Erosion Control and Environment Restoration Plan Development, Matagorda County, Texas. Phase 1: Preliminary Investigation

DTIC Science & Technology

2012-07-01

Matagorda Peninsula east of MCR where a thicker cover of sand with vegetated dunes can be observed. 2.8 Typical beach profile Beach profile shape is a...clay bluffs on the beach face o Small tidal range, defined in Chapter 2, tends to focus wave action on the bluff toe o Breaking waves propel shell...toward the bluff, abrading the bluff toe o Abrasion undercuts the bluff, causing large sections to fail  Slope failure o Cyclical wave loading on

A case study on dune response to infragravity waves

NASA Astrophysics Data System (ADS)

Li, Wenshan; Wang, Hui; Li, Huan; Wu, Shuangquan; Li, Cheng

2017-08-01

A series of numerical simulations were conducted using the process-based model XBeach to investigate dune response under normal and getting rid of infragravity wave conditions with different slopes. Erosion volume upside the dune toe and dune top recession are set as indicators for dune vulnerability as well as defence capacity for its front-beach. Results show that both dune erosion volume and dune top recession decrease with gentler dune slopes. Of all the simulation cases, dune with a face slope of 1/1 lost most sand and supplied most sand for lower-bed. The presence of infragravity waves is validated to be crucial to dune vulnerability. The dune erosion volume is shown to decrease by 44.5%∼61.5% and the dune top recession decreased by 0%∼45.5% correspondingly, in the case that infragravity motion is not taken into account during simulation for different dune slopes.

Past and future drivers of increased erosion risk in the northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Wahl, T.; Plant, N. G.

2014-12-01

We use hourly observations of water levels from two tide gauges and wave data from three buoys to assess their relative contribution to past and potential future changes in the erosion risk for Dauphin Island, a barrier island located off the coastline of Alabama. Topographic information (i.e. beach slopes and dune toe and crest heights) is obtained from the most recent lidar survey conducted in the area in July 2013. Water levels and wave parameters (i.e. significant wave height and peak period) from the two tide gauges and three wave buoys are merged into single records spanning the period from 1981 to 2013. The Stockdon et al. (2006) run-up model is used to estimate the 2% exceedance values of wave run-up maxima, which are then combined with the observed water levels at the representative tide gauge site to obtain total water levels (TWLs). With this information we assess the relative contribution of geocentric sea level rise, vertical land-movement, and long-term changes in the wave parameters to the observed increase in erosion risk. The latter is approximated using the concept of impact hours per year (IHPY; Ruggiero 2013) at dune toe and dune crest elevation thresholds derived from the lidar data. Wahl et al. (2014) recently discovered a significant increase in the amplitude of the seasonal sea level cycle in the Gulf of Mexico. Here, we explore the potential of these changes, and similar developments in the seasonal cycle of the wave data and corresponding IHPY, to affect coastal erosion. Such intra-annual signals with longer-term variations have not been included in most earlier studies in favour of analysing the effects of annually averaged long-term trends. Finally, scenarios of potential future changes of all relevant parameters are used to explore their relative contribution to further increase in the coastal erosion risk over the next few decades.

Movement triggers and remediation in a fracture-dominated translational landslide at the Oregon coast

USGS Publications Warehouse

Priest, George R.; Allan, Jonathan; Niem, Alan; Niem, Wendy A.; Dickenson, Stephen E.

2009-01-01

The Johnson Creek landslide is a translational slide in seaward dipping Miocene siltstone and sandstone (Astoria Formation) and an overlying Quaternary marine terrace deposit. The slide terminates in a sea cliff and has a hummocky to nearly horizontal ground surface. The basal slide plane, however, slopes subparallel to the dip of the Miocene rocks, except beneath the back-tilted toe blocks where it curves upward. The siltstone and sandstone have low estimated permeability but cores and field mapping reveal an extensive fracture system within the slide mass. The slide mainly moves in response to groundwater pressure and coastal erosion of the toe. Limit-equilibrium stability analyses indicate that 3 m of erosion at the toe would destabilize the slide for most of the wet season, although no movement could be directly attributed to erosion in the 5 years of observation. Intense rainfall events raise pore-water pressure throughout the slide in the form of pulses of water pressure traveling from the headwall graben down the axis of the slide at rates of 1.4-2.5 m/hr in the upper part, and 3.5 m/hr to virtually instantaneous in the middle part. Infiltration of meteoric water was only ~50 mm/hr. Slope of the water table exceeds topographic slope from the head to the toe of the slide, so infiltration was too slow to directly raise head in 90 percent of the slide mass where the saturated zone is deeper than a few meters. Only at the headwall graben was the saturated zone shallow enough for rainfall events to trigger pulses of water pressure through the entire saturated zone. When a pressure pulse reached the threshold pressure for movement in the central part of the slide, the whole slide began slow, creeping movement. As head became larger and larger than the threshold for movement in more of the slide mass, movement accelerated and differential displacement between internal slide blocks became more pronounced. These findings suggest that dewatering the shallowest part of the saturated zone in this type of slide will stop these rapid pressure pulses, thereby stopping or greatly reducing seasonal movement. If slides are also subject to continual removal of material from the toe, especially where there are back-tilted toe blocks, then some type of buttress or tied-back shear pile wall may be the only effective long term remediation.

Wave Overtopping of a Barrier Beach

DTIC Science & Technology

2009-09-01

but can result in increased dune erosion along Scenic Road as occurred in 1993, 1997, and 2005 (James, 2005). Field data and observations for...factors are equal to 1. The equations for these run-up formulas are parameterized on significant wave height at the toe of the structure as measured in...3 exp C r SS RQ C D HgH γ ⎛ ⎞ = −⎜ ⎟ ⎝ ⎠ 2pξ > where the significant wave height at the toe of the structure, SH and pT are used. Again the

Martin County, FL, Case Study: Physical and Economic Performance of Martin County Federal Shore Protection Project During 2004 Tropical Season. Flood and Coastal Storm Damage Reduction Program

DTIC Science & Technology

2009-08-01

the landward toe of the dune along with the loss of upland width associated with erosion and volume of sand placed in each reach for emergency dune ...landward toe of the dune for the with-project design cross- section is approximately 49 cu yd/ft. All but one of the representative without-project profiles...2004, 9.2 million dollars in emergency protective actions including seawalls, revetments and construction of emergency dune features are estimated to

Channel Bank Cohesion and the Maintenance of Suspension Rivers

NASA Astrophysics Data System (ADS)

Dunne, K. B. J.; Jerolmack, D. J.

2017-12-01

Gravel-bedded rivers organize their channel geometry and grain size such that transport is close to the threshold of motion at bankfull. Sand-bedded rivers, however, typically maintain bankfull fluid shear (or Shields) stresses far in excess of threshold; there is no widely accepted explanation for these "suspension rivers". We propose that all alluvial rivers are at the threshold of motion for their erosion-limiting material, i.e., the structural component of the river cross-section that is most difficult to mobilize. The entrainment threshold of gravel is large enough that bank cohesion has little influence on gravel-bed rivers. Sand, however, is the most easily entrained material; silt and clay can raise the entrainment threshold of sand by orders of magnitude. We examine a global dataset of river channel geometry and show that the shear stress range for sand-bedded channels is entirely within the range of entrainment thresholds for sand-mud mixtures - suggesting that rivers that suspend their sandy bed material are still threshold rivers in terms of bank material. We then present new findings from a New Jersey coastal-plain river examining if and how river-bank toe composition controls hydraulic geometry. We consider the toe because it is the foundation of the river bank, and its erosion leads to channel widening. Along a 20-km profile of the river we measure cross-section geometry, bed slope, and bed and bank composition, and we explore multiple methods of measuring the threshold shear stress of the the river-bank toe in-situ. As the composition of the river bed transitions from gravel to sand, we see preliminary evidence of a shift from bed-threshold to bank-threshold control on hydraulic geometry. We also observe that sub-bankfull flows are insufficient to erode (cohesive) bank materials, even though transport of sand is active at nearly all flows. Our findings highlight the importance of focusing on river-bank toe material, which in the studied stream is always submerged. The toe is more compacted and more resistant to erosion than the subaerially-exposed upper bank. We find mounting evidence that sand-bedded rivers are much like gravel-bedded river; they are near-threshold channels in which the suspended load does not play a controlling role in the determination of equilibrium hydraulic geometry.

Modeling Megacusps and Dune Erosion

NASA Astrophysics Data System (ADS)

Orzech, M.; Reniers, A. J.; Thornton, E. B.

2009-12-01

Megacusps are large, concave, erosional features of beaches, of O(200m) alongshore wavelength, which sometimes occur when rip channel bathymetry is present. It is commonly hypothesized that erosion of the dune and back beach will be greater at the alongshore locations of the megacusp embayments, principally because the beach width is narrower there and larger waves can more easily reach the dune toe (e.g., Short, J. Geol., 1979, Thornton, et al., Mar. Geol., 2007). At present, available field data in southern Monterey Bay provide some support for this hypothesis, but not enough to fully confirm or refute it. This analysis utilizes XBeach, a 2DH nearshore sediment transport model, to test the above hypothesis under a range of wave conditions over several idealized rip-megacusp bathymetries backed by dunes. Model results suggest that while specific wave conditions may result in erosional hot spots at megacusp embayments, other factors such as tides, wave direction, and surf zone bathymetry can often play an equal or stronger role.

Critical Source Area Delineation: The representation of hydrology in effective erosion modeling.

NASA Astrophysics Data System (ADS)

Fowler, A.; Boll, J.; Brooks, E. S.; Boylan, R. D.

2017-12-01

Despite decades of conservation and millions of conservation dollars, nonpoint source sediment loading associated with agricultural disturbance continues to be a significant problem in many parts of the world. Local and national conservation organizations are interested in targeting critical source areas for control strategy implementation. Currently, conservation practices are selected and located based on the Revised Universal Soil Loss Equation (RUSLE) hillslope erosion modeling, and the National Resource Conservation Service will soon be transiting to the Watershed Erosion Predict Project (WEPP) model for the same purpose. We present an assessment of critical source areas targeted with RUSLE, WEPP and a regionally validated hydrology model, the Soil Moisture Routing (SMR) model, to compare the location of critical areas for sediment loading and the effectiveness of control strategies. The three models are compared for the Palouse dryland cropping region of the inland northwest, with un-calibrated analyses of the Kamiache watershed using publicly available soils, land-use and long-term simulated climate data. Critical source areas were mapped and the side-by-side comparison exposes the differences in the location and timing of runoff and erosion predictions. RUSLE results appear most sensitive to slope driving processes associated with infiltration excess. SMR captured saturation excess driven runoff events located at the toe slope position, while WEPP was able to capture both infiltration excess and saturation excess processes depending on soil type and management. A methodology is presented for down-scaling basin level screening to the hillslope management scale for local control strategies. Information on the location of runoff and erosion, driven by the runoff mechanism, is critical for effective treatment and conservation.

4-D imaging of seepage in earthen embankments with time-lapse inversion of self-potential data constrained by acoustic emissions localization

NASA Astrophysics Data System (ADS)

Rittgers, J. B.; Revil, A.; Planes, T.; Mooney, M. A.; Koelewijn, A. R.

2015-02-01

New methods are required to combine the information contained in the passive electrical and seismic signals to detect, localize and monitor hydromechanical disturbances in porous media. We propose a field experiment showing how passive seismic and electrical data can be combined together to detect a preferential flow path associated with internal erosion in a Earth dam. Continuous passive seismic and electrical (self-potential) monitoring data were recorded during a 7-d full-scale levee (earthen embankment) failure test, conducted in Booneschans, Netherlands in 2012. Spatially coherent acoustic emissions events and the development of a self-potential anomaly, associated with induced concentrated seepage and internal erosion phenomena, were identified and imaged near the downstream toe of the embankment, in an area that subsequently developed a series of concentrated water flows and sand boils, and where liquefaction of the embankment toe eventually developed. We present a new 4-D grid-search algorithm for acoustic emissions localization in both time and space, and the application of the localization results to add spatially varying constraints to time-lapse 3-D modelling of self-potential data in the terms of source current localization. Seismic signal localization results are utilized to build a set of time-invariant yet spatially varying model weights used for the inversion of the self-potential data. Results from the combination of these two passive techniques show results that are more consistent in terms of focused ground water flow with respect to visual observation on the embankment. This approach to geophysical monitoring of earthen embankments provides an improved approach for early detection and imaging of the development of embankment defects associated with concentrated seepage and internal erosion phenomena. The same approach can be used to detect various types of hydromechanical disturbances at larger scales.

Frequency of effective wave activity and the recession of coastal bluffs: Calvert Cliffs, Maryland

USGS Publications Warehouse

Wilcock, P.R.; Miller, D.S.; Shea, R.H.; Kerkin, R.T.

1998-01-01

The Calvert Cliffs, Chesapeake Bay, Maryland, USA, erode by direct wave undercutting or by freeze/thaw erosion accompanied by wave removal of slope debris. Directly undercut slopes recede more rapidly, with long-term rates exceeding 1.0 m/yr; freeze/thaw slopes recede at rates approaching 0.5 m/yr. The frequency of wave height and water level at the shoreline is estimated for eleven sites based on a 37-year wind record, estimates of storm surge, offshore wave geometry, nearshore wave transformation, and breaking wave type. Locations experiencing the largest slope recession are not uniformly those with the largest cumulative wave energy; the resistance to erosion of the slope toe must also be accounted for. An index of relative wave strength is defined as the ratio of wave pressure T and the cohesive strength S of the slope material. For the Calvert Cliffs, a minimum relative wave strength for initiating erosion of intact material is 0.05 < T/S < 0.1. A cumulative duration of ???50 hours per year for T/S ??? 0.1 distinguishes undercut and nonundercut slopes and recession rates greater or lesser than 0.5 m/yr. The relative wave strength index may be used to identify sites at risk of increased erosion. At one site with a small historical erosion rate, the loss of a protective beach and associated decrease in toe elevation caused a positive shift in the frequency of large T/S. Direct wave undercutting and increased slope recession may be anticipated at this site, as indicated by the development of an undercut notch during the course of the study.

Automated Feature Extraction of Foredune Morphology from Terrestrial Lidar Data

NASA Astrophysics Data System (ADS)

Spore, N.; Brodie, K. L.; Swann, C.

2014-12-01

Foredune morphology is often described in storm impact prediction models using the elevation of the dune crest and dune toe and compared with maximum runup elevations to categorize the storm impact and predicted responses. However, these parameters do not account for other foredune features that may make them more or less erodible, such as alongshore variations in morphology, vegetation coverage, or compaction. The goal of this work is to identify other descriptive features that can be extracted from terrestrial lidar data that may affect the rate of dune erosion under wave attack. Daily, mobile-terrestrial lidar surveys were conducted during a 6-day nor'easter (Hs = 4 m in 6 m water depth) along 20km of coastline near Duck, North Carolina which encompassed a variety of foredune forms in close proximity to each other. This abstract will focus on the tools developed for the automated extraction of the morphological features from terrestrial lidar data, while the response of the dune will be presented by Brodie and Spore as an accompanying abstract. Raw point cloud data can be dense and is often under-utilized due to time and personnel constraints required for analysis, since many algorithms are not fully automated. In our approach, the point cloud is first projected into a local coordinate system aligned with the coastline, and then bare earth points are interpolated onto a rectilinear 0.5 m grid creating a high resolution digital elevation model. The surface is analyzed by identifying features along each cross-shore transect. Surface curvature is used to identify the position of the dune toe, and then beach and berm morphology is extracted shoreward of the dune toe, and foredune morphology is extracted landward of the dune toe. Changes in, and magnitudes of, cross-shore slope, curvature, and surface roughness are used to describe the foredune face and each cross-shore transect is then classified using its pre-storm morphology for storm-response analysis.

Subungual Ewing sarcoma/PNET tumor family of the great toe: a case report

PubMed Central

Binesh, Fariba; Sobhanardekani, Mohammad; Zare, Saeedeh; Behniafard, Nasim

2016-01-01

Ewing’s sarcoma is seen mainly in patients less than 18. This aggressive tumor generally affects the axial skeleton and only rarely involves the acral regions. Ewing’s sarcoma in the foot is inordinately scarce. Clinical features are uncertain and can imitate other common diseases. This paper presents a case of 62-year-old malewith complaints of pain and swelling of the subungual area of his right great toe. The lesion was excised, and histopathological diagnosis of Ewing’s sarcoma was made. Histopathological examination, supported by immunochemical methods, remains the mainstay of diagnosis. Surgical ablation along with chemotherapy is the therapy of choice. To our knowledge, this is the first report of Ewing’s sarcoma involving the nail bed of the great toe without bone erosion. The key messages of this case report is “Subungual Ewing sarcoma is a rare case, and Ewing’s sarcoma must be kept in mind for acral lesions, especially in the adult population.” PMID:27279998

Probabilistic assessment of erosion and flooding risk in the northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Wahl, Thomas; Plant, Nathaniel G.; Long, Joseph W.

2016-05-01

We assess erosion and flooding risk in the northern Gulf of Mexico by identifying interdependencies among oceanographic drivers and probabilistically modeling the resulting potential for coastal change. Wave and water level observations are used to determine relationships between six hydrodynamic parameters that influence total water level and therefore erosion and flooding, through consideration of a wide range of univariate distribution functions and multivariate elliptical copulas. Using these relationships, we explore how different our interpretation of the present-day erosion/flooding risk could be if we had seen more or fewer extreme realizations of individual and combinations of parameters in the past by simulating 10,000 physically and statistically consistent sea-storm time series. We find that seasonal total water levels associated with the 100 year return period could be up to 3 m higher in summer and 0.6 m higher in winter relative to our best estimate based on the observational records. Impact hours of collision and overwash—where total water levels exceed the dune toe or dune crest elevations—could be on average 70% (collision) and 100% (overwash) larger than inferred from the observations. Our model accounts for non-stationarity in a straightforward, non-parametric way that can be applied (with little adjustments) to many other coastlines. The probabilistic model presented here, which accounts for observational uncertainty, can be applied to other coastlines where short record lengths limit the ability to identify the full range of possible wave and water level conditions that coastal mangers and planners must consider to develop sustainable management strategies.

Probabilistic assessment of erosion and flooding risk in the northern Gulf of Mexico

USGS Publications Warehouse

Plant, Nathaniel G.; Wahl, Thomas; Long, Joseph W.

2016-01-01

We assess erosion and flooding risk in the northern Gulf of Mexico by identifying interdependencies among oceanographic drivers and probabilistically modeling the resulting potential for coastal change. Wave and water level observations are used to determine relationships between six hydrodynamic parameters that influence total water level and therefore erosion and flooding, through consideration of a wide range of univariate distribution functions and multivariate elliptical copulas. Using these relationships, we explore how different our interpretation of the present-day erosion/flooding risk could be if we had seen more or fewer extreme realizations of individual and combinations of parameters in the past by simulating 10,000 physically and statistically consistent sea-storm time series. We find that seasonal total water levels associated with the 100 year return period could be up to 3 m higher in summer and 0.6 m higher in winter relative to our best estimate based on the observational records. Impact hours of collision and overwash—where total water levels exceed the dune toe or dune crest elevations—could be on average 70% (collision) and 100% (overwash) larger than inferred from the observations. Our model accounts for non-stationarity in a straightforward, non-parametric way that can be applied (with little adjustments) to many other coastlines. The probabilistic model presented here, which accounts for observational uncertainty, can be applied to other coastlines where short record lengths limit the ability to identify the full range of possible wave and water level conditions that coastal mangers and planners must consider to develop sustainable management strategies.

Wave induced coastal cliff top ground motions and infragravity wave dissipation under high energy wave conditions.

NASA Astrophysics Data System (ADS)

Earlie, C. S.; le Dantec, N.; Young, A.

2016-12-01

Coastal cliff erosion is a widespread problem that threatens property and infrastructure globally. The prediction of this risk calls for robust understanding of the processes and mechanisms involved in causing coastal cliff failure. Over the last decade, a number of geomorphological studies have highlighted the importance of the relationship between the offshore wave climate and cliff-toe water levels, and the resultant coastal response in terms of cliff-top ground motion and erosion. Field-based studies of instantaneous cliff response to direct wave impact have shown that wave-induced loading of the foreshore leads to cliff-top ground motions that may have the potential to weaken the integrity of the rocks and prepare them for failure. In order to understand wave-cliff interaction and how beach morphodynamics influences cliff-top ground motion and cliff erosion, two field experiments were carried out simultaneously at two locations in Northern Brittany (France). This three-month long winter field campaign (Jan-Mar 2016) included, for the first time, a comparison of cliff-top ground motion and cliff erosion at sites fronted by different beach morphologies (reflective/dissipative), along with monitoring of hydrodynamic forcing and beach topography. The magnitude of cliff-top displacements at both sites were dependent on tidal stage and free water surface elevation at the cliff toe, with the greatest contributions of cliff-top ground motions found at infragravity frequencies (0.05-0.005 Hz). Vertical displacements at infragravity and incident sea-swell (0.1-0.5 Hz) frequencies were greater at the dissipative site, apart from during spring high tide and energetic wave conditions, where displacements were two times that at the reflective site. Combining these wave-cliff interaction data with beach morphology and nearshore bathymetry will be key to understanding the spatial variability in cliff erosion under a variety of environmental settings and forcing conditions.

Measurements of erosion potential using Gust chamber in Yolo Bypass near Sacramento, California

USGS Publications Warehouse

Work, Paul A.; Schoellhamer, David H.

2018-04-27

This report describes work performed to quantify the erodibility of surface soils in the Yolo Bypass (Bypass) near Sacramento, California, for use in the California Department of Water Resources (DWR) Yolo Bypass D-MCM mercury model. The Bypass, when not serving as a floodway, is heavily utilized for agriculture. During flood events, surface water flows over the soil, resulting in the application of a shear stress to the soil. The shear stress is a function of flow speed and is often assumed to vary as the square of flow speed. Once the shear stress reaches a critical value, erosion commences, and the erosion rate typically increases with applied shear stress. The goal of the work described here was to quantify this process and how it varies throughout the major land uses found in the Yolo Bypass.Each of the major land uses found in the Bypass was targeted for sediment coring and two side-by-side cores, 10 centimeters in diameter, were extracted at each site for testing in a Gust erosion chamber. This device consists of a cylinder with a piston and cap installed to contain a sediment sample and overlying water. In most instances, coring was done with the cylinder, the piston and cap were installed, and testing commenced immediately. The cap at the top of the cylinder contains vanes to induce rotation of the flow and is driven by an electric motor, simulating the bed shear stress experienced by the soil in a flood event. Ambient water is introduced to the cylinder, passes through the device, and carries eroded sediment out of the chamber. The exiting water is tested for turbidity, and water samples obtained to relate turbidity to suspended sediment concentration are used to compute erosion rates for each of the applied shear stresses.The result for each sediment core is (1) definition of the critical shear stress required to initiate sediment erosion and (2) estimation of coefficients required to relate erosion rate to applied shear stress once this critical shear-stress threshold has been exceeded. These quantities were computed for each of the sites sampled. In total, 10 locations were sampled, representing 10 land uses ranging from wild and white rice fields to the flooded Liberty Island and the Toe Drain that receives runoff from much of the cultivated land (table 1).The Gust chamber test causes the erosion of a very small layer of sediment, typically less than a millimeter thick. The strength of the soil within this layer increases with depth, typically, and this soil strength versus depth is measured in the testing process.Results for each land use type tested are presented as the initial critical shear stress at which erosion began and the rate at which erosion increases as shear stress increases (table 2). Of the land use types sampled, irrigated pasture displayed the lowest critical shear stress, meaning that it required the smallest flow speed to initiate erosion. But in this case, the rate of increase of the subsequent erosion, given higher flow speeds, was small. The wild rice field samples exhibited a higher critical shear stress but also exhibited a much higher erosion rate once the critical shear stress was exceeded. The erosion rate for wild rice was about three times greater than that for white rice. Bear in mind that these results are based on only two cores tested per site, and variability between fields with the same crop could be significant. Approved digital data can be viewed and downloaded from ScienceBase, at https://doi.org/10.5066/F7BV7DQC. These results are being used to calculate erosion rates in the DWR Yolo Bypass D-MCM mercury model.The Toe Drain was very difficult to sample, owing to hard, consolidated sediments on the channel bed. On the first visit, two cores were obtained successfully, and testing revealed very different results. A second visit was made, but it was not possible to obtain cores suitable for testing with the coring equipment used. The available results suggest that Toe Drain soil is highly erodible (low critical shear stress and high erosion rate once initiated) despite being difficult to sample. As a collector of runoff, it also has the potential to accumulate soils eroded from adjacent areas, subsequent to storm events, as flows subside. This deposited material will typically be more erodible than the material that it lands on. The deposition and resuspension of material was not simulated in the testing described here because the applied shear stress increases monotonically during testing.The spatial distribution of mean grain size, loss on ignition, and percent fines of Yolo Bypass soils are also presented. Sediment sampling for this effort was performed by DWR; the U.S. Geological Survey (USGS) performed the sample analysis. These data should thus be considered provisional, but the remainder of the data presented here, and this report, have been through the formal U.S. Geological Survey review process.A separate effort has been made by others to develop numerical model results defining the spatially  varying, time-dependent hydrodynamics in the Yolo Bypass. These model results are being used to quantify shear stress on the soil surface, which together with the Gust chamber results shown here, are used for the DWR Yolo Bypass D-MCM mercury transport model to compute erosion rates for each time step.

Impacts of storm chronology on the morphological changes of the Formby beach and dune system, UK

NASA Astrophysics Data System (ADS)

Dissanayake, P.; Brown, J.; Karunarathna, H.

2015-07-01

Impacts of storm chronology within a storm cluster on beach/dune erosion are investigated by applying the state-of-the-art numerical model XBeach to the Sefton coast, northwest England. Six temporal storm clusters of different storm chronologies were formulated using three storms observed during the 2013/2014 winter. The storm power values of these three events nearly halve from the first to second event and from the second to third event. Cross-shore profile evolution was simulated in response to the tide, surge and wave forcing during these storms. The model was first calibrated against the available post-storm survey profiles. Cumulative impacts of beach/dune erosion during each storm cluster were simulated by using the post-storm profile of an event as the pre-storm profile for each subsequent event. For the largest event the water levels caused noticeable retreat of the dune toe due to the high water elevation. For the other events the greatest evolution occurs over the bar formations (erosion) and within the corresponding troughs (deposition) of the upper-beach profile. The sequence of events impacting the size of this ridge-runnel feature is important as it consequently changes the resilience of the system to the most extreme event that causes dune retreat. The highest erosion during each single storm event was always observed when that storm initialised the storm cluster. The most severe storm always resulted in the most erosion during each cluster, no matter when it occurred within the chronology, although the erosion volume due to this storm was reduced when it was not the primary event. The greatest cumulative cluster erosion occurred with increasing storm severity; however, the variability in cumulative cluster impact over a beach/dune cross section due to storm chronology is minimal. Initial storm impact can act to enhance or reduce the system resilience to subsequent impact, but overall the cumulative impact is controlled by the magnitude and number of the storms. This model application provides inter-survey information about morphological response to repeated storm impact. This will inform local managers of the potential beach response and dune vulnerability to variable storm configurations.

Impacts of storm chronology on the morphological changes of the Formby beach and dune system, UK

NASA Astrophysics Data System (ADS)

Dissanayake, P.; Brown, J.; Karunarathna, H.

2015-04-01

Impacts of storm chronology within a storm cluster on beach/dune erosion are investigated by applying the state-of-the-art numerical model XBeach to the Sefton coast, northwest England. Six temporal storm clusters of different storm chronologies were formulated using three storms observed during the 2013/14 winter. The storm power values of these three events nearly halve from the first to second event and from the second to third event. Cross-shore profile evolution was simulated in response to the tide, surge and wave forcing during these storms. The model was first calibrated against the available post-storm survey profiles. Cumulative impacts of beach/dune erosion during each storm cluster were simulated by using the post-storm profile of an event as the pre-storm profile for each subsequent event. For the largest event the water levels caused noticeable retreat of the dune toe due to the high water elevation. For the other events the greatest evolution occurs over the bar formations (erosion) and within the corresponding troughs (deposition) of the upper beach profile. The sequence of events impacting the size of this ridge-runnel feature is important as it consequently changes the resilience of the system to the most extreme event that causes dune retreat. The highest erosion during each single storm event was always observed when that storm initialised the storm cluster. The most severe storm always resulted in the most erosion during each cluster, no matter when it occurred within the chronology, although the erosion volume due to this storm was reduced when it was not the primary event. The greatest cumulative cluster erosion occurred with increasing storm severity; however, the variability in cumulative cluster impact over a beach/dune cross-section due to storm chronology is minimal. Initial storm impact can act to enhance or reduce the system resilience to subsequent impact, but overall the cumulative impact is controlled by the magnitude and number of the storms. This model application provides inter-survey information about morphological response to repeated storm impact. This will inform local managers of the potential beach response and dune vulnerability to variable storm configurations.

Modeling the effect of toe clipping on treefrog survival: Beyond the return rate

USGS Publications Warehouse

Waddle, J.H.; Rice, K.G.; Mazzotti, F.J.; Percival, H.F.

2008-01-01

Some studies have described a negative effect of toe clipping on return rates of marked anurans, but the return rate is limited in that it does not account for heterogeneity of capture probabilities. We used open population mark-recapture models to estimate both apparent survival (ϕ) and the recapture probability (p) of two treefrog species individually marked by clipping 2–4 toes. We used information-theoretic model selection to examine the effect of toe clipping on survival while accounting for variation in capture probability. The model selection results indicate strong support for an effect of toe clipping on survival of Green Treefrogs (Hyla cinerea) and only limited support for an effect of toe clipping on capture probability. We estimate there was a mean absolute decrease in survival of 5.02% and 11.16% for Green Treefrogs with three and four toes removed, respectively, compared to individuals with just two toes removed. Results for Squirrel Treefrogs (Hyla squirella) indicate little support for an effect of toe clipping on survival but may indicate some support for a negative effect on capture probability. We believe that the return rate alone should not be used to examine survival of marked animals because constant capture probability must be assumed, and our examples demonstrate how capture probability may vary over time and among groups. Mark-recapture models provide a method for estimating the effect of toe clipping on anuran survival in situations where unique marks are applied.

Bank erosion along the dam-regulated lower Roanoke River, North Carolina

USGS Publications Warehouse

Hupp, C.R.; Schenk, E.R.; Richter, J.M.; Peet, Robert K.; Townsend, Phil A.

2009-01-01

Dam construction and its impact on downstream fluvial processes may substantially alter ambient bank stability and erosion. Three high dams (completed between 1953 and 1963) were built along the Piedmont portion of the Roanoke River, North Carolina; just downstream the lower part of the river flows across largely unconsolidated Coastal Plain deposits. To document bank erosion rates along the lower Roanoke River, >700 bank-erosion pins were installed along 66 bank transects. Additionally, discrete measurements of channel bathymetry, turbidity, and presence or absence of mass wasting were documented along the entire study reach (153 km). A bank-erosion- floodplain-deposition sediment budget was estimated for the lower river. Bank toe erosion related to consistently high low-flow stages may play a large role in increased mid- and upper-bank erosion. Present bank-erosion rates are relatively high and are greatest along the middle reaches (mean 63 mm/yr) and on lower parts of the bank on all reaches. Erosion rates were likely higher along upstream reaches than present erosion rates, such that erosion-rate maxima have since migrated downstream. Mass wasting and turbidity also peak along the middle reaches; floodplain sedimentation systematically increases downstream in the study reach. The lower Roanoke River isnet depositional (on floodplain) with a surplus of ??2,800,000 m3yr. Results suggest that unmeasured erosion, particularly mass wasting, may partly explain this surplus and should be part of sediment budgets downstream of dams. ?? 2009 The Geological Society of America.

Slope evolution at the Calvert Cliffs, Maryland -- measuring the change from eroding bluffs to stable slopes

USGS Publications Warehouse

Herzog, Martha; Larsen, Curtis E.; McRae, Michele

2002-01-01

Despite a long history of geomorphic studies, it is difficult to ascertain the time required for slopes to change from near vertical exposures to relatively stable slopes due to inadequate age control. Actively eroding coastal bluffs along the western shore of the Chesapeake Bay provide a key for understanding the centennial-scale development of stable slopes from eroding bluff faces. The Calvert Cliffs are composed of sandy silts, silty sands, and clayey silts of Miocene-age. Active wave erosion at the bluff toes encourages rapid sloughing from bluff faces and maintains slope angles of 70-80 degrees and relatively constant bluff-retreat rates. Naturally stabilized slopes are preserved as a fossil bluff line inland from a prograding cuspate foreland at Cove Point. The foreland is migrating southward at a rate of ca. 1.5 m/yr. As it moves south, it progressively protects bluffs from wave action as new beaches are deposited at their toes. Wave erosion is reinitiated at the northern end of the complex as the landform passes. An incremental record of slope change is preserved along the fossil bluff line. 14C dating of swales between beach ridges shows the complex to span 1700 years of progressive migration history. We hypothesized that slopes would change from steep, eroding faces to low-angle slopes covered with vegetation and sought to document the rate of change. Our team measured slope angles at intervals along the fossil bluff line and dated profiles by interpolating 14C ages of adjacent beach ridges. There was no progressive decrease in slope with age. All slopes along the fossil bluff line were 30-40 degrees with a mean of 35 degrees. Constancy in slope angle suggests that steep, actively eroding bluffs were quickly changed to stable slopes by landslides and slumping once they were protected. Given the accuracy of our age control, we conclude that the time required to attain a stable slope under natural processes is less than one century. This indicates that once toe erosion is ended (naturally or through engineering) slopes are reduced to 35-degrees over a period of decades and not centuries.

Quantifying thresholds for significant dune erosion along the Sefton Coast, Northwest England

NASA Astrophysics Data System (ADS)

Esteves, Luciana S.; Brown, Jennifer M.; Williams, Jon J.; Lymbery, Graham

2012-03-01

Field and model hindcast data are used to establish a critical dune erosion threshold for the Sefton Coast (NW England). Events are classified as causing significant erosion if they result in: (a) a mean dune retreat along the entire study area of > 2 m; (b) a dune retreat of ≥ 5 m along a coastal segment ≥ 2 km in length; and (c) an eroded area ≥ 20,000 m2. For the period 1996 to 2008, individual storms were characterised using hindcast results from a POLCOMS-WAM model and measured data from the Liverpool Bay Coastal Observatory. Results show that combined extreme surge levels (> 1.5 m) and wave heights (> 4 m), or tidal water levels above 9.0 m Chart Datum (CD), do not always result in significant dune erosion. Evidence suggests that erosion is more likely to occur when wave heights are > 2.6 m, peak water level is > 10.2 m CD at Liverpool and when consecutive tidal cycles provide 10 h or more of water levels above 9.4 m CD. However, lower water levels and wave heights, and shorter events of sustained water levels, can cause significant erosion in the summer. While the return period for events giving rise to the most severe erosion in the winter is > 50 years, significant erosion in the summer can be caused by events with return periods < 1 year. It is suggested that this may be attributable to a known reduction in the mean dune toe elevation c. 30 cm. Although the study shows it might be possible to characterise objectively storm events based on oceanographic conditions, the resultant morphological change at the coast is demonstrated to depend on the time and duration of events, and on other variables which are not so easy to quantify. Further investigation is needed to understand the influence of alongshore and seasonal variability in beach/dune morphology in determining the response to the hydrodynamic and meteorological conditions causing significant erosion. Improved monitoring pre- and post-storm of changes in beach/dune morphology is required to develop reliable proxies that can be used to establish early warning systems to mitigate the impacts of erosion and flooding in the future.

Landslide susceptibility revealed by LIDAR imagery and historical records, Seattle, Washington

USGS Publications Warehouse

Schulz, W.H.

2007-01-01

Light detection and ranging (LIDAR) data were used to visually map landslides, headscarps, and denuded slopes in Seattle, Washington. Four times more landslides were mapped than by previous efforts that used aerial photographs. The mapped landforms (landslides, headscarps, and denuded slopes) were created by many individual landslides. The spatial distribution of mapped landforms and 1308 historical landslides show that historical landslide activity has been concentrated on the mapped landforms, and that most of the landslide activity that created the landforms was prehistoric. Thus, the spatial densities of historical landslides on the landforms provide approximations of the landforms' relative susceptibilities to future landsliding. Historical landslide characteristics appear to be closely related to landform type so relative susceptibilities were determined for landslides with various characteristics. No strong relations were identified between stratigraphy and landslide occurrence; however, landslide characteristics and slope morphology appear to be related to stratigraphic conditions. Human activity is responsible for causing about 80% of historical Seattle landslides. The distribution of mapped landforms and human-caused landslides suggests the probable characteristics of future human-caused landslides on each of the landforms. The distribution of mapped landforms and historical landslides suggests that erosion of slope-toes by surface water has been a necessary condition for causing Seattle landslides. Human activity has largely arrested this erosion, which implies that landslide activity will decrease with time as hillsides naturally stabilize. However, evaluation of glacial-age analogs of areas of recent slope-toe erosion suggests that landslide activity in Seattle will continue for the foreseeable future. ?? 2006 Elsevier B.V. All rights reserved.

Effect of Sweating on Insulation of Footwear.

PubMed

Kuklane, Kalev; Holmér, Ingvar

1998-01-01

The study aimed to find out the influence of sweating on footwear insulation with a thermal foot model. Simultaneously, the influence of applied weight (35 kg), sock, and steel toe cap were studied. Water to 3 sweat glands was supplied with a pump at the rate of 10 g/hr in total. Four models of boots with steel toe caps were tested. The same models were manufactured also without steel toe. Sweating reduced footwear insulation 19-25% (30-37% in toes). During static conditions, only a minimal amount of sweat evaporated from boots. Weight affected sole insulation: Reduction depended on compressibility of sole material. The influence of steel toe varied with insulation. The method of thermal foot model appears to be a practical tool for footwear evaluation.

Mechanical and Hydrologic Effects of Riparian Vegetation on Critical Conditions for Streambank Stability: Upper Truckee River, California

NASA Astrophysics Data System (ADS)

Simon, A.; Pollen, N. L.; Langendoen, E. J.

2005-05-01

The Upper Truckee River is the single largest contributor of sediment to Lake Tahoe with a large proportion of the suspended-sediment load coming from eroding streambanks. Recent advances in quantifying streambank processes highlight the combined effects of hydraulic erosion at the bank toe with geotechnical stability of the upper part of the bank and resulted in the development of a deterministic model of bank-toe erosion and streambank stability (Simon et al., 1999). The use of riparian vegetation in schemes of bank stabilization and stream restoration have become popular but are often implemented on a trial and error basis because of a lack of quantifiable information on the mechanical and hydrologic effects of vegetation on bank stability. This study, conducted along an unstable reach of the Upper Truckee River, combines field data with numerical modeling to quantify (1) hydraulic and geotechnical driving and resisting forces that control bank failures, (2) the mechanical and hydrologic effects of vegetation on shear strength, and (3) the critical conditions for bank stability with and without indigenous riparian species. Tests were conducted using three top-bank treatments: bare (control), Lemmon's willow, and young Lodgepole pine. The susceptibility of the bank toe to erosion by hydraulic forces was quantified by conducting submerged jet tests of in situ material to determine the erodibility coefficient (k) and the critical shear stress of the material. Drained, shear-strength parameters (cohesion and friction angle) of the banks were determined from borehole shear tests at various depths. Pore-water pressure and matric suction were monitored at three depths (30, 100, and 150 cm) with digital tensiometers to calculate changes in apparent cohesion for the period (September 2003 - May 2004) and to differentiate between the hydrologic effects of the two species. Root reinforcement of the two species was quantified by determining the relation between root-tensile strength and root diameter and integrating this with root distribution. Bank failures occurred during winter and spring, brought on by repeated basal melting of snow packs and rain-on-snow events. Lemmon's willow provided an order of magnitude more root-reinforcement (5.5 kPa) than the young Lodgepole pines (0.5 kPa). This difference is not related to differences in root strength, but to the far greater number of roots associated with Lemmon's willow. The hydrologic effects of the species varied spatially and temporally, were beneficial (drier) at depths of 100 and 150 cm but disadvantageous (wetter) near the surface (30 cm). In total, these effects were generally smaller in magnitude than the mechanical effects. Lemmon's willow provided a significant increase in bank strength to streambanks along the Upper Truckee River. Model runs conducted with the hydrologic and mechanical effects of Lemmon's willow included, showed no failures during the simulation period. Overall, Lemmon's willow provided a significant increase in bank strength, reducing the frequency of bank failures and delivery of fine-grained sediment to the study reach of the Upper Truckee River. The use of Lemmon's willow in a bank-stabilization scheme was found to be numerically equivalent to reducing the angle of the entire bank 10-15 degrees.

Carbon nitrogen ratio, δ13C, δ15N distribution in eroded and buried soil profiles along a small catena

NASA Astrophysics Data System (ADS)

Jakab, Gergely; Hegyi, István; Fullen, Michael; Szalai, Zoltán

2017-04-01

In addition to the serious environmental hazard soil erosion forms and reforms the soil surface. The intensity of these degrading and burial processes is highly variable, it fluctuates in time. One can only get a single view of the current status by the spatial analysis of soil depth and properties. Present study aims to estimate the dynamics of the former driving processes in detail those resulted the recent form of the landscape. Soil samples were taken along two intensively cultivated catenas from the surface to the parent material in vertical and from the ridge to the toe in horizontal direction. A non disturbed soil profile under continuous forest was also sampled as the initial, control status. Soil organic carbon (SOC), total nitrogen (TN), carbon nitrogen ratio (C/N), 13C and 15N stable isotope ratios were measured. Soil redistribution was supposed to be started right after the forest clearance 300 years before. Results indicated that the whole amount of solum (1 m) was taken by erosion in some local spots. Most of the soil loss was deposited at the toe, while vertical SOC and δ13C distributions (peaks) in the deposited profiles indicated the original soil surface at various depth. SOC peak in the profile indicated deeper in situ solum compared to the vertical peaks of the C/N and δ13C values. Presumably the layer of the highest SOC values in the sedimentation profiles is also formed by the deposition of initial soil loss from the upper parts of the catena. At this initial phase the selectivity of erosion was supposed to be quite effective for SOC that resulted the highest value. Therefore C/N and δ13C peaks fingerprint the original, in situ soil surface more adequately. The most effective erosion and deposition period was immediately after forest clearance. This emphasized that continuous tillage erosion had subordinate role compared to that of relief. Moreover, SOC erosion and burial in the present case was a sink in terms of mitigation of the atmospheric carbon content. G. Jakab was supported by the János Bolyai scholarship of the HAS, which is kindly acknowledged.

Time of emergence in regional precipitation changes: an updated assessment using the CMIP5 multi-model ensemble

NASA Astrophysics Data System (ADS)

Nguyen, Thuy-Huong; Min, Seung-Ki; Paik, Seungmok; Lee, Donghyun

2018-01-01

This study conducted an updated time of emergence (ToE) analysis of regional precipitation changes over land regions across the globe using multiple climate models from the Coupled Model Intercomparison Project phase 5 (CMIP5). ToEs were estimated for 14 selected hotspots over two seasons of April to September (AS) and October to March (OM) from three RCP scenarios representing low (RCP2.6), medium (RCP4.5), and high (RCP8.5) emissions. Results from the RCP8.5 scenario indicate that ToEs would occur before 2040 over seven hotspots including three northern high-latitude regions (OM wettening), East Africa (OM wettening), South Asia (AS wettening), East Asia (AS wettening) and South Africa (AS drying). The Mediterranean (both OM and AS drying) is expected to experience ToEs in the mid-twenty-first century (2040-2080). In order to measure possible benefits from taking low-emission scenarios, ToE differences were examined between the RCP2.6 scenario and the RCP4.5 and RCP8.5 scenarios. Significant ToE delays from 26 years to longer than 67 years were identified over East Africa (OM wettening), the Mediterranean (both AS and OM drying), South Asia (AS wettening), and South Africa (AS drying). Further, we investigated ToE differences between CMIP3-based and CMIP5-based models using the same number of models for the comparable scenario pairs (SRESA2 vs. RCP8.5, and SRESB1 vs. RCP4.5). Results were largely consistent between two model groups, indicating the robustness of ToE results. Considerable differences in ToEs (larger than 20 years) between two model groups appeared over East Asia and South Asia (AS wettening) and South Africa (AS drying), which were found due to stronger signals in CMIP5 models. Our results provide useful information on the timing of emerging signals in regional and seasonal hydrological changes, having important implications for associated adaptation and mitigation plans.

Erosion Control and Environment Restoration Plan Development, Matagorda County, Texas. Phase 2. Preliminary Design

DTIC Science & Technology

2013-08-01

recommended groin system. ......................... 37  Figure 23. H1% and Hs at the groin toe as a function of storm surge...phases of work. Keep in mind, the recommended groin system design will advance the shoreline; however, without dune and vegetation management, it...will not create a wider dry beach. Since the existing beach is presumably in equili- brium, the dune and vegetation will advance with the shoreline

Soil Mixing Coupled to Soil Production and Transport on Hillslopes: Responses to Channel Incision, Feather River, California

NASA Astrophysics Data System (ADS)

Yoo, K.; Weinman, B. A.; Mudd, S. M.; Hurst, M. D.; Gabet, E. J.; Singhvi, A. K.; Maher, K.

2012-12-01

Soil mantled hillslopes arise from the combined processes of soil production from the underlying in-situ saprolite/bedrock and the subsequent lateral transport of the colluvial soil materials toward hillslope toes. Often these toes are bounded by channels and respond to channel aggradation or incision. Biological agents such as trees and burrowing animals are often observed to be responsible for soil production and transport. Thus morphologic evolution of hillslopes is primarily derived by the combined action of channel processes setting the hillslopes' boundary condition and biophysical perturbations mixing soils. However, little is known about how the soil perturbation is coupled to the production and transport of soils. Here we quantify soil-mixing rates using optically stimulated luminescence at two hillslopes with contrasting slope gradients and erosion rates being located above and below a migrating knickpoint. The knickpoint is within a tributary basin to the Middle Fork Feather River that incised into a Sierran granitic batholith over the past five million years creating ~1km relief between the river and the surrounding plateau. Vertical soil-mixing rates range from 5-19 cm/kyr and do not vary with slope gradients and physical erosion rate. The distributions of single grain OSL ages from the two hillslopes' soils are also undistinguishable. Furthermore, LiDAR-based tree heights and densities are not statistically different between the two Hillslopes. Therefore, soil perturbation with indistinguishable intensities results in large difference in sediment flux when subject to different slope gradients. Not only do the soils in the three transects have similar mixing rates, but they also feature similar soil thicknesses. These properties, given the transects' differing erosion rates, can only be explained by varying chemical weathering processes in saprolite.

Assessment of beach and dune erosion and accretion using LiDAR: Impact of the stormy 2013-14 winter and longer term trends on the Sefton Coast, UK

NASA Astrophysics Data System (ADS)

Pye, Kenneth; Blott, Simon J.

2016-08-01

An important question for coastal management concerns the importance of individual storms and clusters of storms on longer term beach sediment budgets, beach and dune erosion, and coastal flood risk. Between October 2013 and March 2014 a series of deep Atlantic low pressure systems crossed the Northeast Atlantic, and strong winds, high waves and high water levels affected many coastal areas in the UK and other parts of western Europe. Net dune recession of up to 12.1 m occurred around Formby Point. On 5 December 2013 the highest water level ever recorded at Liverpool (6.22 m ODN) coincided with waves of Hs of 4.55 m and Tp of 9.3 s in Liverpool Bay. Wave trimming of the dune toe occurred along the entire length of the Sefton coast, but significant dune erosion occurred only where the upper beach (between the mean high water spring tide level and the dune toe) was < 25 m wide. Sediment budget calculations based on LiDAR surveys in October 2013 and May 2014 indicated a net loss of 127 × 103 m3 of sediment from the beach (above 0 m ODN) and a loss of 268 × 103 m3 from the frontal dune system, mostly at Formby Point. However, some parts of the beach to the south of Formby Point gained sediment, indicating net north to south transport over the winter. When considered in a longer term context, the 2013-14 winter represents only a small perturbation on the longer-term coast trend of erosion at Formby Point and progradation to the north and south. Analysis of LiDAR data over a longer time period 1999-2014 indicated upper beach and dune sediment loss of 780 × 103 m3 from the north-central part of Formby Point, with net gains of 806 × 103 m3 and 2116 × 103 m3 in areas to the north and south, respectively. This indicates a net onshore transport of 2142 × 103 m3 from Liverpool Bay towards the coast between Birkdale and Altcar, with a further net total of 210 × 103 m3 transported towards the shore between Altcar and Crosby. In view of the demonstrated value of airborne LiDAR surveys for the quantification of storm impacts and longer term coastal changes, it is recommended that such surveys should be undertaken before and after each winter storm period, covering the area between mean low water spring tide level and a line 200 m landward of the dune toe, of as a part of the regional coastal monitoring programme.

Erosional Consequence of Saltcedar Control

NASA Astrophysics Data System (ADS)

Vincent, Kirk R.; Friedman, Jonathan M.; Griffin, Eleanor R.

2009-08-01

Removal of nonnative riparian trees is accelerating to conserve water and improve habitat for native species. Widespread control of dominant species, however, can lead to unintended erosion. Helicopter herbicide application in 2003 along a 12-km reach of the Rio Puerco, New Mexico, eliminated the target invasive species saltcedar ( Tamarix spp.), which dominated the floodplain, as well as the native species sandbar willow ( Salix exigua Nuttall), which occurred as a fringe along the channel. Herbicide application initiated a natural experiment testing the importance of riparian vegetation for bank stability along this data-rich river. A flood three years later eroded about 680,000 m3 of sediment, increasing mean channel width of the sprayed reach by 84%. Erosion upstream and downstream from the sprayed reach during this flood was inconsequential. Sand eroded from channel banks was transported an average of 5 km downstream and deposited on the floodplain and channel bed. Although vegetation was killed across the floodplain in the sprayed reach, erosion was almost entirely confined to the channel banks. The absence of dense, flexible woody stems on the banks reduced drag on the flow, leading to high shear stress at the toe of the banks, fluvial erosion, bank undercutting, and mass failure. The potential for increased erosion must be included in consideration of phreatophyte control projects.

Erosional consequence of saltcedar control

USGS Publications Warehouse

Vincent, K.R.; Friedman, J.M.; Griffin, E.R.

2009-01-01

Removal of nonnative riparian trees is accelerating to conserve water and improve habitat for native species. Widespread control of dominant species, however, can lead to unintended erosion. Helicopter herbicide application in 2003 along a 12-km reach of the Rio Puerco, New Mexico, eliminated the target invasive species saltcedar (Tamarix spp.), which dominated the floodplain, as well as the native species sandbar willow (Salix exigua Nuttall), which occurred as a fringe along the channel. Herbicide application initiated a natural experiment testing the importance of riparian vegetation for bank stability along this data-rich river. A flood three years later eroded about 680,000 m3 of sediment, increasing mean channel width of the sprayed reach by 84%. Erosion upstream and downstream from the sprayed reach during this flood was inconsequential. Sand eroded from channel banks was transported an average of 5 km downstream and deposited on the floodplain and channel bed. Although vegetation was killed across the floodplain in the sprayed reach, erosion was almost entirely confined to the channel banks. The absence of dense, flexible woody stems on the banks reduced drag on the flow, leading to high shear stress at the toe of the banks, fluvial erosion, bank undercutting, and mass failure. The potential for increased erosion must be included in consideration of phreatophyte control projects. ?? 2009 U.S. Government.

National Dam Safety Program. Lake Caroline Dam (Inventory Number VA 03324), Mattaponi River Basin, Caroline County, Virginia. Phase I Inspection Report.

DTIC Science & Technology

1981-04-01

NAM ANDADONS I. PRGRAM ELEMENT. PROJECT, TASKCARA a WORKC UNINUER Lbnabe1 Engineering Associates, P.C. I UBR J. K. Tirmns and Associates, Inc. It...inspections can unsafe conditions be detected and only throug ontinued care and maintenance can these conditions be prevented or corrected. Phase I...downstream toe should be monitored during routine maintenance. It is also recomnended that attempts be made to halt shoreline erosion in order to prevent

Erosion Rates of Volcanic-ash Derived Soils in the Blue Mountains of Eastern Oregon, USA: A Comparison Across Sales in Space and Time.

NASA Astrophysics Data System (ADS)

Wondzell, S. M.; Clifton, C. F.; Harris, R. M.; Ritchie, J. C.

2007-12-01

We examined present day rates of erosion in the Blue Mountains of eastern Oregon to quantify background erosion rates to provide standards for assessing possible accelerated rates of erosion resulting from wild fire or from land-management activities such as prescribed fire. The Skookum Creek watersheds, where stream discharge and sediment yield have been recorded continuously since the watersheds were gauged in 1992, provided a watershed-scale estimate of erosion rates. We installed hillslope erosion plots on north- and south- facing slopes within the watersheds in 2002 and collected data for three years to estimate short-term, hillslope- scale erosion rates. We also collected soil samples and analyzed them for 137Cs to get a 40-yr time- integrated estimate of hillslope erosion rates. Our results showed large differences between whole-watershed sediment yields and hillslope erosion rates measured from plots, suggesting that episodic processes dominated sediment production and transport and therefore controlled watershed-scale sediment budgets. At the hillslope-scale, short-term erosion resulted primarily from digging by small mammals and trampling by elk. Visual observations at the plots suggested that annual down-slope sediment movement was usually less than one meter. There were no significant difference among slope positions, but erosion rates were significantly higher on south-facing aspects and positively correlated to the amount of bare ground. In contrast, the 137Cs data suggested that erosion rates differed with slope position. Higher erosion rates were measured in toe- and mid-slope positions, with little erosion occurring on upper slopes and ridge tops. We examine these results in light of the present-day pattern of surface soils resulting from redistribution of volcanic ash from upper- slope to lower-slope positions and the effects of disturbance, including wildfire and the preferential grazing of riparian and lower-slope positions by domestic livestock.

Insights into lateral marsh retreat mechanism through localized field measurements

NASA Astrophysics Data System (ADS)

Bendoni, M.; Mel, R.; Solari, L.; Lanzoni, S.; Francalanci, S.; Oumeraci, H.

2016-02-01

Deterioration of salt marshes may be due to several factors related to increased anthropic pressure, sea level rise, and erosive processes. While salt marshes can reach equilibrium in the vertical direction, adapting to sea level rise, they are inherently unstable in the horizontal direction. Marsh boundaries are characterized by scarps with bare sediment below the vegetated surface layer that can be easily removed by wave-induced erosion. In this work, we explore the different mechanisms involved in the erosion of marsh borders through the interpretation of field data. The analysis is based on a systematic field monitoring of a salt marsh in the Venice Lagoon subject to lateral erosion. Measurements included horizontal retreat of the scarp at various locations and wave height in front of the marsh during three storm surges. Continuous erosion and mass failures alternated during the observed period, leading to an average retreat up to 80 cm/yr. The data, collected roughly every month for 1.5 year, indicate that the linear relation that links the observed erosion rate to the impinging wave power exhibits a larger slope than that already estimated in literature on the basis of long-term surveys. Moreover, an increase in the gradient of erodibility is detected along the marsh scarp, due to the combined action of soil strengthening by vegetation on the marsh surface and the impact of wave breaking at the bank toe, which promote cantilever failures and increase the lateral erosion rate.

Hydraulics of embankment-dam breaching

NASA Astrophysics Data System (ADS)

Walder, J. S.; Iverson, R. M.; Logan, M.; Godt, J. W.; Solovitz, S.

2012-12-01

Constructed or natural earthen dams can pose hazards to downstream communities. Experiments to date on earthen-dam breaching have focused on dam geometries relevant to engineering practice. We have begun experiments with dam geometries more like those of natural dams. Water was impounded behind dams constructed at the downstream end of the USGS debris-flow flume. Dams were made of compacted, well-sorted, moist beach sand (D50=0.21 mm), 3.5 m from toe to toe, but varying in height from 0.5 to 1 m; the lower the dam, the smaller the reservoir volume and the broader the initially flat crest. Breaching was started by cutting a slot 30-40 mm wide and deep in the dam crest after filling the reservoir. Water level and pore pressure within the dam were monitored. Experiments were also recorded by an array of still- and video cameras above the flume and a submerged video camera pointed at the upstream dam face. Photogrammetric software was used to create DEMs from stereo pairs, and particle-image velocimetry was used to compute the surface-velocity field from the motion of tracers scattered on the water surface. As noted by others, breaching involves formation and migration of a knickpoint (or several). Once the knickpoint reaches the upstream dam face, it takes on an arcuate form whose continued migration we determined by measuring the onset of motion of colored markers on the dam face. The arcuate feature, which can be considered the head of the "breach channel", is nearly coincident with the transition from subcritical to supercritical flow; that is, it acts as a weir that hydraulically controls reservoir emptying. Photogenic slope failures farther downstream, although the morphologically dominant process at work, play no role at all in hydraulic control aside from rare instances in which they extend upstream so far as to perturb the weir, where the flow cross section is nearly self-similar through time. The domain downstream of the critical-flow section does influence the hydrograph in another way: the broader the initial dam crest, the longer the time before critical flow control is established. Flood duration is thus increased but peak discharge is decreased. Visual inspection and overhead videography reveal little turbidity in water pouring over the weir, implying that sediment there moves dominantly as bedload. Furthermore, underwater videography gives the overall impression that along the upstream dam face, erosion occurs without redeposition. Thus it would be a mistake to use empiricisms for equilibrium bedload transport to model erosion of the embankment. In mathematical terms, erosion rate cannot be backed out by calculating the divergence of transport rate; rather, transport rate should be regarded as the spatial integral of erosion rate. We use photogrammetry and motion of the colored markers to determine the erosion rate of the weir, and then infer shear stress at the weir by applying the van Rijn sediment-pickup function. Shear stress determined in this fashion is much less than what one calculates from the gradient of the energy head (an approach appropriate to steady flow). Shear stress inferred from the pickup-function calculation can serve as a constraint on computational fluid-dynamics models. Another constraint on such models, revealed by the underwater videography, is the upstream limit of sand movement, where bed shear stress equals the critical value for sand entrainment.

Pahoehoe toe dimensions, morphology, and branching relationships at Mauna Ulu, Kilauea Volcano, Hawai'i

NASA Astrophysics Data System (ADS)

Crown, David A.; Baloga, Stephen M.

Pahoehoe toe dimensions, morphology, and branching relationships were analyzed in flows emplaced during 1972 at Mauna Ulu, a satellitic shield on the east rift zone of Kilauea Volcano, Hawai'i. In order to characterize regions within flow fields dominated by networks of pahoehoe toes, measurements of toe length, width, thickness, and orientation were completed for 445 toes at 13 sites. Variations in site characteristics, including slope, substrate, and position in the flow field allow an evaluation of the effects of such parameters on toe dimensions. Toe surface morphology (ropy or smooth), local flow lobe position (interior or margin), and connective relationships between toes were documented in the form of detailed toe maps. These maps show the number of branches connecting a given toe to other toes in its local pahoehoe network and illustrate branching patterns. Statistical analyses of toe dimensions and comparisons of pahoehoe toe study sites and sub-populations combined with field observations, evaluation of toe maps, and qualitative examination of toe dimension size distributions show the following: (a) Although there are significant variations at a given site, toes typically have mean lengths (101cm) greater than mean widths (74cm) and mean widths greater than mean thicknesses (19cm) sites that have mean widths greater than mean lengths are those with lower slopes. (b) Where significant site-to-site variations in mean values of a given toe dimension were apparent, these differences could not be directly related to site characteristics. (c) Ropy toes have significantly larger mean values of length, width, and number of branches than smooth toes, and toes with three or more branches have greater lengths, widths, and thicknesses than toes with two or fewer branches, suggesting concentration of flow in these toe types. (d) The skewness of all size distributions of toe length and width to larger values suggests that toes are transitional to larger sheets and channels, consistent with field observations; and (e) Two distinct types of branching patterns (called monolayer and centrally ridged) were observed in preserved pahoehoe flow lobes. The significant variability in measured toe dimensions at Mauna Ulu suggests that toe dimensions are influenced by numerous locally defined, random factors, and that an approach based on stochastic methods can be used to model pahoehoe flow emplacement.

Effects of toe-in and toe-in with wider step width on level walking knee biomechanics in varus, valgus, and neutral knee alignments.

PubMed

Bennett, Hunter J; Shen, Guangping; Cates, Harold E; Zhang, Songning

2017-12-01

Increased peak external knee adduction moments exist for individuals with knee osteoarthritis and varus knee alignments, compared to healthy and neutrally aligned counterparts. Walking with increased toe-in or increased step width have been individually utilized to successfully reduce 1st and 2nd peak knee adduction moments, respectfully, but have not previously been combined or tested among all alignment groups. The purpose of this study was to compare toe-in only and toe-in with wider step width gait modifications in individuals with neutral, valgus, and varus alignments. Thirty-eight healthy participants with confirmed varus, neutral, or valgus frontal-plane knee alignment through anteroposterior radiographs, performed level walking in normal, toe-in, and toe-in with wider step width gaits. A 3×3 (group×intervention) mixed model repeated measures ANOVA compared alignment groups and gait interventions (p<0.05). The 1st peak knee adduction moment was reduced in both toe-in and toe-in with wider step width compared to normal gait. The 2nd peak adduction moment was increased in toe-in compared to normal and toe-in with wider step width. The adduction impulse was also reduced in toe-in and toe-in with wider step width compared to normal gait. Peak knee flexion and external rotation moments were increased in toe-in and toe-in with wider step width compared to normal gait. Although the toe-in with wider step width gait seems to be a viable option to reduce peak adduction moments for varus alignments, sagittal, and transverse knee loadings should be monitored when implementing this gait modification strategy. Copyright © 2017 Elsevier B.V. All rights reserved.

Walking, running and the evolution of short toes in humans.

PubMed

Rolian, Campbell; Lieberman, Daniel E; Hamill, Joseph; Scott, John W; Werbel, William

2009-03-01

The phalangeal portion of the forefoot is extremely short relative to body mass in humans. This derived pedal proportion is thought to have evolved in the context of committed bipedalism, but the benefits of shorter toes for walking and/or running have not been tested previously. Here, we propose a biomechanical model of toe function in bipedal locomotion that suggests that shorter pedal phalanges improve locomotor performance by decreasing digital flexor force production and mechanical work, which might ultimately reduce the metabolic cost of flexor force production during bipedal locomotion. We tested this model using kinematic, force and plantar pressure data collected from a human sample representing normal variation in toe length (N=25). The effect of toe length on peak digital flexor forces, impulses and work outputs was evaluated during barefoot walking and running using partial correlations and multiple regression analysis, controlling for the effects of body mass, whole-foot and phalangeal contact times and toe-out angle. Our results suggest that there is no significant increase in digital flexor output associated with longer toes in walking. In running, however, multiple regression analyses based on the sample suggest that increasing average relative toe length by as little as 20% doubles peak digital flexor impulses and mechanical work, probably also increasing the metabolic cost of generating these forces. The increased mechanical cost associated with long toes in running suggests that modern human forefoot proportions might have been selected for in the context of the evolution of endurance running.

[Claw size of Scottish Highland Cows after pasture and housing periods].

PubMed

Nuss, K; Kolp, E; Braun, U; Weidmann, E; Hässig, M

2014-09-01

The claws of pastured Scottish Highland Cattle are large and this may raise the question if regular claw trimming is necessary. Therefore, the claws of the right thoracic and pelvic limbs were measured in 22 Scottish Highland cows 4 times 8 weeks apart. The cows were kept on various alpine pastures before the first measurement, on a two-hectare low-land pasture before the second measurement, in a welfare-compliant straw-bedded free stall before the third measurement and on alpine pasture before the fourth measurement. Housing conditions significantly affected claw dimensions. The claws were composed of dry, hard horn during pasture periods, and had prominent weight-bearing hoof-wall borders and soles with a natural axial slope. Long dorsal walls and heels and a greater symmetry were common. Claw lesions were absent. In contrast, free-stall housing was associated with shorter toes and steeper toe angles, but white line deterioration, heel horn erosion, wearing of the axial slope and hoof wall edges were common.

Growth, Failure, and Erosion of Submarine Channel Levees on the Upper Mississippi Fan, Gulf of Mexico

NASA Astrophysics Data System (ADS)

Sawyer, D. E.; Flemings, P. B.; Nikolinakou, M. A.

2011-12-01

Late Pleistocene channel levees on the Mississippi Fan failed repeatedly along deep-seated listric faults. These growth faults begin at the top of the levee, as much as a kilometer away from the channel axis. They plunge 150-200 meters downward reaching their deepest point halfway towards the channel axis (0.5 km) along the base of a regional sand unit. They then rise toward the channel axis where they emerge. The erosion of toe-thrust material coupled with levee growth, promoted a dynamic equilibrium: turbidity currents flushed the channel axis and deposited new levee on the margins, which induced further displacement into the channel. With a geomechanical model we show that deep-seated failure occurred by undrained loading of an underlying low permeability mudstone. Excess pore pressure formed a low-strength layer that localized the detachment at the base of a regional sand. Our results show that deep-seated failure is expected when levee systems form above regional sand bodies that were deposited rapidly above low permeability mudstone. Furthermore, the presence of this failure style in channel-levee systems is a strong indicator that overpressures and low effective stresses were present during formation and thus record paleo-pressures. Understanding these systems is critical for the design of safe well penetrations, predicting hydraulic connectivity of deepwater channel sands, and the growth of submarine channel-levee systems. This study illuminates the linkages between sedimentation, erosion, and the mechanical stability of levees in submarine channel systems.

Estimating Erosion Rates using Caesium-137 Tracers in the Ethiopian Highlands

NASA Astrophysics Data System (ADS)

Guzman, C. D.; Tilahun, S. A.; Zegeye, A. D.; Yitaferu, B.; Kay, R. W.; Steenhuis, T. S.

2016-12-01

The effects and seriousness of soil erosion have been gaining more attention recently, especially with respect to shortening the life of reservoirs for hydroelectric power generation and diminished agricultural productivity. A central aim of this study on soil erosion and conservation is to compare and contrast estimates and identification of eroding areas and patterns in the Ethiopian highlands. In Debre Mawi, Ethiopia, we examined spatial variations in erosion from an agricultural watershed using the soil-adsorbed radionuclide caesium-137(Cs-137) as a sediment tracer. Sixteen sites were monitored in this small watershed 30 km south of Lake Tana, with characteristic semi-monsoonal rains, during the long (kremt) rainy season for topsoil depth change, groundwater table height, and ceasium-137 inventory. These sixteen sites are divided among cropped and fallow land and are spread out among upslope, midslope, and downslope areas within the watershed. The Cs-137 tracer method mapped the upland mildly sloping areas to be eroding at a greater average rate than any of the mid-slope or toe-slope areas. From comparisons with the sediment concentration in the downstream weir and groundwater table measurements, we draw information helpful in understanding why and how sediment concentration and erosion decreases or increases at certain times during the rainy season. By combining these different detection methods we hope to enable the development of more effective and sustainable conservation practices.

Nonlinear finite element analysis of the plantar fascia due to the windlass mechanism.

PubMed

Cheng, Hsin-Yi Kathy; Lin, Chun-Li; Chou, Shih-Wei; Wang, Hsien-Wen

2008-08-01

Tightening of plantar fascia by passively dorsiflexing the toes during walking has functional importance. The purpose of this research was to evaluate the influence of big toe dorsiflexion angles upon plantar fascia tension (the windlass effect) with a nonlinear finite element approach. A two-dimensional finite element model of the first ray was constructed for biomechanical analysis. In order to imitate the windlass effect and to evaluate the mechanical responses of the plantar fascia under various conditions, 12 model simulations--three dorsiflexion angles of the big toe (45 degrees, 30 degrees, and 15 degrees), two plantar fascia properties (linear, nonlinear), and two weightbearing conditions (with body weight, without body weight)--were designed and analyzed. Our results demonstrated that nonlinear modeling of the plantar fascia provides a more sophisticated representation of experimental data than the linear one. Nonlinear plantar fascia setting also predicted a higher stress distribution along the fiber directions especially with larger toe dorsiflexion angles (45 degrees>30 degrees>15 degrees). The plantar fascia stress was found higher near the metatarsal insertion and faded as it moved toward the calcaneal insertion. Passively dorsiflexing the big toe imposes tension onto the plantar fascia. Windlass mechanism also occurs during stance phase of walking while the toes begin to dorsiflex. From a biomechanical standpoint, the plantar fascia tension may help propel the body upon its release at the point of push off. A controlled stretch via dorsiflexing the big toe may have a positive effect on treating plantar fasciitis by providing proper guidance for collagen regeneration. The windlass mechanism is also active during the stance phase of walking when the toes begin to dorsiflex.

A simplified model for TIG-dressing numerical simulation

NASA Astrophysics Data System (ADS)

Ferro, P.; Berto, F.; James, M. N.

2017-04-01

Irrespective of the mechanical properties of the alloy to be welded, the fatigue strength of welded joints is primarily controlled by the stress concentration associated with the weld toe or weld root. In order to reduce the effects of such notch defects in welds, which are influenced by tensile properties of the alloy, post-weld improvement techniques have been developed. The two most commonly used techniques are weld toe grinding and TIG dressing, which are intended to both remove toe defects such as non-metallic intrusions and to re-profile the weld toe region to give a lower stress concentration. In the case of TIG dressing the weld toe is re-melted to provide a smoother transition between the plate and the weld crown and to beneficially modify the residual stress redistribution. Assessing the changes to weld stress state arising from TIG-dressing is most easily accomplished through a complex numerical simulation that requires coupled thermo-fluid dynamics and solid mechanics. However, this can be expensive in terms of computational cost and time needed to reach a solution. The present paper therefore proposes a simplified numerical model that overcomes such drawbacks and which simulates the remelted toe region by means of the activation and deactivation of elements in the numerical model.

How climate and weather affect the erosion risk in the northern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Wahl, T.; Plant, N. G.

2015-12-01

Oceanographic variables such as mean sea level, tides, storm surges, and waves are drivers of erosion, and they act on different time scales ranging from hours (associated with weather) to seasonal and decadal variations and trends (associated with climate). Here we explore how the related sea-state conditions affect the erosion risk in the northern Gulf of Mexico for past and future climate scenarios. From the climate perspective we find that long-term trends in the relevant variables have caused an increase of ~30% in the erosion risk since the 1980s; at least half of this increase was due to changes in the wave climate. In the next decades, sea level rise will likely become the dominating driver and may, in combination with ongoing changes in the wave climate (and depending on the emission scenario), escalate the erosion risk by up to 300% over the next 30 years. We also find significant changes in the seasonal cycles of sea level and significant wave height, which have in combination caused a considerable increase of the erosion risk in summer and decrease in winter (superimposed onto the long-term trends). The influence of weather is assessed with a copula-based multivariate sea storm model in a Monte-Carlo framework; i.e. we simulate hundreds of thousands of artificial but physically consistent sea-state conditions to quantify how different our understanding of the present day erosion risk would be if we had seen more or less extreme combinations of the different sea-state parameters over the last three decades. We find, for example, that total water levels (tide + surge + wave run-up) associated with 100-year return periods may be underestimated by up to 30% and that the average number of impact hours - when total water levels exceeded the height of the dune toe (collision) or dune crest (overwash) - could have been up to 50% higher than what we inferred based on the actually observed oceanographic conditions. Assessing erosion risk in such a probabilistic way while accounting for non-stationarity due to climate variability and change can help decision makers and planners to implement improved monitoring and adaptation strategies for long-term sustainability of the coastline and barrier islands.

Erosion risk in the northern Gulf of Mexico - the effects of climate and weather

NASA Astrophysics Data System (ADS)

Wahl, Thomas; Plant, Nathaniel G.; Long, Joseph W.

2016-04-01

Oceanographic variables such as mean sea level, tides, storm surges, and waves are drivers of erosion, and they act on different time scales ranging from hours (associated with weather) to seasonal and decadal variations and trends (associated with climate). Here we explore how the related sea-state conditions affect the erosion risk in the northern Gulf of Mexico for past and future climate scenarios. From the climate perspective we find that long-term trends in the relevant variables have caused an increase of ~30% in the erosion risk since the 1980s; at least half of this increase was due to changes in the wave climate. In the next decades, sea level rise will likely become the dominating driver and may, in combination with ongoing changes in the wave climate (and depending on the emission scenario), escalate the erosion risk by up to 300% over the next 30 years. We also find significant changes in the seasonal cycles of sea level and significant wave height, which have in combination caused a considerable increase of the erosion risk in summer and decrease in winter (superimposed onto the long-term trends). The influence of weather is assessed with a copula-based multivariate sea storm model in a Monte-Carlo framework; i.e. we simulate hundreds of thousands of artificial but physically consistent sea-state conditions to quantify how different our understanding of the present day erosion risk would be if we had seen more or less extreme combinations of the different sea-state parameters over the last three decades. We find, for example, that total water levels (tide + surge + wave run-up) associated with 100-year return periods may be underestimated by up to 30% and that the average number of impact hours - when total water levels exceeded the height of the dune toe (collision) or dune crest (overwash) - could have been up to 50% higher than what we inferred based on the actually observed oceanographic conditions. Assessing erosion risk in such a probabilistic way while accounting for non-stationarity due to climate variability and change can help decision makers and planners to implement improved monitoring and adaptation strategies for long-term sustainability of the coastline and barrier islands.

An Exploration of the Factors Influencing the Adoption of an IS Governance Framework

ERIC Educational Resources Information Center

Parker, Sharon L.

2013-01-01

This research explored IT governance framework adoption, leveraging established IS theories. It applied both the technology acceptance model (TAM) and the technology, organization, environment (TOE) models. The study consisted of developing a model utilizing TOE and TAM, deriving relevant hypotheses. Interviews with a group of practitioners…

Repair, Evaluation, Maintenance, and Rehabilitation Research Program. Stability of Toe Berm Armor Stone and Toe Buttressing Stone on Rubble-Mound Breakwaters and Jetties. Physical Model Investigation

DTIC Science & Technology

1989-09-01

Rehabilitation of Rubble-Mound Structure Toes. The first objective of this work unit was to gain an iinderstanding of the toe stability problems experi- enced ...6.75-FT WAVE FLUMES 12.0- 11.0 - Be10.0- z 0 8.0 0 n- 7.0- _U Z 0 0 6.0 --- (0cc 5.0- h 0 0 LADo cc 4.0 0 . 0 -3 -P - -2 - - 01.0-0.0- - 0_0 co 2.0

Cloud forest restoration for erosion control in a Kichwa community of the Ecuadorian central Andes Mountains

NASA Astrophysics Data System (ADS)

Backus, L.; Giordanengo, J.; Sacatoro, I.

2013-12-01

The Denver Professional Chapter of Engineers Without Borders (EWB) has begun conducting erosion control projects in the Kichwa communities of Malingua Pamba in the Andes Mountains south of Quito, Ecuador. In many high elevation areas in this region, erosion of volcanic soils on steep hillsides (i.e., < 40%) is severe and often associated with roads, water supply systems, and loss of native cloud forests followed by burning and cultivation of food crops. Following a 2011 investigation of over 75 erosion sites, the multidisciplinary Erosion Control team traveled to Malingua Pamba in October 2012 to conduct final design and project implementation at 5 sites. In partnership with the local communities, we installed woody cloud forest species, grass (sig-sig) contour hedges, erosion matting, and rock structures (toe walls, plunge pools, bank armoring, cross vanes, contour infiltration ditches, etc.) to reduce incision rates and risk of slump failures, facilitate aggradation, and hasten revegetation. In keeping with the EWB goal of project sustainability, we used primarily locally available resources. High school students of the community grew 5000 native trees and some naturalized shrubs in a nursery started by the school principal, hand weavers produced jute erosion mats, and rocks were provided by a nearby quarry. Where possible, local rock was harvested from landslide areas and other local erosion features. Based on follow up reports and photographs from the community and EWB travelers, the approach of using locally available materials installed by the community is successful; plants are growing well and erosion control structures have remained in place throughout the November to April rainy season. The community has continued planting native vegetation at several additional erosion sites. Formal monitoring will be conducted in October 2013, followed by analysis of data to determine if induced meandering and other low-maintenance erosion control techniques are working as planned. For comparison of techniques, we will consider installing check dams in comparable gullies. The October 2013 project will also focus on training the community how to conduct erosion control site assessments, design site-appropriate structures, and implement erosion control and revegetation plans. Following the training, the community will teach these skills to adjacent villages.

When will trends in European mean and heavy daily precipitation emerge?

NASA Astrophysics Data System (ADS)

Maraun, Douglas

2013-03-01

A multi-model ensemble of regional climate projections for Europe is employed to investigate how the time of emergence (TOE) for seasonal sums and maxima of daily precipitation depends on spatial scale. The TOE is redefined for emergence from internal variability only; the spread of the TOE due to imperfect climate model formulation is used as a measure of uncertainty in the TOE itself. Thereby, the TOE becomes a fundamentally limiting timescale and translates into a minimum spatial scale on which robust conclusions can be drawn about precipitation trends. Thus, minimum temporal and spatial scales for adaptation planning are also given. In northern Europe, positive winter trends in mean and heavy precipitation, and in southwestern and southeastern Europe, summer trends in mean precipitation already emerge within the next few decades. However, across wide areas, especially for heavy summer precipitation, the local trend emerges only late in the 21st century or later. For precipitation averaged to larger scales, the trend, in general, emerges earlier.

Tactile Toe Agnosia and Percept of a "Missing Toe" in Healthy Humans.

PubMed

Cicmil, Nela; Meyer, Achim P; Stein, John F

2016-03-01

A disturbance of body representation is central to many neurological and psychiatric conditions, but the mechanisms by which body representations are constructed by the brain are not fully understood. We demonstrate a directional disturbance in tactile identification of the toes in healthy humans. Nineteen young adult participants underwent tactile stimulation of the digits with the eyes closed and verbally reported the identity of the stimulated digit. In the majority of individuals, responses to the second and third toes were significantly biased toward the laterally neighboring digit. The directional bias was greater for the nondominant foot and was affected by the identity of the immediately preceding stimulated toe. Unexpectedly, 9/19 participants reported the subjective experience of a "missing toe" or "missing space" during the protocol. These findings challenge current models of somatosensory localization, as they cannot be explained simply by a lack of distinct representations for toes compared with fingers, or by overt toe-finger correspondences. We present a novel theory of equal spatial representations of digit width combined with a "preceding neighbor" effect to explain the observed phenomena. The diagnostic implications for neurological disorders that involve "digit agnosia" are discussed. © The Author(s) 2015.

