Analysis of rainfall-induced slope instability using a field of local factor of safety

USGS Publications Warehouse

Lu, Ning; Şener-Kaya, Başak; Wayllace, Alexandra; Godt, Jonathan W.

2012-01-01

Slope-stability analyses are mostly conducted by identifying or assuming a potential failure surface and assessing the factor of safety (FS) of that surface. This approach of assigning a single FS to a potentially unstable slope provides little insight on where the failure initiates or the ultimate geometry and location of a landslide rupture surface. We describe a method to quantify a scalar field of FS based on the concept of the Coulomb stress and the shift in the state of stress toward failure that results from rainfall infiltration. The FS at each point within a hillslope is called the local factor of safety (LFS) and is defined as the ratio of the Coulomb stress at the current state of stress to the Coulomb stress of the potential failure state under the Mohr-Coulomb criterion. Comparative assessment with limit-equilibrium and hybrid finite element limit-equilibrium methods show that the proposed LFS is consistent with these approaches and yields additional insight into the geometry and location of the potential failure surface and how instability may initiate and evolve with changes in pore water conditions. Quantitative assessments applying the new LFS field method to slopes under infiltration conditions demonstrate that the LFS has the potential to overcome several major limitations in the classical FS methodologies such as the shape of the failure surface and the inherent underestimation of slope instability. Comparison with infinite-slope methods, including a recent extension to variably saturated conditions, shows further enhancement in assessing shallow landslide occurrence using the LFS methodology. Although we use only a linear elastic solution for the state of stress with no post-failure analysis that require more sophisticated elastoplastic or other theories, the LFS provides a new means to quantify the potential instability zones in hillslopes under variably saturated conditions using stress-field based methods.

Comparative evaluation of SUV, tumor-to-blood standard uptake ratio (SUR), and dual time point measurements for assessment of the metabolic uptake rate in FDG PET.

PubMed

Hofheinz, Frank; Hoff, Jörg van den; Steffen, Ingo G; Lougovski, Alexandr; Ego, Kilian; Amthauer, Holger; Apostolova, Ivayla

2016-12-01

We have demonstrated recently that the tumor-to-blood standard uptake ratio (SUR) is superior to tumor standardized uptake value (SUV) as a surrogate of the metabolic uptake rate K m of fluorodeoxyglucose (FDG), overcoming several of the known shortcomings of the SUV approach: excellent linear correlation of SUR and K m from Patlak analysis was found using dynamic imaging of liver metastases. However, due to the perfectly standardized uptake period used for SUR determination and the comparatively short uptake period, these results are not automatically valid and applicable for clinical whole-body examinations in which the uptake periods (T) are distinctly longer and can vary considerably. Therefore, the aim of this work was to investigate the correlation between SUR derived from clinical static whole-body scans and K m-surrogate derived from dual time point (DTP) measurements. DTP (18)F-FDG PET/CT was performed in 90 consecutive patients with histologically proven non-small cell lung cancer (NSCLC). In the PET images, the primary tumor was delineated with an adaptive threshold method. For determination of the blood SUV, an aorta region of interest (ROI) was delineated manually in the attenuation CT and transferred to the PET image. Blood SUV was computed as the mean value of the aorta ROI. SUR values were computed as ratio of tumor SUV and blood SUV. SUR values from the early time point of each DTP measurement were scan time corrected to 75 min postinjection (SURtc). As surrogate of K m, we used the SUR(T) slope, K slope, derived from DTP measurements since it is proportional to the latter under the given circumstances. The correlation of SUV and SURtc with K slope was investigated. The prognostic value of SUV, SURtc, and K slope for overall survival (OS) and progression-free survival (PFS) was investigated with univariate Cox regression in a homogeneous subgroup (N=31) treated with primary chemoradiation. Correlation analysis revealed for both, SUV and SURtc, a clear linear correlation with K slope (P<0.001). Correlation SUR vs. K slope was considerably stronger than correlation SUV vs. K slope (R (2)=0.92 and R (2)=0.69, respectively, P<0.001). Univariate Cox regression revealed SURtc and K slope as significant prognostic factors for PFS (hazard ratio (HR) =3.4/ P=0.017 and HR =4.3/ P=0.020, respectively). For SUV, no significant effect was found. None of the investigated parameters was prognostic for OS. Scan-time-corrected SUR is a significantly better surrogate of tumor FDG metabolism in clinical whole-body PET compared to SUV. The very high linear correlation of SUR and DTP-derived K slope (which is proportional to actual K m) implies that for histologically proven malignant lesions, FDG-DTP does not provide added value in comparison to the SUR approach in NSCLC.

An Investigation of the Effects of Internal Waves on Sound Propagation in a Stratified Medium with a Sloping Bed

NASA Astrophysics Data System (ADS)

Deldar, H.; Bidokhti, A. A.; Chegini, V.

2018-01-01

Internal waves usually cause temporal and spatial changes of density and consequently affect the acoustic wave propagation in the ocean. The purpose of this study is a laboratory investigation of the effects of internal waves generated by oscillation of a cylinder in a large stratified glass tank with a sloping bed on the sound waves propagation. Results showed that sound waves are affected by internal waves that depend on the slope angle to the direction of internal wave propagation angle ratio. When the ratio is subcritical or supercritical, the acoustic signal is much reduced as compared to the case with no sloped bottom. This can be explained in terms of the internal waves energy reaching the sloped bed and their reflections.

Evaluation of Rainfall-induced Landslide Potential

NASA Astrophysics Data System (ADS)

Chen, Y. R.; Tsai, K. J.; Chen, J. W.; Chue, Y. S.; Lu, Y. C.; Lin, C. W.

2016-12-01

Due to Taiwan's steep terrain, rainfall-induced landslides often occur and lead to human causalities and properties loss. Taiwan's government has invested huge reconstruction funds to the affected areas. However, after rehabilitation they still face the risk of secondary sediment disasters. Therefore, this study assessed rainfall-induced landslide potential and spatial distribution in some watersheds of Southern Taiwan to configure reasonable assessment process and methods for landslide potential. This study focused on the multi-year multi-phase heavy rainfall events after 2009 Typhoon Morakot and applied the analysis techniques for the classification of satellite images of research region before and after rainfall to obtain surface information and hazard log data. GIS and DEM were employed to obtain the ridge and water system and to explore characteristics of landslide distribution. A multivariate hazards evaluation method was applied to quantitatively analyze the weights of various hazard factors. Furthermore, the interaction between rainfall characteristic, slope disturbance and landslide mechanism was analyzed. The results of image classification show that the values of coefficient of agreement are at medium-high level. The agreement of landslide potential map is at around 80% level compared with historical disaster sites. The relations between landslide potential level, slope disturbance degree, and the ratio of number and area of landslide increment corresponding heavy rainfall events are positive. The ratio of landslide occurrence is proportional to the value of instability index. Moreover, for each rainfall event, the number and scale of secondary landslide sites are much more than those of new landslide sites. The greater the slope land disturbance, the more likely it is that the scale of secondary landslide become greater. The spatial distribution of landslide depends on the interaction of rainfall patterns, slope, and elevation of the research area.

Evaluation strategies for isotope ratio measurements of single particles by LA-MC-ICPMS.

PubMed

Kappel, S; Boulyga, S F; Dorta, L; Günther, D; Hattendorf, B; Koffler, D; Laaha, G; Leisch, F; Prohaska, T

2013-03-01

Data evaluation is a crucial step when it comes to the determination of accurate and precise isotope ratios computed from transient signals measured by multi-collector-inductively coupled plasma mass spectrometry (MC-ICPMS) coupled to, for example, laser ablation (LA). In the present study, the applicability of different data evaluation strategies (i.e. 'point-by-point', 'integration' and 'linear regression slope' method) for the computation of (235)U/(238)U isotope ratios measured in single particles by LA-MC-ICPMS was investigated. The analyzed uranium oxide particles (i.e. 9073-01-B, CRM U010 and NUSIMEP-7 test samples), having sizes down to the sub-micrometre range, are certified with respect to their (235)U/(238)U isotopic signature, which enabled evaluation of the applied strategies with respect to precision and accuracy. The different strategies were also compared with respect to their expanded uncertainties. Even though the 'point-by-point' method proved to be superior, the other methods are advantageous, as they take weighted signal intensities into account. For the first time, the use of a 'finite mixture model' is presented for the determination of an unknown number of different U isotopic compositions of single particles present on the same planchet. The model uses an algorithm that determines the number of isotopic signatures by attributing individual data points to computed clusters. The (235)U/(238)U isotope ratios are then determined by means of the slopes of linear regressions estimated for each cluster. The model was successfully applied for the accurate determination of different (235)U/(238)U isotope ratios of particles deposited on the NUSIMEP-7 test samples.

A method for predicting the factor of safety of an infinite slope based on the depth ratio of the wetting front induced by rainfall infiltration

NASA Astrophysics Data System (ADS)

Chae, B.-G.; Lee, J.-H.; Park, H.-J.; Choi, J.

2015-08-01

Most landslides in Korea are classified as shallow landslides with an average depth of less than 2 m. These shallow landslides are associated with the advance of a wetting front in the unsaturated soil due to rainfall infiltration, which results in an increase in water content and a reduction in the matric suction in the soil. Therefore, this study presents a modified equation of infinite slope stability analysis based on the concept of the saturation depth ratio to analyze the slope stability change associated with the rainfall on a slope. A rainfall infiltration test in unsaturated soil was performed using a column to develop an understanding of the effect of the saturation depth ratio following rainfall infiltration. The results indicated that the rainfall infiltration velocity due to the increase in rainfall in the soil layer was faster when the rainfall intensity increased. In addition, the rainfall infiltration velocity tends to decrease with increases in the unit weight of soil. The proposed model was applied to assess its feasibility and to develop a regional landslide susceptibility map using a geographic information system (GIS). For that purpose, spatial databases for input parameters were constructed and landslide locations were obtained. In order to validate the proposed approach, the results of the proposed approach were compared with the landslide inventory using a ROC (receiver operating characteristics) graph. In addition, the results of the proposed approach were compared with the previous approach used: a steady-state hydrological model. Consequently, the approach proposed in this study displayed satisfactory performance in classifying landslide susceptibility and showed better performance than the steady-state approach.

Analysis of variation in calibration curves for Kodak XV radiographic film using model-based parameters.

PubMed

Hsu, Shu-Hui; Kulasekere, Ravi; Roberson, Peter L

2010-08-05

Film calibration is time-consuming work when dose accuracy is essential while working in a range of photon scatter environments. This study uses the single-target single-hit model of film response to fit the calibration curves as a function of calibration method, processor condition, field size and depth. Kodak XV film was irradiated perpendicular to the beam axis in a solid water phantom. Standard calibration films (one dose point per film) were irradiated at 90 cm source-to-surface distance (SSD) for various doses (16-128 cGy), depths (0.2, 0.5, 1.5, 5, 10 cm) and field sizes (5 × 5, 10 × 10 and 20 × 20 cm²). The 8-field calibration method (eight dose points per film) was used as a reference for each experiment, taken at 95 cm SSD and 5 cm depth. The delivered doses were measured using an Attix parallel plate chamber for improved accuracy of dose estimation in the buildup region. Three fitting methods with one to three dose points per calibration curve were investigated for the field sizes of 5 × 5, 10 × 10 and 20 × 20 cm². The inter-day variation of model parameters (background, saturation and slope) were 1.8%, 5.7%, and 7.7% (1 σ) using the 8-field method. The saturation parameter ratio of standard to 8-field curves was 1.083 ± 0.005. The slope parameter ratio of standard to 8-field curves ranged from 0.99 to 1.05, depending on field size and depth. The slope parameter ratio decreases with increasing depth below 0.5 cm for the three field sizes. It increases with increasing depths above 0.5 cm. A calibration curve with one to three dose points fitted with the model is possible with 2% accuracy in film dosimetry for various irradiation conditions. The proposed fitting methods may reduce workload while providing energy dependence correction in radiographic film dosimetry. This study is limited to radiographic XV film with a Lumisys scanner.

Validation of measurements of ventilation-to-perfusion ratio inequality in the lung from expired gas

NASA Technical Reports Server (NTRS)

Prisk, G. Kim; Guy, Harold J B.; West, John B.; Reed, James W.

2003-01-01

The analysis of the gas in a single expirate has long been used to estimate the degree of ventilation-perfusion (Va/Q) inequality in the lung. To further validate this estimate, we examined three measures of Va/Q inhomogeneity calculated from a single full exhalation in nine anesthetized mongrel dogs under control conditions and after exposure to aerosolized methacholine. These measurements were then compared with arterial blood gases and with measurements of Va/Q inhomogeneity obtained using the multiple inert gas elimination technique. The slope of the instantaneous respiratory exchange ratio (R slope) vs. expired volume was poorly correlated with independent measures, probably because of the curvilinear nature of the relationship due to continuing gas exchange. When R was converted to the intrabreath Va/Q (iV/Q), the best index was the slope of iV/Q vs. volume over phase III (iV/Q slope). This was strongly correlated with independent measures, especially those relating to inhomogeneity of perfusion. The correlations for iV/Q slope and R slope considerably improved when only the first half of phase III was considered. We conclude that a useful noninvasive measurement of Va/Q inhomogeneity can be derived from the intrabreath respiratory exchange ratio.

Concentrations and isotope ratios of mercury in sediments from shelf and continental slope at Campos Basin near Rio de Janeiro, Brazil.

PubMed

Araujo, Beatriz Ferreira; Hintelmann, Holger; Dimock, Brian; Almeida, Marcelo Gomes; Rezende, Carlos Eduardo

2017-07-01

Mercury (Hg) may originate from both anthropogenic and natural sources. The measurement of spatial and temporal variations of Hg isotope ratios in sediments may enable source identification and tracking of environmental processes. In this study we establish the distribution of mercury concentrations and mercury isotope ratios in surface sediments of three transects along the continental shelf and slope in Campos Basin-RJ-Brazil. The shelf showed on average lower total Hg concentrations (9.2 ± 5.3 ng g -1 ) than the slope (24.6 ± 8.8 ng g -1 ). MMHg average concentrations of shelf 0.15 ± 0.12 ng g -1 and slope 0.13 ± 0.06 ng g -1 were not significantly different. Distinct differences in Hg isotope ratio signatures were observed, suggesting that the two regions were impacted by different sources of Hg. The shelf showed more negative δ 202 Hg and Δ 199 Hg values ranging from -0.59 to -2.19‰ and from -0.76 to 0.08‰, respectively. In contrast, the slope exhibited δ 202 Hg values from -0.29 to -1.82‰ and Δ 199 Hg values from -0.23 to 0.09‰. Mercury found on the shelf, especially along the "D" and "I" transects, is depleted in heavy isotopes resulting in more negative δ 202 Hg compared to the slope. Isotope ratios observed in the "D" and "I" shelf region are similar to Hg ratios commonly associated with plants and vegetation and very comparable to those detected in the estuary and adjoining mangrove forest, which suggests that Hg exported from rivers may be the dominating source of Hg in near coastal regions along the northern part of the shelf. Copyright © 2017 Elsevier Ltd. All rights reserved.

Predictive landslide susceptibility mapping using spatial information in the Pechabun area of Thailand

NASA Astrophysics Data System (ADS)

Oh, Hyun-Joo; Lee, Saro; Chotikasathien, Wisut; Kim, Chang Hwan; Kwon, Ju Hyoung

2009-04-01

For predictive landslide susceptibility mapping, this study applied and verified probability model, the frequency ratio and statistical model, logistic regression at Pechabun, Thailand, using a geographic information system (GIS) and remote sensing. Landslide locations were identified in the study area from interpretation of aerial photographs and field surveys, and maps of the topography, geology and land cover were constructed to spatial database. The factors that influence landslide occurrence, such as slope gradient, slope aspect and curvature of topography and distance from drainage were calculated from the topographic database. Lithology and distance from fault were extracted and calculated from the geology database. Land cover was classified from Landsat TM satellite image. The frequency ratio and logistic regression coefficient were overlaid for landslide susceptibility mapping as each factor’s ratings. Then the landslide susceptibility map was verified and compared using the existing landslide location. As the verification results, the frequency ratio model showed 76.39% and logistic regression model showed 70.42% in prediction accuracy. The method can be used to reduce hazards associated with landslides and to plan land cover.

Local site effect of soil slope based on microtremor measurement in Samigaluh, Kulon Progo Yogyakarta

NASA Astrophysics Data System (ADS)

Prabowo, U. N.; Amalia, A. F.; Wiranata, F. E.

2018-03-01

This paper investigated soil slope-local site effect of earthquake inducing landslide by using microtremor Horizontal to Vertical Spectral Ratio (HVSR) method. Microtremor measurements of 15 sites which were recorded for 45 minutes at each site were carried out in Ngargosari village, Samigaluh, Kulon Progo-Indonesia. Microtremor analysis using HVSR method was performed using Geopsy software. HVSR method resulted in predominant frequency values that ranges between 2,77 to 13,82 Hz and amplification factors varied from 0,46 to 5,70. The predominant frequency is associated with the depth of bedrock and the amplification factor reflects the geological condition of soil (sedimentary layer). The soil vulnerability index (Kg) varied from 0,08 to 5,77 and the higher value (Kg>3,4) in the south of the research area was identified as the weak zone of earthquake inducing landslide.

The experimental and calculated characteristics of 22 tapered wings

NASA Technical Reports Server (NTRS)

Anderson, Raymond F

1938-01-01

The experimental and calculated aerodynamic characteristics of 22 tapered wings are compared, using tests made in the variable-density wind tunnel. The wings had aspect ratios from 6 to 12 and taper ratios from 1:6:1 and 5:1. The compared characteristics are the pitching moment, the aerodynamic-center position, the lift-curve slope, the maximum lift coefficient, and the curves of drag. The method of obtaining the calculated values is based on the use of wing theory and experimentally determined airfoil section data. In general, the experimental and calculated characteristics are in sufficiently good agreement that the method may be applied to many problems of airplane design.

An Additional Method for Analyzing the Reversible Inhibition of an 
Enzyme Using Acid Phosphatase as a Model.

PubMed

Baumhardt, Jordan M; Dorsey, Benjamin M; McLauchlan, Craig C; Jones, Marjorie A

2015-08-01

Using wheat germ acid phosphatase and sodium orthovanadate as a competitive inhibitor, a novel method for analyzing reversible inhibition was carried out. Our alternative approach involves plotting the initial velocity at which product is formed as a function of the ratio of substrate concentration to inhibitor concentration at a constant enzyme concentration and constant assay conditions. The concept of initial concentrations driving equilibrium leads to the chosen axes. Three apparent constants can be derived from this plot: K max , K min , and K inflect . K max and K min represent the substrate to inhibitor concentration ratio for complete inhibition and minimal inhibition, respectively. K inflect represents the substrate to inhibitor concentration ratio at which the enzyme-substrate complex is equal to the inhibitory complex. These constants can be interpolated from the graph or calculated using the first and second derivative of the plot. We conclude that a steeper slope and a shift of the line to the right (increased x-axis values) would indicate a better inhibitor. Since initial velocity is not a linear function of the substrate/inhibitor ratio, this means that inhibition changes more quickly with the change in the [S]/ [I] ratio. When preincubating the enzyme with substrate before the addition of inhibitor, preincubating the enzyme with inhibitor before the addition of substrate or with concurrent addition of both substrate and inhibitor, modest changes in the slopes and y-intercepts were obtained. This plot appears useful for known competitive and non-competitive inhibitors and may have general applicability.

Preclinical evaluation of parametric image reconstruction of [18F]FMISO PET: correlation with ex vivo immunohistochemistry

NASA Astrophysics Data System (ADS)

Cheng, Xiaoyin; Bayer, Christine; Maftei, Constantin-Alin; Astner, Sabrina T.; Vaupel, Peter; Ziegler, Sibylle I.; Shi, Kuangyu

2014-01-01

Compared to indirect methods, direct parametric image reconstruction (PIR) has the advantage of high quality and low statistical errors. However, it is not yet clear if this improvement in quality is beneficial for physiological quantification. This study aimed to evaluate direct PIR for the quantification of tumor hypoxia using the hypoxic fraction (HF) assessed from immunohistological data as a physiological reference. Sixteen mice with xenografted human squamous cell carcinomas were scanned with dynamic [18F]FMISO PET. Afterward, tumors were sliced and stained with H&E and the hypoxia marker pimonidazole. The hypoxic signal was segmented using k-means clustering and HF was specified as the ratio of the hypoxic area over the viable tumor area. The parametric Patlak slope images were obtained by indirect voxel-wise modeling on reconstructed images using filtered back projection and ordered-subset expectation maximization (OSEM) and by direct PIR (e.g., parametric-OSEM, POSEM). The mean and maximum Patlak slopes of the tumor area were investigated and compared with HF. POSEM resulted in generally higher correlations between slope and HF among the investigated methods. A strategy for the delineation of the hypoxic tumor volume based on thresholding parametric images at half maximum of the slope is recommended based on the results of this study.

Stable estimate of primary OC/EC ratios in the EC tracer method

NASA Astrophysics Data System (ADS)

Chu, Shao-Hang

In fine particulate matter studies, the primary OC/EC ratio plays an important role in estimating the secondary organic aerosol contribution to PM2.5 concentrations using the EC tracer method. In this study, numerical experiments are carried out to test and compare various statistical techniques in the estimation of primary OC/EC ratios. The influence of random measurement errors in both primary OC and EC measurements on the estimation of the expected primary OC/EC ratios is examined. It is found that random measurement errors in EC generally create an underestimation of the slope and an overestimation of the intercept of the ordinary least-squares regression line. The Deming regression analysis performs much better than the ordinary regression, but it tends to overcorrect the problem by slightly overestimating the slope and underestimating the intercept. Averaging the ratios directly is usually undesirable because the average is strongly influenced by unrealistically high values of OC/EC ratios resulting from random measurement errors at low EC concentrations. The errors generally result in a skewed distribution of the OC/EC ratios even if the parent distributions of OC and EC are close to normal. When measured OC contains a significant amount of non-combustion OC Deming regression is a much better tool and should be used to estimate both the primary OC/EC ratio and the non-combustion OC. However, if the non-combustion OC is negligibly small the best and most robust estimator of the OC/EC ratio turns out to be the simple ratio of the OC and EC averages. It not only reduces random errors by averaging individual variables separately but also acts as a weighted average of ratios to minimize the influence of unrealistically high OC/EC ratios created by measurement errors at low EC concentrations. The median of OC/EC ratios ranks a close second, and the geometric mean of ratios ranks third. This is because their estimations are insensitive to questionable extreme values. A real world example is given using the ambient data collected from an Atlanta STN site during the winter of 2001-2002.

Analysing hydro-mechanical behaviour of reinforced slopes through centrifuge modelling

NASA Astrophysics Data System (ADS)

Veenhof, Rick; Wu, Wei

2017-04-01

Every year, slope instability is causing casualties and damage to properties and the environment. The behaviour of slopes during and after these kind of events is complex and depends on meteorological conditions, slope geometry, hydro-mechanical soil properties, boundary conditions and the initial state of the soils. This study describes the effects of adding reinforcement, consisting of randomly distributed polyolefin monofilament fibres or Ryegrass (Lolium), on the behaviour of medium-fine sand in loose and medium dense conditions. Direct shear tests were performed on sand specimens with different void ratios, water content and fibre or root density, respectively. To simulate the stress state of real scale field situations, centrifuge model tests were conducted on sand specimens with different slope angles, thickness of the reinforced layer, fibre density, void ratio and water content. An increase in peak shear strength is observed in all reinforced cases. Centrifuge tests show that for slopes that are reinforced the period until failure is extended. The location of shear band formation and patch displacement behaviour indicate that the design of slope reinforcement has a significant effect on the failure behaviour. Future research will focus on the effect of plant water uptake on soil cohesion.

Large-eddy-simulation approach in understanding flow structures of 2D turbulent density currents over sloping surfaces

NASA Astrophysics Data System (ADS)

Nayamatullah, M.; Rao Pillalamarri, Narasimha; Bhaganagar, Kiran

2018-04-01

A numerical investigation was performed to understand the flow dynamics of 2D density currents over sloping surfaces. Large eddy simulation was conducted for lock-exchange (L-E) release currents and overflows. 2D Navier-Stokes equations were solved using the Boussinesq approximation. The effects of the lock aspect-ratio (height/length of lock), slope, and Reynolds number on the flow structures and turbulence mixing have been analyzed. Results have confirmed buoyancy within the head of the two-dimensional currents is not conserved which contradicts the classical thermal theory. The lock aspect-ratio dictates the fraction of initial buoyancy which is carried by the head of the current at the beginning of the slumping (horizontal) and accelerating phase (over a slope), which has important implications on turbulence kinetic energy production, and hence mixing in the current. For L-E flows over a slope, increasing slope angle enhances the turbulence production. Increasing slope results in shear reversal within the density current resulting in shear-instabilities. Differences in turbulence production mechanisms and flow structures exist between the L-E and constant-flux release currents resulting in significant differences in the flow characteristics between different releases.

[Relations of landslide and debris flow hazards to environmental factors].

PubMed

Zhang, Guo-ping; Xu, Jing; Bi, Bao-gui

2009-03-01

To clarify the relations of landslide and debris flow hazards to environmental factors is of significance to the prediction and evaluation of landslide and debris flow hazards. Base on the latitudinal and longitudinal information of 18431 landslide and debris flow hazards in China, and the 1 km x 1 km grid data of elevation, elevation difference, slope, slope aspect, vegetation type, and vegetation coverage, this paper analyzed the relations of landslide and debris flow hazards in this country to above-mentioned environmental factors by the analysis method of frequency ratio. The results showed that the landslide and debris flow hazards in China more occurred in lower elevation areas of the first and second transitional zones. When the elevation difference within a 1 km x 1 km grid cell was about 300 m and the slope was around 30 degree, there was the greatest possibility of the occurrence of landslide and debris hazards. Mountain forest land and slope cropland were the two land types the hazards most easily occurred. The occurrence frequency of the hazards was the highest when the vegetation coverage was about 80%-90%.

