Changes in Central Walker Lane Strain Accommodation near Bridgeport, California; as told by the Stanislaus Group

NASA Astrophysics Data System (ADS)

Carlson, C. W.; Pluhar, C. J.; Glen, J. M.; Farner, M. J.

2012-12-01

Accommodating ~20-25% of the dextral-motion between the Pacific and North American plates the Walker Lane is represented as an elongate, NW oriented, region of active tectonics positioned between the northwesterly-translating Sierra Nevada microplate and the east-west extension of the Basin and Range. This region of transtension is being variably accommodated on regional-scale systems of predominantly strike-slip faulting. At the western edge of the central Walker Lane (ca. 38°-39°N latitude) is a region of crustal-scale blocks bounded by wedge-shaped depositional-basins and normal-fault systems, here defined as the west-central Walker Lane (WCWL). Devoid of obvious strike-slip faulting, the presence of tectonic-block vertical-axis rotations in the WCWL represents unrecognized components of dextral-shearing and/or changes of strain-accommodation over time. We use paleomagnetic reference directions for Eureka Valley Tuff (EVT) members of the late Miocene Stanislaus Group as spatial and temporal markers for documentation of tectonic-block vertical-axis rotations near Bridgeport, CA. Study-site rotations revealed discrete rotational domains of mean vertical-axis rotation ranging from ~10°-30° with heterogeneous regional distribution. Additionally, the highest measured magnitudes of vertical-axis rotation (~50°-60° CW) define a 'Region of High Strain' that includes the wedge-shaped Bridgeport Valley (Basin). This study revealed previously-unrecognized tectonic rotation of reference direction sites from prior studies for two (By-Day and Upper) of the three members of the EVT, resulting in under-estimates of regional strain accommodation by these studies. Mean remanent directions and virtual geomagnetic poles utilized in our study yielded a recalculated reference direction for the By-Day member of: Dec.=353.2°; Inc.= 43.7°; α95=10.1, in agreement with new measurements in the stable Sierra Nevada. This recalculated direction confirmed the presence of previously unrecognized reference site rotations, and provided an additional reference direction for determining vertical-axis rotation magnitudes. We present a kinematic model based on mean rotation magnitudes of ~30° CW for the Sweetwater Mountains and Bodie Hills that accounts for rotational-strain accommodation of dextral shear in the WCWL since the late Miocene. This model considers rotational magnitudes, paleostrain indicators, edge-effects, and strain-accommodating structures of rotating crustal blocks to represent changes in regional strain accommodation over time. The results and models presented here elucidate the complicated and evolving nature of the WCWL, and further understanding of variations in strain accommodation for the Walker Lane.

Magmatic-Tectonic Interactions: Implications for Seismic Hazard Assessment in the Central Walker Lane and Long Valley Caldera Regions

NASA Astrophysics Data System (ADS)

Chacko, R.; Hammond, W. C.; Blewitt, G.; Bormann, J. M.

2014-12-01

Accurate estimates of fault slip rates based on geodetic data rely on measurements that represent the long-term deformation of the crust. In the Central Walker Lane/Sierra Nevada transition, the Long Valley Caldera region has experienced multiple episodes of uplift and subsidence during the last four decades. The latest episode began in late 2011 and is detectable as a transient signal in the time series of GPS stations around the caldera. These transient signals become more apparent and reveal the extent of the impact on the ambient crustal deformation field of the Walker Lane when the velocity vectors are transformed to a Sierra-Nevada reference frame. Estimating contemporary slip-rates on faults for the purpose of seismic hazard assessment in the region around Long Valley requires detecting and subtracting the transient signals caused by the uplift and subsidence in the caldera. We estimate the geographic extent to which the ambient crustal deformation field is significantly perturbed by ongoing magmatic activity in Long Valley. We present a time variable 3D deformation field constrained by InSAR and GPS observations, and discuss the implications that tectonic-magmatic interaction have for estimates of present-day fault slip-rate. We model the time dependent deformation at Long Valley by analyzing InSAR time series from Envisat and ERS interferograms spanning a period of more than 19 years. We use an analytical volcano deformation source model derived from vertical (GPS) and line of site (InSAR) component of geodetic observations to estimate the horizontal component of the signals associated with magmatic activity beneath the caldera. Previous studies showed that the latest episode of uplift can be modeled with a Mogi source located at a depth of ~6 km with a volume change of 0.03 km3 beneath the resurgent dome. This model predicts a perturbation to the ambient crustal deformation field extending as far as 60 km from the center of the resurgent dome. Thus the area affected by Long Valley extends from north of Mono Lake southward to Owens Lake, and eastward to the Mina deflection of the Walker Lane, potentially influencing the estimated slip rates for a dozen or more major faults.

Crustal Deformation of the Central Walker Lane from GPS velocities: Block Rotations and Slip Rates

NASA Astrophysics Data System (ADS)

Bormann, J. M.; Hammond, W. C.; Kreemer, C. W.; Blewitt, G.; Wesnousky, S. G.

2010-12-01

The Walker Lane is a complex zone of active intracontinental transtension between the Sierra Nevada/Great Valley (SNGV) microplate and the Basin and Range in the western United States. Collectively, this ~100 km wide zone accommodates ~20% of the Pacific-North American relative plate motion. The Central Walker Lane (CWL) extends from the southern boundary of the Mina Deflection (~38.0°N) to the latitude of Lake Tahoe (~39.5°N) and encompasses the transition from Basin and Range style faulting in the east to the stable block motion of the SNGV microplate in the West. We combine GPS data from the Mobile Array of GPS for Nevada Transtension (MAGNET, http://geodesy.unr.edu/networks) with continuous observations from the EarthScope Plate Boundary Observatory to solve for rates of crustal deformation in the CWL through a block modeling approach. The GPS coordinate time series are derived in this region as part of a 7000-station global network solution using the latest JPL reanalysis of GPS orbits, and the latest antenna models for stations and satellites. The data were processed by precise point positioning using JPL's GIPSY OASIS II software followed by our custom Ambizap3 software, to produce a globally-consistent, ambiguity-resolved network solution. GPS time series in the western United States are rotated into a North America-fixed reference frame and are spatially filtered with respect to the secular motions of reference stations that demonstrate long-term secular stability. In the study region, we use 130 GPS velocities that are corrected for viscoelastic postseismic relaxation following 19th and 20th century earthquakes in the Central Nevada Seismic Belt to constrain rates of long-term fault slip and block rotation. The spatial density and precision of our velocity field (average station spacing of ~20 km with uncertainties well below 1 mm/yr) allow us to compare geodetically estimated slip rates with geologic observations as well as address specific questions about how shear is transferred from the Southern Walker Lane through the Mina Deflection and evaluate along-strike variation of the slip rate on the Sierra Nevada range front fault. Preliminary results confirm a pattern of deformation consistent with geological observations. Deformation zones are characterized by 1) left-lateral slip on east-northeast trending faults and clockwise block rotations in the Mina Deflection, 2) right-lateral slip on northwest trending faults along the eastern margin of the CWL, 3) east-west extension along north trending faults in the western portion of the CWL with right lateral slip increasing toward the SNGV microplate boundary, 4) clockwise rotation of blocks in the Carson Domain, and 5) northwest directed extension in the Basin and Range. Estimates of fault slip rates along the eastern boundary of the SNGV block find that slip is oblique with preliminary rates ranging between 0.4-0.8(±0.1) mm/yr horizontal extension and 0.9-1.5(±0.1) mm/yr right lateral.

Differential Extension, Displacement Transfer, and the South to North Decrease in Displacement on the Furnace Creek - Fish Lake Valley Fault System, Western Great Basin.

NASA Astrophysics Data System (ADS)

Katopody, D. T.; Oldow, J. S.

2015-12-01

The northwest-striking Furnace Creek - Fish Lake Valley (FC-FLV) fault system stretches for >250 km from southeastern California to western Nevada, forms the eastern boundary of the northern segment of the Eastern California Shear Zone, and has contemporary displacement. The FC-FLV fault system initiated in the mid-Miocene (10-12 Ma) and shows a south to north decrease in displacement from a maximum of 75-100 km to less than 10 km. Coeval elongation by extension on north-northeast striking faults within the adjoining blocks to the FC-FLV fault both supply and remove cumulative displacement measured at the northern end of the transcurrent fault system. Elongation and displacement transfer in the eastern block, constituting the southern Walker Lane of western Nevada, exceeds that of the western block and results in the net south to north decrease in displacement on the FC-FLV fault system. Elongation in the eastern block is accommodated by late Miocene to Pliocene detachment faulting followed by extension on superposed, east-northeast striking, high-angle structures. Displacement transfer from the FC-FLV fault system to the northwest-trending faults of the central Walker Lane to the north is accomplished by motion on a series of west-northwest striking transcurrent faults, named the Oriental Wash, Sylvania Mountain, and Palmetto Mountain fault systems. The west-northwest striking transcurrent faults cross-cut earlier detachment structures and are kinematically linked to east-northeast high-angle extensional faults. The transcurrent faults are mapped along strike for 60 km to the east, where they merge with north-northwest faults forming the eastern boundary of the southern Walker Lane. The west-northwest trending transcurrent faults have 30-35 km of cumulative left-lateral displacement and are a major contributor to the decrease in right-lateral displacement on the FC-FLV fault system.

Contemporary tectonic deformation of the Basin and Range province, western United States: 10 years of observation with the Global Positioning System

USGS Publications Warehouse

Hammond, W.C.; Thatcher, W.

2004-01-01

We have estimated patterns and rates of crustal movement across 800 km of the Basin and Range at ???39?? north latitude with Global Positioning System surveys in 1992, 1996, 1998, and 2002. The total rate of motion tangent to the small circle around the Pacific-North America pole of rotation is 10.4 ?? 1.0 mm/yr, and motion normal to this small circle is 3.9 ?? 0.9 mm/yr compared to the east end of our network. On the Colorado Plateau the east end of our network moves by ???1-2 mm/yr westerly with respect to North America. Transitions in strain rates delimit six major tectonic domains within the province. These deformation zones coincide with areas of modern seismicity and are, from east to west, (1) east-west extension in the Wasatch Fault zone, (2) low rate east-west extension centered near the Nevada-Utah border, (3) low rate east-west contraction between 114.7??W and 117.9??W, (4) extension normal to and strike-slip motion across the N10??E striking Central Nevada Seismic Zone, (5) right lateral simple shear oriented N13??W inside the Walker Lane Belt, and (6) shear plus extension near the Sierra Nevada frontal faults. Concentration of shear and dilatational deformation across the three westernmost zones suggests that the Walker Lane Belt lithosphere is rheologically weak. However, we show that linear gradients in viscosity and gravitational potential energy can also effectively concentrate deformation. In the Basin and Range, gradients in gravitational potential are spatially anticorrelated with dilatational strain rates, consistent with the presence of horizontal variations in viscosity of the lithosphere.

Paleomagnetic Data Bearing on the Eastern and Southern Boundaries of the Walker Lane Belt Transfer System

NASA Astrophysics Data System (ADS)

Grow, J. S.; Geissman, J. W.; Oldow, J. S.

2007-12-01

In west-central Nevada, a transfer zone, which initiated in the mid-Miocene, presently links, via the Mina Deflection, right-lateral faults of the Eastern California Shear Zone to the south and the Central Nevada Seismic Belt and Walker Lane to the north. This transfer zone, the early inception of which is characterized by moderate (20-30°) clockwise crustal rotations previously identified (e.g., Candelaria Hills and surrounding ranges), along with right-lateral structures to the south and north, are part of a diffuse zone of intracontinental deformation that accommodates some 25 percent of the motion between the Pacific and North American plates. Although the northern and western boundaries of the transfer zone are relatively well defined by paleomagnetic data, the eastern and southeastern boundaries remain poorly constrained. Additional paleomagnetic data are being obtained from mid-to-late Tertiary volcanic rocks, presumably lying within (e.g., Montezuma Range, Palmetto Mountains, Monte Cristo Range) and outside (e.g., Goldfield Hills, San Antonio Mountains, Slate Ridge) of the transfer zone. Areas outside of the transfer zone are inferred to have not undergone any appreciable rotation since its inception. Volcanic rocks as well as shallow intrusions ranging in age from Oligocene to mid-Pliocene have been sampled (N=187) from inside and outside of the inferred southern and eastern boundaries of the transfer zone. Overall, the collection responds very favorably to progressive demagnetization; initial results are tentatively interpreted as suggesting the absence of appreciable rotation of the San Antonio Range (Tonopah, Nevada area and farther north). The extent to which areas near the eastern and southeastern boundaries have been rotated is under investigation. These data will aid in a better understanding of differential block rotation and tilting throughout the development of the west-central Nevada transfer system from the mid-Miocene to late Pliocene.

Evolution of Late Miocene to Contemporary Displacement Transfer Between the Northern Furnace Creek and Southern Fish Lake Valley Fault Zones and the Central Walker Lane, Western Great Basin, Nevada

NASA Astrophysics Data System (ADS)

Oldow, J. S.; Geissman, J. W.

2013-12-01

Late Miocene to contemporary displacement transfer from the north Furnace Creek (FCF) and southern Fish Lake Valley (FLVF) faults to structures in the central Walker Lane was and continues to be accommodated by a belt of WNW-striking left-oblique fault zones in the northern part of the southern Walker Lane. The WNW fault zones are 2-9 km wide belts of anastomosing fault strands that intersect the NNW-striking FCF and southern FLVF in northern Death Valley and southern Fish Lake Valley, respectively. The WNW fault zones extend east for over 60 km where they merge with a 5-10 km wide belt of N10W striking faults that marks the eastern boundary of the southern Walker Lane. Left-oblique displacement on WNW faults progressively decreases to the east, as motion is successively transferred northeast on NNE-striking faults. NNE faults localize and internally deform extensional basins that each record cumulative net vertical displacements of between 3.0 and 5.2 km. The transcurrent faults and associated basins decrease in age from south to north. In the south, the WNW Sylvania Mountain fault system initiated left-oblique motion after 7 Ma but does not have evidence of contemporary displacement. Farther north, the left-oblique motion on the Palmetto Mountain fault system initiated after 6.0 to 4.0 Ma and has well-developed scarps in Quaternary deposits. Cumulative left-lateral displacement for the Sylvania Mountain fault system is 10-15 km, and is 8-12 km for the Palmetto fault system. The NNE-striking faults that emanate from the left-oblique faults merge with NNW transcurrent faults farther north in the eastern part of the Mina deflection, which links the Owens Valley fault of eastern California to the central Walker Lane. Left-oblique displacement on the Sylvania Mountain and Palmetto Mountain fault zones deformed the Furnace Creek and Fish Lake Valley faults. Left-oblique motion on Sylvania Mountain fault deflected the FCF into the 15 km wide Cucomungo Canyon restraining bend, segmented the >3.0 km deep basin underlying southern Fish Lake Valley, and formed a 2 km wide restraining bend in the FLVF. Part of the left-oblique motion on the Palmetto Mountain fault zone crosses Fish Lake Valley and offsets the FLVF in a 3 km wide restraining bend with the remainder being taken-up by NNW structures along the eastern side of southern Fish Lake Valley.

A Kinematic Model for Vertical Axis Rotation within the Mina Deflection of the Walker Lane

NASA Astrophysics Data System (ADS)

Gledhill, T.; Pluhar, C. J.; Johnson, S. A.; Lindeman, J. R.; Petronis, M. S.

2016-12-01

The Mina Deflection, at the boundary between the Central and Southern Walker Lane, spans the California-Nevada border and includes a heavily-faulted Pliocene volcanic field overlying Miocene ignimbrites. The dextral Walker Lane accommodates 25% of relative Pacific-North America plate motion and steps right across the sinistral Mina deflection. Ours and previous work shows that the Mina Deflection partially accommodates deformation by vertical-axis rotation of up to 99.9o ± 6.1o rotation since 11 Ma. This rotation is evident in latite ignimbrite of Gilbert et al. (1971), which we have formalized as three members of Tuff of Huntoon Creek (THC). The welded, basal, normal-polarity Huntoon Valley Member of THC is overlain by the unwelded to partially-welded, reversed-polarity Adobe Hills Mbr. This member includes internal breaks suggesting multiple eruptive phases, but the paleomagnetic results from each are statistically indistinguishable, meaning that they were likely erupted in rapid succession (within a few centuries of one another). THC ends with a welded member exhibiting very shallow inclination and south declination that we call Excursional Mbr. One of the upper members has been dated at 11.17 ± 0.04 Ma. These Miocene units are overlain by Pliocene basalts, Quaternary alluvium, and lacustrine deposits. Our paleomagnetic results show a gradient between the zero rotation domain and high rotation across a 20km baseline. A micropolar model, based on 25 years of earthquake data from the Northern and Southern California Seismic Network, suggest the Mina Deflection is currently experiencing transpressional seismogenic deformation (Unruh et al., 2003). Accepting Unruh's model and assuming continuous rotation since 11 Ma, we propose a kinematic model for the western Mina Deflection that accommodates 90o of vertical axis rotation from N-S to ENE-WSW oriented blocks.

Latest Quaternary paleoseismology and evidence of distributed dextral shear along the Mohawk Valley fault zone, northern Walker Lane, California

USGS Publications Warehouse

Gold, Ryan D.; Briggs, Richard; Personius, Stephen; Crone, Anthony J.; Mahan, Shannon; Angster, Stephen

2014-01-01

The dextral-slip Mohawk Valley fault zone (MVFZ) strikes northwestward along the eastern margin of the Sierra Nevada in the northern Walker Lane. Geodetic block modeling indicates that the MVFZ may accommodate ~3 mm/yr of regional dextral strain, implying that it is the highest slip-rate strike-slip fault in the region; however, only limited geologic data are available to constrain the system’s slip rate and earthquake history. We mapped the MVFZ using airborne lidar data and field observations and identified a site near Sulphur Creek for paleoseismic investigation. At this site, oblique dextral-normal faulting on the steep valley margin has created a closed depression that floods annually during spring snowmelt to form an ephemeral pond. We excavated three fault-perpendicular trenches at the site and exposed pond sediment that interfingers with multiple colluvial packages eroded from the scarp that bounds the eastern side of the pond. We documented evidence for four surface-rupturing earthquakes on this strand of the MVFZ. OxCal modeling of radiocarbon and luminescence ages indicates that these earthquakes occurred at 14.0 ka, 12.8 ka, 5.7 ka, and 1.9 ka. The mean ~4 kyr recurrence interval is inconsistent with slip rates of ~3 mm/yr; these rates imply surface ruptures of more than 10 m per event, which is geologically implausible for the subdued geomorphic expression and 60 km length of the MVFZ. We propose that unidentified structures not yet incorporated into geodetic models may accommodate significant dextral shear across the northern Walker Lane, highlighting the role of distributed deformation in this region.

The application of active-source seismic imaging techniques to transtensional problems the Walker Lane and Salton Trough

NASA Astrophysics Data System (ADS)

Kell, Anna Marie

The plate margin in the western United States is an active tectonic region that contains the integrated deformation between the North American and Pacific plates. Nearly focused plate motion between the North American and Pacific plates within the northern Gulf of California gives way north of the Salton Trough to more diffuse deformation. In particular a large fraction of the slip along the southernmost San Andreas fault ultimately bleeds eastward, including about 20% of the total plate motion budget that finds its way through the transtensional Walker Lane Deformation Belt just east of the Sierra Nevada mountain range. Fault-bounded ranges combined with intervening low-lying basins characterize this region; the down-dropped features are often filled with water, which present opportunities for seismic imaging at unprecedented scales. Here I present active-source seismic imaging from the Salton Sea and Walker Lane Deformation Belt, including both marine applications in lakes and shallow seas, and more conventional land-based techniques along the Carson range front. The complex fault network beneath the Salton Trough in eastern California is the on-land continuation of the Gulf of California rift system, where North American-Pacific plate motion is accommodated by a series of long transform faults, separated by small pull-apart, transtensional basins; the right-lateral San Andreas fault bounds this system to the north where it carries, on average, about 50% of total plate motion. The Salton Sea resides within the most youthful and northerly "spreading center" in this several thousand-kilometer-long rift system. The Sea provides an ideal environment for the use of high-data-density marine seismic techniques. Two active-source seismic campaigns in 2010 and 2011 show progression of the development of the Salton pull-apart sub-basin and the northerly propagation of the Imperial-San Andreas system through time at varying resolutions. High fidelity seismic imagery documents the timing of strain transfer from the Imperial fault onto the San Andreas fault through the application of sequence stratigraphy. Evidence shows that the formation of the Salton and Mesquite sub-basins and the associated change of strain partitioning occurred within the last 20-40 k.y., essentially modifying a broader zone of transtension bounding the Imperial and San Andreas faults into two smaller zones of focused extension. The north-central Walker Lane contains a diffuse network of both strike-slip and normal faults, with some degree of strain partitioning characterized by normal faulting to the west along the eastern edge of the Sierra Nevada mountain range, and strike-slip faults to the east that define a diffuse boundary against the Basin and Range proper. A seismic study across the Mount Rose fault zone, bounding the Carson Range near Reno, Nevada, was carried out to investigate slip across a potential low-angle normal fault. A hammer seismic reflection and refraction profile combined with airborne LiDAR (light detection and ranging) imagery highlights fault scarp modification through minor slumping/landslides, providing a better understanding of the nature of slip on this fault. The northeastern margin of the Walker Lane is a region where both "Basin and Range" style normal faults and dextral strike-slip faults contribute to the northward propagation of the Walker Lane (essentially parallel to an equivalent northward propagation of the Mendocino triple junction). Near this intersection lies Pyramid Lake, bounded to the southwest by the dextral Pyramid Lake fault and to the northeast by the normal Lake Range fault. A high-resolution (sub-meter) seismic CHIRP survey collected in 2010 shows intriguing relationships into fault architecture beneath Pyramid Lake. Over 500 line-km of seismic data reveal a polarity flip in basin structure as down-to-the-east motion at the northern end of the Pyramid Lake fault rapidly gives way to down-to-the-west normal motion along the Lake Range fault. Alternating patterns of asymmetric and symmetric stratal patterns west of the Lake Range fault provides some evidence for segmentation of total slip along this large normal fault. Using dated sediment cores, slip rate for the Lake Range fault was found to be approximately 1 mm/yr during the Holocene. A complex zone of transtenstion was also observed in seismic CHIRP data in the northwest quadrant of the lake, where short, discontinuous faults hint at the development of a nascent shear zone trending to the northwest. (Abstract shortened by UMI.)

Geodetic Constraints on Fault Slip Rates and Seismic Hazard in the Greater Las Vegas Area

NASA Astrophysics Data System (ADS)

Hammond, W. C.; Kreemer, C.; Blewitt, G.; Broermann, J.; Bennett, R. A.

2014-12-01

We address fundamental questions about how contemporary tectonic deformation of the crust in the southern Great Basin occurs in the region around Las Vegas (LV) Nevada, western Arizona and eastern California. This area lies in the intersection of the eastern Walker Lane Belt, southern Great Basin and western Colorado Plateau (CP), sharing features of transtensional and extensional deformation associated with Pacific/North America relative motion. We use GPS data collected from 48 stations of the MAGNET semi-continuous network and 77 stations from continuous networks including BARGEN and EarthScope Plate Boundary Observatory. MAGNET stations have been observed for a minimum of 7 years, while most continuous stations have longer records. From these data we estimate the velocity of crustal motion for all stations with respect to the stable North America reference frame NA12. To correct for transients from recent large earthquakes including the 1999 Hector Mine and 2010 El Mayor-Cucapah events we use models of co- and post-seismic deformation, subtracting the predicted motions from the time series before estimating interseismic stain rates. We find approximately 2 mm/yr of relative motion distributed over 200 km centered on Las Vegas, with a mean strain accumulation rate of 10 × 10-9 yr-1, with lower rates of predominantly extensional strain to the east and higher rates of predominantly shear deformation to the west. The mean strain rate is lower than that of the western Walker Lane but about twice that of eastern Nevada where e.g., the Wells, NV MW 6.0 earthquake occurred in 2008. From this new velocity field we generated a horizontal tensor strain rate map and a crustal block motion model to portray the transition of active strain from the CP into the Walker Lane. For faults in the Las Vegas Valley, including the Eglington Fault and Frenchman Mountain Fault, the observed velocity gradients and model results are consistent with normal slip rates of 0.2 mm/yr, which are typical for the region. The Stateline Fault system experiences dextral slip of at least 0.4 mm/yr while normal faults south of LV collectively accommodate 0.9 mm/yr of east-west extension across a zone ~150 km wide. We see no evidence for concentrations of deformation or isolated rigid microplates within this zone.

InSAR Analysis of the 2011 Hawthorne (Nevada) Earthquake Swarm: Implications of Earthquake Migration and Stress Transfer

NASA Astrophysics Data System (ADS)

Zha, X.; Dai, Z.; Lu, Z.

2015-12-01

The 2011 Hawthorne earthquake swarm occurred in the central Walker Lane zone, neighboring the border between California and Nevada. The swarm included an Mw 4.4 on April 13, Mw 4.6 on April 17, and Mw 3.9 on April 27. Due to the lack of the near-field seismic instrument, it is difficult to get the accurate source information from the seismic data for these moderate-magnitude events. ENVISAT InSAR observations captured the deformation mainly caused by three events during the 2011 Hawthorne earthquake swarm. The surface traces of three seismogenic sources could be identified according to the local topography and interferogram phase discontinuities. The epicenters could be determined using the interferograms and the relocated earthquake distribution. An apparent earthquake migration is revealed by InSAR observations and the earthquake distribution. Analysis and modeling of InSAR data show that three moderate magnitude earthquakes were produced by slip on three previously unrecognized faults in the central Walker Lane. Two seismogenic sources are northwest striking, right-lateral strike-slip faults with some thrust-slip components, and the other source is a northeast striking, thrust-slip fault with some strike-slip components. The former two faults are roughly parallel to each other, and almost perpendicular to the latter one. This special spatial correlation between three seismogenic faults and nature of seismogenic faults suggest the central Walker Lane has been undergoing southeast-northwest horizontal compressive deformation, consistent with the region crustal movement revealed by GPS measurement. The Coulomb failure stresses on the fault planes were calculated using the preferred slip model and the Coulomb 3.4 software package. For the Mw4.6 earthquake, the Coulomb stress change caused by the Mw4.4 event increased by ~0.1 bar. For the Mw3.9 event, the Coulomb stress change caused by the Mw4.6 earthquake increased by ~1.0 bar. This indicates that the preceding earthquake may trigger the subsequence one. Because no abnormal volcano activity was observed during the 2011 Hawthorne earthquake swarm, we can rule out the volcano activity to induce these events. However, the groundwater change and mining in the epicentral zone may contribute to the 2011 Hawthorne earthquake.

Magmatism and Epithermal Gold-Silver Deposits of the Southern Ancestral Cascade Arc, Western Nevada and Eastern California

USGS Publications Warehouse

John, David A.; du Bray, Edward A.; Henry, Christopher D.; Vikre, Peter

2015-01-01

Many epithermal gold-silver deposits are temporally and spatially associated with late Oligocene to Pliocene magmatism of the southern ancestral Cascade arc in western Nevada and eastern California. These deposits, which include both quartz-adularia (low- and intermediate-sulfidation; Comstock Lode, Tonopah, Bodie) and quartz-alunite (high-sulfidation; Goldfield, Paradise Peak) types, were major producers of gold and silver. Ancestral Cascade arc magmatism preceded that of the modern High Cascades arc and reflects subduction of the Farallon plate beneath North America. Ancestral arc magmatism began about 45 Ma, continued until about 3 Ma, and extended from near the Canada-United States border in Washington southward to about 250 km southeast of Reno, Nevada. The ancestral arc was split into northern and southern segments across an inferred tear in the subducting slab between Mount Shasta and Lassen Peak in northern California. The southern segment extends between 42°N in northern California and 37°N in western Nevada and was active from about 30 to 3 Ma. It is bounded on the east by the northeast edge of the Walker Lane. Ancestral arc volcanism represents an abrupt change in composition and style of magmatism relative to that in central Nevada. Large volume, caldera-forming, silicic ignimbrites associated with the 37 to 19 Ma ignimbrite flareup are dominant in central Nevada, whereas volcanic centers of the ancestral arc in western Nevada consist of andesitic stratovolcanoes and dacitic to rhyolitic lava domes that mostly formed between 25 and 4 Ma. Both ancestral arc and ignimbrite flareup magmatism resulted from rollback of the shallowly dipping slab that began about 45 Ma in northeast Nevada and migrated south-southwest with time. Most southern segment ancestral arc rocks have oxidized, high potassium, calc-alkaline compositions with silica contents ranging continuously from about 55 to 77 wt%. Most lavas are porphyritic and contain coarse plagioclase ± hornblende, biotite, and pyroxene phenocrysts. Seven epithermal gold-silver deposits with >1 Moz gold production, several large elemental sulfur deposits, and many large areas (10s to >100 km2) of hydrothermally altered rocks are present in the southern ancestral arc, especially south of latitude 40°N. These deposits are principally hosted by intermediate to silicic lava dome complexes; only a few deposits are associated with mafic- to intermediate-composition stratovolcanoes. Large deposits are most abundant and well developed in volcanic fields whose evolution spanned millions of years. Most deposits are hundreds of thousands to several million years younger than their host rocks, although some quartz-alunite deposits are essentially coeval with their host rocks. Variable composition and thickness of crustal basement is the primary control on mineralization along the length of the southern ancestral arc; most deposits and large alteration zones are localized in basement rock terranes with a strong continental affinity, either along the edge of the North American craton (Goldfield, Tonopah) or in an accreted terrane with continental affinities (Walker Lake terrane; Aurora, Bodie, Comstock Lode, Paradise Peak). Epithermal deposits and quartz-alunite alteration zones are scarce to absent in the northern part of the ancestral arc above an accreted island arc (Black Rock terrane) or unknown basement rocks (Modoc Plateau). Walker Lane structures and areas that underwent large magnitude extension during the Late Cenozoic (areas with Oligocene-early Miocene volcanic rocks dipping >40°) do not provide regional control on mineralization. Instead, these features may have served as local-scale conduits for mineralizing fluids.

Fault Imaging with High-Resolution Seismic Reflection for Earthquake Hazard and Geothermal Resource Assessment in Reno, Nevada

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

Frary, Roxanna

2012-05-05

The Truckee Meadows basin is situated adjacent to the Sierra Nevada microplate, on the western boundary of the Walker Lane. Being in the transition zone between a range-front normal fault on the west and northwest-striking right-lateral strike slip faults to the east, there is no absence of faulting in this basin. The Reno- Sparks metropolitan area is located in this basin, and with a signi cant population living here, it is important to know where these faults are. High-resolution seismic reflection surveys are used for the imaging of these faults along the Truckee River, across which only one fault wasmore » previously mapped, and in southern Reno near and along Manzanita Lane, where a swarm of short faults has been mapped. The reflection profiles constrain the geometries of these faults, and suggest additional faults not seen before. Used in conjunction with depth to bedrock calculations and gravity measurements, the seismic reflection surveys provide de nitive locations of faults, as well as their orientations. O sets on these faults indicate how active they are, and this in turn has implications for seismic hazard in the area. In addition to seismic hazard, the faults imaged here tell us something about the conduits for geothermal fluid resources in Reno.« less

Digital Geologic Map of the Nevada Test Site and Vicinity, Nye, Lincoln, and Clark Counties, Nevada, and Inyo County, California

USGS Publications Warehouse

Slate, Janet L.; Berry, Margaret E.; Rowley, Peter D.; Fridrich, Christopher J.; Morgan, Karen S.; Workman, Jeremiah B.; Young, Owen D.; Dixon, Gary L.; Williams, Van S.; McKee, Edwin H.; Ponce, David A.; Hildenbrand, Thomas G.; Swadley, W.C.; Lundstrom, Scott C.; Ekren, E. Bartlett; Warren, Richard G.; Cole, James C.; Fleck, Robert J.; Lanphere, Marvin A.; Sawyer, David A.; Minor, Scott A.; Grunwald, Daniel J.; Laczniak, Randell J.; Menges, Christopher M.; Yount, James C.; Jayko, Angela S.

1999-01-01

This digital geologic map of the Nevada Test Site (NTS) and vicinity, as well as its accompanying digital geophysical maps, are compiled at 1:100,000 scale. The map compilation presents new polygon (geologic map unit contacts), line (fault, fold axis, metamorphic isograd, dike, and caldera wall) and point (structural attitude) vector data for the NTS and vicinity, Nye, Lincoln, and Clark Counties, Nevada, and Inyo County, California. The map area covers two 30 x 60-minute quadrangles-the Pahute Mesa quadrangle to the north and the Beatty quadrangle to the south-plus a strip of 7.5-minute quadrangles on the east side-72 quadrangles in all. In addition to the NTS, the map area includes the rest of the southwest Nevada volcanic field, part of the Walker Lane, most of the Amargosa Desert, part of the Funeral and Grapevine Mountains, some of Death Valley, and the northern Spring Mountains. This geologic map improves on previous geologic mapping of the same area (Wahl and others, 1997) by providing new and updated Quaternary and bedrock geology, new geophysical interpretations of faults beneath the basins, and improved GIS coverages. Concurrent publications to this one include a new isostatic gravity map (Ponce and others, 1999) and a new aeromagnetic map (Ponce, 1999).

Temporal variations in extension rate on the Lone Mountain fault and strain distribution in the eastern California shear zone-Walker Lane

NASA Astrophysics Data System (ADS)

Hoeft, J. S.; Frankel, K. L.

2010-12-01

The eastern California shear zone (ECSZ) and Walker Lane represent an evolving segment of the Pacific-North America plate boundary. Understanding temporal variations in strain accumulation and release along plate boundary structures is critical to assessing how deformation is accommodated throughout the lithosphere. Late Pleistocene displacement along the Lone Mountain fault suggests the Silver Peak-Lone Mountain (SPLM) extensional complex is an important structure in accommodating and transferring strain within the ECSZ and Walker Lane. Using geologic and geomorphic mapping, differential global positioning system surveys, and terrestrial cosmogenic nuclide (TCN) geochronology, we determined rates of extension across the Lone Mountain fault in western Nevada. The Lone Mountain fault displaces the northwestern Lone Mountain and Weepah Hills piedmonts and is the northeastern component of the SPLM extensional complex, a series of down-to-the-northwest normal faults. We mapped seven distinct alluvial fan deposits and dated three of the surfaces using 10Be TCN geochronology, yielding ages of 16.5 ± 1.2 ka, 92 ± 9 ka, and 137 ± 25 ka for the Q3b, Q2c, and Q2b deposits, respectively. The ages were combined with scarp profile measurements across the displaced fans to obtain minimum rates of extension; the Q2b and Q2c surfaces yield an extension rate between 0.1 ± 0.1 and 0.2 ± 01 mm/yr and the Q3b surface yields a rate of 0.2 ± 0.1 to 0.4 ± 0.1 mm/yr, depending on the dip of the fault. Active extension on the Lone Mountain fault suggests that it helps partition strain off of the major strike-slip faults in the northern ECSZ and transfers deformation to the east around the Mina Deflection and northward into the Walker Lane. Combining our results with estimates from other faults accommodating dextral shear in the northern ECSZ reveals an apparent discrepancy between short- and long-term rates of strain accumulation and release. If strain rates have remained constant since the late Pleistocene, this could reflect transient strain accumulation, similar to the Mojave segment of the ECSZ. However, our data also suggest a potential increase in strain rates between ~92 ka and ~17 ka, and possibly to present day, which may also help explain the mismatch between long- and short-term rates of deformation in the region.

Surface faulting and paleoseismic history of the 1932 Cedar Mountain earthquake area, west-central Nevada, and implications for modern tectonics of the Walker Lane

USGS Publications Warehouse

Bell, J.W.; DePolo, C.M.; Ramelli, A.R.; Sarna-Wojcicki, A. M.; Meyer, C.E.

1999-01-01

The 1932 Cedar Mountain earthquake (Ms 7.2) was one of the largest historical events in the Walker Lane region of western Nevada, and it produced a complicated strike-slip rupture pattern on multiple Quaternary faults distributed through three valleys. Primary, right-lateral surface ruptures occurred on north-striking faults in Monte Cristo Valley; small-scale lateral and normal offsets occurred in Stewart Valley; and secondary, normal faulting occurred on north-northeast-striking faults in the Gabbs Valley epicentral region. A reexamination of the surface ruptures provides new displacement and fault-zone data: maximum cumulative offset is estimated to be 2.7 m, and newly recognized faults extend the maximum width and end-to-end length of the rupture zone to 17 and 75 km, respectively. A detailed Quaternary allostratigraphic chronology based on regional alluvialgeomorphic relationships, tephrochronology, and radiocarbon dating provides a framework for interpreting the paleoseismic history of the fault zone. A late Wisconsinan alluvial-fan and piedmont unit containing a 32-36 ka tephra layer is a key stratigraphic datum for paleoseismic measurements. Exploratory trenching and radiocarbon dating of tectonic stratigraphy provide the first estimates for timing of late Quaternary faulting along the Cedar Mountain fault zone. Three trenches display evidence for six faulting events, including that in 1932, during the past 32-36 ka. Radiocarbon dating of organic soils interstratified with tectonically ponded silts establishes best-fit ages of the pre-1932 events at 4, 5,12,15, and 18 ka, each with ??2 ka uncertainties. On the basis of an estimated cumulative net slip of 6-12 m for the six faulting events, minimum and maximum late Quaternary slip rates are 0.2 and 0.7 mm/yr, respectively, and the preferred rate is 0.4-0.5 mm/yr. The average recurrence (interseismic) interval is 3600 yr. The relatively uniform thickness of the ponded deposits suggests that similar-size, characteristic rupture events may characterize late Quaternary slip on the zone. A comparison of event timing with the average late Quaternary recurrence interval indicates that slip has been largely regular (periodic) rather than temporally clustered. To account for the spatial separation of the primary surface faulting in Monte Cristo Valley from the epicenter and for a factor-of-two-to-three disparity between the instrumentally and geologically determined seismic moments associated with the earthquake, we hypothesize two alternative tectonic models containing undetected subevents. Either model would adequately account for the observed faulting on the basis of wrench-fault kinematics that may be associated with the Walker Lane. The 1932 Cedar Mountain earthquake is considered an important modern analogue for seismotectonic modeling and estimating seismic hazard in the Walker Lane region. In contrast to most other historical events in the Basin and Range province, the 1932 event did not occur along a major range-bounding fault, and no single, throughgoing basement structure can account for the observed rupture pattern. The 1932 faulting supports the concept that major earthquakes in the Basin and Range province can exhibit complicated distributive rupture patterns and that slip rate may not be a reliable criterion for modeling seismic hazard.

Late quaternary slip-rate variations along the Warm Springs Valley fault system, northern Walker Lane, California-Nevada border

USGS Publications Warehouse

Gold, Ryan; dePolo, Craig; Briggs, Richard W.; Crone, Anthony

2013-01-01

The extent to which faults exhibit temporally varying slip rates has important consequences for models of fault mechanics and probabilistic seismic hazard. Here, we explore the temporal behavior of the dextral‐slip Warm Springs Valley fault system, which is part of a network of closely spaced (10–20 km) faults in the northern Walker Lane (California–Nevada border). We develop a late Quaternary slip record for the fault using Quaternary mapping and high‐resolution topographic data from airborne Light Distance and Ranging (LiDAR). The faulted Fort Sage alluvial fan (40.06° N, 119.99° W) is dextrally displaced 98+42/-43 m, and we estimate the age of the alluvial fan to be 41.4+10.0/-4.8 to 55.7±9.2  ka, based on a terrestrial cosmogenic 10Be depth profile and 36Cl analyses on basalt boulders, respectively. The displacement and age constraints for the fan yield a slip rate of 1.8 +0.8/-0.8 mm/yr to 2.4 +1.2/-1.1 mm/yr (2σ) along the northern Warm Springs Valley fault system for the past 41.4–55.7 ka. In contrast to this longer‐term slip rate, shorelines associated with the Sehoo highstand of Lake Lahontan (~15.8  ka) adjacent to the Fort Sage fan are dextrally faulted at most 3 m, which limits a maximum post‐15.8 ka slip rate to 0.2  mm/yr. These relations indicate that the post‐Lahontan slip rate on the fault is only about one‐tenth the longer‐term (41–56 ka) average slip rate. This apparent slip‐rate variation may be related to co‐dependent interaction with the nearby Honey Lake fault system, which shows evidence of an accelerated period of mid‐Holocene earthquakes.

Sierra Nevada Mountain Range as seen from STS-58

NASA Image and Video Library

1994-10-20

STS058-72-004 (18 Oct-1 Nov 1993) --- The Sierra Nevada Mountain Range can be seen in this north-looking high oblique view taken in October, 1993, by the STS-58 crew. Visible in the view to the west of the Sierra Nevada are the San Joaquin and Sacramento Valleys of central California. The San Francisco/Oakland Bay Area can be seen to the west of the valley at the extreme left of the photograph. To the east or right of the Sierra Nevada, the basin and Range Region of central and northern Nevada is visible. Mono Lake, Lake Tahoe and Pyramid Lake are also visible in this scene. The long northwest/southeast trending Walker Lane Shear Zone, which lies just to the east (right) of the Sierra Nevada is also visible. Near the top of the view (near the horizon), the snow covered volcanic peak Mount Shasta can be seen. Over 645 kilometers (400 miles) long and from 65 to 130 kilometers (40 to 80 miles) wide, the Sierra Nevada have many peaks in excess of 3,300 meters (11,000 feet) above sea level. A titled fault block in structure (the largest in the United States) and shaped by glaciers during the last ice age over 12,000 years ago, the Sierra Nevada eastern front rises sharply from the Great Basin of Nevada, while its western slope descends gradually to the hills bordering the Central Valley of California. Snow-fed streams supply much of the irrigation water to the Central Valley and to western Nevada and also generate hydroelectricity. Recent above normal precipitation (snowfall) of the last two years has helped in alleviating the drought conditions that had prevailed throughout most of California in the mid and late 1980's and early 1990's.

GPS Imaging of Sierra Nevada Uplift

NASA Astrophysics Data System (ADS)

Hammond, W. C.; Blewitt, G.; Kreemer, C.

2015-12-01

Recent improvements in the scope and precision of GPS networks across California and Nevada have allowed for uplift of the Sierra Nevada to be observed directly. Much of the signal, in the range of 1 to 2 mm/yr, has been attributed to lithospheric scale rebound following massive groundwater withdrawal in the San Joaquin Valley in southern California, exacerbated by drought since 2011. However, natural tectonic deformation associated with long term uplift of the range may also contribute to the observed signal. We have developed new algorithms that enhance the signal of Sierra Nevada uplift and improve our ability to interpret and separate natural tectonic signals from anthropogenic contributions. We apply our new Median Interannual Difference Adjusted for Skewness (MIDAS) algorithm to the vertical times series and a inverse distance-weighted median spatial filtering and Delaunay-based interpolation to despeckle the rate map. The resulting spatially continuous vertical rate field is insensitive to outliers and steps in the GPS time series, and omits isolated features attributable to unstable stations or unrepresentative rates. The resulting vertical rate field for California and Nevada exhibits regionally coherent signals from the earthquake cycle including interseismic strain accumulation in Cascadia, postseismic relaxation of the mantle from recent large earthquakes in central Nevada and southern California, groundwater loading changes, and tectonic uplift of the Sierra Nevada and Coast Ranges. Uplift of the Sierra Nevada extends from the Garlock Fault in the south to an indefinite boundary in the north near the latitude of Mt. Lassen to the eastern Sierra Nevada range front in Owen's Valley. The rates transition to near zero in the southern Walker Lane. The eastern boundary of uplift coincides with the highest strain rates in the western Great Basin, suggesting higher normal fault slip rates and a component of tectonic uplift of the Sierra Nevada.

GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift

NASA Astrophysics Data System (ADS)

Hammond, William C.; Blewitt, Geoffrey; Kreemer, Corné

2016-10-01

We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5-20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011-2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane.

Hydrologic Setting and Conceptual Hydrologic Model of the Walker River Basin, West-Central Nevada

USGS Publications Warehouse

Lopes, Thomas J.; Allander, Kip K.

2009-01-01

The Walker River is the main source of inflow to Walker Lake, a closed-basin lake in west-central Nevada. Between 1882 and 2008, agricultural diversions resulted in a lake-level decline of more than 150 feet and storage loss of 7,400,000 acre-ft. Evaporative concentration increased dissolved solids from 2,500 to 17,000 milligrams per liter. The increase in salinity threatens the survival of the Lahontan cutthroat trout, a native species listed as threatened under the Endangered Species Act. This report describes the hydrologic setting of the Walker River basin and a conceptual hydrologic model of the relations among streams, groundwater, and Walker Lake with emphasis on the lower Walker River basin from Wabuska to Hawthorne, Nevada. The Walker River basin is about 3,950 square miles and straddles the California-Nevada border. Most streamflow originates as snowmelt in the Sierra Nevada. Spring runoff from the Sierra Nevada typically reaches its peak during late May to early June with as much as 2,800 cubic feet per second in the Walker River near Wabuska. Typically, 3 to 4 consecutive years of below average streamflow are followed by 1 or 2 years of average or above average streamflow. Mountain ranges are comprised of consolidated rocks with low hydraulic conductivities, but consolidated rocks transmit water where fractured. Unconsolidated sediments include fluvial deposits along the active channel of the Walker River, valley floors, alluvial slopes, and a playa. Sand and gravel deposited by the Walker River likely are discontinuous strata throughout the valley floor. Thick clay strata likely were deposited in Pleistocene Lake Lahontan and are horizontally continuous, except where strata have been eroded by the Walker River. At Walker Lake, sediments mostly are clay interbedded with alluvial slope, fluvial, and deltaic deposits along the lake margins. Coarse sediments form a multilayered, confined-aquifer system that could extend several miles from the shoreline. Depth to bedrock in the lower Walker River basin ranges from about 900 to 2,000 feet. The average hydraulic conductivity of the alluvial aquifer in the lower Walker River basin is 10-30 feet per day, except where comprised of fluvial sediments. Fluvial sediments along the Walker River have an average hydraulic conductivity of 70 feet per day. Subsurface flow was estimated to be 2,700 acre-feet per year through Double Spring. Subsurface discharge to Walker Lake was estimated to be 4,400 acre-feet per year from the south and 10,400 acre-feet per year from the north. Groundwater levels and groundwater storage have declined steadily in most of Smith and Mason Valleys since 1960. Groundwater levels around Schurz, Nevada, have changed little during the past 50 years. In the Whisky Flat area south of Hawthorne, Nevada, agricultural and municipal pumpage has lowered groundwater levels since 1956. The water-level decline in Walker Lake since 1882 has caused the surrounding alluvial aquifer to drain and groundwater levels to decline. The Wabuska streamflow-gaging station in northern Mason Valley demarcates the upper and lower Walker River basin. The hydrology of the lower Walker River basin is considerably different than the upper basin. The upper basin consists of valleys separated by consolidated-rock mountains. The alluvial aquifer in each valley thins or pinches out at the downstream end, forcing most groundwater to discharge along the river near where the river is gaged. The lower Walker River basin is one surface-water/groundwater system of losing and gaining reaches from Wabuska to Walker Lake, which makes determining stream losses and the direction and amount of subsurface flow difficult. Isotopic data indicate surface water and groundwater in the lower Walker River basin are from two sources of precipitation that have evaporated. The Walker River, groundwater along the Wassuk Range, and Walker Lake plot along one evaporation line. Groundwater along th

GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift

PubMed Central

Blewitt, Geoffrey; Kreemer, Corné

2016-01-01

Abstract We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5–20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011–2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane. PMID:27917328

GPS Imaging of vertical land motion in California and Nevada: Implications for Sierra Nevada uplift.

PubMed

Hammond, William C; Blewitt, Geoffrey; Kreemer, Corné

2016-10-01

We introduce Global Positioning System (GPS) Imaging, a new technique for robust estimation of the vertical velocity field of the Earth's surface, and apply it to the Sierra Nevada Mountain range in the western United States. Starting with vertical position time series from Global Positioning System (GPS) stations, we first estimate vertical velocities using the MIDAS robust trend estimator, which is insensitive to undocumented steps, outliers, seasonality, and heteroscedasticity. Using the Delaunay triangulation of station locations, we then apply a weighted median spatial filter to remove velocity outliers and enhance signals common to multiple stations. Finally, we interpolate the data using weighted median estimation on a grid. The resulting velocity field is temporally and spatially robust and edges in the field remain sharp. Results from data spanning 5-20 years show that the Sierra Nevada is the most rapid and extensive uplift feature in the western United States, rising up to 2 mm/yr along most of the range. The uplift is juxtaposed against domains of subsidence attributable to groundwater withdrawal in California's Central Valley. The uplift boundary is consistently stationary, although uplift is faster over the 2011-2016 period of drought. Uplift patterns are consistent with groundwater extraction and concomitant elastic bedrock uplift, plus slower background tectonic uplift. A discontinuity in the velocity field across the southeastern edge of the Sierra Nevada reveals a contrast in lithospheric strength, suggesting a relationship between late Cenozoic uplift of the southern Sierra Nevada and evolution of the southern Walker Lane.

The Honey Lake fault zone, northeastern California: Its nature, age, and displacement

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

Wagner, D.L.; Saucedo, G.J.; Grose, T.L.T.

The Honey Lake fault zone of northeastern California is composed of en echelon, northwest trending faults that form the boundary between the Sierra Nevada and the Basin Ranges provinces. As such the Honey Lake fault zone can be considered part of the Sierra Nevada frontal fault system. It is also part of the Walker Lane of Nevada. Faults of the Honey Lake zone are vertical with right-lateral oblique displacements. The cumulative vertical component of displacement along the fault zone is on the order of 800 m and right-lateral displacement is at least 10 km (6 miles) but could be considerablymore » more. Oligocene to Miocene (30 to 22 Ma) age rhyolite tuffs can be correlated across the zone, but mid-Miocene andesites do not appear to be correlative indicating the faulting began in early to mid-Miocene time. Volcanic rocks intruded along faults of the zone, dated at 16 to 8 Ma, further suggest that faulting in the Honey Lake zone was initiated during mid-Miocene time. Late Quaternary to Holocene activity is indicated by offset of the 12,000 year old Lake Lahontan high stand shoreline and the surface rupture associated with the 1950 Fort Sage earthquake.« less

3-Dimensional Geologic Modeling Applied to the Structural Characterization of Geothermal Systems: Astor Pass, Nevada, USA

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

Siler, Drew L; Faulds, James E; Mayhew, Brett

2013-04-16

Geothermal systems in the Great Basin, USA, are controlled by a variety of fault intersection and fault interaction areas. Understanding the specific geometry of the structures most conducive to broad-scale geothermal circulation is crucial to both the mitigation of the costs of geothermal exploration (especially drilling) and to the identification of geothermal systems that have no surface expression (blind systems). 3-dimensional geologic modeling is a tool that can elucidate the specific stratigraphic intervals and structural geometries that host geothermal reservoirs. Astor Pass, NV USA lies just beyond the northern extent of the dextral Pyramid Lake fault zone near the boundarymore » between two distinct structural domains, the Walker Lane and the Basin and Range, and exhibits characteristics of each setting. Both northwest-striking, left-stepping dextral faults of the Walker Lane and kinematically linked northerly striking normal faults associated with the Basin and Range are present. Previous studies at Astor Pass identified a blind geothermal system controlled by the intersection of west-northwest and north-northwest striking dextral-normal faults. Wells drilled into the southwestern quadrant of the fault intersection yielded 94°C fluids, with geothermometers suggesting a maximum reservoir temperature of 130°C. A 3-dimensional model was constructed based on detailed geologic maps and cross-sections, 2-dimensional seismic data, and petrologic analysis of the cuttings from three wells in order to further constrain the structural setting. The model reveals the specific geometry of the fault interaction area at a level of detail beyond what geologic maps and cross-sections can provide.« less

Investigating the Seismicity and Stress Field of the Truckee -- Lake Tahoe Region, California -- Nevada

NASA Astrophysics Data System (ADS)

Seaman, Tyler

The Lake Tahoe basin is located in a transtensional environment defined by east-dipping range--bounding normal faults, northeast--trending sinistral, and northwest-trending dextral strike-slip faults in the northern Walker Lane deformation belt. This region accommodates as much as 10 mm/yr of dextral shear between the Sierra Nevada and Basin and Range proper, or about 20% of Pacific-North American plate motion. There is abundant seismicity north of Lake Tahoe through the Truckee, California region as opposed to a lack of seismicity associated with the primary normal faults in the Tahoe basin (i.e., West Tahoe fault). This seismicity study is focused on the structural transition zone from north-striking east-dipping Sierran Range bounding normal faults into the northern Walker Lane right-lateral strike-slip domain. Relocations of earthquakes between 2000-2013 are performed by initially applying HYPOINVERSE mean sea level datum and station corrections to produce higher confidence absolute locations as input to HYPODD. HYPODD applies both phase and cross-correlation times for a final set of 'best' event relocations. Relocations of events in the upper brittle crust clearly align along well-imaged, often intersecting, high-angle structures of limited lateral extent. In addition, the local stress field is modeled from 679 manually determined short-period focal mechanism solutions, between 2000 and 2013, located within a fairly dense local seismic network. Short-period focal mechanisms were developed with the HASH algorithm and moment tensor solutions using long-period surface waves and the MTINV code. Resulting solutions show a 9:1 ratio of strike-slip to normal mechanisms in the transition zone study area. Stress inversions using the application SATSI (USGS Spatial And Temporal Stress Inversion) generally show a T-axis oriented primarily E-W that also rotates about 30 degrees counterclockwise, from a WNW-ESE trend to ENE-WSW, moving west to east across the California--Nevada border just north of Lake Tahoe. Focal mechanism and stress inversion results, based on the variance of the P-axis orientation, reveal a strike-slip dominated region directly north of Lake Tahoe that abruptly transitions northeastward to a transtentional regime along the Sierra front (i.e., in the hanging wall regime of the Sierran block). The majority of earthquakes used in the relocation and stress analysis occurs within a time period that includes unusual upper mantle/lower-crustal (˜30 km depth) dike injection events: 1) 2003 North Lake Tahoe and 2) 2011-2012 Sierra Valley, CA, that we interpret to be rift-related processes along the eastern Sierra Nevada microplate. Earthquake relocations for events shallower than about 18 km depth (the seismogenic depth determined in this study in the north Lake Tahoe area) cluster along high-angle fault structures, primarily in the footwall of the Sierra Nevada block. This new analysis isolates areas of distinctly strike-slip versus transtensional stress regimes, based on the variability of the P-axis plunge, that straddle the Sierra Nevada--Great Basin transition zone at the latitude of Lake Tahoe.

Mineral potential modelling of gold and silver mineralization in the Nevada Great Basin - a GIS-based analysis using weights of evidence

USGS Publications Warehouse

Mihalasky, Mark J.

2001-01-01

The distribution of 2,690 gold-silver-bearing occurrences in the Nevada Great Basin was examined in terms of spatial association with various geological phenomena. Analysis of these relationships, using GIS and weights of evidence modelling techniques, has predicted areas of high mineral potential where little or no mining activity exists. Mineral potential maps for sedimentary (?disseminated?) and volcanic (?epithermal?) rock-hosted gold-silver mineralization revealed two distinct patterns that highlight two sets of crustal-scale geologic features that likely control the regional distribution of these deposit types. The weights of evidence method is a probability-based technique for mapping mineral potential using the spatial distribution of known mineral occurrences. Mineral potential maps predicting the distribution of gold-silver-bearing occurrences were generated from structural, geochemical, geomagnetic, gravimetric, lithologic, and lithotectonic-related deposit-indicator factors. The maps successfully predicted nearly 70% of the total number of known occurrences, including ~83% of sedimentary and ~60% of volcanic rock-hosted types. Sedimentary and volcanic rockhosted mineral potential maps showed high spatial correlation (an area cross-tabulation agreement of 85% and 73%, respectively) with expert-delineated mineral permissive tracts. In blind tests, the sedimentary and volcanic rock-hosted mineral potential maps predicted 10 out of 12 and 5 out of 5 occurrences, respectively. The key mineral predictor factors, in order of importance, were determined to be: geology (including lithology, structure, and lithotectonic terrane), geochemistry (indication of alteration), and geophysics. Areas of elevated sedimentary rock-hosted mineral potential are generally confined to central, north-central, and north-eastern Nevada. These areas form a conspicuous ?V?-shape pattern that is coincident with the Battle Mountain-Eureka (Cortez) and Carlin mineral trends and a segment of the Roberts Mountain thrust front, which bridges the southern ends of the trends. This pattern appears to delineate two well-defined, sub-parallel, northwest?southeast-trending crustal-scale structural zones. These features, here termed the ?Carlin? and ?Cortez? structural zones, are believed to control the regional-scale distribution of the sedimentary rock-hosted occurrences. Mineralizing processes were focused along these structural zones and significant ore deposits exist where they intersect other tectonic zones, favorable host rock-types, and (or) where appropriate physio-chemical conditions were present. The origin and age of the Carlin and Cortez structural zones are not well constrained, however, they are considered to be transcurrent features representing a long-lived, deep-crustal or mantle-rooted zone of weakness. Areas of elevated volcanic rock-hosted mineral potential are principally distributed along two broad and diffuse belts that trend (1) northwest-southeast across southwestern Nevada, parallel to the Sierra Nevada, and (2) northeast-southwest across northern Nevada, extending diagonally from the Sierra Nevada to southern Idaho. The first belt corresponds to the Walker Lane shear zone, a wide region of complex strike-slip faulting. The second, here termed the ?Humboldt shear(?) zone?, may represent a structural zone of transcurrent movement. Together, the Walker Lane and Humboldt shear(?) zones are believed to control the regional-scale distribution of volcanic rock-hosted occurrences. Volcanic rock-hosted mineralization was closely tied to the southward and westward migration of Tertiary magmatism across the region (which may have been mantle plume-driven). Both magmatic and mineralizing processes were localized and concentrated along these structural zones. The Humboldt shear(?) zone may have also affected the distribution of sedimentary rock-hosted mineralization along the Battle Mountain?Eureka (C

Identifying block structure in the Pacific Northwest, USA

USGS Publications Warehouse

Savage, James C.; Wells, Ray E.

2015-01-01

We have identified block structure in the Pacific Northwest (west of 116°W between 38°N and 49°N) by clustering GPS stations so that the same Euler vector approximates the velocity of each station in a cluster. Given the total number k of clusters desired, the clustering procedure finds the best assignment of stations to clusters. Clustering is calculated for k= 2 to 14. In geographic space, cluster boundaries that remain relatively stable as k is increased are tentatively identified as block boundaries. That identification is reinforced if the cluster boundary coincides with a geologic feature. Boundaries identified in northern California and Nevada are the Central Nevada Seismic Belt, the west side of the Northern Walker Lane Belt, and the Bartlett Springs Fault. Three blocks cover all of Oregon and Washington. The principal block boundary there extends west-northwest along the Brothers Fault Zone, then north and northwest along the eastern boundary of Siletzia, the accreted oceanic basement of the forearc. East of this boundary is the Intermountain block, its eastern boundary undefined. A cluster boundary at Cape Blanco subdivides the forearc along the faulted southern margin of Siletzia. South of Cape Blanco the Klamath Mountains-Basin and Range block extends east to the Central Nevada Seismic Belt and south to the Sierra Nevada-Great Valley block. The Siletzia block north of Cape Blanco coincides almost exactly with the accreted Siletz terrane. The cluster boundary in the eastern Olympic Peninsula may mark permanent shortening of Siletzia against the Intermountain block.

Hydrologic data for the Walker River Basin, Nevada and California, water years 2010–14

USGS Publications Warehouse

Pavelko, Michael T.; Orozco, Erin L.

2015-12-10

Walker Lake is a threatened and federally protected desert terminal lake in western Nevada. To help protect the desert terminal lake and the surrounding watershed, the Bureau of Reclamation and U.S. Geological Survey have been studying the hydrology of the Walker River Basin in Nevada and California since 2004. Hydrologic data collected for this study during water years 2010 through 2014 included groundwater levels, surface-water discharge, water chemistry, and meteorological data. Groundwater levels were measured in wells, and surface-water discharge was measured in streams, canals, and ditches. Water samples for chemical analyses were collected from wells, streams, springs, and Walker Lake. Chemical analyses included determining physical properties; the concentrations of major ions, nutrients, trace metals, dissolved gases, and radionuclides; and ratios of the stable isotopes of hydrogen and oxygen. Walker Lake water properties and meteorological parameters were monitored from a floating platform on the lake. Data collection methods followed established U.S. Geological Survey guidelines, and all data are stored in the National Water Information System database. All of the data are presented in this report and accessible on the internet, except multiple-depth Walker Lake water-chemistry data, which are available only in this report.

Silver Peak Innovative Exploration Project (Ram Power Inc.)

DOE Data Explorer

Miller, Clay

2010-01-01

Data generated from the Silver Peak Innovative Exploration Project, in Esmeralda County, Nevada, encompasses a “deep-circulation (amagmatic)” meteoric-geothermal system circulating beneath basin-fill sediments locally blanketed with travertine in western Clayton Valley (lithium-rich brines from which have been mined for several decades). Spring- and shallow-borehole thermal-water geochemistry and geothermometry suggest that a Silver Peak geothermal reservoir is very likely to attain the temperature range 260- 300oF (~125-150oC), and may reach 300-340oF (~150-170oC) or higher (GeothermEx, Inc., 2006). Results of detailed geologic mapping, structural analysis, and conceptual modeling of the prospect (1) support the GeothermEx (op. cit.) assertion that the Silver Peak prospect has good potential for geothermal-power production; and (2) provide a theoretical geologic framework for further exploration and development of the resource. The Silver Peak prospect is situated in the transtensional (regional shearing coupled with extension) Walker Lane structural belt, and squarely within the late Miocene to Pliocene (11 Ma to ~5 Ma) Silver Peak-Lone Mountain metamorphic core complex (SPCC), a feature that accommodated initial displacement transfer between major right-lateral strike- slip fault zones on opposite sides of the Walker Lane. The SPCC consists essentially of a ductiley-deformed lower plate, or “core,” of Proterozoic metamorphic tectonites and tectonized Mesozoic granitoids separated by a regionally extensive, low-angle detachment fault from an upper plate of severely stretched and fractured structural slices of brittle, Proterozoic to Miocene-age lithologies. From a geothermal perspective, the detachment fault itself and some of the upper-plate structural sheets could function as important, if secondary, subhorizontal thermal-fluid aquifers in a Silver Peak hydrothermal system.

Quaternary extensional growth folding beneath Reno, Nevada, imaged by urban seismic profiling

USGS Publications Warehouse

Stephenson, William J.; Frary, Roxy N.; Louie, John; Odum, Jackson K.

2013-01-01

We characterize shallow subsurface faulting and basin structure along a transect through heavily urbanized Reno, Nevada, with high‐resolution seismic reflection imaging. The 6.8 km of P‐wave data image the subsurface to approximately 800 m depth and delineate two subbasins and basin uplift that are consistent with structure previously inferred from gravity modeling in this region of the northern Walker Lane. We interpret two primary faults that bound the uplift and deform Quaternary deposits. The dip of Quaternary and Tertiary strata in the western subbasin increases with greater depth to the east, suggesting recurrent fault motion across the westernmost of these faults. Deformation in the Quaternary section of the western subbasin is likely evidence of extensional growth folding at the edge of the Truckee River through Reno. This deformation is north of, and on trend with, previously mapped Quaternary fault strands of the Mt. Rose fault zone. In addition to corroborating the existence of previously inferred intrabasin structure, these data provide evidence for an active extensional Quaternary fault at a previously unknown location within the Truckee Meadows basin that furthers our understanding of both the seismotectonic framework and earthquake hazards in this urbanized region.

High-Precision Locations and the Stress Field from Instrumental Seismicity, Moment Tensors, and Short-Period Mechanisms through the Mina Deflection, Central Walker Lane

NASA Astrophysics Data System (ADS)

Ruhl, C. J.; Smith, K. D.

2012-12-01

The Mina Deflection (MD) region of the central Walker Lane of eastern California and western Nevada, is a complex zone of northeast-trending normal, and primarily left-lateral strike-slip to oblique-slip faulting that separates the Southern Walker Lane (SWL) from a series of east-tilted normal fault blocks in the Central Walker Lane (CWL) (Faulds and Henry, 2008; Surpless, 2008). The MD accommodates the transfer of right-lateral strike-slip motion from northwest-striking faults in the SWL to a series of left-stepping northwest-striking right-lateral strike-slip faults in the CWL, east of the Wassuk Range near Hawthorne, NV. The ~50 km wide ~80 km long right-step is a distinct transition in regional physiography that has been attributed to strain accommodation through pre-Cenozoic lithospheric structures. Several slip transfer mechanisms have been proposed within the MD, from clockwise rotation of high-angle fault blocks (Wesnousky, 2005), to low-angle displacement within the Silver Peak-Lone Mountain complex (Oldow et al., 2001), and curved fault arrays associated with localized basins and tectonic depressions (Ferranti et al., 2009). The region has been a regular source of M4+ events, the most recent being an extended sequence that included twenty-seven M 3.5+ earthquakes (largest event M 4.6) south of Hawthorne in 2011. These earthquakes (< 5 km depth) define shallow W-dipping (dip ~56°) and NW-dipping (dip ~70°) normal faulting constrained by moment tensor (MT) solutions and earthquake relocations. Temporary stations deployed in the source area provide good control. A distributed sequence in 2004, between Queen Valley and Mono Lake, primarily associated with the Huntoon Valley fault, included three M 5+ left-lateral strike-slip faulting events. A 1997 sequence in northern Fish Lake Valley (east of the White Mountains), with mainshock Mw 5.3 (Ichinose et al., 2003), also showed high-angle northeast-striking left-lateral strike-slip motion. Historical events include the 1934 M 6.5 Excelsior Mountains event south of Mina, NV, and the 1932 M 7.1 Cedar Mountains earthquake east of the Pilot Mountains. Another persistent feature in the seismicity is an ~40 km long arcuate distribution of activity extending from approximately Queen Valley, north of the White Mountains, to Mono Lake that appears to reflect a southwestern boundary to northeast-striking structures in the MD. Here we develop high-precision relocations of instrumental seismicity in the MD from 1984 through 2012, including relocations of the 2004 sequence, and account for the historical seismic record. MT solutions from published reports and computed from recent M 3.5+ earthquakes as well as available and developed short-period focal mechanisms are compiled to evaluate the stress field to assess mechanisms of slip accommodation. Based on the complex distribution of fault orientations, the stress field varies locally northward from the SWL throughout the MD; however, in many cases, fault plane alignments can be isolated from high-precision locations, providing better constraints on stress and slip orientations.

Geologic application of thermal inertia imaging using HCMM data. [Walker Lane, Nevada; San Rafael, Utah; and Death Valley and Pisgah Crater, Lavic Lake Region, California

NASA Technical Reports Server (NTRS)

Kahle, A. B.; Schieldge, J. P.; Abrams, M. J.; Alley, R. E.; Levine, C. J. (Principal Investigator)

1981-01-01

Three test sites in the western US were selected to discriminate among surface geologic materials on the basis of their thermal properties as determined from HCMM data. Attempts to determine quantitatively accurate thermal inertia values from HCMM digital data met with only partial success due to the effects of sensor miscalibrations, radiative transfer in the atmosphere, and varying meteorology and elevation across a scene. In most instances, apparent thermal inertia was found to be an excellent qualitative representation of true thermal inertia. Computer processing of digital day and night HCMM data allowed construction of geologically useful images. At some test sites, more information was provided by data than LANDSAT data. Soil moisture effects and differences in spectrally dark materials were more effectively displayed using the thermal data.

Simulation of the Lower Walker River Basin hydrologic system, west-central Nevada, using PRMS and MODFLOW models

USGS Publications Warehouse

Allander, Kip K.; Niswonger, Richard G.; Jeton, Anne E.

2014-01-01

The effects of fallowing of Walker River Indian Irrigation Project fields from 2007 to 2010 on Walker Lake inflow, level, and dissolved solids were evaluated. Fallowing resulted in a near doubling of Walker River inflow to Walker Lake during this period, an increase in Walker Lake level of about 1.4 feet, and a decrease in dissolved-solids concentration of about 540 mg/L.

Translation vs. Rotation: The Battle for Accommodation of Dextral Shear at the Northern Terminus of the Central Walker Lane, Western Nevada

NASA Astrophysics Data System (ADS)

Carlson, C. W.; Faulds, J. E.