Modeling of Liquid Steel/Slag/Argon Gas Multiphase Flow During Tundish Open Eye Formation in a Two-Strand Tundish

NASA Astrophysics Data System (ADS)

Chatterjee, Saikat; Li, Donghui; Chattopadhyay, Kinnor

2018-04-01

Multiphase flows are frequently encountered in metallurgical operations. One of the most effective ways to understand these processes is by flow modeling. The process of tundish open eye (TOE) formation involves three-phase interaction between liquid steel, slag, and argon gas. The two-phase interaction involving argon gas bubbles and liquid steel can be modeled relatively easily using the discrete phase modeling technique. However, the effect of an upper slag layer cannot be captured using this approach. The presence of an upper buoyant phase can have a major effect on the behavior of TOEs. Hence, a multiphase model, including three phases, viz. liquid steel, slag, and argon gas, in a two-strand slab caster tundish, was developed to study the formation and evolution of TOEs. The volume of fluid model was used to track the interphase between liquid steel and slag phases, while the discrete phase model was used to trace the movement of the argon gas bubbles in liquid steel. The variation in the TOE areas with different amounts of aspirated argon gas was examined in the presence of an overlying slag phase. The mathematical model predictions were compared against steel plant measurements.

Cryo-conditioned rocky coast systems: A case study from Wilczekodden, Svalbard.

PubMed

Strzelecki, M C; Kasprzak, M; Lim, M; Swirad, Z M; Jaskólski, M; Pawłowski, Ł; Modzel, P

2017-12-31

This paper presents the results of an investigation into the processes controlling development of a cryo-conditioned rock coast system in Hornsund, Svalbard. A suite of nested geomorphological and geophysical methods have been applied to characterise the functioning of rock cliffs and shore platforms influenced by lithological control and geomorphic processes driven by polar coast environments. Electrical resistivity tomography (ERT) surveys have been used to investigate permafrost control on rock coast dynamics and reveal the strong interaction with marine processes in High Arctic coastal settings. Schmidt hammer rock tests, demonstrated strong spatial control on the degree of rock weathering (rock strength) along High Arctic rock coasts. Elevation controlled geomorphic zones are identified and linked to distinct processes and mechanisms, transitioning from peak hardness values at the ice foot through the wave and storm dominated scour zones to the lowest values on the cliff tops, where the effects of periglacial weathering dominate. Observations of rock surface change using a traversing micro-erosion meter (TMEM) indicate that significant changes in erosion rates occur at the junction between the shore platform and the cliff toe, where rock erosion is facilitated by frequent wetting and drying and operation of nivation and sea ice processes (formation and melting of snow patches and icefoot complexes). The results are synthesised to propose a new conceptual model of High Arctic rock coast systems, with the aim of contributing towards a unifying concept of cold region landscape evolution and providing direction for future research regarding the state of polar rock coasts. Copyright © 2017 Elsevier B.V. All rights reserved.

Level II scour analysis for Bridge 42 (RANDVT00120042) on State Highway 12, crossing Third Branch White River, Randolph, Vermont

USGS Publications Warehouse

Olson, Scott A.; Weber, Matthew A.

1996-01-01

bridge consisting of four concrete spans. The maximum span length is 57 ft. (Vermont Agency of Transportation, written commun., July 29, 1994). The bridge is supported by vertical, concrete abutments and three concrete piers. The toe of the left abutment is at the channel edge. The toe of the right abutment is set back on the right over-bank. The roadway centerline on the structure has a slight horizontal curve; however, the main channel is skewed approximately 5 degrees to the bridge. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1993). Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. The scour analysis results are presented in tables 1 and 2 and a graph of the scour depths is presented in figure 8.

Increased healing in diabetic toe ulcers in a multidisciplinary foot clinic-An observational cohort study.

PubMed

Almdal, T; Nielsen, A Anker; Nielsen, K E; Jørgensen, M E; Rasmussen, A; Hangaard, S; Siersma, V; Holstein, P E

2015-12-01

To study toe ulcer healing in patients with diabetic foot ulcers attending a multidisciplinary foot clinic over a 10 years period. The study was retrospective, consecutive and observational during 2001 through 2011. The patients were treated according to the International Consensus on the Diabetic Foot. During the period the chiropodist staffing in the foot clinic was doubled; new offloading material and orthopedic foot corrections for recalcitrant ulcers were introduced. Healing was investigated in toe ulcers in Cox regression models. 2634 patients developed foot ulcers, of which 1461 developed toe ulcers; in 790 patients these were neuropathic, in 551 they were neuro-ischemic and in 120 they were critically ischemic. One-year healing rates increased in the period 2001-2011 from 75% to 91% for neuropathic toe ulcers and from 72% to 80% for neuro-ischemic toe ulcers, while no changes was observed for ischemic toe ulcers. Adjusted for changes in the patient population, the overall rate of healing for neuropathic and neuro-ischemic toe ulcers almost doubled (HR=1.95 [95% CI: 1.36-2.80]). The results show that the healing of toe ulcers improved. This outcome could not be explained by changes in the patient characteristics, but coincided with a number of improvements in organization and therapy. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Application of Finite Element Method of Numerical Modelling to Understand Toe Buckling Deformation in the Southern Alps of New Zealand.

NASA Astrophysics Data System (ADS)

Ridl, Romy; Bell, David; Villeneuve, Marlene

2017-04-01

Toe buckling deformation is a temporal product of induced stresses concentrated at the base of a slope. Prolonged induced stresses may lead to yielding of an anisotropic rock mass, either through rheological creep deformation (flexural toe buckling) or brittle failure (hinge buckling). Progressive deformation can lead to the breakout at the buckled toe and ultimately result in deep seated displacements on a mountain range scale, referred to as deep seated gravitational slope deformation (DSGSD). DSGSD can have a considerable impact on civil infrastructure and should be well understood for hazard identification, to inform civil engineering design and for resource management purposes. Toe buckling deformation was identified beneath the basal sliding zone of three large (≥50 Mm3) landslides in the Cromwell Gorge, New Zealand. This area was subjected to extensive geotechnical investigations for the Clyde Hydropower Scheme. During these investigations seventeen major landslides were identified in the Cromwell Gorge and subsequently stabilised. The data from the landslide stabilisation project, including 26.7 km of boreholes and 9 km of tunnels, for the three landslides exhibiting toe buckling was made available for this study. This comprehensive database has enabled comparison and validation of numerical simulations carried out for the Cromwell Gorge. The application of numerical modelling has demonstrated that toe buckling within the Cromwell Gorge is a result of the combination of induced stresses acting on an anisotropic schistose rock mass. The induced stresses comprise: i) topographically-induced gravitational stresses parallel to the slope, associated with the evolution of the Cromwell Gorge from a relatively low relief surface to present day topography (1400 m deep valley), and ii) active far-field tectonic stresses associated with the obliquely convergent stress regime of the Australian-Pacific continent plate boundary. Finite Element Method (FEM) numerical models were used to model the anisotropic nature of the schist rock mass, and a sequential unloading method was adopted to simulate valley evolution. Far-field tectonics were incorporated into the model by comparing topographically induced gravitational stresses with in situ field stress measurements. The results of sensitivity analyses demonstrate that the dominant parameters governing toe buckling deformation in the Cromwell Gorge are a function of the anisotropy of the schist (foliation orientation and stiffness), and the intersection of the two induced stress fields near the base of the slopes.

Modeling and analysis of passive dynamic bipedal walking with segmented feet and compliant joints

NASA Astrophysics Data System (ADS)

Huang, Yan; Wang, Qi-Ning; Gao, Yue; Xie, Guang-Ming

2012-10-01

Passive dynamic walking has been developed as a possible explanation for the efficiency of the human gait. This paper presents a passive dynamic walking model with segmented feet, which makes the bipedal walking gait more close to natural human-like gait. The proposed model extends the simplest walking model with the addition of flat feet and torsional spring based compliance on ankle joints and toe joints, to achieve stable walking on a slope driven by gravity. The push-off phase includes foot rotations around the toe joint and around the toe tip, which shows a great resemblance to human normal walking. This paper investigates the effects of the segmented foot structure on bipedal walking in simulations. The model achieves satisfactory walking results on even or uneven slopes.

When at what scale will trends in European mean and heavy precipitation emerge

NASA Astrophysics Data System (ADS)

Maraun, Douglas

2013-04-01

A multi-model ensemble of regional climate projections for Europe is employed to investigate how the time of emergence (TOE) for seasonal sums and maxima of daily precipitation depends on spatial scale. The TOE is redefined for emergence from internal variability only, the spread of the TOE due to imperfect climate model formulation is used as a measure of uncertainty in the TOE itself. Thereby the TOE becomes a fundamentally limiting time scale and translates into a minimum spatial scale on which robust conclusions can be drawn about precipitation trends. Thus also minimum temporal and spatial scales for adaptation planning are given. In northern Europe, positive winter trends in mean and heavy precipitation, in southwestern and southeastern Europe summer trends in mean precipitation emerge already within the next decades. Yet across wide areas, especially for heavy summer precipitation, the local trend emerges only late in the 21st century or later. For precipitation averaged to larger scales, the trend in general emerges earlier. Douglas Maraun, When at what scale will trends in European mean and heavy precipitation emerge? Env. Res. Lett., in press, 2013.

Towards Robot-Assisted Echocardiographic Monitoring in Catheterization Laboratories : Usability-Centered Manipulator for Transesophageal Echocardiography.

PubMed

Pahl, Christina; Ebelt, Henning; Sayahkarajy, Mostafa; Supriyanto, Eko; Soesanto, Amiliana

2017-08-15

This paper proposes a robotic Transesophageal Echocardiography (TOE) system concept for Catheterization Laboratories. Cardiovascular disease causes one third of all global mortality. TOE is utilized to assess cardiovascular structures and monitor cardiac function during diagnostic procedures and catheter-based structural interventions. However, the operation of TOE underlies various conditions that may cause a negative impact on performance, the health of the cardiac sonographer and patient safety. These factors have been conflated and evince the potential of robot-assisted TOE. Hence, a careful integration of clinical experience and Systems Engineering methods was used to develop a concept and physical model for TOE manipulation. The motion of different actuators of the fabricated motorized system has been tested. It is concluded that the developed medical system, counteracting conflated disadvantages, represents a progressive approach for cardiac healthcare.

Deciphering the Preparatory and Triggering Factors Responsible for Post-Glacial Slope Failures: Insights from Landslide Age and Morphology in Yellowstone National Park

NASA Astrophysics Data System (ADS)

Nicholas, G.; Dixon, J. L.; Pierce, K. L.

2017-12-01

Landslides are ubiquitous to post-glacial landscapes worldwide. Withdrawal of glacier ice exposes oversteepened landscapes that may be unstable, and consequently susceptible to landsliding. Several disparate mechanisms can act as triggers: glacial debuttressing can directly destabilize slopes; however, changes in climate resulting in greater effective moisture and subsequent degradation of permafrost may also play a role. Here, we quantify relative age, spatial relationships, and topographic metrics in a set of post-glacial landslides in northwest Yellowstone National Park. Preliminary analysis of high-resolution topography indicates increasing surface roughness of non-active landslides southward, consistent with younging ages along the retreat path of the Yellowstone Ice Cap. These roughness values in ancient slides are roughly half those of the active Slide Lake Landslide within the same study region. However, the changes in roughness within the non-active landslides disappear when we remove biases such as gullying, fluvial erosional contacts, and areas believed to have been remobilized. These removed areas appear largely linked to a Holocene incision pulse up the Gardiner River, which interacts with the toes of landslides in the southern region. Stream power analysis indicates that incision is focused at a knickpoint locally coincident with the toe of the modern and active Slide Lake Landslide. Our results indicate caution should be used when using surface roughness for landslide ages without accounting for both intrinsic and extrinsic changes in erosion of the landslide system, and suggest tight links between modern stream erosion and landslide reactivation. Insights from this dynamic landscape in Yellowstone National Park are actively being used by park officials to mitigate risk, and broadly show that quantifying the temporal and spatial patterns of landslides can provide diagnostic understanding of the long-term controls on post-glacial slope failure.

Gypsum scarps and asymmetric fluvial valleys in evaporitic terrains. The role of river migration, landslides, karstification and lithology (Ebro River, NE Spain)

NASA Astrophysics Data System (ADS)

Guerrero, J.; Gutiérrez, F.

2017-11-01

Most of the Spanish fluvial systems excavated in Tertiary evaporitic gypsum formations show asymmetric valleys characterized by a stepped sequence of fluvial terraces on one valley flank and kilometric-long and > 100-m high prominent river scarp on the opposite side of the valley. Scarp undermining by the continuous preferential lateral migration of the river channel toward the valley margin leads to vertical to overhanging unstable slopes affected by a large number of slope failures that become the main geological hazard for villages located at the toe of the scarps. Detailed mapping of the gypsum scarps along the Ebro and Huerva Rivers gypsum scarps demonstrates that landslides and lateral spreading processes are predominant when claystones crop out at the base of the scarp, while rockfalls and topples become the dominant movement in those reaches where the rock mass is mainly constituted by evaporites. The dissolution of gypsum nodules, seasonal swelling and shrinking, and dispersion processes contribute to a decrease in the mechanical strength of claystones. The existence of dissolution-enlarged joints, sinkholes, and severely damaged buildings at the toe of the scarp from karstic subsidence demonstrates that the interstratal karstification of evaporites becomes a triggering factor in the instability of the rock mass. The genesis of asymmetric valleys and river gypsum scarps in the study area seem to be caused by the random migration of the river channel in the absence of lateral tilting related to tectonics or dissolution-induced subsidence. Once the scarp is developed, its preservation depends on the physicochemical properties of the substratum, the ratio between bedrock erosion and river incision rates, and climatic conditions that favour runoff erosion versus dissolution.

3D Printing Technology in Planning Thumb Reconstructions with Second Toe Transplant.

PubMed

Zang, Cheng-Wu; Zhang, Jian-Lei; Meng, Ze-Zu; Liu, Lin-Feng; Zhang, Wen-Zhi; Chen, Yong-Xiang; Cong, Rui

2017-05-01

To report preoperative planning using 3D printing to plan thumb reconstructions with second toe transplant. Between December 2013 and October 2015, the thumbs of five patients with grade 3 thumb defects were reconstructed using a wrap-around flap and second toe transplant aided by 3D printing technology. CT scans of hands and feet were analyzed using Boholo surgical simulator software (www.boholo.com). This allowed for the creation of a mirror image of the healthy thumb using the uninjured thumb. Using 3D images of the reconstructed thumb, a model of the big toe and the second toe was created to understand the dimensions of the donor site. This model was also used to repair the donor site defect by designing appropriate iliac bone and superficial circumflex iliac artery flaps. The polylactic acid model of the donor toes and reconstructed thumb was produced using 3D printing. Surgically, the wrap-around flap of the first dorsal metatarsal artery and vein combined with the joint and bone of the second toe was based upon the model donor site. Sensation was reconstructed by anastomosing the dorsal nerve of the foot and the plantar digital nerve of the great toe. Patients commenced exercises 2 weeks after surgery. All reconstructed thumbs survived, although partial flap necrosis occurred in one case. This was managed with regular dressing changes. Patients were followed up for 3-15 months. The lengths of the reconstructed thumbs are 34-49 mm. The widths of the thumb nail beds are 16-19 mm, and the thickness of the digital pulp is 16-20 mm. The thumb opposition function was 0-1.5 cm; the extension angle was 5°-20° (mean, 16°), and the angle of flexion was 38°-55° (mean, 47°). Two-point discrimination was 9-11 mm (mean, 9.6 mm). The reconstructed thumbs had good appearance, function and sensation. Based on the criteria set forth by the Standard on Approval of Reconstructed Thumb and Finger Functional Assessment of the Chinese Medical Association, the results were considered excellent for four cases and good for one case. The success rate was 100%. When planning a wrap-around flap and second toe transplant to reconstruct a thumb, both the donor and recipient sites can be modeled using 3D printing. This can shorten the operative time by supplying digital and accurate schematics for the operation. It can also optimize the function and appearance of the reconstructed thumb while minimizing damage to the donor site. © 2017 Chinese Orthopaedic Association and John Wiley & Sons Australia, Ltd.

Monitoring channel morphology and bluff erosion at two installations of flow-deflecting vanes, North Fish Creek, Wisconsin, 2000-03

USGS Publications Warehouse

Fitzpatrick, Faith A.; Peppler, Marie C.; Schwar, Heather E.; Hoopes, John A.; Diebel, Matthew W.

2005-01-01

Flow-deflecting vanes were installed in the streambed along two meander bends with eroding bluffs in 2000 and 2001 in the upper main stem of North Fish Creek, a tributary to Lake Superior in Wisconsin. About 45 vanes were arranged in 15 arrays at each site to deflect the flow away from the eroding toe or base of the bluff (outside of a bend) and toward the point bar (inside of a bend). Channel cross-section and bluff-erosion surveys were done and streamflow and stage were measured before, during, and after vane installation to monitor changes in channel morphology and bluff erosion in the context of hydrologic conditions. There were two large floods in the study area in spring 2001 (recurrence interval of approximately 100 years) and in spring 2002 (recurrence intervals of approximately 50 years). Some maintenance and replacement of vanes were needed after the floods. Most of the channel-morphology changes resulted from the large floods, and fewer changes resulted from near-bankfull or at-bankfull flows (one in October 2002 and four in April and May 2003). At the bluff located 16.4 river miles upstream of the creek mouth (site 16.4), the vanes deflected flow and caused the channel to migrate away from the base of the bluff and toward the point bar, allowing sediment to deposit along the bluff base. The 361-foot reach at site 16.4 had a net gain of 6,740 cubic feet of sediment over the entire monitoring period (2000?03). Deposition (10,660 cubic feet) occurred mainly along the base of the bluff in the downstream part of the bend. Erosion occurred at site 16.4 along the streambed, the point bar side of the channel, and along a midchannel bar (1,220, 1,610, and 1,090 cubic feet, respectively). Less channel migration was observed during 2001-03 at another bluff located 12.2 river miles upstream of the creek mouth (site 12.2), which had a net loss of sediment through the 439-foot reach of 2,800 cubic feet over the monitored time period. The main volume of sediment was lost from the bluff toe in the downstream part of the bend (7,100 cubic feet). Monitored channel-morphology changes at site 12.2 were less than at site 16.4, most likely because installation was done after the April 2001 flood, which caused major changes in channel morphology at site 16.4, and because the monitoring period was shorter than at site 16.4. Bluff-erosion data from both sites indicate that mass wasting and block failures from the bluff top occur episodically and will continue to occur for decades or more.

Barrier island response to an elevated sea-level anomaly: Onslow Beach, North Carolina, USA

NASA Astrophysics Data System (ADS)

Theuerkauf, E. J.; Rodriguez, A. B.; Fegley, S. R.; Luettich, R.

2012-12-01

Variations in sea level over time scales ranging from hours to millennia influence coastal processes and evolution. At annual time scales, elevated sea-level anomalies produce coastal flooding and promote beach erosion. This study examines the coastal response of Onslow Beach, North Carolina to the summer 2009 East Coast sea-level anomaly. Onslow Beach is a 12-km-long wave-dominated barrier island with highly variable along-barrier morphology. The transgressive southern portion of the island is characterized by a narrow beach, low dunes, and multiple washover fans, while the regressive northern portion is characterized by a wide beach and continuous tall dunes. Hourly tide gauge data from adjacent NOAA stations (Beaufort and Wrightsville Beach) are used to determine the timing and extent of elevated water levels. The seasonal and longer term trends (relative sea level rise) are removed from both of the water level series and the sea-level anomaly is represented by a large residual between the observed and predicted water levels. Beach response is quantified using terrestrial laser scanning for morphology and from geoprobe cores to determine the maximum depth of erosion (MDOE). The mean high water (MHW) shoreline and dune toe are digitized from digital elevation models derived from the laser scans and analyzed using the Digital Shoreline Analysis System (DSAS). Landward (negative) movement of these contacts indicates erosion. Wave data collected from an Acoustic Wave and Current Meter (AWAC) located offshore of the southern end of Onslow Beach is used to characterize the wave regime throughout the study. Water level is elevated in the tide gauge data from June 2009 to March 2010. This sea-level anomaly corresponds with an increase in the maximum depth of erosion between 2009 and 2010. Landward movement of the MHW shoreline and the dunetoe increased during the period between September 2009 and May 2010 indicating an increase in beach erosion during the sea-level anomaly. No significant increase in wave height was observed during this period, suggesting that the increase in beach erosion resulted from the sea-level anomaly. The sites that were strongly impacted by the sea-level anomaly did not fully recover from the beach erosion and consequently experienced large amounts of erosion in response to Hurricane Irene in 2011. These results suggest that long duration (weeks to months) high water levels cause changes to the beach similar to those generally thought to occur only during large storms. Dune erosion from higher sea levels weakens a beaches defense to storms, leading to increased beach erosion and overwash if a storm occurs before the beach can recover. It is likely that similar high water events will increase in duration and magnitude with future climate change, leading to increased "fair-weather" beach erosion and priming the system for devastating hurricane impacts.

A topical aqueous oxygen emulsion stimulates granulation tissue formation in a porcine second-degree burn wound.

PubMed

Li, Jie; Zhang, Yan-Ping; Zarei, Mina; Zhu, Linjian; Sierra, Jose Ollague; Mertz, Patricia M; Davis, Stephen C

2015-08-01

Oxygen is an essential substance for wound healing. Limited studies have shown that topical oxygen can influence healing. This study evaluated the effects of a Topical Oxygen Emulsion (TOE) on burn wound healing. A porcine second-degree burn wound model was used in the study. Burn wounds were randomly assigned to TOE, vehicle control, and no-treatment (air) groups. Effects of TOE on the granulation tissue formation and angiogenesis were studied using hematoxylin and eosin histological analysis. Protein production and gene expression of types I and III collagen and vascular endothelial growth factor (VEGF) were determined using immunofluorescent staining and Reverse Transcription and Polymerase Chain Reaction (RT-PCR), respectively. The TOE treated wounds exhibited better angiogenesis and granulation tissue formation by histology examination. The immunofluorescence staining and RT-PCR analysis demonstrated that protein production and mRNA expression of VEGF and collagen III were significantly higher in TOE treatment group than vehicle alone and air control groups, while there was no significant difference in the level of collagen I. Our data demonstrate that TOE enhances burn wound healing via stimulating the expression of VEGF and type III collagen and strongly indicates the potential use of TOE in wounds. Copyright © 2014 Elsevier Ltd and ISBI. All rights reserved.

Terrestrial laser scanning of anthropogenic beach berms for urban flood defense

NASA Astrophysics Data System (ADS)

Sanders, B. F.; Schubert, J.; Gallien, T.; Shakeri Majd, M.

2013-12-01

Globally, over 20 million people reside below present high tide levels and as many as 200 million are vulnerable to flooding during extreme events. In California, coastal flooding is driven by a combination of factors such as high astronomical tides, waves, storm surge, and other fluctuations such as those caused by the El Nino Southern Oscillation (ENSO), and climate change is likely to exacerbate those factors testing the limits of coastal flood defenses. Beaches provide natural flood protection during storms by mitigating the effects of high water levels and wave runup, and a process known as beach berming can be used to temporarily enhance the ability of beaches to withstand overtopping. In cases where beaches serve as primary protection for development, anthropogenic berms may represent an attractive management option for temporarily addressing future flood hazards. Terrestrial laser scanning (TLS) or lidar has emerged as a valuable technology for capturing the three dimensional geometry of complex surfaces and objects, and in the context of coastal flood prediction mobile TLS could prove invaluable by quickly mapping beach topography before an imminent flood threat and reducing associated uncertainties in coastal flood forecasting systems. The research presented here highlights the results of a field campaign to document the initial conditions and dynamic erosion of anthropogenic berms using TLS. On three occasions in February and March of 2012, a prototype berm was constructed on the foreshore of the city of Newport Beach, CA at low tide, and was scanned to document its initial shape, and then scanned in near-continuous fashion with the rising tide to characterize its subsequent erosion. The purpose is two-fold: (1) to measure the performance of the TLS system relative to accuracy and assess strengths and drawbacks that are likely to bear on the suitability of this technology to support flood prediction as described above, and (2) to develop a better understanding of how typical southern California berms respond to hydrodynamic stresses (rising tides and waves). Near continuous scanning leads to a 4D model (3 spatial coordinates plus time) of the berm that documents its gradual erosion, including a characterization of how the berm crest and volume change over time, which offers primary data on how anthropogenic berms can be expected to perform during a flood event. Results reveal that TLS, when referenced to a temporary bench mark leveled to within 1.5 cm by RTK-GPS, achieves an absolute vertical accuracy of less than 3 cm (VRMSE) with a scan resolution of 10 cm or finer. In regards to berm morphodynamics, a near-linear increase in tide elevation over two hours caused a non-linear lowering of the berm crest with time, characterized first by a gradual and then by a rapid change. The overall erosion of the berm correlates best with the swash elevation in relation to the berm toe elevation. Across the three berm experiments, erosion begins when the swash elevation is about 13% below the toe of the berm, relative to the initial berm height, and the berm is overtopped when the swash elevation is 25-30% of the initial berm height and the berm is 70-75% eroded by volume.

Flexor digitorum brevis transfer for floating toe prevention after Weil osteotomy: a cadaveric study.

PubMed

Lee, Lydia C; Charlton, Timothy P; Thordarson, David B

2013-12-01

A floating toe deformity occurs in many patients who undergo Weil osteotomies. It is likely caused by the failure of the windlass mechanism in shortening the metatarsal. For patients who require a proximal interphalangeal (PIP) joint arthroplasty or fusion in addition to a Weil osteotomy, the transfer of the flexor digitorum brevis (FDB) tendon to the PIP joint might restore the windlass mechanism and decrease the incidence of floating toes. Fourteen cadaveric foot specimens were examined to determine the effects of changing metatarsal length as well as tensioning the FDB tendon on the angle of the metatarsophalangeal (MTP) joint as a measure of a floating toe. Shortening and lengthening the second metatarsal resulted in a significant change in MTP angle (P = .03 and .02, respectively), though there was no clear relationship found between the amount of change in metatarsal length and the change in MTP angle. Transferring the FDB to a PIP arthroplasty site plantarflexed the MTP joint and corrected floating toes; the change in angle was significant compared with the control and shortening groups (P = .0001 and .002, respectively). This study supports the theory that change in length of the metatarsal, possibly via the windlass mechanism, plays a role in the pathophysiology of the floating toe deformity. Tensioning and transferring the FDB tendon into the PIP joint helped prevent the floating toe deformity in this cadaveric model. Continued research in this subject will help to refine methods of prevention and correction of the floating toe deformity.

Long-Term Evolution of a Long-Term Evolution Model

DTIC Science & Technology

2011-01-01

equations for the movement of the dune toe yD and the berm crest location yB are dyD/dt=(qw-qo)/DD and dyB/dt=-(qw-qo)/(DB+DC) respectively, where qw...and sand properties, yB and yD = distances to the seaward end of the berm and the dune toe , respectively, with the y-axis pointing offshore, y50...relative to mean sea level, MSL); zD = dune toe elevation (with respect to MSL); T = swash period (taken to be the same as the wave period); and Cs

Neural Networks and Their Application to Air Force Personnel Modeling

DTIC Science & Technology

1991-11-01

specifications of the error function ( Chauvin , 1990; Hanson & Pratt, 1989) and found that out-of-sample performance can be improved by this modification...X X Black X X X X Hispanic X X - White & female X Black & male X Female X X X X Xŕ] Single or married indicator X X X X X X Age less than or equal 17...administration, female in unknown specialty, and black male in support and administration. 7Five dummies: TOE 4 and YOS 2. TOE 6 and YOS 1. TOE 6 and

Emplacement of Pahoehoe Toe Networks: Observations of May, 2010 Tube-fed Flows at Kilauea Volcano, Hawai'i

NASA Astrophysics Data System (ADS)

Crown, D. A.; Ramsey, M.; Hon, K.

2010-12-01

Pahoehoe lava flows are compound features that consist of multiple overlapping and interfingering lobes and exhibit morphologically diverse surfaces characterized by channelized zones, smooth-surfaced sheets, and numerous, small toe networks. Previous work compiled detailed planform maps of solidified pahoehoe toe networks to document their morphology, morphometry and connective relationships in order to provide constraints on lava transport models. In order to expand this research to active flow emplacement, we observed slow-moving, tube-fed pahoehoe flows on the coastal plain near Kalapana, Hawaii in May, 2010. The evolution of pahoehoe toe and toe network characteristics over their emplacement history was examined and the role of small-scale flow inflation on the advance of pahoehoe lobes evaluated. We collected both visible video footage and high-speed, high-precision thermal infrared (TIR) data using a FLIR S-40 camera. The TIR data provide surface temperature maps that can be easily used to identify formation of new toes and track their growth and surface cooling. From these maps, lobe development, connective relationships, and frontal and lateral spreading rates can be analyzed. Preliminary results suggest that regular cycles of activity characterize the development of these pahoehoe lobes: 1) emplacement of new toes in local topographic lows at the front, margin, and within the interior of an active lobe forming small interconnected networks, 2) decline and sometimes temporary cessation in the production of new pahoehoe toes, 3) inflation of the recently emplaced flow surface, either partially or en masse depending on the rate of influx of new lava, the degree of irregularity of the pre-flow surface, and/or the slope across the recently emplaced lava surface, and 4) fracturing of the recently emplaced surface crust that feeds emplacement of new toes. Inflation fractures typically cut across several previously emplaced toes and can occur at the front, along the margins, or within the active lobe, even at significant distances behind the flow front.

Biomechanical comparison of single-row, double-row, and transosseous-equivalent repair techniques after healing in an animal rotator cuff tear model.

PubMed

Quigley, Ryan J; Gupta, Akash; Oh, Joo-Han; Chung, Kyung-Chil; McGarry, Michelle H; Gupta, Ranjan; Tibone, James E; Lee, Thay Q

2013-08-01

The transosseous-equivalent (TOE) rotator cuff repair technique increases failure loads and contact pressure and area between tendon and bone compared to single-row (SR) and double-row (DR) repairs, but no study has investigated if this translates into improved healing in vivo. We hypothesized that a TOE repair in a rabbit chronic rotator cuff tear model would demonstrate a better biomechanical profile than SR and DR repairs after 12 weeks of healing. A two-stage surgical procedure was performed on 21 New Zealand White Rabbits. The right subscapularis tendon was transected and allowed to retract for 6 weeks to simulate a chronic tear. Repair was done with the SR, DR, or TOE technique and allowed to heal for 12 weeks. Cyclic loading and load to failure biomechanical testing was then performed. The TOE repair showed greater biomechanical characteristics than DR, which in turn were greater than SR. These included yield load (p < 0.05), energy absorbed to yield (p < 0.05), and ultimate load (p < 0.05). For repair of a chronic, retracted rotator cuff tear, the TOE technique was the strongest biomechanical construct after healing followed by DR with SR being the weakest. Copyright © 2013 Orthopaedic Research Society.

The Pace of Perceivable Extreme Climate Change

NASA Astrophysics Data System (ADS)

Tan, X.; Gan, T. Y.

2015-12-01

When will the signal of obvious changes in extreme climate emerge over climate variability (Time of Emergence, ToE) is a key question for planning and implementing measures to mitigate the potential impact of climate change to natural and human systems that are generally adapted to potential changes from current variability. We estimated ToEs for the magnitude, duration and frequency of global extreme climate represented by 24 extreme climate indices (16 for temperature and 8 for precipitation) with different thresholds of the signal-to-noise (S/N) ratio based on projections of CMIP5 global climate models under RCP8.5 and RCP4.5 for the 21st century. The uncertainty of ToE is assessed by using 3 different methods to calculate S/N for each extreme index. Results show that ToEs of the projected extreme climate indices based on the RCP4.5 climate scenarios are generally projected to happen about 20 years later than that for the RCP8.5 climate scenarios. Under RCP8.5, the projected magnitude, duration and frequency of extreme temperature on Earth will all exceed 2 standard deviations by 2100, and the empirical 50th percentile of the global ToE for the frequency and magnitude of hot (cold) extreme are about 2040 and 2054 (2064 and 2054) for S/N > 2, respectively. The 50th percentile of global ToE for the intensity of extreme precipitation is about 2030 and 2058 for S/N >0.5 and S/N >1, respectively. We further evaluated the exposure of ecosystems and human societies to the pace of extreme climate change by determining the year of ToE for various extreme climate indices projected to occur over terrestrial biomes, marine realms and major urban areas with large populations. This was done by overlaying terrestrial, ecoregions and population maps with maps of ToE derived, to extract ToEs for these regions. Possible relationships between GDP per person and ToE are also investigated by relating the mean ToE for each country and its average value of GDP per person.

Decadal-scale variation in dune erosion and accretion rates: An investigation of the significance of changing storm tide frequency and magnitude on the Sefton coast, UK

NASA Astrophysics Data System (ADS)

Pye, K.; Blott, S. J.

2008-12-01

Monitoring of frontal dune erosion and accretion on the Sefton coast in northwest England over the past 50 years has revealed significant spatial and temporal variations. Previous work has shown that the spatial variations primarily reflect longshore differences in beach and nearshore morphology, energy regime and sediment budget, but the causes of temporal variations have not previously been studied in detail. This paper presents the results of work carried out to test the hypothesis that a major cause of temporal variation is changes in the frequency and magnitude of storms, surges and resulting high tides. Dune toe erosion/accretion records dating from 1958 have been compared with tide gauge records at Liverpool and Heysham. Relatively high dune erosion rates at Formby Point 1958-1968 were associated with a relatively large number of storm tides. Slower erosion at Formby, and relatively rapid accretion in areas to the north and south, occurred during the 1970's and 1980's when there were relatively few major storm tides. After 1990 rates of dune erosion at Formby increased again, and dunes to the north and south experienced slower accretion. During this period high storm tides have been more frequent, and the annual number of hours with water levels above the critical level for dune erosion has increased significantly. An increase in the rate of mean sea-level rise at both Liverpool and Heysham is evident since 1990, but we conclude that this factor is of less importance than the occurrence of extreme high tides and wave action associated with storms. The incidence of extreme high tides shows an identifiable relationship with the lunar nodal tidal cycle, but the evidence indicates that meteorological forcing has also had a significant effect. Storms and surges in the eastern Irish Sea are associated with Atlantic depressions whose direction and rate of movement have a strong influence on wind speeds, wave energy and the height of surge tides. However, preliminary analysis has indicated only a modest relationship between dune erosion/accretion rates and the North Atlantic Oscillation index.

Automatic Monitoring System Design and Failure Probability Analysis for River Dikes on Steep Channel

NASA Astrophysics Data System (ADS)

Chang, Yin-Lung; Lin, Yi-Jun; Tung, Yeou-Koung

2017-04-01

The purposes of this study includes: (1) design an automatic monitoring system for river dike; and (2) develop a framework which enables the determination of dike failure probabilities for various failure modes during a rainstorm. The historical dike failure data collected in this study indicate that most dikes in Taiwan collapsed under the 20-years return period discharge, which means the probability of dike failure is much higher than that of overtopping. We installed the dike monitoring system on the Chiu-She Dike which located on the middle stream of Dajia River, Taiwan. The system includes: (1) vertical distributed pore water pressure sensors in front of and behind the dike; (2) Time Domain Reflectometry (TDR) to measure the displacement of dike; (3) wireless floating device to measure the scouring depth at the toe of dike; and (4) water level gauge. The monitoring system recorded the variation of pore pressure inside the Chiu-She Dike and the scouring depth during Typhoon Megi. The recorded data showed that the highest groundwater level insides the dike occurred 15 hours after the peak discharge. We developed a framework which accounts for the uncertainties from return period discharge, Manning's n, scouring depth, soil cohesion, and friction angle and enables the determination of dike failure probabilities for various failure modes such as overtopping, surface erosion, mass failure, toe sliding and overturning. The framework was applied to Chiu-She, Feng-Chou, and Ke-Chuang Dikes on Dajia River. The results indicate that the toe sliding or overturning has the highest probability than other failure modes. Furthermore, the overall failure probability (integrate different failure modes) reaches 50% under 10-years return period flood which agrees with the historical failure data for the study reaches.

Conceptual Model Development for Sea Turtle Nesting Habitat: Support for USACE Navigation Projects

DTIC Science & Technology

2015-08-01

regional values. • Beach Width: The width of the beach (m) defines the region from the shoreline to the dune toe . Loggerhead turtles tend to prefer...primary drivers of the model parameters. • Beach Elevation: Beach elevation (m) is measured from the shoreline to the dune toe . Elevation influences...mapping, and morphological features in combination with imagery-derived environmental parameters (i.e., dune vegetation) have not been attempted

Calculation methods study on hot spot stress of new girder structure detail

NASA Astrophysics Data System (ADS)

Liao, Ping; Zhao, Renda; Jia, Yi; Wei, Xing

2017-10-01

To study modeling calculation methods of new girder structure detail's hot spot stress, based on surface extrapolation method among hot spot stress method, a few finite element analysis models of this welded detail were established by finite element software ANSYS. The influence of element type, mesh density, different local modeling methods of the weld toe and extrapolation methods was analyzed on hot spot stress calculation results at the toe of welds. The results show that the difference of the normal stress in the thickness direction and the surface direction among different models is larger when the distance from the weld toe is smaller. When the distance from the toe is greater than 0.5t, the normal stress of solid models, shell models with welds and non-weld shell models tends to be consistent along the surface direction. Therefore, it is recommended that the extrapolated point should be selected outside the 0.5t for new girder welded detail. According to the results of the calculation and analysis, shell models have good grid stability, and extrapolated hot spot stress of solid models is smaller than that of shell models. So it is suggested that formula 2 and solid45 should be carried out during the hot spot stress extrapolation calculation of this welded detail. For each finite element model under different shell modeling methods, the results calculated by formula 2 are smaller than those of the other two methods, and the results of shell models with welds are the largest. Under the same local mesh density, the extrapolated hot spot stress decreases gradually with the increase of the number of layers in the thickness direction of the main plate, and the variation range is within 7.5%.

Plantar pressure distribution of ostrich during locomotion on loose sand and solid ground

PubMed Central

Han, Dianlei; Ma, Songsong; Luo, Gang; Ji, Qiaoli; Xue, Shuliang; Yang, Mingming; Li, Jianqiao

2017-01-01

Background The ostrich is a cursorial bird with extraordinary speed and endurance, especially in the desert, and thus is an ideal large-scale animal model for mechanic study of locomotion on granular substrate. Methods The plantar pressure distributions of ostriches walking/running on loose sand/solid ground were recorded using a dynamic pressure plate. Results The center of pressure (COP) on loose sand mostly originated from the middle of the 3rd toe, which differed from the J-shaped COP trajectory on solid ground. At mid-stance, a high-pressure region was observed in the middle of the 3rd toe on loose sand, but three high-pressure regions were found on solid ground. The gait mode significantly affected the peak pressures of the 3rd and 4th toes (p = 1.5 × 10−6 and 2.39 × 10−8, respectively), but not that of the claw (p = 0.041). The effects of substrate were similar to those of the gait mode. Discussion Ground reaction force trials of each functional part showed the 3rd toe bore more body loads and the 4th toe undertook less loads. The pressure distributions suggest balance maintenance on loose sand was provided by the 3rd and 4th toes and the angle between their length axes. On loose sand, the middle of the 3rd toe was the first to touch the sand with a smaller attack angle to maximize the ground reaction force, but on solid ground, the lateral part was the first to touch the ground to minimize the transient loading. At push-off, the ostrich used solidification properties of granular sand under the compression of the 3rd toe to generate sufficient traction. PMID:28761792

Accuracy and reproducibility of novel echocardiographic three-dimensional automated software for the assessment of the aortic root in candidates for thanscatheter aortic valve replacement.

PubMed

García-Martín, Ana; Lázaro-Rivera, Carla; Fernández-Golfín, Covadonga; Salido-Tahoces, Luisa; Moya-Mur, Jose-Luis; Jiménez-Nacher, Jose-Julio; Casas-Rojo, Eduardo; Aquila, Iolanda; González-Gómez, Ariana; Hernández-Antolín, Rosana; Zamorano, José Luis

2016-07-01

A specialized three-dimensional transoesophageal echocardiography (3D-TOE) reconstruction tool has recently been introduced; the system automatically configures a geometric model of the aortic root from the images obtained by 3D-TOE and performs quantitative analysis of these structures. The aim of this study was to compare the measurements of the aortic annulus (AA) obtained by the new model to that obtained by 3D-TOE and multidetector computed tomography (MDCT) in candidates to transcatheter aortic valve implantation (TAVI) and to assess the reproducibility of this new method. We included 31 patients who underwent TAVI. The AA diameters and area were evaluated by the manual 3D-TOE method and by the automatic software. We showed an excellent correlation between the measurements obtained by both methods: intra-class correlation coefficient (ICC): 0.731 (0.508-0.862), r: 0.742 for AA diameter and ICC: 0.723 (0.662-0.923), r: 0.723 for the AA area, with no significant differences regardless of the method used. The interobserver variability was superior for the automatic measurements than for the manual ones. In a subgroup of 10 patients, we also found an excellent correlation between the automatic measurements and those obtained by MDCT, ICC: 0.941 (0.761-0.985), r: 0.901 for AA diameter and ICC: 0.853 (0.409-0.964), r: 0.744 for the AA area. The new automatic 3D-TOE software allows modelling and quantifying the aortic root from 3D-TOE data with high reproducibility. There is good correlation between the automated measurements and other 3D validated techniques. Our results support its use in clinical practice as an alternative to MDCT previous to TAVI. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2015. For permissions please email: journals.permissions@oup.com.

21 CFR 888.3730 - Toe joint phalangeal (hemi-toe) polymer prosthesis.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Toe joint phalangeal (hemi-toe) polymer prosthesis. 888.3730 Section 888.3730 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... (hemi-toe) polymer prosthesis. (a) Identification. A toe joint phalangeal (hemi-toe) polymer prosthesis...

21 CFR 888.3730 - Toe joint phalangeal (hemi-toe) polymer prosthesis.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Toe joint phalangeal (hemi-toe) polymer prosthesis. 888.3730 Section 888.3730 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... (hemi-toe) polymer prosthesis. (a) Identification. A toe joint phalangeal (hemi-toe) polymer prosthesis...

21 CFR 888.3730 - Toe joint phalangeal (hemi-toe) polymer prosthesis.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Toe joint phalangeal (hemi-toe) polymer prosthesis. 888.3730 Section 888.3730 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... (hemi-toe) polymer prosthesis. (a) Identification. A toe joint phalangeal (hemi-toe) polymer prosthesis...

21 CFR 888.3730 - Toe joint phalangeal (hemi-toe) polymer prosthesis.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Toe joint phalangeal (hemi-toe) polymer prosthesis. 888.3730 Section 888.3730 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... (hemi-toe) polymer prosthesis. (a) Identification. A toe joint phalangeal (hemi-toe) polymer prosthesis...

21 CFR 888.3730 - Toe joint phalangeal (hemi-toe) polymer prosthesis.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Toe joint phalangeal (hemi-toe) polymer prosthesis. 888.3730 Section 888.3730 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN... (hemi-toe) polymer prosthesis. (a) Identification. A toe joint phalangeal (hemi-toe) polymer prosthesis...

Non-linear feedbacks drive strain partitioning within an active orogen, southern Alaska

NASA Astrophysics Data System (ADS)

Hooks, B.; Koons, P. O.; Upton, P.

2011-12-01

Temperature plays a very important role in the partitioning of deformation within an active orogen. Local variations in the thermal structure of actively uplifting areas can reinforce focused partitioning of strain locally, whereas regional variations can alter deformation patterns on a much broader scale resulting in the re-organization of an entire orogen. Within southern Alaska, the Yakutat micro-terrane has been subducting beneath North America over the previous ~10 Ma. Early deformation related to this event drove uplift of the Alaska Range, as evidenced by stratigraphic and thermochronologic datasets. This was followed by a southerly discontinuous spatial jump in the deformation front to the coastal St. Elias Range. Here we present 3D numerical models that simulate deformation of Earth materials given assigned applied velocity boundary conditions and mechanical and thermal constitutive relationships on a macro- (plate boundary) and meso-scale (<50-km). The goal is to reproduce first-order strain and uplift patterns within this evolving orogen. The macro-scale model undergoes a spatial and temporal reorganization of deformation as strain is progressively shifted to a trench-ward orogenic wedge, the inlet orogen. Subduction related cooling of the fore-arc (i.e. tectonic refrigeration) provides control on the location of the inlet orogen. This control is based upon the creation of a thin sliver of cold, strong material along the mega-thrust interface. The stronger mega-thrust facilitates more efficient transfer of strain, driving the formation of the inlet orogen and determining the location of its frontal toe. This toe is further stabilized by upward displacement of the upper crust over the refrigerated section. This upward motion causes thermal weakening of the upper crust as a tectonic aneurysm with the location controlled by the thermally strengthened lower crust. The net result is an ever weakening upper crust that focuses strain creating dramatic topography, extreme rates of erosion and uplift, and fast exhumation.

What is a Dune: Developing AN Automated Approach to Extracting Dunes from Digital Elevation Models

NASA Astrophysics Data System (ADS)

Taylor, H.; DeCuir, C.; Wernette, P. A.; Taube, C.; Eyler, R.; Thopson, S.

2016-12-01

Coastal dunes can absorb storm surge and mitigate inland erosion caused by elevated water levels during a storm. In order to understand how a dune responds to and recovers from a storm, it is important that we can first identify and differentiate the beach and dune from the rest of the landscape. Current literature does not provide a consistent definition of what the dune features (e.g. dune toe, dune crest) are or how they can be extracted. The purpose of this research is to develop enhanced approaches to extracting dunes from a digital elevation model (DEM). Manual delineation, convergence index, least-cost path, relative relief, and vegetation abundance were compared and contrasted on a small area of Padre Island National Seashore (PAIS), Preliminary results indicate that the method used to extract the dune greatly affects our interpretation of how the dune changes. The manual delineation method was time intensive and subjective, while the convergence index approach was useful to easily identify the dune crest through maximum and minimum values. The least-cost path method proved to be time intensive due to data clipping; however, this approach resulted in continuous geomorphic landscape features (e.g. dune toe, dune crest). While the relative relief approach shows the most features in multi resolution, it is difficult to assess the accuracy of the extracted features because extracted features appear as points that can vary widely in their location from one meter to the next. The vegetation approach was greatly impacted by the seasonal and annual fluctuations of growth but is advantageous in historical change studies because it can be used to extract consistent dune formation from historical aerial imagery. Improving our ability to more accurately assess dune response and recovery to a storm will enable coastal managers to more accurately predict how dunes may respond to future climate change scenarios.

Rip currents, mega-cusps, and eroding dunes

USGS Publications Warehouse

Thornton, E.B.; MacMahan, J.; Sallenger, A.H.

2007-01-01

Dune erosion is shown to occur at the embayment of beach mega-cusps O(200 m alongshore) that are associated with rip currents. The beach is the narrowest at the embayment of the mega-cusps allowing the swash of large storm waves coincident with high tides to reach the toe of the dune, to undercut the dune and to cause dune erosion. Field measurements of dune, beach, and rip current morphology are acquired along an 18 km shoreline in southern Monterey Bay, California. This section of the bay consists of a sandy shoreline backed by extensive dunes, rising to heights exceeding 40 m. There is a large increase in wave height going from small wave heights in the shadow of a headland, to the center of the bay where convergence of waves owing to refraction over the Monterey Bay submarine canyon results in larger wave heights. The large alongshore gradient in wave height results in a concomitant alongshore gradient in morphodynamic scale. The strongly refracted waves and narrow bay aperture result in near normal wave incidence, resulting in well-developed, persistent rip currents along the entire shoreline. The alongshore variations of the cuspate shoreline are found significantly correlated with the alongshore variations in rip spacing at 95% confidence. The alongshore variations of the volume of dune erosion are found significantly correlated with alongshore variations of the cuspate shoreline at 95% confidence. Therefore, it is concluded the mega-cusps are associated with rip currents and that the location of dune erosion is associated with the embayment of the mega-cusp.

Translational Response of Toe-Restrained Retaining Walls to Earthquake Ground Motions Using CorpsWallSlip (CWSlip)

DTIC Science & Technology

2007-06-01

corresponding software developed for the translational response of rock- founded retaining walls buttressed at their toe by a reinforced concrete slab...by a Reinforced Concrete Slab ...........................................................................................................32 2.1...2.5 New translational analysis model of a wall retaining a partially submerged backfill and buttressed by a reinforced concrete slab

Broken toe - self-care

MedlinePlus

Fractured toe - self-care; Broken bone - toe - self-care; Fracture - toe - self-care; Fracture phalanx - toe ... often treated without surgery and can be taken care of at home. Severe injuries include: Breaks that ...

Emergence of the significant local warming of Korea in CMIP5 projections

NASA Astrophysics Data System (ADS)

Boo, Kyung-On; Shim, Sungbo; Kim, Jee-Eun

2016-04-01

According to IPCC AR5, anthropogenic influence on warming is obvious in local scales, especially in some tropical regions. Detection of significant local warming is important for adaptation to climate change of society and ecosystem. Recently much attention has focused on the time of emergence (ToE) for the signal of anthropogenic climate change against the natural climate variability. Motivated from the previous studies, this study analyzes ToE of regional surface air temperature over Korea. Simulations of CMIP5 15 models are used for RCP 2.6, 4.5 and 8.5. For each year, JJA and DJF temperature anomalies are calculated for the time period 1900-1929. For noise of interannual variability, natural-only historical simulations of CMIP5 12 models are used and the standard deviation of the time series is obtained. For signal of warming, we examine the year when the signal above 2 standard deviations is detected in 80% of the models using 30-year smoothed time series. According to our results, interannual variability is larger in land than ocean. Seasonally, it is larger in winter than in summer. Accordingly, ToE of summertime temperature is earlier than that in winter and is expected to appear in 2030s from three RCPs. The seasonal difference is consistent with previous studies. Wintertime ToE appears in 2040s for RCP85 and 2060s for RCP4.5. The different emergence time between RCP8.5 and RCP4.5 reflects the influence of mitigation. In a similar way, daily maximum and minimum temperatures are analyzed. ToE of Tmin appears earlier than that of Tmax and difference is small. Acknowledgements. This study is supported by the National Institute of Meteorological Sciences, Korea Meteorological Administration (NIMR-2012-B-2).

Predicting ground contact events for a continuum of gait types: An application of targeted machine learning using principal component analysis.

PubMed

Osis, Sean T; Hettinga, Blayne A; Ferber, Reed

2016-05-01

An ongoing challenge in the application of gait analysis to clinical settings is the standardized detection of temporal events, with unobtrusive and cost-effective equipment, for a wide range of gait types. The purpose of the current study was to investigate a targeted machine learning approach for the prediction of timing for foot strike (or initial contact) and toe-off, using only kinematics for walking, forefoot running, and heel-toe running. Data were categorized by gait type and split into a training set (∼30%) and a validation set (∼70%). A principal component analysis was performed, and separate linear models were trained and validated for foot strike and toe-off, using ground reaction force data as a gold-standard for event timing. Results indicate the model predicted both foot strike and toe-off timing to within 20ms of the gold-standard for more than 95% of cases in walking and running gaits. The machine learning approach continues to provide robust timing predictions for clinical use, and may offer a flexible methodology to handle new events and gait types. Copyright © 2016 Elsevier B.V. All rights reserved.

Comparison of Two Alternative Methods for Tracking Toe Trajectory

NASA Technical Reports Server (NTRS)

Miller, Chris; Peters, Brian; Brady, Rachel; Mulavara, Ajitkumar; Warren, Liz; Feiveson, Al; Bloomberg, Jacob

2007-01-01

Toe trajectory during the swing phase of locomotion has been identified as a precise motor control task (Karst, et al., 1999). The standard method for tracking toe trajectory is to place a marker on the superior aspect of the distal end of the 2nd toe itself (Karst, et al., 1999; Winter, 1992). However, others have based their toe trajectory results either on a marker positioned on the lateral aspect of the 5th metatarsal head (Dingwell, et al., 1999; Osaki, et al., 2007), or on a virtual toe marker computed at the anterior tip of the second toe based on the positions of other real foot markers (Miller, et al., 2006). While these methods for tracking the toe may seem similar, their results may not be directly comparable. The purpose of this study was to compute toe trajectory parameters using a 5th metatarsal marker and a virtual toe marker, and compare their results with those of the standard toe marker.

A method for determining average beach slope and beach slope variability for U.S. sandy coastlines

USGS Publications Warehouse

Doran, Kara S.; Long, Joseph W.; Overbeck, Jacquelyn R.

2015-01-01

The U.S. Geological Survey (USGS) National Assessment of Hurricane-Induced Coastal Erosion Hazards compares measurements of beach morphology with storm-induced total water levels to produce forecasts of coastal change for storms impacting the Gulf of Mexico and Atlantic coastlines of the United States. The wave-induced water level component (wave setup and swash) is estimated by using modeled offshore wave height and period and measured beach slope (from dune toe to shoreline) through the empirical parameterization of Stockdon and others (2006). Spatial and temporal variability in beach slope leads to corresponding variability in predicted wave setup and swash. For instance, seasonal and storm-induced changes in beach slope can lead to differences on the order of 1 meter (m) in wave-induced water level elevation, making accurate specification of this parameter and its associated uncertainty essential to skillful forecasts of coastal change. A method for calculating spatially and temporally averaged beach slopes is presented here along with a method for determining total uncertainty for each 200-m alongshore section of coastline.

Impact on DARCOM of Nonstandard MTOE.

DTIC Science & Technology

1981-03-01

DIFFERENCES BETWEEN TOE AND MTOE TYPE NR RECORDS TOTAL QTY OF TOTAL QTY OF TOTAL DIFF ORGN IDENTIFIED ITEMS AUTH ITEMS AUTH BETWEEN TOE BY TOE BY MTOE AND MTOE...BETWEEN TOE AND MTOE TYPE NR RECORDS TOTAL QTY OF TOTAL QTY OF TOTAL DIFF ORGN IDENTIFIED ITEMS AUTH ITEMS AUTH BETWEEN TOE BY TOE BY MTOE AND MTOE 01

Effect of Guci powder on toe swelling induced by egg white in rats

NASA Astrophysics Data System (ADS)

Xie, Guoqi; Hao, Shaojun; Shen, Huiling; Ma, Zhenzhen; Zhang, Xuehui; Zhang, Zhengchen

2018-04-01

To observe the effect of Guci Powder on foot swelling induced by egg white in rats. 50 male rats were randomly divided into normal saline group (n=10), white vinegar group (n=10) and Guning lotion group (n=10). There were 10 rats in the high-dose group and 10 in the low-dose group. The rats in each group were treated with the drug on the left and right feet of the rats. 0.5 hours after the last administration, the rats in each group were inflamed. The left hindsole plantar volume was measured respectively, so that the difference of the posterior toe volume before inflammation was taken as the swelling degree, and the swelling degree of each group was calculated. Compared with physiological saline group, the rats' egg white toe swelling (P<0.01) was significantly inhibited at 0.5˜6h after administration. The swelling of egg white toe in rats was inhibited at 0.5˜2h (P<0.05). Bone spur powder has a good intervention effect on the model of toe swelling induced by egg white in rats, and the external application of bone spur powder has anti-inflammatory and swelling effect.

Gully incision rates on the bedrock of a large dip-slope landslide revealed by multi-period LiDAR DEMs

NASA Astrophysics Data System (ADS)

Chan, Y. C.; Hsieh, Y. C.

2017-12-01

Recent advances in airborne laser scanning (ALS) technology have provided a great opportunity for characterizing surface erosion through developing improved methods in multi-period DEM differencing and geomorphometry. This study uses three periods of ALS digital elevation model (DEM) data to analyze the short-term erosional features of the Tsaoling landslide triggered by the 1999 Chi-Chi earthquake in Taiwan. Two methods for calculating the bedrock incision rate, the equal-interval cross section selection method and the continuous swath profiles selection method, were used in the study after nearly ten years of gully incision following the earthquake-triggered dip-slope landslide. Multi-temporal gully incision rates were obtained using the continuous swath profiles selection method, which is considered a practical and convenient approach in terrain change studies. After error estimation and comparison of the multi-period ALS DEMs, the terrain change in different periods can be directly calculated, reducing time-consuming fieldwork such as installation of erosion pins and measurement of topographic cross sections on site. In this study, the gully bedrock incision rates ranged between 0.23 and 3.98 m/year, remarkably higher than the typical results from the previous studies. By comparing the DEM data, aerial photos, and precipitation records of this area, the effects of erosion could be observed from the retreat of the Chunqiu Cliff outline during August 2011 to September 2012. It was inferred that the change in the topographic elevation during 2011-2012 was mainly due to the torrential rain brought by Typhoon Soula, which occurred on 30 July 2012. The local gully incision rate in the lower part of the landslide surface was remarkably faster than that of the other regions, suggesting that the fast incision of the toe area possibly contributes to the occurrence of repeated landslides in the Tsaoling area.

Sailplane Glide Performance and Control Using Fixed and Articulating Winglets. M.S. Thesis

NASA Technical Reports Server (NTRS)

Colling, James David

1995-01-01

An experimental study was conducted to investigate the effects of controllable articulating winglets on glide performance and yawing moments of high performance sailplanes. Testing was conducted in the Texas A&M University 7 x 10 foot Low Speed Wind Tunnel using a full-scale model of the outboard 5.6 feet of a 15 meter class high performance sailplane wing. Different wing tip configurations could be easily mounted to the wing model. A winglet was designed in which the cant and toe angles as well as a rudder on the winglet could be adjusted to a range of positions. Cant angles used in the investigation consisted of 5, 25, and 40 degrees measured from the vertical axis. Toe-out angles ranged from 0 to 22.5 degrees. A rudder on the winglet was used to study the effects of changing the camber of the winglet airfoil on wing performance and wing yawing moments. Rudder deflections consisted of-10, 0, and 10 degrees. Test results for a fixed geometry winglet and a standard wing tip are presented to show the general behavior of winglets on sailplane wings, and the effects of boundary-layer turbulators on the winglets are also presented. By tripping the laminar boundary-layer to turbulent before laminar separation occurs, the wing performance was increased at low Reynolds numbers. The effects on the lift and drag, yawing moment, pitching moment, and wing root bending moment of the model are presented. Oil flows were used on the wing model with the fixed geometry winglet and the standard wing tip to visualize flow directions and areas of boundary layer transition. A cant angle of 25 degrees and a toe-out angle of 2.5 degrees provided an optimal increase in wing performance for the cant and toe angles tested. Maximum performance was obtained when the winglet rudder remained in the neutral position of zero degrees. By varying the cant, toe, and rudder angles from their optimized positions, wing performance decreases. Although the winglet rudder proved to be more effective in increasing the yawing moment compared to varying the cant and toe angles, the amount of increased yawing moment was insignificant when compared to that produced by the vertical tail. A rudder on the winglet was determined to be ineffective for providing additional yaw control.

Fatigue Magnification Factors of Arc-Soft-Toe Bracket Joints

NASA Astrophysics Data System (ADS)

Fu, Qiang; Li, Huajun; Wang, Hongqing; Wang, Shuqing; Li, Dejiang; Li, Qun; Fang, Hui

2018-06-01

Arc-soft-toe bracket (ASTB), as a joint structure in the marine structure, is the hot spot with significant stress concentration, therefore, fatigue behavior of ASTBs is an important point of concern in their design. Since macroscopic geometric factors obviously influence the stress flaws in joints, the shapes and sizes of ASTBs should represent the stress distribution around cracks in the hot spots. In this paper, we introduce a geometric magnification factor for reflecting the macroscopic geometric effects of ASTB crack features and construct a 3D finite element model to simulate the distribution of stress intensity factor (SIF) at the crack endings. Sensitivity analyses with respect to the geometric ratio H t / L b , R/ L b , L t / L b are performed, and the relations between the geometric factor and these parameters are presented. A set of parametric equations with respect to the geometric magnification factor is obtained using a curve fitting technique. A nonlinear relationship exists between the SIF and the ratio of ASTB arm to toe length. When the ratio of ASTB arm to toe length reaches a marginal value, the SIF of crack at the ASTB toe is not influenced by ASTB geometric parameters. In addition, the arc shape of the ASTB slope edge can transform the stress flowing path, which significantly affects the SIF at the ASTB toe. A proper method to reduce stress concentration is setting a slope edge arc size equal to the ASTB arm length.

A preliminary theoretical study of double blade two-dimensional aerodynamics for applications to vertical axis wind turbines

NASA Astrophysics Data System (ADS)

Weibust, E.

1981-04-01

A NASA model for computing the subsonic, viscous, attached flow around multielement airfoils was used to determine the amount of energy lost when using double blades rather than single ones. The resulting tangential force for the double or single blade configuration used as a criterion is found. Radial spacing, toe-in toe-out angle and tangential displacement (stagger) were varied to see how tagential force is affected. The greatest tangential force values are found to be achieved for maximum allowable radial spacing, which is determined by structural considerations, and is assumed to be on the order of 1.5 c. At this rather large distance, stagger as well as toe-in toe-out angle only gives slight improvements as long as the flow separation effects (stall region) are not considered. A large part of the energy is captured at relatively high wind speeds when the flow on the blades is partly separated (stalled).

Effects of toe-out and toe-in gait with varying walking speeds on knee joint mechanics and lower limb energetics.

PubMed

Khan, Soobia Saad; Khan, Saad Jawaid; Usman, Juliana

2017-03-01

Toe-out/-in gait has been prescribed in reducing knee joint load to medial knee osteoarthritis patients. This study focused on the effects of toe-out/-in at different walking speeds on first peak knee adduction moment (fKAM), second peak KAM (sKAM), knee adduction angular impulse (KAAI), net mechanical work by lower limb as well as joint-level contribution to the total limb work during level walking. Gait analysis of 20 healthy young adults was done walking at pre-defined normal (1.18m/s), slow (0.85m/s) and fast (1.43m/s) walking speeds with straight-toe (natural), toe-out (15°>natural) and toe-in (15°

Disturbance of beach sediment by off-road vehicles

NASA Astrophysics Data System (ADS)

Anders, Fred J.; Leatherman, Stephen P.

1987-10-01

A three-year investigation was undertaken to examine the effects of off-road vehicles (ORVs) on the beach at Fire Island, New York. Within the National Seashore over 45,000 vehicle trips per year are concentrated in the zone seaward of the dune toe. The experimental approach was adopted in order to assess the environmental effects of ORVs. Specially developed instrumentation was used to measure the direct displacement of sand by vehicles traversing the beach. Direct displacement data were reduced graphically and analyzed by stepwise linear regression. The results of 89 field experiments (788 cases) showed that slope, sand compaction, and number of vehicle passes in the same track were the principal factors controlling the measured net seaward displacement of sand. The data suggest that ORV use levels within the National Seashore could be contributing to the overall erosion rate by delivering large quantities of sand to the swash zone (max. of 119,300 m3/yr). However, with proper management downslope movement of sand could be reduced by an order of magnitude. While vehicular passage over the open beach displaces sand seaward, it is not known if such activity actually increases the amount of erosion, measured as net loss to the beach face.

Cardiovascular Effect Is Independent of Hemolytic Toxicity of Tentacle-Only Extract from the Jellyfish Cyanea capillata

PubMed Central

Qianqian, Wang; Sihua, Liu; Yang, Wang; Guoyan, Liu; Jia, Lu; Xuting, Ye; Liming, Zhang

2012-01-01

Our previous studies have confirmed that the crude tentacle-only extract (cTOE) from the jellyfish Cyanea capillata (Cyaneidae) exhibits hemolytic and cardiovascular toxicities simultaneously. So, it is quite difficult to discern the underlying active component responsible for heart injury caused by cTOE. The inactivation of the hemolytic toxicity from cTOE accompanied with a removal of plenty of precipitates would facilitate the separation of cardiovascular component and the investigation of its cardiovascular injury mechanism. In our research, after the treatment of one-step alkaline denaturation followed by twice dialysis, the protein concentration of the treated tentacle-only extract (tTOE) was about 1/3 of cTOE, and SDS-PAGE showed smaller numbers and lower density of protein bands in tTOE. The hemolytic toxicity of tTOE was completely lost while its cardiovascular toxicity was well retained. The observations of cardiac function, histopathology and ultrastructural pathology all support tTOE with significant cardiovascular toxicity. Blood gas indexes and electrolytes changed far less by tTOE than those by cTOE, though still with significant difference from normal. In summary, the cardiovascular toxicity of cTOE can exist independently of the hemolytic toxicity and tTOE can be employed as a better venom sample for further purification and mechanism research on the jellyfish cardiovascular toxic proteins. PMID:22905209

Processes of coastal bluff erosion in weakly lithified sands, Pacifica, California, USA

USGS Publications Warehouse

Collins, B.D.; Sitar, N.

2008-01-01

Coastal bluff erosion and landsliding are currently the major geomorphic processes sculpting much of the marine terrace dominated coastline of northern California. In this study, we identify the spatial and temporal processes responsible for erosion and landsliding in an area of weakly lithified sand coastal bluffs located south of San Francisco, California. Using the results of a five year observational study consisting of site visits, terrestrial lidar scanning, and development of empirical failure indices, we identify the lithologic and process controls that determine the failure mechanism and mode for coastal bluff retreat in this region and present concise descriptions of each process. Bluffs composed of weakly cemented sands (unconfined compressive strength - UCS between 5 and 30??kPa) fail principally due to oversteepening by wave action with maximum slope inclinations on the order of 65 at incipient failure. Periods of significant wave action were identified on the basis of an empirical wave run-up equation, predicting failure when wave run-up exceeds the seasonal average value and the bluff toe elevation. The empirical relationship was verified through recorded observations of failures. Bluffs composed of moderately cemented sands (UCS up to 400??kPa) fail due to precipitation-induced groundwater seepage, which leads to tensile strength reduction and fracture. An empirical rainfall threshold was also developed to predict failure on the basis of a 48-hour cumulative precipitation index but was found to be dependent on a time delay in groundwater seepage in some cases.

Micro-seismic measurements of cliff motion under wave impact and implications for the development of near-horizontal shore platforms

NASA Astrophysics Data System (ADS)

Dickson, Mark E.; Pentney, Rachael

2012-05-01

Few high-resolution measurements of process-form interactions have been taken on rock coasts, but recent studies in California have shown that portable seismometers enable useful proxy measurements of wave-energy delivery to cliffs. Here we describe measurements over 20 days of high frequency ground motion of cliffs formed in sedimentary (flysch) rocks at Okakari Point, north of Auckland, New Zealand. Three sensors were located in a shore-normal array inland from the cliff top and a fourth sensor was bolted to a ledge 2 m above the cliff toe. The nearshore wave field in front of the cliff and shore platform was monitored using a shore-normal array of 5 wave gauges. The instrumentation provided measurements of wave-energy delivery and consequent ground motion, including the first observations of motion at the top and bottom of cliffs. Results showed that horizontal ground motion is dominant at the cliff top, whereas vertical motion is dominant at the cliff toe. Power spectra show that several high frequency peaks occur in data from the cliff toe, whereas a single, broader peak frequency occurs at the cliff top resulting from signal modification as seismic waves pass through tens of metres of cliff rock. A 100 m wide shore platform at the cliff toe fundamentally controls the patterns of observed energy delivery. The shore platform is nearly horizontal, elevated close to high water level, and abruptly plunges into water > 10 m deep at its seaward edge. As expected, the magnitude of ground motion at all sensors is greatest during larger waves. Measurements further show that ground motion, both at the bottom and top of the cliff, is strongest at low tide and weakest at high tide. This observation is opposite to that noted at Santa Cruz, where ground motion was greatest at high tide. At Okakari Point the most significant high frequency ground motions occur at low tide when waves are forced to break (sometimes violently) against the seaward edge of the shore platform. Four distinctive frequency peaks between 1 and 50 Hz increase in magnitude as tidal stage drops, implying that wave breaking against the outside edge of the shore platform represents an important source of vibration. A detailed understanding of the energy source (e.g. short duration shock pressures) and rock resonance is not provided by this study. However, quantifying the spatial and temporal patterns of energy delivery places strong emphasis on the important role of shore platform geometry in filtering wave-energy delivery to the cliff. During the 20-day experiment most wave energy was delivered to the outside edge of the shore platform, not the cliff toe. The geomorphic role of high-frequency shaking from wave impacts remains to be clearly demonstrated, but if wave impacts are capable of eroding rock then the data from this study imply that under present conditions the outside edge of the shore platform may be subject to higher erosion rates than the cliff toe. It is possible that the shore platform is currently being destroyed rather than created, but a longer programme of measurements is required to test this notion.

Observations of Interannual Dune Morphological Evolution With Comparisons to Shoreline Change Along the Columbia River Littoral Cell

NASA Astrophysics Data System (ADS)

Doermann, L.; Kaminsky, G. M.; Ruggiero, P.

2006-12-01

Beach topographic data have been collected along the 160 km-long Columbia River Littoral Cell in southwest Washington and northwest Oregon, USA as part of the Southwest Washington Coastal Erosion Study and a NANOOS pilot project. The monitoring program includes the collection of cross-shore beach profiles at 49 sites for each of the 34 seasons since 1997 (with few exceptions), enabling the investigation of the seasonal to interannual morphological variability of this high-energy coast. We focus here on the dunes backing the beaches, aiming to quantitatively describe the wide variety of characteristics they exhibit, as well as to relate dune evolution to shoreline change. To analyze the large volume of high-quality data, we use automated algorithms and systematic processes to identify the location of the dune toe, crest, and face, and calculate a volume (where enough data are available) and beach width for each survey. We define the position of the dune face as the elevation half-way between the average dune toe and average dune crest elevations at each profile location, and beach width as the horizontal distance between the 2-m contour (~MSL) and the dune toe. Much like shoreline proxies lower on the beach profile, (e.g., the 3-m contour), the location of the dune toe shows large seasonal variability with onshore deposition of sand in summer months and offshore sand transport in the winter. However, the location of the dune face and the elevation of the dune crest are much less variable and are useful in describing the evolution of the dune/beach system in the horizontal and vertical directions, respectively, over interannual time scales. On beaches with the highest shoreline change rates in the study area, the dune face follows the progradational trend of the shoreline with the dune face prograding at approximately 25-50% of the rate of the shoreline. Along many of these beaches that experienced severe erosion during the El Niño of 1997/98, the dune face recovered quickly and has continued to grow steadily seaward since 1999. The consistency of this dune face behavior may prove to be a reliable indicator of longer-scale beach trends due to its ability to remove the effects of even the most severe seasonal changes. These prograding dunes also accreted vertically by 1-2 m for several years as a distinctly new foredune evolved. However, the dune crest height has remained relatively constant for about the last two years and there is some evidence of a new seaward ridge forming as the beach continues to prograde. Coastal stretches that exhibit large variability in shoreline position also feature more erratic dune behavior. On eroding beaches, the dune face follows the trend of the shoreline, although the rate of retreat is not always steady because of winter scarping. In contrast, beaches with stable shorelines (over interannual-decadal scale) are backed by dunes 8-9 m in height that have shown little to no significant dune face position change over the last nine years. Additionally, across the study area, we observe that wider beaches ( > 100 m) are associated with higher rates of shoreline and dune face accretion, while the narrower beaches ( < 100 m) are either stable or eroding.

[Hand reconstruction by microsurgical free toe transfer].

PubMed

Stamate, T; Budurcă, A R; Hermeziu, Oana

2003-01-01

Reconstruction of complex hand mutilations with multi-digital or thumb amputations are best treated with microsurgical toe transfers. We present the results of the first 15 cases operated by the first author, of which 12 are thumb reconstructions (6 great toe and 6 second toe transfers) and 3 long fingers reconstructions with combined second and third toe transfers. There were no microsurgical complications. Cortical integration and functional integration was achieved for all transferred toes, with discriminatory sensibility (m2PD between 5 and 13 mm) and active mobility range between 30 and 60 degrees.

Broken Toe

MedlinePlus

... fracture is severe — particularly if it involves your big toe — you may need a cast or even surgery to ensure proper healing. Most broken toes heal well, usually within four to six weeks. Sometimes, a broken toe may become infected ...

Age-related reduction and independent predictors of toe flexor strength in middle-aged men.

PubMed

Suwa, Masataka; Imoto, Takayuki; Kida, Akira; Iwase, Mitsunori; Yokochi, Takashi

2017-01-01

Toe flexor muscles play an important role in posture and locomotion, and poor toe flexor strength is a risk factor for falls. In this cross-sectional study, we estimated the age-related change in toe flexor strength and compared it with that of handgrip strength. Independent factors predicting toe flexor and handgrip strength were also determined. A total of 1401 male (aged 35-59 years) study participants were divided into five groups according to their chronological age; 35-39, 40-44, 45-49, 50-54, and 55-59 years. Toe flexor and handgrip strength, anthropometry, and resting blood pressure were measured. Fasting blood samples were collected to measure blood glucose, triglycerides, high- and low-density lipoprotein-cholesterols, and albumin. A self-administered lifestyle questionnaire was conducted. Decline in absolute toe flexor and handgrip strength began in the age groups 50-55 and 55-59 years, respectively. In comparison to the mean values of the youngest group, relative toe flexor strength (87.0 ± 26.6%) was significantly lower than handgrip strength (94.4 ± 13.1%) for the oldest group. Multiple regression analyses showed that independent factors predicting both toe flexor and handgrip strength were lean body mass, age, serum albumin, drinking habit, and fat mass. Additionally, fasting blood glucose, diastolic blood pressure, sleeping time and exercise habit were predicting factors of toe flexor strength but not of handgrip strength. Age-related reduction in toe flexor strength was earlier and greater than handgrip strength, and toe flexor strength reflects body composition and metabolic status.

Toe-to-hand transfer: Evolving Indications and Relevant Outcomes

PubMed Central

Waljee, Jennifer F.; Chung, Kevin C.

2014-01-01

In the late 19th century, the first toe to hand transfer was performed in Vienna, Switzerland as a staged procedure by Nicolandi.(1) Since that time, the advent of microsurgery has revolutionized toe to hand transfers. In 1966, Buncke performed the first microvascular toe to thumb transfer in a rhesus monkey.(2) The first toe to thumb transfer using microsurgical techniques in humans was performed by Cobbett in 1969, followed shortly thereafter by the first transfer of a second toe to the thumb position.(3,4) Today, due to expanding microsurgical techniques and surgeon innovation, the indications and techniques for toe-to-hand transfer procedures continue to evolve and now encompass patients with a variety of acquired and congenital hand defects.(5) PMID:23790426

Bunions

MedlinePlus

... toe turned toward the other toes and may cross over the second toe. Corns and calluses develop as a result where the first and second toes overlap. Difficulty wearing regular shoes. You may have problems finding shoes that fit or that do not cause pain.

Early emergence of anthropogenically forced heat waves in the western United States and Great Lakes

NASA Astrophysics Data System (ADS)

Lopez, Hosmay; West, Robert; Dong, Shenfu; Goni, Gustavo; Kirtman, Ben; Lee, Sang-Ki; Atlas, Robert

2018-05-01

Climate projections for the twenty-first century suggest an increase in the occurrence of heat waves. However, the time at which externally forced signals of anthropogenic climate change (ACC) emerge against background natural variability (time of emergence (ToE)) has been challenging to quantify, which makes future heat-wave projections uncertain. Here we combine observations and model simulations under present and future forcing to assess how internal variability and ACC modulate US heat waves. We show that ACC dominates heat-wave occurrence over the western United States and Great Lakes regions, with ToE that occurred as early as the 2020s and 2030s, respectively. In contrast, internal variability governs heat waves in the northern and southern Great Plains, where ToE occurs in the 2050s and 2070s; this later ToE is believed to be a result of a projected increase in circulation variability, namely the Great Plain low-level jet. Thus, greater mitigation and adaptation efforts are needed in the Great Lakes and western United States regions.

Toe spreading ability in men with chronic pelvic pain syndrome

PubMed Central

Yilmaz, Ugur; Rothman, Ivan; Ciol, Marcia A; Yang, Claire C; Berger, Richard E

2005-01-01

Background We examined toe-spreading ability in subjects with chronic pelvic pain syndrome (CPPS) to test the hypothesis that subjects with CPPS could have deficiencies in lower extremity functions innervated by sacral spinal roots. Methods Seventy two subjects with CPPS and 98 volunteer controls were examined as part of a larger study on CPPS. All the subjects underwent a detailed urologic and neurological examination including a toe-spreading examination with a quantitative scoring system. We compared the groups in terms of ability of toe-spreading as either "complete" (all toes spreading) or "incomplete" (at least one interdigital space not spreading) and also by comparing the number of interdigital spaces. For CPPS subjects only, we also analyzed the variation of the National Institutes of Health Chronic Prostatitis Symptom Index (NIH-CPSI) scales by toe-spreading categories. Results CPPS subjects were less often able to spread all toes than subjects without CPPS (p = 0.005). None of the NIH-CPSI sub-scales (pain, urinary symptoms, and quality of life), nor the total score showed an association with toe spreading ability. Conclusion We found toe spreading to be diminished in subjects with CPPS. We hypothesize that incomplete toe spreading in subjects with CPPS may be related to subtle deficits involving the most caudal part of the spinal segments. PMID:15949041

Effects of Speed and Visual-Target Distance on Toe Trajectory During the Swing Phase of Treadmill Walking

NASA Technical Reports Server (NTRS)

Miller, Christopher A.; Feiveson, Al; Bloomberg, Jacob J.