Developments in ambient noise analysis for the characterization of dynamic response of slopes to seismic shaking

NASA Astrophysics Data System (ADS)

Del Gaudio, Vincenzo; Wasowski, Janusz

2016-04-01

In the last few decades, we have witnessed a growing awareness of the role of site dynamic response to seismic shaking in slope failures during earthquakes. Considering the time and costs involved in acquiring accelerometer data on landslide prone slopes, the analysis of ambient noise offers a profitable investigative alternative. Standard procedures of ambient noise analysis, according to the technique known as HVNR or Nakamura's method, were originally devised to interpret data under simple site conditions similar to 1D layering (flat horizontal layering infinitely extended). In such cases, conditions of site amplification, characterized by a strong impedance contrast between a soft surface layer and a stiff bedrock, result in a single pronounced isotropic maximum of spectral ratios between horizontal and vertical component of ambient noise. However, previous studies have shown that the dynamic response of slopes affected by landslides is rather complex, being characterized by multiple resonance peaks with directional variability, thus, the use of standard techniques can encounter difficulties in providing reliable information. A new approach of data analysis has recently been proposed to exploit the potential of information content of Rayleigh waves present in ambient noise, with regard to the identification of frequency and orientation of directional resonance. By exploiting ground motion ellipticity this approach can also provide information on vertical distribution of S-wave velocity, which controls site amplification factors. The method, based on the identification of Rayleigh wave packets from instantaneous polarization properties of ambient noise, was first tested using synthetic signals in order to optimize the data processing system. Then the improved processing scheme is adopted to re-process and re-interpret the ambient noise data acquired on landslide prone slopes around Caramanico Terme (central Italy), at sites monitored also with accelerometer stations. The comparison of ambient noise analysis results with the outcomes of accelerometer monitoring reveals potential and limits of the new method for the investigations on slope dynamic response.

Limitations of Lifting-Line Theory for Estimation of Aileron Hinge-Moment Characteristics

NASA Technical Reports Server (NTRS)

Swanson, Robert S.; Gillis, Clarence L.

1943-01-01

Hinge-moment parameters for several typical ailerons were calculated from section data with the aspect-ratio correction as usually determined from lifting-line theory. The calculations showed that the agreement between experimental and calculated results was unsatisfactory. An additional aspect-ratio correction, calculated by the method of lifting-surface theory, was applied to the slope of the curve of hinge-moment coefficient against angle of attack at small angles of attack. This so-called streamline-curvature correction brought the calculated and experimental results into satisfactory agreement.

Using quasars as standard clocks for measuring cosmological redshift.

PubMed

Dai, De-Chang; Starkman, Glenn D; Stojkovic, Branislav; Stojkovic, Dejan; Weltman, Amanda

2012-06-08

We report hitherto unnoticed patterns in quasar light curves. We characterize segments of the quasar's light curves with the slopes of the straight lines fit through them. These slopes appear to be directly related to the quasars' redshifts. Alternatively, using only global shifts in time and flux, we are able to find significant overlaps between the light curves of different pairs of quasars by fitting the ratio of their redshifts. We are then able to reliably determine the redshift of one quasar from another. This implies that one can use quasars as standard clocks, as we explicitly demonstrate by constructing two independent methods of finding the redshift of a quasar from its light curve.

Comparison of Voltage Gated K+ Currents in Arterial Myocytes with Heterologously Expressed K v Subunits.

PubMed

Cox, Robert H; Fromme, Samantha

2016-12-01

We have shown that three components contribute to functional voltage gated K + (K v ) currents in rat small mesenteric artery myocytes: (1) Kv1.2 plus Kv1.5 with Kvβ1.2 subunits, (2) Kv2.1 probably associated with Kv9.3 subunits, and (3) Kv7.4 subunits. To confirm and address subunit stoichiometry of the first two, we have compared the biophysical properties of K v currents in small mesenteric artery myocytes with those of K v subunits heterologously expressed in HEK293 cells using whole cell voltage clamp methods. Selective inhibitors of Kv1 (correolide, COR) and Kv2 (stromatoxin, ScTx) channels were used to separate these K v current components. Conductance-voltage and steady state inactivation data along with time constants of activation, inactivation, and deactivation of native K v components were generally well represented by those of Kv1.2-1.5-β1.2 and Kv2.1-9.3 channels. The slope of the steady state inactivation-voltage curve (availability slope) proved to be the most sensitive measure of accessory subunit presence. The availability slope curves exhibited a single peak for both native K v components. Availability slope curves for Kv1.2-1.5-β1.2 and Kv2.1-9.3 channels expressed in human embryonic kidney cells also exhibited a single peak that shifted to more depolarized voltages with increasing accessory to α subunit transfection ratio. Availability slope curves for SxTc-insensitive currents were similar to those of Kv1.2-1.5 expressed with Kvβ1.2 at a 1:5 molar ratio while curves for COR-insensitive currents closely resembled those of Kv2.1 expressed with Kv9.3 at a 1:1 molar ratio. These results support the suggested K v subunit combinations in small mesenteric artery, and further suggest that Kv1 α and Kvβ1.2 but not Kv2.1 and Kv9.3 subunits are present in a saturated (4:4) stoichiometry.

Linear regression techniques for use in the EC tracer method of secondary organic aerosol estimation

NASA Astrophysics Data System (ADS)

Saylor, Rick D.; Edgerton, Eric S.; Hartsell, Benjamin E.

A variety of linear regression techniques and simple slope estimators are evaluated for use in the elemental carbon (EC) tracer method of secondary organic carbon (OC) estimation. Linear regression techniques based on ordinary least squares are not suitable for situations where measurement uncertainties exist in both regressed variables. In the past, regression based on the method of Deming [1943. Statistical Adjustment of Data. Wiley, London] has been the preferred choice for EC tracer method parameter estimation. In agreement with Chu [2005. Stable estimate of primary OC/EC ratios in the EC tracer method. Atmospheric Environment 39, 1383-1392], we find that in the limited case where primary non-combustion OC (OC non-comb) is assumed to be zero, the ratio of averages (ROA) approach provides a stable and reliable estimate of the primary OC-EC ratio, (OC/EC) pri. In contrast with Chu [2005. Stable estimate of primary OC/EC ratios in the EC tracer method. Atmospheric Environment 39, 1383-1392], however, we find that the optimal use of Deming regression (and the more general York et al. [2004. Unified equations for the slope, intercept, and standard errors of the best straight line. American Journal of Physics 72, 367-375] regression) provides excellent results as well. For the more typical case where OC non-comb is allowed to obtain a non-zero value, we find that regression based on the method of York is the preferred choice for EC tracer method parameter estimation. In the York regression technique, detailed information on uncertainties in the measurement of OC and EC is used to improve the linear best fit to the given data. If only limited information is available on the relative uncertainties of OC and EC, then Deming regression should be used. On the other hand, use of ROA in the estimation of secondary OC, and thus the assumption of a zero OC non-comb value, generally leads to an overestimation of the contribution of secondary OC to total measured OC.

Microfiber Structures for Sensor Applications

NASA Astrophysics Data System (ADS)

Harun, S. W.; Lim, K. S.; Ahmad, H.

Microfiber loop resonator (MLR) and microfiber knot resonator (MKR) are fabricated using melt-stretching method for applications in temperature and current sensor, respectively. The MLR is embedded into low refractive index polymer for robustness. Although the spacing of the transmission comb spectrum of the MLR is unchanged with temperature, the extinction ratio of the spectrum is observed to decrease linearly with temperature due to induced changes in the material's refractive index. The slope of the extinction ratio reduction against temperature is about 0.043dB/°C. With the assistance of a copper wire that is wrapped by the MKR, resonant wavelength can be tuned by varying the electric current delivered to the wire. The resonant wavelength change is based on the thermally induced optical phase shift in the MKR due to the heat produced by the flow of electric current over a short transit length. It is shown that the wavelength shift is linearly proportional to the square of current in the copper wire with a tuning slope of 46 pm/A2.

Nested taxa-area curves for eastern United States floras

USGS Publications Warehouse

Bennett, J.P.

1997-01-01

The slopes of log-log species-area curves have been studied extensively and found to be influenced by the range of areas under study. Two such studies of eastern United States floras have yielded species-area curve slopes which differ by more than 100%: 0.251 and 0.113. The first slope may be too steep because the flora of the world was included, and both may be too steep because noncontiguous areas were used. These two hypotheses were tested using a set of nested floras centered in Ohio and continuing up to the flora of the world. The results suggest that this set of eastern United States floras produces a log-log species-area curve with a slope of approximately 0.20 with the flora of the world excluded, and regardless of whether or not the floras are from nested areas. Genera- and family-area curves are less steep than species-area curves and show similar patterns. Taxa ratio curves also increase with area, with the species/family ratio showing the steepest slope.

How Do Adults Perceive, Analyse and Measure Slope?

ERIC Educational Resources Information Center

Duncan, Bruce; Chick, Helen

2013-01-01

Slope is a mathematical concept that is both fundamental to the study of advanced calculus and commonly perceived in everyday life. The measurement of steepness of terrain as a ratio is an example of an everyday application the concept of slope. In this study, a group of pre-service teachers were tested for their capacity to mathematize the…

Dealing with deep uncertainties in landslide modelling for disaster risk reduction under climate change

NASA Astrophysics Data System (ADS)

Almeida, Susana; Holcombe, Elizabeth Ann; Pianosi, Francesca; Wagener, Thorsten

2017-02-01

Landslides have large negative economic and societal impacts, including loss of life and damage to infrastructure. Slope stability assessment is a vital tool for landslide risk management, but high levels of uncertainty often challenge its usefulness. Uncertainties are associated with the numerical model used to assess slope stability and its parameters, with the data characterizing the geometric, geotechnic and hydrologic properties of the slope, and with hazard triggers (e.g. rainfall). Uncertainties associated with many of these factors are also likely to be exacerbated further by future climatic and socio-economic changes, such as increased urbanization and resultant land use change. In this study, we illustrate how numerical models can be used to explore the uncertain factors that influence potential future landslide hazard using a bottom-up strategy. Specifically, we link the Combined Hydrology And Stability Model (CHASM) with sensitivity analysis and Classification And Regression Trees (CART) to identify critical thresholds in slope properties and climatic (rainfall) drivers that lead to slope failure. We apply our approach to a slope in the Caribbean, an area that is naturally susceptible to landslides due to a combination of high rainfall rates, steep slopes, and highly weathered residual soils. For this particular slope, we find that uncertainties regarding some slope properties (namely thickness and effective cohesion of topsoil) are as important as the uncertainties related to future rainfall conditions. Furthermore, we show that 89 % of the expected behaviour of the studied slope can be characterized based on only two variables - the ratio of topsoil thickness to cohesion and the ratio of rainfall intensity to duration.

Renal outcomes of agalsidase beta treatment for Fabry disease: role of proteinuria and timing of treatment initiation

PubMed Central

Ortiz, Alberto; Mauer, Michael; Linthorst, Gabor E.; Oliveira, João P.; Serra, Andreas L.; Maródi, László; Mignani, Renzo; Vujkovac, Bojan; Beitner-Johnson, Dana; Lemay, Roberta; Cole, J.Alexander; Svarstad, Einar; Waldek, Stephen; Germain, Dominique P.; Wanner, Christoph

2012-01-01

Background. The purpose of this study was to identify determinants of renal disease progression in adults with Fabry disease during treatment with agalsidase beta. Methods. Renal function was evaluated in 151 men and 62 women from the Fabry Registry who received agalsidase beta at an average dose of 1 mg/kg/2 weeks for at least 2 years. Patients were categorized into quartiles based on slopes of estimated glomerular filtration rate (eGFR) during treatment. Multivariate logistic regression analyses were used to identify factors associated with renal disease progression. Results. Men within the first quartile had a mean eGFR slope of –0.1 mL/min/1.73m2/year, whereas men with the most rapid renal disease progression (Quartile 4) had a mean eGFR slope of –6.7 mL/min/1.73m2/year. The risk factor most strongly associated with renal disease progression was averaged urinary protein:creatinine ratio (UP/Cr) ≥1 g/g (odds ratio 112, 95% confidence interval (95% CI) 4–3109, P = 0.0054). Longer time from symptom onset to treatment was also associated with renal disease progression (odds ratio 19, 95% CI 2–184, P = 0.0098). Women in Quartile 4 had the highest averaged UP/Cr (mean 1.8 g/g) and the most rapid renal disease progression: (mean slope –4.4 mL/min/1.73m2/year). Conclusions. Adults with Fabry disease are at risk for progressive loss of eGFR despite enzyme replacement therapy, particularly if proteinuria is ≥1 g/g. Men with little urinary protein excretion and those who began receiving agalsidase beta sooner after the onset of symptoms had stable renal function. These findings suggest that early intervention may lead to optimal renal outcomes. PMID:21804088

NADiA ProsVue prostate-specific antigen slope is an independent prognostic marker for identifying men at reduced risk of clinical recurrence of prostate cancer after radical prostatectomy.

PubMed

Moul, Judd W; Lilja, Hans; Semmes, O John; Lance, Raymond S; Vessella, Robert L; Fleisher, Martin; Mazzola, Clarisse; Sarno, Mark J; Stevens, Barbara; Klem, Robert E; McDermed, Jonathan E; Triebell, Melissa T; Adams, Thomas H

2012-12-01

To validate the hypothesis that men displaying serum prostate-specific antigen (PSA) slopes ≤ 2.0 pg/mL/mo after prostatectomy, measured using a new immuno-polymerase chain reaction diagnostic test (NADiA ProsVue), have a reduced risk of clinical recurrence as determined by positive biopsy, imaging findings, or death from prostate cancer. From 4 clinical sites, we selected a cohort of 304 men who had been followed up for 17.6 years after prostatectomy for clinical recurrence. We assessed the prognostic value of a PSA slope cutpoint of 2.0 pg/mL/mo against established risk factors to identify men at low risk of clinical recurrence using uni- and multivariate Cox proportional hazards regression and Kaplan-Meier analyses. The univariate hazard ratio of a PSA slope >2.0 pg/mL/mo was 18.3 (95% confidence interval 10.6-31.8) compared with a slope ≤ 2.0 pg/mL/mo (P <.0001). The median disease-free survival interval was 4.8 years vs >10 years in the 2 groups (P <.0001). The multivariate hazard ratio for PSA slope with the covariates of preprostatectomy PSA, pathologic stage, and Gleason score was 9.8 (95% confidence interval 5.4-17.8), an 89.8% risk reduction for men with PSA slopes ≤ 2.0 pg/mL/mo (P <.0001). The Gleason score (<7 vs ≥ 7) was the only other significant predictor (hazard ratio 5.4, 95% confidence interval 2.1-13.8, P = .0004). Clinical recurrence after radical prostatectomy is difficult to predict using established risk factors. We have demonstrated that a NADiA ProsVue PSA slope of ≤ 2.0 pg/mL/mo after prostatectomy is prognostic for a reduced risk of prostate cancer recurrence and adds predictive power to the established risk factors. Copyright © 2012 Elsevier Inc. All rights reserved.

Using Controlled Landslide Initiation Experiments to Test Limit-Equilibrium Analyses of Slope Stability

NASA Astrophysics Data System (ADS)

Reid, M. E.; Iverson, R. M.; Brien, D. L.; Iverson, N. R.; Lahusen, R. G.; Logan, M.

2004-12-01

Most studies of landslide initiation employ limit equilibrium analyses of slope stability. Owing to a lack of detailed data, however, few studies have tested limit-equilibrium predictions against physical measurements of slope failure. We have conducted a series of field-scale, highly controlled landslide initiation experiments at the USGS debris-flow flume in Oregon; these experiments provide exceptional data to test limit equilibrium methods. In each of seven experiments, we attempted to induce failure in a 0.65m thick, 2m wide, 6m3 prism of loamy sand placed behind a retaining wall in the 31° sloping flume. We systematically investigated triggering of sliding by groundwater injection, by prolonged moderate-intensity sprinkling, and by bursts of high intensity sprinkling. We also used vibratory compaction to control soil porosity and thereby investigate differences in failure behavior of dense and loose soils. About 50 sensors were monitored at 20 Hz during the experiments, including nests of tiltmeters buried at 7 cm spacing to define subsurface failure geometry, and nests of tensiometers and pore-pressure sensors to define evolving pore-pressure fields. In addition, we performed ancillary laboratory tests to measure soil porosity, shear strength, hydraulic conductivity, and compressibility. In loose soils (porosity of 0.52 to 0.55), abrupt failure typically occurred along the flume bed after substantial soil deformation. In denser soils (porosity of 0.41 to 0.44), gradual failure occurred within the soil prism. All failure surfaces had a maximum length to depth ratio of about 7. In even denser soil (porosity of 0.39), we could not induce failure by sprinkling. The internal friction angle of the soils varied from 28° to 40° with decreasing porosity. We analyzed stability at failure, given the observed pore-pressure conditions just prior to large movement, using a 1-D infinite-slope method and a more complete 2-D Janbu method. Each method provides a static Factor of Safety (FS), and in theory failure occurs when FS ≤ 1. Using the 1-D analysis, all experiments having failure had FS well below 1 (typically 0.5-0.8). Using the 2-D analysis for these same conditions, FS was less than but closer to 1 (typically 0.8-0.9). For the experiment with no failure, the 2-D FS was, reassuringly, > 1. These results indicate that the 2-D Janbu analysis is more accurate than the 1-D infinite-slope method for computing limit-equilibrium slope stability in shallow slides with limited areal extent.

Using multiple logistic regression and GIS technology to predict landslide hazard in northeast Kansas, USA

USGS Publications Warehouse

Ohlmacher, G.C.; Davis, J.C.

2003-01-01

Landslides in the hilly terrain along the Kansas and Missouri rivers in northeastern Kansas have caused millions of dollars in property damage during the last decade. To address this problem, a statistical method called multiple logistic regression has been used to create a landslide-hazard map for Atchison, Kansas, and surrounding areas. Data included digitized geology, slopes, and landslides, manipulated using ArcView GIS. Logistic regression relates predictor variables to the occurrence or nonoccurrence of landslides within geographic cells and uses the relationship to produce a map showing the probability of future landslides, given local slopes and geologic units. Results indicated that slope is the most important variable for estimating landslide hazard in the study area. Geologic units consisting mostly of shale, siltstone, and sandstone were most susceptible to landslides. Soil type and aspect ratio were considered but excluded from the final analysis because these variables did not significantly add to the predictive power of the logistic regression. Soil types were highly correlated with the geologic units, and no significant relationships existed between landslides and slope aspect. ?? 2003 Elsevier Science B.V. All rights reserved.

Investigating Deep-Marine Sediment Waves in the Northern Gulf of Mexico Using 3D Seismic Data

NASA Astrophysics Data System (ADS)

Wang, Z.; Gani, M. R.

2016-12-01

Deep-water depositional elements have been studied for decades using outcrop, flume tank, sidescan sonar, and seismic data. Even though they have been well recognized by researchers, the improvements in the quality of 3D seismic data with increasingly larger dimension allow detailed analysis of deep-water depositional elements with new insights. This study focuses on the deep-marine sediment waves in the northern Gulf of Mexico. By interpreting a 3D seismic dataset covering 635 km2 at Mississippi Canyon and Viosca Knoll areas, large sediment waves, generated by sediment gravity flows, were mapped and analyzed with various seismic attributes. A succession of sediment waves, approximately 100 m in thickness, is observed on the marine slope that tapers out at the toe of the slope. The individual sediment wave exhibits up to 500 m in wavelength and up to 20 m in height. The wave crests oriented northeast-southwest are broadly aligned parallel to the regional slope-strike, indicating their sediment gravity flow origin. The crestlines are straight or slightly sinuous, with sinuosity increasing downslope. Their anti-dune patterns likely imply the presence of supercritical flows. The sediment waves have a retrogradational stacking pattern. Seismic amplitude maps of each sediment wave revealed that after depositing the majority of sheet-like sands on the upper slope, sediment gravity flows started to form large sediment waves on the lower slope. The steep and narrow upcurrent flanks of the sediment waves always display higher amplitudes than the gentle and wide downcurrent flanks, indicating that the sands were likely preferentially trapped along the upcurrent flanks, whereas the muds spread along the downcurrent flanks. The formation of sediment waves likely requires a moderate sand-mud ratio, as suggested by these observations: (1) absence of sediment waves on the upper slope where the sands were mainly deposited as unconfined sheets with a high sand-mud ratio; (2) absence of sediment waves on the basin floor, which is covered mainly by muds and hemipelagic sediments with a low sand-mud ratio; and (3) presence of sediment waves on the lower slope with a moderate sand-mud ratio.

Prognostic value of the oxygen uptake efficiency slope and other exercise variables in patients with coronary artery disease.

PubMed

Coeckelberghs, Ellen; Buys, Roselien; Goetschalckx, Kaatje; Cornelissen, Véronique A; Vanhees, Luc

2016-02-01

Peak exercise capacity is an independent predictor for mortality in patients with coronary artery disease. However, sometimes cardiopulmonary exercise tests are stopped prematurely. Therefore, submaximal exercise measures such as the oxygen uptake efficiency slope have been introduced. The aim of this study was to assess the prognostic value of the oxygen uptake efficiency slope and other exercise parameters, in patients with coronary artery disease. Between 2000 and 2011, 1409 patients with coronary artery disease (age 60.7 ± 9.9 years; 1205 males) underwent cardiopulmonary exercise tests. A maximal effort was not reached in 161 (11.5%) patients. The oxygen uptake efficiency slope was calculated and information on mortality was obtained. Cox proportional hazards regression analyses were used to assess the relation of oxygen uptake efficiency slope and other gas exchange variables with all-cause and cardiovascular mortality. Receiver operating characteristic curve analyses was performed to define optimal cut-off values. During an average follow-up of 7.45 ± 3.20 years (range 0.16-13.95 years), 158 patients died, among which 68 patients for cardiovascular reasons. The oxygen uptake efficiency slope was related to all-cause (hazard ratio: 0.568, p < 0.001) and cardiovascular (hazard ratio: 0.461, p < 0.001) mortality. When significant covariates were entered in the analysis, oxygen uptake efficiency slope remained related to mortality (p < 0.05). When other submaximal exercise parameters were added to the model, oxygen uptake efficiency slope and minute ventilation/carbon dioxide production slope also remained significantly related to mortality. The oxygen uptake efficiency slope is an independent predictor for all-cause and cardiovascular mortality in patients with coronary artery disease, irrespective of a truly maximal effort during cardiopulmonary exercise tests. Furthermore, the oxygen uptake efficiency slope provides prognostic information, complementary to the minute ventilation/carbon dioxide production slope and peak exercise capacity. © The European Society of Cardiology 2015.

Lidar stand-alone retrieval of atmospheric aerosol microphysical properties during SLOPE

NASA Astrophysics Data System (ADS)

Ortiz-Amezcua, Pablo; Samaras, Stefanos; Böckmann, Christine; Antonio Benavent-Oltra, Jose; Luis Guerrero-Rascado, Juan; Román, Roberto; Alados-Arboledas, Lucas

2018-04-01

Two cases from SLOPE campaign at Granada are analyzed in terms of particle microphysical properties using novel software developed at Potsdam University. Multiwavelength Raman lidar measurements of particle extinction and backscatter coefficients as well as linear particle depolarization ratios are used as input for the software. The result of the retrieval is a 2-dimensional particle volume distribution as a function of radius and aspect ratio, from which the particle microphysical properties are obtained.

Ocean subsurface particulate backscatter estimation from CALIPSO spaceborne lidar measurements

NASA Astrophysics Data System (ADS)

Chen, Peng; Pan, Delu; Wang, Tianyu; Mao, Zhihua

2017-10-01

A method for ocean subsurface particulate backscatter estimation from the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) on the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite was demonstrated. The effects of the CALIOP receiver's transient response on the attenuated backscatter profile were first removed. The two-way transmittance of the overlying atmosphere was then estimated as the ratio of the measured ocean surface attenuated backscatter to the theoretical value computed from wind driven wave slope variance. Finally, particulate backscatter was estimated from the depolarization ratio as the ratio of the column-integrated cross-polarized and co-polarized channels. Statistical results show that the derived particulate backscatter by the method based on CALIOP data agree reasonably well with chlorophyll-a concentration using MODIS data. It indicates a potential use of space-borne lidar to estimate global primary productivity and particulate carbon stock.

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

NASA Astrophysics Data System (ADS)

Yilmaz, Işık

2009-06-01

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

Determination of the proton-to-helium ratio in cosmic rays at ultra-high energies from the tail of the Xmax distribution

NASA Astrophysics Data System (ADS)

Yushkov, A.; Risse, M.; Werner, M.; Krieg, J.

2016-12-01

We present a method to determine the proton-to-helium ratio in cosmic rays at ultra-high energies. It makes use of the exponential slope, Λ, of the tail of the Xmax distribution measured by an air shower experiment. The method is quite robust with respect to uncertainties from modeling hadronic interactions and to systematic errors on Xmax and energy, and to the possible presence of primary nuclei heavier than helium. Obtaining the proton-to-helium ratio with air shower experiments would be a remarkable achievement. To quantify the applicability of a particular mass-sensitive variable for mass composition analysis despite hadronic uncertainties we introduce as a metric the 'analysis indicator' and find an improved performance of the Λ method compared to other variables currently used in the literature. The fraction of events in the tail of the Xmax distribution can provide additional information on the presence of nuclei heavier than helium in the primary beam.