2014-12-01

Positioned between the Sierra Nevada microplate and Basin and Range in western North America, the Walker Lane (WL) accommodates ~20% of the dextral motion between the North American and Pacific plates on predominately NW-striking dextral and ENE to E-W-striking sinistral fault systems. The Terrill Mountains (TM) lie at the northern terminus of a domain of dextral faults accommodating translation of crustal-blocks in the central WL and at the southeast edge of sinistral faults accommodating oroclinal flexure and CW rotation of blocks in the northern WL. As the mechanisms of strain transfer between these disparate fault systems are poorly understood, the thick Oligocene to Pliocene volcanic strata of the TM area make it an ideal site for studying the transfer of strain between regions undergoing differing styles of deformation and yet both accommodating dextral shear. Detailed geologic mapping and paleomagnetic study of ash-flow tuffs in the TM region has been conducted to elucidate Neogene strain accommodation for this transitional region of the WL. Strain at the northernmost TM appears to be transferred from a system of NW-striking dextral faults to a system of ~E-W striking sinistral faults with associated CW flexure. A distinct ~23 Ma paleosol is locally preserved below the tuff of Toiyabe and provides an important marker bed. This paleosol is offset with ~6 km of dextral separation across the fault bounding the NE flank of the TM. This fault is inferred as the northernmost strand of the NW-striking, dextral Benton Spring fault system, with offset consistent with minimums constrained to the south (6.4-9.6 km, Gabbs Valley Range). Paleomagnetic results suggest counter-intuitive CCW vertical-axis rotation of crustal blocks south of the domain boundary in the system of NW-striking dextral faults, similar to some other domains of NW-striking dextral faults in the northern WL. This may result from coeval dextral shear and WNW-directed extension within the left-stepping system of dextral fault. The left steps are analogous to Riedel shears developing above a more through-going shear zone at depth. However, a site directly adjacent to the Benton Springs fault is rotated ~30° CW, likely due to fault drag. These results show the complex and important contribution of vertical-axis rotations in accommodation of dextral shear.

Magmatism, ash-flow tuffs, and calderas of the ignimbrite flareup in the western Nevada volcanic field, Great Basin, USA

USGS Publications Warehouse

Christopher D. Henry,; John, David A.

2013-01-01

The western Nevada volcanic field is the western third of a belt of calderas through Nevada and western Utah. Twenty-three calderas and their caldera-forming tuffs are reasonably well identified in the western Nevada volcanic field, and the presence of at least another 14 areally extensive, apparently voluminous ash-flow tuffs whose sources are unknown suggests a similar number of undiscovered calderas. Eruption and caldera collapse occurred between at least 34.4 and 23.3 Ma and clustered into five ∼0.5–2.7-Ma-long episodes separated by quiescent periods of ∼1.4 Ma. One eruption and caldera collapse occurred at 19.5 Ma. Intermediate to silicic lavas or shallow intrusions commonly preceded caldera-forming eruptions by 1–6 Ma in any specific area. Caldera-related as well as other magmatism migrated from northeast Nevada to the southwest through time, probably resulting from rollback of the formerly shallow-dipping Farallon slab. Calderas are restricted to the area northeast of what was to become the Walker Lane, although intermediate and effusive magmatism continued to migrate to the southwest across the future Walker Lane.Most ash-flow tuffs in the western Nevada volcanic field are rhyolites, with approximately equal numbers of sparsely porphyritic (≤15% phenocrysts) and abundantly porphyritic (∼20–50% phenocrysts) tuffs. Both sparsely and abundantly porphyritic rhyolites commonly show compositional or petrographic evidence of zoning to trachydacites or dacites. At least four tuffs have volumes greater than 1000 km3, with one possibly as much as ∼3000 km3. However, the volumes of most tuffs are difficult to estimate, because many tuffs primarily filled their source calderas and/or flowed and were deposited in paleovalleys, and thus are irregularly distributed.Channelization and westward flow of most tuffs in paleovalleys allowed them to travel great distances, many as much as ∼250 km (original distance) to what is now the western foothills of the Sierra Nevada, which was not a barrier to westward flow of ash flows at that time. At least three tuffs flowed eastward across a north-south paleodivide through central Nevada. That tuffs could flow significant distances apparently uphill raises questions about the absolute elevation of the region and the elevation, relief, and location of the paleodivide.Calderas are equant to slightly elongate, at least 12 km in diameter, and as much as 35 km in longest dimension. Exceptional exposure of two caldera complexes that resulted from extensional faulting and tilting show that calderas subsided as much as 5 km as large piston-like blocks; caldera walls were vertical to steeply inward dipping to depths ≥4–5 km, and topographic walls formed by slumping of wall rock into the caldera were only slightly outboard (≤1 km) of structural margins.Most calderas show abundant post-collapse magmatism expressed as resurgent intrusions, ring-fracture intrusions, or intracaldera lavas that are closely related temporally (∼0–0.5 Ma younger) to caldera formation. Granitoid intrusions, which were emplaced at paleodepths ranging from <1 to ∼7 km, are compositionally similar to both intracaldera ash-flow tuffs and post-caldera lavas. Therefore in the western Nevada volcanic field, erupted caldera-forming tuffs commonly were the upper parts of large magma chambers that retained considerable volumes of magma after tuff eruption.Several calderas in the western Nevada volcanic field hosted large hydrothermal systems and underwent extensive hydrothermal alteration. Different types of hydrothermal systems (neutral-pH alkali-chloride and acid or low-pH magmatic-hydrothermal) may reflect proximity to (depth of) large resurgent intrusions. With the exception of the giant Round Mountain epithermal gold deposit, few known caldera-related hydrothermal systems are strongly mineralized. Major middle Cenozoic precious and base metal mineral deposits in and along the margins of the western Nevada volcanic field are mostly related to intrusive rocks that preceded caldera-forming eruptions.

Age, geochemical composition, and distribution of Oligocene ignimbrites in the northern Sierra Nevada, California: Implications for landscape morphology, elevation, and drainage divide geography of the Nevadaplano

USGS Publications Warehouse

Cassel, Elizabeth J.; Calvert, Andrew T.; Graham, Stephan A.

2009-01-01

To gain a better understanding of the topographic and landscape evolution of the Cenozoic Sierra Nevada and Basin and Range, we combine geochemical and isotopic age correlations with palaeoaltimetry data from widely distributed ignimbrites in the northern Sierra Nevada, California. A sequence of Oligocene rhyolitic ignimbrites is preserved across the modern crest of the range and into the western foothills. Using trace and rare earth element geochemical analyses of volcanic glass, these deposits have been correlated to ignimbrites described and isotopically dated in the Walker Lane fault zone and in central Nevada (Henry et al., 2004, Geologic map of the Dogskin mountain quadrangle; Washoe County, Nevada; Faulds et al., 2005, Geology, v. 33, p. 505–508). Ignimbrite deposits were sampled within the northern Sierra Nevada and western Nevada, and four distinct geochemical compositions were identified. The majority of samples from within the northern Sierra Nevada have compositions similar to the tuffs of Axehandle Canyon or Rattlesnake Canyon, both likely sourced from the same caldera complex in either the Clan Alpine Mountains or the Stillwater Range, or to the tuff of Campbell Creek, sourced from the Desatoya Mountains caldera. New 40Ar/39Ar age determinations from these samples of 31.2, 30.9, and 28.7 Ma, respectively, support these correlations. Based on an Oligocene palinspastic reconstruction of the region, our results show that ignimbrites travelled over 200 km from their source calderas across what is now the crest of the Sierra Nevada, and that during that time, no drainage divide existed between the ignimbrite source calderas in central Nevada and sample locations 200 km to the west. Palaeoaltimetry data from Sierra Nevada ignimbrites, based on the hydrogen isotopic composition of hydration water in glass, reflect the effect of a steep western slope on precipitation and indicate that the area had elevations similar to the present-day range. These combined results suggest that source calderas were likely located in a region of high elevation to the east of the Oligocene Sierra Nevada, which had a steep western slope that allowed for the large extent and broad distribution of the ignimbrites.

Lithology, Geochemistry and Paleomagnetism of the Table Mountain Formation at the Little Walker Caldera

NASA Astrophysics Data System (ADS)

Schubert, R.; Pluhar, C. J.; Carlson, C. W.; Jones, S. A.

2015-12-01

West of Bridgeport Valley near the Central Sierra Nevada crest, the Little Walker Caldera (LWC) erupted Stanislaus Group lavas and tuffs during the Late Miocene. Remnants of these rocks are now distributed from the western Sierra Nevada foothills across the range and into the Walker Lane. This wide distribution is attributed to the lavas flowing down paleochannels, which provide an excellent marker for deformation over the last 10 Ma. Priest (1978) identified a thick section of these lavas along Flatiron Ridge, the southeast margin of the LWC, which our preliminary data suggests may correlate with lavas in the Sweetwater Mountains to the northeast and at Rancheria Mtn near Hetch Hetchy to the southwest. The oldest unit in the Stanislaus group is the Table Mountain Formation, a trachyandesite. At Priest's measured section it is divided into three members. By our measurements, the Lower Member (Tmtl) is 256 meters thick, has a fine-grained groundmass with plagioclase and augite phenocrysts (<0.5 cm), and the presence of augite phenocrysts distinguishes it from the other members. Some Tmtl flows have chalcedony amigdules. Overlying this, the Large Plagioclase member (Tmtp) is 43.5 meters thick. Distinguished by (~1 cm) plagioclase and occasional small olivine phenocrysts. The Upper Member (Tmtu) is 116 meters thick, very fine-grained and often platy. Tmtl has a distinctive northwest-oriented normal polarity and geochemistry, similar to several localities at Rancheria Mtn. Tmtu has a reversed polarity similar to the polarity of Table Mountain Formation in the Sweetwater Mountains and lavas that directly underlie the ~9.5 Ma Tollhouse Flat member of the Eureka Valley Tuff at Rancheria Mtn. Thus, our preliminary data suggest that the lower member at Priest's Measured Section could correlate to the normal polarity samples at Rancheria Mtn. Also, that the upper Member reversed-polarity samples may correlate with lavas both at the Sweetwater Mountains and Rancheria Mtn. This correlation across about 60 km allows us to assess rotation between sites as well as estimate throw across some faults of the Eastern Sierra range front.

The Conterminous United States Mineral Appraisal Program; background information to accompany folio of geologic, geochemical, geophysical, and mineral resources maps of the Walker Lake 1 degree x 2 degrees Quadrangle, California and Nevada

USGS Publications Warehouse

Stewart, John Harris; Chaffee, M.A.; Dohrenwend, J.C.; John, D.A.; Kistler, R.W.; Kleinhampl, F.J.; Menzie, W.D.; Plouff, Donald; Rowan, L.C.; Silberling, Norman J.

1984-01-01

The Walker Lake 1? by 2? quadrangle in eastern California and western Nevada was studied by an interdisciplinary research team to appraise its mineral resources. The appraisal is based on geological, geochemical, and geophysical field and laboratory investigations, the results of which are published as a folio of maps, figures, and tables, with accompanying discussions. This circular provides background information on the investigations and integrates the information presented in the folio. The selected bibliography lists selected references to the geology, geochemistry, geophysics, and mineral deposits of the Walker Lake 1? by 2? quadrangle.

Modern lacustrine stromatolites, Walker Lake, Nevada

NASA Astrophysics Data System (ADS)

Osborne, Robert H.; Licari, Gerald R.; Link, Martin H.

1982-05-01

The Walker River drainage basin occupies about 10,000 km 2 in western Nevada and parts of California and is essentially a closed hydrologic system which drains from the crest of the Sierra Nevada in California and terminates in Walker Lake, Nevada. Walker Lake trends north and is about 27.4 km long and 8 km wide with water depths exceeding 30.5 m. The lake is situated in an asymmetric basin with steep alluvial fans flanking the western shoreline (Wassuk Range) and more gentle but areally more extensive alluvial fans flanking the eastern shoreline (Gillis Range). Exposed lake terraces and the present shoreline of Walker Lake record a sequence of Pleistocene and Holocene stromatolitic and tufaceous carbonate deposits. Small generalized and columnar stromatolites, frequently encrusted on exposed coarse-grained clasts or bedrock, are present along parts of the nearshore margin of Walker Lake and at elevated lake stands. Columnar stromatolites as much as 4 cm high are subcylindrical to club shaped discrete, and laterally linked at the base with local branching. These digitate stromatolites start as wavy, generalized stromatolites which are vertically transitional to small, laterally linked cabbage heads with laminae which thicken over the crests. Although algal structures are not well preserved in the older stromatolites, recent precipitation of low magnesium calcite occurs as smooth encrustations and as tiny mounds which are consistently associated with a diverse, seasonally variable, green and blue-green algal community including Cladophora glomerata, Ulothrix (cf. aequalis), Gongrosira, Schizothrix, Amphithrix janthina, Calothrix, Homeothrix, Spirulina, Anabaena, Lyngbya, and Entophysalis. Cladophora glomerata and a species of Ulothrix, which are the two most abundant algae within the Walker Lake stromatolite community, are known to condition semi-alkaline lake water by the removal of CO 2 from bicarbonate during photosynthesis. Such conditioning results in the precipitation of calcium carbonate, which is trapped and bound by an understory of green and blue-green algae. The occurrence of stromatolites in highly siliciclastic lakes seems to be restricted to shoreline and nearshore environments, and can be used to locate ancient lake margins.

Alum Innovative Exploration Project (Ram Power Inc.)

DOE Data Explorer

Miller, Clay

2010-01-01

Data generated from the Alum Innovative Exploration Project, one of several promising geothermal properties located in the middle to upper Miocene (~11-5 Ma, or million years BP) Silver Peak-Lone Mountain metamorphic core complex (SPCC) of the Walker Lane structural belt in Esmeralda County, west-central Nevada. The geothermal system at Alum is wholly concealed; its upper reaches discovered in the late 1970s during a regional thermal-gradient drilling campaign. The prospect boasts several shallow thermal-gradient (TG) boreholes with TG >75oC/km (and as high as 440oC/km) over 200-m intervals in the depth range 0-600 m. Possibly boiling water encountered at 239 m depth in one of these boreholes returned chemical- geothermometry values in the range 150-230oC. GeothermEx (2008) has estimated the electrical- generation capacity of the current Alum leasehold at 33 megawatts for 20 years; and the corresponding value for the broader thermal anomaly extending beyond the property at 73 megawatts for the same duration.

Interpretive geologic cross sections for the Death Valley regional flow system and surrounding areas, Nevada and California

USGS Publications Warehouse

Sweetkind, D.S.; Dickerson, R.P.; Blakely, R.J.; Denning, Paul

2001-01-01

This report presents a network of 28 geologic cross sections that portray subsurface geologic relations within the Death Valley regional ground-water system, a ground-water basin that encompasses a 3? x 3? area (approximately 70,000 km2) in southern Nevada and eastern California. The cross sections transect that part of the southern Great Basin that includes Death Valley, the Nevada Test Site, and the potential high-level nuclear waste underground repository at Yucca Mountain. The specific geometric relationships portrayed on the cross sections are discussed in the context of four general sub-regions that have stratigraphic similarities and general consistency of structural style: (1) the Nevada Test Site vicinity; (2) the Spring Mountains, Pahrump Valley and Amargosa Desert region; (3) the Death Valley region; and (4) the area east of the Nevada Test Site. The subsurface geologic interpretations portrayed on the cross sections are based on an integration of existing geologic maps, measured stratigraphic sections, published cross sections, well data, and geophysical data and interpretations. The estimated top of pre-Cenozoic rocks in the cross sections is based on inversion of gravity data, but the deeper parts of the sections are based on geologic conceptual models and are more speculative. The region transected by the cross sections includes part of the southern Basin and Range Province, the northwest-trending Walker Lane belt, the Death Valley region, and the northern Mojave Desert. The region is structurally complex, where a locally thick Tertiary volcanic and sedimentary section unconformably overlies previously deformed Proterozoic through Paleozoic rocks. All of these rocks have been deformed by complex Neogene ex-tensional normal and strike-slip faults. These cross sections form a three-dimensional network that portrays the interpreted stratigraphic and structural relations in the region; the sections form part of the geologic framework that will be incorporated in a complex numerical model of ground-water flow in the Death Valley region.

Correlations and Areal Distribution of the Table Mountain Formation, Stanislaus Group; Central Sierra Nevada, California

NASA Astrophysics Data System (ADS)

Torrez, G.; Carlson, C. W.; Putirka, K. D.; Pluhar, C. J.; Sharma, R. K.

2011-12-01

Late Cenozoic evolution of the western Cordillera is a matter of ongoing debate in geologic studies. Volcanic deposits within, and adjacent to the Sierra Nevada have played a significant role in many of these debates. With local faulting coincident with eruption of members of the Stanislaus Group at ca. 38°N, the composition and correlation of these volcanics can greatly aid our understanding of Sierra Nevada tectonics. At the crest of the central Sierra Nevada, 23 trachyandesite lava flows of the Table Mountain Formation, dated at ~10 Ma, cap Sonora Peak. These 23 flows compose the thickest and most complete known stratigraphic section of the Table Mountain Formation in the region. Located ~12 km east of Sonora Peak are 16 flows of trachyandesite at Grouse Meadow. We have collected a detailed set of geochemical and paleomagnetic data for flows of these two sections at Sonora Peak and Grouse Meadows in an attempt to correlate volcanic, paleomagnetic and structural events related to uplift and extension in the Sierra Nevada and the Walker Lane. Correlation of individual flows is possible based on: stratigraphic order, temporal gaps in deposition as determined by paleomagnetic remanence direction and nonconformities, and flow geochemistry. These correlations allow us to infer source localities, flow directions, and temporal changes in flow routes. The large number of flows present at Grouse Meadow provides an additional data set from which to correlate various localities in the region to those units not represented at Sonora Peak. Several flows which occur in the upper portions of the Sonora Peak and Grouse Meadow stratigraphic sections do not correlate between these localities. The causes of stratigraphic discontinuity potentially represent: tectonic isolation across the Sierran Crest, topographic isolation by the emplacement of younger flows, or the combination of the two. Additional to the correlation of individual flows at these localities, this study shows a significant shift in geochemistry across a stratigraphic boundary at both localities.

Digital geologic map of the Nevada Test Site and vicinity, Nye, Lincoln, and Clark Counties, Nevada, and Inyo County, California

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

Slate, J.L.; Berry, M.E.; Rowley, P.D.

2000-03-08

This digital geologic map of the Nevada Test Site (NTS) and vicinity, as well as its accompanying digital geophysical maps, are compiled at 1:100,000 scale. The map area covers two 30 {times} 60-minute quadrangles-the Pahute Mesa quadrangle to the north and the Beatty quadrangle to the south-plus a strip of 7 1/2-minute quadrangles on the east side. In addition to the NTS, the map area includes the rest of the southwest Nevada volcanic field, part of the Walker Lane, most of the Amargosa Desert, part of the Funeral and Grapevine Mountains, some of Death Valley, and the northern Spring Mountains.more » This geologic map improves on previous geologic mapping of the same area by providing new and updated Quaternary and bedrock geology, new geophysical interpretations of faults beneath the basins, and improved GIS coverages. This publication also includes a new isostatic gravity map and a new aeromagnetic map. The primary purpose of the three maps is to provide an updated geologic framework to aid interpretation of ground-water flow through and off the NTS. The NTS is centrally located within the area of the Death Valley regional ground-water flow system of southwestern Nevada and adjacent California. During the last 40 years, DOE and its predecessor agencies have conducted about 900 nuclear tests on the NTS, of which 100 were atmospheric tests and the rest were underground tests. More than 200 of the tests were detonated at or beneath the water table, which commonly is about 500 to 600 m below the surface. Because contaminants introduced by these test may move into water supplies off the NTS, rates and directions of ground-water flow must be determined. Knowledge about the ground water also is needed to properly appraise potential future effects of the possible nuclear waste repository at Yucca Mountain, adjacent to the NTS.« less

Late Holocene lake-level fluctuations in Walker Lake, Nevada, USA

USGS Publications Warehouse

Yuan, F.; Linsley, B.K.; Howe, S.S.; Lund, S.P.; McGeehin, J.P.

2006-01-01

Walker Lake, a hydrologically closed, saline, and alkaline lake, is situated along the western margin of the Great Basin in Nevada of the western United States. Analyses of the magnetic susceptibility (??), total inorganic carbon (TIC), and oxygen isotopic composition (??18O) of carbonate sediments including ostracode shells (Limnocythere ceriotuberosa) from Walker Lake allow us to extend the sediment record of lake-level fluctuations back to 2700??years B.P. There are approximately five major stages over the course of the late Holocene hydrologic evolution in Walker Lake: an early lowstand (> 2400??years B.P.), a lake-filling period (??? 2400 to ??? 1000??years B.P.), a lake-level lowering period during the Medieval Warm Period (MWP) (??? 1000 to ??? 600??years B.P.), a relatively wet period (??? 600 to ??? 100??years B.P.), and the anthropogenically induced lake-level lowering period (< 100??years B.P.). The most pronounced lowstand of Walker Lake occurred at ??? 2400??years B.P., as indicated by the relatively high values of ??18O. This is generally in agreement with the previous lower resolution paleoclimate results from Walker Lake, but contrasts with the sediment records from adjacent Pyramid Lake and Siesta Lake. The pronounced lowstand suggests that the Walker River that fills Walker Lake may have partially diverted into the Carson Sink through the Adrian paleochannel between 2700 to 1400??years B.P. ?? 2006 Elsevier B.V. All rights reserved.

Post-middle Miocene Tuffs of Bodie Hills and Mono Basin, California: Paleomagnetic Reference Directions and Vertical Axis Rotation

NASA Astrophysics Data System (ADS)

Lindeman, J. R.; Pluhar, C. J.; Farner, M. J.

2013-12-01

The relative motions of the Pacific and North American plates about the Sierra Nevada-North American Euler pole is accommodated by dextral slip along the San Andreas Fault System (~75%) and the Walker Lane-Eastern California Shear Zone system of faults, east of the Sierra Nevada microplate (~25%). The Bodie Hills and Mono Basin regions lie within the Walker Lane and partially accommodate deformation by vertical axis rotation of up to 60o rotation since ~9.4 Ma. This region experienced recurrent eruptive events from mid to late Miocene, including John et al.'s (2012) ~12.05 Ma Tuff of Jack Springs (TJS) and Gilbert's (1968) 11.1 - 11.9 Ma 'latite ignimbrite' east of Mono Lake. Both tuffs can be identified by phenocrysts of sanidine and biotite in hand specimens, with TJS composed of a light-grey matrix and the latite ignimbrite composed of a grey-black matrix. Our paleomagnetic results show these units to both be normal polarity, with the latite ignimbrite exhibiting a shallow inclination. TJS's normal polarity is consistent with emplacement during subchron C5 An. 1n (12.014 - 12.116 Ma). The X-ray fluorescence analyses of fiamme from TJS in Bodie Hills and the latite ignimbrite located east of Mono Lake reveal them both to be rhyolites with the latite ignimbrite sharing elevated K composition seen in the slightly younger Stanislaus Group (9.0 - 10.2 Ma). We establish a paleomagnetic reference direction of D = 352.8o I = 42.7o α95 = 7.7o n = 5 sites (42 samples) for TJS in the Bodie Hills in a region hypothesized by Carlson (2012) to have experienced low rotation. Our reference for Gilbert's latite ignimbrite (at Cowtrack Mountain) is D = 352.9o I = 32.1o α95 = 4.7o. This reference locality is found on basement highland likely to have experienced less deformation then the nearby Mono Basin since ignimbrite emplacement. Paleomagnetic results from this latite ignimbrite suggests ~98.2o × 5.5o of clockwise vertical axis rotation of parts of eastern Mono Basin since unit emplacement. A welded 11.7 Ma (K-Ar; Drake, 1979) rhyolitic tuff near Trafton Mountain appears similar in composition to TJS. Drake's tuff exhibits a reversed polarity, consistent with reversed polarity subchron C5r.3r (11.614 - 12.014 Ma) and distinguishes this tuff from TJS and Gilbert's latite ignimbrite.

New constraints on slip-rates, recurrence intervals, and strain partitioning beneath Pyramid Lake, Nevada

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

Eisses, Amy

A high-resolution CHIRP seismic survey of Pyramid Lake, Nevada, located within the northern Walker Lane Deformation Belt, was conducted in summer 2010. Seismic CHIRP data with submeter vertical accuracy, together with piston and gravity cores, were used to calculate Holocene vertical slip rates, relative earthquake timing, and produce the first complete fault map beneath the lake. More than 500 line-kilometers of CHIRP data imaged complex fault patterns throughout the basin. Fault architecture beneath Pyramid Lake highlights a polarity flip, where down-to-the west patterns of sedimentation near the dextral Pyramid Lake fault to the south give way to down-to-the-east geometries tomore » the north within a mostly normal (i.e., Lake Range fault) and transtensional environment. The Lake Range fault predominantly controls extensional deformation within the northern two-thirds of the basin and exhibits varying degrees of asymmetric tilting and divergence due to along-strike segmentation. This observation is likely a combination of fault segments splaying onshore moving the focus of extension away from the lake coupled with some true along-strike differences in slip-rate. The combination of normal and oblique-slip faults in the northern basin gives Pyramid Lake its distinctive “fanning open to the north” tectonic geometry. The dense network of oblique-slip faults in the northwestern region of the lake, in contrast to the well-defined Lake Range fault, are short and discontinuous in nature, and possible represent a nascent shear zone. Preliminary vertical slip-rates measured across the Lake Range and other faults provide new estimates on the extension across the Pyramid Lake basin. A minimum vertical slip rate of ~1.0 mm/yr is estimated along the Lake Range fault, which yields a potential earthquake magnitude range between M6.4 and M7.0. A rapid influx of sediment was deposited shortly after the end of the Tioga glaciation somewhere between 12.5 ka to 9.5 ka and provides a punctuated short-term record of little to no slip on the Lake Range fault. In contrast, for the past 9,500 years, the basin has experienced a decrease in sedimentation rate, but an escalation in earthquake activity on the Lake Range fault, with the potential of 3 or 4 major earthquakes assuming a characteristic offset of 2.5 m per event. Regionally, our CHIRP investigation helps to reveal how strain is partitioned along the boundary between the eastern edge of the Walker Lane Deformation Belt and the northwest Great Basin proper.« less

Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada

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

Eisses, A.; Kell, A.; Kent, G.

Amy Eisses, Annie Kell, Graham Kent, Neal Driscoll, Robert Karlin, Rob Baskin, John Louie, and Satish Pullammanappallil, 2011, Marine and land active-source seismic imaging of mid-Miocene to Holocene-aged faulting near geothermal prospects at Pyramid Lake, Nevada: Geothermal Resources Council Transactions, 35, 7 pp. Preprint at http://crack.seismo.unr.edu/geothermal/Eisses-GRCpaper-sm.pdf The Pyramid Lake fault zone lies within a vitally important area of the northern Walker Lane where not only can transtension can be studied through a complex arrangement of strike-slip and normal faults but also geothermal activity can be examined in the extensional regime for productivity. This study used advanced and economical seismic methodsmore » in attempt to develop the Paiute Tribe’s geothermal reservoir and to expand upon the tectonics and earthquake hazard knowledge of the area. 500 line-kilometers of marine CHIRP data were collected on Pyramid Lake combined with 27 kilometers of vibrator seismic on-land data from the northwest side of the basin were collected in 2010 that highlighted two distinct phases of faulting. Preliminary results suggest that the geothermal fluids in the area are controlled by the late Pleistoceneto Holocene-aged faults and not through the mid-Miocene-aged conduits as originally hypothesized.« less

Field screening of water quality, bottom sediment, and biota associated with irrigation drainage in and near Walker River Indian Reservation, Nevada 1994-95

USGS Publications Warehouse

Thodal, Carl E.; Tuttle, Peter L.

1996-01-01

A study was begun in 1994 to determine whether the quality of irrigation drainage from the Walker River Indian Reservation, Nevada, has caused or has potential to cause harmful effects on human health or on fish and wildlife, or may adversely affect the suitability of the Walker River for other beneficial uses. Samples of water, bottom sediment, and biota were collected during June-August 1994 (during a drought year) from sites upstream from and on the Walker River Indian Reservation for analyses of trace elements. Other analyses included physical characteristics, major dissolved constituents, selected species of water-soluble nitrogen and phosphorus, and selected pesticides in bottom sediment. Water samples were collected again from four sites on the Reservation in August 1995 (during a wetterthan- average year) to provide data for comparing extreme climatic conditions. Water samples collected from the Walker River Indian Reservation in 1994 equaled or exceeded the Nevada water-quality standard or level of concern for at least one of the following: water temperature, pH, dissolved solids, unionized ammonia, phosphate, arsenic, boron, chromium, lead, and molybdenum; in 1995, only a single sample from one site exceeded a Nevada water-quality standard for molybdenum. Levels of concern for trace elements in bottom sediment collected in 1994 were equaled or exceeded for arsenic, iron, manganese, and zinc. Concentrations of organochiorine pesticide residues in bottom sediment were below analytical reporting limits. Levels of concern for trace-elements in samples of biota were equaled or exceeded for arsenic, boron, copper, and mercury. Results of toxicity testing indicate that only water samples from Walker Lake caused a toxic response in test bacteria. Arsenic and boron concentrations in water, bottom sediment, and biological tissue exceeded levels of concern throughout the Walker River Basin, but most commonly in the lower Walker River Basin. Mercury also was elevated in several biological samples collected throughout the Basin, although concentrations in water and bottom sediment were below analytical reporting limits. Sources of arsenic, boron, and mercury in the Basin are uncertain, but ambient levels reported for a variety of sample matrices collected from western Nevada generally exceed ranges cited as natural background levels. Because these potentially toxic constituents exceeded concern levels in areas that do not directly receive irrigation drainage, concentrations measured in samples collected for this study may not necessarily be attributable to agricultural activities. Diversion of river water for irrigation may have greater effects on beneficial uses of water and on fish and wildlife than does drainage from agricultural areas on the Reservation. In 1994, agricultural water consumption precluded dilution of ground-water seepage to the river channel. This resulted in concentrations of potentially toxic solutes that exceeded levels of concern. Diversion of irrigation water also may have facilitated leaching of potentially toxic solutes from irrigated soil on the Reservation, but during this study all water applied for irrigation on the Reservation was either consumed by evapotranspiration or infiltrated to recharge shallow ground water. No irrigation drainage was found on the Reservation during this study. However, because 1994 samples of ground-water seepage to the Walker River channel exceeded at least six Nevada waterquality standards, water-quality problems may result should ground-water levels rise enough to cause ground-water discharge to the agricultural drain on the Reservation. Nevertheless, the potential for adverse effects from irrigation drainage on the Reservation is believed to be small because surface-water rights for the Walker River Indian Reservation amount to only 2 percent of total surface- water rights in the entire Walker River Basin.

Earth Observation

NASA Image and Video Library

2012-07-29

ISS032-E-010487 (29 July 2012) --- Walker Lake, Nevada is featured in this image photographed by an Expedition 32 crew member on the International Space Station. According to scientists, the Pleistocene landscape of western Nevada approximately 15,000 years ago was one of narrow mountain ranges and numerous interconnected lakes that together formed the extensive glacial Lake Lahontan. Scientists believe drying and warming of the regional climate since the last Ice Age led to the disappearance of the glaciers feeding meltwater to Lake Lahontan, and eventual disappearance of the lake itself. Today, few remnants of Lahontan remain; most of its arms have become dry enclosed basins known as playas. This photograph highlights Walker Lake, one of only two remnant lakes that contain water throughout the year (Pyramid Lake in Nevada is the other). The lake is located in an enclosed basin bounded by the Wassuk Range to the west and the Gillis Range to the east. It is fed by the Walker River flowing from the north. The current dimensions of the lake are approximately 21 kilometers north-south by 9 kilometers east-west. Shoreline deposits at higher elevations than the current lake level form concentric bands that are just visible in the image (bottom center) ? these record varying lake levels in the geologic past. The nearest town is Hawthorne, Nevada to the southeast. To the southwest the highest peak of the Wassuk Range, Mount Grant (elevation 3,496 meters above sea level), dominates the skyline. Green agricultural fields, primarily alfalfa, located to the west of the Wassuk Range (lower right) provide a striking contrast to the surrounding Great Basin desert. These fields are irrigated using water from the nearby East Fork of the Walker River (right, just visible alongside the fields).

Gravity, magnetic, and physical property data in the Smoke Creek Desert area, northwest Nevada

USGS Publications Warehouse

Tilden, Janet E.; Ponce, David A.; Glen, Jonathan M.G.; Chuchel, Bruce A.; Tushman, Kira; Duvall, Alison

2006-01-01

The Smoke Creek Desert, located approximately 100 km (60 mi) north of Reno near the California-Nevada border, is a large basin situated along the northernmost parts of the Walker Lane Belt (Stewart, 1988), a physiographic province defined by northwest-striking topographic features and strike-slip faulting. Because geologic framework studies play an important role in understanding the hydrology of the Smoke Creek Desert, a geologic and geophysical effort was begun to help determine basin geometry, infer structural features, and estimate depth to Pre-Cenozoic rocks, or basement. In May and June of 2004, and June of 2005, the U.S. Geological Survey (USGS) collected 587 new gravity stations, more than 160 line-kilometers (100 line-miles) of truck-towed magnetometer data, and 111 rock property samples in the Smoke Creek Desert and vicinity in northwest Nevada, as part of an effort to characterize its hydrogeologic framework. In the Smoke Creek Desert area, gravity highs occur over rocks of the Skedaddle Mountains, Fox Range, Granite Range, and over portions of Tertiary volcanic rocks in the Buffalo Hills. These gravity highs likely reflect basement rocks, either exposed at the surface or buried at shallow depths. The southern Smoke Creek Desert corresponds to a 25-mGal isostatic gravity low, which corresponds with a basin depth of approximately 2 km. Magnetic highs are likely due to granitic, andesitic, and metavolcanic rocks, whereas magnetic lows are probably associated with less magnetic gneiss and metasedimentary rocks in the region. Three distinctive patterns of magnetic anomalies occur throughout the Smoke Creek Desert and Squaw Creek Valley, likely reflecting three different geological and structural settings.

Final Scientific/Technical Report – DE-EE0002960 Recovery Act. Detachment faulting and Geothermal Resources - An Innovative Integrated Geological and Geophysical Investigation of Pearl Hot Spring, Nevada

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

Stockli, Daniel F.

2015-11-30

The Pearl Host Spring Geothermal Project funded by the DoE Geothermal Program was a joint academic (KU/UT & OU) and industry collaboration (Sierra and Ram Power) to investigate structural controls and the importance of low-angle normal faults on geothermal fluid flow through a multifaceted geological, geophysical, and geochemical investigation in west-central Nevada. The study clearly showed that the geothermal resources in Clayton Valley are controlled by the interplay between low-angle normal faults and active deformation related to the Walker Lane. The study not only identified potentially feasible blind geothermal resource plays in eastern Clayton Valley, but also provide a transportablemore » template for exploration in the area of west-central Nevada and other regional and actively-deforming releasing fault bends. The study showed that deep-seated low-angle normal faults likely act as crustal scale permeability boundaries and could play an important role in geothermal circulation and funneling geothermal fluid into active fault zones. Not unique to this study, active deformation is viewed as an important gradient to rejuvenated fracture permeability aiding the long-term viability of blind geothermal resources. The technical approach for Phase I included the following components, (1) Structural and geological analysis of Pearl Hot Spring Resource, (2) (U-Th)/He thermochronometry and geothermometry, (3) detailed gravity data and modeling (plus some magnetic and resistivity), (4) Reflection and Refraction Seismic (Active Source), (5) Integration with existing and new geological/geophysical data, and (6) 3-D Earth Model, combining all data in an innovative approach combining classic work with new geochemical and geophysical methodology to detect blind geothermal resources in a cost-effective fashion.« less

Digital geologic map of the Thirsty Canyon NW quadrangle, Nye County, Nevada

USGS Publications Warehouse

Minor, S.A.; Orkild, P.P.; Sargent, K.A.; Warren, R.G.; Sawyer, D.A.; Workman, J.B.

1998-01-01

This digital geologic map compilation presents new polygon (i.e., geologic map unit contacts), line (i.e., fault, fold axis, dike, and caldera wall), and point (i.e., structural attitude) vector data for the Thirsty Canyon NW 7 1/2' quadrangle in southern Nevada. The map database, which is at 1:24,000-scale resolution, provides geologic coverage of an area of current hydrogeologic and tectonic interest. The Thirsty Canyon NW quadrangle is located in southern Nye County about 20 km west of the Nevada Test Site (NTS) and 30 km north of the town of Beatty. The map area is underlain by extensive layers of Neogene (about 14 to 4.5 million years old [Ma]) mafic and silicic volcanic rocks that are temporally and spatially associated with transtensional tectonic deformation. Mapped volcanic features include part of a late Miocene (about 9.2 Ma) collapse caldera, a Pliocene (about 4.5 Ma) shield volcano, and two Pleistocene (about 0.3 Ma) cinder cones. Also documented are numerous normal, oblique-slip, and strike-slip faults that reflect regional transtensional deformation along the southern part of the Walker Lane belt. The Thirsty Canyon NW map provides new geologic information for modeling groundwater flow paths that may enter the map area from underground nuclear testing areas located in the NTS about 25 km to the east. The geologic map database comprises six component ArcINFO map coverages that can be accessed after decompressing and unbundling the data archive file (tcnw.tar.gz). These six coverages (tcnwpoly, tcnwflt, tcnwfold, tcnwdike, tcnwcald, and tcnwatt) are formatted here in ArcINFO EXPORT format. Bundled with this database are two PDF files for readily viewing and printing the map, accessory graphics, and a description of map units and compilation methods.

Summary of tectonic and structural evidence for stress orientation at the Nevada Test Site

USGS Publications Warehouse

Carr, Wilfred James

1974-01-01

A tectonic synthesis of the NTS (Nevada Test Site) region, when combined with seismic data and a few stress and strain measurements, suggests a tentative model for stress orientation. This model proposes that the NTS is undergoing extension in a N. 50 ? W.-S. 50 ? E. direction coincident with the minimum principal stress direction. The model is supported by (1) a tectonic similarity between a belt of NTS Quaternary faulting and part of the Nevada-California seismic belt, for which northwest-southeast extension has been suggested; (2) historic northeast- trending natural- and explosion-produced fractures in the NTS; (3) the virtual absence in the NTS of northwest-trending Quaternary faults; (4) the character of north-trending faults and basin configuration in the Yucca Flat area, which suggest a component of right-lateral displacement and post-10 m.y. (million year) oblique separation of the sides of the north-trending depression; (5) seismic evidence suggesting a north- to northwest-trending tension axis; (6) strain measurements, which indicate episodes of northwest-southeast extension within a net northeast-southwest compression; (7) a stress estimate based on tectonic cracking that indicates near-surface northwest-southeast-directed tension, and two stress measurements indicating an excess (tectonic) maximum principal compressive stress in a northeast-southwest direction at depths of about 1,000 feet (305 m); and (8) enlargement of some drill holes in Yucca Flat in a northwest-southeast direction. It is inferred that the stress episode resulting in the formation of deep alluvium-filled trenches began somewhere between 10 and possibly less than 4 m.y. ago in the NTS and is currently active. In the Walker Lane of western Nevada, crystallization of plutons associated with Miocene volcanism may have increased the competency and thickness of the crust and its ability to propagate stress, thereby modulating the frequency (spacing) of basin-range faults.

Kinematics, partitioning and the relationship between velocity and strain in shear zones

NASA Astrophysics Data System (ADS)

Murphy, Justin James

Granite Point, southeast Washington State, captures older distributed deformation deflected by younger localized deformation. This history agrees with mathematical modeling completed by Watkinson and Patton (2005; 2007 in prep). This model suggests that distributed strain occurs at a lower energy threshold than localized strain and predicts deformation histories similar to Granite Point. Ductile shear zones at Granite Point define a zone of deformation where strain is partitioned and localized into at least ten sub parallel shear zones with sinistral, west side down shear sense. Can the relative movement of the boundaries of this partitioned system be reconstructed? Can partitioning be resolved from a distributed style of deformation? The state of strain and kinematics of actively deforming zones was studied by relating the velocity field to strain. The Aleutian Arc, Alaska and central Walker Lane, Nevada were chosen because they have a wealth of geologic data and are recognized examples of obliquely deforming zones. The graphical construction developed by Declan De Paor is ideally suited for this application because it provides a spatially referenced visualization of the relationship between velocity and strain. The construction of De Paor reproduces the observed orientation of strain in the Aleutian Arc, however, the spatial distribution of GPS stations suggest a component of partitioning. Partitioning does not provide a unique solution and cannot be differentiated from a combination of partitioning and distributed strain. In the central Walker Lane, strain trajectories can be reproduced at the domain scale. Furthermore, the effect of anisotropy from Paleozoic through Cenozoic crustal structure, which breaks the regional strain field into pure shear and simple shear dominated transtension can be detected. Without GPS velocities to document strictly coaxial strain, the strain orientation should not be taken as the velocity orientation. The strain recorded at Granite Point should not be used to reconstruct the relative movement of the boundaries because the strain direction may not be parallel to the velocity orientation. Kinematic reconstructions of obliquely deforming zones that assume a palaeo-velocity orientation equal to the measured orientation of finite strain may not accurately reflect the deviation between velocity and strain.

Paleomagnetic Data Bearing on the Evolution of the Walker Lane Belt Transfer Zone From mid-Miocene to Present: an Investigation of the Inferred Southern and Eastern Boundaries.

NASA Astrophysics Data System (ADS)

Grow, J. S.; Geissman, J. W.; Oldow, J. S.

2008-12-01

The Walker Lane Belt (WLB) transfer zone, which initiated in the mid-Miocene, presently links the Eastern California Shear Zone (ECSZ) in the south to the Central Nevada Seismic Belt (CNSB) and WLB to the east and north, respectively. This transfer zone is part of a diffuse intracontinental deformation zone that accommodates some 25 percent of the current motion between the North American and Pacific plates. The boundary of the transfer system is clear on the northern and western margins but the extent of the system to the south and east is only inferred. The extent of deformation and development of the WLB transfer zone since the mid-Miocene is being examined by a paleomagnetic study of 125 sites that includes Miocene to mid-Pliocene volcanic and shallow intrusive rocks near the inferred southern and eastern boundaries. Results from 39 sites inside and along the southern boundary (i.e. Goldfield Hills, Montezuma Range, Clayton Ridge) show about 30° of clockwise rotation (D = 028.3°, I = 57.8°, α95 = 3.9°, discordant from the expected Neogene direction of D = 358°, I = 55°). The area where 13 of these 39 sites are located (i.e. northern Amargosa Range, eastern Slate Ridge) was previously thought to lie outside of the inferred boundary, yet it also shows about 30° of clockwise rotation (D = 031.2°, I = 52.4°, α95 = 6.7°). Areas along the eastern boundary (i.e. southern San Antonio Range) of the transfer zone are still under investigation; data obtained to date are not internally consistent. Overall, the available paleomagnetic data suggest that the southern extent of the WLB transfer zone was larger than previously expected during the mid-Miocene to mid-Pliocene, and based on previous paleomagnetic, structural, and geodetic studies of the area, support a transition from more diffuse to localized deformation (forming the Mina Deflection) at about 3 Ma.

Airborne SAR determination of relative ages of Walker Valley moraines, eastern Sierra Nevada

NASA Technical Reports Server (NTRS)

Fox, A.; Isacks, B.; Bloom, A.; Fielding, E.; Mcmurry, D.

1991-01-01

A regional study of the distribution and elevations of Pleistocene moraines in the Andes requires a method of determining relative age from space. One of our primary objectives is to establish the relative chronology of major climatic events responsible for glaciation in the Andes and other regions that are difficult to access on the ground and where suitable material for absolute age determination is lacking. The sensitivity of radar to surface roughness makes it possible to develop a remotely-based relative dating technique for landforms for which surface age and roughness can be correlated. We are developing such a technique with Airborne Synthetic Aperture Radar (AIRSAR) imagery of the eastern Sierra Nevada where independent evidence is available for the ages and physical characteristics of moraines. The Sierra Nevada moraines are similar in form and environmental setting to Andean moraines that we have targeted for study during the pending Shuttle Imaging Radar-C (SIR-C) mission. SAR imagery is used to differentiate the ages of five moraine sequences of Walker Valley in the eastern Sierra Nevada. Other aspects of this investigation are briefly discussed.

Map showing late Cenozoic faults in the Walker Lake 1 degree by 2 degrees Quadrangle, Nevada-California

USGS Publications Warehouse

Dohrenwend, J.C.

1982-01-01

The Walker Lake 1o x 2o quadrangle lies athwart the transitional boundary between the Sierra Nevade and Basin and Range physiographic provinces. Six distinct topographic domains are identified with the quadrangle (fig. 1). Theses domains are clearly defined by contrasting orientations, densities, and styles of lake Neogene faulting as follows:

Walker River Paiutes: A Tribal History.

ERIC Educational Resources Information Center

Johnson, Edward C.

The Northern Paiute people of Nevada's Walker Lake area were known as the Agai Diccutta (Trout Eaters); they called themselves the Numa, or the People. For as long as anyone could recall, they had lived in the area, catching the huge trout from the lake and harvesting the pinon nuts and other foods from the surrounding desert. In the 1820's the…

Investigations into the Fish Lake Valley Fault Zone (FLVFZ) and its interactions with normal faulting within Eureka and Deep Springs Valleys

NASA Astrophysics Data System (ADS)

Lawson, M. J.; Rhodes, E.; Yin, A.

2016-12-01

In most textbooks, the San Andreas Fault is stated to be the plate boundary between the North American and the Pacific plates, as plate tectonics assumes that boundaries are essentially discrete. In the Western United States this is not the case, as up to 25% of relative plate motion is accommodated on other structures within the Walker Lane Shear Zone (WLSZ) in a diffuse 100 km margin (Faulds et al., 2005; Oldow et al., 2001). Fish Lake Valley Fault Zone (FLVFZ), situated at the northern border of Death Valley National Park, is the northern continuation of the Furnace Creek Fault Zone (FCFZ), and is an important transfer structure within the Walker Lane Shear Zone. Though the FLVFZ has a long term rate (since 10 Ma) of 5 mm/yr (Reheis and Sawyer, 1997), it has a highly variable slip rate. In the middle Pleistocene, the rate has a maximum of up to 11 mm/yr which would accommodate nearly the entirety of slip within the Walker Lane, and yet this rate decreases significantly ( 2.5 to 3 mm/yr) by the late Pleistocene due to unknown causes (Frankel et al. 2007). This variation in slip rate has been proposed by previous workers to be due to strain transience, an increase in the overall strain rate, or due to other unknown structures (Lee et al., 2009). Currently, we are investigating the cause of this variation, and the possibility of the transfer of slip to faults south of the FLVFZ on oblique normal faults within Eureka and Deep Springs Valleys. Preliminary data will be shown utilizing scarp transects, geomorphic scarp modeling, and Optically Stimulated Luminescence (OSL) dating techniques.

Biological control reduces growth, and alters water relations of the saltcedar tree (Tamarix spp.) in western Nevada, USA

Treesearch

R.R. Pattison; C.M. D' Antonio; T.L. Dudley

2011-01-01

We monitored the impacts of a biological control agent, the saltcedar leaf beetle (Diorhabda carinulata), on the saltcedar tree (Tamarix spp.) at two sites (Humboldt and Walker rivers) in Nevada, USA. At the Humboldt site trees that had experienced three to four defoliation events had more negative water potentials and lower...

Structural evolution of the east Sierra Valley system (Owens Valley and vicinity), California: a geologic and geophysical synthesis

USGS Publications Warehouse

Stevens, Calvin H.; Stone, Paul; Blakely, Richard J.

2013-01-01

The tectonically active East Sierra Valley System (ESVS), which comprises the westernmost part of the Walker Lane-Eastern California Shear Zone, marks the boundary between the highly extended Basin and Range Province and the largely coherent Sierra Nevada-Great Valley microplate (SN-GVm), which is moving relatively NW. The recent history of the ESVS is characterized by oblique extension partitioned between NNW-striking normal and strike-slip faults oriented at an angle to the more northwesterly relative motion of the SN-GVm. Spatially variable extension and right-lateral shear have resulted in a longitudinally segmented valley system composed of diverse geomorphic and structural elements, including a discontinuous series of deep basins detected through analysis of isostatic gravity anomalies. Extension in the ESVS probably began in the middle Miocene in response to initial westward movement of the SN-GVm relative to the Colorado Plateau. At ca. 3-3.5 Ma, the SN-GVm became structurally separated from blocks directly to the east, resulting in significant basin-forming deformation in the ESVS. We propose a structural model that links high-angle normal faulting in the ESVS with coeval low-angle detachment faulting in adjacent areas to the east.

Water Budgets of the Walker River Basin and Walker Lake, California and Nevada

USGS Publications Warehouse

Lopes, Thomas J.; Allander, Kip K.

2009-01-01

The Walker River is the main source of inflow to Walker Lake, a closed-basin lake in west-central Nevada. The only outflow from Walker Lake is evaporation from the lake surface. Between 1882 and 2008, upstream agricultural diversions resulted in a lake-level decline of more than 150 feet and storage loss of 7,400,000 acre-feet. Evaporative concentration increased dissolved solids from 2,500 to 17,000 milligrams per liter. The increase in salinity threatens the survival of the Lahontan cutthroat trout, a native species listed as threatened under the Endangered Species Act. This report describes streamflow in the Walker River basin and an updated water budget of Walker Lake with emphasis on the lower Walker River basin downstream from Wabuska, Nevada. Water budgets are based on average annual flows for a 30-year period (1971-2000). Total surface-water inflow to the upper Walker River basin upstream from Wabuska was estimated to be 387,000 acre-feet per year (acre-ft/yr). About 223,000 acre-ft/yr (58 percent) is from the West Fork of the Walker River; 145,000 acre-ft/yr (37 percent) is from the East Fork of the Walker River; 17,000 acre-ft/yr (4 percent) is from the Sweetwater Range; and 2,000 acre-ft/yr (less than 1 percent) is from the Bodie Mountains, Pine Grove Hills, and western Wassuk Range. Outflow from the upper Walker River basin is 138,000 acre-ft/yr at Wabuska. About 249,000 acre-ft/yr (64 percent) of inflow is diverted for irrigation, transpired by riparian vegetation, evaporates from lakes and reservoirs, and recharges alluvial aquifers. Stream losses in Antelope, Smith, and Bridgeport Valleys are due to evaporation from reservoirs and agricultural diversions with negligible stream infiltration or riparian evapotranspiration. Diversion rates in Antelope and Smith Valleys were estimated to be 3.0 feet per year (ft/yr) in each valley. Irrigated fields receive an additional 0.8 ft of precipitation, groundwater pumpage, or both for a total applied-water rate of 3.8 ft/yr. The average corrected total evapotranspiration rate for alfalfa is 3.2 ft/yr so about 0.6 ft/yr (15 percent) flushes salts from the soil. The diversion rate in Bridgeport Valley was estimated to be 1.1 ft/yr and precipitation is 1.3 ft/yr. The total applied-water rate of 2.4 ft/yr is used to irrigate pasture grass. The total applied water rate in the East Fork of the Walker River and Mason Valley was estimated to be 4.8 ft/yr in each valley. The higher rate likely is due to appreciable infiltration, riparian evapotranspiration, or both. Assuming a diversion rate of 3.0 ft/yr, stream loss due to infiltration and riparian evapotranspiration is about 3,000 acre-ft/yr along the East Fork of the Walker River and 14,000 acre-ft/yr in Mason Valley. In the lower Walker River basin, overall and groundwater budgets were calculated for Wabuska to Schurz, Nev., and Schurz to Walker Lake. An overall water budget was calculated for the combined reaches. Imbalances in the water budgets range from 1 to 7 percent, which are insignificant statistically, so the water budgets balance. Total inflow to the Wabuska-Walker Lake reach from the river and others sources is 140,000 acre-ft/yr. Stream and subsurface discharge into the northern end of Walker Lake totals 110,000 acre-ft/yr. About 30,000 acre-ft/yr is lost on the Walker River Indian Reservation from agricultural evapotranspiration, evapotranspiration by native and invasive vegetation, domestic pumpage, and subsurface outflow from the basin through Double Spring and the Wabuska lineament. Alfalfa fields in the upper Walker River basin are lush and have an average corrected total evapotranspiration rate of 3.2 ft/yr. Alfalfa fields on the Walker River Indian Reservation are not as lush and have a total corrected evapotranspiration rate of 1.6-2.1 ft/yr, which partly could be due to alkaline soils that were submerged by Pleistocene Lake Lahontan. The total applied-water rate is 7.0 ft/yr, almost twice the

Lg attenuation, frequency dependence and relative site response of the western United States as revealed by the EarthScope Transportable Array

NASA Astrophysics Data System (ADS)

Gallegos, Andrea; Ranasinghe, Nishath; Ni, James; Sandvol, Eric

2017-06-01

Lg attenuation of the western United States is estimated using regional waveforms recorded by EarthScope's Transportable Array, the Berkeley Digital Seismograph Network and the Caltech Regional Seismic Network. Lg attenuation is determined using the two-station method (TSM). 292 events ranging from magnitude 4 to 6.5 in a time range for the years between 2005 and 2010 are used. We have tomographically mapped variations in effective Lg Q at narrow bands with central frequencies of 0.5, 1, 2 and 3 Hz. The relative site responses of individual stations are determined using a reverse TSM at these central frequencies. Both the two-station and reverse TSMs have the advantage of effectively removing site and source effects without requiring a priori models while mapping lateral heterogeneities in the crust. Regions of high attenuation are found along the Snake River Plain, along the northern California-Oregon border, throughout the Basin and Range, Walker Lane, Wasatch Fault and the Rio Grande Rift. Regions of low attenuation are found in the Colorado Plateau, Rocky Mountains, central Nevada and the Columbia Plateau. Overall, Lg Q was found to have a power-law frequency dependence, with an increase in central frequency resulting in an increase in Q. Relative site responses were found to vary strongly with local geology. Hard rock areas such as the Sierra Nevada Mountains and the Snake River Plain show a consistent pattern of negative site response (i.e. deamplification), while areas with a higher degree of sediments, such as the grabens of the Basin and Range, show positive site response (i.e. amplification). Finally, site responses were found to vary with frequency, becoming less variable and more pronounced as frequency increases.

Active crustal deformation across the Basin and Range province, western United States, measured with the Global Positioning System, 1992-2002

NASA Astrophysics Data System (ADS)

Hammond, W.; Thatcher, W.

2003-04-01

The Basin and Range province of the western United States is a region of active tectonic extension and dextral shear, accommodating roughly 25% of the motion between non-deforming North America (NA) and the Pacific Plate (PA). The orientation of dextral shear is consistent with that of NA/PA relative plate motion, suggesting that this high elevation interior province is an important part of the plate boundary system. We present an analysis of Global Positioning System (GPS) data collected from 1992 to 2002. An 800 km long network of campaign-style geodetic benchmarks extends from east of the Wasatch fault zone (WFZ) in central Utah to west of the Genoa fault zone and Lake Tahoe in the northern Sierra Nevada mountains. From the new data collected in September 2002 and from data collected in 1992, 1996, and 1998, velocities have been estimated at 92 GPS sites, nearly double the number previously presented by Thatcher et al. [1999]. This new data reduces the uncertainty in site velocities and increases the spatial detail compared to earlier results, and now allows resolution of distinct domains in the tensor strain rate field. To process the data we use the GIPSY/OASIS and Quasi-Observation Combination Analysis (Dong et al. [1998]) software packages and incorporate data from continuously recording GPS stations in California and Nevada. The results show that most of the approximately 12 mm/yr of Sierra Nevada block motion is accommodated by right lateral shear and extensional deformation concentrated in the westernmost 200 km of Nevada, in the vicinity of the Walker Lane (WL). A lesser amount of velocity variation (roughly 3 mm/yr) is localized at the easternmost edge of the network, in the vicinity of the Wasatch Fault Zone (WFZ). Estimates of tensor strain rates show transitions in the style of deformation. Near the WFZ only uniaxial, roughly east-west extension can be resolved. Between longitude -112 and -117.5 no deformation is resolvable. Near longitude -118, in the vicinity of the historic ruptures of the Fairview Peak, Dixie Valley, and Rainbow Mountain earthquakes in the Central Nevada Seismic Zone, the deformation is mostly uniaxial extension oriented roughly NW/SE, in agreement with the roughly NE/SW strike of the normal faults. At the WL between longitude -118.5 and -119.5, deformation is best characterized by right lateral simple shear, which transitions westward to a blend of right lateral shear and uniaxial extension at the westernmost end of our network.

M-X Environmental Technical Report. Environmental Characteristics of Alternative Designated Deployment Areas, Native Americans (Nevada/Utah).

DTIC Science & Technology

1980-12-22

surface (Simpson, 1876:87; Wheat, 1967:115; Heizer and Baumhoff, 1962:48). Similar medicine rocks are found today on the Walker River Indian...addition, Heizer and Baumhoff (1962:60) refer to a Medicine Rock (site Pe-27) in the Humboldt Range, Pershing County (see Figure 2.3-1). Northern...1929) and Heizer and Baumhoff (1962). The distribution of known rock art sites in Nevada and western Utah is seen in Figures 2.3-1 and 2.3-2. Since

Science to Sustain Terminal Lakes: The Walker River Basin Study

USGS Publications Warehouse

,

2005-01-01

Section 2507 of Public Law 107-171 (2002 Farm Bill) provided $200,000,000 to be used by the Secretary of the Interior, acting through the Commissioner of Reclamation, to provide water to at-risk natural desert terminal lakes. This bill was later amended under Public Law 108-7, Section 207 to include language 'Restoration of fish, wildlife, and associated habitats in watersheds of certain lakes'. The amendment specified that only Pyramid, Summit, and Walker Lakes in the State of Nevada were to be considered under Section 2507, Public Law 107-171.

Feasibility of Using Video Camera for Automated Enforcement on Red-Light Running and Managed Lanes.

DOT National Transportation Integrated Search

2009-12-25

The overall objective of this study is to evaluate the feasibility, effectiveness, legality, and public acceptance aspects of automated enforcement on red light running and HOV occupancy requirement using video cameras in Nevada. This objective was a...

Mercury in the Walker River Basin, Nevada and California--sources, distribution, and potential effects on the ecosystem

USGS Publications Warehouse

Seiler, Ralph L.; Lico, Michael S.; Wiemeyer Evers, David C.

2004-01-01

Mercury is one of the most serious contaminants of water, sediment, and biota in Nevada because of its use during 19th century mining activities to recover gold and silver from ores. In 1998, mercury problems were discovered in the Walker River Basin of California and Nevada when blood drawn from three common loons from Walker Lake was analyzed and found to have severely elevated mercury levels. From 1999 to 2001, the U.S. Geological Survey and the U.S. Fish and Wildlife Service collected water, sediment, and biological samples to determine mercury sources, distribution, and potential effects on the Walker River Basin ecosystem. Total-mercury concentrations ranged from 0.62 to 57.11 ng/L in streams from the Walker River system and ranged from 1.02 to 26.8 ng/L in lakes and reservoirs. Total-mercury concentrations in streambed sediment ranged from 1 to 13,600 ng/g, and methylmercury concentrations ranged from 0.07 to 32.1 ng/g. The sediment-effects threshold for mercury for fresh-water invertebrates is 200 ng/g, which was exceeded at nine stream sites in the Walker River Basin. The highest mercury concentrations were in streams with historic mines and milling operations in the watershed. The highest mercury concentration in sediment, 13,600 ng/g, was found in Bodie Creek near Bodie, Calif., a site of extensive gold mining and milling activities during the 19th century. Sediment cores taken from Walker Lake show total-mercury concentrations exceeding 1,000 ng/g at depths greater than 15 cm below lake bottom. The presence of 137Cs above 8 cm in one core indicates that the upper 8 cm was deposited sometime after 1963. The mercury peak at 46 cm in that core, 2,660 ng/g, likely represents the peak of mining and gold extraction in the Bodie and Aurora mining districts between 1870 and 1880. Mercury concentrations in aquatic invertebrates at all sites downstream from mining activities in the Rough Creek watershed, which drains the Bodie and Aurora mining districts, were elevated (range 0.263 to 0.863 ?g/g, dry weight). Mercury concentrations in the Walker Lake tui chub, the most abundant and likely prey for common loons, ranged from approximately 0.09 ?g/g to approximately 0.9 ?g/g (wet weight). Larger tui chub in the lake, which are most likely older, had the highest mercury concentrations. Blood samples from 94 common loons collected at Walker Lake between 1998 and 2001 contained a mean mercury concentration of 2.96 ?g/g (standard deviation 1.72 ?g/g). These levels were substantially higher than those found in more than 1,600 common loons tested across North America. Among the 1,600 common loons, the greatest blood mercury concentration, 9.46 ?g/g, was from a loon at Walker Lake. According to risk assessments for northeastern North America, blood mercury concentrations exceeding 3.0 ?g/g cause behavioral, reproductive, and physiological effects. At least 52 percent of the loons at Walker Lake are at risk for adverse effects from mercury on the basis of their blood-mercury concentrations. The larger loons staging in the spring are the most at risk group. The elevated mercury levels found in tui chub and common loons indicate that there is a potential threat to the well being and reproduction of fish and wildlife that use Walker Lake. Wildlife that use Weber Reservoir may also be at risk because it is the first reservoir downstream from mining activities in the Bodie and Aurora areas and mercury concentrations in sediment were elevated. Additional data on mercury concentrations in top level predators, such as piscivorous fish and birds, are needed to assess public health and other environmental risks.

Tectonic and Structural Controls of Geothermal Activity in the Great Basin Region, Western USA

NASA Astrophysics Data System (ADS)

Faulds, J. E.; Hinz, N.; Kreemer, C. W.

2012-12-01

We are conducting a thorough inventory of structural settings of geothermal systems (>400 total) in the extensional to transtensional Great Basin region of the western USA. Most of the geothermal systems in this region are not related to upper crustal magmatism and thus regional tectonic and local structural controls are the most critical factors controlling the locations of the geothermal activity. A system of NW-striking dextral faults known as the Walker Lane accommodates ~20% of the North American-Pacific plate motion in the western Great Basin and is intimately linked to N- to NNE-striking normal fault systems throughout the region. Overall, geothermal systems are concentrated in areas with the highest strain rates within or proximal to the eastern and western margins of the Great Basin, with the high temperature systems clustering in transtensional areas of highest strain rate in the northwestern Great Basin. Enhanced extension in the northwestern Great Basin probably results from the northwestward termination of the Walker Lane and the concomitant transfer of dextral shear into west-northwest directed extension, thus producing a broad transtensional region. The capacity of geothermal power plants also correlates with strain rates, with the largest (hundreds of megawatts) along the Walker Lane or San Andreas fault system, where strain rates range from 10-100 nanostrain/yr to 1,000 nanostrain/yr, respectively. Lesser systems (tens of megawatts) reside in the Basin and Range (outside the Walker Lane), where local strain rates are typically < 10 nanostrain/yr. Of the 250+ geothermal fields catalogued, step-overs or relay ramps in normal fault zones serve as the most favorable setting, hosting ~32% of the systems. Such areas have multiple, overlapping fault strands, increased fracture density, and thus enhanced permeability. Other common settings include a) intersections between normal faults and strike-slip or oblique-slip faults (27%), where multiple minor faults connect major structures and fluids can flow readily through highly fractured, dilational quadrants, and b) normal fault terminations or tip-lines (22%), where horse-tailing generates closely-spaced faults and increased permeability. Other settings include accommodation zones (i.e., belts of intermeshing, oppositely dipping normal faults; 8%), major range-front faults (5-6%), and pull-aparts in strike-slip faults (4%). In addition, Quaternary faults lie within or near most systems. The relative scarcity of geothermal systems along displacement-maxima of major normal faults may be due to reduced permeability in thick zones of clay gouge and periodic release of stress in major earthquakes. Step-overs, terminations, intersections, and accommodation zones correspond to long-term, critically stressed areas, where fluid pathways are more likely to remain open in networks of closely-spaced, breccia-dominated fractures. These findings may help guide future exploration efforts, especially for blind geothermal systems, which probably comprise the bulk of the geothermal resources in the Great Basin.

Report: Examination of Costs Claimed under EPA Grant X96906001 Awarded to Walker Lake Working Group, Hawthorne, Nevada

EPA Pesticide Factsheets

Report #10-2-0054, January 6, 2010. The grantee did not meet financial management requirements specified by Title 40 Code of Federal Regulations Part 30 and Title 2 Code of Federal Regulations Part 30.

Steady, modest slip over multiple earthquake cycles on the Owens Valley and Little Lake fault zones

NASA Astrophysics Data System (ADS)

Amos, C. B.; Haddon, E. K.; Burgmann, R.; Zielke, O.; Jayko, A. S.

2015-12-01

A comprehensive picture of current plate-boundary deformation requires integration of short-term geodetic records with longer-term geologic strain. Comparing rates of deformation across these time intervals highlights potential time-dependencies in both geodetic and geologic records and yields critical insight into the earthquake deformation process. The southern Walker Lane Belt in eastern California represents one location where short-term strain recorded by geodesy apparently outpaces longer-term geologic fault slip measured from displaced rocks and landforms. This discrepancy persists both for individual structures and across the width of the deforming zone, where ~1 cm/yr of current dextral shear exceeds Quaternary slip rates summed across individual faults. The Owens Valley and Little Lake fault systems form the western boundary of the southern Walker Lane and host a range of published slip rate estimates from ~1 - 7 mm/yr over varying time intervals based on both geodetic and geologic measurements. New analysis of offset geomorphic piercing lines from airborne lidar and field measurements along the Owens Valley fault provides a snapshot of deformation during individual earthquakes and over many seismic cycles. Viewed in context of previously reported ages from pluvial and other landforms in Owens Valley, these offsets suggest slip rates of ~0.6 - 1.6 mm/yr over the past 103 - 105 years. Such rates agree with similar estimates immediately to the south on the Little Lake fault, where lidar measurements indicate dextral slip averaging ~0.6 - 1.3 mm/yr over comparable time intervals. Taken together, these results suggest steady, modest slip in the absence of significant variations over the Mid-to-Late Quaternary for a ~200 km span of the southwestern Walker Lane. Our findings argue against the presence of long-range fault interactions and slip-rate variations for this portion of the larger, regional fault network. This result also suggests that faster slip-rate estimates from geodetic measurements reflect transients over much shorter time scales. Additionally, the persistence of relatively faster geodetic shear in comparison with time-averaged fault slip leaves open the possibility of significant off-fault deformation or slip on subsidiary structures across the Owens Valley.

Marine and land active-source seismic investigation of geothermal potential, tectonic structure, and earthquake hazards in Pyramid Lake, Nevada

NASA Astrophysics Data System (ADS)

Eisses, A.; Kell, A. M.; Kent, G.; Driscoll, N. W.; Karlin, R. E.; Baskin, R. L.; Louie, J. N.; Smith, K. D.; Pullammanappallil, S.

2011-12-01

Preliminary slip rates measured across the East Pyramid Lake fault, or the Lake Range fault, help provide new estimates of extension across the Pyramid Lake basin. Multiple stratigraphic horizons spanning 48 ka were tracked throughout the lake, with layer offsets measured across all significant faults in the basin. A chronstratigraphic framework acquired from four sediment cores allows slip rates of the Lake Range and other faults to be calculated accurately. This region of the northern Walker Lake, strategically placed between the right-lateral strike-slip faults of Honey and Eagle Lakes to the north, and the normal fault bounded basins to the southwest (e.g., Tahoe, Carson), is critical in understanding the underlying structural complexity that is not only necessary for geothermal exploration, but also earthquake hazard assessment due to the proximity of the Reno-Sparks metropolitan area. In addition, our seismic CHIRP imaging with submeter resolution allows the construction of the first fault map of Pyramid Lake. The Lake Range fault can be obviously traced west of Anahoe Island extending north along the east end of the lake in numerous CHIRP lines. Initial drafts of the fault map reveal active transtension through a series of numerous, small, northwest striking, oblique-slip faults in the north end of the lake. A previously field mapped northwest striking fault near Sutcliff can be extended into the west end of Pyramid Lake. This fault map, along with the calculated slip rate of the Lake Range, and potentially multiple other faults, gives a clearer picture into understanding the geothermal potential, tectonic regime and earthquake hazards in the Pyramid Lake basin and the northern Walker Lane. These new results have also been merged with seismicity maps, along with focal mechanisms for the larger events to begin to extend our fault map in depth.

Assessing the Effects of Water Right Purchases on Stream Temperatures and Fish Habitat

NASA Astrophysics Data System (ADS)

Elmore, L.; Null, S. E.