2007-01-01

Toe trajectory during swing phase is a precise motor control task that can provide insights into the sensorimotor control of the legs. The purpose of this study was to determine changes in vertical toe trajectory during treadmill walking due to changes in walking speed and target distance. For each trial, subjects walked on a treadmill at one of five speeds while performing a dynamic visual acuity task at either a far or near target distance (five speeds two targets distances = ten trials). Toe clearance decreased with increasing speed, and the vertical toe peak just before heel strike increased with increasing speed, regardless of target distance. The vertical toe peak just after toe-off was lower during near-target visual acuity tasks than during far-target tasks, but was not affected by speed. The ankle of the swing leg appeared to be the main joint angle that significantly affected all three toe trajectory events. The foot angle of the swing leg significantly affected toe clearance and the toe peak just before heel strike. These results will be used to enhance the analysis of lower limb kinematics during the sensorimotor treadmill testing, where differing speeds and/or visual target distances may be used.

Early reduction in toe flexor strength is associated with physical activity in elderly men.

PubMed

Suwa, Masataka; Imoto, Takayuki; Kida, Akira; Yokochi, Takashi

2016-05-01

[Purpose] To compare the toe flexor, hand grip and knee extensor strengths of young and elderly men, and to examine the association between toe flexor strength and physical activity or inactivity levels. [Subjects and Methods] Young (n=155, 18-23 years) and elderly (n=60, 65-88 years) men participated in this study. Toe flexor, hand grip, and knee extensor strength were measured. Physical activity (time spent standing/walking per day) and inactivity (time spent sitting per day) were assessed using a self-administered questionnaire. [Results] Toe flexor, hand grip, and knee extensor strength of the elderly men were significantly lower than those of the young men. Standing/walking and sitting times of the elderly men were lower than those of the young men. Toe flexor strength correlated with hand grip and knee extensor strength in both groups. In elderly men, toe flexor strength correlated with standing/walking time. In comparison to the young men's mean values, toe flexor strength was significantly lower than knee extensor and hand grip strength in the elderly group. [Conclusion] The results suggest that age-related reduction in toe flexor strength is greater than those of hand grip and knee extensor strengths. An early loss of toe flexor strength is likely associated with reduced physical activity in elderly men.

Presentation-order effects for aesthetic stimulus preference.

PubMed

Englund, Mats P; Hellström, Åke

2012-10-01

For preference comparisons of paired successive musical excerpts, Koh (American Journal of Psychology, 80, 171-185, 1967) found time-order effects (TOEs) that correlated negatively with stimulus valence-the first (vs. the second) of two unpleasant (vs. two pleasant) excerpts tended to be preferred. We present three experiments designed to investigate whether valence-level-dependent order effects for aesthetic preference (a) can be accounted for using Hellström's (e.g., Journal of Experimental Psychology: Human Perception and Performance, 5, 460-477, 1979) sensation-weighting (SW) model, (b) can be generalized to successive and to simultaneous visual stimuli, and (c) vary, in accordance with the stimulus weighting, with interstimulus interval (ISI; for successive stimuli) or stimulus duration (for simultaneous stimuli). Participants compared paired successive jingles (Exp. 1), successive color patterns (Exp. 2), and simultaneous color patterns (Exp. 3), selecting the preferred stimulus. The results were well described by the SW model, which provided a better fit than did two extended versions of the Bradley-Terry-Luce model. Experiments 1 and 2 revealed higher weights for the second stimulus than for the first, and negatively valence-level-dependent TOEs. In Experiment 3, there was no laterality effect on the stimulus weighting and no valence-level-dependent space-order effects (SOEs). In terms of the SW model, the valence-level-dependent TOEs can be explained as a consequence of differential stimulus weighting in combination with stimulus valence varying from low to high, and the absence of valence-level-dependent SOEs as a consequence of the absence of differential weighting. For successive stimuli, there were no important effects of ISI on weightings and TOEs, and, for simultaneous stimuli, duration had only a small effect on the weighting.

Glacial morphology in the Chinese Pamir: Connections among climate, erosion, topography, lithology and exhumation

NASA Astrophysics Data System (ADS)

Schoenbohm, Lindsay M.; Chen, Jie; Stutz, Jamey; Sobel, Edward R.; Thiede, Rasmus C.; Kirby, Benjamin; Strecker, Manfred R.

2014-09-01

Modification of the landscape by glacial erosion reflects the dynamic interplay of climate through temperature, precipitation, and prevailing wind direction, and tectonics through rock uplift and exhumation rate, lithology, and range and fault geometry. We investigate these relationships in the northeast Pamir Mountains using mapping and dating of moraines and terraces to determine the glacial history. We analyze modern glacial morphology to determine glacier area, spacing, headwall relief, debris cover, and equilibrium line altitude (ELA) using the area x altitude balance ratio (AABR), toe-to-headwall altitude ratio (THAR) and toe-to-summit altitude method (TSAM) for 156 glaciers and compare this to lithologic, tectonic, and climatic data. We observe a pronounced asymmetry in glacial ELA, area, debris cover, and headwall relief that we interpret to reflect both structural and climatic control: glaciers on the downwind (eastern) side of the range are larger, more debris covered, have steeper headwalls, and tend to erode headward, truncating the smaller glaciers of the upwind, fault-controlled side of the range. We explain this by the transfer of moisture deep into the range as wind-blown or avalanched snow and by limitations imposed on glacial area on the upwind side of the range by the geometry of the Kongur extensional system (KES). The correspondence between rapid exhumation along the KES and maxima in glacier debris cover and headwall relief and minimums in all measures of ELA suggest that taller glacier headwalls develop in a response to more rapid exhumation rates. However, we find that glaciers in the Muji valley did not extend beyond the range front until at least 43 ka, in contrast to extensive glaciation since 300 ka in the south around the high peaks, a pattern which does not clearly reflect uplift rate. Instead, the difference in glacial history and the presence of large peaks (Muztagh Ata and Kongur Shan) with flanking glaciers likely reflects lithologic control (i.e., the location of crustal gneiss domes) and the formation of peaks that rise above the ELA and escape the glacial buzzsaw.

Foot shape in arboreal birds: two morphological patterns for the same pincer-like tool.

PubMed

Abourachid, Anick; Fabre, Anne-Claire; Cornette, Raphaël; Höfling, Elizabeth

2017-07-01

The feet are the only contact between the body and the substrate in limbed animals and as such they provide a crucial interface between the animal and its environment. This is especially true for bipedal and arboreal species living in a complex three-dimensional environment that likely induces strong selection on foot morphology. In birds, foot morphology is highly variable, with different orientations of the toes, making it a good model for the study of the role of functional, developmental, and phylogenetic constraints in the evolution of phenotypic diversity. Our data on the proportions of the phalanges analyzed in a phylogenetic context show that two different morphological patterns exist that depend mainly on habitat and toe orientation. In the anisodactyl foot, the hallux is the only backward-oriented toe and is enlarged in climbing species and reduced in terrestrial ones. Moreover, a proximo-distal gradient in phalanx size is observed depending on the degree of terrestriality. In the two other cases (heterodactyl and zygodactyl) that have two toes that point backward, the hallux is rather small in contrast to the other backward-pointing toe, which is enlarged. The first pattern is convergent and common among tetrapods and follows rules of skeletal development. The second pattern is unique for the clade and under muscle-morphogenetic control. In all cases, the functional result is the same tool, a pincer-like foot. © 2017 Anatomical Society.

Urinary corticosterone responses to capture and toe-clipping in the cane toad (Rhinella marina) indicate that toe-clipping is a stressor for amphibians.

PubMed

Narayan, Edward J; Molinia, Frank C; Kindermann, Christina; Cockrem, John F; Hero, Jean-Marc

2011-11-01

Toe-clipping, the removal of one or more toes, is a common method used to individually mark free-living animals. Whilst this method is widely used in studies of amphibians, the appropriateness of the method, and its potential detrimental effects have been the subject of debate. Here, we provide for the first time, evidence that toe-clipping is a stressor in a wild amphibian. We measured urinary corticosterone responses of male cane toads (Rhinella marina) to capture and handling only, and to toe-clipping under field conditions. Urinary testosterone concentrations and white blood cell proportions were also measured. Urinary corticosterone metabolite concentrations increased 6h after capture and handling only and remained high for 24h; corticosterone returned to baseline levels after 48 h and remained low at 72 h post capture and handling. Corticosterone concentrations in toads subjected to toe-clipping increased at 6h to significantly higher concentrations than after capture and handling only, then decreased more slowly than after capture and handling, and were still elevated (approximately double basal level) 72 h after toe-clipping. Testosterone did not change significantly after capture and handling only, whereas after toe-clipping testosterone decreased at 6h and remained low at 72 h. There were weak short-term effects of toe-clipping compared with capture and handling only on white blood cell proportions. We have clearly shown that toe-clipping is a distinctly stronger stressor than capture and handling alone. This indicates that there is an ethical cost of toe-clipping, and this should be considered when planning studies of amphibians. Copyright © 2011 Elsevier Inc. All rights reserved.

Determination of Optimum Cross-section for Oran Highway Revetment

NASA Astrophysics Data System (ADS)

Sogut, E.; Velioglu, D.; Guler, I.

2016-12-01

Revetments are shore parallel, sloping coastal structures which are built to provide protection from the negative effects of the sea. The revetment mentioned in this study is located in the City of Oran, Algeria and is currently under construction. This study investigates the determination of the optimum revetment cross section for Oran highway, considering both the hydraulic stability of the revetment and economy. The existence of cliffs in the region and the settlement of the City of Oran created a necessity to re-align Oran highway; therefore, it was shifted towards the Gulf of Oran. Approximately 1 km of the highway is to be constructed on the Mediterranean Sea due to the new alignment. In order to protect the sea side of the road from the adverse effects of the sea, a revetment was designed. The proposed cross section had an armour layer composed of 23 tons of antifer units and regular placement of armour units was recommended. In order to check the hydraulic stability of the proposed section, physical model tests were performed in the laboratory of LEM (Laboratoire d'Etudes Maritimes) in Algeria, using the pre-determined design wave conditions. The physical model tests revealed that the trunk of the revetment was totaly damaged. Accordingly, the proposed section was found insufficient and certain modifications were required. The first modification was made in the arrangement of armour units, changing them from regular to irregular. After testing the new cross section, it was observed that the revetment was vulnerable to breaking wave attack due to the toe geometry and thus the toe of the revetment had to be re-shaped. Therefore, the second option was to reduce the toe elevation. It was observed that even though the revetment trunk was safe, the damage in the toe was not in acceptable limits. The new cross section was found insufficient and as the final option, the weight of the antifer units used in the armour layer was increased, the toe length of the structure was increased and the size of the armour units in the toe was decreased. After the modifications, the new section was tested physically and it was selected as the most optimum option.

Quantifying skin motion artifact error of the hindfoot and forefoot marker clusters with the optical tracking of a multi-segment foot model using single-plane fluoroscopy.

PubMed

Shultz, R; Kedgley, A E; Jenkyn, T R

2011-05-01

The trajectories of skin-mounted markers tracked with optical motion capture are assumed to be an adequate representation of the underlying bone motions. However, it is well known that soft tissue artifact (STA) exists between marker and bone. This study quantifies the STA associated with the hindfoot and midfoot marker clusters of a multi-segment foot model. To quantify STA of the hindfoot and midfoot marker clusters with respect to the calcaneus and navicular respectively, fluoroscopic images were collected on 27 subjects during four quasi-static positions, (1) quiet standing (non-weight bearing), (2) at heel strike (weight-bearing), (3) at midstance (weight-bearing) and (4) at toe-off (weight-bearing). The translation and rotation components of STA were calculated in the sagittal plane. Translational STA at the calcaneus varied from 5.9±7.3mm at heel-strike to 12.1±0.3mm at toe-off. For the navicular the translational STA ranged from 7.6±7.6mm at heel strike to 16.4±16.7mm at toe-off. Rotational STA was relatively smaller for both bones at all foot positions. For the calcaneus they varied between 0.1±2.2° at heel-strike to 0.2±0.6° at toe-off. For the navicular, the rotational STA ranged from 0.6±0.9° at heel-strike to 0.7±0.7° at toe-off. The largest translational STA found in this study (16mm for the navicular) was smaller than those reported in the literature for the thigh and the lower leg, but was larger than the STA of individual spherical markers affixed to the foot. The largest errors occurred at toe-off position for all subjects for both the hindfoot and midfoot clusters. Future studies are recommended to quantify true three-dimensional STA of the entire foot during gait. Copyright © 2011. Published by Elsevier B.V.

Linking clinical measurements and kinematic gait patterns of toe-walking using fuzzy decision trees.

PubMed

Armand, Stéphane; Watelain, Eric; Roux, Emmanuel; Mercier, Moïse; Lepoutre, François-Xavier

2007-03-01

Toe-walking is one of the most prevalent gait deviations and has been linked to many diseases. Three major ankle kinematic patterns have been identified in toe-walkers, but the relationships between the causes of toe-walking and these patterns remain unknown. This study aims to identify these relationships. Clearly, such knowledge would increase our understanding of this gait deviation, and could help clinicians plan treatment. The large quantity of data provided by gait analysis often makes interpretation a difficult task. Artificial intelligence techniques were used in this study to facilitate interpretation as well as to decrease subjective interpretation. Of the 716 limbs evaluated, 240 showed signs of toe-walking and met inclusion criteria. The ankle kinematic pattern of the evaluated limbs during gait was assigned to one of three toe-walking pattern groups to build the training data set. Toe-walker clinical measurements (range of movement, muscle spasticity and muscle strength) were coded in fuzzy modalities, and fuzzy decision trees were induced to create intelligible rules allowing toe-walkers to be assigned to one of the three groups. A stratified 10-fold cross validation situated the classification accuracy at 81%. Twelve rules depicting the causes of toe-walking were selected, discussed and characterized using kinematic, kinetic and EMG charts. This study proposes an original approach to linking the possible causes of toe-walking with gait patterns.

Early reduction in toe flexor strength is associated with physical activity in elderly men

PubMed Central

Suwa, Masataka; Imoto, Takayuki; Kida, Akira; Yokochi, Takashi

2016-01-01

[Purpose] To compare the toe flexor, hand grip and knee extensor strengths of young and elderly men, and to examine the association between toe flexor strength and physical activity or inactivity levels. [Subjects and Methods] Young (n=155, 18–23 years) and elderly (n=60, 65–88 years) men participated in this study. Toe flexor, hand grip, and knee extensor strength were measured. Physical activity (time spent standing/walking per day) and inactivity (time spent sitting per day) were assessed using a self-administered questionnaire. [Results] Toe flexor, hand grip, and knee extensor strength of the elderly men were significantly lower than those of the young men. Standing/walking and sitting times of the elderly men were lower than those of the young men. Toe flexor strength correlated with hand grip and knee extensor strength in both groups. In elderly men, toe flexor strength correlated with standing/walking time. In comparison to the young men’s mean values, toe flexor strength was significantly lower than knee extensor and hand grip strength in the elderly group. [Conclusion] The results suggest that age-related reduction in toe flexor strength is greater than those of hand grip and knee extensor strengths. An early loss of toe flexor strength is likely associated with reduced physical activity in elderly men. PMID:27313353

Risks to Navigation at the Matagorda Ship Channel Entrance, Texas, Phase 2: Evaluation of Significant Risk Factors

DTIC Science & Technology

2011-08-01

jetties are deteriorating. As a result of this deterioration and lowered beach and dunes adjacent to the jetties, there are overwash occurrences during...the toe . An example slope stability analysis is presented in Figure 51. This figure shows a typical cross section or model properties (soil layers...depth caused by the ship passage. Any area of influence will be localized and, in light of a critical gradient analysis, near- toe scouring effects

21 CFR 888.3720 - Toe joint polymer constrained prosthesis.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Toe joint polymer constrained prosthesis. 888.3720... (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3720 Toe joint polymer constrained prosthesis. (a) Identification. A toe joint polymer constrained prosthesis is a device made of silicone...

21 CFR 888.3720 - Toe joint polymer constrained prosthesis.

Code of Federal Regulations, 2011 CFR

2011-04-01

... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Toe joint polymer constrained prosthesis. 888.3720... (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3720 Toe joint polymer constrained prosthesis. (a) Identification. A toe joint polymer constrained prosthesis is a device made of silicone...

21 CFR 888.3720 - Toe joint polymer constrained prosthesis.

Code of Federal Regulations, 2013 CFR

2013-04-01

... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Toe joint polymer constrained prosthesis. 888.3720... (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3720 Toe joint polymer constrained prosthesis. (a) Identification. A toe joint polymer constrained prosthesis is a device made of silicone...

21 CFR 888.3720 - Toe joint polymer constrained prosthesis.

Code of Federal Regulations, 2012 CFR

2012-04-01

... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Toe joint polymer constrained prosthesis. 888.3720... (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3720 Toe joint polymer constrained prosthesis. (a) Identification. A toe joint polymer constrained prosthesis is a device made of silicone...

21 CFR 888.3720 - Toe joint polymer constrained prosthesis.

Code of Federal Regulations, 2014 CFR

2014-04-01

... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Toe joint polymer constrained prosthesis. 888.3720... (CONTINUED) MEDICAL DEVICES ORTHOPEDIC DEVICES Prosthetic Devices § 888.3720 Toe joint polymer constrained prosthesis. (a) Identification. A toe joint polymer constrained prosthesis is a device made of silicone...

Understanding Variability in Beach Slope to Improve Forecasts of Storm-induced Water Levels

NASA Astrophysics Data System (ADS)

Doran, K. S.; Stockdon, H. F.; Long, J.

2014-12-01

The National Assessment of Hurricane-Induced Coastal Erosion Hazards combines measurements of beach morphology with storm hydrodynamics to produce forecasts of coastal change during storms for the Gulf of Mexico and Atlantic coastlines of the United States. Wave-induced water levels are estimated using modeled offshore wave height and period and measured beach slope (from dune toe to shoreline) through the empirical parameterization of Stockdon et al. (2006). Spatial and temporal variability in beach slope leads to corresponding variability in predicted wave setup and swash. Seasonal and storm-induced changes in beach slope can lead to differences on the order of a meter in wave runup elevation, making accurate specification of this parameter essential to skillful forecasts of coastal change. Spatial variation in beach slope is accounted for through alongshore averaging, but temporal variability in beach slope is not included in the final computation of the likelihood of coastal change. Additionally, input morphology may be years old and potentially very different than the conditions present during forecast storm. In order to improve our forecasts of hurricane-induced coastal erosion hazards, the temporal variability of beach slope must be included in the final uncertainty of modeled wave-induced water levels. Frequently collected field measurements of lidar-based beach morphology are examined for study sites in Duck, North Carolina, Treasure Island, Florida, Assateague Island, Virginia, and Dauphin Island, Alabama, with some records extending over a period of 15 years. Understanding the variability of slopes at these sites will help provide estimates of associated water level uncertainty which can then be applied to other areas where lidar observations are infrequent, and improve the overall skill of future forecasts of storm-induced coastal change. Stockdon, H. F., Holman, R. A., Howd, P. A., and Sallenger Jr, A. H. (2006). Empirical parameterization of setup,swash, and runup. Coastal engineering, 53(7), 573-588.

Whole-body MRI assessment of disease activity and structural damage in rheumatoid arthritis: first step towards an MRI joint count.

PubMed

Axelsen, Mette Bjørndal; Eshed, Iris; Duer-Jensen, Anne; Møller, Jakob M; Pedersen, Susanne Juhl; Østergaard, Mikkel

2014-05-01

The aim of this study was to investigate the ability of whole-body MRI (WBMRI) to visualize inflammation [synovitis, bone marrow oedema (BME) and enthesitis] and structural damage in patients with RA. The 3T WBMR images were acquired in a head-to-toe scan in 20 patients with RA and at least one swollen or tender joint. Short Tau Inversion Recovery and pre- and post-contrast T1-weighted images were evaluated for readability and the presence/absence of inflammation (synovitis, BME and enthesitis) and structural damage (erosions and fat infiltrations) in 76 peripheral joints, 30 entheseal sites and in the spine. The readability was >70% for all individual joints, except for the most peripheral joints of the hands and feet. Synovitis was most frequent in the wrist, first tarsometatarsal, first CMC joints and glenohumeral joints (67-61%); BME in the wrist, CMC, acromioclavicular and glenohumeral joints (45-35%) and erosions in the wrist, MTP and CMC joints (19-16%). Enthesitis at ≥ 1 site was registered in 16 patients. BME was frequently seen in the cervical (20%) but not the thoracic and lumbar spine, while fat infiltrations and erosions were rare. The intrareader agreement was high (85-100%) for all pathologies. The agreement between WBMRI and clinical findings was low. Peripheral and axial inflammation and structural damage at joints and entheses was frequently identified by WBMRI, and more frequently than by clinical examination. WBMRI is a promising tool for evaluation of the total inflammatory load of inflammation (an MRI joint count) and structural damage in RA patients.

Kinematic Gait Changes Following Serial Casting and Bracing to Treat Toe Walking in a Child With Autism.

PubMed

Barkocy, Marybeth; Dexter, James; Petranovich, Colleen

2017-07-01

To evaluate the effectiveness of serial casting in a child with autism spectrum disorder (ASD) exhibiting a toe-walking gait pattern with equinus contractures. Although many children with ASD toe walk, little research on physical therapy interventions exists for this population. Serial casting has been validated for use in idiopathic toe walking to increase passive dorsiflexion and improve gait, but not for toe walking in children with ASD. Serial casting followed by ankle-foot orthosis use was implemented to treat a child with ASD who had an obligatory equinus gait pattern. Gait analysis supported improvements in kinematic, spatial, and temporal parameters of gait, and the child maintained a consistent heel-toe gait at 2-year follow-up. STATEMENT OF CONCLUSION AND RECOMMENDATIONS FOR CLINICAL PRACTICE:: Serial casting followed by ankle-foot orthosis use is a viable treatment option for toe walking in children with ASD.

Evaluating the impact of virtualization characteristics on SaaS adoption

NASA Astrophysics Data System (ADS)

Tomás, Sara; Thomas, Manoj; Oliveira, Tiago

2018-03-01

Software as a service (SaaS) is a service model in which the applications are accessible from various client devices through internet. Several studies report possible factors driving the adoption of SaaS but none have considered the perception of the SaaS features and the organization's context. We propose an integrated research model that combines the process virtualization theory (PVT), the technology-organization-environment (TOE) framework and the institutional theory (INT). PVT seeks to explain whether processes are suitable for migration into virtual environments via an information technology-based mechanism as SaaS. The TOE framework seeks to explain the effects of the intra-organizational factors, while INT seeks to explain the effects of the inter-organizational factors on the technology adoption. This research addresses a gap in the SaaS adoption literature by studying the internal perception of the technical features of SaaS and technology, organization, and environment perspectives. Additionally, the integration of PVT, the TOE framework, and INT contributes to the information system (IS) discipline, deepening the applicability and strengths of these theories.

Immediate toe-to-hand transfer in acute hand injuries: overall results, compared with results for elective cases.

PubMed

Woo, Sang-Hyun; Kim, Joo-Sung; Seul, Jung-Hyun

2004-03-01

In the past 5 years, 25 mutilated digits were reconstructed with immediate toe-to-hand transfers after acute hand injuries, for 21 patients. The overall results of the immediate toe-to-hand transfers were evaluated and compared with the results of 65 elective procedures performed during the same period by the same surgeon. There were 15 cases of great toe-to-hand transfer for thumb reconstruction, two cases of second toe transfer for index finger reconstruction, and four cases of simultaneous two-toe transfer for reconstruction of multiple-digit amputations. Two cases (two of 25 cases, 8 percent) were successfully salvaged with emergency reexploration. The incidences of emergency reexploration and postoperative infection were not significantly different from those for elective toe-to-hand transfer cases. The duration of industrial insurance coverage was much shorter than for elective cases, averaging 225 days (p < 0.001). Approximately 44 percent of the patients maintained their original jobs after immediate toe-to-hand transfer. The subjective satisfaction self-assessment scores of aesthetic appearance and function for the newly reconstructed thumb averaged 80 and 88 (of a total score of 100), respectively. Although satisfaction was lower than for elective reconstruction (p < 0.001), it was higher than for reconstruction of other digits. The donor-site appearance after great toe harvesting was mostly unsatisfactory. Immediate toe-to-hand transfer provides many advantages over the elective procedure in acute hand injuries, including single-stage reconstruction, shortened convalescence, early return to work, and socioeconomic efficiency. Because there were no significant differences in the success rates, frequencies of complications, or ultimate functional results, immediate toe-to-hand transfer is a safe and reliable procedure that is indicated for specific cases of acute digital amputation.

Retrograde tracing and toe spreading after experimental autologous nerve transplantation and crush injury of the sciatic nerve: a descriptive methodological study.

PubMed

van Neerven, Sabien Ga; Bozkurt, Ahmet; O'Dey, Dan Mon; Scheffel, Juliane; Boecker, Arne H; Stromps, Jan-Philipp; Dunda, Sebastian; Brook, Gary A; Pallua, Norbert

2012-04-30

Evaluation of functional and structural recovery after peripheral nerve injury is crucial to determine the therapeutic effect of a nerve repair strategy. In the present study, we examined the relationship between the structural evaluation of regeneration by means of retrograde tracing and the functional analysis of toe spreading. Two standardized rat sciatic nerve injury models were used to address this relationship. As such, animals received either a 2 cm sciatic nerve defect (neurotmesis) followed by autologous nerve transplantation (ANT animals) or a crush injury with spontaneous recovery (axonotmesis; CI animals). Functional recovery of toe spreading was observed over an observation period of 84 days. In contrast to CI animals, ANT animals did not reach pre-surgical levels of toe spreading. After the observation period, the lipophilic dye DiI was applied to label sensory and motor neurons in dorsal root ganglia (DRG; sensory neurons) and spinal cord (motor neurons), respectively. No statistical difference in motor or sensory neuron counts could be detected between ANT and CI animals.In the present study we could indicate that there was no direct relationship between functional recovery (toe spreading) measured by SSI and the number of labelled (motor and sensory) neurons evaluated by retrograde tracing. The present findings demonstrate that a multimodal approach with a variety of independent evaluation tools is essential to understand and estimate the therapeutic benefit of a nerve repair strategy.

An automated approach for extracting Barrier Island morphology from digital elevation models

NASA Astrophysics Data System (ADS)

Wernette, Phillipe; Houser, Chris; Bishop, Michael P.

2016-06-01

The response and recovery of a barrier island to extreme storms depends on the elevation of the dune base and crest, both of which can vary considerably alongshore and through time. Quantifying the response to and recovery from storms requires that we can first identify and differentiate the dune(s) from the beach and back-barrier, which in turn depends on accurate identification and delineation of the dune toe, crest and heel. The purpose of this paper is to introduce a multi-scale automated approach for extracting beach, dune (dune toe, dune crest and dune heel), and barrier island morphology. The automated approach introduced here extracts the shoreline and back-barrier shoreline based on elevation thresholds, and extracts the dune toe, dune crest and dune heel based on the average relative relief (RR) across multiple spatial scales of analysis. The multi-scale automated RR approach to extracting dune toe, dune crest, and dune heel based upon relative relief is more objective than traditional approaches because every pixel is analyzed across multiple computational scales and the identification of features is based on the calculated RR values. The RR approach out-performed contemporary approaches and represents a fast objective means to define important beach and dune features for predicting barrier island response to storms. The RR method also does not require that the dune toe, crest, or heel are spatially continuous, which is important because dune morphology is likely naturally variable alongshore.

Dynamic self-cleaning in gecko setae via digital hyperextension

PubMed Central

Hu, Shihao; Lopez, Stephanie; Niewiarowski, Peter H.; Xia, Zhenhai

2012-01-01

Gecko toe pads show strong adhesion on various surfaces yet remain remarkably clean around everyday contaminants. An understanding of how geckos clean their toe pads while being in motion is essential for the elucidation of animal behaviours as well as the design of biomimetic devices with optimal performance. Here, we test the self-cleaning of geckos during locomotion. We provide, to our knowledge, the first evidence that geckos clean their feet through a unique dynamic self-cleaning mechanism via digital hyperextension. When walking naturally with hyperextension, geckos shed dirt from their toes twice as fast as they would if walking without hyperextension, returning their feet to nearly 80 per cent of their original stickiness in only four steps. Our dynamic model predicts that when setae suddenly release from the attached substrate, they generate enough inertial force to dislodge dirt particles from the attached spatulae. The predicted cleaning force on dirt particles significantly increases when the dynamic effect is included. The extraordinary design of gecko toe pads perfectly combines dynamic self-cleaning with repeated attachment/detachment, making gecko feet sticky yet clean. This work thus provides a new mechanism to be considered for biomimetic design of highly reuseable and reliable dry adhesives and devices. PMID:22696482

Factors influencing survival and mark retention in postmetamorphic boreal chorus frogs

USGS Publications Warehouse

Swanson, Jennifer E; Bailey, Larissa L.; Muths, Erin L.; Funk, W. Chris

2013-01-01

The ability to track individual animals is crucial in many field studies and often requires applying marks to captured individuals. Toe clipping has historically been a standard marking method for wild amphibian populations, but more recent marking methods include visual implant elastomer and photo identification. Unfortunately, few studies have investigated the influence and effectiveness of marking methods for recently metamorphosed individuals and as a result little is known about this life-history phase for most amphibians. Our focus was to explore survival probabilities, mark retention, and mark migration in postmetamorphic Boreal Chorus Frogs (Psuedacris maculata) in a laboratory setting. One hundred forty-seven individuals were assigned randomly to two treatment groups or a control group. Frogs in the first treatment group were marked with visual implant elastomer, while frogs in the second treatment group were toe clipped. Growth and mortality were recorded for one year and resulting data were analyzed using known-fate models in Program MARK. Model selection results suggested that survival probabilities of frogs varied with time and showed some variation among marking treatments. We found that frogs with multiple toes clipped on the same foot had lower survival probabilities than individuals in other treatments, but individuals can be marked by clipping a single toe on two different feet without any mark loss or negative survival effects. Individuals treated with visual implant elastomer had a mark migration rate of 4% and mark loss rate of 6%, and also showed very little negative survival impacts relative to control individuals.

Mechanisms controlling rock coast evolution in paraglacial landscapes - examples from Arctic, Antarctic and Scandinavian regions

NASA Astrophysics Data System (ADS)

Strzelecki, M. C.; Lim, M.; Kasprzek, M.; Swirad, Z. M.; Rachlewicz, G.; Migoń, P.; Pawlowski, L.; Jaskolski, M.

2017-12-01

This paper presents the results of an investigation into the processes controlling development of paraglacial rock coast systems in Hornsund, Svalbard, Admiralty Bay, South Shetland Islands and Gotland Island, Scandinavia. A suite of nested geomorphological and geophysical methods have been applied to characterize the functioning of rock cliffs, shore platforms and stacks influenced by lithological control and geomorphic processes driven by paraglacial coast environments - both in glaciated and deglaciated study sites. Rock hardness, quantified by Schmidt hammer rebound tests, demonstrate strong spatial control on the degree of rock weathering (rock strength) along studied rock coasts. Elevation controlled geomorphic zones are identified and linked to distinct processes and mechanisms, transitioning from peak hardness values at the icefoot/sea-ice through the wave and storm dominated scour zones to the lowest values on the cliff tops, where the effects of periglacial weathering dominate. Observations of rock surface change using a traversing micro-erosion meter (TMEM) indicate that significant changes in erosion rates occur at the junction between shore platform and the cliff toe, where rock erosion is facilitated by frequent wetting and drying and operation of nivation and sea ice processes (formation and melting of snow patches and icefoot complexes). Electrical resistivity tomography (ERT) surveys have been used to investigate frozen ground control on rock coast dynamics and reveal the strong interaction with marine processes in polar coastal settings. In Gotland, Scandinavia the morphology of rocky coastal landforms (rauks) bear traces of numerous environmental changes that occurred in Baltic region over the Holocene including salinity, temperature, ice-cover/storminess and relative sea-level. The results are synthesised to propose a new conceptual model of paraglacial rock coast systems, with the aim of contributing towards a unifying concept of cold region landscape evolution and providing direction for future research regarding the state of rock coasts in deglaciated regions. This is a contribution to National Science Centre projects: RAUK (2016/21/D/ST10/01976) and POROCO (UMO-2013/11/B/ST10/00283).

Nonvascularized toe phalangeal transfer and distraction lengthening for symbrachydactyly.

PubMed

Patterson, Ryan W; Seitz, William H

2010-04-01

Symbrachydactyly describes a spectrum of congenital hand differences consisting of digital loss resulting in fused short fingers. As the principles for distraction lengthening have evolved, the technique of nonvascularized toe phalangeal transfer to the hand with shortened digits has provided patients with improved outcomes. Nonvascularized toe phalanx to hand transplant with distraction lengthening restores functional length to a skeletally deficient, poorly functioning hand while maintaining an overlying layer of vascular and sensate tissue. The primary goal is improvement of digital length to enhance mechanical advantage and prehension. We describe the technique of nonvascularized toe phalangeal transfer and distraction lengthening for symbrachydactyly, including the following steps: nonvascularized proximal toe phalanx harvest, toe phalanx transfer to hand, pin placement, osteotomy, and closure.

Accuracy and reproducibility of aortic annular measurements obtained from echocardiographic 3D manual and semi-automated software analyses in patients referred for transcatheter aortic valve implantation: implication for prosthesis size selection.

PubMed

Stella, Stefano; Italia, Leonardo; Geremia, Giulia; Rosa, Isabella; Ancona, Francesco; Marini, Claudia; Capogrosso, Cristina; Giglio, Manuela; Montorfano, Matteo; Latib, Azeem; Margonato, Alberto; Colombo, Antonio; Agricola, Eustachio

2018-02-06

A 3D transoesophageal echocardiography (3D-TOE) reconstruction tool has recently been introduced. The system automatically configures a geometric model of the aortic root and performs quantitative analysis of these structures. We compared the measurements of the aortic annulus (AA) obtained by semi-automated 3D-TOE quantitative software and manual analysis vs. multislice computed tomography (MSCT) ones. One hundred and seventy-five patients (mean age 81.3 ± 6.3 years, 77 men) who underwent both MSCT and 3D-TOE for annulus assessment before transcatheter aortic valve implantation were analysed. Hypothetical prosthetic valve sizing was evaluated using the 3D manual, semi-automated measurements using manufacturer-recommended CT-based sizing algorithm as gold standard. Good correlation between 3D-TOE methods vs. MSCT measurements was found, but the semi-automated analysis demonstrated slightly better correlations for AA major diameter (r = 0.89), perimeter (r = 0.89), and area (r = 0.85) (all P < 0.0001) than manual one. Both 3D methods underestimated the MSCT measurements, but semi-automated measurements showed narrower limits of agreement and lesser bias than manual measurements for most of AA parameters. On average, 3D-TOE semi-automated major diameter, area, and perimeter underestimated the respective MSCT measurements by 7.4%, 3.5%, and 4.4%, respectively, whereas minor diameter was overestimated by 0.3%. Moderate agreement for valve sizing for both 3D-TOE techniques was found: Kappa agreement 0.5 for both semi-automated and manual analysis. Interobserver and intraobserver agreements for the AA measurements were excellent for both techniques (intraclass correlation coefficients for all parameters >0.80). The 3D-TOE semi-automated analysis of AA is feasible and reliable and can be used in clinical practice as an alternative to MSCT for AA assessment. Published on behalf of the European Society of Cardiology. All rights reserved. © The Author(s) 2018. For permissions, please email: journals.permissions@oup.com.

Relationship between early motor milestones and severity of restricted and repetitive behaviors in children and adolescents with autism spectrum disorder.

PubMed

Uljarević, Mirko; Hedley, Darren; Alvares, Gail A; Varcin, Kandice J; Whitehouse, Andrew J O

2017-06-01

This study explored the relationships between the later age of achievement of early motor milestones, current motor atypicalities (toe walking), and the severity of restricted and repetitive behaviors (RRBs) in individuals with autism spectrum disorder (ASD). Parents of 147 children and adolescents with ASD (M age  = 8.09 years, SD = 4.28; 119 males) completed an early developmental milestones questionnaire and the Social Responsiveness Scale as a measure of Insistence on Sameness (IS) and Repetitive Mannerisms (RM). Two hierarchical regression analyses were conducted to test whether RM and IS behaviors were predicted by early motor milestones, or current toe walking. The final model predicting RM accounted for 15% of the variance (F = 3.02, p = .009), with toe walking as a unique and independent predictor of RM scores (t = 3.568, p = .001). The final model predicting IS accounted for 19.1% of variance in IS scores (F = 4.045, p = .001), with chronological age (CA) (t = 2.92, p = .004), age when first standing (t = 2.09, p = .038), and toe walking (t = 2.53, p = .013) as unique independent predictors. Toe walking (t = 2.4, p = .018) and age when first sitting (t = 2.08, p = .04) predicted the severity of RRBs on the Autism Diagnostic Observation Schedule (F = 2.334, p = .036). Our study replicates previous findings on the relationship between concurrent motor impairments and RRBs, and provides the first evidence for the association between RRBs and age of attainment of early motor milestones. Autism Res 2017. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. Autism Res 2017, 10: 1163-1168. © 2017 International Society for Autism Research, Wiley Periodicals, Inc. © 2017 International Society for Autism Research, Wiley Periodicals, Inc.

Modified toe pulp fillet flap coverage: Better wound healing and satisfactory length preservation.

PubMed

Baek, Sang Oon; Suh, Hyo Wan; Lee, Jun Yong

2018-01-01

Amputation is commonly performed for toe necrosis secondary to peripheral vascular diseases, such as diabetes mellitus. When amputating a necrotic toe, preservation of the bony structure is important for preventing the collapse of adjacent digits into the amputated space. However, in the popular terminal Syme's amputation technique, partial amputation of the distal phalanx could cause increased tension on the wound margin. Herein, we introduce a new way to resect sufficient bony structure while maintaining the normal length, based on a morphological analysis of the toes. Unlike the pulp of the finger in the distal phalanx, the toe has abundant teardrop-shaped pulp tissue. The ratio of the vertical length to the longitudinal length in the distal phalanx was compared between the toes and fingers. Amputation was performed at the proximal interphalangeal joint level. Then, a mobilizable pulp flap was rotated 90° cephalad to replace the distal soft tissue defect. This modified toe fillet flap was performed in 5 patients. The toe pulp was found to have a vertically oriented morphology compared to that of the fingers, enabling length preservation through cephalad rotation. All defects were successfully covered without marginal ischemia. While conventional toe fillet flap coverage focuses on the principle of length preservation as the first priority, our modified method takes both wound healing and length into account. The fattiest part of the pulp is advanced to the toe tip, providing a cushioning effect and enough length to substitute for phalangeal bone loss. Our modified method led to satisfactory functional and aesthetic outcomes.

A Midterm Review of Lesser Toe Arthrodesis With an Intramedullary Implant.

PubMed

Harmer, James Lee; Wilkinson, Anthony; Maher, Anthony John

2017-10-01

Lesser toe deformities are one of the most common conditions encountered by podiatric surgeons. When conservative treatments fail surgical correction is indicated. Many surgical options have been described to address the complex nature of these deformities but no perfect solution has been reported to date. However, with the continued advancement of internal fixation technology, interphalangeal joint (IPJ) arthrodesis with an intramedullary implant may be a good option. This retrospective study presents patient reported outcomes and complications at 6 months and 3 years following lesser toe proximal interphalangeal joint (PIPJ) arthrodesis with a polyketone intrameduallary implant (Toe Grip, Orthosolutions, UK). Between September 2011 and November 2012, a total of 38 patients attended for second toe PIPJ arthrodesis by means of the Toe Grip device. At 6 months postoperation, 94.7% of patients and at 3 years postoperation, 92.8% of patients felt that their original complaint was better or much better. Health-related quality of life scores continued to improve overtime as measured by the Manchester Oxford Foot Questionnaire. Complications were generally observational and asymptomatic. The most common complications were floating toes (17.8%), mallet deformities (14.2%), metatarsalgia (17.8%), and transverse plane deformity of the toe (10.7%). This study demonstrates excellent patient-eported outcomes with minimal symptomatic complications making the "Toe Grip" implant a safe and effective alternative fixation device for IPJ arthrodesis when dealing with painful digital deformities. Therapeutic, Level IV: Case series.

Effect of toe extension on EMG of triceps surae muscles during isometric dorsiflexion.

PubMed

Siddiqi, Ariba; Arjunan, Sridhar P; Kumar, Dinesh

2016-12-01

The protocol for estimating force of contraction by triceps surae (TS) muscles requires the immobilization of the ankle during dorsiflexion and plantar flexion. However, large variability in the results has been observed. To identify the cause of this variability, experiments were conducted where ankle dorsiflexion force and electromyogram (EMG) of the TS were recorded under two conditions: (i) toes were strapped and (ii) toes were unstrapped, with all other conditions such as immobilization of the ankle remaining unchanged. The root mean square (RMS) of the EMG and the force were analyzed and one-tail Student's t-test was performed for significance between the two conditions. The RMS of the EMG from TS muscles was found to be significantly higher (~55%) during dorsiflexion with toes unstrapped compared with when the toes were strapped. The torque corresponding to dorsiflexion was also higher with toes unstrapped. Our study has shown that it is important to strap the toes when measuring the torque at the ankle and EMG of the TS muscles.

Long-term responses of rainforest erosional systems at different spatial scales to selective logging and climatic change.

PubMed

Walsh, R P D; Bidin, K; Blake, W H; Chappell, N A; Clarke, M A; Douglas, I; Ghazali, R; Sayer, A M; Suhaimi, J; Tych, W; Annammala, K V

2011-11-27

Long-term (21-30 years) erosional responses of rainforest terrain in the Upper Segama catchment, Sabah, to selective logging are assessed at slope, small and large catchment scales. In the 0.44 km(2) Baru catchment, slope erosion measurements over 1990-2010 and sediment fingerprinting indicate that sediment sources 21 years after logging in 1989 are mainly road-linked, including fresh landslips and gullying of scars and toe deposits of 1994-1996 landslides. Analysis and modelling of 5-15 min stream-suspended sediment and discharge data demonstrate a reduction in storm-sediment response between 1996 and 2009, but not yet to pre-logging levels. An unmixing model using bed-sediment geochemical data indicates that 49 per cent of the 216 t km(-2) a(-1) 2009 sediment yield comes from 10 per cent of its area affected by road-linked landslides. Fallout (210)Pb and (137)Cs values from a lateral bench core indicate that sedimentation rates in the 721 km(2) Upper Segama catchment less than doubled with initially highly selective, low-slope logging in the 1980s, but rose 7-13 times when steep terrain was logged in 1992-1993 and 1999-2000. The need to keep steeplands under forest is emphasized if landsliding associated with current and predicted rises in extreme rainstorm magnitude-frequency is to be reduced in scale.

Modeling the spatial distribution of landslide-prone colluvium and shallow groundwater on hillslopes of Seattle, WA

USGS Publications Warehouse

Schulz, W.H.; Lidke, D.J.; Godt, J.W.

2008-01-01

Landslides in partially saturated colluvium on Seattle, WA, hillslopes have resulted in property damage and human casualties. We developed statistical models of colluvium and shallow-groundwater distributions to aid landslide hazard assessments. The models were developed using a geographic information system, digital geologic maps, digital topography, subsurface exploration results, the groundwater flow modeling software VS2DI and regression analyses. Input to the colluvium model includes slope, distance to a hillslope-crest escarpment, and escarpment slope and height. We developed different statistical relations for thickness of colluvium on four landforms. Groundwater model input includes colluvium basal slope and distance from the Fraser aquifer. This distance was used to estimate hydraulic conductivity based on the assumption that addition of finer-grained material from down-section would result in lower conductivity. Colluvial groundwater is perched so we estimated its saturated thickness. We used VS2DI to establish relations between saturated thickness and the hydraulic conductivity and basal slope of the colluvium. We developed different statistical relations for three groundwater flow regimes. All model results were validated using observational data that were excluded from calibration. Eighty percent of colluvium thickness predictions were within 25% of observed values and 88% of saturated thickness predictions were within 20% of observed values. The models are based on conditions common to many areas, so our method can provide accurate results for similar regions; relations in our statistical models require calibration for new regions. Our results suggest that Seattle landslides occur in native deposits and colluvium, ultimately in response to surface-water erosion of hillstope toes. Regional groundwater conditions do not appear to strongly affect the general distribution of Seattle landslides; historical landslides were equally dispersed within and outside of the area potentially affected by regional groundwater conditions.

Hammertoe and Mallet Toe

MedlinePlus

... hammertoe and mallet toe may involve changing your footwear and wearing shoe inserts. If you have a ... linked to: Certain shoes. High-heeled shoes or footwear that's too tight in the toe box can ...

The Integrated Soil Erosion Risk Management Model of Central Java, Indonesia

NASA Astrophysics Data System (ADS)

Setiawan, M. A.; Stoetter, J.; Sartohadi, J.; Christanto, N.

2009-04-01

Many types of soil erosion modeling have been developed worldwide; each of models has its own advantage and assumption based on the originated area. Ironically, in the tropical countries where the rainfall intensity is higher than other area, the soil erosion problem gain less attention. As in Indonesia, due the inadequate supporting data and method to dealing with, the soil erosion management appears to be least prior in the policy decision. Hence, there is increasing necessity towards the initiation and integration of risk management model in the soil erosion, to prevent further land degradation problem in Indonesia. The main research objective is to generate a model which can analyze the dynamic system of soil erosion problem. This model will comprehensively consider four main aspects within the dynamic system analysis, i.e.: soil erosion rate modeling, the tolerable soil erosion rate, total soil erosion cost, and soil erosion management measures. The generating model will involve some sub-software i.e. the PC Raster to maintain the soil erosion modeling, Powersim Constructor Ver. 2.5 as the tool to analyze the dynamic system and Python Ver. 2.6.1 to build the main Graphical User Interface model. The first step addressed in this research is figuring the most appropriate soil erosion model to be applied in Indonesia based on landscape, climate, and data availability condition. This appropriate model must have the simplicity aspect in input data but still deal with the process based analysis. By using the soil erosion model result, the total soil erosion cost will be calculated both on-site and off-site effect. The total soil erosion cost will be stated in Rupiah (Indonesian currency) and Dollar. That total result is then used as one of input parameters for the tolerable soil erosion rate. Subsequently, the tolerable soil erosion rate decides whether the soil erosion rate has exceeded the allowed value or not. If the soil erosion rate has bigger value than the tolerable soil erosion rate, the soil erosion management will be applied base on cost and benefit analysis. The soil erosion management measures will conduct as decision maker of defining the best alternative soil conservation method in a certain area. Besides the engineering and theoretical methods, the local wisdom also will be taken into account in defining the alternative manners of soil erosion management. As a prototype, this integrated model will be generated and simulated in Serayu Watershed, Central Java, since this area has a serious issue in soil erosion problem mainly in the upper stream area (Dieng area). The extraordinary monoculture plantation (potatoes) and very intensive soil tillage without proper soil conservation method has accelerated the soil erosion and depleted the soil fertility. Based on the potatoes productivity data (kg/ha) from 1997-2007 showed that there was a declining trend line, approximately minus 8,2% every year. On the other hand the fertilizer and pesticide consumption in agricultural land are significantly increasing every year. In the same time, the high erosion rate causes serious sedimentation problem in lower stream. Those conditions can be used as study case in determining the element at risk of soil erosion and calculation method for the total soil erosion cost (on-site and off-site effect). Moreover, The Serayu Watershed consists of complex landforms which might have variation of soil erosion tolerable rate. In the future, this integrated model can obtain valuable basis data of the soil erosion hazard in spatial and temporal information including its total cost, the sustainability time of certain land or agriculture area, also the consequences price of applying certain agriculture or soil management. Since this model give result explicitly in spatial and temporal, this model can be used by the local authority to run the land use scenario in term of soil erosion impact before applied them in the real condition. In practice, such integrated model could give more understanding knowledge to the local people about the soil erosion, its processes, impacts, and how to manage that. Keywords: Risk assessment, soil erosion, dynamic system, environmental valuation

The effect of shoe toe box shape and volume on forefoot interdigital and plantar pressures in healthy females

PubMed Central

2013-01-01

Background Ill-fitting footwear can be detrimental to foot health with the forefoot being an area for most discomfort. Studies on footwear have primarily examined sports or orthopaedic prescription shoes and little is known about the effects that everyday flat shoes have on the forefoot. The aim of this study was to investigate the effect of toe box shape in a popular slip-on pump on dorsal and plantar pressures with particular interest around the forefoot in a healthy female population. Method A convenience sample of 27 female participants with no known foot pathologies was recruited. After assessment of foot size, plantar foot pressure and interdigital pressures were recorded for each of the 3 different toe box styles; round, square and pointed. Participants walked at a self-selected speed over a 10 m walkway whilst wearing each of the 3 styles of shoe and also whilst barefoot. Processed and analysed data extracted included peak pressure, time to peak pressure, contact time and pressure time integral. ANOVA and Freidman analysis was used to test for statistical significance. Results Shoes with a round toe showed least pressure around the medial aspect of the toes whilst the pointed shoe had least pressure on the lateral toes. Contact times for the plantar regions were not altered in any shoe condition yet contact around the medial aspect of the toes was highest in the pointed shoe. Conclusion This study highlights that the shape of the toe box in footwear can significantly influence the amount of pressure applied to the forefoot. Furthermore, the contours of the shoe also have an impact on the contact time and pressure time integral around the forefoot and also the peak plantar pressure in the toe region. The changes observed could be significant in the development of pathology in certain footwear toe box shapes. Consideration should be given to footwear design around the toe box to improve fit and reduce pressure. Further work is required to investigate the effect of toe box shape and volume on a pathological population with pressure related lesions. PMID:23886242

The effect of foot landing position on biomechanical risk factors associated with anterior cruciate ligament injury.

PubMed

Tran, Andrew A; Gatewood, Corey; Harris, Alex H S; Thompson, Julie A; Dragoo, Jason L

2016-12-01

Identification of biomechanical risk factors associated with anterior cruciate ligament (ACL) injury can facilitate injury prevention. The purpose of this study is to investigate the effects of three foot landing positions, "toe-in", "toe-out" and "neutral", on biomechanical risk factors for ACL injury in males and females. The authors hypothesize that 1) relative to neutral, the toe-in position increases the biomechanical risk factors for ACL injury, 2) the toe-out position decreases these biomechanical risk factors, and 3) compared to males, females demonstrate greater changes in lower extremity biomechanics with changes in foot landing position. Motion capture data on ten male and ten female volunteers aged 20-30 years (26.4 ± 2.50) were collected during double-leg jump landing activities. Subjects were asked to land on force plates and target one of three pre-templated foot landing positions: 0° ("neutral"), 30° internal rotation ("toe-in"), and 30° external rotation ("toe-out") along the axis of the anatomical sagittal plane. A mixed-effects ANOVA and pairwise Tukey post-hoc comparison were used to detect differences in kinematic and kinetic variables associated with biomechanical risk factors of ACL injury between the three foot landing positions. Relative to neutral, landing in the toe-in position increased peak hip adduction, knee internal rotation angles and moments (p < 0.01), and peak knee abduction angle (p < 0.001). Landing in the toe-in position also decreased peak hip flexion angle (p < 0.001) and knee flexion angle (p = 0.023). Landing in the toe-out position decreased peak hip adduction, knee abduction, and knee internal rotation angles (all p < 0.001). Male sex was associated with a smaller increase in hip adduction moment (p = 0.043) and knee internal rotation moment (p = 0.032) with toe-in landing position compared with female sex. Toe-in landing position exacerbates biomechanical risk factors associated with ACL injury, while toe-out landing position decreases these factors.

Biomechanical effects of a 2 suture-pass medial inter-implant mattress on transosseous-equivalent rotator cuff repair and considerations for a "technical efficiency ratio".

PubMed

Park, Maxwell C; Peterson, Alexander; Patton, John; McGarry, Michelle H; Park, Chong J; Lee, Thay Q

2014-03-01

Rotator cuff repair involving fewer tendon suture passes without compromising biomechanical performance would represent a technical advancement. An inter-implant "medial pulley-mattress" transosseous-equivalent (MP-TOE) repair requiring fewer tendon suture-passes was hypothesized to provide equivalent biomechanical characteristics compared to the control. In 6 human cadaveric shoulders, a transosseous-equivalent (TOE) repair (control) was performed utilizing 2 separate medial mattresses resulting in 4 tendon-bridging sutures. In 6 matched-pairs, 2 single-loaded anchors were used to create a medial inter-implant mattress construct (all sutures shuttled in 1 tendon pass per anchor)-after knot-tying, the same tendon-bridging pattern as the control was created. A materials testing machine cyclically loaded each repair from 10-180 N for 30 cycles; each repair subsequently underwent failure testing. Gap and strain were measured with a video digitizing system. A "technical efficiency ratio" (TER) was defined as: (#knots + #suture passes + #suture limbs)/#fixation points. Cyclic and failure testing demonstrated no significant differences between constructs. Gap formation at cycle 30 was 5.3 ± 0.8 mm (TOE) and 5.0 ± 0.3 mm (MP-TOE) (P = .62). Cycle 30 anterior strain values were -16.0 ± 7.3% (TOE) and -15.8 ± 6.6% (MP-TOE) (P = .99). Yield loads were 208.7 ± 2.7 N (TOE) and 204.0 ± 1.3 N (MP-TOE) (P = .17). Mode of failure demonstrated less tendon cut-out with the MP-TOE repair. The MP-TOE repair has a TER of 2.0 vs 2.5 for the control. The MP-TOE repair requiring fewer tendon suture passes, yet creating an additional inter-implant mattress configuration, is biomechanically equivalent to the original TOE technique, and may limit failure with improved medial load-sharing capacity. A TER may help quantify technical ease and help standardize comparisons between repair techniques. Copyright © 2014 Journal of Shoulder and Elbow Surgery Board of Trustees. All rights reserved.

Determination of Optimum Cross-section for Oran Highway Revetment

NASA Astrophysics Data System (ADS)

Velioglu, Deniz; Sogut, Erdinc; Guler, Isikhan

2017-04-01

Revetments are shore parallel, sloping coastal structures which are built to provide protection from the negative effects of the sea. The revetment mentioned in this study is located in the City of Oran, Algeria and is currently under construction. This study investigates the determination of the optimum revetment cross section for Oran highway, considering both the hydraulic stability of the revetment and economy. The existence of cliffs in the region and the settlement of the City of Oran created a necessity to re-align Oran highway; therefore, it was shifted towards the Gulf of Oran. Approximately 1 km of the highway is to be constructed on the Mediterranean Sea due to the new alignment. In order to protect the sea side of the road from the adverse effects of the sea, a revetment was designed. The proposed cross section had an armour layer composed of 23 tons of antifer units and regular placement of armour units was recommended. In order to check the hydraulic stability of the proposed section, physical model tests were performed in the laboratory of LEM (Laboratoire d'Etudes Maritimes) in Algeria, using the pre-determined design wave conditions. The physical model tests revealed that the trunk of the revetment was totaly damaged. Accordingly, the proposed section was found insufficient and certain modifications were required. The first modification was made in the arrangement of armour units, changing them from regular to irregular. After testing the new cross section, it was observed that the revetment was vulnerable to breaking wave attack due to the toe geometry and thus the toe of the revetment had to be re-shaped. Therefore, the second option was to reduce the toe elevation. It was observed that even though the revetment trunk was safe, the damage in the toe was not in acceptable limits. The new cross section was found insufficient and as the final option, the weight of the antifer units used in the armour layer was increased, the toe length of the structure was increased and the size of the armour units in the toe was decreased. After the modifications, the new section was tested physically and it was selected as the most optimum option. Acknowledgements: Yuksel Proje Uluslararasi A.S. is acknowledged for its contributon to this study.

Sea-level rise impacts on seawater intrusion in coastal aquifers: Review and integration

NASA Astrophysics Data System (ADS)

Ketabchi, Hamed; Mahmoodzadeh, Davood; Ataie-Ashtiani, Behzad; Simmons, Craig T.

2016-04-01

Sea-level rise (SLR) influences groundwater hydraulics and in particular seawater intrusion (SWI) in many coastal aquifers. The quantification of the combined and relative impacts of influential factors on SWI has not previously been considered in coastal aquifers. In the present study, a systematic review of the available literature on this topic is first provided. Then, the potential remaining challenges are scrutinized. Open questions on the effects of more realistic complexities such as gradual SLR, parameter uncertainties, and the associated influences in decision-making models are issues requiring further investigation. We assess and quantify the seawater toe location under the impacts of SLR in combination with recharge rate variations, land-surface inundation (LSI) due to SLR, aquifer bed slope variation, and changing landward boundary conditions (LWBCs). This is the first study to include all of these factors in a single analysis framework. Both analytical and numerical models are used for these sensitivity assessments. It is demonstrated that (1) LSI caused by SLR has a significant incremental impact on the seawater toe location, especially in the flatter coasts and the flux-controlled (FC) LWBCs, however this impact is less than the reported orders of magnitude differences which were estimated using only analytical solutions; (2) LWBCs significantly influence the SLR impacts under almost all conditions considered in this study; (3) The main controlling factors of seawater toe location are the magnitudes of fresh groundwater discharge to sea and recharge rate. Regional freshwater flux entering from the landward boundary and the groundwater hydraulic gradient are the major contributors of fresh groundwater discharge to sea for both FC and head-controlled (HC) systems, respectively; (4) A larger response of the aquifer and larger seawater toe location changes are demonstrable for a larger ratio of the aquifer thickness to the aquifer length particularly in the HC systems; (5) The lowest sensitivity of seawater toe location is found for the density difference ratio of the seawater and freshwater, and also for the aquifer bed slope; (6) The early-time observations show seawater fingers below the inundated lands due to SLR which are diminished and ultimately extinguished; and (7) A less than 2% reversal effect on the seawater toe location after overshoot mechanism is observed in the transient simulations which suggests that this mechanism is an insignificant and impractical factor compared to other more significant factors.

3D Mechanical Models of Crustal Deformation and the Effect of Erosion on the Strain Pattern in SE Alaska

NASA Astrophysics Data System (ADS)

Barker, A. D.; Koons, P. O.; Upton, P.; Hallet, B.

2008-12-01

Employing 3D mechanical modeling to investigate the susceptibility of strain patterns to distinct erosion conditions we have identified a strong connection between surface erosion and strain localization and vertical motion of crustal material. The specific model geometry and boundary conditions are relevant to the dynamic St. Elias orogen of SE Alaska, but the general results and interpretations are universal. To illustrate the effect of erosion we compare results to a reference model without imposed erosion. We consider the crustal response to boundary conditions representing erosion scenarios: 1) regional erosion (~1 mm a-1 over a region ~600 km on a side) and 2) focused incision (~6 mm a-1 in valleys ~10 km wide and 50-100 km long). Whereas regional erosion mimics broader scale mass wasting and periglacial weathering, focused incision represents efficient erosion confined to valley systems similar to the massive Bering, Malaspina and Bagley glaciers of the St. Elias range. Using these boundary conditions we demonstrate significant localization of strain and crustal uplift beneath the sites of erosion. We also show the strain localization pattern adjusts to spatial shifts in erosion arising from substantial (order of 100km) glacial advance or retreat. The magnitude of the strain is higher in each erosion model compared to the reference model. The difference of the strain magnitude between erosion models and reference model depends on the location of the imposed erosion: crustal strain localize most when the forethrust daylights in the zone being eroded. Sustained focused erosion decreases the overall crustal strength beneath the site of erosion due to thinning of the strong brittle crust. Strain naturally concentrates within the weakened zone. Upward advection of warm crust causes further weakening and thereby leads to a tectonic aneurysm.

Safety and efficiency of the new micro-multiplane transoesophageal probe in paediatric cardiology.

PubMed

Hascoët, Sébastien; Peyre, Marianne; Hadeed, Khaled; Alacoque, Xavier; Chausseray, Gérald; Fesseau, Rose; Amadieu, Romain; Léobon, Bertrand; Berthomieu, Lionel; Dulac, Yves; Acar, Philippe

2014-01-01

Transoesophageal echocardiography (TOE) is feasible in neonates using a miniaturized probe, but is not widely used because of low imaging quality. To assess handling and imaging quality of a new release of a micro-TOE probe in children. Thirty-eight consecutive children, enrolled during February and May 2013, underwent TOE with the Philips S8-3t probe. Insertion, handling and image quality were assessed. The 38 children (aged 7days to 12years; weight 3.1-27kg) underwent 75 TOE (30 [40.0%] before cardiac surgery, 31 [41.3%] after cardiac surgery, 4 [5.3%] during a percutaneous procedure, 10 [13.3%] in the intensive care unit). Insertion of the micro-TOE probe was 'very easy' in 37/38 patients (97.4%). Handling was better in the lightest children (P=0.001). Image quality was mainly 'good' or 'very good', with no significant changes between preoperative and postoperative examinations or over time. Total scores (insertion, handling, image quality) were significantly better in the lightest children (P=0.02). Preoperative TOE did not provide additional information over transthoracic echocardiography. Postoperative TOE was useful to assess surgical results, but no residual lesions required extracorporeal circulation return. Micro-TOE was useful during the postoperative care of neonatal surgery with open breastbone to assess the surgical result and ventricular function. It was also useful to guide extracorporeal membrane oxygenation (ECMO) indication and withdrawal; and was a useful guide for percutaneous procedures. Micro-multiplane TOE is safe and efficient for use in neonates and children. This minimally invasive tool increases the impact of TOE in paediatric cardiology. Copyright © 2014. Published by Elsevier Masson SAS.

Long-term donor site morbidity after free nonvascularized toe phalangeal transfer.

PubMed

Garagnani, Lorenzo; Gibson, Marc; Smith, Paul J; Smith, Gillian D

2012-04-01

Free nonvascularized toe phalangeal transfer is an established surgical option for the reconstruction of hypoplastic digits. This study assessed long-term morbidity in the feet using this technique. We reviewed 40 children treated between 1991 and 2007 by free nonvascularized toe phalangeal transfer. The diagnosis was digital hypoplasia resulting from symbrachydactyly in 33 cases, constriction ring syndrome in 3 cases, thumb hypoplasia in 3 cases, and perinatal subclavian venous thrombosis in 1 case. The patients were followed up after surgery for a mean of 10 years (range, 3-19 y). The Oxford Ankle Foot Questionnaire was administered to patients and families to assess patient symptoms and patient and parental satisfaction. We assessed toe length ratio, the presence of visible deformity, and distal hypoplasia of the donor toes clinically and radiographically. Emotional problems related to foot appearance were common. We also found functional problems with footwear in some patients. All patients had floppy unstable toes with visible deformity. Increasing foot deformity was seen with growth, which led to deterioration in foot aesthetics, particularly where multiple donor toes had been harvested. We identified distal and middle phalangeal and metatarsal hypoplasia in the donor toes. Donor site morbidity for free toe phalangeal transfer is greater than previously documented. This should be considered during surgical decision making for reconstruction of hypoplastic digits. Preoperative counseling should include discussion regarding possible consequences of phalangeal harvest on donor toes and options for donor site reconstruction. Long-term follow-up of the donor site is essential to accurately assess results. Therapeutic III. Copyright © 2012 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Numerical Modelling and Prediction of Erosion Induced by Hydrodynamic Cavitation

NASA Astrophysics Data System (ADS)

Peters, A.; Lantermann, U.; el Moctar, O.

2015-12-01

The present work aims to predict cavitation erosion using a numerical flow solver together with a new developed erosion model. The erosion model is based on the hypothesis that collapses of single cavitation bubbles near solid boundaries form high velocity microjets, which cause sonic impacts with high pressure amplitudes damaging the surface. The erosion model uses information from a numerical Euler-Euler flow simulation to predict erosion sensitive areas and assess the erosion aggressiveness of the flow. The obtained numerical results were compared to experimental results from tests of an axisymmetric nozzle.

Toe Walking in Children

MedlinePlus

... walking sometimes can result from certain conditions, including cerebral palsy, muscular dystrophy and autism spectrum disorder. Symptoms Toe ... can prevent the heel from touching the ground. Cerebral palsy. Toe walking can be caused by a disorder ...

McArdle's disease: A differential diagnosis of idiopathic toe walking.

PubMed

Pomarino, David; Martin, Stephan; Pomarino, Andrea; Morigeau, Stefanie; Biskup, Saskia

2018-06-01

Idiopathic toe walking (ITW) is a pathological gait pattern in which children walk on their tip toes with no orthopedic or neurological reason. Physiological characteristics of the gastrocnemius muscles, the Achilles tendon, and the foot of toe walkers differ from subjects with a plantigrade walking pattern. McArdle's disease is characterized by the inability to break down muscle glycogen. It is an autosomal-recessive condition, characterized by low exercise tolerance, muscular atrophy at the shoulder girdle, episodes of myoglobinuria after vigorous physical activities and the occurrence of the second wind phenomenon. The aim of this review is to present the case studies of two subjects who were originally diagnosed as idiopathic toe walkers, but were then found to have McArdle's disease. This review will describe some physical characteristics that distinguish McArdle´s disease from Idiopathic toe walkers.

Toe transfer in congenital hand malformations.

PubMed

Foucher, G; Medina, J; Navarro, R; Nagel, D

2001-01-01

Fifty-eight patients with congenital hand abnormalities underwent 65 toe-to-hand transfers. Symbrachydactyly (51 cases) was the most frequent indication. Forty-seven second toe-to-hand transfers were performed in 44 patients. The mean follow-up time was 5.2 years. Two failures occurred in cases in which only one artery was anastomosed; no failures were noted when more than one artery fed the transfer. Two patients with a single second-toe transfer presented with lateral instability of the transferred metatarsophalangeal joint. The mean active range of motion was 38 degrees, with a mean extension lag of 25 degrees. The mean two-point discrimination was 5 mm. Forty-one patients used the transferred toe well, when performing activities of daily living and playing games. Toe-to-hand transfer, prior to the establishment of the grip pattern, facilitates integration of the transfer.

The effect of toe marker placement error on joint kinematics and muscle forces using OpenSim gait simulation.

PubMed

Xu, Hang; Merryweather, Andrew; Bloswick, Donald; Mao, Qi; Wang, Tong

2015-01-01

Marker placement can be a significant source of error in biomechanical studies of human movement. The toe marker placement error is amplified by footwear since the toe marker placement on the shoe only relies on an approximation of underlying anatomical landmarks. Three total knee replacement subjects were recruited and three self-speed gait trials per subject were collected. The height variation between toe and heel markers of four types of footwear was evaluated from the results of joint kinematics and muscle forces using OpenSim. The reference condition was considered as the same vertical height of toe and heel markers. The results showed that the residual variances for joint kinematics had an approximately linear relationship with toe marker placement error for lower limb joints. Ankle dorsiflexion/plantarflexion is most sensitive to toe marker placement error. The influence of toe marker placement error is generally larger for hip flexion/extension and rotation than hip abduction/adduction and knee flexion/extension. The muscle forces responded to the residual variance of joint kinematics to various degrees based on the muscle function for specific joint kinematics. This study demonstrates the importance of evaluating marker error for joint kinematics and muscle forces when explaining relative clinical gait analysis and treatment intervention.

Modelling Soil Erosion in the Densu River Basin Using RUSLE and GIS Tools.

PubMed

Ashiagbori, G; Forkuo, E K; Laari, P; Aabeyir, R

2014-07-01

Soil erosion involves detachment and transport of soil particles from top soil layers, degrading soil quality and reducing the productivity of affected lands. Soil eroded from the upland catchment causes depletion of fertile agricultural land and the resulting sediment deposited at the river networks creates river morphological change and reservoir sedimentation problems. However, land managers and policy makers are more interested in the spatial distribution of soil erosion risk than in absolute values of soil erosion loss. The aim of this paper is to model the spatial distribution of soil erosion in Densu River Basin of Ghana using RUSLE and GIS tools and to use the model to explore the relationship between erosion susceptibility, slope and land use/land cover (LULC) in the Basin. The rainfall map, digital elevation model, soil type map, and land cover map, were input data in the soil erosion model developed. This model was then categorized into four different erosion risk classes. The developed soil erosion map was then overlaid with the slope and LULC maps of the study area to explore their effects on erosion susceptibility of the soil in the Densu River Basin. The Model, predicted 88% of the basin as low erosion risk and 6% as moderate erosion risk, 3% as high erosion risk and 3% as severe risk. The high and severe erosion areas were distributed mainly within the areas of high slope gradient and also sections of the moderate forest LULC class. Also, the areas within the moderate forest LULC class found to have high erosion risk, had an intersecting high erodibility soil group.

Effect of Foot Progression Angle and Lateral Wedge Insole on a Reduction in Knee Adduction Moment.

PubMed

Tokunaga, Ken; Nakai, Yuki; Matsumoto, Ryo; Kiyama, Ryoji; Kawada, Masayuki; Ohwatashi, Akihiko; Fukudome, Kiyohiro; Ohshige, Tadasu; Maeda, Tetsuo

2016-10-01

This study evaluated the effect of foot progression angle on the reduction in knee adduction moment caused by a lateral wedged insole during walking. Twenty healthy, young volunteers walked 10 m at their comfortable velocity wearing a lateral wedged insole or control flat insole in 3 foot progression angle conditions: natural, toe-out, and toe-in. A 3-dimensional rigid link model was used to calculate the external knee adduction moment, the moment arm of ground reaction force to knee joint center, and the reduction ratio of knee adduction moment and moment arm. The result indicated that the toe-out condition and lateral wedged insole decreased the knee adduction moment in the whole stance phase. The reduction ratio of the knee adduction moment and the moment arm exhibited a close relationship. Lateral wedged insoles decreased the knee adduction moment in various foot progression angle conditions due to decrease of the moment arm of the ground reaction force. Moreover, the knee adduction moment during the toe-out gait with lateral wedged insole was the smallest due to the synergistic effect of the lateral wedged insole and foot progression angle. Lateral wedged insoles may be a valid intervention for patients with knee osteoarthritis regardless of the foot progression angle.

Simplified Radiographic Damage Index for Affected Joints in Chronic Gouty Arthritis

PubMed Central

2016-01-01

The aim of this study was to develop and validate a new radiographic damage scoring method (DAmagE index of GoUt; DAEGU) in chronic gout using plain radiography. Two independent observers scored foot x-rays from 15 patients with chronic gout according to the DAEGU method and the modified Sharp/van der Heijde (SvdH) method. The 10 metatarsophalangeal (MTP) and 2 interphalangeal (IP) joints of the first toes of both feet were scored to assess the degrees of erosion and joint space narrowing (JSN). The intraobserver and interobserver reliabilities were analyzed by calculating the intraclass correlation coefficient (ICC) and minimal detectable change (MDC). The correlation between the DAEGU and SvdH methods was analyzed by calculating the Spearman's rho correlation coefficients and Kappa coefficients. The DAEGU method was found to be highly reproducible (0.945–0.987 for the intraobserver and 0.993–0.996 for the interobserver ICC values). The erosion, JSN, and total scores exhibited strong positive correlations between the DAEGU and SvdH methods and also within each method (r = 0.860–0.969, P < 0.001 for all parameters). The DAEGU and SvdH methods were in very good agreement as determined by Kappa coefficient analysis [0.732 (0.387–1.000) for erosion and 1.000 (1.000–1.000) for JSN]. In conclusion, this study revealed that DAEGU method was a reliable and feasible tool in the assessment of radiographic damage in chronic gout. The DAEGU method may provide a more easy assessment of structural damage in chronic gout in the real clinical practice. PMID:26955246

Dune recovery after storm erosion on a high-energy beach: Vougot Beach, Brittany (France)

NASA Astrophysics Data System (ADS)

Suanez, Serge; Cariolet, Jean-Marie; Cancouët, Romain; Ardhuin, Fabrice; Delacourt, Christophe

2012-02-01

On 10th March 2008, the high energy storm Johanna hit the French Atlantic coast, generating severe dune erosion on Vougot Beach (Brittany, France). In this paper, the recovery of the dune of Vougot Beach is analysed through a survey of morphological changes and hydrodynamic conditions. Data collection focused on the period immediately following storm Johanna until July 2010, i.e. over two and a half years. Results showed that the dune retreated by a maximum of almost 6 m where storm surge and wave attack were the most energetic. Dune retreat led to the creation of accommodation space for the storage of sediment by widening and elevating space between the pre- and post-storm dune toe, and reducing impacts of the storm surge. Dune recovery started in the month following the storm event and is still ongoing. It is characterised by the construction of "secondary" embryo dunes, which recovered at an average rate of 4-4.5 cm per month, although average monthly volume changes varied from - 1 to 2 m 3.m - 1 . These embryo dunes accreted due to a large aeolian sand supply from the upper tidal beach to the existing foredune. These dune-construction processes were facilitated by growth of vegetation on low-profile embryo dunes promoting backshore accretion. After more than two years of survey, the sediment budget of the beach/dune system showed that more than 10,000 m 3 has been lost by the upper tidal beach. We suggest that seaward return currents generated during the storm of 10th March 2008 are responsible for offshore sediment transport. Reconstitution of the equilibrium beach profile following the storm event may therefore have generated cross-shore sediment redistribution inducing net erosion in the tidal zone.

In-Toeing and Out-Toeing in Children

PubMed Central

Wiley, James J.

1987-01-01

In-toeing and out-toeing problems are generally physiologic variants that arise from in utero posturing, and that gradually correct spontaneously during the active growing years of the child. Few torsional deformities result in genuine problems. Most residual effects are cosmetic, compounded by the anguish of concerned relatives and friends. Rarely is operative correction warranted. If corrective surgery comes under consideration, it is usually deferred until the patient reaches the age of 10. PMID:21263851

Correlation between toe flexor strength and ankle dorsiflexion ROM during the countermovement jump.

PubMed

Yun, Sung Joon; Kim, Moon-Hwan; Weon, Jong-Hyuck; Kim, Young; Jung, Sung-Hoon; Kwon, Oh-Yun

2016-08-01

[Purpose] This study assessed the relationships between peak toe flexor muscle strength, ankle dorsiflexion range of motion, and countermovement jump height. [Subjects and Methods] Eighteen healthy volunteers participated in the study. Each participant completed tests for peak toe flexor muscle strength, ankle dorsiflexion range of motion, and countermovement jump height. [Results] The results showed (1) a moderate correlation between ankle dorsiflexion range of motion and countermovement jump height and (2) a high correlation between peak first toe flexor muscle strength and countermovement jump height. Peak first toe flexor muscle strength and ankle dorsiflexion range of motion are the main contributors to countermovement jump performance. [Conclusion] These findings indicate that the measurement of peak first toe flexor muscle strength and ankle dorsiflexion range of motion may be useful in clinical practice for improving jump performance in athletes training for sports such as volleyball and basketball.

The effects of Taraxacum officinale extracts (TOE) supplementation on physical fatigue in mice.

PubMed

Jinchun, Zhang; Jie, Chen

2011-01-01

The study is to investigate the effect of Taraxacum officinale extracts (TOE) supplementation on physical fatigue based on the forced swimming capacity in mice. Forty Kunming male mice were randomly divided into 4 groups, i.e., normal control (NC) and three doses of TOE treated group (High-dose, Middle-dose and Low-dose). Three TOE treated groups were treated by oral TOE with 10, 30 and 100mg/kg b.w respectively for a period of 42 days. The normal control group was given a corresponding volume of sterile distilled water. After 6 weeks, the forced swimming capacity and blood biochemical parameters in mice were measured, and the result showed that TOE had an anti- physical fatigue effect. It enhanced the maximum swimming capacity of mice, effectively delayed the lowering of glucose in the blood, and prevented the increase in lactate and triglyceride concentrations.

Nailfold Capillaroscopy of Fingers and Toes - Variations of Normal.

PubMed

Lambova, Sevdalina Nikolova; Muller-Ladner, Ulf

2018-04-20

Nailfold capillaroscopy is the only method for morphological assessment of nutritive capillaries. The literature data about capillaroscopic findings in healthy individuals are scarce. To evaluate and compare the capillaroscopic findings of fingers and toes in healthy subjects. 22 healthy individuals were included in the study. Capillaroscopic examination was performed with videocapillaroscope Videocap 3.0 (DS Medica). Exclusion criteria were as follows: history of vasospasm, presence of accompanying diseases, taking any medications, arterial hypertension in first degree relatives, overweight or obesity (body mass index > 25kg/m2) and presence of chronic arterial or venous insufficiency. Poor visibility of nailfold capillaries was found significantly more frequently in the toes (22.7%, 5/22) as compared with fingers (0/22). Slight irregularities in capillary distribution and orientation to their parallel axis were significantly more common in the toes (31.8%, 7/22) as compared with fingers (9%, 2/22), (p<0.05). The mean diameter of the arterial (0.012±0.002mm) and the venous limb (0.017±0.002mm) of the toes did not differ significantly as compared to the respective parameters in the fingers (0.013±0.002mm for the arterial limb, p=0.46 and 0.018±0.002mm for the venous limb, p=0.25). The mean capillary density also did not differ significantly in the fingers and toes. The mean capillary length of the toes (0.165±0.096mm) was shorter as compared with hands (0.220±0.079mm), but the difference was not statistically significant (p=0.37). Presence of tortuous capillaries (>10%) was found significantly more often in the toes (12/22) as compared with fingers (6/22, χ2=6.769, p<0.05). Short capillary loops (length<100µm) were observed significantly more often in the toes (11/22 - toes, 1/22 - fingers, χ2=14.666, p<0.05). Capillaroscopic examination of the toes shows some differences as compared to those of the fingers such as greater number of cases with poor visibility and slight irregularities of distribution, greater number of shorter capillaries and increased tortuosity, which might be related to the thicker epidermis of the toes and increased capillary pressure due to gravity. The values of the major capillaroscopic parameters such as capillary diameters and capillary density in fingers and toes do not differ significantly. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

A numerical study of tsunami wave impact and run-up on coastal cliffs using a CIP-based model

NASA Astrophysics Data System (ADS)

Zhao, Xizeng; Chen, Yong; Huang, Zhenhua; Hu, Zijun; Gao, Yangyang

2017-05-01

There is a general lack of understanding of tsunami wave interaction with complex geographies, especially the process of inundation. Numerical simulations are performed to understand the effects of several factors on tsunami wave impact and run-up in the presence of gentle submarine slopes and coastal cliffs, using an in-house code, a constrained interpolation profile (CIP)-based model. The model employs a high-order finite difference method, the CIP method, as the flow solver; utilizes a VOF-type method, the tangent of hyperbola for interface capturing/slope weighting (THINC/SW) scheme, to capture the free surface; and treats the solid boundary by an immersed boundary method. A series of incident waves are arranged to interact with varying coastal geographies. Numerical results are compared with experimental data and good agreement is obtained. The influences of gentle submarine slope, coastal cliff and incident wave height are discussed. It is found that the tsunami amplification factor varying with incident wave is affected by gradient of cliff slope, and the critical value is about 45°. The run-up on a toe-erosion cliff is smaller than that on a normal cliff. The run-up is also related to the length of a gentle submarine slope with a critical value of about 2.292 m in the present model for most cases. The impact pressure on the cliff is extremely large and concentrated, and the backflow effect is non-negligible. Results of our work are highly precise and helpful in inverting tsunami source and forecasting disaster.