Individual Differences in Auditory Brainstem Response Wave Characteristics

PubMed Central

Jagadeesh, Anoop; Mauermann, Manfred; Ernst, Frauke

2016-01-01

Little is known about how outer hair cell loss interacts with noise-induced and age-related auditory nerve degradation (i.e., cochlear synaptopathy) to affect auditory brainstem response (ABR) wave characteristics. Given that listeners with impaired audiograms likely suffer from mixtures of these hearing deficits and that ABR amplitudes have successfully been used to isolate synaptopathy in listeners with normal audiograms, an improved understanding of how different hearing pathologies affect the ABR source generators will improve their sensitivity in hearing diagnostics. We employed a functional model for human ABRs in which different combinations of hearing deficits were simulated and show that high-frequency cochlear gain loss steepens the slope of the ABR Wave-V latency versus intensity and amplitude versus intensity curves. We propose that grouping listeners according to a ratio of these slope metrics (i.e., the ABR growth ratio) might offer a way to factor out the outer hair cell loss deficit and maximally relate individual differences for constant ratios to other peripheral hearing deficits such as cochlear synaptopathy. We compared the model predictions to recorded click-ABRs from 30 participants with normal or high-frequency sloping audiograms and confirm the predicted relationship between the ABR latency growth curve and audiogram slope. Experimental ABR amplitude growth showed large individual differences and was compared with the Wave-I amplitude, Wave-V/I ratio, or the interwaveI–W latency in the same listeners. The model simulations along with the ABR recordings suggest that a hearing loss profile depicting the ABR growth ratio versus the Wave-I amplitude or Wave-V/I ratio might be able to differentiate outer hair cell deficits from cochlear synaptopathy in listeners with mixed pathologies. PMID:27837052

High power, high signal-to-noise ratio single-frequency 1μm Brillouin all-fiber laser

NASA Astrophysics Data System (ADS)

Wang, Jing; Hou, Yubin; Zhang, Qian; Jin, Dongchen; Sun, Ruoyu; Shi, Hongxing; Liu, Jiang; Wang, Pu

2016-03-01

We demonstrate a high-power, high signal-to-noise ratio single-frequency 1 μm Brillouin all-fiber laser with high slope efficiency. The Brillouin laser system consists of a high-power single-frequency fiber laser and a single-pass Brillouin ring cavity. The high-power single-frequency fiber laser is one-stage master-oscillator power amplifier with the maximum output power of 10.33 W, the signal-to-noise ratio of 50 dB and the slope efficiency of 46%. The Brillouin fiber laser is pumped by the amplified laser with a linewidth of 33 kHz and an output power of 2.61 W limited by the damage threshold of the optical isolator. By optimizing the length of the Brillouin ring cavity to 10 m, stable singlefrequency Brillouin fiber laser is obtained with 3 kHz linewidth owing to the linewidth narrowing effect. At the launched pump power of 2.15 W, the Brillouin fiber laser generates maximum output power of 1.4 W with a slope efficiency of 79% and the optical signal-to-noise ratio of 77 dB.

C:N:P Molar Ratios, Sources and 14C Dating of Surficial Sediments from the NW Slope of Cuba.

PubMed

de la Lanza Espino, Guadalupe; Soto, Luis A

2015-01-01

The surficial sediments recovered from 12 sites located near the channel axis of the Florida Straits and the lower slope off NW Cuba were analyzed for total organic carbon (TOC), nitrogen (TN), phosphorus (TP), elemental C:N:P ratios, C and N isotopic values, and 14C dating. The depth profiles of TOC, TN, and TP (0-18 cm) displayed a downcore trend and a significant variation. The TOC values were low (0.15 to 0.62%; 66 to 516 µmol g(-1)). Sites near the island's lower slope had lower TOC average concentrations (158-333 µmol g(-1)) than those closer to the channel axis (averaging 341-516 µmol g(-1); p <0.05). The TN concentrations near the lower slope attained 0.11% (80 µmol g(-1)), whereas, towards the channel axis, they decreased to 0.07% (55 µmol g(-1); p<0.05). The C:N ratios ranged from 1.9 to 10.2. The mean molar C:N ratio (5.4) indicated a marine hemipelagic deposition. The TP was lower at sites near the lower slope (38.4 to 50.0 µmol gv; 0.12% to 0.16%) than those near the channel axis (50.0 to 66 µmol g(-1); 0.15 to 0.21%). C:P fluctuated from 7.7 to 14.1 in the surficial sediment layer. The bulk organic δ13Corg and δ15N values confirmed pelagic organic sources, and the 14C dating revealed that the sediments were deposited during the Holocene (1000-5000 yr BP). We suggest that the hydrodynamic conditions in the Straits influence vertical and advective fluxes of particulate organic material trapped in the mixed-layer, which reduces the particulate matter flux to the seabed.

Associations between Verbal Learning Slope and Neuroimaging Markers across the Cognitive Aging Spectrum.

PubMed

Gifford, Katherine A; Phillips, Jeffrey S; Samuels, Lauren R; Lane, Elizabeth M; Bell, Susan P; Liu, Dandan; Hohman, Timothy J; Romano, Raymond R; Fritzsche, Laura R; Lu, Zengqi; Jefferson, Angela L

2015-07-01

A symptom of mild cognitive impairment (MCI) and Alzheimer's disease (AD) is a flat learning profile. Learning slope calculation methods vary, and the optimal method for capturing neuroanatomical changes associated with MCI and early AD pathology is unclear. This study cross-sectionally compared four different learning slope measures from the Rey Auditory Verbal Learning Test (simple slope, regression-based slope, two-slope method, peak slope) to structural neuroimaging markers of early AD neurodegeneration (hippocampal volume, cortical thickness in parahippocampal gyrus, precuneus, and lateral prefrontal cortex) across the cognitive aging spectrum [normal control (NC); (n=198; age=76±5), MCI (n=370; age=75±7), and AD (n=171; age=76±7)] in ADNI. Within diagnostic group, general linear models related slope methods individually to neuroimaging variables, adjusting for age, sex, education, and APOE4 status. Among MCI, better learning performance on simple slope, regression-based slope, and late slope (Trial 2-5) from the two-slope method related to larger parahippocampal thickness (all p-values<.01) and hippocampal volume (p<.01). Better regression-based slope (p<.01) and late slope (p<.01) were related to larger ventrolateral prefrontal cortex in MCI. No significant associations emerged between any slope and neuroimaging variables for NC (p-values ≥.05) or AD (p-values ≥.02). Better learning performances related to larger medial temporal lobe (i.e., hippocampal volume, parahippocampal gyrus thickness) and ventrolateral prefrontal cortex in MCI only. Regression-based and late slope were most highly correlated with neuroimaging markers and explained more variance above and beyond other common memory indices, such as total learning. Simple slope may offer an acceptable alternative given its ease of calculation.

Evaluation of drainage-area ratio method used to estimate streamflow for the Red River of the North Basin, North Dakota and Minnesota

USGS Publications Warehouse

Emerson, Douglas G.; Vecchia, Aldo V.; Dahl, Ann L.

2005-01-01

The drainage-area ratio method commonly is used to estimate streamflow for sites where no streamflow data were collected. To evaluate the validity of the drainage-area ratio method and to determine if an improved method could be developed to estimate streamflow, a multiple-regression technique was used to determine if drainage area, main channel slope, and precipitation were significant variables for estimating streamflow in the Red River of the North Basin. A separate regression analysis was performed for streamflow for each of three seasons-- winter, spring, and summer. Drainage area and summer precipitation were the most significant variables. However, the regression equations generally overestimated streamflows for North Dakota stations and underestimated streamflows for Minnesota stations. To correct the bias in the residuals for the two groups of stations, indicator variables were included to allow both the intercept and the coefficient for the logarithm of drainage area to depend on the group. Drainage area was the only significant variable in the revised regression equations. The exponents for the drainage-area ratio were 0.85 for the winter season, 0.91 for the spring season, and 1.02 for the summer season.

Capnogram slope and ventilation dead space parameters: comparison of mainstream and sidestream techniques

PubMed Central

Balogh, A. L.; Petak, F.; Fodor, G. H.; Tolnai, J.; Csorba, Z.; Babik, B.

2016-01-01

Background Capnography may provide useful non-invasive bedside information concerning heterogeneity in lung ventilation, ventilation–perfusion mismatching and metabolic status. Although the capnogram may be recorded by mainstream and sidestream techniques, the capnogram indices furnished by these approaches have not previously been compared systematically. Methods Simultaneous mainstream and sidestream time and volumetric capnography was performed in anaesthetized, mechanically ventilated patients undergoing elective heart surgery. Time capnography was used to assess the phase II (SII,T) and III slopes (SIII,T). The volumetric method was applied to estimate phase II (SII,V) and III slopes (SIII,V), together with the dead space values according to the Fowler (VDF), Bohr (VDB), and Enghoff (VDE) methods and the volume of CO2 eliminated per breath (VCO2). The partial pressure of end-tidal CO2 (PETCO2) was registered. Results Excellent correlation and good agreement were observed in SIII,T measured by the mainstream and sidestream techniques [ratio=1.05 (sem 0.16), R2=0.92, P<0.0001]. Although the sidestream technique significantly underestimated VCO2 and overestimated SIII,V [1.32 (0.28), R2=0.93, P<0.0001], VDF, VDB, and VDE, the agreement between the mainstream and sidestream techniques in the difference between VDE and VDB, reflecting the intrapulmonary shunt, was excellent [0.97 (0.004), R2=0.92, P<0.0001]. The PETCO2 exhibited good correlation and mild differences between the mainstream and sidestream approaches [0.025 (0.005) kPa]. Conclusions Sidestream capnography provides adequate quantitative bedside information about uneven alveolar emptying and ventilation–perfusion mismatching, because it allows reliable assessments of the phase III slope, PETCO2 and intrapulmonary shunt. Reliable measurement of volumetric parameters (phase II slope, dead spaces, and eliminated CO2 volumes) requires the application of a mainstream device. PMID:27317710

Environmental drivers of spatial patterns of topsoil nitrogen and phosphorus under monsoon conditions in a complex terrain of South Korea

PubMed Central

Choi, Kwanghun; Spohn, Marie; Park, Soo Jin; Huwe, Bernd; Ließ, Mareike

2017-01-01

Nitrogen (N) and phosphorus (P) in topsoils are critical for plant nutrition. Relatively little is known about the spatial patterns of N and P in the organic layer of mountainous landscapes. Therefore, the spatial distributions of N and P in both the organic layer and the A horizon were analyzed using a light detection and ranging (LiDAR) digital elevation model and vegetation metrics. The objective of the study was to analyze the effect of vegetation and topography on the spatial patterns of N and P in a small watershed covered by forest in South Korea. Soil samples were collected using the conditioned latin hypercube method. LiDAR vegetation metrics, the normalized difference vegetation index (NDVI), and terrain parameters were derived as predictors. Spatial explicit predictions of N/P ratios were obtained using a random forest with uncertainty analysis. We tested different strategies of model validation (repeated 2-fold to 20-fold and leave-one-out cross validation). Repeated 10-fold cross validation was selected for model validation due to the comparatively high accuracy and low variance of prediction. Surface curvature was the best predictor of P contents in the organic layer and in the A horizon, while LiDAR vegetation metrics and NDVI were important predictors of N in the organic layer. N/P ratios increased with surface curvature and were higher on the convex upper slope than on the concave lower slope. This was due to P enrichment of the soil on the lower slope and a more even spatial distribution of N. Our digital soil maps showed that the topsoils on the upper slopes contained relatively little P. These findings are critical for understanding N and P dynamics in mountainous ecosystems. PMID:28837590

Effects of wind velocity and slope on fire behavior

Treesearch

D.R. Weise; G.S. Biging

1994-01-01

Effects of wind velocity and slope on fire spread rate and flame length were examined. Fuel beds of vertical sticks (13.97 cm x 0.455 cm x 0.1 10 cm) and coarse excelsior were burned in an open-topped tilting wind tunnel. Mean fuel moisture content of sticks and excelsior was 11% and 12%, respectively. Mean surface area to volume ratio was 23 cm-! Five slopes (negative...

Dual-tracer method to estimate coral reef response to a plume of chemically modified seawater

NASA Astrophysics Data System (ADS)

Maclaren, J. K.; Caldeira, K.

2013-12-01

We present a new method, based on measurement of seawater samples, to estimate the response of a reef ecosystem to a plume of an additive (for example, a nutrient or other chemical). In the natural environment, where there may be natural variability in concentrations, it can be difficult to distinguish between changes in concentrations that would occur naturally and changes in concentrations that result from a chemical addition. Furthermore, in the unconfined natural environment, chemically modified water can mix with waters that have not been modified, making it difficult to distinguish between effects of dilution and effects of chemical fluxes or transformations. We present a dual-tracer method that extracts signals from observations that may be affected by both natural variability and dilution. In this dual-tracer method, a substance (in our example case, alkalinity) is added to the water in known proportion to a passive conservative tracer (in our example case, Rhodamine WT dye). The resulting plume of seawater is allowed to flow over the study site. Two transects are drawn across the plume at the front and back of the study site. If, in our example, alkalinity is plotted as a function of dye concentration for the front transect, the slope of the resulting mixing line is the ratio of alkalinity to dye in the added fluid. If a similar mixing line is measured and calculated for the back transect, the slope of this mixing line will indicate the amount of added alkalinity that remains in the water flowing out of the study site per unit of added dye. The ratio of the front and back slopes indicates the fraction of added alkalinity that was taken up by the reef. The method is demonstrated in an experiment performed on One Tree Reef (Queensland, Australia) aimed at showing that ocean acidification is already affecting coral reef growth. In an effort to chemically reverse some of the changes to seawater chemistry that have occurred over the past 200 years, we added sodium hydroxide to increase alkalinity in the plume and controlled for dilution with Rhodamine WT dye. Preliminary data will be presented and analyzed using the approach described above.

The role of topography and surface cover upon soil formation along hillslopes in arid climates

NASA Astrophysics Data System (ADS)

Yair, Aaron

1990-09-01

Two north-facing soil toposequences were selected from within the northern Negev desert, Israel, where average annual rainfall ranges from 70 to 200 mm. Both slopes are composed of an upper rocky and a lower colluvial section. Similar trends were found along both slopes. A high salt content was characteristic of soils at the top of the slope; salinity decreased downslope within the rocky slope section. The opposite occurred along the colluvial slopes, with salinity increasing sharply downslope. At any location along the slopes the northernmost soil toposequence site (160 mm average annual rainfall) represents, from a pedological point of view, an environment which is far more arid than its climatologically drier, more southern counterpart. The explanation provided for the variation of soil proporties at the scale of single hillslopes and at the regional scale is the same. It is contended that water input into the soil, and therefore leaching intensity, is positively related to the ratio of bedrock/soil cover. Rocky areas have limited infiltration, thus yielding high runoff rates into adjoining soil-covered areas, and contribute to water concentration, deeper infiltration and leaching intensity. Soil or sediment-covered areas having relatively high absorption capacities will experience reduced runoff, shallow infiltration and decreased water availability for leaching. This leads over time to salt accumulation at a shallow depth. The decrease in rock/soil ratio downslope within the colluvium is therefore held responsible for the corresponding increase in salinity. Similarly, the greater salinity of the soils in the northern site is explained by the fact that its rock/soil ratio is lower than in the southern area. The theoretical and practical implications regarding the relationship between climatic change and landscape evolution in arid areas are briefly discussed.

Relationship between consecutive deterioration of mean deviation value and progression of visual field defect in open-angle glaucoma.

PubMed

Naito, Tomoko; Yoshikawa, Keiji; Mizoue, Shiro; Nanno, Mami; Kimura, Tairo; Suzumura, Hirotaka; Takeda, Ryuji; Shiraga, Fumio

2015-01-01

To analyze the relationship between consecutive deterioration of mean deviation (MD) value and glaucomatous visual field (VF) progression in open-angle glaucoma (OAG), including primary OAG and normal tension glaucoma. The subjects of the study were patients undergoing treatment for OAG who had performed VF tests at least 10 times with a Humphrey field analyzer (SITA standard, C30-2 program). The VF progression was defined by a significantly negative MD slope (MD slope worsening) at the final VF test during the follow-up period. The relationship between the MD slope worsening and the consecutive deterioration of MD value were retrospectively analyzed. A total of 165 eyes of 165 patients were included in the analysis. Significant progression of VF defects was observed in 72 eyes of 72 patients (43.6%), while no significant progression was evident in 93 eyes of 93 patients (56.4%). There was significant relationship between the frequency of consecutive deterioration of MD value and MD slope worsening (P<0.0001, Cochran-Armitage trend test). A significant association was observed for MD slope worsening in the eyes with three (odds ratio: 2.1, P=0.0224) and four (odds ratio: 3.6, P=0.0008) consecutive deterioration of MD value in multiple logistic regression analysis, but no significant association in the eyes with two consecutive deterioration (odds ratio: 1.1, P=0.8282). The eyes with VF progression had significantly lower intraocular pressure reduction rate (P<0.01). This retrospective study has shown that three or more consecutive deterioration of MD value might be a predictor to future significant MD slope worsening in OAG.

Integration of data-driven and physically-based methods to assess shallow landslides susceptibility

NASA Astrophysics Data System (ADS)

Lajas, Sara; Oliveira, Sérgio C.; Zêzere, José Luis

2016-04-01

Approaches used to assess shallow landslides susceptibility at the basin scale are conceptually different depending on the use of statistic or deterministic methods. The data-driven methods are sustained in the assumption that the same causes are likely to produce the same effects and for that reason a present/past landslide inventory and a dataset of factors assumed as predisposing factors are crucial for the landslide susceptibility assessment. The physically-based methods are based on a system controlled by physical laws and soil mechanics, where the forces which tend to promote movement are compared with forces that tend to promote resistance to movement. In this case, the evaluation of susceptibility is supported by the calculation of the Factor of safety (FoS), and dependent of the availability of detailed data related with the slope geometry and hydrological and geotechnical properties of the soils and rocks. Within this framework, this work aims to test two hypothesis: (i) although conceptually distinct and based on contrasting procedures, statistic and deterministic methods generate similar shallow landslides susceptibility results regarding the predictive capacity and spatial agreement; and (ii) the integration of the shallow landslides susceptibility maps obtained with data-driven and physically-based methods, for the same study area, generate a more reliable susceptibility model for shallow landslides occurrence. To evaluate these two hypotheses, we select the Information Value data-driven method and the physically-based Infinite Slope model to evaluate shallow landslides in the study area of Monfalim and Louriceira basins (13.9 km2), which is located in the north of Lisbon region (Portugal). The landslide inventory is composed by 111 shallow landslides and was divide in two independent groups based on temporal criteria (age ≤ 1983 and age > 1983): (i) the modelling group (51 cases) was used to define the weights for each predisposing factor (lithology, land use, slope, aspect, curvature, topographic position index and the slope over area ratio) with the Information Value method and was used also to calibrate the strength parameters (cohesion and friction angle) of the different lithological units considered in the Infinity Slope model; and (ii) the validation group (60 cases) was used to independent validate and define the predictive capacity of the shallow landslides susceptibility maps produced with the Information Value method and the Infinite Slope method. The comparison of both landslide susceptibility maps was supported by: (i) the computation of the Receiver Operator Characteristic (ROC) curves; (ii) the calculation of the Area Under the Curve (AUC); and (iii) the evaluation of the spatial agreement between the landslide susceptibility classes. Finally, the susceptibility maps produced with the Information Value and the Infinite Slope methods are integrated into a single landslide susceptibility map based on a set of integration rules define by cross-validation of the susceptibility classes of both maps and analysis of the corresponding contingency table. This work was supported by the FCT - Portuguese Foundation for Science and Technology and is within the framework of the FORLAND Project. Sérgio Oliveira was funded by a postdoctoral grant (SFRH/BPD/85827/2012) from the Portuguese Foundation for Science and Technology (FCT).

Response effects in the perception of conjunctions of colour and form.

PubMed

Chmiel, N

1989-01-01

Two experiments addressed the question whether visual search for a target defined by a conjunction of colour and form requires a central, serial, attentional process, but detection of a single feature, such as colour, is preattentive, as proposed by the feature-integration theory of attention. Experiment 1 investigated conjunction and feature search using small array sizes of up to five elements, under conditions which precluded eye-movements, in contrast to previous studies. The results were consistent with the theory. Conjunction search showed the effect of adding distractors to the display, the slopes of the curves relating RT to array size were in the approximate ratio of 2:1, consistent with a central, serial search process, exhaustive for absence responses and self-terminating for presence responses. Feature search showed no significant effect of distractors for presence responses. Experiment 2 manipulated the response requirements in conjunction search, using vocal response in a GO-NO GO procedure, in contrast to Experiment 1, which used key-press responses in a YES-NO procedure. Strikingly, presence-response RT was not affected significantly by the number of distractors in the array. The slope relating RT to array size was 3.92. The absence RT slope was 30.56, producing a slope ratio of approximately 8:1. There was no interaction of errors with array size and the presence and absence conditions, implying that RT-error trade-offs did not produce this slope ratio. This result suggests that feature-integration theory is at least incomplete.

Regional comparisons of Vs30 and Spectral Ratio Methods

NASA Astrophysics Data System (ADS)

McNamara, D. E.; Gee, L. S.; Stephenson, W. J.; Odum, J. K.; Williams, R. A.; Hartzell, S.

2013-12-01

Earthquake damage is often increased due to local ground-motion amplification in soft soils and thick basin sediments with factors such as topographic effects and water saturation. Seismic hazard assessments depend on detailed information on local site response and many different methods have been developed to estimate site response. Based on numerous empirical studies, the average shear-wave velocity in the upper 30 m (Vs30) has become the most common means of classifying site conditions and has been adopted in the NEHRP design provisions for new buildings. In general, higher Vs30 values are associated with firm, dense rock and lower levels of ground shaking while lower Vs30 values are associated with softer soils and high site amplification. Vs30 is commonly computed by measuring the time it takes for shear-waves to travel from 30m depth to the surface using either active sources such as explosions or passive ambient noise microtremor sources. Since this approach is limited to locations where active measurements are undertaken, recent methods have sought to approximate Vs30 regionally, such as using topographic slope as a proxy. In this presentation, we compute a standard site response, horizontal-to-vertical spectral ratio (HVSR) using long-term power spectral density statistics of both ambient noise and earthquake signals at permanent and temporary seismic stations. We compare the HVSR results to surface observations of Vs30 and approximations using topographic slope in several different regions including the Eastern United States, St. Louis and the Los Angeles basin. In our comparison of the HVSR results to Vs30, we find that HVSR peak frequency can be used as a proxy for Vs30. Relationships between surface measured Vs30 and HVSR are less scattered than with Vs30 estimated using topographic approximations. In general, higher Vs30 is associated with higher HVSR peak frequency with variations in slope for different regions. We use these regional relationships to estimate NEHRP soil class at over 200 seismic stations in the US.

Precipitation-Frequency and Discharge-Frequency Relations for Basins Less than 32 Square Miles in Kansas

USGS Publications Warehouse

Perry, Charles A.

2008-01-01

Precipitation-frequency and discharge-frequency relations for small drainage basins with areas less than 32 square miles in Kansas were evaluated to reduce the uncertainty of discharge-frequency estimates. Gaged-discharge records were used to develop discharge-frequency equations for the ratio of discharge to drainage area (Q/A) values using data from basins with variable soil permeability, channel slope, and mean annual precipitation. Soil permeability and mean annual precipitation are the dominant basin characteristics in the multiple linear regression analyses. In addition, 28 discharge measurements at ungaged sites by indirect surveying methods and by velocity meters also were used in this analysis to relate precipitation-recurrence interval to discharge-recurrence interval. Precipitation-recurrence interval for each of these discharge measurements were estimated from weather-radar estimates of precipitation and from nearby raingages. Time of concentration for each basin for each of the ungaged sites was computed and used to determine the precipitation-recurrence interval based on precipitation depth and duration. The ratio of discharge/drainage area (Q/A) value for each event was then assigned to that precipitation-recurrence interval. The relation between the ratio of discharge/drainage area (Q/A) and precipitation-recurrence interval for all 28 measured events resulted in a correlation coefficient of 0.79. Using basins less than 5.4 mi2 only, the correlation decreases to 0.74. However, when basins greater than 5.4 and less than 32 mi2 are examined the relation improves to a correlation coefficient of 0.95. There were a sufficient number of discharge and radar-measured precipitation events for both the 5-year (8 events) and the 100-year (11 events) recurrence intervals to examine the effect of basin characteristics on the Q/A values for basins less than 32 mi2. At the 5-year precipitation-/discharge-recurrence interval, channel slope was a significant predictor (r=0.99) of Q/A. Permeability (r=0.68) also had a significant effect on Q/A values for the 5-year recurrence interval. At the 100-year recurrence interval, permeability, channel slope, and mean annual precipitation did not have a significant effect on Q/A; however, time of concentration was a significant factor in determining Q/A for the 100-year events with greater times of concentration resulting in lower Q/A values. Additional high-recurrence interval (5-, 10-, 25-, 50-, and 100-year) precipitation/discharge data are needed to confirm these relations suggested above. Discharge data with attendant basin-wide precipitation data from precipitation-radar estimates provides a unique opportunity to study the effects of basin characteristics on the relation between precipitation recurrence interval and discharge-recurrence interval. Discharge-frequency values from the Q/A equations, the rational method, and the Kansas discharge-frequency equations (KFFE) were compared to 28 measured weather-radar precipitation-/discharge-frequency values. The association between precipitation frequency from weather-radar estimates and the frequency of the resulting discharge was shown in these comparisons. The measured and Q/A equation computed discharges displayed the best equality from low to high discharges of the three methods. Here the slope of the line was nearly 1:1 (y=0.9844x0.9677). Comparisons with the rational method produced a slope greater than 1:1 (y=0.0722x1.235), and the KFFE equations produced a slope less than 1:1 (y=5.9103x0.7475). The Q/A equation standard error of prediction averaged 0.1346 log units for the 5.4-to 32-square-mile group and 0.0944 log units for the less than 5.4-square mile group. The KFFE standard error averaged 0.2107 log units for the less-than-30-square-mile equations. Using the Q/A equations for determining discharge frequency values for ungaged sites thus appears to be a good alternative to the other two methods because of this s

Origin of the bell-like dependence of the DPOAE amplitude on primary frequency ratio

NASA Astrophysics Data System (ADS)

Lukashkin, Andrei N.; Russell, Ian J.

