTM) and the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER).

Illumination Conditions at the Asteroid 4 Vesta: Implications for the Presence of Water Ice

NASA Technical Reports Server (NTRS)

Stubbs, Timothy J.; Wang, Yongli

2011-01-01

The mean illumination conditions and surface temperatures over one orbital period are calculated for the Asteroid 4 Vesta using a coarse digital elevation model produced from Hubble Space Telescope images. Even with the anticipated effects of finer-scale topography taken into account, it is unlikely that any significant permanently shadowed regions currently exist on Vesta due to its large axial tilt (approx. = 27deg). However, under present day conditions, it is predicted that about half of Vesta's surface has an average temperature of less than 145 K, which, based on previous thermal modeling of main belt asteroids, suggests that water ice could survive in the top few meters of the vestal regolith on billion-year timescales.

Alpine Fault, New Zealand, SRTM Shaded Relief and Colored Height

NASA Technical Reports Server (NTRS)

2005-01-01

The Alpine fault runs parallel to, and just inland of, much of the west coast of New Zealand's South Island. This view was created from the near-global digital elevation model produced by the Shuttle Radar Topography Mission (SRTM) and is almost 500 kilometers (just over 300 miles) wide. Northwest is toward the top. The fault is extremely distinct in the topographic pattern, nearly slicing this scene in half lengthwise.

In a regional context, the Alpine fault is part of a system of faults that connects a west dipping subduction zone to the northeast with an east dipping subduction zone to the southwest, both of which occur along the juncture of the Indo-Australian and Pacific tectonic plates. Thus, the fault itself constitutes the major surface manifestation of the plate boundary here. Offsets of streams and ridges evident in the field, and in this view of SRTM data, indicate right-lateral fault motion. But convergence also occurs across the fault, and this causes the continued uplift of the Southern Alps, New Zealand's largest mountain range, along the southeast side of the fault.

Two visualization methods were combined to produce this image: shading and color coding of topographic height. The shade image was derived by computing topographic slope in the northwest-southeast (image top to bottom) direction, so that northwest slopes appear bright and southeast slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations.

Elevation data used in this image were acquired by the Shuttle Radar Topography Mission aboard the Space Shuttle Endeavour, launched on Feb. 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect 3-D measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter (approximately 200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between NASA, the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif., for NASA's Earth Science Enterprise, Washington, D.C.

Size: 495 kilometers (307 miles) by 162 kilometers (100 miles) Location: 43.2 degrees South latitude, 170.5 degrees East longitude Orientation: Northwest toward the top Image Data: Shaded and colored SRTM elevation model Date Acquired: February 2000

Maternal Separation Does Not Produce a Significant Behavioral Change in Mice

PubMed Central

Tan, Shawn; Ho, Hin San; Song, Anna Yoonsu; Low, Joey

2017-01-01

Early life adversities together with genetic predispositions have been associated with elevated risks of neuropsychiatric disorders during later life. In order to investigate the underlying mechanisms, many chronic, early-life stress paradigms in multiple animal models have been developed. Previously, studies reported that maternal separation (MS) in the early postnatal stages triggers depression-and/or anxiety-like behaviors in rats. However, similar studies using mice have reported inconsistent behavioral outcomes. In this study, we sought to assess behavioral outcomes from two different early-life stress paradigms; a conventional 3-hour MS and a maternal separation with early weaning (MSEW) paradigm using C57BL/6J male mice with independent cohorts. Our data demonstrated that both MS and MSEW paradigms did not produce reported behavioral anomalies. Therefore, MS paradigms in mice require further validation and modification. PMID:29302206

New Geologic Map of the Scandia Region of Mars

NASA Technical Reports Server (NTRS)

Tanaka, K. L.; Rodriquez, J. A. P.; Skinner, J. A., Jr.; Hayward, R. K.; Fortezzo, C.; Edmundson, K.; Rosiek, M.

2009-01-01

We have begun work on a sophisti-cated digital geologic map of the Scandia region (Fig. 1) at 1:3,000,000 scale based on post-Viking image and to-pographic datasets. Through application of GIS tools, we will produce a map product that will consist of (1) a printed photogeologic map displaying geologic units and relevant modificational landforms produced by tectonism, erosion, and collapse/mass wasting; (2) a landform geoda-tabase including sublayers of key landform types, attributed with direct measurements of their planform and to-pography using Mars Orbiter Laser Altimeter (MOLA) altimetry data and High-Resolution Stereo Camera (HRSC) digital elevation models (DEMs) and various image datasets; and (3) a series of digital, reconstructed paleostratigraphic and paleotopographic maps showing the inferred distribution and topographic form of materi-als and features during past ages

Experimental insights into geochemical changes in hydraulically fractured Marcellus Shale

DOE Office of Scientific and Technical Information (OSTI.GOV)

Marcon, Virginia; Joseph, Craig; Carter, Kimberly E.

Hydraulic fracturing applied to organic-rich shales has significantly increased the recoverable volume of methane available for U.S. energy consumption. Fluid-shale reactions in the reservoir may affect long-term reservoir productivity and waste management needs through changes to fracture mineral composition and produced fluid chemical composition. We performed laboratory experiments with Marcellus Shale and lab-generated hydraulic fracturing fluid at elevated pressures and temperatures to evaluate mineral reactions and the release of trace elements into solution. Results from the experiment containing fracturing chemicals show evidence for clay and carbonate dissolution, secondary clay and anhydrite precipitation, and early-stage (24-48 h) fluid enrichment of certainmore » elements followed by depletion in later stages (i.e. Al, Cd, Co, Cr, Cu, Ni, Sc, Zn). Other elements such as As, Fe, Mn, Sr, and Y increased in concentration and remained elevated throughout the duration of the experiment with fracturing fluid. Geochemical modeling of experimental fluid data indicates primary clay dissolution, and secondary formation of smectites and barite, after reaction with fracturing fluid. Changes in aqueous organic composition were observed, indicating organic additives may be chemically transformed or sequestered by the formation after hydraulic fracturing. The NaCl concentrations in our fluids are similar to measured concentrations in Marcellus Shale produced waters, showing that these experiments are representative of reservoir fluid chemistries and can provide insight on geochemical reactions that occur in the field. These results can be applied towards evaluating the evolution of hydraulically-fractured reservoirs, and towards understanding geochemical processes that control the composition of produced water from unconventional shales.« less

Metabolic profiles in five high-producing Swedish dairy herds with a history of abomasal displacement and ketosis

PubMed Central

Stengärde, Lena; Tråvén, Madeleine; Emanuelson, Ulf; Holtenius, Kjell; Hultgren, Jan; Niskanen, Rauni

2008-01-01

Background Body condition score and blood profiles have been used to monitor management and herd health in dairy cows. The aim of this study was to examine BCS and extended metabolic profiles, reflecting both energy metabolism and liver status around calving in high-producing herds with a high incidence of abomasal displacement and ketosis and to evaluate if such profiles can be used at herd level to pinpoint specific herd problems. Methods Body condition score and metabolic profiles around calving in five high-producing herds with high incidences of abomasal displacement and ketosis were assessed using linear mixed models (94 cows, 326 examinations). Cows were examined and blood sampled every three weeks from four weeks ante partum (ap) to nine weeks postpartum (pp). Blood parameters studied were glucose, fructosamine, non-esterified fatty acids (NEFA), insulin, β-hydroxybutyrate, aspartate aminotransferase, glutamate dehydrogenase, haptoglobin and cholesterol. Results All herds had overconditioned dry cows that lost body condition substantially the first 4–6 weeks pp. Two herds had elevated levels of NEFA ap and three herds had elevated levels pp. One herd had low levels of insulin ap and low levels of cholesterol pp. Haptoglobin was detected pp in all herds and its usefulness is discussed. Conclusion NEFA was the parameter that most closely reflected the body condition losses while these losses were not seen in glucose and fructosamine levels. Insulin and cholesterol were potentially useful in herd profiles but need further investigation. Increased glutamate dehydrogenase suggested liver cell damage in all herds. PMID:18687108

Experimental insights into geochemical changes in hydraulically fractured Marcellus Shale

DOE PAGES

Marcon, Virginia; Joseph, Craig; Carter, Kimberly E.; ...

2016-11-09

Hydraulic fracturing applied to organic-rich shales has significantly increased the recoverable volume of methane available for U.S. energy consumption. Fluid-shale reactions in the reservoir may affect long-term reservoir productivity and waste management needs through changes to fracture mineral composition and produced fluid chemical composition. We performed laboratory experiments with Marcellus Shale and lab-generated hydraulic fracturing fluid at elevated pressures and temperatures to evaluate mineral reactions and the release of trace elements into solution. Results from the experiment containing fracturing chemicals show evidence for clay and carbonate dissolution, secondary clay and anhydrite precipitation, and early-stage (24-48 h) fluid enrichment of certainmore » elements followed by depletion in later stages (i.e. Al, Cd, Co, Cr, Cu, Ni, Sc, Zn). Other elements such as As, Fe, Mn, Sr, and Y increased in concentration and remained elevated throughout the duration of the experiment with fracturing fluid. Geochemical modeling of experimental fluid data indicates primary clay dissolution, and secondary formation of smectites and barite, after reaction with fracturing fluid. Changes in aqueous organic composition were observed, indicating organic additives may be chemically transformed or sequestered by the formation after hydraulic fracturing. The NaCl concentrations in our fluids are similar to measured concentrations in Marcellus Shale produced waters, showing that these experiments are representative of reservoir fluid chemistries and can provide insight on geochemical reactions that occur in the field. These results can be applied towards evaluating the evolution of hydraulically-fractured reservoirs, and towards understanding geochemical processes that control the composition of produced water from unconventional shales.« less

A systems model for immune cell interactions unravels the mechanism of inflammation in human skin.

PubMed

Valeyev, Najl V; Hundhausen, Christian; Umezawa, Yoshinori; Kotov, Nikolay V; Williams, Gareth; Clop, Alex; Ainali, Crysanthi; Ouzounis, Christos; Tsoka, Sophia; Nestle, Frank O

2010-12-02

Inflammation is characterized by altered cytokine levels produced by cell populations in a highly interdependent manner. To elucidate the mechanism of an inflammatory reaction, we have developed a mathematical model for immune cell interactions via the specific, dose-dependent cytokine production rates of cell populations. The model describes the criteria required for normal and pathological immune system responses and suggests that alterations in the cytokine production rates can lead to various stable levels which manifest themselves in different disease phenotypes. The model predicts that pairs of interacting immune cell populations can maintain homeostatic and elevated extracellular cytokine concentration levels, enabling them to operate as an immune system switch. The concept described here is developed in the context of psoriasis, an immune-mediated disease, but it can also offer mechanistic insights into other inflammatory pathologies as it explains how interactions between immune cell populations can lead to disease phenotypes.

Management experiments for high-elevation agroforestry systems jointly producing matsutake mushrooms and high-quality timber in the Cascade Range of southern Oregon.

Treesearch

James F. Weigand

1998-01-01

Experimental prescriptions compare agroforestry systems designed to increase financial returns from high-elevation stands in the southern Oregon Cascade Range. The prescriptions emphasize alternative approaches for joint production of North American matsutake mushrooms (also known as North American pine mushrooms; Tricholoma magnivelare) and high-...

Insolation-sunshine relation with site elevation and latitude

DOE Office of Scientific and Technical Information (OSTI.GOV)

Raja, I.A.

1994-07-01

Data from six meteorological stations dispersed widely over Pakistan have been used to produce a correlation between the monthly means of easily measured sunshine duration and the less frequently recorded global solar radiation, taking into account the site elevation above sea level and the latitude. The relation is shown to be valuable for other regions too.

A categorical, improper probability method for combining NDVI and LiDAR elevation information for potential cotton precision agricultural applications

USDA-ARS?s Scientific Manuscript database

An algorithm is presented to fuse the Normalized Difference Vegetation Index (NDVI) with Light Detection and Ranging (LiDAR) elevation data to produce a map potentially useful for the site-specific scouting and pest management of several insect pests. In cotton, these pests include the Tarnished Pl...

UV-C mutagenesis of Kluyveromyces marxianus NRRL Y-1109 strain for improved anaerobic growth at elevated temperature on pentose and hexose sugars

USDA-ARS?s Scientific Manuscript database

More robust industrial yeast strains from Kluyveromyces marxianus NRRL Y-1109 and have been produced using UV-C irradiation specifically for anaerobic conversion of lignocellulosic sugar streams to fuel ethanol at elevated temperature (45°C). This type of random mutagenesis offers the possibility o...

CIELO-A GIS integrated model for climatic and water balance simulation in islands environments

NASA Astrophysics Data System (ADS)

Azevedo, E. B.; Pereira, L. S.

2003-04-01

The model CIELO (acronym for "Clima Insular à Escala Local") is a physically based model that simulates the climatic variables in an island using data from a single synoptic reference meteorological station. The reference station "knows" its position in the orographic and dynamic regime context. The domain of computation is a GIS raster grid parameterised with a digital elevation model (DEM). The grid is oriented following the direction of the air masses circulation through a specific algorithm named rotational terrain model (RTM). The model consists of two main sub-models. One, relative to the advective component simulation, assumes the Foehn effect to reproduce the dynamic and thermodynamic processes occurring when an air mass moves through the island orographic obstacle. This makes possible to simulate the air temperature, air humidity, cloudiness and precipitation as influenced by the orography along the air displacement. The second concerns the radiative component as affected by the clouds of orographic origin and by the shadow produced by the relief. The initial state parameters are computed starting from the reference meteorological station across the DEM transept until the sea level at the windward side. Then, starting from the sea level, the model computes the local scale meteorological parameters according to the direction of the air displacement, which is adjusted with the RTM. The air pressure, temperature and humidity are directly calculated for each cell in the computational grid, while several algorithms are used to compute the cloudiness, net radiation, evapotranspiration, and precipitation. The model presented in this paper has been calibrated and validated using data from some meteorological stations and a larger number of rainfall stations located at various elevations in the Azores Islands.

Modeling Input Errors to Improve Uncertainty Estimates for Sediment Transport Model Predictions

NASA Astrophysics Data System (ADS)

Jung, J. Y.; Niemann, J. D.; Greimann, B. P.

2016-12-01

Bayesian methods using Markov chain Monte Carlo algorithms have recently been applied to sediment transport models to assess the uncertainty in the model predictions due to the parameter values. Unfortunately, the existing approaches can only attribute overall uncertainty to the parameters. This limitation is critical because no model can produce accurate forecasts if forced with inaccurate input data, even if the model is well founded in physical theory. In this research, an existing Bayesian method is modified to consider the potential errors in input data during the uncertainty evaluation process. The input error is modeled using Gaussian distributions, and the means and standard deviations are treated as uncertain parameters. The proposed approach is tested by coupling it to the Sedimentation and River Hydraulics - One Dimension (SRH-1D) model and simulating a 23-km reach of the Tachia River in Taiwan. The Wu equation in SRH-1D is used for computing the transport capacity for a bed material load of non-cohesive material. Three types of input data are considered uncertain: (1) the input flowrate at the upstream boundary, (2) the water surface elevation at the downstream boundary, and (3) the water surface elevation at a hydraulic structure in the middle of the reach. The benefits of modeling the input errors in the uncertainty analysis are evaluated by comparing the accuracy of the most likely forecast and the coverage of the observed data by the credible intervals to those of the existing method. The results indicate that the internal boundary condition has the largest uncertainty among those considered. Overall, the uncertainty estimates from the new method are notably different from those of the existing method for both the calibration and forecast periods.

Parameter variation effects on temperature elevation in a steady-state, one-dimensional thermal model for millimeter wave exposure of one- and three-layer human tissue.

PubMed

Kanezaki, Akio; Hirata, Akimasa; Watanabe, Soichi; Shirai, Hiroshi

2010-08-21

The present study describes theoretical parametric analysis of the steady-state temperature elevation in one-dimensional three-layer (skin, fat and muscle) and one-layer (skin only) models due to millimeter-wave exposure. The motivation of this fundamental investigation is that some variability of warmth sensation in the human skin has been reported. An analytical solution for a bioheat equation was derived by using the Laplace transform for the one-dimensional human models. Approximate expressions were obtained to investigate the dependence of temperature elevation on different thermal and tissue thickness parameters. It was shown that the temperature elevation on the body surface decreases monotonically with the blood perfusion rate, heat conductivity and heat transfer from the body to air. Also revealed were the conditions where maximum and minimum surface temperature elevations were observed for different thermal and tissue thickness parameters. The surface temperature elevation in the three-layer model is 1.3-2.8 times greater than that in the one-layer model. The main reason for this difference is attributed to the adiabatic nature of the fat layer. By considering the variation range of thermal and tissue thickness parameters which causes the maximum and minimum temperature elevations, the dominant parameter influencing the surface temperature elevation was found to be the heat transfer coefficient between the body surface and air.

SRTM Anaglyph: Sredinnyy Khrebet, Kamchatka Peninsula, Russia

NASA Technical Reports Server (NTRS)

2001-01-01

The Kamchatka Peninsula in eastern Russia is shown in this scene created from a preliminary elevation model derived from the first data collected during the Shuttle Radar Topography Mission (SRTM) on February 12, 2000. Sredinnyy Khrebet, the mountain range that makes up the spine of the peninsula, is a chain of active volcanic peaks. Pleistocene and recent glaciers have carved the broad valleys and jagged ridges that are common here. The relative youth of the volcanism is revealed by the topography as infilling and smoothing of the otherwise rugged terrain by lava, ash, and pyroclastic flows, particularly surrounding the high peaks in the south central part of the image. Elevations here range from near sea level up to 2,618 meters (8,590 feet).

This anaglyph was produced by first shading a preliminary SRTM elevation model. The stereoscopic effect was then created by generating two differing perspectives, one for each eye. When viewed through special glasses, the result is a vertically exaggerated view of Earth's surface in its full three dimensions. Anaglyph glasses cover the left eye with a red filter and cover the right eye with a blue filter.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense, and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

Size: 93.0 x 105.7 kilometers ( 57.7 x 65.6 miles) Location: 58.3 deg. North lat., 160.9 deg. East lon. Orientation: North toward the top Image Data: Shaded SRTM elevation model Date Acquired: February 12, 2000

Impacts of Near-Future Ocean Acidification and Warming on the Shell Mechanical and Geochemical Properties of Gastropods from Intertidal to Subtidal Zones.

PubMed

Leung, Jonathan Y S; Connell, Sean D; Nagelkerken, Ivan; Russell, Bayden D

2017-11-07

Many marine organisms produce calcareous shells as the key structure for defense, but the functionality of shells may be compromised by ocean acidification and warming. Nevertheless, calcifying organisms may adaptively modify their shell properties in response to these impacts. Here, we examined how reduced pH and elevated temperature affect shell mechanical and geochemical properties of common grazing gastropods from intertidal to subtidal zones. Given the greater environmental fluctuations in the intertidal zone, we hypothesized that intertidal gastropods would exhibit more plastic responses in shell properties than subtidal gastropods. Overall, three out of five subtidal gastropods produced softer shells at elevated temperature, while intertidal gastropods maintained their shell hardness at both elevated pCO 2 (i.e., reduced pH) and temperature. Regardless of pH and temperature, degree of crystallization was maintained (except one subtidal gastropod) and carbonate polymorph remained unchanged in all tested species. One intertidal gastropod produced less soluble shells (e.g., higher calcite/aragonite) in response to reduced pH. In contrast, subtidal gastropods produced only aragonite which has higher solubility than calcite. Overall, subtidal gastropods are expected to be more susceptible than intertidal gastropods to shell dissolution and physical damage under future seawater conditions. The increased vulnerability to shell dissolution and predation could have serious repercussions for their survival and ecological contributions in the future subtidal environment.

An Imminent Revolution in Modeling Interactions of Ice Sheets With Climate

NASA Astrophysics Data System (ADS)

Hughes, T.

2008-12-01

Modeling continental ice sheets was inaugurated by meteorologists William Budd and Uwe Radok, with mathematician Richard Jenssen, in 1971. Their model calculated the thermal and mechanical regime using measured surface accumulation rates, temperatures, and elevations, and bed topography. This top-down approach delivered a basal thermal regime of temperatures or melting rates for an assumed basal geothermal heat flux. When Philippe Huybrechts and others incorporated time, largely unknownpast surface conditions had a major effect on present basal thermal conditions. This approach produced ice-sheet models with only a slow response to external forcing, whereas the glacial geological record and climate records from ice and ocean cores show that ice sheets can have rapid changes in size and shape independent of external forcing. These top-down models were wholly inadequate for reconstructing former ice sheets at the LGM for CLIMAP in 1981. Ice-sheet areas,elevations, and volumes provided the albedo, surface topography, and sea-surface area as input to climate models. A bottom-up model based on dated glacial geology was developed to provide the areal extent and basal thermal regime of ice sheets at the LGM. Basal thermal conditions determined ice-bed coupling and therefore the elevation of ice sheets. High convex ice surfaces for slow sheet flow lower about 20 percent when a frozen bed becomes thawed. As further basal melting drowns bedrock bumps that "pin" basal ice, the ice surface becomes concave in fast stream flow that ends as low floating ice shelves at marine ice margins. A revolution in modeling interactions between glaciation, climate, and sea level is driven by new Greenland and Antarctic data from Earth-orbiting satellites, airborne and surface traverses, and deep drilling. We anticipate continuous data acquisition of surface albedo, accumulation/ablation rates, elevations, velocities, and temperatures over a whole ice sheet, mapping basal thermal conditions by radar, seismic, and magnetic profiling, and direct measurement of basal conditions by deep drilling and coring into the ice and the bed. These data allow calculating the geothermal heat flux and mapping flow of basal meltwater from geothermal sources to sinks at the termini of ice streams, which discharge up to 90 percent of the ice. James Fastook has a preliminary solution of the full momentum equation needed to model ice streams. Douglas MacAyeal has pioneered modeling catastrophic ice-shelf disintegration that releases "armadas" of icebergs into the world ocean, to extract heat from ocean surface water and thereby reduce the critical ocean-to-atmosphere heat exchange that drives global climate. Ice sheets are the only component of Earth's climate machine that can destroy itself-- swiftly--and thereby radically and rapidly alter global climate and sea level.

The Algorithm Theoretical Basis Document for the Derivation of Range and Range Distributions from Laser Pulse Waveform Analysis for Surface Elevations, Roughness, Slope, and Vegetation Heights

NASA Technical Reports Server (NTRS)

Brenner, Anita C.; Zwally, H. Jay; Bentley, Charles R.; Csatho, Bea M.; Harding, David J.; Hofton, Michelle A.; Minster, Jean-Bernard; Roberts, LeeAnne; Saba, Jack L.; Thomas, Robert H.;

The benefits of improved national elevation data

USGS Publications Warehouse

Snyder, Gregory I.

2013-01-01

This article describes how the National Enhanced Elevation Assessment (NEEA) has identified substantial benefits that could come about if improved elevation data were publicly available for current and emerging applications and business uses such as renewable energy, precision agriculture, and intelligent vehicle navigation and safety. In order to support these diverse needs, new national elevation data with higher resolution and accuracy are needed. The 3D Elevation Program (3DEP) initiative was developed to meet the majority of these needs and it is expected that 3DEP will result in new, unimagined information services that would result in job growth and the transformation of the geospatial community. Private-sector data collection companies are continuously evolving sensors and positioning technologies that are needed to collect improved elevation data. An initiative of this scope might also provide an opportunity for companies to improve their capabilities and produce even higher data quality and consistency at a pace that might not have otherwise occurred.