The miR172 target TOE3 represses AGAMOUS expression during Arabidopsis floral patterning.

PubMed

Jung, Jae-Hoon; Lee, Sangmin; Yun, Ju; Lee, Minyoung; Park, Chung-Mo

2014-02-01

microRNA172 (miR172) regulates phase transition and floral patterning in Arabidopsis by repressing targets that encode the APETALA2 (AP2) and AP2-like transcription factors. The miR172-mediated repression of the AP2 gene restricts AGAMOUS (AG) expression. In addition, most miR172 targets, including AP2, redundantly act as floral repressors, and the overexpression of the target genes causes delayed flowering. However, how miR172 targets other than AP2 regulate both of the developmental processes remains unclear. Here, we demonstrate that miR172-mediated repression of the TARGET OF EAT 3 (TOE3) gene is critical for floral patterning in Arabidopsis. Transgenic plants that overexpress a miR172-resistant TOE3 gene (rTOE3-ox) exhibit indeterminate flowers with numerous stamens and carpelloid organs, which is consistent with previous observations in transgenic plants that overexpress a miR172-resistant AP2 gene. TOE3 binds to the second intron of the AG gene. Accordingly, AG expression is significantly reduced in rTOE3-ox plants. TOE3 also interacts with AP2 in the nucleus. Given the major role of AP2 in floral patterning, miR172 likely regulates TOE3 in floral patterning, at least in part via AP2. In addition, a miR156 target SQUAMOSA PROMOTER BINDING PROTEIN-LIKE 3 directly activates TOE3 expression, revealing a novel signaling interaction between miR156 and miR172 in floral patterning. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

The DEP domain-containing protein TOE-2 promotes apoptosis in the Q lineage of C. elegans through two distinct mechanisms

PubMed Central

Gurling, Mark; Talavera, Karla; Garriga, Gian

2014-01-01

Neuroblast divisions in the nematode Caenorhabditis elegans often give rise to a larger neuron and a smaller cell that dies. We have previously identified genes that, when mutated, result in neuroblast divisions that generate daughter cells that are more equivalent in size. This effect correlates with the survival of daughter cells that would normally die. We now describe a role for the DEP domain-containing protein TOE-2 in promoting the apoptotic fate in the Q lineage. TOE-2 localized at the plasma membrane and accumulated in the cleavage furrow of the Q.a and Q.p neuroblasts, suggesting that TOE-2 might position the cleavage furrow asymmetrically to generate daughter cells of different sizes. This appears to be the case for Q.a divisions where loss of TOE-2 led to a more symmetric division and to survival of the smaller Q.a daughter. Localization of TOE-2 to the membrane is required for this asymmetry, but, surprisingly, the DEP domain is dispensable. By contrast, loss of TOE-2 led to loss of the apoptotic fate in the smaller Q.p daughter but did not affect the size asymmetry of the Q.p daughters. This function of TOE-2 required the DEP domain but not localization to the membrane. We propose that TOE-2 ensures an apoptotic fate for the small Q.a daughter by promoting asymmetry in the daughter cell sizes of the Q.a neuroblast division but by a mechanism that is independent of cell size in the Q.p division. PMID:24961802

Erosion modeling and test of slip-cast fused silica

NASA Astrophysics Data System (ADS)

Weiskopf, Francis B., Jr.; Lin, Jeffrey S.; Drobnick, Rudy A.; Feather, Brian K.

1990-10-01

This paper summarizes a test program to verify the Balageas erosion model for Slip Cast Fused Silica in a flight-like erosive environment. The test program is summarized with particular attention paid to documenting the erosive environment. The Balageas model was found to over predict the erosion for these tests and a revised model which gives reasonable agreement with the data is proposed.

Upscaling Bedrock Erosion Laws from the Point to the Patch and from the Event to the Year

NASA Astrophysics Data System (ADS)

Beer, A. R.; Turowski, J. M.

2017-12-01

Bedrock erosion depends on the interactions between the bedload tools and cover effects. However, it is unclear (i) how well long-term calibrations of existing erosion models can predict individual erosion events, and (ii) whether at-a-point event calibrations can be spatio-temporally upscaled. Here, we evaluate the performance of at-a-point calibrated erosion models by scaling their erosional efficiency coefficients (k-factors). We use continuous measurements of water discharge and bedload transport at 1- minute resolution, supplemented by repeated sub-millimeter-resolution spatial erosion surveys of a concrete slab in a small Swiss pre-alpine stream. Our results confirm the linear dependency of bedrock abrasion on sediment flux under sediment-starved conditions integrated over space (the 0.2m2 slab surface) and time (20 months). The predictive quality of the commonly applied unit stream power (USP) model is strongly susceptible to bedload transport distribution, whereas the bedload-dependent tools-only model yields more reasonable results. Applying the fitted mean model k-factors to a 16-year, 1-minute-resolution time series of discharge and bedload transport shows that the excess USP model EUSP (which includes a discharge threshold for bedload transport) generally predicts cumulative erosion reasonably well. For exceptional events, however, the EUSP model fails to predict the resulting large erosion rates. Hence, for sediment-starved conditions, event-based erosion model calibration can be applied over larger spatio-temporal scales with stationary k-factors, if a discharge threshold for sediment transport is taken into account. The EUSP model is a surrogate to predict long-term erosion given average erosive events, but fails to capture large event erosion rates. Consequently, the erosion tendency during average erosive events is generally matched by overall EUSP modelling, but large and highly erosive events are underpredicted. In such, water discharge does not account for the non-linearity in sediment availability (e.g., due to sudden release of interlocked sediment from the streambed) and in grain impact energies on the bedrock (i.e., large grain impacts dominate total erosion), which are the main drivers of a bedrock channel's morphology.

Models for estimating daily rainfall erosivity in China

NASA Astrophysics Data System (ADS)

Xie, Yun; Yin, Shui-qing; Liu, Bao-yuan; Nearing, Mark A.; Zhao, Ying

2016-04-01

The rainfall erosivity factor (R) represents the multiplication of rainfall energy and maximum 30 min intensity by event (EI30) and year. This rainfall erosivity index is widely used for empirical soil loss prediction. Its calculation, however, requires high temporal resolution rainfall data that are not readily available in many parts of the world. The purpose of this study was to parameterize models suitable for estimating erosivity from daily rainfall data, which are more widely available. One-minute resolution rainfall data recorded in sixteen stations over the eastern water erosion impacted regions of China were analyzed. The R-factor ranged from 781.9 to 8258.5 MJ mm ha-1 h-1 y-1. A total of 5942 erosive events from one-minute resolution rainfall data of ten stations were used to parameterize three models, and 4949 erosive events from the other six stations were used for validation. A threshold of daily rainfall between days classified as erosive and non-erosive was suggested to be 9.7 mm based on these data. Two of the models (I and II) used power law functions that required only daily rainfall totals. Model I used different model coefficients in the cool season (Oct.-Apr.) and warm season (May-Sept.), and Model II was fitted with a sinusoidal curve of seasonal variation. Both Model I and Model II estimated the erosivity index for average annual, yearly, and half-month temporal scales reasonably well, with the symmetric mean absolute percentage error MAPEsym ranging from 10.8% to 32.1%. Model II predicted slightly better than Model I. However, the prediction efficiency for the daily erosivity index was limited, with the symmetric mean absolute percentage error being 68.0% (Model I) and 65.7% (Model II) and Nash-Sutcliffe model efficiency being 0.55 (Model I) and 0.57 (Model II). Model III, which used the combination of daily rainfall amount and daily maximum 60-min rainfall, improved predictions significantly, and produced a Nash-Sutcliffe model efficiency for daily erosivity index prediction of 0.93. Thus daily rainfall data was generally sufficient for estimating annual average, yearly, and half-monthly time scales, while sub-daily data was needed when estimating daily erosivity values.

Advancing internal erosion monitoring using seismic methods in field and laboratory studies

NASA Astrophysics Data System (ADS)

Parekh, Minal L.

This dissertation presents research involving laboratory and field investigation of passive and active methods for monitoring and assessing earthen embankment infrastructure such as dams and levees. Internal erosion occurs as soil particles in an earthen structure migrate to an exit point under seepage forces. This process is a primary failure mode for dams and levees. Current dam and levee monitoring practices are not able to identify early stages of internal erosion, and often the result is loss of structure utility and costly repairs. This research contributes to innovations for detection and monitoring by studying internal erosion and monitoring through field experiments, laboratory experiments, and social and political framing. The field research in this dissertation included two studies (2009 and 2012) of a full-scale earthen embankment at the IJkdijk in the Netherlands. In both of these tests, internal erosion occurred as evidenced by seepage followed by sand traces and boils, and in 2009, eventual failure. With the benefit of arrays of closely spaced piezometers, pore pressure trends indicated internal erosion near the initiation time. Temporally and spatially dense pore water pressure measurements detected two pore water pressure transitions characteristic to the development of internal erosion, even in piezometers located away from the backward erosion activity. At the first transition, the backward erosion caused anomalous pressure decrease in piezometers, even under constant or increasing upstream water level. At the second transition, measurements stabilized as backward erosion extended further upstream of the piezometers, as shown in the 2009 test. The transitions provide an indication of the temporal development and the spatial extent of backward erosion. The 2012 IJkdijk test also included passive acoustic emissions (AE) monitoring. This study analyzed AE activity over the course of the 7-day test using a grid of geophones installed on the embankment surface. Analysis of root mean squared amplitude and AE threshold counts indicated activity focused at the toe in locations matching the sand boils. This analysis also compared the various detection methods employed at the 2012 test to discuss a timeline of detection related to observable behaviors of the structure. The second area of research included designing and fabricating an instrumented laboratory apparatus for investigating active seismic wave propagation through soil samples. This dissertation includes a description of the rigid wall permeameter, instrumentation, control, and acquisitions systems along with descriptions of the custom-fabricated seismic sensors. A series of experiments (saturated sand, saturated sand with a known static anomaly placed near the center of the sample, and saturated sand with a diminishing anomaly near the center of the sample) indicated that shear wave velocity changes reflected changes in the state of stress of the soil. The mean effective stress was influenced by the applied vertical axial load, the frictional interaction between the soil and permeameter wall, and the degree of preloading. The frictional resistance was sizeable at the sidewall of the permeameter and decreased the mean effective stress with depth. This study also included flow tests to monitor changes in shear wave velocities as the internal erosion process started and developed. Shear wave velocity decreased at voids or lower density zones in the sample and increased as arching redistributes loads, though the two conditions compete. Finally, the social and political contexts surrounding nondestructive inspection were considered. An analogous approach utilized by the aerospace industry was introduced: a case study comparing the path toward adopting nondestructive tools as standard practices in monitoring aircraft safety. Additional lessons for dam and levee safety management were discussed from a Science, Technology, Engineering, and Policy (STEP) perspective.

The Role of Cooling in Pahohoe Emplacement on Planetary Surfaces.

NASA Technical Reports Server (NTRS)

Glaze, L. S.; Baloga, S. M.

2015-01-01

Abundant evidence is emerging that many lavas on Mars were emplaced as slow-moving pahoehoe flows. Models for such scenarios contrast sharply with those for steep-sloped applications where gravity is the dominant force. The mode of flow emplacement on low slopes is characterized by toe formation and inflation. In the latter phase of pahoehoe flow emplacement, stagnation, inflation, and toe formation are most closely tied to the final topography, dimensions, and morphologic features. This mode of emplacement is particularly relevant to the low slopes of planetary surfaces such as the plains of Mars, Io and the Moon.

29 CFR 1910.132 - General requirements.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR OCCUPATIONAL SAFETY AND HEALTH STANDARDS Personal Protective Equipment § 1910.132 General requirements. (a... pay for non-specialty safety-toe protective footwear (including steel-toe shoes or steel-toe boots...

Historic bluff retreat and stabilization at Flag Harbor, Chesapeake Bay, Maryland

USGS Publications Warehouse

Clark, Inga; Larsen, Curtis E.; McRae, Michele

2002-01-01

Studies of bluff erosion and slope stability along the western shore of Chesapeake Bay suggest relative evolution from steep, eroding coastal bluffs to stable slopes at angles of repose ca. 35 degrees over decades. Because of the dating methods in those studies, it was impossible to precisely define rates of change. The present study provides historic age control. A pair of small harbor structures were constructed in the early 1950's at Chesapeake Beach, MD to maintain a dredged channel to a small marina occupying a ravine in the Calvert Cliffs. Prior to construction, this section of shoreline was comprised of eroding steep bluffs cut into Miocene-age sediments. Downdrift erosion is now apparent south of the structures as is updrift deposition behind the northern jetty. Since construction the updrift sand body has prograded northward and progressively deposited protective beaches along the toes of the bluffs. Former eroding bluffs nearest the harbor are now stable, vegetated slopes at angles near 35 degrees. Slope angles widen to the north and to the northern limit of the sand body. Beyond this are eroding bluffs standing at angles of 70-80 degrees. The relative time required for eroding bluffs to reach stability is estimated by interpolating the distance and time for the sand body to prograde northward since harbor construction. We measured slope angles at intervals northward from the updrift structure for a distance of 2000 feet. A least squares regression of slope angle vs distance showed progressive decrease in angle from north to south. Actively eroding 70-80 degree bluffs gave way to vegetated, but slumping slopes, and finally to stable 35-degree slopes at the harbor. A relationship between time and distance along the shore allowed us to estimate a stabilization time for this location of 35-40 years. The shortness of this time scale allows us to suggest that attempts to artificially stabilize eroding bluffs along this coast is not a simple task of protecting the toes of slopes from wave action. Once shoreline retreat ends, sloughing of sediment from bluff faces gives way to longer-term landslide processes. The bluff top recedes until a stable 35-degree slope is attained. Thus, simple shoreline protection methods may not preserve property at the bluff edge.

Footwear

MedlinePlus

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Using Student-Produced Video to Validate Head-to-Toe Assessment Performance.

PubMed

Purpora, Christina; Prion, Susan

2018-03-01

This study explored third-semester baccalaureate nursing students' perceptions of the value of using student-produced video as an approach for learning head-to-toe assessment, an essential clinical nursing skill taught in the classroom. A cognitive apprenticeship model guided the study. The researchers developed a 34-item survey. A convenience sample of 72 students enrolled in an applied assessment and nursing fundamentals course at a university in the western United States provided the data. Most students reported a videotaping process that worked, supportive faculty, valuable faculty review of their work, confidence, a sense of performance independence, the ability to identify normal assessment findings, and few barriers to learning. The results suggested that a student-produced video approach to learning head-to-toe assessment was effective. Further, the study demonstrated how to leverage available instructional technology to provide meaningful, personalized instruction and feedback to students about an essential nursing skill. [J Nurs Educ. 2018;57(3):154-158.]. Copyright 2018, SLACK Incorporated.

Pliocene shorelines and the deformation of passive margins.

NASA Astrophysics Data System (ADS)

Rovere, Alessio; Raymo, Maureen; Austermann, Jacqueline; Mitrovica, Jerry; Janßen, Alexander

2016-04-01

Characteristic geomorphology described from three Pliocene scarps in Rovere et al. [2014] was used to guide a global search for additional Pliocene age scarps that could be used to document former Pliocene shoreline locations. Each of the Rovere et al. [2014] paleo-shorelines was measured at the scarp toe abutting a flat coastal plain. In this study, nine additional such scarp-toe paleo-shorelines were identified. Each of these scarps has been independently dated to the Plio-Pleistocene; however, they were never unified by a single formation mechanism. Even when corrected for Glacial Isostatic Adjustment post-depositional effects, Post-Pliocene deformation of the inferred shorelines precludes a direct assessment of maximum Pliocene sea level height at the scarp toes. However, careful interpretation of the processes at the inferred paleo-shoreline suggests specific amplitudes of dynamic topography at each location, which could lead to a corrected maximum sea level height and provide a target dataset with which to compare dynamic topography model output.

Distribution of resistive and conductive structures in Nankai accretionary wedge reveals contrasting stress paths

NASA Astrophysics Data System (ADS)

Conin, Marianne; Bourlange, Sylvain; Henry, Pierre; Boiselet, Aurelien; Gaillot, Philippe

2014-01-01

In this article, we study the characteristics and spatial distribution of the deformation structures along the Kumano transect of the Nankai accretionary wedge, and use this information to interpret the stress path followed by the sediments. Deformation structures are identified from logging while drilling (LWD) resistivity images of the materials surrounding the drill hole and from 3-dimensional X-ray CT-images of cores acquired during the IODP NanTroSEIZE project. The relative resistivity of the structures identified on logs and the strike, dip, and density of structures identified on CT scan images are measured. The analysis of dip and strike of structures indicates that most of the resistive structures identified on logging data correspond to compactive shear bands. Results also indicate that conductive structures predominate at the toe of the prism and above the main out of sequence thrust, in locations where past and recent erosion occurred. We propose several mechanisms that could explain the relation between erosion and the absence of compactive shear bands. We conclude that sediments followed different stress paths depending on their location within the wedge, and that those differences explain the distribution of deformation structures within the wedge. We also show the coexistence of dilatant and compactant structures in fault zones including the frontal thrust and mega splay fault, and we interpret the coexistence of these structures as a possible consequence of a transient fluid pressure.

Developmental and Behavioral Effects of Toe Clipping on Neonatal and Preweanling Mice with and without Vapocoolant Anesthesia

PubMed Central

Paluch, Lee-Ronn; Lieggi, Christine C; Dumont, Magali; Monette, Sebastien; Riedel, Elyn R; Lipman, Neil S

2014-01-01

Toe clipping is used to identify and genotype preweanling mice, but the procedure generates concerns relevant to pain and distress. The few pertinent studies available evaluated mice between postnatal days (PND) 3 and 7, advocate the use of toe clipping in mice PND 7 or younger, and identify handling as the most distressing aspect of the procedure. Because both toe and tail clipping may be necessary in older mice to obtain sufficient DNA for genotyping, we surmised that performing these procedures concurrently to minimize handling would be beneficial. We also examined reflex development until PND 21 and adult behavior at 8 to 10 wk of age in mice toe clipped at PND 7 or 17 and the benefits of using topical vapocoolant anesthesia. C57BL/6J pups at PND 7 and 17 were assigned to 1 of 4 groups: 1) clipping of digit 3 of contralateral fore- and hindpaws; 2) toe clipping after topical vapocoolant anesthesia; 3) unclipped, unsprayed controls; and, 4) unclipped and vapocoolant-sprayed. Compared with unanesthetized pups, those sprayed with vapocoolant vocalized and struggled more when handled and had more bleeding, erythema, and swelling, which persisted for as long as 12 h after toe clipping. Reflex development, anxiety, locomotion, and motor coordination were not different among groups or with regard to the age of toe clipping. No tissue reaction was noted microscopically in paws collected at 10 wk of age. We conclude that the use of vapocoolant cannot be recommended due to its harmful effects and that toe clipping at PND 7 or 17 does not significantly affect the long-term welfare of mice. PMID:24602538

Toe spatiotemporal differences between transition steps when ascending shorter flight stairways of different heights.

PubMed

Ajisafe, Toyin; Wu, Jianhua; Geil, Mark

2017-03-01

Studies have typically treated the first and second floor-to-stair transition steps (TS1 and TS2) as one stride. However, because the foot is devoid of plantar cutaneous input from the stair surface at TS1, these steps may have different toe spatiotemporal profiles, and resultantly, different susceptibilities to a trip and/or a fall. This study compared vertical toe clearance, forward velocity, and their respective variability magnitudes between TS1 and TS2 when ascending stairs of different heights. Twenty young adults (seven males and 13 females) (21.68 ± 2.49 years; 169.70 ± 9.56 cm; 63.91 ± 9.62 kg) negotiated an intervening three-step staircase placed midpoint on a 10 m walkway. There were three stair heights: low stairs (LS), medium stairs (MS), and high stairs (HS). Vertical toe clearance, forward velocity, and their variability magnitudes were calculated. Vertical toe clearance was only higher (P < 0.05) at TS1 than TS2 in the medium and high stairs. Vertical toe clearance was more variable (P < 0.05) in the low compared to medium stairs. Also, forward toe velocity was greater at TS1 than TS2, but was lower in the medium and high stairs. The locomotor system appeared cautious by exaggerating vertical toe clearance at both TS1 and TS2 only in low stairs, possibly due to higher forward toe velocity. If the exaggeration strategy consistently persists, this finding may suggest decreased trip or fall risk at both TS1 and TS2 only when transitioning onto low stairs. Copyright © 2016 Elsevier Ltd. All rights reserved.

Antiphospholipid Antibodies and Recurrent Thrombotic Events: Persistence and Portfolio

PubMed Central

Amory, Colum F.; Levine, Steve R.; Brey, Robin L.; Gebregziabher, Mulugeta; Tuhrim, Stanley; Tilley, Barbara C.; Simpson, Ann-Catherin N.; Sacco, Ralph L.; Mohr, J.P.

2015-01-01

Background There are very limited prospective data on the significance of persistent of antiphospholipid antibodies (aPL) and recurrent thrombo-occlusive events (TOEs). We investigated the prognostic value of (1) two newer aPL assays, (2) an aPL portfolio, and (3) persistent aPL positivity following stroke. Methods 1,770 subjects from the APASS-WARSS study underwent further aPL testing for antibodies to phosphatidylserine (aPS) and β2-glycoprotein-I (anti-β2GPI) from stored sera. Follow-up aPL status was also tested in a subset of subjects. Primary analysis was based on time to any TOE (ischemic stroke, MI, TIA, DVT, PE, or systemic arterial occlusion)/death at 2 years. Cox proportional hazard analyses assessed whether aPL independently related to outcome. Results Persistent anti-β2GPI decreased the time to TOE/death after adjustment for potential confounders (HR=2.86, CI 1.21-6.76, p=0.017). When persistent anti-β2GPI was combined with another persistently positive aPL, time to TOE/death was also reduced (HR=3.79, CI 1.18-12.14, p=0.025). Neither persistent aCL, persistent aPS alone, nor a single positive anti-β2GPI or aPS was associated with decreased time to TOE/death. No single positive aPL, portfolio of baseline aPL, or any persistent aPL increased the rate of TOE/death. Conclusions Rates of TOE/death were not influenced by aPL results at baseline or follow-up. Persistent anti-β2GPI alone and with persistent second aPL were independently associated with decreased time to TOE/death. Persistent aPL, an aPL portfolio, and newer aPL in ischemic stroke patients are not helpful in predicting an increased rate of recurrent TOEs. PMID:26513489

Anatomical characterization of hoof growth pattern in six Iranian sheep breeds and its possible implication for trimming recommendations.

PubMed

Azarpajouh, S; Marchewka, J; Segura Correa, J C; Calderón Díaz, J A

2018-03-11

The objective of this study was to compare hoof anatomy, hoof growth pattern, and hoof weight-bearing surface of six different Iranian sheep breeds to identify possible differences in the hoof anatomical features that could help to minimize adverse effects of hoof trimming methods. Front and hind hooves of 2-year-old, previously untrimmed, pastured dairy ewes of six Iranian breeds (Afshari, Moghani, Kurdi, Makoui, Chaleshtori, and Lori-Bakhtiari; n = 180 ewes; 30 ewes per breed) were collected after slaughter. Medial and lateral claws were incised sagittally and anatomical measurements such as toe length, heel height, toe height, sole thickness, sole length, and toe angle were recorded in each claw. Data were analyzed using mixed model equations including breed, claw (lateral or medial), hoof (front or hind) and their interactions as fixed effects, and ewe as random effect. Breed differences were observed for all hoof measurements (P < 0.05). Chaleshtori sheep had higher measurements for most of the traits studied while Afshari and Makoui sheep had lower measurements. All measurements, except for toe length and toe height to solar surface to heel height ratio, were significantly greater in the front hooves than in the hind hooves (P < 0.05). Soles were longer in the medial claws compared to the lateral claws of the front hooves (P < 0.05). Results suggest the observed breed differences could interfere with establishing a standard, uniform hoof trimming method for sheep. For instance, it might be possible that while Afshari and Makoui sheep could require more conservative trimming, Chaleshtori sheep could require to be trimmed more. In consequence, hoof trimming methods might need to be adjusted to specific breed characteristics to avoid possible tissue damage.

AERO: A Decision Support Tool for Wind Erosion Assessment in Rangelands and Croplands

NASA Astrophysics Data System (ADS)

Galloza, M.; Webb, N.; Herrick, J.

2015-12-01

Wind erosion is a key driver of global land degradation, with on- and off-site impacts on agricultural production, air quality, ecosystem services and climate. Measuring rates of wind erosion and dust emission across land use and land cover types is important for quantifying the impacts and identifying and testing practical management options. This process can be assisted by the application of predictive models, which can be a powerful tool for land management agencies. The Aeolian EROsion (AERO) model, a wind erosion and dust emission model interface provides access by non-expert land managers to a sophisticated wind erosion decision-support tool. AERO incorporates land surface processes and sediment transport equations from existing wind erosion models and was designed for application with available national long-term monitoring datasets (e.g. USDI BLM Assessment, Inventory and Monitoring, USDA NRCS Natural Resources Inventory) and monitoring protocols. Ongoing AERO model calibration and validation are supported by geographically diverse data on wind erosion rates and land surface conditions collected by the new National Wind Erosion Research Network. Here we present the new AERO interface, describe parameterization of the underpinning wind erosion model, and provide a summary of the model applications across agricultural lands and rangelands in the United States.

Molded foot orthosis after great toe or medial ray amputations in diabetic feet.

PubMed

Due, T M; Jacobs, R L

1985-12-01

Necrosis of the tip of the next lateral remaining toe has been found to be a late complication of great toe and medial ray amputations in diabetic feet. The use of custom-molded insert foot orthoses helps avoid this complication.

29 CFR 1917.96 - Payment for protective equipment.

Code of Federal Regulations, 2014 CFR

2014-07-01

... Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION... employer at no cost to employees. (b) The employer is not required to pay for non-specialty safety-toe protective footwear (including steel-toe shoes or steel-toe boots) and non-specialty prescription safety...

29 CFR 1917.96 - Payment for protective equipment.

Code of Federal Regulations, 2013 CFR

2013-07-01

... Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION... employer at no cost to employees. (b) The employer is not required to pay for non-specialty safety-toe protective footwear (including steel-toe shoes or steel-toe boots) and non-specialty prescription safety...

29 CFR 1917.96 - Payment for protective equipment.

Code of Federal Regulations, 2012 CFR

2012-07-01

... Labor Regulations Relating to Labor (Continued) OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION... employer at no cost to employees. (b) The employer is not required to pay for non-specialty safety-toe protective footwear (including steel-toe shoes or steel-toe boots) and non-specialty prescription safety...

Effect of turf toe on foot contact pressures in professional American football players.

PubMed

Brophy, Robert H; Gamradt, Seth C; Ellis, Scott J; Barnes, Ronnie P; Rodeo, Scott A; Warren, Russell F; Hillstrom, Howard

2009-05-01

The relationship between turf toe and plantar foot pressures has not been extensively studied. Two hypotheses were tested in a cohort of professional American football players: first, that a history of turf toe is associated with increased peak hallucal and first metatarsophalangeal (MTP) plantar pressures; second, that decreased range of motion (ROM) of the first MTP correlates with increased peak hallucal and first MTP plantar pressures. Forty-four athletes from one National Football League (NFL) team were screened for a history of turf toe during preseason training. Dorsal passive MTP ROM and dynamic plantar pressures were measured in both feet of each player. Anatomical masking was used to assess peak pressure at the first MTP and hallux. First MTP dorsiflexion was significantly lower in halluces with a history of turf toe (40.6 +/- 15.1 degrees versus 48.4 +/- 12.8 degrees, p = 0.04). Peak hallucal pressures were higher in athletes with turf toe (535 +/- 288 kPa versus 414 +/- 202 kPa, p = 0.05) even after normalizing for athlete body mass index (p = 0.0003). Peak MTP pressure was not significantly different between the two groups tested. First MTP dorsiflexion did not correlate with peak hallucal or first MTP pressures. This study showed that turf toe is associated with decreased MTP motion. In addition, increased peak hallucal pressures were found. Further study is warranted to determine whether these pressures correlate with the severity of symptoms or progression of turf toe to first MTP arthritis.

Relationships Between Simple Toe Elevation Angle in the Standing Position and Dynamic Balance and Fall Risk Among Community-Dwelling Older Adults.

PubMed

Takatori, Katsuhiko; Matsumoto, Daisuke

2015-10-01

To investigate the relationships between toe elevation ability in the standing position and dynamic balance and fall risk among community-dwelling older adults. Cross-sectional survey. General community. Community-dwelling older adults (N = 287). Toe elevation angles in the standing position. Intra-rater and inter-rater reliability of measurements of the toe elevation angle was high (internal coefficient of correlation [ICC] (1,2) = 0.94 for the former and ICC (2,1) = 0.90 for the latter). Significant correlations were found between the toe elevation angle and age (r = -0.20, P < .01), 5-m walking time (r = -0.31, P < .01), Functional Reach Test (r = 0.36, P < .01), Timed Up and Go Test (r = -0.36, P < .01), and Chair Stand Test (r = 0.26, P < .01). Subjects who experienced a fall in the previous 6 months had a significantly lower toe elevation angle compared with subjects who did not experience a fall (t = 2.19, P < .05). Multiple regression analysis revealed that results of the Functional Reach Test (β = .22, P < .001) and Timed Up and Go Test (β = -0.74, P < .001) were significantly associated with the toe elevation angle. Toe elevation angle was an index of dynamic balance ability and appears to be a simple screening test for fall risk in community-dwelling older adults. Copyright © 2015 American Academy of Physical Medicine and Rehabilitation. Published by Elsevier Inc. All rights reserved.

Biomechanical Performance of Medial Row Suture Placement Relative to the Musculotendinous Junction in Transosseous Equivalent Suture Bridge Double-Row Rotator Cuff Repair.

PubMed

Virk, Mandeep S; Bruce, Benjamin; Hussey, Kristen E; Thomas, Jacqueline M; Luthringer, Tyler A; Shewman, Elizabeth F; Wang, Vincent M; Verma, Nikhil N; Romeo, Anthony A; Cole, Brian J

2017-02-01

To compare the biomechanical performance of medial row suture placement relative to the musculotendinous junction (MTJ) in a cadaveric transosseous equivalent suture bridge (TOE-SB) double-row (DR) rotator cuff repair (RCR) model. A TOE-SB DR technique was used to reattach experimentally created supraspinatus tendon tears in 9 pairs of human cadaveric shoulders. The medial row sutures were passed either near the MTJ (MTJ group) or 10 mm lateral to the MTJ (rotator cuff tendon [RCT] group). After the supraspinatus repair, the specimens underwent cyclic loading and load to failure tests. The localized displacement of the markers affixed to the tendon surface was measured with an optical tracking system. The MTJ group showed a significantly higher (P = .03) medial row failure (5/9; 3 during cyclic testing and 2 during load to failure testing) compared with the RCT group (0/9). The mean number of cycles completed during cyclic testing was lower in the MTJ group (77) compared with the RCT group (100; P = .07) because 3 specimens failed in the MTJ group during cyclic loading. There were no significant differences between the 2 study groups with respect to biomechanical properties during the load to failure testing. In a cadaveric TOE-SB DR RCR model, medial row sutures through the MTJ results in a significantly higher rate of medial row failure. In rotator cuff tears with tendon tissue loss, passage of medial row sutures through the MTJ should be avoided in a TOE-SB RCR technique because of the risk of medial row failure. Copyright © 2016. Published by Elsevier Inc.

Peripheral neuropathy in military aircraft maintenance workers in Australia.

PubMed

Guest, Maya; Attia, John R; D'este, Catherine A; Boggess, May M; Brown, Anthony M; Gibson, Richard E; Tavener, Meredith A; Ross, James; Gardner, Ian; Harrex, Warren

2011-04-01

This study aimed to examine possible persisting peripheral neuropathy in a group who undertook fuel tank repairs on F-111 aircraft, relative to two contemporaneous comparison groups. Vibration perception threshold (VPT) was tested using biothesiometry in 614 exposed personnel, compared with two unexposed groups (513 technical trades and 403 nontrades). Regression modeling was used to examine associations, adjusting for possible confounders. We observed that 26% of participants had chronic persistent increased VPT in the great toe. In contrast, statistically significant higher VPT of the great toe was observed in the comparison groups; however, the effect was small, about 1/4 the magnitude of diabetes. Age, height, and diabetes were all significant and strong predictors in most models. This study highlights chronic persisting peripheral neuropathy in a population of aircraft maintainers.

Foot ulcer risk and location in relation to prospective clinical assessment of foot shape and mobility among persons with diabetes.

PubMed

Cowley, Matthew S; Boyko, Edward J; Shofer, Jane B; Ahroni, Jessie H; Ledoux, William R

2008-11-01

We assessed baseline clinical foot shape for 2939 feet of diabetic subjects who were monitored prospectively for foot ulceration. Assessments included hammer/claw toes, hallux valgus, hallux limitus, prominent metatarsal heads, bony prominences, Charcot deformity, plantar callus, foot type, muscle atrophy, ankle and hallux mobility, and neuropathy. Risk factors were linked to ulcer occurrence and location via a Cox proportional hazards model. Hammer/claw toes (hazard ratio [HR] (95% confidence interval [CI])=1.43 (1.06, 1.94) p=0.02), marked hammer/claw toes (HR=1.77 (1.18, 2.66) p=0.006), bony prominences (HR=1.38 (1.02, 1.88), p=0.04), and foot type (Charcot or drop foot vs. neutrally aligned) (HR=2.34 (1.33, 4.10), p=0.003) were significant risk factors for ulceration adjusting for age, body mass index, insulin medication, ulcer history and amputation history. With adjustment for neuropathy only hammer/claw toes (HR=1.40 (1.03, 1.90), p=0.03) and foot type (HR=1.76 (1.04, 3.04), p=0.05) were significantly related to ulceration. However, there was no relationship between ulcer location and foot deformity. Certain foot deformities were predictive of ulceration, although there was no relationship between clinical foot deformity and ulcer location.

How does slope form affect erosion in CATFLOW-SED?

NASA Astrophysics Data System (ADS)

Gabelmann, Petra; Wienhöfer, Jan; Zehe, Erwin

2016-04-01

Erosion is a severe environmental problem in agro-ecosystems with highly erodible loess soils. It is controlled by various factors, e.g. rainfall intensity, initial wetness conditions, soil type, land use and tillage practice. Furthermore slope form and gradient have been shown to influence erosion amounts to a large extent. Within the last fifty years, various erosion models have been developed to describe the erosion process, estimate erosion amounts and identify erosion-prone areas. These models differ in terms of complexity, the processes which are considered, and the data required for model calibration and they can be categorised into empirical or statistical, conceptual, and physically-based models. CATFLOW-SED is a process-based hydrology and erosion model that can operate on catchment and hillslope scales. Soil water dynamics are described by the Richards equation including effective approaches for preferential flow. Evapotranspiration is simulated using an approach based on the Penman-Monteith equation. The model simulates overland flow using the diffusion wave equation. Soil detachment is related to the attacking forces of rainfall and overland flow, and the erosion resistance of soil. Sediment transport capacity and sediment deposition are related to overland flow velocity using the equation of Engelund and Hansen and the sinking velocity of grain sizes respectively. We performed a study to analyse the erosion process on different virtual hillslopes, with varying slope gradient and slope form, using the CATFLOW-SED model. We explored the role of landform on erosion and sedimentation, particularly we look for forms that either maximise or minimise erosion. Results indicate the importance to performing the process implementation within physically meaningful limits and choose appropriate model parameters respectively.

Sediment Budgets and Sources Inform a Novel Valley Bottom Restoration Practice Impacted by Legacy Sediment: The Big Spring Run, PA, Restoration Experiment

NASA Astrophysics Data System (ADS)

Walter, R. C.; Merritts, D.; Rahnis, M. A.; Gellis, A.; Hartranft, J.; Mayer, P. M.; Langland, M.; Forshay, K.; Weitzman, J. N.; Schwarz, E.; Bai, Y.; Blair, A.; Carter, A.; Daniels, S. S.; Lewis, E.; Ohlson, E.; Peck, E. K.; Schulte, K.; Smith, D.; Stein, Z.; Verna, D.; Wilson, E.

2017-12-01

Big Spring Run (BSR), a small agricultural watershed in southeastern Pennsylvania, is located in the Piedmont Physiographic Province, which has the highest nutrient and sediment yields in the Chesapeake Bay watershed. To effectively reduce nutrient and sediment loading it is important to monitor the effect of management practices on pollutant reduction. Here we present results of an ongoing study, begun in 2008, to understand the impact of a new valley bottom restoration strategy for reducing surface water sediment and nutrient loads. We test the hypotheses that removing legacy sediments will reduce sediment and phosphorus loads, and that restoring eco-hydrological functions of a buried Holocene wetland (Walter & Merritts 2008) will improve surface and groundwater quality by creating accommodation space to trap sediment and process nutrients. Comparisons of pre- and post-restoration gage data show that restoration lowered the annual sediment load by at least 118 t yr-1, or >75%, from the 1000 m-long restoration reach, with the entire reduction accounted for by legacy sediment removal. Repeat RTK-GPS surveys of pre-restoration stream banks verified that >90 t yr-1 of suspended sediment was from bank erosion within the restoration reach. Mass balance calculations of 137Cs data indicate 85-100% of both the pre-restoration and post-restoration suspended sediment storm load was from stream bank sources. This is consistent with trace element data which show that 80-90 % of the pre-restoration outgoing suspended sediment load at BSR was from bank erosion. Meanwhile, an inventory of fallout 137Cs activity from two hill slope transects adjacent to BSR yields average modern upland erosion rates of 2.7 t ha-1 yr-1 and 5.1 t ha-1 yr-1, showing modest erosion on slopes and deposition at toe of slopes. We conclude that upland farm slopes contribute little soil to the suspended sediment supply within this study area, and removal of historic valley bottom sediment effectively reduced bank erosion and sediment and phosphorus loads. Enhanced deposition further contributed to load reductions; prior to restoration, there was no deposition on tile pads on the 1.5 m-high legacy sediment "floodplain" terrace, whereas after restoration deposition on the low, restored floodplain showed net accumulation of 0.009 ± 0.012 m yr-1.

30 CFR 56.11005 - Fixed ladder anchorage and toe clearance.

Code of Federal Regulations, 2012 CFR

2012-07-01

... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Fixed ladder anchorage and toe clearance. 56.11005 Section 56.11005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Travelways § 56.11005 Fixed ladder anchorage and toe clearance. Fixed ladders shall be anchored securely and...

30 CFR 56.11005 - Fixed ladder anchorage and toe clearance.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Fixed ladder anchorage and toe clearance. 56.11005 Section 56.11005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Travelways § 56.11005 Fixed ladder anchorage and toe clearance. Fixed ladders shall be anchored securely and...

30 CFR 56.11005 - Fixed ladder anchorage and toe clearance.

Code of Federal Regulations, 2013 CFR

2013-07-01

... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Fixed ladder anchorage and toe clearance. 56.11005 Section 56.11005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Travelways § 56.11005 Fixed ladder anchorage and toe clearance. Fixed ladders shall be anchored securely and...

30 CFR 56.11005 - Fixed ladder anchorage and toe clearance.

Code of Federal Regulations, 2011 CFR

2011-07-01

... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Fixed ladder anchorage and toe clearance. 56.11005 Section 56.11005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Travelways § 56.11005 Fixed ladder anchorage and toe clearance. Fixed ladders shall be anchored securely and...

30 CFR 56.11005 - Fixed ladder anchorage and toe clearance.

Code of Federal Regulations, 2014 CFR

2014-07-01

... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Fixed ladder anchorage and toe clearance. 56.11005 Section 56.11005 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR... Travelways § 56.11005 Fixed ladder anchorage and toe clearance. Fixed ladders shall be anchored securely and...

[Modification of the Furnas-Vilkki technic in the reconstruction of congenital or traumatic carpal hands].

PubMed

Foucher, G

1995-01-01

A technique is described for reconstruction of a pincer, by a second toe transfer, in traumatic and congenital deformities, leaving only the wrist. Transfer on the anterior aspect of the radius allows to benefit from the wrist mobility to compensate for the limited range of motion of the second toe. Proximal situation of the toe gives the possibility of harvesting plenty of tendons to balance the toe. Results have been encouraging in two traumatic and 6 congenital cases of peromelic type of symbrachydactyly.

Extreme Cost Growth: Themes from Six U.S. Air Force Major Defense Acquisition Programs

DTIC Science & Technology

2015-01-01

launch company SpaceX brought anti-trust litigation against the ULA as early as 2005, arguing that the agreement foreclosed competition. Legal maneuvering...was still under way through 2014. See “ SpaceX and ULA Go Toe-to-Toe Over EELV Contracts,” NASA Spaceflight.com, March 5, 2014. 16 Again, it is...December 9, 2014: http://www.rand.org/pubs/papers/P4748.html “ SpaceX and ULA Go Toe-to-Toe Over EELV Contracts,” NASA Spaceflight.com, March 5

Sensitivity of mountain ecosystems to human-accelerated soil erosion. Contrasting geomorphic response between tropical and semi-arid ecosystems.

NASA Astrophysics Data System (ADS)

Vanacker, Veerle; Bellin, Nicolas; Schoonejans, Jerome; Molina, Armando; Kubik, Peter W.

2014-05-01

Human-induced land cover changes are causing important adverse effects on the ecological services rendered by mountain ecosystems, and the number of case-studies of the impact of humans on soil erosion and sediment yield has mounted rapidly. A modelling framework that is specifically adapted to mountain environments is currently lacking. Most studies make use of general river basin models that were originally parameterized and calibrated for temperate, low relief landscapes. Transposing these modelling concepts directly to steep environments with shallow and stony soils often leads to unrealistic model predictions, as model input parameters are rarely calibrated for the range of environmental conditions found in mountain regions. Here, we present a conceptual model that evaluates erosion regulation as a function of human disturbances in vegetation cover. The basic idea behind this model is that soil erosion mechanisms are independent of human impact, but that the frequency-magnitude distributions of erosion rates change as a response to human disturbances. Pre-disturbance (or natural) erosion rates are derived from in-situ produced 10Be concentrations in river sediment, while post-disturbance (or modern) erosion rates are derived from sedimentation rates in small catchments. In its simplicity, the model uses vegetation cover change as a proxy of human disturbance in a given vegetation system. The model is then calibrated with field measurements from two mountainous sites with strongly different vegetation dynamics, climatic and geological settings: the Tropical Andes, and the Spanish Betic Cordillera. Natural erosion processes are important in mountainous sites, and natural erosion benchmarks are primordial to assess human-induced changes in erosion rates. While the Spanish Betic Cordillera is commonly characterized as a degraded landscape, there is no significant change in erosion due to human disturbance for uncultivated sites. The opposite is true for the Tropical Andes where the share of natural erosion in the modern erosion rate is minimal for most disturbed sites. When pooling pre- and post-disturbance erosion data from both sites, it becomes evident that the human acceleration of erosion is significantly related to vegetation disturbance. It may therefore be expected that the potential for erosion regulation is larger in well-vegetated ecosystem where strong differences may exist in vegetation cover between human disturbed and undisturbed or restored sites.

Long-term responses of rainforest erosional systems at different spatial scales to selective logging and climatic change

PubMed Central

Walsh, R. P. D.; Bidin, K.; Blake, W. H.; Chappell, N. A.; Clarke, M. A.; Douglas, I.; Ghazali, R.; Sayer, A. M.; Suhaimi, J.; Tych, W.; Annammala, K. V.

2011-01-01

Long-term (21–30 years) erosional responses of rainforest terrain in the Upper Segama catchment, Sabah, to selective logging are assessed at slope, small and large catchment scales. In the 0.44 km2 Baru catchment, slope erosion measurements over 1990–2010 and sediment fingerprinting indicate that sediment sources 21 years after logging in 1989 are mainly road-linked, including fresh landslips and gullying of scars and toe deposits of 1994–1996 landslides. Analysis and modelling of 5–15 min stream-suspended sediment and discharge data demonstrate a reduction in storm-sediment response between 1996 and 2009, but not yet to pre-logging levels. An unmixing model using bed-sediment geochemical data indicates that 49 per cent of the 216 t km−2 a−1 2009 sediment yield comes from 10 per cent of its area affected by road-linked landslides. Fallout 210Pb and 137Cs values from a lateral bench core indicate that sedimentation rates in the 721 km2 Upper Segama catchment less than doubled with initially highly selective, low-slope logging in the 1980s, but rose 7–13 times when steep terrain was logged in 1992–1993 and 1999–2000. The need to keep steeplands under forest is emphasized if landsliding associated with current and predicted rises in extreme rainstorm magnitude-frequency is to be reduced in scale. PMID:22006973

Pedal symphalangism in modern American and Japanese skeletons.

PubMed

Case, D T; Heilman, J

2005-01-01

Pedal symphalangism is a surprisingly common heritable trait of the human foot. In individuals exhibiting the trait, the joint between the intermediate and distal phalanges of one or more lateral toes never develops, resulting in toes with two phalanges rather than three. This study was undertaken to explore variation in the frequency of pedal symphalangism among groups with widely different geographic ancestry, and to consider the applicability of this trait to skeletal biological distance studies. A total of 460 Euro-American, 191 African-American and 99 Japanese skeletons were examined for presence of pedal symphalangism. The American individuals date to the first half of the 20th c, while the Japanese individuals date to the late 19th and early 20th c. Although the country of ancestry is unknown for most of the American individuals, the Euro-Americans appear to be largely northern European, with roots in Germany, Ireland and Scandinavia, while the African-Americans are primarily descendants of slaves with roots in west African countries such as Nigeria, Benin, Togo, Ghana and Sierra Leone. Frequencies of fifth toe pedal symphalangism were calculated and compared among all three samples and found to be significantly higher in modern Japanese (83.7%) than in either Euro-Americans (46.4%) or African-Americans (44.0%). The Euro- and African-American frequencies were statistically indistinguishable for symphalangism of the fifth toe. In the fourth toe, however, the opposite result was found. The African-American frequency (7.9%) was significantly higher than the Euro-American frequency (2.6%), while no difference was found between the African-Americans and Japanese (11.7%). Since fourth toe pedal symphalangism has never been observed in the absence of fifth toe involvement, some of the same genes are clearly involved in producing the trait in both toes. However, differences in the pattern of fourth and fifth toe expression among the three groups identified in this study suggest that additional genetic or developmental factors may play a role in expression of pedal symphalangism in each of the toes.

Clinical and biomechanical changes following a 4-month toe-out gait modification program for people with medial knee osteoarthritis: a randomized controlled trial.

PubMed

Hunt, M A; Charlton, J M; Krowchuk, N M; Tse, C T F; Hatfield, G L

2018-04-27

To compare changes in knee pain, function, and loading following a 4-month progressive walking program with or without toe-out gait modification in people with medial tibiofemoral knee osteoarthritis. Individuals with medial knee osteoarthritis were randomized to a 4-month program to increase walking activity with (toe-out) or without (progressive walking) concomitant toe-out gait modification. The walking program was similar between the two groups, except that the gait modification group was trained to walk with 15° more toe-out. Primary outcomes included: knee joint pain (WOMAC), foot progression angles and knee joint loading during gait (knee adduction moment (KAM)). Secondary outcomes included WOMAC function, timed stair climb, and knee flexion moments during gait. Seventy-nine participants (40 in toe-out group, 39 in progressive walking group) were recruited. Intention-to-treat analysis showed no between-group differences in knee pain, function, or timed stair climb. However, the toe-out group exhibited significantly greater changes in foot progression angle (mean difference = -9.04° (indicating more toe-out), 95% CI: -11.22°, -6.86°; P < 0.001), late stance KAM (mean difference = -0.26 %BW*ht, 95% CI: -0.39 %BW*ht, -0.12 %BW*ht, P < 0.001) and KAM impulse (-0.06 %BW*ht*s, 95% CI: -0.11 %BW*ht*s, -0.01 %BW*ht*s; P = 0.031) compared to the progressive walking group at follow-up. The only between-group difference that remained at a 1-month retention assessment was foot progression angle, with greater changes in the toe-out group (mean difference = -6.78°, 95% CI: -8.82°, -4.75°; P < 0.001). Though both groups experienced improvements in self-reported pain and function, only the toe-out group experienced biomechanical improvements. NCT02019108. Copyright © 2018 Osteoarthritis Research Society International. Published by Elsevier Ltd. All rights reserved.

Simulation of Surface Erosion on a Logging Road in the Jackson Demonstration State Forest

Treesearch

Teresa Ish; David Tomberlin

2007-01-01

In constructing management models for the control of sediment delivery to streams, we have used a simulation model of road surface erosion known as the Watershed Erosion Prediction Project (WEPP) model, developed by the USDA Forest Service. This model predicts discharge, erosion, and sediment delivery at the road segment level, based on a stochastic climate simulator...

Comparison of Two Alternate Methods for Tracking Toe Clearance

NASA Technical Reports Server (NTRS)

Miller, Christopher A.; Feiveson, Alan H.; Bloomberg, Jacob J.

2007-01-01

Analyses of toe clearance during the swing phase of locomotion has often been utilized in determining a subject s propensity to trip while either walking or stepping over an obstacle. In the literature, toe clearance has been studied using a marker on the superior aspect of the second toe (rtoe), a marker on the lateral aspect of the fifth metatarsal head (mth5), or a virtual marker positioned at the anterior tip of the toe (vtoe). The purpose of this study was to compute toe clearance and associated parameters using a fifth metatarsal marker and a virtual toe marker, and compare the results with those of the standard toe marker. Subjects walked on a motorized treadmill at five different speeds while performing a visual acuity task at two separate target distances (ten 60-second trials). The minimum vertical height (TCl) was determined for each stride, along with its point of occurence in the gait cycle, and the angles of the foot and ankle at that time. A regression analysis was performed on the vtoe and mth5 results versus rtoe individually. For all TCl parameters, the mth5 marker did not correlate well with rtoe; the vtoe marker showed better agreement. Most importantly, the mth5 marker predicted a later occurence of TCl than rtoe and vtoe - thereby missing the most dangerous point in swing phase for a trip. From this analysis, the vtoe marker proved to be a better analog to rtoe than mth5, especially for determining a subject s propensity to trip.

From tails to toes: developing nonlethal tissue indicators of mercury exposure in five amphibian species.

PubMed

Pfleeger, Adam Z; Eagles-Smith, Collin A; Kowalski, Brandon M; Herring, Garth; Willacker, James J; Jackson, Allyson K; Pierce, John R

2016-04-01

Exposure to environmental contaminants has been implicated as a factor in global amphibian decline. Mercury (Hg) is a particularly widespread contaminant that biomagnifies in amphibians and can cause a suite of deleterious effects. However, monitoring contaminant exposure in amphibian tissues may conflict with conservation goals if lethal take is required. Thus, there is a need to develop non-lethal tissue sampling techniques to quantify contaminant exposure in amphibians. Some minimally invasive sampling techniques, such as toe-clipping, are common in population-genetic research, but it is unclear if these methods can adequately characterize contaminant exposure. We examined the relationships between mercury (Hg) concentrations in non-lethally sampled tissues and paired whole-bodies in five amphibian species. Specifically, we examined the utility of three different tail-clip sections from four salamander species and toe-clips from one anuran species. Both tail and toe-clips accurately predicted whole-body THg concentrations, but the relationships differed among species and the specific tail-clip section or toe that was used. Tail-clips comprised of the distal 0-2 cm segment performed the best across all salamander species, explaining between 82 and 92% of the variation in paired whole-body THg concentrations. Toe-clips were less effective predictors of frog THg concentrations, but THg concentrations in outer rear toes accounted for up to 79% of the variability in frog whole-body THg concentrations. These findings suggest non-lethal sampling of tails and toes has potential applications for monitoring contaminant exposure and risk in amphibians, but care must be taken to ensure consistent collection and interpretation of samples.

Mandibular canine intrusion with the segmented arch technique: A finite element method study.

PubMed

Caballero, Giselle Milagros; Carvalho Filho, Osvaldo Abadia de; Hargreaves, Bernardo Oliveira; Brito, Hélio Henrique de Araújo; Magalhães Júnior, Pedro Américo Almeida; Oliveira, Dauro Douglas

2015-06-01

Mandibular canines are anatomically extruded in approximately half of the patients with a deepbite. Although simultaneous orthodontic intrusion of the 6 mandibular anterior teeth is not recommended, a few studies have evaluated individual canine intrusion. Our objectives were to use the finite element method to simulate the segmented intrusion of mandibular canines with a cantilever and to evaluate the effects of different compensatory buccolingual activations. A finite element study of the right quadrant of the mandibular dental arch together with periodontal structures was modeled using SolidWorks software (Dassault Systèmes Americas, Waltham, Mass). After all bony, dental, and periodontal ligament structures from the second molar to the canine were graphically represented, brackets and molar tubes were modeled. Subsequently, a 0.021 × 0.025-in base wire was modeled with stainless steel properties and inserted into the brackets and tubes of the 4 posterior teeth to simulate an anchorage unit. Finally, a 0.017 × 0.025-in cantilever was modeled with titanium-molybdenum alloy properties and inserted into the first molar auxiliary tube. Discretization and boundary conditions of all anatomic structures tested were determined with HyperMesh software (Altair Engineering, Milwaukee, Wis), and compensatory toe-ins of 0°, 4°, 6°, and 8° were simulated with Abaqus software (Dassault Systèmes Americas). The 6° toe-in produced pure intrusion of the canine. The highest amounts of periodontal ligament stress in the anchor segment were observed around the first molar roots. This tooth showed a slight tendency for extrusion and distal crown tipping. Moreover, the different compensatory toe-ins tested did not significantly affect the other posterior teeth. The segmented mechanics simulated in this study may achieve pure mandibular canine intrusion when an adequate amount of compensatory toe-in (6°) is incorporated into the cantilever to prevent buccal and lingual crown tipping. The effects on the posterior anchorage segment were small and initially concentrated on the first molar. Copyright © 2015 American Association of Orthodontists. Published by Elsevier Inc. All rights reserved.

Your Bones

MedlinePlus

... part of the foot is similar to the hand, with five bones. Each toe has three tiny bones, except for your big toe, which has just two. This brings the bone total in both feet and ankles to 52! Most people don't use their toes and feet for grabbing stuff or writing, but they do use them for two very ...

Erosion and deposition on a debris-flow fan

NASA Astrophysics Data System (ADS)

Densmore, A. L.; Schuerch, P.; Rosser, N. J.; McArdell, B. W.

2011-12-01

The ability of a debris flow to entrain or deposit sediment controls the downstream evolution of flow volume, and ultimately dictates both the geomorphic impact of the flow and the potential hazard that it represents. Our understanding of the patterns of, and controls on, such flow volume changes remains extremely limited, however, partly due to a poor mechanistic grasp of the interactions between debris flows and their bed and banks. In addition, we lack a good understanding of the cumulative long-term effects of sequences of flows in a single catchment-fan system. Here we begin to address these issues by using repeated terrestrial laser scanning (TLS) to characterize the detailed surface change associated with the passage of multiple debris flows on the Illgraben fan, Switzerland. We calculate surface elevation change along a 300 m study reach, and from this derive the downfan rate of flow volume change, or lag rate; for comparison, we also derive the spatially-averaged lag rate over the entire ~2 km length of the fan. Lag rates are broadly comparable over both length scales, indicating that flow behavior does not vary significantly across the fan for most flows, but importantly we find that flow volume at the fan head is a poor predictor of volume at the fan toe. The sign and magnitude of bed elevation change scale with local flow depth; at flow depths < 2 m, erosion and deposition are approximately equally likely, but erosion becomes increasingly dominant for flow depths > 2 m. On the Illgraben fan, this depth corresponds to a basal shear stress of 3-4 kPa. Because flow depth is in part a function of channel cross-sectional topography, which varies strongly both within and between flows, this result indicates that erosion and deposition are likely to be highly dynamic. The dependence of flow volume change on both the channel topography and the flow history may thus complicate efforts to predict debris-flow inundation areas by simple flow routing. We then apply a 2d numerical model of debris-flow fan evolution to explore the key controls on debris-flow routing and topographic development over sequences of multiple flows. We find that fan topographic roughness plays an important role in both channel development and fan surface stability. We also find that, while first-order fan shape is largely insensitive to the input flow sequence, second-order variables such as the pattern of surface exposure ages and the distribution of channel characteristics hold more promise as robust recorders of past flow conditions. Further work is needed to understand the degree to which the TLS-derived (and Illgraben-specific) relationship between bed elevation change and flow depth can be applied in different settings, and to elucidate the role played by coarse debris in controlling patterns of erosion and deposition.

Operative Outcomes of Grade 3 Turf Toe Injuries in Competitive Football Players.

PubMed

Smith, Kenneth; Waldrop, Norman

2018-06-01

Turf toe is a term used to describe a hyperextension injury to the first metatarsophalangeal joint. Although the vast majority of turf toe injuries can be treated successfully without operative intervention, there are instances where surgery is required to allow the athlete to return to play. Although there is a plethora of literature on turf toe injuries and nonoperative management, there are currently few reports on operative outcomes in athletes. We obtained all cases of turf toe repair according to the ICD-10 procedural code. The inclusion criteria included: age greater than 16, turf toe injury requiring operative management and at least a varsity level high school football player. The charts were reviewed for age, BMI, level of competition, injury mechanism, football position, setting of injury and playing surface. In addition, we recorded the specifics of the operative procedure, a listing of all injured structures, the implants used and the great toe range of motion at final follow-up visit. The AOFAS Hallux score and VAS was used postoperatively as our outcome measures. Our patient population included 15 patients. The average follow-up time was 27.5 months. The average patient was 19.3 years old with a body mass index of 32.3. The average playing time missed was 16.5 weeks. The average dorsiflexion range of motion at the final follow-up was 42.3 degrees. At final follow-up, the average AOFAS Hallux score was 91.3. The average VAS pain score was 0.7 at rest and 0.8 with physical activity. Complete turf toe injuries are often debilitating and may require operative management to restore a pain-free, stable, and functional forefoot. This study represents the largest cohort of operatively treated grade 3 turf toe injuries in the literature and demonstrates that good clinical outcomes were achieved with operative repair. Level IV, case series.

Antiphospholipid Antibodies and Recurrent Thrombotic Events: Persistence and Portfolio.

PubMed

Amory, Colum F; Levine, Steven R; Brey, Robin L; Gebregziabher, Mulugeta; Tuhrim, Stanley; Tilley, Barbara C; Simpson, Ann-Catherin C; Sacco, Ralph L; Mohr, Jay P

2015-01-01

There are very limited prospective data on the significance of persistent antiphospholipid antibodies (aPL) and recurrent thrombo-occlusive events (TOEs). We investigated the prognostic value of (1) 2 newer aPL assays, (2) an aPL portfolio and (3) persistent aPL positivity following stroke. A total of 1,770 subjects from the APASS-WARSS study underwent further aPL testing for antibodies to phosphatidylserine (aPS) and anti-β2-glycoprotein-I (anti-β2GPI) from stored sera. Follow-up aPL status was also tested in a subset of subjects. Primary analysis was based on time to any TOE (ischemic stroke, myocardial infarction, transient ischemic attack, deep vein thrombosis, pulmonary embolism or systemic arterial occlusion)/death at 2 years. Cox proportional hazard analyses assessed whether aPL independently related to outcome. Persistent anti-β2GPI decreased the time to TOE/death after adjustment for potential confounders (hazards ratio (HR) 2.86, 95% CI 1.21-6.76, p = 0.017). When persistent anti-β2GPI was combined with another persistently positive aPL, time to TOE/death was also reduced (HR 3.79, 95% CI 1.18-12.14, p = 0.025). Neither persistent anticardiolipin antibodies nor persistent aPS alone nor a single positive anti-β2GPI nor aPS was associated with decreased time to TOE/death. No single positive aPL, portfolio of baseline aPL or any persistent aPL increased the rate of TOE/death. Rates of TOE/death were not influenced by aPL results at baseline or follow-up. Persistent anti-β2GPI alone, and with persistent second aPL, was independently associated with decreased time to TOE/death. Persistent aPL, an aPL portfolio and newer aPL in ischemic stroke patients are not helpful in predicting an increased rate of recurrent TOEs. © 2015 S. Karger AG, Basel.

Long-term predictive capability of erosion models

NASA Technical Reports Server (NTRS)

Veerabhadra, P.; Buckley, D. H.

1983-01-01

A brief overview of long-term cavitation and liquid impingement erosion and modeling methods proposed by different investigators, including the curve-fit approach is presented. A table was prepared to highlight the number of variables necessary for each model in order to compute the erosion-versus-time curves. A power law relation based on the average erosion rate is suggested which may solve several modeling problems.

Non-Fluvial Controls of Erosion, Sediment Transport and Fluvial Morphology in a mid-Atlantic Piedmont Watershed, White Clay Creek, Pennsylvania, U.S.A.

NASA Astrophysics Data System (ADS)

McCarthy, K.; Affinito, R. A.; Pizzuto, J. E.; Stotts, S.; Henry, T.; Krauthauser, M.; O'Neal, M. A.

2017-12-01

Quantifying contemporary sediment budgets is essential for restoration and ecosystem management of mid-Atlantic watersheds, but relevant processes and controls are poorly understood. In the 153 km2 White Clay Creek watershed in southeastern Pennsylvania, longitudinal profiles reflect migration of knickpoints though bedrock over Quaternary timescales. In bank exposures along stream valleys, saprolite, bedrock, and matrix-supported cobbly and bouldery diamicton (likely colluvial) commonly underlie finer-grained clay, silt, sand, and gravel deposits of valley floor depositional environments. Overbank sedimentation rates were quantified by measuring the thickness of sediment deposited over the roots of floodplain trees. The sampled trees range in age from 25-270 years with median sediment accumulation rates of approximately 2 mm/yr (range 0-10 mm/yr). Rates of bank retreat (measured from historical aerial imagery or root-exposure dendrochronology) vary from 6-36 cm/yr, with median rates of 10 cm/yr. While bank erosion rates are subject to a variety of controls, including channel curvature, the density of riparian trees, and freeze-thaw processes, the strongest influence appears to be the grain size and thickness of bouldery diamicton exposed along the toes of retreating banks. Cobbles and boulders supplied by eroding diamicton also mantle the bed of the channel, such that 33- 80% of the bed material remains immobile at bankfull stage. A conceptual model of fluvial processes and sediment budgets for these channels must account for the watershed's history of changing climate, tectonics, and land use, requiring mapping of bedrock, colluvium, former mill dam sediments, and other non-alluvial deposits and controls. Efforts to apply hydraulic geometry principles (requiring a precise adjustment to contemporary hydraulic and sediment regime) or to treat these channels as traditional "threshold" rivers are unlikely to be successful.

Validation of Water Erosion Prediction Project (WEPP) model for low-volume forest roads

Treesearch

William Elliot; R. B. Foltz; Charlie Luce

1995-01-01

Erosion rates of recently graded nongravel forest roads were measured under rainfall simulation on five different soils. The erosion rates observed on 24 forest road erosion plots were compared with values predicted by the Water Erosion Prediction Project (WEPP) Model, Version 93.1. Hydraulic conductivity and soil erodibility values were predicted from methods...

Modeling the Contribution of Ephemeral Gully Erosion Under Different Soil Management in An Olive Orchard Microcatchment Using AnnAGNPS Model

EPA Science Inventory

In Spain, few studies have been carried out to explore the erosion caused by processes other than interrill and rill erosion, such as gully and ephemeral gully erosion, especially because most of the available studies have evaluated the erosion at plot scale. A study about the en...

Analyzing hydro abrasive erosion in Kaplan turbine: A case study from India

NASA Astrophysics Data System (ADS)

Rai, Anant Kr.; Kumar, Arun

2016-10-01

Sediment flow through hydro turbine causes erosion of hydraulic components resulting in drop of turbine efficiency, particularly in hydropower plants of the Himalayan region. The measurement of erosion and monitoring of sediment flow in turbine are major concerns in erosion study. Attempts have been made to study erosion mainly in Pelton and Francis turbines. In this study, a simple and effective method has been presented to measure erosion in a Kaplan turbine of a run-of-river scheme Chilla hydropower plant in foothills of Himalaya. Recent techniques were used to measure sediment parameters like concentration, size, shape and mineral content. A standard erosion model is applied to estimate the erosion in Kaplan turbine blade, runner chamber and draft tube cone. A calibration factor has been proposed to apply the erosion model for site specific conditions. It has been found that the outer trailing edges of the turbine blade and upper runner chamber are most erosion prone zones. Sediment analysis revealed that effective operation can reduce erosion in turbine components. The estimated erosion values from model are found to be consistent with measured values. Finally, suggestions for design improvements and effective operation of erosion affected hydropower plants are given.

Gradual digital lengthening with autologous bone graft and external fixation for correction of flail toe in a patient with Raynaud's disease.

PubMed

Lamm, Bradley M; Ades, Joe K

2009-01-01

Iatrogenic flail toe is a complication of hammertoe surgery that occurs when an overaggressive resection of the proximal phalanx occurs. This can cause both functional and cosmetic concerns for the patient. We present a case report of the correction of a flail second toe in a patient with Raynaud's disease. The correction was achieved by means of gradual soft tissue lengthening with external fixation and an interposition autologous bone graft digital arthrodesis. After 5 months, this 2-stage procedure lengthened, stabilized, and restored the function of the toe. 4.

Toe-to-hand transfer.

PubMed

Yoshimura, M

1980-07-01

Toe-to-hand transfer was performed in 28 patients, involving 33 fingers, using microvascular technique. Of this number, 26 patients (31 fingers) had experienced trauma, and the remaining 2 patients (2 fingers) had a congenital deformity. The toew used for grafting were the great toe (1), the second tow (30), and third toe (2). Success was achieved in all cases, sensory recovery was good, and remarkable improvement was attained in function and cosmetic appearance. Metacarpal hand, amputation of thumb, and amputation thumb and three fingers were good indications for this procedure, which gave satisfactory aesthetic results, even in patients with amputation of single digits.

Accurate localization of organ representation areas on the feet & hands using the bi-digital O-ring test resonance phenomenon: its clinical implication in diagnosis & treatment--Part I.

PubMed

Omura, Y

1994-01-01

Accuracy of the widely used organ representation areas, currently used in different schools of foot and hand reflexology was evaluated using Bi-Digital O-Ring test resonance phenomenon. Our previous study indicated that mapping organ representation areas of the tongue using Bi-Digital O-Ring Test resonance phenomenon between 2 identical substances often provided more reliable clinical information for both diagnosis and treatment than the 2 widely used, but crude, traditional schools of Chinese tongue diagnosis. This same method was applied for the mapping of the organ representation areas on the feet and hands. We succeeded in mapping the following areas on human feet: 1) Middle (3rd) toe on the sole side represents the following starting from the tip: A) Head, B) Face with eye, ear, nose, and mouth (1st Digit) C) Neck and organs within the neck (narrow band of space between 1st crease after the 1st digit and crease at the junction of the beginning of the sole); 2) 2nd and 4th toe represent upper extremities, the beginning tip being fingers and hands. The crease at the base of these toes represents the shoulder. The 2nd toe represents right upper extremity, and the 4th toe represents left upper extremity; 3) 1st and 5th toes in both the right and left feet represent lower extremities with the tip being the toes and soles of feet. The crease at the base of these toes represents the inguinal area. The 1st toe of each foot represents right lower extremity, and 5th toe represents left lower extremity. The sole of the foot is divided into the following 3 distinctive sections. 1) Upper (1st) section represents organs in the chest cavity including 2 thymus glands, trachea, 2 lungs, with the heart between them, and with the esophagus appearing as a narrow band outside of the lung near and below the 1st and 2nd toe depending upon the individual. Chest section occupies the first 1/3 to 1/5 (on a relatively long foot) of the entire sole. The boundary between the chest and G.I. system can be approximately estimated by extending the length of the entire toe or up to 25% longer to the sole, but it can be accurately determined using a diaphragm tissue microscope slide as a reference control substance. 2) Middle (2nd) section represents Gastro-Intestinal system, including lower end of the esophagus, liver, stomach, spleen, gall bladder, pancreas, duodenum, jejunum, ileum, appendix, colon, and anus.(ABSTRACT TRUNCATED AT 400 WORDS)

The WEPP Model Application in a Small Watershed in the Loess Plateau

PubMed Central

Han, Fengpeng; Ren, Lulu; Zhang, Xingchang; Li, Zhanbin

2016-01-01

In the Loess Plateau, soil erosion has not only caused serious ecological and environmental problems but has also impacted downstream areas. Therefore, a model is needed to guide the comprehensive control of soil erosion. In this study, we introduced the WEPP model to simulate soil erosion both at the slope and watershed scales. Our analyses showed that: the simulated values at the slope scale were very close to the measured. However, both the runoff and soil erosion simulated values at the watershed scale were higher than the measured. At the slope scale, under different coverage, the simulated erosion was slightly higher than the measured. When the coverage is 40%, the simulated results of both runoff and erosion are the best. At the watershed scale, the actual annual runoff of the Liudaogou watershed is 83m3; sediment content is 0.097 t/m3, annual erosion sediment 8.057t and erosion intensity 0.288 t ha-1 yr-1. Both the simulated values of soil erosion and runoff are higher than the measured, especially the runoff. But the simulated erosion trend is relatively accurate after the farmland is returned to grassland. We concluded that the WEPP model can be used to establish a reasonable vegetation restoration model and guide the vegetation restoration of the Loess Plateau. PMID:26963704

Implementation of channel-routing routines in the Water Erosion Prediction Project (WEPP) model

Treesearch

Li Wang; Joan Q. Wu; William J. Elliott; Shuhui Dun; Sergey Lapin; Fritz R. Fiedler; Dennis C. Flanagan

2010-01-01

The Water Erosion Prediction Project (WEPP) model is a process-based, continuous-simulation, watershed hydrology and erosion model. It is an important tool for water erosion simulation owing to its unique functionality in representing diverse landuse and management conditions. Its applicability is limited to relatively small watersheds since its current version does...

A square root ensemble Kalman filter application to a motor-imagery brain-computer interface.

PubMed

Kamrunnahar, M; Schiff, S J

2011-01-01

We here investigated a non-linear ensemble Kalman filter (SPKF) application to a motor imagery brain computer interface (BCI). A square root central difference Kalman filter (SR-CDKF) was used as an approach for brain state estimation in motor imagery task performance, using scalp electroencephalography (EEG) signals. Healthy human subjects imagined left vs. right hand movements and tongue vs. bilateral toe movements while scalp EEG signals were recorded. Offline data analysis was conducted for training the model as well as for decoding the imagery movements. Preliminary results indicate the feasibility of this approach with a decoding accuracy of 78%-90% for the hand movements and 70%-90% for the tongue-toes movements. Ongoing research includes online BCI applications of this approach as well as combined state and parameter estimation using this algorithm with different system dynamic models.

Distribution and depth of bottom-simulating reflectors in the Nankai subduction margin.

PubMed

Ohde, Akihiro; Otsuka, Hironori; Kioka, Arata; Ashi, Juichiro

2018-01-01

Surface heat flow has been observed to be highly variable in the Nankai subduction margin. This study presents an investigation of local anomalies in surface heat flows on the undulating seafloor in the Nankai subduction margin. We estimate the heat flows from bottom-simulating reflectors (BSRs) marking the lower boundaries of the methane hydrate stability zone and evaluate topographic effects on heat flow via two-dimensional thermal modeling. BSRs have been used to estimate heat flows based on the known stability characteristics of methane hydrates under low-temperature and high-pressure conditions. First, we generate an extensive map of the distribution and subseafloor depths of the BSRs in the Nankai subduction margin. We confirm that BSRs exist at the toe of the accretionary prism and the trough floor of the offshore Tokai region, where BSRs had previously been thought to be absent. Second, we calculate the BSR-derived heat flow and evaluate the associated errors. We conclude that the total uncertainty of the BSR-derived heat flow should be within 25%, considering allowable ranges in the P-wave velocity, which influences the time-to-depth conversion of the BSR position in seismic images, the resultant geothermal gradient, and thermal resistance. Finally, we model a two-dimensional thermal structure by comparing the temperatures at the observed BSR depths with the calculated temperatures at the same depths. The thermal modeling reveals that most local variations in BSR depth over the undulating seafloor can be explained by topographic effects. Those areas that cannot be explained by topographic effects can be mainly attributed to advective fluid flow, regional rapid sedimentation, or erosion. Our spatial distribution of heat flow data provides indispensable basic data for numerical studies of subduction zone modeling to evaluate margin parallel age dependencies of subducting plates.

On the use of wave parameterizations and a storm impact scaling model in National Weather Service Coastal Flood and decision support operations

USGS Publications Warehouse

Mignone, Anthony; Stockdon, H.; Willis, M.; Cannon, J.W.; Thompson, R.

2012-01-01

National Weather Service (NWS) Weather Forecast Offices (WFO) are responsible for issuing coastal flood watches, warnings, advisories, and local statements to alert decision makers and the general public when rising water levels may lead to coastal impacts such as inundation, erosion, and wave battery. Both extratropical and tropical cyclones can generate the prerequisite rise in water level to set the stage for a coastal impact event. Forecasters use a variety of tools including computer model guidance and local studies to help predict the potential severity of coastal flooding. However, a key missing component has been the incorporation of the effects of waves in the prediction of total water level and the associated coastal impacts. Several recent studies have demonstrated the importance of incorporating wave action into the NWS coastal flood program. To follow up on these studies, this paper looks at the potential of applying recently developed empirical parameterizations of wave setup, swash, and runup to the NWS forecast process. Additionally, the wave parameterizations are incorporated into a storm impact scaling model that compares extreme water levels to beach elevation data to determine the mode of coastal change at predetermined “hotspots” of interest. Specifically, the storm impact model compares the approximate storm-induced still water level, which includes contributions from tides, storm surge, and wave setup, to dune crest elevation to determine inundation potential. The model also compares the combined effects of tides, storm surge, and the 2 % exceedance level for vertical wave runup (including both wave setup and swash) to dune toe and crest elevations to determine if erosion and/or ocean overwash may occur. The wave parameterizations and storm impact model are applied to two cases in 2009 that led to significant coastal impacts and unique forecast challenges in North Carolina: the extratropical “Nor'Ida” event during 11-14 November and the large swell event from distant Hurricane Bill on 22 August. The coastal impacts associated with Nor'Ida were due to the combined effects of surge, tide, and wave processes and led to an estimated 5.8 million dollars in damage. While the impacts from Hurricane Bill were not as severe as Nor'Ida, they were mainly associated with wave processes. Thus, this event exemplifies the importance of incorporating waves into the total water level and coastal impact prediction process. These examples set the stage for potential future applications including adaption to the more complex topography along the New England coast.

Material and biofilm load of K wires in toe surgery: titanium versus stainless steel.

PubMed

Clauss, Martin; Graf, Susanne; Gersbach, Silke; Hintermann, Beat; Ilchmann, Thomas; Knupp, Markus

2013-07-01

Recurrence rates for toe deformity correction are high and primarily are attributable to scar contractures. These contractures may result from subclinical infection. We hypothesized that (1) recurrence of toe deformities and residual pain are related to low-grade infections from biofilm formation on percutaneous K wires, (2) biofilm formation is lower on titanium (Ti) K wires compared with stainless steel (SS) K wires, and (3) clinical outcome is superior with the use of Ti K wires compared with SS K wires. In this prospective nonrandomized, comparative study, we investigated 135 lesser toe deformities (61 patients; 49 women; mean ± SD age, 60 ± 15 years) temporarily fixed with K wires between August 2010 and March 2011 (81 SS, 54 Ti). K wires were removed after 6 weeks. The presence of biofilm-related infections was analyzed by sonication. High bacterial loads (> 500 colony-forming units [CFU]/mL) were detected on all six toes requiring revision before 6 months. Increased bacterial load was associated with pain and swelling but not recurrence of the deformity. More SS K wires had greater than 100 CFU/mL bacteria than Ti K wires. For K wires with a bacterial count greater than 100 CFU/mL, toes with Ti K wires had a lower recurrence rate, less pain, and less swelling than toes with SS K wires. Ti K wires showed superior clinical outcomes to SS K wires. This appears to be attributable to reduced infection rates. Although additional study is needed, we currently recommend the use of Ti K wires for the transfixation of toe deformities. Level II, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Importance and challenges of measuring intrinsic foot muscle strength

PubMed Central

2012-01-01

Background Intrinsic foot muscle weakness has been implicated in a range of foot deformities and disorders. However, to establish a relationship between intrinsic muscle weakness and foot pathology, an objective measure of intrinsic muscle strength is needed. The aim of this review was to provide an overview of the anatomy and role of intrinsic foot muscles, implications of intrinsic weakness and evaluate the different methods used to measure intrinsic foot muscle strength. Method Literature was sourced from database searches of MEDLINE, PubMed, SCOPUS, Cochrane Library, PEDro and CINAHL up to June 2012. Results There is no widely accepted method of measuring intrinsic foot muscle strength. Methods to estimate toe flexor muscle strength include the paper grip test, plantar pressure, toe dynamometry, and the intrinsic positive test. Hand-held dynamometry has excellent interrater and intrarater reliability and limits toe curling, which is an action hypothesised to activate extrinsic toe flexor muscles. However, it is unclear whether any method can actually isolate intrinsic muscle strength. Also most methods measure only toe flexor strength and other actions such as toe extension and abduction have not been adequately assessed. Indirect methods to investigate intrinsic muscle structure and performance include CT, ultrasonography, MRI, EMG, and muscle biopsy. Indirect methods often discriminate between intrinsic and extrinsic muscles, but lack the ability to measure muscle force. Conclusions There are many challenges to accurately measure intrinsic muscle strength in isolation. Most studies have measured toe flexor strength as a surrogate measure of intrinsic muscle strength. Hand-held dynamometry appears to be a promising method of estimating intrinsic muscle strength. However, the contribution of extrinsic muscles cannot be excluded from toe flexor strength measurement. Future research should clarify the relative contribution of intrinsic and extrinsic muscles during intrinsic foot muscle strength testing. PMID:23181771

Measuring systolic ankle and toe pressure using the strain gauge technique--a comparison study between mercury and indium-gallium strain gauges.