2001-12-01

For low and medium sound pressure levels (SPLs), the amplitude of the distortion product otoacoustic emission (DPOAE) recorded from guinea pigs at the 2f1-f2 frequency is maximal when f2/f1~1.23 and decreases for lower and higher f2/f1 ratios. The high-ratio slope of the DPOAE dependence on the ratio of the primary frequencies might be anticipated since the f1 amplitude at the f2 place is expected to decrease for higher f2/f1 ratios. The low-ratio slope of the dependence at low and medium SPLs of the primaries is actually one slope of a notch. The DPOAE amplitude recovers from the notch when the f2/f1 ratio is further reduced. In two-dimensional space formed by the f2/f1 ratio, and the levels of the primaries, the notch is continuous and has a level-dependent phase transition. The notch is identical to that seen in DPOAE growth functions. Similar notches and phase transitions were observed for high-order and high-frequency DPOAEs. Theoretical analysis reveals that a single saturating nonlinearity is capable of generating similar amplitude notch and phase transition when the f2/f1 ratio is decreased because of the increase in f1 amplitude at the DPOAE generation place (f2 place). The difference between the DPOAE recorded from guinea pigs and humans is discussed in terms of different position of the operating point of the DPOAE generating nonlinearity.

Dispersion and dispersion slope compensation impact on high channel bit rate optical signal transmission degradation

NASA Astrophysics Data System (ADS)

Hamidine, Mahamadou; Yuan, Xiuhua

2011-11-01

In this article a numerical simulation is carried out on a single channel optical transmission system with channel bit rate greater than 40 Gb/s to investigate optical signal degradation due to the impact of dispersion and dispersion slope of both transmitting and dispersion compensating fibers. By independently varying the input signal power and the dispersion slope of both transmitting and dispersion compensating fibers of an optical link utilizing a channel bit rate of 86 Gb/s, a good quality factor (Q factor) is obtained with a dispersion slope compensation ratio change of +/-10% for a faithful transmission. With this ratio change a minimum Q factor of 16 dB is obtained in the presence of amplifier noise figure of 5 dB and fiber nonlinearities effects at input signal power of 5 dBm and 3 spans of 100 km standard single mode fiber with a dispersion (D) value of 17 ps/nm.km.

Near-infrared reddening of extra-galactic giant molecular clouds in a face-on geometry

NASA Astrophysics Data System (ADS)

Kainulainen, J.; Juvela, M.; Alves, J.

2008-04-01

Aims: We describe the near-infrared reddening signature of giant molecular clouds (GMCs) in external galaxies. In particular, we examine the EJ-H and EH-K color excesses and the effective extinction law observed in discrete GMC regions. We also study the effect of the relative scale height of the GMC distribution to the color excesses, and to the observed mass function of GMCs when the masses are derived using color excess as a linear estimator of mass. Methods: We performed Monte Carlo radiative transfer simulations with 3D models of stellar radiation and clumpy dust distributions, resembling a face-on geometry. The scattered light is included in the models, and near-infrared color maps were calculated from the simulated data. We performed the simulations with different scale heights of GMCs and compared the color excesses and attenuation of light in different geometries. We extracted GMCs from the simulated color maps and compared the mass functions to the input mass functions. Results: The effective near-infrared reddening law, i.e. the ratio EJ-H/EH-K, has a value close to unity in GMC regions. The ratio depends significantly on the relative scale height of GMCs, ξ, and for ξ values 0.1...0.75, we find the typical ratios of 0.6...1.1. The effective extinction law turns out to be very flat in GMC regions. We find the ratios of apparent extinctions of AH^a/AKa = 1.35...1.55 and AJ^a/AHa = 1.15. The effect of the scattered flux on the effective reddening law, as well as on the effective extinction law, is significant. Regarding the GMC mass function, we find no correlation between the input and observed slopes of the mass functions. Instead, the observed slope reflects the parameter ξ and the dynamical range of the mass function. As the observed slope depends on the geometric parameters, which are not known, it is not possible to constrain the slope of the mass function using this technique. We estimate that only a fraction of 10...20% of the total mass of GMCs is recovered, if the observed color excess values are transformed to masses using the Galactic reddening law. In the case of individual clouds, the fraction can vary between ~0...50%.

Deployment of a Secondary Concentrator to Increase the Intercept Factor of a Dish with Large Slope Errors

NASA Technical Reports Server (NTRS)

Ortabasi, U.; Gray, E.; Ogallagher, J. J.

1984-01-01

The testing of a hyperbolic trumpet non-imaging secondary concentrator with a parabolic dish having slope errors of about 10 mrad is reported. The trumpet, which has a concentration ratio of 2.1, increased the flux through a 141-mm focal aperture by 72%, with an efficiency of 96%, thus demonstrating its potential for use in tandem with cheap dishes having relatively large slope errors.

Determination of Slope Safety Factor with Analytical Solution and Searching Critical Slip Surface with Genetic-Traversal Random Method

PubMed Central

2014-01-01

In the current practice, to determine the safety factor of a slope with two-dimensional circular potential failure surface, one of the searching methods for the critical slip surface is Genetic Algorithm (GA), while the method to calculate the slope safety factor is Fellenius' slices method. However GA needs to be validated with more numeric tests, while Fellenius' slices method is just an approximate method like finite element method. This paper proposed a new method to determine the minimum slope safety factor which is the determination of slope safety factor with analytical solution and searching critical slip surface with Genetic-Traversal Random Method. The analytical solution is more accurate than Fellenius' slices method. The Genetic-Traversal Random Method uses random pick to utilize mutation. A computer automatic search program is developed for the Genetic-Traversal Random Method. After comparison with other methods like slope/w software, results indicate that the Genetic-Traversal Random Search Method can give very low safety factor which is about half of the other methods. However the obtained minimum safety factor with Genetic-Traversal Random Search Method is very close to the lower bound solutions of slope safety factor given by the Ansys software. PMID:24782679

Accuracy of maximum likelihood and least-squares estimates in the lidar slope method with noisy data.

PubMed

Eberhard, Wynn L

2017-04-01

The maximum likelihood estimator (MLE) is derived for retrieving the extinction coefficient and zero-range intercept in the lidar slope method in the presence of random and independent Gaussian noise. Least-squares fitting, weighted by the inverse of the noise variance, is equivalent to the MLE. Monte Carlo simulations demonstrate that two traditional least-squares fitting schemes, which use different weights, are less accurate. Alternative fitting schemes that have some positive attributes are introduced and evaluated. The principal factors governing accuracy of all these schemes are elucidated. Applying these schemes to data with Poisson rather than Gaussian noise alters accuracy little, even when the signal-to-noise ratio is low. Methods to estimate optimum weighting factors in actual data are presented. Even when the weighting estimates are coarse, retrieval accuracy declines only modestly. Mathematical tools are described for predicting retrieval accuracy. Least-squares fitting with inverse variance weighting has optimum accuracy for retrieval of parameters from single-wavelength lidar measurements when noise, errors, and uncertainties are Gaussian distributed, or close to optimum when only approximately Gaussian.

Determining the average path length of amplified spontaneous emission in a four-level laser near the 1/3 mode-degeneracy cavity configurations

NASA Astrophysics Data System (ADS)

Chen, Ching-Hsu; Lu, Ming-Lun; Tai, Po-Tse

2015-08-01

We determine the average path length ls of amplified spontaneous emission (ASE) by comparing the numerical slope of a straight line with the experimental slope in the graph of the square of relaxation oscillation frequency versus normalized pump ratio. The simple method is applied in an end-pumped Nd:YVO4 laser with the 1/3 mode-degeneracy cavity having the transverse mode spacing equal to 1/3 of the longitudinal mode spacing. We find that ls is larger at the degeneracy than that far from the degeneracy. This result indicates the existence of stronger ASE at the degeneracy, which is confirmed below the threshold. This is because many spontaneous emission photons can undergo amplification not only before escaping from the gain medium but also after leaving the gain medium, owing to cavity reflection. Our method can be applied in the situations where the Auger upconversion effect is absent, weak, or well-known.

The influence of slope-angle ratio on the dynamics of granular flows: insights from laboratory experiments

NASA Astrophysics Data System (ADS)

Sulpizio, R.; Castioni, D.; Rodriguez-Sedano, L. A.; Sarocchi, D.; Lucchi, F.

2016-11-01

Laboratory experiments on granular flows using natural material were carried out in order to investigate the behaviour of granular flows passing over a break in slope. Sensors in the depositional area recorded the flow kinematics, while video footage permitted reconstruction of the deposit formation, which allowed investigation of the deposit shape as a function of the change in slope. We defined the slope-angle ratio as the proportion between slope angle in the depositional area and that of the channel. When the granular flow encounters the break in slope part of the flow front forms a bouncing clast zone due to elastic impact with the expansion box floor. During this process, part of the kinetic energy of the dense granular flow is transferred to elutriating fine ash, which subsequently forms turbulent ash cloud accompanying the granular flow until it comes to rest. Morphometric analysis of the deposits shows that they are all elliptical, with an almost constant minor axis and a variable major axis. The almost constant value of the minor axis relates to the spreading angle of flow at the end of the channel, which resembles the basal friction angle of the material. The variation of the major axis is interpreted to relate to the effect of competing inertial and frictional forces. This effect also reflects the partitioning of centripetal and tangential velocities, which changes as the flow passes over the break in slope. After normalization, morphometric data provided empirical relationships that highlight the dependence of runout from the product of slope-angle ratio and the difference in height between granular material release and deposit. The empirical relationships were tested against the runouts of hot avalanches formed during the 1944 ad eruption at Vesuvius, with differences among actual and calculated values are between 1.7 and 15 %. Velocity measurements of laboratory granular flows record deceleration paths at different breaks in slope. When normalized, the velocity data show third-order polynomial fit, highlighting a complex behaviour involving interplay between inertial and frictional forces. The theoretical velocity decays were tested against the data published for volcaniclastic debris flows of the 5-6 May 1998 event in the Sarno area. The comparison is very good for non-channelized debris flows, with significant differences between actual and calculated velocities for the channelized debris flows.

Ramp-related incidents involving wheeled mobility device users during transit bus boarding/alighting.

PubMed

Frost, Karen L; Bertocci, Gina; Smalley, Craig

2015-05-01

To estimate the prevalence of wheeled mobility device (WhMD) ramp-related incidents while boarding/alighting a public transit bus and to determine whether the frequency of incidents is less when the ramp slope meets the proposed Americans with Disabilities Act (ADA) maximum allowable limit of ≤9.5°. Observational study. Community public transportation. WhMD users (N=414) accessing a public transit bus equipped with an instrumented ramp. Not applicable. Prevalence of boarding/alighting incidents involving WhMD users and associated ramp slopes; factors affecting incidents. A total of 4.6% (n=35) of WhMD users experienced an incident while boarding/alighting a transit bus. Significantly more incidents occurred during boarding (6.3%, n=26) than during alighting (2.2%, n=9) (P<.01), and when the ramp was deployed to street level (mean slope=11.4°) compared with sidewalk level (mean slope=4.2°) (P=.01). The odds ratio for experiencing an incident when the ramp slope exceeded the proposed ADA maximum allowable ramp slope was 5.4 (95% confidence interval, 2.4-12.2; P<.01). The odds ratio for assistance being rendered to board/alight when the ramp slope exceeded the proposed ADA maximum allowable ramp slope was 5.1 (95% confidence interval, 2.9-9.0; P<.01). The findings of this study support the proposed ADA maximum allowable ramp slope of 9.5°. Ramp slopes >9.5° and ramps deployed to street level are associated with a higher frequency of incidents and provision of assistance. Transit agencies should increase awareness among bus operators of the effect kneeling and deployment location (street/sidewalk) have on the ramp slope. In addition, ramp components and the built environment may contribute to incidents. When prescribing WhMDs, skills training must include ascending/descending ramps at slopes encountered during boarding/alighting to ensure safe and independent access to public transit buses. Copyright © 2015 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.

Landslide hazard mapping with selected dominant factors: A study case of Penang Island, Malaysia

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

Tay, Lea Tien; Alkhasawneh, Mutasem Sh.; Ngah, Umi Kalthum

Landslide is one of the destructive natural geohazards in Malaysia. In addition to rainfall as triggering factos for landslide in Malaysia, topographical and geological factors play important role in the landslide susceptibility analysis. Conventional topographic factors such as elevation, slope angle, slope aspect, plan curvature and profile curvature have been considered as landslide causative factors in many research works. However, other topographic factors such as diagonal length, surface area, surface roughness and rugosity have not been considered, especially for the research work in landslide hazard analysis in Malaysia. This paper presents landslide hazard mapping using Frequency Ratio (FR) and themore » study area is Penang Island of Malaysia. Frequency ratio approach is a variant of probabilistic method that is based on the observed relationships between the distribution of landslides and each landslide-causative factor. Landslide hazard map of Penang Island is produced by considering twenty-two (22) landslide causative factors. Among these twenty-two (22) factors, fourteen (14) factors are topographic factors. They are elevation, slope gradient, slope aspect, plan curvature, profile curvature, general curvature, tangential curvature, longitudinal curvature, cross section curvature, total curvature, diagonal length, surface area, surface roughness and rugosity. These topographic factors are extracted from the digital elevation model of Penang Island. The other eight (8) non-topographic factors considered are land cover, vegetation cover, distance from road, distance from stream, distance from fault line, geology, soil texture and rainfall precipitation. After considering all twenty-two factors for landslide hazard mapping, the analysis is repeated with fourteen dominant factors which are selected from the twenty-two factors. Landslide hazard map was segregated into four categories of risks, i.e. Highly hazardous area, Hazardous area, Moderately hazardous area and Not hazardous area. The maps was assessed using ROC (Rate of Curve) based on the area under the curve method (AUC). The result indicates an increase of accuracy from 77.76% (with all 22 factors) to 79.00% (with 14 dominant factors) in the prediction of landslide occurrence.« less

Geomorphometric variability of "monogenetic" volcanic cones: Evidence from Mauna Kea, Lanzarote and experimental cones

NASA Astrophysics Data System (ADS)

Kervyn, M.; Ernst, G. G. J.; Carracedo, J.-C.; Jacobs, P.

2012-01-01

Volcanic cones are the most common volcanic constructs on Earth. Their shape can be quantified using two morphometric ratios: the crater/cone base ratio (W cr/W co) and the cone height/width ratio (H co/W co). The average values for these ratios obtained over entire cone fields have been explained by the repose angle of loose granular material (i.e. scoria) controlling cone slopes. The observed variability in these ratios between individual cones has been attributed to the effect of erosional processes or contrasting eruptive conditions on cone morphometry. Using a GIS-based approach, high spatial resolution Digital Elevation Models and airphotos, two new geomorphometry datasets for cone fields at Mauna Kea (Hawaii, USA) and Lanzarote (Canary Islands, Spain) are extracted and analyzed here. The key observation in these datasets is the great variability in morphometric ratios, even for simple-shape and well-preserved cones. Simple analog experiments are presented to analyze factors influencing the morphometric ratios. The formation of a crater is simulated within an analog cone (i.e. a sand pile) by opening a drainage conduit at the cone base. Results from experiments show that variability in the morphometric ratios can be attributed to variations in the width, height and horizontal offset of the drainage point relative to the cone symmetry axis, to the dip of the underlying slope or to the influence of a small proportion of fine cohesive material. GIS analysis and analog experiments, together with specific examples of cones documented in the field, suggest that the morphometric ratios for well-preserved volcanic cones are controlled by a combination of 1) the intrinsic cone material properties, 2) time-dependent eruption conditions, 3) the local setting, and 4) the method used to estimate the cone height. Implications for interpreting cone morphometry solely as either an age or as an eruption condition indicator are highlighted.

[Geographic variation of seed morphological traits of Picea schrenkiana var. tianschanica in Tianshan Mountains, Xinjiang of Northwest China].

PubMed

Liu, Gui-Feng; Zang, Run-Guo; Liu, Hua; Bai, Zhi-Qiang; Guo, Zhong-Jun; Ding, Yi

2012-06-01

Taking the Picea schrenkiana var. tianschanica forests at three sites with different longitudes (Zhaosu, Tianchi, and Qitai) in Tianshan Mountains as the objects, the cones were collected along an altitudinal gradient to analyze the variation of their seed morphological traits (seed scale length and width, seed scale length/width ratio, seed wing length and width, seed wing length/ width ratio, seed length and width, and seed length/width ratio). All the seed traits except seed width tended to decrease with increasing altitude. The seed traits except seed wing width, seed width, and seed length/width ratio all had significant negative correlations with altitude. Seed scale length and width and seed scale length/width ratio had significant positive correlations with longitude. Seed scale length, seed scale length/width ratio, and seed wing length/width ratio had significant negative correlations with slope degree. No significant correlations were observed between the seed traits except seed wing width and the slope aspect. Altitude was the main factor affecting the seed scale length, seed scale length/width ratio, and seed wing length/width ratio.

Interpretation of recent alpine landscape system evolution using geomorphic mapping and L-band InSAR analyses

NASA Astrophysics Data System (ADS)

Imaizumi, Fumitoshi; Nishiguchi, Takaki; Matsuoka, Norikazu; Trappmann, Daniel; Stoffel, Markus

2018-06-01

Alpine landscapes are typically characterized by inherited features of past glaciations and, for the more recent past, by the interplay of a multitude of types of geomorphic processes, including permafrost creep, rockfalls, debris flows, and landslides. These different processes usually exhibit large spatial and temporal variations in activity and velocity. The understanding of these processes in a wide alpine area is often hindered by difficulties in their surveying. In this study, we attempt to disentangle recent changes in an alpine landscape system using geomorphic mapping and L-band DInSAR analyses (ALOS-PALSAR) in the Zermatt Valley, Swiss Alps. Geomorphic mapping points to a preferential distribution of rock glaciers on north-facing slopes, whereas talus slopes are concentrated on south-facing slopes. Field-based interpretation of ground deformation in rock glaciers and movements in talus slopes correlates well with the ratio of InSAR images showing potential ground deformation. Moraines formed during the Little Ice Age, rock glaciers, and talus slopes on north-facing slopes are more active than landforms on south-facing slopes, implying that the presence of permafrost facilitates the deformation of these geomorphic units. Such deformations of geomorphic units prevail also at the elevation of glacier termini. For rock cliffs, the ratio of images indicating retreat is affected by slope orientation and elevation. Linkages between sediment supply from rock cliffs and sediment transport in torrents are different among tributaries, affected by relative locations between sediment supply areas and the channel network. We conclude that the combined use of field surveys and L-band DInSAR analyses can substantially improve process understanding in steep, high-mountain terrain.

Effect of Soil Roughness on Overland Flow Connectivity at Different Slope Scenarios

NASA Astrophysics Data System (ADS)

Penuela Fernandez, A.; Javaux, M.; Bielders, C.

2013-12-01

Runoff generation, which involves the gradual depression filling and connection of overflowing depressions, is affected by surface roughness and slope. Therefore, quantifying and understanding the effects of surface roughness and slope on overland flow connectivity at the sub-grid scale can potentially improve current hydrological modeling and runoff prediction. However, little work has been conducted on quantifying these effects. This study examines the role of surface roughness on overland flow connectivity at the plot scale at different slopes. For this purpose, standard multi-Gaussian synthetic fields (6 × 6 m) with contrasting surface roughnesses, as defined by the parameters of the variogram (sill and range) of surface elevation, were used. In order to quantify the effects of soil roughness and slope on overland flow connectivity a functional connectivity indicator, so-called the Relative Surface Connection function (Antoine et al., 2009), was applied. This indicator, that represents the ratio of area connected to the outflow boundary (C) in function of the depression storage (DS), is able to capture runoff-relevant connectivity properties. Three parameters characterizing the connectivity function were used to quantify the effects of roughness and slope. These parameters are: C at DS = 0 (CDS=0), connectivity threshold (CT) and maximum depression storage (MDS). Results showed that variations on soil roughness and slope greatly affect the three parameters showing in some cases a clear relationship between structural connectivity and functional connectivity, such as between the ratio sill/range and MDS and between CDS=0 and range. This relationship, described by mathematical expressions, not only allows the quantification and comparison of the effects of soil roughness and slope in overland flow connectivity but also the prediction of these effects by the study of the variogram.

Investigation of complexes tannic acid and myricetin with Fe(III)

NASA Astrophysics Data System (ADS)

Sungur, Şana; Uzar, Atike

2008-01-01

The pH dependence of the complexes was determined by both potentiometric and spectrophotometric studies. Stability constants and stoichiometries of the formed complexes were determined using slope ratio method. Fe(III) was formed complexes with tannic acid of various stoichiometries, which in the 1:1 molar ratio at pH < 3, in the 2:1 molar ratio at pH 3-7 and in the 4:1 molar ratio at pH > 7. Fe(III) was formed complexes with myricetin in the 1:2 molar ratio at pH 4 and 5 and in the 1:1 molar ratio at pH 6. Stability constant values were found to be 10 5 to 10 17 and 10 5 to 10 9 for Fe(III)-tannic acid complexes and Fe(III)-myricetin complexes. Both tannic acid and myricetin were possessed minimum affinities to Cu(II) and Zn(II). They had less affinity for Al(III) than for Fe(III).

The Transportation of Debris by Running Water

USGS Publications Warehouse

Gilbert, Grove Karl; Murphy, Edward Charles

1914-01-01

Scope.-The finer debris transported by a stream is borne in suspension. The coarser is swept along the channel bed. The suspended load is readily sampled and estimated, and much is known as to its quantity. The bed load is inaccessible and we are without definite information as to its amount. The primary purpose of the investigation was to learn the laws which control the movement of bed load, and especially to determine how the quantity of load is related to the stream's slope and discharge and to the degree of comminution of the debris. Method.-To this end a laboratory was equipped at Berkeley, Cal., and experiments were performed in which each of the three conditions mentioned was separately varied and the resulting variations of load were observed and measured. Sand and gravel were sorted by sieves into grades of uniform size. Determinate discharges were used. In each experiment a specific load was fed to a stream of specific width and discharge, and measurement was made of the slope to which the stream automatically adjusted its bed so as to enable the current to transport the load. The slope factor.-For each combination of discharge, width, and grade of debris there is a slope, called competent slope, which limits transportation. With lower slopes there is no load, or the stream has no capacity for load. With higher slopes capacity exists; and increase of slope gives increase of capacity. The value of capacity is approximately proportional to a power of the excess of slope above competent slope. If S equal the stream's slope and sigma equal competent slope, then the stream's capacity varies as (S - sigma)n. This is not a deductive, but an empiric law. The exponent n has not a fixed value, but an indefinite series of values depending on conditions. Its range of values in the experience of the laboratory is from 0.93 to 2.37, the values being greater as the discharges are smaller or the debris is coarser. The discharge factor.-For each combination of width, slope, and grade of debris there is a competent discharge, k. Calling the stream's discharge Q, the stream's capacity varies as (Q - k)o. The observed range of values for o is from 0.81 to 1.24, the values being greater as the slopes are smaller or the debris is coarser. Under like conditions o is less than n; or, in other words, capacity is less sensitive to change3 of discharge than to changes of slope. The fineness factor.-For each combination of width, slope, and discharge there is a limiting fineness of debris below which no transportation takes place. Calling fineness (or degree of comminution) F and competent fineness o, the stream's capacity varies with (F - o)p. The observed range of values for p is from 0.50 to 0.62, the values being greater as slopes and discharges are smaller. Capacity is less sensitive to changes in fineness of debris than to changes in discharge or slope. The form factor.-Most of the experiments were with straight channels. A few with crooked channels yielded nearly the same estimates of capacity. The ratio of depth to width is a more important factor. For any combination of slope, discharge, and fineness it is possible to reduce capacity to zero by making the stream very wide and shallow or very narrow and deep. Between these extremes is a particular ratio of depth to width, p, corresponding to a maximum capacity. The values of p range, under laboratory conditions, from 0.5 to 0.04, being greater as slope, discharge, and fineness are less. Velocity.-The velocity which determines capacity for bed load is that near the stream's bed, but attempts to measure bed velocity were not successful. Mean velocity was measured instead. To make a definite comparison between capacity and mean velocity it is necessary to postulate constancy in some accessory condition. If slope be the constant, in which case velocity changes with discharge, capacity varies on the average with the 3.2 power of velocity. If discharge be the constant, in w

Experimental study of the effect of grain sizes in a bimodal mixture on bed slope, bed texture, and the transition to washload

NASA Astrophysics Data System (ADS)

Hill, Kimberly M.; Gaffney, John; Baumgardner, Sarah; Wilcock, Peter; Paola, Chris

2017-01-01

When fine sediment is added to a coarse-grained system, the mobility and composition of the bed can change dramatically. We conducted a series of flume experiments to determine how the size of fine particles introduced to an active gravel bed influences the mobility and composition of the bed. We initiated our experiments using a constant water discharge and feed rate of gravel. After the system reached steady state, we doubled the feed rate by supplying a second sediment of equal or lesser size, creating size ratios from 1:1 to 1:150. As we decreased the relative size of the fine particles, the system transitioned among three regimes: (1) For particle size ratios close to one, the bed slope increased to transport the additional load of similar-sized particles. The bed surface remained planar and unchanged. (2) For intermediate particle size ratios, the bed slope decreased with the additional fines. The bed surface became patchy with regions of fine and coarse grains. (3) For the largest particle size ratios (the smallest fines), the bed slope remained relatively unchanged. The subsurface became clogged with fine sediment, but fine particles were not present in the surface layer. This third regime constitutes washload, defined by those fractions that do not affect bed-material transport conditions. Our results indicate washload should be defined in terms of three conditions: small grain size relative to that of the bed material, full suspension based on the Rouse number, and a small rate of fine sediment supply relative to transport capacity.