2012-12-01

Warm stream temperature and low flow conditions are limiting factors for native trout species in Nevada's Walker River. Water rights purchases are being considered to increase instream flow and improve habitat conditions. However, the effect of water rights purchases on stream temperatures and fish habitat have yet to be assessed. Manipulating flow conditions affect stream temperatures by altering water depth, velocity, and thermal mass. This study uses the River Modeling System (RMSv4), an hourly, physically-based hydrodynamic and water quality model, to estimate flows and stream temperatures in the Walker River. The model is developed for two wet years (2010-2011). Study results highlight reaches with cold-water habitat that is suitable for native trout species. Previous research on the Walker River has evaluated instream flow changes with water rights purchases. This study incorporates stream temperatures as a proxy for trout habitat, and thus explicitly incorporates water quality and fish habitat into decision-making regarding water rights purchases. Walker River

Effect of psychological tension on pedestrian counter flow via an extended cost potential field cellular automaton model

NASA Astrophysics Data System (ADS)

Li, Xingli; Guo, Fang; Kuang, Hua; Zhou, Huaguo

2017-12-01

Psychology tells us that the different level of tension may lead to different behavior variation for individuals. In this paper, an extended cost potential field cellular automaton is proposed to simulate pedestrian counter flow under an emergency by considering behavior variation of pedestrian induced by psychological tension. A quantitative formula is introduced to describe behavioral changes caused by psychological tension, which also leads to the increasing cost of discomfort. The numerical simulations are performed under the periodic boundary condition and show that the presented model can capture some essential features of pedestrian counter flow, such as lane formation and segregation phenomenon for normal condition. Furthermore, an interesting feature is found that when pedestrians are in an extremely nervous state, a stable lane formation will be broken by a disordered mixture flow. The psychological nervousness under an emergency is not always negative to moving efficiency and a moderate level of tension will delay the occurrence of jamming phase. In addition, a larger asymmetrical ratio of left walkers to right walkers will improve the critical density related to the jamming phase and retard the occurrence of completely jammed phase. These findings will be helpful in pedestrian control and management under an emergency.

Kinematic Model for the Sierra Nevada Frontal Fault Zone, California: Paleomagnetism of the Eureka Valley Tuff

NASA Astrophysics Data System (ADS)

Rood, D. H.; Burbank, D. W.; Luyendyk, B. P.

2005-12-01

We document the geometry, timing, rates, and kinematic style of Late Tertiary deformation between Sonora Pass and Mono Basin, central Sierra Nevada, California. Observed mismatches between geodetic and geologic deformation rates in the western Great Basin may be primarily due to underestimates of true geologic deformation. Relatively little attention has been paid to the role of permanent deformation between faults, i.e. folding or crustal block rotation. Current slip discrepancies may be accounted for if a significant component of off-fault transrotational deformation is present. We use geologic and paleomagnetic data to address the kinematic development of the Sierra Nevada frontal fault zone (SNFFZ), and to quantify both the elastic and inelastic strain accumulated across the Sierra Nevada-Basin and Range transition since ~9 Ma. The complex structure of this transition, between the regions of Sonora Pass and Mono Basin, may be a result of three distinct modes of dextral shear accommodation (transtensional, transpressional, and crustal thinning). The study area is characterized by four important structural elements that lie between the SNFFZ and Walker Lane Belt: (1) N- to NNW-striking normal and oblique faults, dominantly E-dipping, and associated W-tilted fault blocks; (2) NW-striking dextral faults; (3) ENE- to NE-striking left-lateral oblique faults that may accommodate overall dextral shear through clockwise vertical axis rotations of fault blocks; (4) E- to NE-trending folds, which may accommodate N-S shortening at large-scale left steps in the dextral transtensional fault system. Between Bridgeport and Mono Basins, a regional E- to NE-trending fold is present that affects both the Tertiary volcanic strata and a Quaternary glacial outwash surface. To the west, normal faulting rates on the SNFFZ are 1-2 mm/yr (Bursik and Sieh, 1989). This slip decreases to the north, into the folded region of the Bodie Hills. This kinematic relationship suggests that the region may be an accommodation zone between two linking faults, possibly an active fold that accommodates N-S shortening at a large-scale left step in the range front fault system. We collected ~200 paleomagnetic samples from the Late Miocene Eureka Valley Tuff of the Stanislaus Group at 21 sites over a 125-km-long, E-W transect (from the Sierra Nevada foothills to east of Mono Basin). Stepwise AF demagnetization reveals a stable characteristic remnant magnetization. Our preliminary data suggest 20-40 degrees of clockwise rotation adjacent to faults of the SNFFZ. An expanded dataset aims to identify specific structural domains, quantify differential vertical axis block rotations, and test geometric models of transrotation (i.e. block-specific versus gradational) during transtensional lithospheric deformation.

High Resolution Seismic Imaging of the Trench Canyon Fault Zone, Mono Lake, Northeastern California

NASA Astrophysics Data System (ADS)

Novick, M. W.; Jayko, A. S.; Roeske, S.; McClain, J. S.; Hart, P. E.; Boyle, M.

2009-12-01

High resolution seismic imaging of Mono Lake, located in northeastern California, has revealed an approximately northwest striking fault in the area to the west of aerially exposed Negit Volcano. This fault, henceforth referred to as the Trench Canyon Fault (TCF), has also been mapped onshore along a correlating strike as far north as Cedar Hill Volcano, located to the northeast of the lake on the California/Nevada border. Onshore, the TCF was mapped for approximately 10 kilometers using air photos, DEM images, and standard geologic pace and compass mapping techniques. The TCF post- dates the last glacial maximum, evidenced by the cutting of wave cut benches along Cedar Hill Volcano. Relict, non-historic shorelines, left by the steady evaporation of Mono Lake beginning approximately 13k, are also repeatedly cut by the fault. Additional evidence of fault presence includes sag ponds, pressure ridges, tectonically fractured rocks, and normal fault scarps found along strike. Offshore, DEM images show a northeast striking structure to the northwest of Negit Volcano, which is co-linear with the onshore TCF. High resolution seismic imaging of the structure, using an applied acoustic/SIG mini-sparker system, reveals steeply dipping Holocene sediments, as well as volcanic deposits from active vents which have erupted in the last 1000 years, offset by the fault. Detailed structural analysis of the previously unstudied Trench Canyon Fault (TFC) and faults in the Cedar Hill region of northern California, along with seismic studies of sediments beneath Mono Lake not only allow for a better comprehension of this minor fault system, but provide greater understanding of the larger and more complex Walker Lane Shear Zone. Fault analyses, combined and correlated with those from CHV, give a better understanding of how slip is transferred into the complicated Mina defection to the east, from the dextral and normal faults along the Sierra Nevada Range front.

Bathymetry of Walker Lake, West-Central Nevada

USGS Publications Warehouse

Lopes, Thomas J.; Smith, J. LaRue

2007-01-01

Walker Lake lies within a topographically closed basin in west-central Nevada and is the terminus of the Walker River. Much of the streamflow in the Walker River is diverted for irrigation, which has contributed to a decline in lake-surface altitude of about 150 feet and an increase in dissolved solids from 2,500 to 16,000 milligrams per liter in Walker Lake since 1882. The increase in salinity threatens the fresh-water ecosystem and survival of the Lahontan cutthroat trout, a species listed as threatened under the Endangered Species Act. Accurately determining the bathymetry and relations between lake-surface altitude, surface area, and storage volume are part of a study to improve the water budget for Walker Lake. This report describes the updated bathymetry of Walker Lake, a comparison of results from this study and a study by Rush in 1970, and an estimate of the 1882 lake-surface altitude. Bathymetry was measured using a single-beam echosounder coupled to a differentially-corrected global positioning system. Lake depth was subtracted from the lake-surface altitude to calculate the altitude of the lake bottom. A Lidar (light detection and ranging) survey and high resolution aerial imagery were used to create digital elevation models around Walker Lake. The altitude of the lake bottom and digital elevation models were merged together to create a single map showing land-surface altitude contours delineating areas that are currently or that were submerged by Walker Lake. Surface area and storage volume for lake-surface altitudes of 3,851.5-4,120 feet were calculated with 3-D surface-analysis software. Walker Lake is oval shaped with a north-south trending long axis. On June 28, 2005, the lake-surface altitude was 3,935.6 feet, maximum depth was 86.3 feet, and the surface area was 32,190 acres. The minimum altitude of the lake bottom from discrete point depths is 3,849.3 feet near the center of Walker Lake. The lake bottom is remarkably smooth except for mounds near the shore and river mouth that could be boulders, tree stumps, logs, or other submerged objects. The echosounder detected what appeared to be mounds in the deepest parts of Walker Lake, miles from the shore and river mouth. However, side-scan sonar and divers did not confirm the presence of mounds. Anomalies occur in two northwest trending groups in northern and southern Walker Lake. It is hypothesized that some anomalies indicate spring discharge along faults based on tufa-like rocks that were observed and the northwest trend parallel to and in proximity of mapped faults. Also, evaporation measured from Walker Lake is about 50 percent more than the previous estimate, indicating more water is flowing into the lake from sources other than the Walker River. Additional studies need to be done to determine what the anomalies are and whether they are related to the hydrology of Walker Lake. Most differences in surface area and storage volume between this study and a study by Rush in 1970 were less than 1 percent. The largest differences occur at lake-surface altitudes less than 3,916 feet. In general, relations between lake-surface altitude, surface area, and storage volume from Rush's study and this study are nearly identical throughout most of the range in lake-surface altitude. The lake-surface altitude in 1882 was estimated to be between 4,080 feet and 4,086 feet with a probable altitude of 4,082 feet. This estimate compares well with two previous estimates of 4,083 feet and 4,086 feet. Researchers believe the historic highstand of Walker Lake occurred in 1868 and estimated the highstand was between 4,089 feet and 4,108 feet. By 1882, Mason Valley was predominantly agricultural. The 7-26 feet decline in lake-surface altitude between 1868 and 1882 could partially be due to irrigation diversions during this time.

76 FR 19030 - Lyon & Mineral County Resource Advisory Committee

Federal Register 2010, 2011, 2012, 2013, 2014

2011-04-06

... Committee will meet in Smith Valley, Nevada. The committee is meeting as authorized under the Secure Rural...: The meeting will be held April 25, 2011 at 9 a.m. ADDRESSES: The meeting will be held at the Smith Valley Library at 32 Day Lane, Smith Valley, NV 89444. Written comments should be sent to Mike Crawley...

75 FR 26774 - Notice of Re-Designation of the Service Delivery Area for the Cowlitz Indian Tribe

Federal Register 2010, 2011, 2012, 2013, 2014

2010-05-12

... Tribe of Louisiana St. Mary Parish, LA. Cocopah Tribe of Arizona Yuma, AZ, Imperial, CA. Coeur D'Alene... of the Colville Chelan, WA,\\8\\ Douglas, WA, Reservation, Washington. Ferry, WA, Grant, WA, Lincoln... & Siuslaw Indians of Oregon. Douglas, OR, Lane, OR, Lincoln, OR. Confederated Tribes of the Goshute Nevada...

New Mapping in the Sand Springs Range of Western Nevada Clarifies and Constrains Regional Deformation Sequences of the Luning-Fencemaker Thrust Belt

NASA Astrophysics Data System (ADS)

Czarnecki, S.; Jarvis, J.; Satterfield, J. I.

2016-12-01

The Sand Springs Range in western Nevada exposes Mesozoic through Cenozoic structures of the eastern Sierra Nevada, Luning-Fencemaker Thrust Belt (LFTB), Basin and Range province, and Walker Lane. A recent undergraduate geologic mapping project in the northern Sand Springs Range (nSSR) set out to map igneous intrusions in detail, specifically smaller intrusions which had not been a focus in previous work. This was accomplished using different techniques including mapping at a smaller scale (1:8000 vs. 1:24000), locating contacts and faults using handheld GPS, and focusing on relationships between metamorphic tectonites and igneous units. This revealed key cross-cutting relations between structures and diverse Triassic through Tertiary igneous rocks as well as distinctions between the nSSR and the surrounding LFTB assemblages. During our mapping we identified four metamorphic tectonite map units, Cretaceous granitoid and diorite plutons and sills, Tertiary rhyolite sills and dikes, and interbedded Tertiary basalt and ash flow tuff. The cross-cutting relations of these units overturn previously published sequences of events and constrain the timing of a deformation sequence which differs from the surrounding LFTB assemblages. We found that the nSSR contains three phases of deformation: a pre-LFTB syn-metamorphic event which achieved amphibolite facies that is not described elsewhere in the LFTB (D1), followed by two non-metamorphic folding and thrusting phases characteristic of the LFTB (D2 and D3). Our mapping provided four key timing constraints. First, D1 axial-planar cleavage (S1) deformed Triassic intrusions. Second, Cretaceous granitoid and diorite units cross-cut S1 foliation, D1 folds, and low-angle faults. Third, Cretaceous and Tertiary sills that locally terminate at a low-angle fault actually post-dated faulting. Fourth, cross-cutting relations showed a basaltic lava previously mapped as Jurassic is actually Tertiary. The large Sand Springs Pluton was the only intrusion mapped in detail during previous studies; but our mapping has demonstrated the importance of both small and large intrusions in understanding the overall structural history of a complex area. This project was supported by research grants from Angelo State University and the Southwest Section AAPG.

Estimates of Deep Percolation Beneath Native Vegetation, Irrigated Fields, and The Amargosa-River Channel, Amargosa Desert, Nye County, Nevada

DTIC Science & Technology

2003-01-01

based primarily on measurements of spring discharge (Walker and Eakin, 1963; Winograd and Thordarson , 1975; Dudley and Larson, 1976). The other...vadose-zone profiles from the northern Mojave Desert: Water Resources Research, v. 38, no. 12, p. 27-1 to 27-12. Winograd, I.J., and Thordarson , W

Water-related scientific activities of the U.S. Geological Survey in Nevada, fiscal years 1993-94

USGS Publications Warehouse

Foglesong, M. Teresa

1995-01-01

The U.S. Geological Survey has been collecting water-resources data in Nevada since 1890. Most of the projects that constitute the current Nevada District program can be classified as either basic- data acquisition (about 25 percent) or hydrologic interpretation (about 75 percent). About 39 percent of the activities are supported by cooperative agreements with State and local agencies. Technical projects supported by other Federal agencies make up about 32 percent of the program, and the re- maining 29 percent consists of USGS data collection, interpretive projects, and research. Water con- ditions in most of Nevada during fiscal years 1993 and 1994 continued to be dry, a continuation of drought conditions since late 1986. The major water-resource issues in Nevada include: water allocation in the Truckee River and Carson River Basins; water-supply needs of Las Vegas and the Reno/Sparks area, including water-importation plans; hydrologic effects of weapons testing at the Nevada Test Site; assessment of potential long-term effects of the proposed Yucca Mountain Nuclear Waste Repository; and drought. Future water-resources issues in Nevada are likely to center on water supply for, and environmental effects of, the rapidly growing population centers at Las Vegas, Reno, and Elko; impacts of operations at the Nevada Test Site; management of interstate rivers such as the Truckee, Carson, Walker, and Colorado Rivers; hydrologic and environmental impacts at heavily mined areas; and water-quality management in the Lake Tahoe Basin.

STRUCTURAL CONTROLS OF THE EMERSON PASS GEOTHERMAL SYSTEM, NORTHWESTERN NEVADA: CHARACTERIZATION OF A "BLIND" SYSTEM

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

Anderson, Ryan B; Faulds, James E

Detailed geologic analyses have elucidated the kinematics, stress state, structural controls, and past surface activity of a blind geothermal system in Emerson Pass on the Pyramid Lake Paiute Reservation, western Nevada. The Emerson Pass area resides near the boundary of the Basin and Range and Walker Lane provinces and at the western edge of a broad left step or relay ramp between the north- to north-northeast-striking, west-dipping, Fox and Lake Range normal faults. The step-over provides a structurally favorable setting for deep circulation of meteoric fluids. Strata in the area are comprised of late Miocene to Pliocene sedimentary rocks andmore » the middle Miocene Pyramid sequence mafic to intermediate volcanic rocks, all overlying Mesozoic metasedimentary and intrusive rocks. A thermal anomaly was discovered in Emerson Pass by use of 2-m temperature surveys deployed within a structurally favorable setting and proximal to surface features indicative of geothermal activity. The 2-m temperature surveys define a north-south elongate thermal anomaly that has a maximum recorded temperature of ~60°C and resides on a north- to north-northeast-striking normal fault. Although the active geothermal system is expressed solely as a soil heat anomaly, late Pleistocene travertine and tufa mounds, chalcedonic silica/calcite veins, and silica cemented Pleistocene lacustrine gravels indicate a robust geothermal system was active at the surface in the recent past. The geothermal system is controlled primarily by the broad step-over between two major range-bounding normal faults. In detail, the system likely results from enhanced permeability generated by the intersection of two oppositely dipping, southward terminating north- to north-northwest-striking (Fox Range fault) and north-northeast-striking normal faults. Structural complexity and spatial heterogeneities of the strain and stress field have developed in the step-over region, but kinematic data suggest a west-northwest-trending (~280° azimuth) extension direction. Therefore, geothermal activity in the Emerson Pass area is probably hosted on north-to north-northeast striking normal faults.« less

Geophysical Investigations of the Smoke Creek Desert and their Geologic Implications, Northwest Nevada and Northeast California

USGS Publications Warehouse

Ponce, David A.; Glen, Jonathan M.G.; Tilden, Janet E.

2006-01-01

The Smoke Creek Desert is a large basin about 100 km (60 mi) north of Reno near the California-Nevada border, situated along the northernmost parts of the Walker Lane Belt, a physiographic region defined by diverse topographic expression consisting of northweststriking topographic features and strike-slip faulting. Because geologic and geophysical framework studies play an important role in understanding the hydrogeology of the Smoke Creek Desert, a geophysical effort was undertaken to help determine basin geometry, infer structural features, and estimate depth to basement. In the northernmost parts of the Smoke Creek Desert basin, along Squaw Creek Valley, geophysical data indicate that the basin is shallow and that granitic rocks are buried at shallow depths throughout the valley. These granitic rocks are faulted and fractured and presumably permeable, and thus may influence ground-water resources in this area. The Smoke Creek Desert basin itself is composed of three large oval sub-basins, all of which reach depths to basement of up to about 2 km (1.2 mi). In the central and southern parts of the Smoke Creek Desert basin, magnetic anomalies form three separate and narrow EW-striking features. These features consist of high-amplitude short-wavelength magnetic anomalies and probably reflect Tertiary basalt buried at shallow depth. In the central part of the Smoke Creek Desert basin a prominent EW-striking gravity and magnetic prominence extends from the western margin of the basin to the central part of the basin. Along this ridge, probably composed of Tertiary basalt, overlying unconsolidated basin-fill deposits are relatively thin (< 400 m). The central part of the Smoke Creek Desert basin is also characterized by the Mid-valley fault, a continuous geologic and geophysical feature striking NS and at least 18-km long, possibly connecting with faults mapped in the Terraced Hills and continuing southward to Pyramid Lake. The Mid-valley fault may represent a lateral (east-west) barrier to ground-water flow. In addition, the Mid-valley fault may also be a conduit for along-strike (north-south) ground-water flow, channeling flow to the southernmost parts of the basin and the discharge areas north of Sand Pass.

Crustal controls on magmatic-hydrothermal systems: A geophysical comparison of White River, Washington, with Goldfield, Nevada

USGS Publications Warehouse

Blakely, R.J.; John, D.A.; Box, S.E.; Berger, B.R.; Fleck, R.J.; Ashley, R.P.; Newport, G.R.; Heinemeyer, G.R.

2007-01-01

The White River altered area, Washington, and the Goldfield mining district, Nevada, are nearly contemporaneous Tertiary (ca.20 Ma) calc-alkaline igneous centers with large exposures of shallow (<1 km depth) magmatic-hydrothermal, acid-sulfate alteration. Goldfield is the largest known high-sulfidation gold deposit in North America. At White River, silica is the only commodity exploited to date, but, based on its similarities with Goldfield, White River may have potential for concealed precious and/or base metal deposits at shallow depth. Both areas are products of the ancestral Cascade arc Goldfield lies within the Great Basin physiographic province in an area of middle Miocene and younger Basin and Range and Walker Lane faulting, whereas White River is largely unaffected by young faults. However, west-northwest-striking magnetic anomalies at White River do correspond with mapped faults synchronous with magmatism, and other linear anomalies may reflect contemporaneous concealed faults. The White River altered area lies immediately south of the west-northwest-striking White River fault zone and north of a postulated fault with similar orientation. Structural data from the White River altered area indicate that alteration developed synchronously with an anomalous stress field conducive to left-lateral, strike-slip displacement on west-north-west-striking faults. Thus, the White River alteration may have developed in a transient transtensional region between the two strike-slip faults, analogous to models proposed for Goldfield and other mineral deposits in transverse deformational zones. Gravity and magnetic anomalies provide evidence for a pluton beneath the White River altered area that may have provided heat and fluids to overlying volcanic rocks. East- to east- northeast-striking extensional faults and/or fracture zones in the step-over region, also expressed in magnetic anomalies, may have tapped this intrusion and provided vertical and lateral transport of fluids to now silicified areas. By analogy to Goldfield, geophysical anomalies at the White River altered area may serve as proxies for geologic mapping in identifying faults, fractures, and intrusions relevant to hydrothermal alteration and ore formation in areas of poor exposure. ?? 2006 Geological Society of America.

STRUCTURAL CONTROLS OF THE EMERSON PASS GEOTHERMAL SYSTEM, NORTHWESTERN NEVADA: CHARACTERIZATION OF A "BLIND" SYSTEM

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

Anderson, Ryan B; Faulds, James E

The Pyramid Lake area is favorable for geothermal development due to the tectonic setting of the region. The Walker Lane belt, a dextral shear zone that accommodates ~20% relative motion between the Pacific and North American plates, terminates northwestward in northeast California. NW-directed dextral shear is transferred to WNW extension accommodated by N-to -NNE striking normal faults of the Basin and Range. As a consequence, enhanced dilation occurs on favorably oriented faults generating high geothermal potential in the northwestern Great Basin. The NW-striking right-lateral Pyramid Lake fault, a major structure of the northern Walker Lane, terminates at the southern endmore » of Pyramid Lake and transfers strain to the NNE-striking down to the west Lake Range fault, resulting in high geothermal potential. Known geothermal systems in the area have not been developed due to cultural considerations of the Pyramid Lake Paiute Tribe. Therefore, exploration has been focused on discovering blind geothermal systems elsewhere on the reservation by identifying structurally favorable settings and indicators of past geothermal activity. One promising area is the northeast end of Pyramid Lake, where a broad left step between the west-dipping range-bounding faults of the Lake and Fox Ranges has led to the formation of a broad, faulted relay ramp. Furthermore, tufa mounds, mineralized veins, and altered Miocene rocks occur proximal to a thermal anomaly discovered by a 2-m shallow temperature survey at the north end of the step-over in Emerson Pass. Detailed geologic mapping has revealed a system of mainly NNE-striking down to the west normal faults. However, there are three notable exceptions to this generality, including 1) a prominent NW-striking apparent right-lateral fault, 2) a NW-striking down to the south fault which juxtaposes the base of the mid-Miocene Pyramid sequence against younger late Tertiary sedimentary rocks, and 3) a NNE-striking down to the east normal fault, which accommodates motion such that the Mesozoic Nightingale sequence is juxtaposed with late Tertiary sedimentary rocks. The NW dextral fault, the NNE-down to east fault, and several NNE-down to the west faults intersect roughly at the thermal anomaly in Emerson Pass. This suggests that fault intersections locally control upwelling of geothermal fluids within the step-over. Based on this assumption, it is proposed that the area near Buckbrush Springs be investigated further for geothermal potential. At this location, a NNE-down to the west normal fault, with >1 km of offset, intersects a NW-striking down to the south fault at a small left step in the NNE fault. Further studies will include collection of available kinematic indicators near the shallow thermal anomaly in Emerson Pass, geothermometry on Buckbrush Spring, and possibly drilling of temperature gradient wells in Emerson Pass and at Buckbrush Spring.« less

Active tectonics of northwestern U.S. inferred from GPS-derived surface velocities

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

Robert McCaffrey; Robert W. King; Suzette J. Payne

2013-02-01

Surface velocities derived from GPS observations from 1993 to 2011 at several hundred sites across the deforming northwestern United States are used to further elucidate the region's active tectonics. The new velocities reveal that the clockwise rotations, relative to North America, seen in Oregon and western Washington from earlier GPS observations, continue to the east to include the Snake River Plain of Idaho and south into the Basin and Range of northern Nevada. Regional-scale rotation is attributed to gravitationally driven extension in the Basin and Range and Pacific-North America shear transferred through the Walker Lane belt aided by potentially strongmore » pinning below the Idaho Batholith. The large rotating section comprising eastern Oregon displays very low internal deformation rates despite seismological evidence for a thin crust, warm mantle, organized mantle flow, and elevated topography. The observed disparity between mantle and surface kinematics suggests that either little stress acts between them (low basal shear) or that the crust is strong relative to the mantle. The rotation of the Oregon block impinges on Washington across the Yakima fold-thrust belt where shortening occurs in a closing-fan style. Elastic fault locking at the Cascadia subduction zone is reevaluated using the GPS velocities and recently published uplift rates. The 18 year GPS and 80 year leveling data can both be matched with a common locking model suggesting that the locking has been stable over many decades. The rate of strain accumulation is consistent with hundreds of years between great subduction events.« less

Uranium transport in the Walker River Basin, California and Nevada

USGS Publications Warehouse

Benson, L.V.; Leach, D.L.

1979-01-01

During the summer of 1976 waters from tributaries, rivers, springs and wells were sampled in the Walker River Basin. Snow and sediments from selected sites were also sampled. All samples were analyzed for uranium and other elements. The resulting data provide an understanding of the transport of uranium within a closed hydrologic basin as well as providing a basis for the design of geochemical reconnaissance studies for the Basin and Range Province of the Western United States. Spring and tributary data are useful in locating areas containing anomalous concentrations of uranium. However, agricultural practices obscure the presence of known uranium deposits and render impossible the detection of other known deposits. Uranium is extremely mobile in stream waters and does not appear to sorb or precipitate. Uranium has a long residence time (2500 years) in the open waters of Walker Lake; however, once it crosses the sediment-water interface, it is reduced to the U(IV) state and is lost from solution. Over the past two million years the amount of uranium transported to the terminal point of the Walker River system may have been on the order of 4 ?? 108 kg. This suggests that closed basin termini are sites for significant uranium accumulations and are, therefore, potential sites of uranium ore deposits. ?? 1979.

Evapotranspiration from the Lower Walker River Basin, West-Central Nevada, Water Years 2005-07

USGS Publications Warehouse

Allander, Kip K.; Smith, J. LaRue; Johnson, Michael J.

2009-01-01

Evapotranspiration is the ultimate path of outflow of nearly all water from the Lower Walker River basin. Walker Lake is the terminus of the topographically closed Walker River basin, and the lake level has been declining at an average rate of about 1.6 feet per year (ft/yr) since 1917. As a result of the declining lake level, dissolved-solids concentrations are increasingly threatening the fishery and ecosystem health of the lake. Uncertainties in the water budget components of the Lower Walker River basin led the U.S. Geological Survey, in cooperation with the Bureau of Reclamation, to undertake an investigation to refine estimates of the water budget. Evapotranspiration from the Lower Walker River basin represents a major component of this water budget. The specific objectives of this report are to provide estimates of total and net evapotranspiration for water years 2005-07 for areas in the Lower Walker River basin in which annual evapotranspiration exceeds annual precipitation, and to summarize these results for areas of similar vegetation and soil characteristics, hydrographic subareas, and Walker Lake and Weber Reservoir. The three hydrographic subareas include the area along Walker River north of Walker Lake, the area of and adjacent to Walker Lake, and the area south of Walker Lake. Areas of annual evapotranspiration exceeding annual precipitation were identified and mapped in the field and were further delineated using remote-sensing analysis. These areas were classified into 10 evapotranspiration units. A network of 11 evapotranspiration stations was operated in natural and agricultural vegetation and on Walker Lake. Measured evapotranspiration rates ranged from 0.5 ft/yr at a sparsely vegetated desert shrub site to 5.0 ft/yr from Walker Lake. The greatest evapotranspiration rate on land was 4.1 ft/yr at an irrigated alfalfa field, and the greatest rate for natural vegetation was 3.9 ft/yr in a riparian community along Walker River. At an evapotranspiration station in a saltcedar grove, measurements indicated a possible decrease in evapotranspiration of about 50 percent due to defoliation of the saltcedar by the saltcedar leaf beetle. Total evapotranspiration from the evapotranspiration units identified in the Lower Walker River basin was about 231,000 acre-feet per year (acre-ft/yr). Of this amount, about 45,000 acre-ft/yr originated from direct precipitation, resulting in net evapotranspiration of about 186,000 acre-ft/yr. More than 80 percent of net evapotranspiration in the Lower Walker River basin was through evaporation from Walker Lake. Total evaporation from Walker Lake was about 161,000 acre-ft/yr and net evaporation was about 149,000 acre-ft/yr. Some previous estimates of evaporation from Walker Lake based on water-budget analysis actually represent total evaporation minus ground-water inflow to the lake. Historical evaporation rates determined on the basis of water budget analysis were less than the evaporation rate measured directly during this study. The difference could represent ground-water inflow to Walker Lake of 16,000 to 26,000 acre-ft/yr or could indicate that ground-water inflow to Walker Lake is decreasing over time as the lake perimeter recedes.

Assessing the Effects of Water Rights Purchases on Dissolved Oxygen, Stream Temperatures, and Fish Habitat

NASA Astrophysics Data System (ADS)

Mouzon, N. R.; Null, S. E.

2014-12-01

Human impacts from land and water development have degraded water quality and altered the physical, chemical, and biological integrity of Nevada's Walker River. Reduced instream flows and increased nutrient concentrations affect native fish populations through warm daily stream temperatures and low nightly dissolved oxygen concentrations. Water rights purchases are being considered to maintain instream flows, improve water quality, and enhance habitat for native fish species, such as Lahontan cutthroat trout. This study uses the River Modeling System (RMSv4), an hourly, physically-based hydrodynamic and water quality model, to estimate streamflows, temperatures, and dissolved oxygen concentrations in the Walker River. We simulate thermal and dissolved oxygen changes from increased streamflow to prioritize the time periods and locations that water purchases most enhance native trout habitat. Stream temperatures and dissolved oxygen concentrations are proxies for trout habitat. Monitoring results indicate stream temperature and dissolved oxygen limitations generally exist in the 115 kilometers upstream of Walker Lake (about 37% of the study area) from approximately May through September, and this reach currently acts as a water quality barrier for fish passage.

Evidence of spatial and temporal slip partitioning in the northern Central Nevada Seismic Belt from ground-based imaging of offset landforms

NASA Astrophysics Data System (ADS)

Gold, P. O.; Cowgill, E.; Kreylos, O.

2010-12-01

Measurements derived from high-resolution terrestrial LiDAR (t-Lidar) surveys of landforms displaced during the 16 December 1954 Mw 6.8 Dixie Valley earthquake in central Nevada confirm the absence of historical strike slip north of latitude 39.5°N. This conclusion has implications for the effect of stress changes on the spatial and temporal evolution of the central Nevada seismic belt. The Dixie Valley fault is a low-angle, east-dipping, range-bounding normal fault located in the central-northern reach of the central Nevada seismic belt (CNSB), a ~N-S trending group of historical ruptures that may represent a migration of northwest trending right-lateral Pacific-North American plate motion into central Nevada. Migration of a component of right slip eastward from the eastern California shear zone/Walker lane to the CNSB is supported by the presence of pronounced right-lateral motion observed in most of the CNSB earthquakes south of the Dixie Valley fault and by GPS data spanning the CNSB. Such eastward migration and northward propagation of right-slip into the CNSB predicts a component of lateral slip on the Dixie Valley fault. However, landforms offsets have previously been reported to indicate only purely normal slip in the 1954 Dixie Valley event. To check the direction of motion during the Dixie Valley earthquake using higher precision methods than previously employed, we collected t-LiDAR data to quantify displacements of two well-preserved debris flow chutes separated along strike by ~10 km and at locations where the local fault strike diverges by >10° from the regional strike. Our highest confidence measurements yield a horizontal slip vector azimuth of ~107° at both sites, orthogonal to the average regional fault strike of ~17°. Thus, we find no compelling evidence for regional lateral motion in our other measurements. This result indicates that continued northward propagation of right lateral slip from its diffuse termination at the northern end of the 1954 Fairview Peak event, 4 minutes before the Dixie Valley event, and the Rainbow Mountain-Stillwater events six months earlier, must be accommodated by some other mechanism. We see several options for the spatial and temporal evolution of right slip propagation into the northern CNSB. 1) Lateral motion may be accommodated to the east by faults opposite the Dixie Valley fault along the base of Clan Alpine range, or to the west by faults at the western base of the Stillwater range-diffuse faults to the SW and SE of the Dixie Valley fault that also ruptured in 1954 accommodated right slip and could represent a west and/or east migration of lateral motion; 2) right lateral motion may activate an as yet unrecognized fault within the Dixie Valley; or 3) the Dixie Valley fault may be reactivated with a greater component of lateral slip in response to changes in stress, a phenomena that has been recognized on the Borrego Fault in northern Mexico between the penultimate event and the recent 4 April 2010 El Mayor-Cucapah earthquake.

Structure of the Mina Deflection in Mono Lake, CA: Inferences from Paleoseismology

NASA Astrophysics Data System (ADS)

Sangani, Radhika Chandrakant

Walker Lane, a zone of transcurrent faulting along the Sierran range front, is dominated by NNW trending normal faults. Within the Walker Lane, the Mina Deflection is a region of structural anomaly, where a significant component of regional displacement and seismicity is transferred from NNW-trending faults to ENE-trending faults of the Excelsior-Coledale domain. Geographically, the western boundary of the Mina Deflection lies along the western margin of Mono Basin. This is kinematically implied by the distributed tensional and shear stress in the NNW- and ENE- trending faults of the region. Transfer of strain from the NNW-trending, right-lateral oblique slip faults to the ENE-trending, primarily left-lateral faults is poorly understood. The nature of this transfer is complicated by the presence of the young volcanics of Mono Lake at the stepover bend. I undertook detailed study of the sub-km scale geometry and kinematics of the stepover bend, and its relation to nearby recent magmatic fluid flow within the Mono Lake. Fault orientations, slip rates and ages of most recent events allow for understanding strain transfer between faulting and volcanism. The results suggest that strain is transferred from the outer arc to the inner arc of the stepover bend. Within the inner arc, the magmatism on Paoha Island seems to have arisen from a sill-like intrusion. Furthermore, strain transfer is accomplished through sets of faults and fissures that variously act as large-scale Reidel shears and tension gashes allowing the migration of magmatic fluids from depth.

Recapitalizing Nuclear Weapons (Walker Paper, Number 8)

DTIC Science & Technology

2007-08-01

Sandia National Laboratories, with cam- puses in California and New Mexico), four production plants (the Pantex Plant in Amarillo, TX; the Y-12 Plant in...Oak Ridge, TN; the Kansas City Plant in Kansas City, MO; and the Savan- nah River Site in Savannah River, SC), and the Nevada Test Site. The fall...this infrastructure (e.g., closures of Rocky Flats, Mound, and Pinellas facilities). At the same time, investments in the remaining supporting

Similar and Contrasting Response of Rifting and Transtension in the Gulf of California and Walker Lane to Preceding Arc Magmatism

NASA Astrophysics Data System (ADS)

Henry, C. D.; Faulds, J. E.

2006-12-01

The Gulf of California (GC) and Walker Lane (WL) have undergone strikingly similar development with strike- slip faulting following initial extension. They differ significantly in the amount of Pacific-North American plate motion taken up by each: essentially all relative motion in the GC and ~25% in the WL. In both areas, ancestral arc magmatism preceded and probably focused deformation, perhaps because heating and/or hydration weakened the lithosphere. However, differences in migration of the Rivera (RTJ) and Mendocino triple junctions (MTJ) related to differences in the orientation of plate boundaries determined how strike-slip faulting developed. Abrupt southward jumps in the RTJ led to abrupt cessation of magmatism over arc lengths of as much as 1000 km and initiation of east-northeast extension within the future GC. The best known jump was at ~13 Ma, but an earlier jump occurred at ~18 Ma. Arc magmatism has been best documented in Baja California, Sonora, and Nayarit, although Baja constituted the most-trenchward fringe of the ancestral arc. New and published data indicate that Sinaloa underwent a similar history of arc magmatism. The greatest volume of the arc immediately preceding RTJ jumps was probably in mainland Mexico. Arc magmatism shut off following these jumps, extension began in the future GC, and strike-slip faulting either followed or accompanied extension in the GC. In contrast, the MTJ migrated progressively northward. New and published data indicate magmatism generally shut off coincident with this retreat, but distinct nodes or zones of magmatism, presumably unrelated to subduction, persisted or initiated after arc activity ceased. We have suggested that the WL has grown progressively northward, following the retreating arc, and that the northern WL is its youngest part. However, the timing of initiation of strike-slip faulting in most of the WL is poorly known and controversial. Testing our hypothesis requires determining initiation and magnitudes of total slip across different parts. Despite the progressive migration of the MTJ, arc magmatism ceased abruptly at the latitude of Lake Tahoe (39.2°) at about 3 Ma, and the southern end of the active Cascade arc jumped ~160 km northward to Lassen Peak (40.5°), where it remains. Geologic data indicate strike-slip faulting began between these two areas immediately following the end of arc magmatism. The southern Cascade arc is undergoing ~east-west extension, which was the case for the northern Walker Lane immediately before strike-slip faulting began. Further progression or steps in magmatism and strike-slip faulting will likely follow further northward migration of the MTJ.

FOP 2012 stop, Honey Lake fault, Doyle, CA

USGS Publications Warehouse

Gold, Ryan; Briggs, Richard W.; Crone, Anthony; Angster, Steve; Seitz, Gordon G.

2012-01-01

The Honey Lake fault system (HLFS) strikes north-northwestward across Long Valley near Doyle, CA and is part of a network of active, dextral strike-slip faults in the northern Walker Lane (Figure 1). Geologic investigations of a right-laterally offset terrace riser along the north bank of Long Valley Creek, which we refer to as site 1 (Figure 2), indicate a latest Quaternary slip rate of 1.1-2. 6 mm/yr [Wills and Borchardt, 1993] and 1.7 ± 0.6 mm/yr [Turner and others, 2008] (Table 1). These studies also document evidence of at least four post-6.8 ka surface-rupturing earthquakes at this site.

Evidence of varying magma chambers and magmatic evolutionary histories for the Table Mountain Formation in the Carson-Iceberg Wilderness region, Sonora Pass, California

NASA Astrophysics Data System (ADS)

Asami, R.; Putirka, K. D.; Pluhar, C. J.; Farner, M. J.; Torrez, G.; Shrum, B. L.; Jones, S.

2012-12-01

The Sonora Pass- Dardanelles region in the Carson- Iceberg Wilderness area is located in the central Sierra Nevada and home to the type section for latites (Slemmons, 1953), a volcanic rock that contains high potassium, clinopyroxene, and plagioclase phenocysts. Latite lavas and tuffs exposed in the Sonora Pass region originated from the sources in the eastern Sierra Nevada (Noble et al., 1974) where lavas flowed toward California's Great Valley, and were emplaced in stream valleys along the way, which are now inverted to form "table mountains", ergo the name "Table Mountain Latite" (TML) (Slemmons, 1966). Similarly high-K volcanic rocks of the same age are exposed at Grouse Meadows, which is just north of the Walker Lane Caldera east of Sonora Pass, and at the type section, between Red Peak and Bald Peak west of Sonora Pass. Latites lavas and tuffs in all three regions were analyzed for major oxides and trace elements with X-ray fluorescence spectrometry at California State University, Fresno. Analysis of three locations of (TML) at the type section show that they (Ransome, 1898), may have a different magmatic evolutionary history compared to other latites, exposed at Sonora Pass and Grouse Meadows, as the latter two show similar major oxide and trace element compositions. Most compelling is the contrast in the behavior of Al2O3 and CaO at the type section. Variation diagrams show that at the type section Al2O3 and CaO enrichment decreases with increasing amounts of MgO as fractional crystallization occurs. Conversely, at Sonora Peak and Grouse Meadows, CaO and Al2O3 concentrations mostly increase as MgO decreases with fractional crystallization. This contrasts shows that plagioclase was a major fractioning phase at the type section, but not at the other two localities. This suggests that the lava flows at the type section were erupted from a distinct set of magma chambers and vents that underwent a very distinct magmatic evolutionary history, perhaps involving fractionation at shallower depths compared to the Sonora Pass and Grouse Meadows flows, which appear to evolve by clinopyroxene fractionation. These contrasts in the pressures of crystal fractionation may be the result of contrasts in crustal structure or tectonic setting, an issue currently being investigated.

Collaborative modelling and integrated decision support system analysis of a developed terminal lake basin

USGS Publications Warehouse

Niswonger, Richard G.; Allander, Kip K.; Jeton, Anne E.

2014-01-01

A terminal lake basin in west-central Nevada, Walker Lake, has undergone drastic change over the past 90 yrs due to upstream water use for agriculture. Decreased inflows to the lake have resulted in 100 km2 decrease in lake surface area and a total loss of fisheries due to salinization. The ecologic health of Walker Lake is of great concern as the lake is a stopover point on the Pacific route for migratory birds from within and outside the United States. Stakeholders, water institutions, and scientists have engaged in collaborative modeling and the development of a decision support system that is being used to develop and analyze management change options to restore the lake. Here we use an integrated management and hydrologic model that relies on state-of-the-art simulation capabilities to evaluate the benefits of using integrated hydrologic models as components of a decision support system. Nonlinear feedbacks among climate, surface-water and groundwater exchanges, and water use present challenges for simulating realistic outcomes associated with management change. Integrated management and hydrologic modeling provides a means of simulating benefits associated with management change in the Walker River basin where drastic changes in the hydrologic landscape have taken place over the last century. Through the collaborative modeling process, stakeholder support is increasing and possibly leading to management change options that result in reductions in Walker Lake salt concentrations, as simulated by the decision support system.

Monitoring And Modeling Environmental Water Quality To Support Environmental Water Purchase Decision-making

NASA Astrophysics Data System (ADS)

Null, S. E.; Elmore, L.; Mouzon, N. R.; Wood, J. R.

2016-12-01

More than 25 million cubic meters (20,000 acre feet) of water has been purchased from willing agricultural sellers for environmental flows in Nevada's Walker River to improve riverine habitat and connectivity with downstream Walker Lake. Reduced instream flows limit native fish populations, like Lahontan cutthroat trout, through warm daily stream temperatures and low dissolved oxygen concentrations. Environmental water purchases maintain instream flows, although effects on water quality are more varied. We use multi-year water quality monitoring and physically-based hydrodynamic and water quality modeling to estimate streamflow, water temperature, and dissolved oxygen concentrations with alternative environmental water purchases. We simulate water temperature and dissolved oxygen changes from increased streamflow to prioritize the time periods and locations that environmental water purchases most enhance trout habitat as a function of water quality. Monitoring results indicate stream temperature and dissolved oxygen limitations generally exist in the 115 kilometers upstream of Walker Lake (about 37% of the study area) from approximately May through September, and this reach acts as a water quality barrier for fish passage. Model results indicate that low streamflows generally coincide with critically warm stream temperatures, water quality refugia exist on a tributary of the Walker River, and environmental water purchases may improve stream temperature and dissolved oxygen conditions for some reaches and seasons, especially in dry years and prolonged droughts. This research supports environmental water purchase decision-making and allows water purchase decisions to be prioritized with other river restoration alternatives.

Bouguer gravity anomaly and isostatic residual gravity maps of the Tonopah 1 degree by 2 degrees Quadrangle, central Nevada

USGS Publications Warehouse

Plouff, Donald

1992-01-01

A residual isostatic gravity map (sheet 2) was prepared so that the regional effect of isostatic compensation present on the Bouguer gravity anomaly map (sheet 1) would be minimized. Isostatic corrections based on the Airy-Heiskanen system (Heiskanen and Vening Meinesz, 1958, p. 135-137) were estimated by using 3-minute topographic digitization and applying the method of Jachens and Roberts (1981). Parameters selected for the isostatic model were 25 km for the normal crustal thickness at sea level, 2.67 g/cm3 for the density of the crust, and 0.4 g/cm3 for the contrast in density between the crust and the upper mantle. These parameters were selected so that the isostatic residual gravity map would be consistent with isostatic residual gravity maps of the adjacent Walker Lake quadrangle (Plouff, 1987) and the state of Nevada (Saltus, 1988c).

Predicting the Affects of Climate Change on Evapotranspiration and Agricultural Productivity of Semi-arid Basins

NASA Astrophysics Data System (ADS)

Peri, L.; Tyler, S. W.; Zheng, C.; Pohll, G. M.; Yao, Y.

2013-12-01

Many arid and semi-arid regions around the world are experiencing water shortages that have become increasingly problematic. Since the late 1800s, upstream diversions in Nevada's Walker River have delivered irrigation supply to the surrounding agricultural fields resulting in a dramatic water level decline of the terminal Walker Lake. Salinity has also increased because the only outflow from the lake is evaporation from the lake surface. The Heihe River basin of northwestern China, a similar semi-arid catchment, is also facing losses from evaporation of terminal locations, agricultural diversions and evapotranspiration (ET) of crops. Irrigated agriculture is now experiencing increased competition for use of diminishing water resources while a demand for ecological conservation continues to grow. It is important to understand how the existing agriculture in these regions will respond as climate changes. Predicting the affects of climate change on groundwater flow, surface water flow, ET and agricultural productivity of the Walker and Heihe River basins is essential for future conservation of water resources. ET estimates from remote sensing techniques can provide estimates of crop water consumption. By determining similarities of both hydrologic cycles, critical components missing in both systems can be determined and predictions of impacts of climate change and human management strategies can be assessed.

Color and 3D views of the Sierra Nevada mountains

NASA Technical Reports Server (NTRS)

2002-01-01

A stereo 'anaglyph' created using the nadir and 45.6-degree forward-viewing cameras provides a three-dimensional view of the scene when viewed with red/blue glasses. The red filter should be placed over your left eye. To facilitate the stereo viewing, the images have been oriented with north toward the left. Some prominent features are Mono Lake, in the center of the image; Walker Lake, to its left; and Lake Tahoe, near the lower left. This view of the Sierra Nevadas includes Yosemite, Kings Canyon, and Sequoia National Parks. Mount Whitney, the highest peak in the contiguous 48 states (elev. 14,495 feet), is visible near the righthand edge. Above it (to the east), the Owens Valley shows up prominently between the Sierra Nevada and Inyo ranges. Precipitation falling as rain or snow on the Sierras feeds numerous rivers flowing southwestward into the San Joaquin Valley. The abundant fields of this productive agricultural area can be seen along the lower right; a large number of reservoirs that supply water for crop irrigation are apparent in the western foothills of the Sierras. Urban areas in the valley appear as gray patches; among the California cities that are visible are Fresno, Merced, and Modesto.

Hydrologic and geologic characteristics of the Yucca Mountain site relevant to the performance of a potential repository: Day 1, Las Vegas, Nevada to Pahrump, Nevada: Stop 6A. Keane Wonder Spring and regional groundwater flow in the Death Valley region

USGS Publications Warehouse

Steinkampf, W.C.

2000-01-01

Yucca Mountain, located ~100 mi northwest of Las Vegas, Nevada, has been designated by Congress as a site to be characterized for a potential mined geologic repository for high-level radioactive waste. This field trip will examine the regional geologic and hydrologic setting for Yucca Mountain, as well as specific results of the site characterization program, The first day focuses on the regional seeing with emphasis on current and paleo hydrology, which are both of critical concern for predicting future performance of a potential repository. Morning stops will be in southern Nevada and afternoon stops will be in Death Valley. The second day will be spent at Yucca Mountain. The filed trip will visit the underground testing sites in the "Exploratory Studies Facility" and the "Busted Butte Unsaturated Zone Transport Field Test" plus several surface-based testing sites. Much of the work at the site has concentrated on studies of the unsaturated zone, and element of the hydrologic system that historically has received little attention. Discussions during the second day will comprise selected topics of Yucca Mountain geology, mic hazard in the Yucca Mountain area. Evening discussions will address modeling of regional groundwater flow, the geology and hydrology of Yucca Mountain to the performance of a potential repository. Day 3 will examine the geologic framework and hydrology of the Pahute Mesa-Oasis Valley Groundwater Basin and then will continue to Reno via Hawthorne, Nevada and the Walker Lake area.

Dissolved oxygen, stream temperature, and fish habitat response to environmental water purchases.

PubMed

Null, Sarah E; Mouzon, Nathaniel R; Elmore, Logan R

2017-07-15

Environmental water purchases are increasingly used for ecological protection. In Nevada's Walker Basin (western USA), environmental water purchases augment streamflow in the Walker River and increase lake elevation of terminal Walker Lake. However, water quality impairments like elevated stream temperatures and low dissolved oxygen concentrations also limit ecosystems and species, including federally-threatened Lahontan cutthroat trout. In this paper, we prioritize water volumes and locations that most enhance water quality for riverine habitat from potential environmental water rights purchases. We monitored and modeled streamflows, stream temperatures, and dissolved oxygen concentrations using River Modeling System, an hourly, physically-based hydrodynamic and water quality model. Modeled environmental water purchases ranged from average daily increases of 0.11-1.41 cubic meters per second (m 3 /s) during 2014 and 2015, two critically dry years. Results suggest that water purchases consistently cooled maximum daily stream temperatures and warmed nightly minimum temperatures. This prevented extremely low dissolved oxygen concentrations below 5.0 mg/L, but increased the duration of moderate conditions between 5.5 and 6.0 mg/L. Small water purchases less than approximately 0.71 m 3 /s per day had little benefit for Walker River habitat. Dissolved oxygen concentrations were affected by upstream environmental conditions, where suitable upstream water quality improved downstream conditions and vice versa. Overall, this study showed that critically dry water years degrade environmental water quality and habitat, but environmental water purchases of at least 0.71 m 3 /s were promising for river restoration. Published by Elsevier Ltd.

Recent state of stress change in the Walker Lane zone, western Basin and Range province, United States

NASA Astrophysics Data System (ADS)

Bellier, Olivier; Zoback, Mary Lou

1995-06-01

The NW to north-trending Walker Lane zone (WLZ) is located along the western boundary of the northern Basin and Range province with the Sierra Nevada. This zone is distinguished from the surrounding Basin and Range province on the basis of irregular topography and evidence for both normal and strike-slip Holocene faulting. Inversion of slip vectors from active faults, historic fault offsets, and earthquake focal mechanisms indicate two distinct Quaternary stress regimes within the WLZ, both of which are characterized by a consistent WNW σ3 axis; these are a normal faulting regime with a mean σ3 axis of N85°±9°W and a mean stress ratio (R value) (R=(σ2-σ1)/(σ3-σ1)) of 0.63-0.74 and a younger strike-slip faulting regime with a similar mean σ3 axis (N65° - 70°W) and R values ranging between ˜ 0.1 and 0.2. This younger regime is compatible with historic fault offsets and earthquake focal mechanisms. Both the extensional and strike-slip stress regimes reactivated inherited Mesozoic and Cenozoic structures and also produced new faults. The present-day strike-slip stress regime has produced strike-slip, normal oblique-slip, and normal dip-slip historic faulting. Previous workers have explained the complex interaction of active strike-slip, oblique, and normal faulting in the WLZ as a simple consequence of a single stress state with a consistent WNW σ3 axis and transitional between strike-slip and normal faulting (maximum horizontal stress approximately equal to vertical stress, or R ≈ 0 in both regimes) with minor local fluctuations. The slip data reported here support previous results from Owens Valley that suggest deformation within temporally distinct normal and strike-slip faulting stress regimes with a roughly constant WNW trending σ3 axis (Zoback, 1989). A recent change from a normal faulting to a strike-slip faulting stress regime is indicated by the crosscutting striae on faults in basalts <300,000 years old and is consistent with the dominantly strike-slip earthquake focal mechanisms and the youngest striae observed on faults in Plio-Quaternary deposits. Geologic control on the timing of the change is poor; it is impossible to determine if there has been a single recent absolute change or if there is, rather, an alternating or cyclical variation in stress magnitudes. Our slip data, in particular, the cross-cutting normal and strike-slip striae on the same fault plane, are inconsistent with postulated simple strain partitioning of deformation within a single regional stress field suggested for the WLZ by Wesnousky and Jones [1994]. The location of the WLZ between the deep-seated regional extension of the Basin and Range and the right-lateral strike-slip regional tectonics of the San Andreas fault zone is probably responsible for the complex interaction of tectonic regimes in this transition zone. In early to mid-Tertiary time the WLZ appears to have had a similarly complex deformational history, in this case as a back arc or intra-arc region, accommodating at least part of the right-lateral component of oblique convergence as well as a component of extension.

Ground Water Atlas of the United States: Segment 1, California, Nevada

USGS Publications Warehouse

Planert, Michael; Williams, John S.

1995-01-01

California and Nevada compose Segment 1 of the Ground Water Atlas of the United States. Segment 1 is a region of pronounced physiographic and climatic contrasts. From the Cascade Mountains and the Sierra Nevada of northern California, where precipitation is abundant, to the Great Basin in Nevada and the deserts of southern California, which have the most arid environments in the United States, few regions exhibit such a diversity of topography or environment. Since the discovery of gold in the mid-1800's, California has experienced a population, industrial, and agricultural boom unrivaled by that of any other State. Water needs in California are very large, and the State leads the United States in agricultural and municipal water use. The demand for water exceeds the natural water supply in many agricultural and nearly all urban areas. As a result, water is impounded by reservoirs in areas of surplus and transported to areas of scarcity by an extensive network of aqueducts. Unlike California, which has a relative abundance of water, development in Nevada has been limited by a scarcity of recoverable freshwater. The Truckee, the Carson, the Walker, the Humboldt, and the Colorado Rivers are the only perennial streams of significance in the State. The individual basin-fill aquifers, which together compose the largest known ground-water reserves, receive little annual recharge and are easily depleted. Nevada is sparsely populated, except for the Las Vegas, the Reno-Sparks, and the Carson City areas, which rely heavily on imported water for public supplies. Although important to the economy of Nevada, agriculture has not been developed to the same degree as in California due, in large part, to a scarcity of water. Some additional ground-water development might be possible in Nevada through prudent management of the basin-fill aquifers and increased utilization of ground water in the little-developed carbonate-rock aquifers that underlie the eastern one-half of the State. The potential problem of withdrawals in excess of natural recharge, however, will require careful management of ground-water withdrawals.

Channel Transmission Loss Studies During Ephemeral Flow Events: ER-5-3 Channel and Cambric Ditch, Nevada Test Site, Nye County, Nevada

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

J.J. Miller; S.A. Mizell; R.H. French

2005-10-01

Transmission losses along ephemeral channels are an important, yet poorly understood, aspect of rainfall-runoff prediction. Losses occur as flow infiltrates channel bed, banks, and floodplains. Estimating transmission losses in arid environments is difficult because of the variability of surficial geomorphic characteristics and infiltration capacities of soils and near-surface low-permeability geologic layers (e.g., calcrete). Transmission losses in ephemeral channels are nonlinear functions of discharge and time (Lane, 1972), and vary spatially along the channel reach and with soil antecedent moisture conditions (Sharma and Murthy, 1994). Rainfall-runoff models used to estimate peak discharge and runoff volume for flood hazard assessment are notmore » designed specifically for ephemeral channels, where transmission loss can be significant because of the available storage volume in channel soils. Accuracy of the flow routing and rainfall-runoff models is dependent on the transmission loss estimate. Transmission loss rate is the most uncertain parameter in flow routing through ephemeral channels. This research, sponsored by the U.S. Department of Energy, National Nuclear Security Administration (DOE/NNSA) and conducted at the Nevada Test Site (NTS), is designed to improve understanding of the impact of transmission loss on ephemeral flood modeling and compare various methodologies for predicting runoff from rainfall events. Various applications of this research to DOE projects include more site-specific accuracy in runoff prediction; possible reduction in size of flood mitigation structures at the NTS; and a better understanding of expected infiltration from runoff losses into landfill covers. Two channel transmission loss field experiments were performed on the NTS between 2001 and 2003: the first was conducted in the ER-5-3 channel (Miller et al., 2003), between March and June 2001, and the second was conducted in the Cambric Ditch (Mizell et al., 2005), between April and July 2003. Both studies used water discharged from unrelated drilling activities during well development and aquifer pump tests. Discharge measurements at several flumes located along the channels were used to directly measure transmission losses. Flume locations were chosen in relation to geomorphic surface types and ages, vegetative cover and types, subsurface indurated layers (calcrete), channel slopes, etc. Transmission losses were quantified using three different analysis methods. Method 1 uses Lane's Method (Lane, 1983) for estimating flood magnitude in ephemeral channels. Method 2 uses heat as a subsurface tracer for infiltration. Numerical modeling, using HYDRUS-2D (Simunek et al., 1999), a finite-element-based flow and transport code, was applied to estimate infiltration from soil temperature data. Method 3 uses hydraulic gradient and water content in a Darcy's Law approach (Freeze and Cherry, 1979) to calculate one-dimensional flow rates. Heat dissipation and water content data were collected for this analysis.« less

Preliminary Paleomagnetically Determined Vertical-Axis Rotations and their Relationship to Extensional Events of the Southern Walker Lane

NASA Astrophysics Data System (ADS)

Johnson, S.; Geissman, J. W.; Katopody, D. T.; Kerstetter, S. R.; Oldow, J. S.

2016-12-01

The northern part of the southern Walker Lane experienced three extensional events from the late Oligocene to the Holocene: 1) late Oligocene to early Miocene WNW and ENE trending half-grabens, 2) Late Miocene to early Pliocene high-magnitude extension on a low-angle normal fault, and 3) contemporary transtensional deformation that initiated at 4 Ma. Each of the extensional events controlled deposition of synextensional strata. What is less understood is the timing and magnitude of vertical axis rotation and its relationship to each of the three extensional events. As part of a recent and ongoing multidisciplinary study to better understand the complex nature and history of these extensional events we present preliminary paleomagnetic data from 55 sites in Miocene extrusive igneous rocks which record that clockwise vertical-axis rotation played a significant role in accommodating displacement in these systems. Recently refined stratigraphic, geochronologic, and structural controls have allowed the detailed paleomagnetic sampling required for this study. We seek to provide better constraints on timing, areal extent, and distribution of vertical axis rotation to answer how vertical axis rotation interacted with these extensional events. Consistent with past studies, we have recognized 20-30 degrees of clockwise vertical-axis rotation distributed heterogeneously throughout the study area. However, clockwise vertical-axis rotations are no longer occurring in this region as evidenced by modern geodetic velocity fields. The accommodation of displacement by vertical axis rotations in this region likely ceased by early Pliocene to late Miocene when the structural step-over migrated to the northwest to its present day manifestation in the Mina Deflection. Anisotropy of magnetic susceptibility (AMS), used as a proxy for flow direction in igneous extrusive rocks, provides evidence that at least one late Oligocene-early Miocene half-grabens acted as near-source depositional centers concurrent with extension.

Geophysical characterization of transtensional fault systems in the Eastern California Shear Zone-Walker Lane Belt

NASA Astrophysics Data System (ADS)

McGuire, M.; Keranen, K. M.; Stockli, D. F.; Feldman, J. D.; Keller, G. R.

2011-12-01

The Eastern California Shear Zone (ECSZ) and Walker Lane belt (WL) accommodate ~25% of plate motion between the North American and Pacific plates. Faults within the Mina deflection link the ECSZ and the WL, transferring strain from the Owens Valley and Death Valley-Fish Lake Valley fault systems to the transcurrent faults of the central Walker Lane. During the mid to late Miocene the majority of strain between these systems was transferred through the Silver Peak-Lone Mountain (SPLM) extensional complex via a shallowly dipping detachment. Strain transfer has since primarily migrated north to the Mina Deflection; however, high-angle faults bounding sedimentary basins and discrepancies between geodetic and geologic models indicate that the SPLM complex may still actively transfer a portion of the strain from the ECSZ to the WL on a younger set of faults. Establishing the pattern and amount of active strain transfer within the SPLM region is required for a full accounting of strain accommodation, and provides insight into strain partitioning at the basin scale within a broader transtensional zone. To map the active structures in and near Clayton Valley, within the SPLM region, we collected seismic reflection and refraction profiles and a dense grid of gravity readings that were merged with existing gravity data. The primary goals were to determine the geometry of the high-angle fault system, the amount and sense of offset along each fault set, connectivity of the faults, and the relationship of these faults to the Miocene detachment. Seismic reflection profiles imaged the high-angle basin-bounding normal faults and the detachment in both the footwall and hanging wall. The extensional basin is ~1 km deep, with a steep southeastern boundary, a gentle slope to the northwest, and a sharp boundary on the northwest side, suggestive of another fault system. Two subparallel dip-slip faults bound the southeast (deeper) basin margin with a large lateral velocity change (from ~2.0 km/sec in the basin fill to 4.5-5.5 km/sec in the footwall) across the basin-bounding normal fault system. Very fast (approaching 6.0 km/sec) basement underlies the basin fill. The residual gravity anomaly indicates that Clayton Valley is divided into a shallower northern basin, imaged by the seismic lines, and a deeper, more asymmetric southern basin. Faults within Clayton Valley are curvilinear in nature, similar to faults observed in other step-over systems (e.g., the Mina Deflection). Gravity profiles support the seismic reflection interpretation and indicate a high angle fault (>60 degrees) bounding the northern sub-basin on its southeast margin, with a shallower fault bounding it to the northwest. A basement high trends west-northwest and separates the northern and southern basins, and is likely bounded on its southern edge by a predominantly strike-slip fault crossing the valley. Much of the strain accommodated within the southern sub-basin appears to be transferred into southern Big Smoky Valley, northwest of Clayton Valley, via these dextral strike-slip faults that obliquely cross Clayton Valley.

MISR Sees the Sierra Nevadas in Stereo

NASA Technical Reports Server (NTRS)

2000-01-01

These MISR images of the Sierra Nevada mountains near the California-Nevada border were acquired on August 12, 2000 during Terra orbit 3472. On the left is an image from the vertical-viewing (nadir) camera. On the right is a stereo 'anaglyph' created using the nadir and 45.6-degree forward-viewing cameras, providing a three-dimensional view of the scene when viewed with red/blue glasses. The red filter should be placed over your left eye. To facilitate the stereo viewing, the images have been oriented with north toward the left.

Some prominent features are Mono Lake, in the center of the images; Walker Lake, to its left; and Lake Tahoe, near the lower left. This view of the Sierra Nevadas includes Yosemite, Kings Canyon, and Sequoia National Parks. Mount Whitney, the highest peak in the contiguous 48 states (elev. 14,495 feet), is visible near the righthand edge. Above it (to the east), the Owens Valley shows up prominently between the Sierra Nevada and Inyo ranges.

Precipitation falling as rain or snow on the Sierras feeds numerous rivers flowing southwestward into the San Joaquin Valley. The abundant fields of this productive agricultural area can be seen along the lower right; a large number of reservoirs that supply water for crop irrigation are apparent in the western foothills of the Sierras. Urban areas in the valley appear as gray patches; among the California cities that are visible are Fresno, Merced, and Modesto.

MISR was built and is managed by NASA's Jet Propulsion Laboratory, Pasadena, CA, for NASA's Office of Earth Science, Washington, DC. The Terra satellite is managed by NASA's Goddard Space Flight Center, Greenbelt, MD. JPL is a division of the California Institute of Technology.

Proposed Relocation of the 37th Tactical Fighter Wing and Other Tactical Force Structure Actions

DTIC Science & Technology

1991-05-09

Joseph M. Tonopah NV Merlino, Bernie Tonopah NV 3 Murphy, N. V. Tonopah NV Michols, Judith E. Tonopah NV Nye, Al Tonopah NV 3 Payne, Unda Tonopah NV...the iNavy’s weTher tFctca operate-bospeds Aof mor reqir e ient. The e iiatssinldtohe tosha ve 00m lsn per g h ou r ea an aflon tio w idr-treed, lo-rs...John B. Walker, Nevada State ClearinghoUSe Document R Kevin Von Finger, TX Document S Jim Fish, Public Lands Action Network, NM Document T Judith S

On the nature and dynamics of the seismogenetic systems of North California, USA: An analysis based on Non-Extensive Statistical Physics

NASA Astrophysics Data System (ADS)

Efstathiou, Angeliki; Tzanis, Andreas; Vallianatos, Filippos

2017-09-01

We examine the nature of the seismogenetic system in North California, USA, by searching for evidence of complexity and non-extensivity in the earthquake record. We attempt to determine whether earthquakes are generated by a self-excited Poisson process, in which case they obey Boltzmann-Gibbs thermodynamics, or by a Critical process, in which long-range interactions in non-equilibrium states are expected (correlation) and the thermodynamics deviate from the Boltzmann-Gibbs formalism. Emphasis is given to background seismicity since it is generally agreed that aftershock sequences comprise correlated sets. We use the complete and homogeneous earthquake catalogue published by the North California Earthquake Data Centre, in which aftershocks are either included, or have been removed by a stochastic declustering procedure. We examine multivariate cumulative frequency distributions of earthquake magnitudes, interevent time and interevent distance in the context of Non-Extensive Statistical Physics, which is a generalization of extensive Boltzmann-Gibbs thermodynamics to non-equilibrating (non-extensive) systems. Our results indicate that the seismogenetic systems of North California are generally sub-extensive complex and non-Poissonian. The background seismicity exhibits long-range interaction as evidenced by the overall increase of correlation observed by declustering the earthquake catalogues, as well as by the high correlation observed for earthquakes separated by long interevent distances. It is also important to emphasize that two subsystems with rather different properties appear to exist. The correlation observed along the Sierra Nevada Range - Walker Lane is quasi-stationary and indicates a Self-Organized Critical fault system. Conversely, the north segment of the San Andreas Fault exhibits changes in the level of correlation with reference to the large Loma Prieta event of 1989 and thus has attributes of Critical Point behaviour albeit without acceleration of seismic release rates. SOC appears to be a likely explanation of complexity mechanisms but since there are other ways by which complexity may emerge, additional work is required before assertive conclusions can be drawn.

Lg Attenuation Anisotropy Across the Western US

NASA Astrophysics Data System (ADS)

Phillips, W. S.; Rowe, C. A.; Stead, R. J.; Begnaud, M. L.

2017-12-01

The USArray has allowed us to map seismic attenuation of local and regional phases to unprecedented spatial extent and resolution. Following standard mantle Pn velocity anisotropy methods, we have incorporated azimuthal anisotropy into our tomographic inversion of high-frequency Lg amplitudes. The Lg is a crustal shear phase made up of many trapped modes, thus results can be considered to be crustal averages. Azimuthal anisotropy reduces residual variance by just over 10% for 1.5-3 Hz Lg. We observe a median anisotropic variation of 12%, and a high of 50% in the Salton Trough. Low attenuation (high-Q) directions run parallel to topographic fabric and major strike slip faults in tectonically active areas, and often run parallel to mantle shear wave splitting directions in stable regions. Tradeoffs are of concern, and synthetic tests show that elongated attenuation anomalies will produce anisotropy artifacts, but of factors 2-3 times lower than observations. In particular, the strength of a long, narrow high-Q anomaly will trade off with high-Q directions parallel to the long axis, while an elongated low-Q anomaly will trade off with high-Q directions perpendicular to the long axis. We observe an elongated low-Q anomaly associated with the Walker Lane; however, observed high-Q directions run parallel to the long axis of this anomaly, opposite to the tradeoff effect, supporting the anisotropic observation, and implying that the effect may be underestimated. Further, we observe an elongated high-Q anomaly associated with the Great Valley and Sierra Nevada that runs across the long axis, again opposite to the tradeoff effect. This study was performed using waveforms, event locations and phase picks made available by IRIS, NEIC and ANF, and processing was done using semi-automated means, thus this is a technique that can be applied quickly to study crustal anisotropy over large areas when appropriate station density is available.

Late Quaternary history of the Owens Valley fault zone, eastern California, and surface rupture associated with the 1872 earthquake

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

Beanland, S.; Clark, M.M.