PubMed

Broholm, Rikke; Wiinberg, Niels; Simonsen, Lene

2014-09-01

Measurement of the ankle and toe pressures are often performed using a plethysmograph, compression cuffs and a strain gauge. Usually, the strain gauge contains mercury but other alternatives exist. From 2014, the mercury-containing strain gauge will no longer be available in the European Union. The aim of this study was to compare an indium-gallium strain gauge to the established mercury-containing strain gauge. Consecutive patients referred to the Department of Clinical Physiology and Nuclear Medicine at Bispebjerg and Frederiksberg Hospitals for measurements of systolic ankle and toe pressures volunteered for the study. Ankle and toe pressures were measured twice with the mercury and the indium-gallium strain gauge in random order. Comparison of the correlation between the mean pressure using the mercury and the indium-gallium device and the difference between the two devices was performed for both toe and ankle level. A total of 53 patients were included (36 male). Mean age was 69 (range, 45-92 years). Mean pressures at toe and ankle level with the mercury and the indium-gallium strain gauges were 77 (range, 0-180) mm Hg and 113 (range, 15-190) mm Hg, respectively. Comparison between the mercury and the indium-gallium strain gauge showed a difference in toe blood pressure values of - 0.7 mm Hg (SD: 7.0). At the ankle level, a difference of 2.0 mm Hg (SD: 8.6) was found. The two different devices agree sufficiently in the measurements of systolic ankle and toe pressure for the indium-gallium strain gauge to replace the mercury strain gauge.

[Second toe transfer in congenital hand differences].

PubMed

Dautel, G; Barbary, S

2008-12-01

In congenital hand differences, microsurgical toe transfer involves the creation of one or several rays in a child that never possessed them before. Second toe transplantation was uniformly used in this series that include 65 consecutive cases. Etiologies were represented by symbrachydactyly, constriction band syndrome or central cleft hand. Second toe transfer was performed with or without the MTP joint and followed by proximal ray resection of the donor toe. In the vast majority of theses cases, transplantation was performed in adactylic or monodactylic hand, the ultimate functional goal was the creation of a "tip-to-tip" two fingers pinch. Implantation site was chosen according to the situation of the existing finger(s). The existence of a functioning recipient MCP joint was one of the key factors of the final functional outcome. There were two vascular failures in this series with complete necrosis of the transplanted toe. Two additional toes appeared mediocre with respect to the overall transfer integration. The final mobility of the fingers reconstructed was measured using the total active motion score. Average TAM was poor (42 degrees +/-24 degrees ). In 12 out of 15 patients that were evaluated with a follow-up of at least five years, the static two-point discrimination was found to be excellent (less than 6mm). Our series did not allow us to establish a firm correlation between the type of nerve suture used and the quality of sensory recovery. Growth was measured as a percentage of the intact second toe (68 to 95%). All children on a long term basis had a normal gait without any impediment during sports or leisure activities. Clinical results obtained in this series lead to think that the cerebral cortex has got some plasticity which allows the integration of the transplants.

Comparison of implant cost and surgical time in arthroscopic transosseous and transosseous equivalent rotator cuff repair.

PubMed

Black, Eric M; Austin, Luke S; Narzikul, Alexa; Seidl, Adam J; Martens, Kelly; Lazarus, Mark D

2016-09-01

We investigated the cost savings associated with arthroscopic transosseous (anchorless) double-row rotator cuff repair compared with double-row anchored (transosseous-equivalent [TOE]) repair. All patients undergoing double-row arthroscopic rotator cuff repair from 2009 to 2012 by a single surgeon were eligible for inclusion. The study included 2 consecutive series of patients undergoing anchorless or TOE repair. Excluded from the study were revision repairs, subscapularis repairs, patients with poor tendon quality or excursion requiring medialized repair, and partial repairs. Rotator cuff implant costs (paid by the institution) and surgical times were compared between the 2 groups, controlling for rotator cuff tear size and additional procedures performed. The study included 344 patients, 178 with TOE repairs and 166 with anchorless repairs. Average implant cost for TOE repairs was $1014.10 ($813.00 for small, $946.67 for medium, $1104.56 for large, and $1507.29 for massive tears). This was significantly more expensive compared with anchorless repairs, which averaged $678.05 ($659.75 for small, $671.39 for medium, $695.55 for large, and $716.00 for massive tears). Average total operative time in TOE and anchorless groups was not significantly different (99 vs. 98 minutes). There was larger (although not statistically significant) case time variation in the TOE group. Compared with TOE repair, anchorless rotator cuff repair provides substantial implant-related cost savings, with no significant differences in surgical time for medium and large rotator cuff tears. Case time for TOE repair varied more with extremes in tear size. Copyright © 2016 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

Non-MTC gait cycles: An adaptive toe trajectory control strategy in older adults.

PubMed

Santhiranayagam, Braveena K; Sparrow, W A; Lai, Daniel T H; Begg, Rezaul K

2017-03-01

Minimum-toe-clearance (MTC) above the walking surface is a critical representation of toe-trajectory control due to its association with tripping risk. Not all gait cycles exhibit a clearly defined MTC within the swing phase but there have been few previous accounts of the biomechanical characteristics of non-MTC gait cycles. The present report investigated the within-subject non-MTC gait cycle characteristics of 15 older adults (mean 73.1 years) and 15 young controls (mean 26.1 years). Participants performed the following tasks on a motorized treadmill: preferred speed walking, dual task walking (carrying a glass of water) and a dual-task speed-matched control. Toe position-time coordinates were acquired using a 3 dimensional motion capture system. When MTC was present, toe height at MTC (MTC height ) was extracted. The proportion of non-MTC gait cycles was computed for the age groups and individuals. For non-MTC gait cycles an 'indicative' toe height at the individual's average swing phase time (MTC time ) for observed MTC cycles was averaged across multiple non-MTC gait cycles. In preferred-speed walking Young demonstrated 2.9% non-MTC gait cycles and Older 18.7%. In constrained walking conditions both groups increased non-MTC gait cycles and some older adults revealed over 90%, confirming non-MTC gait cycles as an ageing-related phenomenon in lower limb trajectory control. For all participants median indicative toe-height on non-MTC gait cycles was greater than median MTC height . This result suggests that eliminating the biomechanically hazardous MTC event by adopting more of the higher-clearance non-MTC gait cycles, is adaptive in reducing the likelihood of toe-ground contact. Copyright © 2017 Elsevier B.V. All rights reserved.

From tails to toes: developing nonlethal tissue indicators of mercury exposure in five amphibian species

USGS Publications Warehouse

Pfleeger, Adam Z.; Eagles-Smith, Collin A.; Kowalski, Brandon M.; Herring, Garth; Willacker, James J.; Jackson, Allyson K.; Pierce, John

2016-01-01

Exposure to environmental contaminants has been implicated as a factor in global amphibian decline. Mercury (Hg) is a particularly widespread contaminant that biomagnifies in amphibians and can cause a suite of deleterious effects. However, monitoring contaminant exposure in amphibian tissues may conflict with conservation goals if lethal take is required. Thus, there is a need to develop non-lethal tissue sampling techniques to quantify contaminant exposure in amphibians. Some minimally invasive sampling techniques, such as toe-clipping, are common in population-genetic research, but it is unclear if these methods can adequately characterize contaminant exposure. We examined the relationships between mercury (Hg) concentrations in non-lethally sampled tissues and paired whole-bodies in five amphibian species. Specifically, we examined the utility of three different tail-clip sections from four salamander species and toe-clips from one anuran species. Both tail and toe-clips accurately predicted whole-body THg concentrations, but the relationships differed among species and the specific tail-clip section or toe that was used. Tail-clips comprised of the distal 0–2 cm segment performed the best across all salamander species, explaining between 82 and 92 % of the variation in paired whole-body THg concentrations. Toe-clips were less effective predictors of frog THg concentrations, but THg concentrations in outer rear toes accounted for up to 79 % of the variability in frog whole-body THg concentrations. These findings suggest non-lethal sampling of tails and toes has potential applications for monitoring contaminant exposure and risk in amphibians, but care must be taken to ensure consistent collection and interpretation of samples.

Phalangeal joints kinematics during ostrich (Struthio camelus) locomotion

PubMed Central

Ji, Qiaoli; Luo, Gang; Xue, Shuliang; Ma, Songsong; Li, Jianqiao

2017-01-01

The ostrich is a highly cursorial bipedal land animal with a permanently elevated metatarsophalangeal joint supported by only two toes. Although locomotor kinematics in walking and running ostriches have been examined, these studies have been largely limited to above the metatarsophalangeal joint. In this study, kinematic data of all major toe joints were collected from gaits with double support (slow walking) to running during stance period in a semi-natural setup with two selected cooperative ostriches. Statistical analyses were conducted to investigate the effect of locomotor gait on toe joint kinematics. The MTP3 and MTP4 joints exhibit the largest range of motion whereas the first phalangeal joint of the 4th toe shows the largest motion variability. The interphalangeal joints of the 3rd and 4th toes present very similar motion patterns over stance phases of slow walking and running. However, the motion patterns of the MTP3 and MTP4 joints and the vertical displacement of the metatarsophalangeal joint are significantly different during running and slow walking. Because of the biomechanical requirements, osctriches are likely to select the inverted pendulum gait at low speeds and the bouncing gait at high speeds to improve movement performance and energy economy. Interestingly, the motions of the MTP3 and MTP4 joints are highly synchronized from slow to fast locomotion. This strongly suggests that the 3rd and 4th toes really work as an “integrated system” with the 3rd toe as the main load bearing element whilst the 4th toe as the complementary load sharing element with a primary role to ensure the lateral stability of the permanently elevated metatarsophalangeal joint. PMID:28097064

Process-oriented modelling to identify main drivers of erosion-induced carbon fluxes

NASA Astrophysics Data System (ADS)

Wilken, Florian; Sommer, Michael; Van Oost, Kristof; Bens, Oliver; Fiener, Peter

2017-05-01

Coupled modelling of soil erosion, carbon redistribution, and turnover has received great attention over the last decades due to large uncertainties regarding erosion-induced carbon fluxes. For a process-oriented representation of event dynamics, coupled soil-carbon erosion models have been developed. However, there are currently few models that represent tillage erosion, preferential water erosion, and transport of different carbon fractions (e.g. mineral bound carbon, carbon encapsulated by soil aggregates). We couple a process-oriented multi-class sediment transport model with a carbon turnover model (MCST-C) to identify relevant redistribution processes for carbon dynamics. The model is applied for two arable catchments (3.7 and 7.8 ha) located in the Tertiary Hills about 40 km north of Munich, Germany. Our findings indicate the following: (i) redistribution by tillage has a large effect on erosion-induced vertical carbon fluxes and has a large carbon sequestration potential; (ii) water erosion has a minor effect on vertical fluxes, but episodic soil organic carbon (SOC) delivery controls the long-term erosion-induced carbon balance; (iii) delivered sediments are highly enriched in SOC compared to the parent soil, and sediment delivery is driven by event size and catchment connectivity; and (iv) soil aggregation enhances SOC deposition due to the transformation of highly mobile carbon-rich fine primary particles into rather immobile soil aggregates.

Agility, gnosis, and graphaesthesia for the toes and fingers in children: normative data (ages 7-14 years).

PubMed

Richards, P M; Persinger, M A

2004-01-01

The differential representation of the toes/feet and fingers/hands along the medial and lateral surfaces of the cerebral cortices, respectively, may have diagnostic utility. Normative data for errors for toe and finger graphaesthesia and gnosis, as well as foot and finger agility, were collected for 86 children (ages 7 to 14). The fingers were more agile than the feet, and the right side of the body was more agile than the left side, regardless of age. A marked improvement in toe gnosis, but not in finger gnosis occurred in children after 11-12 years of age. A statistically significant interaction between laterality and gender was due to the greater numbers of errors for both toe and finger gnosis, displayed by girls for the left sides of their bodies compared to their right sides. This discrepancy was not significant for boys.

Idiopathic toe walking.

PubMed

Oetgen, Matthew E; Peden, Sean

2012-05-01

Toe walking is a bilateral gait abnormality in which a normal heel strike is absent and most weight bearing occurs through the forefoot. This abnormality may not be pathologic in patients aged <2 years, but it is a common reason for referral to an orthopaedic surgeon. Toe walking can be caused by several neurologic and developmental abnormalities and may be the first sign of a global developmental problem. Cases that lack a definitive etiology are categorized as idiopathic. A detailed history, with careful documentation of the developmental history, and a thorough physical examination are required in the child with a primary report of toe walking. Treatment is based on age and the severity of the abnormality. Management includes observation, stretching, casting, bracing, chemodenervation, and surgical lengthening of the gastrocnemius-soleus complex and/or Achilles tendon. An understanding of idiopathic toe walking as well as treatment options and their outcomes can help the physician individualize treatment to achieve optimal results.

Improvements in Modeling Thruster Plume Erosion Damage to Spacecraft Surfaces

NASA Technical Reports Server (NTRS)

Soares, Carlos; Olsen, Randy; Steagall, Courtney; Huang, Alvin; Mikatarian, Ron; Myers, Brandon; Koontz, Steven; Worthy, Erica

2015-01-01

Spacecraft bipropellant thrusters impact spacecraft surfaces with high speed droplets of unburned and partially burned propellant. These impacts can produce erosion damage to optically sensitive hardware and systems (e.g., windows, camera lenses, solar cells and protective coatings). On the International Space Station (ISS), operational constraints are levied on the position and orientation of the solar arrays to mitigate erosion effects during thruster operations. In 2007, the ISS Program requested evaluation of erosion constraint relief to alleviate operational impacts due to an impaired Solar Alpha Rotary Joint (SARJ). Boeing Space Environments initiated an activity to identify and remove sources of conservatism in the plume induced erosion model to support an expanded range of acceptable solar array positions ? The original plume erosion model over-predicted plume erosion and was adjusted to better correlate with flight experiment results. This paper discusses findings from flight experiments and the methodology employed in modifying the original plume erosion model for better correlation of predictions with flight experiment data. The updated model has been successful employed in reducing conservatism and allowing for enhanced flexibility in ISS solar array operations.

Physical erosion modelling of complex morphodynamics in the upper Val d'Orcia: a combination of EROSION 3D, UAV, SFM and CANUPO

NASA Astrophysics Data System (ADS)

Buchholz, Arno; Kaiser, Andreas; Neugirg, Fabian; Schindewolf, Marcus; Schmidt, Jürgen

2017-04-01

Throughout the Mediterranean Basin soil erosion is both a widely spread and a landscape shaping process. In order to increase the understanding of morphodynamics inside large Italian badland areas, so called Calanchi, the process based erosion model EROSION 3D was parameterized by artificial rainfall simulations, soil sampling and an UAV based high resolution digital elevation model. Vegetation structures were removed with the CANUPO-classifier in CloudCompare. The rainfall experiments proved to be a convenient but costly tool for deriving the model input parameters. While building up the model, different composition of the inhomogeneous soil surface was considered. A diverse behavior against erosion by water was observed. The results showed that the deposition surfaces of rotational or translational slides, besides calanco depth contour, tend to degrade. Although these deposits present a comparatively low bulk density, they reduce the infiltration due to soil surface clogging and cause less erosion resistances. The differential consideration of erosion sub-processes turns out as particularly challenging. The simulation of a reference year showed an annual soil export from the catchment of 43 t/ha, which corresponds to an average surface lowering of 3 mm. Sheet erosion represents an amount of about 5% of the total erosion of badlands. Furthermore, infiltration depth, amount of runoff, sediment concentration, and grain size composition of the deposits were calculated. This study makes a contribution to the understanding of denudation processes in Calanchi badlands. The presented process-based modeling of badlands is contributing a new aspect to erosion research.

A (137)Cs erosion model with moving boundary.

PubMed

Yin, Chuan; Ji, Hongbing

2015-12-01

A novel quantitative model of the relationship between diffused concentration changes and erosion rates using assessment of soil losses was developed. It derived from the analysis of surface soil (137)Cs flux variation under persistent erosion effect and based on the principle of geochemistry kinetics moving boundary. The new moving boundary model improves the basic simplified transport model (Zhang et al., 2008), and mainly applies to uniform rainfall areas which show a long-time soil erosion. The simulation results for this kind of erosion show under a long-time soil erosion, the influence of (137)Cs concentration will decrease exponentially with increasing depth. Using the new model fit to the measured (137)Cs depth distribution data in Zunyi site, Guizhou Province, China which has typical uniform rainfall provided a good fit with R(2) = 0.92. To compare the soil erosion rates calculated by the simple transport model and the new model, we take the Kaixian reference profile as example. The soil losses estimated by the previous simplified transport model are greater than those estimated by the new moving boundary model, which is consistent with our expectations. Copyright © 2015 Elsevier Ltd. All rights reserved.

Treatment of Idiopathic Toe-Walking in Children with Autism Using GaitSpot Auditory Speakers and Simplified Habit Reversal

ERIC Educational Resources Information Center

Marcus, Ann; Sinnott, Brigit; Bradley, Stephen; Grey, Ian

2010-01-01

This study aimed to examine the effectiveness of a simplified habit reversal procedure (SHR) using differential reinforcement of incompatible behaviour (DRI) and a stimulus prompt (GaitSpot Auditory Squeakers) to reduce the frequency of idiopathic toe-walking (ITW) and increase the frequency of correct heel-to-toe-walking in three children with…

16 CFR Figures 6 and 7 to Part 1512 - Toe Clearance and Chain Guard Requirements

Code of Federal Regulations, 2011 CFR

2011-01-01

... 16 Commercial Practices 2 2011-01-01 2011-01-01 false Toe Clearance and Chain Guard Requirements 6 Figures 6 and 7 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Figs. 6 and 7 Figures 6 and 7 to Part 1512—Toe...

16 CFR Figures 6 and 7 to Part 1512 - Toe Clearance and Chain Guard Requirements

Code of Federal Regulations, 2010 CFR

2010-01-01

... 16 Commercial Practices 2 2010-01-01 2010-01-01 false Toe Clearance and Chain Guard Requirements 6 Figures 6 and 7 to Part 1512 Commercial Practices CONSUMER PRODUCT SAFETY COMMISSION FEDERAL HAZARDOUS SUBSTANCES ACT REGULATIONS REQUIREMENTS FOR BICYCLES Pt. 1512, Figs. 6 and 7 Figures 6 and 7 to Part 1512—Toe...

76 FR 2648 - Hand Trucks and Certain Parts Thereof From the People's Republic of China: Preliminary Results of...

Federal Register 2010, 2011, 2012, 2013, 2014

2011-01-14

... the vertical frame, the handling area and the projecting edges or toe plate, and any combination... edge or edges, or toe plate, perpendicular or angled to the vertical frame, at or near the lower section of the vertical frame. The projecting edge or edges, or toe plate, slides under a load for...

Toe-to-hand transfer in symbrachydactyly.

PubMed

Richardson, Philip W F; Johnstone, Bruce R; Coombs, Christopher J

2004-07-01

Symbrachydactyly, or central atypical cleft, is classified as a failure of formation. For the adactylous or monodactylous forms, free toe transfer is the treatment of choice. We present 18 free toe transfers in 13 patients for symbrachydactyly. Despite abnormal anatomy, the functional building blocks have always been available and transfer technically possible. The result has been improved function and high levels of parental satisfaction.

Foot agility and toe gnosis/graphaesthesia as potential indicators of integrity of the medial cerebral surface: normative data and comparison with clinical populations.

PubMed

Persinger, M A; Richards, P M

1995-06-01

A protocol was designed to identify quantitative indicators of the function of the medial surfaces of the cerebral hemispheres. Normative data were collected from 40 volunteers for foot agility, toe gnosis, and toe graphaesthesia. A total of 100 patients (most of whom had been referred for possible closed-head injuries) completed thorough neuropsychological and cognitive assessments. Deficits for toe graphaesthesia were most consistently correlated with general brain impairment and with scores for tasks whose normal performance requires the integrity of structures within the dorsal half of the medial cerebral hemispheres.

Rupture of the extensor hood of the fifth toe: a rare injury.

PubMed

Venturini, Sara; Gaba, Suchi; Mangwani, Jitendra

2017-02-27

Closed injuries of the extensor hood of the lesser toes are rare and seldom reported in the literature. We present the case of a woman aged 25 years who presented to the orthopaedic fracture clinic with a 2-week history of pain in the left fifth toe and inability to extend following a ballet dancing session. Investigations showed no fracture on plain radiographs, but an ultrasound scan demonstrated rupture to the extensor hood of the little toe. Successful surgical repair of the extensor hood was performed, and the patient made a good recovery with return to dancing activities. 2017 BMJ Publishing Group Ltd.

Advances in soil erosion research: processes, measurement, and modeling

USDA-ARS?s Scientific Manuscript database

Soil erosion by the environmental agents of water and wind is a continuing global menace that threatens the agricultural base that sustains our civilization. Members of ASABE have been at the forefront of research to understand erosion processes, measure erosion and related processes, and model very...

Quantification Of Erosion Rates Of Agriculturally Used Soils By Artificial

NASA Astrophysics Data System (ADS)

Jha, Abhinand

2010-05-01

0.0.1 1. Introduction to soil erosion measurement by radionuclides Soil erosion by water, wind and tillage affects both agriculture and the natural environment. Studying this phenomenon would be one of the advancements in science. Soil erosion occurs worldwide and since the last two decades it has been a main topic of discussion all over the world. The use of environmental radionuclides such as 90Sr, 137Cs to study medium term soil erosion (40 yrs) started in the early 1990's. Using these new techniques better knowledge about erosion can be gained and this knowledge can be implemented for erosion risk management. The erosion and sedimentation study by using man-made and natural radioisotopes is a key technique, which has developed over the past 30 years. Fallout 137Cs and Cosmogenic 7Be are radionuclides that have been used to provide independent measurements of soil-erosion and sediment-deposition rates and patterns [1] [2] [3] [4]. Erosion measurements using radionuclides 137Cs, 7Be Caesium-137 from atmospheric nuclear-weapons tests in the 1950s and 1960s (Fig.1) is a unique tracer of erosion and sedimentation, since there are no natural sources of 137Cs. Unique events such as the Chernobyl accident in April 1986 caused regional dispersal of 137Cs that affects the total global deposition budget. This yearly pattern of fallout can be used to develop a chronology of deposition horizons in lakes, reservoirs, and floodplains. 137Cs can be easily measured by gamma spectroscopy. Using 137Cs is a fast and cheap method to study erosion-deposition processes compared to the traditional methods like silt bags. PIC Figure 1: Global 137Cs fallout (Modified from SAAS Bulletin 353, Part E, DDR, 1986) When 137Cs, 7Be reach the soil surface by wet and dry deposition, they are quickly and strongly adsorbed by ion exchange and are essentially non exchangeable in most environments. Each radionuclide is distributed differently in the soil because of differences in half-lives (30 yrs for 137Cs and 53 days for 7Be), delivery rates, delivery histories, and land use (Fig. 2). An Physical processes, such as water and wind, are the dominant factors moving 137Cs, 7Be tagged soil particles within and between landscape compartments. PIC Figure 2: Generalized sketch illustrating the distributions of 137Cs and 7Be in tilled and undisturbed soils 2 Erosion study at Young Moraine regions of Germany Recently, a study had been performed to evaluate erosion rates in a typical pattern of landscapes in the Young Moraine regions of North-East Germany [5]. The 137Cs concentrations were measured at selected sampling points of various study sites. Among the areas selected for sampling was Basedow, which is a cultivated area, situated north of Berlin. During a master thesis study at university of Bremen in the academic year 2008-2009 [6] a second sampling campaign was performed at the same study site and 137Cs and 7Be concentrations were measured. Two mathematical models (a proportional model and a mass balance model) were applied to estimate erosion or deposition rates giving a distinction between uncultivated or essentially undisturbed soils and cultivated or soils under permanent pasture (Fig.3A). An improved depositional model was developed during this study. The simulation results from this model are presented in Fig.4. Due to the half-life (53.2 days) of 7Be, a mass balance model was developed and used to calculate erosion rates from 7Be (Fig.3B). PIC Figure 3: A: Erosion rates for 137Cs calculated by mass balance model. B: Erosion rates calculated with mass balance model using the 7Be data at Basedow (2008). The results verify that there is long term erosion as a result of wind, water and agricultural practices. The annual erosion rates at Basedow calculated using a mass balance and a proportional model were in the range between 30-50 t ha-1yr-1. These values were comparable to the erosion rates calculated in the previous study [5] by the models mentioned above. PIC Figure 4: Profiles of sediment calculated for different erosion rates by Cs-137 within the ploughed soil 3 Conclusions and outlook Erosion rates for agricultural soils at Young Moraine regions of North-East Germany were determined by using two radionuclides, 137Cs and 7Be. In combination, the two radionuclides provide a valuable means of investigating soil erosion and assessing erosion risk in the study area. Potentials and limitations of the erosion measurement techniques using radiotracers are discussed in this study. The models used to quantify erosion rates using 137Cs and 7Be were studied. Erosion rates calculated by theses models are difficult to measure over a period of 50 years. A validation of these erosion rates for the time period (50 years) used in the 137Cs-based models will give a new perspective to the use of soil erosion modeling. Most of the regions in India are suffering from high erosion rates [7]. By using the new techniques in erosion quantification the land management practices can be improved and the erosion risk can be reduced in India.

RUSLE2015, GIS-RWEQ and CENTURY: new modelling integration for soil loss and carbon fluxes at European scale

NASA Astrophysics Data System (ADS)

Panagos, Panos; Borrelli, Pasquale; Lugato, Emanuele

2016-04-01

Land degradation through erosion has been identified as major threat to European soils and agriculture. During the last years, the Directorates General for Agriculture and for Environment (plus EUROSTAT) require formal assessments and indicators on the state of soil erosion for the European Union. Moreover, the European Soil Data Centre (ESDAC) is the main data repository for soil threats at European scale. To meet these needs we have worked with recognized research institutes and scientists to develop a series of pan-EU modelling tools that estimate soil erosion by water and wind. Over the past three years, the European Commission Joint Research Centre has worked to develop a modified RUSLE modelling approach, named RUSLE2015 and the necessary input factors. These have all been peer reviewed and published as individual papers in different refereed journals. The published soil erodibility map for Europe has been modelled with the latest state of the art soil data (LUCAS) and a robust geo-statistical model (Science of Total Environment, 479-480: 189-200). Rainfall erosivity has been modelled after an extensive data collection of high temporal resolution rainfall data and the compilation of Rainfall Erosivity Database at European Scale (REDES) (Science of Total Environment, 511: 801-814). Cover-Management factor has been modelled taking into account crop composition, management practices (reduced tillage, plant residues, cover crops) and remote sensing data on vegetation density (Land Use policy, 48C: 38-50). Topography has been modelled with the recently published Digital Elevation Model at 25m resolution (Geosciences, 5: 117-126). Conservation and support practices have included the Good Agricultural Environmental Condition (GAEC database) and the 270,000 earth observations of LUCAS survey (Environmental Science & Policy 51: 23-34). The new assessment of soil erosion by water in Europe has been recently published (Environmental Science & Policy. 54: 438-447) and subsequently the core message focusing on soil erosion in agricultural lands was published in a recent correspondence in Nature (Nature, 526, 195). Additionally, the soil erosion potential for the European Union's forests was modelled using the high-resolution Global Forest Cover Loss map (2000-2012) and taking into consideration the lodging, forest cuts and forest fires (Ecological Indicators, 60:1208-1220). The first qualitative assessment of wind erosion at European scale has been done using the Index of Land Susceptibility to Wind Erosion (ILSWE) (Sustainability, 7(7): 8823-8836). The wind-erodible fraction of soil (EF) is one of the key parameters for estimating the susceptibility of soil to wind erosion (Geoderma, 232-234: 471-478). ILSWE was created by combining spatiotemporal variations of the most influential wind erosion factors such as climatic erosivity, soil erodibility, vegetation cover and landscape roughness) (Land Degradation & Development, 10.1002/ldr.2318). The quantitative assessment of wind erosion has been concluded recently using Revised Wind Erosion Equation (GIS-RWEQ). Modelling the lateral carbon fluxes due to soil erosion both at national scale (Land Use Policy, 50: 408-421) and at European scale (Global Change Biology, 10.1111/gcb.13198) is an important milestone in climate change perspective. We coupled soil erosion into a biogeochemistry model, running at 1 km2 resolution across the agricultural soils of the European Union (EU). In the future, the soil erosion (by water and wind) modelling activities will incorporate temporal variability, sediment transport and economic assessments of land degradation.

Plantar-plate disruptions: "the severe turf-toe injury." three cases in contact athletes.

PubMed

Drakos, Mark C; Fiore, Russell; Murphy, Conor; DiGiovanni, Christopher W

2015-05-01

To present 3 cases of plantar-plate rupture and turf-toe injury in contact athletes at 1 university and to discuss appropriate diagnosis and treatment algorithms for each case. Turf toe is a common injury in athletes participating in outdoor cutting sports. However, it has been used as an umbrella term to describe many different injuries of the great toe. In some cases, the injury can be so severe that the plantar plate and sesamoid apparatus may be ruptured. These patients may be better managed with surgery than with traditional nonoperative interventions. Turf toe, plantar-plate disruption, sesamoid fracture. For stable injuries in which the plantar plate is not completely disrupted, nonoperative treatment with casting or a stiff-soled shoe, gradual weight bearing, and rehabilitation is the best practice. Unstable injuries require surgical intervention and plantar-plate repair. Turf toe and injury to the first metatarsophalangeal joint are relatively common injuries in athletes, but few researchers have detailed the operative and nonoperative treatments of plantar-plate disruption in these patients. We examine 3 cases that occurred over 4 seasons on a collegiate football team. Turf toe represents a wide array of pathologic conditions involving the first metatarsophalangeal joint. Stress and instability testing are key components to assess in determining whether surgical intervention is warranted to restore optimal function. Stiffer-soled shoes or shoes with steel-plate insertions may help to prevent these injuries and are useful tools for protection during the rehabilitation period.

Fractal Approach to Erosion Threshold of Bentonites

NASA Astrophysics Data System (ADS)

Xu, Y. F.; Li, X. Y.

Bentonite has been considered as a candidate buffer material for the disposal of high-level radioactive waste (HLW) because of its low permeability, high sorption capacity, self-sealing characteristics and durability in a natural environment. Bentonite erosion caused by groundwater flow may take place at the interface of the compacted bentonite and fractured granite. Surface erosion of bentonite flocs is represented typically as an erosion threshold. Predicting the erosion threshold of bentonite flocs requires taking into account cohesion, which results from interactions between clay particles. Beyond the usual dependence on grain size, a significant correlation between erosion threshold and porosity measurements is confirmed for bentonite flocs. A fractal model for erosion threshold of bentonite flocs is proposed. Cohesion forces, the long-range van der Waals interaction between two clay particles are taken as the resource of the erosion threshold. The model verification is conducted by the comparison with experiments published in the literature. The results show that the proposed model for erosion threshold is in good agreement with the experimental data.

Performance Evaluation and Modeling of Erosion Resistant Turbine Engine Thermal Barrier Coatings

NASA Technical Reports Server (NTRS)

Miller, Robert A.; Zhu, Dongming; Kuczmarski, Maria

2008-01-01

The erosion resistant turbine thermal barrier coating system is critical to the rotorcraft engine performance and durability. The objective of this work was to determine erosion resistance of advanced thermal barrier coating systems under simulated engine erosion and thermal gradient environments, thus validating a new thermal barrier coating turbine blade technology for future rotorcraft applications. A high velocity burner rig based erosion test approach was established and a new series of rare earth oxide- and TiO2/Ta2O5- alloyed, ZrO2-based low conductivity thermal barrier coatings were designed and processed. The low conductivity thermal barrier coating systems demonstrated significant improvements in the erosion resistance. A comprehensive model based on accumulated strain damage low cycle fatigue is formulated for blade erosion life prediction. The work is currently aiming at the simulated engine erosion testing of advanced thermal barrier coated turbine blades to establish and validate the coating life prediction models.

75 FR 75961 - Notice of Implementation of the Wind Erosion Prediction System for Soil Erodibility System...

Federal Register 2010, 2011, 2012, 2013, 2014

2010-12-07

... Wind Erosion Prediction System for Soil Erodibility System Calculations for the Natural Resources... Erosion Prediction System (WEPS) for soil erodibility system calculations scheduled for implementation for... computer model is a process-based, daily time-step computer model that predicts soil erosion via simulation...

Can foot anthropometric measurements predict dynamic plantar surface contact area?

PubMed

McPoil, Thomas G; Vicenzino, Bill; Cornwall, Mark W; Collins, Natalie

2009-10-28

Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area. Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 +/- 3.5 years). The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform. A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p < 0.0001)). A three variable model was also found to describe the relationship between the foot measures/ratio and plantar contact area minus the toe region (R2 = 0.76, p < 0.0001). The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region.

Can foot anthropometric measurements predict dynamic plantar surface contact area?

PubMed Central

2009-01-01

Background Previous studies have suggested that increased plantar surface area, associated with pes planus, is a risk factor for the development of lower extremity overuse injuries. The intent of this study was to determine if a single or combination of foot anthropometric measures could be used to predict plantar surface area. Methods Six foot measurements were collected on 155 subjects (97 females, 58 males, mean age 24.5 ± 3.5 years). The measurements as well as one ratio were entered into a stepwise regression analysis to determine the optimal set of measurements associated with total plantar contact area either including or excluding the toe region. The predicted values were used to calculate plantar surface area and were compared to the actual values obtained dynamically using a pressure sensor platform. Results A three variable model was found to describe the relationship between the foot measures/ratio and total plantar contact area (R2 = 0.77, p < 0.0001)). A three variable model was also found to describe the relationship between the foot measures/ratio and plantar contact area minus the toe region (R2 = 0.76, p < 0.0001). Conclusion The results of this study indicate that the clinician can use a combination of simple, reliable, and time efficient foot anthropometric measurements to explain over 75% of the plantar surface contact area, either including or excluding the toe region. PMID:19863799

Towards estimates of future rainfall erosivity in Europe based on REDES and WorldClim datasets

NASA Astrophysics Data System (ADS)

Panagos, Panos; Ballabio, Cristiano; Meusburger, Katrin; Spinoni, Jonathan; Alewell, Christine; Borrelli, Pasquale

2017-05-01

The policy requests to develop trends in soil erosion changes can be responded developing modelling scenarios of the two most dynamic factors in soil erosion, i.e. rainfall erosivity and land cover change. The recently developed Rainfall Erosivity Database at European Scale (REDES) and a statistical approach used to spatially interpolate rainfall erosivity data have the potential to become useful knowledge to predict future rainfall erosivity based on climate scenarios. The use of a thorough statistical modelling approach (Gaussian Process Regression), with the selection of the most appropriate covariates (monthly precipitation, temperature datasets and bioclimatic layers), allowed to predict the rainfall erosivity based on climate change scenarios. The mean rainfall erosivity for the European Union and Switzerland is projected to be 857 MJ mm ha-1 h-1 yr-1 till 2050 showing a relative increase of 18% compared to baseline data (2010). The changes are heterogeneous in the European continent depending on the future projections of most erosive months (hot period: April-September). The output results report a pan-European projection of future rainfall erosivity taking into account the uncertainties of the climatic models.

Towards estimates of future rainfall erosivity in Europe based on REDES and WorldClim datasets.

PubMed

Panagos, Panos; Ballabio, Cristiano; Meusburger, Katrin; Spinoni, Jonathan; Alewell, Christine; Borrelli, Pasquale

2017-05-01

The policy requests to develop trends in soil erosion changes can be responded developing modelling scenarios of the two most dynamic factors in soil erosion, i.e. rainfall erosivity and land cover change. The recently developed Rainfall Erosivity Database at European Scale (REDES) and a statistical approach used to spatially interpolate rainfall erosivity data have the potential to become useful knowledge to predict future rainfall erosivity based on climate scenarios. The use of a thorough statistical modelling approach (Gaussian Process Regression), with the selection of the most appropriate covariates (monthly precipitation, temperature datasets and bioclimatic layers), allowed to predict the rainfall erosivity based on climate change scenarios. The mean rainfall erosivity for the European Union and Switzerland is projected to be 857 MJ mm ha -1  h -1  yr -1 till 2050 showing a relative increase of 18% compared to baseline data (2010). The changes are heterogeneous in the European continent depending on the future projections of most erosive months (hot period: April-September). The output results report a pan-European projection of future rainfall erosivity taking into account the uncertainties of the climatic models.

Real-Time Measurements of Aft Dome Insulation Erosion on Space Shuttle Reusable Solid Rocket Motor

NASA Technical Reports Server (NTRS)

McWhorter, Bruce; Ewing, Mark; Albrechtsen, Kevin; Noble, Todd; Longaker, Matt

2004-01-01

Real-time erosion of aft dome internal insulation was measured with internal instrumentation on a static test of a lengthened version of the Space Shuffle Reusable Solid Rocket Motor (RSRM). This effort marks the first time that real-time aft dome insulation erosion (Le., erosion due to the combined effects of thermochemical ablation and mechanical abrasion) was measured in this kind of large motor static test [designated as Engineering Test Motor number 3 (ETM3)I. This paper presents data plots of the erosion depth versus time. The data indicates general erosion versus time behavior that is in contrast to what would be expected from earlier analyses. Engineers have long known that the thermal environment in the aft dome is severe and that the resulting aft dome insulation erosion is significant. Models of aft dome erosion involve a two-step process of computational fluid dynamics (CFD) modeling and material ablation modeling. This modeling effort is complex. The time- dependent effects are difficult to verify with only prefire and postfire insulation measurements. Nozzle vectoring, slag accumulation, and changing boundary conditions will affect the time dependence of aft dome erosion. Further study of this data and continued measurements on future motors will increase our understanding of the aft dome flow and erosion environment.

Advances in wind erosion modelling in Europe

NASA Astrophysics Data System (ADS)

Borrelli, Pasquale; Lugato, Emanuele; Alewell, Christine; Montanarella, Luca; Panagos, Panos

2017-04-01

Soil erosion by wind is a serious environmental problem often resulting in severe forms of soil degradation. Wind erosion is also a phenomenon relevant for Europe, although this land degradation process has been overlooked until very recently. The state-of-the-art literature presents wind erosion as a process that locally affects the semi-arid areas of the Mediterranean region as well as the temperate climate areas of the northern European countries. Actual observations, field measurements and modelling assessments, however, are all extremely limited and highly unequally distributed across Europe. As a result, we currently lack comprehensive understanding about where and when wind erosion occurs in Europe, and the intensity of erosion that poses a threat to agricultural productivity. Today's challenge is to integrate the insights of local experiments and field-scale models into a new generation of large-scale wind erosion models. While naturally being less accurate than field-scale models, these large-scale modelling approaches still provide essential knowledge about where and when wind erosion occurs and can disclose the level of risk for agricultural productivity in specific areas. Here, we present a geographic information system (GIS) version of the RWEQ (named GIS-RWEQ) to quantitatively assess soil loss by wind over large study areas (Land Degradation & Development, DOI: 10.1002/ldr.2588). The model designed to predict the daily soil loss potential at a ca. 1 km2 spatial resolution shows high consistency with local measurements reported in literature. The average soil loss predicted by GIS-RWEQ for the European arable land totals 62 million Mg yr-1, with an average area-specific soil loss of 0.53 Mg yr-1. The JRC model RUSLE2015, for the same area estimates 295 million Mg yr-1 of soil loss due to water erosion. Notably, soil loss by wind erosion in the European arable land could be as high as 20% of water erosion, even though the areas affected are mainly concentrated in hotspots.

Efficacy of bedrock erosion by subglacial water flow

NASA Astrophysics Data System (ADS)

Beaud, F.; Flowers, G. E.; Venditti, J. G.

2015-09-01

Bedrock erosion by sediment-bearing subglacial water remains little-studied, however the process is thought to contribute to bedrock erosion rates in glaciated landscapes and is implicated in the excavation of tunnel valleys and the incision of inner gorges. We adapt physics-based models of fluvial abrasion to the subglacial environment, assembling the first model designed to quantify bedrock erosion caused by transient subglacial water flow. The subglacial drainage model consists of a one-dimensional network of cavities dynamically coupled to one or several Röthlisberger channels (R-channels). The bedrock erosion model is based on the tools and cover effect, whereby particles entrained by the flow impact exposed bedrock. We explore the dependency of glacial meltwater erosion on the structure and magnitude of water input to the system, the ice geometry and the sediment supply. We find that erosion is not a function of water discharge alone, but also depends on channel size, water pressure and on sediment supply, as in fluvial systems. Modelled glacial meltwater erosion rates are one to two orders of magnitude lower than the expected rates of total glacial erosion required to produce the sediment supply rates we impose, suggesting that glacial meltwater erosion is negligible at the basin scale. Nevertheless, due to the extreme localization of glacial meltwater erosion (at the base of R-channels), this process can carve bedrock (Nye) channels. In fact, our simulations suggest that the incision of bedrock channels several centimetres deep and a few meters wide can occur in a single year. Modelled incision rates indicate that subglacial water flow can gradually carve a tunnel valley and enhance the relief or even initiate the carving of an inner gorge.

Modelling rainfall erosion resulting from climate change

NASA Astrophysics Data System (ADS)

Kinnell, Peter

2016-04-01

It is well known that soil erosion leads to agricultural productivity decline and contributes to water quality decline. The current widely used models for determining soil erosion for management purposes in agriculture focus on long term (~20 years) average annual soil loss and are not well suited to determining variations that occur over short timespans and as a result of climate change. Soil loss resulting from rainfall erosion is directly dependent on the product of runoff and sediment concentration both of which are likely to be influenced by climate change. This presentation demonstrates the capacity of models like the USLE, USLE-M and WEPP to predict variations in runoff and erosion associated with rainfall events eroding bare fallow plots in the USA with a view to modelling rainfall erosion in areas subject to climate change.

The Development and Evaluation of an Online Formative Assessment upon Single-Player Game in E-Learning Environment

ERIC Educational Resources Information Center

Tsai, Fu-Hsing

2013-01-01

This study developed a game-based formative assessment, called tic-tac-toe quiz for single-player version (TRIS-Q-SP), in an energy education e-learning system. This assessment game combined tic-tac-toe with online assessment, and revised the rule of tic-tac-toe for stimulating students to use online formative assessment actively. Additionally, to…

Modeling streamflow in a snow-dominated forest watershed using the Water Erosion Prediction Project (WEPP) model

USDA-ARS?s Scientific Manuscript database

The Water Erosion Prediction Project (WEPP) model was originally developed for hillslope and small watershed applications. The model simulates complex interactive processes influencing erosion, such as surface runoff, soil-water changes, vegetation growth and senescence, and snow accumulation and me...

The Rangeland Hydrology and Erosion Model: A dynamic approach for predicting soil loss on rangelands

USDA-ARS?s Scientific Manuscript database

In this study we present the improved Rangeland Hydrology and Erosion Model (RHEM V2.3), a process-based erosion prediction tool specific for rangeland application. The article provides the mathematical formulation of the model and parameter estimation equations. Model performance is assessed agains...

Modelling topographic potential for erosion and deposition using GIS

Treesearch

Helena Mitasova; Louis R. Iverson

1996-01-01

Modelling of erosion and deposition in complex terrain within a geographical information system (GIS) requires a high resolution digital elevation model (DEM), reliable estimation of topographic parameters, and formulation of erosion models adequate for digital representation of spatially distributed parameters. Regularized spline with tension was integrated within a...

Development of Erosive Burning Models for CFD Predictions of Solid Rocket Motor Internal Environments

NASA Technical Reports Server (NTRS)

Wang, Qun-Zhen

2003-01-01

Four erosive burning models, equations (11) to (14). are developed in this work by using a power law relationship to correlate (1) the erosive burning ratio and the local velocity gradient at propellant surfaces; (2) the erosive burning ratio and the velocity gradient divided by centerline velocity; (3) the erosive burning difference and the local velocity gradient at propellant surfaces; and (4) the erosive burning difference and the velocity gradient divided by centerline velocity. These models depend on the local velocity gradient at the propellant surface (or the velocity gradient divided by centerline velocity) only and, unlike other empirical models, are independent of the motor size. It was argued that, since the erosive burning is a local phenomenon occurring near the surface of the solid propellant, the erosive burning ratio should be independent of the bore diameter if it is correlated with some local flow parameters such as the velocity gradient at the propellant surface. This seems to be true considering the good results obtained by applying these models, which are developed from the small size 5 inch CP tandem motor testing, to CFD simulations of much bigger motors.

Effect of pylon cross-sectional geometries on propulsion integration for a low-wing transport

NASA Technical Reports Server (NTRS)

Ingraldi, Anthony M.; Naik, Dinesh A.; Pendergraft, Odis C., Jr.

1993-01-01

An experimental program was conducted in the Langley 16-Foot Transonic Tunnel to evaluate the performance effects of various types of pylons on a 1/17th-scale, low-wing transport model. The model wing was designed for cruise at a Mach number of 0.77 and a lift coefficient of 0.55. The pylons were tested at two wing semispan locations over a range of toe-in angles. The effects of toe-in angle were found to be minimal, but the variation in geometry had a more pronounced effect on the lift characteristics of the model. A pylon whose maximum thickness occurred at the wing trailing edge, known as a compression pylon, proved to be the best choice in terms of retaining the flow characteristics of the wing without pylons. Practical considerations such as structural viability may necessitate modification of the compression pylon concept in order to take advantage of its apparent benefits.

Bedrock river erosion measurements and modelling along a river of the Frontal Himalaya

NASA Astrophysics Data System (ADS)

Lave, Jerome; Dubille, Matthieu

2017-04-01

River incision is a key process in mountains denudation and therefore in landscape evolution models. Despite its importance, most incision models for mountain rivers rely on simplified, or quite empirical relations, and generally only consider annual average values for water discharge and sediment flux. In contrast, very few studies consider mechanistic models at the timescale of a flood, and try to bridge the gap between experimental or theoretical approaches and long term river incision studies. In this contribution, we present observations made during 7 monsoon seasons on fluvial bedrock erosion along the Bakeya river across the Frontal Himalaya in Central Nepal. Along its lower gorge, this river incises alternation of indurated sandstone and less resistant claystone, at Holocene rates larger than 10mm/yr. More importantly, its upper drainage mostly drains through non-cohesive conglomerate which allows, in this specific setting, estimating the bedload characteristics and instantaneous fluxes, i.e. a pre-requisite to test mechanistic models of fluvial erosion. During the study period, we monitored and documented the channel bank erosion in order to understand the amplitude of the erosion processes, their occurrence in relation with hydrology, in order to test time-integrated models of erosion. Besides hydrologic monitoring, erosion measurements were threefold: (1) at the scale of the whole monsoon, plucking and block removal by repeated photo surveys of a 400m long channel reach, (2) detailed microtopographic surveys of channel bedrock elevation along a few sandstone bars to document their abrasion, (3) real time measurement of fluvial bedrock wear to document erosion timing using a new erosion sensor. Results indicate that: 1. Erosion is highly dependent on rock resistance, but on average block detachment and removal is a more efficient process than bedrock attrition, and operates at a rate that permit channel banks downcutting to keep pace with Holocene uplift rate. 2. Both block detachment and attrition processes clearly increase with fluvial shear stress, but non-linearly, in particular through the existence of a minimum threshold. As a result of which bank erosion occur during only a few hours per year during short and very high flood events, which questions the use of average discharge (or drainage area) in many bedrock erosion models. We then propose a semi-physical model of sandstone bars abrasion based on discharge history (HEC-RAS modelling), Rouse suspension model, and experimental measurements on dependency of abrasion rate vs impacting particle size. This model predicts well the timing and the amplitude of both real-time and monsoon average abrasion along the surveyed sandstone bars. This first validation of a model for bank erosion opens large perspective for future work on channel bottom incision modelling using physical models of erosion and their time- and gravel-size-integration, with the objective to introduce more physical rules in landscape evolution models.

A square root ensemble Kalman filter application to a motor-imagery brain-computer interface

PubMed Central

Kamrunnahar, M.; Schiff, S. J.

2017-01-01

We here investigated a non-linear ensemble Kalman filter (SPKF) application to a motor imagery brain computer interface (BCI). A square root central difference Kalman filter (SR-CDKF) was used as an approach for brain state estimation in motor imagery task performance, using scalp electroencephalography (EEG) signals. Healthy human subjects imagined left vs. right hand movements and tongue vs. bilateral toe movements while scalp EEG signals were recorded. Offline data analysis was conducted for training the model as well as for decoding the imagery movements. Preliminary results indicate the feasibility of this approach with a decoding accuracy of 78%–90% for the hand movements and 70%–90% for the tongue-toes movements. Ongoing research includes online BCI applications of this approach as well as combined state and parameter estimation using this algorithm with different system dynamic models. PMID:22255799

Urban Runoff: Model Ordinances for Erosion and Sediment Control

EPA Pesticide Factsheets

The model ordinance in this section borrows language from the erosion and sediment control ordinance features that might help prevent erosion and sedimentation and protect natural resources more fully.

Performance of the SWEEP model affected by estimates of threshold friction velocity

USDA-ARS?s Scientific Manuscript database

The Wind Erosion Prediction System (WEPS) is a process-based model and needs to be verified under a broad range of climatic, soil, and management conditions. Occasional failure of the WEPS erosion submodel (Single-event Wind Erosion Evaluation Program or SWEEP) to simulate erosion in the Columbia Pl...

Neuroleptic-induced "painful legs and moving toes" syndrome: successful treatment with clonazepam and baclofen.

PubMed

Sandyk, R

1990-12-01

The syndrome of "painful legs and moving toes" is characterised by spontaneous causalgic pain in the lower extremities associated with peculiar involuntary movements of the toes and feet. It has been observed after a variety of lesions affecting the posterior nerve roots, the spinal ganglia and the peripheral nerves. The pathophysiology of the syndrome is unknown. I report a patient who developed the syndrome during treatment for schizophrenia with the antipsychotic agent molindone hydrochloride. The patient's response to the combination of clonazepam and baclofen suggests that the pathophysiology of the "painful legs and moving toes" may be linked to impairment of spinal serotonergic and GABA functions.

[Therapy of the peromelic form of symbrachydactyly by double second-toe transplantation].

PubMed

Hülsemann, W; Preisser, P; Habenicht, R; Partecke, B-D

2002-09-01

From 1989 to 2001 eleven children with the peromelic type of symbrachydactyly underwent a staged double second toes transplantation for restoration of two finger rays. The second toe of the feet were transplanted first to the small finger position and in the second step to the thumb position. One failure occurred in the first toe transplantation and another developed a venous thrombosis with partial necrosis and eventually a useless ray. Eight children were reviewed retrospectively in a mean follow-up of 5.3 years. The ability to pinch was restored in four children. In all patients without complications the function of the hand improved and the sensitivity was good.

Runoff as a factor in USLE/RUSLE technology

NASA Astrophysics Data System (ADS)

Kinnell, Peter

2014-05-01

Modelling erosion for prediction purposes started with the development of the Universal Soil Loss Equation the focus of which was the prediction of long term (~20) average annul soil loss from field sized areas. That purpose has been maintained in the subsequent revision RUSLE, the most widely used erosion prediction model in the world. The lack of ability to predict short term soil loss saw the development of so-called process based models like WEPP and EUROSEM which focussed on predicting event erosion but failed to improve the prediction of long term erosion where the RUSLE worked well. One of the features of erosion recognised in the so-called process based modes is the fact that runoff is a primary factor in rainfall erosion and some modifications of USLE/RUSLE model have been proposed have included runoff as in independent factor in determining event erosivity. However, these models have ignored fundamental mathematical rules. The USLE-M which replaces the EI30 index by the product of the runoff ratio and EI30 was developed from the concept that soil loss is the product of runoff and sediment concentration and operates in a way that obeys the mathematical rules upon which the USLE/RUSLE model was based. In accounts for event soil loss better that the EI30 index where runoff values are known or predicted adequately. RUSLE2 now includes a capacity to model runoff driven erosion.

Foot trajectory approximation using the pendulum model of walking.

PubMed

Fang, Juan; Vuckovic, Aleksandra; Galen, Sujay; Conway, Bernard A; Hunt, Kenneth J

2014-01-01

Generating a natural foot trajectory is an important objective in robotic systems for rehabilitation of walking. Human walking has pendular properties, so the pendulum model of walking has been used in bipedal robots which produce rhythmic gait patterns. Whether natural foot trajectories can be produced by the pendulum model needs to be addressed as a first step towards applying the pendulum concept in gait orthosis design. This study investigated circle approximation of the foot trajectories, with focus on the geometry of the pendulum model of walking. Three able-bodied subjects walked overground at various speeds, and foot trajectories relative to the hip were analysed. Four circle approximation approaches were developed, and best-fit circle algorithms were derived to fit the trajectories of the ankle, heel and toe. The study confirmed that the ankle and heel trajectories during stance and the toe trajectory in both the stance and the swing phases during walking at various speeds could be well modelled by a rigid pendulum. All the pendulum models were centred around the hip with pendular lengths approximately equal to the segment distances from the hip. This observation provides a new approach for using the pendulum model of walking in gait orthosis design.

Development of a statistical model for the determination of the probability of riverbank erosion in a Meditteranean river basin

NASA Astrophysics Data System (ADS)

Varouchakis, Emmanouil; Kourgialas, Nektarios; Karatzas, George; Giannakis, Georgios; Lilli, Maria; Nikolaidis, Nikolaos

2014-05-01

Riverbank erosion affects the river morphology and the local habitat and results in riparian land loss, damage to property and infrastructures, ultimately weakening flood defences. An important issue concerning riverbank erosion is the identification of the areas vulnerable to erosion, as it allows for predicting changes and assists with stream management and restoration. One way to predict the vulnerable to erosion areas is to determine the erosion probability by identifying the underlying relations between riverbank erosion and the geomorphological and/or hydrological variables that prevent or stimulate erosion. A statistical model for evaluating the probability of erosion based on a series of independent local variables and by using logistic regression is developed in this work. The main variables affecting erosion are vegetation index (stability), the presence or absence of meanders, bank material (classification), stream power, bank height, river bank slope, riverbed slope, cross section width and water velocities (Luppi et al. 2009). In statistics, logistic regression is a type of regression analysis used for predicting the outcome of a categorical dependent variable, e.g. binary response, based on one or more predictor variables (continuous or categorical). The probabilities of the possible outcomes are modelled as a function of independent variables using a logistic function. Logistic regression measures the relationship between a categorical dependent variable and, usually, one or several continuous independent variables by converting the dependent variable to probability scores. Then, a logistic regression is formed, which predicts success or failure of a given binary variable (e.g. 1 = "presence of erosion" and 0 = "no erosion") for any value of the independent variables. The regression coefficients are estimated by using maximum likelihood estimation. The erosion occurrence probability can be calculated in conjunction with the model deviance regarding the independent variables tested (Atkinson et al. 2003). The developed statistical model is applied to the Koiliaris River Basin in the island of Crete, Greece. The aim is to determine the probability of erosion along the Koiliaris' riverbanks considering a series of independent geomorphological and/or hydrological variables. Data for the river bank slope and for the river cross section width are available at ten locations along the river. The riverbank has indications of erosion at six of the ten locations while four has remained stable. Based on a recent work, measurements for the two independent variables and data regarding bank stability are available at eight different locations along the river. These locations were used as validation points for the proposed statistical model. The results show a very close agreement between the observed erosion indications and the statistical model as the probability of erosion was accurately predicted at seven out of the eight locations. The next step is to apply the model at more locations along the riverbanks. In November 2013, stakes were inserted at selected locations in order to be able to identify the presence or absence of erosion after the winter period. In April 2014 the presence or absence of erosion will be identified and the model results will be compared to the field data. Our intent is to extend the model by increasing the number of independent variables in order to indentify the key factors favouring erosion along the Koiliaris River. We aim at developing an easy to use statistical tool that will provide a quantified measure of the erosion probability along the riverbanks, which could consequently be used to prevent erosion and flooding events. Atkinson, P. M., German, S. E., Sear, D. A. and Clark, M. J. 2003. Exploring the relations between riverbank erosion and geomorphological controls using geographically weighted logistic regression. Geographical Analysis, 35 (1), 58-82. Luppi, L., Rinaldi, M., Teruggi, L. B., Darby, S. E. and Nardi, L. 2009. Monitoring and numerical modelling of riverbank erosion processes: A case study along the Cecina River (central Italy). Earth Surface Processes and Landforms, 34 (4), 530-546. Acknowledgements This work is part of an on-going THALES project (CYBERSENSORS - High Frequency Monitoring System for Integrated Water Resources Management of Rivers). The project has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: THALES. Investing in knowledge society through the European Social Fund.

Elastic modulus of tree frog adhesive toe pads.

PubMed

Barnes, W Jon P; Goodwyn, Pablo J Perez; Nokhbatolfoghahai, Mohsen; Gorb, Stanislav N

2011-10-01

Previous work using an atomic force microscope in nanoindenter mode indicated that the outer, 10- to 15-μm thick, keratinised layer of tree frog toe pads has a modulus of elasticity equivalent to silicone rubber (5-15 MPa) (Scholz et al. 2009), but gave no information on the physical properties of deeper structures. In this study, micro-indentation is used to measure the stiffness of whole toe pads of the tree frog, Litoria caerulea. We show here that tree frog toe pads are amongst the softest of biological structures (effective elastic modulus 4-25 kPa), and that they exhibit a gradient of stiffness, being stiffest on the outside. This stiffness gradient results from the presence of a dense network of capillaries lying beneath the pad epidermis, which probably has a shock absorbing function. Additionally, we compare the physical properties (elastic modulus, work of adhesion, pull-off force) of the toe pads of immature and adult frogs.

SPECT (HMPAO) support for activation of the medial prefrontal cortices during toe graphaesthesia.

PubMed

Persinger, M A; Webster, D; Tiller, S G

1998-08-01

This experiment was designed to test the construct validity of psychometric analyses that suggested a strong functional association between the accuracy for toe graphaesthesia and selective activation of neurons within the medial prefrontal regions. Single Photon Emission Computerized Tomography (SPECT) profiles were obtained for three volunteers (2 men, 1 woman) after they had been exposed to a toe graphaesthesia task or had been exposed to the control setting. The two measurements for each participant were separated by at least one week. Qualitative evaluation, using criteria employed for clinical diagnoses, of serial coronal, sagittal, and horizontal sections clearly indicated a specific increase in uptake of tracer within the rostral one-third to one-half of the medial prefrontal cortices of all three subjects during the toe graphaesthesia task compared to that during baseline conditions. The results are consistent with our neuropsychological research which indicates that toe graphaesthesia may be an accurate and useful indicator of the functional integrity of the medial surfaces of the anterior cerebral hemispheres.

An integrated assessment of soil erosion dynamics with special emphasis on gully erosion: Case studies from South Africa and Iran

NASA Astrophysics Data System (ADS)

Maerker, Michael; Sommer, Christian; Zakerinejad, Reza; Cama, Elena

2017-04-01

Soil erosion by water is a significant problem in arid and semi arid areas of large parts of Iran. Water erosion is one of the most effective phenomena that leads to decreasing soil productivity and pollution of water resources. Especially in semiarid areas like in the Mazayjan watershed in the Southwestern Fars province as well as in the Mkomazi catchment in Kwa Zulu Natal, South Africa, gully erosion contributes to the sediment dynamics in a significant way. Consequently, the intention of this research is to identify the different types of soil erosion processes acting in the area with a stochastic approach and to assess the process dynamics in an integrative way. Therefore, we applied GIS, and satellite image analysis techniques to derive input information for the numeric models. For sheet and rill erosion the Unit Stream Power-based Erosion Deposition Model (USPED) was utilized. The spatial distribution of gully erosion was assessed using a statistical approach which used three variables (stream power index, slope, and flow accumulation) to predict the spatial distribution of gullies in the study area. The eroded gully volumes were estimated for a multiple years period by fieldwork and Google Earth high resolution images as well as with structure for motion algorithm. Finally, the gully retreat rates were integrated into the USPED model. The results show that the integration of the SPI approach to quantify gully erosion with the USPED model is a suitable method to qualitatively and quantitatively assess water erosion processes in data scarce areas. The application of GIS and stochastic model approaches to spatialize the USPED model input yield valuable results for the prediction of soil erosion in the test areas. The results of this research help to develop an appropriate management of soil and water resources in the study areas.

Modeling runoff and erosion risk in a~small steep cultivated watershed using different data sources: from on-site measurements to farmers' perceptions

NASA Astrophysics Data System (ADS)

Auvet, B.; Lidon, B.; Kartiwa, B.; Le Bissonnais, Y.; Poussin, J.-C.

2015-09-01

This paper presents an approach to model runoff and erosion risk in a context of data scarcity, whereas the majority of available models require large quantities of physical data that are frequently not accessible. To overcome this problem, our approach uses different sources of data, particularly on agricultural practices (tillage and land cover) and farmers' perceptions of runoff and erosion. The model was developed on a small (5 ha) cultivated watershed characterized by extreme conditions (slopes of up to 55 %, extreme rainfall events) on the Merapi volcano in Indonesia. Runoff was modelled using two versions of STREAM. First, a lumped version was used to determine the global parameters of the watershed. Second, a distributed version used three parameters for the production of runoff (slope, land cover and roughness), a precise DEM, and the position of waterways for runoff distribution. This information was derived from field observations and interviews with farmers. Both surface runoff models accurately reproduced runoff at the outlet. However, the distributed model (Nash-Sutcliffe = 0.94) was more accurate than the adjusted lumped model (N-S = 0.85), especially for the smallest and biggest runoff events, and produced accurate spatial distribution of runoff production and concentration. Different types of erosion processes (landslides, linear inter-ridge erosion, linear erosion in main waterways) were modelled as a combination of a hazard map (the spatial distribution of runoff/infiltration volume provided by the distributed model), and a susceptibility map combining slope, land cover and tillage, derived from in situ observations and interviews with farmers. Each erosion risk map gives a spatial representation of the different erosion processes including risk intensities and frequencies that were validated by the farmers and by in situ observations. Maps of erosion risk confirmed the impact of the concentration of runoff, the high susceptibility of long steep slopes, and revealed the critical role of tillage direction. Calibrating and validating models using in situ measurements, observations and farmers' perceptions made it possible to represent runoff and erosion risk despite the initial scarcity of hydrological data. Even if the models mainly provided orders of magnitude and qualitative information, they significantly improved our understanding of the watershed dynamics. In addition, the information produced by such models is easy for farmers to use to manage runoff and erosion by using appropriate agricultural practices.

Quantifying spatial and temporal trends in beach-dune volumetric changes using spatial statistics

NASA Astrophysics Data System (ADS)

Eamer, Jordan B. R.; Walker, Ian J.

2013-06-01

Spatial statistics are generally underutilized in coastal geomorphology, despite offering great potential for identifying and quantifying spatial-temporal trends in landscape morphodynamics. In particular, local Moran's Ii provides a statistical framework for detecting clusters of significant change in an attribute (e.g., surface erosion or deposition) and quantifying how this changes over space and time. This study analyzes and interprets spatial-temporal patterns in sediment volume changes in a beach-foredune-transgressive dune complex following removal of invasive marram grass (Ammophila spp.). Results are derived by detecting significant changes in post-removal repeat DEMs derived from topographic surveys and airborne LiDAR. The study site was separated into discrete, linked geomorphic units (beach, foredune, transgressive dune complex) to facilitate sub-landscape scale analysis of volumetric change and sediment budget responses. Difference surfaces derived from a pixel-subtraction algorithm between interval DEMs and the LiDAR baseline DEM were filtered using the local Moran's Ii method and two different spatial weights (1.5 and 5 m) to detect statistically significant change. Moran's Ii results were compared with those derived from a more spatially uniform statistical method that uses a simpler student's t distribution threshold for change detection. Morphodynamic patterns and volumetric estimates were similar between the uniform geostatistical method and Moran's Ii at a spatial weight of 5 m while the smaller spatial weight (1.5 m) consistently indicated volumetric changes of less magnitude. The larger 5 m spatial weight was most representative of broader site morphodynamics and spatial patterns while the smaller spatial weight provided volumetric changes consistent with field observations. All methods showed foredune deflation immediately following removal with increased sediment volumes into the spring via deposition at the crest and on lobes in the lee, despite erosion on the stoss slope and dune toe. Generally, the foredune became wider by landward extension and the seaward slope recovered from erosion to a similar height and form to that of pre-restoration despite remaining essentially free of vegetation.

A fluidized bed technique for estimating soil critical shear stress

USDA-ARS?s Scientific Manuscript database

Soil erosion models, depending on how they are formulated, always have erodibilitiy parameters in the erosion equations. For a process-based model like the Water Erosion Prediction Project (WEPP) model, the erodibility parameters include rill and interrill erodibility and critical shear stress. Thes...

A Mechanistic Model of Waterfall Plunge Pool Erosion into Bedrock

NASA Astrophysics Data System (ADS)

Scheingross, Joel S.; Lamb, Michael P.

2017-11-01

Landscapes often respond to changes in climate and tectonics through the formation and upstream propagation of knickzones composed of waterfalls. Little work has been done on the mechanics of waterfall erosion, and instead most landscape-scale models neglect waterfalls or use rules for river erosion, such as stream power, that may not be applicable to waterfalls. Here we develop a physically based model to predict waterfall plunge pool erosion into rock by abrasion from particle impacts and test the model against flume experiments. Both the model and experiments show that evolving plunge pools have initially high vertical erosion rates due to energetic particle impacts, and erosion slows and eventually ceases as pools deepen and deposition protects the pool floor from further erosion. Lateral erosion can continue after deposition on the pool floor, but it occurs at slow rates that become negligible as pools widen. Our work points to the importance of vertical drilling of successive plunge pools to drive upstream knickzone propagation in homogenous rock, rather than the classic mechanism of headwall undercutting. For a series of vertically drilling waterfalls, we find that upstream knickzone propagation is faster under higher combined water and sediment fluxes and for knickzones composed of many waterfalls that are closely spaced. Our model differs significantly from stream-power-based erosion rules in that steeper knickzones can retreat faster or more slowly depending on the number and spacing of waterfalls within a knickzone, which has implications for interpreting climatic and tectonic history through analysis of river longitudinal profiles.

Hydrologic Drivers of Soil Organic Carbon Erosion and Burial: Insights from a Spatially-explicit Model of a Degraded Landscape at the Calhoun Critical Zone Observatory

NASA Astrophysics Data System (ADS)

Dialynas, Y. G.; Bras, R. L.; Richter, D. D., Jr.

2017-12-01

Soil erosion and burial of organic material may constitute a substantial sink of atmospheric CO2. Attempts to quantify impacts of soil erosion on the soil-atmosphere C exchange are limited by difficulties in accounting for the fate of eroded soil organic carbon (SOC), a key factor in estimating of the net effect of erosion on the C cycle. Processes that transport SOC are still inadequately represented in terrestrial carbon (C) cycle models. This study investigates hydrologic controls on SOC redistribution across the landscape focusing on dynamic feedbacks between watershed hydrology, soil erosional processes, and SOC burial. We use tRIBS-ECO (Triangulated Irregular Network-based Real-time Integrated Basin Simulator-Erosion and Carbon Oxidation), a spatially-explicit model of SOC dynamics coupled with a physically-based hydro-geomorphic model. tRIBS-ECO systematically accounts for the fate of eroded SOC across the watershed: Rainsplash erosion and sheet erosion redistribute SOC from upland sites to depositional environments, altering depth-dependent soil biogeochemical properties in diverse soil profiles. Eroded organic material is transferred with sediment and can be partially oxidized upon transport, or preserved from decomposition by burial. The model was applied in the Calhoun Critical Zone Observatory (CZO), a site that is recovering from some of the most serious agricultural erosion in North America. Soil biogeochemical characteristics at multiple soil horizons were used to initialize the model and test performance. Remotely sensed soil moisture data (NASA SMAP) were used for model calibration. Results show significant rates of hydrologically-induced burial of SOC at the Calhoun CZO. We find that organic material at upland eroding soil profiles is largely mobilized by rainsplash erosion. Sheet erosion mainly drives C transport in lower elevation clayey soils. While SOC erosion and deposition rates declined with recent reforestation at the study site, the erosional potential of the degraded landscape remains significant.

Plantar-Plate Disruptions: “The Severe Turf-Toe Injury.” Three Cases in Contact Athletes

PubMed Central

Drakos, Mark C.; Fiore, Russell; Murphy, Conor; DiGiovanni, Christopher W.

2015-01-01

Objective: To present 3 cases of plantar-plate rupture and turf-toe injury in contact athletes at 1 university and to discuss appropriate diagnosis and treatment algorithms for each case. Background: Turf toe is a common injury in athletes participating in outdoor cutting sports. However, it has been used as an umbrella term to describe many different injuries of the great toe. In some cases, the injury can be so severe that the plantar plate and sesamoid apparatus may be ruptured. These patients may be better managed with surgery than with traditional nonoperative interventions. Differential Diagnosis: Turf toe, plantar-plate disruption, sesamoid fracture. Treatment: For stable injuries in which the plantar plate is not completely disrupted, nonoperative treatment with casting or a stiff-soled shoe, gradual weight bearing, and rehabilitation is the best practice. Unstable injuries require surgical intervention and plantar-plate repair. Uniqueness: Turf toe and injury to the first metatarsophalangeal joint are relatively common injuries in athletes, but few researchers have detailed the operative and nonoperative treatments of plantar-plate disruption in these patients. We examine 3 cases that occurred over 4 seasons on a collegiate football team. Conclusions: Turf toe represents a wide array of pathologic conditions involving the first metatarsophalangeal joint. Stress and instability testing are key components to assess in determining whether surgical intervention is warranted to restore optimal function. Stiffer-soled shoes or shoes with steel-plate insertions may help to prevent these injuries and are useful tools for protection during the rehabilitation period. PMID:25695855

Customizing Extensor Reconstruction in Vascularized Toe Joint Transfers to Finger Proximal Interphalangeal Joints: A Strategic Approach for Correcting Extensor Lag.

PubMed

Loh, Charles Yuen Yung; Hsu, Chung-Chen; Lin, Cheng-Hung; Chen, Shih-Heng; Lien, Shwu-Huei; Lin, Chih-Hung; Wei, Fu-Chan; Lin, Yu-Te

2017-04-01

Vascularized toe proximal interphalangeal joint transfer allows the restoration of damaged joints. However, extensor lag and poor arc of motion have been reported. The authors present their outcomes of treatment according to a novel reconstructive algorithm that addresses extensor lag and allows for consistent results postoperatively. Vascularized toe joint transfers were performed in a consecutive series of 26 digits in 25 patients. The average age was 30.5 years, with 14 right and 12 left hands. Reconstructed digits included eight index, 10 middle, and eight ring fingers. Simultaneous extensor reconstructions were performed and eight were centralization of lateral bands, five were direct extensor digitorum longus-to-extensor digitorum communis repairs, and 13 were central slip reconstructions. The average length of follow-up was 16.7 months. The average extension lag was 17.9 degrees. The arc of motion was 57.7 degrees (81.7 percent functional use of pretransfer toe proximal interphalangeal joint arc of motion). There was no significant difference in the reconstructed proximal interphalangeal joint arc of motion for the handedness (p = 0.23), recipient digits (p = 0.37), or surgical experience in vascularized toe joint transfer (p = 0.25). The outcomes of different techniques of extensor mechanism reconstruction were similar in terms of extensor lag, arc of motion, and reconstructed finger arc of motion compared with the pretransfer toe proximal interphalangeal joint arc of motion. With this treatment algorithm, consistent outcomes can be produced with minimal extensor lag and maximum use of potential toe proximal interphalangeal joint arc of motion. Therapeutic, IV.

Effects of shoe sole geometry on toe clearance and walking stability in older adults.

PubMed

Thies, S B; Price, C; Kenney, L P J; Baker, R

2015-07-01

Thirty-five percent of people above age 65 fall each year, and half of their falls are associated with tripping: tripping, an apparently 'mundane' everyday problem, therefore, significantly impacts on older people's health and associated medical costs. To avoid tripping and subsequent falling, sufficient toe clearance during the swing phase is crucial. We previously found that a rocker-shaped shoe sole enhances toe clearance in young adults, thereby decreasing their trip-risk. This study investigates whether such sole design also enhances older adults' toe clearance, without inadvertently affecting their walking stability. Toe clearance and its variability are reported together with measures of walking stability for twelve older adults, walking in shoes with rocker angles of 10°, 15°, and 20°. Surface inclinations (flat, incline, decline) were chosen to reflect a potential real-world environment. Toe clearance increased substantially from the 10° to the 15° rocker angle (p=0.003) without compromising measures of walking stability (p>0.05). A further increase in rocker angle to 20° resulted in less substantial enhancement of toe clearance and came at the cost of a decrease in gait speed on the decline. The novelty of this investigation lies in the exploration of the trade-off between reduction of trip-risk through footwear design and adverse effects on walking stability on real-life relevant surfaces. Our two studies suggest that the current focus on slip-resistance in footwear design may need to be generalised to include other factors that affect trip-risk. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.

The Rangeland Hydrology and Erosion Model

NASA Astrophysics Data System (ADS)

Nearing, M. A.

2016-12-01

The Rangeland Hydrology and Erosion Model (RHEM) is a process-based model that was designed to address rangelands conditions. RHEM is designed for government agencies, land managers and conservationists who need sound, science-based technology to model, assess, and predict runoff and erosion rates on rangelands and to assist in evaluating rangeland conservation practices effects. RHEM is an event-based model that estimates runoff, erosion, and sediment delivery rates and volumes at the spatial scale of the hillslope and the temporal scale of as single rainfall event. It represents erosion processes under normal and fire-impacted rangeland conditions. Moreover, it adopts a new splash erosion and thin sheet-flow transport equation developed from rangeland data, and it links the model hydrologic and erosion parameters with rangeland plant community by providing a new system of parameter estimation equations based on 204 plots at 49 rangeland sites distributed across 15 western U.S. states. A dynamic partial differential sediment continuity equation is used to model the total detachment rate of concentrated flow and rain splash and sheet flow. RHEM is also designed to be used as a calculator, or "engine", within other watershed scale models. From the research perspective RHEM acts as a vehicle for incorporating new scientific findings from rangeland infiltration, runoff, and erosion studies. Current applications of the model include: 1) a web site for general use (conservation planning, research, etc.), 2) National Resource Inventory reports to Congress, 3) as a computational engine within watershed scale models (e.g., KINEROS, HEC), 4) Ecological Site & State and Transition Descriptions, 5) proposed in 2015 to become part of the NRCS Desktop applications for field offices.

Effect of mechanical properties on erosion resistance of ductile materials

NASA Astrophysics Data System (ADS)

Levin, Boris Feliksovih

Solid particle erosion (SPE) resistance of ductile Fe, Ni, and Co-based alloys as well as commercially pure Ni and Cu was studied. A model for SPE behavior of ductile materials is presented. The model incorporates the mechanical properties of the materials at the deformation conditions associated with SPE process, as well as the evolution of these properties during the erosion induced deformation. An erosion parameter was formulated based on consideration of the energy loss during erosion, and incorporates the material's hardness and toughness at high strain rates. The erosion model predicts that materials combining high hardness and toughness can exhibit good erosion resistance. To measure mechanical properties of materials, high strain rate compression tests using Hopkinson bar technique were conducted at strain rates similar to those during erosion. From these tests, failure strength and strain during erosion were estimated and used to calculate toughness of the materials. The proposed erosion parameter shows good correlation with experimentally measured erosion rates for all tested materials. To analyze subsurface deformation during erosion, microhardness and nanoindentation tests were performed on the cross-sections of the eroded materials and the size of the plastically deformed zone and the increase in materials hardness due to erosion were determined. A nanoindentation method was developed to estimate the restitution coefficient within plastically deformed regions of the eroded samples which provides a measure of the rebounding ability of a material during particle impact. An increase in hardness near the eroded surface led to an increase in restitution coefficient. Also, the stress rates imposed below the eroded surface were comparable to those measured during high strain-rate compression tests (10sp3-10sp4 ssp{-1}). A new parameter, "area under the microhardness curve" was developed that represents the ability of a material to absorb impact energy. By incorporating this parameter into a new erosion model, good correlation was observed with experimentally measured erosion rates. An increase in area under the microhardness curve led to an increase in erosion resistance. It was shown that an increase in hardness below the eroded surface occurs mainly due to the strain-rate hardening effect. Strain-rate sensitivities of tested materials were estimated from the nanoindentation tests and showed a decrease with an increase in materials hardness. Also, materials combining high hardness and strain-rate sensitivity may offer good erosion resistance. A methodology is presented to determine the proper mechanical properties to incorporate into the erosion parameter based on the physical model of the erosion mechanism in ductile materials.

Feedforward neural control of toe walking in humans.