C:N:P Molar Ratios, Sources and 14C Dating of Surficial Sediments from the NW Slope of Cuba

PubMed Central

de la Lanza Espino, Guadalupe; Soto, Luis A.

2015-01-01

The surficial sediments recovered from 12 sites located near the channel axis of the Florida Straits and the lower slope off NW Cuba were analyzed for total organic carbon (TOC), nitrogen (TN), phosphorus (TP), elemental C:N:P ratios, C and N isotopic values, and 14C dating. The depth profiles of TOC, TN, and TP (0-18 cm) displayed a downcore trend and a significant variation. The TOC values were low (0.15 to 0.62%; 66 to 516 µmol g-1). Sites near the island’s lower slope had lower TOC average concentrations (158-333 µmol g-1) than those closer to the channel axis (averaging 341-516 µmol g-1; p <0.05). The TN concentrations near the lower slope attained 0.11% (80 µmol g-1), whereas, towards the channel axis, they decreased to 0.07% (55 µmol g-1; p<0.05). The C:N ratios ranged from 1.9 to 10.2. The mean molar C:N ratio (5.4) indicated a marine hemipelagic deposition. The TP was lower at sites near the lower slope (38.4 to 50.0 µmol g-1; 0.12% to 0.16%) than those near the channel axis (50.0 to 66 µmol g-1; 0.15 to 0.21%). C:P fluctuated from 7.7 to 14.1 in the surficial sediment layer. The bulk organic δ13Corg and δ15N values confirmed pelagic organic sources, and the 14C dating revealed that the sediments were deposited during the Holocene (1000-5000 yr BP). We suggest that the hydrodynamic conditions in the Straits influence vertical and advective fluxes of particulate organic material trapped in the mixed-layer, which reduces the particulate matter flux to the seabed. PMID:26110791

Multigrid preconditioned conjugate-gradient method for large-scale wave-front reconstruction.

PubMed

Gilles, Luc; Vogel, Curtis R; Ellerbroek, Brent L

2002-09-01

We introduce a multigrid preconditioned conjugate-gradient (MGCG) iterative scheme for computing open-loop wave-front reconstructors for extreme adaptive optics systems. We present numerical simulations for a 17-m class telescope with n = 48756 sensor measurement grid points within the aperture, which indicate that our MGCG method has a rapid convergence rate for a wide range of subaperture average slope measurement signal-to-noise ratios. The total computational cost is of order n log n. Hence our scheme provides for fast wave-front simulation and control in large-scale adaptive optics systems.

Zonal wavefront reconstruction in quadrilateral geometry for phase measuring deflectometry

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

Huang, Lei; Xue, Junpeng; Gao, Bo

2017-06-14

There are wide applications for zonal reconstruction methods in slope-based metrology due to its good capability of reconstructing the local details on surface profile. It was noticed in the literature that large reconstruction errors occur when using zonal reconstruction methods designed for rectangular geometry to process slopes in a quadrilateral geometry, which is a more general geometry with phase measuring deflectometry. In this paper, we present a new idea for the zonal methods for quadrilateral geometry. Instead of employing the intermediate slopes to set up height-slope equations, we consider the height increment as a more general connector to establish themore » height-slope relations for least-squares regression. The classical zonal methods and interpolation-assisted zonal methods are compared with our proposal. Results of both simulation and experiment demonstrate the effectiveness of the proposed idea. In implementation, the modification on the classical zonal methods is addressed. Finally, the new methods preserve many good aspects of the classical ones, such as the ability to handle a large incomplete slope dataset in an arbitrary aperture, and the low computational complexity comparable with the classical zonal method. Of course, the accuracy of the new methods is much higher when integrating the slopes in quadrilateral geometry.« less

Alpha-Fetoprotein Slope >7.5 ng/mL per Month Predicts Microvascular Invasion and Tumor Recurrence After Liver Transplantation for Hepatocellular Carcinoma.

PubMed

Giard, Jeanne-Marie; Mehta, Neil; Dodge, Jennifer L; Roberts, John P; Yao, Francis Y

2018-05-01

Rising alpha-fetoprotein (AFP) is a potential marker of worse prognosis after liver transplant (LT) for hepatocellular carcinoma (HCC), but prior studies relied on only 2 data points and were imprecise in assessing AFP slope. The aim of this study was to examine the association between AFP slope and post-LT HCC recurrence, with AFP slope estimated from multiple data points over time. Our cohort included 336 patients undergoing LT with Model for End Stage Liver Disease exception for HCC within Milan criteria from 2003 to 2013. Most (98%) had pre-LT locoregional therapy. AFP slope was estimated by fitting a regression line to the AFP levels over time. The 1- and 5-year post-LT survivals were 94% and 77% and 1- and 5-year recurrence-free probabilities were 95% and 86%, respectively. In univariate analysis, HCC recurrence was significantly associated with microvascular invasion (hazard ratio [HR], 13.1; P<0.001), tumor grade (HR, 1.8; P<0.001), pathologic stage >Milan criteria (HR, 8.9; P<0.001), 3 tumor nodules (HR, 5.5; P=0.002), AFP slope greater than 7.5 ng/mL per month (HR, 3.9; P=0.005), and female sex (HR, 2.3; P=0.01). In multivariable analysis of factors known before LT, 3 tumor nodules (HR, 7.6; P<0.001), female sex (HR, 2.5; P=0.01), and AFP slope >7.5 (HR, 3.0; P=0.03) were significantly associated with HCC recurrence. AFP slope greater than 7.5 was also associated with microvascular invasion (odds ratio, 6.8; P=0.008). AFP slope increasing greater than 7.5 ng/mL per month despite locoregional therapy is associated with post-LT HCC recurrence and may serve as a surrogate for microvascular invasion. These findings support incorporating changes in the AFP into candidate selection for LT.

Physics of Gate Modulated Resonant Tunneling (RT)-FETs: Multi-barrier MOSFET for steep slope and high on-current

NASA Astrophysics Data System (ADS)

Afzalian, Aryan; Colinge, Jean-Pierre; Flandre, Denis

2011-05-01

A new concept of nanoscale MOSFET, the Gate Modulated Resonant Tunneling Transistor (RT-FET), is presented and modeled using 3D Non-Equilibrium Green's Function simulations enlightening the main physical mechanisms. Owing to the additional tunnel barriers and the related longitudinal confinement present in the device, the density of state is reduced in its off-state, while remaining comparable in its on-state, to that of a MOS transistor without barriers. The RT-FET thus features both a lower RT-limited off-current and a faster increase of the current with V G, i.e. an improved slope characteristic, and hence an improved Ion/ Ioff ratio. Such improvement of the slope can happen in subthreshold regime, and therefore lead to subthreshold slope below the kT/q limit. In addition, faster increase of current and improved slope occur above threshold and lead to high thermionic on-current and significant Ion/ Ioff ratio improvement, even with threshold voltage below 0.2 V and supply voltage V dd of a few hundreds of mV as critically needed for future technology nodes. Finally RT-FETs are intrinsically immune to source-drain tunneling and are therefore promising candidate for extending the roadmap below 10 nm.

[Impact of Land Utilization Pattern on Distributing Characters of Labile Organic Carbon in Soil Aggregates in Jinyun Mountain].

PubMed

Li, Rui; Jiang, Chang-sheng; Hao, Qing-ju

2015-09-01

Four land utilization patterns were selected for this study in Jinyun mountain, including subtropical evergreen broad-leaved forest (abbreviation: forest), sloping farmland, orchard and abandoned land. Soil samples were taken every 10 cm in the depth of 60 cm soil and proportions of large macroaggregates (> 2 mm), small macroaggregates (0. 25-2 mm), microaggregates (0. 053 - 0. 25 mm) and silt + clay (<0. 053 mm) were obtained by wet sieving method to measure the content of organic carbon and labile organic carbon in each aggregate fraction and analyze impacts of land uses on organic carbon and labile organic carbon of soil aggregates. LOC content of four soil aggregates were significantly reduced with the increase of soil depth; in layers of 0-60 cm soil depth, our results showed that LOC contents of forest and abandoned land were higher than orchard and sloping farmland. Reserves of labile organic carbon were estimated by the same soil quality, it revealed that forest (3. 68 Mg.hm-2) > abandoned land (1. 73 Mg.hm-2) > orchard (1. 43 Mg.hm-2) >sloping farmland (0.54 Mg.hm-2) in large macroaggregates, abandoned land (7.77, 5. 01 Mg.hm-2) > forest (4. 96, 2.71 Mg.hm-2) > orchard (3. 33, 21. 10 Mg.hm-2) > sloping farmland (1. 68, 1. 35 Mg.hm-2) in small macroaggregates and microaggregates, and abandoned land(4. 32 Mg.hm-2) > orchard(4. 00 Mg.hm-2) > forest(3. 22 Mg.hm-2) > sloping farmland (2.37 Mg.hm-2) in silt + clay, forest and abandoned land were higher than orchard and sloping farmland in other three soil aggregates except silt + clay. It was observed that the level of organic carbon and labile organic carbon were decreased when bringing forest under cultivation to orchard or farmland, and augments on organic carbon and labile organic carbon were found after exchanging farmland to abandoned land. The most reverses of forest and abandoned land emerged in small macroaggregates, orchard and sloping farmland were in microaggregates. That was, during the transformations of land utilization pattern, soil aggregates with bigger size were easier to accumulate or lose labile organic carbon. Allocation ratios of labile organic carbon to soil organic carbon under four land uses were decreased as the soil depth added. Allocation ratios of orchard and sloping farmland were a bit higher than forest and abandoned land, which indicated that organic carbon of forest and abandoned land were more steady and available for soil as a carbon sink, meanwhile, the forest and abandoned land would avoid more CO2 diffusing to the atmosphere from the decomposition of soil organic carbon.

Evaluation of Thermoelectric Devices by the Slope-Efficiency Method

DTIC Science & Technology

2016-09-01

ARL-TR-7837 ● SEP 2016 US Army Research Laboratory Evaluation of Thermoelectric Devices by the Slope-Efficiency Method by...Evaluation of Thermoelectric Devices by the Slope-Efficiency Method by Patrick J Taylor Sensors and Electron Devices Directorate, ARL Jay R...

Relation of perceived breathiness to laryngeal kinematics and acoustic measures based on computational modeling

PubMed Central

Samlan, Robin A.; Story, Brad H.; Bunton, Kate

2014-01-01

Purpose To determine 1) how specific vocal fold structural and vibratory features relate to breathy voice quality and 2) the relation of perceived breathiness to four acoustic correlates of breathiness. Method A computational, kinematic model of the vocal fold medial surfaces was used to specify features of vocal fold structure and vibration in a manner consistent with breathy voice. Four model parameters were altered: vocal process separation, surface bulging, vibratory nodal point, and epilaryngeal constriction. Twelve naïve listeners rated breathiness of 364 samples relative to a reference. The degree of breathiness was then compared to 1) the underlying kinematic profile and 2) four acoustic measures: cepstral peak prominence (CPP), harmonics-to-noise ratio, and two measures of spectral slope. Results Vocal process separation alone accounted for 61.4% of the variance in perceptual rating. Adding nodal point ratio and bulging to the equation increased the explained variance to 88.7%. The acoustic measure CPP accounted for 86.7% of the variance in perceived breathiness, and explained variance increased to 92.6% with the addition of one spectral slope measure. Conclusions Breathiness ratings were best explained kinematically by the degree of vocal process separation and acoustically by CPP. PMID:23785184

30 CFR 56.3130 - Wall, bank, and slope stability.

Code of Federal Regulations, 2010 CFR

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Wall, bank, and slope stability. 56.3130... Mining Methods § 56.3130 Wall, bank, and slope stability. Mining methods shall be used that will maintain wall, bank, and slope stability in places where persons work or travel in performing their assigned...

A Study on Project Priority Evaluation Method on Road Slope Disaster Prevention Management

NASA Astrophysics Data System (ADS)

Sekiguchi, Nobuyasu; Ohtsu, Hiroyasu; Izu, Ryuutarou

To improve the safety and security of driving while coping with today's stagnant economy and frequent natural disasters, road slopes should be appropriately managed. To achieve the goals, road managers should establish project priority evaluation methods for each stage of road slope management by clarifying social losses that would result by drops in service levels. It is important that road managers evaluate a project priority properly to manage the road slope effectively. From this viewpoint, this study proposed "project priority evaluation methods" in road slope disaster prevention, which use available slope information at each stage of road slope management under limited funds. In addition, this study investigated the effect of managing it from the high slope of the priority by evaluating a risk of slope failure. In terms of the amount of available information, staged information provision is needed ranging from macroscopic studies, which involves evaluation of the entire route at each stage of decision making, to semi- and microscopic investigations for evaluating slopes, and microscopic investigations for evaluating individual slopes. With limited funds, additional detailed surveys are difficult to perform. It is effective to use the slope risk assessment system, which was constructed to complement detailed data, to extract sites to perform precise investigations.

Laser reflection method for determination of shear stress in low density transitional flows

NASA Astrophysics Data System (ADS)

Sathian, Sarith P.; Kurian, Job

2006-03-01

The details of laser reflection method (LRM) for the determination of shear stress in low density transitional flows are presented. The method is employed to determine the shear stress due to impingement of a low density supersonic free jet issuing out from a convergent divergent nozzle on a flat plate. The plate is smeared with a thin oil film and kept parallel to the nozzle axis. For a thin oil film moving under the action of aerodynamic boundary layer, the shear stress at the air-oil interface is equal to the shear stress between the surface and air. A direct and dynamic measurement of the oil film slope generated by the shear force is done using a position sensing detector (PSD). The thinning rate of the oil film is directly measured which is the major advantage of the LRM. From the oil film slope history, calculation of the shear stress is done using a three-point formula. The range of Knudsen numbers investigated is from 0.028 to 0.516. Pressure ratio across the nozzle varied from 3,500 to 8,500 giving highly under expanded free jets. The measured values of shear, in the overlapping region of experimental parameters, show fair agreement with those obtained by force balance method and laser interferometric method.

Parametric Net Influx Rate Images of 68Ga-DOTATOC and 68Ga-DOTATATE: Quantitative Accuracy and Improved Image Contrast.

PubMed

Ilan, Ezgi; Sandström, Mattias; Velikyan, Irina; Sundin, Anders; Eriksson, Barbro; Lubberink, Mark

2017-05-01

68 Ga-DOTATOC and 68 Ga-DOTATATE are radiolabeled somatostatin analogs used for the diagnosis of somatostatin receptor-expressing neuroendocrine tumors (NETs), and SUV measurements are suggested for treatment monitoring. However, changes in net influx rate ( K i ) may better reflect treatment effects than those of the SUV, and accordingly there is a need to compute parametric images showing K i at the voxel level. The aim of this study was to evaluate parametric methods for computation of parametric K i images by comparison to volume of interest (VOI)-based methods and to assess image contrast in terms of tumor-to-liver ratio. Methods: Ten patients with metastatic NETs underwent a 45-min dynamic PET examination followed by whole-body PET/CT at 1 h after injection of 68 Ga-DOTATOC and 68 Ga-DOTATATE on consecutive days. Parametric K i images were computed using a basis function method (BFM) implementation of the 2-tissue-irreversible-compartment model and the Patlak method using a descending aorta image-derived input function, and mean tumor K i values were determined for 50% isocontour VOIs and compared with K i values based on nonlinear regression (NLR) of the whole-VOI time-activity curve. A subsample of healthy liver was delineated in the whole-body and K i images, and tumor-to-liver ratios were calculated to evaluate image contrast. Correlation ( R 2 ) and agreement between VOI-based and parametric K i values were assessed using regression and Bland-Altman analysis. Results: The R 2 between NLR-based and parametric image-based (BFM) tumor K i values was 0.98 (slope, 0.81) and 0.97 (slope, 0.88) for 68 Ga-DOTATOC and 68 Ga-DOTATATE, respectively. For Patlak analysis, the R 2 between NLR-based and parametric-based (Patlak) tumor K i was 0.95 (slope, 0.71) and 0.92 (slope, 0.74) for 68 Ga-DOTATOC and 68 Ga-DOTATATE, respectively. There was no bias between NLR and parametric-based K i values. Tumor-to-liver contrast was 1.6 and 2.0 times higher in the parametric BFM K i images and 2.3 and 3.0 times in the Patlak images than in the whole-body images for 68 Ga-DOTATOC and 68 Ga-DOTATATE, respectively. Conclusion: A high R 2 and agreement between NLR- and parametric-based K i values was found, showing that K i images are quantitatively accurate. In addition, tumor-to-liver contrast was superior in the parametric K i images compared with whole-body images for both 68 Ga-DOTATOC and 68 Ga DOTATATE. © 2017 by the Society of Nuclear Medicine and Molecular Imaging.

Computerized margin and texture analyses for differentiating bacterial pneumonia and invasive mucinous adenocarcinoma presenting as consolidation.

PubMed

Koo, Hyun Jung; Kim, Mi Young; Koo, Ja Hwan; Sung, Yu Sub; Jung, Jiwon; Kim, Sung-Han; Choi, Chang-Min; Kim, Hwa Jung

2017-01-01

Radiologists have used margin characteristics based on routine visual analysis; however, the attenuation changes at the margin of the lesion on CT images have not been quantitatively assessed. We established a CT-based margin analysis method by comparing a target lesion with normal lung attenuation, drawing a slope to represent the attenuation changes. This approach was applied to patients with invasive mucinous adenocarcinoma (n = 40) or bacterial pneumonia (n = 30). Correlations among multiple regions of interest (ROIs) were obtained using intraclass correlation coefficient (ICC) values. CT visual assessment, margin and texture parameters were compared for differentiating the two disease entities. The attenuation and margin parameters in multiple ROIs showed excellent ICC values. Attenuation slopes obtained at the margins revealed a difference between invasive mucinous adenocarcinoma and pneumonia (P<0.001), and mucinous adenocarcinoma produced a sharply declining attenuation slope. On multivariable logistic regression analysis, pneumonia had an ill-defined margin (odds ratio (OR), 4.84; 95% confidence interval (CI), 1.26-18.52; P = 0.02), ground-glass opacity (OR, 8.55; 95% CI, 2.09-34.95; P = 0.003), and gradually declining attenuation at the margin (OR, 12.63; 95% CI, 2.77-57.51, P = 0.001). CT-based margin analysis method has a potential to act as an imaging parameter for differentiating invasive mucinous adenocarcinoma and bacterial pneumonia.

Capnogram slope and ventilation dead space parameters: comparison of mainstream and sidestream techniques.

PubMed

Balogh, A L; Petak, F; Fodor, G H; Tolnai, J; Csorba, Z; Babik, B

2016-07-01

Capnography may provide useful non-invasive bedside information concerning heterogeneity in lung ventilation, ventilation-perfusion mismatching and metabolic status. Although the capnogram may be recorded by mainstream and sidestream techniques, the capnogram indices furnished by these approaches have not previously been compared systematically. Simultaneous mainstream and sidestream time and volumetric capnography was performed in anaesthetized, mechanically ventilated patients undergoing elective heart surgery. Time capnography was used to assess the phase II (SII,T) and III slopes (SIII,T). The volumetric method was applied to estimate phase II (SII,V) and III slopes (SIII,V), together with the dead space values according to the Fowler (VDF), Bohr (VDB), and Enghoff (VDE) methods and the volume of CO2 eliminated per breath ([Formula: see text]). The partial pressure of end-tidal CO2 ([Formula: see text]) was registered. Excellent correlation and good agreement were observed in SIII,T measured by the mainstream and sidestream techniques [ratio=1.05 (sem 0.16), R(2)=0.92, P<0.0001]. Although the sidestream technique significantly underestimated [Formula: see text] and overestimated SIII,V [1.32 (0.28), R(2)=0.93, P<0.0001], VDF, VDB, and VDE, the agreement between the mainstream and sidestream techniques in the difference between VDE and VDB, reflecting the intrapulmonary shunt, was excellent [0.97 (0.004), R(2)=0.92, P<0.0001]. The [Formula: see text] exhibited good correlation and mild differences between the mainstream and sidestream approaches [0.025 (0.005) kPa]. Sidestream capnography provides adequate quantitative bedside information about uneven alveolar emptying and ventilation-perfusion mismatching, because it allows reliable assessments of the phase III slope, [Formula: see text] and intrapulmonary shunt. Reliable measurement of volumetric parameters (phase II slope, dead spaces, and eliminated CO2 volumes) requires the application of a mainstream device. © The Author 2016. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Slope angle estimation method based on sparse subspace clustering for probe safe landing

NASA Astrophysics Data System (ADS)

Li, Haibo; Cao, Yunfeng; Ding, Meng; Zhuang, Likui

2018-06-01

To avoid planetary probes landing on steep slopes where they may slip or tip over, a new method of slope angle estimation based on sparse subspace clustering is proposed to improve accuracy. First, a coordinate system is defined and established to describe the measured data of light detection and ranging (LIDAR). Second, this data is processed and expressed with a sparse representation. Third, on this basis, the data is made to cluster to determine which subspace it belongs to. Fourth, eliminating outliers in subspace, the correct data points are used for the fitting planes. Finally, the vectors normal to the planes are obtained using the plane model, and the angle between the normal vectors is obtained through calculation. Based on the geometric relationship, this angle is equal in value to the slope angle. The proposed method was tested in a series of experiments. The experimental results show that this method can effectively estimate the slope angle, can overcome the influence of noise and obtain an exact slope angle. Compared with other methods, this method can minimize the measuring errors and further improve the estimation accuracy of the slope angle.

The Stability Analysis Method of the Cohesive Granular Slope on the Basis of Graph Theory.

PubMed

Guan, Yanpeng; Liu, Xiaoli; Wang, Enzhi; Wang, Sijing

2017-02-27

This paper attempted to provide a method to calculate progressive failure of the cohesivefrictional granular geomaterial and the spatial distribution of the stability of the cohesive granular slope. The methodology can be divided into two parts: the characterization method of macro-contact and the analysis of the slope stability. Based on the graph theory, the vertexes, the edges and the edge sequences are abstracted out to characterize the voids, the particle contact and the macro-contact, respectively, bridging the gap between the mesoscopic and macro scales of granular materials. This paper adopts this characterization method to extract a graph from a granular slope and characterize the macro sliding surface, then the weighted graph is analyzed to calculate the slope safety factor. Each edge has three weights representing the sliding moment, the anti-sliding moment and the braking index of contact-bond, respectively, . The safety factor of the slope is calculated by presupposing a certain number of sliding routes and reducing Weight repeatedly and counting the mesoscopic failure of the edge. It is a kind of slope analysis method from mesoscopic perspective so it can present more detail of the mesoscopic property of the granular slope. In the respect of macro scale, the spatial distribution of the stability of the granular slope is in agreement with the theoretical solution.

Kaon-nucleus scattering

NASA Technical Reports Server (NTRS)

Hong, Byungsik; Buck, Warren W.; Maung, Khin M.

1989-01-01

Two kinds of number density distributions of the nucleus, harmonic well and Woods-Saxon models, are used with the t-matrix that is taken from the scattering experiments to find a simple optical potential. The parameterized two body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to imaginary part of the forward elastic scattering amplitude, are shown. The eikonal approximation was chosen as the solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

Measurement precision of the anaerobic threshold by means of a portable calorimeter.

PubMed

Nogueira, Fernando dos Santos; Pompeu, Fernando Augusto Monteiro Sabóia

2010-09-01

Many methods are used for determining the Anaerobic Threshold (AT) by means of sophisticated ergospirometer. To test the AT variation, detected by mathematical models and visual inspection, when low cost ergospirometer is used and intended for clinical application. Seventy nine apparently healthy subjects were volunteers in this study; from these, 57 men. The VO₂(max) and the ventilatory threshold were determined by indirect, open-circuit calorimetry. The electro-enzymatic method was used for analyzing the lactacidemia and direct determination of the Lactate Threshold (LT). The AT was determined by two mathematical methods (MM(RSS) and MM(slope)), based on the gases exchange, and by the log-log visual method, for determining the LT. Two independent investigators determined the AT through visual inspection of three graphs, considering two methods (AT₋(a)= V-slope, EqV; and AT₋(b) = V-slope, EqV and ExCO₂). The data were analyzed by means of parametric statistics for determining the differences between AT₋(a) versus ExCO₂, MM(RSS) and MM(slope); AT-b versus MM(RSS) and MM(slope); and LT versus AT₋(a), AT₋(b), MM(RSS) and MM(slope). The MM(slope) was the only method that presented a significant difference between the AT₋(a) and AT₋(b) (p=0.001), with CV% >15. LT versus MM(slope) did not present significant difference (p=0.274), however, it was observed a high CV (24%). It was concluded that with the low cost equipment, the MM(RSS) and AT₋(a) methods can be used for determining the TAn. The MM(slope) method did not present satisfactory precision to be employed with this equipment.

Comparison of methods for removing electromagnetic noise from electromyographic signals.

PubMed

Defreitas, Jason M; Beck, Travis W; Stock, Matt S

2012-02-01

The purpose of this investigation was to compare three different methods of removing noise from monopolar electromyographic (EMG) signals: (a) electrical shielding with a Faraday cage, (b) denoising with a digital notch-filter and (c) applying a bipolar differentiation with another monopolar EMG signal. Ten men and ten women (mean age = 24.0 years) performed isometric muscle actions of the leg extensors at 10-100% of their maximal voluntary contraction on two separate occasions. One trial was performed inside a Faraday tent (a flexible Faraday cage made from conductive material), and the other was performed outside the Faraday tent. The EMG signals collected outside the Faraday tent were analyzed three separate ways: as a raw signal, as a bipolar signal, and as a signal digitally notch filtered to remove 60 Hz noise and its harmonics. The signal-to-noise ratios were greatest after notch-filtering (range: 3.0-33.8), and lowest for the bipolar arrangement (1.6-10.2). Linear slope coefficients for the EMG amplitude versus force relationship were also used to compare the methods of noise removal. The results showed that a bipolar arrangement had a significantly lower linear slope coefficient when compared to the three other conditions (raw, notch and tent). These results suggested that an appropriately filtered monopolar EMG signal can be useful in situations that require a large pick-up area. Furthermore, although it is helpful, a Faraday tent (or cage) is not required to achieve an appropriate signal-to-noise ratio, as long as the correct filters are applied.