The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China.

PubMed

Xu, Jingxin; Zheng, Youfei; He, Yuhong; Wu, Rongjun; Mai, Boru; Kang, Hanqing

2016-01-01

Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L.) at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb), Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb), and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb), with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system). These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R(2) = 0.85 & T2: R(2) = 0.89) of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m(-2) of cumulative ozone uptake. At the regional level, dry matter loss in winter wheat would reach 50% under elevated ozone concentrations and reduced solar irradiance as determined in T1, and 30% under conditions as determined in T2. Results from this study suggest that a combination of elevated ozone concentrations and reduced solar irradiance could result in substantial dry matter loss in the Chinese wheat-growing regions.

The Effect of Elevated Ozone Concentrations with Varying Shading on Dry Matter Loss in a Winter Wheat-Producing Region in China

PubMed Central

Xu, Jingxin; Zheng, Youfei; He, Yuhong; Wu, Rongjun; Mai, Boru; Kang, Hanqing

2016-01-01

Surface-level ozone pollution causes crop production loss by directly reducing healthy green leaf area available for carbon fixation. Ozone and its precursors also affect crop photosynthesis indirectly by decreasing solar irradiance. Pollutants are reported to have become even more severe in Eastern China over the last ten years. In this study, we investigated the effect of a combination of elevated ozone concentrations and reduced solar irradiance on a popular winter wheat Yangmai13 (Triticum aestivum L.) at field and regional levels in China. Winter wheat was grown in artificial shading and open-top-chamber environments. Treatment 1 (T1, i.e., 60% shading with an enhanced ozone of 100±9 ppb), Treatment 2 (T2, i.e., 20% shading with an enhanced ozone of 100±9 ppb), and Control Check Treatment (CK, i.e., no shading with an enhanced ozone of 100±9 ppb), with two plots under each, were established to investigate the response of winter wheat under elevated ozone concentrations and varying solar irradiance. At the field level, linear temporal relationships between dry matter loss and cumulative stomatal ozone uptake were first established through a parameterized stomatal-flux model. At the regional level, ozone concentrations and meteorological variables, including solar irradiance, were simulated using the WRF-CMAQ model (i.e., a meteorology and air quality modeling system). These variables were then used to estimate cumulative stomatal ozone uptake for the four major winter wheat-growing provinces. The regional-level cumulative ozone uptake was then used as the independent variable in field data-based regression models to predict dry matter loss over space and time. Field-level results showed that over 85% (T1: R2 = 0.85 & T2: R2 = 0.89) of variation in dry matter loss was explained by cumulative ozone uptake. Dry matter was reduced by 3.8% in T1 and 2.2% in T2 for each mmol O3·m-2 of cumulative ozone uptake. At the regional level, dry matter loss in winter wheat would reach 50% under elevated ozone concentrations and reduced solar irradiance as determined in T1, and 30% under conditions as determined in T2. Results from this study suggest that a combination of elevated ozone concentrations and reduced solar irradiance could result in substantial dry matter loss in the Chinese wheat-growing regions. PMID:26760509

A complete VLBI delay model for deforming radio telescopes: the Effelsberg case

NASA Astrophysics Data System (ADS)

Artz, T.; Springer, A.; Nothnagel, A.

2014-12-01

Deformations of radio telescopes used in geodetic and astrometric very long baseline interferometry (VLBI) observations belong to the class of systematic error sources which require correction in data analysis. In this paper we present a model for all path length variations in the geometrical optics of radio telescopes which are due to gravitational deformation. The Effelsberg 100 m radio telescope of the Max Planck Institute for Radio Astronomy, Bonn, Germany, has been surveyed by various terrestrial methods. Thus, all necessary information that is needed to model the path length variations is available. Additionally, a ray tracing program has been developed which uses as input the parameters of the measured deformations to produce an independent check of the theoretical model. In this program as well as in the theoretical model, the illumination function plays an important role because it serves as the weighting function for the individual path lengths depending on the distance from the optical axis. For the Effelsberg telescope, the biggest contribution to the total path length variations is the bending of the main beam located along the elevation axis which partly carries the weight of the paraboloid at its vertex. The difference in total path length is almost 100 mm when comparing observations at 90 and at 0 elevation angle. The impact of the path length corrections is validated in a global VLBI analysis. The application of the correction model leads to a change in the vertical position of mm. This is more than the maximum path length, but the effect can be explained by the shape of the correction function.

An Applet to Estimate the IOP-Induced Stress and Strain within the Optic Nerve Head

PubMed Central

2011-01-01

Purpose. The ability to predict the biomechanical response of the optic nerve head (ONH) to intraocular pressure (IOP) elevation holds great promise, yet remains elusive. The objective of this work was to introduce an approach to model ONH biomechanics that combines the ease of use and speed of analytical models with the flexibility and power of numerical models. Methods. Models representing a variety of ONHs were produced, and finite element (FE) techniques used to predict the stresses (forces) and strains (relative deformations) induced on each of the models by IOP elevations (up to 10 mm Hg). Multivariate regression was used to parameterize each biomechanical response as an analytical function. These functions were encoded into a Flash-based applet. Applet utility was demonstrated by investigating hypotheses concerning ONH biomechanics posited in the literature. Results. All responses were parameterized well by polynomials (R2 values between 0.985 and 0.999), demonstrating the effectiveness of our fitting approach. Previously published univariate results were reproduced with the applet in seconds. A few minutes allowed for multivariate analysis, with which it was predicted that often, but not always, larger eyes experience higher levels of stress and strain than smaller ones, even at the same IOP. Conclusions. An applet has been presented with which it is simple to make rapid estimates of IOP-related ONH biomechanics. The applet represents a step toward bringing the power of FE modeling beyond the specialized laboratory and can thus help develop more refined biomechanics-based hypotheses. The applet is available for use at www.ocularbiomechanics.com. PMID:21527378

Simulation and optimization of silicon-on-sapphire pressure sensor

NASA Astrophysics Data System (ADS)

Kulesh, N. A.; Kudyukov, E. V.; Balymov, K. G.; Beloyshov, A. A.

2017-09-01

In this paper, finite element analysis software COMSOL Multiphysics was used to simulate the performance of silicon-on-sapphire piezoresistive pressure sensor, aiming to elaborate a flexible model suitable for further optimization and customization of the currently produced pressure sensors. The base model was built around the cylindrical pressure cell made of titanium alloy having a circular diaphragm with monocrystalline sapphire layer attached. The monocrystalline piezoresistive elements were placed on top of the double-layer diaphragm and electrically connected to form the Wheatstone bridge. Verification of the model and parametric study included three main areas: geometrical parameters of the cell, position of the elements on the diaphragm, and operation at elevated temperature. Optimization of the cell geometry included variation of bossed titanium diaphragm parameters as well as rounding-off radiuses near the edges of the diaphragm. Influence of the temperature was considered separately for thermal expansion of the mechanical components and for the changes of electrical and piezoresistive properties of the piezoresistive elements. In conclusion, the simulation results were compared to the experimental data obtained for three different constructions of the commercial pressure sensors produced by SPA of Automatics named after Academician N.A. Semikhatov.

The morphology of transverse aeolian ridges on Mars

NASA Astrophysics Data System (ADS)

Geissler, Paul E.; Wilgus, Justin T.

2017-06-01

A preliminary survey of publicly released high resolution digital terrain models (DTMs) produced by the High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter identified transverse aeolian ridges (TARs) in 154 DTMs in latitudes from 50°S to 40°N. Consistent with previous surveys, the TARs identified in HiRISE DTMs are found at all elevations, irrespective of the regional thermal inertia of the surface. Ten DTMs were selected for measuring the characteristics of the TARs, including maximum height, mean height, mean spacing (wavelength), and the slope of the surface where they are located. We confined our measurements to features that were taller than 1 m and spaced more than 10 m apart. We found a surprisingly wide variability of TAR sizes within each local region (typically 5 km by 25 km), with up to a factor of 7 difference in TAR wavelengths in a single DTM. The TAR wavelengths do not appear to be correlated to latitude or elevation, but the largest TARs in our small survey were found at lower elevations. The tallest TARs we measured were on the flat floor of Moni crater, within Kaiser crater in the southern highlands. These TARs are up to 14 m tall, with a typical wavelength of 120 m. TAR heights are weakly correlated with their wavelengths. The height-to-wavelength ratios for most TARs are far less than 1/2π (the maximum predicted for antidunes), however in two cases the ratio is close to 1/2π, and in one case (in the bend of a channel) the ratio exceeds 1/2π. TAR wavelengths are uncorrelated with surface slope, both on local and regional scales. TAR heights are weakly anti-correlated with local slope. These results help constrain models of TAR formation, particularly a new hypothesis (Geissler, 2014) that suggests that TARs were formed from micron-sized dust that was transported in suspension. The lack of correlation between TAR wavelength and surface slope seems to rule out formation by gravity-driven dust flows such as avalanches or density currents, and suggests that the TARs were instead produced by the Martian winds.

Anthropogenic contribution to the geological and geomorphological record: A case study from Great Yarmouth, Norfolk, UK

NASA Astrophysics Data System (ADS)

Jordan, Hannah; Hamilton, Ken; Lawley, Russell; Price, Simon James

2016-01-01

Reconstruction of artificial or anthropogenic topographies, sediment thicknesses and volumes provides a mechanism for quantifying anthropogenic changes to sedimentary systems in the context of the proposed Anthropocene epoch. We present a methodology for determining the volumetric contribution of anthropogenic deposits to the geological and geomorphological record and apply it to the Great Yarmouth area of Norfolk, UK. 115 boreholes, drilled to a maximum depth of 6 m below ground level, were used to determine the thickness and distribution of seven geo-archaeological units comprising natural and anthropogenic deposits in the central Great Yarmouth area. This was supplemented by additional depth information derived from 467 existing ground investigation boreholes and published 1:50 000 scale geological maps. The top and base of each geo-archaeological unit were modelled from elevations recorded in the borehole data. Grids were produced using a natural neighbour analysis with a 25 m cell size using MapInfo 8.0 Vertical Mapper 3.1 to produce palaeotopographical surfaces. Maximum, minimum and average elevations for each geo-archaeological unit generally increase with decreasing age with the exception of the Early-Medieval palaeotopographical surface which locally occurs at higher elevations than that of the younger Late-Medieval unit. The total sediment volume for the combined Modern, Post-Medieval, Late-Medieval and Early-Medieval geo-archaeological units is 10.91 × 105 m3. The total sediment volume for the Aeolian, River Terrace and Marine geo-archaeological units combined is 65.58 × 105 m3. Anthropogenic sedimentation rates were calculated to increase from 590 m3/yr during the Early-Medieval period, 1500 m3/yr during the Post-Medieval period and 2300 m3/yr during the Modern period. It is estimated that the combined anthropogenic geo-archaeological units contribute approximately 15% of the total volume of sediments that would have been traditionally considered natural Holocene deposits in the Great Yarmouth area. The results indicate that an approach combining geological and archaeological deposit modelling can be used to quantify anthropogenic landscape impact and its associated sediment flux.

Analysis of rainfall distribution in Kelantan river basin, Malaysia

NASA Astrophysics Data System (ADS)

Che Ros, Faizah; Tosaka, Hiroyuki

2018-03-01

Using rainfall gauge on its own as input carries great uncertainties regarding runoff estimation, especially when the area is large and the rainfall is measured and recorded at irregular spaced gauging stations. Hence spatial interpolation is the key to obtain continuous and orderly rainfall distribution at unknown points to be the input to the rainfall runoff processes for distributed and semi-distributed numerical modelling. It is crucial to study and predict the behaviour of rainfall and river runoff to reduce flood damages of the affected area along the Kelantan river. Thus, a good knowledge on rainfall distribution is essential in early flood prediction studies. Forty six rainfall stations and their daily time-series were used to interpolate gridded rainfall surfaces using inverse-distance weighting (IDW), inverse-distance and elevation weighting (IDEW) methods and average rainfall distribution. Sensitivity analysis for distance and elevation parameters were conducted to see the variation produced. The accuracy of these interpolated datasets was examined using cross-validation assessment.

Land use and land cover digital data from 1:250,000- and 1:100,000- scale maps

USGS Publications Warehouse

,

1990-01-01

The Earth Science Information Centers (ESIC) distribute digital cartographic/geographic data files produced by the U.S. Geological Survey (USGS) as part of the National Mapping Program. The data files are grouped into four basic types. The first type, called a Digital Line Graph (DLG), is line map information in digital form. These data files include information on planimetric base categories, such as transportation, hydrography, and boundaries. The second type, called a Digital Elevation Model (DEM), consists of a sampled array of elevations for ground positions that are usually at regularly spaced intervals. The third type, Land Use and Land Cover digital data, provide information on nine major classes of land use such as urban, agricultural, or forest as well as associated map data such as political units and Federal land ownership. The fourth type, the Geographic Names Information System, provides primary information for known places, features, and areas in the United States identified by a proper name.

Digital line graphs from 1:24,000-scale maps

USGS Publications Warehouse

,

1990-01-01

The Earth Science Information Centers (ESIC) distribute digital cartographic/geographic data files produced by the U.S. Geological Survey (USGS) as part of the National Mapping Program. Digital cartographic data flles are grouped into four basic types. The first of these, called a Digital Line . Graph (DLG), is line map information in digital form. These data files include information on planimetric base categories, such as transportation, hydrography, and boundaries. The second type, called a Digital Elevation Model (DEM), consists of a sampled array of elevations for a number of ground positions that are usually at regularly spaced intervals. The third type is Land Use and Land Cover digital data, which provides information on nine major classes of land use such as urban, agricultural, or forest as wen as associated map data such as political units and Federal land ownership. The fourth type, the Geographic Names Information System, provides primary information for all known places, features, and areas in the United States identified by a proper name.

Digital line graphs from 1:100,000-scale maps

USGS Publications Warehouse

,

1989-01-01

The National Cartographic Information Center (NCIC) distributes digital cartographic/geographic data files produced by the U.S. Geological Survey (USGS) as part of the National Mapping Program. Digital cartographic data files may be grouped into four basic types. The first of these, called a Digital Line Graph (DLG), is line map information in digital form. These data files include information on planimetric base categories, such as transportation, hydrography, and boundaries. The second form, called a Digital Elevation Model (OEM), consists of a sampled array of elevations for ground positions that are usually, but not always, at regularly spaced intervals. The third type is Land Use and Land Cover digital data, which provides information on nine major classes of land use such as urban, agricultural, or forest as well as associated map data such as political units and Federal land ownership. The fourth type, the Geographic Names Information System, provides primary information for known places, features, and areas in the United States identified by a proper name.

Massive Thermal Acceleration of the Emergence of Primordial Chemistry, the Incidence of Spontaneous Mutation, and the Evolution of Enzymes*

PubMed Central

Wolfenden, Richard

2014-01-01

Kelvin considered it unlikely that sufficient time had elapsed on the earth for life to have reached its present level of complexity. In the warm surroundings in which life first appeared, however, elevated temperatures would have reduced the kinetic barriers to reaction. Recent experiments disclose the profound extent to which very slow reactions are accelerated by elevated temperatures, collapsing the time that would have been required for early events in primordial chemistry before the advent of enzymes. If a primitive enzyme, like model catalysts and most modern enzymes, accelerated a reaction by lowering its enthalpy of activation, then the rate enhancement that it produced would have increased automatically as the environment cooled, quite apart from any improvements in catalytic activity that arose from mutation and natural selection. The chemical events responsible for spontaneous mutation are also highly sensitive to temperature, furnishing an independent mechanism for accelerating evolution. PMID:25210030

Dense lower crust elevates long-term earthquake rates in the New Madrid seismic zone

USGS Publications Warehouse

Levandowski, William Brower; Boyd, Oliver; Ramirez-Guzman, Leonardo

2016-01-01

Knowledge of the local state of stress is critical in appraising intraplate seismic hazard. Inverting earthquake moment tensors, we demonstrate that principal stress directions in the New Madrid seismic zone (NMSZ) differ significantly from those in the surrounding region. Faults in the NMSZ that are incompatible with slip in the regional stress field are favorably oriented relative to local stress. We jointly analyze seismic velocity, gravity, and topography to develop a 3-D crustal and upper mantle density model, revealing uniquely dense lower crust beneath the NMSZ. Finite element simulations then estimate the stress tensor due to gravitational body forces, which sums with regional stress. The anomalous lower crust both elevates gravity-derived stress at seismogenic depths in the NMSZ and rotates it to interfere more constructively with far-field stress, producing a regionally maximal deviatoric stress coincident with the highest concentration of modern seismicity. Moreover, predicted principal stress directions mirror variations (observed independently in moment tensors) at the NMSZ and across the region.

The Upper Mississippi River floodscape: spatial patterns of flood inundation and associated plant community distributions

USGS Publications Warehouse

DeJager, Nathan R.; Rohweder, Jason J.; Yin, Yao; Hoy, Erin E.

2016-01-01

Questions How is the distribution of different plant communities associated with patterns of flood inundation across a large floodplain landscape? Location Thirty-eight thousand nine hundred and seventy hectare of floodplain, spanning 320 km of the Upper Mississippi River (UMR). Methods High-resolution elevation data (Lidar) and 30 yr of daily river stage data were integrated to produce a ‘floodscape’ map of growing season flood inundation duration. The distributions of 16 different remotely sensed plant communities were quantified along the gradient of flood duration. Results Models fitted to the cumulative frequency of occurrence of different vegetation types as a function of flood duration showed that most types exist along a continuum of flood-related occurrence. The diversity of community types was greatest at high elevations (0–10 d of flooding), where both upland and lowland community types were found, as well as at very low elevations (70–180 d of flooding), where a variety of lowland herbaceous communities were found. Intermediate elevations (20–60 d of flooding) tended to be dominated by floodplain forest and had the lowest diversity of community types. Conclusions Although variation in flood inundation is often considered to be the main driver of spatial patterns in floodplain plant communities, few studies have quantified flood–vegetation relationships at broad scales. Our results can be used to identify targets for restoration of historical hydrological regimes or better anticipate hydro-ecological effects of climate change at broad scales.

Improved mapping of National Atmospheric Deposition Program wet-deposition in complex terrain using PRISM-gridded data sets

USGS Publications Warehouse

Latysh, Natalie E.; Wetherbee, Gregory Alan

2012-01-01

High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation for unsampled areas does not account for topographic influences. Therefore, NADP/NTN isopleth maps lack detail and potentially underestimate wet deposition in high-elevation regions. The NADP/NTN wet-deposition maps may be improved using precipitation grids generated by other networks. The Parameter-elevation Regressions on Independent Slopes Model (PRISM) produces digital grids of precipitation estimates from many precipitation-monitoring networks and incorporates influences of topographical and geographical features. Because NADP/NTN ion concentrations do not vary with elevation as much as precipitation depths, PRISM is used with unadjusted NADP/NTN data in this paper to calculate ion wet deposition in complex terrain to yield more accurate and detailed isopleth deposition maps in complex terrain. PRISM precipitation estimates generally exceed NADP/NTN precipitation estimates for coastal and mountainous regions in the western United States. NADP/NTN precipitation estimates generally exceed PRISM precipitation estimates for leeward mountainous regions in Washington, Oregon, and Nevada, where abrupt changes in precipitation depths induced by topography are not depicted by IDW interpolation. PRISM-based deposition estimates for nitrate can exceed NADP/NTN estimates by more than 100% for mountainous regions in the western United States.

Improved mapping of National Atmospheric Deposition Program wet-deposition in complex terrain using PRISM-gridded data sets.

PubMed

Latysh, Natalie E; Wetherbee, Gregory Alan

2012-01-01

High-elevation regions in the United States lack detailed atmospheric wet-deposition data. The National Atmospheric Deposition Program/National Trends Network (NADP/NTN) measures and reports precipitation amounts and chemical constituent concentration and deposition data for the United States on annual isopleth maps using inverse distance weighted (IDW) interpolation methods. This interpolation for unsampled areas does not account for topographic influences. Therefore, NADP/NTN isopleth maps lack detail and potentially underestimate wet deposition in high-elevation regions. The NADP/NTN wet-deposition maps may be improved using precipitation grids generated by other networks. The Parameter-elevation Regressions on Independent Slopes Model (PRISM) produces digital grids of precipitation estimates from many precipitation-monitoring networks and incorporates influences of topographical and geographical features. Because NADP/NTN ion concentrations do not vary with elevation as much as precipitation depths, PRISM is used with unadjusted NADP/NTN data in this paper to calculate ion wet deposition in complex terrain to yield more accurate and detailed isopleth deposition maps in complex terrain. PRISM precipitation estimates generally exceed NADP/NTN precipitation estimates for coastal and mountainous regions in the western United States. NADP/NTN precipitation estimates generally exceed PRISM precipitation estimates for leeward mountainous regions in Washington, Oregon, and Nevada, where abrupt changes in precipitation depths induced by topography are not depicted by IDW interpolation. PRISM-based deposition estimates for nitrate can exceed NADP/NTN estimates by more than 100% for mountainous regions in the western United States.

Geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin

NASA Astrophysics Data System (ADS)

Vibhava, F.; Graham, W. D.; Maxwell, R. M.

2012-12-01

Streamflow at any given location and time is representative of surface and subsurface contributions from various sources. The ability to fully identify the factors controlling these contributions is key to successfully understanding the transport of contaminants through the system. In this study we developed a fully integrated 3D surface water-groundwater-land surface model, PARFLOW, to evaluate geologic and climatic controls on streamflow generation processes in a complex eogenetic karst basin in North Central Florida. In addition to traditional model evaluation criterion, such as comparing field observations to model simulated streamflow and groundwater elevations, we quantitatively evaluated the model's predictions of surface-groundwater interactions over space and time using a suite of binary end-member mixing models that were developed using observed specific conductivity differences among surface and groundwater sources throughout the domain. Analysis of model predictions showed that geologic heterogeneity exerts a strong control on both streamflow generation processes and land atmospheric fluxes in this watershed. In the upper basin, where the karst aquifer is overlain by a thick confining layer, approximately 92% of streamflow is "young" event flow, produced by near stream rainfall. Throughout the upper basin the confining layer produces a persistent high surficial water table which results in high evapotranspiration, low groundwater recharge and thus negligible "inter-event" streamflow. In the lower basin, where the karst aquifer is unconfined, deeper water tables result in less evapotranspiration. Thus, over 80% of the streamflow is "old" subsurface flow produced by diffuse infiltration through the epikarst throughout the lower basin, and all surface contributions to streamflow originate in the upper confined basin. Climatic variability provides a secondary control on surface-subsurface and land-atmosphere fluxes, producing significant seasonal and interannual variability in these processes. Spatial and temporal patterns of evapotranspiration, groundwater recharge and streamflow generation processes reveal potential hot spots and hot moments for surface and groundwater contamination in this basin.

Reevaluating Musculoskeletal Linkages in Suction-Feeding Fishes with X-Ray Reconstruction of Moving Morphology (XROMM).