1993-04-01

The right-lateral Owens Valley fault zone (OVFZ) in eastern California extends north about 100 km from near the northwest shore of Owens Lake to beyond Big Pine. It passes through Lone Pine near the eastern base of the Alabama Hills and follows the floor of Owens Valley northward to the Poverty Hills, where it steps 3 km to the left and continues northwest across Crater Mountain and through Big Pine. Data from one site suggest an average net slip rate for the OVFZ of 1.5 [+-] 1 mm/yr for the past 300 ky. Several other sites yield an average Holocenemore » net slip rate of 2 [+-] 1 mm/yr. The OVFZ apparently has experienced three major Holocene earthquakes. The minimum average recurrence interval is 5,000 years at the subsidiary Lone Pine fault, whereas it is 3,300 to 5,000 years elsewhere along the OVFZ. The prehistoric earthquakes are not dated, so an average recurrence interval need not apply. However, roughly equal (characteristic) displacement apparently happened during each Holocene earthquake. The Owens Valley fault zone accommodates some of the relative motion (dextral shear) between the North American and Pacific plates along a discrete structure. This shear occurs in the Walker Lane belt of normal and strike-slip faults within the mainly extensional Basin and Range Province. In Owens Valley displacement is partitioned between the OVFZ and the nearby, subparallel, and purely normal range-front faults of the Sierra Nevada. Compared to the OVFZ, these range-front normal faults are very discontinuous and have smaller Holocene slip rates of 0.1 to 0.8 mm/yr, dip slip. Contemporary activity on adjacent faults of such contrasting styles suggests large temporal fluctuations in the relative magnitudes of the maximum and intermediate principal stresses while the extension direction remains consistently east-west.« less

Shallow Seismic Reflection Study of Recently Active Fault Scarps, Mina Deflection, Western Nevada

NASA Astrophysics Data System (ADS)

Black, R. A.; Christie, M.; Tsoflias, G. P.; Stockli, D. F.

2006-12-01

During the spring and summer of 2006 University of Kansas geophysics students and faculty acquired shallow, high resolution seismic reflection data over actively deforming alluvial fans developing across the Emmigrant Peak (in Fish Lake Valley) and Queen Valley Faults in western Nevada. These normal faults represent a portion of the transition from the right-lateral deformation associated with the Walker Lane/Eastern California Shear Zone to the normal and left-lateral faulting of the Mina Deflection. Data were gathered over areas of recent high resolution geological mapping and limited trenching by KU students. An extensive GPR data grid was also acquired. The GPR results are reported in Christie, et al., 2006. The seismic data gathered in the spring included both walkaway tests and a short CMP test line. These data indicated that a very near-surface P-wave to S-wave conversion was taking place and that very high quality S-wave reflections were probably dominating shot records to over one second in time. CMP lines acquired during the summer utilized a 144 channel networked Geode system, single 28 hz geophones, and a 30.06 downhole rifle source. Receiver spacing was 0.5 m, source spacing 1.0m and CMP bin spacings were 0.25m for all lines. Surveying was performed using an RTK system which was also used to develop a concurrent high resolution DEM. A dip line of over 400m and a strike line over 100m in length were shot across the active fan scarp in Fish Lake Valley. Data processing is still underway. However, preliminary interpretation of common-offset gathers and brute stacks indicates very complex faulting and detailed stratigraphic information to depths of over 125m. Depth of information was actually limited by the 1024ms recording time. Several west-dipping normal faults downstep towards the basin. East-dipping antithetic normal faulting is extensive. Several distinctive stratigraphic packages are bound by the faults and apparent unconformitites. A CMP dip line was also run across a large active scarp in Queen Valley near Boundary Peak. Due to slope steepness and extensive boulder armoring shot and receiver locations had to be skipped within several meters of the actual scarp location. Initial structural and stratigraphic interpretations are similar to those in the Fish Lake Valley location. Overall the data prove that the actively deforming fans can be imaged in detail sufficient to perform structural and possibly seismic stratigraphic analysis within the upper one hundred meters of the fans, if not deeper.

Quantifying seepage using heat as a tracer in selected irrigation canals, Walker River Basin, Nevada, 2012 and 2013

USGS Publications Warehouse

Naranjo, Ramon C.; Smith, David W.

2016-11-16

The Walker River is an important source of water for western Nevada. The river provides water for agriculture and recharge to local aquifers used by several communities. Farmers began diverting water from the Walker River in the 1860s to support growing agricultural development. Over time, the reduced inflows into Walker Lake from upstream reservoirs and diversions have resulted in 170 feet of lake level decline and increased dissolved-solids concentrations to levels that threaten aquatic ecosystems, including survival of Lahonton cutthroat trout, a native species listed in the Endangered Species Act. Investigations of the water-budget components in the Walker River Basin have revealed uncertainty in the recharge to aquifers from irrigation canals. To address this need, the U.S. Geological Survey conducted an extensive field study from March 2012 through October 2013 to quantify seepage losses in selected canals in the Smith Valley, Mason Valley, and Walker Lake Valley irrigation areas.The seepage rates estimated for the 2012 and 2013 irrigation seasons in the Smith Valley transect sites (Saroni and Plymouth canals) ranged between 0.01 to 2.5 feet per day (ft/d) (0.01 to 0.68 cubic feet per second per mile [ft3/s-mi]). From 2012 to 2013, the average number of days the canals had flowing water decreased from 190 to 125 due to drier climate and lack of water available for diversion from the Walker River. The nearly 50-percent reductions in volumetric loss rates between 2012 and 2013 were associated with less than average diversions into canals from the Walker River and reductions in infiltration rates following routine canal maintenance.Models developed for the Saroni canal in 2012 were recalibrated in 2013 to evaluate changes in seepage as a result of siltation. Just prior to the 2012 irrigation season, nearly the entire length of the canal was cleared of vegetation and debris to improve flow conveyance. In 2013, following the first year of maintenance, a 90-percent reduction in seepage was observed at one of the transect sites. The removal of sediment-clogged layers during canal maintenance may have more profound effects on seepage rates beyond what was observed at the transect sites. The seepage rates for the Saroni canal in 2012 ranged from 0.02 to 1.6 ft/d (0.03 to 0.4 ft3/s-mi). The total seepage loss in the Saroni canal for the 2012 and 2013 irrigation seasons was estimated to be 1,100 and 590 acre-feet (acre-ft), respectively.Seepage rates on the Plymouth canal in Smith Valley in 2012 were among the lowest, ranging from 0.01 to 0.2 ft/d (0.01 to 0.1 ft3/s-mi). In 2013, the seepage rate on the Plymouth canal was similar to 2012; however, the volumetric loss was reduced by 50 percent due to the 50-percent reduction in number of canal flow days. Lower rates of seepage on the Plymouth canal for the 2012 and 2013 irrigation seasons were estimated to be 210 and 130 acre-ft, respectively.The seepage rates estimated for the 2012 and 2013 irrigation seasons in the Mason Valley transect sites (Fox, Mickey, and Campbell ditches) ranged from 0.1 to 3.3 ft/d (0.2 to 1.3 ft3/s-mi). The influence of water-table declines on seepage was observed at the Mickey and Campbell ditches. In 2012, the estimated seepage on the Mickey ditch was 1.6 ft/d during a period when the water-table altitude was at or above the canal altitude. Following extensive declines in the water table, the hydraulic gradient increased between the canal and the shallow aquifer, thereby increasing the seepage rates to 3.2 ft/d in 2013. During the period of hydraulic disconnection, seepage rates increased to 9.5 ft/d during intermittent periods of canal flow. For the Mickey ditch, the seepage loss in 2013 was 1.5 times the rate estimated in 2012 despite the canal having 45 days less flow. Similarly, the Campbell ditch seepage loss increased slightly from 660 to 700 acre-ft, a factor of 1.1, with 49 days less flow. The seepage loss for the Fox ditch did not exhibit significant year to year variability. The annual seepage loss estimated for 2012 and 2013 in the Fox ditch was 2,100 and 2,200 acre-ft, respectively.The seepage rates estimated for the 2013 irrigation season in the Walker Lake Valley transect sites (Schurz Lateral Canals 1A and 2A, and Canal 2) ranged from 0.7 to 0.9 ft/d (0.4 to 1.3 ft3/s-mi). In Walker Lake Valley, diversions into Lateral Canals 1A and 2A during the 2013 irrigation season were highly intermittent, a characteristic common of lateral diversions. The annual estimated seepage loss in Walker Lake Valley ranged between 50 and 725 acre-ft among the transect sites.

Floods of November-December 1950 in western Nevada

USGS Publications Warehouse

Wells, J.V.B.

1954-01-01

Record-breaking floods in the Walker, Carson, and Truckee River basins during November and December 1950 resulted from a rapid sequence of storms and unseasonably high temperatures that melted most of the early snow cover. During the period November 13 to December 8, 1950, total precipitation ranged from about 5 inches at the foot of the Sierra Nevada in Nevada to about 30 inches at the crest in California, near the California-Nevada State line. About half of this total occurred during the period November 16-21. The resulting floods were the greatest in more than 50 years of record. The highest discharge occurred on Truckee River where the greatest damage potential exists?in the urban area of Reno and Sparks. Notable rates of discharge were 19,900 cfs, or 36.1 cfs per square mile, from 551 square miles in Truckee River at Reno, Nev.; 7,010 cfs, or 212 cfs per square mile, from 33 square miles in Little Truckee River near Hobart Mills, Calif.; and 3,570 cfs, or 119 cfs per square mile, from 30 square miles in East Fork Carson River near Markleeville, Calif. The estimate of damages compiled by the Corps of Engineers total $4,360,000 for the area; $1,982,000 of this was for Reno. Two deaths were reported. The American Red Cross assisted about 200 persons, at an expenditure of about $7,500. Federal aid for city and county rehabilitation in Nevada totaled $75,000. This report contains records of stage and discharge at 20 gaging stations and contents of 2 reservoirs, and a summary of peak discharges at 23 points within or adjacent to the flood area. The report contains also a discussion of the storms and floods, a section on meteorology prepared by the Weather Bureau, and a brief discussion of previous floods.

The Gabbs Valley, Nevada, geothermal prospect: Exploring for a potential blind geothermal resource

NASA Astrophysics Data System (ADS)

Payne, J.; Bell, J. W.; Calvin, W. M.

2012-12-01

The Gabbs Valley prospect in west-central Nevada is a potential blind geothermal resource system. Possible structural controls on this system were investigated using high-resolution LiDAR, low sun-angle aerial (LSA) photography, exploratory fault trenching and a shallow temperature survey. Active Holocene faults have previously been identified at 37 geothermal systems with indication of temperatures greater than 100° C in the western Nevada region. Active fault controls in Gabbs Valley include both Holocene and historical structures. Two historical earthquakes occurring in 1932 and 1954 have overlapping surface rupture patterns in Gabbs Valley. Three active fault systems identified through LSA and LiDAR mapping have characteristics of Basin and Range normal faulting and Walker Lane oblique dextral faulting. The East Monte Cristo Mountains fault zone is an 8.5 km long continuous NNE striking, discrete fault with roughly 0.5 m right-normal historic motion and 3 m vertical Quaternary separation. The Phillips Wash fault zone is an 8.2 km long distributed fault system striking NE to N, with Quaternary fault scarps of 1-3 m vertical separation and a 500 m wide graben adjacent to the Cobble Cuesta anticline. This fault displays ponded drainages, an offset terrace riser and right stepping en echelon fault patterns suggestive of left lateral offset, and fault trenching exposed non-matching stratigraphy typical of a significant component of lateral offset. The unnamed faults of Gabbs Valley are a 10.6 km long system of normal faults striking NNE and Quaternary scarps are up to 4 m high. These normal faults largely do not have historic surface rupture, but a small segment of 1932 rupture has been identified. A shallow (2 m deep) temperature survey of 80 points covering roughly 65 square kilometers was completed. Data were collected over approximately 2 months, and continual base station temperature measurements were used to seasonally correct temperature measurements. A 2.5 km long temperature anomaly greater than 3° C above background temperatures forms west-northwest trending zone between terminations of the Phillips Wash fault zone and unnamed faults of Gabbs Valley to the south. Rupture segments of two young active faults bracket the temperature anomaly. The temperature anomaly may be due to several possible causes. 1. Increases in stress near the rupture segments or tip-lines of these faults, or where multiple fault splays exist, can increase fault permeability. The un-ruptured segments of these faults may be controlling the location of the Gabbs Valley thermal anomaly between ruptured segments of the 1932 Cedar Mountain and 1954 Fairview Peak earthquakes. 2. Numerous unnamed normal faults may interact and the hanging wall of these faults is hosting the thermal anomaly. The size and extent of the anomaly may be due to its proximity to a flat playa and not the direct location of the shallow heat anomaly. 3. The linear northwest nature of the thermal anomaly may reflect a hydrologic barrier in the subsurface controlling where heated fluids rise. A concealed NW- striking fault is possible, but has not been identified in previous studies or in the LiDAR or LSA fault mapping.

The 2011 Hawthorne, Nevada, Earthquake Sequence; Shallow Normal Faulting

NASA Astrophysics Data System (ADS)

Smith, K. D.; Johnson, C.; Davies, J. A.; Agbaje, T.; Knezevic Antonijevic, S.; Kent, G.

2011-12-01

An energetic sequence of shallow earthquakes that began in early March 2011 in western Nevada, near the community of Hawthorne, has slowly decreased in intensity through mid-2011. To date about 1300 reviewed earthquake locations have been compiled; we have computed moment tensors for the larger earthquakes and have developed a set of high-precision locations for all reviewed events. The sequence to date has included over 50 earthquakes ML 3 and larger with the largest at Mw 4.6. Three 6-channel portable stations configured with broadband sensors and accelerometers were installed by April 20. Data from the portable instruments is telemetered through NSL's microwave backbone to Reno where it is integrated with regional network data for real-time notifications, ShakeMaps, and routine event analysis. The data is provided in real-time to NEIC, CISN and the IRIS DMC. The sequence is located in a remote area about 15-20 km southwest of Hawthorne in the footwall block of the Wassuk Range fault system. An initial concern was that the sequence might be associated with volcanic processes due to the proximity of late Quaternary volcanic flows; there have been no volcanic signatures observed in near source seismograms. An additional concern, as the sequence has proceeded, was a clear progression eastward toward the Wassuk Range front fault. The east dipping range bounding fault is capable of M 7+ events, and poses a significant hazard to the community of Hawthorne and local military facilities. The Hawthorne Army Depot is an ordinance storage facility and the nation's storage site for surplus mercury. The sequence is within what has been termed the 'Mina Deflection' of the Central Walker Lane Belt. Faulting along the Whiskey Flat section of the Wassuk front fault would be primarily down-to-the-east, with an E-W extension direction; moment tensors for the 2011 earthquake show a range of extension directions from E-W to NW-SE, suggesting a possible dextral component to the Wassuk Range front fault at this latitude. At least two faults have been imaged within the sequence; these structures are at shallow depth (3-6 km), strike NE, and dip ~NW. Prior to temporary station installation event depths were poorly constrained, with the nearest network station 25 km from the source area. Early sequence moment tensor solutions show depths are on the order of 2-6 km and locations using the near source stations also confirm the shallow depths of the Hawthorne sequence. S-P times of 0.5 sec and less have been observed on a near-source station, illustrating extremely shallow source depths for some events. Along with the 2011 Hawthorne activity, very shallow depths in Nevada have been observed from near source stations in the 2008 west Reno earthquake sequence (primarily strike-slip faulting; main shock Mw 5.0) and the 1993 Rock Valley sequence in southern NNSS (strike-slip faulting; main shock Mw 4.0). These shallow sequences tend to include high rates of low magnitude earthquakes continuing over several months duration.

Young (<7 Ma) gold deposits and active geothermal systems of the Great Basin: Enigmas, questions, and exploration potential

USGS Publications Warehouse

Coolbaugh, Mark F.; Vikre, Peter G.; Faulds, James E.

2011-01-01

Young gold systems in the Great Basin (£ 7 Ma), though not as well studied as their older counterparts, comprise a rapidly growing and in some ways controversial group. The gold inventory for these systems has more than doubled in the last 5 years from roughly 370 tonnes (12 Moz) to 890 tonnes (29 Moz). Although these deposits are characterized by low grades, tonnages can be high and stripping ratios low, and they have been mined profitably, as exemplified by Florida Canyon and Hycroft. Active geothermal systems in the Great Basin also comprise a rapidly growing group, as evidenced by a number of recent discoveries of geothermal groundwater and a more than 50% increase in electricity production capacity from these systems in the last 5 years. Many young gold deposits are closely associated with active geothermal systems, suggesting that gold deposits may be forming today in the Great Basin. Measured or estimated geothermal reservoir temperatures commonly approach or exceed 200∞C, and other characteristics and processes (advanced argillic caps, hydrothermal eruption breccias) of these young deposits resemble those of nearby Tertiary precious metal deposits. Nonetheless, many young gold systems, especially in Nevada, are not associated with coeval igneous rocks. Similarly, almost all electricity-grade geothermal systems in Nevada are not associated with Quaternary silicic volcanic rocks, and have lower temperature gradients, lower 3He/4He ratios, and lower dissolved trace element concentrations than most magmatic-heated geothermal systems elsewhere in the world. The increasing economic significance of young gold deposits and active geothermal systems justifies more research to better understand their origins, particularly because in some aspects they remain enigmatic and controversial. Are young gold deposits in Nevada truly amagmatic, or have they received metal and fluid contributions from magmas deeper within the crust? Has gold in these deposits been remobilized from older gold mineralization? Current research is investigating these and other questions to improve our genetic understanding of these young gold systems, which in turn can lead to improved exploration targeting. The recent rapid growth in resources for both young gold deposits and geothermal systems underscores their underdeveloped exploration potential. Even though many young gold deposits exhibit relatively shallow hot-springs-style mineralization, their young age may preclude exposure by erosion. Uplift along active normal faults has exposed some deposits (e.g., Florida Canyon, Dixie Comstock, Wind Mountain), but in other areas, such as the Walker Lane, where strike-slip faulting is prevalent, the opportunities for exposure can be limited. Many active geothermal systems are also concealed below the surface in that hot springs or steam vents may be absent above areas of thermal groundwater.With sources of energy to support mine production becoming more problematic, the potential advantages of simultaneously exploring for young gold deposits and spatially associated geothermal systems are becoming more apparent. Exploration methods recently proven effective in geothermal exploration that can be adapted to gold exploration include temperature surveys, hyperspectral remote sensing, geophysical surveys, water analyses, and detailed mapping of geothermal-related features and related fault systems.

Unraveling the volcanic and post-volcanic history at Upsal Hogback, Fallon, Nevada, USA

NASA Astrophysics Data System (ADS)

Anderson, E.; Cousens, B.

2013-12-01

Upsal Hogback is a < 25 ka phreatomagmatic volcanic center situated near Fallon, Nevada. The volcano neighbors two other young volcanic complexes: the Holocene Soda Lakes maars and Rattlesnake Hill, a ~ 1 Ma volcanic neck (Shevenell et al., 2005). These volcanoes lie on the transition between the Sierra Nevada and the Basin and Range province, as well as on the edge of the Walker Lane. Upsal Hogback includes two to four vents, fewer than mapped by Morrison (1964), and can be divided into north (one vent) and south (three potential vents) complexes. The vents all produced phreatomagmatic eruptions resulting in tuff rings composed primarily of coarse, indurated lapilli tuffs with abundant volcanic bombs. Ash tuffs are infrequent, as are structures such as crossbedding. The bombs and lapilli include olivine and plagioclase phenocrysts. The basalts are alkaline and have intraplate-type normalized incompatible element patterns. Both complexes are enriched in LREE compared to HREE, though the north complex overall has lower concentrations of the REE. The flat HREE pattern is indicative of spinel peridotite mantle source. Epsilon Nd values for the north complex are +2.50+/-0.02 and for the south complex are +2.83+/-0.02. The magmas appear to have an enriched asthenospheric mantle source. Bomb samples show that eruptions from the two complexes are geochemically distinguishable both in major and trace elements, suggesting that the two complexes tapped different magma types during eruptions that likely occurred at slightly different times. The proximity of Upsal Hogback to Fallon makes constraining its age important to characterize the hazard to the city. It lies above the Wono ash bed, dated at 25,000 years (Fultz et al., 1983), and tufa deposited over the edifice is dated at 11,100 +/- 100 and 8,600 +/- 200 years (Benson et al., 1992; Broecker and Kaufman, 1965). 40Ar/39Ar total gas age by Shevenell et al. (2005) dated the volcano at 0.60 +/- 0.09 Ma, but with no plateau or isochron, and is thus unreliable. The ash bed and tufa ages show that the eruptions would have occurred during the late history of glacial Lake Lahontan. The evidence for primarily subaerial or shallow subaqueous eruptions, including abundant bomb sags and armored lapilli, demonstrate that most of the volcanism occurred during a low stand in lake level history. Some upper tuff units have been heavily altered to palagonite, which establishes that there was substantial water present during some of the later eruptions. The upper edifice has been significantly modified by slumping of the lapilli tuffs during or after of the eruptions, as indicated by the wildly varying strikes and dips found in adjacent lapilli tuff blocks. Lake Lahontan has substantially altered the morphology of the volcano through wave action and shoreline erosion, as well as tufa deposition, since the eruption and emplacement of the tuffs. The edifice has gone through significant changes during its post-eruptive history that mask many of its original features; it was possible that it was a tuff cone that has been modified into a tuff ring.

Analysis of pedestrian dynamics in counter flow via an extended lattice gas model.

PubMed

Kuang, Hua; Li, Xingli; Song, Tao; Dai, Shiqiang

2008-12-01

The modeling of human behavior is an important approach to reproduce realistic phenomena for pedestrian flow. In this paper, an extended lattice gas model is proposed to simulate pedestrian counter flow under the open boundary conditions by considering the human subconscious behavior and different maximum velocities. The simulation results show that the presented model can capture some essential features of pedestrian counter flows, such as lane formation, segregation effect, and phase separation at higher densities. In particular, an interesting feature that the faster walkers overtake the slower ones and then form a narrow-sparse walkway near the central partition line is discovered. The phase diagram comparison and analysis show that the subconscious behavior plays a key role in reducing the occurrence of jam cluster. The effects of the symmetrical and asymmetrical injection rate, different partition lines, and different combinations of maximum velocities on pedestrian flow are investigated. An important conclusion is that it is needless to separate faster and slower pedestrians in the same direction by a partition line. Furthermore, the increase of the number of faster walkers does not always benefit the counter flow in all situations. It depends on the magnitude and asymmetry of injection rate. And at larger maximum velocity, the obtained critical transition point corresponding to the maximum flow rate of the fundamental diagram is in good agreement with the empirical results.

Subsurface Constraints on Late Cenozoic Basin Geometry in Northern Fish Lake Valley and Displacement Transfer Along the Northern Fish Lake Valley Fault Zone, Western Nevada

NASA Astrophysics Data System (ADS)

Mueller, N.; Kerstetter, S. R.; Katopody, D. T.; Oldow, J. S.

2016-12-01

The NW-striking, right-oblique Fish Lake Valley fault zone (FLVFZ) forms the northern segment of the longest active structure in the western Great Basin; the Death Valley - Furnace Creek - Fish Lake Valley fault system. Since the mid-Miocene, 50 km of right-lateral displacement is documented on the southern FLVFZ and much of that displacement was and is transferred east and north on active WNW left-lateral faults. Prior to the Pliocene, displacement was transferred east and north on a low-angle detachment. Displacement on the northern part of the FLVFZ continues and is transferred to a fanned array of splays striking (west to east) WNW, NNW, ENE and NNE. To determine the displacement budget on these structures, we conducted a gravity survey to determine subsurface basin morphology and its relation to active faults. Over 2450 stations were collected and combined with existing PACES and proprietary data for a total of 3388 stations. The data were terrain corrected and reduced to a 2.67 g/cm3 density to produce a residual complete Bouguer anomaly. The eastern part of northern Fish Lake Valley is underlain by several prominent gravity lows forming several sub-basins with maximum RCBA values ranging from -24 to -28 mGals. The RCBA was inverted for depth using Geosoft Oasis Montaj GM-SYS 3D modeling software. Density values for the inversion were constrained by lithologic and density logs from wells that penetrate the entire Cenozoic section into the Paleozoic basement. Best fitting gravity measurements taken at the wellheads yielded an effective density of 2.4 g/cm3 for the basin fill. Modeled basement depths range between 2.1 to 3 km. The sub-basins form an arc opening to the NW and are bounded by ENE and NNE faults in the south and NS to NNW in the north. At the northern end of the valley, the faults merge with ENE left-lateral strike slip faults of the Mina deflection, which carries displacement to NW dextral strike-slip faults of the central Walker Lane.

Velocity model calibration as a tool to improve regional wave moment tensors: Application to the Basin and Range Province

NASA Astrophysics Data System (ADS)

Ichinose, G. A.

2006-12-01

Many scientific issues for the Basin and Range Province (BRP) remain unsettled including structural evolution, strain rates, slip partitioning and earthquake source physics. A catalog of earthquake source parameters including locations and moment tensors is the basis for tectonic and geophysical study. New instrumentation from the Advance National Seismic System, EarthScope Plate Boundary Observatory, Bigfoot and US-Array brings the opportunity for high quality research; therefore, a catalog is an underlying foundation for examining the BRP. We are continuing to generate a moment tensor catalog for the BRP (Mw<3.5) using long-period regional waves spanning back to 1990. Iterative waveform inversion method (e.g., Nolet et al., 1986, Randell, 1994) is used to calibrate the BRP velocity and density structure using two northern and southern BRP earthquakes. The calibrated models generate realistic synthetics for (f<0.5Hz) with ~50-80% variance reduction. We averaged all path specific models to construct a 1-D BRP community background model. The crust is relatively simple between 5-20km (~6.12km/s) and there is a strong velocity gradient in the upper 5- km. There are lower velocities in the upper crust but higher velocities in the mid-crust for the Sierra Nevada paths relative to BRP. There is also a lower crust high-velocity anomaly near Battle Mountain and Elko that is faster by ~5% and may indicate a wider area of under-plating by basaltic magmas. There are significant low velocity zones in the upper and mid crust mainly across the Walker Lane Belt that may indicate the presence of fluids. We are continuing to work on assessing the performance of these newly calibrated models in improving the estimation of moment tensors down to lower magnitudes and mapping out holes in the seismic network which can be filled to improve moment tensor catalog. We also are looking at how these models work at locating earthquakes and comparing synthetics with those computed from models constrained from different data including refraction, surface wave dispersion, and travel-time tomography.

Lake-level variation in the Lahontan basin for the past 50,000 years

USGS Publications Warehouse

Benson, L.V.; Thompson, R.S.

1987-01-01

Selected radiocarbon data on surficial materials from the Lahontan basin, Nevada and California, provide a chronology of lake-level variation for the past 50,000 yr. A moderate-sized lake connected three western Lahontan subbasins (the Smoke Creek-Black Rock Desert subbasin, the Pyramid Lake subbasin, and the Winnemucca Dry Lake subbasin) from about 45,000 to 16,500 yr B.P. Between 50,000 and 45,000 yr B.P., Walker Lake rose to its sill level in Adrian Valley and spilled to the Carson Desert subbasin. By 20,000 yr B.P., lake level in the western Lahontan subbasins had risen to about 1265 m above sea level, where it remained for 3500 yr. By 16,000 yr B.P., lake level in the western Lahontan subbasins had fallen to 1240 m. This recession appears synchronous with a desiccation of Walker Lake; however, whether the Walker Lake desiccation resulted from climate change or from diversion of the Walker River is not known. From about 15,000 to 13,500 yr B.P., lake level rapidly rose, so that Lake Lahontan was a single body of water by 14,000 yr B.P. The lake appears to have reached a maximum highstand altitude of 1330 m by 13,500 yr B.P., a condition that persisted until about 12,500 yr B.P., at which time lake level fell ???100 m. No data exist that indicate the level of lakes in the various subbasins between 12,000 and 10,000 yr B.P. During the Holocene, the Lahontan basin was the site of shallow lakes, with many subbasins being the site of one or more periods of desiccation. The shape of the lake-level curve for the three western subbasins indicates that past changes in the hydrologic balance (and hence climate) of the Lahontan basin were large in magnitude and took place in a rapid step-like manner. The rapid changes in lake level are hypothesized to have resulted from changes in the mean position of the jet stream, as it was forced north or south by the changing size and shape of the continental ice sheet. ?? 1987.

A relation between landsat digital numbers, surface reflectance, and the cosine of the solar zenith angle

USGS Publications Warehouse

Kowalik, William S.; Marsh, Stuart E.; Lyon, Ronald J. P.

1982-01-01

A method for estimating the reflectance of ground sites from satellite radiance data is proposed and tested. The method uses the known ground reflectance from several sites and satellite data gathered over a wide range of solar zenith angles. The method was tested on each of 10 different Landsat images using 10 small sites in the Walker Lake, Nevada area. Plots of raw Landsat digital numbers (DNs) versus the cosine of the solar zenith angle (cos Z) for the the test areas are linear, and the average correlation coefficients of the data for Landsat bands 4, 5, 6, and 7 are 0.94, 0.93, 0.94, and 0.94, respectively. Ground reflectance values for the 10 sites are proportional to the slope of the DN versus cos Z relation at each site. The slope of the DN versus cos Z relation for seven additional sites in Nevada and California were used to estimate the ground reflectances of those sites. The estimates for nearby sites are in error by an average of 1.2% and more distant sites are in error by 5.1%. The method can successfully estimate the reflectance of sites outside the original scene, but extrapolation of the reflectance estimation equations to other areas may violate assumptions of atmospheric homogeneity.

Early impacts of biological control on canopy cover and water use of the invasive saltcedar tree (Tamarix spp.) in western Nevada, USA

USGS Publications Warehouse

Pattison, R.R.; D'Antonio, C. M.; Dudley, T.L.; Allander, K.K.; Rice, B.

2011-01-01

The success of biological control programs is rarely assessed beyond population level impacts on the target organism. The question of whether a biological control agent can either partially or completely restore ecosystem services independent of population level control is therefore still open to discussion. Using observational and experimental approaches, we investigated the ability of the saltcedar leaf beetle [Diorhabda carinulata (Brull??) (Coleoptera: Chrysomelidae)] to reduce the water use of saltcedar trees (Tamarix ramosissima Ledeb.) in two sites (Humboldt and Walker Rivers) in Nevada, USA. At these sites D. carinulata defoliated the majority of trees within 25 and 9 km, respectively, of the release location within 3 years. At the Humboldt site, D. carinulata reduced the canopy cover of trees adjacent to the release location by >90%. At a location 4 km away during the first year of defoliation, D. carinulata reduced peak (August) stem water use by 50-70% and stand transpiration (July to late September) by 75% (P = 0. 052). There was, however, no reduction in stem water use and stand transpiration during the second year of defoliation due to reduced beetle abundances at that location. At the Walker site, we measured stand evapotranspiration (ET) in the center of a large saltcedar stand and found that ET was highest immediately prior to D. carinulata arrival, dropped dramatically with defoliation, and remained low through the subsequent 2 years of the study. In contrast, near the perimeter of the stand, D. carinulata did not reduce sap flow, partly because of low rates of defoliation but also because of increased water use per unit leaf area in response to defoliation. Taken together, our results provide evidence that in the early stages of population expansion D. carinulata can lead to substantial declines in saltcedar water use. The extent of these declines varies spatially and temporally and is dependent on saltcedar compensatory responses along with D. carinulata population dynamics and patterns of dispersal. ?? 2010 Springer-Verlag (outside the USA).

Mega-rings Surrounding Timber Mountain Nested Calderas, Geophysical Anomalies: Rethinking Structure and Volcanism Near Yucca Mountain (YM), Nevada

NASA Astrophysics Data System (ADS)

Tynan, M. C.; Smith, K. D.; Savino, J. M.; Vogt, T. J.

2004-12-01

Observed regional mega-rings define a zone ˜80-100 km in diameter centered on Timber Mountain (TM). The mega-rings encompass known smaller rhyolitic nested Miocene calderas ( ˜11-15 my, < 10 km circular to elliptical small "rings") and later stage basaltic features (< 11 my, small flows, cones, dikes) in the Southwest Nevada Volcanic Field. Miocene rhyolitic calderas cluster within the central area and on the outer margin of the interpreted larger mega-ring complex. The mega-ring interpretation is consistent with observations of regional physiography, tomographic images, seismicity patterns, and structural relationships. Mega-rings consist of arcuate faulted blocks with deformation (some remain active structures) patterns showing a genetic relationship to the TM volcanic system; they appear to be spatially associated and temporally correlated with Miocene volcanism and two geophysically identified crustal/upper mantle features. A 50+ km diameter pipe-like high velocity anomaly extends from crustal depth to over 200 km beneath TM (evidence for 400km depth to NE). The pipe is located between two ˜100 km sub-parallel N/S linear trends of small-magnitude earthquake activity, one extending through the central NV Test Site, and a second located near Beatty, NV. Neither the kinematics nor relational mechanism of 100km seismically active N/S linear zones, pipe, and mega-rings are understood. Interpreted mega-rings are: 1) Similar in size to larger terrestrial volcanic complexes (e.g., Yellowstone, Indonesia's Toba system); 2) Located in the region of structural transition from the Mohave block to the south, N/S Basin and Range features to the north, Walker Lane to the NW, and the Las Vegas Valley shear zone to the SE; 3) Associated with the two seismically active zones (similar to other caldera fault-bounded sags), the mantle high velocity feature, and possibly a regional bouguer gravity anomaly; 4) Nearly coincident with area hydrologic basins and sub-basins; 5) Similar to features described from terrestrial and planetary caldera-collapse studies, and as modeled in laboratory scaled investigations (ice melt, balloon/sand). Post Mid-Miocene basalts commonly occur within or adjacent to the older rhyolitic caldera moats; other basaltic material occurs marginal to both the outer rings of the interpreted mega-ring system and high velocity pipe. The YM repository may be situated in an isolated structural setting within the mega-ring system; basaltic materials are absent in the block for over 11my for geologic reasons. The mega-ring model may better explain YM area structures (Highway 95 fault), tectonism, and volcanism. Coincident physiographic, geologic, and geophysical features associated with the mega-rings feature, and temporal characteristics of regional seismicity and volcanism suggest the need to critically re-assess regional scale and YM tectonic, seismotectonic, and volcanic models.

Hydrologic and geologic characteristics of the Yucca Mountain site relevant to the performance of a potential repository

USGS Publications Warehouse

Levich, R.A.; Linden, R.M.; Patterson, R.L.; Stuckless, J.S.

2000-01-01

Yucca Mountain, located ~100 mi northwest of Las Vegas, Nevada, has been designated by Congress as a site to be characterized for a potential mined geologic repository for high-level radioactive waste. This field trip will examine the regional geologic and hydrologic setting for Yucca Mountain, as well as specific results of the site characterization program. The first day focuses on the regional setting with emphasis on current and paleo hydrology, which are both of critical concern for predicting future performance of a potential repository. Morning stops will be southern Nevada and afternoon stops will be in Death Valley. The second day will be spent at Yucca Mountain. The field trip will visit the underground testing sites in the "Exploratory Studies Facility" and the "Busted Butte Unsaturated Zone Transport Field Test" plus several surface-based testing sites. Much of the work at the site has concentrated on studies of the unsaturated zone, an element of the hydrologic system that historically has received little attention. Discussions during the second day will compromise selected topics of Yucca Mountain geology, hydrology and geochemistry and will include the probabilistic volcanic hazard analysis and the seismicity and seismic hazard in the Yucca Mountain area. Evening discussions will address modeling of regional groundwater flow, the results of recent hydrologic studies by the Nye County Nuclear Waste Program Office, and the relationship of the geology and hydrology of Yucca Mountain to the performance of a potential repository. Day 3 will examine the geologic framework and hydrology of the Pahute Mesa-Oasis Valley Groundwater Basin and then will continue to Reno via Hawthorne, Nevada and the Walker Lake area.

Geochemical evidence for hydroclimatic variability over the last 2460 years from Crevice Lake in Yellowstone National Park, USA

USGS Publications Warehouse

Stevens, L.R.; Dean, W.E.

2008-01-01

A 2460-year-long hydroclimatic record for Crevice Lake, Yellowstone National Park, Montana was constructed from the ??18O values of endogenic carbonates. The ??18O record is compared to the Palmer Hydrologic Drought Index (PHDI) and Pacific Decadal Oscillation (PDO) indices, as well as inferred discharge of the Yellowstone River. During the last century, high ??18O values coincide with drought conditions and the warm phase of the PDO index. Low ??18O values coincide with wet years and a negative PDO index. Comparison of tree-ring inferred discharge of the Yellowstone River with the ??18O record over the last 300 years indicates that periods of high discharge (i.e., wet winters with significant snow pack) correspond with low ??18O values. Extrapolating this relationship we infer wet winters and high river discharge for the periods of 1090-1030, 970-870, 670-620, and 500-430 cal years BP. The wet intervals at 670 and 500 cal BP are synchronous with similar events in Banff, Canada and Walker Lake, Nevada. The wet intervals at 970 and 670 cal BP overlap with wet intervals at Walker Lake and major drought events identified in the western Great Basin. These results suggest that the northern border of Yellowstone National Park straddles the boundary between Northern Rocky Mountains and Great Basin climate regimes. ?? 2007 Elsevier Ltd and INQUA.

Iron-absorption band analysis for the discrimination of iron-rich zones

NASA Technical Reports Server (NTRS)

Rowan, L. C. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Study has concentrated on the two primary aspects of the project, structural analysis through evaluation of lineaments and circular features and spectral analyses through digital computer-processing techniques. Several previously unrecognized lineaments are mapped which may be the surface manifestations of major fault or fracture zones. Two of these, the Walker Lane and the Midas Trench lineament system, transect the predominantly NNE-NNW-trending moutain ranges for more than 500 km. Correlation of major lineaments with productive mining districts implies a genetic relationship, the 50 circular or elliptical features delineated suggest a related role for Tertiary volcanism. Color-ratio composites have been used to identify limonitic zones and to discriminate mafic and felsic rock by combing diazo color transparencies of three different ratios. EROS Data Center scene identification number for color composite in this report is ER 1 CC 500. Refinement of enhancement procedures for the ratio images is progressing. Fieldwork in coordination with both spectral and structural analyses is underway.

Therapy After Exposure to Toxins (I)

DTIC Science & Technology

2005-09-01

Apta30enkel DNA: 120 ng (lane 7), 12 ng (lane 8), 1.2 ng (lane 9 ), 120 pg (lane 10) or 12 pg (lane 11 ). A blank assay to which no DNA was added was...cycles in lane 6). A blank assay to which no DNA was added was pertormed as well (12 cycles, lane 8; 31 cycles (lane 9 ), 36 (lane 10) or 41 (lane 11 ...tg (lane 3, 7, 11 and 15), 400 jig (lane 4, 8, 12 and 16) and 600 jig (lane 5, 9 , 13 and 17) were used. Amplification products of the ssDNA that was

Geometry and kinematics of the eastern Lake Mead fault system in the Virgin Mountains, Nevada and Arizona

USGS Publications Warehouse

Beard, Sue; Campagna, David J.; Anderson, R. Ernest

2010-01-01

The Lake Mead fault system is a northeast-striking, 130-km-long zone of left-slip in the southeast Great Basin, active from before 16 Ma to Quaternary time. The northeast end of the Lake Mead fault system in the Virgin Mountains of southeast Nevada and northwest Arizona forms a partitioned strain field comprising kinematically linked northeast-striking left-lateral faults, north-striking normal faults, and northwest-striking right-lateral faults. Major faults bound large structural blocks whose internal strain reflects their position within a left step-over of the left-lateral faults. Two north-striking large-displacement normal faults, the Lakeside Mine segment of the South Virgin–White Hills detachment fault and the Piedmont fault, intersect the left step-over from the southwest and northeast, respectively. The left step-over in the Lake Mead fault system therefore corresponds to a right-step in the regional normal fault system.Within the left step-over, displacement transfer between the left-lateral faults and linked normal faults occurs near their junctions, where the left-lateral faults become oblique and normal fault displacement decreases away from the junction. Southward from the center of the step-over in the Virgin Mountains, down-to-the-west normal faults splay northward from left-lateral faults, whereas north and east of the center, down-to-the-east normal faults splay southward from left-lateral faults. Minimum slip is thus in the central part of the left step-over, between east-directed slip to the north and west-directed slip to the south. Attenuation faults parallel or subparallel to bedding cut Lower Paleozoic rocks and are inferred to be early structures that accommodated footwall uplift during the initial stages of extension.Fault-slip data indicate oblique extensional strain within the left step-over in the South Virgin Mountains, manifested as east-west extension; shortening is partitioned between vertical for extension-dominated structural blocks and south-directed for strike-slip faults. Strike-slip faults are oblique to the extension direction due to structural inheritance from NE-striking fabrics in Proterozoic crystalline basement rocks.We hypothesize that (1) during early phases of deformation oblique extension was partitioned to form east-west–extended domains bounded by left-lateral faults of the Lake Mead fault system, from ca. 16 to 14 Ma. (2) Beginning ca. 13 Ma, increased south-directed shortening impinged on the Virgin Mountains and forced uplift, faulting, and overturning along the north and west side of the Virgin Mountains. (3) By ca. 10 Ma, initiation of the younger Hen Spring to Hamblin Bay fault segment of the Lake Mead fault system accommodated westward tectonic escape, and the focus of south-directed shortening transferred to the western Lake Mead region. The shift from early partitioned oblique extension to south-directed shortening may have resulted from initiation of right-lateral shear of the eastern Walker Lane to the west coupled with left-lateral shear along the eastern margin of the Great Basin.

Late Cenozoic Magmatic and Tectonic Evolution of the Ancestral Cascade Arc in the Bodie Hills, California and Nevada: Insights from Integrated Geologic, Geophysical, Geochemical and Geochronologic Studies

NASA Astrophysics Data System (ADS)

John, D. A.; du Bray, E. A.; Box, S. E.; Blakely, R. J.; Fleck, R. J.; Vikre, P. G.; Cousens, B.; Moring, B. C.

2012-12-01

Geologic mapping integrated with new geophysical, geochemical, and geochronologic data characterize the evolution of Bodie Hills volcanic field (BHVF), a long-lived eruptive center in the southern part of the ancestral Cascade arc. The ~700 km2 field was a locus of magmatic activity from ~15 to 8 Ma. It includes >25 basaltic andesite to trachyandesite stratovolcanoes and silicic trachyandesite to rhyolite dome complexes. The southeastern part of the BHVF is overlain by the ~3.9 to 0.1 Ma, post-arc Aurora Volcanic Field. Long-lived BHVF magmatism was localized by crustal-scale tectonic features, including the Precambrian continental margin, the Walker Lane, the Basin and Range Province, and the Mina deflection. BHVF eruptive activity occurred primarily during 3 stages: 1) dominantly trachyandesite stratovolcanoes (~15.0 to 12.9 Ma), 2) coalesced trachydacite and rhyolite lava domes and trachyandesite stratovolcanoes (~11.6 to 9.7 Ma), and 3) dominantly silicic trachyandesite to dacite lava dome complexes (~9.2 to 8.0 Ma). Small rhyolite domes were emplaced at ~6 Ma. Relatively mafic stratovolcanoes surrounded by debris flow aprons lie on the margins of the BHVF, whereas more silicic dome fields occupy its center. Detailed gravity and aeromagnetic data suggest the presence of unexposed cogenetic granitic plutons beneath the center of the BHVF. Isotopic compositions of BHVF rocks are generally more radiogenic with decreasing age (e.g., initial Sr isotope values increase from ~0.7049 to 0.7061), which suggests progressively greater magma contamination by crustal components during evolution of the BHVF. Approximately circular, polygenetic volcanoes and scarcity of dikes suggest a low differential horizontal stress field during BHVF formation. Extensive alluvial gravel deposits that grade laterally into fluvial gravels and finer grained lacustrine sediments and the westerly sourced Eureka Valley Tuff (EVT; ~9.4 Ma) blanket large parts of the BHVF. The earliest sediments (≥11.5 Ma to ~9.4 Ma) fill paleotopography around and between older volcanic centers, lap onto the NE part of the BHVF, extend east into Fletcher Valley, and are overlain by EVT. The Fletcher Valley sediments probably mark the beginning of regional Basin-Range extension. Post-EVT alluvial-fan, fluvial, and lacustrine deposits on the NW margin of the Bodie Hills apparently are related to development of the flanking Bridgeport Valley graben to the west. No major through-going faults are recognized in the Bodie Hills, and BHVF volcanoes are only gently (<25°) tilted and little extended. Dominantly intermediate to silicic stratovolcanoes and dome complexes in the BHVF are similar to other long-lived, ancestral Cascade arc eruptive centers in the western Basin and Range (e.g., Virginia Range, Tonopah, Goldfield) and differ from areas farther west and north (e.g., central Sierra Nevada, Lake Tahoe, Warner Range) characterized by more mafic compositions (mostly basalt to andesite), mixed strato- and shield volcanoes, and small lava domes. These differences likely reflect thicker crust that inhibited direct ascent of mafic, mantle-derived magma, thereby promoting long-lived magma reservoirs with extensive differentiation and crustal contamination at shallow depths.

Evaluation of Lane Reduction "Road Diet" Measures and their Effects on Crashes and Injuries

DOT National Transportation Integrated Search

2004-12-01

Road diets are often conversions of four-lane undivided roads into three lanes (two through lanes and a center turn lane). The fourth lane may be converted to bicycle lanes, sidewalks, and/or on-street parking. In other words, existing space is reall...

A new bus lane on urban expressway with no-bay bus stop

NASA Astrophysics Data System (ADS)

Tian, Zhao; Jia, Limin

2016-01-01

The sharp increase in residents and vehicles causes heavy traffic pressure in many cities. To ease traffic congestion, it has been the common sense that we should develop public transit system. The priority of the bus appears particularly necessary with the rapid development of the public transport system. The bus lane is an important embodiment of the bus priority. Focusing on the problem of the unreasonable dedicated bus lane (DBL) under the lower ratio of buses, this paper proposed a new bus lane with limited physical length. And this bus lane can reduce the lane-changing conflict caused by the buses and cars running on roads without bus lanes. Based on the cellular automata (CA) traffic flow model and the lane-changing behavior of the vehicle including the optional lane-changing and the mandatory lane-changing, a three-lane traffic model with an isolated no-bay bus stop is proposed. The ordinary three-lane traffic without a bus lane and the cases of traffic with a DBL or the proposed bus lane are simulated, and the comparisons in the form of the fundamental diagrams are made among them. It is shown that the no-bay bus stop can act as a bottleneck on the traffic flow because of the mandatory lane-changing behavior. Under a certain ratio of the bus number to the total vehicles number, (1) the traffic with the proposed bus lane has less lane-changing conflict and can provide higher traffic capacity than the ordinary traffic without a bus lane, (2) compared with the DBL, the proposed bus lane is advantageous in easing congestion on the ordinary lanes when the traffic flow is high and can avoid unreasonable allocation of the road resources.

Two-lane traffic-flow model with an exact steady-state solution.

PubMed

Kanai, Masahiro

2010-12-01

We propose a stochastic cellular-automaton model for two-lane traffic flow based on the misanthrope process in one dimension. The misanthrope process is a stochastic process allowing for an exact steady-state solution; hence, we have an exact flow-density diagram for two-lane traffic. In addition, we introduce two parameters that indicate, respectively, driver's driving-lane preference and passing-lane priority. Due to the additional parameters, the model shows a deviation of the density ratio for driving-lane use and a biased lane efficiency in flow. Then, a mean-field approach explicitly describes the asymmetric flow by the hop rates, the driving-lane preference, and the passing-lane priority. Meanwhile, the simulation results are in good agreement with an observational data, and we thus estimate these parameters. We conclude that the proposed model successfully produces two-lane traffic flow particularly with the driving-lane preference and the passing-lane priority.

Lane-changing behavior and its effect on energy dissipation using full velocity difference model

NASA Astrophysics Data System (ADS)

Wang, Jian; Ding, Jian-Xun; Shi, Qin; Kühne, Reinhart D.

2016-07-01

In real urban traffic, roadways are usually multilane with lane-specific velocity limits. Most previous researches are derived from single-lane car-following theory which in the past years has been extensively investigated and applied. In this paper, we extend the continuous single-lane car-following model (full velocity difference model) to simulate the three-lane-changing behavior on an urban roadway which consists of three lanes. To meet incentive and security requirements, a comprehensive lane-changing rule set is constructed, taking safety distance and velocity difference into consideration and setting lane-specific speed restriction for each lane. We also investigate the effect of lane-changing behavior on distribution of cars, velocity, headway, fundamental diagram of traffic and energy dissipation. Simulation results have demonstrated asymmetric lane-changing “attraction” on changeable lane-specific speed-limited roadway, which leads to dramatically increasing energy dissipation.

Effects of modified short-leg walkers on ground reaction force characteristics.

PubMed

Keefer, Maria; King, Jon; Powell, Douglas; Krusenklaus, John H; Zhang, Songning

2008-11-01

Although short-leg walkers are often used in the treatment of lower extremity injuries (ankle and foot fractures and severe ankle sprains), little is known about the effect the short-leg walker on gait characteristics. The purpose was to examine how heel height modifications in different short-leg walkers and shoe side may affect ground reaction forces in walking. Force platforms were used to collect ground reaction force data on 10 healthy participants. Five trials were performed in each of six conditions: lab shoes, gait walker, gait walker with heel insert on shoe side, gait walker modified with insert on walker side, equalizer walker, and equalizer walker with heel insert on shoe side. Conditions were randomized and walking speed was standardized between conditions. A 2x6 (sidexcondition) repeated analysis of variance was used on selected ground reaction force variables (P<0.05). The application of a walker created peak vertical and anteroposterior ground reaction forces prior to the normal peaks associated with the loading response. Wearing a walker introduced an elevated minimum vertical ground reaction force in all conditions except the equalizer walker when compared to shoe on the shoe side. Peak propulsive anteroposterior ground reaction forces were smaller in all walker conditions compared to shoe on walker side. The application of heel insert in gait walker with heel insert (on shoe side) and gait walker modified (on walker side) does not diminish the minimum vertical ground reaction force as hypothesized. Wearing a walker decreases the peak propulsive anteroposterior ground reaction force on the walker side and induces asymmetrical loading.

Road Lane Detection by Discriminating Dashed and Solid Road Lanes Using a Visible Light Camera Sensor.

PubMed

Hoang, Toan Minh; Hong, Hyung Gil; Vokhidov, Husan; Park, Kang Ryoung

2016-08-18

With the increasing need for road lane detection used in lane departure warning systems and autonomous vehicles, many studies have been conducted to turn road lane detection into a virtual assistant to improve driving safety and reduce car accidents. Most of the previous research approaches detect the central line of a road lane and not the accurate left and right boundaries of the lane. In addition, they do not discriminate between dashed and solid lanes when detecting the road lanes. However, this discrimination is necessary for the safety of autonomous vehicles and the safety of vehicles driven by human drivers. To overcome these problems, we propose a method for road lane detection that distinguishes between dashed and solid lanes. Experimental results with the Caltech open database showed that our method outperforms conventional methods.

Road Lane Detection by Discriminating Dashed and Solid Road Lanes Using a Visible Light Camera Sensor

PubMed Central

Hoang, Toan Minh; Hong, Hyung Gil; Vokhidov, Husan; Park, Kang Ryoung

2016-01-01

With the increasing need for road lane detection used in lane departure warning systems and autonomous vehicles, many studies have been conducted to turn road lane detection into a virtual assistant to improve driving safety and reduce car accidents. Most of the previous research approaches detect the central line of a road lane and not the accurate left and right boundaries of the lane. In addition, they do not discriminate between dashed and solid lanes when detecting the road lanes. However, this discrimination is necessary for the safety of autonomous vehicles and the safety of vehicles driven by human drivers. To overcome these problems, we propose a method for road lane detection that distinguishes between dashed and solid lanes. Experimental results with the Caltech open database showed that our method outperforms conventional methods. PMID:27548176

Baby walkers--health visitors' current practice, attitudes and knowledge.

PubMed

Kendrick, Denise; Illingworth, Rachel; Hapgood, Rhydian; Woods, Amanda J; Collier, Jacqueline

2003-09-01

Baby walkers are a commonly used item of nursery equipment. Between 12% and 50% of parents whose infant uses a walker report that their child has suffered a walker-related injury. Health visitors' knowledge, attitudes and practice with regard to walkers and related health education has not been explored so far. The aim of the study was to describe health visitors' knowledge of walkers and walker-related injuries, their attitudes towards walkers and current practice with regard to walker health education, and to examine the relationship between knowledge and attitudes and knowledge and practice. A survey was carried out with 64 health visitors prior to participation in a randomized controlled trial assessing the effectiveness of an educational package in reducing baby walker use. The response rate was 95%. Half of the health visitors always discussed walkers postnatally, most frequently at the 6-9 month check. Most did not usually discuss the frequency of walker-related injuries. Most had negative attitudes towards walkers, but believed that parents hold positive attitudes to them and that it is hard to persuade parents not to use them. Health visitors had a limited knowledge of walker use and walker-related injuries. Those giving advice on walkers most often had higher knowledge scores than those giving advice less often (P = 0.03). Those with higher knowledge scores held more negative attitudes towards walkers (rs = 0.29, P = 0.023) and believed parents to have more positive attitudes towards walkers (rs = -0.49, P < 0.001). Few health visitors had resources to discuss walkers. Health visitor advice regarding walkers needs to be given earlier in the postnatal period than is currently common practice, and they need more knowledge about walker use and related injuries. Education about baby walkers needs to be incorporated into undergraduate and in-service education, which may need to include the development of skills in exploring reasons why parents use walkers and in negotiating alternatives to their use. The provision of audio-visual aids for discussing walkers might also be helpful.

Semantic Information Extraction of Lanes Based on Onboard Camera Videos

NASA Astrophysics Data System (ADS)

Tang, L.; Deng, T.; Ren, C.

2018-04-01

In the field of autonomous driving, semantic information of lanes is very important. This paper proposes a method of automatic detection of lanes and extraction of semantic information from onboard camera videos. The proposed method firstly detects the edges of lanes by the grayscale gradient direction, and improves the Probabilistic Hough transform to fit them; then, it uses the vanishing point principle to calculate the lane geometrical position, and uses lane characteristics to extract lane semantic information by the classification of decision trees. In the experiment, 216 road video images captured by a camera mounted onboard a moving vehicle were used to detect lanes and extract lane semantic information. The results show that the proposed method can accurately identify lane semantics from video images.

Operational analysis of shared lane markings and green bike lanes on roadways with speeds greater than 35 mph : [summary].

DOT National Transportation Integrated Search

2014-01-01

In this project, University of North Florida : researchers analyzed how shared lane markings : (sharrows), wide curb lanes, standard and : buffered bike lanes, and green bike lanes affected : operations of bicycle facilities. Three measures : of effe...

Operational analysis of shared lane markings and green bike lanes on roadways with speeds greater than 35 mph.

DOT National Transportation Integrated Search

2014-01-01

This study analyzed the effectiveness of shared lane markings (sharrows), wide curb lanes, standard and buffered : bike lanes, and green bike lanes on improving operations of bicycle facilities. Three measures of effectiveness : were used in this stu...

Lane Marking Detection and Reconstruction with Line-Scan Imaging Data.

PubMed

Li, Lin; Luo, Wenting; Wang, Kelvin C P

2018-05-20

A bstract: Lane marking detection and localization are crucial for autonomous driving and lane-based pavement surveys. Numerous studies have been done to detect and locate lane markings with the purpose of advanced driver assistance systems, in which image data are usually captured by vision-based cameras. However, a limited number of studies have been done to identify lane markings using high-resolution laser images for road condition evaluation. In this study, the laser images are acquired with a digital highway data vehicle (DHDV). Subsequently, a novel methodology is presented for the automated lane marking identification and reconstruction, and is implemented in four phases: (1) binarization of the laser images with a new threshold method (multi-box segmentation based threshold method); (2) determination of candidate lane markings with closing operations and a marching square algorithm; (3) identification of true lane marking by eliminating false positives (FPs) using a linear support vector machine method; and (4) reconstruction of the damaged and dash lane marking segments to form a continuous lane marking based on the geometry features such as adjacent lane marking location and lane width. Finally, a case study is given to validate effects of the novel methodology. The findings indicate the new strategy is robust in image binarization and lane marking localization. This study would be beneficial in road lane-based pavement condition evaluation such as lane-based rutting measurement and crack classification.

Gap Acceptance During Lane Changes by Large-Truck Drivers—An Image-Based Analysis

PubMed Central

Nobukawa, Kazutoshi; Bao, Shan; LeBlanc, David J.; Zhao, Ding; Peng, Huei; Pan, Christopher S.

2016-01-01

This paper presents an analysis of rearward gap acceptance characteristics of drivers of large trucks in highway lane change scenarios. The range between the vehicles was inferred from camera images using the estimated lane width obtained from the lane tracking camera as the reference. Six-hundred lane change events were acquired from a large-scale naturalistic driving data set. The kinematic variables from the image-based gap analysis were filtered by the weighted linear least squares in order to extrapolate them at the lane change time. In addition, the time-to-collision and required deceleration were computed, and potential safety threshold values are provided. The resulting range and range rate distributions showed directional discrepancies, i.e., in left lane changes, large trucks are often slower than other vehicles in the target lane, whereas they are usually faster in right lane changes. Video observations have confirmed that major motivations for changing lanes are different depending on the direction of move, i.e., moving to the left (faster) lane occurs due to a slower vehicle ahead or a merging vehicle on the right-hand side, whereas right lane changes are frequently made to return to the original lane after passing. PMID:26924947

Gap Acceptance During Lane Changes by Large-Truck Drivers-An Image-Based Analysis.

PubMed

Nobukawa, Kazutoshi; Bao, Shan; LeBlanc, David J; Zhao, Ding; Peng, Huei; Pan, Christopher S

2016-03-01

This paper presents an analysis of rearward gap acceptance characteristics of drivers of large trucks in highway lane change scenarios. The range between the vehicles was inferred from camera images using the estimated lane width obtained from the lane tracking camera as the reference. Six-hundred lane change events were acquired from a large-scale naturalistic driving data set. The kinematic variables from the image-based gap analysis were filtered by the weighted linear least squares in order to extrapolate them at the lane change time. In addition, the time-to-collision and required deceleration were computed, and potential safety threshold values are provided. The resulting range and range rate distributions showed directional discrepancies, i.e., in left lane changes, large trucks are often slower than other vehicles in the target lane, whereas they are usually faster in right lane changes. Video observations have confirmed that major motivations for changing lanes are different depending on the direction of move, i.e., moving to the left (faster) lane occurs due to a slower vehicle ahead or a merging vehicle on the right-hand side, whereas right lane changes are frequently made to return to the original lane after passing.

Fault Slip Partitioning in the Eastern California Shear Zone-Walker Lane Belt: Pliocene to Late Pleistocene Contraction Across the Mina Deflection

NASA Astrophysics Data System (ADS)

Lee, J.; Stockli, D.; Gosse, J.

2007-12-01

Two different mechanisms have been proposed for fault slip transfer between the subparallel NW-striking dextral- slip faults that dominant the Eastern California Shear Zone (ECSZ)-Walker Lane Belt (WLB). In the northern WLB, domains of sinistral-slip along NE-striking faults and clockwise block rotation within a zone of distributed deformation accommodated NW-dextral shear. A somewhat modified version of this mechanism was also proposed for the Mina deflection, southern WLB, whereby NE-striking sinistral faults formed as conjugate faults to the primary zone of NW-dextral shear; clockwise rotation of the blocks bounding the sinistral faults accommodated dextral slip. In contrast, in the northern ECSZ and Mina deflection, domains of NE-striking pure dip-slip normal faults, bounded by NW-striking dextral-slip faults, exhibited no rotation; the proposed mechanism of slip transfer was one of right-stepping, high angle normal faults in which the magnitude of extension was proportional to the amount of strike-slip motion transferred. New geologic mapping, tectonic geomorphologic, and geochronologic data from the Queen Valley area, southern Mina deflection constrain Pliocene to late Quaternary fault geometries, slip orientations, slip magnitudes, and slip rates that bear on the mechanism of fault slip transfer from the relatively narrow northern ECSZ to the broad deformation zone that defines the Mina deflection. Four different fault types and orientations cut across the Queen Valley area: (1) The NE-striking normal-slip Queen Valley fault; (2) NE-striking sinistral faults; (3) the NW-striking dextral Coyote Springs fault, which merges into (4) a set of EW-striking thrust faults. (U-Th)/He apatite and cosmogenic radionuclide data, combined with magnitude of fault offset measurements, indicate a Pliocene to late Pleistocene horizontal extension rate of 0.2-0.3 mm/yr across the Queen Valley fault. Our results, combined with published slip rates for the dextral White Mountain fault zone (0.3-0.8 mm/yr) and the eastern sinistral Coaldale fault (0.4 mm/yr) suggest that transfer of dextral slip from the narrow White Mountains fault zone is explained best by a simple shear couple whereby slip is partitioned into three different components: horizontal extension along the Queen Valley fault, dominantly dextral slip along the Coyote Springs fault, and dominantly sinistral slip along the Coaldale fault. A velocity vector diagram illustrating fault slip partitioning predicts contraction rates of <0.1 to 0.5 mm/yr across the Coyote Springs and western Coaldale faults. The predicted long-term contraction across the Mina deflection is consistent with present-day GPS data.

Study of current and planned high occupancy vehicle lane use: performance and prospects

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

Southworth, F.; Westbrook, F.

1985-12-01

This report details the results of a nationwide study of HOV lanes: their characteristics and performance as traffic congestion mitigating and rideshare enhancing facilities. The study took the form of telephone interviews with a variety of planning agencies in each of the 48 contiguous states and Hawaii over the period April through June 1985, with subsequent receipt of the most current documentation on regional HOV lane operations. The most up-to-date evidence on each lane's performance is presented: its hourly and peak period person throughput vis-a-vis the highway's adjacent, conventional mixed traffic lane(s), its vehicle throughput and occupancy, travel speed andmore » travel time savings for HOVs, lane rule violation rates, lane construction and maintenance costs and accident data. Estimates are provided of the growth in ridesharing over the life of the HOV-only lanes, of the number of vehicles removed from the highway through ridesharing, and of the subsequent fuel savings attributable to HOV lane projects. The relationship between bus patronage and carpool/vanpool mode adoption is looked at, and it is concluded that both forms of HOV can do well on properly planned lanes. The authors also point out the very partial nature of the existing evidence upon which to base HOV lane project evaluation, and the subsequent difficulty associated with ''selling'' the HOV lane concept to many planners and members of the public. They identify those characteristics associated with clearly successful HOV lane projects. Finally, the current state of planning for new HOV lanes in cities around the nation is described, and the major reasons given for rejection or abandonment of HOV lane projects are discussed.« less

A microscopic lane changing process model for multilane traffic

NASA Astrophysics Data System (ADS)

Lv, Wei; Song, Wei-guo; Liu, Xiao-dong; Ma, Jian

2013-03-01

In previous simulations lane-changing behavior is usually assumed as an instantaneous action. However, in real traffic, lane changing is a continuing process which can seriously affect the following cars. In this paper, a microscopic lane-changing process (LCP) model is clearly described. A new idea of simplifying the lane-changing process to the car-following framework is presented by controlling fictitious cars. To verify the model, the results of flow, lane-changing frequency, and single-car velocity are extracted from experimental observations and are compared with corresponding simulation. It is found that the LCP model agrees well with actual traffic flow and lane-changing behaviors may induce a 12%-18% reduction of traffic flow. The results also reflect that most of the drivers on the two roads in a city are conservative but not aggressive to change lanes. Investigation of lane-changing frequency shows that the largest lane-changing frequency occurs at a medium density range from 15 vehs km lane to 35 vehs km lane. It also implies that the lane-changing process might strengthen velocity variation at medium density and weaken velocity variation at high density. It is hoped that the idea of this study may be helpful to promote the modeling and simulation study of traffic flow.

Application of a performance management framework for priced lanes.

DOT National Transportation Integrated Search

2013-04-01

The Texas Department of Transportation and its agency partners have implemented various forms of lane : management and pricing over the past three decades, including high-occupancy vehicle (HOV) lanes, highoccupancy toll lanes, managed lanes, and tol...

Road diet informational guide.

DOT National Transportation Integrated Search

2014-11-01

A classic Road Diet converts an existing four-lane undivided roadway segment to a three-lane segment consisting of two : through lanes and a center two-way left turn lane (TWLTL). A Road Diet improves safety by including a protected left-turn lane : ...

Wheeled and standard walkers in Parkinson's disease patients with gait freezing.

PubMed

Cubo, Esther; Moore, Charity G; Leurgans, Sue; Goetz, Christopher G

2003-10-01

Compare the efficacy of two walking assistance devices (wheeled walker and standard walker) to unassisted walking for patients with PD and gait freezing. Although numerous walking devices are used clinically, their relative effects on freezing and walking speed have never been systematically tested. Nineteen PD patients (14 non-demented) walked under three conditions in randomized order: unassisted walking, standard walker, and wheeled walker. Patients walked up to three times in each condition through a standard course that included rising from a chair, walking through a doorway, straightway walking, pivoting, and return. Total walking time, freezing time and number of freezes were compared for the three conditions using mixed models (walking time) and Friedman's test (freezing). The wheeled walker was further studied by comparing the effect of an attached laser that projected a bar of light on the floor as a visual walking cue. Use of either type of device significantly slowed walking compared to unassisted walking. Neither walker reduced any index of freezing, nor the laser attachment offered any advantage to the wheeled walker. The standard walker increased freezing, and the wheeled walker had no effect on freezing. Among the non-demented subjects (n=14), the same patterns occurred, although the walking speed was less impaired by the wheeled walker than the standard walker in this group. Though walkers may stabilize patients and increase confidence, PD patients walk more slowly when using them, without reducing freezing. Because the wheeled walker was intermediate for walking time and does not aggravate freezing, if walkers are used for these subjects, this type of walker should be favored.

Analysis of driver merging behavior at lane drops on freeways.

DOT National Transportation Integrated Search

2013-12-01

Lane changing assistance systems advise drivers on safe gaps for making mandatory lane changes at lane drops. In this : study, such a system was developed using a Bayes classifier and a decision tree to model lane changes. Detailed vehicle : trajecto...

Intelligently Controllable Walker with Magnetorheological Fluid Brake

NASA Astrophysics Data System (ADS)

Kikuchi, Takehito; Tanida, Sosuke; Tanaka, Toshimasa; Kobayashi, Keigo; Mitobe, Kazuhisa

Caster walkers are supporting frames with casters and wheels. These tools are regularly utilized as life support tools or walking rehabilitation tools in hospitals, nursing homes and individual residences. Users of the walkers can easily move it thanks to its wheels and casters. However falling accidents often happen when it moves without users. The falling accident is very serious problem and one of leading causes of secondary injuries. In the other case, it is hard to move to desired directions if users have imbalance in their motor functions or sensory functions, e.g., hemiplegic patients. To improve safeness and operability of the walkers, we installed compact MR fluid brakes on the wheels and controlled walking speed and direction of the walker. We named this intelligently controllable walker, “i-Walker” and discussed on the control methods and experimental results in this paper. Preliminary trials for direction control of the first-generation of the i-Walker (i-Walker1) are presented. On the basis of the results, we improved the control method and hardware of the i-Walker1, and developed the second-generation (i-Walker2). System description and experimental results of the i-Walker2 are also described. The i-Walker2 has better operability and lower energy consumption than that of the i-Walker1. The line-tracing controller of the i-Walker2 well controls human motions during walking experiments on the target straight line.

Understanding Traveler Behavior : The Psychology Behind Managed Lane Use

DOT National Transportation Integrated Search

2012-07-01

Recent analysis of Katy Freeway/Managed Lane (ML) travelers and I-394 Freeway/High : Occupancy Toll (HOT) lane traveler data has found that many travelers pay to use these HOT : lanes and MLs when adjacent toll-free lanes are operating at nearly the ...

Maritime Trade Warfare Against a Modern Power

DTIC Science & Technology

2013-05-20

numerous archipelagic sea lanes. There are three designated sea lanes, several tributaries to these sea lanes, and numerous other customary sea lanes...such as innocent passage in territorial seas or use of archipelagic sea lanes. Operationally, a multilateral blockade also provides ports and bases for...Indonesian archipelagic sea lanes, the Strait of Hormuz, the Bab-El-Mandeb, the Panama Canal, and the Bearing Strait. Attempts to bypass these chokepoints

[Dandy-Walker complex: a clinicopathologic study of 9 cases].