Stress resistance strategy in an arid land shrub: interactions between developmental instability and fractal dimention

USGS Publications Warehouse

Escos, J.; Alados, C.L.; Pugnaire, F. I.; Puigdefábregas, J.; Emlen, J.

2000-01-01

This paper investigates allocation of energy to mechanisms that generate and preserve architectural forms (i.e. developmental stability, complexity of branching patterns) and productivity (growth and reproduction) in response to environmental disturbances (i.e. grazing and resource availability). The statistical error in translational symmetry was used to detect random intra-individual variability during development. This can be thought of as a measure of developmental instability caused by stress. Additionally, we use changes in fractal complexity and shoot distribution of branch structures as an alternate indicator of stress. These methods were applied to Anthyllis cytisoides L., a semi-arid environment shrub, to ascertain the effect of grazing and slope exposure on developmental traits in a 2×2 factorial design. The results show that A. cytisoidesmaintains developmental stability at the expense of productivity. Anthyllis cytisoides was developmentally more stable when grazed and when on south-facing, as opposed to north-facing slopes. On the contrary, shoot length, leaf area, fractal dimension and reproductive-to-vegetative allocation ratio were larger in north- than in south-facing slopes. As a consequence, under extreme xeric conditions, shrub mortality increased in north-facing slopes, especially when not grazed. The removal of transpiring area and the reduction of plant competition favoured developmental stability and survival in grazed plants. Differences between grazed and ungrazed plants were most evident in more mesic (north-facing) areas.

Characterisation of slope directional resonance by analysing ambient noise instantaneous polarisation

NASA Astrophysics Data System (ADS)

Del Gaudio, Vincenzo; Wasowski, Janusz

2014-05-01

Several studies have shown that the dynamic response of landslide prone slopes to seismic shaking can play an important role in failure triggering during earthquakes. It was also demonstrated that slope seismic response is often characterised by directional resonance phenomena. Directivity can be revealed by the analysis of ambient noise recordings according to a technique known as HVNR method based on the analysis of azimuthal variation of spectral ratios between the spectral amplitude of horizontal H and vertical V component of noise recording. Directional resonance is then revealed by the presence of a preferential polarisation of H/V ratio peaks, whose frequencies correspond to resonance frequencies and whose amplitudes depend on the impedance contrast between surface material and bedrock. H/V ratio amplitudes can potentially provide information also on amplification factors. However, the relation is not straightforward depending on the nature of the waves contributing to the ambient noise. Thus, it is desirable to distinguish different kinds of noise wave packets, possibly isolating the contribution of Rayleigh waves, which appear to better reflect site response properties. To identify Rayleigh wave packets in noise recording a new approach was tested, based on a technique of analysis of instantaneous polarisation. The results are promising for the investigation of site response directional properties, particularly in the case of complex site conditions, where resonance can be characterised by multiple anisotropic peaks. In our preliminary tests of noise recordings carried out at a site located on a slope affected by landslides, only a small fraction of data samples (in the order of 1 %) were identified as Rayleigh type waves: this was likely due the fact that the noise recording was dominated by an overlapping of signals with different kinds of polarisation. Thus, it was possible to recognise Rayleigh polarisation only when the energy of this kind of wave was prevalent. However, from a relatively short noise recording (in the order of 30-45 minutes) one can obtain a high number (in the order of thousands) of estimates of H/V amplitude and azimuth, providing a robust statistics to recognise ground vibration properties reflecting site response. The tests on sites where directional resonance properties had been verified through the analysis of seismic event recordings, showed that more coherent observations can be obtained for H/V ratios and directivity estimates by selecting Rayleigh type data samples, rather than analysing the entire data set or SH-type wave packets.This offers the possibility of reducing the uncertainties in data interpretation related to the influence of the nature of the noise wavefield.

Laboratory and 3-D distinct element analysis of the failure mechanism of a slope under external surcharge

NASA Astrophysics Data System (ADS)

Li, N.; Cheng, Y. M.

2015-01-01

Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient detail. There is however increasing interest in the consequences after the initiation of failure that includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more detail and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and a laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanisms and the post-failure mechanisms of slopes will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure, which can give additional information not available from the classical methods of analysis.

Laboratory and 3-D-distinct element analysis of failure mechanism of slope under external surcharge

NASA Astrophysics Data System (ADS)

Li, N.; Cheng, Y. M.

2014-09-01

Landslide is a major disaster resulting in considerable loss of human lives and property damages in hilly terrain in Hong Kong, China and many other countries. The factor of safety and the critical slip surface for slope stabilization are the main considerations for slope stability analysis in the past, while the detailed post-failure conditions of the slopes have not been considered in sufficient details. There are however increasing interest on the consequences after the initiation of failure which includes the development and propagation of the failure surfaces, the amount of failed mass and runoff and the affected region. To assess the development of slope failure in more details and to consider the potential danger of slopes after failure has initiated, the slope stability problem under external surcharge is analyzed by the distinct element method (DEM) and laboratory model test in the present research. A more refined study about the development of failure, microcosmic failure mechanism and the post-failure mechanism of slope will be carried out. The numerical modeling method and the various findings from the present work can provide an alternate method of analysis of slope failure which can give additional information not available from the classical methods of analysis.

Coaxially gated in-wire thin-film transistors made by template assembly.

PubMed

Kovtyukhova, Nina I; Kelley, Brian K; Mallouk, Thomas E

2004-10-13

Nanowire field effect transistors were prepared by a wet chemical template replication method using anodic aluminum oxide membranes. The membrane pores were first lined with a thin SiO2 layer by the surface sol-gel method. Au, CdS (or CdSe), and Au wire segments were then sequentially electrodeposited within the pores, and the resulting nanowires were released by dissolution of the membrane. Electrofluidic alignment of these nanowires between source and drain leads and evaporation of gold over the central CdS (CdSe) stripe affords a "wrap-around gate" structure. At VDS = -2 V, the Au/CdS/Au devices had an ON/OFF current ratio of 103, a threshold voltage of 2.4 V, and a subthreshold slope of 2.2 V/decade. A 3-fold decrease in the subthreshold slope relative to that of planar nanocrystalline CdSe devices can be attributed to coaxial gating. The control of dimensions afforded by template synthesis should make it possible to reduce the gate dielectric thickness, channel length, and diameter of the semiconductor segment to sublithographic dimensions while retaining the simplicity of the wet chemical synthetic method.

SU-E-T-130: Dosimetric Evaluation of Tissue Equivalent Gel Dosimeter Using Saccharide in Radiotherapy System

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

Cho, Y; Lee, D; Jung, H

2014-06-01

Purpose: In this study, the dose responses of the MAGIC gel with various concentrations and type of saccharide are examined to clarify the roles of mono and disaccharide in the polymerization process. Then we focused on the tissue equivalence and dose sensitivity of MAGIC gel dosimeters. Methods: The gel is composed of HPLC, 8% gelatin, 2 × 10-3 M L-ascorbic acid, 1.8 × 10-2 M hydroquinone, 8 × 10-5 M copper(II)sulfate and 9% methacrylic acid, new polymer gels are synthesized by adding glucose(monosaccharide), sucrose(disaccharide) and urea in the concentration range of 5∼35%. For irradiation of the gel, cesium-137 gamma-ray irradiatormore » was used, radiation dose was delivered from 5∼50 Gy. MRI images of the gel were acquired by using a 3.0 T MRI system. Results: When saccharide and urea were added, the O/C, O/N and C/N ratios agreed with those of soft tissue with 1.7%. The dose-response of glucose and sucrose gel have slope-to-intercept ratio of 0.044 and 0.283 respectively. The slope-to-ratio is one important determinant of gel sensitivity. R-square values of glucose and sucrose gel dosimeters were 0.984 and 0.994 respectively. Moreover when urea were added, the slope-to-intercept ratio is 0.044 and 0.073 respectively. R-square values of mono and disaccharide gel were 0.973 and 0.989 respectively. When a saccharide is added into the MAGIC gel dosimeter, dose sensitivity is increased. However when urea were added, dose sensitivity is slightly decreased. Conclusion: In this study, it was possible to obtain the following conclusions by looking at the dose response characteristics after adding mono-, di-saccharide and urea to a MAGIC gel dosimeter. Saccharide was a tendency of increasing dose sensitivity with disaccharide. Sa.ccharide is cost effective, safe, soft tissue equivalent, and can be used under various experimental conditions, making it a suitable dosimeter for some radiotherapy applications.« less

A comparison of near-surface potential temperature variance budgets for unstable atmospheric flows over vegetated and non-vegetated flat surfaces and a gentle slope

NASA Astrophysics Data System (ADS)

Hang, C.; Nadeau, D.; Pardyjak, E.; Parlange, M. B.

2017-12-01

Over the past decades, researchers have made much progress toward a fundamental understanding of the budgets of turbulence variables over flat and homogeneous terrain, and only more recently over complex terrain. However, temperature variance budgets, which are parameterized in most meteorological models, are still poorly understood even under relatively idealized conditions. In this work, we rely on near-surface turbulence observations collected as part of the Mountain Terrain Atmospheric Modeling and Observations (MATERHORN) program. Data collected in May 2013 in western Utah at three field sites subjected to similar large-scale forcing are analyzed: a desert playa (dry lakebed), characterized by a at surface devoid of vegetation; a vegetated site, characterized by at valley oor covered with greasewood vegetation, and a mountain terrain site with a slope angle of 2 -4° and covered by high-elevation vegetation. The analysis reveals the presence of a 5-m layer where the production and dissipation terms of potential temperature variance (θ2) drop rapidly below this level. During convective periods, vertical advection and turbulent transport of θ2 can often be non-negligible, in particular at Playa and Slope sites. In addition, within the 5-m layer, turbulent transport of θ2 acts as a sink term at all sites of interest. Neither the ratio of turbulent transport to production nor the ratio of production to dissipation show a stability dependence during the unstable periods studied. A short-period comparison of dissipation rates calculated using dissipation-scale resolving hot-wire/cold-wire anemometry and several common indirect methods using sonic anemometry is presented for data acquired at Playa site. The results indicates that the dissipation rates from all methods follow similar trends, however the magnitudes can differ by a factor of 2 - 3.

The dependence of oxygen and nitrogen abundances on stellar mass from the CALIFA survey

NASA Astrophysics Data System (ADS)

Pérez-Montero, E.; García-Benito, R.; Vílchez, J. M.; Sánchez, S. F.; Kehrig, C.; Husemann, B.; Duarte Puertas, S.; Iglesias-Páramo, J.; Galbany, L.; Mollá, M.; Walcher, C. J.; Ascasíbar, Y.; González Delgado, R. M.; Marino, R. A.; Masegosa, J.; Pérez, E.; Rosales-Ortega, F. F.; Sánchez-Blázquez, P.; Bland-Hawthorn, J.; Bomans, D.; López-Sánchez, Á. R.; Ziegler, B.; Califa Collaboration

2016-10-01

Context. The study of the integrated properties of star-forming galaxies is central to understand their formation and evolution. Some of these properties are extensive and therefore their analysis require totally covering and spatially resolved observations. Among these properties, metallicity can be defined in spiral discs by means of integral field spectroscopy (IFS) of individual H II regions. The simultaneous analysis of the abundances of primary elements, as oxygen, and secondary, as nitrogen, also provides clues about the star formation history and the processes that shape the build-up of spiral discs. Aims: Our main aim is to analyse simultaneously O/H and N/O abundance ratios in H II regions in different radial positions of the discs in a large sample of spiral galaxies to obtain the slopes and the characteristic abundance ratios that can be related to their integrated properties. Methods: We analysed the optical spectra of individual selected H II regions extracted from a sample of 350 spiral galaxies of the CALIFA survey. We calculated total O/H abundances and, for the first time, N/O ratios using the semi-empirical routine Hii-Chi-mistry, which, according to Pérez-Montero (2014, MNRAS, 441, 2663), is consistent with the direct method and reduces the uncertainty in the O/H derivation using [N II] lines owing to the dispersion in the O/H-N/O relation. Then we performed linear fittings to the abundances as a function of the de-projected galactocentric distances. Results: The analysis of the radial distribution both for O/H and N/O in the non-interacting galaxies reveals that both average slopes are negative, but a non-negligible fraction of objects have a flat or even a positive gradient (at least 10% for O/H and 4% for N/O). The slopes normalised to the effective radius appear to have a slight dependence on the total stellar mass and the morphological type, as late low-mass objects tend to have flatter slopes. No clear relation is found, however, to explain the presence of inverted gradients in this sample, and there is no dependence between the average slopes and the presence of a bar. The relation between the resulting O/H and N/O linear fittings at the effective radius is much tighter (correlation coefficient ρs = 0.80) than between O/H and N/O slopes (ρs = 0.39) or for O/H and N/O in the individual H II regions (ρs = 0.37). These O/H and N/O values at the effective radius also correlate very tightly (less than 0.03 dex of dispersion) with total luminosity and stellar mass. The relation with other integrated properties, such as star formation rate, colour, or morphology, can be understood only in light of the found relation with mass. Based on observations collected at the Centro Astronómico Hispano Alemán (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut für Astronomie and the Instituto de Astrofísica de Andalucía (CSIC).Full Table 1 is only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (http://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/595/A62

Quasi-analytical treatment of spatially averaged radiation transfer in complex terrain

NASA Astrophysics Data System (ADS)

Löwe, H.; Helbig, N.

2012-04-01

We provide a new quasi-analytical method to compute the topographic influence on the effective albedo of complex topography as required for meteorological, land-surface or climate models. We investigate radiative transfer in complex terrain via the radiosity equation on isotropic Gaussian random fields. Under controlled approximations we derive expressions for domain averages of direct, diffuse and terrain radiation and the sky view factor. Domain averaged quantities are related to a type of level-crossing probability of the random field which is approximated by longstanding results developed for acoustic scattering at ocean boundaries. This allows us to express all non-local horizon effects in terms of a local terrain parameter, namely the mean squared slope. Emerging integrals are computed numerically and fit formulas are given for practical purposes. As an implication of our approach we provide an expression for the effective albedo of complex terrain in terms of the sun elevation angle, mean squared slope, the area averaged surface albedo, and the direct-to-diffuse ratio of solar radiation. As an application, we compute the effective albedo for the Swiss Alps and discuss possible generalizations of the method.

The Stability Analysis Method of the Cohesive Granular Slope on the Basis of Graph Theory

PubMed Central

Guan, Yanpeng; Liu, Xiaoli; Wang, Enzhi; Wang, Sijing

2017-01-01

This paper attempted to provide a method to calculate progressive failure of the cohesive-frictional granular geomaterial and the spatial distribution of the stability of the cohesive granular slope. The methodology can be divided into two parts: the characterization method of macro-contact and the analysis of the slope stability. Based on the graph theory, the vertexes, the edges and the edge sequences are abstracted out to characterize the voids, the particle contact and the macro-contact, respectively, bridging the gap between the mesoscopic and macro scales of granular materials. This paper adopts this characterization method to extract a graph from a granular slope and characterize the macro sliding surface, then the weighted graph is analyzed to calculate the slope safety factor. Each edge has three weights representing the sliding moment, the anti-sliding moment and the braking index of contact-bond, respectively, E1E2E3E1E2E3. The safety factor of the slope is calculated by presupposing a certain number of sliding routes and reducing Weight E3 repeatedly and counting the mesoscopic failure of the edge. It is a kind of slope analysis method from mesoscopic perspective so it can present more detail of the mesoscopic property of the granular slope. In the respect of macro scale, the spatial distribution of the stability of the granular slope is in agreement with the theoretical solution. PMID:28772596

Nonplanar Method for Predicting Incompressible Aerodynamic Coefficients of Rectangular Wings with Circular-Arc Camber. Ph.D. Thesis - Virginia Polytechnic Institute

NASA Technical Reports Server (NTRS)

Lamar, J. E.

1971-01-01

The development of a nonplanar lifting surface method having a continuous distribution of singularities and satisfying the tangent flow boundary condition on the mean camber surface is given. The method predicts some incompressible longitudinal aerodynamic coefficients of rectangular wings which have circular-arc camber. The solution method is of the integral-equation type and the resulting surface integrals are evaluated by either using numerical or analytical techniques, as are appropriate. Applications are made and the results compared with those from an exact two-dimensional circular-arc camber solution, a three-dimensional flat-wing solution which represents the camber by a projected slope onto the flat surface, and a flat-wing experiment. From these comparisons, the present method is found to predict well the flat-wing experiment and limiting values, in addition to the center of pressure variation at an angle of attack of zero for any camber. For wings having camber ratios larger than about 1.25% and moderate to high aspect ratios, the results deterioriate due to the inadequacy of lifting pressure modes employed.

Relative roughness controls on incipient sediment motion in steep channels

NASA Astrophysics Data System (ADS)

Prancevic, J.; Lamb, M. P.; Fuller, B. M.

2012-12-01

For over eight decades, researchers have noted an appreciable increase in the nondimensional shear stress (Shields number) at initiation of fluvial bedload transport with increasing bed slope. The precise cause of the trend, however, is obscured by the covariance of several factors with increased slope: a greater downstream component of the gravity acting on the grains and fluid, changes in bed morphology, increased grainsize relative to the channel width that may lead to grain bridging, and increased grainsize relative to flow depth (relative roughness) that may change flow hydraulics and particle buoyancy. Here, we report on ongoing laboratory experiments spanning a wide range of bed slopes (2% to 67%) designed to isolate these variables and determine the true cause of heightened critical Shields numbers on steep slopes. First, we eliminated bed morphology as a factor by using only planar beds. To investigate the effect of grain bridging, we used two different channel widths, representing width-to-grainsize ratios of 23:1 and 9:1. Finally, to separate the effects of slope from relative roughness, we compared incipient motion conditions for acrylic particles (submerged specific gravity of 0.15) to natural siliciclastic gravel (submerged specific gravity of 1.65). Different particle densities allowed us to explore incipient motion as a function of relative roughness, independent of channel slope, because lighter particles move at shallower flow depths than heavier ones of the same size. Results show that both materials exhibit a positive trend between bed slope and critical Shields number despite the existence of planar beds for all slopes. Furthermore, changing the grainsize-to-width ratio had a negligible effect on this trend. For all slopes, the critical Shields number for bedload transport was higher for the acrylic particles than for gravel, indicating that relative roughness has a strong control on incipient sediment motion independent of channel slope. These results are consistent with a simple force balance model that considers the effect of relative roughness on flow hydraulics and particle buoyancy, and neglects grain bridging and particle wedging. Together, our results indicate that heightened critical Shields number on steep planar beds is fundamentally due to the increase in relative roughness with increasing slope at the onset of sediment motion.

Aerodynamic Characteristics of Low-Aspect-Ratio Wings in Close Proximity to the Ground

NASA Technical Reports Server (NTRS)

Fink, Marvin P.; Lastinger, James L.

1961-01-01

A wind-tunnel investigation has been conducted to determine the effect of ground proximity on the aerodynamic characteristics of thick highly cambered rectangular wings with aspect ratios of 1. 2, 4, and 6. The results showed that, for these aspect ratios, as the ground war, approached all wings experienced increases in lift-curve slope and reductions in induced drag which resulted in increases in lift-drag ratio. Although an increase in lift-curve slope was obtained for all aspect ratios as the ground was approached, the lift coefficient at an angle of attack of 0 deg for any given aspect ratio remained nearly constant. The experimental results were in general agreement with Wieselsberger's ground-effect theory (NACA Technical Memorandum 77). As the wings approached the ground, there was an increase in static longitudinal stability at positive angles of attack. When operating in ground effect, all the wings had stability of height at positive angles of attack and instability of height at negative angles of attack. Wing-tip fairings on the wings with aspect ratios of 1 and 2 produced small increases in lift-drag ratio in ground effect. End plates extending only below the chord plane on the wing with an aspect ratio of 1 provided increases in lift coefficient and in lift-drag ratio in ground effect.

Rates of total oxygen uptake of sediments and benthic nutrient fluxes measured using an in situ autonomous benthic chamber in the sediment of the slope off the southwestern part of Ulleung Basin, East Sea

NASA Astrophysics Data System (ADS)

Lee, Jae Seong; An, Sung-Uk; Park, Young-Gyu; Kim, Eunsoo; Kim, Dongseon; Kwon, Jung No; Kang, Dong-Jin; Noh, Jae-Hoon

2015-09-01

We have developed a new autonomous benthic lander for deep-sea research, the Korea Institute of Ocean Science and Technology (KIOST) Belc II and Belp II. The benthic lander was successfully tested at 950 and 1450 m water depths on the slope off the southwestern part of the Ulleung Basin in the East Sea of Korea. The ex situ measurements of the total oxygen uptake (TOU) rates at all the stations exceeded the in situ measurement values, and may indicate artificial effects from onboard incubation. The TOU rates were estimated to be 5.80 mmol m-2 d-1 and 3.77 mmol m-2 d-1 at water depths of 950 m and 1450 m, respectively. The benthic nutrient fluxes were also higher at water depths of 950 m, which indicates a partitioning of organic degradation with water depth. In addition, the negative phosphate and nitrogen benthic flux ratios and the higher nitrate removal flux via the sediment-water interface at the slope imply that the nitrogen in the bottom water may be preferentially removed via microbial respiration processes in the sediments, and may be coupled with the low nitrogen-to-phosphate ratio found in the deep water. Although our measurements comprised just two experiments in the slope sediment, the robust in situ measurement of the benthic fluxes in the slope sediment is a forerunner for new research into the biogeochemical cycles across the shelf edge-slope-basin system in the East Sea.

Rates of total oxygen uptake of sediments and benthic nutrient fluxes measured by an in situ autonomous benthic chamber in the sediment of the slope off the southwestern part of Ulleung Basin, East Sea

NASA Astrophysics Data System (ADS)

Lee, J. S.; An, S. U.; Park, Y. G.; Kim, E.; Kim, D.; Kwon, J. N.; Kang, D. J.; Noh, J. H.

2016-02-01

We have developed a new autonomous benthic lander for deep-sea research, the Korea Institute of Ocean Science and Technology (KIOST) BelcII and BelpII. The benthic lander was successfully tested at 950 and 1450 m water depths on the slope off the southwestern part of the Ulleung Basin in the East Sea of Korea. The ex situ measurements of the total oxygen uptake (TOU) rates at all the stations exceeded the in situ measurement values, and may indicate artificial effects from onboard incubation. The TOU rates were estimated to be 5.80 mmol m-2 d-1 and 3.77 mmol m-2 d-1 at water depths of 950 m and 1450 m, respectively. The benthic nutrient fluxes were also higher at water depths of 950 m, which indicates a partitioning of organic degradation with water depth. In addition, the negative phosphate and nitrogen benthic flux ratios and the higher nitrate removal flux via the sediment-water interface at the slope imply that the nitrogen in the bottom water may be preferentially removed via microbial respiration processes in the sediments, and may be coupled with the low nitrogen-to-phosphate ratio found in the deep water. Although our measurements comprised just two experiments in the slope sediment, the robust in situ measurement of the benthic fluxes in the slope sediment is a forerunner for new research into the biogeochemical cycles across the shelf edge- slope-basin system in the East Sea.

Relationships between chlorophyll density and ocean radiance as measured by U2/OCS: Algorithms, examples and comparison

NASA Technical Reports Server (NTRS)

Kim, H. H.; Hart, W. D.

1983-01-01

An ocean atmosphere radiative transfer process computation method which is suitable for determining lower boundary ocean albedo and other radiation components from spectral measurements of upwelling radiance taken from a high altitude platform is described. The method was applied to a set of color scanner data taken from slope water of the South Atlantic Bight to determine the influence of cholorophyll-a pigments in the sea on the ratio of upwelling radiance to down welling irradiance as a function of wavelength. The resulting chlorophyll concentrations are compared with measurements made by ships stationed along the flight path.

Progress in the application of landform analysis in studies of semiarid erosion

USGS Publications Warehouse

Schumm, Stanley Alfred; Hadley, R.F.

1961-01-01

The analysis of topographic and hydrologic data gathered during studies of erosion in semiarid areas of Western United States show the following relation: (a) Mean annual sediment yield from small drainage basins is related to a ratio of basin relief to length; (b) mean annual runoff from small drainage basins is related to drainage density; (c) mean annual sediment yield per unit area decreases with increase in drainage area; (d) the form of some convex hill slopes is related to surficial creep; (e) asymmetry of drainage basins, including differences in hill-slope erosion and drainage density, is related to microclimatic variations on slopes of diverse exposure; .(f) the cutting of discontinuous gullies is closely related to steepening by deposition of the semiarid valley floor; (g) aggradation in ephemeral streams seems to be most prevalent in reaches where the ratio of contributing drainage area to channel length is relatively small; and (h) streamchannel shape, expressed as a width-depth ratio, is related to the percentage of silt-clay in bed and bank alluvium. The above relations cannot be detected without measurement of terrain characteristics. They further indicate the importance of quantitative terrain analysis in studies of erosion.

Dark matter contraction and stellar-mass-to-light ratio gradients in massive early-type galaxies

NASA Astrophysics Data System (ADS)

Oldham, Lindsay J.; Auger, Matthew W.