PubMed

Camp, Ariel L; Brainerd, Elizabeth L

2015-07-01

Suction-feeding fishes encompass a vast diversity of morphologies and ecologies, but during feeding they all rely on musculoskeletal linkages and levers to transform the shortening of muscle into 3D expansion of the mouth cavity. To relate the shape of these skeletal elements to their function in expansion of the mouth, four-bar linkage models have been developed and widely used in studies of ecology, evolution, and development. However, we have lacked the ability to test the predictions of these 2D linkage models against the actual 3D motions of fishes' skulls. A new imaging method, X-ray Reconstruction of Moving Morphology (XROMM), now makes it possible to measure 3D skeletal motions relative to other bones within the head and relative to the fish's body, and thereby to examine directly the proposed linkages. We used XROMM to examine the opercular linkage, in which shortening of the levator operculi muscle is hypothesized to retract the operculum, and thereby the interoperculum and interoperculomandibular ligament to generate depression of the lower jaw about the quadratomandibular joint. XROMM animations of suction strikes in largemouth bass revealed that the operculum is indeed retracted relative to the suspensorium as the levator operculi muscle shortens and the jaw depresses. However, the four-bar model of this linkage overestimates the depression of the jaw by nearly a factor of two. Therefore, caution should be used in interpreting and applying the predictions of this linkage model. When we measured kinematics relative to the fish's body, we found that the operculum was relatively stable, whereas the suspensorium was elevated along with the neurocranium, pushing the quadratomandibular joint forward to produce depression of the jaw. Thus, it is the epaxial muscles elevating the neurocranium that powers depression of the jaw through the opercular linkage. However, the levator operculi muscle plays a crucial role in stabilizing the operculum to allow elevation of the head to produce depression of the lower jaw. These results support the role of cranial muscles in controlling and transmitting power from the axial muscles, rather than generating substantial power themselves. We also demonstrate the utility of XROMM for assessing the function of this, and other, cranial linkages in suction-feeding fishes. © The Author 2015. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology. All rights reserved. For permissions please email: journals.permissions@oup.com.

Relation of structure to mechanical properties of thin thoria dispersion strengthened nickel-chromium (TD-NiCr alloy sheet

NASA Technical Reports Server (NTRS)

Whittenberger, J. D.

1975-01-01

A study of the relation between structure and mechanical properties of thin TD-NiCr sheet indicated that the elevated temperature tensile, stress-rupture, and creep strength properties depend primarily on the grain aspect ratio and sheet thickness. In general, the strength properties increased with increasing grain aspect ratio and sheet thickness. Tensile testing revealed an absence of ductility at elevated temperatures. A threshold stress for creep appears to exist. Even small amounts of prior creep deformation at elevated temperatures can produce severe creep damage.

A Systematic Review of Global Drivers of Ant Elevational Diversity

PubMed Central

Szewczyk, Tim; McCain, Christy M.

2016-01-01

Ant diversity shows a variety of patterns across elevational gradients, though the patterns and drivers have not been evaluated comprehensively. In this systematic review and reanalysis, we use published data on ant elevational diversity to detail the observed patterns and to test the predictions and interactions of four major diversity hypotheses: thermal energy, the mid-domain effect, area, and the elevational climate model. Of sixty-seven published datasets from the literature, only those with standardized, comprehensive sampling were used. Datasets included both local and regional ant diversity and spanned 80° in latitude across six biogeographical provinces. We used a combination of simulations, linear regressions, and non-parametric statistics to test multiple quantitative predictions of each hypothesis. We used an environmentally and geometrically constrained model as well as multiple regression to test their interactions. Ant diversity showed three distinct patterns across elevations: most common were hump-shaped mid-elevation peaks in diversity, followed by low-elevation plateaus and monotonic decreases in the number of ant species. The elevational climate model, which proposes that temperature and precipitation jointly drive diversity, and area were partially supported as independent drivers. Thermal energy and the mid-domain effect were not supported as primary drivers of ant diversity globally. The interaction models supported the influence of multiple drivers, though not a consistent set. In contrast to many vertebrate taxa, global ant elevational diversity patterns appear more complex, with the best environmental model contingent on precipitation levels. Differences in ecology and natural history among taxa may be crucial to the processes influencing broad-scale diversity patterns. PMID:27175999

Creating a Coastal National Elevation Database (CoNED) for science and conservation applications

USGS Publications Warehouse

Thatcher, Cindy A.; Brock, John C.; Danielson, Jeffrey J.; Poppenga, Sandra K.; Gesch, Dean B.; Palaseanu-Lovejoy, Monica; Barras, John; Evans, Gayla A.; Gibbs, Ann

2016-01-01

The U.S. Geological Survey is creating the Coastal National Elevation Database, an expanding set of topobathymetric elevation models that extend seamlessly across coastal regions of high societal or ecological significance in the United States that are undergoing rapid change or are threatened by inundation hazards. Topobathymetric elevation models are raster datasets useful for inundation prediction and other earth science applications, such as the development of sediment-transport and storm surge models. These topobathymetric elevation models are being constructed by the broad regional assimilation of numerous topographic and bathymetric datasets, and are intended to fulfill the pressing needs of decision makers establishing policies for hazard mitigation and emergency preparedness, coastal managers tasked with coastal planning compatible with predictions of inundation due to sea-level rise, and scientists investigating processes of coastal geomorphic change. A key priority of this coastal elevation mapping effort is to foster collaborative lidar acquisitions that meet the standards of the USGS National Geospatial Program's 3D Elevation Program, a nationwide initiative to systematically collect high-quality elevation data. The focus regions are located in highly dynamic environments, for example in areas subject to shoreline change, rapid wetland loss, hurricane impacts such as overwash and wave scouring, and/or human-induced changes to coastal topography.

Modeling Elevation and Aspect Controls on Emerging Ecohydrologic Processes and Ecosystem Patterns Using the Component-based Landlab Framework

NASA Astrophysics Data System (ADS)

Nudurupati, S. S.; Istanbulluoglu, E.; Adams, J. M.; Hobley, D. E. J.; Gasparini, N. M.; Tucker, G. E.; Hutton, E. W. H.

2014-12-01

Topography plays a commanding role on the organization of ecohydrologic processes and resulting vegetation patterns. In southwestern United States, climate conditions lead to terrain aspect- and elevation-controlled ecosystems, with mesic north-facing and xeric south-facing vegetation types; and changes in biodiversity as a function of elevation from shrublands in low desert elevations, to mixed grass/shrublands in mid elevations, and forests at high elevations and ridge tops. These observed patterns have been attributed to differences in topography-mediated local soil moisture availability, micro-climatology, and life history processes of plants that control chances of plant establishment and survival. While ecohydrologic models represent local vegetation dynamics in sufficient detail up to sub-hourly time scales, plant life history and competition for space and resources has not been adequately represented in models. In this study we develop an ecohydrologic cellular automata model within the Landlab component-based modeling framework. This model couples local vegetation dynamics (biomass production, death) and plant establishment and competition processes for resources and space. This model is used to study the vegetation organization in a semiarid New Mexico catchment where elevation and hillslope aspect play a defining role on plant types. Processes that lead to observed plant types across the landscape are examined by initializing the domain with randomly assigned plant types and systematically changing model parameters that couple plant response with soil moisture dynamics. Climate perturbation experiments are conducted to examine the plant response in space and time. Understanding the inherently transient ecohydrologic systems is critical to improve predictions of climate change impacts on ecosystems.

Evaluation of lipid peroxidation and antioxidant status on fenvalerate, nitrate and their co-exposure in Bubalus bubalis.

PubMed

Gill, Kamalpreet Kaur; Sandhu, Harpal Singh; Kaur, Rajdeep

2015-09-01

The toxic effects of pesticides and minerals have been explored in different species, but still there is paucity of information regarding their combined toxicological effects. The present investigation reports oxidative stress induced by oral subacute exposure to fenvalerate (1 mg/kg) and sodium nitrate (20 mg/kg) alone, as well as in combination daily for 21 days in buffalo calves. Fenvalerate exposure produced significant elevation in lipid peroxidation (LPO), glutathione peroxidase (GPx), while it produced significant decline in blood glutathione (GSH) levels, superoxide dismutase (SOD) and catalase (CAT). No significant alteration was evidenced in nitric oxide (NOx) levels. Oral exposure to sodium nitrate produced significant inclination in LPO and NOx, while on the other hand significant depreciation in SOD and CAT with no significant change in GPx activity. Combined exposure to fenvalerate and sodium nitrate produced severe effects with an appreciably more prominent elevation in extent of LPO and decline in blood GSH levels. Copyright © 2015 Elsevier Inc. All rights reserved.

A comparative appraisal of hydrological behavior of SRTM DEM at catchment level

NASA Astrophysics Data System (ADS)

Sharma, Arabinda; Tiwari, K. N.

2014-11-01

The Shuttle Radar Topography Mission (SRTM) data has emerged as a global elevation data in the past one decade because of its free availability, homogeneity and consistent accuracy compared to other global elevation dataset. The present study explores the consistency in hydrological behavior of the SRTM digital elevation model (DEM) with reference to easily available regional 20 m contour interpolated DEM (TOPO DEM). Analysis ranging from simple vertical accuracy assessment to hydrological simulation of the studied Maithon catchment, using empirical USLE model and semidistributed, physical SWAT model, were carried out. Moreover, terrain analysis involving hydrological indices was performed for comparative assessment of the SRTM DEM with respect to TOPO DEM. Results reveal that the vertical accuracy of SRTM DEM (±27.58 m) in the region is less than the specified standard (±16 m). Statistical analysis of hydrological indices such as topographic wetness index (TWI), stream power index (SPI), slope length factor (SLF) and geometry number (GN) shows a significant differences in hydrological properties of the two studied DEMs. Estimation of soil erosion potentials of the catchment and conservation priorities of microwatersheds of the catchment using SRTM DEM and TOPO DEM produce considerably different results. Prediction of soil erosion potential using SRTM DEM is far higher than that obtained using TOPO DEM. Similarly, conservation priorities determined using the two DEMs are found to be agreed for only 34% of microwatersheds of the catchment. ArcSWAT simulation reveals that runoff predictions are less sensitive to selection of the two DEMs as compared to sediment yield prediction. The results obtained in the present study are vital to hydrological analysis as it helps understanding the hydrological behavior of the DEM without being influenced by the model structural as well as parameter uncertainty. It also reemphasized that SRTM DEM can be a valuable dataset for hydrological analysis provided any error/uncertainty therein is being properly evaluated and characterized.

ArcticDEM; A Publically Available, High Resolution Elevation Model of the Arctic

NASA Astrophysics Data System (ADS)

Morin, Paul; Porter, Claire; Cloutier, Michael; Howat, Ian; Noh, Myoung-Jong; Willis, Michael; Bates, Brian; Willamson, Cathleen; Peterman, Kennith

2016-04-01

A Digital Elevation Model (DEM) of the Arctic is needed for a large number of reasons, including: measuring and understanding rapid, ongoing changes to the Arctic landscape resulting from climate change and human use and mitigation and adaptation planning for Arctic communities. The topography of the Arctic is more poorly mapped than most other regions of Earth due to logistical costs and the limits of satellite missions with low-latitude inclinations. A convergence of civilian, high-quality sub-meter stereo imagery; petascale computing and open source photogrammetry software has made it possible to produce a complete, very high resolution (2 to 8-meter posting), elevation model of the Arctic. A partnership between the US National Geospatial-intelligence Agency and a team led by the US National Science Foundation funded Polar Geospatial Center is using stereo imagery from DigitalGlobe's Worldview-1, 2 and 3 satellites and the Ohio State University's Surface Extraction with TIN-based Search-space Minimization (SETSM) software running on the University of Illinois's Blue Water supercomputer to address this challenge. The final product will be a seemless, 2-m posting digital surface model mosaic of the entire Arctic above 60 North including all of Alaska, Greenland and Kamchatka. We will also make available the more than 300,000 individual time-stamped DSM strip pairs that were used to assemble the mosaic. The Arctic DEM will have a vertical precision of better than 0.5m and can be used to examine changes in land surfaces such as those caused by permafrost degradation or the evolution of arctic rivers and floodplains. The data set can also be used to highlight changing geomorphology due to Earth surface mass transport processes occurring in active volcanic and glacial environments. When complete the ArcticDEM will catapult the Arctic from the worst to among the best mapped regions on Earth.

A model for collisionally induced disturbed structure in disk galaxies

NASA Technical Reports Server (NTRS)

Gerber, Richard A.; Lamb, Susan A.

1994-01-01

We derive analytic expressions, using the impulse and epicycle approximations, which describe the kinematic response of a disk galaxy following a collision with a second spherical galaxy which collides perpendicular to, but not through the center of, the disk. This model can reporduce the morphologies found in n-body experiments in which distant encounters produce two-armed spiral patterns and more central collisions produce rings in the disk galaxy, thereby confirming that simple kinematics can be used to describe the early evolution of these systems. Application of this procedure provides a convenient method with which to conduct parameter studies of these collisions. Comparison of the kinematic description with a fully self-gravitating, three-dimensional n-body/gasdynamics computer model shows that the disk galaxy's response is initially well represented by the kinematic model but that the self-gravity of the disk becomes important at longer times after the collision. The flows of gas and stars decouple from one another where stellar orbits cross, leaving regions of elevated gas density behind as the stars move freely past each other. If star formation rates are enhanced in these regions of high gas density, active star formation could be taking place where there is no corresponding dense feature in the old stellar population.

Estimation of Groundwater Radon in North Carolina Using Land Use Regression and Bayesian Maximum Entropy.

PubMed

Messier, Kyle P; Campbell, Ted; Bradley, Philip J; Serre, Marc L

2015-08-18

Radon ((222)Rn) is a naturally occurring chemically inert, colorless, and odorless radioactive gas produced from the decay of uranium ((238)U), which is ubiquitous in rocks and soils worldwide. Exposure to (222)Rn is likely the second leading cause of lung cancer after cigarette smoking via inhalation; however, exposure through untreated groundwater is also a contributing factor to both inhalation and ingestion routes. A land use regression (LUR) model for groundwater (222)Rn with anisotropic geological and (238)U based explanatory variables is developed, which helps elucidate the factors contributing to elevated (222)Rn across North Carolina. The LUR is also integrated into the Bayesian Maximum Entropy (BME) geostatistical framework to increase accuracy and produce a point-level LUR-BME model of groundwater (222)Rn across North Carolina including prediction uncertainty. The LUR-BME model of groundwater (222)Rn results in a leave-one out cross-validation r(2) of 0.46 (Pearson correlation coefficient = 0.68), effectively predicting within the spatial covariance range. Modeled results of (222)Rn concentrations show variability among intrusive felsic geological formations likely due to average bedrock (238)U defined on the basis of overlying stream-sediment (238)U concentrations that is a widely distributed consistently analyzed point-source data.

Ice elevation change from Swath Processing of CryoSat SARIn Mode Data

NASA Astrophysics Data System (ADS)

Foresta, Luca; Gourmelen, Noel; Shepherd, Andrew; Muir, Alan; Nienow, Pete

2015-04-01

Reference and repeat-observations of Glacier and Ice Sheet Margin (GISM) topography are critical to identify changes in ice elevation, provide estimates of mass gain or loss and thus quantify the contribution of the cryosphere to sea level rise (e.g. McMillan et al., 2014). The Synthetic Interferometric Radar Altimeter (SIRAL) onboard the ESA radar altimetry CryoSat (CS) mission has collected ice elevation measurements since 2010. The corresponding SARIn mode of operation, activated over GISM areas, provides high spatial resolution in the along-track direction while resolving the angular origin of echoes (i.e. across-track). The current ESA SARIn processor calculates the elevation of the Point Of Closest Approach (POCA) within each waveform and maps of elevation change in Antarctica and Greenland have been produced using the regular CS height product (McMillan et al., 2014; Helm et al., 2014). Data from the CS-SARIn mode has also been used to produce measurements of ice elevation beyond the POCA, also known as swath elevation (Hawley et al. 2009; Gray et al., 2013; ESA-STSE CryoTop project). Here we use the swath processing approach to generate maps of ice elevation change from selected regions around the margins of the Greenland and Antarctic Ice Sheets. We discuss the impact of the swath processing on the spatial resolution and precision of the resulting ice elevation field and compare our results to current dh/dt estimates. References: ESA STSE CryoTop project - http://www.stse-cryotop.org/ Gray L., Burgess D., Copland L., Cullen R., Galin N., Hawley R. and Helm V. Interferometric swath processing of Cryosat data for glacial ice topography. The Cryosphere, 7(6):1857-1867, December 2013. Hawley R.L., Shepherd A., Cullen R., Helm V. and WIngham D.J. Ice-sheet elevations from across-track processing of airborne interferometric radar altimetry. Geophysical Research Letters, 36(22):L22501, November 2009. Helm V., Humbert A. and Miller H. Elevation and elevation change of Greenland and Antarctica derived from CryoSat-2. The Cryosphere, 8(4):1539-1559, August 2014. McMillan M., Shepherd A., Sundal A., Briggs K., Muir A., Ridout A., Hogg A. and Wingham D. Increased ice losses from Antarctica detected by CryoSat-2. Geophysical Research Letters, pages 3899-3905, 2014.

Method for producing electricity from a fuel cell having solid-oxide ionic electrolyte

DOEpatents

Mason, David M.

1984-01-01

Stabilized quadrivalent cation oxide electrolytes are employed in fuel cells at elevated temperatures with a carbon and/or hydrogen containing fuel anode and an oxygen cathode. The fuel cell is operated at elevated temperatures with conductive metallic coatings as electrodes and desirably having the electrolyte surface blackened. Of particular interest as the quadrivalent oxide is zirconia.

The effects of elevated CO2 on cereal crop natural defenses and the potential implications for mycotoxin risk

USDA-ARS?s Scientific Manuscript database

Wheat and corn are an essential part of the world’s grain supply, but climate change has the potential to increase grain susceptibility to toxin producing fungal pathogens. While rising atmospheric [CO2] is a driving force of climate change, our understanding of how elevated [CO2] will effect grain ...

Automated UV-C mutagenesis of Kluyveromyces marxianus NRRL Y-1109 and selection for microaerophilic growth and ethanol production at elevated temperature on biomass sugars

USDA-ARS?s Scientific Manuscript database

The yeast Kluyveromyces marxianus is a potential microbial catalyst for producing ethanol from lignocellulosic substrates at elevated temperatures. To improve its growth and ethanol yield under anaerobic conditions, K. marxianus NRRL Y-1109 was irradiated with UV-C, and surviving cells were grown a...

Thyrotoxicosis presenting as hypogonadism: a case of central hyperthyroidism.

PubMed

Childress, R Dale; Qureshi, M Nauman; Kasparova, Meri; Oktaei, Hooman; Williams-Cleaves, Beverly; Solomon, Solomon S

2004-11-01

Herein, we present a case of central thyrotoxicosis with well-documented serial therapeutic interventions. Thyroid-stimulating hormone (TSH)-secreting pituitary tumors represent a rare cause of hyperthyroidism. It is being diagnosed more frequently with the third-generation TSH assay. Many conditions can produce normal or elevated TSH levels in combination with elevated thyroid hormone levels. The differential diagnosis includes resistance to thyroid hormone (RTH, Refetoff's syndrome), assay interference from anti-T4/T3 and heterophile antibodies, elevated or altered binding proteins, drugs affecting peripheral metabolism, and noncompliance with thyroid replacement therapy. In contrast to RTH, our patient presented had high alpha-subunit-to-TSH molar ratio, failed TSH response to thyrotropin-releasing hormone stimulation, and a large pituitary mass. Normal or high TSH in the presence of elevated T4 or T3 is a fairly common clinical scenario with many etiologic possibilities. This TSH-producing adenoma represents an unusual initial clinical presentation, as hypogonadism appeared before features of thyrotoxicosis were appreciated. This case represents the most modern therapeutic approach to the management of this rare disease. Our patient has done well on octreotide with control of thyrotoxicosis and an additional 30% shrinkage of his tumor mass.

SRTM Colored Height and Shaded Relief: Sredinnyy Khrebet, Kamchatka Peninsula, Russia

NASA Technical Reports Server (NTRS)

2001-01-01

The Kamchatka Peninsula in eastern Russia is shown in this scene created from a preliminary elevation model derived from the first data collected during the Shuttle Radar Topography Mission (SRTM) on February 12, 2000. Sredinnyy Khrebet, the mountain range that makes up the spine of the peninsula, is a chain of active volcanic peaks. Pleistocene and recent glaciers have carved the broad valleys and jagged ridges that are common here. The relative youth of the volcanism is revealed by the topography as infilling and smoothing of the otherwise rugged terrain by lava, ash, and pyroclastic flows, particularly surrounding the high peaks in the south central part of the image. Elevations here range from near sea level up to 2,618 meters (8,590 feet).

Two visualization methods were combined to produce this image: shading and color coding of topographic height. The shade image was derived by computing topographic slope in the north-south direction. Northern slopes appear bright and southern slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow, red, and magenta, to white at the highest elevations.

Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard Space Shuttle Endeavour, launched on February 11,2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense, and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC.

Size: 93.0 x 105.7 kilometers ( 57.7 x 65.6 miles) Location: 58.3 deg. North lat., 160.9 deg. East lon. Orientation: North toward the top Image Data: Shaded and colored SRTM elevation model Date Acquired: February 12, 2000

Sredinnyy Khrebet, Kamchatka Peninsula, Russia

NASA Technical Reports Server (NTRS)

2002-01-01

The Kamchatka Peninsula in eastern Russia is shown in this scene created from a preliminary elevation model derived from the first data collected during the Shuttle Radar Topography Mission (SRTM) on February 12, 2000. Sredinnyy Khrebet, the mountain range that makes up the spine of the peninsula, is a chain of active volcanic peaks. Pleistocene and recent glaciers have carved the broad valleys and jagged ridges that are common here. The relative youth of the volcanism is revealed by the topography as infilling and smoothing of the otherwise rugged terrain by lava, ash, and pyroclastic flows, particularly surrounding the high peaks in the south central part of the image. Elevations here range from near sea level up to 2,618 meters (8,590 feet). Two visualization methods were combined to produce this image: shading and color coding of topographic height. The shade image was derived by computing topographic slope in the north-south direction. Northern slopes appear bright and southern slopes appear dark. Color coding is directly related to topographic height, with green at the lower elevations, rising through yellow, red, and magenta, to white at the highest elevations. Elevation data used in this image were acquired by the Shuttle Radar Topography Mission (SRTM) aboard Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Imagery and Mapping Agency (NIMA) of the U.S. Department of Defense, and the German and Italian space agencies. It is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Earth Science Enterprise, Washington, DC. Size: 93.0 x 105.7 kilometers ( 57.7 x 65.6 miles) Location: 58.3 deg. North lat., 160.9 deg. East lon. Orientation: North toward the top Image Data: Shaded and colored SRTM elevation model Date Acquired: February 12, 2000 Image courtesy NASA/JPL/NIMA

A new, multi-resolution bedrock elevation map of the Greenland ice sheet

NASA Astrophysics Data System (ADS)

Griggs, J. A.; Bamber, J. L.; Grisbed Consortium

2010-12-01

Gridded bedrock elevation for the Greenland ice sheet has previously been constructed with a 5 km posting. The true resolution of the data set was, in places, however, considerably coarser than this due to the across-track spacing of ice-penetrating radar transects. Errors were estimated to be on the order of a few percent in the centre of the ice sheet, increasing markedly in relative magnitude near the margins, where accurate thickness is particularly critical for numerical modelling and other applications. We use new airborne and satellite estimates of ice thickness and surface elevation to determine the bed topography for the whole of Greenland. This is a dynamic product, which will be updated frequently as new data, such as that from NASA’s Operation Ice Bridge, becomes available. The University of Kansas has in recent years, flown an airborne ice-penetrating radar system with close flightline spacing over several key outlet glacier systems. This allows us to produce a multi-resolution bedrock elevation dataset with the high spatial resolution needed for ice dynamic modelling over these key outlet glaciers and coarser resolution over the more sparsely sampled interior. Airborne ice thickness and elevation from CReSIS obtained between 1993 and 2009 are combined with JPL/UCI/Iowa data collected by the WISE (Warm Ice Sounding Experiment) covering the marginal areas along the south west coast from 2009. Data collected in the 1970’s by the Technical University of Denmark were also used in interior areas with sparse coverage from other sources. Marginal elevation data from the ICESat laser altimeter and the Greenland Ice Mapping Program were used to help constrain the ice thickness and bed topography close to the ice sheet margin where, typically, the terrestrial observations have poor sampling between flight tracks. The GRISBed consortium currently consists of: W. Blake, S. Gogineni, A. Hoch, C. M. Laird, C. Leuschen, J. Meisel, J. Paden, J. Plummer, F. Rodriguez-Morales and L. Smith, CReSIS, University of Kansas; E. Rignot, JPL and University of California, Irvine; Y. Gim, JPL; J. Mouginot, University of California, Irvine; D. Kirchner, University of Iowa; I. Howat, Byrd Polar Research Center, Ohio State University; I. Joughin and B. Smith, University of Washington; T. Scambos, NSIDC; S. Martin, University of Washington; T. Wagner, NASA.