PubMed

Zhang, Xiao-bo; Gu, Yi-qun; Sun, Xiao-fei; Wang, Ying-nan; Wang, Ai-chun

2013-12-01

To investigate the etiology, pathogenesis, clinicopathologic characteristics, clinical prognosis and treatment of Dandy-Walker syndrome. Nine cases of Dandy-Walker syndrome were included in the study. The autopsy findings and clinical history were evaluated along with review of the literature. The causes, pathogenetic mechanism, pathologic features and prognosis of Dandy-Walker syndrome were analyzed. Among 9 Dandy-Walker syndrome cases, six patients presented with variants of Dandy-Walker complex and 3 cases had classic Dandy-Walker malformation. In addition, 4 patients presented with combined lateral ventricle expansion and multiple malformations were seen in 7 cases. Combined umbilical cord abnormality was noted in 4 patients with variant of Dandy-Walker complex and combined placental abnormality was seen in one classic Dandy-Walker syndrome. Dandy-Walker syndrome is a rare disease. In addition to complex pathogenesis with possible genetic and environmental antigenic etiologies, placental and umbilical cord abnormality may be also related to its development.

Fibreglass Total Contact Casting, Removable Cast Walkers, and Irremovable Cast Walkers to Treat Diabetic Neuropathic Foot Ulcers: A Health Technology Assessment

PubMed Central

Costa, Vania; Tu, Hong Anh; Wells, David; Weir, Mark; Holubowich, Corinne; Walter, Melissa

2017-01-01

Background Diabetic neuropathic foot ulcers are a risk factor for lower leg amputation. Many experts recommend offloading with fibreglass total contact casting, removable cast walkers, and irremovable cast walkers as a way to treat these ulcers. Methods We completed a health technology assessment, which included an evaluation of clinical benefits and harms, value for money, and patient preferences for offloading devices. We performed a systematic literature search on August 17, 2016, to identify randomized controlled trials that compared fibreglass total contact casting, removable cast walkers, and irremovable cast walkers with other treatments (offloading or non-offloading) in patients with diabetic neuropathic foot ulcers. We developed a decision-analytic model to assess the cost-effectiveness of fibreglass total contact casting, removable cast walkers, and irremovable cast walkers, and we conducted a 5-year budget impact analysis. Finally, we interviewed people with diabetes who had lived experience with foot ulcers, asking them about the different offloading devices and the factors that influenced their treatment choices. Results We identified 13 randomized controlled trials. The evidence suggests that total contact casting, removable cast walkers, and irremovable cast walkers are beneficial in the treatment of neuropathic, noninfected foot ulcers in patients with diabetes but without severe peripheral arterial disease. Compared to removable cast walkers, ulcer healing was improved with total contact casting (moderate quality evidence; risk difference 0.17 [95% confidence interval 0.00–0.33]) and irremovable cast walkers (low quality evidence; risk difference 0.21 [95% confidence interval 0.01–0.40]). We found no difference in ulcer healing between total contact casting and irremovable cast walkers (low quality evidence; risk difference 0.02 [95% confidence interval −0.11–0.14]). The economic analysis showed that total contact casting and irremovable cast walkers were less expensive and led to more health outcome gains (e.g., ulcers healed and quality-adjusted life-years) than removable cast walkers. Irremovable cast walkers were as effective as total contact casting and were associated with lower costs. The 5-year budget impact of funding total contact casting, removable cast walkers, and irremovable cast walkers (device costs only at 100% access) would be $17 to $20 million per year. The patients we interviewed felt that wound healing was improved with total contact casting than with removable cast walkers, but that removable cast walkers were more convenient and came with a lower cost burden. They reported no experience or familiarity with irremovable cast walkers. Conclusions Ulcer healing improved with total contact casting, irremovable cast walkers, and removable cast walkers, but total contact casting and irremovable cast walkers had higher rates of ulcer healing than removable cast walkers. Increased access to offloading devices could result in cost savings for the health system because of fewer amputations. Patients with diabetic foot ulcers reported a preference for total contact casting over removable cast walkers, largely because they perceived wound healing to be improved with total contact casting. However, cost, comfort, and convenience are concerns for patients. PMID:28989556

Fibreglass Total Contact Casting, Removable Cast Walkers, and Irremovable Cast Walkers to Treat Diabetic Neuropathic Foot Ulcers: A Health Technology Assessment.

PubMed

2017-01-01

Diabetic neuropathic foot ulcers are a risk factor for lower leg amputation. Many experts recommend offloading with fibreglass total contact casting, removable cast walkers, and irremovable cast walkers as a way to treat these ulcers. We completed a health technology assessment, which included an evaluation of clinical benefits and harms, value for money, and patient preferences for offloading devices. We performed a systematic literature search on August 17, 2016, to identify randomized controlled trials that compared fibreglass total contact casting, removable cast walkers, and irremovable cast walkers with other treatments (offloading or non-offloading) in patients with diabetic neuropathic foot ulcers. We developed a decision-analytic model to assess the cost-effectiveness of fibreglass total contact casting, removable cast walkers, and irremovable cast walkers, and we conducted a 5-year budget impact analysis. Finally, we interviewed people with diabetes who had lived experience with foot ulcers, asking them about the different offloading devices and the factors that influenced their treatment choices. We identified 13 randomized controlled trials. The evidence suggests that total contact casting, removable cast walkers, and irremovable cast walkers are beneficial in the treatment of neuropathic, noninfected foot ulcers in patients with diabetes but without severe peripheral arterial disease. Compared to removable cast walkers, ulcer healing was improved with total contact casting (moderate quality evidence; risk difference 0.17 [95% confidence interval 0.00-0.33]) and irremovable cast walkers (low quality evidence; risk difference 0.21 [95% confidence interval 0.01-0.40]). We found no difference in ulcer healing between total contact casting and irremovable cast walkers (low quality evidence; risk difference 0.02 [95% confidence interval -0.11-0.14]). The economic analysis showed that total contact casting and irremovable cast walkers were less expensive and led to more health outcome gains (e.g., ulcers healed and quality-adjusted life-years) than removable cast walkers. Irremovable cast walkers were as effective as total contact casting and were associated with lower costs. The 5-year budget impact of funding total contact casting, removable cast walkers, and irremovable cast walkers (device costs only at 100% access) would be $17 to $20 million per year. The patients we interviewed felt that wound healing was improved with total contact casting than with removable cast walkers, but that removable cast walkers were more convenient and came with a lower cost burden. They reported no experience or familiarity with irremovable cast walkers. Ulcer healing improved with total contact casting, irremovable cast walkers, and removable cast walkers, but total contact casting and irremovable cast walkers had higher rates of ulcer healing than removable cast walkers. Increased access to offloading devices could result in cost savings for the health system because of fewer amputations. Patients with diabetic foot ulcers reported a preference for total contact casting over removable cast walkers, largely because they perceived wound healing to be improved with total contact casting. However, cost, comfort, and convenience are concerns for patients.

Guidelines for the conversion of urban four-lane undivided roadways to three-lane two-way left-turn lane facilities

DOT National Transportation Integrated Search

2001-04-01

The primary objective of this research project was to develop a set of guidelines to assist in the selection of candidate roadways for urban four-lane undivided to three-lane cross section conversions. The authors evaluated and assessed the physical,...

Potential Safety Effects of Lane Width and Shoulder Width on Two-Lane Rural State Highways in Idaho

DOT National Transportation Integrated Search

2012-07-01

This study provides a comprehensive evaluation of the relationship between crash rates and shoulder width and lane width for two-lane rural state highways in Idaho. Crash Modification Factors (CMFs) for shoulder width and lane width were developed us...

Demixing-stimulated lane formation in binary complex plasma

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

Du, C.-R.; Jiang, K.; Suetterlin, K. R.

2011-11-29

Recently lane formation and phase separation have been reported for experiments with binary complex plasmas in the PK3-Plus laboratory onboard the International Space Station (ISS). Positive non-additivity of particle interactions is known to stimulate phase separation (demixing), but its effect on lane formation is unknown. In this work, we used Langevin dynamics (LD) simulation to probe the role of non-additivity interactions on lane formation. The competition between laning and demixing leads to thicker lanes. Analysis based on anisotropic scaling indices reveals a crossover from normal laning mode to a demixing-stimulated laning mode. Extensive numerical simulations enabled us to identify amore » critical value of the non-additivity parameter {Delta} for the crossover.« less

Robust lane detection and tracking using multiple visual cues under stochastic lane shape conditions

NASA Astrophysics Data System (ADS)

Huang, Zhi; Fan, Baozheng; Song, Xiaolin

2018-03-01

As one of the essential components of environment perception techniques for an intelligent vehicle, lane detection is confronted with challenges including robustness against the complicated disturbance and illumination, also adaptability to stochastic lane shapes. To overcome these issues, we proposed a robust lane detection method named classification-generation-growth-based (CGG) operator to the detected lines, whereby the linear lane markings are identified by synergizing multiple visual cues with the a priori knowledge and spatial-temporal information. According to the quality of linear lane fitting, the linear and linear-parabolic models are dynamically switched to describe the actual lane. The Kalman filter with adaptive noise covariance and the region of interests (ROI) tracking are applied to improve the robustness and efficiency. Experiments were conducted with images covering various challenging scenarios. The experimental results evaluate the effectiveness of the presented method for complicated disturbances, illumination, and stochastic lane shapes.

Q&A with Andy Walker: The Ins and Outs of Renewable Energy Optimization |

Science.gov Websites

Optimization April 30, 2018 Profile image of researcher Andy Walker Andy Walker is a research fellow at NREL and the creator of Renewable Energy Optimization. Profile image of researcher Andy Walker Andy Walker is a research fellow at NREL and the creator of Renewable Energy Optimization. Andy Walker is a

Comparison of upper extremity glenohumeral joint forces in children with cerebral palsy using anterior and posterior walkers - biomed 2009.

PubMed

Strifling, Kelly M B; Konop, Katherine A; Wang, Mei; Harris, Gerald F

2009-01-01

Walkers are prescribed with the notion that one type of walker will be better for a child than another. One underlying justification for this practice is the theory that one walker may produce less stress on the upper extremities as the patient uses the walker. Nevertheless, upper extremity joint loading is not typically analyzed during walker assisted gait in children with spastic diplegic cerebral palsy. It has been difficult to evaluate the theory of walker prescription based on upper extremity stresses because loading on the upper extremities however has not been quantified until recently. In this study, weight bearing on the glenohumeral joints was analyzed in five children with spastic diplegic cerebral palsy using both anterior and posterior walkers fitted with 6-axis handle transducers. Though walkers' effects on the upper extremities proved to be similar between walker types, the differences between the walkers may have some clinical significance in the long run. In general, posterior walker use created larger glenohumeral joint forces. Though these differences are not statistically significant, over time and with repetitive loading they may be clinically significant.

Using SLAM to Look For the Dog Valley Fault, Truckee Area, California

NASA Astrophysics Data System (ADS)

Cronin, V. S.; Ashburn, J. A.; Sverdrup, K. A.

2014-12-01

The Truckee earthquake (9/12/1966, ML6.0) was a left-lateral event on a previously unrecognized NW-trending fault. The Prosser Creek and Boca Dams sustained damage, and the trace of the suspected causative fault passes near or through the site of the then-incomplete Stampede Dam. Another M6 earthquake occurred along the same general trend in 1948 with an epicenter in Dog Valley ~14 km to the NW of the 1966 epicenter. This trend is called the Dog Valley Fault (DVF), and its location on the ground surface is suggested by a prominent but broad zone of geomorphic lineaments near the cloud of aftershock epicenters determined for the 1966 event. Various ground effects of the 1966 event described by Kachadoorian et al. (1967) were located within this broad zone. The upper shoreface of reservoirs in the Truckee-Prosser-Martis basin are now exposed due to persistent drought. We have examined fault strands in a roadcut and exposed upper shoreface adjacent to the NE abutment of Stampede Dam. These are interpreted to be small-displacement splays associated with the DVF -- perhaps elements of the DVF damage zone. We have used the Seismo-Lineament Analysis Method (SLAM) to help us constrain the location of the DVF, based on earthquake focal mechanisms. Seismo-lineaments were computed, using recent revisions in the SLAM code (bearspace.baylor.edu/Vince_Cronin/www/SLAM/), for the 1966 main earthquake and for the better-recorded earthquakes of 7/3/1983 (M4) and 8/30/1992 (M3.2) that are inferred to have occurred along the DVF. Associated geomorphic analysis and some field reconnaissance identified a trend that might be associated with a fault, extending from the NW end of Prosser Creek Reservoir ~32° toward the Stampede Dam area. Triangle-strain analysis using horizontal velocities of local Plate Boundary Observatory GPS sites P146, P149, P150 and SLID indicates that the area rotates clockwise ~1-2°/Myr relative to the stable craton, as might be expected because the study area is within the Walker Lane transition zone between the Basin and Range and the Sierra Nevada-Great Valley Block. If the current seismogenic trace of the DVF is along the ~32° trend, perhaps the more prominent geomorphic lineaments traditionally associated with the DVF are inactive older features that are more strongly expressed on the landscape and that have rotated.

Interior Western U. S. Deformation Coming into Focus with Maturing Survey and Continuous GPS Networks

NASA Astrophysics Data System (ADS)

Thatcher, W. R.; Svarc, J. L.

2010-12-01

Active Basin and Range (BR) extension produces spectacular fault-generated topography spread over ~800 km in the interior western US. However, present-day deformation rates are relatively low east of the San Andreas fault system and Cascadia subduction zone and ± 1 mm/yr precision in GPS velocity is needed to pinpoint the major faults that accommodate extension. Typically, 3 years of continuous (CGPS) operation and 8 years of sparsely repeated survey (SGPS) network occupations are required to attain this precision. U. S. Geological Survey (USGS) survey networks and Plate Boundary Observatory (PBO) continuous station records are now long enough to meet these requirements. USGS and PBO station coverage is generally complementary. PBO coverage established since 2005 within the ~1000 km x 1500 km deforming zone is relatively complete at ~100 km station spacing; USGS survey-mode profiles established during 1999-2003 are dense; typical station spacing is ~25 km and results are sufficiently precise to determine localized velocity gradients of 1 mm/yr or greater (over ~25-50 km distances) across mapped active strike-slip and normal faults traversed by the SGPS profiles. The great majority of geologically young faults appear to slip at rates less than 1 mm/yr but rates are measurably higher near the western and eastern edges of the BR. There is a marked transition in NE California from strike-slip faulting at rates of ~ 4 mm/yr across the northern Walker Lane zone to pure extension north of about Mt. Lassen. This distinct boundary is apparently related to the prevalence of strike-slip tractions on the San Andreas plate boundary south of the Mendocino triple junction (MTJ) to tensile stresses caused by Cascadia slab retreat north of the MTJ. A horizontal extension rate of 3 mm/yr is observed across the north-striking Hat Creek and related normal faults immediately north of Lassen, but this extension decreases to no more than 1 mm/yr in the Klamath Basin, about 150 km to the north. Extension rates could be as high as ~1 mm/yr across the Surprise Valley fault (near the California-Nevada border) and the Steens Mountain-Pueblo Mountains fault (SE Oregon). But elsewhere in Oregon, Idaho and Montana, extension rates are < 1 mm/yr and only on the eastern edge of the BR, across the Wasatch and related faults in central Utah, do rates reach 3 mm/yr.

Walker's Eleodes (Coleoptera: Tenebrionidae)

USDA-ARS?s Scientific Manuscript database

The type specimens of five species of Eleodes described by Francis Walker were studied in order to establish their true identity. The synonymy of Eleodes convexicollis Walker and Eleodes conjunctus Walker with E. obscurus (Say); that of Eleodes latiusculus Walker with E. humeralis LeConte; and that ...

Highway planning and operations for the Dallas district: Implementation and evaluation of concurrent flow HOV lanes in Texas. Research report, September 1996--August 1997

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

Skowronek, D.A.; Stoddard, A.M.; Ranft, S.E.

1997-11-01

Limited capital investment for major transportation improvements and growth in metropolitan areas require the most efficient use of the existing transportation system. One means to achieve this is high-occupancy vehicle (HOV) lanes. While an extensive system of permanent HOV lanes is planned for the Dallas-Fort Worth urbanized area, the Texas Department of Transportation (TxDOT) and Dallas Area Rapid Transit (DART) have pursued and continue short-term or interim HOV lane projects that would enhance public transportation and overall mobility. There are currently 57 km (35.4 mi) of interim HOV lanes operational in the Dallas area, including a barrier-separated contraflow lane onmore » I-30 (East R.L. Thornton Freeway) and buffer-separated concurrent flow HOV lanes on I-35E North (Stemmons Freeway) and I-635 (Lyndon B. Johnson Freeway). The objective of this research is to investigate the operational effectiveness of the new concurrent flow HOV lanes in the Dallas area, as well as to assess the effectiveness of concurrent flow (buffer-separated) versus contraflow (barrier-separated) HOV lanes. Issues such as person movement, carpool formation, travel time savings, violation rates, and project cost effectiveness are addressed. By understanding the operational performance and issues of both concurrent flow (buffer-separated) HOV lanes and contraflow (barrier-separated) HOV lanes, recommendations can be made on suggested HOV lane polices, including the type of permanent HOV lanes to be implemented in the Dallas area.« less

Study of Small Ligands Which Bind Specifically to Breast Cancer Cells

DTIC Science & Technology

1997-09-01

Sepharose conjugated to three different lectins: ConA, wheat germ and lentil,. Each lectin bound many proteins in both the ECD-AP sup and the control 3T3 sup...control Lanes 13-14: Wheat germ ECD-AP Lanes 15-16: Wheat germ 3T3 control Odd lanes were eluted with a low sugar concentration; even lanes were...ECD-AP post incubation with lentil-Sepharose Lane 6: Protein remaining in pp ECD-AP post incubation with wheat germ -Sepharose Lane 8: Protein

PSO Algorithm Particle Filters for Improving the Performance of Lane Detection and Tracking Systems in Difficult Roads

PubMed Central

Cheng, Wen-Chang

2012-01-01

In this paper we propose a robust lane detection and tracking method by combining particle filters with the particle swarm optimization method. This method mainly uses the particle filters to detect and track the local optimum of the lane model in the input image and then seeks the global optimal solution of the lane model by a particle swarm optimization method. The particle filter can effectively complete lane detection and tracking in complicated or variable lane environments. However, the result obtained is usually a local optimal system status rather than the global optimal system status. Thus, the particle swarm optimization method is used to further refine the global optimal system status in all system statuses. Since the particle swarm optimization method is a global optimization algorithm based on iterative computing, it can find the global optimal lane model by simulating the food finding way of fish school or insects under the mutual cooperation of all particles. In verification testing, the test environments included highways and ordinary roads as well as straight and curved lanes, uphill and downhill lanes, lane changes, etc. Our proposed method can complete the lane detection and tracking more accurately and effectively then existing options. PMID:23235453

Promoting child safety in primary care: a cluster randomised controlled trial to reduce baby walker use.

PubMed

Kendrick, Denise; Illingworth, Rachel; Woods, Amanda; Watts, Kim; Collier, Jacqueline; Dewey, Michael; Hapgood, Rhydian; Chen, Chih-Mei

2005-08-01

Baby walkers are commonly used items of nursery equipment, but cause more than 3000 injuries each year in the UK. There is currently little evidence regarding the effectiveness of interventions in primary care to reduce walker use. To evaluate the effectiveness of an educational package provided by midwives and health visitors to reduce baby walker possession and use. Cluster randomised controlled trial. Sixty-four general practices in Nottingham and North Nottinghamshire, UK. An educational package aimed at discouraging mothers-to-be from obtaining and using a walker was delivered by midwives and health visitors to 1174 mothers-to-be of at least 28 weeks gestation. The control arm received usual care. Primary outcome measures were the possession and use of a walker. Secondary outcome measures included the frequency and duration of walker use, knowledge and attitudes towards walkers, plans to use a walker with future children, recommending a walker to a friend, and use of stair gates and fire guards. Intervention arm participants were significantly less likely to own (odds ratio [OR] = 0.63, 95% confidence interval [CI] = 0.43 to 0.93) or to use a walker (OR = 0.26, 95% CI = 0.08 to 0.84). They were significantly less likely to plan to use a walker with their next child (OR = 0.52, 95% CI = 0.31 to 0.86) or to agree that walkers keep children safe (OR = 0.35, 95% CI = 0.16 to 0.78). There was some evidence that they were less likely to recommend a walker to a friend (OR = 0.51, 95% CI = 0.28 to 0.91) or to agree that they help children to walk more quickly (OR = 0.53, 95% CI = 0.29 to 0.95). An educational package delivered by midwives and health visitors was effective in reducing baby walker possession and use. Providers of primary healthcare services should include baby walker education in their injury prevention strategy and child health promotion programme.

Evaluation of the high occupancy vehicle (HOV) lanes on the Long Island Expressway : January 1997 HOV lane user and non-user survey

DOT National Transportation Integrated Search

1997-01-01

As part of the periodic evaluation of the High Occupancy Vehicle (HOV) lanes on the Long Island Expressway, an HOV lane user/non-user survey was conducted in January 1997. The survey included users of the HOV lanes during the HOV-reserved hours, HOV ...

Motorcycle lane-sharing : literature review.

DOT National Transportation Integrated Search

2010-06-01

This report examines the use of lane-sharing (also sometimes referred to as lane-splitting and filtering) nationally and internationally and includes discussions on motorcycle and driver (auto) safety, and the potential benefits of lane-sharing.

Agent-based modeling of lane discipline in heterogeneous traffic

NASA Astrophysics Data System (ADS)

Dailisan, Damian N.; Lim, May T.

2016-09-01

Designating lanes for different vehicle types is ideal road safety-wise. Practical considerations, however, require road sharing. Using a modified Nagel-Schreckenberg cellular automata model for two vehicle types (cars and motorcycles), we analyzed the interplay of lane discipline, lane changing, and vehicle density. In the absence of lane changing, the transition between free flow and congested states occurs at a higher vehicle (road occupation) density when the ratio of cars to motorcycles is increased. When lane changing is allowed, the smaller motorcycles tend to fill in unused spaces, until the point when the wider cars effectively block their way at high vehicle densities. When the condition of lane discipline is not imposed, i.e. staying wholly within lane boundaries is not required, further improvement in throughput becomes possible at the cost of required driver attentiveness.

Highway planning and operations for the Dallas district: Implementation and evaluation of concurrent flow HOV lanes in Texas. Project summary report 1994-14S, September 1996--August 1997

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

Skowronek, D.A.; Stoddard, A.M.; Ranft, S.E.

1997-11-01

Limited capital investment for major transportation improvements and growth in metropolitan areas require the most efficient use of the existing transportation system. One means to achieve this is high-occupancy vehicle (HOV) lanes. While an extensive system of permanent HOV lanes is planned for the Dallas-Fort Worth urbanized area, the Texas Department of Transportation (TxDOT) and Dallas Area Rapid Transit (DART) have pursued and continue to pursue short-term or interim HOV lane projects that would enhance public transportation and overall mobility. There are currently 57 km (35.4 mi) of interim HOV lanes operational in the Dallas area, including a barrier-separated contraflowmore » lane on I-30 (East R.L. Thornton Freeway) and buffer-separated concurrent flow HOV lanes on I-35E North (Stemmons Freeway) and I-635 (Lyndon B. Johnson Freeway). The objective of this research is to investigate the operational effectiveness of concurrent flow (buffer-separated) versus contraflow (barrier-separated) HOV lanes. Issues such as person movement, carpool formation, travel time savings, violation rates, and project cost effectiveness are addressed. By understanding the operational performance and issues of both concurrent flow (buffer-separated) HOV lanes and contraflow (barrier-separated) HOV lanes, recommendations can be made on suggested HOV lane policies, including the type of permanent HOV lanes to be implemented in the Dallas area.« less

Effective dynamics of a random walker on a heterogeneous ring: Exact results

NASA Astrophysics Data System (ADS)

Masharian, S. R.

2018-07-01

In this paper, by considering a biased random walker hopping on a one-dimensional lattice with a ring geometry, we investigate the fluctuations of the speed of the random walker. We assume that the lattice is heterogeneous i.e. the hopping rate of the random walker between the first and the last lattice sites is different from the hopping rate of the random walker between the other links of the lattice. Assuming that the average speed of the random walker in the steady-state is v∗, we have been able to find the unconditional effective dynamics of the random walker where the absolute value of the average speed of the random walker is -v∗. Using a perturbative method in the large system-size limit, we have also been able to show that the effective hopping rates of the random walker near the defective link are highly site-dependent.

Do orthotic walkers affect knee and hip function during gait?

PubMed

Richards, Jim; Payne, Katherine; Myatt, Darren; Chohan, Ambreen

2016-02-01

Much previous research on orthotic walkers has focussed on their ability to offload structures in the foot and ankle; however, little is known about their effects on lower limb mechanics. This study aimed to determine effects of two orthotic walkers on the biomechanics of the knee and hip joints compared to standardised footwear. A total of 10 healthy participants walked under three conditions: Walker A (Össur, Iceland), Walker B (DJO Global, USA) and standardised footwear (Hotter, UK). Kinematic and kinetic data were collected using a Qualisys motion analysis system (Qualisys Medical AB, Sweden) and force plates (AMTI, Boston, MA, USA). Significant differences were seen in hip kinematics and knee moments between walkers and standardised footwear and in knee kinematics between Walker A and standardised footwear. Both walkers show significant kinematic and kinetic differences compared with standardised footwear; however, Walker A appeared to produce greater deviation, including potentially damaging greater hyperextension moments at the knee. Further research is needed into the effects of orthotic walkers on knee and hip joint mechanics, which should help to inform future designs of walker, with greater focus on obtaining a more normal gait pattern. © The International Society for Prosthetics and Orthotics 2014.

Injuries associated with infant walkers.

PubMed

2001-09-01

In 1999, an estimated 8800 children younger than 15 months were treated in hospital emergency departments in the United States for injuries associated with infant walkers. Thirty-four infant walker-related deaths were reported from 1973 through 1998. The vast majority of injuries occur from falls down stairs, and head injuries are common. Walkers do not help a child learn to walk; indeed, they can delay normal motor and mental development. The use of warning labels, public education, adult supervision during walker use, and stair gates have all been demonstrated to be insufficient strategies to prevent injuries associated with infant walkers. To comply with the revised voluntary standard (ASTM F977-96), walkers manufactured after June 30, 1997, must be wider than a 36-in doorway or must have a braking mechanism designed to stop the walker if 1 or more wheels drop off the riding surface, such as at the top of a stairway. Because data indicate a considerable risk of major and minor injury and even death from the use of infant walkers, and because there is no clear benefit from their use, the American Academy of Pediatrics recommends a ban on the manufacture and sale of mobile infant walkers. If a parent insists on using a mobile infant walker, it is vital that they choose a walker that meets the performance standards of ASTM F977-96 to prevent falls down stairs. Stationary activity centers should be promoted as a safer alternative to mobile infant walkers.

Drainage reversals in Mono Basin during the late pliocene and Pleistocene

USGS Publications Warehouse

Reheis, M.C.; Stine, S.; Sarna-Wojcicki, A. M.

2002-01-01

Mono Basin, on the eastern flank of the central Sierra Nevada, is the highest of the large hydrographically closed basins in the Basin and Range province. We use geomorphic features, shoreline deposits, and basalt-filled paleochannels to reconstruct an early to middle Pleistocene record of shorelines and changing spillways of Lake Russell in Mono Basin. During this period of time, Lake Russell repeatedly attained altitudes between 2205 and 2280 m-levels far above the present surface of Mono Lake (~1950 m) and above its last overflow level (2188 m). The spill point of Lake Russell shifted through time owing to late Tertiary and Quaternary faulting and volcanism. During the early Pleistocene, the lake periodically discharged through the Mount Hicks spillway on the northeastern rim of Mono Basin and flowed northward into the Walker Lake drainage basin via the East Walker River. Paleochannels recording such discharge were incised prior to 1.6 Ma, possibly between 1.6 and 1.3 Ma, and again after 1.3 Ma (ages of basaltic flows that plugged the paleochannels). Faulting in the Adobe Hills on the southeastern margin of the basin eventually lowered the rim in this area to below the altitude of the Mount Hicks spillway. Twice after 0.76 Ma, and possibly as late as after 0.1 Ma, Lake Russell discharged southward through the Adobe Hills spillway into the Owens-Death Valley system of lakes. This study supports a pre-Pleistocene aquatic connection through Mono Basin between the hydrologically distinct Lahontan and Owens-Death Valley systems, as long postulated by biologists, and also confirms a probable link during the Pleistocene for species adapted to travel upstream in fast-flowing water.

Where do bike lanes work best? A Bayesian spatial model of bicycle lanes and bicycle crashes

Treesearch

Michelle C. Kondo; Christopher Morrison; Erick Guerra; Elinore J. Kaufman; Douglas J. Wiebe

2018-01-01

US municipalities are increasingly introducing bicycle lanes to promote bicycle use, increase roadway safety and improve public health. The aim of this study was to identify specific locations where bicycle lanes, if created, could most effectively reduce crash rates. Previous research has found that bike lanes reduce crash incidence, but a lack of comprehensive...

Intelligent driving in traffic systems with partial lane discipline

NASA Astrophysics Data System (ADS)

Assadi, Hamid; Emmerich, Heike

2013-04-01

It is a most common notion in traffic theory that driving in lanes and keeping lane changes to a minimum leads to smooth and laminar traffic flow, and hence to increased traffic capacity. On the other hand, there exist persistent vehicular traffic systems that are characterised by habitual disregarding of lane markings, and partial or complete loss of laminar traffic flow. Here, we explore the stability of such systems through a microscopic traffic flow model, where the degree of lane-discipline is taken as a variable, represented by the fraction of drivers that disregard lane markings completely. The results show that lane-free traffic may win over completely ordered traffic at high densities, and that partially ordered traffic leads to the poorest overall flow, while not considering the crash probability. Partial order in a lane-free system is similar to partial disorder in a lane-disciplined system in that both lead to decreased traffic capacity. This could explain the reason why standard enforcement methods, which rely on continuous increase of order, often fail to incur order to lane-free traffic systems. The results also provide an insight into the cooperative phenomena in open systems with self-driven particles.

The effects of lane width, shoulder width, and road cross-sectional reallocation on drivers' behavioral adaptations.

PubMed

Mecheri, Sami; Rosey, Florence; Lobjois, Régis

2017-07-01

Previous research has shown that lane-width reduction makes drivers operate vehicles closer to the center of the road whereas hard-shoulder widening induces a position farther away from the road's center. The goal of the present driving-simulator study was twofold. First, it was aimed at further investigating the respective effects of lane and shoulder width on in-lane positioning strategies, by examining vehicle distance from the center of the lane. The second aim was to assess the impact on safety of three possible cross-sectional reallocations of the width of the road (i.e., three lane-width reductions with concomitant shoulder widening at a fixed cross-sectional width) as compared to a control road. The results confirmed that lane-width reduction made participants drive closer to the road's center. However, in-lane position was affected differently by lane narrowing, depending on the traffic situation. In the absence of oncoming traffic, lane narrowing gave rise to significant shifts in the car's distance from the lane's center toward the edge line, whereas this distance remained similar across lane widths during traffic periods. When the shoulders were at least 0.50m wide, participants drove farther away from both the road center and the lane center. Road reallocation operations resulted in vehicles positioned farther away from the edge of the road and less swerving behavior, without generating higher driving speeds. Finally, it is argued that road-space reallocation may serve as a good low-cost tool for providing a recovery area for steering errors, without impairing drivers' behavior. Copyright © 2017 Elsevier Ltd. All rights reserved.

Training strategies and materials.

DOT National Transportation Integrated Search

2014-06-01

TxDOT project 0-6706 Design and Scope of Impact of Auxiliary Lanes has developed : guidelines for implementation of auxiliary lanes including general guidelines on the use of : auxiliary lanes and design guidelines for auxiliary lanes. To facil...

0-6810 : guidelines for applying right-turn slip lanes.

DOT National Transportation Integrated Search

2014-10-01

Rightturn slip lanes are advantageous to : motorists because they reduce delays by : separating right-turning traffic from adjacent : lanes and accommodating higherspeed right : turns. The right-turn slip lane channelizing : island may also pro...

Iron-absorption band analysis for the discrimination of iron-rich zones

NASA Technical Reports Server (NTRS)

Rowan, L. C. (Principal Investigator)

1973-01-01

The author has identified the following significant results. Lineament analysis of the area was initiated on individual images and then expanded areally by the use of mosaics at the 1:1,000,000 scale. Principal trends are NE, NW, NNE-NNW, and ENE. Several previously unrecognized lineaments are mapped which may be the surface manifestations of major fault or fracture zones. Three lineaments are especially noteworthy. Two of these, the Walker Lane and the Midas Trench lineament system, transect the prediominantly NNE-NNW trending mountain ranges for more than 500 km. A third major lineament, formed by the alinement of several topographic escarpments 10-20 km long, is orthogonal to the Midas Trench lineament. This lineament is marked by a distinct positive magnetic anomaly for approximately 200 km. Further visual analysis of ERTS-1 images has resulted in the delineation of 50 circular or elliptical features which are presumed to be volcanic or intrusive centers. A comparison with the 78 Tertiary volcanic centers mapped in the study area in 1970 indicates some good agreement between the proposed and known volcanic centers. The coincidence of some major lineaments and productive ore bodies implies a genetic relationship.

LiDAR-Assisted identification of an active fault near Truckee, California

USGS Publications Warehouse

Hunter, L.E.; Howle, J.F.; Rose, R.S.; Bawden, G.W.

2011-01-01

We use high-resolution (1.5-2.4 points/m2) bare-earth airborne Light Detection and Ranging (LiDAR) imagery to identify, map, constrain, and visualize fault-related geomorphology in densely vegetated terrain surrounding Martis Creek Dam near Truckee, California. Bare-earth LiDAR imagery reveals a previously unrecognized and apparently youthful right-lateral strike-slip fault that exhibits laterally continuous tectonic geomorphic features over a 35-km-long zone. If these interpretations are correct, the fault, herein named the Polaris fault, may represent a significant seismic hazard to the greater Truckee-Lake Tahoe and Reno-Carson City regions. Three-dimensional modeling of an offset late Quaternary terrace riser indicates a minimum tectonic slip rate of 0.4 ?? 0.1 mm/yr.Mapped fault patterns are fairly typical of regional patterns elsewhere in the northern Walker Lane and are in strong coherence with moderate magnitude historical seismicity of the immediate area, as well as the current regional stress regime. Based on a range of surface-rupture lengths and depths to the base of the seismogenic zone, we estimate a maximum earthquake magnitude (M) for the Polaris fault to be between 6.4 and 6.9.

Grizzly Valley fault system, Sierra Valley, CA

USGS Publications Warehouse

Gold, Ryan; Stephenson, William; Odum, Jack; Briggs, Rich; Crone, Anthony; Angster, Steve

2012-01-01

The Grizzly Valley fault system (GVFS) strikes northwestward across Sierra Valley, California and is part of a network of active, dextral strike-slip faults in the northern Walker Lane (Figure 1). To investigate Quaternary motion across the GVFS, we analyzed high-resolution (0.25 m) airborne LiDAR data (Figure 2) in combination with six, high-resolution, P-wave, seismic-reflection profiles [Gold and others, 2012]. The 0.5- to 2.0-km-long seismic-reflection profiles were sited orthogonal to suspected tectonic lineaments identified from previous mapping and our analysis of airborne LiDAR data. To image the upper 400–700 m of subsurface stratigraphy of Sierra Valley (Figure 3), we used a 230-kg accelerated weight drop source. Geophone spacing ranged from 2 to 5 m and shots were co-located with the geophones. The profiles reveal a highly reflective, deformed basal marker that we interpret to be the top of Tertiary volcanic rocks, overlain by a 120- to 300-m-thick suite of subhorizontal reflectors we interpret as Plio-Pleistocene lacustrine deposits. Three profiles image the principle active trace of the GVFS, which is a steeply dipping fault zone that offsets the volcanic rocks and the basin fill (Figures 4 & 5).

Comparison of upper extremity kinematics in children with spastic diplegic cerebral palsy using anterior and posterior walkers.

PubMed

Strifling, Kelly M B; Lu, Na; Wang, Mei; Cao, Kevin; Ackman, Jeffrey D; Klein, John P; Schwab, Jeffrey P; Harris, Gerald F

2008-10-01

This prospective study analyzes the upper extremity kinematics of 10 children with spastic diplegic cerebral palsy using anterior and posterior walkers. Although both types of walkers are commonly prescribed by clinicians, no quantitative data comparing the two in regards to upper extremity motion has been published. The study methodology included testing of each subject with both types of walkers in a motion analysis laboratory after an acclimation period of at least 1 month. Overall results showed that statistically, both walkers are relatively similar. With both anterior and posterior walkers, the shoulders were extended, elbows flexed, and wrists extended. Energy expenditure, walking speed and stride length was also similar with both walker types. Several differences were also noted although not statistically significant. Anterior torso tilt was reduced with the posterior walker and shoulder extension and elbow flexion were increased. Outcomes analysis indicated that differences in upper extremity torso and joint motion were not dependent on spasticity or hand dominance. These findings may help to build an understanding of upper extremity motion in walker-assisted gait and potentially to improve walker prescription.

[Differential diagnosis of Dandy-Walker syndrome different presentations].

PubMed

Tobías-González, Pablo; Gil Mira, Mar; Valero de Bernabé, Javier; Zapardiel, Ignacio

2012-08-01

Dandy-Walker syndrome is a set of abnormalities of the posterior fossa including three modalities: classic Dandy-Walker malformation, Dandy-Walker variant and mega-cisterna magna. Our objective is clarify the differential diagnosis among these entities. Descriptive and retrospective study of Dandy-Walker cases diagnosed at our Department during the last five years plus a review of the related Medical literature. Three cases of Dandy-Walker modalities are reported: one case of classic Dandy-Walker malformation, one case of Dandy-Walker variant, and one case of false Dandy-Walker. In the first two cases the patients underwent legal abortion, whereas in the last one a healthy male newborn was delivered in the week 38 of gestation. Malformations in the posterior fossa, including Dandy-Walker syndrome, are still a challenge in prenatal diagnosis. Technical developments in imaging, such as in three-dimensional sonography and magnetic resonance, allow higher resolution and multiplanar images for an easier diagnose. There is a high rate of false positive, particularly before the 18th week of gestation. It is advisable not to establish a final diagnose before that week.

A comparative study of bike lane injuries.

PubMed

Wee, Jung Hee; Park, Jeong Ho; Park, Kyu Nam; Choi, Seung Pill

2012-02-01

Because of the increased number of bicycle riders and governmental promotions, a recent increase in the construction of bicycle lanes has occurred. We aimed to characterize injuries specific to bicycle lane accidents by comparing them with injuries that occurred on regular roadways. On the basis of our findings, we provide suggestions on proper preventive strategies. We performed a retrospective study on 408 cases obtained between January 1, 2009, and December 31, 2010. Of these cases, 387 met the criterion that the location of the injury could be confirmed by telephone or via review of the patient's chart. Data regarding age, gender, Injury Severity Score, time of the accident, location of the accident, and other characteristics were collected. Data were analyzed using SPSS 12.0K. Of the 387 cases, 204 (52.7%) patients were injured in bicycle lanes and 183 (47.3%) were injured on regular roadways. Comparing cases of bicycle lane injuries and non-bicycle lane injuries, there were no differences in age, day of the week, season, or the time at which the accident occurred. Bicycle helmets were used more frequently in bicycle lane injuries (33.2% vs. 13.7%; p < 0.001). In addition, the most common causes of injury for bicycle lane incidences were falls (59.3%) and collisions with other bicycles (23.5%), whereas in non-bicycle lane cases, falls (42.6%) and collisions with other vehicles (39.3%) were the most common causes of injury. Although the severity of injuries was slightly lower in bicycle lane cases, it was not significantly lower than non-bicycle lane cases. Although people are increasingly using bicycle lanes for safety, this study shows that they are not definitively safer. Therefore, improvements in the policies related to implementing bicycle lane safety are needed, for example, by enforcing the use of protective gear or preventing the use of bicycle lanes by pedestrians. More safety education programs are also needed. III.

Lifting HOV/HOT lane eligibility and shoulder use restrictions for traffic incident management : [technical summary].

DOT National Transportation Integrated Search

2013-12-01

High occupancy vehicle lanes{Pmrcpmj}; : High occupancy toll lanes{Pmrcpmjh}; : Incident management{Dcmthcj}; : Road shoulders{Pmrcps}; : Traffic diversion{Bthh}; : Decision making{Epdmd}; : General purpose lanes{Pmrcpmd}; : Ramp metering{Dcmthcfr}; ...

Deployment strategies of managed lanes on arterials.

DOT National Transportation Integrated Search

2015-02-01

This report investigates issues related to planning, financing, deployment, and operation of managed : lanes on arterials. In this report, a strategy for managed lanes refers to a combination of the managed : lane type, the design and implementation,...

An electric vehicle driving behavior model in the traffic system with a wireless charging lane

NASA Astrophysics Data System (ADS)

He, Jia; Huang, Hai-Jun; Yang, Hai; Tang, Tie-Qiao

2017-09-01

In this paper, a car-following model is proposed to study each EV's (electric vehicle) motion behavior near the WCL (wireless charging lane) and a lane-changing rule is designed to describe the EV's lane-changing behavior. Then, the car-following model and lane-changing rule are used to explore each EV's micro driving behavior in a two-lane system with a WCL. Finally, the impacts of the WCL on each EV's motion behavior are investigated. The numerical results show that each EV should run slowly on the WCL if it needs charge of electricity, that the EV's lane-changing behavior has great effects on the whole system, that the delay time caused by the WCL turns more prominent when the traffic turns heavy, and that lane-changing frequently occurs near the WCL (especially at the downstream of the WCL).

Effect of bike lane infrastructure improvements on ridership in one New Orleans neighborhood.

PubMed

Parker, Kathryn M; Rice, Janet; Gustat, Jeanette; Ruley, Jennifer; Spriggs, Aubrey; Johnson, Carolyn

2013-02-01

Incorporating cycling into daily life is one way to increase physical activity. This study examined the impact of building new bike lanes in New Orleans to determine whether more people were cycling on the street and with the flow of traffic after bike lanes were built. Through direct observation of one intervention and two adjacent streets, observers counted cyclists riding on the street and sidewalk, with and against traffic, before and after installation of the lanes. Data were tallied separately for adults, children, males, females, and by race for each location. There was an increase in cyclists on all three streets after the installation of the bike lanes, with the largest increase on the street with the new lane. Additionally, the proportion of riders cycling with traffic increased after the lanes were striped. Bike lanes can have a positive impact in creating a healthy neighborhood.

The role of walkers' needs and expectations in supporting maintenance of attendance at walking groups: a longitudinal multi-perspective study of walkers and walk group leaders.

PubMed

Kassavou, Aikaterini; Turner, Andrew; French, David P

2015-01-01

There is good evidence that when people's needs and expectations regarding behaviour change are met, they are satisfied with that change, and maintain those changes. Despite this, there is a dearth of research on needs and expectations of walkers when initially attending walking groups and whether and how these needs and expectations have been satisfied after a period of attendance. Equally, there is an absence of research on how people who lead these groups understand walkers' needs and walk leaders' actions to address them. The present study was aimed at addressing both of these gaps in the research. Two preliminary thematic analyses were conducted on face-to-face interviews with (a) eight walkers when they joined walking groups, five of whom were interviewed three months later, and (b) eight walk leaders. A multi-perspective analysis building upon these preliminary analyses identified similarities and differences within the themes that emerged from the interviews with walkers and walk leaders. Walkers indicated that their main needs and expectations when joining walking groups were achieving long-term social and health benefits. At the follow up interviews, walkers indicated that satisfaction with meeting similar others within the groups was the main reason for continued attendance. Their main source of dissatisfaction was not feeling integrated in the existing walking groups. Walk leaders often acknowledged the same reasons for walkers joining and maintaining attendance at walking. However, they tended to attribute dissatisfaction and drop out to uncontrollable environmental factors and/or walkers' personalities. Walk leaders reported a lack of efficacy to effectively address walkers' needs. Interventions to increase retention of walkers should train walk leaders with the skills to help them modify the underlying psychological factors affecting walkers' maintenance at walking groups. This should result in greater retention of walkers in walking groups, thereby allowing walkers to receive the long-term social and health benefits of participation in these groups.

Lane marking detection based on waveform analysis and CNN

NASA Astrophysics Data System (ADS)

Ye, Yang Yang; Chen, Hou Jin; Hao, Xiao Li

2017-06-01

Lane markings detection is a very important part of the ADAS to avoid traffic accidents. In order to obtain accurate lane markings, in this work, a novel and efficient algorithm is proposed, which analyses the waveform generated from the road image after inverse perspective mapping (IPM). The algorithm includes two main stages: the first stage uses an image preprocessing including a CNN to reduce the background and enhance the lane markings. The second stage obtains the waveform of the road image and analyzes the waveform to get lanes. The contribution of this work is that we introduce local and global features of the waveform to detect the lane markings. The results indicate the proposed method is robust in detecting and fitting the lane markings.

Should state DOTs prefer bicycle lanes or wide curb lanes?

DOT National Transportation Integrated Search

2008-06-01

This report investigates collisions between bicycles and motor vehicles to ascertain their relationship (if any) to a Bicycle Lane or Wide Curb Lane for the purpose of informing State Departments of Transportation (DOTs). A literature review describe...

Applications for the environment : real-time information synthesis (AERIS). Eco-lanes : operational concept.

DOT National Transportation Integrated Search

2013-10-01

This document serves as an Operational Concept for the Applications for the Environment: Real-Time Information Synthesis (AERIS) Eco-Lanes Transformative Concept. The Eco-Lanes Transformative Concept features dedicated lanes on freeways optimized for...

Using walker during walking: a pilot study for health elder.

PubMed

Po-Chan, Yeh; Cherng-Yee, Leung

2012-01-01

Walker operation completely relies on the walker handle, however most marketed walkers possess two horizontal handles. Several researchers have suggested that horizontal handles might lead to wrist injury. Therefore, the purpose of this study is to assess the relevant design aspects of walker for elderly people. 28 elders participated in this study; when the experiment was started, subject walked on the tile for 3 meter distance twice by using walker. Data for analysis were selected at the corresponding wrist deviation and vertical force. The results showed that during walker using, the mean wrist deviation was greater than zero. The largest vertical force is significantly larger than the smallest one, and different wrist deviation occurred at three phases, the largest wrist deviation while raising walker is larger than the smallest one, however, no significant different was found between the largest and smallest wrist deviation while pressing walker. No significant correlation occurred between weight and wrist deviation. The correlation between weight and vertical force was significantly positive. With wrist deviation walker use may cause injury to upper-limb, however wrists remain in a neutral position during hand movement to prevent damage. The findings of this study should improve the design of walker handles to reduce the wrist deviations of users.

Studies of vehicle lane-changing dynamics and its effect on traffic efficiency, safety and environmental impact

NASA Astrophysics Data System (ADS)

Li, Xiang; Sun, Jian-Qiao

2017-02-01

Drivers often change lanes on the road to maintain desired speed and to avoid slow vehicles, pedestrians, obstacles and lane closure. Understanding the effect of lane-changing on the traffic is an important topic in designing optimal traffic control systems. This paper presents a comprehensive study of this topic. We review the theory of microscopic dynamic car-following models and the lane-changing models, propose additional lane-changing rules to deal with moving bottleneck and lane reduction, and investigate the effects of lane-changing on the traffic efficiency, traffic safety and fuel consumption as a function of different variables including the distance of the emergency sign ahead of the lane closure, speed limit, traffic density, etc. Extensive simulations of the traffic system have been carried out in different scenarios. A number of important findings of the effect of various factors on the traffic are reported. These findings provide guidance on the traffic management and are important to the designers and engineers of modern highway or inner city roads to achieve high traffic efficiency and safety with minimum environmental impact.

Efficient Lane Boundary Detection with Spatial-Temporal Knowledge Filtering

PubMed Central

Nan, Zhixiong; Wei, Ping; Xu, Linhai; Zheng, Nanning

2016-01-01

Lane boundary detection technology has progressed rapidly over the past few decades. However, many challenges that often lead to lane detection unavailability remain to be solved. In this paper, we propose a spatial-temporal knowledge filtering model to detect lane boundaries in videos. To address the challenges of structure variation, large noise and complex illumination, this model incorporates prior spatial-temporal knowledge with lane appearance features to jointly identify lane boundaries. The model first extracts line segments in video frames. Two novel filters—the Crossing Point Filter (CPF) and the Structure Triangle Filter (STF)—are proposed to filter out the noisy line segments. The two filters introduce spatial structure constraints and temporal location constraints into lane detection, which represent the spatial-temporal knowledge about lanes. A straight line or curve model determined by a state machine is used to fit the line segments to finally output the lane boundaries. We collected a challenging realistic traffic scene dataset. The experimental results on this dataset and other standard dataset demonstrate the strength of our method. The proposed method has been successfully applied to our autonomous experimental vehicle. PMID:27529248

False capacity for lane drops : final report.

DOT National Transportation Integrated Search

2005-02-01

Lane drops downstream of signalized intersections are found on many urban and suburban streets and highways. Since : drivers tend to avoid using the short lane due to the potential for stressful merges downstream of the signal, the short lane is : ty...

Impact of lane closures on roadway capacity, phase 2.

DOT National Transportation Integrated Search

2014-01-01

This project is a follow-up to Florida Department of Transportation (FDOT) research project BD545-61, Impact of : Lane Closures on Roadway Capacity (specifically, Part A: Development of a Two-Lane Work Zone Lane Closure : Analysis Procedure and...

The safety potential of lane departure warning systems-A descriptive real-world study of fatal lane departure passenger car crashes in Sweden.

PubMed

Sternlund, Simon

2017-05-29

Lane departure crashes account for a significant proportion of passenger car occupant fatalities and serious injuries. Utilizing real-world data involving fatal passenger car crashes in Sweden, the characteristics of lane departure crashes were identified and the safety potential of lane departure warning (LDW) systems was quantified. The material consisted of 104 in-depth studies of fatal passenger car crashes in 2010. The crashes were classified as single-vehicle (n = 48), head-on (n = 52), and overtaking (n = 4) crashes. These crash types were identified as crashes that could have potentially involved lane departure. A case-by-case analysis was carried out and lane departure crashes were identified and characterized using police reports and information collected by crash investigators at the Swedish Transport Administration; for example, inspections and photographs of the crash sites and of the involved vehicles. Lane departure crashes were separated from crashes where loss of control occurred pre-lane departure. Furthermore, loss of control post-lane departures were identified. When studying the pre-stage of lane departure without prior loss of control, crashes were categorized as unintentional drifting, intentional lane change, or evasive maneuver. Using previously published effectiveness information, the potential for LDW systems to prevent crashes was estimated. Of all crashes with passenger car occupant fatalities in Sweden in 2010, 46% (63/138) were found to relate to lane departure without prior loss of control. These crashes accounted for 61% (63/104) of all single-vehicle, head-on, and overtaking crashes. The remaining 41 crashes were due to loss of control pre-lane departure. Unintentional drifting accounted for 81% (51/63) of all lane departure crashes without prior loss of control, which corresponded to 37% (51/138) of all fatal passenger car occupant crashes. LDW systems were found to potentially prevent 33-38 of the 100 fatal head-on and single vehicle crashes. These crashes involved drifting and occurred on roads with visible lane markings, signed posted speed limits ≥70 km/h, and without rumble strips on the corresponding lane departure side. The range of potentially prevented crashes (33-38) is due to the inclusion or exclusion of crashes involving excessive speeding. In this study, approximately half (51/100) of all head-on and single-vehicle crashes were identified as being a consequence of drifting, where LDW systems had the potential to prevent the majority (33-38) of these crashes. The typical lane departure crash without prior loss of control occurred on undivided roads in rural areas with signed posted speed limits ≥70 km/h, where the center and side road markings were visible.

Visible/near-infrared subdiffraction imaging reveals the stochastic nature of DNA walkers.

PubMed

Pan, Jing; Cha, Tae-Gon; Li, Feiran; Chen, Haorong; Bragg, Nina A; Choi, Jong Hyun

2017-01-01

DNA walkers are designed with the structural specificity and functional diversity of oligonucleotides to actively convert chemical energy into mechanical translocation. Compared to natural protein motors, DNA walkers' small translocation distance (mostly <100 nm) and slow reaction rate (<0.1 nm s -1 ) make single-molecule characterization of their kinetics elusive. An important indication of single-walker kinetics is the rate-limiting reactions that a particular walker design bears. We introduce an integrated super-resolved fluorescence microscopy approach that is capable of long-term imaging to investigate the stochastic behavior of DNA walkers. Subdiffraction tracking and imaging in the visible and second near-infrared spectra resolve walker structure and reaction rates. The distributions of walker kinetics are analyzed using a stochastic model to reveal reaction randomness and the rate-limiting biochemical reaction steps.

Mechanical-Kinetic Modeling of a Molecular Walker from a Modular Design Principle

NASA Astrophysics Data System (ADS)

Hou, Ruizheng; Loh, Iong Ying; Li, Hongrong; Wang, Zhisong

2017-02-01

Artificial molecular walkers beyond burnt-bridge designs are complex nanomachines that potentially replicate biological walkers in mechanisms and functionalities. Improving the man-made walkers up to performance for widespread applications remains difficult, largely because their biomimetic design principles involve entangled kinetic and mechanical effects to complicate the link between a walker's construction and ultimate performance. Here, a synergic mechanical-kinetic model is developed for a recently reported DNA bipedal walker, which is based on a modular design principle, potentially enabling many directional walkers driven by a length-switching engine. The model reproduces the experimental data of the walker, and identifies its performance-limiting factors. The model also captures features common to the underlying design principle, including counterintuitive performance-construction relations that are explained by detailed balance, entropy production, and bias cancellation. While indicating a low directional fidelity for the present walker, the model suggests the possibility of improving the fidelity above 90% by a more powerful engine, which may be an improved version of the present engine or an entirely new engine motif, thanks to the flexible design principle. The model is readily adaptable to aid these experimental developments towards high-performance molecular walkers.

Implementation elements for conversion of general-purpose freeway lane into high-occupancy-vehicle lane

DOT National Transportation Integrated Search

1997-01-01

Conversion of a general-purpose freeway into a high-occupancy-vehicle (HOV) lane is an alternative to infrastructure addition for HOV system implementation. Research indicates that lane conversion is feasible technically if sufficient HOV usage and m...

Evaluation of adjacent AC and CRC pavement lanes : final report.

DOT National Transportation Integrated Search

1995-02-01

On some of Oregon's highways, particularly on the interstate freeways in Eastern Oregon, most of the heavy trucks travel in the outside lane (right lane). With this kind of truck traffic pattern, the right lane experiences significantly higher axle l...

A review of HOV lane performance and policy options in the United States

DOT National Transportation Integrated Search

2008-12-01

The report provides an assessment of performance of existing HOV lane facilities in the United States, and explores policy alternatives and effects related to conversion of existing HOV lanes to HOT lane operations. The report includes sketch plannin...

Bicycle Lanes Versus Wide Curb Lanes: Operational and Safety Findings and Countermeasure Recommendations

DOT National Transportation Integrated Search

1999-10-01

This report presents operational and safety findings and countermeasure recommendations from a comparative analysis of bicycle lanes (BLs) versus wide curb lanes (WCLs). The primary analysis was based on videotapes of almost 4,600 bicyclists in Santa...

Lane marking/striping to improve image processing lane departure warning systems.

DOT National Transportation Integrated Search

2007-05-01

Vision-based Lane Departure Warning Systems (LDWS) depend on pavement marking tracking to : determine that vehicles perform unintended drifts out of the travel lanes. Thus, it is expected that : the performances of these LDWS be influenced by the vis...

A lane line segmentation algorithm based on adaptive threshold and connected domain theory

NASA Astrophysics Data System (ADS)

Feng, Hui; Xu, Guo-sheng; Han, Yi; Liu, Yang

2018-04-01

Before detecting cracks and repairs on road lanes, it's necessary to eliminate the influence of lane lines on the recognition result in road lane images. Aiming at the problems caused by lane lines, an image segmentation algorithm based on adaptive threshold and connected domain is proposed. First, by analyzing features like grey level distribution and the illumination of the images, the algorithm uses Hough transform to divide the images into different sections and convert them into binary images separately. It then uses the connected domain theory to amend the outcome of segmentation, remove noises and fill the interior zone of lane lines. Experiments have proved that this method could eliminate the influence of illumination and lane line abrasion, removing noises thoroughly while maintaining high segmentation precision.

New Jersey I-80 and I-287 HOV lane case study

DOT National Transportation Integrated Search

2000-07-01

This report documents the New Jersey I-80 and I-287 high-occupancy vehicle (HOV) lane case study. Information is presented on planning, implementing, operating, and redesignating the HOV lanes on the two freeways. The operation of the lanes is compar...

A summary of design, policies and operational characteristics for shared bicycle/bus lanes : [summary].

DOT National Transportation Integrated Search

2012-01-01

Traffic lanes set aside for the use of specific categories of vehicles are becoming more common, from dedicated bicycle lanes on urban roadways to managed lanes for carpools and other high occupancy vehicles on Floridas interstate highways. These ...

Road Lane Detection Robust to Shadows Based on a Fuzzy System Using a Visible Light Camera Sensor.

PubMed

Hoang, Toan Minh; Baek, Na Rae; Cho, Se Woon; Kim, Ki Wan; Park, Kang Ryoung

2017-10-28

Recently, autonomous vehicles, particularly self-driving cars, have received significant attention owing to rapid advancements in sensor and computation technologies. In addition to traffic sign recognition, road lane detection is one of the most important factors used in lane departure warning systems and autonomous vehicles for maintaining the safety of semi-autonomous and fully autonomous systems. Unlike traffic signs, road lanes are easily damaged by both internal and external factors such as road quality, occlusion (traffic on the road), weather conditions, and illumination (shadows from objects such as cars, trees, and buildings). Obtaining clear road lane markings for recognition processing is a difficult challenge. Therefore, we propose a method to overcome various illumination problems, particularly severe shadows, by using fuzzy system and line segment detector algorithms to obtain better results for detecting road lanes by a visible light camera sensor. Experimental results from three open databases, Caltech dataset, Santiago Lanes dataset (SLD), and Road Marking dataset, showed that our method outperformed conventional lane detection methods.

The impact of false warnings on partial and full lane departure warnings effectiveness and acceptance in car driving.

PubMed

Navarro, Jordan; Yousfi, Elsa; Deniel, Jonathan; Jallais, Christophe; Bueno, Mercedes; Fort, Alexandra

2016-12-01

In the past, lane departure warnings (LDWs) were demonstrated to improve driving behaviours during lane departures but little is known about the effects of unreliable warnings. This experiment focused on the influence of false warnings alone or in combination with missed warnings and warning onset on assistance effectiveness and acceptance. Two assistance unreliability levels (33 and 17%) and two warning onsets (partial and full lane departure) were manipulated in order to investigate interaction. Results showed that assistance, regardless unreliability levels and warning onsets, improved driving behaviours during lane departure episodes and outside of these episodes by favouring better lane-keeping performances. Full lane departure and highly unreliable warnings, however, reduced assistance efficiency. Drivers' assistance acceptance was better for the most reliable warnings and for the subsequent warnings. The data indicate that imperfect LDWs (false warnings or false and missed warnings) further improve driving behaviours compared to no assistance. Practitioner Summary: This study revealed that imperfect lane departure warnings are able to significantly improve driving performances and that warning onset is a key element for assistance effectiveness and acceptance. The conclusion may be of particular interest for lane departure warning designers.

Detecting lane departures from steering wheel signal.

PubMed

Sandström, Max; Lampsijärvi, Eetu; Holmström, Axi; Maconi, Göran; Ahmadzai, Shabana; Meriläinen, Antti; Hæggström, Edward; Forsman, Pia

2017-02-01

Current lane departure warning systems are video-based and lose data when road- and weather conditions are bad. This study sought to develop a lane departure warning algorithm based on the signal drawn from the steering wheel. The rationale is that a car-based lane departure warning system should be robust regardless of road- and weather conditions. N=34 professional driver students drove in a high-fidelity driving simulator at 80km/h for 55min every third hour during 36h of sustained wakefulness. During each driving session we logged the steering wheel- and lane position signals at 60Hz. To derive the lane position signal, we quantified the transfer function of the simulated vehicle and used it to derive the absolute lane position signal from the steering wheel signal. The Pearson correlation between the derived- and actual lane position signals was r=0.48 (based on 12,000km). Next we designed an algorithm that alerted, up to three seconds before they occurred, about upcoming lane deviations that exceeded 0.2m. The sensitivity of the algorithm was 47% and the specificity was 71%. To our knowledge this exceeds the performance of the current video-based systems. Copyright © 2016 Elsevier Ltd. All rights reserved.

Lane-changing model with dynamic consideration of driver's propensity

NASA Astrophysics Data System (ADS)

Wang, Xiaoyuan; Wang, Jianqiang; Zhang, Jinglei; Ban, Xuegang Jeff

2015-07-01

Lane-changing is the driver's selection result of the satisfaction degree in different lane driving conditions. There are many different factors influencing lane-changing behavior, such as diversity, randomicity and difficulty of measurement. So it is hard to accurately reflect the uncertainty of drivers' lane-changing behavior. As a result, the research of lane-changing models is behind that of car-following models. Driver's propensity is her/his emotion state or the corresponding preference of a decision or action toward the real objective traffic situations under the influence of various dynamic factors. It represents the psychological characteristics of the driver in the process of vehicle operation and movement. It is an important factor to influence lane-changing. In this paper, dynamic recognition of driver's propensity is considered during simulation based on its time-varying discipline and the analysis of the driver's psycho-physic characteristics. The Analytic Hierarchy Process (AHP) method is used to quantify the hierarchy of driver's dynamic lane-changing decision-making process, especially the influence of the propensity. The model is validated using real data. Test results show that the developed lane-changing model with the dynamic consideration of a driver's time-varying propensity and the AHP method are feasible and with improved accuracy.

Why is walker-assisted gait metabolically expensive?

PubMed

Priebe, Jonathon R; Kram, Rodger

2011-06-01

Walker-assisted gait is reported to be ∼200% more metabolically expensive than normal bipedal walking. However, previous studies compared different walking speeds. Here, we compared the metabolic power consumption and basic stride temporal-spatial parameters for 10 young, healthy adults walking without assistance and using 2-wheeled (2W), 4-wheeled (4W) and 4-footed (4F) walker devices, all at the same speed, 0.30m/s. We also measured the metabolic power demand for walking without any assistive device using a step-to gait at 0.30m/s, walking normally at 1.25m/s, and for repeated lifting of the 4F walker mimicking the lifting pattern used during 4F walker-assisted gait. Similar to previous studies, we found that the cost per distance walked was 217% greater with a 4F walker at 0.30m/s compared to unassisted, bipedal walking at 1.25m/s. Compared at the same speed, 0.30m/s, using a 4F walker was still 82%, 74%, and 55% energetically more expensive than walking unassisted, with a 4W walker and a 2W walker respectively. The sum of the metabolic cost of step-to walking plus the cost of lifting itself was equivalent to the cost of walking with a 4F walker. Thus, we deduce that the high cost of 4F walker assisted gait is due to three factors: the slow walking speed, the step-to gait pattern and the repeated lifting of the walker. Copyright © 2011 Elsevier B.V. All rights reserved.

A walker with a device of partial suspension for patients with gait disturbance: body weight supported walker.

PubMed

Ochi, Mitsuhiro; Makino, Kenichiro; Wada, Futoshi; Saeki, Satoru; Hachisuka, Kenji

2009-09-01

We developed a walker, the Body Weight Supported (BWS) Walker, with a device of partial suspension for patients with gait disturbance. It consists of a light frame with casters, a harness, and a winch system. One therapist alone can perform gait training safely with the BWS Walker without any additional physical load, even if a patient has severe gait disturbance, and the therapist can concentrate on evaluating and improving the patient' s standing balance and gait pattern. Because the BWS Walker is less expensive, simpler, and easier to operate than other BWS systems, we believe the BWS Walker can be widely applicable in training for patients with severe and moderate gait disturbance.

Lane detection based on color probability model and fuzzy clustering

NASA Astrophysics Data System (ADS)

Yu, Yang; Jo, Kang-Hyun

2018-04-01

In the vehicle driver assistance systems, the accuracy and speed of lane line detection are the most important. This paper is based on color probability model and Fuzzy Local Information C-Means (FLICM) clustering algorithm. The Hough transform and the constraints of structural road are used to detect the lane line accurately. The global map of the lane line is drawn by the lane curve fitting equation. The experimental results show that the algorithm has good robustness.

Driver Behavior During Overtaking Maneuvers from the 100-Car Naturalistic Driving Study.

PubMed

Chen, Rong; Kusano, Kristofer D; Gabler, Hampton C

2015-01-01

Lane changes with the intention to overtake the vehicle in front are especially challenging scenarios for forward collision warning (FCW) designs. These overtaking maneuvers can occur at high relative vehicle speeds and often involve no brake and/or turn signal application. Therefore, overtaking presents the potential of erroneously triggering the FCW. A better understanding of driver behavior during lane change events can improve designs of this human-machine interface and increase driver acceptance of FCW. The objective of this study was to aid FCW design by characterizing driver behavior during lane change events using naturalistic driving study data. The analysis was based on data from the 100-Car Naturalistic Driving Study, collected by the Virginia Tech Transportation Institute. The 100-Car study contains approximately 1.2 million vehicle miles of driving and 43,000 h of data collected from 108 primary drivers. In order to identify overtaking maneuvers from a large sample of driving data, an algorithm to automatically identify overtaking events was developed. The lead vehicle and minimum time to collision (TTC) at the start of lane change events was identified using radar processing techniques developed in a previous study. The lane change identification algorithm was validated against video analysis, which manually identified 1,425 lane change events from approximately 126 full trips. Forty-five drivers with valid time series data were selected from the 100-Car study. From the sample of drivers, our algorithm identified 326,238 lane change events. A total of 90,639 lane change events were found to involve a closing lead vehicle. Lane change events were evenly distributed between left side and right side lane changes. The characterization of lane change frequency and minimum TTC was divided into 10 mph speed bins for vehicle travel speeds between 10 and 90 mph. For all lane change events with a closing lead vehicle, the results showed that drivers change lanes most frequently in the 40-50 mph speed range. Minimum TTC was found to increase with travel speed. The variability in minimum TTC between drivers also increased with travel speed. This study developed and validated an algorithm to detect lane change events in the 100-Car Naturalistic Driving Study and characterized lane change events in the database. The characterization of driver behavior in lane change events showed that driver lane change frequency and minimum TTC vary with travel speed. The characterization of overtaking maneuvers from this study will aid in improving the overall effectiveness of FCW systems by providing active safety system designers with further understanding of driver action in overtaking maneuvers, thereby increasing system warning accuracy, reducing erroneous warnings, and improving driver acceptance.

A Real-Time System for Lane Detection Based on FPGA and DSP

NASA Astrophysics Data System (ADS)

Xiao, Jing; Li, Shutao; Sun, Bin

2016-12-01

This paper presents a real-time lane detection system including edge detection and improved Hough Transform based lane detection algorithm and its hardware implementation with field programmable gate array (FPGA) and digital signal processor (DSP). Firstly, gradient amplitude and direction information are combined to extract lane edge information. Then, the information is used to determine the region of interest. Finally, the lanes are extracted by using improved Hough Transform. The image processing module of the system consists of FPGA and DSP. Particularly, the algorithms implemented in FPGA are working in pipeline and processing in parallel so that the system can run in real-time. In addition, DSP realizes lane line extraction and display function with an improved Hough Transform. The experimental results show that the proposed system is able to detect lanes under different road situations efficiently and effectively.

Crash prediction method for freeway facilities with high occupancy vehicle (HOV) and high occupancy toll (HOT) lanes.

DOT National Transportation Integrated Search

2015-07-01

This study developed methods for estimating the expected crash frequency of urban freeway segments : with HOV or HOT lanes. The safety impacts of the type of separation between the managed lanes and : general purpose lanes were examined. Separate mod...

Signing and pavement marking for concurrent-flow high-occupancy-vehicle lanes : summary of current practice

DOT National Transportation Integrated Search

1997-01-01

Concurrent-flow lanes account for more than half of existing high-occupancy-vehicle (HOV) mileage in the United States. Traffic on this type of HOV lane operates in the same direction as the adjacent traffic, typically in the far-left lane. Limited n...

Crash Models For Rural Intersections: Four-Lane By Two-Lane Stop-Controlled And Two-Lane By Two-Lane Signalized

DOT National Transportation Integrated Search

1999-10-01

This report describes the collection, analysis, and modeling of crash and roadway data for intersections on rural roads in California and Michigan for the years 1993-1995. Three classes of intersections are considered: (1) three-legged intersections ...

A high accuracy vehicle positioning system implemented in a lane assistance system when GPS Is unavailable.

DOT National Transportation Integrated Search

2011-07-01

The use of lane assistance systems can reduce the stress levels experienced by drivers and allow for better lane : keeping in narrow, bus-dedicated lanes. In 2008, the Intelligent Vehicles (IV) Lab at the University of Minnesota : has developed such ...