2018-05-01

We present models for the dark and luminous mass structure of 12 strong lensing early-type galaxies. We combine pixel-based modelling of multiband Hubble Space Telescope imaging with Jeans modelling of kinematics obtained from Keck/ESI spectra to disentangle the dark and luminous contributions to the mass. Assuming a generalised NFW (gNFW) profile for the dark matter halo and a spatially constant stellar-mass-to-light ratio ϒ⋆ for the baryonic mass, we infer distributions for ϒ⋆ consistent with initial mass functions (IMFs) that are heavier than the Milky Way's (with a global mean mismatch parameter relative to a Chabrier IMF μαc = 1.80 ± 0.14) and halo inner density slopes that span a large range but are generally cuspier than the dark-matter-only prediction (μ _{γ ^' }} = 2.01_{-0.22}^{+0.19}). We investigate possible reasons for overestimating the halo slope, including the neglect of spatially varying stellar-mass-to-light ratios and/or stellar orbital anisotropy, and find that a quarter of the systems prefer radially declining stellar-mass-to-light ratio gradients, but that the overall effect on our inference on the halo slope is small. We suggest a coherent explanation of these results in the context of inside-out galaxy growth, and that the relative importance of different baryonic processes in shaping the dark halo may depend on halo environment.

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.

Remote Sensing techniques used to characterize soil erosion in southwestern Sao Paulo state. M.S. Thesis - 29 Sep. 1982; [Brazil

NASA Technical Reports Server (NTRS)

Parada, N. D. J. (Principal Investigator); Pinto, S. D. A. F.

1983-01-01

Within randomly sampled squares of a 1 km x 1 km grid, rill/gullies frequency, land cover/land use type and shape of the slopes were extracted from aerial photographs of the Ribeirao Anhumas drainage basin. Mean slope gradient, stream frequency and slope length were calculated on topographic maps. Ground truth data on fine sand/coarse sand ratio and vegetation cover densities were obtained. The MSS-LANDSAT-2 data (CCTs) were analyzed using single-cell, cluster synthesis and slicer algorithms. Graphical and statistical analyses of the data indicate that different slope gradients and land cover/land use types are the most significant factors related to the soil erosion process. The digital analysis of MSS data allowed the association among gray level classes and vegetation cover classes, which defined seven classes. These gray level classes and slope gradient classes were used to rank erosion risk.

A novel risk assessment method for landfill slope failure: Case study application for Bhalswa Dumpsite, India.

PubMed

Jahanfar, Ali; Amirmojahedi, Mohsen; Gharabaghi, Bahram; Dubey, Brajesh; McBean, Edward; Kumar, Dinesh

2017-03-01

Rapid population growth of major urban centres in many developing countries has created massive landfills with extraordinary heights and steep side-slopes, which are frequently surrounded by illegal low-income residential settlements developed too close to landfills. These extraordinary landfills are facing high risks of catastrophic failure with potentially large numbers of fatalities. This study presents a novel method for risk assessment of landfill slope failure, using probabilistic analysis of potential failure scenarios and associated fatalities. The conceptual framework of the method includes selecting appropriate statistical distributions for the municipal solid waste (MSW) material shear strength and rheological properties for potential failure scenario analysis. The MSW material properties for a given scenario is then used to analyse the probability of slope failure and the resulting run-out length to calculate the potential risk of fatalities. In comparison with existing methods, which are solely based on the probability of slope failure, this method provides a more accurate estimate of the risk of fatalities associated with a given landfill slope failure. The application of the new risk assessment method is demonstrated with a case study for a landfill located within a heavily populated area of New Delhi, India.

The influence of electromyographic recording methods and the innervation zone on the mean power frequency-torque relationships.

PubMed

Herda, Trent J; Zuniga, Jorge M; Ryan, Eric D; Camic, Clayton L; Bergstrom, Haley C; Smith, Doug B; Weir, Joseph P; Cramer, Joel T; Housh, Terry J

2015-06-01

This study examined the effects of electromyographic (EMG) recording methods and innervation zone (IZ) on the mean power frequency (MPF)-torque relationships. Nine subjects performed isometric ramp muscle actions of the leg extensors from 5% to 100% of maximal voluntary contraction with an eight channel linear electrode array over the IZ of the vastus lateralis. The slopes were calculated from the log-transformed monopolar and bipolar EMG MPF-torque relationships for each channel and subject and 95% confidence intervals (CI) were constructed around the slopes for each relationship and the composite of the slopes. Twenty-two to 55% of the subjects exhibited 95% CIs that did not include a slope of zero for the monopolar EMG MPF-torque relationships while 25-75% of the subjects exhibited 95% CIs that did not include a slope of zero for the bipolar EMG MPF-torque relationships. The composite of the slopes from the EMG MPF-torque relationships were not significantly different from zero for any method or channel, however, the method and IZ location slightly influenced the number of significant slopes on a subject-by-subject basis. The log-transform model indicated that EMG MPF-torque patterns were nonlinear regardless of recording method or distance from the IZ. Copyright © 2015 Elsevier Ltd. All rights reserved.

Establish Effective Lower Bounds of Watershed Slope for Traditional Hydrologic Methods

DOT National Transportation Integrated Search

2012-06-01

Equations to estimate timing parameters for a watershed contain watershed slope as a principal parameter and : estimates are usually inversely proportional to topographic slope. Hence as slope vanishes, the estimates approach : infinity. The research...

A framework to evaluate the cost-effectiveness of the NADiA ProsVue slope to guide adjuvant radiotherapy among men with high-risk characteristics following prostatectomy for prostate cancer.

PubMed

Reed, Shelby D; Stewart, Suzanne Biehn; Scales, Charles D; Moul, Judd W

2014-07-01

The NADiA ProsVue is a prognostic system that measures prostate-specific antigen slope to identify men at lower risk of clinical recurrence of prostate cancer after radical prostatectomy. We developed a decision-modeling framework to evaluate its cost-effectiveness to guide the use of adjuvant radiotherapy (ART). We populated the model using patient-level data and external sources. Patients were classified as intermediate risk or high risk on the basis of Cancer of the Prostate Risk Assessment-Postsurgical (CAPRA-S) nomogram and then stratified by the ProsVue slope (≤2 pg/mL/mo; >2 pg/mL/mo) and receipt of ART. In sensitivity analyses, we varied the effect of the ProsVue slope on the use of ART and other model parameters. The cost-effectiveness of the ProsVue-guided strategy varied widely because of small differences in quality-adjusted life-years (QALYs) at 10 years. In the intermediate-risk group, when the use of ART decreased from 20% (standard care) to 7.5% among patients with a ProsVue slope value of 2 pg/mL/mo or less, the incremental cost-effectiveness ratio was $25,160/QALY. In the high-risk group, the use of ART would have to decrease from 40% (standard care) to 11.5% among those with a ProsVue slope value of 2 pg/mL/mo or less to obtain a ratio of $50,000/QALY. The cost-effectiveness ratios were sensitive to varying benefits of salvage therapy, quality of life, and costs of ART and ProsVue testing. The effect of the ProsVue system on costs will be dependent on the extent to which ART decreases among men identified as having a low risk of recurrence. Its effect on QALYs will remain conditional on uncertain clinical and quality-of-life benefits associated with ART. Copyright © 2014 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. All rights reserved.

Novel Modulation Method for Multidirectional Matrix Converter

PubMed Central

Misron, Norhisam; Aris, Ishak Bin; Yamada, Hiroaki

2014-01-01

This study presents a new modulation method for multidirectional matrix converter (MDMC), based on the direct duty ratio pulse width modulation (DDPWM). In this study, a new structure of MDMC has been proposed to control the power flow direction through the stand-alone battery based system and hybrid vehicle. The modulation method acts based on the average voltage over one switching period concept. Therefore, in order to determine the duty ratio for each switch, the instantaneous input voltages are captured and compared with triangular waveform continuously. By selecting the proper switching pattern and changing the slope of the carriers, the sinusoidal input current can be synthesized with high power factor and desired output voltage. The proposed system increases the discharging time of the battery by injecting the power to the system from the generator and battery at the same time. Thus, it makes the battery life longer and saves more energy. This paper also derived necessary equation for proposed modulation method as well as detail of analysis and modulation algorithm. The theoretical and modulation concepts presented have been verified in MATLAB simulation. PMID:25298969

A multi-center screening trial of rasagiline in patients with amyotrophic lateral sclerosis: Possible mitochondrial biomarker target engagement

PubMed Central

Macchi, Zachary; Wang, Yunxia; Moore, Dan; Katz, Jonathan; Saperstein, David; Walk, David; Simpson, Ericka; Genge, Angela; Bertorini, Tulio; Fernandes, J Americo; Swenson, Andrea; Elman, Lauren; Dimachkie, Mazen; Herbelin, Laura; Miller, Joann; Lu, Jianghua; Wilkins, Heather; Swerdlow, Russell H; Statland, Jeffrey; Barohn, Richard

2015-01-01

OBJECTIVE Rasagiline, a monoamine oxidase B inhibitor, slowed disease progression in the SOD1 mouse, and in a case series of patients with amyotrophic lateral sclerosis (ALS). Here we determine whether rasagiline is safe and effective in ALS compared to historical placebo controls, and whether it alters mitochondrial biomarkers. METHODS We performed a prospective open-label, multicenter screening trial of 36 ALS patients treated with 2mg oral rasagiline daily for 12 months. Outcomes included the slope of deterioration of the revised ALS Functional Rating Scale (ALSFRS-R), adverse event monitoring, time to treatment failure, and exploratory biomarkers. RESULTS Participants experienced no serious drug-related adverse events, and the most common adverse event was nausea (11.1%). Rasagiline did not improve the rate of decline in the ALSFRS-R; however, differences in symptom duration compared to historical placebo controls differentially affected ALSFRS-R slope estimates. Rasagiline changed biomarkers over 12 months, such that the mitochondrial membrane potential increased (JC-1 red/green fluorescent ratio 1.92, P=0.0001) and apoptosis markers decreased (Bcl-2/Bax ratio 0.24, P<0.0001). CONCLUSION Engagement of exploratory biomarkers and questions about comparability of baseline characteristics lead us to recommend a further placebo-controlled trial. PMID:25832828

Impacts of Greening Materials and Seed Pretreatment on Vegetation Development at an initial stage

NASA Astrophysics Data System (ADS)

Obriejetan, Michael

2015-04-01

Slope protection using greening measures as an integral part of soil-bioengineering is characterized by an increasing demand in research and practice. However, successful greening is a very complex issue due to the vast variety in specific slope characteristics such as morphology, soil properties and environmental factors. Because of practical experience in the greening of slopes and the results of further investigations in small-scale tests, it can be stated that the use of appropriate planting techniques, the quality of the materials used and the proper implementation of potential needed auxiliary materials at difficult locations are seen as key success criteria for sustainable vegetation development. Within this framework small-scale testing series were conducted regarding the influence of specific soil-properties, the use of auxiliary greening materials (fertilizer, mycorrhiza fungi, Bonded fiber matrix (BFM)…), application of different seed-pretreatment methods and influences of specific environmental factors (inclination, seeding depth) on vegetational development in an early phase. The aim of the series is to quantitatively and thus economically optimize the use of different greening-components and seed mixtures for practical application, while ensuring optimal development of vegetation. To quantify the influence of the treatment systems, vegetation cover ratio, biomass production (aboveground and belowground) and the germination of plant seeds served as main criteria for assessing the development in an initial stage. Selected findings for instance show that the admixture of mycorrhiza fungi can increase the cover ratio up to 23 % compared to untreated plots. In addition, pretreatment of seeds showed distinct effects too by shortening germination phase and increasing the capability of producing a higher amount of healthy sprouts. From a bioengineering perspective the results will serve as potential decisive advantage for successful implementation of greening measures.

Pretreatment CD4 Cell Slope and Progression to AIDS or Death in HIV-Infected Patients Initiating Antiretroviral Therapy—The CASCADE Collaboration: A Collaboration of 23 Cohort Studies

PubMed Central

Wolbers, Marcel; Babiker, Abdel; Sabin, Caroline; Young, Jim; Dorrucci, Maria; Chêne, Geneviève; Mussini, Cristina; Porter, Kholoud; Bucher, Heiner C.

2010-01-01

Background CD4 cell count is a strong predictor of the subsequent risk of AIDS or death in HIV-infected patients initiating combination antiretroviral therapy (cART). It is not known whether the rate of CD4 cell decline prior to therapy is related to prognosis and should, therefore, influence the decision on when to initiate cART. Methods and Findings We carried out survival analyses of patients from the 23 cohorts of the CASCADE (Concerted Action on SeroConversion to AIDS and Death in Europe) collaboration with a known date of HIV seroconversion and with at least two CD4 measurements prior to initiating cART. For each patient, a pre-cART CD4 slope was estimated using a linear mixed effects model. Our primary outcome was time from initiating cART to a first new AIDS event or death. We included 2,820 treatment-naïve patients initiating cART with a median (interquartile range) pre-cART CD4 cell decline of 61 (46–81) cells/µl per year; 255 patients subsequently experienced a new AIDS event or death and 125 patients died. In an analysis adjusted for established risk factors, the hazard ratio for AIDS or death was 1.01 (95% confidence interval 0.97–1.04) for each 10 cells/µl per year reduction in pre-cART CD4 cell decline. There was also no association between pre-cART CD4 cell slope and survival. Alternative estimates of CD4 cell slope gave similar results. In 1,731 AIDS-free patients with >350 CD4 cells/µl from the pre-cART era, the rate of CD4 cell decline was also not significantly associated with progression to AIDS or death (hazard ratio 0.99, 95% confidence interval 0.94–1.03, for each 10 cells/µl per year reduction in CD4 cell decline). Conclusions The CD4 cell slope does not improve the prediction of clinical outcome in patients with a CD4 cell count above 350 cells/µl. Knowledge of the current CD4 cell count is sufficient when deciding whether to initiate cART in asymptomatic patients. Please see later in the article for the Editors' Summary PMID:20186270

Relation between self-organized criticality and grain aspect ratio in granular piles

NASA Astrophysics Data System (ADS)

Denisov, D. V.; Villanueva, Y. Y.; Lőrincz, K. A.; May, S.; Wijngaarden, R. J.

2012-05-01

We investigate experimentally whether self-organized criticality (SOC) occurs in granular piles composed of different grains, namely, rice, lentils, quinoa, and mung beans. These four grains were selected to have different aspect ratios, from oblong to oblate. As a function of aspect ratio, we determined the growth (β) and roughness (α) exponents, the avalanche fractal dimension (D), the avalanche size distribution exponent (τ), the critical angle (γ), and its fluctuation. At superficial inspection, three types of grains seem to have power-law-distributed avalanches with a well-defined τ. However, only rice is truly SOC if we take three criteria into account: a power-law-shaped avalanche size distribution, finite size scaling, and a universal scaling relation relating characteristic exponents. We study SOC as a spatiotemporal fractal; in particular, we study the spatial structure of criticality from local observation of the slope angle. From the fluctuation of the slope angle we conclude that greater fluctuation (and thus bigger avalanches) happen in piles consisting of grains with larger aspect ratio.

Inorganic and organic geochemical fingerprinting of sediment sources and ocean circulation on a complex continental margin (São Paulo Bight, Brazil)

NASA Astrophysics Data System (ADS)

Michaelovitch de Mahiques, Michel; Jörg Hanebuth, Till Jens; Hanae Nagai, Renata; Caruso Bícego, Marcia; Lopes Figueira, Rubens Cesar; Mello Sousa, Silvia Helena; Burone, Leticia; Franco-Fraguas, Paula; Taniguchi, Satie; Barbosa Salaroli, Alexandre; Pereira Dias, Gilberto; Menezes Prates, Denise; Fernandes Freitas, Maria Eugenia

2017-03-01

In this study, we use inorganic (metal) and organic (bulk and molecular) markers in sediment samples of the south-eastern Brazilian margin to investigate the response of geochemical fingerprints to the complex hydrodynamic processes present in the area. Results indicate the potential of export of terrigenous siliciclastic and organic constituents to the upper slope, even in an area with limited fluvial supply.

Metal contents and especially the ln(Ti / Al) and ln(Fe / K) ratios make it possible to recognise the extension of shelf sediments toward the upper slope. Potassium, here expressed as ln(K / Sc) and ln(K / Al) ratios used as proxies of illite-kaolinite variations, proved to be an important parameter, especially because it allowed us to decipher the imprint of the northward flow of the Intermediate Western Boundary Current (IWBC) in comparison to the southward flows of the Brazil Current (BC) and Deep Western Boundary Current (DWBC). Using organic matter analyses, we were able to evaluate the extent of terrestrial contributions to the outer shelf and slope, even without the presence of significant fluvial input. In addition, molecular markers signify a slight increase in the input of C4-derived plants to the slope sediments, transported from distant areas by the main alongshore boundary currents, indicating that the terrestrial fraction of the organic matter deposited on the slope has a distinct origin when compared to shelf sediments.

Reliability Analysis of Differential Relay as Main Protection Transformer Using Fuzzy Logic Algorithm

NASA Astrophysics Data System (ADS)

Mulyadi, Y.; Sucita, T.; Sumarto; Alpani, M.

2018-02-01

Electricity supply demand is increasing every year. It makes PT. PLN (Persero) is required to provide optimal customer service and satisfaction. Optimal service depends on the performance of the equipment of the power system owned, especially the transformer. Power transformer is an electrical equipment that transforms electricity from high voltage to low voltage or vice versa. However, in the electrical power system, is inseparable from interference included in the transformer. But, the disturbance can be minimized by the protection system. The main protection transformer is differential relays. Differential relays working system using Kirchoff law where inflows equal outflows. If there are excessive currents that interfere then the relays will work. But, the relay can also experience decreased performance. Therefore, this final project aims to analyze the reliability of the differential relay on the transformer in three different substations. Referring to the standard applied by the transmission line protection officer, the differential relay shall have slope characteristics of 30% in the first slope and 80% in the second slope when using two slopes and 80% when using one slope with an instant time and the corresponding ratio. So, the results obtained on the Siemens differential release have a reliable slope characteristic with a value of 30 on the fuzzy logic system. In a while, ABB a differential relay is only 80% reliable because two experiments are not reliable. For the time, all the differential relays are instant with a value of 0.06 on the fuzzy logic system. For ratios, the differential relays ABB have a better value than others brand with a value of 151 on the fuzzy logic system.

Past Decline Versus Current eGFR and Subsequent Mortality Risk.

PubMed

Naimark, David M J; Grams, Morgan E; Matsushita, Kunihiro; Black, Corri; Drion, Iefke; Fox, Caroline S; Inker, Lesley A; Ishani, Areef; Jee, Sun Ha; Kitamura, Akihiko; Lea, Janice P; Nally, Joseph; Peralta, Carmen Alicia; Rothenbacher, Dietrich; Ryu, Seungho; Tonelli, Marcello; Yatsuya, Hiroshi; Coresh, Josef; Gansevoort, Ron T; Warnock, David G; Woodward, Mark; de Jong, Paul E

2016-08-01

A single determination of eGFR associates with subsequent mortality risk. Prior decline in eGFR indicates loss of kidney function, but the relationship to mortality risk is uncertain. We conducted an individual-level meta-analysis of the risk of mortality associated with antecedent eGFR slope, adjusting for established risk factors, including last eGFR, among 1.2 million subjects from 12 CKD and 22 other cohorts within the CKD Prognosis Consortium. Over a 3-year antecedent period, 12% of participants in the CKD cohorts and 11% in the other cohorts had an eGFR slope <-5 ml/min per 1.73 m(2) per year, whereas 7% and 4% had a slope >5 ml/min per 1.73 m(2) per year, respectively. Compared with a slope of 0 ml/min per 1.73 m(2) per year, a slope of -6 ml/min per 1.73 m(2) per year associated with adjusted hazard ratios for all-cause mortality of 1.25 (95% confidence interval [95% CI], 1.09 to 1.44) among CKD cohorts and 1.15 (95% CI, 1.01 to 1.31) among other cohorts during a follow-up of 3.2 years. A slope of +6 ml/min per 1.73 m(2) per year also associated with higher all-cause mortality risk, with adjusted hazard ratios of 1.58 (95% CI, 1.29 to 1.95) among CKD cohorts and 1.43 (95% CI, 1.11 to 1.84) among other cohorts. Results were similar for cardiovascular and noncardiovascular causes of death and stronger for longer antecedent periods (3 versus <3 years). We conclude that prior decline or rise in eGFR associates with an increased risk of mortality, independent of current eGFR. Copyright © 2016 by the American Society of Nephrology.

Long-term weight-change slope, weight fluctuation and risk of type 2 diabetes mellitus in middle-aged Japanese men and women: findings of Aichi Workers' Cohort Study

PubMed Central

Zhang, Y; Yatsuya, H; Li, Y; Chiang, C; Hirakawa, Y; Kawazoe, N; Tamakoshi, K; Toyoshima, H; Aoyama, A

2017-01-01

Objective: This study aims to investigate the association of long-term weight-change slopes, weight fluctuation and the risk of type 2 diabetes mellitus (T2DM) in middle-aged Japanese men and women. Methods: A total of 4234 participants of Aichi Workers' Cohort Study who were aged 35–66 years and free of diabetes in 2002 were followed through 2014. Past body weights at the ages of 20, 25, 30, 40 years, and 5 years before baseline as well as measured body weight at baseline were regressed on the ages. Slope and root-mean-square-error of the regression line were obtained and used to represent the weight changes and the weight fluctuation, respectively. The associations of the weight-change slopes and the weight fluctuation with incident T2DM were estimated by Cox proportional hazards models. Results: During the median follow-up of 12.2 years, 400 incident cases of T2DM were documented. After adjustment for baseline overweight and other lifestyle covariates, the weight-change slopes were significantly associated with higher incidence of T2DM (hazard ratio (HR): 1.80, 95% confident interval (CI): 1.17–2.77 for men; and HR: 2.78, 95% CI: 1.07–7.23 for women), while the weight fluctuation was not (HR: 1.08, 95% CI: 1.00–1.18 for men and HR: 1.02, 95% CI: 0.84–1.25 for women). Conclusions: Regardless of the presence of overweight, the long-term weight-change slopes were significantly associated with the increased risk of T2DM; however, the weight fluctuation was not associated with the risk of T2DM in middle-aged Japanese men and women. PMID:28319107

Central command differentially affects aortic and carotid sinus baroreflexes at the onset of spontaneous motor activity.

PubMed

Matsukawa, Kanji; Ishii, Kei; Idesako, Mitsuhiro; Ishida, Tomoko; Endo, Kana; Liang, Nan

2013-12-01

Our laboratory has recently demonstrated that central command provides selective inhibition of the cardiomotor component of aortic (AOR) baroreflex during exercise, preserving carotid sinus (CS) baroreflex. To further explore the differential effects of central command on the arterial baroreflexes, we surgically separated the AOR and CS baroreflex systems, to identify the input-output relationship of each baroreflex system using brief occlusion of the abdominal aorta in decerebrate cats. Baroreflex sensitivity for heart rate (HR) was estimated from the baroreflex ratio between the pressor and bradycardia responses during aortic occlusion and from the slope of the baroreflex curve between the changes in mean arterial blood pressure (ΔMAP) and ΔHR. Spontaneous motor activity accompanied the abrupt increases in HR and MAP. When aortic occlusion was given at the onset of spontaneous motor activity, the baroreflex ratio was blunted to 11-25% of the preexercise value in either intact or AOR baroreflex. The slope of the ΔMAP-ΔHR curve was similarly attenuated at the onset of spontaneous motor activity to 11-18% of the slope during the preexercise period. In contrast, in the CS baroreflex, the baroreflex ratio and curve slope were not significantly (P>0.05) altered by spontaneous motor activity. An upward shift of the baroreflex curve appeared at the onset of spontaneous motor activity, irrespective of the intact, AOR, and CS baroreflex conditions. Taken together, it is concluded that central command provides selective inhibition for the cardiomotor limb of the aortic baroreflex at the onset of exercise, which in turn contributes to an instantaneous increase in HR. © 2013.

Quantifying peak discharges for historical floods

USGS Publications Warehouse

Cook, J.L.

1987-01-01

It is usually advantageous to use information regarding historical floods, if available, to define the flood-frequency relation for a stream. Peak stages can sometimes be determined for outstanding floods that occurred many years ago before systematic gaging of streams began. In the United States, this information is usually not available for more than 100-200 years, but in countries with long cultural histories, such as China, historical flood data are available at some sites as far back as 2,000 years or more. It is important in flood studies to be able to assign a maximum discharge rate and an associated error range to the historical flood. This paper describes the significant characteristics and uncertainties of four commonly used methods for estimating the peak discharge of a flood. These methods are: (1) rating curve (stage-discharge relation) extension; (2) slope conveyance; (3) slope area; and (4) step backwater. Logarithmic extensions of rating curves are based on theoretical plotting techniques that results in straight line extensions provided that channel shape and roughness do not change significantly. The slope-conveyance and slope-area methods are based on the Manning equation, which requires specific data on channel size, shape and roughness, as well as the water-surface slope for one or more cross-sections in a relatively straight reach of channel. The slope-conveyance method is used primarily for shaping and extending rating curves, whereas the slope-area method is used for specific floods. The step-backwater method, also based on the Manning equation, requires more cross-section data than the slope-area ethod, but has a water-surface profile convergence characteristic that negates the need for known or estimated water-surface slope. Uncertainties in calculating peak discharge for historical floods may be quite large. Various investigations have shown that errors in calculating peak discharges by the slope-area method under ideal conditions for recent floods (i.e., when flood elevations, slope and channel characteristics are reasonably certain), may be on the order of 10-25%. Under less than ideal conditions, where streams are hydraulically steep and rough, errors may be much larger. The additional uncertainties for historical floods created by the passage of time may result in even larger errors of peak discharge. ?? 1987.