Determining and Interpreting Detailed Ice Surface Elevation Changes of the Glaciers in Upernavik Isstrøm, Northwest Greenland, 1985-2016

NASA Astrophysics Data System (ADS)

Wendler, L.; Csatho, B. M.; Schenk, A. F.

2017-12-01

The several distinct glaciers of Upernavik Isstrøm in NW Greenland exhibit variable thinning, retreat, and velocity behaviors, despite being in close proximity, draining into the same fjord, and experiencing similar climatic conditions. This study reconstructed the 1985-2016 surface elevation change history for each Upernavik glacier. The data sets used included altimetry data collected by NASA's ATM, LVIS, and ICESat systems and digital elevation models (DEMs) derived from 1985 aerial photographs; ASTER, SPOT, and Worldview-1 and 2 satellite stereo imagery. The Surface Elevation Reconstruction and Change detection (SERAC) program was used to combine the data and correct the DEMs for fusing with the altimetry data. The spatiotemporal pattern of ice surface change was partitioned into changes related to surface processes and ice dynamics. The resulting ice thickness change time series were compared to other data sets, such as bed elevation, SMB anomalies, runoff, as well as marginal retreat derived from satellite imagery corresponding to the ASTER DEMs, to investigate possible forcings causing the variable behavior of the glaciers. Major findings include detection of rapid dynamic thinning of glacier 1 between 2005 and 2006, during a period of a stable calving front position. Continuing thinning and speed-up led to a loss of contact with a pinning point causing a major retreat between 2007 and 2008. This sequence of events contradicts previously held hypotheses that major thinning was caused by reduced backstress when a long-lived floating tongue disintegrated. Also, our results show a period of large thinning on glacier 2 between 2010 and 2011, after the retreat of the front resulted in a loss of contact between the glacier and one of its flanking outcrops suggesting that reduction of lateral drag might have contributed to the thinning. While the study reinforces that bed topography is a major factor in controlling outlet glacier dynamic thinning, it also highlights the importance of other factors, such as variations in calving rates and lateral drag. The study produced improved surface elevation change histories of the Upernavik glaciers that are the most detailed and accurate to date and will be important for future numerical modeling studies of outlet glacier dynamic processes.

The use of multi temporal LiDAR to assess basin-scale erosion and deposition following the catastrophic January 2011 Lockyer flood, SE Queensland, Australia

NASA Astrophysics Data System (ADS)

Croke, Jacky; Todd, Peter; Thompson, Chris; Watson, Fiona; Denham, Robert; Khanal, Giri

2013-02-01

Advances in remote sensing and digital terrain processing now allow for a sophisticated analysis of spatial and temporal changes in erosion and deposition. Digital elevation models (DEMs) can now be constructed and differenced to produce DEMs of Difference (DoD), which are used to assess net landscape change for morphological budgeting. To date this has been most effectively achieved in gravel-bed rivers over relatively small spatial scales. If the full potential of the technology is to be realised, additional studies are required at larger scales and across a wider range of geomorphic features. This study presents an assessment of the basin-scale spatial patterns of erosion, deposition, and net morphological change that resulted from a catastrophic flood event in the Lockyer Creek catchment of SE Queensland (SEQ) in January 2011. Multitemporal Light Detection and Ranging (LiDAR) DEMs were used to construct a DoD that was then combined with a one-dimensional flow hydraulic model HEC-RAS to delineate five major geomorphic landforms, including inner-channel area, within-channel benches, macrochannel banks, and floodplain. The LiDAR uncertainties were quantified and applied together with a probabilistic representation of uncertainty thresholded at a conservative 95% confidence interval. The elevation change distribution (ECD) for the 100-km2 study area indicates a magnitude of elevation change spanning almost 10 m but the mean elevation change of 0.04 m confirms that a large part of the landscape was characterised by relatively low magnitude changes over a large spatial area. Mean elevation changes varied by geomorphic feature and only two, the within-channel benches and macrochannel banks, were net erosional with an estimated combined loss of 1,815,149 m3 of sediment. The floodplain was the zone of major net deposition but mean elevation changes approached the defined critical limit of uncertainty. Areal and volumetric ECDs for this extreme event provide a representative expression of the balance between erosion and deposition, and importantly sediment redistribution, which is extremely difficult to quantify using more traditional channel planform or cross-sectional surveys. The ability of LiDAR to make a rapid and accurate assessment of key geomorphic processes over large spatial scales contributes to our understanding of key processes and, as demonstrated here, to the assessment of major geomorphological hazards such as extreme flood events.

Three Dimensional Modeling via Photographs for Documentation of a Village Bath

NASA Astrophysics Data System (ADS)

Balta, H. B.; Hamamcioglu-Turan, M.; Ocali, O.

2013-07-01

The aim of this study is supporting the conceptual discussions of architectural restoration with three dimensional modeling of monuments based on photogrammetric survey. In this study, a 16th century village bath in Ulamış, Seferihisar, and Izmir is modeled for documentation. Ulamış is one of the historical villages within which Turkish population first settled in the region of Seferihisar - Urla. The methodology was tested on an antique monument; a bath with a cubical form. Within the limits of this study, only the exterior of the bath was modeled. The presentation scale for the bath was determined as 1 / 50, considering the necessities of designing structural interventions and architectural ones within the scope of a restoration project. The three dimensional model produced is a realistic document presenting the present situation of the ruin. Traditional plan, elevation and perspective drawings may be produced from the model, in addition to the realistic textured renderings and wireframe representations. The model developed in this study provides opportunity for presenting photorealistic details of historical morphologies in scale. Compared to conventional drawings, the renders based on the 3d models provide an opportunity for conceiving architectural details such as color, material and texture. From these documents, relatively more detailed restitution hypothesis can be developed and intervention decisions can be taken. Finally, the principles derived from the case study can be used for 3d documentation of historical structures with irregular surfaces.

Final Report: Archiving Data to Support Data Synthesis of DOE Sponsored Elevated CO 2 Experiments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Megonigal, James; Lu, Meng

Over the last three decades DOE made a large investment in field-scale experiments in order to understand the role of terrestrial ecosystems in the global carbon cycle, and forecast how carbon cycling will change over the next century. The Smithsonian Environmental Research Center received one of the first awards in this program and managed two long-term studies (25 years and 10 years) with a total of approximately $10 million of support from DOE, and many more millions leveraged from the Smithsonian Institution and agencies such as NSF. The present DOE grant was based on the premise that such a largemore » investment demands a proper synthesis effort so that the full potential of these experiments are realized through data analysis and modeling. The goal of the this grant was to archive legacy data from two major elevated carbon dioxide experiments in DOE databases, and to engage in synthesis activities using these data. Both goals were met. All datasets deemed a high priority for data synthesis and modeling were prepared for archiving and analysis. Many of these datasets were deposited in DOE’s CDIAC, while others are being held at the Oak Ridge National Lab and the Smithsonian Institution until they can be received by DOE’s new ESS-DIVE system at Berkeley Lab. Most of the effort was invested in researching and re-constituting high-quality data sets from a 30-year elevated CO 2 experiment. Using these data, the grant produced products that are already benefiting climate change science, including the publication of new coastal wetland allometry equations based on 9,771 observations, public posting of dozens of datasets, metadata and supporting codes from long-term experiments at the Global Change Research Wetland, and publication of two synthetic data papers on scrub oak forest responses to elevated CO 2. In addition, three papers are in review or nearing submission reporting unexpected long-term patterns in ecosystem responses to elevated CO 2 and nitrogen in a coastal wetland.« less

Fossil Chironomidae (Insecta: Diptera) as Paleothermometers in the African Tropics

NASA Astrophysics Data System (ADS)

Eggermont, H.; Heiri, O.; Russell, J.; Vuille, M.; Audenaert, L.; Klaassen, G.; Verschuren, D.

2008-12-01

Reconstruction of Africa's temperature history from natural climate archives such as lake sediments is essential to amend the current scarcity of information on natural tropical climate and ecosystem variability. Chironomids are well-established paleothermometers in north-temperate/boreal regions, but their potential in tropical lakes has never before been assessed. We surveyed sub-fossil chironomid assemblages in surface sediments from 65 lakes and permanent pools in southwestern Uganda and central/southern Kenya, spanning elevations between 489 and 4575 m asl. Using various subsets of lakes and corresponding Surface-Water Temperatures (SWTemp) and Mean Annual Air Temperatures (MATemp), we developed a series of inference models for quantitative paleotemperature reconstruction. Models using both low-, mid- and high-elevation sites suffer to some extent from the small number of samples between 2500 and 3500 m asl, and from the presence of ecologically distinct but morphologically indistinguishable taxa. Models confined to mountain sites produce poorer error statistics, but are less prone to the biogeographical and taxonomic complexities associated with long climatic gradients. Overall, error statistics compare favourably with those of inference models developed for temperate regions, indicating that fossil assemblages of African Chironomidae can be valuable indicators of past temperature change. We subsequently used these models to evaluate whether high-elevation lakes in the Rwenzori Mountains (>3000 m asl) have been impacted by climate warming in recent centuries by comparing temperatures inferred from chironomid assemblages in modern sediments with those derived from chironomid assemblages in sediments deposited within or briefly after the Little Ice Age (1270-1850 AD). Depending on the model used, between 44 and 63% of the 16 lakes studied indicate significantly warmer temperatures in recent times (corresponding with an average MATemp rise of 0.88 ° C, and average SWTemp rise of 1.33 ° C), while all but one of the other lakes show temperature changes that are statistically insignificant. We conclude that chironomid communities in Rwenzori lakes adequately record past temperature changes, with potential for evaluating the impacts of past air temperature variation on the long-term dynamics of the Rwenzori glaciers.

Probability of detecting atrazine/desethyl-atrazine and elevated concentrations of nitrate in ground water in Colorado

USGS Publications Warehouse

Rupert, Michael G.

2003-01-01

Draft Federal regulations may require that each State develop a State Pesticide Management Plan for the herbicides atrazine, alachlor, metolachlor, and simazine. Maps were developed that the State of Colorado could use to predict the probability of detecting atrazine and desethyl-atrazine (a breakdown product of atrazine) in ground water in Colorado. These maps can be incorporated into the State Pesticide Management Plan and can help provide a sound hydrogeologic basis for atrazine management in Colorado. Maps showing the probability of detecting elevated nitrite plus nitrate as nitrogen (nitrate) concentrations in ground water in Colorado also were developed because nitrate is a contaminant of concern in many areas of Colorado. Maps showing the probability of detecting atrazine and(or) desethyl-atrazine (atrazine/DEA) at or greater than concentrations of 0.1 microgram per liter and nitrate concentrations in ground water greater than 5 milligrams per liter were developed as follows: (1) Ground-water quality data were overlaid with anthropogenic and hydrogeologic data using a geographic information system to produce a data set in which each well had corresponding data on atrazine use, fertilizer use, geology, hydrogeomorphic regions, land cover, precipitation, soils, and well construction. These data then were downloaded to a statistical software package for analysis by logistic regression. (2) Relations were observed between ground-water quality and the percentage of land-cover categories within circular regions (buffers) around wells. Several buffer sizes were evaluated; the buffer size that provided the strongest relation was selected for use in the logistic regression models. (3) Relations between concentrations of atrazine/DEA and nitrate in ground water and atrazine use, fertilizer use, geology, hydrogeomorphic regions, land cover, precipitation, soils, and well-construction data were evaluated, and several preliminary multivariate models with various combinations of independent variables were constructed. (4) The multivariate models that best predicted the presence of atrazine/DEA and elevated concentrations of nitrate in ground water were selected. (5) The accuracy of the multivariate models was confirmed by validating the models with an independent set of ground-water quality data. (6) The multivariate models were entered into a geographic information system and the probability maps were constructed.

Adolescent activity-based anorexia increases anxiety-like behavior in adulthood.

PubMed

Kinzig, Kimberly P; Hargrave, Sara L

2010-09-01

Activity-based anorexia is a paradigm that induces increased physical activity, reduced food intake, and heightened activity of the hypothalamic-pituitary-adrenal axis in adult rats. To investigate whether experience with activity-based anorexia produced enduring effects on brain and behavior, female adolescent rats experienced activity-based anorexia during adolescence and were tested in adulthood for anxiety-like behavior on an elevated plus maze and in an open field. Analysis of elevated plus maze and open field behavior in adulthood revealed that rats that experienced activity-based anorexia during adolescence, but not rats that were simply food restricted, displayed increased anxiety-like behavior in adulthood. Plasma corticosterone and expression levels of corticotropin-releasing hormone mRNA in the hypothalamic paraventricular nucleus and in the central nucleus of the amygdala were significantly elevated in adult rats that had undergone activity-based anorexia in adolescence in response to the open field exposure, as compared to control rats. These data demonstrate enduring effects of adolescent activity-based anorexia on anxiety-like behavior and neuroendocrine factors critical in stress responsivity in adulthood. Furthermore, we demonstrate that activity-based anorexia during adolescence serves as a model whereby prolonged anxiety is induced, allowing for evaluation of the behavioral and neural correlates of mediating anxiety-like behaviors in adulthood. Copyright 2010 Elsevier Inc. All rights reserved.

Adolescent Activity-Based Anorexia Increases Anxiety-Like Behavior in Adulthood

PubMed Central

Kinzig, Kimberly P.; Hargrave, Sara L.

2010-01-01

Activity-based anorexia is a paradigm that induces increased physical activity, reduced food intake, and heightened activity of the hypothalamic-pituitary-adrenal axis in adult rats. To investigate whether experience with activity-based anorexia produced enduring effects on brain and behavior, female adolescent rats experienced activity-based anorexia during adolescence and were tested in adulthood for anxiety-like behavior on an elevated plus maze and in an open field. Analysis of elevated plus maze and open field behavior in adulthood revealed that rats that experienced activity-based anorexia during adolescence, but not rats that were simply food restricted, displayed increased anxiety-like behavior in adulthood. Plasma corticosterone and expression levels of corticotropin- releasing hormone mRNA in the hypothalamic paraventricular nucleus and in the central nucleus of the amygdala were significantly elevated in adult rats that had undergone activity-based anorexia in adolescence in response to the open field exposure, as compared to control rats. These data demonstrate enduring effects of adolescent activity-based anorexia on anxiety-like behavior and neuroendocrine factors critical in stress responsivity in adulthood. Furthermore, we demonstrate that activity-based anorexia during adolescence serves as a model whereby prolonged anxiety is induced, allowing for evaluation of the behavioral and neural correlates of mediating anxiety-like behaviors in adulthood. PMID:20566408

Integrating terrestrial LiDAR and stereo photogrammetry to map the Tolay lakebed in northern San Francisco Bay

USGS Publications Warehouse

Woo, Isa; Storesund,; Takekawa, John Y.; Gardiner, Rachel J.; Ehret,

2009-01-01

The Tolay Creek Watershed drains approximately 3,520 ha along the northern edge of San Francisco Bay. Surrounded by a mosaic of open space conservation easements and public wildlife areas, it is one of the only watersheds in this urbanized estuary that is protected from its headwaters to the bay. Tolay Lake is a seasonal, spring-fed lake found in the upper watershed that historically extended over 120 ha. Although the lakebed was farmed since the early 1860s, the majority of the lakebed was recently acquired by the Sonoma County Regional Parks Department to restore its natural habitat values. As part of the restoration planning process, we produced a digital elevation model (DEM) of the historic extent of Tolay Lake by integrating terrestrial LiDAR (light detection and ranging) and stereo photogrammetry datasets, and real-time kinematic (RTK) global positioning system (GPS) surveys. We integrated the data, generated a DEM of the lakebed and upland areas, and analyzed errors. The accuracy of the composite DEM was verified using spot elevations obtained from the RTK GPS. Thus, we found that by combining photogrammetry, terrestrial LiDAR, and RTK GPS, we created an accurate baseline elevation map to use in watershed restoration planning and design.

Right Ventricular Failure Post LVAD Implantation Corrected with Biventricular Support: An In Vitro Model.

PubMed

Shehab, Sajad; Allida, Sabine M; Davidson, Patricia M; Newton, Phillip J; Robson, Desiree; Jansz, Paul C; Hayward, Christopher S

Right ventricular failure after left ventricular assist device (LVAD) implantation is associated with high mortality. Management remains limited to pharmacologic therapy and temporary mechanical support. Delayed right ventricular assist device (RVAD) support after LVAD implantation is associated with poorer outcomes. With the advent of miniaturized, durable, continuous flow ventricular assist device systems, chronic RVAD and biventricular assist device (BiVAD) support has been used with some success. The purpose of this study was to assess combined BiVAD and LVAD with delayed RVAD support within a four-elemental mock circulatory loop (MCL) simulating the human cardiovascular system. Our hypothesis was that delayed continuous flow RVAD (RVAD) would produce similar hemodynamic and flow parameters to those of initial BiVAD support. Using the MCL, baseline biventricular heart failure with elevated right and left filling pressures with low cardiac output was simulated. The addition of LVAD within a biventricular configuration improved cardiac output somewhat, but was associated with persistent right heart failure with elevated right-sided filling pressures. The addition of an RVAD significantly improved LVAD outputs and returned filling pressures to normal throughout the circulation. In conclusion, RVAD support successfully restored hemodynamics and flow parameters of biventricular failure supported with isolated LVAD with persistent elevated right atrial pressure.

An investigation of the basic physics of irrigation in urology and the role of automated pump irrigation in cystoscopy.

PubMed

Chang, Dwayne; Manecksha, Rustom P; Syrrakos, Konstantinos; Lawrentschuk, Nathan

2012-01-01

To investigate the effects of height, external pressure, and bladder fullness on the flow rate in continuous, non-continuous cystoscopy and the automated irrigation fluid pumping system (AIFPS). Each experiment had two 2-litre 0.9% saline bags connected to a continuous, non-continuous cystoscope or AIFPS via irrigation tubing. Other equipment included height-adjustable drip poles, uroflowmetry devices, and model bladders. In Experiment 1, saline bags were elevated to measure the increment in flow rate. In Experiment 2, saline bags were placed under external pressures to evaluate the effect on flow rate. In Experiment 3, flow rate changes in response to variable bladder fullness were measured. Elevating saline bags caused an increase in flow rates, however the increment slowed down beyond a height of 80 cm. Increase in external pressure on saline bags elevated flow rates, but inconsistently. A fuller bladder led to a decrease in flow rates. In all experiments, the AIFPS posted consistent flow rates. Traditional irrigation systems were susceptible to changes in height of irrigation solution, external pressure application, and bladder fullness thus creating inconsistent flow rates. The AIFPS produced consistent flow rates and was not affected by any of the factors investigated in the study.

Increasing the utility of regional water table maps: a new method for estimating groundwater recharge

NASA Astrophysics Data System (ADS)

Gilmore, T. E.; Zlotnik, V. A.; Johnson, M.

2017-12-01

Groundwater table elevations are one of the most fundamental measurements used to characterize unconfined aquifers, groundwater flow patterns, and aquifer sustainability over time. In this study, we developed an analytical model that relies on analysis of groundwater elevation contour (equipotential) shape, aquifer transmissivity, and streambed gradient between two parallel, perennial streams. Using two existing regional water table maps, created at different times using different methods, our analysis of groundwater elevation contours, transmissivity and streambed gradient produced groundwater recharge rates (42-218 mm yr-1) that were consistent with previous independent recharge estimates from different methods. The three regions we investigated overly the High Plains Aquifer in Nebraska and included some areas where groundwater is used for irrigation. The three regions ranged from 1,500 to 3,300 km2, with either Sand Hills surficial geology, or Sand Hills transitioning to loess. Based on our results, the approach may be used to increase the value of existing water table maps, and may be useful as a diagnostic tool to evaluate the quality of groundwater table maps, identify areas in need of detailed aquifer characterization and expansion of groundwater monitoring networks, and/or as a first approximation before investing in more complex approaches to groundwater recharge estimation.

Lithospheric extension near Lake Mead, Nevada - A model for ductile flow in the lower crust

NASA Technical Reports Server (NTRS)

Kruse, Sarah; Mcnutt, Marcia; Phipps-Morgan, Jason; Royden, Leigh

1991-01-01

Small variations in gravity anomalies and topographic elevation observed in areas that have undergone highly variable amounts of upper crustal thinning can be satisfactorily explained by ductile flow of lower crustal material under the proper conditions. The boundary between the unextended Colorado Plateau and a strongly extended domain in the Basin and Range Province in the Lake Mead (Nevada) region is examined. Finite element modeling of Newtonian flow and power law creep shows that flow over the length scale of the eastern Basin and Range (500) km or more) corresponding to upper crustal extension by a factor of 1.4-3 over 10 million years requires effective viscosities less than 10 to the 18th - 10 to the 20th Pa s for ductile channels 10-25 km thick. Modeling suggests that these effective viscosities may be sustained by lower crustal material deforming at laboratory-derived power law creep rates. The longer-scale flow may require elevated crustal temperatures (more than 700 C), depending on the composition and material properties assumed. Under the boundary conditions assumed in this study the linear viscous flow models yield a satisfactory approximation to deformation by power law creep. This work suggests that flow in the lower crust may be a viable mechanism for producing small variations in total crustal thickness between strongly extended and less extended regions, and thereby explaining the relative uniformity in gravity and topography between such regions.

Monitoring, Modeling, and Diagnosis of Alkali-Silica Reaction in Small Concrete Samples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Agarwal, Vivek; Cai, Guowei; Gribok, Andrei V.