PubMed

Lorentzen, Jakob; Willerslev-Olsen, Maria; Hüche Larsen, Helle; Svane, Christian; Forman, Christian; Frisk, Rasmus; Farmer, Simon Francis; Kersting, Uwe; Nielsen, Jens Bo

2018-03-23

Activation of ankle muscles at ground contact during toe walking is unaltered when sensory feedback is blocked or the ground is suddenly dropped. Responses in the soleus muscle to transcranial magnetic stimulation, but not peripheral nerve stimulation, are facilitated at ground contact during toe walking. We argue that toe walking is supported by feedforward control at ground contact. Toe walking requires careful control of the ankle muscles in order to absorb the impact of ground contact and maintain a stable position of the joint. The present study aimed to clarify the peripheral and central neural mechanisms involved. Fifteen healthy adults walked on a treadmill (3.0 km h -1 ). Tibialis anterior (TA) and soleus (Sol) EMG, knee and ankle joint angles, and gastrocnemius-soleus muscle fascicle lengths were recorded. Peripheral and central contributions to the EMG activity were assessed by afferent blockade, H-reflex testing, transcranial magnetic brain stimulation (TMS) and sudden unloading of the planter flexor muscle-tendon complex. Sol EMG activity started prior to ground contact and remained high throughout stance. TA EMG activity, which is normally seen around ground contact during heel strike walking, was absent. Although stretch of the Achilles tendon-muscle complex was observed after ground contact, this was not associated with lengthening of the ankle plantar flexor muscle fascicles. Sol EMG around ground contact was not affected by ischaemic blockade of large-diameter sensory afferents, or the sudden removal of ground support shortly after toe contact. Soleus motor-evoked potentials elicited by TMS were facilitated immediately after ground contact, whereas Sol H-reflexes were not. These findings indicate that at the crucial time of ankle stabilization following ground contact, toe walking is governed by centrally mediated motor drive rather than sensory driven reflex mechanisms. These findings have implications for our understanding of the control of human gait during voluntary toe walking. © 2018 The Authors. The Journal of Physiology © 2018 The Physiological Society.

Modeling of technical soil-erosion control measures and its impact on soil erosion off-site effects within urban areas

NASA Astrophysics Data System (ADS)

Dostal, Tomas; Devaty, Jan

2013-04-01

The paper presents results of surface runoff, soil erosion and sediment transport modeling using Erosion 3D software - physically based mathematical simulation model, event oriented, fully distributed. Various methods to simulate technical soil-erosion conservation measures were tested, using alternative digital elevation models of different precision and resolution. Ditches and baulks were simulated by three different approaches, (i) by change of the land-cover parameters to increase infiltration and decrease flow velocity, (ii) by change of the land-cover parameters to completely infiltrate the surface runoff and (iii) by adjusting the height of the digital elevation model by "burning in" the channels of the ditches. Results show advantages and disadvantages of each approach and conclude suitable methods for combinations of particular digital elevation model and purpose of the simulations. Further on a set of simulations was carried out to model situations before and after technical soil-erosion conservation measures application within a small catchment of 4 km2. These simulations were focused on quantitative and qualitative assessment of technical soil-erosion control measures impact on soil erosion off-site effects within urban areas located downstream of intensively used agricultural fields. The scenarios were built upon a raster digital elevation model with spatial resolution of 3 meters derived from LiDAR 5G vector point elevation data. Use of this high-resolution elevation model allowed simulating the technical soil-erosion control measures by direct terrain elevation adjustment. Also the structures within the settlements were emulated by direct change in the elevation of the terrain model. The buildings were lifted up to simulate complicated flow behavior of the surface runoff within urban areas, using approach of Arévalo (Arévalo, 2011) but focusing on the use of commonly available data without extensive detailed editing. Application of the technical soil-erosion control measures induced strong change in overall amount of eroded/deposited material as well as spatial erosion/deposition patterns within the settlement areas. Validation of modeled scenarios and effects on measured data was not possible as no real runoff event was recorded in the target area so the conclusions were made by comparing the different modeled scenarios. Advantages and disadvantages of used approach to simulate technical soil-erosion conservation measures are evaluated and discussed as well as the impact of use of high-resolution elevation data on the intensity and spatial distribution of soil erosion and deposition. Model approved ability to show detailed distribution of damages over target urban area, which is very sensitive for off-site effects of surface runoff, soil erosion and sediment transport and also high sensitivity to input data, especially to DEM, which affects surface runoff pattern and therefore intensity of harmful effects. Acknowledgement: This paper has been supported by projects: Ministry of the interior of the CR VG 20122015092, and project NAZV QI91C008 TPEO.

Comparison of WEPP and APEX runoff and erosion prediction at field scale in Goodwater Creek Experimental Watershed

USDA-ARS?s Scientific Manuscript database

The Water Erosion Prediction Project (WEPP) and the Agricultural Policy/Environmental eXtender (APEX) are process-based models that can predict spatial and temporal distributions of erosion for hillslopes and watersheds. This study applies the WEPP model to predict runoff and erosion for a 35-ha fie...

Validation of a probabilistic post-fire erosion model

Treesearch

Pete Robichaud; William J. Elliot; Sarah A. Lewis; Mary Ellen Miller

2016-01-01

Post-fire increases of runoff and erosion often occur and land managers need tools to be able to project the increased risk. The Erosion Risk Management Tool (ERMiT) uses the Water Erosion Prediction Project (WEPP) model as the underlying processor. ERMiT predicts the probability of a given amount of hillslope sediment delivery from a single rainfall or...

Soil erosion risk assessment using interviews, empirical soil erosion modeling (RUSLE) and fallout radionuclides in a volcanic crater lake watershed subjected to land use change, western Uganda

NASA Astrophysics Data System (ADS)

De Crop, Wannes; Ryken, Nick; Tomma Okuonzia, Judith; Van Ranst, Eric; Baert, Geert; Boeckx, Pascal; Verschuren, Dirk; Verdoodt, Ann

2017-04-01

Population pressure results in conversion of natural vegetation to cropland within the western Ugandan crater lake watersheds. These watersheds however are particularly prone to soil degradation and erosion because of the high rainfall intensity and steep topography. Increased soil erosion losses expose the aquatic ecosystems to excessive nutrient loading. In this study, the Katinda crater lake watershed, which is already heavily impacted by agricultural land use, was selected for an explorative study on its (top)soil characteristics - given the general lack of data on soils within these watersheds - as well as an assessment of soil erosion risks. Using group discussions and structured interviews, the local land users' perceptions on land use, soil quality, soil erosion and lake ecology were compiled. Datasets on rainfall, topsoil characteristics, slope gradient and length, and land use were collected. Subsequently a RUSLE erosion model was run. Results from this empirical erosion modeling approach were validated against soil erosion estimates based on 137Cs measurements.

Erosion estimation of guide vane end clearance in hydraulic turbines with sediment water flow

NASA Astrophysics Data System (ADS)

Han, Wei; Kang, Jingbo; Wang, Jie; Peng, Guoyi; Li, Lianyuan; Su, Min

2018-04-01

The end surface of guide vane or head cover is one of the most serious parts of sediment erosion for high-head hydraulic turbines. In order to investigate the relationship between erosion depth of wall surface and the characteristic parameter of erosion, an estimative method including a simplified flow model and a modificatory erosion calculative function is proposed in this paper. The flow between the end surfaces of guide vane and head cover is simplified as a clearance flow around a circular cylinder with a backward facing step. Erosion characteristic parameter of csws3 is calculated with the mixture model for multiphase flow and the renormalization group (RNG) k-𝜀 turbulence model under the actual working conditions, based on which, erosion depths of guide vane and head cover end surfaces are estimated with a modification of erosion coefficient K. The estimation results agree well with the actual situation. It is shown that the estimative method is reasonable for erosion prediction of guide vane and can provide a significant reference to determine the optimal maintenance cycle for hydraulic turbine in the future.

Simulations of wind erosion along the Qinghai-Tibet Railway in north-central Tibet

NASA Astrophysics Data System (ADS)

Jiang, Yingsha; Gao, Yanhong; Dong, Zhibao; Liu, Benli; Zhao, Lin

2018-06-01

Wind erosion along the Qinghai-Tibet Railway causes sand hazard and poses threats to the safety of trains and passengers. A coupled land-surface erosion model (Noah-MPWE) was developed to simulate the wind erosion along the railway. Comparison with the data from the 137Cs isotope analysis shows that this coupled model could simulate the mean erosion amount reasonably. The coupled model was then applied to eight sites along the railway to investigate the wind-erosion distribution and variations from 1979 to 2012. Factors affecting wind erosion spatially and temporally were assessed as well. Majority wind erosion occurs in the non-monsoon season from December to April of the next year except for the site located in desert. The region between Wudaoliang and Tanggula has higher wind erosion occurrences and soil lose amount because of higher frequency of strong wind and relatively lower soil moisture than other sites. Inter-annually, all sites present a significant decreasing trend of annual soil loss with an average rate of -0.18 kg m-2 a-1 in 1979-2012. Decreased frequency of strong wind, increased precipitation and soil moisture contribute to the reduction of wind erosion in 1979-2012. Snow cover duration and vegetation coverage also have great impact on the occurrence of wind erosion.

Advances in modeling soil erosion after disturbance on rangelands

USDA-ARS?s Scientific Manuscript database

Research has been undertaken to develop process based models that predict soil erosion rate after disturbance on rangelands. In these models soil detachment is predicted as a combination of multiple erosion processes, rain splash and thin sheet flow (splash and sheet) detachment and concentrated flo...

Validation of Erosion 3D in Lower Saxony - Comparison between modelled soil erosion events and results of a long term monitoring project

NASA Astrophysics Data System (ADS)

Bug, Jan; Mosimann, Thomas

2013-04-01

Since 2000 water erosion has been surveyed on 400 ha arable land in three different regions of Lower Saxony (Mosimann et al. 2009). The results of this long-term survey are used for the validation of the soil erosion models such as USLE and Erosion 3D. The validation of the physically-based model Erosion 3D (Schmidt & Werner 2000) is possible because the survey analyses the effects (soil loss, sediment yield, deposition on site) of single thunder storm events and also maps major factors of soil erosion (soil, crop, tillage). A 12.5 m Raster DEM was used to model the soil erosion events.Rainfalldata was acquired from climate stations. Soil and landuse parameters were derived from the "Parameterkatalog Sachsen"(Michael et al. 1996). During thirteen years of monitoring, high intensity storms fell less frequently than expected. High intensity rainfalls with a return period of five or ten years usually occurred during periods of maximum plant cover.Winter events were ruled out because dataon snow melt and rainfallwere not measured. The validation is therefore restricted to 80 events. The validation consists of three parts. The first part compares the spatial distribution of the mapped soil erosion with the model results. The second part calculates the difference in the amount of redistributed soil. The third part analyses off-site effects such as sediment yield and pollution of water bodies. The validation shows that the overall result of erosion 3D is quite good. Spatial hotspots of soil erosion and of off-site effects are predicted correctly in most cases. However, quantitative comparison is more problematic, because the mapping allows only the quantification of rillerosion and not of sheet erosion. So as a rule,the predicted soil loss is higher than the mapped. The prediction of rill development is also problematic. While the model is capable of predicting rills in thalwegs, the modelling of erosion in tractor tracks and headlands is more complicated. In order to obtain better results, the DEM needs a higher resolution, and soil and landuse parameters have to been optimized in tractor tracks and headlands (higher bulk density, less coverage). Other models like LINERO (Bug &Mosimann 2012) can help to get an overview over the location of erosion forms and the soil loss due to rill erosion. References: Bug J., & T. Mosimann (2012): Modellierung der linearen Bodenerosion. Entwicklung eines entscheidungsbasierten Modells zur flächenhaften Prognose der linearen Erosionsaktivität, Geosynthesis 15, Hannover, 105 S. Michael, A., Schmidt, J. & W. A. Schmidt (1996): EROSION 2D/3D - Ein Computermodell zur Simulation der Bodenerosion durch Wasser. Parameterkatalog Sachsen, Freiberg. Mosimann, T., Bug, J. Sanders, S. & F. Beisiegel (2009): Bodenerosionsdauerbeobachtung in Niedersachsen 2000-2008. Methodik, Erosionsgeschehen, Bodenabträge und Anwendung der Ergebnisse, Geosynthesis 14, Hannover, 101 S. Schmidt, J., & M. v. Werner (2000): Modeling sediment and heavy metal yields of drinking water reservoirs in the Osterzgebirge region of Saxony (Germany). In: Schmidt, J. (Ed.), Soil Erosion—Application of Physically Based Models. Springer, Berlin, Heidelberg, New York, pp. 93- 108.

Dynamic Modelling of Erosion and Deposition Processes in Debris Flows With Application to Real Debris Flow Events in Switzerland

NASA Astrophysics Data System (ADS)

Deubelbeiss, Y.; McArdell, B. W.; Graf, C.

2011-12-01

The dynamics of a debris flow can be significantly influenced by erosion and deposition processes during an event because volume changes have a strong influence on flow properties such as flow velocity, flow heights and runout distances. It is therefore worth exploring how to include these processes in numerical models, which are used for hazard assessment and mitigation measure planning. However, it is still under debate, what mechanism drives the erosion of material at the base of a debris flow. There are different processes attributed to erosion: it has been proposed that erosion correlates with the stresses due to granular interactions at the front, which in turn strongly depend on particle size or it may be related to basal shear forces. Because it is expected that larger flow heights result in larger stresses one can additionally hypothesize that there is a correlation between erosion rate and flow height. To test different erosion laws in a numerical model and its influence on the flow behavior we implement different relationships and compare simulation results with field data. Herefore, we use the numerical model, RAMMS (Christen et al., 2010), employing the Voellmy-fluid friction law. While it has already been shown that a correlation of erosion with velocity does not lead to a satisfying result (too high entrainment in the tail) a correlation with flow height combined with velocity (momentum) has been successfully applied to ice-avalanches. Currently, we are testing the momentum-driven and for comparison we reconsider the simple velocity-driven erosion rate. However, these laws do not consider processes on a smaller scale such as particle fluctuations resulting in energy production, which might play an important role. Therefore, we additionally consider an erosion model that has potential to draw new insights on the erosion process in debris flows. The model is based on an extended Voellmy model, which additionally employs an equation, which is a measure of the random kinetic energy (RKE, equivalent to granular temperature) produced by the random movement of particles in a debris flow (Buser and Bartelt, 2009). Advantageous is that friction is dependent on the production of RKE and is decreasing with decreasing RKE. The amount of energy produced in the system, might therefore be a useful indicator for the erosion rate. While the erosion model using the Voellmy approach might be successfully applicable to cases where erosion and bulking are the main processes, such as in Illgraben (CH), it might be less straight forward in mountain torrents where we additionally observe a lot of deposition along the flow path such as in Dorfbach (CH). The extended Voellmy model is indirectly accounting for this process as friction is a function of RKE, which allows material to deposit earlier. At both locations we have debris flow observation stations including innovative new measurement techniques indication parameters such as flow velocity, height and volumes at specific locations (Illgraben, Dorfbach) as well as erosion rate measurements (Illgraben). These highly valuable data allow us good model calibration as well as verification of the newly implemented erosion models.

The role of internal climate variability for interpreting climate change scenarios

NASA Astrophysics Data System (ADS)

Maraun, Douglas

2013-04-01

When communicating information on climate change, the use of multi-model ensembles has been advocated to sample uncertainties over a range as wide as possible. To meet the demand for easily accessible results, the ensemble is often summarised by its multi-model mean signal. In rare cases, additional uncertainty measures are given to avoid loosing all information on the ensemble spread, e.g., the highest and lowest projected values. Such approaches, however, disregard the fundamentally different nature of the different types of uncertainties and might cause wrong interpretations and subsequently wrong decisions for adaptation. Whereas scenario and climate model uncertainties are of epistemic nature, i.e., caused by an in principle reducible lack of knowledge, uncertainties due to internal climate variability are aleatory, i.e., inherently stochastic and irreducible. As wisely stated in the proverb "climate is what you expect, weather is what you get", a specific region will experience one stochastic realisation of the climate system, but never exactly the expected climate change signal as given by a multi model mean. Depending on the meteorological variable, region and lead time, the signal might be strong or weak compared to the stochastic component. In cases of a low signal-to-noise ratio, even if the climate change signal is a well defined trend, no trends or even opposite trends might be experienced. Here I propose to use the time of emergence (TOE) to quantify and communicate when climate change trends will exceed the internal variability. The TOE provides a useful measure for end users to assess the time horizon for implementing adaptation measures. Furthermore, internal variability is scale dependent - the more local the scale, the stronger the influence of internal climate variability. Thus investigating the TOE as a function of spatial scale could help to assess the required spatial scale for implementing adaptation measures. I exemplify this proposal with a recently published study on the TOE for mean and heavy precipitation trends in Europe. In some regions trends emerge only late in the 21st century or even later, suggesting that in these regions adaptation to internal variability rather than to climate change is required. Yet in other regions the climate change signal is strong, urging for timely adaptation. Douglas Maraun, When at what scale will trends in European mean and heavy precipitation emerge? Env. Res. Lett., in press, 2013.

Estimating erosion in a riverine watershed: Bayou Liberty-Tchefuncta River in Louisiana.

PubMed

Martin, August; Gunter, James T; Regens, James L

2003-01-01

GOAL, SCOPE, BACKGROUND: Sheet erosion from agricultural, forest and urban lands may increase stream sediment loads as well as transport other pollutants that adversely affect water quality, reduce agricultural and forest production, and increase infrastructure maintenance costs. This study uses spatial analysis techniques and a numerical modeling approach to predict areas with the greatest sheet erosion potential given different soils disturbance scenarios. A Geographic Information System (GIS) and the Universal Soil Loss Equation (USLE) were used to estimate sheet erosion from 0.64 ha parcels of land within the watershed. The Soil Survey of St. Tammany Parish, Louisiana was digitized, required soil attributes entered into the GIS database, and slope factors determined for each 80 x 80 meter parcel in the watershed. The GIS/USLE model used series-specific erosion K factors, a rainfall factor of 89, and a GIS database of scenario-driven cropping and erosion control practice factors to estimate potential soil loss due to sheet erosion. A general trend of increased potential sheet erosion occurred for all land use categories (urban, agriculture/grasslands, forests) as soil disturbance increases from cropping, logging and construction activities. Modeling indicated that rapidly growing urban areas have the greatest potential for sheet erosion. Evergreen and mixed forests (production forest) had lower sheet erosion potentials; with deciduous forests (mostly riparian) having the least sheet erosion potential. Erosion estimates from construction activities may be overestimated because of the value chosen for the erosion control practice factor. This study illustrates the ease with which GIS can be integrated with the Universal Soil Loss Equation to identify areas with high sheet erosion potential for large scale management and policy decision making. The GIS/USLE modeling approach used in this study offers a quick and inexpensive tool for estimating sheet erosion within watersheds using publicly available information. This method can quickly identify discrete locations with relatively precise spatial boundaries (approximately 80 meter resolution) that have a high sheet erosion potential as well as areas where management interventions might be appropriate to prevent or ameliorate erosion.

Water erosion susceptibility mapping by applying Stochastic Gradient Treeboost to the Imera Meridionale River Basin (Sicily, Italy)

NASA Astrophysics Data System (ADS)

Angileri, Silvia Eleonora; Conoscenti, Christian; Hochschild, Volker; Märker, Michael; Rotigliano, Edoardo; Agnesi, Valerio

2016-06-01

Soil erosion by water constitutes a serious problem affecting various countries. In the last few years, a number of studies have adopted statistical approaches for erosion susceptibility zonation. In this study, the Stochastic Gradient Treeboost (SGT) was tested as a multivariate statistical tool for exploring, analyzing and predicting the spatial occurrence of rill-interrill erosion and gully erosion. This technique implements the stochastic gradient boosting algorithm with a tree-based method. The study area is a 9.5 km2 river catchment located in central-northern Sicily (Italy), where water erosion processes are prevalent, and affect the agricultural productivity of local communities. In order to model soil erosion by water, the spatial distribution of landforms due to rill-interrill and gully erosion was mapped and 12 environmental variables were selected as predictors. Four calibration and four validation subsets were obtained by randomly extracting sets of negative cases, both for rill-interrill erosion and gully erosion models. The results of validation, based on receiving operating characteristic (ROC) curves, showed excellent to outstanding accuracies of the models, and thus a high prediction skill. Moreover, SGT allowed us to explore the relationships between erosion landforms and predictors. A different suite of predictor variables was found to be important for the two models. Elevation, aspect, landform classification and land-use are the main controlling factors for rill-interrill erosion, whilst the stream power index, plan curvature and the topographic wetness index were the most important independent variables for gullies. Finally, an ROC plot analysis made it possible to define a threshold value to classify cells according to the presence/absence of the two erosion processes. Hence, by heuristically combining the resulting rill-interrill erosion and gully erosion susceptibility maps, an integrated water erosion susceptibility map was created. The adopted method offers the advantages of an objective and repeatable procedure, whose result is useful for local administrators to identify the areas that are most susceptible to water erosion and best allocate resources for soil conservation strategies.

A watershed scale spatially-distributed model for streambank erosion rate driven by channel curvature

NASA Astrophysics Data System (ADS)

McMillan, Mitchell; Hu, Zhiyong

2017-10-01

Streambank erosion is a major source of fluvial sediment, but few large-scale, spatially distributed models exist to quantify streambank erosion rates. We introduce a spatially distributed model for streambank erosion applicable to sinuous, single-thread channels. We argue that such a model can adequately characterize streambank erosion rates, measured at the outsides of bends over a 2-year time period, throughout a large region. The model is based on the widely-used excess-velocity equation and comprised three components: a physics-based hydrodynamic model, a large-scale 1-dimensional model of average monthly discharge, and an empirical bank erodibility parameterization. The hydrodynamic submodel requires inputs of channel centerline, slope, width, depth, friction factor, and a scour factor A; the large-scale watershed submodel utilizes watershed-averaged monthly outputs of the Noah-2.8 land surface model; bank erodibility is based on tree cover and bank height as proxies for root density. The model was calibrated with erosion rates measured in sand-bed streams throughout the northern Gulf of Mexico coastal plain. The calibrated model outperforms a purely empirical model, as well as a model based only on excess velocity, illustrating the utility of combining a physics-based hydrodynamic model with an empirical bank erodibility relationship. The model could be improved by incorporating spatial variability in channel roughness and the hydrodynamic scour factor, which are here assumed constant. A reach-scale application of the model is illustrated on ∼1 km of a medium-sized, mixed forest-pasture stream, where the model identifies streambank erosion hotspots on forested and non-forested bends.

Adhesion and friction in gecko toe attachment and detachment

PubMed Central

Tian, Yu; Pesika, Noshir; Zeng, Hongbo; Rosenberg, Kenny; Zhao, Boxin; McGuiggan, Patricia; Autumn, Kellar; Israelachvili, Jacob

2006-01-01

Geckos can run rapidly on walls and ceilings, requiring high friction forces (on walls) and adhesion forces (on ceilings), with typical step intervals of ≈20 ms. The rapid switching between gecko foot attachment and detachment is analyzed theoretically based on a tape model that incorporates the adhesion and friction forces originating from the van der Waals forces between the submicron-sized spatulae and the substrate, which are controlled by the (macroscopic) actions of the gecko toes. The pulling force of a spatula along its shaft with an angle θ between 0 and 90° to the substrate, has a “normal adhesion force” contribution, produced at the spatula-substrate bifurcation zone, and a “lateral friction force” contribution from the part of spatula still in contact with the substrate. High net friction and adhesion forces on the whole gecko are obtained by rolling down and gripping the toes inward to realize small pulling angles θ between the large number of spatulae in contact with the substrate. To detach, the high adhesion/friction is rapidly reduced to a very low value by rolling the toes upward and backward, which, mediated by the lever function of the setal shaft, peels the spatulae off perpendicularly from the substrates. By these mechanisms, both the adhesion and friction forces of geckos can be changed over three orders of magnitude, allowing for the swift attachment and detachment during gecko motion. The results have obvious implications for the fabrication of dry adhesives and robotic systems inspired by the gecko's locomotion mechanism. PMID:17148600

The influence of muscles on knee flexion during the swing phase of gait.

PubMed

Piazza, S J; Delp, S L

1996-06-01

Although the movement of the leg during swing phase is often compared to the unforced motion of a compound pendulum, the muscles of the leg are active during swing and presumably influence its motion. To examine the roles of muscles in determining swing phase knee flexion, we developed a muscle-actuated forward dynamic simulation of the swing phase of normal gait. Joint angles and angular velocities at toe-off were derived from experimental measurements, as were pelvis motions and muscle excitations. Joint angles and joint moments resulting from the simulation corresponded to experimental measurements made during normal gait. Muscular joint moments and initial joint angular velocities were altered to determine the effects of each upon peak knee flexion in swing phase. As expected, the simulation demonstrated that either increasing knee extension moment or decreasing toe-off knee flexion velocity decreased peak knee flexion. Decreasing hip flexion moment or increasing toe-off hip flexion velocity also caused substantial decreases in peak knee flexion. The rectus femoris muscle played an important role in regulating knee flexion; removal of the rectus femoris actuator from the model resulted in hyperflexion of the knee, whereas an increase in the excitation input to the rectus femoris actuator reduced knee flexion. These findings confirm that reduced knee flexion during the swing phase (stiff-knee gait) may be caused by overactivity of the rectus femoris. The simulations also suggest that weakened hip flexors and stance phase factors that determine the angular velocities of the knee and hip at toe-off may be responsible for decreased knee flexion during swing phase.

An elastic-plastic fracture mechanics analysis of weld-toe surface cracks in fillet welded T-butt joint

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

Fu, B.

1994-12-31

This paper describes an elastic-plastic fracture mechanics (EPFM) study of shallow weld-toe cracks. Two limiting crack configurations, plane strain edge crack and semi-circular surface crack in fillet welded T-butt plate joint, were analyzed using the finite element method. Crack depth ranging from 2 to 40% of plate thickness were considered. The elastic-plastic analysis, assuming power-law hardening relationship and Mises yield criterion, was based on incremental plasticity theory. Tension and bending loads applied were monotonically increased to a level causing relatively large scale yielding at the crack tip. Effects of weld-notch geometry and ductile material modeling on prediction of fracture mechanicsmore » characterizing parameter were assessed. It was found that the weld-notch effect reduces and the effect of material modeling increases as crack depth increases. Material modeling is less important than geometric modeling in analysis of very shallow cracks but is more important for relatively deeper cracks, e.g. crack depth more than 20% of thickness. The effect of material modeling can be assessed using a simplified structural model. Weld magnification factors derived assuming linear elastic conditions can be applied to EPFM characterization.« less

Study On The Application Of CBERS-02B To Quantitative Soil Erosion Monitoring

NASA Astrophysics Data System (ADS)

Shi, Mingchang; Xu, Jing; Wang, Lei; Wang, Xiaoyun; Mu, Jing

2010-10-01

Currently, the reduction of soil erosion is an important prerequisite for achieving ecological security. Since real-time and quantitative evaluation on regional soil erosion plays a significant role in reducing the soil erosion, soil erosion models are more and more widely used. Based on RUSLE model, this paper carries out the quantitative soil erosion monitoring in the Xi River Basin and its surrounding areas by using CBERS-02B CCD, DEM, TRMM and other data. Besides, it performs the validation for monitoring results by using remote sensing investigation results in 2005. The monitoring results show that in 2009, the total amount of soil erosion in the study area was 1.94×106t, the erosion area was 2055.2km2 (54.06% of the total area), and the average soil erosion modulus was 509.7t km-2 a-1. As a case using CBERS-02B data for quantitative soil erosion monitoring, this study provides experience on the application of CBERS-02B data in the field of quantitative soil erosion monitoring and also for local soil erosion management.

Enhancements to the Water Erosion Prediction Project (WEPP) for modeling large snow-dominated mountainous forest watersheds

Treesearch

Anurag Srivastava; Joan Q. Wu; William J. Elliot; Erin S. Brooks

2015-01-01

The Water Erosion Prediction Project (WEPP) model, originally developed for hillslope and small watershed applications, simulates complex interactive processes influencing erosion. Recent incorporations to the model have improved the subsurface hydrology components for forest applications. Incorporation of channel routing has made the WEPP model well suited for large...

Guidelines for transoesophageal echocardiographic probe cleaning and disinfection from the British Society of Echocardiography.

PubMed

Kanagala, P; Bradley, C; Hoffman, P; Steeds, R P

2011-10-01

The clinical utility of transoesophageal echocardiography (TOE) is well established. Being a semi-invasive procedure, however, the potential for transmission of infection between sequential patients exists. This has implications for the protection of both patients and medical staff. Guidelines for disinfection during gastrointestinal endoscopy (GIE) have been in place for many years.(1,2) Unfortunately, similar guidance is lacking with respect to TOE. Although traversing the same body cavities and sharing many similarities with upper GIE, there are fundamental structural and procedural differences with TOE which merit special consideration in establishing a decontamination protocol. This document provides recommendations for TOE probe decontamination based on the available evidence, expert opinion, and modification of the current British Society of Gastroenterology guidelines.

Modeling of phosphorus fluxes produced by wild fires at watershed scales.

NASA Astrophysics Data System (ADS)

Matyjasik, M.; Hernandez, M.; Shaw, N.; Baker, M.; Fowles, M. T.; Cisney, T. A.; Jex, A. P.; Moisen, G.

2017-12-01

River runoff is one of the controlling processes in the terrestrial phosphorus cycle. Phosphorus is often a limiting factor in fresh water. One of the factors that has not been studied and modeled in detail is phosporus flux produced from forest wild fires. Phosphate released by weathering is quickly absorbed in soils. Forest wild fires expose barren soils to intensive erosion, thus releasing relatively large fluxes of phosphorus. Measurements from three control burn sites were used to correlate erosion with phosphorus fluxes. These results were used to model phosphorus fluxes from burned watersheds during a five year long period after fires occurred. Erosion in our model is simulated using a combination of two models: the WEPP (USDA Water Erosion Prediction Project) and the GeoWEPP (GIS-based Water Erosion Prediction Project). Erosion produced from forest disturbances is predicted for any watershed using hydrologic, soil, and meteorological data unique to the individual watersheds or individual slopes. The erosion results are modified for different textural soil classes and slope angles to model fluxes of phosphorus. The results of these models are calibrated using measured concentrations of phosphorus for three watersheds located in the Interior Western United States. The results will help the United States Forest Service manage phosporus fluxes in national forests.

Facing the scaling problem: A multi-methodical approach to simulate soil erosion at hillslope and catchment scale

NASA Astrophysics Data System (ADS)

Schmengler, A. C.; Vlek, P. L. G.

2012-04-01

Modelling soil erosion requires a holistic understanding of the sediment dynamics in a complex environment. As most erosion models are scale-dependent and their parameterization is spatially limited, their application often requires special care, particularly in data-scarce environments. This study presents a hierarchical approach to overcome the limitations of a single model by using various quantitative methods and soil erosion models to cope with the issues of scale. At hillslope scale, the physically-based Water Erosion Prediction Project (WEPP)-model is used to simulate soil loss and deposition processes. Model simulations of soil loss vary between 5 to 50 t ha-1 yr-1 dependent on the spatial location on the hillslope and have only limited correspondence with the results of the 137Cs technique. These differences in absolute soil loss values could be either due to internal shortcomings of each approach or to external scale-related uncertainties. Pedo-geomorphological soil investigations along a catena confirm that estimations by the 137Cs technique are more appropriate in reflecting both the spatial extent and magnitude of soil erosion at hillslope scale. In order to account for sediment dynamics at a larger scale, the spatially-distributed WaTEM/SEDEM model is used to simulate soil erosion at catchment scale and to predict sediment delivery rates into a small water reservoir. Predicted sediment yield rates are compared with results gained from a bathymetric survey and sediment core analysis. Results show that specific sediment rates of 0.6 t ha-1 yr-1 by the model are in close agreement with observed sediment yield calculated from stratigraphical changes and downcore variations in 137Cs concentrations. Sediment erosion rates averaged over the entire catchment of 1 to 2 t ha-1 yr-1 are significantly lower than results obtained at hillslope scale confirming an inverse correlation between the magnitude of erosion rates and the spatial scale of the model. The study has shown that the use of multiple methods facilitates the calibration and validation of models and might provide a more accurate measure for soil erosion rates in ungauged catchments. Moreover, the approach could be used to identify the most appropriate working and operational scales for soil erosion modelling.

Numerical study of impact erosion of multiple solid particle

NASA Astrophysics Data System (ADS)

Zheng, Chao; Liu, Yonghong; Chen, Cheng; Qin, Jie; Ji, Renjie; Cai, Baoping

2017-11-01

Material erosion caused by continuous particle impingement during hydraulic fracturing results in significant economic loss and increased production risks. The erosion process is complex and has not been clearly explained through physical experiments. To address this problem, a multiple particle model in a 3D configuration was proposed to investigate the dynamic erosion process. This approach can significantly reduce experiment costs. The numerical model considered material damping and elastic-plastic material behavior of target material. The effects of impact parameters on erosion characteristics, such as plastic deformation, contact time, and energy loss rate, were investigated. Based on comprehensive studies, the dynamic erosion mechanism and geometry evolution of eroded crater was obtained. These findings can provide a detailed erosion process of target material and insights into the material erosion caused by multiple particle impingement.

Scaling and Predicting the Geotechnical Resistance Provided by Alfalfa in Experimental Studies of Alluvial-Channel Morphology and Planform

NASA Astrophysics Data System (ADS)

Bankhead, N.; Simon, A.

2008-12-01

Several complex interactions occur between riparian vegetation and bank stability processes. Although there are both positive and negative effects of riparian vegetation on streambank stability, a link between increased vegetation density and decreased bank erosion and lateral migration rates of channels has generally been recorded. The ability of vegetation to promote increased bank stability leads to a positive feedback, in which bank stability then allows the growth and establishment of more vegetation. To study interactions between vegetation density and channel planform, past flume studies have used alfalfa sprouts (Medicago sativa), seeded over the entire floodplain in varying densities. Such studies have observed reductions in braiding intensity with increased alfalfa density. It has been assumed in these studies that the alfalfa sprouts increase the resistance of the bank material to lateral erosion. When alfalfa sprouts are scaled up they simulate mature riparian trees well. However, the geotechnical properties of alfalfa roots, and quantification of the increase in resistance provided to the banks under different densities of alfalfa have thus far been ignored. It is therefore unknown if the resistance provided by the alfalfa roots also scales well to real-world root-reinforcement values. To quantify additional bank strength, alfalfa sprouts were grown in sand and the roots tested at regular intervals to measure tensile strength. Results of tensile-strength measurements for alfalfa sprouts displayed the typical non-linear decrease of tensile strength (in MPa) with increasing root diameter. Values for the additional cohesion provided by alfalfa roots were calculated by inputting alfalfa tensile-strength and root density data to the root-reinforcement model, RipRoot, resulting in root-reinforcement values of 0 to 11.8 kPa. These values are similar to those that would be expected under field conditions. The root-cohesion values calculated for alfalfa sprouts were then used in conjunction with the Bank Stability and Toe Erosion Model (BSTEM), and a series of laboratory experiments, to evaluate if the factor of safety (FS) of experimental channels lined with different densities of alfalfa could be predicted. Sand banks ranging in height from 1.25 to 3.75 cm were modeled and tested experimentally for cases with different groundwater heights and flow depths in the channel, and with cohesion due to roots being scaled appropriately using a length reduction factor. Model results showed that for alfalfa stem densities ranging from 0 to 10 stems/cm2, bank FS ranged from 0.60 to 1.87 and from 0.60 to 1.12 for 1.25 cm and 3.75 cm-high banks respectively. Preliminary results of the laboratory experiments have successfully shown that if cohesion due to roots calculated from the RipRoot model is scaled appropriately, the stability of experimental channels lined with alfalfa of different densities can be predicted. By quantifying the geotechnical resistance of banks during such studies, more accurate predictions of the conditions necessary to create meandering versus braided channel planforms, and the feedback between channel planform and vegetation density in both experimental and real-world scenarios may now be possible.

Mapping monthly rainfall erosivity in Europe.

PubMed

Ballabio, Cristiano; Borrelli, Pasquale; Spinoni, Jonathan; Meusburger, Katrin; Michaelides, Silas; Beguería, Santiago; Klik, Andreas; Petan, Sašo; Janeček, Miloslav; Olsen, Preben; Aalto, Juha; Lakatos, Mónika; Rymszewicz, Anna; Dumitrescu, Alexandru; Tadić, Melita Perčec; Diodato, Nazzareno; Kostalova, Julia; Rousseva, Svetla; Banasik, Kazimierz; Alewell, Christine; Panagos, Panos

2017-02-01

Rainfall erosivity as a dynamic factor of soil loss by water erosion is modelled intra-annually for the first time at European scale. The development of Rainfall Erosivity Database at European Scale (REDES) and its 2015 update with the extension to monthly component allowed to develop monthly and seasonal R-factor maps and assess rainfall erosivity both spatially and temporally. During winter months, significant rainfall erosivity is present only in part of the Mediterranean countries. A sudden increase of erosivity occurs in major part of European Union (except Mediterranean basin, western part of Britain and Ireland) in May and the highest values are registered during summer months. Starting from September, R-factor has a decreasing trend. The mean rainfall erosivity in summer is almost 4 times higher (315MJmmha -1 h -1 ) compared to winter (87MJmmha -1 h -1 ). The Cubist model has been selected among various statistical models to perform the spatial interpolation due to its excellent performance, ability to model non-linearity and interpretability. The monthly prediction is an order more difficult than the annual one as it is limited by the number of covariates and, for consistency, the sum of all months has to be close to annual erosivity. The performance of the Cubist models proved to be generally high, resulting in R 2 values between 0.40 and 0.64 in cross-validation. The obtained months show an increasing trend of erosivity occurring from winter to summer starting from western to Eastern Europe. The maps also show a clear delineation of areas with different erosivity seasonal patterns, whose spatial outline was evidenced by cluster analysis. The monthly erosivity maps can be used to develop composite indicators that map both intra-annual variability and concentration of erosive events. Consequently, spatio-temporal mapping of rainfall erosivity permits to identify the months and the areas with highest risk of soil loss where conservation measures should be applied in different seasons of the year. Copyright © 2016 British Geological Survey, NERC. Published by Elsevier B.V. All rights reserved.

Infiltration and soil erosion modelling on Lausatian post mine sites

NASA Astrophysics Data System (ADS)

Kunth, Franziska; Schmidt, Jürgen

2013-04-01

Land management of reclaimed lignite mine sites requires long-term and safe structuring of recultivation areas. Erosion by water leads to explicit soil losses, especially on heavily endangered water repellent and non-vegetated soil surfaces. Beyond that, weathering of pyrite-containing lignite burden dumps causes sulfuric acid-formation, and hence the acidification of groundwater, seepage water and surface waters. Pyrite containing sediment is detached by precipitation and transported into worked-out open cuts by draining runoff. In addition to ground water influence, erosion processes are therefore involved in acidification of surface waters. A model-based approach for the conservation of man-made slopes of post mining sites is the objective of this ongoing study. The study shall be completed by modeling of the effectiveness of different mine site recultivation scenarios. Erosion risks on man-made slopes in recultivation areas should be determined by applying the physical, raster- and event based computer model EROSION 2D/3D (Schmidt, 1991, 1992; v. Werner, 1995). The widely used erosion model is able to predict runoff as well as detachment, transport and deposition of sediments. Lignite burden dumps contain hydrophobic substances that cover soil particles. Consequently, these soils show strong water repellency, which influences the processes of infiltration and soil erosion on non-vegetated, coal containing dump soils. The influence of water repellency had to be implemented into EROSION 2D/3D. Required input data for soil erosion modelling (e.g. physical soil parameters, infiltration rates, calibration factors, etc.) were gained by soil sampling and rainfall experiments on non-vegetated as well as recultivated reclaimed mine sites in the Lusatia lignite mining region (southeast of Berlin, Germany). The measured infiltration rates on the non-vegetated water repellent sites were extremely low. Therefore, a newly developed water repellency-factor was applied to depict infiltration and erosion processes on water repellent dump soils. For infiltration modelling with EROSION 2D calibration factors (e.g. water repellency factor, skin-factor, etc.) were determined in different steps by calibrating computer modelled infiltration, respectively volume rate of flow to the measured data.

A probabilistic approach to modeling erosion for spatially-varied conditions

Treesearch

William J. Elliot; Peter R. Robichaud; C. D. Pannkuk

2001-01-01

In the years following a major forest disturbance, such as fire, the erosion rate is greatly influenced by variability in weather, in soil properties, and in spatial distribution. This paper presents a method to incorporate these variabilities into the erosion rate predicted by the Water Erosion Prediction Project model. It appears that it is not necessary to describe...

Modeling of high-Z materials erosion and its suppression in DIII-D

NASA Astrophysics Data System (ADS)

Ding, Rui; Guo, H. Y.; Chan, V. S.; Snyder, P. B.; Rudakov, D. L.; Stangeby, P. C.; Elder, J. D.; Tskhakaya, D.; Wampler, W. R.; Kirschner, A.; McLean, A. G.

2015-11-01

Erosion of plasma facing components is a key issue for high-power, long pulse operation. The 3D Monte Carlo code ERO has been used to simulate the erosion/redeposition of Mo and W samples exposed to DIII-D divertor plasma using the DiMES. The net erosion rate is significantly reduced due to the high local re-deposition ratio of eroded materials, which is mainly controlled by the electric field and plasma density within the Chodura sheath as indicated by ERO modeling. Similar re-deposition ratios were obtained from the modeling using three sheath models for small inclined magnetic field angle, all being close to the measured value. ERO modeling shows that local CH4 injection can create a carbon coating on the Mo sample to mitigate Mo erosion; the local decrease of electron temperature due to gas injection also suppresses net erosion, consistent with experimental observation. Supported by the US DOE under DE-FC02-04ER54698 and PSI-SciDAC project.

Movement of a large, slow-moving landslide in the North Island, New Zealand, controlled by porewater pressure and river flow

NASA Astrophysics Data System (ADS)

McColl, Samuel; Holdsworth, Charlotte; Massey, Chris

2017-04-01

New Zealand has 7000 mapped large (> 2 ha) landslides, most of which occur in the Neogene cover rocks, and many of which are active. Active landslides in New Zealand damage lifeline infrastructure, entire suburbs, agricultural land, and they deliver large but little-quantified sediment load to rivers. Despite their prevalence in the landscape and these impacts, much remains unknown of their initiation, movement patterns and processes, or their contributions to landscape evolution. This research assesses how toe cutting and rainfall at a daily to seasonal timescale drive movement of a large (50 hectare) slow-moving, translational rockslide that is severely damaging a farm in the Rangitikei catchment, central North Island. Geomorphological mapping has been undertaken to define the landslide boundary, drainage lines and to assess zones of movements. Since July 2015, 3-monthly GPS-occupations of a survey mark network, and hourly time-lapse photography of the toe of the landslide have been used to identify the distribution and patterns of landslide movement. Pixel-tracking software is being used to quantify movement at the toe from the time-lapse photography at an daily timescale. Movement data are being compared with river flow data (i.e. toe cutting potential) and local rainfall and groundwater from a nearby site (i.e. a proxy for porewater-pressure changes at the landslide). Results so far indicate movement of several mm to cm per year in the upper part of the landslide through a block sliding mechanism, increasing to several metres per year towards the toe where block-sliding transitions sharply to more mobile earth flow-slide behaviour. In the upper part of the landslide, vertical displacements are larger closer to earth flow-slide zone, expressed as decimetre to metre-scale scarps and mini-grabens. The failure surface is exposed at the toe, which is being actively cut by a major river, and reveals a highly remoulded landslide body 1-3 metres thick, overlaying intact sandstone. Based on existing structural data and the landslide surface morphology it is assumed that the landslide thickens to about 60 m towards the head. The geomorphology suggests extension and thinning of the landslide body - which corroborates the movement data showing movement rates at the head (mm per year) increasing downslope to some metres per year at the toe - and without a zone of compression at the toe, suggesting near-continuous toe-unloading. Movement is fastest in the winter-spring months when water tables are high due to reduced evapotranspiration and slightly greater rainfall. However, this period also coincides with a period of higher river flow and flood events (i.e. toe cutting), and the landslide appears to be particularly sensitive (i.e. surges forward) following high river flow events that cut the toe. This observation suggests that movement is driven by both local and catchment-scale rainfall events.

Sediment reallocations due to erosive rainfall events in the Three Gorges Reservoir Area, Central China

NASA Astrophysics Data System (ADS)

Stumpf, Felix; Goebes, Philipp; Schmidt, Karsten; Schindewolf, Marcus; Schönbrodt-Stitt, Sarah; Wadoux, Alexandre; Xiang, Wei; Scholten, Thomas

2017-04-01

Soil erosion by water outlines a major threat to the Three Gorges Reservoir Area in China. A detailed assessment of soil conservation measures requires a tool that spatially identifies sediment reallocations due to rainfall-runoff events in catchments. We applied EROSION 3D as a physically based soil erosion and deposition model in a small mountainous catchment. Generally, we aim to provide a methodological frame that facilitates the model parametrization in a data scarce environment and to identify sediment sources and deposits. We used digital soil mapping techniques to generate spatially distributed soil property information for parametrization. For model calibration and validation, we continuously monitored the catchment on rainfall, runoff and sediment yield for a period of 12 months. The model performed well for large events (sediment yield>1 Mg) with an averaged individual model error of 7.5%, while small events showed an average error of 36.2%. We focused on the large events to evaluate reallocation patterns. Erosion occurred in 11.1% of the study area with an average erosion rate of 49.9Mgha 1. Erosion mainly occurred on crop rotation areas with a spatial proportion of 69.2% for 'corn-rapeseed' and 69.1% for 'potato-cabbage'. Deposition occurred on 11.0%. Forested areas (9.7%), infrastructure (41.0%), cropland (corn-rapeseed: 13.6%, potatocabbage: 11.3%) and grassland (18.4%) were affected by deposition. Because the vast majority of annual sediment yields (80.3%) were associated to a few large erosive events, the modelling approach provides a useful tool to spatially assess soil erosion control and conservation measures.

A systematic review of discomfort due to toe or ear clipping in laboratory rodents

PubMed Central

Geessink, Florentine J.; Brouwer, Michelle A. E.; Tillema, Alice; Ritskes-Hoitinga, Merel

2017-01-01

Toe clipping and ear clipping (also ear notching or ear punching) are frequently used methods for individual identification of laboratory rodents. These procedures potentially cause severe discomfort, which can reduce animal welfare and distort experimental results. However, no systematic summary of the evidence on this topic currently exists. We conducted a systematic review of the evidence for discomfort due to toe or ear clipping in rodents. The review methodology was pre-specified in a registered review protocol. The population, intervention, control, outcome (PICO) question was: In rodents, what is the effect of toe clipping or ear clipping, compared with no clipping or sham clipping, on welfare-related outcomes? Through a systematic search in PubMed, Embase, Web of Science and grey literature, we identified seven studies on the effect of ear clipping on animal welfare, and five such studies on toe clipping. Studies were included in the review if they contained original data from an in vivo experiment in rodents, assessing the effect of toe clipping or ear clipping on a welfare-related outcome. Case studies and studies applying unsuitable co-interventions were excluded. Study quality was appraised using an extended version of SYstematic Review Centre for Laboratory animal Experimentation (SYRCLE)’s risk of bias tool for animal studies. Study characteristics and outcome measures were highly heterogeneous, and there was an unclear or high risk of bias in all studies. We therefore present a narrative synthesis of the evidence identified. None of the studies reported a sample size calculation. Out of over 60 different outcomes, we found evidence of discomfort due to ear clipping in the form of increased respiratory volume, vocalization and blood pressure. For toe clipping, increased vocalization and decreased motor activity in pups were found, as well as long-term effects in the form of reduced grip strength and swimming ability in adults. In conclusion, there is too little evidence to reliably assess discomfort due to toe or ear clipping, and the quality of the available evidence is uncertain. Adequately powered, high-quality studies reporting reliable, relevant outcome measures are needed to accurately assess the impact of these identification techniques. Until more reliable evidence is available, any effect of toe clipping or ear clipping on animal welfare and study results cannot be confirmed or excluded. PMID:28429644

Seasonal monitoring of soil erosion at regional scale: An application of the G2 model in Crete focusing on agricultural land uses

NASA Astrophysics Data System (ADS)

Panagos, Panagos; Christos, Karydas; Cristiano, Ballabio; Ioannis, Gitas

2014-04-01

A new soil erosion model, namely G2, was applied in the island of Crete with a focus on agricultural land uses, including potential grazing lands. The G2 model was developed within the Geoland2 project as an agro-environmental service in the framework of the Global Monitoring for Environment and Security (GMES, now Copernicus) initiative. The G2 model takes advantage of the empirical background of the Universal Soil Loss Equation (USLE) and the Gavrilovic model, together with readily available time series of vegetation layers and 10-min rainfall intensity data to produce monthly time-step erosion risk maps at 300 m cell size. The innovations of the G2 model include the implementation of land-use influence parameters based on empirical data and the introduction of a corrective term in the estimation of the topographic influence factor. The mean annual erosion rate in Crete was found to be 8.123 t ha-1. The season from October to January (the rainy season in Crete) was found to be the most critical, accounting for 80% of the annual erosion in the island. Seasonal erosion figures proved to be crucial for the identification of erosion hotspots and of risky land uses. In Crete, high annual erosion figures were detected in natural grasslands and shrublands (14.023 t ha-1), mainly due to the intensification of livestock grazing during the past decades. The G2 model allows for the integrated spatio-temporal monitoring of soil erosion per land-use type based on moderate data input requirements and existing datasets.

Developing a Terrestrial Biogeochemical Cycle Modeling System to Support the Management of Fort Benning and its Surrounding Areas

DTIC Science & Technology

2010-12-01

Soil Survey Geographic database USDA U.S. Department of Agriculture USLE Universal Soil Loss Equation USPED Unit-Stream-Power Erosion and...2003). A suite of models has been developed to simulate soil erosion and deposition, ranging from empirical (e.g., USLE and MUSLE at http... Soil Erosion and Deposition 4.4.1 USPED The algorithm for the simulation of soil erosion in USPED is similar to that of the USLE or RUSLE model

Impaired heel to toe progression during gait is related to reduced ankle range of motion in people with Multiple Sclerosis.

PubMed

Psarakis, Michael; Greene, David; Moresi, Mark; Baker, Michael; Stubbs, Peter; Brodie, Matthew; Lord, Stephen; Hoang, Phu

2017-11-01

Gait impairment in people with Multiple Sclerosis results from neurological impairment, muscle weakness and reduced range of motion. Restrictions in passive ankle range of motion can result in abnormal heel-to-toe progression (weight transfer) and inefficient gait patterns in people with Multiple Sclerosis. The purpose of this study was to determine the associations between gait impairment, heel-to-toe progression and ankle range of motion in people with Multiple Sclerosis. Twelve participants with Multiple Sclerosis and twelve healthy age-matched participants were assessed. Spatiotemporal parameters of gait and individual footprint data were used to investigate group differences. A pressure sensitive walkway was used to divide each footprint into three phases (contact, mid-stance, propulsive) and calculate the heel-to-toe progression during the stance phase of gait. Compared to healthy controls, people with Multiple Sclerosis spent relatively less time in contact phase (7.8% vs 25.1%) and more time in the mid stance phase of gait (57.3% vs 33.7%). Inter-limb differences were observed in people with Multiple Sclerosis between the affected and non-affected sides for contact (7.8% vs 15.3%) and mid stance (57.3% and 47.1%) phases. Differences in heel-to-toe progression remained significant after adjusting for walking speed and were correlated with walking distance and ankle range of motion. Impaired heel-to-toe progression was related to poor ankle range of motion in people with Multiple Sclerosis. Heel-to-toe progression provided a sensitive measure for assessing gait impairments that were not detectable using standard spatiotemporal gait parameters. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of foot rotation positions on knee valgus during single-leg drop landing: Implications for ACL injury risk reduction.

PubMed

Teng, P S P; Kong, P W; Leong, K F

2017-06-01

Non-contact anterior cruciate ligament (ACL) injuries commonly occur when athletes land in high risk positions such as knee valgus. The position of the foot at landing may influence the transmission of forces from the ankle to the knee. Using an experimental approach to manipulate foot rotation positions, this study aimed to provide new insights on how knee valgus during single-leg landing may be influenced by foot positions. Eleven male recreational basketball players performed single-leg drop landings from a 30-cm high platform in three foot rotation positions (toe-in, toe-forward and toe-out) at initial contact. A motion capture system and a force plate were used to measure lower extremity kinematics and kinetics. Knee valgus angles at initial contact (KVA) and maximum knee valgus moments (KVM), which were known risk factors associated with ACL injury, were measured. A one-way repeated measures Analysis of Variance was conducted (α=0.05) to compare among the three foot positions. Foot rotation positions were found to have a significant effect on KVA (p<0.001, η 2 =0.66) but the difference between conditions (about 1°) was small and not clinically meaningful. There was a significant effect of foot position on KVM (p<0.001, η 2 =0.55), with increased moment observed in the toe-out position as compared to toe-forward (p=0.012) or toe-in positions (p=0.002). When landing with one leg, athletes should avoid extreme toe-out foot rotation positions to minimise undesirable knee valgus loading associated with non-contact ACL injury risks. Copyright © 2017 Elsevier B.V. All rights reserved.

Evaluation of the rusle and disturbed wepp erosion models for predicting soil loss in the first year after wildfire in NW Spain.

PubMed

Fernández, Cristina; Vega, José A

2018-05-04

Severe fire greatly increases soil erosion rates and overland-flow in forest land. Soil erosion prediction models are essential for estimating fire impacts and planning post-fire emergency responses. We evaluated the performance of a) the Revised Universal Soil Loss Equation (RUSLE), modified by inclusion of an alternative equation for the soil erodibility factor, and b) the Disturbed WEPP model, by comparing the soil loss predicted by the models and the soil loss measured in the first year after wildfire in 44 experimental field plots in NW Spain. The Disturbed WEPP has not previously been validated with field data for use in NW Spain; validation studies are also very scarce in other areas. We found that both models underestimated the erosion rates. The accuracy of the RUSLE model was low, even after inclusion of a modified soil erodibility factor accounting for high contents of soil organic matter. We conclude that neither model is suitable for predicting soil erosion in the first year after fire in NW Spain and suggest that soil burn severity should be given greater weighting in post-fire soil erosion modelling. Copyright © 2018 Elsevier Inc. All rights reserved.

Point Judith, Rhode Island, Breakwater Risk Assessment

DTIC Science & Technology

2015-08-01

output stations. Beach zones considered included the sandy beach to the west side of the HoR, which had significant dune features and was fronting...time dependency for crest height and wave parameters is assumed, hc = total damaged crest height of structure from toe , Lp is the local wave length...computed using linear wave theory and Tp, h is the toe depth, hc’ = total undamaged crest height of structure from toe , At = area of structure enclosed

Toe pressure determination by audiophotoplethysmography.

PubMed

Fronek, A; Blazek, V; Curran, B

1994-08-01

The purpose of this study was to evaluate the performance of audiophotoplethysmography as a modality to measure toe pressure without the requirement of a recorder. A portable photoplethysmograph with an audio output was used to determine toe pressures, and the results were compared with those obtained by a commercial photoplethysmograph with a recorder. Thirty-one measurements in control subjects and 62 measurements in patients with arterial occlusive disease were performed. The average toe pressure recorded with oscillography with standard photoplethysmography was 103.5 mm Hg +/- 14.7 SD and 95.9 mm Hg +/- 13.4 SD with audio-photoplethysmography. In the patient group the pressure recorded with a commercial photoplethysmograph was 65.3 mm Hg +/- 34.9 SD compared with 61.6 mm Hg +/- 34.8 SD obtained with audio-photoplethysmography. The difference in both groups was insignificant, and the correlation between both methods was very good. A portable hand-held photoplethysmograph equipped with an audio output was used to measure toe pressure in control subjects and in patients with arterial occlusive disease. The results have been compared with the oscillometric method by a standard commercial photoplethysmograph connected to a recorder. The correlation was very good in the control and patient groups, and the difference between both methods was below the level of statistical significance. The fact that no recorder is needed may help in introducing toe pressure measurement into everyday office diagnostic practice.

In-toeing in children with type I osteogenesis imperfecta: an observational descriptive study.

PubMed

Losa Iglesias, Marta Elena; Becerro de Bengoa Vallejo, Ricardo; Salvadores Fuentes, Paloma

2009-01-01

Osteogenesis imperfecta is an autosomal-dominant disorder of the connective tissue. Also known as brittle bone disease, it renders those affected susceptible to fractures after minimal trauma. Therefore, it is important to minimize the risk of falls and subsequent fractures in patients with this disease. In-toeing is a common condition in children that can result from various pathologic entities, including anteversion, internal tibial torsion, and metatarsus adductus. These conditions can result in frequent tripping and other functional problems. A descriptive study was undertaken to determine the prevalence of in-toeing gait attributable to tibial or femoral torsion or metatarsus adductus in children with type I osteogenesis imperfecta. The study involved orthopedic and biomechanical examination of 15 children (9 girls and 6 boys) aged 4 to 9 years with confirmed type I osteogenesis imperfecta. Patients who used assistive ambulatory devices, such as canes, crutches, and wheelchairs, were excluded from the study. Of the 15 children studied, 12 (80%) demonstrated previously undiagnosed in-toeing gait attributable to torsional deformity or metatarsus adductus in all but one child. Many children with confirmed type I osteogenesis imperfecta have in-toeing gait caused by torsional deformity or metatarsus adductus. Detection and control of in-toeing gait in children with osteogenesis imperfecta is important to prevent fractures resulting from trauma directly related to these conditions.

ERO modelling of tungsten erosion and re-deposition in EAST L mode discharges

NASA Astrophysics Data System (ADS)

Xie, H.; Ding, R.; Kirschner, A.; Chen, J. L.; Ding, F.; Mao, H. M.; Feng, W.; Borodin, D.; Wang, L.

2017-09-01

Tungsten erosion and re-deposition at the upper outer divertor of the Experimental Advanced Superconducting Tokamak has been modelled using the 3D Monte Carlo code ERO. The measured divertor plasma condition in attached L mode discharges with upper single null configuration has been used to build the background plasma in the simulations. The tungsten gross erosion rate is mainly determined by carbon impurity in the background plasma. Increasing carbon concentration can first increase and afterwards suppress the tungsten erosion rate. Taking into account the material mixing surface model, the influence of eroded particles returning to the surface on sputtering has been studied. Sputtering by eroded particles returning to the surface can significantly enhance the gross erosion by reduction of the carbon ratio within the surface interaction layer and by increasing the erosion rate due to sputtering by both eroded tungsten and carbon particles. Modelling indicates that carbon deposition occurs on the dome plate and part of the vertical plate close to the dome plate, whereas tungsten net erosion occurs on most of the vertical plate. The modelling results are in reasonable agreement with the experimental WI spectroscopy.

Modeling erosion under future climates with the WEPP model

Treesearch

Timothy Bayley; William Elliot; Mark A. Nearing; D. Phillp Guertin; Thomas Johnson; David Goodrich; Dennis Flanagan

2010-01-01

The Water Erosion Prediction Project Climate Assessment Tool (WEPPCAT) was developed to be an easy-to-use, web-based erosion model that allows users to adjust climate inputs for user-specified climate scenarios. WEPPCAT allows the user to modify monthly mean climate parameters, including maximum and minimum temperatures, number of wet days, precipitation, and...

Does WEPP meet the specificity of soil erosion in steep mountain regions?

USDA-ARS?s Scientific Manuscript database

We chose the USDA-ARS-WEPP model (Water Erosion Prediction Project) to describe the soil erosion in the Urseren valley (Central Switzerland) as it seems to be one of the most promising models for steep mountain environments. Crucial model parameters were determined in the field (slope, plant species...

Towards new-generation soil erosion modeling: Building a unified omnivorous model

USDA-ARS?s Scientific Manuscript database

Soil erosion is a global threat to agricultural production, and results in off-site sediment and nutrient losses that negatively impact water and air quality. Models are mathematical equations used to estimate the amount of soil lost from a land air, due to the erosive forces of water or wind. Early...

Hammertoe

MedlinePlus

... Hammertoe What Is Hammertoe? Hammertoe is a contracture (bending) deformity of one or both joints of the ... third, fourth or fifth (little) toes. This abnormal bending can put pressure on the toe when wearing ...

Beach morphodynamics and types of foredune erosion generated by storms along the Emilia-Romagna coastline, Italy

NASA Astrophysics Data System (ADS)

Armaroli, Clara; Grottoli, Edoardo; Harley, Mitchell D.; Ciavola, Paolo

2013-10-01

The objectives of this study are to examine the response of a dune and beach system on the Adriatic coastline in northern Italy to the arrival of storms, compare it with seasonal (months) and medium-term (3-year) morphodynamic change, and evaluate results predicted by the numerical model XBeach. The studied coastline stretches 4 km from the Bevano River mouth to the north of the site to the township of Lido di Classe to the south, where the beach is protected by coastal structures. Fieldwork consisted of topographic profile surveys using RTK-DGPS technology (7 times over an approx. 3-year period). 103 samples of surface sediment were collected along 20 of the cross-shore profiles at 6 distinct cross-shore positions, selected on the basis of morphological beach characteristics. Data analyses of dune and beach slopes enabled the study area to be divided into 6 separate morphological zones using the spatial (longshore and cross-shore) variation of morphologies located on the backshore and intertidal beach observed in a preliminary survey of the area. Other criteria were a spatial consistency in beach slopes and/or presence/absence of intertidal morphologies identified in the aerial photographs and Lidar data. The swash zone slope did not show any significant variability for the entire area. A weak seasonal trend in the variability of the mean foredune slope was observed, with steeper slopes typically during winter and flatter slopes during summer. Analysis of grain size revealed that the beach sediment is well-sorted fine sand tending to medium, with a decreasing trend in size from the Bevano River mouth southwards towards Lido di Classe. According to the Masselink and Short (1993) classification, the natural part of the study site has an Intermediate Barred Beach (IBB) and following the Short (1999) classification, results in a modally LBT (longshore bar-trough) or LTT (low tide terrace) with a small section being TBR (transverse bar and rip). Storms are considered the main factor controlling changes in the beach and dune slope. The most significant storm was recorded in March 2010 with a peak significant wave height of 3.91 m. Contrary to the seasonal dune trend, several foredune slopes were observed to flatten following this event, which can be attributed to the action of dune slumping from the already weakened dune state. Modelling of foredune erosion, using a process-based model (XBeach), reproduced the erosion of the upper beach and dune toe reasonably well, but is currently limited by the acceptable slope value for dune stability, which does not account for biotic factors (e.g. plant roots). The comparison between the storm impact categories of Sallenger (2000) and the DSF (Dune Stability Factor) of Armaroli et al. (2012) shows a very good correspondence between the effects of the winter 2008-2009 storms and the vulnerability of the dune system predicted using both classifications.

Scaling up from field to region for wind erosion prediction using a field-scale wind erosion model and GIS

USGS Publications Warehouse

Zobeck, T.M.; Parker, N.C.; Haskell, S.; Guoding, K.

2000-01-01

Factors that affect wind erosion such as surface vegetative and other cover, soil properties and surface roughness usually change spatially and temporally at the field-scale to produce important field-scale variations in wind erosion. Accurate estimation of wind erosion when scaling up from fields to regions, while maintaining meaningful field-scale process details, remains a challenge. The objectives of this study were to evaluate the feasibility of using a field-scale wind erosion model with a geographic information system (GIS) to scale up to regional levels and to quantify the differences in wind erosion estimates produced by different scales of soil mapping used as a data layer in the model. A GIS was used in combination with the revised wind erosion equation (RWEQ), a field-scale wind erosion model, to estimate wind erosion for two 50 km2 areas. Landsat Thematic Mapper satellite imagery from 1993 with 30 m resolution was used as a base map. The GIS database layers included land use, soils, and other features such as roads. The major land use was agricultural fields. Data on 1993 crop management for selected fields of each crop type were collected from local government agency offices and used to 'train' the computer to classify land areas by crop and type of irrigation (agroecosystem) using commercially available software. The land area of the agricultural land uses was overestimated by 6.5% in one region (Lubbock County, TX, USA) and underestimated by about 21% in an adjacent region (Terry County, TX, USA). The total estimated wind erosion potential for Terry County was about four times that estimated for adjacent Lubbock County. The difference in potential erosion among the counties was attributed to regional differences in surface soil texture. In a comparison of different soil map scales in Terry County, the generalised soil map had over 20% more of the land area and over 15% greater erosion potential in loamy sand soils than did the detailed soil map. As a result, the wind erosion potential determined using the generalised soil map Was about 26% greater than the erosion potential estimated by using the detailed soil map in Terry County. This study demonstrates the feasibility of scaling up from fields to regions to estimate wind erosion potential by coupling a field-scale wind erosion model with GIS and identifies possible sources of error with this approach.

Non-vascularized free toe phalanx transfers in congenital hand deformities--the Great Ormond Street experience.

PubMed

Cavallo, A V; Smith, P J; Morley, S; Morsi, A W

2003-12-01

Many options of varying complexity are available for the management of congenital short digits resulting from aphalangia in symbrachydactyly and constriction ring syndrome. We have used non-vascularized free toe phalanx transfers for these children when a vascularized toe transfer has been contraindicated. We describe our technique and experience with 22 children who underwent a total of 64 transfers of the proximal (35) or middle (29) toe phalanges (average 3 per child). The mean age at initial surgery was 15 months, and the mean follow-up was 5 years. Duration of time until epiphyseal closure could not be determined accurately, but total digital elongation averaged 6mm. Complications of this technique include joint instability, premature epiphyseal closure and, in one patient, infection and graft loss. Donor site deformity was determined according to measured growth deficit and toe function. This technique is a simple option for digital elongation and, if performed in the appropriate age group in short fingered and monodactylous subtypes of symbrachydactyly, has the potential to allow growth and function with minimal donor site deficit.

Lower-extremity rotational profile and toe-walking in preschool children with autism spectrum disorder.

PubMed

Arik, Atilla; Aksoy, Cemalettin; Aysev, Ayla; Akçakin, Melda

2018-04-24

The aim of this study was to establish the torsional and toe-walking profiles of children with autism spectrum disorder (ASD), and to analyze the correlations between torsion, toe-walking, autism severity score, and age. In total, 79 consecutive children with autism were examined to determine their hip rotations, thigh-foot angle, degree of toe-walking, and autism severity. Femoral and tibial torsion values, of the preschool patients, were compared statistically with age-matched controls. The hip rotation profile of the patients was similar to the normal group. Nearly a half of the patients with ASD present excessive external tibial torsion. The difference in the tibial torsion between patients and normal children was statistically significant. A weak correlation was found only between tibial torsion and the autism severity score, but no correlation was found between the other parameters. External tibial torsion is the cardinal and persistent orthopedic manifestation among patients with ASD. Toe-walking is the second most common such manifestation and is an independent orthopedic feature in these patients. External tibial torsion may potentially contribute toward the described gait abnormalities in patients with ASD.

Alarm toe switch. [Patent application

DOEpatents

Ganyard, F.P.

1980-11-18

An alarm toe switch inserted within a shoe for energizing an alarm circuit in a covert manner includes an insole mounting pad into which a miniature reed switch is fixedly molded. An elongated slot perpendicular to the reed switch is formed in the bottom surface of the mounting pad. A permanent cylindrical magnet positioned in the forward portion of the slot with a diameter greater than the pad thickness causes a bump above the pad. A foam rubber block is also positioned in the slot rearwardly of the magnet and holds the magnet in normal inoperative relation. A non-magnetic support plate covers the slot and holds the magnet and foam rubber in the slot. The plate minimizes bending and frictional forces to improve movement of the magnet for reliable switch activation. The bump occupies the knuckle space beneath the big toe. When the big toe is scrunched rearwardly the magnet is moved within the slot relative to the reed switch, thus magnetically activating the switch. When toe pressure is released the foam rubber block forces the magnet back into normal inoperative position to deactivate the reed switch.

Determination of riverbank erosion probability using Locally Weighted Logistic Regression

NASA Astrophysics Data System (ADS)

Ioannidou, Elena; Flori, Aikaterini; Varouchakis, Emmanouil A.; Giannakis, Georgios; Vozinaki, Anthi Eirini K.; Karatzas, George P.; Nikolaidis, Nikolaos

2015-04-01

Riverbank erosion is a natural geomorphologic process that affects the fluvial environment. The most important issue concerning riverbank erosion is the identification of the vulnerable locations. An alternative to the usual hydrodynamic models to predict vulnerable locations is to quantify the probability of erosion occurrence. This can be achieved by identifying the underlying relations between riverbank erosion and the geomorphological or hydrological variables that prevent or stimulate erosion. Thus, riverbank erosion can be determined by a regression model using independent variables that are considered to affect the erosion process. The impact of such variables may vary spatially, therefore, a non-stationary regression model is preferred instead of a stationary equivalent. Locally Weighted Regression (LWR) is proposed as a suitable choice. This method can be extended to predict the binary presence or absence of erosion based on a series of independent local variables by using the logistic regression model. It is referred to as Locally Weighted Logistic Regression (LWLR). Logistic regression is a type of regression analysis used for predicting the outcome of a categorical dependent variable (e.g. binary response) based on one or more predictor variables. The method can be combined with LWR to assign weights to local independent variables of the dependent one. LWR allows model parameters to vary over space in order to reflect spatial heterogeneity. The probabilities of the possible outcomes are modelled as a function of the independent variables using a logistic function. Logistic regression measures the relationship between a categorical dependent variable and, usually, one or several continuous independent variables by converting the dependent variable to probability scores. Then, a logistic regression is formed, which predicts success or failure of a given binary variable (e.g. erosion presence or absence) for any value of the independent variables. The erosion occurrence probability can be calculated in conjunction with the model deviance regarding the independent variables tested. The most straightforward measure for goodness of fit is the G statistic. It is a simple and effective way to study and evaluate the Logistic Regression model efficiency and the reliability of each independent variable. The developed statistical model is applied to the Koiliaris River Basin on the island of Crete, Greece. Two datasets of river bank slope, river cross-section width and indications of erosion were available for the analysis (12 and 8 locations). Two different types of spatial dependence functions, exponential and tricubic, were examined to determine the local spatial dependence of the independent variables at the measurement locations. The results show a significant improvement when the tricubic function is applied as the erosion probability is accurately predicted at all eight validation locations. Results for the model deviance show that cross-section width is more important than bank slope in the estimation of erosion probability along the Koiliaris riverbanks. The proposed statistical model is a useful tool that quantifies the erosion probability along the riverbanks and can be used to assist managing erosion and flooding events. Acknowledgements This work is part of an on-going THALES project (CYBERSENSORS - High Frequency Monitoring System for Integrated Water Resources Management of Rivers). The project has been co-financed by the European Union (European Social Fund - ESF) and Greek national funds through the Operational Program "Education and Lifelong Learning" of the National Strategic Reference Framework (NSRF) - Research Funding Program: THALES. Investing in knowledge society through the European Social Fund.

SSEM: A model for simulating runoff and erosion of saline-sodic soil slopes under coastal reclamation

NASA Astrophysics Data System (ADS)

Liu, Dongdong; She, Dongli

2018-06-01

Current physically based erosion models do not carefully consider the dynamic variations of soil properties during rainfall and are unable to simulate saline-sodic soil slope erosion processes. The aim of this work was to build upon a complete model framework, SSEM, to simulate runoff and erosion processes for saline-sodic soils by coupling dynamic saturated hydraulic conductivity Ks and soil erodibility Kτ. Sixty rainfall simulation rainfall experiments (2 soil textures × 5 sodicity levels × 2 slope gradients × 3 duplicates) provided data for model calibration and validation. SSEM worked very well for simulating the runoff and erosion processes of saline-sodic silty clay. The runoff and erosion processes of saline-sodic silt loam were more complex than those of non-saline soils or soils with higher clay contents; thus, SSEM did not perform very well for some validation events. We further examined the model performances of four concepts: Dynamic Ks and Kτ (Case 1, SSEM), Dynamic Ks and Constant Kτ (Case 2), Constant Ks and Dynamic Kτ (Case 3) and Constant Ks and Constant Kτ (Case 4). The results demonstrated that the model, which considers dynamic variations in soil saturated hydraulic conductivity and soil erodibility, can provide more reasonable runoff and erosion prediction results for saline-sodic soils.

Modelling soil erosion at European scale: towards harmonization and reproducibility

NASA Astrophysics Data System (ADS)

Bosco, C.; de Rigo, D.; Dewitte, O.; Poesen, J.; Panagos, P.

2015-02-01

Soil erosion by water is one of the most widespread forms of soil degradation. The loss of soil as a result of erosion can lead to decline in organic matter and nutrient contents, breakdown of soil structure and reduction of the water-holding capacity. Measuring soil loss across the whole landscape is impractical and thus research is needed to improve methods of estimating soil erosion with computational modelling, upon which integrated assessment and mitigation strategies may be based. Despite the efforts, the prediction value of existing models is still limited, especially at regional and continental scale, because a systematic knowledge of local climatological and soil parameters is often unavailable. A new approach for modelling soil erosion at regional scale is here proposed. It is based on the joint use of low-data-demanding models and innovative techniques for better estimating model inputs. The proposed modelling architecture has at its basis the semantic array programming paradigm and a strong effort towards computational reproducibility. An extended version of the Revised Universal Soil Loss Equation (RUSLE) has been implemented merging different empirical rainfall-erosivity equations within a climatic ensemble model and adding a new factor for a better consideration of soil stoniness within the model. Pan-European soil erosion rates by water have been estimated through the use of publicly available data sets and locally reliable empirical relationships. The accuracy of the results is corroborated by a visual plausibility check (63% of a random sample of grid cells are accurate, 83% at least moderately accurate, bootstrap p ≤ 0.05). A comparison with country-level statistics of pre-existing European soil erosion maps is also provided.

Relationship Between Muscle Strength Asymmetry and Body Sway in Older Adults.

PubMed

Koda, Hitoshi; Kai, Yoshihiro; Murata, Shin; Osugi, Hironori; Anami, Kunihiko; Fukumoto, Takahiko; Imagita, Hidetaka

2018-05-31

The purpose of this study was to investigate the relationship between muscle strength asymmetry and body sway while walking. We studied 63 older adult women. Strong side and weak side of knee extension strength, toe grip strength, hand grip strength, and body sway while walking were measured. The relationship between muscle strength asymmetry for each muscle and body sway while walking was evaluated using Pearson's correlation coefficient. Regarding the muscles recognized to have significant correlation with body sway, the asymmetry cutoff value causing an increased sway was calculated. Toe grip strength asymmetry was significantly correlated with body sway. Toe grip strength asymmetry causing an increased body sway had a cutoff value of 23.5%. Our findings suggest toe grip strength asymmetry may be a target for improving gait stability.

Longitudinal bracketed epiphysis of proximal phalanx of the great toe with congenital hallux varus managed simultaneously with monorail external fixator: a case report.

PubMed

Verma, Vineet; Batra, Amit; Singla, Rohit; Gogna, Paritosh; Magu, Narender; Gupta, Rakesh

2014-02-01

Longitudinal bracketed epiphysis (delta phalanx) is a rare congenital anomaly that affects phalanges in the hand more commonly than toes. We present a rare case of congenital hallux varus with longitudinal bracketed epiphysis of proximal phalanx with bifid distal phalanx of the great toe, which was managed with monorail type of external fixator. To the best of our knowledge, this is the first report of its successful implementation in simultaneous treatment of longitudinal bracketed epiphysis of the proximal phalanx of the great toe and hallux varus. Apart from adding to the literature a case of rare subtype of delta phalanx with hallux varus, the present study highlights the role of a reliable alternative in its management.

Numerical simulation of failure behavior of granular debris flows based on flume model tests.

PubMed

Zhou, Jian; Li, Ye-xun; Jia, Min-cai; Li, Cui-na

2013-01-01

In this study, the failure behaviors of debris flows were studied by flume model tests with artificial rainfall and numerical simulations (PFC(3D)). Model tests revealed that grain sizes distribution had profound effects on failure mode, and the failure in slope of medium sand started with cracks at crest and took the form of retrogressive toe sliding failure. With the increase of fine particles in soil, the failure mode of the slopes changed to fluidized flow. The discrete element method PFC(3D) can overcome the hypothesis of the traditional continuous medium mechanic and consider the simple characteristics of particle. Thus, a numerical simulations model considering liquid-solid coupled method has been developed to simulate the debris flow. Comparing the experimental results, the numerical simulation result indicated that the failure mode of the failure of medium sand slope was retrogressive toe sliding, and the failure of fine sand slope was fluidized sliding. The simulation result is consistent with the model test and theoretical analysis, and grain sizes distribution caused different failure behavior of granular debris flows. This research should be a guide to explore the theory of debris flow and to improve the prevention and reduction of debris flow.

Erosivity, surface runoff, and soil erosion estimation using GIS-coupled runoff-erosion model in the Mamuaba catchment, Brazil.

PubMed

Marques da Silva, Richarde; Guimarães Santos, Celso Augusto; Carneiro de Lima Silva, Valeriano; Pereira e Silva, Leonardo

2013-11-01

This study evaluates erosivity, surface runoff generation, and soil erosion rates for Mamuaba catchment, sub-catchment of Gramame River basin (Brazil) by using the ArcView Soil and Water Assessment Tool (AvSWAT) model. Calibration and validation of the model was performed on monthly basis, and it could simulate surface runoff and soil erosion to a good level of accuracy. Daily rainfall data between 1969 and 1989 from six rain gauges were used, and the monthly rainfall erosivity of each station was computed for all the studied years. In order to evaluate the calibration and validation of the model, monthly runoff data between January 1978 and April 1982 from one runoff gauge were used as well. The estimated soil loss rates were also realistic when compared to what can be observed in the field and to results from previous studies around of catchment. The long-term average soil loss was estimated at 9.4 t ha(-1) year(-1); most of the area of the catchment (60%) was predicted to suffer from a low- to moderate-erosion risk (<6 t ha(-1) year(-1)) and, in 20% of the catchment, the soil erosion was estimated to exceed > 12 t ha(-1) year(-1). Expectedly, estimated soil loss was significantly correlated with measured rainfall and simulated surface runoff. Based on the estimated soil loss rates, the catchment was divided into four priority categories (low, moderate, high and very high) for conservation intervention. The study demonstrates that the AvSWAT model provides a useful tool for soil erosion assessment from catchments and facilitates the planning for a sustainable land management in northeastern Brazil.