Development and Evaluation of Lane-By-Lane Gap-Out Based Actuated Traffic Signal Control

DOT National Transportation Integrated Search

2012-09-01

Actuated traffic signal controls at isolated intersections largely benefit from gap-out and phase skip features as they allow : unused green times to be re-allocated to those movements need them. A few studies indicated that lane-by-lane gap-out : sh...

Adult manifestation of the Dandy-Walker syndrome. Report of two cases with review of the literature.

PubMed

Unsgaard, G; Sand, T; Støvring, J; Ringkjøb, R

1987-01-01

Two cases of Dandy-Walker syndrome that became manifest in adult life are reported. A review of the literature of Dandy-Walker syndrome revealed 13 additional cases with onset in adult life and three cases that could not be differentiated from arachnoid cysts. While shunting is the primary treatment in infantile Dandy-Walker, the usual treatment of adult Dandy-Walker has been excision of the membrane covering the enlarged fourth ventricle. The outcome of our two cases treated with membrane excision indicates that primary shunting should also be tried in adult Dandy-Walker.

Effects of walker gender and observer gender on biological motion walking direction discrimination.

PubMed

Yang, Xiaoying; Cai, Peng; Jiang, Yi

2014-09-01

The ability to recognize the movements of other biological entities, such as whether a person is walking toward you, is essential for survival and social interaction. Previous studies have shown that the visual system is particularly sensitive to approaching biological motion. In this study, we examined whether the gender of walkers and observers influenced the walking direction discrimination of approaching point-light walkers in fine granularity. The observers were presented a walker who walked in different directions and were asked to quickly judge the walking direction (left or right). The results showed that the observers demonstrated worse direction discrimination when the walker was depicted as male than when the walker was depicted as female, probably because the observers tended to perceive the male walkers as walking straight ahead. Intriguingly, male observers performed better than female observers at judging the walking directions of female walkers but not those of male walkers, a result indicating perceptual advantage with evolutionary significance. These findings provide strong evidence that the gender of walkers and observers modulates biological motion perception and that an adaptive perceptual mechanism exists in the visual system to facilitate the survival of social organisms. © 2014 The Institute of Psychology, Chinese Academy of Sciences and Wiley Publishing Asia Pty Ltd.

Cross-Cultural Investigation of Male Gait Perception in Relation to Physical Strength and Speed

PubMed Central

Fink, Bernhard; Wübker, Marieke; Ostner, Julia; Butovskaya, Marina L.; Mezentseva, Anna; Muñoz-Reyes, José Antonio; Sela, Yael; Shackelford, Todd K.

2017-01-01

Previous research documents that men and women can accurately judge male physical strength from gait, but also that the sexes differ in attractiveness judgments of strong and weak male walkers. Women’s (but not men’s) attractiveness assessments of strong male walkers are higher than for weak male walkers. Here, we extend this research to assessments of strong and weak male walkers in Chile, Germany, and Russia. Men and women judged videos of virtual characters, animated with the walk movements of motion-captured men, on strength and attractiveness. In two countries (Germany and Russia), these videos were additionally presented at 70% (slower) and 130% (faster) of their original speed. Stronger walkers were judged to be stronger and more attractive than weak walkers, and this effect was independent of country (but not sex). Women tended to provide higher attractiveness judgments to strong walkers, and men tended to provide higher attractiveness judgments to weak walkers. In addition, German and Russian participants rated strong walkers most attractive at slow and fast speed. Thus, across countries men and women can assess male strength from gait, although they tended to differ in attractiveness assessments of strong and weak male walkers. Attractiveness assessments of male gait may be influenced by society-specific emphasis on male physical strength. PMID:28878720

Comparison of bird community indices for riparian restoration planning and monitoring

USGS Publications Warehouse

Young, Jock S.; Ammon, Elisabeth M.; Weisburg, Peter J.; Dilts, Thomas E.; Newton, Wesley E.; Wong-Kone, Diane C.; Heki, Lisa G.

2013-01-01

The use of a bird community index that characterizes ecosystem integrity is very attractive to conservation planners and habitat managers, particularly in the absence of any single focal species. In riparian areas of the western USA, several attempts at arriving at a community index signifying a functioning riparian bird community have been made previously, mostly resorting to expert opinions or national conservation rankings for species weights. Because extensive local and regional bird monitoring data were available for Nevada, we were able to develop three different indices that were derived empirically, rather than from expert opinion. We formally examined the use of three species weighting schemes in comparison with simple species richness, using different definitions of riparian species assemblage size, for the purpose of predicting community response to changes in vegetation structure from riparian restoration. For the three indices, species were weighted according to the following criteria: (1) the degree of riparian habitat specialization based on regional data, (2) the relative conservation ranking of landbird species, and (3) the degree to which a species is under-represented compared to the regional species pool for riparian areas. To evaluate the usefulness of these indices for habitat restoration planning and monitoring, we modeled them using habitat variables that are expected to respond to riparian restoration efforts, using data from 64 sampling sites in the Walker River Basin in Nevada and California. We found that none of the species-weighting schemes performed any better as an index for evaluating overall habitat condition than using species richness alone as a community index. Based on our findings, the use of a fairly complete list of 30–35 riparian specialists appears to be the best indicator group for predicting the response of bird communities to the restoration of riparian vegetation.

23 CFR 810.104 - Applicability of other provisions.

Code of Federal Regulations, 2012 CFR

2012-04-01

... are reserved exclusively for use by carpool and vanpool passengers and vehicles. (e) As required by... for a physical construction or resurfacing project having a carpool lane(s) within the project limits may not be granted unless the project allows the use of the carpool lane(s) by motorcycles or it is...

23 CFR 810.104 - Applicability of other provisions.

Code of Federal Regulations, 2013 CFR

2013-04-01

... are reserved exclusively for use by carpool and vanpool passengers and vehicles. (e) As required by... for a physical construction or resurfacing project having a carpool lane(s) within the project limits may not be granted unless the project allows the use of the carpool lane(s) by motorcycles or it is...

23 CFR 810.104 - Applicability of other provisions.

Code of Federal Regulations, 2014 CFR

2014-04-01

... are reserved exclusively for use by carpool and vanpool passengers and vehicles. (e) As required by... for a physical construction or resurfacing project having a carpool lane(s) within the project limits may not be granted unless the project allows the use of the carpool lane(s) by motorcycles or it is...

23 CFR 810.104 - Applicability of other provisions.

Code of Federal Regulations, 2011 CFR

2011-04-01

... are reserved exclusively for use by carpool and vanpool passengers and vehicles. (e) As required by... for a physical construction or resurfacing project having a carpool lane(s) within the project limits may not be granted unless the project allows the use of the carpool lane(s) by motorcycles or it is...

Safety evaluation of signal installation with and without left turn lanes on two lane roads in rural and suburban areas.

DOT National Transportation Integrated Search

2014-10-01

Data from 117 intersections on two lane roads in rural and suburban areas in North Carolina were used to determine the safety : effect of signalization with and without left turn lanes. This was a before-after study that was conducted using the empir...

Motion of Skyrmions in Well-Separated Two-Lane Racetracks

NASA Astrophysics Data System (ADS)

Lai, P.; Zhao, G. P.; Morvan, F. J.; Wu, S. Q.; Ran, N.

Magnetic skyrmions are topological structures which can be used to store information as data bits in metallic racetrack memories. Their good properties, such as their stability, small size and low currents needed to drive them make them better candidates than traditional magnetic domain walls for the building of the next generation data storage. A skyrmion racetrack memory has been suggested, with the binary data encoded in the distance between skyrmions when the racetrack is a single lane. Here, we propose a new skyrmion-based two-lane racetrack structure separated by a high-K (high magnetocrystalline anisotropy) middle lane, which confines the skyrmions in their respective lanes. This design gives a new data presentation for the skyrmions on the racetrack. Phase diagrams for the skyrmion motion on the proposed racetrack as functions of the current density, middle lane anisotropy, middle lane width and DMI constant have been calculated and given, demonstrating that skyrmions can be driven in different lanes of the racetrack. This design offers the possibility of building an ultrafast and energy-efficient skyrmion transport device.

Road Lane Detection Robust to Shadows Based on a Fuzzy System Using a Visible Light Camera Sensor

PubMed Central

Hoang, Toan Minh; Baek, Na Rae; Cho, Se Woon; Kim, Ki Wan; Park, Kang Ryoung

2017-01-01

Recently, autonomous vehicles, particularly self-driving cars, have received significant attention owing to rapid advancements in sensor and computation technologies. In addition to traffic sign recognition, road lane detection is one of the most important factors used in lane departure warning systems and autonomous vehicles for maintaining the safety of semi-autonomous and fully autonomous systems. Unlike traffic signs, road lanes are easily damaged by both internal and external factors such as road quality, occlusion (traffic on the road), weather conditions, and illumination (shadows from objects such as cars, trees, and buildings). Obtaining clear road lane markings for recognition processing is a difficult challenge. Therefore, we propose a method to overcome various illumination problems, particularly severe shadows, by using fuzzy system and line segment detector algorithms to obtain better results for detecting road lanes by a visible light camera sensor. Experimental results from three open databases, Caltech dataset, Santiago Lanes dataset (SLD), and Road Marking dataset, showed that our method outperformed conventional lane detection methods. PMID:29143764

Lane detection using Randomized Hough Transform

NASA Astrophysics Data System (ADS)

Mongkonyong, Peerawat; Nuthong, Chaiwat; Siddhichai, Supakorn; Yamakita, Masaki

2018-01-01

According to the report of the Royal Thai Police between 2006 and 2015, lane changing without consciousness is one of the most accident causes. To solve this problem, many methods are considered. Lane Departure Warning System (LDWS) is considered to be one of the potential solutions. LDWS is a mechanism designed to warn the driver when the vehicle begins to move out of its current lane. LDWS contains many parts including lane boundary detection, driver warning and lane marker tracking. This article focuses on the lane boundary detection part. The proposed lane boundary detection detects the lines of the image from the input video and selects the lane marker of the road surface from those lines. Standard Hough Transform (SHT) and Randomized Hough Transform (RHT) are considered in this article. They are used to extract lines of an image. SHT extracts the lines from all of the edge pixels. RHT extracts only the lines randomly picked by the point pairs from edge pixels. RHT algorithm reduces the time and memory usage when compared with SHT. The increase of the threshold value in RHT will increase the voted limit of the line that has a high possibility to be the lane marker, but it also consumes the time and memory. By comparison between SHT and RHT with the different threshold values, 500 frames of input video from the front car camera will be processed. The accuracy and the computational time of RHT are similar to those of SHT in the result of the comparison.

Impact of age and cognitive demand on lane choice and changing under actual highway conditions.

PubMed

Reimer, Bryan; Donmez, Birsen; Lavallière, Martin; Mehler, Bruce; Coughlin, Joseph F; Teasdale, Normand

2013-03-01

Previous research suggests that drivers change lanes less frequently during periods of heightened cognitive load. However, lane changing behavior of different age groups under varying levels of cognitive demand is not well understood. The majority of studies which have evaluated lane changing behavior under cognitive workload have been conducted in driving simulators. Consequently, it is unclear if the patterns observed in these simulation studies carry over to actual driving. This paper evaluates data from an on-road study to determine the effects of age and cognitive demand on lane choice and lane changing behavior. Three age groups (20-29, 40-49, and 60-69) were monitored in an instrumented vehicle. The 40's age group had 147% higher odds of exhibiting a lane change than the 60's group. In addition, drivers in their 60's were less likely to drive on the leftmost lane compared to drivers in their 20's and 40's. These results could be interpreted as evidence that older adults adopt a more conservative driving style as reflected in being less likely to choose the leftmost lane than the younger groups and less likely to change lanes than drivers in their 40's. Regardless of demand level, cognitive workload reduced the frequency of lane changes for all age groups. This suggests that in general drivers of all ages attempt to regulate their behavior in a risk reducing direction when under added cognitive demand. The extent to which such self-regulation fully compensates for the impact of added cognitive demand remains an open question. Copyright © 2012 Elsevier Ltd. All rights reserved.

"Bicycles May Use Full Lane" Signage Communicates U.S. Roadway Rules and Increases Perception of Safety.

PubMed

Hess, George; Peterson, M Nils

2015-01-01

Many global challenges, including obesity, health care costs, and climate change, could be addressed in part by increasing the use of bicycles for transportation. Concern about the safety of bicycling on roadways is frequently cited as a deterrent to increasing bicycle use in the USA. The use of effective signage along roadways might help alleviate these concerns by increasing knowledge about the rights and duties of bicyclists and motorists, ideally reducing crashes. We administered a web-based survey, using Twitter for recruitment, to examine how well three US traffic control devices communicated the message that bicyclists are permitted in the center of the travel lane and do not have to "get out of the way" to allow motorists to pass without changing lanes: "Bicycles May Use Full Lane" and "Share the Road" signage, and Shared Lane Markings on the pavement. Each was compared to an unsigned roadway. We also asked respondents whether it was safe for a bicyclist to occupy the center of the travel lane. "Bicycles May Use Full Lane" signage was the most consistently comprehended device for communicating the message that bicyclists may occupy the travel lane and also increased perceptions of safety. "Share the Road" signage did not increase comprehension or perceptions of safety. Shared Lane Markings fell somewhere between. "Bicycles May Use Full Lane" signage showed notable increases in comprehension among novice bicyclists and private motor vehicle commuters, critical target audiences for efforts to promote bicycling in the USA. Although limited in scope, our survey results are indicative and suggest that Departments of Transportation consider replacing "Share the Road" with "Bicycles May Use Full Lane" signage, possibly combined with Shared Lane Markings, if the intent is to increase awareness of roadway rights and responsibilities. Further evaluation through virtual reality simulations and on-road experiments is merited.

Vertical force and wrist deviation angle when using a walker to stand up and sit down.

PubMed

Leung, Cherng-Yee; Yeh, Po-Chan

2011-08-01

Research investigating walkers suggests that safety and assistance for the elderly with weak lower limbs were important. However, the relationship between the use of a walker and the upper limbs has received little investigation. Standing up and sitting down are important daily activities. Therefore, the aim of this study was to explore wrist deviation and vertical force among elderly individuals using a walker for assistance to stand up and sit down. In total, 64 elderly volunteers (M age = 80.22, SD = 9.36) were enrolled. Data were obtained from four load cells and a twin-axis wrist goniometer. Wrist deviation and vertical force were examined when participants used a walker with horizontal handles to assist in standing up and sitting down. Significant wrist angle deviation occurred with the use of a walker, with dorsiflexion of the right hand greater than that of the left. Males exerted significantly greater vertical force. In the sitting position, greater ulnar deviation was seen among experienced walker users, whereas during standing, experienced users exhibited greater dorsiflexion. The horizontal handles of most marketed walkers may cause user wrist deviations, suggesting researchers should pursue improvements in walker design.

The effects of texting on driving performance in a driving simulator: the influence of driver age.

PubMed

Rumschlag, Gordon; Palumbo, Theresa; Martin, Amber; Head, Doreen; George, Rajiv; Commissaris, Randall L

2015-01-01

Distracted driving is a significant contributor to motor vehicle accidents and fatalities, and texting is a particularly significant form of driver distraction that continues to be on the rise. The present study examined the influence of driver age (18-59 years old) and other factors on the disruptive effects of texting on simulated driving behavior. While 'driving' the simulator, subjects were engaged in a series of brief text conversations with a member of the research team. The primary dependent variable was the occurrence of Lane Excursions (defined as any time the center of the vehicle moved outside the directed driving lane, e.g., into the lane for oncoming traffic or onto the shoulder of the road), measured as (1) the percent of subjects that exhibited Lane Excursions, (2) the number of Lane Excursions occurring and (3) the percent of the texting time in Lane Excursions. Multiple Regression analyses were used to assess the influence of several factors on driving performance while texting, including text task duration, texting skill level (subject-reported), texting history (#texts/week), driver gender and driver age. Lane Excursions were not observed in the absence of texting, but 66% of subjects overall exhibited Lane Excursions while texting. Multiple Regression analysis for all subjects (N=50) revealed that text task duration was significantly correlated with the number of Lane Excursions, and texting skill level and driver age were significantly correlated with the percent of subjects exhibiting Lane Excursions. Driver gender was not significantly correlated with Lane Excursions during texting. Multiple Regression analysis of only highly skilled texters (N=27) revealed that driver age was significantly correlated with the number of Lane Excursions, the percent of subjects exhibiting Lane Excursions and the percent of texting time in Lane Excursions. In contrast, Multiple Regression analysis of those drivers who self-identified as not highly skilled texters (N=23) revealed that text task duration was significantly correlated with the number of Lane Excursions. The present studies confirm past reports that texting impairs driving simulator performance. Moreover, the present study demonstrates that for highly skilled texters, the effects of texting on driving are actually worse for older drivers. Given the increasing frequency of texting while driving within virtually all age groups, these data suggest that 'no texting while driving' education and public service messages need to be continued, and they should be expanded to target older drivers as well. Copyright © 2014 Elsevier Ltd. All rights reserved.

Visible/near-infrared subdiffraction imaging reveals the stochastic nature of DNA walkers

PubMed Central

Pan, Jing; Cha, Tae-Gon; Li, Feiran; Chen, Haorong; Bragg, Nina A.; Choi, Jong Hyun

2017-01-01

DNA walkers are designed with the structural specificity and functional diversity of oligonucleotides to actively convert chemical energy into mechanical translocation. Compared to natural protein motors, DNA walkers’ small translocation distance (mostly <100 nm) and slow reaction rate (<0.1 nm s−1) make single-molecule characterization of their kinetics elusive. An important indication of single-walker kinetics is the rate-limiting reactions that a particular walker design bears. We introduce an integrated super-resolved fluorescence microscopy approach that is capable of long-term imaging to investigate the stochastic behavior of DNA walkers. Subdiffraction tracking and imaging in the visible and second near-infrared spectra resolve walker structure and reaction rates. The distributions of walker kinetics are analyzed using a stochastic model to reveal reaction randomness and the rate-limiting biochemical reaction steps. PMID:28116353

Impact of strut height on offloading capacity of removable cast walkers.

PubMed

Crews, Ryan T; Sayeed, Fraaz; Najafi, Bijan

2012-08-01

Reducing weight-bearing stress to diabetic foot ulcers is critical to healing and commonly called offloading. Removable cast walkers are frequently used for offloading; however, patient compliance is often poor. Walkers commonly extend to the knee. Patients complain about walkers' weight and diminished balance with their use. This study compared the offloading capacity of walkers that varied by height. Heights included: knee, ankle, and shoe levels. To ensure a fair comparison the outsole and insole were standardized across the devices. Eleven diabetic subjects with moderate to high risk of ulceration were recruited. Subjects completed four 20 m walking trials. Subjects performed one trial with each walker and one trial with an athletic shoe. Primary outcomes focused on plantar loading and were measured by pressure insoles. Secondary outcomes were associated with gait kinematics as collected by body worn sensors. Significant differences were found for the peak pressure and pressure time integrals of the different footwear. All walkers performed better than the athletic shoe. The ankle and knee-high devices performed best. Center of mass rotation data showed a trend of the ankle walker yielding a smaller range of motion (18% medial/lateral and 22% anterior/posterior) than the knee level. The ankle-high walker was able to provide similar offloading capacities as the knee-high walker. The diminished weight, along with potentially improved stability, may result in improved compliance with ankle-high walkers. A study comparing the use of the two devices for treating ulcers is now suggested. Copyright © 2012 Elsevier Ltd. All rights reserved.

Alternative Fuels Data Center

Science.gov Websites

miles per hour. To operate in HOV lanes, PEV owners must obtain a permit, not to exceed $20, from the High Occupancy Vehicle (HOV) Lane Exemption Permitted PEVs may operate in Maryland HOV lanes report PEV use in HOV lanes to the governor. This exemption expires September 30, 2019. For more

Managed lane operations--adjusted time of day pricing vs. near-real time dynamic pricing : volume I, dynamic pricing and operations of managed lanes.

DOT National Transportation Integrated Search

2012-02-12

In 2008, the Florida Department of Transportation began implementing the 95 Express, a segment of I-95 in Miami with high occupancy toll (HOT) lanes. Some vehicles use HOT lanes free, but most vehicles pay a toll based on real-time traffic conditions...

Towards a Possible Therapy for Diabetes Complications

DTIC Science & Technology

2012-10-01

with 8M Urea , 10% NP40; Lane 2 with 0.5 M Sodium Acetate pH 4.5. In lane 3 the beads had not been treated with cell lysate. Right Panel. Retention...8M urea 10% NP40 wash (lane 1) than with 0.5 M sodium acetate pH 4.5 (lane 2). Lane 3 is the modified C-peptide run in the gel as a control... Urea , 10% NP40 appears to be effective in reducing the retention of non-specific hydrophobic proteins by the magnetic beads without dislodging the

78 FR 48301 - Establishment of Class E Airspace; Walker, MN

Federal Register 2010, 2011, 2012, 2013, 2014

2013-08-08

...-0266; Airspace Docket No. 13-AGL-11] Establishment of Class E Airspace; Walker, MN AGENCY: Federal... at Walker, MN. Controlled airspace is necessary to accommodate new Area Navigation (RNAV) Standard Instrument Approach Procedures at Walker Municipal Airport. The FAA is taking this action to enhance the...

75 FR 51178 - Safety Standard for Infant Walkers; Correction

Federal Register 2010, 2011, 2012, 2013, 2014

2010-08-19

... provision concerning warning statements on walkers with parking brakes. DATES: Effective on December 21... the last sentence. Another provision, at Sec. 1216.2(b)(21)(i), concerning a warning statement for walkers with parking brakes omitted a phrase indicating that the warning is only required for walkers that...

Bedrock geologic map of the Yucca Mountain area, Nye County, Nevada

USGS Publications Warehouse

Day, Warren C.; Dickerson, Robert P.; Potter, Christopher J.; Sweetkind, Donald S.; San Juan, Carma A.; Drake, Ronald M.; Fridrich, Christopher J.

1998-01-01

Yucca Mountain, Nye County, Nevada, has been identified as a potential site for underground storage of high-level radioactive nuclear waste. Detailed bedrock geologic maps form an integral part of the site characterization program by providing the fundamental framework for research into the geologic hazards and hydrologic behavior of the mountain. This bedrock geologic map provides the geologic framework and structural setting for the area in and adjacent to the site of the potential repository. The study area comprises the northern and central parts of Yucca Mountain, located on the southern flank of the Timber Mountain-Oasis Valley caldera complex, which was the source for many of the volcanic units in the area. The Timber Mountain-Oasis Valley caldera complex is part of the Miocene southwestern Nevada volcanic field, which is within the Walker Lane belt. This tectonic belt is a northwest-striking megastructure lying between the more active Inyo-Mono and Basin-and-Range subsections of the southwestern Great Basin.Excluding Quaternary surficial deposits, the map area is underlain by Miocene volcanic rocks, principally ash-flow tuffs with lesser amounts of lava flows. These volcanic units include the Crater Flat Group, the Calico Hills Formation, the Paintbrush Group, and the Timber Mountain Group, as well as minor basaltic dikes. The tuffs and lava flows are predominantly rhyolite with lesser amounts of latite and range in age from 13.4 to 11.6 Ma. The 10-Ma basaltic dikes intruded along a few fault traces in the north-central part of the study area. Fault types in the area can be classified as block bounding, relay structures, strike slip, and intrablock. The block-bounding faults separate the 1- to 4-km-wide, east-dipping structural blocks and exhibit hundreds of meters of displacement. The relay structures are northwest-striking normal fault zones that kinematically link the block-bounding faults. The strike-slip faults are steep, northwest-striking dextral faults located in the northern part of Yucca Mountain. The intrablock faults are modest faults of limited offset (tens of meters) and trace length (less than 7 km) that accommodated intrablock deformation.The concept of structural domains provides a useful tool in delineating and describing variations in structural style. Domains are defined across the study area on the basis of the relative amount of internal faulting, style of deformation, and stratal dips. In general, there is a systematic north to south increase in extensional deformation as recorded in the amount of offset along the block-bounding faults as well as an increase in the intrablock faulting.The rocks in the map area had a protracted history of Tertiary extension. Rocks of the Paintbrush Group cover much of the area and obscure evidence for older tectonism. An earlier history of Tertiary extension can be inferred, however, because the Timber Mountain-Oasis Valley caldera complex lies within and cuts an older north-trending rift (the Kawich-Greenwater rift}. Evidence for deformation during eruption of the Paintbrush Group is locally present as growth structures. Post-Paintbrush Group, pre-Timber Mountain Group extension occurred along the block-bounding faults. The basal contact of the 11.6-Ma Rainier Mesa Tuff of the Timber Mountain Group provides a key time horizon throughout the area. Other workers have shown that west of the study area in northern Crater Flat the basal angular unconformity is as much as 20° between the Rainier Mesa and underlying Paintbrush Group rocks. In the westernmost part of the study area the unconformity is smaller (less than 10°), whereas in the central and eastern parts of the map area the contact is essentially conformable. In the central part of the map the Rainier Mesa Tuff laps over fault splays within the Solitario Canyon fault zone. However, displacement did occur on the block-bounding faults after deposition of the Rainier Mesa Tuff inasmuch as it is locally caught up in the hanging-wall deformation of the block-bounding faults. Therefore, the regional Tertiary to Recent extension was protracted, occurring prior to and after the eruption of the tuffs exposed at Yucca Mountain.

Agile Walker.

PubMed

Katz, Reuven

2015-01-01

The goal of the Agile Walker is to improve the outdoor mobility of healthy elderly people with some mobility limitations. It is a newly developed, all-terrain walker, equipped with an electric drive system and speed control that can assists elderly people to walk outdoors or to hike. The walker has a unique product design with an attractive look that will appeal to "active-agers" population. This paper describes product design requirements and the development process of the Agile Walker, its features and some preliminary testing results.

A driving simulator study of driver performance on deceleration lanes.

PubMed

Calvi, A; Benedetto, A; De Blasiis, M R

2012-03-01

Deceleration lanes are important because they help drivers transition from high-speed lanes to low-speed ramps. Although they are designed to allow vehicles to depart the freeway safely and efficiently, many studies report high accident rates on exit ramps with the highest percentage of crashes taking place in deceleration lanes. This paper describes the results of a driving simulator study that focused on driving performance while approaching a divergence area and decelerating during the exiting maneuver. Three different traffic scenarios were simulated to analyze the influence of traffic volume on driving performance. Thirty drivers drove in the simulator in these scenarios while data on their lateral position, speed and deceleration were collected. Our results indicate there are considerable differences between the main assumptions of models generally used to design deceleration lanes and actual driving performance. In particular, diverging drivers begin to decelerate before arriving at the deceleration lane, causing interference with the main flow. Moreover, speeds recorded at the end of the deceleration lane exceed those for which the ramp's curves are designed; this creates risky driving conditions that could explain the high crash rates found in studies of exit ramps. Finally, statistical analyses demonstrate significant influences of traffic volume on some aspects of exiting drivers' performance: lower traffic volume results in elevated exiting speed and deceleration, and diverging drivers begin to decelerate earlier along the main lane when traffic volume is low. However, speeds at the end of the deceleration lane and the site of lane changing are not significantly influenced by traffic volume. Copyright © 2011 Elsevier Ltd. All rights reserved.

LCP method for a planar passive dynamic walker based on an event-driven scheme

NASA Astrophysics Data System (ADS)

Zheng, Xu-Dong; Wang, Qi

2018-06-01

The main purpose of this paper is to present a linear complementarity problem (LCP) method for a planar passive dynamic walker with round feet based on an event-driven scheme. The passive dynamic walker is treated as a planar multi-rigid-body system. The dynamic equations of the passive dynamic walker are obtained by using Lagrange's equations of the second kind. The normal forces and frictional forces acting on the feet of the passive walker are described based on a modified Hertz contact model and Coulomb's law of dry friction. The state transition problem of stick-slip between feet and floor is formulated as an LCP, which is solved with an event-driven scheme. Finally, to validate the methodology, four gaits of the walker are simulated: the stance leg neither slips nor bounces; the stance leg slips without bouncing; the stance leg bounces without slipping; the walker stands after walking several steps.

LCP method for a planar passive dynamic walker based on an event-driven scheme

NASA Astrophysics Data System (ADS)

Zheng, Xu-Dong; Wang, Qi

2018-02-01

The main purpose of this paper is to present a linear complementarity problem (LCP) method for a planar passive dynamic walker with round feet based on an event-driven scheme. The passive dynamic walker is treated as a planar multi-rigid-body system. The dynamic equations of the passive dynamic walker are obtained by using Lagrange's equations of the second kind. The normal forces and frictional forces acting on the feet of the passive walker are described based on a modified Hertz contact model and Coulomb's law of dry friction. The state transition problem of stick-slip between feet and floor is formulated as an LCP, which is solved with an event-driven scheme. Finally, to validate the methodology, four gaits of the walker are simulated: the stance leg neither slips nor bounces; the stance leg slips without bouncing; the stance leg bounces without slipping; the walker stands after walking several steps.

Designing instrumented walker to measure upper-extremity's efforts: A case study.

PubMed

Khodadadi, Mohammad; Baniasad, Mina Arab; Arazpour, Mokhtar; Farahmand, Farzam; Zohoor, Hassan

2018-02-26

The high prevalence of shoulder pain in using walkers in patients who have spinal cord injury (SCI). Also, the limited options available to economically measure grip forces in walkers, which drove the need to create one. This article describes a method to obtain upper-extremities' forces and moments in a person with SCI by designing an appropriate instrumented walker. First, since the commercial multidirectional loadcells are too expensive, custom loadcells are fabricated. Ultimately, a complete gait analysis by means of VICON motion analysis and using inverse dynamic method has been held to measure upper-extremities' efforts. The results for a person with SCI using a two-wheel walker in low and high heights and a basic walker show that there are higher shoulder and elbow flexion-extension moments and also higher shoulder forces in superior-inferior direction and higher elbow and wrist forces in anterior-posterior directions. The results are not much different in using two different types of walker. By using the proposed method, upper-extremities' forces and moments were obtained and the results were compared to each other in using two different walkers.

Vertical force and wrist deviation angle in a sample of elderly people using walkers.

PubMed

Leung, Cherng-Yee; Yeh, Po-Chan

2013-02-01

Walkers are frequently used by elderly people with weak lower limbs and limited balance, but the ergonomic relationship between the use of a walker and stress on the upper limbs is relatively unstudied. The current study assessed wrist deviation and vertical force among elderly individuals using a walker for assistance in walking. 60 elderly volunteers (M age = 81.0 yr., SD = 8.8) participated, 30 of whom frequently used a walker, and 30 who had no such prior experience. Data were obtained from four load cells and a twin-axis wrist goniometer during assisted ambulation using the walker. No significant group difference was found in gait cycle. Significant wrist deviation occurred, with ulnar deviation/dorsiflexion of the right hand, which was greater than that of the left. Non-experienced participants had larger dorsiflexion than experienced participants. Experienced participants produced larger vertical force than non-experienced participants. The greaterthe wrist deviation, the greater was the vertical force. The horizontal handles of most marketed walkers cause wrist deviations. This is a concern for users, clinicians, and related industries. Improvements in walker design should be considered.

Aging in mortal superdiffusive Lévy walkers.

PubMed

Stage, Helena

2017-12-01

A growing body of literature examines the effects of superdiffusive subballistic movement premeasurement (aging or time lag) on observations arising from single-particle tracking. A neglected aspect is the finite lifetime of these Lévy walkers, be they proteins, cells, or larger structures. We examine the effects of aging on the motility of mortal walkers, and discuss the means by which permanent stopping of walkers may be categorized as arising from "natural" death or experimental artifacts such as low photostability or radiation damage. This is done by comparison of the walkers' mean squared displacement (MSD) with the front velocity of propagation of a group of walkers, which is found to be invariant under time lags. For any running time distribution of a mortal random walker, the MSD is tempered by the stopping rate θ. This provides a physical interpretation for truncated heavy-tailed diffusion processes and serves as a tool by which to better classify the underlying running time distributions of random walkers. Tempering of aged MSDs raises the issue of misinterpreting superdiffusive motion which appears Brownian or subdiffusive over certain time scales.

Intelligent control of a smart walker and its performance evaluation.

PubMed

Grondin, Simon L; Li, Qingguo

2013-06-01

Recent technological advances have allowed the development of force-dependent, intelligently controlled smart walkers that are able to provide users with enhanced mobility, support and gait assistance. The purpose of this study was to develop an intelligent rule-based controller for a smart walker to achieve a smooth interaction between the user and the walker. This study developed a rule-based mapping between the interaction force, measured by a load cell attached to the walker handle, and the acceleration of the walker. Ten young, healthy subjects were used to evaluate the performance of the proposed controller compared to a well-known admittance-based control system. There were no significant differences between the two control systems concerning their user experience, velocity profiles or average cost of transportation. However, the admittance-based control system required a 1.2N lower average interaction force to maintain the 1m/s target speed (p = 0.002). Metabolic data also indicated that smart walker-assisted gait could considerably reduce the metabolic demand of walking with a four-legged walker.

Aging in mortal superdiffusive Lévy walkers

NASA Astrophysics Data System (ADS)

Stage, Helena

2017-12-01

A growing body of literature examines the effects of superdiffusive subballistic movement premeasurement (aging or time lag) on observations arising from single-particle tracking. A neglected aspect is the finite lifetime of these Lévy walkers, be they proteins, cells, or larger structures. We examine the effects of aging on the motility of mortal walkers, and discuss the means by which permanent stopping of walkers may be categorized as arising from "natural" death or experimental artifacts such as low photostability or radiation damage. This is done by comparison of the walkers' mean squared displacement (MSD) with the front velocity of propagation of a group of walkers, which is found to be invariant under time lags. For any running time distribution of a mortal random walker, the MSD is tempered by the stopping rate θ . This provides a physical interpretation for truncated heavy-tailed diffusion processes and serves as a tool by which to better classify the underlying running time distributions of random walkers. Tempering of aged MSDs raises the issue of misinterpreting superdiffusive motion which appears Brownian or subdiffusive over certain time scales.

a Novel Approach to Camera Calibration Method for Smart Phones Under Road Environment

NASA Astrophysics Data System (ADS)

Lee, Bijun; Zhou, Jian; Ye, Maosheng; Guo, Yuan

2016-06-01

Monocular vision-based lane departure warning system has been increasingly used in advanced driver assistance systems (ADAS). By the use of the lane mark detection and identification, we proposed an automatic and efficient camera calibration method for smart phones. At first, we can detect the lane marker feature in a perspective space and calculate edges of lane markers in image sequences. Second, because of the width of lane marker and road lane is fixed under the standard structural road environment, we can automatically build a transformation matrix between perspective space and 3D space and get a local map in vehicle coordinate system. In order to verify the validity of this method, we installed a smart phone in the `Tuzhi' self-driving car of Wuhan University and recorded more than 100km image data on the road in Wuhan. According to the result, we can calculate the positions of lane markers which are accurate enough for the self-driving car to run smoothly on the road.

Impacts of wireless charging lanes on travel time and energy consumption in a two-lane road system

NASA Astrophysics Data System (ADS)

He, Jia; Yang, Hai; Huang, Hai-Jun; Tang, Tie-Qiao

2018-06-01

In this paper, we propose a method to compare different energy consumption models and design a strategy to study the quantitative effects of wireless charging lane (WCL) on each electric vehicle's (EV's) link travel time. We utilize the modified energy consumption model and strategy to explore electric vehicle's electricity consumption and link travel time in a two-lane system with a WCL. The numerical results show that EVs' charging behavior on WCL will cause the drivers to execute the lane-changing maneuvers frequently and that the WCL has prominent impacts on EV's energy consumption and travel time, i.e., the capacity drops by 8%-17% while the EV's energy consumption increases by 3%-14% in the two-lane road system.

The use of baby walkers in Iranian infants.

PubMed

Shiva, F; Ghotbi, F; Yavari, S F

2010-08-01

A study was conducted to define the pattern of baby walker usage and the rate of walker-related injuries in infants, as well as to determine the effects of baby walkers on the start of independent walking among infants. Families of infants aged six months to two years who presented at health facility clinics in 2007 and 2008 were enrolled in the study. The study team interviewed the primary caregiver and documented the relevant data on a pre-designed questionnaire. The data of users of baby walkers was compared with that of non-users. Walkers were used by 54.5 percent of 414 infants. Their use was significantly higher in one-child families (p-value is 0.009) and in those with higher parental education levels (p-value is less than 0.001). 78.6 percent of users and 85 percent of non-users were walking by 12 months of age (p-value is 0.283); no significant difference was observed between the two groups in terms of the age at which the infants starting walking (p-value is 0.401). 76.8 percent of parents of users versus 8.2 percent of parents of non-users believed that walkers promote early walking (p-value is less than 0.001). 44.7 percent of parents of users knew that walkers can be hazardous, as compared to 22.3 percent of parents of non-users. No serious injury was reported, but 14.1 percent of infants sustained trivial walker-associated injuries. Baby walkers do not hasten independent walking and may be associated with injuries. However, it was noted that knowledge of the associated hazards has not deterred parents from using baby walkers for their infants.

An extended two-lane car-following model accounting for inter-vehicle communication

NASA Astrophysics Data System (ADS)

Ou, Hui; Tang, Tie-Qiao

2018-04-01

In this paper, we develop a novel car-following model with inter-vehicle communication to explore each vehicle's movement in a two-lane traffic system when an incident occurs on a lane. The numerical results show that the proposed model can perfectly describe each vehicle's motion when an incident occurs, i.e., no collision occurs while the classical full velocity difference (FVD) model produces collision on each lane, which shows the proposed model is more reasonable. The above results can help drivers to reasonably adjust their driving behaviors when an incident occurs in a two-lane traffic system.

76 FR 13665 - Arcelor Mittal, Formerly Known as Mittal Steel Walker Wire, a Subsidiary of Arcelor Mittal...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-03-14

... Known as Mittal Steel Walker Wire, a Subsidiary of Arcelor Mittal--Montreal, Including On-Site Leased... Steel Walker Wire, a subsidiary of Arcelor Mittal-- Montreal, including on-site leased workers from... Walker Wire, Inc., Ferndale, Michigan, separated from employment on or after July 23, 2006 through August...

STS-30 Commander Walker on forward flight deck

NASA Technical Reports Server (NTRS)

1989-01-01

On Atlantis', Orbiter Vehicle (OV) 104's, forward flight deck between commanders and pilots seats, STS-30 Commander David M. Walker smiles while having his picture taken. Walker, wearing a mission polo shirt and light blue flight coverall pants, holds onto the commanders seat back. Forward flight control panels are visible above Walker's head and behind him.

Factors Associated with Women's Antenatal Plans to Use a Baby Walker: A Cross Sectional Study

ERIC Educational Resources Information Center

Illingworth, Rachel; Kendrick, Denise; Collier, Jacqueline; Woods, Amanda; Wattse, Kim; Dewey, Michael; Chen, Chih-Mei

2006-01-01

Objective: The objective of these analyses was to explore maternal antenatal decisions about baby walker use, factors associated with these decisions and the relationship between antenatal plans to use a walker and postnatal walker use. Design: Cross sectional study. Setting: Mothers-to-be (n = 1174) participating in a cluster randomised…

A new species of Ormocerus Walker (Hymenoptera: Pteromalidae) from North America and a range expansion for Ormocerus latus Walker

USDA-ARS?s Scientific Manuscript database

Ormocerus dirigoius, n. sp. is described and compared to the North American O. americanus Dzhanokmen and Grissell and European species O. latus Walker and O. vernalis Walker. A range expansion into the Nearctic is reported for O. latus, previously only known from the Palearctic. Specimens were colle...

Recent progress on DNA based walkers.

PubMed

Pan, Jing; Li, Feiran; Cha, Tae-Gon; Chen, Haorong; Choi, Jong Hyun

2015-08-01

DNA based synthetic molecular walkers are reminiscent of biological protein motors. They are powered by hybridization with fuel strands, environment induced conformational transitions, and covalent chemistry of oligonucleotides. Recent developments in experimental techniques enable direct observation of individual walkers with high temporal and spatial resolution. The functionalities of state-of-the-art DNA walker systems can thus be analyzed for various applications. Herein we review recent progress on DNA walker principles and characterization methods, and evaluate various aspects of their functions for future applications. Copyright © 2014 Elsevier Ltd. All rights reserved.

A review of the functionalities of smart walkers.

PubMed

Martins, Maria; Santos, Cristina; Frizera, Anselmo; Ceres, Ramón

2015-10-01

There is a need to conceptualize and improve the investigation and developments in assistive devices, focusing on the design and effectiveness of walkers in the user's rehabilitation process and functional compensation. This review surveys the importance of smart walkers in maintaining mobility and discusses their potential in rehabilitation and their demands as assistive devices. It also presents related research in addressing and quantifying the smart walker's efficiency and influence on gait. Besides, it discusses smart walkers focusing on studies related to the concept of autonomous and shared-control and manual guidance, the use of smart walkers as personal helpers to sit-to-stand and diagnostic tools for patients' rehabilitation through the evaluation of their gait. Copyright © 2015 IPEM. Published by Elsevier Ltd. All rights reserved.

Quantifying MTBE biodegradation in the Vandenberg Air Force Base ethanol release study using stable carbon isotopes

NASA Astrophysics Data System (ADS)

McKelvie, Jennifer R.; Mackay, Douglas M.; de Sieyes, Nicholas R.; Lacrampe-Couloume, Georges; Sherwood Lollar, Barbara

2007-12-01

Compound-specific isotope analysis (CSIA) was used to assess biodegradation of MTBE and TBA during an ethanol release study at Vandenberg Air Force Base. Two continuous side-by-side field releases were conducted within a preexisting MTBE plume to form two lanes. The first involved the continuous injection of site groundwater amended with benzene, toluene and o-xylene ("No ethanol lane"), while the other involved the continuous injection of site groundwater amended with benzene, toluene and o-xylene and ethanol ("With ethanol lane"). The δ 13C of MTBE for all wells in the "No ethanol lane" remained constant during the experiment with a mean value of - 31.3 ± 0.5‰ ( n = 40), suggesting the absence of any substantial MTBE biodegradation in this lane. In contrast, substantial enrichment in 13C of MTBE by 40.6‰, was measured in the "With ethanol lane", consistent with the effects of biodegradation. A substantial amount of TBA (up to 1200 μg/L) was produced by the biodegradation of MTBE in the "With ethanol lane". The mean value of δ 13C for TBA in groundwater samples in the "With ethanol lane" was - 26.0 ± 1.0‰ ( n = 32). Uniform δ 13C TBA values through space and time in this lane suggest that substantial anaerobic biodegradation of TBA did not occur during the experiment. Using the reported range in isotopic enrichment factors for MTBE of - 9.2‰ to - 15.6‰, and values of δ 13C of MTBE in groundwater samples, MTBE first-order biodegradation rates in the "With ethanol lane" were 12.0 to 20.3 year - 1 ( n = 18). The isotope-derived rate constants are in good agreement with the previously published rate constant of 16.8 year - 1 calculated using contaminant mass-discharge for the "With ethanol lane".

Measuring Systemic Impacts of Bike Infrastructure Projects

DOT National Transportation Integrated Search

2018-05-01

This paper qualitatively identifies the impacts of bicycle infrastructure on all roadway users, including safety, operations, and travel route choice. Bicycle infrastructure includes shared lanes, conventional bike lanes, and separated bike lanes. Th...

Improving the Safety of Moving Lane Closures

DOT National Transportation Integrated Search

2009-06-01

Moving lane closures are an increasingly utilized and inherently hazardous traffic control procedure for highway : maintenance and operations activities. To improve the safety of moving lane closures for workers and motorists, : this research studied...

2005 Bay Area HOV lanes.

DOT National Transportation Integrated Search

2006-01-01

The ANNUAL HOV LANE REPORT is prepared by the California Department of : Transportation (Caltrans) District 4 Office of Highway Operations. This report : contains information concerning High Occupancy Vehicle (HOV) lanes on the : San Francisco Bay Ar...

Toward a best practice model for managed lanes in Texas.

DOT National Transportation Integrated Search

2013-09-01

Increasing implementation of managed lanes in the : United States : Katy Freeway Managed Lanes : (KML) offers lessons learned : for other projects : First operational, multilane, : variably priced, managed facility : in Texas : Became oper...

Excursions out-of-lane versus standard deviation of lateral position as outcome measure of the on-the-road driving test.

PubMed

Verster, Joris C; Roth, Thomas

2014-07-01

The traditional outcome measure of the Dutch on-the-road driving test is the standard deviation of lateral position (SDLP), the weaving of the car. This paper explores whether excursions out-of-lane are a suitable additional outcome measure to index driving impairment. A literature search was conducted to search for driving tests that used both SDLP and excursions out-of-lane as outcome measures. The analyses were limited to studies examining hypnotic drugs because several of these drugs have been shown to produce next-morning sedation. Standard deviation of lateral position was more sensitive in demonstrating driving impairment. In fact, solely relying on excursions out-of-lane as outcome measure incorrectly classifies approximately half of impaired drives as unimpaired. The frequency of excursions out-of-lane is determined by the mean lateral position within the right traffic lane. Defining driving impairment as having a ΔSDLP > 2.4 cm, half of the impaired driving tests (51.2%, 43/84) failed to produce excursions out-of-lane. Alternatively, 20.9% of driving tests with ΔSDLP < 2.4 cm (27/129) had at least one excursion out-of-lane. Excursions out-of-lane are neither a suitable measure to demonstrate driving impairment nor is this measure sufficiently sensitive to differentiate adequately between differences in magnitude of driving impairment. Copyright © 2014 John Wiley & Sons, Ltd.

Comparing Lanes in the Pulsed-Field Gel Electrophoresis (PFGE) Images

DTIC Science & Technology

2001-10-25

Department of Computer and Information Science, National Chiao Tung University, Hsin Chu Taiwan 2 Department of Biological Science and Technology, National...Chiao Tung University Hsin Chu Taiwan Performing Organization Report Number Sponsoring/Monitoring Agency Name(s) and Address(es) US Army Research...image contains several lanes. And each lane consists of bands. Two lanes are identical if the relative positions of bands are the same. We present a

33 CFR 149.565 - What are the required characteristics and intensity of lights on buoys used to define traffic lanes?

Code of Federal Regulations, 2014 CFR

2014-07-01

... define traffic lanes? (a) The buoy's light color that defines the lateral boundaries of a traffic lane must comply with the buoy color schemes in § 62.25 of this chapter. (b) The buoy light may be fixed or... characteristics and intensity of lights on buoys used to define traffic lanes? 149.565 Section 149.565 Navigation...

33 CFR 149.565 - What are the required characteristics and intensity of lights on buoys used to define traffic lanes?

Code of Federal Regulations, 2011 CFR

2011-07-01

... define traffic lanes? (a) The buoy's light color that defines the lateral boundaries of a traffic lane must comply with the buoy color schemes in § 62.25 of this chapter. (b) The buoy light may be fixed or... characteristics and intensity of lights on buoys used to define traffic lanes? 149.565 Section 149.565 Navigation...

33 CFR 149.565 - What are the required characteristics and intensity of lights on buoys used to define traffic lanes?

Code of Federal Regulations, 2013 CFR

2013-07-01

... define traffic lanes? (a) The buoy's light color that defines the lateral boundaries of a traffic lane must comply with the buoy color schemes in § 62.25 of this chapter. (b) The buoy light may be fixed or... characteristics and intensity of lights on buoys used to define traffic lanes? 149.565 Section 149.565 Navigation...

33 CFR 149.565 - What are the required characteristics and intensity of lights on buoys used to define traffic lanes?

Code of Federal Regulations, 2010 CFR

2010-07-01

... define traffic lanes? (a) The buoy's light color that defines the lateral boundaries of a traffic lane must comply with the buoy color schemes in § 62.25 of this chapter. (b) The buoy light may be fixed or... characteristics and intensity of lights on buoys used to define traffic lanes? 149.565 Section 149.565 Navigation...

33 CFR 149.565 - What are the required characteristics and intensity of lights on buoys used to define traffic lanes?

Code of Federal Regulations, 2012 CFR

2012-07-01

... define traffic lanes? (a) The buoy's light color that defines the lateral boundaries of a traffic lane must comply with the buoy color schemes in § 62.25 of this chapter. (b) The buoy light may be fixed or... characteristics and intensity of lights on buoys used to define traffic lanes? 149.565 Section 149.565 Navigation...

Non-linear continuous time random walk models★

NASA Astrophysics Data System (ADS)

Stage, Helena; Fedotov, Sergei

2017-11-01

A standard assumption of continuous time random walk (CTRW) processes is that there are no interactions between the random walkers, such that we obtain the celebrated linear fractional equation either for the probability density function of the walker at a certain position and time, or the mean number of walkers. The question arises how one can extend this equation to the non-linear case, where the random walkers interact. The aim of this work is to take into account this interaction under a mean-field approximation where the statistical properties of the random walker depend on the mean number of walkers. The implementation of these non-linear effects within the CTRW integral equations or fractional equations poses difficulties, leading to the alternative methodology we present in this work. We are concerned with non-linear effects which may either inhibit anomalous effects or induce them where they otherwise would not arise. Inhibition of these effects corresponds to a decrease in the waiting times of the random walkers, be this due to overcrowding, competition between walkers or an inherent carrying capacity of the system. Conversely, induced anomalous effects present longer waiting times and are consistent with symbiotic, collaborative or social walkers, or indirect pinpointing of favourable regions by their attractiveness. Contribution to the Topical Issue "Continuous Time Random Walk Still Trendy: Fifty-year History, Current State and Outlook", edited by Ryszard Kutner and Jaume Masoliver.

Development of a lane change risk index using vehicle trajectory data.

PubMed

Park, Hyunjin; Oh, Cheol; Moon, Jaepil; Kim, Seongho

2018-01-01

Surrogate safety measures (SSMs) have been widely used to evaluate crash potential, which is fundamental for the development of effective safety countermeasures. Unlike existing SSMs, which are mainly focused on the evaluation of longitudinal vehicle maneuvering leading to rear-end crashes, this study proposes a new method for estimating crash risk while a subject vehicle changes lanes, referred to as the lane change risk index (LCRI). A novel feature of the proposed methodology is its incorporation of the amount of exposure time to potential crash and the expected crash severity level by applying a fault tree analysis (FTA) to the evaluation framework. Vehicle interactions between a subject vehicle and adjacent vehicles in the starting lane and the target lane are evaluated in terms of crash potential during lane change. Vehicle trajectory data obtained from a traffic stream, photographed using a drone flown over a freeway segment, is used to investigate the applicability of the proposed methodology. This study compares the characteristics of compulsory and discretionary lane changes observed in a work zone section and a general section of a freeway using the LCRI. It is expected that the outcome of this study will be valuable in evaluating the effectiveness of various traffic operations and control strategies in terms of lane change safety. Copyright © 2017 Elsevier Ltd. All rights reserved.

Traffic flow behavior at a single-lane urban roundabout

NASA Astrophysics Data System (ADS)

Lakouari, N.; Oubram, O.; Ez-Zahraouy, H.; Cisneros-Villalobos, L.; Velásquez-Aguilar, J. G.

In this paper, we propose a stochastic cellular automata model to study the traffic behavior at a single-lane roundabout. Vehicles can enter the interior lane or exit from it via N intersecting lane, the boundary conditions are stochastic. The traffic is controlled by a self-organized scheme. It has turned out that depending on the rules of insertion to the roundabout, five distinct traffic phases can appear, namely, free flow, congestion, maximum current, jammed and gridlock. The transition between the free flow and the gridlock is forbidden. The density profiles are used to study the traffic pattern at the interior lane of the roundabout. In order to quantify the interactions between vehicles in the interior lane of the roundabout, the velocity correlation coefficient (VCC) is also studied. Besides, the spatiotemporal diagrams corresponding to the entry/exit lanes are derived numerically. Furthermore, we have investigated the effect of displaying signal (PIn), as the PIn decreases, the maximum current increases at the expense of the free flow and the jamming phase. Finally, we have investigated the effect of the braking probability P on the interior lane of the roundabout. We have found that the increase of P raises the spontaneous jam formation on the ring. Thus, enlarges the maximum current and the jamming phase while the free flow phase decreases.

Statistical projection effects in a hydrodynamic pilot-wave system

NASA Astrophysics Data System (ADS)

Sáenz, Pedro J.; Cristea-Platon, Tudor; Bush, John W. M.

2018-03-01

Millimetric liquid droplets can walk across the surface of a vibrating fluid bath, self-propelled through a resonant interaction with their own guiding or `pilot' wave fields. These walking droplets, or `walkers', exhibit several features previously thought to be peculiar to the microscopic, quantum realm. In particular, walkers confined to circular corrals manifest a wave-like statistical behaviour reminiscent of that of electrons in quantum corrals. Here we demonstrate that localized topological inhomogeneities in an elliptical corral may lead to resonant projection effects in the walker's statistics similar to those reported in quantum corrals. Specifically, we show that a submerged circular well may drive the walker to excite specific eigenmodes in the bath that result in drastic changes in the particle's statistical behaviour. The well tends to attract the walker, leading to a local peak in the walker's position histogram. By placing the well at one of the foci, a mode with maxima near the foci is preferentially excited, leading to a projection effect in the walker's position histogram towards the empty focus, an effect strongly reminiscent of the quantum mirage. Finally, we demonstrate that the mean pilot-wave field has the same form as the histogram describing the walker's statistics.

Influence of an infant walker on onset and quality of walking pattern of locomotion:an electromyographic investigation.

PubMed

Kauffman, I B; Ridenour, M

1977-12-01

Acquisition of bipedal locomotor skill in human infants was studied electromyographically with regard to the deprivation or enrichment behavior resulting from the frequent and regular use of an infant walker. Subjects were six sets of male, fraternal twins. One randomly selected sibling from each set underwent a training program, commencing at the age of 300 days, spending a total of 2 hr. per day in a walker. Siblings not included in this group were subjected to no special training. EMG recordings were taken of all subjects at specified intervals in order to establish a model of the typical motor pattern at various stages of skill development. These data were then contrasted with EMG data similarly obtained from the walker-trained subjects. Use of an infant walker modified the mechanics of the infant's locomotion in a number of important ways. It was shown that use of the walker enables an infant to commit substantial mechanical errors yet succeed in bipedal locomotion. Inasmuch as the mechanics of walker-assisted and non-assisted bipedal locomotion are dissimilar in so many important ways, positive transfer from walker-training appears questionable.

Optimizing DNA nanotechnology through coarse-grained modeling: a two-footed DNA walker.

PubMed

Ouldridge, Thomas E; Hoare, Rollo L; Louis, Ard A; Doye, Jonathan P K; Bath, Jonathan; Turberfield, Andrew J

2013-03-26

DNA has enormous potential as a programmable material for creating artificial nanoscale structures and devices. For more complex systems, however, rational design and optimization can become difficult. We have recently proposed a coarse-grained model of DNA that captures the basic thermodynamic, structural, and mechanical changes associated with the fundamental process in much of DNA nanotechnology, the formation of duplexes from single strands. In this article, we demonstrate that the model can provide powerful insight into the operation of complex nanotechnological systems through a detailed investigation of a two-footed DNA walker that is designed to step along a reusable track, thereby offering the possibility of optimizing the design of such systems. We find that applying moderate tension to the track can have a large influence on the operation of the walker, providing a bias for stepping forward and helping the walker to recover from undesirable overstepped states. Further, we show that the process by which spent fuel detaches from the walker can have a significant impact on the rebinding of the walker to the track, strongly influencing walker efficiency and speed. Finally, using the results of the simulations, we propose a number of modifications to the walker to improve its operation.

An efficient computational method for the approximate solution of nonlinear Lane-Emden type equations arising in astrophysics

NASA Astrophysics Data System (ADS)

Singh, Harendra

2018-04-01

The key purpose of this article is to introduce an efficient computational method for the approximate solution of the homogeneous as well as non-homogeneous nonlinear Lane-Emden type equations. Using proposed computational method given nonlinear equation is converted into a set of nonlinear algebraic equations whose solution gives the approximate solution to the Lane-Emden type equation. Various nonlinear cases of Lane-Emden type equations like standard Lane-Emden equation, the isothermal gas spheres equation and white-dwarf equation are discussed. Results are compared with some well-known numerical methods and it is observed that our results are more accurate.

Safety performance for freeway weaving segments.

DOT National Transportation Integrated Search

2014-09-01

The intensive lane change maneuvers at weaving sections often result in safety and operational problems. : Various factors, including the design of ramp roadways, use of auxiliary lanes, and continuity of lanes will have : significant effects on the ...

Assessment of carpool utilization of the Katy high-occupancy vehicle lane and the characteristics of Houston's HOV lane users and nonusers. Final research report, Sep 84-Aug 91

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

Bullard, D.L.

1991-10-01

The report documents data collected in the Katy Freeway corridor in October 1990, 66 months or 5.5 years after carpool utilization of the Katy HOV Lane began. The 1990 data are compared to similar data collected before carpool utilization was permitted (March 1985) and after carpool utilization was permitted (April 1986, October 1987, October 1988 and October 1989). These comparisons address numerous concerns and provide an indication of the effectiveness of allowing carpools onto the Katy HOV Lane. Also included in the report are summaries of survey data collected along the Katy, North, Northwest and Gulf Freeway/HOV Lane corridors frommore » April 1985 through October 1990. The primary intent of these surveys was to: (1) determine perceptions of HOV lane utilization; (2) identify why commuters have chosen their present travel mode; and (3) assess attitudes and impacts pertaining to the HOV lanes. Demographic data and data concerning general travel characteristics were also collected.« less

Active tectonics of the northern Mojave Desert: The 2017 Desert Symposium field trip road log

USGS Publications Warehouse

Miller, David; Reynolds, R.E.; Phelps, Geoffrey; Honke, Jeff; Cyr, Andrew J.; Buesch, David C.; Schmidt, Kevin M.; Losson, G.

2017-01-01

The 2017 Desert Symposium field trip will highlight recent work by the U.S. Geological Survey geologists and geophysicists, who have been mapping young sediment and geomorphology associated with active tectonic features in the least well-known part of the eastern California Shear Zone (ECSZ). This area, stretching from Barstow eastward in a giant arc to end near the Granite Mountains on the south and the Avawatz Mountains on the north (Fig. 1-1), encompasses the two major structural components of the ECSZ—east-striking sinistral faults and northwest-striking dextral faults—as well as reverseoblique and normal-oblique faults that are associated with topographic highs and sags, respectively. In addition, folds and stepovers (both restraining stepovers that form pop-up structures and releasing stepovers that create narrow basins) have been identified. The ECSZ is a segment in the ‘soft’ distributed deformation of the North American plate east of the San Andreas fault (Fig. 1-1), where it takes up approximately 20-25% of plate motion in a broad zone of right-lateral shear (Sauber et al., 1994) The ECSZ (sensu strictu) begins in the Joshua Tree area and passes north through the Mojave Desert, past the Owens Valley-to-Death Valley swath and northward, where it is termed the Walker Lane. It has been defined as the locus of active faulting (Dokka and Travis, 1990), but when the full history from about 10 Ma forward is considered, it lies in a broader zone of right shear that passes westward in the Mojave Desert to the San Andreas fault (Mojave strike-slip province of Miller and Yount, 2002) and passes eastward to the Nevada state line or beyond (Miller, this volume).We will visit several accessible highlights for newly studied faults, signs of young deformation, and packages of syntectonic sediments. These pieces of a complex active tectonic puzzle have yielded some answers to longstanding questions such as: How is fault slip transfer in this area accommodated between northwest-striking dextral faults and eaststriking sinistral faults?How is active deformation on the Ludlow fault transferred northward, presumably to connect to the southern Death Valley fault zone?When were faults in this area of the central Mojave Desert initiated?Are faults in this area more or less active than faults in the ECSZ to the west?What is the role of NNW-striking faults and when did they form?How has fault slip changed over time? Locations and fault names are provided in figure 1-2. Important turns and locations are identified with locations in the projection: UTM, zone 11; datum NAD 83: (578530 3917335).

DNA Walkers as Transport Vehicles of Nanoparticles Along a Carbon Nanotube Track.

PubMed

Pan, Jing; Cha, Tae-Gon; Chen, Haorong; Li, Feiran; Choi, Jong Hyun

2017-01-01

DNA-based molecular motors are synthetic analogs of naturally occurring protein motors. Typical DNA walkers are constructed from synthetic short DNA strands and are powered by various free energy changes during hybridization reactions. Due to the constraints set by their small physical dimension and slow kinetics, most DNA walkers are characterized by ensemble measurements that result in averaged kinetics data. Here we present a synthetic DNA walker system that exploits the extraordinary physicochemical properties of nanomaterials and the functionalities of DNA molecules, which enables real-time control and monitoring of single-DNA walkers over an extended period.

Design and scope of impact of auxiliary lanes : technical report.

DOT National Transportation Integrated Search

2014-06-01

For decades, Texas Department of Transportation districts have constructed auxiliary lanes to support interchange : ramp operations and to resolve congestion proximate to freeway entrance and exit ramps. While auxiliary lanes are : built throughout T...

Use of videotape in HOV lane surveillance and enforcement

DOT National Transportation Integrated Search

1990-03-01

Enforcement of Californias HOV lanes currently requires substantial commitments of California Highway Patrol (CHP) personnel and equipment. Personnel costs for enforcing the states ten mainline HOV lanes alone will exceed $400,000 in 1990. HOV ...

Toolbox of countermeasures for rural two-lane curves.

DOT National Transportation Integrated Search

2013-10-01

The Federal Highway Administration (FHWA) estimates that 58 percent of roadway fatalities are lane departures, while 40 : percent of fatalities are single-vehicle run-off-road (SVROR) crashes. Addressing lane-departure crashes is therefore a : priori...

Toolbox of countermeasures for rural two-lane curves.

DOT National Transportation Integrated Search

2012-06-01

The Federal Highway Administration (FHWA) estimates that 58 percent of roadway fatalities are lane departures, while 40 percent of fatalities are single-vehicle run-off-road (SVROR) crashes. Addressing lane-departure crashes is therefore a priority f...

Centerline pavement markings on two-lane mountain highways.

DOT National Transportation Integrated Search

1983-01-01

The Virginia Department of Highways and Transportation uses a lane marking designated mountain pavement marking (MPM) on two-lane highways in mountainous areas. This special marking consists of a single broken yellow line supplemented with "PASS WITH...

Impact of exempt vehicles on managed lanes.

DOT National Transportation Integrated Search

2014-01-15

In order to better utilize available capacity in high-occupancy vehicle (HOV) lanes, states are permitted to allow certain qualifying non-HOVs to use HOV lanes. In general, states may allow motorcycles, public transportation vehicles, high-occupancy ...

Operational performance management of priced facilities

DOT National Transportation Integrated Search

2011-03-01

The Texas Department of Transportation and its agency partners have implemented various forms of lane management and pricing over the past three decades, including HOV lanes, managed lanes, and toll roads. As more of these complex transportation faci...

Lane Detection on the iPhone

NASA Astrophysics Data System (ADS)

Ren, Feixiang; Huang, Jinsheng; Terauchi, Mutsuhiro; Jiang, Ruyi; Klette, Reinhard

A robust and efficient lane detection system is an essential component of Lane Departure Warning Systems, which are commonly used in many vision-based Driver Assistance Systems (DAS) in intelligent transportation. Various computation platforms have been proposed in the past few years for the implementation of driver assistance systems (e.g., PC, laptop, integrated chips, PlayStation, and so on). In this paper, we propose a new platform for the implementation of lane detection, which is based on a mobile phone (the iPhone). Due to physical limitations of the iPhone w.r.t. memory and computing power, a simple and efficient lane detection algorithm using a Hough transform is developed and implemented on the iPhone, as existing algorithms developed based on the PC platform are not suitable for mobile phone devices (currently). Experiments of the lane detection algorithm are made both on PC and on iPhone.

Stability analysis of dynamic collaboration model with control signals on two lanes

NASA Astrophysics Data System (ADS)

Li, Zhipeng; Zhang, Run; Xu, Shangzhi; Qian, Yeqing; Xu, Juan

2014-12-01

In this paper, the influence of control signals on the stability of two-lane traffic flow is mainly studied by applying control theory with lane changing behaviors. We present the two-lane dynamic collaboration model with lateral friction and the expressions of feedback control signals. What is more, utilizing the delayed feedback control theory to the two-lane dynamic collaboration model with control signals, we investigate the stability of traffic flow theoretically and the stability conditions for both lanes are derived with finding that the forward and lateral feedback signals can improve the stability of traffic flow while the backward feedback signals cannot achieve it. Besides, direct simulations are conducted to verify the results of theoretical analysis, which shows that the feedback signals have a significant effect on the running state of two vehicle groups, and the results are same with the theoretical analysis.

Modeling electric bicycle's lane-changing and retrograde behaviors

NASA Astrophysics Data System (ADS)

Tang, Tie-Qiao; Luo, Xiao-Feng; Zhang, Jian; Chen, Liang

2018-01-01

Recently, electric bicycle (EB) has been one important traffic tool due to its own merits. However, EB's motion behaviors (especially at a signalized/non-signalized intersection) are more complex than those of vehicle since it always has lane-changing and retrograde behaviors. In this paper, we propose a model to explore EB's lane-changing and retrograde behaviors on a road with a signalized intersection. The numerical results indicate that the proposed model can qualitatively describe each EB's lane-changing and retrograde behaviors near a signalized intersection, and that lane-changing and retrograde behaviors have prominent impacts on the signalized intersection (i.e., prominent jams and congestions occur). The above results show that EB should be controlled as a vehicle, i.e., lane-changing and retrograde behaviors at a signalized intersection should strictly be prohibited to improve the operational efficiency and traffic safety at the signalized intersection.

Cross-Validation of a Recently Published Equation Predicting Energy Expenditure to Run or Walk a Mile in Normal-Weight and Overweight Adults

ERIC Educational Resources Information Center

Morris, Cody E.; Owens, Scott G.; Waddell, Dwight E.; Bass, Martha A.; Bentley, John P.; Loftin, Mark

2014-01-01

An equation published by Loftin, Waddell, Robinson, and Owens (2010) was cross-validated using ten normal-weight walkers, ten overweight walkers, and ten distance runners. Energy expenditure was measured at preferred walking (normal-weight walker and overweight walkers) or running pace (distance runners) for 5 min and corrected to a mile. Energy…

Effect of uphill and downhill walking on walking performance in geriatric patients using a wheeled walker.

PubMed

Lindemann, Ulrich; Schwenk, Michael; Schmitt, Syn; Weyrich, Michael; Schlicht, Wolfgang; Becker, Clemens

2017-08-01

Wheeled walkers are recommended to improve walking performance in older persons and to encourage and assist participation in daily life. Nevertheless, using a wheeled walker can cause serious problems in the natural environment. This study aimed to compare uphill and downhill walking with walking level in geriatric patients using a wheeled walker. Furthermore, we investigated the effect of using a wheeled walker with respect to dual tasking when walking level. A total of 20 geriatric patients (median age 84.5 years) walked 10 m at their habitual pace along a level surface, uphill and downhill, with and without a standard wheeled walker. Gait speed, stride length and cadence were assessed by wearable sensors and the walk ratio was calculated. When using a wheeled walker while walking level the walk ratio improved (0.58 m/[steps/min] versus 0.57 m/[steps/min], p = 0.023) but gait speed decreased (1.07 m/s versus 1.12 m/s, p = 0.020) when compared to not using a wheeled walker. With respect to the walk ratio, uphill and downhill walking with a wheeled walker decreased walking performance when compared to level walking (0.54 m/[steps/min] versus 0.58 m/[steps/min], p = 0.023 and 0.55 m/[steps/min] versus 0.58 m/[steps/min], p = 0.001, respectively). At the same time, gait speed decreased (0.079 m/s versus 1.07 m/s, p < 0.0001) or was unaffected. The use of a wheeled walker improved the quality of level walking but the performance of uphill and downhill walking was worse compared to walking level when using a wheeled walker.

Four-wheeled walker related injuries in older adults in the Netherlands.