Assessment and management of aging concrete structures in nuclear power plants require a more systematic approach than simple reliance on existing code margins of safety. Structural health monitoring of concrete structures aims to understand the current health condition of a structure based on heterogeneous measurements to produce high-confidence actionable information regarding structural integrity that supports operational and maintenance decisions. This report describes alkali-silica reaction (ASR) degradation mechanisms and factors influencing the ASR. A fully coupled thermo-hydro-mechanical-chemical model developed by Saouma and Perotti by taking into consideration the effects of stress on the reaction kinetics and anisotropic volumetric expansion is presentedmore » in this report. This model is implemented in the GRIZZLY code based on the Multiphysics Object Oriented Simulation Environment. The implemented model in the GRIZZLY code is randomly used to initiate ASR in a 2D and 3D lattice to study the percolation aspects of concrete. The percolation aspects help determine the transport properties of the material and therefore the durability and service life of concrete. This report summarizes the effort to develop small-size concrete samples with embedded glass to mimic ASR. The concrete samples were treated in water and sodium hydroxide solution at elevated temperature to study how ingress of sodium ions and hydroxide ions at elevated temperature impacts concrete samples embedded with glass. Thermal camera was used to monitor the changes in the concrete sample and results are summarized.« less

Re-evaluation of the interrelationships among the behavioral tests in rats exposed to chronic unpredictable mild stress

PubMed Central

Hu, Congli; Luo, Ying; Wang, Hong; Kuang, Shengnan; Liang, Guojuan; Yang, Yang; Mai, Shaoshan; Yang, Junqing

2017-01-01

The chronic unpredictable mild stress model of depression has been widely used as an experimental tool to investigate human psychopathology. Our objective was to provide an update on the validity and reliability of the chronic unpredictable mild stress model, by analyzing the interrelationships among the indexes using stepwise discriminant analysis and Pearson correlation coefficient to examine the possible combinations. We evaluated the depressive rats in both the presence and the absence of chronic unpredictable mild stress, using weight change, percentage of sucrose preference, coat state, splash test, open-field test, elevated plus-maze test, forced swimming test, and Morris water maze test. The results showed that 6-week-long chronic unpredictable mild stress produces significant depression and anxiety-like behavior. The combination of body weight change, percentage of sucrose preference, coat state score, open-field score, grooming latency of splash test, immobility time in force swimming test, and platform crossing in the Morris water maze test can effectively discriminate between normal and chronic unpredictable mild stress rats. Strong interrelationships were noted among these indexes in both open-field test and elevated plus-maze test. In conclusion, there might be certain criteria for the combination of behavioral endpoints, which is advantageous to more effectively and reliably assess the chronic unpredictable mild stress induced depression model. PMID:28931086

Characterization of Tensile Properties, Limiting Strains, and Deep Drawing Behavior of AA5754-H22 Sheet at Elevated Temperature

NASA Astrophysics Data System (ADS)

Panicker, Sudhy S.; Singh, Har Govind; Panda, Sushanta Kumar; Dashwood, Richard

2015-11-01

Automotive industries are very much interested in characterization of formability improvement of aluminum alloys at elevated temperatures before designing tools, heating systems, and processing sequences for fabrication of auto-body panels by warm forming technology. In this study, tensile tests of AA5754-H22 aluminum alloy were carried out at five different temperatures and three different strain rates to investigate the deformation behavior correlating with Cowper-Symonds constitutive equation. Laboratory scale warm forming facilities were designed and fabricated to perform limiting dome height and deep drawing tests to evaluate forming limit strains and drawability of sheet metal at different tool temperatures. The forming limit strain and dome height improved significantly when both the die and punch were heated to 200 °C. Remarkable improvement in deep drawn cup depth was observed when die and punch temperatures were maintained at 200 and 30 °C, respectively, producing a non-isothermal temperature gradient of approximately 93 °C across the blank from flange to center. The forming behavior at different isothermal and non-isothermal conditions were predicted successfully using a thermo-mechanical FE model incorporating temperature-dependent properties in Barlat-89 yield criterion coupled with Cowper-Symonds hardening model, and the thinning/failure location in deformed cups were validated implementing the experimental limiting strains as damage model.

How light competition between plants affects their response to climate change.

PubMed

van Loon, Marloes P; Schieving, Feike; Rietkerk, Max; Dekker, Stefan C; Sterck, Frank; Anten, Niels P R

2014-09-01

How plants respond to climate change is of major concern, as plants will strongly impact future ecosystem functioning, food production and climate. Here, we investigated how vegetation structure and functioning may be influenced by predicted increases in annual temperatures and atmospheric CO2 concentration, and modeled the extent to which local plant-plant interactions may modify these effects. A canopy model was developed, which calculates photosynthesis as a function of light, nitrogen, temperature, CO2 and water availability, and considers different degrees of light competition between neighboring plants through canopy mixing; soybean (Glycine max) was used as a reference system. The model predicts increased net photosynthesis and reduced stomatal conductance and transpiration under atmospheric CO2 increase. When CO2 elevation is combined with warming, photosynthesis is increased more, but transpiration is reduced less. Intriguingly, when competition is considered, the optimal response shifts to producing larger leaf areas, but with lower stomatal conductance and associated vegetation transpiration than when competition is not considered. Furthermore, only when competition is considered are the predicted effects of elevated CO2 on leaf area index (LAI) well within the range of observed effects obtained by Free air CO2 enrichment (FACE) experiments. Together, our results illustrate how competition between plants may modify vegetation responses to climate change. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

An automated, open-source pipeline for mass production of digital elevation models (DEMs) from very-high-resolution commercial stereo satellite imagery

NASA Astrophysics Data System (ADS)

Shean, David E.; Alexandrov, Oleg; Moratto, Zachary M.; Smith, Benjamin E.; Joughin, Ian R.; Porter, Claire; Morin, Paul

2016-06-01

We adapted the automated, open source NASA Ames Stereo Pipeline (ASP) to generate digital elevation models (DEMs) and orthoimages from very-high-resolution (VHR) commercial imagery of the Earth. These modifications include support for rigorous and rational polynomial coefficient (RPC) sensor models, sensor geometry correction, bundle adjustment, point cloud co-registration, and significant improvements to the ASP code base. We outline a processing workflow for ˜0.5 m ground sample distance (GSD) DigitalGlobe WorldView-1 and WorldView-2 along-track stereo image data, with an overview of ASP capabilities, an evaluation of ASP correlator options, benchmark test results, and two case studies of DEM accuracy. Output DEM products are posted at ˜2 m with direct geolocation accuracy of <5.0 m CE90/LE90. An automated iterative closest-point (ICP) co-registration tool reduces absolute vertical and horizontal error to <0.5 m where appropriate ground-control data are available, with observed standard deviation of ˜0.1-0.5 m for overlapping, co-registered DEMs (n = 14, 17). While ASP can be used to process individual stereo pairs on a local workstation, the methods presented here were developed for large-scale batch processing in a high-performance computing environment. We are leveraging these resources to produce dense time series and regional mosaics for the Earth's polar regions.

New land surface digital elevation model covers the Earth

USGS Publications Warehouse

Gesch, Dean B.; Verdin, Kristine L.; Greenlee, Susan K.

1999-01-01

Land surface elevation around the world is reaching new heights—as far as its description and measurement goes. A new global digital elevation model (DEM) is being cited as a significant improvement in the quality of topographic data available for Earth science studies.Land surface elevation is one of the Earth's most fundamental geophysical properties, but the accuracy and detail with which it has been measured and described globally have been insufficient for many large-area studies. The new model, developed at the U.S. Geological Survey's (USGS) EROS Data Center (EDC), has changed all that.

Integrated research in constitutive modelling at elevated temperatures, part 1

NASA Technical Reports Server (NTRS)

Haisler, W. E.; Allen, D. H.

1986-01-01

Topics covered include: numerical integration techniques; thermodynamics and internal state variables; experimental lab development; comparison of models at room temperature; comparison of models at elevated temperature; and integrated software development.

Modelling the influence of elevation and snow regime on winter stream temperature in the rain-on-snow zone

NASA Astrophysics Data System (ADS)

Leach, J.; Moore, D.

2015-12-01

Winter stream temperature of coastal mountain catchments influences fish growth and development. Transient snow cover and advection associated with lateral throughflow inputs are dominant controls on stream thermal regimes in these regions. Existing stream temperature models lack the ability to properly simulate these processes. Therefore, we developed and evaluated a conceptual-parametric catchment-scale stream temperature model that includes the role of transient snow cover and lateral advection associated with throughflow. The model provided reasonable estimates of observed stream temperature at three test catchments. We used the model to simulate winter stream temperature for virtual catchments located at different elevations within the rain-on-snow zone. The modelling exercise examined stream temperature response associated with interactions between elevation, snow regime, and changes in air temperature. Modelling results highlight that the sensitivity of winter stream temperature response to changes in climate may be dependent on catchment elevation and landscape position.

Phage-Bacterial Dynamics with Spatial Structure: Self Organization around Phage Sinks Can Promote Increased Cell Densities

PubMed Central

Bull, James J.; Christensen, Kelly A.; Scott, Carly; Crandall, Cameron J.; Krone, Stephen M.

2018-01-01

Bacteria growing on surfaces appear to be profoundly more resistant to control by lytic bacteriophages than do the same cells grown in liquid. Here, we use simulation models to investigate whether spatial structure per se can account for this increased cell density in the presence of phages. A measure is derived for comparing cell densities between growth in spatially structured environments versus well mixed environments (known as mass action). Maintenance of sensitive cells requires some form of phage death; we invoke death mechanisms that are spatially fixed, as if produced by cells. Spatially structured phage death provides cells with a means of protection that can boost cell densities an order of magnitude above that attained under mass action, although the effect is sometimes in the opposite direction. Phage and bacteria self organize into separate refuges, and spatial structure operates so that the phage progeny from a single burst do not have independent fates (as they do with mass action). Phage incur a high loss when invading protected areas that have high cell densities, resulting in greater protection for the cells. By the same metric, mass action dynamics either show no sustained bacterial elevation or oscillate between states of low and high cell densities and an elevated average. The elevated cell densities observed in models with spatial structure do not approach the empirically observed increased density of cells in structured environments with phages (which can be many orders of magnitude), so the empirical phenomenon likely requires additional mechanisms than those analyzed here. PMID:29382134

Computer program simplifies selection of structural steel columns

NASA Technical Reports Server (NTRS)

Vissing, G. S.

1966-01-01

Computer program rapidly selects appropriate size steel columns and base plates for construction of multistory structures. The program produces a printed record containing the size of a section required at a particular elevation, the stress produced by the loads, and the allowable stresses for that section.

Using noble gas tracers to constrain a groundwater flow model with recharge elevations: A novel approach for mountainous terrain

USGS Publications Warehouse

Doyle, Jessica M.; Gleeson, Tom; Manning, Andrew H.; Mayer, K. Ulrich

2015-01-01

Environmental tracers provide information on groundwater age, recharge conditions, and flow processes which can be helpful for evaluating groundwater sustainability and vulnerability. Dissolved noble gas data have proven particularly useful in mountainous terrain because they can be used to determine recharge elevation. However, tracer-derived recharge elevations have not been utilized as calibration targets for numerical groundwater flow models. Herein, we constrain and calibrate a regional groundwater flow model with noble-gas-derived recharge elevations for the first time. Tritium and noble gas tracer results improved the site conceptual model by identifying a previously uncertain contribution of mountain block recharge from the Coast Mountains to an alluvial coastal aquifer in humid southwestern British Columbia. The revised conceptual model was integrated into a three-dimensional numerical groundwater flow model and calibrated to hydraulic head data in addition to recharge elevations estimated from noble gas recharge temperatures. Recharge elevations proved to be imperative for constraining hydraulic conductivity, recharge location, and bedrock geometry, and thus minimizing model nonuniqueness. Results indicate that 45% of recharge to the aquifer is mountain block recharge. A similar match between measured and modeled heads was achieved in a second numerical model that excludes the mountain block (no mountain block recharge), demonstrating that hydraulic head data alone are incapable of quantifying mountain block recharge. This result has significant implications for understanding and managing source water protection in recharge areas, potential effects of climate change, the overall water budget, and ultimately ensuring groundwater sustainability.

Four-dimensional Doppler ultrasound measurements in carotid bifurcation models: effect of concentric versus eccentric stenosis

NASA Astrophysics Data System (ADS)

Poepping, Tamie L.; Rankin, Richard N.; Holdsworth, David W.

2001-05-01

A unique in-vitro system has been developed that incorporates both realistic phantoms and flow. The anthropomorphic carotid phantoms are fabricated in agar with stenosis severity of 30% or 70% (by NASCET standards) and one of two geometric configurations- concentric or eccentric. The phantoms are perfused with a flow waveform that simulates normal common carotid flow. Pulsed Doppler ultrasound data are acquired at a 1 mm grid spacing throughout the lumen of the carotid bifurcation. To obtain a half-lumen volume, symmetric about the mid plane, requires a 13 hour acquisition over 3238 interrogation sites, producing 5.6 Gbytes of data. The spectral analysis produces estimates of parameters such as the peak velocity, mean velocity, spectral-broadening index, and turbulence intensity. Color-encoded or grayscale-encoded maps of these spectral parameters show distinctly different flow patterns resulting from stenoses of equal severity but different eccentricity. The most noticeable differences are seen in the volumes of the recirculation zones and the paths of the high-velocity jets. Elevated levels of turbulence intensity are also seen distal to the stenosis in the 70%-stenosed models.

Swiss Re Global Flood Hazard Zones: Know your flood risk

NASA Astrophysics Data System (ADS)

Vinukollu, R. K.; Castaldi, A.; Mehlhorn, J.

2012-12-01

Floods, among all natural disasters, have a great damage potential. On a global basis, there is strong evidence of increase in the number of people affected and economic losses due to floods. For example, global insured flood losses have increased by 12% every year since 1970 and this is expected to further increase with growing exposure in the high risk areas close to rivers and coastlines. Recently, the insurance industry has been surprised by the large extent of losses, because most countries lack reliable hazard information. One example has been the 2011 Thailand floods where millions of people were affected and the total economic losses were 30 billion USD. In order to assess the flood risk across different regions and countries, the flood team at Swiss Re based on a Geomorphologic Regression approach, developed in house and patented, produced global maps of flood zones. Input data for the study was obtained from NASA's Shuttle Radar Topographic Mission (SRTM) elevation data, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) and HydroSHEDS. The underlying assumptions of the approach are that naturally flowing rivers shape their channel and flood plain according to basin inherent forces and characteristics and that the flood water extent strongly depends on the shape of the flood plain. On the basis of the catchment characteristics, the model finally calculates the probability of a location to be flooded or not for a defined return period, which in the current study was set to 100 years. The data is produced at a 90-m resolution for latitudes 60S to 60N. This global product is now used in the insurance industry to inspect, inform and/or insure the flood risk across the world.

The ASTER Global Digital Elevation Model (GDEM) -for societal benefit -

NASA Astrophysics Data System (ADS)

Hato, M.; Tsu, H.; Tachikawa, T.; Abrams, M.; Bailey, B.

2009-12-01

The Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) Global Digital Elevation Model (GDEM) was developed jointly by the Ministry of Economy, Trade and Industry (METI) of Japan and the United States National Aeronautics and Space Administration (NASA) under the agreement of contribution to GEOSS and a public release was started on June 29th. ASTER GDEM can be downloaded to users from the Earth Remote Sensing Data Analysis Center (ERSDAC) of Japan and NASA’s Land Processes Distributed Active Archive Center (LP DAAC) free of charge. The ASTER instrument was built by METI and launched onboard NASA’s Terra spacecraft in December 1999. It has an along-track stereoscopic capability using its near infrared spectral band (NIR) and its nadir-viewing and backward-viewing telescopes to acquire stereo image data with a base-to-height ratio of 0.6. The ASTER GDEM was produced by applying newly-developed automated algorithm to more than 1.2 million NIR data Produced DEMs of all scene data was stacked after cloud masking and finally partitioned into 1° x 1°unit (called ‘tile’) data for convenience of distribution and handling by users. Before start of public distribution, ERSDAC and USGS/NASA together with many volunteers did validation and characterization by using a preliminary product of the ASTER GDEM. As a result of validation, METI and NASA evaluated that Version 1 of the ASTER GDEM has enough quality to be used as “experimental” or “research grade” data and consequently decided to release it. The ASTER GDEM covering almost all land area of from 83N to 83S on the earth represents as an important contribution to the global earth observation community. We will show our effort of development of ASTER GDEM and its accuracy and character.

Visualizing Coastal Erosion, Overwash and Coastal Flooding in New England

NASA Astrophysics Data System (ADS)

Young Morse, R.; Shyka, T.

2017-12-01

Powerful East Coast storms and their associated storm tides and large, battering waves can lead to severe coastal change through erosion and re-deposition of beach sediment. The United States Geological Survey (USGS) has modeled such potential for geological response using a storm-impact scale that compares predicted elevations of hurricane-induced water levels and associated wave action to known elevations of coastal topography. The resulting storm surge and wave run-up hindcasts calculate dynamic surf zone collisions with dune structures using discrete regime categories of; "collision" (dune erosion), "overwash" and "inundation". The National Weather Service (NWS) recently began prototyping this empirical technique under the auspices of the North Atlantic Regional Team (NART). Real-time erosion and inundation forecasts were expanded to include both tropical and extra-tropical cyclones along vulnerable beaches (hotspots) on the New England coast. Preliminary results showed successful predictions of impact during hurricane Sandy and several intense Nor'easters. The forecasts were verified using observational datasets, including "ground truth" reports from Emergency Managers and storm-based, dune profile measurements organized through a Maine Sea Grant partnership. In an effort to produce real-time visualizations of this forecast output, the Northeastern Regional Association of Coastal Ocean Observing Systems (NERACOOS) and the Gulf of Maine Research Institute (GMRI) partnered with NART to create graphical products of wave run-up levels for each New England "hotspot". The resulting prototype system updates the forecasts twice daily and allows users the ability to adjust atmospheric and sea state input into the calculations to account for model errors and forecast uncertainty. This talk will provide an overview of the empirical wave run-up calculations, the system used to produce forecast output and a demonstration of the new web based tool.

Upregulation of the endothelin A (ETA) receptor and its association with neurodegeneration in a rodent model of glaucoma.

PubMed

McGrady, Nolan R; Minton, Alena Z; Stankowska, Dorota L; He, Shaoqing; Jefferies, Hayden B; Krishnamoorthy, Raghu R

2017-03-01

Primary open angle glaucoma is a heterogeneous group of optic neuropathies that results in optic nerve degeneration and a loss of retinal ganglion cells (RGCs) ultimately causing blindness if allowed to progress. Elevation of intraocular pressure (IOP) is the most attributable risk factor for developing glaucoma and lowering of IOP is currently the only available therapy. However, despite lowering IOP, neurodegenerative effects persist in some patients. Hence, it would be beneficial to develop approaches to promote neuroprotection of RGCs in addition to IOP lowering therapies. The endothelin system is a key target for intervention against glaucomatous neurodegeneration. The endothelin family of peptides and receptors, particularly endothelin-1 (ET-1) and endothelin B (ET B ) receptor, has been shown to have neurodegenerative roles in glaucoma. The purpose of this study was to examine changes in endothelin A (ET A ) receptor protein expression in the retinas of adult male Brown Norway rats following IOP elevation by the Morrison's model of ocular hypertension and the impact of ET A receptor overexpression on RGC viability in vitro. IOP elevation was carried out in one eye of Brown Norway rats by injection of hypertonic saline through episcleral veins. After 2 weeks of IOP elevation, immunohistochemical analysis of retinal sections from rat eyes showed an increasing trend in immunostaining for ET A receptors in multiple retinal layers including the inner plexiform layer, ganglion cell layer and outer plexiform layer. Following 4 weeks of IOP elevation, a significant increase in immunostaining for ET A receptor expression was found in the retina, primarily in the inner plexiform layer and ganglion cells. A modest increase in staining for ET A receptors was also found in the outer plexiform layer in the retina of rats with IOP elevation. Cell culture studies showed that overexpression of ET A receptors in 661W cells as well as primary RGCs decreases cell viability, compared to empty vector transfected cells. Adeno-associated virus mediated overexpression of the ET A receptor produced an increase in the ET B receptor in primary RGCs. Elevated IOP results in an appreciable change in ET A receptor expression in the retina. Overexpression of the ET A receptor results in an overall decrease in cell viability, accompanied by an increase in ET B receptor levels, suggesting the involvement of both ET A and ET B receptors in mediating cell death. These findings raise possibilities for the development of ET A /ET B dual receptor antagonists as neuroprotective treatments for glaucomatous neuropathy.

Elevated Passive Continental Margins may form much Later than the time of Rifting

NASA Astrophysics Data System (ADS)

Chalmers, J. A.; Japsen, P.; Green, P. F.; Bonow, J.; Lidmar-Bergstrom, K.

2007-12-01

Many current models of the development of elevated passive continental margins assume that they are either the remains of foot-wall uplift at the time of rifting or due to underplating by magma from a plume or other mantle source. We have studied the rift and post-rift history of such a passive margin in West and South Greenland and have concluded that the present-day elevations developed 25-60 million years after cessation of rifting and local volcanism, suggesting that additional factors need to be considered when modelling such margins. The morphology of West Greenland is similar to that of other elevated passive margins ion many parts of the world. There are high-level, large-scale, quasi-planar landscapes (planation surfaces) at altitudes of 1-2 km cut by deeply incised valleys. The gradient from the highest ground to the coast is much steeper than that away from the coast. We combined analysis of the morphology of the landscape with studies of fission tracks and the preserved stratigraphic record both on- and off-shore. Rifting and the commencement of sea-floor spreading in the Early Paleogene was accompanied by voluminous high-temperature volcanism. Kilometer-scale uplift at the time of rifting was followed shortly afterwards by kilometer-scale subsidence and possibly by transgression of marine sediments across the rift margin. The present elevated margin formed during three episodes of uplift during the Neogene, 25-60 million years after the cessation of rifting and local volcanism. The quasi-planar planation surfaces presently at 1-2 km altitude are the end-products of denudation to near sea-level in the mid- and late Cenozoic and these surfaces were uplifted to their present altitudes during the Neogene events. Rivers then incised the summit surface to form valleys that were further enlarged and deepened by glaciers. Similar elevated margins exist all around the northern North Atlantic and in many other parts of the world; eastern North America, on both sides of the South Atlantic, western India, eastern Australia, and possibly in Antarctica. Our results show that we cannot simply assume that these elevations were produced either at the time of rifting or as underplating at the time of plume impact. There is, however, no general agreement as to what caused them and we suggest that the history of these margins need to be re-assessed in the light of our results.

Elevated Passive Continental Margins may form much Later than the time of Rifting

NASA Astrophysics Data System (ADS)

Chalmers, J. A.; Japsen, P.; Green, P. F.; Bonow, J.; Lidmar-Bergstrom, K.

2004-12-01

Many current models of the development of elevated passive continental margins assume that they are either the remains of foot-wall uplift at the time of rifting or due to underplating by magma from a plume or other mantle source. We have studied the rift and post-rift history of such a passive margin in West and South Greenland and have concluded that the present-day elevations developed 25-60 million years after cessation of rifting and local volcanism, suggesting that additional factors need to be considered when modelling such margins. The morphology of West Greenland is similar to that of other elevated passive margins ion many parts of the world. There are high-level, large-scale, quasi-planar landscapes (planation surfaces) at altitudes of 1-2 km cut by deeply incised valleys. The gradient from the highest ground to the coast is much steeper than that away from the coast. We combined analysis of the morphology of the landscape with studies of fission tracks and the preserved stratigraphic record both on- and off-shore. Rifting and the commencement of sea-floor spreading in the Early Paleogene was accompanied by voluminous high-temperature volcanism. Kilometer-scale uplift at the time of rifting was followed shortly afterwards by kilometer-scale subsidence and possibly by transgression of marine sediments across the rift margin. The present elevated margin formed during three episodes of uplift during the Neogene, 25-60 million years after the cessation of rifting and local volcanism. The quasi-planar planation surfaces presently at 1-2 km altitude are the end-products of denudation to near sea-level in the mid- and late Cenozoic and these surfaces were uplifted to their present altitudes during the Neogene events. Rivers then incised the summit surface to form valleys that were further enlarged and deepened by glaciers. Similar elevated margins exist all around the northern North Atlantic and in many other parts of the world; eastern North America, on both sides of the South Atlantic, western India, eastern Australia, and possibly in Antarctica. Our results show that we cannot simply assume that these elevations were produced either at the time of rifting or as underplating at the time of plume impact. There is, however, no general agreement as to what caused them and we suggest that the history of these margins need to be re-assessed in the light of our results.