A simple enrichment correction factor for improving erosion estimation by rare earth oxide tracers

USDA-ARS?s Scientific Manuscript database

Spatially distributed soil erosion data are needed to better understanding soil erosion processes and validating distributed erosion models. Rare earth element (REE) oxides were used to generate spatial erosion data. However, a general concern on the accuracy of the technique arose due to selective ...

Current and future assessments of soil erosion by water on the Tibetan Plateau based on RUSLE and CMIP5 climate models.

PubMed

Teng, Hongfen; Liang, Zongzheng; Chen, Songchao; Liu, Yong; Viscarra Rossel, Raphael A; Chappell, Adrian; Yu, Wu; Shi, Zhou

2018-04-18

Soil erosion by water is accelerated by a warming climate and negatively impacts water security and ecological conservation. The Tibetan Plateau (TP) has experienced warming at a rate approximately twice that observed globally, and heavy precipitation events lead to an increased risk of erosion. In this study, we assessed current erosion on the TP and predicted potential soil erosion by water in 2050. The study was conducted in three steps. During the first step, we used the Revised Universal Soil Equation (RUSLE), publicly available data, and the most recent earth observations to derive estimates of annual erosion from 2002 to 2016 on the TP at 1-km resolution. During the second step, we used a multiple linear regression (MLR) model and a set of climatic covariates to predict rainfall erosivity on the TP in 2050. The MLR was used to establish the relationship between current rainfall erosivity data and a set of current climatic and other covariates. The coefficients of the MLR were generalised with climate covariates for 2050 derived from the fifth phase of the Coupled Model Intercomparison Project (CMIP5) models to estimate rainfall erosivity in 2050. During the third step, soil erosion by water in 2050 was predicted using rainfall erosivity in 2050 and other erosion factors. The results show that the mean annual soil erosion rate on the TP under current conditions is 2.76tha -1 y -1 , which is equivalent to an annual soil loss of 559.59×10 6 t. Our 2050 projections suggested that erosion on the TP will increase to 3.17tha -1 y -1 and 3.91tha -1 y -1 under conditions represented by RCP2.6 and RCP8.5, respectively. The current assessment and future prediction of soil erosion by water on the TP should be valuable for environment protection and soil conservation in this unique region and elsewhere. Copyright © 2018 Elsevier B.V. All rights reserved.

Ankle fracture - aftercare

MedlinePlus

... coldness in your foot, or your toes look dark. You cannot move your toes. You have increased ... to the principles of the Health on the Net Foundation (www.hon.ch). The information provided herein ...

Modeling of Hall Thruster Lifetime and Erosion Mechanisms (Preprint)

DTIC Science & Technology

2007-09-01

Hall thruster plasma discharge has been upgraded to simulate the erosion of the thruster acceleration channel, the degradation of which is the main life-limiting factor of the propulsion system. Evolution of the thruster geometry as a result of material removal due to sputtering is modeled by calculating wall erosion rates, stepping the grid boundary by a chosen time step and altering the computational mesh between simulation runs. The code is first tuned to predict the nose cone erosion of a 200 W Busek Hall thruster , the BHT-200. Simulated erosion

Effects of DEM source and resolution on WEPP hydrologic and erosion simulation: A case study of two forest watersheds in northern Idaho

Treesearch

J. X. Zhang; J. Q. Wu; K. Chang; W. J. Elliot; S. Dun

2009-01-01

The recent modification of the Water Erosion Prediction Project (WEPP) model has improved its applicability to hydrology and erosion modeling in forest watersheds. To generate reliable topographic and hydrologic inputs for the WEPP model, carefully selecting digital elevation models (DEMs) with appropriate resolution and accuracy is essential because topography is a...

Developing relations between soil erodibilty factors in two different soil erosion prediction models (USLE/RUSLE and wWEPP) and fludization bed technique for mechanical soil cohesion

USDA-ARS?s Scientific Manuscript database

Soil erosion models are valuable analysis tools that scientists and engineers use to examine observed data sets and predict the effects of possible future soil loss. In the area of water erosion, a variety of modeling technologies are available, ranging from solely qualitative models, to merely quan...

Scales and erosion

USDA-ARS?s Scientific Manuscript database

There is a need to develop scale explicit understanding of erosion to overcome existing conceptual and methodological flaws in our modelling methods currently applied to understand the process of erosion, transport and deposition at the catchment scale. These models need to be based on a sound under...

Regional Sediment Management (RSM) Principles in Flood Recovery: Incorporating RSM after the 2011 Missouri River Flood

DTIC Science & Technology

2013-06-01

outer bank threatened a Fed- eral levee that protects adjacent homes and farmland. The eroded chute bank approached the toe of the levee causing...design drawing for repairing the levee toe . Approximately 30,000 tons of riprap were placed to re-establish the bank in front of the scour hole...Sediment was needed to fill and stabilize the scour hole between the riprap bank and the toe of the levee. The volume required to fill the scour hole

First Year Sedimentological Characteristics and Morphological Evolution of an Artificial Berm at Fort Myers Beach, Florida

DTIC Science & Technology

2011-06-17

collected in the berm area. In the control areas, surface sediment samples were taken at approximately the toe of the dune (where present...In the berm area, surface sediment samples were taken at approximately the toe of the dune (where 29   present), backbeach, high tide line, mean...samples were taken at approximately the toe of the dune (where present), backbeach, high tide line, mean sea level, low tide line, 2 ft water depth

Heterogeneity and topsoil depletion due to tillage erosion and soil co-extraction with root vegetables: a serious threat to sustainable agricultural land use in the UK

NASA Astrophysics Data System (ADS)

Quine, Timothy; van Oost, Kristof

2010-05-01

The term soil erosion has become almost synonymous with water erosion and yet tillage erosion and soil loss with root crop harvest, although less visible, may be responsible for the majority of the on-site costs of soil erosion in many arable areas of the UK. The study reported here is a first attempt to model soil erosion associated with these processes in England and Wales, at the National scale. A GIS-based modelling approach in the Arc/Info environment is employed in order to meet the requirement for large-scale evaluation of erosion severity. Existing models that have been subject to independent test are used or adapted and widely available data is employed in model parameterisation. Tillage erosion is simulated using a diffusion-type model and a slope curvature index derived from coarse-scale topographic data. The curvature index is calibrated by statistical comparison to curvature values derived from a high resolution digital terrain model. Soil loss with root crop harvest is simulated using information concerning patterns of sugar beet and potato cultivation and estimation of soil moisture during the crop harvest season. Soil loss associated with root crop harvest may be as high as 1 t ha-1 year-1 if land is permanently used for root crops in a 3 year rotation. However, when the arable area of the UK is considered as a whole root crop harvest is responsible for a mean rate of soil loss of approximately 0.1 t ha-1 year-1. Tillage erosion is found to be the dominant process of soil redistribution and onsite erosion on arable land, in comparison with both soil loss through root crop harvest and with long-term water erosion rates. Mean gross rates of tillage erosion were found to be 3.7 t ha-1 year-1, representing approximately 7.4 t ha-1 year-1 erosion and the same rate of deposition. Soil redistribution at these rates is generating an heterogeneous soilscape in which continued functioning for food and fibre production may be jeopardized. These problems may be exacerbated by increased water stress in eroded soils if climate change does, as predicted, result in hotter and drier summers.

Soil erosion modelled with USLE and PESERA using QuickBird derived vegetation parameters in an alpine catchment

NASA Astrophysics Data System (ADS)

Meusburger, K.; Konz, N.; Schaub, M.; Alewell, C.

2010-06-01

The focus of soil erosion research in the Alps has been in two categories: (i) on-site measurements, which are rather small scale point measurements on selected plots often constrained to irrigation experiments or (ii) off-site quantification of sediment delivery at the outlet of the catchment. Results of both categories pointed towards the importance of an intact vegetation cover to prevent soil loss. With the recent availability of high-resolution satellites such as IKONOS and QuickBird options for detecting and monitoring vegetation parameters in heterogeneous terrain have increased. The aim of this study is to evaluate the usefulness of QuickBird derived vegetation parameters in soil erosion models for alpine sites by comparison to Cesium-137 (Cs-137) derived soil erosion estimates. The study site (67 km 2) is located in the Central Swiss Alps (Urseren Valley) and is characterised by scarce forest cover and strong anthropogenic influences due to grassland farming for centuries. A fractional vegetation cover (FVC) map for grassland and detailed land-cover maps are available from linear spectral unmixing and supervised classification of QuickBird imagery. The maps were introduced to the Pan-European Soil Erosion Risk Assessment (PESERA) model as well as to the Universal Soil Loss Equation (USLE). Regarding the latter model, the FVC was indirectly incorporated by adapting the C factor. Both models show an increase in absolute soil erosion values when FVC is considered. In contrast to USLE and the Cs-137 soil erosion rates, PESERA estimates are low. For the USLE model also the spatial patterns improved and showed "hotspots" of high erosion of up to 16 t ha -1 a -1. In conclusion field measurements of Cs-137 confirmed the improvement of soil erosion estimates using the satellite-derived vegetation data.

A plastic flow model for the Acquara - Vadoncello landslide in Senerchia, Southern Italy

USGS Publications Warehouse

Savage, W.; Wasowski, J.

2006-01-01

A previously developed model for stress and velocity fields in two-dimensional Coulomb plastic materials under self-weight and pore pressure predicts that long, shallow landslides develop slip surfaces that manifest themselves as normal faults and normal fault scarps at the surface in areas of extending flow and as thrust faults and thrust fault scarps at the surface in areas of compressive flow. We have applied this model to describe the geometry of slip surfaces and ground stresses developed during the 1995 reactivation of the Acquara - Vadoncello landslide in Senerchia, southern Italy. This landslide is a long and shallow slide in which regions of compressive and extending flow are clearly identified. Slip surfaces in the main scarp region of the landslide have been reconstructed using surface surveys and subsurface borehole logging and inclinometer observations made during retrogression of the main scarp. Two of the four inferred main scarp slip surfaces are best constrained by field data. Slip surfaces in the toe region are reconstructed in the same way and three of the five inferred slip surfaces are similarly constrained. The location of the basal shear surface of the landslide is inferred from borehole logging and borehole inclinometry. Extensive data on material properties, landslide geometries, and pore pressures collected for the Acquara - Vadoncello landslide give values for cohesion, friction angle, and unit weight, plus average basal shear-surface slopes, and pore-pressures required for modelling slip surfaces and stress fields. Results obtained from the landslide-flow model and the field data show that predicted slip surface shapes are consistent with inferred slip surface shapes in both the extending flow main scarp region and in the compressive flow toe region of the Acquara - Vadoncello landslide. Also predicted stress distributions are found to explain deformation features seen in the toe and main scarp regions of the landslide. ?? 2005 Elsevier B.V. All rights reserved.

Erosive Burning of Composite Solid Propellants: Experimental and Modeling Studies

DTIC Science & Technology

1978-08-01

of Crossflow on Solid Pro- appears that an additional mechanism(s) of erosive pallant Combustion: Interior Ballistic Design burning will have to be...Orlondo, Florida, July , 1977, AIAA Paper 77-930. 14. Lengelle,G., "Model Describing the Erosive Com- bustion and Velocity Response of Composite Pro...Propulsion Conference, Orlando, Florida, July , 1977. 17. Beddini, R.A., A Reacting Turbulent Boundary Layer Approach to Solid Propellant Erosive Burning, AFOSR

Hydro-abrasive erosion on coated Pelton runners: Partial calibration of the IEC model based on measurements in HPP Fieschertal

NASA Astrophysics Data System (ADS)

Felix, D.; Abgottspon, A.; Albayrak, I.; Boes, R. M.

2016-11-01

At medium- and high-head hydropower plants (HPPs) on sediment-laden rivers, hydro-abrasive erosion on hydraulic turbines is a major economic issue. For optimization of such HPPs, there is an interest in equations to predict erosion depths. Such a semi-empirical equation suitable for engineering practice is proposed in the relevant guideline of the International Electrotechnical Commission (IEC 62364). However, for Pelton turbines no numerical values of the model's calibration parameters have been available yet. In the scope of a research project at the high-head HPP Fieschertal, Switzerland, the particle load and the erosion on the buckets of two hard-coated 32 MW-Pelton runners have been measured since 2012. Based on three years of field data, the numerical values of a group of calibration parameters of the IEC erosion model were determined for five application cases: (i) reduction of splitter height, (ii) increase of splitter width and (iii) increase of cut-out depth due to erosion of mainly base material, as well as erosion of coating on (iv) the splitter crests and (v) inside the buckets. Further laboratory and field investigations are recommended to quantify the effects of individual parameters as well as to improve, generalize and validate erosion models for uncoated and coated Pelton turbines.

Interventions for treating osteoarthritis of the big toe joint.

PubMed

Zammit, Gerard V; Menz, Hylton B; Munteanu, Shannon E; Landorf, Karl B; Gilheany, Mark F

2010-09-08

Osteoarthritis affecting of the big toe joint of the foot (hallux limitus or rigidus) is a common and painful condition. Although several treatments have been proposed, few have been adequately evaluated. To identify controlled trials evaluating interventions for osteoarthritis of the big toe joint and to determine the optimum intervention(s). Literature searches were conducted across the following electronic databases: CENTRAL; MEDLINE; EMBASE; CINAHL; and PEDro (to 14th January 2010). No language restrictions were applied. Randomised controlled trials, quasi-randomised trials, or controlled clinical trials that assessed treatment outcomes for osteoarthritis of the big toe joint. Participants of any age or gender with osteoarthritis of the big toe joint (defined either radiographically or clinically) were included. Two authors examined the list of titles and abstracts identified by the literature searches. One content area expert and one methodologist independently applied the pre-determined inclusion and exclusion criteria to the full text of identified trials. To minimise error and reduce potential bias, data were extracted independently by two content experts. Only one trial satisfactorily fulfilled the inclusion criteria and was included in this review. This trial evaluated the effectiveness of two physical therapy programs in 20 individuals with osteoarthritis of the big toe joint. Assessment outcomes included pain levels, big toe joint range of motion and plantar flexion strength of the hallux. Mean differences at four weeks follow up were 3.80 points (95% CI 2.74 to 4.86) for self reported pain, 28.30 degrees (95% CI 21.37 to 35.23) for big toe joint range of motion, and 2.80 kg (95% CI 2.13 to 3.47) for muscle strength. Although differences in outcomes between treatment and control groups were reported, the risk of bias was high. The trial failed to employ appropriate randomisation or adequate allocation concealment, used a relatively small sample and incorporated a short follow up (four weeks). No adverse reactions were reported. The reviewed trial presented a high risk of bias, which limited conclusions that could be drawn from the presented data. The inclusion of only one trial indicates the need for more robust randomised controlled trials to determine the efficacy of interventions for this condition.

Effects of different foot progression angles and platform settings on postural stability and fall risk in healthy and medial knee osteoarthritic adults.

PubMed

Khan, Saad Jawaid; Khan, Soobia Saad; Usman, Juliana; Mokhtar, Abdul Halim; Abu Osman, Noor Azuan

2018-02-01

This study aims to investigate the effects of varying toe angles at different platform settings on Overall Stability Index of postural stability and fall risk using Biodex Balance System in healthy participants and medial knee osteoarthritis patients. Biodex Balance System was employed to measure postural stability and fall risk at different foot progression angles (ranging from -20° to 40°, with 10° increments) on 20 healthy (control group) and 20 knee osteoarthritis patients (osteoarthritis group) randomly (age: 59.50 ± 7.33 years and 61.50 ± 8.63 years; body mass: 69.95 ± 9.86 kg and 70.45 ± 8.80 kg). Platform settings used were (1) static, (2) postural stability dynamic level 8 (PS8), (3) fall risk levels 12 to 8 (FR12) and (4) fall risk levels 8 to 2 (FR8). Data from the tests were analysed using three-way mixed repeated measures analysis of variance. The participant group, platform settings and toe angles all had a significant main effect on balance ( p ≤ 0.02). Platform settings had a significant interaction effect with participant group F(3, 144) = 6.97, p < 0.01 and toe angles F(21, 798) = 2.83, p < 0.01. Non-significant interactions were found for group × toe angles, F(7, 266) = 0.89, p = 0.50, and for group × toe angles × settings, F(21, 798) = 1.07, p = 0.36. The medial knee osteoarthritis group has a poorer postural stability and increased fall risk as compared to the healthy group. Changing platform settings has a more pronounced effect on balance in knee osteoarthritis group than in healthy participants. Changing toe angles produced similar effects in both the participant groups, with decreased stability and increased fall risk at extreme toe-in and toe-out angles.

The influence of basal-ice debris on patterns and rates of glacial erosion

NASA Astrophysics Data System (ADS)

Ugelvig, Sofie V.; Egholm, David L.

2018-05-01

Glaciers have played a key role for shaping much of Earth's high topography during the cold periods of the Late Cenozoic. However, despite of their distinct influence on landscapes, the mechanisms of glacial erosion, and the properties that determine their rate of operation, are still poorly understood. Theoretical models of subglacial erosion generally highlight the influence of basal sliding in setting the pace of erosion, but they also point to a strong influence of other subglacial properties, such as effective bed pressure and basal-ice debris concentration. The latter properties are, however, not easily measured in existing glaciers, and hence their influence cannot readily be confirmed by observations. In order to better connect theoretical models for erosion to measurable properties in glaciers, we used computational landscape evolution experiments to study the expected influence of basal-ice debris concentration for subglacial abrasion at the scale of glaciers. The computational experiments couple the two erosion processes of quarrying and abrasion, and furthermore integrate the flow of ice and transport of debris within the ice, thus allowing for the study of dynamic feedbacks between subglacial erosion and systematic glacier-scale variations in basal-ice debris concentration. The experiments explored several physics-based models for glacial erosion, in combination with different models for basal sliding to elucidate the relationship between sliding speed, erosion rate and basal-ice debris concentration. The results demonstrate how differences in debris concentration can explain large variations in measured rates. The experiments also provide a simple explanation for the observed dependence of glacier-averaged rate of erosion on glacier size: that large glacier uplands feed more debris into their lower-elevation parts, thereby strengthening their erosive power.

Soil erosion studies in western Europe from the early 1980s

NASA Astrophysics Data System (ADS)

Boardman, John; Favis-Mortlock, David

2013-04-01

Before the early 1980s, scientific interest in soil erosion in western Europe was minimal. On British soils, for example, high rates of erosion were considered unlikely: "[Soil erosion in Britain] cannot in any way be regarded as a national menace, as can erosion in some other countries" (Jacks, 1954). There was some truth in this perception. By comparison with (for example) the USA, European rainfall was seen as relatively modest in terms of amount and intensity; and European land usage was still generally based on traditional practices which rather rarely left land vulnerable to erosion. However, studies from the late 1970s and early 1980s revealed a growing erosion problem. The earliest UK studies were opportunistic descriptions of large and unusual erosion events which lacked statistical rigour. They led, however, to a growing scientific appreciation of the potential for soil erosion even in those areas which were not previously thought to be erosion-prone e.g. Evans and Northcliff (1978), Boardman (1983). These studies were followed by more ambitious attempts to assess erosion over larger spatial and longer temporal scales: Evans, 1982-86 in England and Wales; Boardman , 1982-91 on the South Downs. Along with this move from considering only single events was a growing appreciation that the most damaging impact of European erosion, in contrast with erosion in the US mid-west and in the tropics, was not on-site but off-site. During these more ambitious monitoring exercises data was also collected on off-site damage by muddy runoff. This led to the realisation that such off-site impacts could be the product of frequent, low magnitude events. This insight has led directly to current concerns regarding agricultural impacts on freshwater systems as exemplified in the Water Framework Directive. These changes in emphasis necessitated a change in experimental and observational approach from small plot to the field scale. The early 1980s also saw the development of erosion models that adapted the USLE to local conditions (e.g. SLEMSA) or incorporated new process-based information into models e.g. EPIC, CREAMS, WEPP and in the UK/Europe, the Morgan, Morgan and Finney model and EUROSEM. Later evaluations focused on the limitations of erosion models e.g. the GCTE exercise (Boardman and Favis-Mortlock, 1998). Since the early 1990s, model development seems to have stalled despite the continued need for progress particularly in the area of erosion-climate change relationships.

Challenges in soil erosion research and prediction model development

USDA-ARS?s Scientific Manuscript database

Quantification of soil erosion has been traditionally considered as a surface hydrologic process with equations for soil detachment and sediment transport derived from the mechanics and hydraulics of the rainfall and surface flow. Under the current erosion modeling framework, the soil has a constant...

Assessment of soil erosion risk in Komering watershed, South Sumatera, using SWAT model

NASA Astrophysics Data System (ADS)

Salsabilla, A.; Kusratmoko, E.

2017-07-01

Changes in land use watershed led to environmental degradation. Estimated loss of soil erosion is often difficult due to some factors such as topography, land use, climate and human activities. This study aims to predict soil erosion hazard and sediment yield using the Soil and Water Assessment Tools (SWAT) hydrological model. The SWAT was chosen because it can simulate the model with limited data. The study area is Komering watershed (806,001 Ha) in South Sumatera Province. There are two factors land management intervention: 1) land with agriculture, and 2) land with cultivation. These factors selected in accordance with the regulations of spatial plan area. Application of the SWAT demonstrated that the model can predict surface runoff, soil erosion loss and sediment yield. The erosion risk for each watershed can be classified and predicted its changes based on the scenarios which arranged. In this paper, we also discussed the relationship between the distribution of erosion risk and watershed's characteristics in a spatial perspective.

Toe and Metatarsal Fractures (Broken Toes)

MedlinePlus

... badly displaced. Follow-up care. Your foot and ankle surgeon will provide instructions for care following surgical or nonsurgical treatment. Physical therapy, exercises and rehabilitation may be included in a schedule for return ...

Capsulitis of the Second Toe

MedlinePlus

... second toe is a result of abnormal foot mechanics, where the ball of the foot beneath the ... options for early treatment of capsulitis: Rest and ice. Staying off the foot and applying ice packs ...

Modeling mechanical and thermo-mechanical erosion by flowing lava at Raglan, Cape Smith Belt, New Québec, Canada

NASA Astrophysics Data System (ADS)

Cataldo, V.; Williams, D. A.; Lesher, C. M.

2015-12-01

The 1.5-D Williams et al. model of thermal erosion by turbulent lava was recently applied to the Athabasca Valles lava channel on Mars, in an attempt to establish the importance of thermal erosion in excavating this ~80-100 m deep outflow channel. The modeled erosion depths (0.4-7.5 m) are far less than the depth of the channel which, combined with the short duration of the eruption, suggests that mechanical erosion may have had a greater role. Several studies suggest that mechanical erosion by lava is more important in channel-tube formation than previously thought, under certain circumstances. How would we be able to distinguish between mechanical and thermal erosion? By investigating model results when substrate properties change, as we move from a consolidated, mechanically strong substrate to a partially consolidated or unconsolidated, mechanically weaker substrate. The Proterozoic Raglan komatiitic basalt lava channel of the Cape Smith Belt, New Québec, Canada is a complex erosional environment involving invasive erosion of both sediment and gabbro substrates - which makes it a critical test case. The lava eroded an upper layer of soft sediment, with erosion at the tops, bottoms, and sides of the conduit, through underlying gabbro, and then burrowed laterally into underlying sediment, a scenario requiring a two-dimensional modeling approach. Using the available field data, we will simulate two-dimensional thermomechanical and mechanical erosion interfaces on all sides of a turbulent lava flow by creating a finite-element mesh. The mesh will be defined by the geometry of the lava flow at those lava conduits for which data on lava and substrate composition, lava thickness, slope of the ground, conduit area and volume, and lava flow length are available. Ultimately, this model will be applied to lunar sinuous rilles and martian lava channels for which the use of a two-dimensional approach is needed.

Nonmonotonic and spatial-temporal dynamic slope effects on soil erosion during rainfall-runoff processes

NASA Astrophysics Data System (ADS)

Wu, Songbai; Yu, Minghui; Chen, Li

2017-02-01

The slope effect on flow erosivity and soil erosion still remains a controversial issue. This theoretical framework explained and quantified the direct slope effect by coupling the modified Green-Ampt equation accounting for slope effect on infiltration, 1-D kinematic wave overland flow routing model, and WEPP soil erosion model. The flow velocity, runoff rate, shear stress, interrill, and rill erosion were calculated on 0°-60° isotropic slopes with equal horizontal projective length. The results show that, for short-duration rainfall events, the flow erosivity and erosion amounts exhibit a bell-shaped trend which first increase with slope gradient, and then decrease after a critical slope angle. The critical slope angles increase significantly or even vanish with increasing rainfall duration but are nearly independent of the slope projective length. The soil critical shear stress, rainfall intensity, and temporal patterns have great influences on the slope effect trend, while the other soil erosion parameters, soil type, hydraulic conductivity, and antecedent soil moisture have minor impacts. Neglecting the slope effect on infiltration would generate smaller erosion and reduce critical slope angles. The relative slope effect on soil erosion in physically based model WEPP was compared to those in the empirical models USLE and RUSLE. The trends of relative slope effect were found quite different, but the difference may diminish with increasing rainfall duration. Finally, relatively smaller critical slope angles could be obtained with the equal slope length and the range of variation provides a possible explanation for the different critical slope angles reported in previous studies.

Lava channel formation during the 2001 eruption on Mount Etna: evidence for mechanical erosion.

PubMed

Ferlito, Carmelo; Siewert, Jens

2006-01-20

We report the direct observation of a peculiar lava channel that was formed near the base of a parasitic cone during the 2001 eruption on Mount Etna. Erosive processes by flowing lava are commonly attributed to thermal erosion. However, field evidence strongly suggests that models of thermal erosion cannot explain the formation of this channel. Here, we put forward the idea that the essential erosion mechanism was abrasive wear. By applying a simple model from tribology we demonstrate that the available data agree favorably with our hypothesis. Consequently, we propose that erosional processes resembling the wear phenomena in glacial erosion are possible in a volcanic environment.

Thermal erosion of a permafrost coastline: Improving process-based models using time-lapse photography

USGS Publications Warehouse

Wobus, C.; Anderson, R.; Overeem, I.; Matell, N.; Clow, G.; Urban, F.

2011-01-01

Coastal erosion rates locally exceeding 30 m y-1 have been documented along Alaska's Beaufort Sea coastline, and a number of studies suggest that these erosion rates have accelerated as a result of climate change. However, a lack of direct observational evidence has limited our progress in quantifying the specific processes that connect climate change to coastal erosion rates in the Arctic. In particular, while longer ice-free periods are likely to lead to both warmer surface waters and longer fetch, the relative roles of thermal and mechanical (wave) erosion in driving coastal retreat have not been comprehensively quantified. We focus on a permafrost coastline in the northern National Petroleum Reserve-Alaska (NPR-A), where coastal erosion rates have averaged 10-15 m y-1 over two years of direct monitoring. We take advantage of these extraordinary rates of coastal erosion to observe and quantify coastal erosion directly via time-lapse photography in combination with meteorological observations. Our observations indicate that the erosion of these bluffs is largely thermally driven, but that surface winds play a crucial role in exposing the frozen bluffs to the radiatively warmed seawater that drives melting of interstitial ice. To first order, erosion in this setting can be modeled using formulations developed to describe iceberg deterioration in the open ocean. These simple models provide a conceptual framework for evaluating how climate-induced changes in thermal and wave energy might influence future erosion rates in this setting.

Mapping regional soil water erosion risk in the Brittany-Loire basin for water management agency

NASA Astrophysics Data System (ADS)

Degan, Francesca; Cerdan, Olivier; Salvador-Blanes, Sébastien; Gautier, Jean-Noël

2014-05-01

Soil water erosion is one of the main degradation processes that affect soils through the removal of soil particles from the surface. The impacts for environment and agricultural areas are diverse, such as water pollution, crop yield depression, organic matter loss and reduction in water storage capacity. There is therefore a strong need to produce maps at the regional scale to help environmental policy makers and soil and water management bodies to mitigate the effect of water and soil pollution. Our approach aims to model and map soil erosion risk at regional scale (155 000 km²) and high spatial resolution (50 m) in the Brittany - Loire basin. The factors responsible for soil erosion are different according to the spatial and time scales considered. The regional scale entails challenges about homogeneous data sets availability, spatial resolution of results, various erosion processes and agricultural practices. We chose to improve the MESALES model (Le Bissonnais et al., 2002) to map soil erosion risk, because it was developed specifically for water erosion in agricultural fields in temperate areas. The MESALES model consists in a decision tree which gives for each combination of factors the corresponding class of soil erosion risk. Four factors that determine soil erosion risk are considered: soils, land cover, climate and topography. The first main improvement of the model consists in using newly available datasets that are more accurate than the initial ones. The datasets used cover all the study area homogeneously. Soil dataset has a 1/1 000 000 scale and attributes such as texture, soil type, rock fragment and parent material are used. The climate dataset has a spatial resolution of 8 km and a temporal resolution of mm/day for 12 years. Elevation dataset has a spatial resolution of 50 m. Three different land cover datasets are used where the finest spatial resolution is 50 m over three years. Using these datasets, four erosion factors are characterized and quantified: the soil factors (soil sealing, erodibility and runoff), the rate of land cover over three years for each season and for 77 land use classes, the topographic factor (slope and drainage area) and the climate hazard (seasonal amount and rainfall erosivity). These modifications of the original MESALES model allow to better represent erosion risk for arable and bare land. We validated model results by stakeholder consultations and meetings over all the study area. The model has finally been modified taking into account validation results. Results are provided with a spatial resolution of 1 km, and then integrated into 2121 catchments. An erosion risk map for each season and an annual erosion risk map are produced. These new maps allow to organize in hierarchy 2121 catchments into three erosion risk classes. In the annual erosion risk map, 347 catchments have the highest erosion risk, which corresponds to 16 % of total Brittany-Loire basin area. Water management agency now uses these maps to identify priority areas and to plan specific preservation practices.

Hammer toe repair

MedlinePlus

... causing: Pain Irritation Sores Problems finding shoes that fit Skin infections Surgery may not be advised if: Treatment with paddings and strapping works You can still straighten your toe Changing to different shoe types can alleviate symptoms

Tinea pedis and onychomycosis frequency in diabetes mellitus patients and diabetic foot ulcers. A cross sectional - observational study.

PubMed

Akkus, Gamze; Evran, Mehtap; Gungor, Dilek; Karakas, Mehmet; Sert, Murat; Tetiker, Tamer

2016-01-01

Impaired cellular immunity and reduced phagocytic function of polymorphonuclear leukocytes facilitate the development of skin fungal and bacterial infections due to uncontrolled hyperglycemia in diabetic patients. In our study, we aimed to assess onychomycosis and/or tinea pedis frequency in diabetic patients, and effects on the development of chronic complications, particularly foot ulcer. We included 227 diabetic patients in the study. Forty-three patients had diabetic foot ulcer. We screened and recorded demographic characteristics, HbA1c levels of patients, and presence of complications We examined patients dermatologically, and collected samples by scalpel from skin between toes, and from sole, toe nail, and area surrounding nails from suspected to have fungal infection. Native positivity between toes was higher in men compared to women (p<0.05). We obtained significant relation between HbA1c elevation and native positivity between toes (p<0.05). Fungal infection between toes, at sole and toe nail significantly increased in patients with diabetic foot ulcer compared to patients without diabetic foot ulcer (p<0.05). Moreover, native positivity in patients with diabetic foot ulcer correlated with presence of fungal infection examination findings (p<0.05). Fungal infections were more frequently observed in the presence of poor glycemic control and peripheral vascular disease in diabetic patients in compliance with the literature, and the presence of fungal infection may also responsible for the development of foot ulcers.

Tinea pedis and onychomycosis frequency in diabetes mellitus patients and diabetic foot ulcers. A cross sectional – observational study

PubMed Central

Akkus, Gamze; Evran, Mehtap; Gungor, Dilek; Karakas, Mehmet; Sert, Murat; Tetiker, Tamer

2016-01-01

Objective: Impaired cellular immunity and reduced phagocytic function of polymorphonuclear leukocytes facilitate the development of skin fungal and bacterial infections due to uncontrolled hyperglycemia in diabetic patients. In our study, we aimed to assess onychomycosis and/or tinea pedis frequency in diabetic patients, and effects on the development of chronic complications, particularly foot ulcer. Methods: We included 227 diabetic patients in the study. Forty-three patients had diabetic foot ulcer. We screened and recorded demographic characteristics, HbA1c levels of patients, and presence of complications We examined patients dermatologically, and collected samples by scalpel from skin between toes, and from sole, toe nail, and area surrounding nails from suspected to have fungal infection. Results: Native positivity between toes was higher in men compared to women (p<0.05). We obtained significant relation between HbA1c elevation and native positivity between toes (p<0.05). Fungal infection between toes, at sole and toe nail significantly increased in patients with diabetic foot ulcer compared to patients without diabetic foot ulcer (p<0.05). Moreover, native positivity in patients with diabetic foot ulcer correlated with presence of fungal infection examination findings (p<0.05). Conclusion: Fungal infections were more frequently observed in the presence of poor glycemic control and peripheral vascular disease in diabetic patients in compliance with the literature, and the presence of fungal infection may also responsible for the development of foot ulcers. PMID:27648034

Experimental wave attenuation study over flexible plants on a submerged slope

NASA Astrophysics Data System (ADS)

Yin, Zegao; Yang, Xiaoyu; Xu, Yuanzhao; Ding, Meiling; Lu, Haixiang

2017-12-01

Using plants is a kind of environmentally-friendly coastal protection to attenuate wave energy. In this paper, a set of experiments were conducted to investigate the wave attenuation performance using flexible grasses on a submerged slope, and the wave attenuation coefficient for these experiments was calculated for different still water depths, slope and grass configurations. It was found that the slope plays a significant role in wave attenuation. The wave attenuation coefficient increases with increasing relative row number and relative density. For a small relative row number, the two configurations from the slope top to its toe and from the slope toe to its top performed equally to a large extent. For a medium relative row number, the configuration from the slope toe to its top performed more poorly than that from the slope top to its toe; however, it performed better than that from the slope top to its toe for a high relative row number. With a single row of grasses close to the slope top from the slope toe, the wave attenuation coefficient shows double peaks. With increasing grass rows or still water depth, the grass location corresponding to the maximum wave attenuation coefficient is close to the slope top. The dimensional analysis and the least square method were used to derive an empirical equation of the wave attenuation coefficient considering the effect of relative density, the slope, the relative row number and the relative location of the middle row, and the equation was validated to experimental data.

Changes in toe clearance during treadmill walking after long-duration spaceflight.

PubMed

Miller, Christopher A; Peters, Brian T; Brady, Rachel R; Richards, Jason R; Ploutz-Snyder, Robert J; Mulavara, Ajitkumar P; Bloomberg, Jacob J

2010-10-01

Astronauts exhibit sensorimotor changes upon return from long-duration spaceflight that can result in altered gait kinematics and possibly an increased risk of tripping. Toe trajectory during locomotion is a precise motor control task involving both legs, thus providing a composite metric of locomotor control. The purpose of this study was to determine whether astronauts are at an increased risk of tripping after their return from long-duration spaceflight. This was accomplished by assessing the pre- to postflight changes in toe clearance during treadmill walking. Ten crewmembers walked on a treadmill while performing a visual-acuity task pre- and postflight. In the three subjects on whom landing day data were available, each exhibited a characteristic of increased tripping risk on landing day: either a decreased median toe clearance or an increased interquartile range (a measure of variance). For all crewmembers, toe clearance median and interquartile range were not significantly different from preflight for the other postflight sessions (the earliest being 1 d after landing). A follow-up analysis showed that changes in foot pitch, ankle dorsiflexion, and pelvis roll angles were significant predictors of changes in toe clearance. The landing-day observations indicated an increased risk of tripping, which may pose a hazard during locomotion immediately upon return to Earth, especially in an emergency scenario. However, tripping risk on subsequent days was not different than preflight. The joint angle analysis suggested that the crewmembers tried to reestablish their normal walking pattern postflight, instead of developing a new motor control strategy.

A model for multiple-drop-impact erosion of brittle solids

NASA Technical Reports Server (NTRS)

Engel, O. G.

1971-01-01

A statistical model for the multiple-drop-impact erosion of brittle solids was developed. An equation for calculating the rate of erosion is given. The development is not complete since two quantities that are needed to calculate the rate of erosion with use of the equation must be assessed from experimental data. A partial test of the equation shows that it gives results that are in good agreement with experimental observation.

Issues of upscaling in space and time with soil erosion models

NASA Astrophysics Data System (ADS)

Brazier, R. E.; Parsons, A. J.; Wainwright, J.; Hutton, C.

2009-04-01

Soil erosion - the entrainment, transport and deposition of soil particles - is an important phenomenon to understand; the quantity of soil loss determines the long term on-site sustainability of agricultural production (Pimental et al., 1995), and has potentially important off-site impacts on water quality (Bilotta and Brazier, 2008). The fundamental mechanisms of the soil erosion process have been studied at the laboratory scale, plot scale (Wainwright et al., 2000), the small catchment scale (refs here) and river basin scale through sediment yield and budgeting work. Subsequently, soil erosion models have developed alongside and directly from this empirical work, from data-based models such as the USLE (Wischmeier and Smith, 1978), to ‘physics or process-based' models such as EUROSEM (Morgan et al., 1998) and WEPP (Nearing et al., 1989). Model development has helped to structure our understanding of the fundamental factors that control soil erosion process at the plot and field scale. Despite these advances, however, our understanding of and ability to predict erosion and sediment yield at the same plot, field and also larger catchment scales remains poor. Sediment yield has been shown to both increase and decrease as a function of drainage area (de Vente et al., 2006); the lack of a simple relationship demonstrates complex and scale-dependant process domination throughout a catchment, and emphasises our uncertainty and poor conceptual basis for predicting plot to catchment scale erosion rates and sediment yields (Parsons et al., 2006b). Therefore, this paper presents a review of the problems associated with modelling soil erosion across spatial and temporal scales and suggests some potential solutions to address these problems. The transport-distance approach to scaling erosion rates (Wainwright, et al., 2008) is assessed and discussed in light of alternative techniques to predict erosion across spatial and temporal scales. References Bilotta, G.S. and Brazier, R.E., 2008. Understanding the influence of suspended solids on water quality and aquatic biota. Water Research, 42(12): 2849-2861. de Vente, J., Poesen, J., Bazzoffi, P., Van Ropaey, A.V. and Verstraeten, G., 2006. Predicting catchment sediment yield in Mediterranean environments: the importance of sediment sources and connectivity in Italian drainage basins. Earth Surface Processes And Landforms, 31: 1017-1034. Morgan, R.P.C. et al., 1998. The European soil erosion model (EUROSEM): a dynamic approach for predicting sediment transport from fields to small catchments. Earth Surface Processes And Landforms, 23: 527-544. Nearing, M. A., G. R. Foster, L. J. Lane, and S. C. Finkner. 1989. A process-based soil erosion model for USDA Water Erosion Prediction Project technology. Trans. ASAE 32(5): 1587-1593. Parsons, A.J., Brazier, R.E., Wainwright, J. and Powell, D.M., 2006a. Scale relationships in hillslope runoff and erosion. Earth Surface Processes and Landforms, 31(11): 1384-1393. Parsons, A.J., Wainwright, J., Brazier, R.E. and Powell, D.M., 2006b. Is sediment delivery a fallacy? Earth Surface Processes and Landforms, 31(10): 1325-1328. Pimental, D. et al., 1995. Environmental and economic costs of soil erosion and conservation benefits. Science, 267:1117-1122. Wainwright, J., Parsons, A.J. and Abrahams, A.D., 2000. Plot-scale studies of vegetation, overland flow and erosion interactions: case studies from Arizona and New Mexico. Hydrological Processes, 14(16-17): 2921-2943. Wischmeier, W.H. and Smith, D.D., 1978. Predicting rainfall erosion losses - a guide for conservation planning., 537.

COMPARING 3D FOOT SHAPE MODELS BETWEEN TAIWANESE AND JAPANESE FEMALES.

PubMed

Lee, Yu-Chi; Kouchi, Makiko; Mochimaru, Masaaki; Wang, Mao-Jiun

2015-06-01

This study compares foot shape and foot dimensions between Taiwanese and Japanese females. One hundred Taiwanese and 100 Japanese female 3D foot scanning data were used for comparison. To avoid the allometry effect, data from 23 Taiwanese and 19 Japanese with foot length between 233 to 237 mm were used for shape comparison. Homologous models created for the right feet of the 42 subjects were analyzed by Multidimensional Scaling. The results showed that there were significant differences in the forefoot shape between the two groups, and Taiwanese females had slightly wider feet with straighter big toe than Japanese females. The results of body and foot dimension comparison indicated that Taiwanese females were taller, heavier and had larger feet than Japanese females, while Japanese females had significantly larger toe 1 angle. Since some Taiwanese shoemakers adopt the Japanese shoe sizing system for making shoes, appropriateness of the shoe sizing system was also discussed. The present results provide very useful information for improving shoe last design and footwear fit for Taiwanese females.

Integrated process-based hydrologic and ephemeral gully modeling for better assessment of soil erosion in small watersheds

NASA Astrophysics Data System (ADS)

Sheshukov, A. Y.; Karimov, V. R.

2017-12-01

Excessive soil erosion in agriculturally dominated watersheds causes degradation of arable land and affects agricultural productivity. Structural and soil-quality best management practices can be beneficial in reducing sheet and rill erosion, however, larger rills, ephemeral gullies, and concentrated flow channels still remain to be significant sources of sediment. A better understanding of channelized soil erosion, underlying physical processes, and ways to mitigate the problem is needed to develop innovative approaches for evaluation of soil losses from various sediment sources. The goal of this study was to develop a novel integrated process-based catchment-scale model for sheet, rill, and ephemeral gully erosion and assess soil erosion mitigation practices. Geospatially, a catchment was divided into ephemeral channels and contributing hillslopes. Surface runoff hydrograph and sheet-rill erosion rates from contributing hillslopes were calculated based on the Water Erosion Prediction Project (WEPP) model. For ephemeral channels, a dynamic ephemeral gully erosion model was developed. Each channel was divided into segments, and channel flow was routed according to the kinematic wave equation. Reshaping of the channel profile in each segment (sediment deposition, soil detachment) was simulated at each time-step according to acting shear stress distribution along the channel boundary and excess shear stress equation. The approach assumed physically-consistent channel shape reconfiguration representing channel walls failure and deposition in the bottom of the channel. Soil erodibility and critical shear stress parameters were dynamically adjusted due to seepage/drainage forces based on computed infiltration gradients. The model was validated on the data obtained from the field study by Karimov et al. (2014) yielding agreement with NSE coefficient of 0.72. The developed model allowed to compute ephemeral gully erosion while accounting for antecedent soil moisture conditions. Results showed significant differences in performance of management practices for initially dry and wet soils. Application of no-till and conversion to grassland significantly reduced the erosion rates compared to conventional tillage for small runoff events, while the efficiency was reduced for large events.

Advancements in Hydrology and Erosion Process Understanding and Post-Fire Hydrologic and Erosion Model Development for Semi-Arid Landscapes

NASA Astrophysics Data System (ADS)

Williams, C. Jason; Pierson, Frederick B.; Al-Hamdan, Osama Z.; Robichaud, Peter R.; Nearing, Mark A.; Hernandez, Mariano; Weltz, Mark A.; Spaeth, Kenneth E.; Goodrich, David C.

2017-04-01

Fire activity continues to increase in semi-arid regions around the globe. Private and governmental land management entities are challenged with predicting and mitigating post-fire hydrologic and erosion responses on these landscapes. For more than a decade, a team of scientists with the US Department of Agriculture has collaborated on extensive post-fire hydrologic field research and the application of field research to development of post-fire hydrology and erosion predictive technologies. Experiments funded through this research investigated the impacts of fire on vegetation and soils and the effects of these fire-induced changes on infiltration, runoff generation, erodibility, and soil erosion processes. The distribution of study sites spans diverse topography across grassland, shrubland, and woodland landscapes throughout the western United States. Knowledge gleaned from the extensive field experiments was applied to develop and enhance physically-based models for hillslope- to watershed-scale runoff and erosion prediction. Our field research and subsequent data syntheses have identified key knowledge gaps and challenges regarding post-fire hydrology and erosion modeling. Our presentation details some consistent trends across a diverse domain and varying landscape conditions based on our extensive field campaigns. We demonstrate how field data have advanced our understanding of post-fire hydrology and erosion for semi-arid landscapes and highlight remaining key knowledge gaps. Lastly, we briefly show how our well-replicated experimental methodologies have contributed to advancements in hydrologic and erosion model development for the post-fire environment.

Regional modeling of wind erosion in the North West and South West of Iran

NASA Astrophysics Data System (ADS)

Mirmousavi, S. H.

2016-08-01

About two-thirds of the Iran's area is located in the arid and semiarid region. Lack of soil moisture and vegetation is poor in most areas can lead to soil erosion caused by wind. So that the annual suffered severe damage to large areas of rich soils. Modeling studies of wind erosion in Iran is very low and incomplete. Therefore, this study aimed to wind erosion modeling, taking into three factors: wind speed, vegetation and soil types have been done. Wind erosion sensitivity was modeled using the key factors of soil sensitivity, vegetation cover and wind erodibility as proxies. These factors were first estimated separately by factor sensitivity maps and later combined by fuzzy logic into a regional-scale wind erosion sensitivity map. Large areas were evaluated by using publicly available datasets of remotely sensed vegetation information, soil maps and meteorological data on wind speed. The resulting estimates were verified by field studies and examining the economic losses from wind erosion as compensated by the state insurance company. The spatial resolution of the resulting sensitivity map is suitable for regional applications, as identifying sensitive areas is the foundation for diverse land development control measures and implementing management activities.

Evaluation of different machine learning models for predicting and mapping the susceptibility of gully erosion

NASA Astrophysics Data System (ADS)

Rahmati, Omid; Tahmasebipour, Nasser; Haghizadeh, Ali; Pourghasemi, Hamid Reza; Feizizadeh, Bakhtiar

2017-12-01

Gully erosion constitutes a serious problem for land degradation in a wide range of environments. The main objective of this research was to compare the performance of seven state-of-the-art machine learning models (SVM with four kernel types, BP-ANN, RF, and BRT) to model the occurrence of gully erosion in the Kashkan-Poldokhtar Watershed, Iran. In the first step, a gully inventory map consisting of 65 gully polygons was prepared through field surveys. Three different sample data sets (S1, S2, and S3), including both positive and negative cells (70% for training and 30% for validation), were randomly prepared to evaluate the robustness of the models. To model the gully erosion susceptibility, 12 geo-environmental factors were selected as predictors. Finally, the goodness-of-fit and prediction skill of the models were evaluated by different criteria, including efficiency percent, kappa coefficient, and the area under the ROC curves (AUC). In terms of accuracy, the RF, RBF-SVM, BRT, and P-SVM models performed excellently both in the degree of fitting and in predictive performance (AUC values well above 0.9), which resulted in accurate predictions. Therefore, these models can be used in other gully erosion studies, as they are capable of rapidly producing accurate and robust gully erosion susceptibility maps (GESMs) for decision-making and soil and water management practices. Furthermore, it was found that performance of RF and RBF-SVM for modelling gully erosion occurrence is quite stable when the learning and validation samples are changed.

Sediment erosion and delivery from Toutle River basin after the 1980 eruption of Mount St. Helens: A 30-year perspective

USGS Publications Warehouse

Major, Jon J.; Mosbrucker, Adam; Spicer, Kurt R.; Crisafulli, Charles; Dale, V.

2018-01-01

Exceptional sediment yields persist in Toutle River valley more than 30 years after the major 1980 eruption of Mount St. Helens. Differencing of decadal-scale digital elevation models shows the elevated load comes largely from persistent lateral channel erosion across the debris-avalanche deposit. Since the mid-1980s, rates of channel-bed-elevation change have diminished, and magnitudes of lateral erosion have outpaced those of channel incision. A digital elevation model of difference from 1999 to 2009 shows erosion across the debris-avalanche deposit is more spatially distributed compared to a model from 1987 to 1999, in which erosion was strongly focused along specific reaches of the channel.

Scenario Analysis of Soil and Water Conservation in Xiejia Watershed Based on Improved CSLE Model

NASA Astrophysics Data System (ADS)

Liu, Jieying; Yu, Ming; Wu, Yong; Huang, Yao; Nie, Yawen

2018-01-01

According to the existing research results and related data, use the scenario analysis method, to evaluate the effects of different soil and water conservation measures on soil erosion in a small watershed. Based on the analysis of soil erosion scenarios and model simulation budgets in the study area, it is found that all scenarios simulated soil erosion rates are lower than the present situation of soil erosion in 2013. Soil and water conservation measures are more effective in reducing soil erosion than soil and water conservation biological measures and soil and water conservation tillage measures.

Evaluating the influence of geo-environmental factors on gully erosion in a semi-arid region of Iran: An integrated framework.

PubMed

Rahmati, Omid; Tahmasebipour, Naser; Haghizadeh, Ali; Pourghasemi, Hamid Reza; Feizizadeh, Bakhtiar

2017-02-01

Despite the importance of soil erosion in sustainable development goals in arid and semi-arid areas, the study of the geo-environmental conditions and factors influencing gully erosion occurrence is rarely undertaken. As effort to this challenge, the main objective of this study is to apply an integrated approach of Geographic Object-Based Image Analysis (GEOBIA) together with high-spatial resolution imagery (SPOT-5) for detecting gully erosion features at the Kashkan-Poldokhtar watershed, Iran. We also aimed to apply a Conditional Probability (CP) model for establishing the spatial relationship between gullies and the Geo-Environmental Factors (GEFs). The gully erosion inventory map prepared using GEOBIA and field surveying was randomly partitioned into two subsets: (1) part 1 that contains 70% was used in the training phase of the CP model; (2) part 2 is a validation dataset (30%) for validation of the model and to confirm its accuracy. Prediction performances of the GEOBIA and CP model were checked by overall accuracy and Receiver Operating Characteristics (ROC) curve methods, respectively. In addition, the influence of all GEFs on gully erosion was evaluated by performing a sensitivity analysis model. The validation findings illustrated that overall accuracy for GEOBIA approach and the area under the ROC curve for the CP model were 92.4% and 89.9%, respectively. Also, based on sensitivity analysis, soil texture, drainage density, and lithology represent significantly effects on the gully erosion occurrence. This study has shown that the integrated framework can be successfully used for modeling gully erosion occurrence in a data-poor environment. Copyright © 2016 Elsevier B.V. All rights reserved.

Modeling soil erosion processes on a hillslope with dendritic rill network

NASA Astrophysics Data System (ADS)

Chen, L.; Wu, S.

2017-12-01

The effect of planform of dendritic rill network on hillslope rainfall-runoff and soil erosion processes was usually neglected in previous studies, which, however, could dramatically alter the mechanisms of the hydrologic and geomorphic processes. In the present study, the interrill areas were treated as two-dimensional (2D), while the complicated rill network was represented by a piecewise one-dimensional (1D) rill retaining the characteristic of rill network (the rill density and average rill deflection angle). Based on a 2D diffusive wave overland flow model, and the WEPP erosion theory, the 1D and 2D coupling model was developed to simulate the hillslope runoff and soil erosion on both the interrill areas and the representative rill. The rill number and rill inclination angle were introduced in the model to reflect the actual rill density, rill length, rill slope gradient, and confluence processes from the interrill areas to the rill. The excess rainfall and sediment load coming into the representative rill were not only from the two lateral interrill areas but also from the upstream interrill areas. The model was successfully tested against experimental data obtained from a hillslope with complicated rill network. Comparison of the results obtained from the present model with WEPP indicates that WEPP calculated the hillslope runoff yield accurately but overestimated the amount of rill erosion. Moreover, the effects of rill deflection angle and rill number distribution on both interrill and rill erosions were examined and found neglecting the planar characteristic of rill network has a considerable impact on soil erosion prediction. It is expected that the model can extend the scope of WEPP application and predict more accurately the runoff and erosion yield on a hillslope with complicated rill network.

Predictors of outcomes after arthroscopic transosseous equivalent rotator cuff repair in 155 cases: a propensity score weighted analysis of knotted and knotless self-reinforcing repair techniques at a minimum of 2 years.

PubMed

Millett, Peter J; Espinoza, Chris; Horan, Marilee P; Ho, Charles P; Warth, Ryan J; Dornan, Grant J; Christoph Katthagen, J

2017-10-01

To evaluate the outcomes of two commonly used transosseous-equivalent (TOE) arthroscopic rotator cuff repair (RCR) techniques for full-thickness supraspinatus tendon tears (FTST) using a robust multi-predictor model. 155 shoulders in 151 patients (109 men, 42 women; mean age 59 ± 10 years) who underwent arthroscopic RCR of FTST, using either a knotted suture bridging (KSB) or a knotless tape bridging (KTB) TOE technique were included. ASES and SF-12 PCS scores assessed at a minimum of 2 years postoperatively were modeled using propensity score weighting in a multiple linear regression model. Patients able to return to the study center underwent a follow-up MRI for evaluation of rotator cuff integrity. The outcome data were available for 137 shoulders (88%; n = 35/41 KSB; n = 102/114 KTB). Seven patients (5.1%) that underwent revision rotator cuff surgery were considered failures. The median postoperative ASES score of the remaining 130 shoulders was 98 at a mean follow-up of 2.9 years (range 2.0-5.4 years). A higher preoperative baseline outcome score and a longer follow-up had a positive effect, whereas a previous RCR and workers' compensation claims (WCC) had a negative effect on final ASES or SF 12 PCS scores. The repair technique, age, gender and the number of anchors used for the RCR had no significant influence. Fifty-two patients returned for a follow-up MRI at a mean of 4.4 years postoperatively. Patients with a KSB RCR were significantly more likely to have an MRI-diagnosed full-thickness rotator cuff re-tear (p < 0.05). Excellent outcomes can be achieved at a minimum of 2 years following arthroscopic KSB or KTB TOE RCR of FTST. The preoperative baseline outcome score, a prior RCR, WCC and the length of follow-up significantly influenced the outcome scores. The repair technique did not affect the final functional outcomes, but patients with KTB TOE RCR were less likely to have a full-thickness rotator cuff re-tear. Level III, Retrospective Comparative Study.

The use of spatial empirical models to estimate soil erosion in arid ecosystems.

PubMed

Abdullah, Meshal; Feagin, Rusty; Musawi, Layla

2017-02-01

The central objective of this project was to utilize geographical information systems and remote sensing to compare soil erosion models, including Modified Pacific South-west Inter Agency Committee (MPSIAC), Erosion Potential Method (EPM), and Revised Universal Soil Loss Equation (RUSLE), and to determine their applicability for arid regions such as Kuwait. The northern portion of Umm Nigga, containing both coastal and desert ecosystems, falls within the boundaries of the de-militarized zone (DMZ) adjacent to Iraq and has been fenced off to restrict public access since 1994. Results showed that the MPSIAC and EPM models were similar in spatial distribution of erosion, though the MPSIAC had a more realistic spatial distribution of erosion and presented finer level details. The RUSLE presented unrealistic results. We then predicted the amount of soil loss between coastal and desert areas and fenced and unfenced sites for each model. In the MPSIAC and EPM models, soil loss was different between fenced and unfenced sites at the desert areas, which was higher at the unfenced due to the low vegetation cover. The overall results implied that vegetation cover played an important role in reducing soil erosion and that fencing is much more important in the desert ecosystems to protect against human activities such as overgrazing. We conclude that the MPSIAC model is best for predicting soil erosion for arid regions such as Kuwait. We also recommend the integration of field-based experiments with lab-based spatial analysis and modeling in future research.

Thermographic Patterns of the Upper and Lower Limbs: Baseline Data

PubMed Central

Cassar, Kevin; Camilleri, Kenneth P.; De Raffaele, Clifford; Mizzi, Stephen; Cristina, Stefania

2015-01-01

Objectives. To collect normative baseline data and identify any significant differences between hand and foot thermographic distribution patterns in a healthy adult population. Design. A single-centre, randomized, prospective study. Methods. Thermographic data was acquired using a FLIR camera for the data acquisition of both plantar and dorsal aspects of the feet, volar aspects of the hands, and anterior aspects of the lower limbs under controlled climate conditions. Results. There is general symmetry in skin temperature between the same regions in contralateral limbs, in terms of both magnitude and pattern. There was also minimal intersubject temperature variation with a consistent temperature pattern in toes and fingers. The thumb is the warmest digit with the temperature falling gradually between the 2nd and the 5th fingers. The big toe and the 5th toe are the warmest digits with the 2nd to the 4th toes being cooler. Conclusion. Measurement of skin temperature of the limbs using a thermal camera is feasible and reproducible. Temperature patterns in fingers and toes are consistent with similar temperatures in contralateral limbs in healthy subjects. This study provides the basis for further research to assess the clinical usefulness of thermography in the diagnosis of vascular insufficiency. PMID:25648145

An uncommon presentation of non-small-cell lung cancer with acrometastases to the great toe and index finger.

PubMed

Reynolds, Jamie; Skandan, Savitri P

2016-03-01

Acrometastasis as initial presentation of metastatic cancer is an extremely rare finding. We describe an unusual case of late-stage non-small-cell lung cancer with metastatic lesions to the great toe and index fnger with associated pain in those areas as the only presenting symptom. A 71-year-old white woman was referred to the emergency department by her primary care physician for necrosis and swelling of the left great toe for work-up of possible osteomyelitis (Figure 1). Before she presented to her physician, she had been complaining of severe pain, swelling, and erythema of the left great toe that had lasted for 1-2 months. Infection was initially suspected. She completed 2 courses of oral antibiotics with no improvement. She was also complaining of similar symptoms on the left index finger and attributed her symptoms to an injury a month earlier (Figure 2). The pain was so severe that she was not able to bear weight on her left foot. An outpatient X-ray of her left great toe raised her physician's concerns that it might be osteomyelitis so she was referred to the emergency department. ©2016 Frontline Medical Communications.

A new small frog species of the genus Pristimantis (Anura: Craugastoridae) from the northern paramos of Colombia.

PubMed

González-Durán, Gustavo A

2016-01-18

I describe a new species of a small-sized frog of the genus Pristimantis found in the paramo ecosystem (3700 masl) on the northern slope of Los Nevados National Park, Cordillera Central, department of Caldas, Colombia. This new species is assigned to the Pristimantis leptolophus species-group, given that Toe V is much longer than Toe III and extends to the distal edge of the distal subarticular tubercle on Toe IV. The new species differs from other taxa by its dorsal golden or yellowish color patterns, the absence of nuptial pads, lateral fringes on its fingers and toes, and the absence of vomerine odontophores. Discriminant analyses of morphometric characters of females of P. leptolophus, P. uranobates, and the new species separate the new species by snout-vent length, tibia length, eye diameter, eye-to-nostril distance, tympanum diameter, and length of toe III. Vomer terms frequently used to describe species are reviewed, such as the oblique keels of the vomer and the different forms of the dentigerous process. Species belonging to the high Andean Pristimantis leptolophus species-group are allopatric, suggesting vicariant speciation in different areas of the paramos.

Assessment of leg muscle activity using toe tapping in patients with Parkinson's disease: comparison of two types of toe tapping.

PubMed

Taniguchi, Seira; Peper, Ferdinand; Shimokawa, Tetsuya

2018-05-01

[Purpose] This study investigates two types of toe tapping, i.e., "closed," with both feet on the floor, and "open," in which the foot does not touch the ground, and evaluates their usefulness in combination with monitoring of muscle activity during toe tapping. [Subjects and Methods] The study enrolled 11 patients with Parkinson's disease (PD) and 9 controls (Controls). The tibialis anterior (TA) and gastrocnemius (GS) muscle activity during toe tapping was measured using surface electromyography. [Results] In closed tapping, the minima in GS activation with the first tap was significantly higher in patients with PD than in Controls. In open tapping, the coefficient of variation (CV) of local maxima in TA activation was significantly higher in patients with PD than in Controls. In both types of tapping, the CV of extrema in GS activities increased with disease duration, but this may be due to the long-term administration of Levodopa, which itself tends to cause excessive GS activities. [Conclusion] Closed tapping is suitable for the assessment of GS activity and can detect excessive activities, which is observed as visible movement. Open tapping, on the other hand, is suitable for assessment of TA activity.

Modeling and analysis of Soil Erosion processes by the River Basins model: The Case Study of the Krivacki Potok Watershed, Montenegro

NASA Astrophysics Data System (ADS)

Vujacic, Dusko; Barovic, Goran; Mijanovic, Dragica; Spalevic, Velibor; Curovic, Milic; Tanaskovic, Vjekoslav; Djurovic, Nevenka

2016-04-01

The objective of this research was to study soil erosion processes in one of Northern Montenegrin watersheds, the Krivacki Potok Watershed of the Polimlje River Basin, using modeling techniques: the River Basins computer-graphic model, based on the analytical Erosion Potential Method (EPM) of Gavrilovic for calculation of runoff and soil loss. Our findings indicate a low potential of soil erosion risk, with 554 m³ yr-1 of annual sediment yield; an area-specific sediment yield of 180 m³km-2 yr-1. The calculation outcomes were validated for the entire 57 River Basins of Polimlje, through measurements of lake sediment deposition at the Potpec hydropower plant dam. According to our analysis, the Krivacki Potok drainage basin is with the relatively low sediment discharge; according to the erosion type, it is mixed erosion. The value of the Z coefficient was calculated on 0.297, what indicates that the river basin belongs to 4th destruction category (of five). The calculated peak discharge from the river basin was 73 m3s-1 for the incidence of 100 years and there is a possibility for large flood waves to appear in the studied river basin. Using the adequate computer-graphic and analytical modeling tools, we improved the knowledge on the soil erosion processes of the river basins of this part of Montenegro. The computer-graphic River Basins model of Spalevic, which is based on the EPM analytical method of Gavrilovic, is highly recommended for soil erosion modelling in other river basins of the Southeastern Europe. This is because of its reliable detection and appropriate classification of the areas affected by the soil loss caused by soil erosion, at the same time taking into consideration interactions between the various environmental elements such as Physical-Geographical Features, Climate, Geological, Pedological characteristics, including the analysis of Land Use, all calculated at the catchment scale.

Model development and applications at the USDA-ARS National Soil Erosion Research Laboratory

USDA-ARS?s Scientific Manuscript database

The United States Department of Agriculture (USDA) has a long history of development of soil erosion prediction technology, initially with empirical equations like the Universal Soil Loss Equation (USLE), and more recently with process-based models such as the Water Erosion Prediction Project (WEPP)...

Demonstration of the Water Erosion Prediction Project (WEPP) internet interface and services

USDA-ARS?s Scientific Manuscript database

The Water Erosion Prediction Project (WEPP) model is a process-based FORTRAN computer simulation program for prediction of runoff and soil erosion by water at hillslope profile, field, and small watershed scales. To effectively run the WEPP model and interpret results additional software has been de...

Numerical investigation and identification of susceptible sites of atherosclerotic lesion formation in a complete coronary artery bypass model.

PubMed

Zhang, Jun-Mei; Chua, Leok Poh; Ghista, Dhanjoo N; Yu, Simon Ching Man; Tan, Yong Seng

2008-07-01

As hemodynamics is widely believed to correlate with anastomotic stenosis in coronary bypass surgery, this paper investigates the flow characteristics and distributions of the hemodynamic parameters (HPs) in a coronary bypass model (which includes both proximal and distal anastomoses), under physiological flow conditions. Disturbed flows (flow separation/reattachment, vertical and secondary flows) as well as regions of high oscillatory shear index (OSI) with low wall shear stress (WSS), i.e., high-OSI-and-low-WSS and low-OSI-and-high-WSS were found in the proximal and distal anastomoses, especially at the toe and heel regions of distal anastomosis, which indicate highly suspected sites for the onset of the atherosclerotic lesions. The flow patterns found in the graft and distal anastomoses of our model at deceleration phases are different from those of the isolated distal anastomosis model. In addition, a huge significant difference in segmental averages of HPs was found between the distal and proximal anastomoses. These findings further suggest that intimal hyperplasia would be more prone to form in the distal anastomosis than in the proximal anastomosis, particularly along the suture line at the toe and heel of distal anastomosis.

Micro-topographic controls on hillslope erosion and deposition: a multi-scale case study using random forest

NASA Astrophysics Data System (ADS)

Lu, X.; Li, Y.; Washington-Allen, R. A.; Li, Y.

2017-12-01

Topography imposes a significant impact on water induced soil erosion and deposition. Although existing models incorporate topographic factors in the prediction of erosion, the topography of the hillslope is often considered as a whole and summarized as a single value, without accounting for the micro-variations within the hillslope created through factors including local roughness and channelization. Within-hillslope scale erosion and deposition and their micro-topographic controls are not well understood due to a lack of means to monitor and quantify the geomorphic change with high resolution and accuracy. Advances in remote sensing technology enabled mapping and quantification of erosion and deposition at such scale. On a hillslope in Loudoun Tennessee USA, we used laser scanning to produce temporal DEMs, based on which the erosion and deposition were calculated, and topographic factors including slope, aspect, roughness index, convergence index, terrain wetness index, channel depth, contributing area, and slope length-gradient were derived. To examine how these micro-topographic factors affect erosion and deposition, random forest regression models were used for erosion and deposition at two scales: analytical windows and rill basins (RBs). Two variables representing the impact of precipitation and freeze/thaw are also incorporated. Our models show that the influences of topographic variables on erosion and deposition differ regarding different analytical scales. The two variables denoting the relative location within a slope (elevation) and the RBs (contributing area) are the most important. Threshold effects show that the locations at low elevations are more subjective to more erosion and also more deposition, suggesting larger contributing areas lead to more dynamics regarding sediment exchange. The relative location along rill cross-sections (channel depth) is also important, especially for deposition. Thresholds show that along the cross-sections, erosion tends to occur on the sidewalls, while deposition mainly takes place on rill floors. The models showed better performance for erosion (R2 = 0.49 and 0.61 for window- and RB-based models) compared to deposition (R2 = 0.43 and 0.54 for window- and RB-based models) and were able to predict the spatial patterns of sediment movement.

[Estimation of the effect derived from wind erosion of soil and dust emission in Tianjin suburbs on the central district based on WEPS model].

PubMed

Chen, Li; Han, Ting-Ting; Li, Tao; Ji, Ya-Qin; Bai, Zhi-Peng; Wang, Bin

2012-07-01

Due to the lack of a prediction model for current wind erosion in China and the slow development for such models, this study aims to predict the wind erosion of soil and the dust emission and develop a prediction model for wind erosion in Tianjin by investigating the structure, parameter systems and the relationships among the parameter systems of the prediction models for wind erosion in typical areas, using the U.S. wind erosion prediction system (WEPS) as reference. Based on the remote sensing technique and the test data, a parameter system was established for the prediction model of wind erosion and dust emission, and a model was developed that was suitable for the prediction of wind erosion and dust emission in Tianjin. Tianjin was divided into 11 080 blocks with a resolution of 1 x 1 km2, among which 7 778 dust emitting blocks were selected. The parameters of the blocks were localized, including longitude, latitude, elevation and direction, etc.. The database files of blocks were localized, including wind file, climate file, soil file and management file. The weps. run file was edited. Based on Microsoft Visualstudio 2008, secondary development was done using C + + language, and the dust fluxes of 7 778 blocks were estimated, including creep and saltation fluxes, suspension fluxes and PM10 fluxes. Based on the parameters of wind tunnel experiments in Inner Mongolia, the soil measurement data and climate data in suburbs of Tianjin, the wind erosion module, wind erosion fluxes, dust emission release modulus and dust release fluxes were calculated for the four seasons and the whole year in suburbs of Tianjin. In 2009, the total creep and saltation fluxes, suspension fluxes and PM10 fluxes in the suburbs of Tianjin were 2.54 x 10(6) t, 1.25 x 10(7) t and 9.04 x 10(5) t, respectively, among which, the parts pointing to the central district were 5.61 x 10(5) t, 2.89 x 10(6) t and 2.03 x 10(5) t, respectively.

Geo-statistical model of Rainfall erosivity by using high temporal resolution precipitation data in Europe

NASA Astrophysics Data System (ADS)

Panagos, Panos; Ballabio, Cristiano; Borrelli, Pasquale; Meusburger, Katrin; Alewell, Christine

2015-04-01

Rainfall erosivity (R-factor) is among the 6 input factors in estimating soil erosion risk by using the empirical Revised Universal Soil Loss Equation (RUSLE). R-factor is a driving force for soil erosion modelling and potentially can be used in flood risk assessments, landslides susceptibility, post-fire damage assessment, application of agricultural management practices and climate change modelling. The rainfall erosivity is extremely difficult to model at large scale (national, European) due to lack of high temporal resolution precipitation data which cover long-time series. In most cases, R-factor is estimated based on empirical equations which take into account precipitation volume. The Rainfall Erosivity Database on the European Scale (REDES) is the output of an extensive data collection of high resolution precipitation data in the 28 Member States of the European Union plus Switzerland taking place during 2013-2014 in collaboration with national meteorological/environmental services. Due to different temporal resolutions of the data (5, 10, 15, 30, 60 minutes), conversion equations have been applied in order to homogenise the database at 30-minutes interval. The 1,541 stations included in REDES have been interpolated using the Gaussian Process Regression (GPR) model using as covariates the climatic data (monthly precipitation, monthly temperature, wettest/driest month) from WorldClim Database, Digital Elevation Model and latitude/longitude. GPR has been selected among other candidate models (GAM, Regression Kriging) due the best performance both in cross validation (R2=0.63) and in fitting dataset (R2=0.72). The highest uncertainty has been noticed in North-western Scotland, North Sweden and Finland due to limited number of stations in REDES. Also, in highlands such as Alpine arch and Pyrenees the diversity of environmental features forced relatively high uncertainty. The rainfall erosivity map of Europe available at 500m resolution plus the standard error and the erosivity density (Rainfall erosivity per mm of precipitation) are available in the European Soil Data Centre (ESDAC). The highest erosivity has been found in the mediterrean countries (Italy, Western Greece, Spain, Northern Portugal), South Austria, Slovenia, Croatia and Western United Kingdom.

[Lesser toe deformities. Definition, pathogenesis, and options for surgical correction].

PubMed

Arnold, H

2005-08-01

Whereas in the past resection arthroplasty was - in analogy to hallux valgus surgery - the preferred therapy to correct lesser toe deformities, the point of view has undergone a change. Much interest is directed toward functional aspects that require reconstructive management. Whenever possible the integrity of joint play should be saved. Above all the metatarsophalangeal joint of the lesser toes is worth being preserved to prevent a severe disturbance of the biomechanics of the foot. Tendon transfers and subtle corrective osteotomies such as the Weil procedure allow restricting resection procedures to contraction deformities.

Improvisation in wrap-around toe-to-thumb transfer.

PubMed

Govila, A

1993-01-01

Wrap-around partial great toe transfer, a one time dream, is now a well established and universally accepted method of thumb reconstruction. In this technique, part of the soft tissue of the great toe are wrapped around and shaped to the size of the graft from iliac bone in such a manner that a thumb of normal dimensions and shape is produced. Instead of the iliac bone graft, we found great merit in using the second metacarpal from the traumatised hand to be reconstructed. In this paper its use and merits are elaborated.

A new treatment for parrot beak deformity of the toe.

PubMed

Kurokawa, M; Isshiki, N; Inoue, K

1994-03-01

Two cases of congenital parrot beak deformity of the toe were treated by pushing back the nail plate, nailbed, matrix, and proximal skin fold in one piece as a flap. The proximal skin portion of this flap was deepithelialized to facilitate this shift, and thus no dog-ear deformity was produced. The distal skin defect of the pulp was covered by a palmar advancement flap. This method does not require augmentation of the fingertip or toetip and is very useful for correcting parrot beak deformities of the toes.

Intercalary non-vascularised toe phalanx transplantation for short finger-type symbrachydactyly.

PubMed

Kanauchi, Yumiko; Takahara, Masatoshi; Ogino, Toshihiko; Kashiwa, Hideo; Ishigaki, Daisuke

2003-12-01

A two-year-old boy with short finger-type symbrachydactyly involving the index, middle, and ring fingers was treated with intercalary nonvascularised toe phalanx transplantation into the middle finger to obtain stability of the middle finger before syndactyly release. He underwent syndactyly release one year after the transplantation. Two years after the transplantation, the clinical result was satisfactory, although X-ray showed fibrous union between the transplanted phalanx and the host phalanx. Intercalary nonvascularised toe phalanx transplantation is one of the way of stabilising a finger after syndactyly release.

Double second toe transfer in congenital hand anomalies.

PubMed

Van Holder, C; Giele, H; Gilbert, A

1999-08-01

A series of 14 patients with congenital hand anomalies who received staged double second toe transfers to the same hand for restoration of function or form were reviewed retrospectively. There were three children with constriction ring syndrome, two with symbrachydactyly and nine with transverse absence (failure of formation). There were different indications, technical difficulties and results with the various anomalies. All transferred toes were mobile and sensate, and were reported to be of benefit in both function and appearance. However, secondary surgical procedures were required in all patients.

Calculation of Beach Change Under Interacting Cross-Shore and Longshore Processes

DTIC Science & Technology

2010-01-01

the dune toe , berm width, and shoreline position are calculated, while maintaining longshore transport rates representative of the regional long-term...during growth together with the dune shape, the seaward movement of the dune toe ΔyDw for a given increase in dune volume ΔVDw is: ΔyDw = ΔVDw DD ð2Þ...Expressing Eq. (1) in terms of dune toe advance yields: dyDw dt = qw DD ð3Þ It is assumed that sand transport to the dune is related to thewidth of the

Quantifying and modeling soil erosion and sediment export from construction sites in southern California

NASA Astrophysics Data System (ADS)

Wernet, A. K.; Beighley, R. E.

2006-12-01

Soil erosion is a power process that continuously alters the Earth's landscape. Human activities, such as construction and agricultural practices, and natural events, such as forest fires and landslides, disturb the landscape and intensify erosion processes leading to sudden increases in runoff sediment concentrations and degraded stream water quality. Understanding soil erosion and sediment transport processes is of great importance to researchers and practicing engineers, who routinely use models to predict soil erosion and sediment movement for varied land use and climate change scenarios. However, existing erosion models are limited in their applicability to constructions sites which have highly variable soil conditions (density, moisture, surface roughness, and best management practices) that change often in both space and time. The goal of this research is to improve the understanding, predictive capabilities and integration of treatment methodologies for controlling soil erosion and sediment export from construction sites. This research combines modeling with field monitoring and laboratory experiments to quantify: (a) spatial and temporal distribution of soil conditions on construction sites, (b) soil erosion due to event rainfall, and (c) potential offsite discharge of sediment with and without treatment practices. Field sites in southern California were selected to monitor the effects of common construction activities (ex., cut/fill, grading, foundations, roads) on soil conditions and sediment discharge. Laboratory experiments were performed in the Soil Erosion Research Laboratory (SERL), part of the Civil and Environmental Engineering department at San Diego State University, to quantify the impact of individual factors leading to sediment export. SERL experiments utilize a 3-m by 10-m tilting soil bed with soil depths up to 1 m, slopes ranging from 0 to 50 percent, and rainfall rates up to 150 mm/hr (6 in/hr). Preliminary modeling, field and laboratory results are presented.

The detailed measurement of foot clearance by young adults during stair descent.

PubMed

Telonio, A; Blanchet, S; Maganaris, C N; Baltzopoulos, V; McFadyen, B J

2013-04-26

Foot clearance is an important variable for understanding safe stair negotiation, but few studies have provided detailed measures of it. This paper presents a new method to calculate minimal shoe clearance during stair descent and compares it to previous literature. Seventeen healthy young subjects descended a five step staircase with step treads of 300 mm and step heights of 188 mm. Kinematic data were collected with an Optotrak system (model 3020) and three non-colinear infrared markers on the feet. Ninety points were digitized on the foot sole prior to data collection using a 6 marker probe and related to the triad of markers on the foot. The foot sole was reconstructed using the Matlab (version 7.0) "meshgrid" function and minimal distance to each step edge was calculated for the heel, toe and foot sole. Results showed significant differences in minimum clearance between sole, heel and toe, with the shoe sole being the closest and the toe the furthest. While the hind foot sole was closest for 69% of the time, the actual minimum clearance point on the sole did vary across subjects and staircase steps. This new method, and the findings on healthy young subjects, can be applied to future studies of other populations and staircase dimensions. Copyright © 2013 Elsevier Ltd. All rights reserved.

Modeling the erosion of tropical volcanic ocean islands : The Tahiti island case (French Polynesia)

NASA Astrophysics Data System (ADS)

Ye, F.; Sichoix, L.; Barriot, J.; Dumas, P.

2009-12-01

In this study, we are interested in modeling the erosion of the Tahiti island, with two main objectives: risk assessment (erodibility of terrains with rainfall, catastrophic runoffs) and estimation of subsidence rate. The Tahiti island created around 1.4 Myears ago by an intraplate hotspot (aerial radiometric dating), is divided into two geological units: the main island Tahiti-Nui to northwest (end of volcanism 200,000 years ago) and the subsidiary Tahiti-Iti to the southeast (end of volcanism 380,000 years ago). It is now volcanically inactive and is deeply dissected by erosion. Tahiti Nui is around 30 km in diameter, and Tahiti Iti around 15 km. Both are linked through the isthmus of Taravao. The highest elevation is 2241 m. The two sub-islands are basaltic edifices, with an overwhelming presence of oxisols (down to tens of meters in some places). Slopes can be divided into three classes: 15° for the global slope of the shield volcanoes, 47° for the incision valleys and 2° for the seashore rim. Rainfalls range from 8,000 mm/year on the East side of Tahiti (trade winds) to 2,000 mm/year on the West side, the humid season of a year is summer. This study is conducted to validate the Unit Stream Power Erosion and Deposition (USPED) model, an enrichment to the Universal Soil Loss Equation (USLE) to calculate average annual soil loss per unit land area resulting from rill and sheet erosion. The USPED model differs from other USLE models on how it handles the influence of topography on the erosion process, because USLE consider erosion only along the flow line without the influence of flow convergence/divergence. As the result, the USPED model predicts both erosion and deposition, while most other USLE-based models are limited to predictions of erosion only. The USLE, USPED equation can be written as A=R*K*LS*C*P where A is the soil loss, R the rainfall-runoff erosivity factor, K a soil erodibility factor, L a slope-length factor, S a slope steepness factor, C a cover-management factor and P a supporting practice factor. However, USPED adds a dimensionless index of sediment transport capacity and a topographic index, representing the change in transport capacity in the flow direction, to estimate the spatial distribution of both erosion and deposition. As an application, we show how this approach permits a better modeling of the soil losses in Tahiti with respect to the basic USLE-only approach, with both societal and risk-assessment benefits. Keywords: erosion, volcano, modeling, USLE, USPED

Soil erosion by snow gliding - a first quantification attempt in a sub-alpine area, Switzerland

NASA Astrophysics Data System (ADS)

Meusburger, K.; Leitinger, G.; Mabit, L.; Mueller, M. H.; Walter, A.; Alewell, C.