PubMed

van Riel, K M M; Hartholt, K A; Panneman, M J M; Patka, P; van Beeck, E F; van der Cammen, T J M

2014-02-01

With ageing populations worldwide, mobility devices are used more than ever. In the current literature there is no consensus whether the available mobility devices safely improve the mobility of their users. Also, evidence is lacking concerning the risks and types of injuries sustained while using a four-wheeled walker. To assess injury risks and injury patterns in older adults (≥65 years) who presented at Emergency Departments (ED) in the Netherlands with an injury due to using a four-wheeled walker. In this study, the Dutch Injury Surveillance System was used to obtain a national representative sample of annual ED visits in the Netherlands in the adult population (≥65 years) sustaining an injury while using a four-wheeled walker. The numbers of four-wheeled walker users in the Netherlands were obtained from the national insurance board. The numbers of ED visits were divided by the numbers of four-wheeled walker users to calculate age- and sex-specific injury risks. Annually 1869 older adults visited an ED after sustaining an injury while using a four-wheeled walker. Falls were the main cause of injury (96%). The injury risk was 3.1 per 100 users of four-wheeled walkers. Women (3.5 per 100 users) had a higher risk than men (2.0 per 100 users). Injury risk was the highest in women aged 85 years and older (6.2 per 100 users). The majority of injuries were fractures (60%) with hip fracture (25%) being the most common injury. Nearly half of all four-wheeled walker related injuries required hospitalisation, mostly due to hip fractures. Healthcare costs per injury were approximately €12 000. This study presents evidence that older adults experiencing a fall while using a four-wheeled walker are at high risk to suffer severe injuries.

Recent intensification of the Walker Circulation and the role of natural sea surface temperature variability

NASA Astrophysics Data System (ADS)

Zhao, X.; Allen, R.

2017-12-01

In a warming world, the tropical atmospheric overturning circulation-including the Walker Circulation-is expected to weaken due to thermodynamic constraints. Tropical precipitation increases at a slower rate than water vapor-which increases according to Clausius Clapeyron scaling, assuming constant relative humidity-so the tropical overturning circulation slows down. This is supported by both observations and model simulations, which show a slowdown of the Walker Circulation over the 20th century. Model projections suggest a further weakening of the Walker Circulation in the 21st century. However, over the last several decades (1979-2014), multiple observations reveal a robust strengthening of the Walker Circulation. Although coupled CMIP5 simulations are unable to reproduce this strengthening, AMIP simulations-which feature the observed evolution of SSTs-are generally able to reproduce it. Assuming the ensemble mean sea surface temperatures (SSTs) from historical CMIP5 simulations accurately represent the externally forced SST response, the observed SSTs can be decomposed into a forced and an unforced component. CAM5 AMIP-type simulations driven by the unforced component of observed SSTs reproduce the observed strengthening of the Walker Circulation. Corresponding simulations driven by the forced component of observed SSTs yield a weaker Walker Circulation. These results are consistent with the zonal tropical SST gradient and the Bjerknes feedback. The unforced component of SSTs yield an increased SST gradient over tropical Pacific (a La Nina like pattern) and strengthening of the tropical trade winds, which constitute the lower branch of the Walker Circulation. The forced component of SSTs yields a zonally uniform tropical Pacific SST warming and a marginal weakening of the Walker Circulation. Our results suggest significant modulation of the tropical Walker Circulation by natural SST variability over the last several decades.

Assistive devices alter gait patterns in Parkinson disease: advantages of the four-wheeled walker.

PubMed

Kegelmeyer, Deb A; Parthasarathy, Sowmya; Kostyk, Sandra K; White, Susan E; Kloos, Anne D

2013-05-01

Gait abnormalities are a hallmark of Parkinson's disease (PD) and contribute to fall risk. Therapy and exercise are often encouraged to increase mobility and decrease falls. As disease symptoms progress, assistive devices are often prescribed. There are no guidelines for choosing appropriate ambulatory devices. This unique study systematically examined the impact of a broad range of assistive devices on gait measures during walking in both a straight path and around obstacles in individuals with PD. Quantitative gait measures, including velocity, stride length, percent swing and double support time, and coefficients of variation were assessed in 27 individuals with PD with or without one of six different devices including canes, standard and wheeled walkers (two, four or U-Step). Data were collected using the GAITRite and on a figure-of-eight course. All devices, with the exception of four-wheeled and U-Step walkers significantly decreased gait velocity. The four-wheeled walker resulted in less variability in gait measures and had less impact on spontaneous unassisted gait patterns. The U-Step walker exhibited the highest variability across all parameters followed by the two-wheeled and standard walkers. Higher variability has been correlated with increased falls. Though subjects performed better on a figure-of-eight course using either the four-wheeled or the U-Step walker, the four-wheeled walker resulted in the most consistent improvement in overall gait variables. Laser light use on a U-Step walker did not improve gait measures or safety in figure-of-eight compared to other devices. Of the devices tested, the four-wheeled-walker offered the most consistent advantages for improving mobility and safety. Copyright © 2012 Elsevier B.V. All rights reserved.

Evidence for auditory-visual processing specific to biological motion.

PubMed

Wuerger, Sophie M; Crocker-Buque, Alexander; Meyer, Georg F

2012-01-01

Biological motion is usually associated with highly correlated sensory signals from more than one modality: an approaching human walker will not only have a visual representation, namely an increase in the retinal size of the walker's image, but also a synchronous auditory signal since the walker's footsteps will grow louder. We investigated whether the multisensorial processing of biological motion is subject to different constraints than ecologically invalid motion. Observers were presented with a visual point-light walker and/or synchronised auditory footsteps; the walker was either approaching the observer (looming motion) or walking away (receding motion). A scrambled point-light walker served as a control. Observers were asked to detect the walker's motion as quickly and as accurately as possible. In Experiment 1 we tested whether the reaction time advantage due to redundant information in the auditory and visual modality is specific for biological motion. We found no evidence for such an effect: the reaction time reduction was accounted for by statistical facilitation for both biological and scrambled motion. In Experiment 2, we dissociated the auditory and visual information and tested whether inconsistent motion directions across the auditory and visual modality yield longer reaction times in comparison to consistent motion directions. Here we find an effect specific to biological motion: motion incongruency leads to longer reaction times only when the visual walker is intact and recognisable as a human figure. If the figure of the walker is abolished by scrambling, motion incongruency has no effect on the speed of the observers' judgments. In conjunction with Experiment 1 this suggests that conflicting auditory-visual motion information of an intact human walker leads to interference and thereby delaying the response.

Concurrent flow lanes - phase III.

DOT National Transportation Integrated Search

2011-01-01

This report describes efforts taken to develop and calibrate VISSIM models of existing : concurrent flow lane designs of north- and southbound lanes of I-270 from the interchange at : I-70 to interchanges on I-495 at Connecticut Avenue in Maryland an...

A guide for HOT lane development

DOT National Transportation Integrated Search

2002-12-01

This guide is intended to be a comprehensive source of collective experience gained from the nations current and implemented high occupancy toll (HOT) lane projects. The guide presents a wide range of information on HOT lanes and is intended to as...

Development of a MASH TL-3 median barrier gate.

DOT National Transportation Integrated Search

2011-06-01

Median barriers are commonly used to separate opposing lanes of traffic on divided highways and to : separate managed lanes from general purpose lanes. Concrete median barriers (CMBs) are often preferred : on urban freeways with narrow medians due to...

Hydrogel Walkers with Electro-Driven Motility for Cargo Transport.

PubMed

Yang, Chao; Wang, Wei; Yao, Chen; Xie, Rui; Ju, Xiao-Jie; Liu, Zhuang; Chu, Liang-Yin

2015-08-28

In this study, soft hydrogel walkers with electro-driven motility for cargo transport have been developed via a facile mould-assisted strategy. The hydrogel walkers consisting of polyanionic poly(2-acrylamido-2-methylpropanesulfonic acid-co-acrylamide) exhibit an arc looper-like shape with two "legs" for walking. The hydrogel walkers can reversibly bend and stretch via repeated "on/off" electro-triggers in electrolyte solution. Based on such bending/stretching behaviors, the hydrogel walkers can move their two "legs" to achieve one-directional walking motion on a rough surface via repeated "on/off" electro-triggering cycles. Moreover, the hydrogel walkers loaded with very heavy cargo also exhibit excellent walking motion for cargo transport. Such hydrogel systems create new opportunities for developing electro-controlled soft systems with simple design/fabrication strategies in the soft robotic field for remote manipulation and transportation.

[Needs, uses, cons-pros, good practices and opportunities about walker in elderly with loss of autonomy].

PubMed

Mézière, Anthony; Schonheit, Claire; Moreau, Caroline; Baudry, Elodie; Monié, Marguerite; Piette, François; Curtis, Valentine; Pasqui, Viviane

2015-01-01

Non-use of the walker may be secondary to an initial inappropriate prescribing, a lack of adequate training, a lack of monitoring and side effects of using. Improving both stability and mobility in users is due to several biomechanical mechanisms. The benefits of walker are: general physiological effects, more confidence, better social life and decrease in the burden of care. The disadvantages of walker are: technical or practical aspects criticized by users, musculoskeletal disorders, delayed reaction time, fall risk and stigma. Few scientific data evaluating the interest of the walker concerning mobility exist, thus recommendations are low grade and are often taken from professional clinical experiences. The choice of technical walking assistance depends on the pathology and biomechanical mechanism. The walker robots are few distributed. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Development and evaluation of low-cost walker with trunk support for senior citizen.

PubMed

Poier, Paloma Hohmann; Godke, Francisco; Foggiatto, José Aguiomar; Ulbricht, Leandra

2017-10-09

Develop and evaluate a low-cost walker with trunk support for senior citizens. Two-stage descriptive study: development of a walker with trunk support and evaluation with fourth age senior citizens. Twenty-three fourth age senior citizens were selected. The evaluated criteria were the immediate influence of the walker on the static stabilometry with baropodometer and the evaluation of gait with accelerometers monitoring time and amplitude of the hip movement. There was a significant decrease in the body oscillation of senior citizens with the use of the developed walker, and there were changes in the joint amplitudes of the hip, but they were not significant. Using low-cost materials, it was possible to develop and equipment that met resistance and effectiveness requirements. The walker interfered in the balance of the senior citizens, reducing significantly the static body oscillation.

Pole walking down-under: profile of pole walking leaders, walkers and programs in Australia and factors relating to participation.

PubMed

Fritschi, Juliette O; van Uffelen, Jannique G Z; Brown, Wendy J

2014-12-01

Although pole walking (PW) has the potential to be a useful health-enhancing physical activity (PA), little is known about by whom or how it is being practised. The aims of this study were to describe (1) the characteristics of PW leaders, pole walkers and PW programs in Australia, and (2) participants' perceptions of PW and their reasons for participation. In 2012, PW leaders (n=31) and walkers (n=107) completed self-administered surveys that included questions about participants' sociodemographic and health characteristics, PW programs and perceptions of PW. Data were analysed using SPSS. Leaders and walkers were generally born in Australia (leaders, 71%; walkers, 83%), older (leaders, 55 years [s.d. 11.5]; walkers, 65 years [s.d. 10.6]) and female (leaders, 77%; walkers, 79%). Most walkers (82%) walked regularly in groups, approximately once per week for about an hour, at light to moderate intensity. The program's aims most strongly endorsed by PW leaders were to increase participant enjoyment (90%), increase PA levels (81%), provide a positive social experience (77%) and increase PA confidence (71%). The most strongly endorsed motivations for PW among walkers were to remain physically active (63%), improve fitness (62%) and personal and social enjoyment (60%). In Australia, PW is being practised by a health conscious, older population. It is perceived as an enjoyable and health-enhancing outdoor activity. SO WHAT?: Health and exercise practitioners may find that PW is a beneficial form of PA for older Australians.

Engineered Plants as Biosensors

DTIC Science & Technology

2003-05-28

GFP fluorescence was detectable in the lower leaves and especially in the roots of one transgenic plant compared to negative and positive control...mgfp5-er gene, lane 5 contains cDNA from a 35s-mgfp5-er transgenic plant , lanes 6-10 contain cDNAs from gn1/gfp plants. RNA extraction was performed 7...contains transgenic plant sprayed with water (negative control). Lanes 5-12 are independent gn1/gfp transgenic events sprayed with 5 mM BTH. Lanes

Comprehensive and Practical Vision System for Self-Driving Vehicle Lane-Level Localization.

PubMed

Du, Xinxin; Tan, Kok Kiong

2016-05-01

Vehicle lane-level localization is a fundamental technology in autonomous driving. To achieve accurate and consistent performance, a common approach is to use the LIDAR technology. However, it is expensive and computational demanding, and thus not a practical solution in many situations. This paper proposes a stereovision system, which is of low cost, yet also able to achieve high accuracy and consistency. It integrates a new lane line detection algorithm with other lane marking detectors to effectively identify the correct lane line markings. It also fits multiple road models to improve accuracy. An effective stereo 3D reconstruction method is proposed to estimate vehicle localization. The estimation consistency is further guaranteed by a new particle filter framework, which takes vehicle dynamics into account. Experiment results based on image sequences taken under different visual conditions showed that the proposed system can identify the lane line markings with 98.6% accuracy. The maximum estimation error of the vehicle distance to lane lines is 16 cm in daytime and 26 cm at night, and the maximum estimation error of its moving direction with respect to the road tangent is 0.06 rad in daytime and 0.12 rad at night. Due to its high accuracy and consistency, the proposed system can be implemented in autonomous driving vehicles as a practical solution to vehicle lane-level localization.

Effect of traffic density on drivers' lane change and overtaking maneuvers in freeway situation - A driving simulator based study.

PubMed

Yang, Liu; Li, Xiaomeng; Guan, Wei; Zhang, H Michael; Fan, Lingling

2018-05-14

The aim of this study is to examine the effect of traffic density on drivers' lane change and overtaking maneuvers. The differences between drivers' left and right lane-changing/overtaking maneuvers were also investigated. A driving simulator experiment was conducted and 24 participants took part in this experiment. Based on the driving simulation data, lane change frequency, time duration, average speed and acceleration were extracted as key variables of lane change maneuvers; overtaking frequency, overtaking duration, initial overtaking distance and headway, instantaneous speed and acceleration before overtaking were analyzed as the key overtaking variables. One-way repeated measures ANOVA, Friedman test and Wilcoxon signed-rank test were adopted for hypothesis tests with significance level of 0.05. Further pairwise comparisons were performed with a Bonferroni correction for multiple comparisons. Some significant differences in lane change and overtake behaviors were observed among different traffic densities: 1) both lane change and overtaking frequencies significantly increase with traffic density; 2) the average lane change acceleration and instantaneous overtaking acceleration significantly increase with traffic density; 3) as the traffic density increases, the initial overtaking distance and headway decrease. As for the effect of the directions of maneuvers: 1) the time duration of lane change and overtaking from right side was significantly shorter than that from left side; 2) the right initial overtaking distance/headway was smaller than that of left side; 3) the right instantaneous overtaking acceleration was significantly higher than the left instantaneous acceleration. The results showed that as traffic density increases, drivers' intention for lane change and overtaking is enhanced. Both initial overtaking distance and headway decrease with traffic density, which might influence road safety. In addition, drivers do not show a preference on the directions of lane change or overtaking according to the frequency. However, drivers tend to be more decisive and reckless when conducting the right overtaking because of a smaller distance/headway before overtaking, higher instantaneous acceleration and also a more restricted field of view compared with left overtaking.

Do baby walkers delay onset of walking in young children?

PubMed

Burrows, Patricia; Griffiths, Peter

2002-11-01

Baby walkers have been a source of considerable controversy. Some people suggest developmental benefit from their use while others focus on the potential harm that stems from accidents and even suggest developmental delay. This mini-review aimed to determine if use of a baby walker delays affects the onset of walking. The Cochrane library, Embase, CINAHL and Medline were searched for randomized controlled trials (RCTs) and cohort studies, which compared the onset of walking in infants who used baby walkers with a group who did not. Two RCTs and two cohort studies were identified and available for consideration. All of the studies examined the effect of infant walkers on the onset of walking. The results of the two RCTs did not demonstrate a significant effect on the onset of walking. The cohort studies suggest that the use of infant walkers delayed the onset of walking in young children and a pooled analysis of the four studies suggested a delay of between 11 and 26 days. Although the quality of the studies was relatively poor these studies lend no support to the argument that walkers aid the development of walking. The significance of a delay of this magnitude is however unclear. Further work is required to determine whether walkers are an independent causal factor in accidents.

Pediatricians' attitude about the use of infant walkers.

PubMed

Kara, Semra; Yilmaz, Ayşe Esra; Gümüş Dogan, Derya; Bilici, Meki; Turkay, Sadi; Akca, Halise; Catal, Ferhat

2013-12-01

Infant walkers are still very popular even though their use might cause injuries. A survey was carried out to obtain information about attitudes and pediatricians' approach regarding the use of infant walkers. Two hundred and forty seven pediatricians who attended the 44th Turkish Congress of Pediatrics and Europediatrics (2008) were invited to reply to a questionnaire prepared by the authors. Two hundred and twenty six questionnaires replied in full were included. The median age of participants (119 women) was 39 years old (range: 29-58 years old). Out of the total, 4% recommended the use of a walker; 32.2% left the decision to parents' judgment, and 63.7% did not recommend its use. A hundred and five had previously treated an infant who had an injury associated to the use of the walker; out of them, 73.3% did not recommend its use and 57.1% stated that there should be a ban on the sale and manufacture of walkers. Out of the total number of surveyed pediatricians, 4% recommend the use of infant walkers and over 30% leave this decision to parents. Those pediatricians who took care of babies who had an injury associated to the use of a walker were less prone to recommending it.

Nonconvergence of the Wang-Landau algorithms with multiple random walkers.

PubMed

Belardinelli, R E; Pereyra, V D

2016-05-01

This paper discusses some convergence properties in the entropic sampling Monte Carlo methods with multiple random walkers, particularly in the Wang-Landau (WL) and 1/t algorithms. The classical algorithms are modified by the use of m-independent random walkers in the energy landscape to calculate the density of states (DOS). The Ising model is used to show the convergence properties in the calculation of the DOS, as well as the critical temperature, while the calculation of the number π by multiple dimensional integration is used in the continuum approximation. In each case, the error is obtained separately for each walker at a fixed time, t; then, the average over m walkers is performed. It is observed that the error goes as 1/sqrt[m]. However, if the number of walkers increases above a certain critical value m>m_{x}, the error reaches a constant value (i.e., it saturates). This occurs for both algorithms; however, it is shown that for a given system, the 1/t algorithm is more efficient and accurate than the similar version of the WL algorithm. It follows that it makes no sense to increase the number of walkers above a critical value m_{x}, since it does not reduce the error in the calculation. Therefore, the number of walkers does not guarantee convergence.

Walker use, but not falls, is associated with lower physical functioning and health of residents in an assisted-living environment.

PubMed

Andersen, Daniel A; Roos, Bernard A; Stanziano, Damian C; Gonzalez, Natasha M; Signorile, Joseph F

2007-01-01

The relationship between perceived health and walker use has seldom been addressed. Concerns over falls and falls risk are precursors to walker use. We compared the SF-36 scores of 26 women and 14 men, mean age 86.8 +/- 6.0 years based on walker use and faller status. An analysis of covariance (ANCOVA) with age as the covariate, compared groups for the SF-36 constructs and totals score. Significant differences were noted between walker users and nonusers in physical functioning, role limitations due to physical problems, general health, and the total SF-36 score. Pairwise comparisons favored nonusers, while no differences were seen due to faller status. Walker use is associated with lower self-perceptions of physical functioning, role limitations due to physical problems, and general health in assisted-living residents. Faller status is not associated with self-perceived health status. Although walker use aids mobility and lowers the probability of falls, further research is needed to determine if the prescription of assistive devices has a more negative impact on self-perceived health than does falling. This possibility could be explained, in part, by the greater activity levels of those individuals who do not depend on walkers.

Freeway work zone lane capacity.

DOT National Transportation Integrated Search

2009-01-01

The focus of this report is a capacity analysis of two long-term urban freeway Work Zones. Work Zone #1 : tapered four mainline lanes to two, using two separate tapers; Work Zone #2 tapered two mainline lanes to one. : Work Zone throughput was analyz...

Evaluation of shared lane markings in Miami Beach, Florida.

DOT National Transportation Integrated Search

2012-04-01

This report is a before-after evaluation of shared lane markings on Washington Avenue in Miami Beach, FL, which requested and received permission from the Federal Highway Administration (FHWA) to conduct a pilot study of shared lane markings. The mar...

I-15 express lanes study, phase II : recommendations.

DOT National Transportation Integrated Search

2015-02-01

The primary objective of this research was to recommend actions that will improve average speeds in the : Express Lanes (ELs) such that the lanes meet Utahs goal of 55 mph. To accomplish this objective it was important : to investigate the current...

Evaluating the performance and making best use of passing relief lanes.

DOT National Transportation Integrated Search

2011-12-01

This report documents the evaluation of the performance and safety effectiveness of passing relief lanes within the State of Michigan. The study began with the identification of passing relief lanes within Michigan. This was followed by collecting hi...

Managed lanes handbook training : year 2 report of activities.

DOT National Transportation Integrated Search

2009-02-01

This report summarizes the Year 2 activities under Implementation Project 5-4160-01, Managed Lanes : Handbook Training. The overall objective of the project is to develop a 12-hour workshop covering The : Managed Lanes Handbook, and teach the materia...

Biomimetic Molecular Signaling using DNA Walkers on Microparticles.

PubMed

Damase, Tulsi Ram; Spencer, Adam; Samuel, Bamidele; Allen, Peter B

2017-06-22

We report the release of catalytic DNA walkers from hydrogel microparticles and the detection of those walkers by substrate-coated microparticles. This might be considered a synthetic biology analog of molecular signal release and reception. One type of particles was coated with components of a DNA one-step strand displacement (OSD) reaction to release the walker. A second type of particle was coated with substrate (or "track") for the molecular walker. We distinguish these particle types using fluorescence barcoding: we synthesized and distinguished multiple particle types with multicolor fluorescence microscopy and automated image analysis software. This represents a step toward amplified, multiplex, and microscopically localized detection based on DNA nanotechnology.

Differences in the Limits of Stability Between Older Rolling Walker Users and Older Single-Tip-Cane Users - A Preliminary Study.

PubMed

Liu, Hao Howe; Quiben, Myles; Holmes, Clayton; Connors, Michael; Salem, Yasser

To identify the differences in the limits of stability (LOS) between older rolling walker and single-tip-cane users. This was a matched paired t-test design with repeated measure. Eighteen older subjects were matched based on age, gender, and functional level. The subjects were assessed using the multidirectional reach test initially and 5-month later in four directions: forward, backward, leftward, and rightward. Initially, there were no differences between cane users and rolling walker users in the LOS in all directions. However, 5-month later, the cane users who held their canes in their right hand had significantly better stability in forward and rightward reach than the walker users (p < .05). Further, the walker users demonstrated significantly decreased functional reach in forward reach (p < .05). Cane users might have better stability than walker users in the forward direction and in the direction toward the side holding the cane. This study may provide guide for clinicians including nurses for selecting appropriate rehabilitative interventions for older adults using walkers and canes.

Anatomic variants in Dandy-Walker complex.

PubMed

Jurcă, Maria Claudia; Kozma, Kinga; Petcheşi, CodruŢa Diana; Bembea, Marius; Pop, Ovidiu Laurean; MuŢiu, Gabriela; Coroi, Mihaela Cristiana; Jurcă, Alexandru Daniel; Dobjanschi, Luciana

2017-01-01

Dandy-Walker complex (DWC) is a malformative association of the central nervous system. DWC includes four different types: Dandy-Walker malformation (vermis agenesis or hypoplasia, cystic dilatation of the fourth ventricle and a large posterior fossa); Dandy-Walker variant (vermis hypoplasia, cystic dilatation of the fourth ventricle, normal posterior fossa); mega cysterna magna (large posterior fossa, normal vermis and fourth ventricle) and posterior fossa arachnoid cyst. We present and discuss four cases with different morphological and clinical forms of the Dandy-Walker complex. In all four cases, diagnosis was reached by incorporation of clinical (macrocephaly, seizures) and imaging [X-ray, computed tomography (CT), magnetic resonance imaging (MRI)] data. Two patients were diagnosed with Dandy-Walker complex, one patient was diagnosed with Dandy-Walker variant in a rare association with neurofibromatosis and one patient was diagnosed with a posterior fossa arachnoid cyst associated with left-sided Claude Bernard-Horner syndrome, congenital heart disease (coarctation of the aorta, mitral stenosis) and gastroesophageal reflux. In all forms of DWC, the clinical, radiological and functional manifestations are variable and require adequate diagnostic and therapeutic measures.

Image processing-based framework for continuous lane recognition in mountainous roads for driver assistance system

NASA Astrophysics Data System (ADS)

Manoharan, Kodeeswari; Daniel, Philemon

2017-11-01

This paper presents a robust lane detection technique for roads on hilly terrain. The target of this paper is to utilize image processing strategies to recognize lane lines on structured mountain roads with the help of improved Hough transform. Vision-based approach is used as it performs well in a wide assortment of circumstances by abstracting valuable information contrasted with other sensors. The proposed strategy processes the live video stream, which is a progression of pictures, and concentrates on the position of lane markings in the wake of sending the edges through different channels and legitimate thresholding. The algorithm is tuned for Indian mountainous curved and paved roads. A technique of computation is utilized to discard the disturbing lines other than the credible lane lines and show just the required prevailing lane lines. This technique will consequently discover two lane lines that are nearest to the vehicle in a picture as right on time as could reasonably be expected. Various video sequences on hilly terrain are tested to verify the effectiveness of our method, and it has shown good performance with a detection accuracy of 91.89%.

Highway driving safety the day after using sleep medication: the direction of lapses and excursions out-of-lane in drowsy drivers.

PubMed

Verster, Joris C; Mooren, Loes; Bervoets, Adriana C; Roth, Thomas

2017-10-24

The primary outcome measure of the on-road driving test is the Standard Deviation of Lateral Position. However, other outcome measures, such as lapses and excursions out-of-lane, also need to be considered as they may be related to crash risk. The aim of this study was to determine the direction of lapses and excursions out-of-lane (i.e. towards/into the adjacent traffic lane or towards/into the road shoulder). In total, data from 240 driving tests were re-analysed, and 628 lapses and 401 excursions out-of-lane were identified. The analyses revealed that lapses were made equally frequently over left (49.4%) and over right (43.3%). In contrast, excursions out-of-lane were almost exclusively directed over right into the (safer) road shoulder (97.3%). These findings suggest that drivers are unaware of having lapses, whereas excursions out-of-lane are events where the driver is aware of loss of vehicle control. © 2017 The Authors. Journal of Sleep Research published by John Wiley & Sons Ltd on behalf of European Sleep Research Society.

Considerations for high occupancy vehicle (HOV) to high occupancy toll (HOT) lanes conversions primer.

DOT National Transportation Integrated Search

2007-09-01

This primer presents key issues and challenges related to the conversion of high occupancy vehicle (HOV) lanes to high occupancy toll (HOT) lanes. The primer is intended for community leaders, administrators, : the public, and other stakeholders resp...

Evaluation of the Cargill SafeLane surface overlay.

DOT National Transportation Integrated Search

2009-01-01

A recent development in polymer concrete overlays is the Cargill SafeLane surface overlay (SafeLane overlay). The 3/8-in-thick overlay is constructed with epoxy and broadcast aggregates, as are typical multiple-layer epoxy overlays that are used to p...

Impact of transportation demand management (TDM) elements on managed lanes toll prices.

DOT National Transportation Integrated Search

2015-03-01

This research involved a simulation comparing three days of actual traffic data for the I-95 Express : Lanes and General Purpose Lanes in Miami, Florida to a hypothetical scenario where all transportation : demand management (TDM) activities and toll...

Development of warrants for installation of dual right-turn lanes at signalized intersections.

DOT National Transportation Integrated Search

2012-04-01

Right-turn lanes provide space for the deceleration and storage of right-turn vehicles, and separate turning vehicles : from through movements. Dual right-turn lanes are increasingly used at urban intersections primarily for two : reasons: (1) to acc...

Modeling Single Occupant Vehicle Behavior in High-Occupancy Toll (HOT) Facilities

DOT National Transportation Integrated Search

2009-12-14

High-occupancy toll (HOT) lanes are in operation, under construction, and planned for in several major metropolitan areas. The premise behind HOT lanes is to allow single occupant vehicles (SOVs) to access high occupancy vehicle (HOV) lanes (and theo...

0-6811 : reducing lane and shoulder width to permit an additional lane on a freeway.

DOT National Transportation Integrated Search

2015-03-01

This research identified the operational and : safety implications of using reduced lane and : shoulder widths for a variety of freeway : configurations. As demand on Texas freeways : continues to increase, it is important to better : understand the ...

Analysis of Driver Behavior and Operations at Intersection Short Lanes

DOT National Transportation Integrated Search

2016-08-01

With the ever-increasing demand to add roadway capacity in a safe and efficient manner, the application of auxiliary through lanes (ATLs) at intersections has increased in recent years. ATL intersections exist when there is an added through lane intr...

Evaluation of the late merge work zone traffic control strategy.

DOT National Transportation Integrated Search

2004-01-01

Several alternative lane merge strategies have been proposed in recent years to process vehicles through work zone lane closures more safely and efficiently. Among these is the late merge. With the late merge, drivers are instructed to use all lanes ...

Quantitative Analysis for Installation Access Planning at Naval Base San Diego

DTIC Science & Technology

2012-09-01

VPH in one processing lane, then we can assume that if the SECO were to open another sentry processing lane, the total throughput of both lanes would...be 600 VPH . Similarly, if two sentries in tandem can produce a throughput of 500 VPH , then having two lanes with two sentries in tandem each will...produce a total throughput of 1000 VPH . We assume throughout that there is no server idleness and so there is essentially an infinite backlog of

Dynamical density functional theory analysis of the laning instability in sheared soft matter.

PubMed

Scacchi, A; Archer, A J; Brader, J M

2017-12-01

Using dynamical density functional theory (DDFT) methods we investigate the laning instability of a sheared colloidal suspension. The nonequilibrium ordering at the laning transition is driven by nonaffine particle motion arising from interparticle interactions. Starting from a DDFT which incorporates the nonaffine motion, we perform a linear stability analysis that enables identification of the regions of parameter space where lanes form. We illustrate our general approach by applying it to a simple one-component fluid of soft penetrable particles.

Mobility Aids

MedlinePlus

... or have an injury. They include Crutches Canes Walkers Wheelchairs Motorized scooters You may need a walker or cane if you are at risk of ... You should be fitted for crutches, canes and walkers. If they fit, these devices give you support, ...

Older homebound women: negotiating reliance on a cane or walker.

PubMed

Porter, Eileen J; Benson, Jacquelyn J; Matsuda, Sandy

2011-04-01

Canes and walkers are commonly characterized as assistive devices that serve the same purpose: as walking aides. These general views were reappraised and tempered in this descriptive phenomenological study with 40 older women (aged 85 to 98 years) who were unable to leave their homes without help. The purpose was to describe the phenomena of negotiating reliance on canes and walkers as walking devices and the lifeworld context underlying each phenomenon. Relative to lifeworld, there were differences between coming to terms with using a cane and coming to terms with using a walker. Data revealed similarities and distinctions between the basic intentions of relying on canes and walkers and the associated purposes served by canes and walkers. Participants did not view either device as consistently assistive. Findings evoke opportunities for dialogue among older persons, scholars, practitioners, and designers of these devices about coming to terms with such devices and relying on them.

Older Homebound Women: Negotiating Reliance on a Cane or Walker

PubMed Central

Porter, Eileen J.; Benson, Jacquelyn J.; Matsuda, Sandy

2012-01-01

Canes and walkers are commonly characterized as assistive devices and as devices that serve the same purpose, as walking aides. These general views were reappraised and tempered in this descriptive phenomenological study with 40 older women (aged 85-98) who were unable to leave their homes without help. The purpose was to describe the phenomena of negotiating reliance on canes and walkers as walking devices and the lifeworld context underlying each phenomenon. Relative to lifeworld, there were differences between coming to terms with using a cane and coming to terms with using a walker. Data revealed similarities and distinctions between the basic intentions of relying on canes and on walkers and the associated purposes served by canes and walkers. Participants did not view either device as consistently assistive. Findings evoke opportunities for dialogue among older persons, scholars, practitioners, and designers of these devices about coming to terms with such devices and relying on them. PMID:21041520

Spontaneous symmetry breaking in a two-lane model for bidirectional overtaking traffic

NASA Astrophysics Data System (ADS)

Appert-Rolland, C.; Hilhorst, H. J.; Schehr, G.

2010-08-01

Firstly, we consider a unidirectional flux \\bar {\\omega } of vehicles, each of which is characterized by its 'natural' velocity v drawn from a distribution P(v). The traffic flow is modeled as a collection of straight 'world lines' in the time-space plane, with overtaking events represented by a fixed queuing time τ imposed on the overtaking vehicle. This geometrical model exhibits platoon formation and allows, among many other things, for the calculation of the effective average velocity w\\equiv \\phi (v) of a vehicle of natural velocity v. Secondly, we extend the model to two opposite lanes, A and B. We argue that the queuing time τ in one lane is determined by the traffic density in the opposite lane. On the basis of reasonable additional assumptions we establish a set of equations that couple the two lanes and can be solved numerically. It appears that above a critical value \\bar {\\omega }_{\\mathrm {c}} of the control parameter \\bar {\\omega } the symmetry between the lanes is spontaneously broken: there is a slow lane where long platoons form behind the slowest vehicles, and a fast lane where overtaking is easy due to the wide spacing between the platoons in the opposite direction. A variant of the model is studied in which the spatial vehicle density \\bar {\\rho } rather than the flux \\bar {\\omega } is the control parameter. Unequal fluxes \\bar {\\omega }_{\\mathrm {A}} and \\bar {\\omega }_{\\mathrm {B}} in the two lanes are also considered. The symmetry breaking phenomenon exhibited by this model, even though no doubt hard to observe in pure form in real-life traffic, nevertheless indicates a tendency of such traffic.

An evaluation of the real-world safety effect of a lane change driver support system and characteristics of lane change crashes based on insurance claims data.

PubMed

Isaksson-Hellman, Irene; Lindman, Magdalena

2018-02-28

Lane changes, which frequently occur when vehicles travel on major roads, may contribute to critical situations that significantly affect the traffic flow and traffic safety. Thus, knowledge of lane change situations is important for infrastructure improvements as well as for driver support systems and automated driving development projects. The objectives of this study were to evaluate the crash avoidance performance of a lane change driver support system, the Blind Spot Information System (BLIS) in Volvo car models, and to describe the characteristics of lane change crashes by analyzing detailed information from insurance claim reports. An overall evaluation of the safety effect of BLIS was performed by analyzing crash rate differences in lane change situations for cars with and without the optionally mounted BLIS system based on a population of 380,000 insured vehicle years. Further, crashes in which the repair cost of the host vehicle exceeded approximately US$1,250 were selected and compared. Finally, the study examined different precrash factors and crash configurations, using in-depth insurance claims data from representative lane change crash cases including all severity levels in a population of more than 200,000 insured vehicle years. The technology did not significantly reduce the overall number of crashes when all types of lane change crashes and severity levels were considered, though a significant crash-reducing effect of 31% for BLIS cars was found when more severe crashes with a repair cost exceeding US$1,250 were analysed. Cars with the BLIS technology also have a 30% lower claim cost on average for reported lane change crashes, indicating reduced crash severity. When stratifying the data into specific situations, by collecting precrash information in a case-by-case study, the influence of BLIS was indicated to differ for the evaluated situations, although no significant results were found. For example, during general lane change maneuvers (i.e., not while exiting or entering highways or during weaving/merging situations) the crash rate was reduced by 14%, whereas in weaving/merging situations the crash rate increased. The insurance data analyzed provided useful information about real-world lane change crash characteristics by covering collisions in all crash severities and thus revealed information beyond what is available in, for example, data sets of police-reported crashes. This will guide further development of driver support systems. For crashes with repair cost exceeding US$1,250, a significant crash reduction was found, although the technology did not significantly reduce the total number of lane change crashes. An average lower insurance claim cost for cars equipped with the BLIS technology also indicated that the technology contributes to reduced crash severity even if crashes were not totally avoided. Stratifying the data into different lane change crash situations gave indications of the condition-specific performance of the system, even if the results were not statistically significant at the 95% level.

Assessment and validation of managed lanes weaving and access guidelines.

DOT National Transportation Integrated Search

2010-06-01

The goal of this project was to establish spacing requirements for access points to managed lanes : with respect to the location of entrance and exit ramps on the general purpose lanes of the freeway. Traffic : entering the freeway destined for the m...

Safety and operational analysis of 4-lane to 3-lane conversions (road diets) in Michigan.

DOT National Transportation Integrated Search

2012-01-10

Road diets, specifically 4-to-3 lane conversions, implemented in various locations in Michigan were studied to determine the safety- and delay-related impacts, develop crash modification factors (CMFs), and develop guidelines that would be useful in ...

A summary of design, policies and operational characteristics for shared bicycle/bus lanes.

DOT National Transportation Integrated Search

2012-07-01

This report contains the results of an investigation of the design and operation of shared bicycle/bus lanes in municipalities in the United States and other countries. These lanes are designated for use by public transit buses, bicycles, and usually...

Shared-use bus priority lanes on city streets : case studies in design and management

DOT National Transportation Integrated Search

2012-04-01

This report examines the policies and strategies governing the design and, especially, operations of bus lanes in major congested urban centers. It focuses on bus lanes that operate in mixed traffic conditions; the study does not examine practices co...

Enhancing CORSIM for simulating high occupancy/toll lane operations.

DOT National Transportation Integrated Search

2012-03-15

Congestion pricing has been advocated as an efficient way to mitigate traffic congestion : since 1920s. A prevalent form of congestion pricing in the U.S. is high occupancy/toll (HOT) : lanes. The operating objective of HOT lanes is to improve the th...

Investigating the value of time and value of reliability for managed lanes : [summary].

DOT National Transportation Integrated Search

2015-09-01

Managed lanes employ various operational and design strategies to improve highway : efficiency by moving traffic to lanes that are restricted, for example, to drivers with one or : more passengers or to drivers that pay a fee. A drivers decision t...

Development of guidelines for triple left and dual right-turn lanes : technical report.

DOT National Transportation Integrated Search

2011-07-01

Left- or right-turn lanes at intersections improve safety and operations by separating turning and through vehicles. At intersections : with heavy turning demand, it may be necessary to provide multiple turn lanes. Triple left-turn (TLT) and dual rig...

Sensing for HOV/HOT lanes enforcement : final report.

DOT National Transportation Integrated Search

2017-02-01

The use and creation of combined high-occupancy vehicle/high-occupancy toll (HOV/HOT Lanes) have become : more common in urban areas since all types of road users can take advantage of the lane either as a highoccupancy : vehicle or opting in to pay ...

Sensing system development for HOV/HOT (high occupancy vehicle) lane monitoring.

DOT National Transportation Integrated Search

2011-02-01

With continued interest in the efficient use of roadways the ability to monitor the use of HOV/HOT lanes is essential for management, planning and operation. A system to reliably monitor these lanes on a continuous basis and provide usage statistics ...

Sensing system development for HOV/HOT (high occupancy vehicle) lane monitoring.

DOT National Transportation Integrated Search

2011-02-01

. : ii : ABSTRACT : With continued interest in the efficient use of roadways the ability to monitor the use of HOV/HOT lanes is essential for management, planning and operation. A system to reliably monitor these lanes on a continuous basis and provi...

Safety and driver behavior studies at multiple lane approaches to stop-controlled intersections.

DOT National Transportation Integrated Search

2010-05-01

Multiple-lane approaches (MLAs) controlled by stop signs are becoming increasingly common in Nebraska. Installation of MLAs occurs when a single approach lane can no longer adequately serve the minor road traffic volume, and a signal is unwarranted b...

Effective public communication and marketing of high-occupancy-vehicle lanes : an agency perspective

DOT National Transportation Integrated Search

1997-01-01

The Massachusetts Highway Department (MassHighway) opened the Southeast Expressway high-occupancy-vehicle (HOV) lane on November 15, 1995. The 6-mi (9.6-km) contraflow lane, open to vehicles with at least three occupants, was MassHighways third at...

Lifting HOV/HOT lane eligibility and shoulder use restrictions for traffic incident management.

DOT National Transportation Integrated Search

2013-12-01

This report presents an investigation of the possibility of lifting HOV/HOT lane eligibility and shoulder : use restrictions during major incidents on general-purpose (GP) lanes. Using traffic data from FDOT : Districts 4 and 6, the impacts of incide...

Macro-modeling and micro-modeling tools for HOV-to-HOT lane analysis.

DOT National Transportation Integrated Search

2016-06-01

This report summarizes the analysis of observed commuting changes after conversion of an : existing carpool lane into a high-occupancy toll lane, on 15.5 miles of Atlanta I-85. The team explored the : correlations between observed changes in travel b...

Reducing lane and shoulder width to permit an additional lane on a freeway : technical report.

DOT National Transportation Integrated Search

2015-03-01

This research effort identified the operational and safety implications of using reduced lane and : shoulder widths for a variety of freeway configurations. The research team used speed, crash, and geometric : data for freeways in Dallas, Houston, an...

A new traffic model with a lane-changing viscosity term

NASA Astrophysics Data System (ADS)

Ko, Hung-Tang; Liu, Xiao-He; Guo, Ming-Min; Wu, Zheng

2015-09-01

In this paper, a new continuum traffic flow model is proposed, with a lane-changing source term in the continuity equation and a lane-changing viscosity term in the acceleration equation. Based on previous literature, the source term addresses the impact of speed difference and density difference between adjacent lanes, which provides better precision for free lane-changing simulation; the viscosity term turns lane-changing behavior to a “force” that may influence speed distribution. Using a flux-splitting scheme for the model discretization, two cases are investigated numerically. The case under a homogeneous initial condition shows that the numerical results by our model agree well with the analytical ones; the case with a small initial disturbance shows that our model can simulate the evolution of perturbation, including propagation, dissipation, cluster effect and stop-and-go phenomenon. Project supported by the National Natural Science Foundation of China (Grant Nos. 11002035 and 11372147) and Hui-Chun Chin and Tsung-Dao Lee Chinese Undergraduate Research Endowment (Grant No. CURE 14024).

Spacetime emergence of the robertson-walker universe from a matrix model.

PubMed

Erdmenger, Johanna; Meyer, René; Park, Jeong-Hyuck

2007-06-29

Using a novel, string theory-inspired formalism based on a Hamiltonian constraint, we obtain a conformal mechanical system for the spatially flat four-dimensional Robertson-Walker Universe. Depending on parameter choices, this system describes either a relativistic particle in the Robertson-Walker background or metric fluctuations of the Robertson-Walker geometry. Moreover, we derive a tree-level M theory matrix model in this time-dependent background. Imposing the Hamiltonian constraint forces the spacetime geometry to be fuzzy near the big bang, while the classical Robertson-Walker geometry emerges as the Universe expands. From our approach, we also derive the temperature of the Universe interpolating between the radiation and matter dominated eras.

Modeling mechanical restriction differences between car and heavy truck in two-lane cellular automata traffic flow model

NASA Astrophysics Data System (ADS)

Li, Xin; Li, Xingang; Xiao, Yao; Jia, Bin

2016-06-01

Real traffic is heterogeneous with car and truck. Due to mechanical restrictions, the car and the truck have different limited deceleration capabilities, which are important factors in safety driving. This paper extends the single lane safety driving (SD) model with limited deceleration capability to two-lane SD model, in which car-truck heterogeneous traffic is considered. A car has a larger limited deceleration capability while a heavy truck has a smaller limited deceleration capability as a result of loaded goods. Then the safety driving conditions are different as the types of the following and the leading vehicles vary. In order to eliminate the well-known plug in heterogeneous two-lane traffic, it is assumed that heavy truck has active deceleration behavior when the heavy truck perceives the forming plug. The lane-changing decisions are also determined by the safety driving conditions. The fundamental diagram, spatiotemporal diagram, and lane-changing frequency were investigated to show the effect of mechanical restriction on heterogeneous traffic flow. It was shown that there would be still three traffic phases in heterogeneous traffic condition; the active deceleration of the heavy truck could well eliminate the plug; the lane-changing frequency was low in synchronized flow; the flow and velocity would decrease as the proportion of heavy truck grows or the limited deceleration capability of heavy truck drops; and the flow could be improved with lane control measures.

Chronic cerebral herniation in shunted Dandy-Walker malformation.

PubMed

Naidich, T P; Radkowski, M A; McLone, D G; Leestma, J

1986-02-01

A review of serial computed tomography (CT) scans of 25 patients with the Dandy-Walker malformation revealed six patients with chronic downward transincisural herniation of the cerebrum after shunt decompression of the posterior fossa cyst or malfunction of a lateral ventricular drainage catheter, or both. Chronic cerebral herniation was detected postmortem in a seventh patient with the Dandy-Walker malformation. The CT findings and autopsy appearance of this previously undescribed feature of shunted Dandy-Walker malformation are illustrated.

A biomechanical analysis of upper extremity kinetics in children with cerebral palsy using anterior and posterior walkers.

PubMed

Konop, Katherine A; Strifling, Kelly M B; Wang, Mei; Cao, Kevin; Schwab, Jeffrey P; Eastwood, Daniel; Jackson, Scott; Ackman, Jeffrey D; Harris, Gerald F

2009-10-01

Upper extremity (UE) joint kinetics during aided ambulation is an area of research that is not well characterized in the current literature. Biped UE joints are not anatomically designed to be weight bearing, therefore it is important to quantify UE kinetics during assisted gait. This will help to better understand the biomechanical implications of UE weight bearing, and enable physicians to prescribe more effective methods for treatment and therapy, perhaps minimizing excessive loads and torques. To address this challenge, an UE model that incorporates both kinematics and kinetics has been developed for use with walkers instrumented with load cells. In this study, the UE joint kinetics are calculated for 10 children with cerebral palsy using both anterior and posterior walkers. Three-dimensional joint reaction forces and moments are fully characterized for the wrist, elbow, and shoulder (glenohumeral) joints for both walker types. Statistical analysis methods are used to quantify the differences in forces or moments between the two walker types. Comparisons showed no significant differences in kinetic joint parameters between walker types. Results from a power analysis of the current data are provided which may be useful for planning longer term clinical studies. If risk factors for UE joint pathology can be identified early, perhaps a change in gait training routine, walker prescription, or walker design could prevent further harm.

Effects of aging on identifying emotions conveyed by point-light walkers.

PubMed

Spencer, Justine M Y; Sekuler, Allison B; Bennett, Patrick J; Giese, Martin A; Pilz, Karin S

2016-02-01

The visual system is able to recognize human motion simply from point lights attached to the major joints of an actor. Moreover, it has been shown that younger adults are able to recognize emotions from such dynamic point-light displays. Previous research has suggested that the ability to perceive emotional stimuli changes with age. For example, it has been shown that older adults are impaired in recognizing emotional expressions from static faces. In addition, it has been shown that older adults have difficulties perceiving visual motion, which might be helpful to recognize emotions from point-light displays. In the current study, 4 experiments were completed in which older and younger adults were asked to identify 3 emotions (happy, sad, and angry) displayed by 4 types of point-light walkers: upright and inverted normal walkers, which contained both local motion and global form information; upright scrambled walkers, which contained only local motion information; and upright random-position walkers, which contained only global form information. Overall, emotion discrimination accuracy was lower in older participants compared with younger participants, specifically when identifying sad and angry point-light walkers. In addition, observers in both age groups were able to recognize emotions from all types of point-light walkers, suggesting that both older and younger adults are able to recognize emotions from point-light walkers on the basis of local motion or global form. (c) 2016 APA, all rights reserved).

Southeast Expressway High Occupancy Vehicle Lane Evaluation Report

DOT National Transportation Integrated Search

1978-05-01

A non-separated concurrent-flow lane was instituted on Boston's Southeast Expressway on May 4, 1977. An eight-mile section of the left-most inbound lane was reserved for buses and carpools of three or more persons between the hours of 6:30 a.m. and 9...

Houston managed lanes case study : the evolution of the Houston HOV system

DOT National Transportation Integrated Search

2003-09-01

A nine-mile contraflow High Occupancy Vehicle (HOV) lane on the I-45 North Freeway in Houston, Texas was implemented as a demonstration project in 1979. This demonstration borrowed an off-peak direction traffic lane for use by buses and vanpools in t...

Human factors study of driver assistance systems to reduce lane departures and side collision accidents.

DOT National Transportation Integrated Search

2008-07-01

This study investigated the human factors issues related to the implementation of lane departure warning systems (LDWS) to reduce side collision and run-off-road crashes for heavy trucks. Lane departures can be either intentional (e.g., to pass anoth...

Safety evaluation of lane and shoulder width combinations on rural, two-lane, undivided roads

DOT National Transportation Integrated Search

2009-06-01

The Federal Highway Administration (FHWA) organized a pooled fund study of 26 States to evaluate low-cost safety strategies as part of its strategic highway safety effort. The goal of this study is to evaluate the safety effectiveness of various lane...

Policy options evaluation tool for managed lanes (POET-ML) users guide and methodology description : Federal Highway Administration HOV lane performance

DOT National Transportation Integrated Search

2008-12-01

Users guide for a sketch planning tool for exploring policy alternatives. It is intended for an audience of transportation professionals responsible for planning, designing, funding, operating, enforcing, monitoring, and managing HOV and HOT lanes...

Impact of lane closures on roadway capacity, phase 2 : [summary].

DOT National Transportation Integrated Search

2014-01-01

Maintenance or construction on two-lane roads often requires setting up a work zone which closes one lane and uses the other for both traffic directions. Workers posted at each end of the work zone allow traffic to flow alternately one way and then t...

Impact of left lane truck restriction strategies on multilane highways in Louisiana : a literature review.

DOT National Transportation Integrated Search

2009-04-01

Truck lane restriction strategies (TLRS) are a means of managing truck traffic on highways by prohibiting trucks from using certain lanes to minimize interaction between trucks and other vehicles. The purpose of this study is to review the literature...

The influence of curbs on driver behaviors in four-lane rural highways--A driving simulator based study.

PubMed

Yang, Qiang; Overton, Ryan; Han, Lee D; Yan, Xuedong; Richards, Stephen H

2013-01-01

The speed limit of 55mph (88km/h) is typically used on rural highways in the U.S. For locations where curbs are installed along these roadways, some transportation agencies have suggested the use of a lower 45mph (72km/h) speed limit because, according to AASHTO, running into curbs at high speeds may cause significant vehicular damage and even severe injuries. However, it has also been argued that lowering the speed limit after the installation of curbs may cause confusion in drivers, who do not perceive the risk associated with the newly installed curbs and tend to operate their vehicles at the same speed as before. To better understand driver behavior on rural highways before and after curb installation, and with different speed limits, researchers at the University of Tennessee conducted a series of experiments in two-lane and four-lane highways on a high-fidelity driving simulator. This paper mainly presents the findings from the four-lane study, and compares the results from the previous two-lane study. The scenario matrix consists of several dimensions including posted speed limit (45 and 55mph, or 72 and 88km/h), curb installation, lateral clearance between the edge of travel lane and the curb (2ft, 6ft, and no-curb, or 0.6m, 1.8m, and no-curb), weather (clear and fog), traffic conditions in the next lane (1400veh/h and 400veh/h), etc. For each subject under different experimental scenarios, detailed driving parameters, such as driving speed and vehicle position in the travel lane, were recorded and analyzed subsequently. Results of the study suggest that driver behaviors are influenced by the various factors in a complex and interrelated manner. It is likely that drivers do not perceive the risk from the curb in determining their speed on four-lane rural highways. However, it is found that curbs may provide certain guidance to drivers, especially in selecting lane position. Compared to the previous research in two-lane conditions, it is found that drivers are more likely to choose driving speeds according to posted speed limits, rather than lane configurations. It is also found that the relative speed between driver's vehicle and ambient traffic or curbs is an important factor determining drivers' perception of risk and thus their driving behavior. The influence of subjective effects of these factors to their driving behavior is also observed in the study. Copyright © 2012 Elsevier Ltd. All rights reserved.

Multi-pedal DNA walker biosensors based on catalyzed hairpin assembly and isothermal strand-displacement polymerase reaction for the chemiluminescent detection of proteins.

PubMed

Li, Ningxing; Du, Mingyuan; Liu, Yucheng; Ji, Xinghu; He, Zhike

2018-06-25

Two kinds of sensitive biosensors based on multi-pedal DNA walker along a 3-D DNA functional magnet particles track for the chemiluminescent detection of streptavidin are constructed and compared in this study. In the presence of SA, multi-pedal DNA walker has been constructed by biotin-modified catalyst as a result of the terminal protection for avoiding the digestion by exonuclease I. Then a toehold of CHA-H1 conjugated with magnetic microparticles (MMPs) could interact with a 'leg' of multi-pedal DNA walker to open the hairpin via toehold-mediated strand exchange catalysis. A newly exposed DNA segment in CHA-H1 would be hybridized with a toehold of biotin-labeled H2. Via the strand displacement process, H2 displaces one 'leg' of multi-pedal DNA walker, and the other 'leg' could still hybridize with neighboring H1 to initiate the next cycle. In order to solve the high background caused by the hybridization between CHA-H1 and H2 without CHA-catalyst, the other model has been designed. The principle of the other model (ISDPR DNA walker) is similar to the above one. After the terminal protection of SA, a 'leg' of multi-pedal DNA walker triggers the opening of the hairpin of ISDPR-H1 conjugated with MMPs. Then the biotin-modified primer could hybridize with the open stem, triggering the polymerization reaction in the presence of dNTPs/polymerase. As the extension of the primer, the 'leg' of multi-pedal DNA walker is displaced so that the other 'leg' could trigger proximal H1 to go on the next cycle. Due to its lower background and stronger signal, multi-pedal DNA walker based on ISDPR has a lower limit of detection for SA. The limit of detection (LOD) for SA is 6.5 pM. What's more, these DNA walker methods have been applied in complex samples successfully.

Walking on the edge: meanings of living in an ageing body and using a walker in everyday life - a phenomenological hermeneutic study.

PubMed

Brännström, Helene; Bäckman, Margit; Santamäki Fischer, Regina

2013-05-01

In order to maintain one's state of health whilst growing older, the ability to walk is essential. The aim of this study was to illuminate the meanings of the lived experience of living in an ageing body and using a walker in daily life. Narrative interviews were performed with seven older persons aged 79-95 years. The transcribed text was analysed using a phenomenological hermeneutic method. The key finding of the study was that the lived experience of living in an ageing body and using a walker in daily life was interpreted as 'walking on the edge' based on the themes 'Being vulnerable and dependent' and 'Being confident and independent'. The results highlight the importance of reflecting on this phenomenon as a health care professional while meeting the care needs of older persons who use walkers. Nurses need to consider the walker as a personal and valued possession of the individual and handle the walker in agreement with the older person, placing the walker close at hand with the brakes locked to give secure support. © 2012 Blackwell Publishing Ltd.

Design Principles of DNA Enzyme-Based Walkers: Translocation Kinetics and Photoregulation.

PubMed

Cha, Tae-Gon; Pan, Jing; Chen, Haorong; Robinson, Heather N; Li, Xiang; Mao, Chengde; Choi, Jong Hyun

2015-07-29

Dynamic DNA enzyme-based walkers complete their stepwise movements along the prescribed track through a series of reactions, including hybridization, enzymatic cleavage, and strand displacement; however, their overall translocation kinetics is not well understood. Here, we perform mechanistic studies to elucidate several key parameters that govern the kinetics and processivity of DNA enzyme-based walkers. These parameters include DNA enzyme core type and structure, upper and lower recognition arm lengths, and divalent metal cation species and concentration. A theoretical model is developed within the framework of single-molecule kinetics to describe overall translocation kinetics as well as each reaction step. A better understanding of kinetics and design parameters enables us to demonstrate a walker movement near 5 μm at an average speed of ∼1 nm s(-1). We also show that the translocation kinetics of DNA walkers can be effectively controlled by external light stimuli using photoisomerizable azobenzene moieties. A 2-fold increase in the cleavage reaction is observed when the hairpin stems of enzyme catalytic cores are open under UV irradiation. This study provides general design guidelines to construct highly processive, autonomous DNA walker systems and to regulate their translocation kinetics, which would facilitate the development of functional DNA walkers.

Dandy-Walker Malformation: is the 'tail sign' the key sign?

PubMed

Bernardo, Silvia; Vinci, Valeria; Saldari, Matteo; Servadei, Francesca; Silvestri, Evelina; Giancotti, Antonella; Aliberti, Camilla; Porpora, Maria Grazia; Triulzi, Fabio; Rizzo, Giuseppe; Catalano, Carlo; Manganaro, Lucia

2015-12-01

The study aims to demonstrate the value of the 'tail sign' in the assessment of Dandy-Walker malformation. A total of 31 fetal magnetic resonance imaging (MRI), performed before 24 weeks of gestation after second-line ultrasound examination between May 2013 and September 2014, were examined retrospectively. All MRI examinations were performed using a 1.5 Tesla magnet without maternal sedation. Magnetic resonance imaging diagnosed 15/31 cases of Dandy-Walker malformation, 6/31 of vermian partial caudal agenesis, 2/31 of vermian hypoplasia, 4/31 of vermian malrotation, 2/31 of Walker-Warburg syndrome, 1/31 of Blake pouch cyst and 1/31 of rhombencephalosynapsis. All data were compared with fetopsy results, fetal MRI after the 30th week or postnatal MRI; the follow-up depended on the maternal decision to terminate or continue pregnancy. In our review study, we found the presence of the 'tail sign'; this sign was visible only in Dandy-Walker malformation and Walker-Warburg syndrome. The 'tail sign' could be helpful in the difficult differential diagnosis between Dandy-Walker, vermian malrotation, vermian hypoplasia and vermian partial agenesis. © 2015 John Wiley & Sons, Ltd.

Measuring cortical motor hemodynamics during assisted stepping - An fNIRS feasibility study of using a walker.

PubMed

de Lima-Pardini, Andrea Cristina; Zimeo Morais, Guilherme A; Balardin, Joana Bisol; Coelho, Daniel Boari; Azzi, Nametala Maia; Teixeira, Luis Augusto; Sato, João Ricardo

2017-07-01

Walkers are commonly prescribed worldwide to individuals unable to walk independently. Walker usage leads to improved postural control and voluntary movement during step. In the present study, we aimed to provide a concept-proof on the feasibility of an event-related protocol integrating the analyses of biomechanical variables of step initiation and functional near-infrared spectroscopy (fNIRS) to measure activation of the supplementary motor area (SMA) while using a walker. Healthy young participants were tested while stepping with versus without the use of the walker. Behavioral analysis showed that anticipatory postural adjustments (APA) decreased when supporting the body weight on the walker. Delta (without-with) of activation magnitude of the muscle tibialis anterior was positively correlated to the delta of deoxyhemoglobin concentration changes in the SMA. The novelty of this study is the development of a protocol to assess brain function together with biomechanical analysis during the use of a walker. The method sheds light to the potential utility of combining fNIRS and biomechanical assessment during assistive step initiation, which can represent a new opportunity to study populations with mobility deficits. Copyright © 2017 Elsevier B.V. All rights reserved.

Phase II : operational and safety-based analyses of varied toll lane configurations.

DOT National Transportation Integrated Search

2016-08-01

The Puerto Rico Dynamic Toll Lane (DTL) is a 6.44 mi (10.4 km) reversible facility within a stretch of freeway PR-22 that operates a congestion pricing system; the first of its kind in the Commonwealth of Puerto Rico. This managed lane system is shar...

77 FR 8253 - Notice of Proposed Settlement Agreement and Opportunity for Public Comment: Hidden Lane Landfill...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-02-14

... ENVIRONMENTAL PROTECTION AGENCY [FRL-9631-3] Notice of Proposed Settlement Agreement and Opportunity for Public Comment: Hidden Lane Landfill Superfund Site ACTION: Notice. SUMMARY: In accordance... (``DOJ'') on behalf of EPA, in connection with the Hidden Lane Landfill Superfund Site, Sterling, Loudoun...

Evaluation of the effects of changing to continuous access HOT lanes on SR 167 : WSDOT research report.

DOT National Transportation Integrated Search

2016-02-01

In August 2014, The Washington State Department of Transportation (WSDOT) changed the access : controls for the HOT (High Occupancy Toll) lanes on State Route (SR) 167. The lanes were initially designed : and implemented to allow access at only six p...

40 CFR 52.1162 - Regulation for bicycle use.

Code of Federal Regulations, 2010 CFR

2010-07-01

... painted lanes, pavement coloring or other appropriate markings. A peak hour bike lane means a bike lane... following elements: (1) The physical design for bikeways, intersections involving bikeways, and means of... conversion from auto use; (11) The special problems related to the design and incorporation in the bikeway...

40 CFR 52.1162 - Regulation for bicycle use.

Code of Federal Regulations, 2013 CFR

2013-07-01

... painted lanes, pavement coloring or other appropriate markings. A peak hour bike lane means a bike lane... following elements: (1) The physical design for bikeways, intersections involving bikeways, and means of... conversion from auto use; (11) The special problems related to the design and incorporation in the bikeway...

40 CFR 52.1162 - Regulation for bicycle use.

Code of Federal Regulations, 2012 CFR

2012-07-01

... painted lanes, pavement coloring or other appropriate markings. A peak hour bike lane means a bike lane... following elements: (1) The physical design for bikeways, intersections involving bikeways, and means of... conversion from auto use; (11) The special problems related to the design and incorporation in the bikeway...

40 CFR 52.1162 - Regulation for bicycle use.

Code of Federal Regulations, 2011 CFR

2011-07-01

... painted lanes, pavement coloring or other appropriate markings. A peak hour bike lane means a bike lane... following elements: (1) The physical design for bikeways, intersections involving bikeways, and means of... conversion from auto use; (11) The special problems related to the design and incorporation in the bikeway...

40 CFR 52.1162 - Regulation for bicycle use.

Code of Federal Regulations, 2014 CFR

2014-07-01

... painted lanes, pavement coloring or other appropriate markings. A peak hour bike lane means a bike lane... following elements: (1) The physical design for bikeways, intersections involving bikeways, and means of... conversion from auto use; (11) The special problems related to the design and incorporation in the bikeway...

Work zone simulator analysis : driver performance and acceptance of Missouri alternate lane shift configurations.

DOT National Transportation Integrated Search

2017-01-13

The objective of this project is to evaluate MoDOTs alternate lane shift sign configuration for work zones. The single sign proposed by MoDOT provides the traveler with enough information to let them know that all lanes are available to shift arou...

Shared-use bus priority lanes on city streets : case studies in design and management [research brief].

DOT National Transportation Integrated Search

2012-04-01

This study examines the design and operations of bus lanes in major congested urban centers. It focuses on shared-use bus lanes that operate in mixed traffic conditions. : Study Methods : The key questions addressed are: : 1. How do the many public a...

Managed lane operations--adjusted time of day pricing vs. near-real time dynamic pricing : summary.

DOT National Transportation Integrated Search

2012-01-01

In 2008, the Florida Department of Transportation began implementing the 95 Express, a segment of I-95 in Miami with high occupancy toll (HOT) lanes. Some vehicles use HOT lanes free, but most vehicles pay a toll based on real-time traffic conditions...

Studies to determine the operational effects of shoulder and centerline rumble strips on two-lane undivided roadways.

DOT National Transportation Integrated Search

2009-08-01

This report describes the methodology and results of analyses performed to (1) evaluate the impact of : shoulder rumble strips (SRS) and centerline rumble strips (CRS) on the placement of vehicles in the travel : lane of two-lane, undivided roadways ...

75 FR 22578 - Application To Export Electric Energy; Centre Lane Trading Limited

Federal Register 2010, 2011, 2012, 2013, 2014

2010-04-29

... DEPARTMENT OF ENERGY [OE Docket No. EA-365] Application To Export Electric Energy; Centre Lane... application. SUMMARY: Centre Lane Trading Limited (CLT) has applied for authority to transmit electric energy...)). On April 20, 2010, DOE received an application from CLT for authority to transmit electric energy...

Bus--carpool FWY lanes in San Francisco area

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

Newman, L.

1976-11-01

The California Department of Transportation is studying ways to increase the use of the urban freeway systems that will accommodate the maximum number of people with the least delay and the maximum possible safety in a cost-effective way. This paper describes operational features of four different projects under way, namely: a contraflow bus lane; a part-time bus lane in the same direction and unseparated from normal traffic; a bus-carpool lane also in the same direction and unseparated from normal traffic; and a preferential access to a metered freeway. (MCW)

Formal Methods for Information Protection Technology. Task 2: Mathematical Foundations, Architecture and Principles of Implementation of Multi-Agent Learning Components for Attack Detection in Computer Networks. Part 2

DTIC Science & Technology

2003-11-01

Lafayette, IN 47907. [Lane et al-97b] T. Lane and C . E. Brodley. Sequence matching and learning in anomaly detection for computer security. Proceedings of...Mining, pp 259-263. 1998. [Lane et al-98b] T. Lane and C . E. Brodley. Temporal sequence learning and data reduction for anomaly detection ...W. Lee, C . Park, and S. Stolfo. Towards Automatic Intrusion Detection using NFR. 1st USENIX Workshop on Intrusion Detection and Network Monitoring

Effects of turning and through lane sharing on traffic performance at intersections

NASA Astrophysics Data System (ADS)

Li, Xiang; Sun, Jian-Qiao

2016-02-01

Turning vehicles strongly influence traffic flows at intersections. Effective regulation of turning vehicles is important to achieve better traffic performance. This paper studies the impact of lane sharing and turning signals on traffic performance at intersections by using cellular automata. Both right-turn and left-turn lane sharing are studied. Interactions between vehicles and pedestrians are considered. The transportation efficiency, road safety and energy economy are the traffic performance metrics. Extensive simulations are carried out to study the traffic performance indices. It is observed that shared turning lanes and permissive left-turn signal improve the transportation efficiency and reduce the fuel consumption in most cases, but the safety is usually sacrificed. It is not always beneficial for the through vehicles when they are allowed to be in the turning lanes.

The Santa Monica freeway diamond lanes. Volume I. Summary. Final report, March 1976-August 1976

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

Billheimer, J.W.; Bullemer, R.J.; Fratessa, C.

1977-09-01

The Santa Monica Freeway Diamond Lanes, a pair of concurrent-flow preferential lanes for buses and carpools linking the City of Santa Monica, California, with the Los Angeles CBD, opened on March 16, 1976 and operated amid much controversy for 21 weeks until the U.S. District Court halted the project. The Diamond Lane project marked the first time preferential lanes had been created by taking busy freeway lanes out of existing service and dedicating them to the exclusive use of high-occupancy vehicles. This report summarizes the findings of the evaluation of the project. The report addresses a broad range of impactsmore » in the following major areas: Traffic speeds and travel times; traffic volumes and carpool information; bus operations and ridership; safety and enforcement; energy and air quality; and public attitudes and response. Analysis shows that the project succeeded in increasing carpool ridership by 65% and the increased bus service accompanying the Diamond Lanes caused bus ridership to more than triple. Nonetheless, energy savings and air quality improvements were insignificant, freeway accidents increased significantly, non-carpoolers lost far more time than carpoolers gained, and a heated public outcry developed which has delayed the implementation of other preferential treatment projects in S. California.« less

Real-Time Lane Region Detection Using a Combination of Geometrical and Image Features

PubMed Central

Cáceres Hernández, Danilo; Kurnianggoro, Laksono; Filonenko, Alexander; Jo, Kang Hyun

2016-01-01

Over the past few decades, pavement markings have played a key role in intelligent vehicle applications such as guidance, navigation, and control. However, there are still serious issues facing the problem of lane marking detection. For example, problems include excessive processing time and false detection due to similarities in color and edges between traffic signs (channeling lines, stop lines, crosswalk, arrows, etc.). This paper proposes a strategy to extract the lane marking information taking into consideration its features such as color, edge, and width, as well as the vehicle speed. Firstly, defining the region of interest is a critical task to achieve real-time performance. In this sense, the region of interest is dependent on vehicle speed. Secondly, the lane markings are detected by using a hybrid color-edge feature method along with a probabilistic method, based on distance-color dependence and a hierarchical fitting model. Thirdly, the following lane marking information is extracted: the number of lane markings to both sides of the vehicle, the respective fitting model, and the centroid information of the lane. Using these parameters, the region is computed by using a road geometric model. To evaluate the proposed method, a set of consecutive frames was used in order to validate the performance. PMID:27869657

Neutral signature Walker-CSI metrics

NASA Astrophysics Data System (ADS)

Coley, A.; Musoke, N.

2015-03-01

We will construct explicit examples of four-dimensional neutral signature Einstein Walker spaces for which all of the polynomial scalar curvature invariants are constant. We show that these Einstein Walker spaces are Kundt. We then investigate the mathematical properties of the spaces, including holonomy and universality.