Determining and Interpreting Detailed Ice Surface Elevation Changes of the Glaciers in Upernavik Isstrom, Northwest Greenland, 1985-2016

NASA Astrophysics Data System (ADS)

Wendler, Lindsay

The several distinct glaciers of Upernavik Isstrom, which drain a portion of the northwest margin of the Greenland Ice Sheet (GrIS), exhibit variable thinning, retreat, and velocity behaviors, despite being in such close proximity, draining into the same fjord, and experiencing similar climatic conditions. The goal of this study was to reconstruct, in as much detail as possible, a 1985-2016 surface elevation change history for each Upernavik glacier. Surface elevation datasets used in these reconstructions included laser altimetry data collected by several NASA systems (ATM, LVIS, ICESat) and digital elevation models (DEMs) derived from various sources (1985 aerial photographs; ASTER, SPOT, and Worldview-1 and 2 satellite stereo imagery). The Surface Elevation Reconstruction and Change detection (SERAC) program was used to combine the data and correct the DEMs for use in final reconstructions. The spatiotemporal pattern of ice surface change was analyzed and compared with other data sets, such as bed elevation, SMB anomalies, runoff, as well as marginal retreat derived from satellite imagery corresponding to the ASTER DEMs, to investigate possible forcings that may have influenced the variable behavior of the glaciers. We detected rapid thinning on glaciers 1, 2, and 5 and determined the timing of these thinning events. Major findings included detection of rapid dynamic thinning of glacier 1 between 2005 and 2006, during a period of a stable calving front position. Continued thinning and speed-up led to a loss of contact with a pinning point causing a major retreat between 2007 and 2008. This sequence of events contradicts previously held hypotheses that major thinning was caused by reduced backstress when a long-lived floating tongue disintegrated. Also, our results show a period of large thinning on glacier 2 between 2010 and 2011, after the retreat of the front resulted in a loss of contact between the glacier and one of its flanking outcrops, suggesting that reduction of lateral drag might have contributed to the thinning. While this study reinforces that bed topography is a major factor in controlling outlet glacier dynamic thinning, it also highlights the importance of other factors, such as variations in calving rates and lateral drag. My study produced improved surface elevation change histories of the Upernavik glaciers that are the most detailed and accurate to date and will be important for future numerical modeling studies of outlet glacier dynamic processes.

Trait-based diversification shifts reflect differential extinction among fossil taxa.

PubMed

Wagner, Peter J; Estabrook, George F

2014-11-18

Evolution provides many cases of apparent shifts in diversification associated with particular anatomical traits. Three general models connect these patterns to anatomical evolution: (i) elevated net extinction of taxa bearing particular traits, (ii) elevated net speciation of taxa bearing particular traits, and (iii) elevated evolvability expanding the range of anatomies available to some species. Trait-based diversification shifts predict elevated hierarchical stratigraphic compatibility (i.e., primitive→derived→highly derived sequences) among pairs of anatomical characters. The three specific models further predict (i) early loss of diversity for taxa retaining primitive conditions (elevated net extinction), (ii) increased diversification among later members of a clade (elevated net speciation), and (iii) increased disparity among later members in a clade (elevated evolvability). Analyses of 319 anatomical and stratigraphic datasets for fossil species and genera show that hierarchical stratigraphic compatibility exceeds the expectations of trait-independent diversification in the vast majority of cases, which was expected if trait-dependent diversification shifts are common. Excess hierarchical stratigraphic compatibility correlates with early loss of diversity for groups retaining primitive conditions rather than delayed bursts of diversity or disparity across entire clades. Cambrian clades (predominantly trilobites) alone fit null expectations well. However, it is not clear whether evolution was unusual among Cambrian taxa or only early trilobites. At least among post-Cambrian taxa, these results implicate models, such as competition and extinction selectivity/resistance, as major drivers of trait-based diversification shifts at the species and genus levels while contradicting the predictions of elevated net speciation and elevated evolvability models.

Assessment of Required Accuracy of Digital Elevation Data for Hydrologic Modeling

NASA Technical Reports Server (NTRS)

Kenward, T.; Lettenmaier, D. P.

1997-01-01

The effect of vertical accuracy of Digital Elevation Models (DEMs) on hydrologic models is evaluated by comparing three DEMs and resulting hydrologic model predictions applied to a 7.2 sq km USDA - ARS watershed at Mahantango Creek, PA. The high resolution (5 m) DEM was resempled to a 30 m resolution using method that constrained the spatial structure of the elevations to be comparable with the USGS and SIR-C DEMs. This resulting 30 m DEM was used as the reference product for subsequent comparisons. Spatial fields of directly derived quantities, such as elevation differences, slope, and contributing area, were compared to the reference product, as were hydrologic model output fields derived using each of the three DEMs at the common 30 m spatial resolution.

Improving ecophysiological simulation models to predict the impact of elevated atmospheric CO2 concentration on crop productivity

PubMed Central

Yin, Xinyou

2013-01-01

Background Process-based ecophysiological crop models are pivotal in assessing responses of crop productivity and designing strategies of adaptation to climate change. Most existing crop models generally over-estimate the effect of elevated atmospheric [CO2], despite decades of experimental research on crop growth response to [CO2]. Analysis A review of the literature indicates that the quantitative relationships for a number of traits, once expressed as a function of internal plant nitrogen status, are altered little by the elevated [CO2]. A model incorporating these nitrogen-based functional relationships and mechanisms simulated photosynthetic acclimation to elevated [CO2], thereby reducing the chance of over-estimating crop response to [CO2]. Robust crop models to have small parameterization requirements and yet generate phenotypic plasticity under changing environmental conditions need to capture the carbon–nitrogen interactions during crop growth. Conclusions The performance of the improved models depends little on the type of the experimental facilities used to obtain data for parameterization, and allows accurate projections of the impact of elevated [CO2] and other climatic variables on crop productivity. PMID:23388883

HIGH PRESSURE COAL COMBUSTON KINETICS PROJECT

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stefano Orsino

As part of the U.S. Department of Energy (DoE) initiative to improve the efficiency of coal-fired power plants and reduce the pollution generated by these facilities, DOE has funded the High-Pressure Coal Combustion Kinetics (HPCCK) Projects. A series of laboratory experiments were conducted on selected pulverized coals at elevated pressures with the specific goals to provide new data for pressurized coal combustion that will help extend to high pressure and validate models for burnout, pollutant formation, and generate samples of solid combustion products for analyses to fill crucial gaps in knowledge of char morphology and fly ash formation. Two seriesmore » of high-pressure coal combustion experiments were performed using SRI's pressurized radiant coal flow reactor. The first series of tests characterized the near burner flame zone (NBFZ). Three coals were tested, two high volatile bituminous (Pittsburgh No.8 and Illinois No.6), and one sub-bituminous (Powder River Basin), at pressures of 1, 2, and 3 MPa (10, 20, and 30 atm). The second series of experiments, which covered high-pressure burnout (HPBO) conditions, utilized a range of substantially longer combustion residence times to produce char burnout levels from 50% to 100%. The same three coals were tested at 1, 2, and 3 MPa, as well as at 0.2 MPa. Tests were also conducted on Pittsburgh No.8 coal in CO2 entrainment gas at 0.2, 1, and 2 MPa to begin establishing a database of experiments relevant to carbon sequestration techniques. The HPBO test series included use of an impactor-type particle sampler to measure the particle size distribution of fly ash produced under complete burnout conditions. The collected data have been interpreted with the help of CFD and detailed kinetics simulation to extend and validate devolatilization, char combustion and pollutant model at elevated pressure. A global NOX production sub-model has been proposed. The submodel reproduces the performance of the detailed chemical reaction mechanism for the NBFZ tests.« less

Discharges of produced waters from oil and gas extraction via wastewater treatment plants are sources of disinfection by-products to receiving streams.

PubMed

Hladik, Michelle L; Focazio, Michael J; Engle, Mark

2014-01-01

Fluids co-produced with oil and gas production (produced waters) are often brines that contain elevated concentrations of bromide. Bromide is an important precursor of several toxic disinfection by-products (DBPs) and the treatment of produced water may lead to more brominated DBPs. To determine if wastewater treatment plants that accept produced waters discharge greater amounts of brominated DBPs, water samples were collected in Pennsylvania from four sites along a large river including an upstream site, a site below a publicly owned wastewater treatment plant (POTW) outfall (does not accept produced water), a site below an oil and gas commercial wastewater treatment plant (CWT) outfall, and downstream of the POTW and CWT. Of 29 DBPs analyzed, the site at the POTW outfall had the highest number detected (six) ranging in concentration from 0.01 to 0.09 μg L(-1) with a similar mixture of DBPs that have been detected at POTW outfalls elsewhere in the United States. The DBP profile at the CWT outfall was much different, although only two DBPs, dibromochloronitromethane (DBCNM) and chloroform, were detected, DBCNM was found at relatively high concentrations (up to 8.5 μg L(-1)). The water at the CWT outfall also had a mixture of inorganic and organic precursors including elevated concentrations of bromide (75 mg L(-1)) and other organic DBP precursors (phenol at 15 μg L(-1)). To corroborate these DBP results, samples were collected in Pennsylvania from additional POTW and CWT outfalls that accept produced waters. The additional CWT also had high concentrations of DBCNM (3.1 μg L(-1)) while the POTWs that accept produced waters had elevated numbers (up to 15) and concentrations of DBPs, especially brominated and iodinated THMs (up to 12 μg L(-1) total THM concentration). Therefore, produced water brines that have been disinfected are potential sources of DBPs along with DBP precursors to streams wherever these wastewaters are discharged. © 2013.

Evaluation of the US DOE's conceptual model of hydrothermal activity at Yucca Mountain, Nevada

NASA Astrophysics Data System (ADS)

Dublyansky, Y. V.

2014-08-01

A unique conceptual model describing the conductive heating of rocks in the thick unsaturated zone of Yucca Mountain, Nevada by a silicic pluton emplaced several kilometers away is accepted by the US Department of Energy (DOE) as an explanation of the elevated depositional temperatures measured in fluid inclusions in secondary fluorite and calcite. Acceptance of this model allowed the DOE to keep from considering hydrothermal activity in the performance assessment of the proposed high-level nuclear waste disposal facility. The evaluation presented in this paper shows that no computational modeling results have yet produced a satisfactory match with the empirical benchmark data, specifically with age and fluid inclusion data that indicate high temperatures (up to ca. 80 °C) in the unsaturated zone of Yucca Mountain. Auxiliary sub-models complementing the DOE model, as well as observations at a natural analog site, have also been evaluated. Summarily, the model cannot be considered as validated. Due to the lack of validation, the reliance on this model must be discontinued and the appropriateness of decisions which rely on this model must be re-evaluated.

Mapping boreal forest biomass from a SRTM and TanDEM-X based on canopy height model and Landsat spectral indices

NASA Astrophysics Data System (ADS)

Sadeghi, Yaser; St-Onge, Benoît; Leblon, Brigitte; Prieur, Jean-François; Simard, Marc

2018-06-01

We propose a method for mapping above-ground biomass (AGB) (Mg ha-1) in boreal forests based predominantly on Landsat 8 images and on canopy height models (CHM) generated using interferometric synthetic aperture radar (InSAR) from the Shuttle Radar Topographic Mission (SRTM) and the TanDEM-X mission. The original SRTM digital elevation model (DEM) was corrected by modelling the respective effects of landform and land cover on its errors and then subtracted from a TanDEM-X DSM to produce a SAR CHM. Among all the landform factors, the terrain curvature had the largest effect on SRTM elevation errors, with a r2 of 0.29. The NDSI was the best predictor of the residual SRTM land cover error, with a r2 of 0.30. The final SAR CHM had a RMSE of 2.45 m, with a bias of 0.07 m, compared to a lidar-based CHM. An AGB prediction model was developed based on a combination of the SAR CHM, TanDEM-X coherence, Landsat 8 NDVI, and other vegetation indices of RVI, DVI, GRVI, EVI, LAI, GNDVI, SAVI, GVI, Brightness, Greenness, and Wetness. The best results were obtained using a Random forest regression algorithm, at the stand level, yielding a RMSE of 26 Mg ha-1 (34% of average biomass), with a r2 of 0.62. This method has the potential of creating spatially continuous biomass maps over entire biomes using only spaceborne sensors and requiring only low-intensity calibration.

A Candida guilliermondii lysine hyperproducer capable of elevated citric acid production.

PubMed

West, Thomas P

2016-05-01

A mutant of the yeast Candida guilliermondii ATCC 9058 exhibiting elevated citric acid production was isolated based upon its ability to overproduce lysine. This method involved the use of a solid medium containing a combination of lysine analogues to identify a mutant that produced a several-fold higher lysine level compared to its parent strain using glucose or glycerol as a carbon source. The mutant strain was also capable of producing more than a fivefold higher citric acid level on glycerol as a carbon source compared to its parent strain. It was concluded that the screening of yeast lysine hyperproducer strains could provide a rapid approach to isolate yeast citric acid hyperproducer strains.

Advanced use of tissue adhesive in hair transplantation.

PubMed

Elliott, R M; Thomas, R A; True, R H

1993-09-01

Cobblestoning is an unsightly result of graft elevation in the recipient site after hair transplantation. To describe the use of tissue adhesives for the avoidance of cobblestoning. The long-term cosmetic appearance of hair transplants may be improved through the use of cyanoacrylate adhesives is the virtual elimination of the common problem of graft elevation or cobblestoning, which produces an unsightly bumpiness in the recipient area. The choice of type of adhesive and the method of application are central to successful use of this technique. The indirect benefits of elimination of the need for postoperative bandages and restrictions in activities couple with the cosmetic results to produce a high degree of patient satisfaction.

Attributes for NHDPlus Catchments (Version 1.1): Basin Characteristics, 2002

USGS Publications Warehouse

Wieczorek, Michael; LaMotte, Andrew E.

2010-01-01

This data set represents basin characteristics, compiled for every catchment in NHDPlus for the conterminous United States. These characteristics are basin shape index, stream density, sinuosity, mean elevation, mean slope, and number of road-stream crossings. The source data sets are the U.S. Environmental Protection Agency's NHDPlus and the U.S. Census Bureau's TIGER/Line Files. The NHDPlus Version 1.1 is an integrated suite of application-ready geospatial datasets that incorporates many of the best features of the National Hydrography Dataset (NHD) and the National Elevation Dataset (NED). The NHDPlus includes a stream network (based on the 1:100,00-scale NHD), improved networking, naming, and value-added attributes (VAAs). NHDPlus also includes elevation-derived catchments (drainage areas) produced using a drainage enforcement technique first widely used in New England, and thus referred to as "the New England Method." This technique involves "burning in" the 1:100,000-scale NHD and when available building "walls" using the National Watershed Boundary Dataset (WBD). The resulting modified digital elevation model (HydroDEM) is used to produce hydrologic derivatives that agree with the NHD and WBD. Over the past two years, an interdisciplinary team from the U.S. Geological Survey (USGS), and the U.S. Environmental Protection Agency (USEPA), and contractors, found that this method produces the best quality NHD catchments using an automated process (USEPA, 2007). The NHDPlus dataset is organized by 18 Production Units that cover the conterminous United States. The NHDPlus version 1.1 data are grouped by the U.S. Geologic Survey's Major River Basins (MRBs, Crawford and others, 2006). MRB1, covering the New England and Mid-Atlantic River basins, contains NHDPlus Production Units 1 and 2. MRB2, covering the South Atlantic-Gulf and Tennessee River basins, contains NHDPlus Production Units 3 and 6. MRB3, covering the Great Lakes, Ohio, Upper Mississippi, and Souris-Red-Rainy River basins, contains NHDPlus Production Units 4, 5, 7 and 9. MRB4, covering the Missouri River basins, contains NHDPlus Production Units 10-lower and 10-upper. MRB5, covering the Lower Mississippi, Arkansas-White-Red, and Texas-Gulf River basins, contains NHDPlus Production Units 8, 11 and 12. MRB6, covering the Rio Grande, Colorado and Great Basin River basins, contains NHDPlus Production Units 13, 14, 15 and 16. MRB7, covering the Pacific Northwest River basins, contains NHDPlus Production Unit 17. MRB8, covering California River basins, contains NHDPlus Production Unit 18.

Feature extraction from multiple data sources using genetic programming

NASA Astrophysics Data System (ADS)

Szymanski, John J.; Brumby, Steven P.; Pope, Paul A.; Eads, Damian R.; Esch-Mosher, Diana M.; Galassi, Mark C.; Harvey, Neal R.; McCulloch, Hersey D.; Perkins, Simon J.; Porter, Reid B.; Theiler, James P.; Young, Aaron C.; Bloch, Jeffrey J.; David, Nancy A.

2002-08-01

Feature extraction from imagery is an important and long-standing problem in remote sensing. In this paper, we report on work using genetic programming to perform feature extraction simultaneously from multispectral and digital elevation model (DEM) data. We use the GENetic Imagery Exploitation (GENIE) software for this purpose, which produces image-processing software that inherently combines spatial and spectral processing. GENIE is particularly useful in exploratory studies of imagery, such as one often does in combining data from multiple sources. The user trains the software by painting the feature of interest with a simple graphical user interface. GENIE then uses genetic programming techniques to produce an image-processing pipeline. Here, we demonstrate evolution of image processing algorithms that extract a range of land cover features including towns, wildfire burnscars, and forest. We use imagery from the DOE/NNSA Multispectral Thermal Imager (MTI) spacecraft, fused with USGS 1:24000 scale DEM data.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Szymanski, J. J.; Brumby, Steven P.; Pope, P. A.

Feature extration from imagery is an important and long-standing problem in remote sensing. In this paper, we report on work using genetic programming to perform feature extraction simultaneously from multispectral and digital elevation model (DEM) data. The tool used is the GENetic Imagery Exploitation (GENIE) software, which produces image-processing software that inherently combines spatial and spectral processing. GENIE is particularly useful in exploratory studies of imagery, such as one often does in combining data from multiple sources. The user trains the software by painting the feature of interest with a simple graphical user interface. GENIE then uses genetic programming techniquesmore » to produce an image-processing pipeline. Here, we demonstrate evolution of image processing algorithms that extract a range of land-cover features including towns, grasslands, wild fire burn scars, and several types of forest. We use imagery from the DOE/NNSA Multispectral Thermal Imager (MTI) spacecraft, fused with USGS 1:24000 scale DEM data.« less

Using a GIS to link digital spatial data and the precipitation-runoff modeling system, Gunnison River Basin, Colorado

USGS Publications Warehouse

Battaglin, William A.; Kuhn, Gerhard; Parker, Randolph S.

1993-01-01

The U.S. Geological Survey Precipitation-Runoff Modeling System, a modular, distributed-parameter, watershed-modeling system, is being applied to 20 smaller watersheds within the Gunnison River basin. The model is used to derive a daily water balance for subareas in a watershed, ultimately producing simulated streamflows that can be input into routing and accounting models used to assess downstream water availability under current conditions, and to assess the sensitivity of water resources in the basin to alterations in climate. A geographic information system (GIS) is used to automate a method for extracting physically based hydrologic response unit (HRU) distributed parameter values from digital data sources, and for the placement of those estimates into GIS spatial datalayers. The HRU parameters extracted are: area, mean elevation, average land-surface slope, predominant aspect, predominant land-cover type, predominant soil type, average total soil water-holding capacity, and average water-holding capacity of the root zone.

A stochastic, evolutionary model for range shifts and richness on tropical elevational gradients under Quaternary glacial cycles

PubMed Central

Colwell, Robert K.; Rangel, Thiago F.

2010-01-01

Quaternary glacial–interglacial cycles repeatedly forced thermal zones up and down the slopes of mountains, at all latitudes. Although no one doubts that these temperature cycles have left their signature on contemporary patterns of geography and phylogeny, the relative roles of ecology and evolution are not well understood, especially for the tropics. To explore key mechanisms and their interactions in the context of chance events, we constructed a geographical range-based, stochastic simulation model that incorporates speciation, anagenetic evolution, niche conservatism, range shifts and extinctions under late Quaternary temperature cycles along tropical elevational gradients. In the model, elevational patterns of species richness arise from the differential survival of founder lineages, consolidated by speciation and the inheritance of thermal niche characteristics. The model yields a surprisingly rich variety of realistic patterns of phylogeny and biogeography, including close matches to a variety of contemporary elevational richness profiles from an elevational transect in Costa Rica. Mountaintop extinctions during interglacials and lowland extinctions at glacial maxima favour mid-elevation lineages, especially under the constraints of niche conservatism. Asymmetry in temperature (greater duration of glacial than of interglacial episodes) and in lateral area (greater land area at low than at high elevations) have opposing effects on lowland extinctions and the elevational pattern of species richness in the model—and perhaps in nature, as well. PMID:20980317

Clinical characteristics and current treatment of glaucoma.

PubMed

Cohen, Laura P; Pasquale, Louis R

2014-06-02

Glaucoma is a neurodegenerative disorder in which degenerating retinal ganglion cells (RGC) produce significant visual disability. Clinically, glaucoma refers to an array of conditions associated with variably elevated intraocular pressure (IOP) that contributes to RGC loss via mechanical stress, vascular abnormalities, and other mechanisms, such as immune phenomena. The clinical diagnosis of glaucoma requires assessment of the ocular anterior segment with slit lamp biomicroscopy, which allows the clinician to recognize signs of conditions that can produce elevated IOP. After measurement of IOP, a specialized prismatic lens called a gonioscope is used to determine whether the angle is physically open or closed. The structural manifestation of RGC loss is optic nerve head atrophy and excavation of the neuroretinal rim tissue. Treatment is guided by addressing secondary causes for elevated IOP (such as inflammation, infection, and ischemia) whenever possible. Subsequently, a variety of medical, laser, and surgical options are used to achieve a target IOP. Copyright © 2014 Cold Spring Harbor Laboratory Press; all rights reserved.

Allometry, growth and architecture of two Solidago species in elevated CO{sub 2} environment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choung, Yeon-Sook; Bazzaz, F.A.

1995-06-01

We grew the common old-field rhizomatous perennials, Solidago canadensis and S. gigantea, which have compact and relatively spreading clonal structure respectively, in ambient and doubled CO{sub 2} environments to study the influence of elevated CO{sub 2} on the growth, allometry and architecture of these two species. Most growth parameters were enhanced significantly by high CO{sub 2} in both species, but there were no significant differences in the allometric relationships between plant parts except for allocation to rhizomes. Unlike allocation to other plant organs, rhizome growth was directly affected by elevated CO{sub 2}. In a high CO{sub 2}, S. canadensis, whichmore » has short rhizomes, allocated more biomass to new rhizomes, and produced longer new rhizomes, while S. gigantea, which has longer rhizomes, produced shorter and more branched rhizomes, forming a more aggregated clone. If global change will lead to expansion of clonal perennials when trees die, S. canadensis may expand faster than S. gigantea.« less

Microencapsuling aerial conidia of Trichoderma harzianum through spray drying at elevated temperatures

USDA-ARS?s Scientific Manuscript database

Trichoderma conidia are mostly produced by solid fermentation systems. Inoculum is produced by liquid culturing, and then transferred to solid substrate for aerial conidial production. Aerial conidia of T. harzianum are hydrophilic in nature, and it is difficult to separate them from the solid subst...