2014-03-01

Snow processes might be one important driver of soil erosion in Alpine grasslands and thus the unknown variable when erosion modelling is attempted. The aim of this study is to assess the importance of snow gliding as soil erosion agent for four different land use/land cover types in a sub-alpine area in Switzerland. We used three different approaches to estimate soil erosion rates: sediment yield measurements in snow glide deposits, the fallout radionuclide 137Cs, and modelling with the Revised Universal Soil Loss Equation (RUSLE). The RUSLE model is suitable to estimate soil loss by water erosion, while the 137Cs method integrates soil loss due to all erosion agents involved. Thus, we hypothesise that the soil erosion rates determined with the 137Cs method are higher and that the observed discrepancy between the soil erosion rate of RUSLE and the 137Cs method is related to snow gliding and sediment concentrations in the snow glide deposits. Cumulative snow glide distance was measured for the sites in the winter 2009/10 and modelled for the surrounding area with the Spatial Snow Glide Model (SSGM). Measured snow glide distance ranged from 2 to 189 cm, with lower values at the north facing slopes. We observed a reduction of snow glide distance with increasing surface roughness of the vegetation, which is important information with respect to conservation planning and expected land use changes in the Alps. Our hypothesis was confirmed: the difference of RUSLE and 137Cs erosion rates was related to the measured snow glide distance (R2= 0.64; p < 0.005) and snow sediment yields (R2 = 0.39; p = 0.13). A high difference (lower proportion of water erosion compared to total net erosion) was observed for high snow glide rates and vice versa. The SSGM reproduced the relative difference of the measured snow glide values under different land uses and land cover types. The resulting map highlighted the relevance of snow gliding for large parts of the investigated area. Based on these results, we conclude that snow gliding is a key process impacting soil erosion pattern and magnitude in sub-alpine areas with similar topographic and climatic conditions.

Rock riprap design for protection of stream channels near highway structures; Volume 2, Evaluation of Riprap design procedures

USGS Publications Warehouse

Blodgett, J.C.; McConaughy, C.E.

1986-01-01

In volume 2, seven procedures now being used for design of rock riprap installations were evaluated using data from 26 field sites. Four basic types of riprap failures were identified: Particle erosion, translational slide, modified slump, and slump. Factors associated with riprap failure include stone size , bank side slope, size gradation, thickness, insufficient toe or endwall, failure of the bank material, overtopping during floods, and geomorphic changes in the channel. A review of field data and the design procedures suggests that estimates of hydraulic forces acting on the boundary based on flow velocity rather than shear stress are more reliable. Several adjustments for local conditions, such as channel curvature, superelevation, or boundary roughness, may be unwarranted in view of the difficulty in estimating critical hydraulic forces for which the riprap is to be designed. Success of the riprap is related not only to the appropriate procedure for selecting stone size, but also to the reliability of estimated hydraulic and channel factors applicable to the site. (See also W89-04910) (Author 's abstract)

A preliminary assessment of the impact of landslide, earthflow, and gully erosion on soil carbon stocks in New Zealand

NASA Astrophysics Data System (ADS)

Basher, Les; Betts, Harley; Lynn, Ian; Marden, Mike; McNeill, Stephen; Page, Mike; Rosser, Brenda

2018-04-01

In geomorphically active landscapes such as New Zealand, quantitative data on the relationship between erosion and soil carbon (C) are needed to establish the effect of erosion on past soil C stocks and future stock changes. The soil C model currently used in New Zealand for soil C stock reporting does not account for erosion. This study developed an approach to characterise the effect of erosion suitable for soil C stock reporting and provides an initial assessment of the magnitude of the effect of erosion. A series of case studies were used to establish the local effect of landslide, earthflow, and gully erosion on soil C stocks and to compare field measurements of soil C stocks with model estimates. Multitemporal erosion mapping from orthophotographs was used to characterise erosion history, identify soil sampling plot locations, and allow soil C stocks to be calculated accounting for erosion. All eroded plots had lower soil C stocks than uneroded (by mass movement and gully erosion) plots sampled at the same sites. Landsliding reduces soil C stocks at plot and landscape scale, largely as a result of individual large storms. After about 70 years, soil C stocks were still well below the value measured for uneroded plots (by 40% for scars and 20-30% for debris tails) indicating that the effect of erosion is very persistent. Earthflows have a small effect on estimates of baseline (1990) soil C stocks and reduce soil C stocks at landscape scale. Gullies have local influence on soil C stocks but because they cover a small proportion of the landscape have little influence at landscape scale. At many of the sites, the soil C model overestimates landscape-scale soil C stocks.

Five- and 10-Year Follow-Up of Nonvascularized Toe Phalanx Transfers.

PubMed

Kawabata, Hidehiko; Tamura, Daisuke

2018-05-01

The purpose of this study was to evaluate long-term outcomes of nonvascularized toe phalanx transfer. We retrospectively reviewed 54 nonvascularized toe phalanx transfers in 29 children with symbrachydactyly. Forty-seven transfers in 24 children were evaluated at 5-year follow-up and 27 transfers in 14 children were evaluated at 10-year follow-up. We recorded the incidence of the early physeal closure and the length of the transferred toe phalanx on plain radiographs at 5- and 10-year follow-up. Growth rate in the first 5 years and the following 5 years were calculated. Function of the metacarpophalangeal joint (motion, stability, and alignment) was also evaluated. The mean age at surgery was 1.5 years. Seven toe phalanges were trimmed because the skin pocket was tight. Five transfers required revision surgery for partial necrosis of the skin pocket. At 5-year follow-up, the physis was closed in 23%, and at 10 years, 78% of physes were closed. The phalanx length was 87% of expected at 5-year follow-up and 71% at 10-year follow-up. Growth rate was 0.83 mm/y in the first 5 years and 0.22 mm/y in the following 5 years. Active motion was rated as good in 24, fair in 7, and poor in 16. Stability and alignment were rated as good in 37 and 33, fair in 8 and 5, and poor in 2 and 9, respectively. Nonvascularized toe phalanx transfer offered a relatively simple method to lengthen short digits and to provide satisfactory function. The transferred toe phalanges grew at a near-normal rate in the first 5 years, but the growth rate decreased between 5 and 10 years. Therapeutic IV. Copyright © 2018 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

Prediction of Soil Erosion Rates in Japan where Heavily Forested Landscape with Unstable Terrain

NASA Astrophysics Data System (ADS)

Nanko, K.; Oguro, M.; Miura, S.; Masaki, T.

2016-12-01

Soil is fundamental for plant growth, water conservation, and sustainable forest management. Multidisciplinary interest in the role of the soil in areas such as biodiversity, ecosystem services, land degradation, and water security has been growing (Miura et al., 2015). Forest is usually protective land use from soil erosion because vegetation buffers rainfall power and erosivity. However, some types of forest in Japan show high susceptibility to soil erosion due to little ground cover and steep slopes exceeding thirty degree, especially young Japanese cypress (Chamaecyparis obtusa) plantations (Miura et al., 2002). This is a critical issue for sustainable forest management because C. obtusaplantations account for 10% of the total forest coverage in Japan (Forestry Agency, 2009). Prediction of soil erosion rates on nationwide scale is necessary to make decision for future forest management plan. To predict and map soil erosion rates across Japan, we applied three soil erosion models, RUSLE (Revised Universal Soil Loss Equation, Wischmeier and Smith, 1978), PESERA (Pan-European Soil Erosion Risk Assessment, Kirkby et al., 2003), and RMMF (Revised Morgan-Morgan-Finney, Morgan, 2001). The grid scale is 1-km. RUSLE and PESERA are most widely used erosion models today. RMMF includes interactions between rainfall and vegetation, such as canopy interception and ratio of canopy drainage in throughfall. Evaporated rainwater by canopy interception, generally accounts for 15-20% in annual rainfall, does not contribute soil erosion. Whereas, larger raindrops generated by canopy drainage produced higher splash erosion rates than gross rainfall (Nanko et al., 2008). Therefore, rainfall redistribution process in canopy should be considered to predict soil erosion rates in forested landscape. We compared the results from three erosion models and analyze the importance of environmental factors for the prediction of soil erosion rates. This research was supported by the Environment Research and Technology Development Fund (S15-2-2) of the Ministry of the Environment, Japan.

Soil erosion under climate change in Great Britain: long-term simulations using high-resolution regional models

NASA Astrophysics Data System (ADS)

Ciampalini, Rossano; Kendon, Elizabeth; Constantine, José Antonio; Schindewolf, Marcus; Hall, Ian

2016-04-01

Twenty-first century climate change simulations for Great Britain reveal an increase in heavy precipitation that may lead to widespread soil loss and reduced soil carbon stores by increasing the likelihood of surface runoff. We find the quality and resolution of the simulated rainfall used to drive soil loss variation can widely influence the results. Hourly high definition rainfall simulations from a 1.5km resolution regional climate model are used to examine the soil erosion response in two UK catchments. The catchments have different sensitivity to soil erosion. "Rother" in West Sussex, England, reports some of the most erosive events that have been observed during the last 50 years in the UK. "Conwy" in North Wales, is resilient to soil erosion because of the abundant natural vegetation cover and very limited agricultural practises. We modelled with Erosion3D to check variations in soil erosion as influenced by climate variations for the periods 1996-2009 and 2086-2099. Our results indicate the Rother catchment is the most erosive, while the Conwy catchment is confirmed as the more resilient to soil erosion. The values of the reference-base period are consistent with the values of those locally observed in the previous decades. A soil erosion comparison for the two periods shows an increasing of sediment production (off-site erosion) for the end of the century at about 27% in the Rother catchment and about 50% for the Conwy catchment. The results, thanks to high-definition rainfall predictions, throw some light on the effect of climatic change effects in Great Britain.

Climate change impact on soil erosion in the Mandakini River Basin, North India

NASA Astrophysics Data System (ADS)

Khare, Deepak; Mondal, Arun; Kundu, Sananda; Mishra, Prabhash Kumar

2017-09-01

Correct estimation of soil loss at catchment level helps the land and water resources planners to identify priority areas for soil conservation measures. Soil erosion is one of the major hazards affected by the climate change, particularly the increasing intensity of rainfall resulted in increasing erosion, apart from other factors like landuse change. Changes in climate have an adverse effect with increasing rainfall. It has caused increasing concern for modeling the future rainfall and projecting future soil erosion. In the present study, future rainfall has been generated with the downscaling of GCM (Global Circulation Model) data of Mandakini river basin, a hilly catchment in the state of Uttarakhand, India, to obtain future impact on soil erosion within the basin. The USLE is an erosion prediction model designed to predict the long-term average annual soil loss from specific field slopes in specified landuse and management systems (i.e., crops, rangeland, and recreational areas) using remote sensing and GIS technologies. Future soil erosion has shown increasing trend due to increasing rainfall which has been generated from the statistical-based downscaling method.

How to "Read" Your Shoes

MedlinePlus

... the Big Toe Ailments of the Smaller Toes Diabetic Foot Treatments Injections and other Procedures Treatments of the ... Find a Surgeon Información en Español Foot Health Foot ... Diabetic Shoes 10 Points of Proper Shoe Fit All ...

Effects of Long-duration Space Flight on Toe Clearance During Treadmill Walking

NASA Technical Reports Server (NTRS)

Miller, Chris; Peters, Brian; Brady, Rachel; Mulavara, Ajitkumar; Richards, Jason; Hayat, Matthew; Bloomberg, Jacob

2008-01-01

Upon returning from long-duration space flight, astronauts and cosmonauts must overcome physiologic and sensorimotor changes induced by prolonged exposure to microgravity as they readapt to a gravitational environment. Their compromised balance and coordination lead to an altered and more variable walking pattern (Bloomberg & Mulavara, 2003; McDonald, et al., 1996). Toe trajectory during the swing phase of locomotion has been identified as a precise motor control task (Karst, et al., 1999), thus providing an indication of the coordination of the lower limbs (Winter, 1992). Failure to achieve sufficient toe clearance may put the crew member at a greater risk of tripping and falling, especially if an emergency egress from the vehicle should be necessary upon landing. The purpose of this study was to determine the pre- to post-flight changes in toe clearance in crew members returning from long-duration missions and the recovery thereafter.

Experimental rill erosion research vs. model concepts - quantification of the hydraulic and erosional efficiency of rills

NASA Astrophysics Data System (ADS)

Wirtz, Stefan

2014-05-01

In soil erosion research, rills are believed to be one of the most efficient forms. They act as preferential flow paths for overland flow and hence become the most efficient sediment sources in a catchment. However their fraction of the overall detachment in a certain area compared to other soil erosion processes is contentious. The requirement for handling this subject is the standardization of the used measurement methods for rill erosion quantification. Only by using a standardized method, the results of different studies become comparable and can be synthesized to one overall statement. In rill erosion research, such a standardized field method was missing until now. Hence, the first aim of this study is to present an experimental setup that enables us to obtain comparable data about process dynamics in eroding rills under standardized conditions in the field. Using this rill experiment, the runoff efficiency of rills (second aim) and the fraction of rill erosion on total soil loss (third aim) in a catchment are quantified. The erosion rate [g m-2] in the rills is between twenty- and sixty-times higher compared to the interrill areas, the specific discharge [L s-1 m-2] in the rills is about 2000 times higher. The identification and quantification of different rill erosion processes are the fourth aim within this project. Gravitative processes like side wall failure, headcut- and knickpoint retreat provide up to 94 % of the detached sediment quantity. In soil erosion models, only the incision into the rill's bottom is considered, hence the modelled results are unsatisfactorily. Due to the low quality of soil erosion model results, the fifth aim of the study is to review two physical basic assumptions using the rill experiments. Contrasting with the model assumptions, there is no clear linear correlation between any hydraulic parameter and the detachment rate and the transport rate is capable of exceeding the transport capacity. In conclusion, the results clearly show the need of experimental field data obtained under conditions as close as possible to reality. This is the only way to improve the fundamental knowledge about the function and the impact of the different processes in rill erosion. A better understanding of the process combinations is a fundamental request for developing a really functioning soil erosion model. In such a model, spatial and temporal variability as well as the combination of different sub-processes must be considered. Regarding the experimental results of this study, the simulation of natural processes using simple, static mathematical equations seems not to be possible.

Regional soil erosion assessment based on a sample survey and geostatistics

NASA Astrophysics Data System (ADS)

Yin, Shuiqing; Zhu, Zhengyuan; Wang, Li; Liu, Baoyuan; Xie, Yun; Wang, Guannan; Li, Yishan

2018-03-01

Soil erosion is one of the most significant environmental problems in China. From 2010 to 2012, the fourth national census for soil erosion sampled 32 364 PSUs (Primary Sampling Units, small watersheds) with the areas of 0.2-3 km2. Land use and soil erosion controlling factors including rainfall erosivity, soil erodibility, slope length, slope steepness, biological practice, engineering practice, and tillage practice for the PSUs were surveyed, and the soil loss rate for each land use in the PSUs was estimated using an empirical model, the Chinese Soil Loss Equation (CSLE). Though the information collected from the sample units can be aggregated to estimate soil erosion conditions on a large scale; the problem of estimating soil erosion condition on a regional scale has not been addressed well. The aim of this study is to introduce a new model-based regional soil erosion assessment method combining a sample survey and geostatistics. We compared seven spatial interpolation models based on the bivariate penalized spline over triangulation (BPST) method to generate a regional soil erosion assessment from the PSUs. Shaanxi Province (3116 PSUs) in China was selected for the comparison and assessment as it is one of the areas with the most serious erosion problem. Ten-fold cross-validation based on the PSU data showed the model assisted by the land use, rainfall erosivity factor (R), soil erodibility factor (K), slope steepness factor (S), and slope length factor (L) derived from a 1 : 10 000 topography map is the best one, with the model efficiency coefficient (ME) being 0.75 and the MSE being 55.8 % of that for the model assisted by the land use alone. Among four erosion factors as the covariates, the S factor contributed the most information, followed by K and L factors, and R factor made almost no contribution to the spatial estimation of soil loss. The LS factor derived from 30 or 90 m Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) data worsened the estimation when used as the covariates for the interpolation of soil loss. Due to the unavailability of a 1 : 10 000 topography map for the entire area in this study, the model assisted by the land use, R, and K factors, with a resolution of 250 m, was used to generate the regional assessment of the soil erosion for Shaanxi Province. It demonstrated that 54.3 % of total land in Shaanxi Province had annual soil loss equal to or greater than 5 t ha-1 yr-1. High (20-40 t ha-1 yr-1), severe (40-80 t ha-1 yr-1), and extreme ( > 80 t ha-1 yr-1) erosion occupied 14.0 % of the total land. The dry land and irrigated land, forest, shrubland, and grassland in Shaanxi Province had mean soil loss rates of 21.77, 3.51, 10.00, and 7.27 t ha-1 yr-1, respectively. Annual soil loss was about 207.3 Mt in Shaanxi Province, with 68.9 % of soil loss originating from the farmlands and grasslands in Yan'an and Yulin districts in the northern Loess Plateau region and Ankang and Hanzhong districts in the southern Qingba mountainous region. This methodology provides a more accurate regional soil erosion assessment and can help policymakers to take effective measures to mediate soil erosion risks.

Erosion of Northern Hemisphere blanket peatlands under 21st-century climate change

NASA Astrophysics Data System (ADS)

Li, Pengfei; Holden, Joseph; Irvine, Brian; Mu, Xingmin

2017-04-01

Peatlands are important terrestrial carbon stores particularly in the Northern Hemisphere. Many peatlands, such as those in the British Isles, Sweden, and Canada, have undergone increased erosion, resulting in degraded water quality and depleted soil carbon stocks. It is unclear how climate change may impact future peat erosion. Here we use a physically based erosion model (Pan-European Soil Erosion Risk Assessment-PEAT), driven by seven different global climate models (GCMs), to predict fluvial blanket peat erosion in the Northern Hemisphere under 21st-century climate change. After an initial decline, total hemispheric blanket peat erosion rates are found to increase during 2070-2099 (2080s) compared with the baseline period (1961-1990) for most of the GCMs. Regional erosion variability is high with changes to baseline ranging between -1.27 and +21.63 t ha-1 yr-1 in the 2080s. These responses are driven by effects of temperature (generally more dominant) and precipitation change on weathering processes. Low-latitude and warm blanket peatlands are at most risk to fluvial erosion under 21st-century climate change.

Understanding soil erosion impacts in temperate agroecosystems: bridging the gap between geomorphology and soil ecology using nematodes as a model organism

NASA Astrophysics Data System (ADS)

Baxter, C.; Rowan, J. S.; McKenzie, B. M.; Neilson, R.

2013-11-01

Soil is a key asset of natural capital, providing a myriad of goods and ecosystem services that sustain life through regulating, supporting and provisioning roles, delivered by chemical, physical and biological processes. One of the greatest threats to soil is accelerated erosion, which raises a natural process to unsustainable levels, and has downstream consequences (e.g.~economic, environmental and social). Global intensification of agroecosystems is a recognised major cause of soil erosion which, in light of predicted population growth and increased demand for food security, will continue or increase. Transport and redistribution of biota by soil erosion has hitherto been ignored and thus is poorly understood. With the move to sustainable intensification this is a key knowledge gap that needs to be addressed. Here we highlight the erosion-energy and effective-erosion-depth continuum in soils, differentiating between different forms of soil erosion, and argue that nematodes are an appropriate model taxa to investigate impacts of erosion on soil biota across scales. We review the different known mechanisms of soil erosion that impact on soil biota in general, and nematodes in particular, and highlight the few detailed studies, primarily from tropical regions, that have considered soil biota. Based on the limited literature and using nematodes as a model organism we outline future research priorities to initially address the important interrelationships between soil erosion processes and soil biota.

The management submodel of the Wind Erosion Prediction System

USDA-ARS?s Scientific Manuscript database

The Wind Erosion Prediction System (WEPS) is a process-based, daily time-step, computer model that predicts soil erosion via simulation of the physical processes controlling wind erosion. WEPS is comprised of several individual modules (submodels) that reflect different sets of physical processes, ...

Estimates of soil erosion using cesium-137 tracer models.

PubMed

Saç, M M; Uğur, A; Yener, G; Ozden, B

2008-01-01

The soil erosion was studied by 137Cs technique in Yatagan basin in Western Turkey, where there exist intensive agricultural activities. This region is subject to serious soil loss problems and yet there is not any erosion data towards soil management and control guidelines. During the soil survey studies, the soil profiles were examined carefully to select the reference points. The soil samples were collected from the slope facets in three different study areas (Kirtas, Peynirli and Kayisalan Hills). Three different models were applied for erosion rate calculations in undisturbed and cultivated sites. The profile distribution model (PDM) was used for undisturbed soils, while proportional model (PM) and simplified mass balance model (SMBM) were used for cultivated soils. The mean annual erosion rates found using PDM in undisturbed soils were 15 t ha(-1) year(-1) at the Peynirli Hill and 27 t ha(-1) year(-1) at the Kirtas Hill. With the PM and SMBM in cultivated soils at Kayişalan, the mean annual erosion rates were obtained to be 65 and 116 t ha(-1) year(-1), respectively. The results of 137Cs technique were compared with the results of the Universal Soil Loss Equation (USLE).

Measurement of erosion in helicon plasma thrusters using the VASIMR® VX-CR device

NASA Astrophysics Data System (ADS)

Del Valle Gamboa, Juan Ignacio; Castro-Nieto, Jose; Squire, Jared; Carter, Mark; Chang-Diaz, Franklin

2015-09-01

The helicon plasma source is one of the principal stages of the high-power VASIMR® electric propulsion system. The VASIMR® VX-CR experiment focuses solely on this stage, exploring the erosion and long-term operation effects of the VASIMR helicon source. We report on the design and operational parameters of the VX-CR experiment, and the development of modeling tools and characterization techniques allowing the study of erosion phenomena in helicon plasma sources in general, and stand-alone helicon plasma thrusters (HPTs) in particular. A thorough understanding of the erosion phenomena within HPTs will enable better predictions of their behavior as well as more accurate estimations of their expected lifetime. We present a simplified model of the plasma-wall interactions within HPTs based on current models of the plasma density distributions in helicon discharges. Results from this modeling tool are used to predict the erosion within the plasma-facing components of the VX-CR device. Experimental techniques to measure actual erosion, including the use of coordinate-measuring machines and microscopy, will be discussed.

End-to-side neurotization with the phrenic nerve in restoring the function of toe extension: an experimental study in a rat model.

PubMed

Jia, Xiaotian; Chen, Chao; Yang, Jianyun; Yu, Cong

2018-06-01

The phrenic nerve being transferred to the posterior division of the lower trunk with end-to-end neurorrhaphy is reported to be effective in restoring the function of digit extension in literature. However, the phrenic nerve is extremely important in respiration. We designed an animal experiment to discover whether the phrenic nerve being transferred to the posterior division of the lower trunk with end-to-side neurotization was feasible and provided the theoretical basis. A sum of 36 Sprague-Dawley rats was randomly assigned to one of two groups. In Group A, the phrenic nerve was transferred to the posterior division of the lower trunk with end-to-side neurotization. In Group B, the posterior division of the lower trunk was directly sutured. The results of behavioral assessment, electrophysiology, histology and nerve fiber count and muscle weight at 12 weeks postoperatively were recorded. In Group A, none of the rats experienced tachypnea. The motion of slight toe extension was observed. The results of electrophysiology, histology and nerve fiber count and muscle weight in Group A were not as well as those of Group B, but gradually improved with time. The phrenic nerve being transferred to the posterior division of lower trunk with end-to-side neurotization can partially restore the function of toe extension in a rat model. Whether the function of digit extension can be restored by the phrenic nerve with end-to-side neurotization in humans still needs more practice in clinic.

Regionally dependent summer heat wave response to increased surface temperature in the US

NASA Astrophysics Data System (ADS)

Lopez, H.; Dong, S.; Kirtman, B. P.; Goni, G. J.; Lee, S. K.; Atlas, R. M.; West, R.

2017-12-01

Climate projections for the 21st Century suggest an increase in the occurrence of heat waves. However, the time it takes for the externally forced signal of climate change to emerge against the background of natural variability (i.e., Time of Emergence, ToE) particularly on the regional scale makes reliable future projection of heat waves challenging. Here, we combine observations and model simulations under present and future climate forcing to assess internal variability versus external forcing in modulating US heat waves. We characterized the most common heat wave patterns over the US by the use of clustering of extreme events by their spatial distribution. For each heat wave cluster, we assess changes in the probability density function (PDF) of summer temperature extremes by modeling the PDF as a stochastically generated skewed (SGS) distribution. The probability of necessary causation for each heat wave cluster was also quantified, allowing to make assessments of heat extreme attribution to anthropogenic climate change. The results suggest that internal variability will dominate heat wave occurrence over the Great Plains with ToE occurring in the 2050s (2070s) and of occurrence of ratio of warm-to-cold extremes of 1.7 (1.7) for the Northern (Southern) Plains. In contrast, external forcing will dominate over the Western (Great Lakes) region with ToE occurring as early as in the 2020s (2030s) and warm-to-cold extremes ratio of 6.4 (10.2), suggesting caution in attributing heat extremes to external forcing due to their regional dependence.

Numerical modelling of flow structures over idealized transverse aeolian dunes of varying geometry

NASA Astrophysics Data System (ADS)

Parsons, Daniel R.; Walker, Ian J.; Wiggs, Giles F. S.

2004-04-01

A Computational Fluid Dynamics (CFD) model (PHOENICS™ 3.5) previously validated for wind tunnel measurements is used to simulate the streamwise and vertical velocity flow fields over idealized transverse dunes of varying height ( h) and stoss slope basal length ( L). The model accurately reproduced patterns of: flow deceleration at the dune toe; stoss flow acceleration; vertical lift in the crest region; lee-side flow separation, re-attachment and reversal; and flow recovery distance. Results indicate that the flow field over transverse dunes is particularly sensitive to changes in dune height, with an increase in height resulting in flow deceleration at the toe, streamwise acceleration and vertical lift at the crest, and an increase in the extent of, and strength of reversed flows within, the lee-side separation cell. In general, the length of the separation zone varied from 3 to 15 h from the crest and increased over taller, steeper dunes. Similarly, the flow recovery distance ranged from 45 to >75 h and was more sensitive to changes in dune height. For the range of dune shapes investigated in this study, the differing effects of height and stoss slope length raise questions regarding the applicability of dune aspect ratio as a parameter for explaining airflow over transverse dunes. Evidence is also provided to support existing research on: streamline curvature and the maintenance of sand transport in the toe region; vertical lift in the crest region and its effect on grainfall delivery; relations between the turbulent shear layer and downward forcing of flow re-attachment; and extended flow recovery distances beyond the separation cell. Field validation is required to test these findings in natural settings. Future applications of the model will characterize turbulence and shear stress fields, examine the effects of more complex isolated dune forms and investigate flow over multiple dunes.

Process-based coastal erosion modeling for Drew Point (North Slope, Alaska)

USGS Publications Warehouse

Ravens, Thomas M.; Jones, Benjamin M.; Zhang, Jinlin; Arp, Christopher D.; Schmutz, Joel A.

2012-01-01

A predictive, coastal erosion/shoreline change model has been developed for a small coastal segment near Drew Point, Beaufort Sea, Alaska. This coastal setting has experienced a dramatic increase in erosion since the early 2000’s. The bluffs at this site are 3-4 m tall and consist of ice-wedge bounded blocks of fine-grained sediments cemented by ice-rich permafrost and capped with a thin organic layer. The bluffs are typically fronted by a narrow (∼ 5  m wide) beach or none at all. During a storm surge, the sea contacts the base of the bluff and a niche is formed through thermal and mechanical erosion. The niche grows both vertically and laterally and eventually undermines the bluff, leading to block failure or collapse. The fallen block is then eroded both thermally and mechanically by waves and currents, which must occur before a new niche forming episode may begin. The erosion model explicitly accounts for and integrates a number of these processes including: (1) storm surge generation resulting from wind and atmospheric forcing, (2) erosional niche growth resulting from wave-induced turbulent heat transfer and sediment transport (using the Kobayashi niche erosion model), and (3) thermal and mechanical erosion of the fallen block. The model was calibrated with historic shoreline change data for one time period (1979-2002), and validated with a later time period (2002-2007).

Cavitation erosion - scale effect and model investigations

NASA Astrophysics Data System (ADS)

Geiger, F.; Rutschmann, P.

2015-12-01

The experimental works presented in here contribute to the clarification of erosive effects of hydrodynamic cavitation. Comprehensive cavitation erosion test series were conducted for transient cloud cavitation in the shear layer of prismatic bodies. The erosion pattern and erosion rates were determined with a mineral based volume loss technique and with a metal based pit count system competitively. The results clarified the underlying scale effects and revealed a strong non-linear material dependency, which indicated significantly different damage processes for both material types. Furthermore, the size and dynamics of the cavitation clouds have been assessed by optical detection. The fluctuations of the cloud sizes showed a maximum value for those cavitation numbers related to maximum erosive aggressiveness. The finding suggests the suitability of a model approach which relates the erosion process to cavitation cloud dynamics. An enhanced experimental setup is projected to further clarify these issues.

CFD study of fluid flow changes with erosion

NASA Astrophysics Data System (ADS)

López, Alejandro; Stickland, Matthew T.; Dempster, William M.

2018-06-01

For the first time, a three dimensional mesh deformation algorithm is used to assess fluid flow changes with erosion. The validation case chosen is the Jet Impingement Test, which was thoroughly analysed in previous works by Hattori et al. (Kenichi Sugiyama and Harada, 2008), Gnanavelu et al. in (Gnanavelu et al., 2009, 2011), Lopez et al. in (Lopez et al., 2015) and Mackenzie et al. in (Mackenzie et al., 2015). Nguyen et al. (2014) showed the formation of a new stagnation area when the wear scar is deep enough by performing a three-dimensional scan of the wear scar after 30 min of jet impingement test. However, in the work developed here, this stagnation area was obtained solely by computational means. The procedure consisted of applying an erosion model in order to obtain a deformed geometry, which, due to the changes in the flow pattern lead to the formation of a new stagnation area. The results as well as the wear scar were compared to the results by Nguyen et al. (2014) showing the same trend. OpenFOAM® was the software chosen for the implementation of the deforming mesh algorithm as well as remeshing of the computational domain after deformation. Different techniques for mesh deformation and approaches to erosion modelling are discussed and a new methodology for erosion calculation including mesh deformation is developed. This new approach is independent of the erosion modelling approach, being applicable to both Eulerian and Lagrangian based equations for erosion calculation. Its different applications such as performance decay in machinery subjected to erosion as well as modelling of natural erosion processes are discussed here.

Pain Experience is Somatotopically Organized and Overlaps with Pain Anticipation in the Human Cerebellum.

PubMed

Michelle Welman, F H S; Smit, Albertine E; Jongen, Joost L M; Tibboel, Dick; van der Geest, Jos N; Holstege, Jan C

2018-02-26

Many fMRI studies have shown activity in the cerebellum after peripheral nociceptive stimulation. We investigated whether the areas in the cerebellum that were activated after nociceptive thumb stimulation were separate from those after nociceptive toe stimulation. In an additional experiment, we investigated the same for the anticipation of a nociceptive stimulation on the thumb or toe. For his purpose, we used fMRI after an electrical stimulation of the thumb and toe in 19 adult healthy volunteers. Following nociceptive stimulation, different areas were activated by stimulation on the thumb (lobule VI ipsilaterally and Crus II mainly contralaterally) and toe (lobules VIII-IX and IV-V bilaterally and lobule VI contralaterally), i.e., were somatotopically organized. Cerebellar areas innervated non-somatotopically by both toe and thumb stimulation were the posterior vermis and Crus I, bilaterally. In the anticipation experiment, similar results were found. However, here, the somatotopically activated areas were relatively small for thumb and negligible for toe stimulation, while the largest area was innervated non-somatotopically and consisted mainly of Crus I and lobule VI bilaterally. These findings indicate that nociceptive stimulation and anticipation of nociceptive stimulation are at least partly processed by the same areas in the cerebellum. This was confirmed by an additional conjunction analysis. Based on our findings, we hypothesize that input that is organized in a somatotopical manner reflects direct input from the spinal cord, while non-somatotopically activated parts of the cerebellum receive their information indirectly through cortical and subcortical connections, possibly involved in processing contextual emotional states, like the expectation of pain.

Gender differences of sagittal knee and ankle biomechanics during stair-to-ground descent transition.

PubMed

Hong, Yoon No Gregory; Shin, Choongsoo S

2015-12-01

Falls on stairs often result in severe injury and occur twice as frequently in women. However, gender differences in kinetics and kinematics during stair descent are unknown. Thus, this study aimed to determine whether gender differences of knee and ankle biomechanics exist in the sagittal plane during the stair-to-ground descending transition. It was hypothesized that 1) women would reveal higher ground-toe-trochanter angle and lower ground-toe length during stair-to-ground descent transition than men; and 2) women would reveal lower peak knee extension moment during stair-to-ground descent transition than men. Fifteen men and fifteen women were recruited and performed a stair descent activity. Kinetic and kinematic data were obtained using a force plate and motion capture system. The women performed the stair descent with a lower peak knee extension moment and a peak knee power at the early weight acceptance phase. The women also revealed a higher ground-toe-trochanter angle and a lower ground-toe length, which indicated a more forward position of the lower extremity relative to the toe contact point at both the initial contact and at the time of peak kinematic and kinetic events. This study found that knee and ankle kinematics and kinetics differed significantly between the genders due to differences in ground-toe-trochanter angle. Women have a different stair descending strategy that reduces the demand of the lower extremity muscle function, but this strategy seems to increase the risk of falls. Copyright © 2015 Elsevier Ltd. All rights reserved.

A simplified measurement of pulse wave velocity is not inferior to standard measurement in young adults and children.

PubMed

Edgell, Heather; Stickland, Michael K; MacLean, Joanna E

2016-06-01

The standard measurement of pulse wave velocity (PWV) is restricted by the need for simultaneous tonometry measurements requiring two technicians and expensive equipment, limiting this technique to well-resourced settings. In this preliminary study, we compared a simplified method of pulse wave detection from the finger and toe to pulse wave detection from the carotid and radial arteries using applanation tonometry in children and young adults. We hypothesized that the simplified method of PWV measurement would strongly correlate with the standard measurement in different age groups and oxygen conditions. Participants included (a) boys and girls aged 8-12 years and (b) men and women aged 18-40 years. Participants rested supine while carotid and radial artery pulse waves were measured using applanation tonometry and finger and toe pulse waves were simultaneously collected using a Finometer Midi and a piezo-electric pulse transducer, respectively. These measurements were repeated under hypoxic conditions. Finger-toe PWV measurements were strongly correlated to carotid-radial PWV in adults (R=0.58; P=0.011), but not in children (R=0.056; P=0.610). Finger-toe PWV was sensitive enough to show increases in PWV with age (P<0.0001) and hypoxia in children (P<0.0001) and adults (P=0.003). These results indicate that the simplified measurement of finger-toe PWV strongly correlates with the standard measurement of carotid-radial PWV in adults, but not in children. However, finger-toe PWV can be used in either population to determine changes with hypoxia.

Role of erosion and isostasy in the Cordillera Blanca uplift: insights from Low-T thermochronology and landscape evolution modeling (northern Peru, Andes)

NASA Astrophysics Data System (ADS)

Margirier, A.; Robert, X.; Braun, J.; Laurence, A.

2017-12-01

The uplift and exhumation of the highest Peruvian peaks seems closely linked to the Cordillera Blanca normal fault that delimits and shape the western flank of the Cordillera Blanca. Two models have been previously proposed to explain the occurrence of extension and the presence of this active normal fault in a compression setting but the Cordillera Blanca normal fault and the uplift and exhumation of the Cordillera Blanca remain enigmatic. Recent studies suggested an increase of exhumation rates during the Quaternary in the Cordillera Blanca and related this increase to a change in climate and erosion process (glacial erosion vs. fluvial erosion). The Cordillera Blanca granite has been significantly eroded since its emplacement (12-5 Ma) indicating a significant mass of rocks removal. Whereas it has been demonstrated recently that the effect of eroding denser rocks can contribute to an increase of uplift rate, the impact of erosion and isostasy on the increase of the Cordillera Blanca uplift rates has never been explored. Based on numerical modeling of landscape evolution we address the role of erosion and isostasy in the uplift and exhumation of the Cordillera Blanca. We performed inversions of the present-day topography, total exhumation and thermochronological data using a landscape evolution model (FastScape). Our results evidence the contribution of erosion and associated flexural rebound to the uplift of the Cordillera Blanca. Our models suggest that the erosion of the Cordillera Blanca dense intrusion since 3 Ma could also explain the Quaternary exhumation rate increase in this area. Finally, our results allow to question the previous models proposed for the formation of the Cordillera Blanca normal fault.

Experimental and Analytical Study of Erosive Burning of Solid Propellants

DTIC Science & Technology

1981-06-01

Identity by block number) Experirnert~iI - d analytical, *bdeling studies of the erosive burning ,..solfd propel l;n!t; w’r(, ,conducted at Atlantic Research...is approved for public ’release IAVV AFR 190-12 (Tb). Distribuiiou is unlitited. A. D . HLOSE Z Tecuhtgal Ina’o ’nation Offo icer - 3. Conduct...roughness. 8. Extend the erosive burning model from flat-plate geometry to axisymmetric flow. 9. Validate the 2- D model of erosive burning by experimental

Mapping soil erosion risk in Serra de Grândola (Portugal)

NASA Astrophysics Data System (ADS)

Neto Paixão, H. M.; Granja Martins, F. M.; Zavala, L. M.; Jordán, A.; Bellinfante, N.

2012-04-01

Geomorphological processes can pose environmental risks to people and economical activities. Information and a better knowledge of the genesis of these processes is important for environmental planning, since it allows to model, quantify and classify risks, what can mitigate the threats. The objective of this research is to assess the soil erosion risk in Serra de Grândola, which is a north-south oriented mountain ridge with an altitude of 383 m, located in southwest of Alentejo (southern Portugal). The study area is 675 km2, including the councils of Grândola, Santiago do Cacém and Sines. The process for mapping of erosive status was based on the guidelines for measuring and mapping the processes of erosion of coastal areas of the Mediterranean proposed by PAP/RAC (1997), developed and later modified by other authors in different areas. This method is based on the application of a geographic information system that integrates different types of spatial information inserted into a digital terrain model and in their derivative models. Erosive status are classified using information from soil erodibility, slope, land use and vegetation cover. The rainfall erosivity map was obtained using the modified Fournier index, calculated from the mean monthly rainfall, as recorded in 30 meteorological stations with influence in the study area. Finally, the soil erosion risk map was designed by ovelaying the erosive status map and the rainfall erosivity map.

Assessing soil erosion using USLE model and MODIS data in the Guangdong, China

NASA Astrophysics Data System (ADS)

Gao, Feng; Wang, Yunpeng; Yang, Jingxue

2017-07-01

In this study, soil erosion in the Guangdong, China during 2012 was quantitatively assessed using Universal Soil Loss Equation (USLE). The parameters of the model were calculated using GIS and MODIS data. The spatial distribution of the average annual soil loss on grid basis was mapped. The estimated average annual soil erosion in Guangdong in 2012 is about 2294.47t/ (km2.a). Four high sensitive area of soil erosion in Guangdong in 2012 was found. The key factors of these four high sensitive areas of soil erosion were significantly contributed to the land cover types, rainfall and Economic development and human activities.

Boreal forest soil erosion and soil-atmosphere carbon exchange

NASA Astrophysics Data System (ADS)

Billings, S. A.; Harden, J. W.; O'Donnell, J.; Sierra, C. A.

2013-12-01

Erosion may become an increasingly important agent of change in boreal systems with climate warming, due to enhanced ice wedge degradation and increases in the frequency and intensity of stand-replacing fires. Ice wedge degradation can induce ground surface subsidence and lateral movement of mineral soil downslope, and fire can result in the loss of O horizons and live roots, with associated increases in wind- and water-promoted erosion until vegetation re-establishment. It is well-established that soil erosion can induce significant atmospheric carbon (C) source and sink terms, with the strength of these terms dependent on the fate of eroded soil organic carbon (SOC) and the extent to which SOC oxidation and production characteristics change with erosion. In spite of the large SOC stocks in the boreal system and the high probability that boreal soil profiles will experience enhanced erosion in the coming decades, no one has estimated the influence of boreal erosion on the atmospheric C budget, a phenomenon that can serve as a positive or negative feedback to climate. We employed an interactive erosion model that permits the user to define 1) profile characteristics, 2) the erosion rate, and 3) the extent to which each soil layer at an eroding site retains its pre-erosion SOC oxidation and production rates (nox and nprod=0, respectively) vs. adopts the oxidation and production rates of previous, non-eroded soil layers (nox and nprod=1, respectively). We parameterized the model using soil profile characteristics observed at a recently burned site in interior Alaska (Hess Creek), defining SOC content and turnover times. We computed the degree to which post-burn erosion of mineral soil generates an atmospheric C sink or source while varying erosion rates and assigning multiple values of nox and nprod between 0 and 1, providing insight into the influence of erosion rate, SOC oxidation, and SOC production on C dynamics in this and similar profiles. Varying nox and nprod did not induce meaningful changes in model estimates of atmospheric C source or sink strength, likely due to the low turnover rate of SOC in this system. However, variation in mineral soil erosion rates induced large shifts in the source and sink strengths for atmospheric C; after 50 y of mineral soil erosion at 5 cm y-1, we observed a maximum C source of 35 kg C m-2 and negligible sink strength. Doubling the erosion rate approximately doubled the source strength. Scaling these estimates to the region requires estimates of the area undergoing mineral soil erosion in forests similar to those modeled. We suggest that erosion is an important but little studied feature of fire-driven boreal systems that will influence atmospheric CO2 budgets.

Soil erosion model predictions using parent material/soil texture-based parameters compared to using site-specific parameters

Treesearch

R. B. Foltz; W. J. Elliot; N. S. Wagenbrenner

2011-01-01

Forested areas disturbed by access roads produce large amounts of sediment. One method to predict erosion and, hence, manage forest roads is the use of physically based soil erosion models. A perceived advantage of a physically based model is that it can be parameterized at one location and applied at another location with similar soil texture or geological parent...

Modeling of Soil Erosion by IntErO model: The Case Study of the Novsicki Potok Watershed, of the Prokletije high mountains of Montenegro

NASA Astrophysics Data System (ADS)

Spalevic, Velibor; Al-Turki, Ali M.; Barovic, Goran; Leandro Naves Silva, Marx; Djurovic, Nevenka; Soares Souza, Walisson; Veloso Gomes Batista, Pedro; Curovic, Milic

2016-04-01

The application of soil conservation programs to combat erosion and sedimentation are significantly contributing to the protection of the natural resources. Watershed management practices include the assessment of Physical-Geographical, Climate, Geological, Pedological characteristics, including the analysis of Land Use of the regions concerned. The policy makers are increasingly looking for the different land uses and climatic scenarios that can be used for valuable projections for watershed management. To increase knowledge about those processes, use of hydrological and soil erosion models is needed and that is allowing quantification of soil redistribution and sediment productions. We focused on soil erosion processes in one of Northern Montenegrin mountain watersheds, the Novsicki Potok Watershed of the Polimlje River Basin, using modeling techniques: the IntErO model for calculation of runoff and soil loss. The model outcomes were validated through measurements of lake sediment deposition at the Potpec hydropower plant dam. Our findings indicate a medium potential of soil erosion risk. With 464 m³ yr-1 of annual sediment yield, corresponding to an area-specific sediment yield of 270 m³km-2 yr-1, the Novsicki Potok drainage basin belongs to the Montenegrin basins with the medium sediment discharge; according to the erosion type, it is surface erosion. The value of the Z coefficient was calculated on 0.403, what indicates that the river basin belongs to 3rd destruction category (of five). Our results suggest that the calculated peak discharge from the river basin was 82 m3s-1 for the incidence of 100 years. According to our analysis there is a possibility for large flood waves to appear in the studied river basin. With this research we, to some extent, improved the knowledge on the status of sediment yield and runoff of the river basins of Montenegro, where the map of Soil erosion is still not prepared. The IntErO model we used in this study is relatively novel concept and is highly recommended for soil erosion modelling in other river basins similar to the studied watershed, because of its simple identification of critical areas affected by the soil loss caused by soil erosion.

Temporal and spatial variations of rainfall erosivity in Southern Taiwan

NASA Astrophysics Data System (ADS)

Lee, Ming-Hsi; Lin, Huan-Hsuan; Chu, Chun-Kuang

2014-05-01

Soil erosion models are essential in developing effective soil and water resource conservation strategies. Soil erosion is generally evaluated using the Universal Soil Loss Equation (USLE) with an appropriate regional scale description. Among factors in the USLE model, the rainfall erosivity index (R) provides one of the clearest indications of the effects of climate change. Accurate estimation of rainfall erosivity requires continuous rainfall data; however, such data rarely demonstrate good spatial and temporal coverage. The data set consisted of 9240 storm events for the period 1993 to 2011, monitored by 27 rainfall stations of the Central Weather Bureau (CWB) in southern Taiwan, was used to analyze the temporal-spatial variations of rainfall erosivity. The spatial distribution map was plotted based on rainfall erosivity by the Kriging interpolation method. Results indicated that rainfall erosivity is mainly concentrated in rainy season from June to November typically contributed 90% of the yearly R factor. The temporal variations of monthly rainfall erosivity during June to November and annual rainfall erosivity have increasing trend from 1993 to 2011. There is an increasing trend from southwest to northeast in spatial distribution of rainfall erosivity in southern Taiwan. The results further indicated that there is a higher relationship between elevation and rainfall erosivity. The method developed in this study may also be useful for sediment disasters on Climate Change.

5. VIEW SHOWING DOWNSTREAM FACE AND TOE OF DAM, LOOKING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. VIEW SHOWING DOWNSTREAM FACE AND TOE OF DAM, LOOKING SOUTHWEST - High Mountain Dams in Upalco Unit, Kidney Lake Dam, Ashley National Forest, 4.7 miles North of Miners Gulch Campground, Mountain Home, Duchesne County, UT

6. VIEW SHOWING DOWNSTREAM FACE AND TOE OF DAM, LOOKING ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

6. VIEW SHOWING DOWNSTREAM FACE AND TOE OF DAM, LOOKING SOUTHWEST - High Mountain Dams in Upalco Unit, Kidney Lake Dam, Ashley National Forest, 4.7 miles North of Miners Gulch Campground, Mountain Home, Duchesne County, UT

5. DETAIL VIEW OF TOE SPILLWAY SECTION OF LOWWATER DAM, ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

5. DETAIL VIEW OF TOE SPILLWAY SECTION OF LOW-WATER DAM, LOOKING NORTHWEST (UPSTREAM). ST. LOUIS WATER DEPARTMENT INTAKE IN BACKGROUND - Upper Mississippi River 9-Foot Channel Project, Lock & Dam 27, Granite City, Madison County, IL

[Atheroembolism renal disease: diagnosis and etiologic factors].

PubMed

Granata, A; Insalaco, M; Di Pietro, F; Di Rosa, S; Romano, G; Scuderi, R

2012-07-01

Atheromatous renal disease is the major cause of renal insufficiency in the elderly, and cholesterol embolism is a manifestation of this disease. Cholesterol embolism occurs in patients suffering from diffuse erosive atherosclerosis, usually after triggering causes, such as aortic surgery, arterial invasive procedures (angiography, left heart catheterization and coronary angioplasty) and anticoagulant or thrombolytic therapy. It is characterized by occlusion of small arteries with cholesterol emboli deriving from eroded atheromatous plaques of the aorta or large feeder arteries. The proximity of the kidneys to the abdominal aorta and the large renal blood supply make the kidney a frequent target organ for cholesterol atheroembolism. The exact incidence of atheroembolic renal disease (AERD) is not known. The reported incidence AERD varied in the literature because of the differences in study design and the different criteria used for making the diagnosis. Retrospective data derived from autopsy or biopsy studies may exaggerate the frequency by including many subclinical cases. Clinical observations that are based on a short duration of follow-up after an invasive vascular procedure and the infrequency of the confirmatory renal biopsies can lead to an underestimation of the true incidence of AERD. The initial signs and symptoms in patients diagnosed with cholesterol embolism were blue toes syndrome, livedo reticularis, gangrene, leg, toe or foot pain, abdominal pain and flank or back pain, gross haematuria, accelerated hypertension and renal failure. Cholesterol embolism may also be associated with fever, increased erythrocyte sedimentation rate and eosinophilia. Thus, in the cases of spontaneous cholesterol embolism, differential diagnosis includes, polyarteritis nodosa, allergic vasculitis and subacute bacterial endocarditis. Skin and renal biopsy specimens are the best sample for histologic diagnosis. There is, at present, no pharmacological treatments shown to be effective in altering the course of the disease. Management is limited to supportive therapy and avoidance of anticoagulation; aortic procedures should be postponed.

Quantification of Dune Response over the Course of a 6-Day Nor'Easter, Outer Banks, NC

NASA Astrophysics Data System (ADS)

Brodie, K. L.; Spore, N.; Swann, C.

2014-12-01

The amount and type of foredune morphologic change during a storm event primarily scales with the level of inundation during that event. Specifically, external hydrodynamic forcing (total water level) can be compared with antecedent beach and foredune morphology to predict an impact regime that relates to the type of expected morphologic evolution of the system. For example, when total water levels are above the dune toe, but below the dune crest, the impact regime is classified as "collision" and the expected morphology response is slumping or scarping of the dune face. While the amount of dune retreat scales largely with the duration of wave attack to the dune face, characteristics of the dune other than its crest or toe elevation may also enhance or impede rates of morphologic change. The aftermath of Hurricane Sandy provided a unique opportunity to observe alongshore variations in dune response to a 6-day Nor'Easter (Hs >4 m in 6 m depth), as a variety of dunes were constructed (or not) by individual home owners in preparation for the winter storm season. Daily terrestrial lidar scans were conducted along 20 km of coastline in Duck, NC using Coastal Lidar And Radar Imaging System (CLARIS) during the first dune collision event following Sandy. Foredunes were grouped by their pre-storm form (e.g. vegetated, pushed, scarped, etc) using automated feature extraction tools based on surface curvature and slope, and daily rates of morphologic volume change were calculated. The highest dune retreat rates were focused along a 1.5 km region where cross-shore erosion of recently pushed, un-vegetated dunes reached 2 m/day. Variations in dune response were analyzed in relation to their pre-storm morphology, with care taken to normalize for alongshore variations in hydrodynamic forcing. Ongoing research is focused on identifying specific metrics that can be easily extracted from topographic DEMs to aid in dune retreat predictions.

Anatomic relationship of the proximal nail matrix to the extensor hallucis longus tendon insertion.

PubMed

Palomo López, P; Becerro de Bengoa Vallejo, R; López López, D; Prados Frutos, J C; Alfonso Murillo González, J; Losa Iglesias, M E

2015-10-01

The purpose of this study was to delineate the relationship of the terminal extensor hallucis longus tendon insertion to the proximal limit of the nail matrix of the great toe. Fifty fresh-frozen human cadaver great toes with no evidence of trauma (average age, 62.5 years; 29 males and 21 females) were used for this study. Under 25X magnification, the proximal limit of the nail matrix and the terminal bony insertion of the extensor hallucis longus tendons were identified. The distance from the terminal tendon insertion to the nail matrix was ascertained using precision calipers, an optical microscope, and autocad(®) software for windows. Twenty-five great toes were placed in a neutral formalin solution and further analysed by histological longitudinal-sections. The specimens were stained with haematoxylin and eosin and examined microscopically to determine the presence of the extensor hallucis longus tendon along the dorsal aspect of the distal phalanx of each great toe. The main result we found in great toes was that the extensor tendon is between the matrix and the phalanx and extends dorsally to the distal aspect of the distal phalanx in all, 100%, specimens. The nail matrix of the great toe is not attached to the periosteum of the dorsal aspect of the base of the distal phalanx as is the case for fingers, because the extensor hallucis tendon is plantar or directly underneath the nail matrix and the tendon is dorsal to the bone. We have found that the extensor tendon is between the matrix and the phalanx and extends dorsally to the distal aspect of the distal phalanx. The nail matrix of the great toe is not attached to the periosteum of the dorsal aspect of the base of distal phalanx as is the case in fingers, because the extensor hallucis tendon is plantar or directly underneath the nail matrix and the tendon is dorsal to the bone. Our anatomic study demonstrates that the proximal limit of the matrix and nail bed of the human great toe are dorsal and overlapping the terminal extensor hallucis longus tendon until its distal bony insertion in all specimens. © 2015 European Academy of Dermatology and Venereology.

Characterizing low-Z erosion and deposition in the DIII-D divertor using aluminum

DOE PAGES

Chrobak, Chris P.; Doerner, R. P.; Stangeby, Peter C.; ...

2017-01-28

Here, we present measurements and modeling of aluminum erosion and redeposition experiments in separate helium and deuterium low power, low density L-mode plasmas at the outer divertor strike point of DIII-D to provide a low-Z material benchmark dataset for tokamak erosion-deposition modeling codes. Coatings of Al ~100nm thick were applied to ideal (smooth) and realistic (rough) surfaces and exposed to repeat plasma discharges using the DiMES probe. Redeposition and re-erosion in all cases was primarily in the downstream toroidal field direction, evident from both in-situ spectroscopic and post-mortem non spectroscopic measurements. The gross Al erosion yield estimated from both Hemore » and D plasma exposures was ~40-70% of the expected erosion yield based on theoretical physical sputtering yields. However, the multi-step redeposition and re-erosion process, and hence the measured net erosion yield and material migration, was found to be influenced by the surface roughness and/or porosity. On rough surfaces, the fraction of the eroded Al coating found redeposited outside the original coating area was 25x higher than on smooth surfaces. The amount of Al found redeposited on the rough substrate was in fact proportional to the net eroded Al, suggesting an accumulation of deposited Al in surface pores and other areas shadowed from re-erosion. In order to determine the fraction and distribution of eroded Al returning to the surface, a simple model for erosion and redeposition was developed and fitted to the measurements. The model presented here reproduces many of the observed results in these experiments by using theoretically calculated sputtering yields, calculating surface composition changes and erosion rates in time, assuming a spatial distribution function for redepositing atoms, and accounting for deposit trapping in pores. The results of the model fits reveal that total redeposition fraction increases with higher plasma temperature (~30% for 15-18eV plasmas, and ~45% for 25-30eV plasmas), and that 50% of the atoms redepositing on rough surfaces accumulated in shadowed areas.« less

The Distribution and Magnitude of Glacial Erosion on 103-year Timescales at Engabreen, Norway

NASA Astrophysics Data System (ADS)

Rand, C.; Goehring, B. M.

2017-12-01

We derive the magnitudes of glacial erosion integrated over 103-year timescales across a transect transverse to the direction of ice flow at Engabreen, Norway. Understanding the distribution of glacial erosion is important for several reasons, including sediment budgeting to fjord environments, development of robust landscape evolution models, and if a better understanding between erosion and ice-bed interface properties (e.g., sliding rate, basal water pressure) can be developed, we can use records of glacial erosion to infer glaciological properties that can ultimately benefit models of past and future glaciers. With few exceptions, measurements of glacial erosion are limited to the historical past and even then are rare owing to the difficulty of accessing the glacier bed. One method proven useful in estimating glacial erosion on 103-year timescales is to measure the remaining concentrations of cosmogenic nuclides that accumulate in exposed bedrock during periods of retracted glacier extent and are removed by glacial erosion and radioactive decay during ice cover. Here we will present measurements of 14C and 10Be measured in proglacial bedrock from Engabreen. Our transects are ca. 600 and 400 meters in front of the modern ice front, and based on historical imagery, was ice covered until the recent past. Initial 10Be results show an increase in concentrations of nearly an order of magnitude from the samples near the center of the glacial trough to those on the lateral margin, consistent with conceptual models of glacial erosion parameterized in terms of sliding velocity. Naïve exposure ages that assume no subglacial erosion range from 0.22 - 9.04 ka. More importantly, we can estimate erosion depths by assuming zero erosion of the highest concentration sample along the two transects and calculate the amount of material removed to yield the lower concentrations elsewhere along the two transects. Results indicate minimum erosion depths of 1-183 cm for most ice proximal transect and 7-56 cm for the more distal one.

Behavior of farmers in regard to erosion by water as reflected by their farming practices.

PubMed

Auerswald, Karl; Fischer, Franziska K; Kistler, Michael; Treisch, Melanie; Maier, Harald; Brandhuber, Robert

2018-02-01

The interplay between natural site conditions and farming raises erosion by water above geological background levels. We examined the hypothesis that farmers take erosion into account in their farming decisions and switch to farming practices with lower erosion risk the higher the site-specific hazard becomes. Erosion since the last tillage was observed from aerial orthorectified photographs for 8100 fields belonging to 1879 farmers distributed across Bavaria (South Germany) and it was modeled by the Universal Soil Loss Equation using highly detailed input data (e.g., digital terrain model with 5×5m 2 resolution, rain data with 1×1km 2 and 5min resolution, crop and cropping method from annual field-specific data from incentive schemes). Observed and predicted soil loss correlated closely, demonstrating the accuracy of this method. The close correlation also indicted that the farmers could easily observe the degree of recent erosion on their fields, even without modelling. Farmers clearly did not consider erosion in their decisions. When natural risk increased, e.g. due to steeper slopes, they neither grew crops with lower erosion potential, nor reduced field size, nor used contouring. In addition, they did not compensate for the cultivation of crops with higher erosion potential by using conservation techniques like mulch tillage or contouring, or by reducing field size. Only subsidized measures, like mulch tillage or organic farming, were applied but only at the absolute minimum that was necessary to obtain subsidies. However, this did not achieve the reduction in erosion that would be possible if these measures had been fully applied. We conclude that subsidies may be an appropriate method of reducing erosion but the present weak supervision, which assumes that farmers themselves will take erosion into account and that subsidies are only needed to compensate for any disadvantages caused by erosion-reducing measures, is clearly not justified. Copyright © 2017 Elsevier B.V. All rights reserved.

ERMiT: Estimating Post-Fire Erosion in Probabilistic Terms

NASA Astrophysics Data System (ADS)

Pierson, F. B.; Robichaud, P. R.; Elliot, W. J.; Hall, D. E.; Moffet, C. A.

2006-12-01

Mitigating the impact of post-wildfire runoff and erosion on life, property, and natural resources have cost the United States government tens of millions of dollars over the past decade. The decision of where, when, and how to apply the most effective mitigation treatments requires land managers to assess the risk of damaging runoff and erosion events occurring after a fire. The Erosion Risk Management Tool (ERMiT) is a web-based application that estimates erosion in probabilistic terms on burned and recovering forest, range, and chaparral lands. Unlike most erosion prediction models, ERMiT does not provide `average annual erosion rates;' rather, it provides a distribution of erosion rates with the likelihood of their occurrence. ERMiT combines rain event variability with spatial and temporal variabilities of hillslope burn severity, soil properties, and ground cover to estimate Water Erosion Prediction Project (WEPP) model input parameter values. Based on 20 to 40 individual WEPP runs, ERMiT produces a distribution of rain event erosion rates with a probability of occurrence for each of five post-fire years. Over the 5 years of modeled recovery, the occurrence probability of the less erodible soil parameters is increased and the occurrence probability of the more erodible soil parameters is decreased. In addition, the occurrence probabilities and the four spatial arrangements of burn severity (arrangements of overland flow elements (OFE's)), are shifted toward lower burn severity with each year of recovery. These yearly adjustments are based on field measurements made through post-fire recovery periods. ERMiT also provides rain event erosion rate distributions for hillslopes that have been treated with seeding, straw mulch, straw wattles and contour-felled log erosion barriers. Such output can help managers make erosion mitigation treatment decisions based on the probability of high sediment yields occurring, the value of resources at risk for damage, cost, and other management considerations.

Modeling sediment transport after ditch network maintenance of a forested peatland

NASA Astrophysics Data System (ADS)

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

2016-11-01

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

A spatially distributed model for the dynamic prediction of sediment erosion and transport in mountainous forested watersheds

NASA Astrophysics Data System (ADS)

Doten, Colleen O.; Bowling, Laura C.; Lanini, Jordan S.; Maurer, Edwin P.; Lettenmaier, Dennis P.

2006-04-01

Erosion and sediment transport in a temperate forested watershed are predicted with a new sediment model that represents the main sources of sediment generation in forested environments (mass wasting, hillslope erosion, and road surface erosion) within the distributed hydrology-soil-vegetation model (DHSVM) environment. The model produces slope failures on the basis of a factor-of-safety analysis with the infinite slope model through use of stochastically generated soil and vegetation parameters. Failed material is routed downslope with a rule-based scheme that determines sediment delivery to streams. Sediment from hillslopes and road surfaces is also transported to the channel network. A simple channel routing scheme is implemented to predict basin sediment yield. We demonstrate through an initial application of this model to the Rainy Creek catchment, a tributary of the Wenatchee River, which drains the east slopes of the Cascade Mountains, that the model produces plausible sediment yield and ratios of landsliding and surface erosion when compared to published rates for similar catchments in the Pacific Northwest. A road removal scenario and a basin-wide fire scenario are both evaluated with the model.

Modeling soil erosion and transport on forest landscape

Treesearch

Ge Sun; Steven G McNulty

1998-01-01

Century-long studies on the impacts of forest management in North America suggest sediment can cause major reduction on stream water quality. Soil erosion patterns in forest watersheds are patchy and heterogeneous. Therefore, patterns of soil erosion are difficult to model and predict. The objective of this study is to develop a user friendly management tool for land...

Modeling climate change effects on runoff and soil erosion in southeastern Arizona rangelands and implications for mitigation with rangeland conservation practices

USDA-ARS?s Scientific Manuscript database

Climate change is expected to impact runoff and soil erosion on rangelands in the southwestern United States. This study was done to evaluate the potential impacts of precipitation changes on soil erosion and surface runoff in southeastern Arizona using seven GCM models with three emission scenarios...

Geospatial application of the Water Erosion Prediction Project (WEPP) Model

Treesearch

D. C. Flanagan; J. R. Frankenberger; T. A. Cochrane; C. S. Renschler; W. J. Elliot

2011-01-01

The Water Erosion Prediction Project (WEPP) model is a process-based technology for prediction of soil erosion by water at hillslope profile, field, and small watershed scales. In particular, WEPP utilizes observed or generated daily climate inputs to drive the surface hydrology processes (infiltration, runoff, ET) component, which subsequently impacts the rest of the...

Adapting the Water Erosion Prediction Project (WEPP) model for forest applications

Treesearch

Shuhui Dun; Joan Q. Wu; William J. Elliot; Peter R. Robichaud; Dennis C. Flanagan; James R. Frankenberger; Robert E. Brown; Arthur C. Xu

2009-01-01

There has been an increasing public concern over forest stream pollution by excessive sedimentation due to natural or human disturbances. Adequate erosion simulation tools are needed for sound management of forest resources. The Water Erosion Prediction Project (WEPP) watershed model has proved useful in forest applications where Hortonian flow is the major form of...

Advances in understanding of high- Z material erosion and re-deposition in low- Z wall environment in DIII-D

DOE PAGES

Ding, R.; Rudakov, D. L.; Stangeby, P. C.; ...

2017-03-24

Dedicated DIII-D experiments coupled with modeling reveal that the net erosion rate of high-Z materials, i.e. Mo and W, is strongly affected by carbon concentration in the plasma and the magnetic pre-sheath properties. We have investigated different methods such as electrical biasing and local gas injection to control high-Z material erosion. The net erosion rate of high-Z materials is significantly reduced due to the high local re-deposition ratio. The ERO modeling shows that the local re-deposition ratio is mainly controlled by the electric field and plasma density within the magnetic pre-sheath. The net erosion can be significantly suppressed by reducingmore » the sheath potential drop. A high carbon impurity concentration in the background plasma is also found to reduce the net erosion rate of high-Z materials. Both DIII-D experiments and modeling show that local 13CH 4 injection can create a carbon coating on the metal surface. The profile of 13C deposition provides quantitative information on radial transport due to E × B drift and the cross-field diffusion. The deuterium gas injection upstream of the W sample can reduce W net erosion rate by plasma perturbation. The inter-ELM W erosion we measured in H-mode plasmas, rates at different radial locations are well reproduced by ERO modeling taking into account charge-state-resolved carbon ion flux in the background plasma calculated using the OEDGE code.« less

49 CFR 214.115 - Foot protection.

Code of Federal Regulations, 2014 CFR

2014-10-01

... shock or burns, or other hazardous condition. (b) Safety-toe footwear for railroad bridge workers shall conform to the national consensus standards for safety-toe footwear (American National Standards Institute, American National Standard Z41-1991, Standard for Personal Protection-Protective Footwear). This...

49 CFR 214.115 - Foot protection.

Code of Federal Regulations, 2012 CFR

2012-10-01

... shock or burns, or other hazardous condition. (b) Safety-toe footwear for railroad bridge workers shall conform to the national consensus standards for safety-toe footwear (American National Standards Institute, American National Standard Z41-1991, Standard for Personal Protection-Protective Footwear). This...

49 CFR 214.115 - Foot protection.

Code of Federal Regulations, 2013 CFR

2013-10-01

... shock or burns, or other hazardous condition. (b) Safety-toe footwear for railroad bridge workers shall conform to the national consensus standards for safety-toe footwear (American National Standards Institute, American National Standard Z41-1991, Standard for Personal Protection-Protective Footwear). This...

49 CFR 214.115 - Foot protection.

Code of Federal Regulations, 2011 CFR

2011-10-01

... shock or burns, or other hazardous condition. (b) Safety-toe footwear for railroad bridge workers shall conform to the national consensus standards for safety-toe footwear (American National Standards Institute, American National Standard Z41-1991, Standard for Personal Protection-Protective Footwear). This...

Bunion removal - series (image)

MedlinePlus

... causes the joint to thicken and enlarge. This causes the bones of the big toe to angle in toward and over the ... pain-free (general anesthesia) and rarely requires a hospital ... the bones of the big toe into the foot. The deformed joint and ...

[Breast cancer metastasis in distal phalanx of the big toe. Case report].

PubMed

Carlesimo, B; Tempesta, M; Fioramonti, P; Bistoni, G; Ruggiero, M; Marchetti, F

2009-01-01

Breast cancer represents the most prevalent malignancies in women and bone is the first site of metastasis in 26-50% of cases. Usually metastasis involve limbs in 16%. We present a rare case of 47-year-old woman, who underwent to monolateral mastectomy for lobular cancer. After 8 years from surgery, she presented pain, swelling and functional limitations, gradually increasing, to the left big toe. X-rays and MRI showed a lucent area of bone destruction on the shaft of the distal phalanx of the left big toe. Surgical biopsy on the excised bone assessed for breast cancer metastasis.

Free toe pulp transfer for digital reconstruction after high-pressure injection injury.

PubMed

Chan, B K; Tham, S K; Leung, M

1999-10-01

We report two cases of high-pressure injection injuries to the fingertip in which free toe pulp flaps were used to resurface the palmar surface of the finger following extensive wound debridement. There was good return of sensibility and, because of the high durability of the donor skin, both patients regained good functional use of the injured digits and returned to heavy manual work. There was minimal associated morbidity of the donor sites. The free toe pulp flap represents an excellent alternative for resurfacing the digit with a large residual skin defect after high-pressure injection injury.

Distribution and depth of bottom-simulating reflectors in the Nankai subduction margin

NASA Astrophysics Data System (ADS)

Ohde, Akihiro; Otsuka, Hironori; Kioka, Arata; Ashi, Juichiro

2018-04-01

Surface heat flow has been observed to be highly variable in the Nankai subduction margin. This study presents an investigation of local anomalies in surface heat flows on the undulating seafloor in the Nankai subduction margin. We estimate the heat flows from bottom-simulating reflectors (BSRs) marking the lower boundaries of the methane hydrate stability zone and evaluate topographic effects on heat flow via two-dimensional thermal modeling. BSRs have been used to estimate heat flows based on the known stability characteristics of methane hydrates under low-temperature and high-pressure conditions. First, we generate an extensive map of the distribution and subseafloor depths of the BSRs in the Nankai subduction margin. We confirm that BSRs exist at the toe of the accretionary prism and the trough floor of the offshore Tokai region, where BSRs had previously been thought to be absent. Second, we calculate the BSR-derived heat flow and evaluate the associated errors. We conclude that the total uncertainty of the BSR-derived heat flow should be within 25%, considering allowable ranges in the P-wave velocity, which influences the time-to-depth conversion of the BSR position in seismic images, the resultant geothermal gradient, and thermal resistance. Finally, we model a two-dimensional thermal structure by comparing the temperatures at the observed BSR depths with the calculated temperatures at the same depths. The thermal modeling reveals that most local variations in BSR depth over the undulating seafloor can be explained by topographic effects. Those areas that cannot be explained by topographic effects can be mainly attributed to advective fluid flow, regional rapid sedimentation, or erosion. Our spatial distribution of heat flow data provides indispensable basic data for numerical studies of subduction zone modeling to evaluate margin parallel age dependencies of subducting plates.[Figure not available: see fulltext.

A prototype wireless inertial-sensing device for measuring toe clearance.

PubMed

Lai, Daniel T H; Charry, E; Begg, R; Palaniswami, M

2008-01-01

Tripping and slipping are serious health concerns for the elderly because they result in life threatening injuries i.e., fractures and high medical costs. Our recent work in detection of tripping gait patterns has demonstrated that minimum toe clearance (MTC) is a sensitive falls risk predictor. MTC measurement has previously been done in gait laboratories and on treadmills which potentially imposes controlled walking conditions. In this paper, we describe a prototype design of a wireless device for monitoring vertical toe clearance. The sensors consists of a tri-axis accelerometer and dual-axis gyroscope connected to Crossbow sensor motes for wireless data transmission. Sensor data are transmitted to a laptop and displayed on a Matlab graphic user interface (GUI). We have performed zero base and treadmill experiments to investigate sensor performance to environmental variations and compared the calculated toe clearance against measurements made by an Optotrak motion system. It was found that device outputs were approximately independent of small ambient temperature variations, had a reliable range of 20m indoors and 50m outdoors and a maximum transmission rate of 20 packets/s. Toe clearance measurements were found to follow the Optotrak measurement trend but could be improved further by dealing with double integration errors and improving data transmission rates.

Prediction of wound healing after minor amputations of the diabetic foot.

PubMed

Caruana, Luana; Formosa, Cynthia; Cassar, Kevin

2015-08-01

To identify any significant differences in physiological test results between healing and non healing amputation sites. A single center prospective non-experimental study design was conducted on fifty subjects living with type 2 diabetes and requiring a forefoot or toe amputation. Subjects underwent non-invasive physiological testing preoperatively. These included assessment of pedal pulses, preoperative arterial spectral waveforms at the ankle, absolute toe pressures, toe-brachial pressure index and ankle-brachial pressure index. After 6 weeks, patients were examined to assess whether the amputation site was completely healed, was healing, had developed complications, or did not heal. There was no significant difference in ABPI between the healed/healing and the non-healing groups. Mean TBI (p=0.031) and toe pressure readings (p=0.014) were significantly higher in the healed/healing group compared to the non healing group. A significant difference was also found in ankle spectral waveforms between the two groups (p=0.028). TBIs, toe pressures and spectral waveforms at the ankle are better predictors of likelihood of healing and non-healing after minor amputation than ABPIs. ABPI alone is a poor indicator of the likelihood of healing of minor amputations and should not be relied on to determine need for revascularization procedures before minor amputation. Copyright © 2015 Elsevier Inc. All rights reserved.

Finnish bioenergy research

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

Malinen, H.

1993-12-31

Finland is one of the leading countries in the use of biofuels. The share of wood derived fuels of the total primary energy requirement was about 14% (ca. 4 million toe) and peat about 5% (1.4 million toe). The possibilities for increasing the use of biofuels in Finland are significant. There is theoretically about 10 million m{sup 3}/a (about 2 million toe/a) of harvestable wood. Areas suitable for fuel peat production (0.5 million ha) could produce ca. 420 million toe of peat. At present rates of use, the peat reserves are adequate for centuries. During the next few years 0.5--1more » million hectares of fields withdrawn from farming could be used for biofuel production. The production potential of this field area is estimated to be about 0.2--0.5 million toe. In addition, the use of wastes in energy production could be increased. The aim of the new Bioenergy Research Programme is to increase the use of economically profitable and environmentally sound bioenergy by improving the competitiveness of present peat and wood fuels. New economically competitive biofuels, new equipment and methods for production, handling and use of biofuels will also be developed. The main research areas are production of wood fuels, peat production, use of bioenergy and conversion of biomass.« less

Alarm toe switch

DOEpatents

Ganyard, Floyd P.

1982-01-01

An alarm toe switch inserted within a shoe for energizing an alarm circuit n a covert manner includes an insole mounting pad into which a miniature reed switch is fixedly molded. An elongated slot perpendicular to the reed switch is formed in the bottom surface of the mounting pad. A permanent cylindrical magnet positioned in the forward portion of the slot with a diameter greater than the pad thickness causes a bump above the pad. A foam rubber block is also positioned in the slot rearwardly of the magnet and holds the magnet in normal inoperative relation. A non-magnetic support plate covers the slot and holds the magnet and foam rubber in the slot. The plate minimizes bending and frictional forces to improve movement of the magnet for reliable switch activation. The bump occupies the knuckle space beneath the big toe. When the big toe is scrunched rearwardly the magnet is moved within the slot relative to the reed switch, thus magnetically activating the switch. When toe pressure is released the foam rubber block forces the magnet back into normal inoperative position to deactivate the reed switch. The reed switch is hermetically sealed with the magnet acting through the wall so the switch assembly S is capable of reliable operation even in wet and corrosive environments.

Evaluating the new soil erosion map of Hungary

NASA Astrophysics Data System (ADS)

Waltner, István; Centeri, Csaba; Takács, Katalin; Pirkó, Béla; Koós, Sándor; László, Péter; Pásztor, László

2017-04-01

With growing concerns on the effects of climate change and land use practices on our soil resources, soil erosion by water is becoming a significant issue internationally. Since the 1964 publication of the first soil erosion map of Hungary, there have been several attempts to provide a countrywide assessment of erosion susceptibility. However, there has been no up-to-date map produced in the last decade. In 2016, a new, 1:100 000 scale soil erosion map was published, based on available soil, elevation, land use and meteorological data for the extremely wet year of 2010. The map utilized combined outputs for two spatially explicit methods: the widely used empirical Universal Soil Loss Equation (USLE) and the process-based Pan-European Soil Erosion Risk Assessment (PESERA) models. The present study aims to provide a detailed analysis of the model results. In lieu of available national monitoring data, information from other sources were used. The Soil Degradation Subsystem (TDR) of the National Environmental Information System (OKIR) is a digital database based on a soil survey and farm dairy data collected from representative farms in Hungary. During the survey all kind of degradation forms - including soil erosion - were considered. Agricultural and demographic data was obtained from the Hungarian Central Statistical Office (KSH). Data from an interview-based survey was also used in an attempt to assess public awareness of soil erosion risks. Point-based evaluation of the model results was complemented with cross-regional assessment of soil erosion estimates. This, combined with available demographic information provides us with an opportunity to address soil erosion on a community level, with the identification of regions with the highest risk of being affected by soil erosion.

Riparian erosion vulnerability model based on environmental features.

PubMed

Botero-Acosta, Alejandra; Chu, Maria L; Guzman, Jorge A; Starks, Patrick J; Moriasi, Daniel N

2017-12-01

Riparian erosion is one of the major causes of sediment and contaminant load to streams, degradation of riparian wildlife habitats, and land loss hazards. Land and soil management practices are implemented as conservation and restoration measures to mitigate the environmental problems brought about by riparian erosion. This, however, requires the identification of vulnerable areas to soil erosion. Because of the complex interactions between the different mechanisms that govern soil erosion and the inherent uncertainties involved in quantifying these processes, assessing erosion vulnerability at the watershed scale is challenging. The main objective of this study was to develop a methodology to identify areas along the riparian zone that are susceptible to erosion. The methodology was developed by integrating the physically-based watershed model MIKE-SHE, to simulate water movement, and a habitat suitability model, MaxEnt, to quantify the probability of presences of elevation changes (i.e., erosion) across the watershed. The presences of elevation changes were estimated based on two LiDAR-based elevation datasets taken in 2009 and 2012. The changes in elevation were grouped into four categories: low (0.5 - 0.7 m), medium (0.7 - 1.0 m), high (1.0 - 1.7 m) and very high (1.7 - 5.9 m), considering each category as a studied "species". The categories' locations were then used as "species location" map in MaxEnt. The environmental features used as constraints to the presence of erosion were land cover, soil, stream power index, overland flow, lateral inflow, and discharge. The modeling framework was evaluated in the Fort Cobb Reservoir Experimental watershed in southcentral Oklahoma. Results showed that the most vulnerable areas for erosion were located at the upper riparian zones of the Cobb and Lake sub-watersheds. The main waterways of these sub-watersheds were also found to be prone to streambank erosion. Approximatively 80% of the riparian zone (streambank included) has up to 30% probability to experience erosion greater than 1.0 m. By being able to identify the most vulnerable areas for stream and riparian sediment mobilization, conservation and management practices can be focused on areas needing the most attention and resources. Copyright © 2017 Elsevier Ltd. All rights reserved.