Dynamical spacetimes in conformal gravity

NASA Astrophysics Data System (ADS)

Zhang, Hongsheng; Zhang, Yi; Li, Xin-Zhou

2017-08-01

The conformal gravity remarkably boosts our prehension of gravity theories. We find a series of dynamical solutions in the W2-conformal gravity, including generalized Schwarzschild-Friedmann-Robertson-Walker (GSFRW), charged generalized Schwarzschild-Friedmann-Robertson-Walker (CGSFRW), especially rotating Friedmann-Robertson-Walker (RFRW), charged rotating Friedmann-Robertson-Walker (CRFRW), and a dynamical cylindrically symmetric solutions. The RFRW, CRFRW and the dynamical cylindrically symmetric solutions are never found in the Einstein gravity and modified gravities. The GSFRW and CGSFRW solutions take different forms from the corresponding solutions in the Einstein gravity.

Walking my way? Walker gender and display format Confounds the perception of specific emotions.

PubMed

Halovic, Shaun; Kroos, Christian

2018-02-01

Previous evidence has shown that males and females display different gait kinematics which may influence the perception of emotions displayed through the same walking gait. We therefore investigated the influence of walker gender on the perception of happiness, sadness, anger and fear displayed through walking movements. Full-light (FL), point-light (PL) and synthetically modelled point-light walkers (SW) of both genders were shown to perceivers over three experiments. Additionally, gender ambiguous synthetic walkers were shown to control for the influence of form, gender stereotypes and idiosyncratic gait movements on emotional gait perception. Each emotion was identified above chance level for both walker genders and in all display conditions though significantly less in PL and SW than in FL. The gender of the walker did not influence the pattern of identifications in FL walkers (Fear > Sad > Happy > Anger > Neutral), but did influence the identification patterns in PL (Female: [Happy = Sad = Fear = Anger] > Neutral; Male: Fear = Sad = [Happy > Anger] > Neutral) and SWs (Female: Happy = Sad = Anger = Fear = Neutral; Male: [Happy = Sad = Anger] > [Fear = Neutral]; Ambiguous: [[Happy = Sad = Anger] > Fear] = Neutral). The gender of the walker and format in which they are displayed influenced the perception of different basic emotions. The constructed SW stimuli also displayed happiness, sadness and anger with equivalent intensity in female, male and gender ambiguous walkers thus untangling the perception-expression entanglement that has plagued previous emotion perception research. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

Dataset reporting the perceiver identification rates of basic emotions expressed by male, female and ambiguous gendered walkers in full-light, point-light and synthetically modelled point-light walkers.

PubMed

Halovic, Shaun; Kroos, Christian

2017-12-01

This data set describes the experimental data collected and reported in the research article "Walking my way? Walker gender and display format confounds the perception of specific emotions" (Halovic and Kroos, in press) [1]. The data set represent perceiver identification rates for different emotions (happiness, sadness, anger, fear and neutral), as displayed by full-light, point-light and synthetic point-light walkers. The perceiver identification scores have been transformed into H t rates, which represent proportions/percentages of correct identifications above what would be expected by chance. This data set also provides H t rates separately for male, female and ambiguously gendered walkers.

A walking prescription for statically-stable walkers based on walker/terrain interaction

NASA Technical Reports Server (NTRS)

Nagy, Peter V.; Whittaker, William L.; Desa, Subhas

1992-01-01

The walker/terrain interaction phenomena for the control of a statically stable walking machine are described. The algorithms, measures, and knowledge of walker/terrain interaction phenomena are then combined to form a prescription for how to walk on general terrain. This prescription consists of two parts: nominal control and reactive control. The function of nominal control is the evaluation and execution of planned motions, based on predicted foot force redistributions, to achieve reliable locomotion. The function of reactive control is the monitoring of walker/terrain interaction in real-time to detect anomalous conditions and then respond with the appropriate reflexive actions. Simulations and experiments have been used to test and verify various aspects of the walking prescription.

AmeriFlux US-WBW Walker Branch Watershed

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

Meyers, Tilden

2016-01-01

This is the AmeriFlux version of the carbon flux data for the site US-WBW Walker Branch Watershed. Site Description - The stand is over 50 years old, having regenerated from agricultural land.This site is located near Oak Ridge, Tennessee near the Walker Branch Watershed.

Evolution in the Dust Lane Fraction of Edge-on L* V Spiral Galaxies Since z = 0.8

NASA Astrophysics Data System (ADS)

Holwerda, B. W.; Dalcanton, J. J.; Radburn-Smith, D.; de Jong, R. S.; Guhathakurta, P.; Koekemoer, A.; Allen, R. J.; Böker, T.

2012-07-01

The presence of a well-defined and narrow dust lane in an edge-on spiral galaxy is the observational signature of a thin and dense molecular disk, in which gravitational collapse has overcome turbulence. Using a sample of galaxies out to z ~ 1 extracted from the COSMOS survey, we identify the fraction of massive (L* V ) disks that display a dust lane. Our goal is to explore the evolution in the stability of the molecular interstellar medium (ISM) disks in spiral galaxies over a cosmic timescale. We check the reliability of our morphological classifications against changes in rest-frame wavelength, resolution, and cosmic dimming with (artificially redshifted) images of local galaxies from the Sloan Digital Sky Survey. We find that the fraction of L* V disks with dust lanes in COSMOS is consistent with the local fraction (≈80%) out to z ~ 0.7. At z = 0.8, the dust lane fraction is only slightly lower. A somewhat lower dust lane fraction in starbursting galaxies tentatively supports the notion that a high specific star formation rate can efficiently destroy or inhibit a dense molecular disk. A small subsample of higher redshift COSMOS galaxies display low internal reddening (E[B - V]), as well as a low incidence of dust lanes. These may be disks in which the growth of the dusty ISM disk lags behind that of the stellar disk. We note that at z = 0.8, the most massive galaxies display a lower dust lane fraction than lower mass galaxies. A small contribution of recent mergers or starbursts to this most massive population may be responsible. The fact that the fraction of galaxies with dust lanes in COSMOS is consistent with little or no evolution implies that models to explain the spectral energy distribution or the host galaxy dust extinction of supernovae based on local galaxies are still applicable to higher redshift spirals. It also suggests that dust lanes are long-lived phenomena or can be reformed over very short timescales.

Prevalence of driver physical factors leading to unintentional lane departure crashes.

PubMed

Cicchino, Jessica B; Zuby, David S

2017-07-04

Some lane-keeping assist systems in development and production provide autonomous braking and steering to correct unintentional lane drift but otherwise require drivers to fully control their vehicles. The goal of this study was to quantify the proportion of drivers involved in unintentional lane drift crashes who would be unable to regain control of their vehicles to inform the design of such systems. The NHTSA's National Motor Vehicle Crash Causation Survey collected in-depth, on-scene data for a nationally representative sample of 5,470 U.S. police-reported passenger vehicle crashes during 2005-2007 that occurred between 6 a.m. and midnight and for which emergency medical services were dispatched. The physical states of drivers involved in the 631 lane drift crashes in the sample, which represented 259,034 crashes nationally, were characterized. Thirty-four percent of drivers who crashed because they drifted from their lanes were sleeping or otherwise incapacitated. These drivers would be unlikely to regain full control of their vehicles if an active safety system prevented their initial drift. An additional 13% of these drivers had a nonincapacitating medical issue, blood alcohol concentration (BAC) ≥ 0.08%, or other physical factor that may not allow them to regain full vehicle control. When crashes involved serious or fatal injuries, 42% of drivers who drifted were sleeping or otherwise incapacitated, and an additional 14% were impacted by a nonincapacitating medical issue, BAC ≥ 0.08%, or other physical factor. Designers of active safety systems that provide autonomous lateral control should consider that a substantial proportion of drivers at risk of lane drift crashes are incapacitated. Systems that provide only transient corrective action may not ultimately prevent lane departure crashes for these drivers, and drivers who do avoid lane drift crashes because of these systems may be at high risk of other types of crashes when they attempt to regain control. Active lane-keeping assist systems may need to be combined with in-vehicle driver monitoring to identify incapacitated drivers and safely remove them from the roadway if the systems are to reach their maximum potential benefit.

EVOLUTION IN THE DUST LANE FRACTION OF EDGE-ON L*{sub V} SPIRAL GALAXIES SINCE z = 0.8

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

Holwerda, B. W.; Boeker, T.; Dalcanton, J. J.

2012-07-01

The presence of a well-defined and narrow dust lane in an edge-on spiral galaxy is the observational signature of a thin and dense molecular disk, in which gravitational collapse has overcome turbulence. Using a sample of galaxies out to z {approx} 1 extracted from the COSMOS survey, we identify the fraction of massive (L*{sub V}) disks that display a dust lane. Our goal is to explore the evolution in the stability of the molecular interstellar medium (ISM) disks in spiral galaxies over a cosmic timescale. We check the reliability of our morphological classifications against changes in rest-frame wavelength, resolution, andmore » cosmic dimming with (artificially redshifted) images of local galaxies from the Sloan Digital Sky Survey. We find that the fraction of L*{sub V} disks with dust lanes in COSMOS is consistent with the local fraction ( Almost-Equal-To 80%) out to z {approx} 0.7. At z = 0.8, the dust lane fraction is only slightly lower. A somewhat lower dust lane fraction in starbursting galaxies tentatively supports the notion that a high specific star formation rate can efficiently destroy or inhibit a dense molecular disk. A small subsample of higher redshift COSMOS galaxies display low internal reddening (E[B - V]), as well as a low incidence of dust lanes. These may be disks in which the growth of the dusty ISM disk lags behind that of the stellar disk. We note that at z = 0.8, the most massive galaxies display a lower dust lane fraction than lower mass galaxies. A small contribution of recent mergers or starbursts to this most massive population may be responsible. The fact that the fraction of galaxies with dust lanes in COSMOS is consistent with little or no evolution implies that models to explain the spectral energy distribution or the host galaxy dust extinction of supernovae based on local galaxies are still applicable to higher redshift spirals. It also suggests that dust lanes are long-lived phenomena or can be reformed over very short timescales.« less

Robust Lane Sensing and Departure Warning under Shadows and Occlusions

PubMed Central

Tapia-Espinoza, Rodolfo; Torres-Torriti, Miguel

2013-01-01

A prerequisite for any system that enhances drivers' awareness of road conditions and threatening situations is the correct sensing of the road geometry and the vehicle's relative pose with respect to the lane despite shadows and occlusions. In this paper we propose an approach for lane segmentation and tracking that is robust to varying shadows and occlusions. The approach involves color-based clustering, the use of MSAC for outlier removal and curvature estimation, and also the tracking of lane boundaries. Lane boundaries are modeled as planar curves residing in 3D-space using an inverse perspective mapping, instead of the traditional tracking of lanes in the image space, i.e., the segmented lane boundary points are 3D points in a coordinate frame fixed to the vehicle that have a depth component and belong to a plane tangent to the vehicle's wheels, rather than 2D points in the image space without depth information. The measurement noise and disturbances due to vehicle vibrations are reduced using an extended Kalman filter that involves a 6-DOF motion model for the vehicle, as well as measurements about the road's banking and slope angles. Additional contributions of the paper include: (i) the comparison of textural features obtained from a bank of Gabor filters and from a GMRF model; and (ii) the experimental validation of the quadratic and cubic approximations to the clothoid model for the lane boundaries. The results show that the proposed approach performs better than the traditional gradient-based approach under different levels of difficulty caused by shadows and occlusions. PMID:23478598

[Upper extremity kinetics and energy expenditure during walker-assisted gait in children with cerebral palsy].

PubMed

Konop, Katherine A; Strifling, Kelly M B; Wang, Mei; Cao, Kevin; Eastwood, Daniel; Jackson, Scott; Ackman, Jeffrey; Altiok, Haluk; Schwab, Jeffrey; Harris, Gerald F

2009-01-01

We evaluated the relationships between upper extremity (UE) kinetics and the energy expenditure index during anterior and posterior walker-assisted gait in children with spastic diplegic cerebral palsy (CP). Ten children (3 boys, 7 girls; mean age 12.1 years; range 8 to 18 years) with spastic diplegic CP, who ambulated with a walker underwent gait analyses that included UE kinematics and kinetics. Upper extremity kinetics were obtained using instrumented walker handles. Energy expenditure index was obtained using the heart rate method (EEIHR) by subtracting resting heart rate from walking heart rate, and dividing by the walking speed. Correlations were sought between the kinetic variables and the EEIHR and temporal and stride parameters. In general, anterior walker use was associated with a higher EEIHR. Several kinetic variables correlated well with temporal and stride parameters, as well as the EEIHR. All of the significant correlations (r>0.80; p<0.005) occurred during anterior walker use and involved joint reaction forces (JRF) rather than moments. Some variables showed multiple strong correlations during anterior walker use, including the medial JRF in the wrist, the posterior JRF in the elbow, and the inferior and superior JRFs in the shoulder. The observed correlations may indicate a relationship between the force used to advance the body forward within the walker frame and an increased EEIHR. More work is needed to refine the correlations, and to explore relationships with other variables, including the joint kinematics.

49 CFR 325.33 - Site characteristics; highway operations.

Code of Federal Regulations, 2010 CFR

2010-10-01

... includes a portion of, a traveled lane of a public highway. A microphone target point shall be established on the centerline of the traveled lane of the highway, and a microphone location point shall be... microphone target point and on a line that is perpendicular to the centerline of the traveled lane of the...

Operational and safety impacts of restriping inside lanes of urban multilane curbed roadways to 11 feet or less to create wider outside curb lanes for bicyclists.

DOT National Transportation Integrated Search

2011-09-30

This study analyzes the influence of several site characteristics on the operational behavior of motorists when passing bicyclists on wider outside through lanes. More than 2000 videotaped passing events were analyzed. Several measures of effectivene...

Alternative Fuels Data Center

Science.gov Websites

Virginia Clean Special Fuel license plate may use Virginia HOV lanes, regardless of the number of occupants license plates issued before July 1, 2011, are exempt from HOV lane requirements. For express lanes serving the I-95/I-395 corridor, registered vehicles displaying Clean Special Fuel license plates are not

SOUTHEAST BY 125 DEGREES, NORTHWEST PORTAL. NOTE THE BRIDGE HAS ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

SOUTHEAST BY 125 DEGREES, NORTHWEST PORTAL. NOTE THE BRIDGE HAS THREE TRUSSES AND TWO LANES OF UNEQUAL WIDTH. THE LARGER LANE WAS FOR VEHICLES AND FARM MACHINERY, WHILE THE SMALLER LANE WAS FOR ANIMALS AND POSSIBLY PEDESTRIANS. - Rollins Farm Bridge, Spanning Boston & Maine Railroad at Ham Road, Rollinsford, Strafford County, NH

Certified organic farming research and demonstration project by Oklahoma State University and USDA's Agricultural Research Service at Lane, Oklahoma

USDA-ARS?s Scientific Manuscript database

In 2003, Oklahoma State University and USDA, Agricultural Research Service, South Central Agricultural Research Laboratory received organic certification for 8 acres at the Lane Agricultural Center, Lane, OK. The certified organic land was used to develop a cooperative project with a diversity of a...

Proposed Occupational Exploration Program for Cady School--Long Lane, Middletown, Connecticut.

ERIC Educational Resources Information Center

Williams, Michael J.

Long Lane School is a coeducational, residential treatment facility for juvenile delinquents in Middletown, Connecticut. The Proposed Occupational Exploration Program described in this document is intended to provide the dual function of career exploration for the approximately 425 residents of Long Lane and a means for integrating the academic…

MARMION WAY AND AVENUE 66 ENTRANCE TO SOUTHBOUND LANES OF ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

MARMION WAY AND AVENUE 66 ENTRANCE TO SOUTHBOUND LANES OF ARROYO SECO PARKWAY. NOTE SMALL ISLAND AND SHORT ACCESS LANES. SEEN FROM SAME CAMERA POSITION ON DEBS PARK HILL AS CA-265-14. LOOKING 0°N - Arroyo Seco Parkway, Marmion Way Bridge, Milepost 29.28, Los Angeles, Los Angeles County, CA

Analyzing Driver Behavior in Passing Zones with Differential Speed Limits on Two-Lane Two-Way Undivided Highways in Alaska

DOT National Transportation Integrated Search

2017-12-01

Due to the relatively high crash rates attributed to two lane highways in Alaska, solutions have been explored to improve safety by providing passing lanes to give drivers a better chance to pass the slow moving vehicles. Drivers of slow moving vehic...

Phase-plane analysis of the totally asymmetric simple exclusion process with binding kinetics and switching between antiparallel lanes

PubMed Central

Kuan, Hui-Shun; Betterton, Meredith D.

2016-01-01

Motor protein motion on biopolymers can be described by models related to the totally asymmetric simple exclusion process (TASEP). Inspired by experiments on the motion of kinesin-4 motors on antiparallel microtubule overlaps, we analyze a model incorporating the TASEP on two antiparallel lanes with binding kinetics and lane switching. We determine the steady-state motor density profiles using phase-plane analysis of the steady-state mean field equations and kinetic Monte Carlo simulations. We focus on the density-density phase plane, where we find an analytic solution to the mean field model. By studying the phase-space flows, we determine the model’s fixed points and their changes with parameters. Phases previously identified for the single-lane model occur for low switching rate between lanes. We predict a multiple coexistence phase due to additional fixed points that appear as the switching rate increases: switching moves motors from the higher-density to the lower-density lane, causing local jamming and creating multiple domain walls. We determine the phase diagram of the model for both symmetric and general boundary conditions. PMID:27627345

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

21 CFR 890.3825 - Mechanical walker.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mechanical walker. 890.3825 Section 890.3825 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES PHYSICAL MEDICINE DEVICES Physical Medicine Prosthetic Devices § 890.3825 Mechanical walker. (a...

Evaluation of safety effect of turbo-roundabout lane dividers using floating car data and video observation.

PubMed

Kieć, Mariusz; Ambros, Jiří; Bąk, Radosław; Gogolín, Ondřej

2018-06-01

Roundabouts are one of the safest types of intersections. However, the needs to meet the requirements of operation, capacity, traffic organization and surrounding development lead to a variety of design solutions. One of such alternatives are turbo-roundabouts, which simplify drivers' decision making, limit lane changing in the roundabout, and induce low driving speed thanks to raised lane dividers. However, in spite of their generally positive reception, the safety impact of turbo-roundabouts has not been sufficiently studied. Given the low number of existing turbo-roundabouts and the statistical rarity of accident occurrence, the prevalent previously conducted studies applied only simple before-after designs or relied on traffic conflicts in micro-simulations. Nevertheless, the presence of raised lane dividers is acknowledged as an important feature of well performing and safe turbo-roundabouts. Following the previous Polish studies, the primary objective of the present study was assessment of influence of presence of lane dividers on road safety and developing a reliable and valid surrogate safety measure based on field data, which will circumvent the limitations of accident data or micro-simulations. The secondary objective was using the developed surrogate safety measure to assess and compare the safety levels of Polish turbo-roundabout samples with and without raised lane dividers. The surrogate safety measure was based on speed and lane behaviour. Speed was obtained from video observations and floating car data, which enabled the construction of representative speed profiles. Lane behaviour data was gathered from video observations. The collection of the data allowed for a relative validation of the method by comparing the safety performance of turbo-roundabouts with and without raised lane dividers. In the end, the surrogate measure was applied for evaluation of safety levels and enhancement of the existing safety performance functions, which combine traffic volumes, and speeds as a function of radii). The final models may help quantify the safety impact of different turbo-roundabout solutions. Copyright © 2018 Elsevier Ltd. All rights reserved.

Is improved lane keeping during cognitive load caused by increased physical arousal or gaze concentration toward the road center?

PubMed

Li, Penghui; Markkula, Gustav; Li, Yibing; Merat, Natasha

2018-08-01

Driver distraction is one of the main causes of motor-vehicle accidents. However, the impact on traffic safety of tasks that impose cognitive (non-visual) distraction remains debated. One particularly intriguing finding is that cognitive load seems to improve lane keeping performance, most often quantified as reduced standard deviation of lateral position (SDLP). The main competing hypotheses, supported by current empirical evidence, suggest that cognitive load improves lane keeping via either increased physical arousal, or higher gaze concentration toward the road center, but views are mixed regarding if, and how, these possible mediators influence lane keeping performance. Hence, a simulator study was conducted, with participants driving on a straight city road section whilst completing a cognitive task at different levels of difficulty. In line with previous studies, cognitive load led to increased physical arousal, higher gaze concentration toward the road center, and higher levels of micro-steering activity, accompanied by improved lane keeping performance. More importantly, during the high cognitive task, both physical arousal and gaze concentration changed earlier in time than micro-steering activity, which in turn changed earlier than lane keeping performance. In addition, our results did not show a significant correlation between gaze concentration and physical arousal on the level of individual task recordings. Based on these findings, various multilevel models for micro-steering activity and lane keeping performance were conducted and compared, and the results suggest that all of the mechanisms proposed by existing hypotheses could be simultaneously involved. In other words, it is suggested that cognitive load leads to: (i) an increase in arousal, causing increased micro-steering activity, which in turn improves lane keeping performance, and (ii) an increase in gaze concentration, causing lane keeping improvement through both (a) further increased micro-steering activity and (b) a tendency to steer toward the gaze target. Copyright © 2018 Elsevier Ltd. All rights reserved.

Lane change warning threshold based on driver perception characteristics.

PubMed

Wang, Chang; Sun, Qinyu; Fu, Rui; Li, Zhen; Zhang, Qiong

2018-08-01

Lane Change Warning system (LCW) is exploited to alleviate driver workload and improve the safety performance of lane changes. Depending on the secure threshold, the lane change warning system could transmit caution to drivers. Although the system possesses substantial benefits, it may perturb the conventional operating of the driver and affect driver judgment if the warning threshold does not conform to the driver perception of safety. Therefore, it is essential to establish an appropriate warning threshold to enhance the accuracy rate and acceptability of the lane change warning system. This research aims to identify the threshold that conforms to the driver perception of the ability to safely change lanes with a rear vehicle fast approaching. We propose a theoretical warning model of lane change based on a safe minimum distance and deceleration of the rear vehicle. For the purpose of acquiring the different safety levels of lane changes, 30 licensed drivers are recruited and we obtain the extreme moments represented by driver perception characteristics from a Front Extremity Test and a Rear Extremity Test implemented on the freeway. The required deceleration of the rear vehicle corresponding to the extreme time is calculated according to the proposed model. In light of discrepancies in the deceleration in these extremity experiments, we determine two levels of a hierarchical warning system. The purpose of the primary warning is to remind drivers of the existence of potentially dangerous vehicles and the second warning is used to warn the driver to stop changing lanes immediately. We use the signal detection theory to analyze the data. Ultimately, we confirm that the first deceleration threshold is 1.5 m/s 2 and the second deceleration threshold is 2.7 m/s 2 . The findings provide the basis for the algorithm design of LCW and enhance the acceptability of the intelligent system. Copyright © 2018 Elsevier Ltd. All rights reserved.

33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 33 Navigation and Navigable Waters 2 2010-07-01 2010-07-01 false Security Zone: Walkers Point, Kennebunkport ME. 165.102 Section 165.102 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... Zone: Walkers Point, Kennebunkport ME. (a) Location. The following area is a security zone: From point...

33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 33 Navigation and Navigable Waters 2 2013-07-01 2013-07-01 false Security Zone: Walkers Point, Kennebunkport ME. 165.102 Section 165.102 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... Zone: Walkers Point, Kennebunkport ME. (a) Location. The following area is a security zone: From point...

33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Security Zone: Walkers Point, Kennebunkport ME. 165.102 Section 165.102 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... Zone: Walkers Point, Kennebunkport ME. (a) Location. The following area is a security zone: From point...

33 CFR 165.102 - Security Zone: Walkers Point, Kennebunkport ME.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Security Zone: Walkers Point, Kennebunkport ME. 165.102 Section 165.102 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND... Zone: Walkers Point, Kennebunkport ME. (a) Location. The following area is a security zone: From point...

Payload Specialist Charles Walker with handheld protein growth experiment

NASA Image and Video Library

1985-11-26

61B-02-014 (26 Nov-3 Dec 1985) --- Payload Specialist Charles D. Walker works with the handheld protein growth experiment -- one of a series of tests being flown to study the possibility of crystallizing biological materials. Walker rests the experiment against the larger continuous flow electrophoresis systems experiment.

Dandy-Walker Malformation Presenting with Psychological Manifestations.

PubMed

Rohanachandra, Yasodha Maheshi; Dahanayake, Dulangi Maneksha Amerasinghe; Wijetunge, Swarna

2016-01-01

Dandy-Walker malformation, which is a congenital malformation of the cerebellum, is documented in literature to be associated with psychotic symptoms, obsessive compulsive symptoms, mood symptoms, hyperactivity, and impulsive behavior. The pathogenesis of psychiatric symptoms in Dandy-Walker malformation is thought to be due to disruption of the corticocerebellar tracts, resulting in what is known as cerebellar cognitive affective syndrome. We present a case of Dandy-Walker malformation presenting with psychiatric symptoms. This case highlights the necessity to be aware of psychiatric manifestations of cerebellar disease as it has an impact on the diagnosis and treatment.

Dandy-Walker malformation: a rare association with hypoparathyroidism.

PubMed

Coban, Dilek; Akin, Mustafa Ali; Kurtoglu, Selim; Oktem, Suat; Yikilmaz, Ali

2010-12-01

Dandy-Walker malformation is characterized by cystic dilatation of the fourth ventricle and an enlarged posterior cranial fossa with upward displacement of the tentorium, lateral sinuses, and torcular, with agenesis or hypoplasia of the cerebellar vermis. Dandy-Walker malformation occurs in approximately the 4th week of gestation and is associated with various abnormalities involving the cardiac, skeletal, genitourinary, and gastrointestinal systems. The parathyroid gland also forms in the 3rd and 4th gestational weeks. Reported here is the case of a male infant with Dandy-Walker malformation with ventricular and atrial septal defect, unilateral renal agenesis, and hypoparathyroidism. To our knowledge, this rare association with neural crest events during the development of Dandy-Walker malformation has not been reported previously. Crown Copyright © 2010. Published by Elsevier Inc. All rights reserved.

A Review of the Planthopper Genus Armacia Stål (Hemiptera: Fulgoromorpha: Ricaniidae) with Descriptions of Four New Species from Indonesia and Papua New Guinea

PubMed Central

Bu, Cui-Ping; Fletcher, Murray J; Liang, Ai-Ping

2011-01-01

The genus Armacia Stål (Hemiptera: Fulgoromorpha: Ricaniidae) is reviewed taxonomically. Four new species of the genus are described and illustrated from West-Pacific region: A. madangensis sp. nov. (Papua New Guinea), A. rubilimba sp. nov. (Indonesia), A. spinae sp. nov. (Indonesia) and A. vigorata sp. nov. (Indonesia), A. albipes (Walker 1868), A. clara (Stål 1859), A. divisura (Walker 1868), A. fusca Melichar 1898, A. hyalinata (Donovan 1805), A. latipennis (Walker 1868), A. nigrifrons (Walker 1858), A. simaethis Fennah 1956, and A. spatiosa (Walker 1868) are redescribed and illustrated. A checklist of all known species and a diagnosis of the genus are provided. A key to all species in the genus is provided. PMID:21870985

Dog ownership, functional ability, and walking in community-dwelling older adults.

PubMed

Gretebeck, Kimberlee A; Radius, Kaitlyn; Black, David R; Gretebeck, Randall J; Ziemba, Rosemary; Glickman, Lawrence T

2013-07-01

Regular walking improves overall health and functional ability of older adults, yet most are sedentary. Dog ownership/pet responsibility may increase walking in older adults. Goals of this study were to identify factors that influence older adult walking and compare physical activity, functional ability and psychosocial characteristics by dog ownership status. In this cross-sectional study, older adults (65-95 years of age, n = 1091) completed and returned questionnaires via postal mail. Measures included: Physical Activity Scale for the Elderly, Physical Functioning Questionnaire and Theory of Planned Behavior Questionnaire. Dog owner/dog walkers (n = 77) reported significantly (P < .05) more total walking, walking frequency, leisure and total physical activity and higher total functional ability than dog owner/nondog walkers (n = 83) and nondog owners (n = 931). Dog owner/nondog walkers reported lower intention and perceived behavioral control and a less positive attitude than dog owner/dog walkers (P < .05). Dog owner/ dog walkers were significantly different than the nondog walker groups in nearly every study variable. Many dog owners (48.1%) reported walking their dogs regularly and the dog owner/dog walkers participated in nearly 50% more total walking than the 2 nondog walking groups, suggesting that pet obligation may provide a purposeful activity that motivates some older dog owners to walk.

[Effect of abducens orthosis combined with walker on developmental dysplasia of the hip].

PubMed

Hu, Zhiyong; Xu, Yongqiang; Liang, Jieyu; Li, Kanghua; Liao, Qiande

2009-07-01

To evaluate the effect of abducens orthosis combined with walker on developmental dysplasia of the hip (DDH). A total of 126 patients (224 hips) with DDH aged 6-36 months in Xiangya Hospital was randomly divided into 2 groups: an orthosis combined with walker group and an improved hip frog cast fixation group. Seventy patients (130 hips) were treated by the orthosis combined with walker and 56 patients (94 hips) were treated by the improved hip frog cast fixation. We compared the effect and complications of the 2 groups. The fineness rates of the orthosis combined with walker group and the improved hip frog cast fixation group were 89.2% and 90.4%, respectively, with no significant difference (P>0.05). The rate of femoral head osteonecrosis in the orthosis combined with walker group was significantly lower than that in the improved hip frog cast fixation group (1.5% vs. 5.3%,P<0.05), but the re-dislocation rate in the former was significantly higher than that in the latter (6.9% vs. 1.1 %, P<0.05). Both methods are effective for DDH. Orthosis combined with walker has a lower proportion of femoral head osteonecrosis, but a higher proportion of re-dislocation.

A new walker with upper trunk suspension system for severely disabled patients.

PubMed

Scoppetta, C; Scoppetta, M

2013-10-01

We have recently designed a new type of walker for those severely disabled patients who cannot walk with commonly used medical walkers. A drawing and the description of this new walker is reported in order to permit the worldwide companies as well as artisans to develop and produce it for the people affected from severe motor problems. This walker supposes the patient wearing either a modified climbing harness or equipped clothes and being suspended to the walking frame. It consists in two series of bands suspending the patient from the frame; the upper one suspends him for the upper part of his trunk, the lower one by his pelvis. This walker is suggested for patients belonging to three principal groups: (1) Persons who have no trunk control (e.g.: patients affected by severe stroke or ataxias). (2) Persons whose walk is allowed only if they achieve a significant reduction (up to 30-40%) of the their body weight charging on trunk, spine, and lower limbs. (3) Persons who need a differentiated reduction of the body weight either among anterior and posterior side or among their right and left part of the body (hemiparesis, Parkinson disease, scoliosis, kyphosis). Creating this walker is easy; producing costs are low; there are no maintenance costs.

Dandy-Walker complex and syringomyelia in an adult: case report and discussion.

PubMed

Hammond, Christopher J; Chitnavis, Bhupal; Penny, Christopher C; Strong, Anthony J

2002-01-01

Syringomyelia in association with the Dandy-Walker complex is rare and only 17 cases have been reported, mostly as autopsy findings or incidental reports in series for other conditions. We present a further case report and discuss the possible pathogenetic mechanisms of syrinx formation in the presence of the Dandy-Walker complex. We emphasize the role of foramen magnum obstruction and alteration in cerebrospinal fluid flow dynamics in syrinx formation. The therapeutic importance of disimpaction of the foramen magnum is stressed. A 39-year-old man presented with headache. As a child, he had had cystoperitoneal and ventriculoperitoneal shunts inserted for hydrocephalus in association with the Dandy-Walker complex. On examination, the patient had limited upgaze but was otherwise normal. Magnetic resonance imaging revealed a large cervicothoracic syrinx and a Dandy-Walker cyst obstructing the foramen magnum. The cystoperitoneal shunt was revised. The patient's headaches resolved, and follow-up imaging demonstrated resolution of the syrinx and disimpaction of the foramen magnum. Disimpaction of the foramen magnum can resolve syringomyelia in patients with the Dandy-Walker complex. This can be achieved by a shunt procedure or by formal foramen magnum decompression. The rarity of the association between the Dandy-Walker complex and syringomyelia prevents firm conclusions from being made regarding the best management strategy for this condition.

CommWalker: correctly evaluating modules in molecular networks in light of annotation bias.

PubMed

Luecken, M D; Page, M J T; Crosby, A J; Mason, S; Reinert, G; Deane, C M

2018-03-15

Detecting novel functional modules in molecular networks is an important step in biological research. In the absence of gold standard functional modules, functional annotations are often used to verify whether detected modules/communities have biological meaning. However, as we show, the uneven distribution of functional annotations means that such evaluation methods favor communities of well-studied proteins. We propose a novel framework for the evaluation of communities as functional modules. Our proposed framework, CommWalker, takes communities as inputs and evaluates them in their local network environment by performing short random walks. We test CommWalker's ability to overcome annotation bias using input communities from four community detection methods on two protein interaction networks. We find that modules accepted by CommWalker are similarly co-expressed as those accepted by current methods. Crucially, CommWalker performs well not only in well-annotated regions, but also in regions otherwise obscured by poor annotation. CommWalker community prioritization both faithfully captures well-validated communities and identifies functional modules that may correspond to more novel biology. The CommWalker algorithm is freely available at opig.stats.ox.ac.uk/resources or as a docker image on the Docker Hub at hub.docker.com/r/lueckenmd/commwalker/. deane@stats.ox.ac.uk. Supplementary data are available at Bioinformatics online.

Impact of Bicycle Route Type on Exposure to Traffic-Related Air Pollution

PubMed Central

MacNaughton, Piers; Melly, Steven; Vallarino, Jose; Adamkiewicz, Gary; Spengler, John D.

2017-01-01

Cyclists are exposed to traffic-related air pollution (TRAP) during their commutes due to their proximity to vehicular traffic. Two of the main components of TRAP are black carbon (BC) and nitrogen dioxide (NO2), which have both been causally associated with increased mortality. To assess the impact of cyclists’ exposure to TRAP, a battery-powered mobile monitoring station was designed to sample air pollutants along five bike routes in Boston, Massachusetts. The bike routes were categorized into three types: bike paths, which are separated from vehicle traffic; bike lanes, which are adjacent to traffic; and designated bike lanes, which are shared traffic lanes for buses and cyclists. Bike lanes were found to have significantly higher concentrations of BC and NO2 than bike paths in both adjusted and unadjusted generalized linear models. Higher concentrations were observed in designated bike lanes than bike paths; however, this association was only significant for NO2. After adjusting for traffic density, background concentration, and proximity to intersections, bike lanes were found to have concentrations of BC and NO2 that were approximately 33% higher than bike paths. Distance from the road, vegetation barriers, and reduced intersection density appear to influence these variations. These findings suggest that cyclists can reduce their exposure to TRAP during their commute by using bike paths preferentially over bike lanes regardless of the potential increase of traffic near these routes. PMID:24840278

Proactive vs. reactive car driving: EEG evidence for different driving strategies of older drivers

PubMed Central

Wascher, Edmund; Getzmann, Stephan

2018-01-01

Aging is associated with a large heterogeneity in the extent of age-related changes in sensory, motor, and cognitive functions. All these functions can influence the performance in complex tasks like car driving. The present study aims to identify potential differences in underlying cognitive processes that may explain inter-individual variability in driving performance. Younger and older participants performed a one-hour monotonous driving task in a driving simulator under varying crosswind conditions, while behavioral and electrophysiological data were recorded. Overall, younger and older drivers showed comparable driving performance (lane keeping). However, there was a large difference in driving lane variability within the older group. Dividing the older group in two subgroups with low vs. high driving lane variability revealed differences between the two groups in electrophysiological correlates of mental workload, consumption of mental resources, and activation and sustaining of attention: Older drivers with high driving lane variability showed higher frontal Alpha and Theta activity than older drivers with low driving lane variability and—with increasing crosswind—a more pronounced decrease in Beta activity. These results suggest differences in driving strategies of older and younger drivers, with the older drivers using either a rather proactive and alert driving strategy (indicated by low driving lane variability and lower Alpha and Beta activity), or a rather reactive strategy (indicated by high driving lane variability and higher Alpha activity). PMID:29352314

Crowd of individuals walking in opposite directions. A toy model to study the segregation of the group into lanes of individuals moving in the same direction

NASA Astrophysics Data System (ADS)

Goldsztein, Guillermo H.

2017-08-01

Consider a corridor, street or bridge crowded with pedestrians walking in both directions. The individuals do not walk in a completely straight line. They adjust their path to avoid colliding with incoming pedestrians. As a result of these adjustments, the whole group sometimes end up split into lanes of individuals moving in the same direction. While this formation of lanes facilitates the flow and benefits the whole group, it is believed that results from the actions of the individuals acting only on their behalf, without considering others. This phenomenon is an example of self-organization. We analyze a simple model. We assume that individuals move around a two-lane circular track. All of them at the same speed. Half of them in one direction and the rest in the opposite direction. Each time two individuals collide, one of them moves to the other lane. The individual changing lanes is selected randomly. The system self-organizes. Eventually each lane is occupied with individuals moving in only one direction. We show that the time required for the system to self-organize is bounded by a linear function on the number of individuals. This toy model provides an example where global self-organization occurs even though each member of the group acts without considering the rest.

Real-time stereo vision-based lane detection system

NASA Astrophysics Data System (ADS)

Fan, Rui; Dahnoun, Naim

2018-07-01

The detection of multiple curved lane markings on a non-flat road surface is still a challenging task for vehicular systems. To make an improvement, depth information can be used to enhance the robustness of the lane detection systems. In this paper, a proposed lane detection system is developed from our previous work where the estimation of the dense vanishing point is further improved using the disparity information. However, the outliers in the least squares fitting severely affect the accuracy when estimating the vanishing point. Therefore, in this paper we use random sample consensus to update the parameters of the road model iteratively until the percentage of the inliers exceeds our pre-set threshold. This significantly helps the system to overcome some suddenly changing conditions. Furthermore, we propose a novel lane position validation approach which computes the energy of each possible solution and selects all satisfying lane positions for visualisation. The proposed system is implemented on a heterogeneous system which consists of an Intel Core i7-4720HQ CPU and an NVIDIA GTX 970M GPU. A processing speed of 143 fps has been achieved, which is over 38 times faster than our previous work. Moreover, in order to evaluate the detection precision, we tested 2495 frames including 5361 lanes. It is shown that the overall successful detection rate is increased from 98.7% to 99.5%.

Dislocation models of interseismic deformation in the western United States

USGS Publications Warehouse

Pollitz, F.F.; McCrory, P.; Svarc, J.; Murray, J.

2008-01-01

The GPS-derived crustal velocity field of the western United States is used to construct dislocation models in a viscoelastic medium of interseismic crustal deformation. The interseismic velocity field is constrained by 1052 GPS velocity vectors spanning the ???2500-km-long plate boundary zone adjacent to the San Andreas fault and Cascadia subduction zone and extending ???1000 km into the plate interior. The GPS data set is compiled from U.S. Geological Survey campaign data, Plate Boundary Observatory data, and the Western U.S. Cordillera velocity field of Bennett et al. (1999). In the context of viscoelastic cycle models of postearthquake deformation, the interseismic velocity field is modeled with a combination of earthquake sources on ???100 known faults plus broadly distributed sources. Models that best explain the observed interseismic velocity field include the contributions of viscoelastic relaxation from faulting near the major plate margins, viscoelastic relaxation from distributed faulting in the plate interior, as well as lateral variations in depth-averaged rigidity in the elastic lithosphere. Resulting rigidity variations are consistent with reduced effective elastic plate thickness in a zone a few tens of kilometers wide surrounding the San Andreas fault (SAF) system. Primary deformation characteristics are captured along the entire SAF system, Eastern California Shear Zone, Walker Lane, the Mendocino triple junction, the Cascadia margin, and the plate interior up to ???1000 km from the major plate boundaries.

Clustering of GPS velocities in the Mojave Block, southeastern California

USGS Publications Warehouse

Savage, James C.; Simpson, Robert W.

2013-01-01

We find subdivisions within the Mojave Block using cluster analysis to identify groupings in the velocities observed at GPS stations there. The clusters are represented on a fault map by symbols located at the positions of the GPS stations, each symbol representing the cluster to which the velocity of that GPS station belongs. Fault systems that separate the clusters are readily identified on such a map. The most significant representation as judged by the gap test involves 4 clusters within the Mojave Block. The fault systems bounding the clusters from east to west are 1) the faults defining the eastern boundary of the Northeast Mojave Domain extended southward to connect to the Hector Mine rupture, 2) the Calico-Paradise fault system, 3) the Landers-Blackwater fault system, and 4) the Helendale-Lockhart fault system. This division of the Mojave Block is very similar to that proposed by Meade and Hager. However, no cluster boundary coincides with the Garlock Fault, the northern boundary of the Mojave Block. Rather, the clusters appear to continue without interruption from the Mojave Block north into the southern Walker Lane Belt, similar to the continuity across the Garlock Fault of the shear zone along the Blackwater-Little Lake fault system observed by Peltzer et al. Mapped traces of individual faults in the Mojave Block terminate within the block and do not continue across the Garlock Fault [Dokka and Travis, ].

Managed lane operations--adjusted time of day pricing vs. near-real time dynamic pricing : volume II, ramp signaling and variable speed limits (VSL).

DOT National Transportation Integrated Search

2012-02-12

In 2008, the Florida Department of Transportation began implementing the 95 Express, a segment of I-95 in Miami with high occupancy toll (HOT) lanes. Some vehicles use HOT lanes free, but most vehicles pay a toll based on real-time traffic conditions...

Comprehensive Truck Size and Weight (TS&W) Study. Phase 1-synthesis, working paper 13 : permits and pricing mechanisms and truck size and weight regulations

DOT National Transportation Integrated Search

2013-01-01

The Miami-Ft. Lauderdale region is creating a 22-mile managed-lane facility, including HOT lanes on I-95, between I-395 and I-595, with a longer term goal of providing a network of managed lanes throughout the congested region. Freeflowing conditions...

Operational and safety impacts of restriping inside lanes of urban multilane curbed roadways to 11 feet or less to create wider outside curb lanes for bicyclists :[summary].

DOT National Transportation Integrated Search

2011-01-01

Bicycling is an integral part of a sustainable transportation system. It is energy efficient, cost : effective, and environmentally friendly. Dedi-cated bike lanes provide the ideal conditions for both motorists and bicyclists. However, it is not alw...

Classification of walking ability of household walkers versus community walkers based on K-BBS, gait velocity and upright motor control.

PubMed

Joa, K L; Kwon, S Y; Choi, J W; Hong, S E; Kim, C H; Jung, H Y

2015-10-01

Few guidelines are available to assist clinicians with assessment of whether a patient is a household or community walker. To assess the Korean Berg balance scale (K-BBS) and gait velocity cut-off points of a household walker versus a community walker and evaluate which combinations of the three scales (K-BBS, upright motor control test (UMCT), and gait velocity) best assessed walking ability. Cross-sectional study. Outpatient. A total of 124 stroke patients with walking difficulty. Participants were classified into one of six walking classifications (three household walkers and three community walkers) and K-BBS, UMCT, and gait velocity were evaluated. The optimal cut-off scores for walking classification were determined based on received operator characteristic (ROC) analyses. The cut-off value of K-BBS for dividing the household walker versus the community walker was 42 points. The cut-off value of gait velocity was 48 m/s for the community walker. The area under the ROC curve of the combined K-BBS and gait velocity values was larger than that of each individual scale and those of the other combined scales. The results suggest that K-BBS, gait velocity, and UMCT are useful instruments for classifying household ambulation and community ambulation. The authors recommend K-BBS as single scale and K-BBS and gait velocity as combined scales for evaluating community ambulation in stroke patients In this report, we have some clinical implication. We recommend 3 outcome measures to assess walking ability about home or community; K-BBS (>42 points), gait speed (>48 m/min), UMCT (strong grade in either knee flexion of extension). Suggesting cut-off points of Korean Berg balance scale, gait velocity, and level of upright motor control test for community ambulation could be used as outcome measures to evaluate patient's actual performance level. It is also important to combine several scales for determining walking classification. We suggest to evaluate walking ability by combining K-BBS and UMCT to best predict community ambulation.

The effect of concurrent bandwidth feedback on learning the lane-keeping task in a driving simulator.

PubMed

de Groot, Stefan; de Winter, Joost C F; López García, José Manuel; Mulder, Max; Wieringa, Peter A

2011-02-01

The aim of this study was to investigate whether concurrent bandwidth feedback improves learning of the lane-keeping task in a driving simulator. Previous research suggests that bandwidth feedback improves learning and that off-target feedback is superior to on-target feedback. This study aimed to extend these findings for the lane-keeping task. Participants without a driver's license drove five 8-min lane-keeping sessions in a driver training simulator: three practice sessions, an immediate retention session, and a delayed retention session I day later. There were four experimental groups (n=15 per group): (a) on-target, receiving seat vibrations when the center of the car was within 0.5 m of the lane center; (b) off-target, receiving seat vibrations when the center of the car was more than 0.5 m away from the lane center; (c) control, receiving no vibrations; and (d) realistic, receiving seat vibrations depending on engine speed. During retention, all groups were provided with the realistic vibrations. During practice, on-target and off-target groups had better lane-keeping performance than the nonaugmented groups, but this difference diminished in the retention phase. Furthermore, during late practice and retention, the off-target group outperformed the on-target group.The off-target group had a higher rate of steering reversal and higher steering entropy than the nonaugmented groups, whereas no clear group differences were found regarding mean speed, mental workload, or self-reported measures. Off-target feedback is superior to on-target feedback for learning the lane-keeping task. This research provides knowledge to researchers and designers of training systems about the value of feedback in simulator-based training of vehicular control.

Drivers overtaking bicyclists-An examination using naturalistic driving data.

PubMed

Feng, Fred; Bao, Shan; Hampshire, Robert C; Delp, Michael

2018-06-01

This paper demonstrates a unique and promising approach to study driver-bicyclist interactions from a driver's perspective by using in-vehicle sensory data from naturalistic driving studies. A total of 4789 events of drivers overtaking bicyclists were extracted from an existing naturalistic driving study in Michigan, United States. The vehicle lateral placement at the time of passing bicyclists was used as a surrogate safety measure. A number of factors were examined, including the lane marking type, the presence of a bike lane or paved shoulder, the presence of traffic, lane width, and driver distraction. Some notable findings include that (1) when a bike lane or paved shoulder was present, a dashed non-center line (i.e., a dashed line separating two lanes in the same direction) was associated with significantly less vehicle lane-crossing and closer distance to the bike lane/shoulder compared to a solid centerline; (2) an alarming 7.8% of the overtaking occurred when the drivers were distracted within five seconds prior to passing bicyclists. From a bicyclist's perspective, that translates to one overtaken by a distracted driver for every thirteen times they are overtaken. In addition, drivers manipulating a cell phone were associated with significantly less vehicle lane-crossing when overtaking bicyclists. The results of this work could be potentially used by traffic engineers, policymakers and legislators to support the designs of better road infrastructures, education programs, policies, and traffic laws that aim to improve the safety of all road users. The quantitative results could also be potentially used as a baseline to develop and benchmark automated vehicle technologies on how to interact with bicyclists on the road. Copyright © 2018 Elsevier Ltd. All rights reserved.

Comparison of spatiotemporal and energy cost of the use of 3 different walkers and unassisted walking in older adults.

PubMed

Protas, Elizabeth J; Raines, Mary Lynn; Tissier, Sandrine

2007-06-01

To compare temporal, spatial, and oxygen costs of gait while elderly subjects walked without an assistive device, with a new assistive device, and with 2 other commercially available assistive devices. Descriptive, repeated measures. University-based research laboratory. Thirteen healthy older subjects who could walk without an assistive device. Not applicable. Gait speed, normalized gait speed, cadence, stride lengths, 5-minute walk distance and gait speed, oxygen consumption (Vo2) per meter walked, respiratory exchange ratio (RER) per meter walked, and minute ventilation per meter walked. Gait speed, normalized gait speed, and stride lengths decreased when the Merry Walker device was used, compared with walking without an assistive device. Outcome measures when walking with either the wheeled walker or the WalkAbout did not differ significantly from walking without a device except for a faster cadence with the WalkAbout. The distance walked and gait speed were decreased and the RER and minute ventilation were increased during the 5-minute walk with the Merry Walker compared with normal walking. The Vo2 was higher with the wheeled walker and Merry Walker than when walking without an assistive device, but there was no difference when the WalkAbout was used. Older adults walked in the new assistive device, the WalkAbout, with parameters that did not differ significantly from their gait without a device. The oxygen demands of walking were similar to unassisted walking for the WalkAbout, but were higher for the wheeled walker and Merry Walker. These results may help guide the prescription of assistive devices for older adults.

Can use of walkers or canes impede lateral compensatory stepping movements?

PubMed

Bateni, Hamid; Heung, Evelyn; Zettel, John; McLlroy, William E; Maki, Brian E

2004-08-01

Although assistive devices, such as walkers and canes are often prescribed to aid in balance control, recent studies have suggested that such devices may actually increase risk of falling. In this study, we investigated one possible mechanism: the potential for walkers or canes to interfere with, or constrain, lateral movement of the feet and thereby impede execution of compensatory stepping reactions during lateral loss of balance. Lateral stepping reactions were evoked, in 10 healthy young adults (ages 22-27 years), by means of sudden unpredictable medio-lateral support surface translation. Subjects were tested while holding and loading a standard pickup walker or single-tip cane or while using no assistive device (hands free or holding an object). Results supported the hypothesis that using a walker or cane can interfere with compensatory stepping. Collisions between the swing-foot and mobility aid were remarkably frequent when using the walker (60% of stepping reactions) and also occurred in cane trials (11% of stepping reactions). Furthermore, such collisions were associated with a significant reduction (26-37%) in lateral step length. It appeared that subjects were sometimes able to avoid collision by increasing the forward or backward displacement of the swing-foot or by moving the cane; however, attempts to lift the walker out of the way occurred rarely and were usually impeded due to collision between the contralateral walker post and stance foot. The fact that compensatory stepping behavior was altered significantly in such a healthy cohort clearly demonstrates some of the safety limitations inherent to these assistive devices, as currently designed. Copyright 2003 Elsevier B.V.

GPS/DR Error Estimation for Autonomous Vehicle Localization.

PubMed

Lee, Byung-Hyun; Song, Jong-Hwa; Im, Jun-Hyuck; Im, Sung-Hyuck; Heo, Moon-Beom; Jee, Gyu-In

2015-08-21

Autonomous vehicles require highly reliable navigation capabilities. For example, a lane-following method cannot be applied in an intersection without lanes, and since typical lane detection is performed using a straight-line model, errors can occur when the lateral distance is estimated in curved sections due to a model mismatch. Therefore, this paper proposes a localization method that uses GPS/DR error estimation based on a lane detection method with curved lane models, stop line detection, and curve matching in order to improve the performance during waypoint following procedures. The advantage of using the proposed method is that position information can be provided for autonomous driving through intersections, in sections with sharp curves, and in curved sections following a straight section. The proposed method was applied in autonomous vehicles at an experimental site to evaluate its performance, and the results indicate that the positioning achieved accuracy at the sub-meter level.

Effects of blind spot monitoring systems on police-reported lane-change crashes.

PubMed

Cicchino, Jessica B

2018-06-21

To examine the effectiveness of blind spot monitoring systems in preventing police-reported lane-change crashes. Poisson regression was used to compare crash involvement rates per insured vehicle year in police-reported lane-change crashes in 26 U.S. states during 2009-2015 between vehicles with blind spot monitoring and the same vehicle models without the optional system, controlling for other factors that can affect crash risk. Crash involvement rates in lane-change crashes were 14% lower (95% confidence limits -24% to -2%) among vehicles with blind spot monitoring than those without. Blind spot monitoring systems are effective in preventing police-reported lane-change crashes when considering crashes of all severities. If every U.S. vehicle in 2015 were equipped with blind spot monitoring that performed like the study systems, it is estimated that about 50,000 crashes could have been prevented.

Magnetic skyrmions on a two-lane racetrack

NASA Astrophysics Data System (ADS)

Müller, Jan

2017-02-01

Magnetic skyrmions are particle-like textures in magnetization, characterized by a topological winding number. Nanometer-scale skyrmions have been observed at room temperature in magnetic multilayer structures. The combination of their small size, topological quantization and their efficient electric manipulation makes them interesting candidates for information carriers in high-performance memory devices. A skyrmion racetrack memory has been suggested, in which information is encoded in the distance between skyrmions moving in a one-dimensional nanostrip. Here, I propose an alternative design where skyrmions move in two (or more) parallel lanes and the information is stored in the lane number of each skyrmion. Such a multilane track can be constructed by controlling the height profile of the nanostrip. Repulsive skyrmion-skyrmion interactions in narrow nanostrips guarantee that skyrmions on different lanes cannot pass each other. Current pulses can be used to induce a lane change, and combining these elements provides a robust, efficient design for skyrmion-based storage devices.

GPS/DR Error Estimation for Autonomous Vehicle Localization

PubMed Central

Lee, Byung-Hyun; Song, Jong-Hwa; Im, Jun-Hyuck; Im, Sung-Hyuck; Heo, Moon-Beom; Jee, Gyu-In

2015-01-01

Autonomous vehicles require highly reliable navigation capabilities. For example, a lane-following method cannot be applied in an intersection without lanes, and since typical lane detection is performed using a straight-line model, errors can occur when the lateral distance is estimated in curved sections due to a model mismatch. Therefore, this paper proposes a localization method that uses GPS/DR error estimation based on a lane detection method with curved lane models, stop line detection, and curve matching in order to improve the performance during waypoint following procedures. The advantage of using the proposed method is that position information can be provided for autonomous driving through intersections, in sections with sharp curves, and in curved sections following a straight section. The proposed method was applied in autonomous vehicles at an experimental site to evaluate its performance, and the results indicate that the positioning achieved accuracy at the sub-meter level. PMID:26307997

78 FR 40443 - Submission for OMB Review; Comment Request-Recordkeeping Requirements Under the Safety Standard...

Federal Register 2010, 2011, 2012, 2013, 2014

2013-07-05

... Request--Recordkeeping Requirements Under the Safety Standard for Infant Walkers AGENCY: Consumer Product... for infant walkers, 16 CFR part 1216. No comments were received in response to that notice. Therefore... has been incorporated by reference in the safety standard for infant walkers, 16 CFR part 1216...

75 FR 35265 - Safety Standard for Infant Walkers: Final Rule

Federal Register 2010, 2011, 2012, 2013, 2014

2010-06-21

... application, the maximum allowable displacement (i.e., movement) of the walker is 1.97 inches. The commenter... advocated increasing the maximum allowable displacement to 6 inches in accordance with ASTM F 2012. Response... playing with toys. The parking brake performance test should set limits on the displacement of the walker...

77 FR 67811 - Porter-Walker LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for...

Federal Register 2010, 2011, 2012, 2013, 2014

2012-11-14

... DEPARTMENT OF ENERGY Federal Energy Regulatory Commission [Docket No. ER13-327-000] Porter-Walker LLC; Supplemental Notice That Initial Market-Based Rate Filing Includes Request for Blanket Section 204 Authorization This is a supplemental notice in the above-referenced proceeding of Porter-Walker...

Resonant current in coupled inertial Brownian particles with delayed-feedback control

NASA Astrophysics Data System (ADS)

Gao, Tian-Fu; Zheng, Zhi-Gang; Chen, Jin-Can

2017-12-01

The transport of a walker in rocking feedback-controlled ratchets is investigated. The walker consists of two coupled "feet" that allow the interchange of the order of particles while the walker moves. In the underdamped case, the deterministic dynamics of the walker in a tilted asymmetric ratchet with an external periodic force is considered. It is found that delayed feedback ratchets with a switching-onand-off dependence of the states of the system can lead to absolute negative mobility. In such a novel phenomenon, the particles move against the bias. Moreover, the walker can acquire a series of resonant steps for different values of the current. It is interesting to find that the resonant currents of the walker are induced by the phase locked motion that corresponds to the synchronization of the motion with the change in the frequency of the external driving. These resonant steps can be well predicted in terms of time-space symmetry analysis, which is in good agreement with dynamics simulations. The transport performances can be optimized and controlled by suitably adjusting the parameters of the delayed-feedback ratchets.

Two-particle problem in comblike structures

NASA Astrophysics Data System (ADS)

Agliari, Elena; Cassi, Davide; Cattivelli, Luca; Sartori, Fabio

2016-05-01

Encounters between walkers performing a random motion on an appropriate structure can describe a wide variety of natural phenomena ranging from pharmacokinetics to foraging. On homogeneous structures the asymptotic encounter probability between two walkers is (qualitatively) independent of whether both walkers are moving or one is kept fixed. On infinite comblike structures this is no longer the case and here we deepen the mechanisms underlying the emergence of a finite probability that two random walkers will never meet, while one single random walker is certain to visit any site. In particular, we introduce an analytical approach to address this problem and even more general problems such as the case of two walkers with different diffusivity, particles walking on a finite comb and on arbitrary bundled structures, possibly in the presence of loops. Our investigations are both analytical and numerical and highlight that, in general, the outcome of a reaction involving two reactants on a comblike architecture can strongly differ according to whether both reactants are moving (no matter their relative diffusivities) or only one is moving and according to the density of shortcuts among the branches.

The chaotic interaction of two walkers

NASA Astrophysics Data System (ADS)

Tadrist, Loic; Samara, Naresh; Schlagheck, Peter; Gilet, Tristan

2016-11-01

A droplet bouncing on a vertically vibrated bath may be propelled horizontally by the Faraday waves that it generates at each rebound. This association of a wave and a particle is called a walker. Ten years ago, Yves Couder and co-workers noted that the dynamical encounter of two walkers may lead to either scattered trajectories or orbital motion. In this work, we investigate the interaction of two walkers more systematically. The walkers are launched towards each other with finely controlled initial conditions. Output trajectories are classified in four types: scattering, orbiting, wandering and complex. The interaction appears stochastic: the same set of initial parameters (to the measurement accuracy) can produce different outputs. Our analysis of the underlying chaos provides new insights on the stochastic nature of this experiment. This work is supported by the ARC Quandrops of the Wallonia-Brussels Federation.

76 FR 79755 - Notice of Final Federal Agency Actions on the Interstate 95 High Occupancy Toll Lanes Project in...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-12-22

..., Stafford, Prince William, and Fairfax Counties and City of Fredericksburg, Virginia, and those actions... interchange in Fairfax County (in the vicinity of the I-395/Edsall Road interchange) to the Prince William Parkway in Prince William County (Exit 158) and convert them to HOT Lanes. The existing two HOV lanes will...

Multiple tag labeling method for DNA sequencing

DOEpatents

Mathies, Richard A.; Huang, Xiaohua C.; Quesada, Mark A.

1995-01-01

A DNA sequencing method described which uses single lane or channel electrophoresis. Sequencing fragments are separated in said lane and detected using a laser-excited, confocal fluorescence scanner. Each set of DNA sequencing fragments is separated in the same lane and then distinguished using a binary coding scheme employing only two different fluorescent labels. Also described is a method of using radio-isotope labels.

Perception of Safety and Liking Associated to the Colour Intervention of Bike Lanes: Contribution from the Behavioural Sciences to Urban Design and Wellbeing.

PubMed

Vera-Villarroel, Pablo; Contreras, Daniela; Lillo, Sebastián; Beyle, Christian; Segovia, Ariel; Rojo, Natalia; Moreno, Sandra; Oyarzo, Francisco

2016-01-01

The perception of colour and its subjective effects are key issues to designing safe and enjoyable bike lanes. This paper addresses the relationship between the colours of bike lane interventions-in particular pavement painting and intersection design-and the subjective evaluation of liking, visual saliency, and perceived safety related to such an intervention. Utilising images of three real bike lane intersections modified by software to change their colour (five in total), this study recruited 538 participants to assess their perception of all fifteen colour-design combinations. A multivariate analysis of covariance (MANCOVA) with the Bonferroni post hoc test was performed to assess the effect of the main conditions (colour and design) on the dependent variables (liking towards the intervention, level of visual saliency of the intersection, and perceived safety of the bike lane). The results showed that the colour red was more positively associated to the outcome variables, followed by yellow and blue. Additionally, it was observed that the effect of colour widely outweighs the effect of design, suggesting that the right choice and use of colour would increase the effectiveness on bike-lanes pavement interventions. Limitations and future directions are discussed.

The influence of gate start position on physical performance and anxiety perception in expert BMX athletes.

PubMed

Di Rienzo, Franck; Martinent, Guillaume; Levêque, Lucie; MacIntyre, Tadhg; Collet, Christian; Guillot, Aymeric

2018-02-01

The critical importance of the start phase in bicycle motocross (BMX) racing is increasingly acknowledged. Past experiments underlined that the internal lane of the starting gate provides a strong positional advantage. However, how lane position affects start performance and cognitive and somatic state anxiety remains unexplored. We examined the start performance and anxiety responses of youth national-level BMX riders in both experimental and ecological contexts. We used contextualization motor imagery routines to evaluate start performance and state anxiety from the internal and external lanes. Cycle ergometer measures revealed a better start performance from the external lane, but we did not record any lane effect on actual gate start times. Both somatic and cognitive anxiety scores were higher before racing from the internal compared to the external lane. Finally, state anxiety (i.e., somatic anxiety, worry and concentration disruptions) negatively predicted the start performance. Present findings provide original insights on psychological factors involved in BMX start performance, and might contribute to fruitful coping interventions and training programmes in sports overlapping the framework of "handicap races" taking the specific form of positional advantages/disadvantages at the start (e.g., ski/snowboard cross, athletics, swimming, motorsports, etc.).

Predicting Average Vehicle Speed in Two Lane Highways Considering Weather Condition and Traffic Characteristics

NASA Astrophysics Data System (ADS)

Mirbaha, Babak; Saffarzadeh, Mahmoud; AmirHossein Beheshty, Seyed; Aniran, MirMoosa; Yazdani, Mirbahador; Shirini, Bahram

2017-10-01

Analysis of vehicle speed with different weather condition and traffic characteristics is very effective in traffic planning. Since the weather condition and traffic characteristics vary every day, the prediction of average speed can be useful in traffic management plans. In this study, traffic and weather data for a two-lane highway located in Northwest of Iran were selected for analysis. After merging traffic and weather data, the linear regression model was calibrated for speed prediction using STATA12.1 Statistical and Data Analysis software. Variables like vehicle flow, percentage of heavy vehicles, vehicle flow in opposing lane, percentage of heavy vehicles in opposing lane, rainfall (mm), snowfall and maximum daily wind speed more than 13m/s were found to be significant variables in the model. Results showed that variables of vehicle flow and heavy vehicle percent acquired the positive coefficient that shows, by increasing these variables the average vehicle speed in every weather condition will also increase. Vehicle flow in opposing lane, percentage of heavy vehicle in opposing lane, rainfall amount (mm), snowfall and maximum daily wind speed more than 13m/s acquired the negative coefficient that shows by increasing these variables, the average vehicle speed will decrease.

Dandy-Walker Malformation Presenting with Psychological Manifestations

PubMed Central

Dahanayake, Dulangi Maneksha Amerasinghe

2016-01-01

Dandy-Walker malformation, which is a congenital malformation of the cerebellum, is documented in literature to be associated with psychotic symptoms, obsessive compulsive symptoms, mood symptoms, hyperactivity, and impulsive behavior. The pathogenesis of psychiatric symptoms in Dandy-Walker malformation is thought to be due to disruption of the corticocerebellar tracts, resulting in what is known as cerebellar cognitive affective syndrome. We present a case of Dandy-Walker malformation presenting with psychiatric symptoms. This case highlights the necessity to be aware of psychiatric manifestations of cerebellar disease as it has an impact on the diagnosis and treatment. PMID:27493822

Prenatal diagnosis and molecular characterization of a novel locus for Dandy-Walker malformation on chromosome 7p21.3.

PubMed

Liao, Can; Fu, Fang; Li, Ru; Yang, Xin; Xu, Qing; Li, Dong-Zhi

2012-01-01

We present three foetuses with Dandy-Walker malformation, intra-uterine growth restriction and multiple congenital abnormalities, who were studied by array-based comparative genomic hybridization and revealed a novel locus on chromosome 7p21.3. The association of pure chromosome 7p aberrations with Dandy-Walker malformation has rarely been reported. The present study suggests that the critical region associated with Dandy-Walker malformation is restricted to 7p21.3, including the cerebellar disease associated genes NDUFA4 and PHF14. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Comparative Study of Assisted Ambulation and Perceived Exertion With the Wheeled Knee Walker and Axillary Crutches in Healthy Subjects.

PubMed

Kocher, Benjamin K; Chalupa, Robyn L; Lopez, Donna M; Kirk, Kevin L

2016-11-01

Functional limitations after lower extremity surgery often require the use of an assistive device for ambulation during rehabilitation and recovery. There are no known objective data evaluating the wheeled knee walker as an assistive device for protected ambulation. The purpose of this study was to compare assisted ambulation and perceived exertion with the wheeled knee walker and the axillary crutches in healthy participants. A prospective, randomized crossover study was performed using 24 healthy volunteers. Each participant performed a 6-minute walk test (6MWT) using each assistive device in a crossover manner. Preactivity and postactivity heart rates were recorded. The self-selected walking velocity (SSWV) was calculated and the participant's rating of perceived exertion was recorded using the OMNI Rating of Perceived Exertion (OMNI-RPE). Participant's preference for assistive device was identified. The 6MWT, SSWV, and the Omni-RPE were evaluated using paired t tests and determined to be statistically significant for the wheeled knee walker compared with axillary crutches. Evaluation of the preactivity and postactivity heart rates demonstrated a statistically significant difference for the wheeled knee walker compared with axillary crutches. The wheeled knee walker was preferred by 88% of participants. The wheeled knee walker provided increased assisted ambulation and had a lower rating of perceived exertion than axillary crutches on level surfaces in healthy participants. Level III, comparative study. © The Author(s) 2016.

Foot pressures during gait: a comparison of techniques for reducing pressure points.

PubMed

Lawless, M W; Reveal, G T; Laughlin, R T

2001-07-01

Various methods have been used to redistribute plantar surface foot pressure in patients with foot ulcers. This study was conducted to determine the effectiveness of four modalities (fracture walker, fracture walker with insert, and open and closed toe total contact casts) in reducing plantar foot pressure. Ten healthy, normal volunteer subjects had an F-scan sensor (ultra thin shoe insert pressure monitor) placed under the right foot. They then ambulated on a flat surface, maintaining their normal gait. Dynamic plantar pressures were averaged over 10 steps at four different sites (plantar surface of great toe, first metatarsal head, base of fifth metatarsal, and plantar heel). All subjects repeated this sequence under five different testing conditions (barefoot, with a fracture walker, fracture walker with arch support insert, open and closed toe total contact cast). Each subject's barefoot pressures were then compared with the pressures during the different modalities. All four treatment modalities significantly reduced (p < 0.05) plantar pressure at the first metatarsal head (no method was superior). The fracture walker, fracture walker with insert, and open toe total contact cast significantly reduced pressure at the heel. Pressures at the base of the fifth metatarsal and great toe were not significantly reduced with any treatment form. The fracture walker, with and without arch support, and total contact cast can effectively reduce plantar pressure at the heel and first metatarsal head.

Quantifying the total cost of infrastructure to enable environmentally preferable decisions: the case of urban roadway design

NASA Astrophysics Data System (ADS)

Gosse, Conrad A.; Clarens, Andres F.

2013-03-01

Efforts to reduce the environmental impacts of transportation infrastructure have generally overlooked many of the efficiencies that can be obtained by considering the relevant engineering and economic aspects as a system. Here, we present a framework for quantifying the burdens of ground transportation in urban settings that incorporates travel time, vehicle fuel and pavement maintenance costs. A Pareto set of bi-directional lane configurations for two-lane roadways yields non-dominated combinations of lane width, bicycle lanes and curb parking. Probabilistic analysis and microsimulation both show dramatic mobility reductions on road segments of insufficient width for heavy vehicles to pass bicycles without encroaching on oncoming traffic. This delay is positively correlated with uphill grades and increasing traffic volumes and inversely proportional to total pavement width. The response is nonlinear with grade and yields mixed uphill/downhill optimal lane configurations. Increasing bicycle mode share is negatively correlated with total costs and emissions for lane configurations allowing motor vehicles to safely pass bicycles, while the opposite is true for configurations that fail to facilitate passing. Spatial impacts on mobility also dictate that curb parking exhibits significant spatial opportunity costs related to the total cost Pareto curve. The proposed framework provides a means to evaluate relatively inexpensive lane reconfiguration options in response to changing modal share and priorities. These results provide quantitative evidence that efforts to reallocate limited pavement space to bicycles, like those being adopted in several US cities, could appreciably reduce costs for all users.