Development of Elevation and Relief Databases for ICESat-2/ATLAS Receiver Algorithms

NASA Astrophysics Data System (ADS)

Leigh, H. W.; Magruder, L. A.; Carabajal, C. C.; Saba, J. L.; Urban, T. J.; Mcgarry, J.; Schutz, B. E.

2013-12-01

The Advanced Topographic Laser Altimeter System (ATLAS) is planned to launch onboard NASA's ICESat-2 spacecraft in 2016. ATLAS operates at a wavelength of 532 nm with a laser repeat rate of 10 kHz and 6 individual laser footprints. The satellite will be in a 500 km, 91-day repeat ground track orbit at an inclination of 92°. A set of onboard Receiver Algorithms has been developed to reduce the data volume and data rate to acceptable levels while still transmitting the relevant ranging data. The onboard algorithms limit the data volume by distinguishing between surface returns and background noise and selecting a small vertical region around the surface return to be included in telemetry. The algorithms make use of signal processing techniques, along with three databases, the Digital Elevation Model (DEM), the Digital Relief Map (DRM), and the Surface Reference Mask (SRM), to find the signal and determine the appropriate dynamic range of vertical data surrounding the surface for downlink. The DEM provides software-based range gating for ATLAS. This approach allows the algorithm to limit the surface signal search to the vertical region between minimum and maximum elevations provided by the DEM (plus some margin to account for uncertainties). The DEM is constructed in a nested, three-tiered grid to account for a hardware constraint limiting the maximum vertical range to 6 km. The DRM is used to select the vertical width of the telemetry band around the surface return. The DRM contains global values of relief calculated along 140 m and 700 m ground track segments consistent with a 92° orbit. The DRM must contain the maximum value of relief seen in any given area, but must be as close to truth as possible as the DRM directly affects data volume. The SRM, which has been developed independently from the DEM and DRM, is used to set parameters within the algorithm and select telemetry bands for downlink. Both the DEM and DRM are constructed from publicly available digital elevation models. No elevation models currently exist that provide global coverage at a sufficient resolution, so several regional models have been mosaicked together to produce global databases. In locations where multiple data sets are available, evaluations have been made to determine the optimal source for the databases, primarily based on resolution and accuracy. Separate procedures for calculating relief were developed for high latitude (>60N/S) regions in order to take advantage of polar stereographic projections. An additional method for generating the databases was developed for use over Antarctica, such that high resolution, regional elevation models can be easily incorporated as they become available in the future. The SRM is used to facilitate DEM and DRM production by defining those regions that are ocean and sea ice. Ocean and sea ice elevation values are defined by the geoid, while relief is set to a constant value. Results presented will include the details of data source selection, the methodologies used to create the databases, and the final versions of both the DEM and DRM databases. Companion presentations by McGarry, et al. and Carabajal, et al. describe the ATLAS onboard Receiver Algorithms and the database verification, respectively.

Rapid Configurational Fluctuations in a Model of Methylcellulose

NASA Astrophysics Data System (ADS)

Li, Xiaolan; Dorfman, Kevin

Methylcellulose is a thermoresponsive polymer that undergoes a phase transition at elevated temperature, forming fibrils of a uniform diameter. However, the gelation mechanism is still unclear, in particular at higher polymer concentrations. We have investigated a coarse-grained model for methylcellulose, proposed by Larson and coworkers, that produces collapsed toroids in dilute solution with a radius close to that in experiments. Using Brownian Dynamics simulations, we demonstrate that this model's dihedral potential generates ``flipping events'', which helps the chain to avoid kinetic traps by undergoing a sudden transition between a coiled and a collapsed state. If the dihedral potential is removed, the chains cannot escape from their collapsed configuration, whereas at high dihedral potentials, the chains cannot stabilize the collapsed state. We will present quantitative results on the effect of the dihedral potential on both chain statistics and dynamic behavior, and discuss the implication of our results on the spontaneous formation of high-aspect ratio fibrils in experiments.

Gene Deletions Resulting in Increased Nitrogen Release by Azotobacter vinelandii: Application of a Novel Nitrogen Biosensor

PubMed Central

Eberhart, Lauren J.; Ohlert, Janet M.; Knutson, Carolann M.; Plunkett, Mary H.

2015-01-01

Azotobacter vinelandii is a widely studied model diazotrophic (nitrogen-fixing) bacterium and also an obligate aerobe, differentiating it from many other diazotrophs that require environments low in oxygen for the function of the nitrogenase. As a free-living bacterium, A. vinelandii has evolved enzymes and transporters to minimize the loss of fixed nitrogen to the surrounding environment. In this study, we pursued efforts to target specific enzymes and further developed screens to identify individual colonies of A. vinelandii producing elevated levels of extracellular nitrogen. Targeted deletions were done to convert urea into a terminal product by disrupting the urease genes that influence the ability of A. vinelandii to recycle the urea nitrogen within the cell. Construction of a nitrogen biosensor strain was done to rapidly screen several thousand colonies disrupted by transposon insertional mutagenesis to identify strains with increased extracellular nitrogen production. Several disruptions were identified in the ammonium transporter gene amtB that resulted in the production of sufficient levels of extracellular nitrogen to support the growth of the biosensor strain. Further studies substituting the biosensor strain with the green alga Chlorella sorokiniana confirmed that levels of nitrogen produced were sufficient to support the growth of this organism when the medium was supplemented with sufficient sucrose to support the growth of the A. vinelandii in coculture. The nature and quantities of nitrogen released by urease and amtB disruptions were further compared to strains reported in previous efforts that altered the nifLA regulatory system to produce elevated levels of ammonium. These results reveal alternative approaches that can be used in various combinations to yield new strains that might have further application in biofertilizer schemes. PMID:25888177

A functional antigen in a practical crop: LT-B producing maize protects mice against Escherichia coli heat labile enterotoxin (LT) and cholera toxin (CT).

PubMed

Chikwamba, Rachel; Cunnick, Joan; Hathaway, Diane; McMurray, Jennifer; Mason, Hugh; Wang, Kan

2002-10-01

We have produced a functional heat labile enterotoxin (LT-) B subunit of Escherichia coli in maize. LT-B is a multimeric protein that presents an ideal model for an edible vaccine, displaying stability in the gut and inducing mucosal and systemic immune responses. Transgenic maize was engineered to synthesize the LT-B polypeptides, which assembled into oligomeric structures with affinity for G(M1) gangliosides. We orally immunized BALB/c mice by feeding transgenic maize meal expressing LT-B or non-transgenic maize meal spiked with bacterial LT-B. Both treatments stimulated elevated IgA and IgG antibodies against LT-B and the closely related cholera toxin B subunit (CT-B) in serum, and elevated IgA in fecal pellets. The transgenic maize induced a higher anti-LT-B and anti-CT-B mucosal and serum IgA response compared to the equivalent amount of bacterial LT-B spiked into maize. Following challenge by oral administration of the diarrhea inducing toxins LT and CT, transgenic maize-fed mice displayed reduced fluid accumulation in the gut compared to non-immunized mice. Moreover, the gut to carcass ratio of immunized mice was not significantly different from the PBS (non-toxin) challenged control group. We concluded that maize-synthesized LT-B had features of the native bacterial LT-B such as molecular weight, G(M1) binding ability, and induction of serum and mucosal immunity. We have demonstrated that maize, a major food and feed ingredient, can be efficiently transformed to produce, accumulate, and store a fully assembled and functional candidate vaccine antigen.

Technical snow production in skiing areas: conditions, practice, monitoring and modelling. A case study in Mayrhofen/Austria

NASA Astrophysics Data System (ADS)

Strasser, Ulrich; Hanzer, Florian; Marke, Thomas; Rothleitner, Michael

2017-04-01

The production of technical snow today is a self-evident feature of modern alpine skiing resort management. Millions of Euros are invested every year for the technical infrastructure and its operation to produce a homogeneous and continuing snow cover on the skiing slopes for the winter season in almost every larger destination in the Alps. In Austria, skiing tourism is a significant factor of the national economic structure. We present the framing conditions of technical snow production in the mid-size skiing resort of Mayrhofen (Zillertal Alps/Austria, 136 km slopes, elevation range 630 - 2.500 m a.s.l.). Production conditions are defined by the availability of water, the planned date for the season opening, and the climatic conditions in the weeks before. By means of an adapted snow production strategy an attempt is made to ecologically and economically optimize the use of water and energy resources. Monitoring of the snow cover is supported by a network of low-cost sensors and mobile snow depth recordings. Finally, technical snow production is simulated with the spatially distributed, physically based hydroclimatological model AMUNDSEN. The model explicitly considers individual snow guns and distributes the produced snow along the slopes. The amount of simulated snow produced by each device is a function of its type, of actual wet-bulb temperature at the location, of ski area infrastructure (in terms of water supply and pumping capacity), and of snow demand.

Effects of organophosphorus anticholinesterase compounds on brain glucose and energy metabolism. Final summary report, 1 October 1981-29 February 1984

DOE Office of Scientific and Technical Information (OSTI.GOV)

Medina, M.A.; Miller, A.L.

1984-09-01

The effects of Soman and paraoxon on cerebral metabolic rate (CMRg) and the levels of various metabolites in rate brain were investigated. In non-convulsing animals, 0.8 of the paraoxon LD50 and 0.5 of the Soman LD50 tended to lower CMRg. A higher dose of Soman, 0.8-0.95 of the LD50, resulted in convulsive seizures in some but not all of the animals. In convulsing rats the CMRg and lactate levels were elevated primarily in the cortex and thalamus/basal ganglia. Decreased ATP and glucose levels with an elevated CMRg and lactate concentration was observed in the cortex, suggesting that Soman may bemore » uncoupling oxidative phosphorylation. Pretreatment with atropine prevented the behavioral manifestations and the elevated CMRg but not the hyperglycemia produced by an 0.8 LD50 dose of Soman. These results suggest that Soman-induced convulsions are similar to those produced by other central nervous system (CNS) excitatory agents in that only certain brain regions are affected. The use of atropine to block the CNS disturbances produced by Soman appears to be effective also does not result in the extensive depression of CMRg observed with TAB, a mixture of trimedoxime, atropine and benactyzine.« less

SREBP cleavage-activating protein (SCAP) is required for increased lipid synthesis in liver induced by cholesterol deprivation and insulin elevation

PubMed Central

Matsuda, Morihiro; Korn, Bobby S.; Hammer, Robert E.; Moon, Young-Ah; Komuro, Ryutaro; Horton, Jay D.; Goldstein, Joseph L.; Brown, Michael S.; Shimomura, Iichiro

2001-01-01

In liver, the synthesis of cholesterol and fatty acids increases in response to cholesterol deprivation and insulin elevation, respectively. This regulatory mechanism underlies the adaptation to cholesterol synthesis inhibitors (statins) and high calorie diets (insulin). In nonhepatic cells, lipid synthesis is controlled by sterol regulatory element-binding proteins (SREBPs), membrane-bound transcription factors whose active domains are released proteolytically to enter the nucleus and activate genes involved in the synthesis and uptake of cholesterol and fatty acids. SCAP (SREBP cleavage-activating protein) is a sterol-regulated escort protein that transports SREBPs from their site of synthesis in the endoplasmic reticulum to their site of cleavage in the Golgi. Here, we produced a conditional deficiency of SCAP in mouse liver by genomic recombination mediated by inducible Cre recombinase. SCAP-deficient mice showed an 80% reduction in basal rates of cholesterol and fatty acid synthesis in liver, owing to decreases in mRNAs encoding multiple biosynthetic enzymes. Moreover, these mRNAs failed to increase normally in response to cholesterol deprivation produced by a cholesterol synthesis inhibitor and to insulin elevation produced by a fasting–refeeding protocol. These data provide in vivo evidence that SCAP and the SREBPs are required for hepatic lipid synthesis under basal and adaptive conditions. PMID:11358865

Comparison of 7.5-minute and 1-degree digital elevation models

NASA Technical Reports Server (NTRS)

Isaacson, Dennis L.; Ripple, William J.

1995-01-01

We compared two digital elevation models (DEM's) for the Echo Mountain SE quadrangle in the Cascade Mountains of Oregon. Comparisons were made between 7.5-minute (1:24,000-scale) and 1-degree (1:250,000-scale) images using the variables of elevation, slope aspect, and slope gradient. Both visual and statistical differences are presented.

Comparison of 7.5-minute and 1-degree digital elevation models

NASA Technical Reports Server (NTRS)

Isaacson, Dennis L.; Ripple, William J.

1990-01-01

Two digital elevation models are compared for the Echo Mountain SE quadrangle in the Cascade Mountains of Oregon. Comparisons were made between 7.5-minute (1:24,000-scale) and 1-degree (1:250,000-scale) images using the variables of elevation, slope aspect, and slope gradient. Both visual and statistical differences are presented.

Where’s the Ground Surface? – Elevation Bias in LIDAR-derived Digital Elevation Models Due to Dense Vegetation in Oregon Tidal Marshes

EPA Science Inventory

Light Detection and Ranging (LIDAR) is a powerful resource for coastal and wetland managers and its use is increasing. Vegetation density and other land cover characteristics influence the accuracy of LIDAR-derived ground surface digital elevation models; however the degree to wh...

Developments in remote sensing technology enable more detailed urban flood risk analysis.

NASA Astrophysics Data System (ADS)

Denniss, A.; Tewkesbury, A.

2009-04-01

Spaceborne remote sensors have been allowing us to build up a profile of planet earth for many years. With each new satellite launched we see the capabilities improve: new bands of data, higher resolution imagery, the ability to derive better elevation information. The combination of this geospatial data to create land cover and usage maps, all help inform catastrophe modelling systems. From Landsat 30m resolution to 2.44m QuickBird multispectral imagery; from 1m radar data collected by TerraSAR-X which enables rapid tracking of the rise and fall of a flood event, and will shortly have a twin satellite launched enabling elevation data creation; we are spoilt for choice in available data. However, just what is cost effective? It is always a question of choosing the appropriate level of input data detail for modelling, depending on the value of the risk. In the summer of 2007, the cost of the flooding in the UK was approximately £3bn and affected over 58,000 homes and businesses. When it comes to flood risk, we have traditionally considered rising river levels and surge tides, but with climate change and variations in our own construction behaviour, there are other factors to be taken into account. During those summer 2007 events, the Environment Agency suggested that around 70% of the properties damaged were the result of pluvial flooding, where high localised rainfall events overload localised drainage infrastructure, causing widespread flooding of properties and infrastructure. To create a risk model that is able to simulate such an event requires much more accurate source data than can be provided from satellite or radar. As these flood events cause considerable damage within relatively small, complex urban environments, therefore new high resolution remote sensing techniques have to be applied to better model these events. Detailed terrain data of England and Wales, plus cities in Scotland, have been produced by combining terrain measurements from the latest digital airborne sensors, both optical and lidar, to produce the input layer for surface water flood modelling. A national flood map product has been created. The new product utilises sophisticated modelling techniques, perfected over many years, which harness graphical processing power. This product will prove particularly valuable for risk assessment decision support within insurance/reinsurance, property/environmental, utilities, risk management and government agencies. However, it is not just the ground elevation that determines the behaviour of surface water. By combining height information (surface and terrain) with high resolution aerial photography and colour infrared imagery, a high definition land cover mapping dataset (LandBase) is being produced, which provides a precise measure of sealed versus non sealed surface. This will allows even more sophisticated modelling of flood scenarios. Thus, the value of airborne survey data can be demonstrated by flood risk analysis down to individual addresses in urban areas. However for some risks, an even more detailed survey may be justified. In order to achieve this, Infoterra is testing new 360˚ mobile lidar technology. Collecting lidar data from a moving vehicle allows each street to be mapped in very high detail, allowing precise information about the location, size and shape of features such as kerbstones, gullies, road camber and building threshold level to be captured quickly and accurately. These data can then be used to model the problem of overland flood risk at the scale of individual properties. Whilst at present it might be impractical to undertake such detailed modelling for all properties, these techniques can certainly be used to improve the flood risk analysis of key locations. This paper will demonstrate how these new high resolution remote sensing techniques can be combined to provide a new resolution of detail to aid urban flood modelling.

Sound stress-induced long-term enhancement of mechanical hyperalgesia in rats is maintained by sympathoadrenal catecholamines.

PubMed

Khasar, Sachia G; Dina, Olayinka A; Green, Paul G; Levine, Jon D

2009-10-01

Although stress plays an important role in chronic widespread pain syndromes, such as fibromyalgia, the underlying mechanism has remained elusive. We have recently demonstrated, in a model of chronic widespread pain, that prolonged enhancement of immune mediator hyperalgesia, induced by unpredictable sound stress, requires a contribution of both the sympathoadrenal (epinephrine) and the hypothalamic-pituitary adrenal (corticosterone) neuroendocrine stress axes. Because this stress protocol produced sustained elevation of plasma epinephrine, in the current study we tested the hypothesis that the sympathoadrenal axis also plays a role in maintenance of symptoms in this model of chronic widespread pain. After establishment, adrenal medullectomy abolished the enhancement of epinephrine-induced cutaneous and muscle hyperalgesia. Administration of stress levels of epinephrine to adrenal medullectomized rats reconstituted the pain phenotype. These observations suggest that the sympathoadrenal stress axis plays a major role in the induction as well as maintenance of stress-induced enhancement of mechanical hyperalgesia, mediated by prolonged elevation of circulating epinephrine. We present data showing mechanical hyperalgesia persisting for up to 28 days after exposure to sound stress, with evidence that the sympathoadrenal axis mediator epinephrine plays a major role. These findings could have clinical implications with regard to novel potential treatments for chronic widespread pain syndromes, such as fibromyalgia.

Prospective relations between growth in drinking and familial stressors across adolescence

PubMed Central

King, Kevin M.; Molina, Brooke S.G.; Chassin, Laurie

2010-01-01

Although there is much empirical support for the relation between stress and alcohol consumption in adolescence, it is unclear whether exposure to stressors is associated with overall trajectories or temporary elevations in drinking. Moreover, little research has explored whether the stress-alcohol use association in adolescence may be explained by shared risk factors that produce both individual differences in stress exposure and elevated risk for alcohol use. The current study tested these hypotheses within the context of a state-trait model of family stressors in a prospectively studied sample of children at high risk for alcoholism: children of alcoholic parents and matched controls (n = 451). Levels and growth in alcohol use were modeled longitudinally from ages 13 to 17. Results indicated that shared risk factors accounted for 53% of the impact of trait family stressors on growth in adolescent drinking, but time-specific exposure to familial stressors still predicted short-term boosts in alcohol use in adolescence. These findings imply that trait familial stressors mark adolescents at risk for alcohol use, and also impact adolescent alcohol use within a short time frame (i.e. over a year versus over many years) when they occur above and beyond the adolescent’s “usual load” of stressors. PMID:19685957

Trait-based diversification shifts reflect differential extinction among fossil taxa

PubMed Central

Wagner, Peter J.; Estabrook, George F.

2014-01-01

Evolution provides many cases of apparent shifts in diversification associated with particular anatomical traits. Three general models connect these patterns to anatomical evolution: (i) elevated net extinction of taxa bearing particular traits, (ii) elevated net speciation of taxa bearing particular traits, and (iii) elevated evolvability expanding the range of anatomies available to some species. Trait-based diversification shifts predict elevated hierarchical stratigraphic compatibility (i.e., primitive→derived→highly derived sequences) among pairs of anatomical characters. The three specific models further predict (i) early loss of diversity for taxa retaining primitive conditions (elevated net extinction), (ii) increased diversification among later members of a clade (elevated net speciation), and (iii) increased disparity among later members in a clade (elevated evolvability). Analyses of 319 anatomical and stratigraphic datasets for fossil species and genera show that hierarchical stratigraphic compatibility exceeds the expectations of trait-independent diversification in the vast majority of cases, which was expected if trait-dependent diversification shifts are common. Excess hierarchical stratigraphic compatibility correlates with early loss of diversity for groups retaining primitive conditions rather than delayed bursts of diversity or disparity across entire clades. Cambrian clades (predominantly trilobites) alone fit null expectations well. However, it is not clear whether evolution was unusual among Cambrian taxa or only early trilobites. At least among post-Cambrian taxa, these results implicate models, such as competition and extinction selectivity/resistance, as major drivers of trait-based diversification shifts at the species and genus levels while contradicting the predictions of elevated net speciation and elevated evolvability models. PMID:25331898

Chronic Glucocorticoids Increase Hippocampal Vulnerability to Neurotoxicity under Conditions That Produce CA3 Dendritic Retraction But Fail to Impair Spatial Recognition Memory

PubMed Central

Conrad, Cheryl D.; McLaughlin, Katie J.; Harman, James S.; Foltz, Cainan; Wieczorek, Lindsay; Lightner, Elizabeth; Wright, Ryan L.

2007-01-01

We previously found that chronic stress conditions producing CA3 dendritic retraction and spatial memory deficits make the hippocampus vulnerable to the neurotoxin ibotenic acid (IBO). The purpose of this study was to determine whether exposure to chronic corticosterone (CORT) under conditions that produce CA3 dendritic retraction would enhance CA3 susceptibility to IBO. Male Sprague Dawley rats were chronically treated for 21 d with CORT in drinking water (400 μg/ml), and half were given daily injections of phenytoin (40 mg/kg), an antiepileptic drug that prevents CA3 dendritic retraction. Three days after treatments stopped, IBO was infused into the CA3 region. Conditions producing CA3 dendritic retraction (CORT and vehicle) exacerbated IBO-induced CA3 damage compared with conditions in which CA3 dendritic retraction was not observed (vehicle and vehicle, vehicle and phenytoin, CORT and phenytoin). Additionally, spatial recognition memory was assessed using the Y-maze, revealing that conditions producing CA3 dendritic retraction failed to impair spatial recognition memory. Furthermore, CORT levels in response to a potentially mild stressor (injection and Y-maze exposure) stayed at basal levels and failed to differ among key groups (vehicle and vehicle, CORT and vehicle, CORT and phenytoin), supporting the interpretations that CORT levels were unlikely to have been elevated during IBO infusion and that the neuroprotective actions of phenytoin were not through CORT alterations. These data are the first to show that conditions with prolonged glucocorticoid elevations leading to structural changes in hippocampal dendritic arbors can make the hippocampus vulnerable to neurotoxic challenges. These findings have significance for many disorders with elevated glucocorticoids that include depression, schizophrenia, Alzheimer’s disease, and Cushing’s disease. PMID:17670974

Do all leaf photosynthesis parameters of rice acclimate to elevated CO2 , elevated temperature, and their combination, in FACE environments?

PubMed

Cai, Chuang; Li, Gang; Yang, Hailong; Yang, Jiaheng; Liu, Hong; Struik, Paul C; Luo, Weihong; Yin, Xinyou; Di, Lijun; Guo, Xuanhe; Jiang, Wenyu; Si, Chuanfei; Pan, Genxing; Zhu, Jianguo

2018-04-01

Leaf photosynthesis of crops acclimates to elevated CO 2 and temperature, but studies quantifying responses of leaf photosynthetic parameters to combined CO 2 and temperature increases under field conditions are scarce. We measured leaf photosynthesis of rice cultivars Changyou 5 and Nanjing 9108 grown in two free-air CO 2 enrichment (FACE) systems, respectively, installed in paddy fields. Each FACE system had four combinations of two levels of CO 2 (ambient and enriched) and two levels of canopy temperature (no warming and warmed by 1.0-2.0°C). Parameters of the C 3 photosynthesis model of Farquhar, von Caemmerer and Berry (the FvCB model), and of a stomatal conductance (g s ) model were estimated for the four conditions. Most photosynthetic parameters acclimated to elevated CO 2 , elevated temperature, and their combination. The combination of elevated CO 2 and temperature changed the functional relationships between biochemical parameters and leaf nitrogen content for Changyou 5. The g s model significantly underestimated g s under the combination of elevated CO 2 and temperature by 19% for Changyou 5 and by 10% for Nanjing 9108 if no acclimation was assumed. However, our further analysis applying the coupled g s -FvCB model to an independent, previously published FACE experiment showed that including such an acclimation response of g s hardly improved prediction of leaf photosynthesis under the four combinations of CO 2 and temperature. Therefore, the typical procedure that crop models using the FvCB and g s models are parameterized from plants grown under current ambient conditions may not result in critical errors in projecting productivity of paddy rice under future global change. © 2017 John Wiley & Sons Ltd.

Evaluation of the U.S. Geological Survey standard elevation products in a two-dimensional hydraulic modeling application for a low relief coastal floodplain

USGS Publications Warehouse

Witt, Emitt C.

2015-01-01

Growing use of two-dimensional (2-D) hydraulic models has created a need for high resolution data to support flood volume estimates, floodplain specific engineering data, and accurate flood inundation scenarios. Elevation data are a critical input to these models that guide the flood-wave across the landscape allowing the computation of valuable engineering specific data that provides a better understanding of flooding impacts on structures, debris movement, bed scour, and direction. High resolution elevation data are becoming publicly available that can benefit the 2-D flood modeling community. Comparison of these newly available data with legacy data suggests that better modeling outcomes are achieved by using 3D Elevation Program (3DEP) lidar point data and the derived 1 m Digital Elevation Model (DEM) product relative to the legacy 3 m, 10 m, or 30 m products currently available in the U.S. Geological Survey (USGS) National Elevation Dataset. Within the low topographic relief of a coastal floodplain, the newer 3DEP data better resolved elevations within the forested and swampy areas achieving simulations that compared well with a historic flooding event. Results show that the 1 m DEM derived from 3DEP lidar source provides a more conservative estimate of specific energy, static pressure, and impact pressure for grid elements at maximum flow relative to the legacy DEM data. Better flood simulations are critically important in coastal floodplains where climate change driven storm frequency and sea level rise will contribute to more frequent flooding events.

FG7142, yohimbine, and βCCE produce anxiogenic-like effects in the elevated plus-maze but do not affect brainstem activated hippocampal theta.

PubMed

Yeung, Michelle; Lu, Lily; Hughes, Adam M; Treit, Dallas; Dickson, Clayton T

2013-12-01

The neurobiological underpinnings of anxiety are of paramount importance to selective and efficacious pharmaceutical intervention. Hippocampal theta frequency in urethane anaesthetized rats is suppressed by all known (and some previously unknown) anti-anxiety (anxiolytic) drugs. Although these findings support the predictive validity of this assay, its construct validity (i.e., whether theta frequency actually indexes anxiety per se) has not been a subject of systematic investigation. We reasoned that if anxiolytic drugs suppress hippocampal theta frequency, then drugs that increase anxiety (i.e., anxiogenic agents) should increase theta frequency, thus providing evidence of construct validity. We used three proven anxiogenic drugs--two benzodiazepine receptor inverse agonists, N-methyl-β-carboline-3-carboxamide (FG7142) and β-carboline-3-carboxylate ethyl ester (βCCE), and one α2 noradrenergic receptor antagonist, 17α-hydroxy-yohimban-16α-carboxylic acid methyl ester (yohimbine) as pharmacological probes to assess the construct validity of the theta model. Although all three anxiogenic drugs significantly increased behavioural measures of anxiety in the elevated plus-maze, none of the three increased the frequency of hippocampal theta oscillations in the neurophysiological model. As a positive control, we demonstrated that diazepam, a proven anxiolytic drug, decreased the frequency of hippocampal theta, as in all other studies using this model. Given this discrepancy between the significant effects of anxiogenic drugs in the behavioural model and the null effects of these drugs in the neurophysiological model, we conclude that the construct validity of the hippocampal theta model of anxiety is questionable. Copyright © 2013 Elsevier Ltd. All rights reserved.

Seasonal and Interannual Variations of Ice Sheet Surface Elevation at the Summit of Greenland: Observed and Modeled

NASA Technical Reports Server (NTRS)

Zwally, H. Jay; Jun, Li; Koblinsky, Chester J. (Technical Monitor)

2001-01-01

Observed seasonal and interannual variations in the surface elevation over the summit of the Greenland ice sheet are modeled using a new temperature-dependent formulation of firn-densification and observed accumulation variations. The observed elevation variations are derived from ERS (European Remote Sensing)-1 and ERS-2 radar altimeter data for the period between April 1992 and April 1999. A multivariate linear/sine function is fitted to an elevation time series constructed from elevation differences measured by radar altimetry at orbital crossovers. The amplitude of the seasonal elevation cycle is 0.25 m peak-to-peak, with a maximum in winter and a minimum in summer. Inter-annually, the elevation decreases to a minimum in 1995, followed by an increase to 1999, with an overall average increase of 4.2 cm a(exp -1) for 1992 to 1999. Our densification formulation uses an initial field-density profile, the AWS (automatic weather station) surface temperature record, and a temperature-dependent constitutive relation for the densification that is based on laboratory measurements of crystal growth rates. The rate constant and the activation energy commonly used in the Arrhenius-type constitutive relation for firn densification are also temperature dependent, giving a stronger temperature and seasonal amplitudes about 10 times greater than previous densification formulations. Summer temperatures are most important, because of the strong non-linear dependence on temperature. Much of firn densification and consequent surface lowering occurs within about three months of the summer season, followed by a surface build-up from snow accumulation until spring. Modeled interannual changes of the surface elevation, using the AWS measurements of surface temperature and accumulation and results of atmospheric modeling of precipitation variations, are in good agreement with the altimeter observations. In the model, the surface elevation decreases about 20 cm over the seven years due to more compaction driven by increasing summer temperatures. The minimum elevation in 1995 is driven mainly by a temporary accumulation decrease and secondarily by warmer temperatures. However, the overall elevation increase over the seven years is dominated by the accumulation increase in the later years.

Dynamic Inland Propagation of Thinning Due to Ice Loss at the Margins of the Greenland Ice Sheet

NASA Technical Reports Server (NTRS)

Wang, Wei Li; Li, Jun J.; Zwally, H. Jay

2012-01-01

Mass-balance analysis of the Greenland ice sheet based on surface elevation changes observed by the European Remote-sensing Satellite (ERS) (1992-2002) and Ice, Cloud and land Elevation Satellite (ICESat) (2003-07) indicates that the strongly increased mass loss at lower elevations (<2000 m) of the ice sheet, as observed during 2003-07, appears to induce interior ice thinning at higher elevations. In this paper, we perform a perturbation experiment with a three-dimensional anisotropic ice-flow model (AIF model) to investigate this upstream propagation. Observed thinning rates in the regions below 2000m elevation are used as perturbation inputs. The model runs with perturbation for 10 years show that the extensive mass loss at the ice-sheet margins does in fact cause interior thinning on short timescales (i.e. decadal). The modeled pattern of thinning over the ice sheet agrees with the observations, which implies that the strong mass loss since the early 2000s at low elevations has had a dynamic impact on the entire ice sheet. The modeling results also suggest that even if the large mass loss at the margins stopped, the interior ice sheet would continue thinning for 300 years and would take thousands of years for full dynamic recovery.

A receptor-based model for dopamine-induced fMRI signal

PubMed Central

Mandeville, Joseph. B.; Sander, Christin Y. M.; Jenkins, Bruce G.; Hooker, Jacob M.; Catana, Ciprian; Vanduffel, Wim; Alpert, Nathaniel M.; Rosen, Bruce R.; Normandin, Marc D.

2013-01-01

This report describes a multi-receptor physiological model of the fMRI temporal response and signal magnitude evoked by drugs that elevate synaptic dopamine in basal ganglia. The model is formulated as a summation of dopamine’s effects at D1-like and D2-like receptor families, which produce functional excitation and inhibition, respectively, as measured by molecular indicators like adenylate cyclase or neuroimaging techniques like fMRI. Functional effects within the model are described in terms of relative changes in receptor occupancies scaled by receptor densities and neuro-vascular coupling constants. Using literature parameters, the model reconciles many discrepant observations and interpretations of pre-clinical data. Additionally, we present data showing that amphetamine stimulation produces fMRI inhibition at low doses and a biphasic response at higher doses in the basal ganglia of non-human primates (NHP), in agreement with model predictions based upon the respective levels of evoked dopamine. Because information about dopamine release is required to inform the fMRI model, we simultaneously acquired PET 11C-raclopride data in several studies to evaluate the relationship between raclopride displacement and assumptions about dopamine release. At high levels of dopamine release, results suggest that refinements of the model will be required to consistently describe the PET and fMRI data. Overall, the remarkable success of the model in describing a wide range of preclinical fMRI data indicate that this approach will be useful for guiding the design and analysis of basic science and clinical investigations and for interpreting the functional consequences of dopaminergic stimulation in normal subjects and in populations with dopaminergic neuroadaptations. PMID:23466936

Generation of 2D Land Cover Maps for Urban Areas Using Decision Tree Classification

NASA Astrophysics Data System (ADS)

Höhle, J.

2014-09-01

A 2D land cover map can automatically and efficiently be generated from high-resolution multispectral aerial images. First, a digital surface model is produced and each cell of the elevation model is then supplemented with attributes. A decision tree classification is applied to extract map objects like buildings, roads, grassland, trees, hedges, and walls from such an "intelligent" point cloud. The decision tree is derived from training areas which borders are digitized on top of a false-colour orthoimage. The produced 2D land cover map with six classes is then subsequently refined by using image analysis techniques. The proposed methodology is described step by step. The classification, assessment, and refinement is carried out by the open source software "R"; the generation of the dense and accurate digital surface model by the "Match-T DSM" program of the Trimble Company. A practical example of a 2D land cover map generation is carried out. Images of a multispectral medium-format aerial camera covering an urban area in Switzerland are used. The assessment of the produced land cover map is based on class-wise stratified sampling where reference values of samples are determined by means of stereo-observations of false-colour stereopairs. The stratified statistical assessment of the produced land cover map with six classes and based on 91 points per class reveals a high thematic accuracy for classes "building" (99 %, 95 % CI: 95 %-100 %) and "road and parking lot" (90 %, 95 % CI: 83 %-95 %). Some other accuracy measures (overall accuracy, kappa value) and their 95 % confidence intervals are derived as well. The proposed methodology has a high potential for automation and fast processing and may be applied to other scenes and sensors.

Acetone photophysics at 282 nm excitation at elevated pressure and temperature. II: Fluorescence modeling

NASA Astrophysics Data System (ADS)

Hartwig, Jason; Raju, Mandhapati; Sung, Chih-Jen

2017-07-01

This is the second in a series of two papers that presents an updated fluorescence model and compares with the new experimental data reported in the first paper, as well as the available literature data, to extend the range of acetone photophysics to elevated pressure and temperature conditions. This work elucidates the complete acetone photophysical model in terms of each and every competing radiative and non-radiative rate. The acetone fluorescence model is then thoroughly examined and optimized based on disparity with recently conducted elevated pressure and temperature photophysical calibration experiments. The current work offers insight into the competition between non-radiative and vibrational energy decay rates at elevated temperature and pressure and proposes a global optimization of model parameters from the photophysical model developed by Thurber (Acetone Laser-Induced Fluorescence for Temperature and Multiparameter Imaging in Gaseous Flows. PhD thesis, Stanford University Mechanical Engineering Department, 1999). The collisional constants of proportionality, which govern vibrational relaxation, are shown to be temperature dependent at elevated pressures. A new oxygen quenching rate is proposed which takes into account collisions with oxygen as well as the oxygen-assisted intersystem crossing component. Additionally, global trends in ketone photophysics are presented and discussed.

UAV-based photogrammetry combination of the elevational outcrop and digital surface models: an example of Sanyi active fault in western Taiwan

NASA Astrophysics Data System (ADS)

Hsieh, Cheng-En; Huang, Wen-Jeng; Chang, Ping-Yu; Lo, Wei

2016-04-01

An unmanned aerial vehicle (UAV) with a digital camera is an efficient tool for geologists to investigate structure patterns in the field. By setting ground control points (GCPs), UAV-based photogrammetry provides high-quality and quantitative results such as a digital surface model (DSM) and orthomosaic and elevational images. We combine the elevational outcrop 3D model and a digital surface model together to analyze the structural characteristics of Sanyi active fault in Houli-Fengyuan area, western Taiwan. Furthermore, we collect resistivity survey profiles and drilling core data in the Fengyuan District in order to build the subsurface fault geometry. The ground sample distance (GSD) of an elevational outcrop 3D model is 3.64 cm/pixel in this study. Our preliminary result shows that 5 fault branches are distributed 500 meters wide on the elevational outcrop and the width of Sanyi fault zone is likely much great than this value. Together with our field observations, we propose a structural evolution model to demonstrate how the 5 fault branches developed. The resistivity survey profiles show that Holocene gravel was disturbed by the Sanyi fault in Fengyuan area.

space Radar Image of Long Valley, California

NASA Image and Video Library

1999-05-01

An area near Long Valley, California, was mapped by the Spaceborne Imaging Radar-C and X-band Synthetic Aperture Radar aboard the space shuttle Endeavor on April 13, 1994, during the first flight of the radar instrument, and on October 4, 1994, during the second flight of the radar instrument. The orbital configurations of the two data sets were ideal for interferometric combination -- that is overlaying the data from one image onto a second image of the same area to create an elevation map and obtain estimates of topography. Once the topography is known, any radar-induced distortions can be removed and the radar data can be geometrically projected directly onto a standard map grid for use in a geographical information system. The 50 kilometer by 50 kilometer (31 miles by 31 miles) map shown here is entirely derived from SIR-C L-band radar (horizontally transmitted and received) results. The color shown in this image is produced from the interferometrically determined elevations, while the brightness is determined by the radar backscatter. The map is in Universal Transverse Mercator (UTM) coordinates. Elevation contour lines are shown every 50 meters (164 feet). Crowley Lake is the dark feature near the south edge of the map. The Adobe Valley in the north and the Long Valley in the south are separated by the Glass Mountain Ridge, which runs through the center of the image. The height accuracy of the interferometrically derived digital elevation model is estimated to be 20 meters (66 feet) in this image. http://photojournal.jpl.nasa.gov/catalog/PIA01749

A data-led comparison of simple canopy radiative transfer models for the boreal forest

NASA Astrophysics Data System (ADS)

Reid, T.; Essery, R.; Rutter, N.; King, M.

2012-12-01

Given the computational complexity of numerical weather and climate models, it is worthwhile developing very simple parameterizations for processes such as the transmission of radiation through forest canopies. For this reason, the land surface schemes in global models, and most snow hydrological models, tend to use simple one-dimensional approaches based on Beer's Law or two-stream approximations. Such approaches assume a continuous canopy structure that may not be suitable for the varied, heterogeneous forest cover in boreal regions, especially in winter when snow in the canopy and on the ground may either block radiation or produce multiple reflections between the ground and the trees. There is great benefit in comparing models to real transmissivity values calculated from radiation measurements below and above Arctic canopies. In particular, there is a lack of data for leafless boreal deciduous forests, where canopy gaps are prevalent even at low solar elevation angles near the horizon. In this study, models are compared to radiation data collected in an area of boreal birch forest near Abisko, Sweden in March/April 2011 and mixed conifer forest at Sodankylä, Finland in March/April 2012. Arrays comprising ten shortwave pyranometers were deployed for periods of up to 50 days, under forest plots of varying canopy structures and densities. In addition, global and diffuse shortwave irradiances were recorded at nearby open sites representing the top-of-canopy conditions. A model is developed that explicitly accounts for both diffuse radiation and direct beam transmission on a 5-minute timestep, by using upward-looking hemispherical photographs taken from every pyranometer site. This model reproduces measured transmissivity, although with a slight underestimation, especially at low solar elevations - this could be attributed to multiple reflections that are not accounted for in the model. On the other hand, models based on Beer's Law tend to underestimate the canopy transmissivity significantly, especially for leafless birch canopies where the required assumption of a continuous canopy breaks down. These findings are important for the often sparse, heterogeneous forest cover in boreal regions, where forest edges and canopy gaps are plentiful. They could also have an impact on estimations of overall land surface albedo. Moreover, all models are sensitive to the partitioning of top-of-canopy radiation into its direct and diffuse components, which is complicated by the low solar elevations in the Arctic. More research is required to decide the best way of quantifying the diffuse fraction, using data alongside both physical and empirical models.

Deep desulfurization of hydrocarbon fuels

DOEpatents

Song, Chunshan [State College, PA; Ma, Xiaoliang [State College, PA; Sprague, Michael J [Calgary, CA; Subramani, Velu [State College, PA

2012-04-17

The invention relates to processes for reducing the sulfur content in hydrocarbon fuels such as gasoline, diesel fuel and jet fuel. The invention provides a method and materials for producing ultra low sulfur content transportation fuels for motor vehicles as well as for applications such as fuel cells. The materials and method of the invention may be used at ambient or elevated temperatures and at ambient or elevated pressures without the need for hydrogen.

Amelioration of boron toxicity in sweet pepper as affected by calcium management under an elevated CO2 concentration.

PubMed

Piñero, María Carmen; Pérez-Jiménez, Margarita; López-Marín, Josefa; Del Amor, Francisco M

2017-04-01

We investigated B tolerance in sweet pepper plants (Capsicum annuun L.) under an elevated CO 2 concentration, combined with the application of calcium as a nutrient management amelioration technique. The data show that high B affected the roots more than the aerial parts, since there was an increase in the shoot/root ratio, when plants were grown with high B levels; however, the impact was lessened when the plants were grown at elevated CO 2 , since the root FW reduction caused by excess B was less marked at the high CO 2 concentration (30.9% less). Additionally, the high B concentration affected the membrane permeability of roots, which increased from 39 to 54% at ambient CO 2 concentration, and from 38 to 51% at elevated CO 2 concentration, producing a cation imbalance in plants, which was differentially affected by the CO 2 supply. The Ca surplus in the nutrient solution reduced the nutritional imbalance in sweet pepper plants produced by the high B concentration, at both CO 2 concentrations. The medium B concentration treatment (toxic according to the literature) did not result in any toxic effect. Hence, there is a need to review the literature on critical and toxic B levels taking into account increases in atmospheric CO 2 .

Intrinsic increase in lymphangion muscle contractility in response to elevated afterload

PubMed Central

Scallan, Joshua P.; Wolpers, John H.; Muthuchamy, Mariappan; Gashev, Anatoliy A.; Zawieja, David C.

2012-01-01

Collecting lymphatic vessels share functional and biochemical characteristics with cardiac muscle; thus, we hypothesized that the lymphatic vessel pump would exhibit behavior analogous to homeometric regulation of the cardiac pump in its adaptation to elevated afterload, i.e., an increase in contractility. Single lymphangions containing two valves were isolated from the rat mesenteric microcirculation, cannulated, and pressurized for in vitro study. Pressures at either end of the lymphangion [input pressure (Pin), preload; output pressure (Pout), afterload] were set by a servo controller. Intralymphangion pressure (PL) was measured using a servo-null micropipette while internal diameter and valve positions were monitored using video methods. The responses to step- and ramp-wise increases in Pout (at low, constant Pin) were determined. PL and diameter data recorded during single contraction cycles were used to generate pressure-volume (P-V) relationships for the subsequent analysis of lymphangion pump behavior. Ramp-wise Pout elevation led to progressive vessel constriction, a rise in end-systolic diameter, and an increase in contraction frequency. Step-wise Pout elevation produced initial vessel distention followed by time-dependent declines in end-systolic and end-diastolic diameters. Significantly, a 30% leftward shift in the end-systolic P-V relationship accompanied an 84% increase in dP/dt after a step increase in Pout, consistent with an increase in contractility. Calculations of stroke work from the P-V loop area revealed that robust pumps produced net positive work to expel fluid throughout the entire afterload range, whereas weaker pumps exhibited progressively more negative work as gradual afterload elevation led to pump failure. We conclude that lymphatic muscle adapts to output pressure elevation with an intrinsic increase in contractility and that this compensatory mechanism facilitates the maintenance of lymph pump output in the face of edemagenic and/or gravitational loads. PMID:22886407

Heterologous desensitization of both phosphoinositide and Ca2+ signaling in SH-SY5Y neuroblastoma cells: a role for intracellular Ca2+ store depletion?

PubMed

Willars, G B; Nahorski, S R

1995-03-01

Measurement of the intracellular Ca2+ concentration ([Ca2+]i) in fura-2-loaded single cells of the human neuroblastoma line SH-SY5Y indicated coexpression of muscarinic and bradykinin receptors linked to activation of phosphoinositidase C (PIC). Both agonists elevated [Ca2+]i and inositol-1,4,5-trisphosphate [Ins(1,4,5)P3] levels in populations of adherent cells, although in cells used directly upon attainment of confluence the responses to carbachol were greater than those to bradykinin and displayed additional sustained components. This model system was used to examine heterologous interactions when a second PIC-linked agonist was added 100-300 sec after but in the continued presence of the first. Maximal (1 mM) carbachol concentrations abolished the elevation of [Ca2+]i produced by bradykinin but the muscarinic antagonist atropine (10 microM) restored the response, provided that extracellular Ca2+ was present throughout the experiment or was added before bradykinin. Carbachol also abolished bradykinin-mediated Ins(1,4,5)P3 elevation. In contrast, bradykinin did not influence [Ca2+]i or Ins(1,4,5)P3 responses to carbachol in the presence of extracellular Ca2+. In cells maintained at confluence for 2 weeks, the rapid peak elevations of [Ca2+]i and Ins(1,4,5)P3 levels induced by carbachol and bradykinin were approximately equivalent in magnitude. In these cells carbachol again abolished bradykinin-mediated elevation of [Ca2+]i but only attenuated, rather than abolished, the elevation of Ins(1,4,5)P3 levels. The [Ca2+]i and Ins(1,4,5)P3 responses to bradykinin were fully restored 100 sec after atropine only in the presence of extracellular Ca2+. Thus, depletion of an intracellular Ins(1,4,5)P3-sensitive Ca2+ store may underlie the ability of carbachol to produce not only heterologous desensitization of the [Ca2+]i elevation induced by bradykinin but also that of the Ins(1,4,5)P3 response. This suggests a feed-forward activation of PIC by Ca2+ released from Ins(1,4,5)P3-sensitive stores. Furthermore, studies in which Ins(1,4,5)P3-sensitive stores were depleted with thapsigargin and cells were challenged in the presence or absence of extracellular Ca2+ indicated that Ca2+, irrespective of its origin (intra- or extracellular), potentiated the Ins(1,4,5)P3 response to bradykinin alone. In cells maintained at confluence for 2 weeks, bradykinin was again unable to influence either [Ca2+]i or Ins(1,4,5)P3 responses to carbachol in the presence of Ca2+. This lack of heterologous desensitization may be due to the rapid, full, homologous desensitization of bradykinin receptors, compared with an incomplete homologous desensitization of muscarinic receptors.