Landslide susceptibility mapping by combining the three methods Fuzzy Logic, Frequency Ratio and Analytical Hierarchy Process in Dozain basin

NASA Astrophysics Data System (ADS)

Tazik, E.; Jahantab, Z.; Bakhtiari, M.; Rezaei, A.; Kazem Alavipanah, S.

2014-10-01

Landslides are among the most important natural hazards that lead to modification of the environment. Therefore, studying of this phenomenon is so important in many areas. Because of the climate conditions, geologic, and geomorphologic characteristics of the region, the purpose of this study was landslide hazard assessment using Fuzzy Logic, frequency ratio and Analytical Hierarchy Process method in Dozein basin, Iran. At first, landslides occurred in Dozein basin were identified using aerial photos and field studies. The influenced landslide parameters that were used in this study including slope, aspect, elevation, lithology, precipitation, land cover, distance from fault, distance from road and distance from river were obtained from different sources and maps. Using these factors and the identified landslide, the fuzzy membership values were calculated by frequency ratio. Then to account for the importance of each of the factors in the landslide susceptibility, weights of each factor were determined based on questionnaire and AHP method. Finally, fuzzy map of each factor was multiplied to its weight that obtained using AHP method. At the end, for computing prediction accuracy, the produced map was verified by comparing to existing landslide locations. These results indicate that the combining the three methods Fuzzy Logic, Frequency Ratio and Analytical Hierarchy Process method are relatively good estimators of landslide susceptibility in the study area. According to landslide susceptibility map about 51% of the occurred landslide fall into the high and very high susceptibility zones of the landslide susceptibility map, but approximately 26 % of them indeed located in the low and very low susceptibility zones.

Empirical correspondence between trophic transfer efficiency in freshwater food webs and the slope of their size spectra.

PubMed

Mehner, Thomas; Lischke, Betty; Scharnweber, Kristin; Attermeyer, Katrin; Brothers, Soren; Gaedke, Ursula; Hilt, Sabine; Brucet, Sandra

2018-06-01

The density of organisms declines with size, because larger organisms need more energy than smaller ones and energetic losses occur when larger organisms feed on smaller ones. A potential expression of density-size distributions are Normalized Biomass Size Spectra (NBSS), which plot the logarithm of biomass independent of taxonomy within bins of logarithmic organismal size, divided by the bin width. Theoretically, the NBSS slope of multi-trophic communities is exactly -1.0 if the trophic transfer efficiency (TTE, ratio of production rates between adjacent trophic levels) is 10% and the predator-prey mass ratio (PPMR) is fixed at 10 4 . Here we provide evidence from four multi-trophic lake food webs that empirically estimated TTEs correspond to empirically estimated slopes of the respective community NBSS. Each of the NBSS considered pelagic and benthic organisms spanning size ranges from bacteria to fish, all sampled over three seasons in 1 yr. The four NBSS slopes were significantly steeper than -1.0 (range -1.14 to -1.19, with 95% CIs excluding -1). The corresponding average TTEs were substantially lower than 10% in each of the four food webs (range 1.0% to 3.6%, mean 1.85%). The overall slope merging all biomass-size data pairs from the four systems (-1.17) was almost identical to the slope predicted from the arithmetic mean TTE of the four food webs (-1.18) assuming a constant PPMR of 10 4 . Accordingly, our empirical data confirm the theoretically predicted quantitative relationship between TTE and the slope of the biomass-size distribution. Furthermore, we show that benthic and pelagic organisms can be merged into a community NBSS, but future studies have yet to explore potential differences in habitat-specific TTEs and PPMRs. We suggest that community NBSS may provide valuable information on the structure of food webs and their energetic pathways, and can result in improved accuracy of TTE-estimates. © 2018 by the Ecological Society of America.

Effect of Different Groundwater Levels on Seismic Dynamic Response and Failure Mode of Sandy Slope

PubMed Central

Huang, Shuai; Lv, Yuejun; Peng, Yanju; Zhang, Lifang; Xiu, Liwei

2015-01-01

Heavy seismic damage tends to occur in slopes when groundwater is present. The main objectives of this paper are to determine the dynamic response and failure mode of sandy slope subjected simultaneously to seismic forces and variable groundwater conditions. This paper applies the finite element method, which is a fast and efficient design tool in modern engineering analysis, to evaluate dynamic response of the slope subjected simultaneously to seismic forces and variable groundwater conditions. Shaking table test is conducted to analyze the failure mode and verify the accuracy of the finite element method results. The research results show that dynamic response values of the slope have different variation rules under near and far field earthquakes. And the damage location and pattern of the slope are different in varying groundwater conditions. The destruction starts at the top of the slope when the slope is in no groundwater, which shows that the slope appears obvious whipping effect under the earthquake. The destruction starts at the toe of the slope when the slope is in the high groundwater levels. Meanwhile, the top of the slope shows obvious seismic subsidence phenomenon after earthquake. Furthermore, the existence of the groundwater has a certain effect of damping. PMID:26560103

Weighted spline based integration for reconstruction of freeform wavefront.

PubMed

Pant, Kamal K; Burada, Dali R; Bichra, Mohamed; Ghosh, Amitava; Khan, Gufran S; Sinzinger, Stefan; Shakher, Chandra

2018-02-10

In the present work, a spline-based integration technique for the reconstruction of a freeform wavefront from the slope data has been implemented. The slope data of a freeform surface contain noise due to their machining process and that introduces reconstruction error. We have proposed a weighted cubic spline based least square integration method (WCSLI) for the faithful reconstruction of a wavefront from noisy slope data. In the proposed method, the measured slope data are fitted into a piecewise polynomial. The fitted coefficients are determined by using a smoothing cubic spline fitting method. The smoothing parameter locally assigns relative weight to the fitted slope data. The fitted slope data are then integrated using the standard least squares technique to reconstruct the freeform wavefront. Simulation studies show the improved result using the proposed technique as compared to the existing cubic spline-based integration (CSLI) and the Southwell methods. The proposed reconstruction method has been experimentally implemented to a subaperture stitching-based measurement of a freeform wavefront using a scanning Shack-Hartmann sensor. The boundary artifacts are minimal in WCSLI which improves the subaperture stitching accuracy and demonstrates an improved Shack-Hartmann sensor for freeform metrology application.

Numerical Computation of Homogeneous Slope Stability

PubMed Central

Xiao, Shuangshuang; Li, Kemin; Ding, Xiaohua; Liu, Tong

2015-01-01

To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS) to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM) and particle swarm optimization algorithm (PSO) to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759) were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS). PMID:25784927

Numerical computation of homogeneous slope stability.

PubMed

Xiao, Shuangshuang; Li, Kemin; Ding, Xiaohua; Liu, Tong

2015-01-01

To simplify the computational process of homogeneous slope stability, improve computational accuracy, and find multiple potential slip surfaces of a complex geometric slope, this study utilized the limit equilibrium method to derive expression equations of overall and partial factors of safety. This study transformed the solution of the minimum factor of safety (FOS) to solving of a constrained nonlinear programming problem and applied an exhaustive method (EM) and particle swarm optimization algorithm (PSO) to this problem. In simple slope examples, the computational results using an EM and PSO were close to those obtained using other methods. Compared to the EM, the PSO had a small computation error and a significantly shorter computation time. As a result, the PSO could precisely calculate the slope FOS with high efficiency. The example of the multistage slope analysis indicated that this slope had two potential slip surfaces. The factors of safety were 1.1182 and 1.1560, respectively. The differences between these and the minimum FOS (1.0759) were small, but the positions of the slip surfaces were completely different than the critical slip surface (CSS).

Correction of Excessive Precipitation over Steep and High Mountains in a GCM: A Simple Method of Parameterizing the Thermal Effects of Subgrid Topographic Variation

NASA Technical Reports Server (NTRS)

Chao, Winston C.

2015-01-01

The excessive precipitation over steep and high mountains (EPSM) in GCMs and meso-scale models is due to a lack of parameterization of the thermal effects of the subgrid-scale topographic variation. These thermal effects drive subgrid-scale heated slope induced vertical circulations (SHVC). SHVC provide a ventilation effect of removing heat from the boundary layer of resolvable-scale mountain slopes and depositing it higher up. The lack of SHVC parameterization is the cause of EPSM. The author has previously proposed a method of parameterizing SHVC, here termed SHVC.1. Although this has been successful in avoiding EPSM, the drawback of SHVC.1 is that it suppresses convective type precipitation in the regions where it is applied. In this article we propose a new method of parameterizing SHVC, here termed SHVC.2. In SHVC.2 the potential temperature and mixing ratio of the boundary layer are changed when used as input to the cumulus parameterization scheme over mountainous regions. This allows the cumulus parameterization to assume the additional function of SHVC parameterization. SHVC.2 has been tested in NASA Goddard's GEOS-5 GCM. It achieves the primary goal of avoiding EPSM while also avoiding the suppression of convective-type precipitation in regions where it is applied.

Geologic control of mineral composition of stream waters of the eastern slope of the Southern Coast Ranges, California

USGS Publications Warehouse

Davis, G.H.

1961-01-01

Chemical analyses of waters of streams that drain the semiarid eastern slope of the southern Coast Ranges in California demonstrate that differences in the anion composition, especially in the ratio of bicarbonate to sulfate, are related chiefly to the lithologic character of the rocks exposed in the tributary drainage area. Where more than hall the drainage area of a typical eastern-slope stream is underlain by clastic marine sedimentary rocks of Jurassic and Cretaceous age, bicarbonate generally predominates over sulfate; the ratio of bicarbonate to sullate, both expressed in equivalents per million, in samples of the streams at low-flow stage ranges from 0.8 to 6. Conversely, where more than hall the drainage area is underlain by marine and continental deposits of Tertiary age and continental deposits of Quaternary age, sulfate predominates over bicarbonate, and the ratio of bicarbonate to sulfate in samples taken during the low-flow stage ranges from 0.02 to 0.7. Organic siliceous marine shale of Tertiary age deposited in a reducing environment is probably the primary source of sullate in the region. Secondary deposits of sulfate minerals, chiefly gypsum, which are abundant in the continental deposits of late Tertiary and Quaternary age, also contribute sullate to the stream waters.

Scintigraphy for pulmonary capillary protein leak. Final report, 1 October 1981-30 September 1985

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

Sugerman, H.J.; Tatum, J.L.; Hirsch, J.I.

1986-06-01

Computerized scintigraphy, employing the gamma camera, has been used to study the dynamics of the pulmonary capillary membrane leak of 99m-technetium-tagged human serum albumin (Tc-HSA). In preliminary canine studies, the severity of an oleic acid-induced albumin leak was proportional to the slope of lung: heart radioactivity ratio and was more sensitive than arterial blood gases or standard chest roentgenograms. This rising ratio is called slope of injury slope index. A number of agents were studied in an attempt to prevent oleic acid-induced pulmonary microvascular injury. Following a series of five control dogs, five dogs each were studied with each ofmore » the following agents: methylprednisolone, ibuprofen, the superoxide radical scavenger, MK-44, and, in three dogs, calcium gluconate. None of these agents was able to alter the rise in lung: heart radioactivity ratio following oleic acid injury. A septic pig model was developed for study of bacterially induced ARDS. Septic-induced ARDS and multi-system organ failure are probably secondary to the systemic release of several mediators of inflammation, treatment will probably require a combination of anti-inflammatory agents. This should impact significantly on the mortality and morbidity of septic complications in traumatized combat soldiers.« less

Research on discrete element simulation of anchor frame beam reinforcement in bedding shale slope

NASA Astrophysics Data System (ADS)

Zhang, Xiao yong; Xie, Xiao ting

2017-11-01

The anchor frame beam is a new type of composite support method, which is a kind of slope protection structure considering the interaction between the anchors and the slope. Based on the reinforcement project of a bedding shale slope in Chengzhang highway, the reinforced effect of anchor frame beam is studied by discrete element method. Firstly, the mesoscopic parameters of the rock mass are obtained by calibration while that of anchor frame beam are obtained by calculation. Then the slope model with the reinforcement of anchor frame beam is established by particle flow software PFC2D. Afterwards, the statement of slope can be analyzed and the reinforcement effect of anchor frame beam can be predicted. Results show that: there is no instability in the slope after reinforcement, and the sliding of slope can be effectively prevented by anchor frame beam. The simulation results can provide reference for the design and construction of the project.

PARTIAL RESTRAINING FORCE INTRODUCTION METHOD FOR DESIGNING CONSTRUCTION COUNTERMESURE ON ΔB METHOD

NASA Astrophysics Data System (ADS)

Nishiyama, Taku; Imanishi, Hajime; Chiba, Noriyuki; Ito, Takao

Landslide or slope failure is a three-dimensional movement phenomenon, thus a three-dimensional treatment makes it easier to understand stability. The ΔB method (simplified three-dimensional slope stability analysis method) is based on the limit equilibrium method and equals to an approximate three-dimensional slope stability analysis that extends two-dimensional cross-section stability analysis results to assess stability. This analysis can be conducted using conventional spreadsheets or two-dimensional slope stability computational software. This paper describes the concept of the partial restraining force in-troduction method for designing construction countermeasures using the distribution of the restraining force found along survey lines, which is based on the distribution of survey line safety factors derived from the above-stated analysis. This paper also presents the transverse distributive method of restraining force used for planning ground stabilizing on the basis of the example analysis.

Rate-dependent carbon and nitrogen kinetic isotope fractionation in hydrolysis of isoproturon.

PubMed

Penning, Holger; Cramer, Christopher J; Elsner, Martin

2008-11-01

Stable isotope fractionation permits quantifying contaminant degradation in the field when the transformation reaction is associated with a consistent isotope enrichment factor epsilon. When interpreted in conjunction with dual isotope plots, isotope fractionation is also particularly useful for elucidating reaction mechanisms. To assess the consistency of epsilon and dual isotope slopes in a two-step reaction, we investigated the abiotic hydrolysis of the herbicide isoproturon (3-(4-isopropylphenyl)-1,1-dimethylurea) using a fragmentation method that allows measuring isotope ratios in different parts of the molecule. Carbon and nitrogen position-specific isotope fractionation, as well as slopes in dual isotope plots, varied linearly with rate constants k(obs) depending on the presence of buffers that mediate the initial zwitterion formation. The correlation can be explained by two consecutive reaction steps (zwitterion formation followed by dimethylamine elimination) each of which has a different kinetic isotope effect and may be rate-limiting. Intrinsic isotope effects for both steps, extracted from our kinetic data using a novel theoretical treatment, agree well with values computed from density functional calculations. Our study therefore demonstrates that more variable isotope fractionation may be observed in simple chemical reactions than commonly thought, but that consistent epsilon or dual isotope slopes may nonetheless be encountered in certain molecular fragments.

Helping Students with Mathematics Difficulties Understand Ratios and Proportions

ERIC Educational Resources Information Center

Dougherty, Barbara; Bryant, Diane Pedrotty; Bryant, Brian R.; Shin, Mikyung

2016-01-01

Ratios and proportions are foundational to student understanding across multiple topics in mathematics and science. In mathematics, they are central to developing concepts and skills related to slope, constant rate of change, and similar figures, which are all fundamental to algebraic concepts and skills. This article examines the importance of…

Experimental detection of optical vortices with a Shack-Hartmann wavefront sensor.

PubMed

Murphy, Kevin; Burke, Daniel; Devaney, Nicholas; Dainty, Chris

2010-07-19

Laboratory experiments are carried out to detect optical vortices in conditions typical of those experienced when a laser beam is propagated through the atmosphere. A Spatial Light Modulator (SLM) is used to mimic atmospheric turbulence and a Shack-Hartmann wavefront sensor is utilised to measure the slopes of the wavefront surface. A matched filter algorithm determines the positions of the Shack-Hartmann spot centroids more robustly than a centroiding algorithm. The slope discrepancy is then obtained by taking the slopes measured by the wavefront sensor away from the slopes calculated from a least squares reconstruction of the phase. The slope discrepancy field is used as an input to the branch point potential method to find if a vortex is present, and if so to give its position and sign. The use of the slope discrepancy technique greatly improves the detection rate of the branch point potential method. This work shows the first time the branch point potential method has been used to detect optical vortices in an experimental setup.

A DESIGN METHOD FOR RETAINING WALL BASED ON RETURN PERIOD OF RAINFALL AND SNOWMELT

NASA Astrophysics Data System (ADS)

Ebana, Ryo; Uehira, Kenichiro; Yamada, Tadashi

The main purpose of this study is to develop a new design method for the retaining wall in a cold district. In the cold district, snowfall and snowmelt is one of the main factors in sediment related disaster. However, the effect of the snowmelt is not being taken account of sediment disasters precaution and evacuation system. In this study, we target at past slope failure disaster and quantitatively evaluate that the effect of rainfall and snowmelt on groundwater level and then verify the stability of slope. Water supplied on the slope was determined from the probabilistic approach of the snowmelt using DegreeDay method in this study. Furthermore, a slope stability analysis was carried out based on the ground water level that was obtained from the unsaturated infiltration flow with the saturated seepage flow simulations. From the result of the slope stability analysis, it was found that the effect of ground water level on the stability of slope is much bigger than that of other factors.

REGRES: A FORTRAN-77 program to calculate nonparametric and ``structural'' parametric solutions to bivariate regression equations

NASA Astrophysics Data System (ADS)

Rock, N. M. S.; Duffy, T. R.

REGRES allows a range of regression equations to be calculated for paired sets of data values in which both variables are subject to error (i.e. neither is the "independent" variable). Nonparametric regressions, based on medians of all possible pairwise slopes and intercepts, are treated in detail. Estimated slopes and intercepts are output, along with confidence limits, Spearman and Kendall rank correlation coefficients. Outliers can be rejected with user-determined stringency. Parametric regressions can be calculated for any value of λ (the ratio of the variances of the random errors for y and x)—including: (1) major axis ( λ = 1); (2) reduced major axis ( λ = variance of y/variance of x); (3) Y on Xλ = infinity; or (4) X on Y ( λ = 0) solutions. Pearson linear correlation coefficients also are output. REGRES provides an alternative to conventional isochron assessment techniques where bivariate normal errors cannot be assumed, or weighting methods are inappropriate.

Determination Of Slope Instability Using Spatially Integrated Mapping Framework

NASA Astrophysics Data System (ADS)

Baharuddin, I. N. Z.; Omar, R. C.; Roslan, R.; Khalid, N. H. N.; Hanifah, M. I. M.

2016-11-01

The determination and identification of slope instability are often rely on data obtained from in-situ soil investigation work where it involves the logistic of machineries and manpower, thus these aspects may increase the cost especially for remote locations. Therefore a method, which is able to identify possible slope instability without frequent ground walkabout survey, is needed. This paper presents the method used in prediction of slope instability using spatial integrated mapping framework which applicable for remote areas such as tropical forest and natural hilly terrain. Spatial data such as geology, topography, land use map, slope angle and elevation were used in regional analysis during desktop study. Through this framework, the occurrence of slope instability was able to be identified and was validate using a confirmatory site- specific analysis.

Slope efficiency over 30% single-frequency ytterbium-doped fiber laser based on Sagnac loop mirror filter.

PubMed

Yin, Mojuan; Huang, Shenghong; Lu, Baole; Chen, Haowei; Ren, Zhaoyu; Bai, Jintao

2013-09-20

A high-slope-efficiency single-frequency (SF) ytterbium-doped fiber laser, based on a Sagnac loop mirror filter (LMF), was demonstrated. It combined a simple linear cavity with a Sagnac LMF that acted as a narrow-bandwidth filter to select the longitudinal modes. And we introduced a polarization controller to restrain the spatial hole burning effect in the linear cavity. The system could operate at a stable SF oscillating at 1064 nm with the obtained maximum output power of 32 mW. The slope efficiency was found to be primarily dependent on the reflectivity of the fiber Bragg grating. The slope efficiency of multi-longitudinal modes was higher than 45%, and the highest slope efficiency of the single longitudinal mode we achieved was 33.8%. The power stability and spectrum stability were <2% and <0.1%, respectively, and the signal-to-noise ratio measured was around 60 dB.

Moxifloxacin-induced QTc interval prolongations in healthy male Japanese and Caucasian volunteers: a direct comparison in a thorough QT study

PubMed Central

Morganroth, Joel; Wang, Yaning; Thorn, Michael; Kumagai, Yuji; Harris, Stuart; Stockbridge, Norman; Kleiman, Robert; Shah, Rashmi

2015-01-01

Aim We investigated whether moxifloxacin-induced QTc prolongations in Japanese and Caucasian healthy male volunteers were significantly different. Methods A two period, randomized, crossover, ICH-E14-compliant thorough QT (TQT) study compared placebo-corrected changes in QTc interval from baseline (ΔΔQTcF) and concentration–effect relationships following administration of placebo and 400 mg moxifloxacin to 40 healthy male volunteers from each ethnic population. The point estimates of ΔΔQTcF for each population, and the difference between the two, were calculated at a geometric mean Cmax of moxifloxacin using a linear mixed effects model. The concentration–effect slopes of the two populations were also compared. Equivalence was concluded if the two-sided 90% confidence interval of the difference in ΔΔQTcF was contained within −5 ms to +5 ms limits and the ratio of the slopes was between 0.5 and 2. Results There were no statistically significant differences between the two populations studied, Japanese vs. Caucasians, respectively, for moxifloxacin Cmax (3.27 ± 0.6 vs. 2.98 ± 0.7 µg ml–1), ΔΔQTcF (9.63 ± 1.15 vs. 11.46 ± 1.19 ms at Cmax of 3.07 µg ml–1) and concentration–response slopes (2.58 ± 0.62 vs. 2.34 ± 0.64 ms per µg ml–1). The difference in the two ΔΔQTcF of −1.8 (90% CI −4.6, 0.9) and the ratio of the two slopes (1.1; 90% CI 0.63, 1.82) were within pre-specified equivalence limits. Conclusions Moxifloxacin-induced QTc prolongations did not differ significantly between the Japanese and Caucasian subjects. However, before our findings are more widely generalized, further studies in other populations and with other QT-prolonging drugs are needed to clarify whether inter-ethnic differences in QT sensitivity exist and whether ethnicity of the study population may affect the outcome of a TQT study. PMID:26011050

Comparative Analysis of a Principal Component Analysis-Based and an Artificial Neural Network-Based Method for Baseline Removal.

PubMed

Carvajal, Roberto C; Arias, Luis E; Garces, Hugo O; Sbarbaro, Daniel G

2016-04-01

This work presents a non-parametric method based on a principal component analysis (PCA) and a parametric one based on artificial neural networks (ANN) to remove continuous baseline features from spectra. The non-parametric method estimates the baseline based on a set of sampled basis vectors obtained from PCA applied over a previously composed continuous spectra learning matrix. The parametric method, however, uses an ANN to filter out the baseline. Previous studies have demonstrated that this method is one of the most effective for baseline removal. The evaluation of both methods was carried out by using a synthetic database designed for benchmarking baseline removal algorithms, containing 100 synthetic composed spectra at different signal-to-baseline ratio (SBR), signal-to-noise ratio (SNR), and baseline slopes. In addition to deomonstrating the utility of the proposed methods and to compare them in a real application, a spectral data set measured from a flame radiation process was used. Several performance metrics such as correlation coefficient, chi-square value, and goodness-of-fit coefficient were calculated to quantify and compare both algorithms. Results demonstrate that the PCA-based method outperforms the one based on ANN both in terms of performance and simplicity. © The Author(s) 2016.

What controls channel form in steep mountain streams?

NASA Astrophysics Data System (ADS)

Palucis, M. C.; Lamb, M. P.

2017-07-01

Steep mountain streams have channel morphologies that transition from alternate bar to step-pool to cascade with increasing bed slope, which affect stream habitat, flow resistance, and sediment transport. Experimental and theoretical studies suggest that alternate bars form under large channel width-to-depth ratios, step-pools form in near supercritical flow or when channel width is narrow compared to bed grain size, and cascade morphology is related to debris flows. However, the connection between these process variables and bed slope—the apparent dominant variable for natural stream types—is unclear. Combining field data and theory, we find that certain bed slopes have unique channel morphologies because the process variables covary systematically with bed slope. Multiple stable states are predicted for other ranges in bed slope, suggesting that a competition of underlying processes leads to the emergence of the most stable channel form.

The Sex and Race Specific Relationship between Anthropometry and Body Fat Composition Determined from Computed Tomography: Evidence from the Multi-Ethnic Study of Atherosclerosis

PubMed Central

Mongraw-Chaffin, Morgana; Golden, Sherita Hill; Allison, Matthew A.; Ding, Jingzhong; Ouyang, Pamela; Schreiner, Pamela J.; Szklo, Moyses; Woodward, Mark; Young, Jeffery Hunter; Anderson, Cheryl A. M.

2015-01-01

Background Few studies have investigated the relationship of anthropometric measurements with computed tomography (CT) body fat composition, and even fewer determined if these relationships differ by sex and race. Methods CT scans from 1,851 participants in the population based Multi-Ethnic Study of Atherosclerosis were assessed for visceral and subcutaneous fat areas by semi-automated segmentation of body compartments. Regression models were used to investigate relationships for anthropometry with visceral and subcutaneous fat separately by sex and race/ethnicity. Results Participants were 50% female, 41% Caucasian, 13% Asian, 21% African American, and 25% Hispanic. For visceral fat, the positive relationship with weight (p = 0.028), waist circumference (p<0.001), waist to hip ratio (p<0.001), and waist to height ratio (p = 0.05) differed by sex, with a steeper slope for men. That is, across the range of these anthropometric measures the rise in visceral fat is faster for men than for women. Additionally, there were differences by race/ethnicity in the relationship with height (p<0.001), weight (p<0.001), waist circumference (p<0.001), hip circumference (p = 0.006), and waist to hip ratio (p = 0.001) with the Hispanic group having shallower slopes. For subcutaneous fat, interaction by sex was found for all anthropometric indices at p<0.05, but not for race/ethnicity. Conclusion The relationship between anthropometry and underlying adiposity differs by sex and race/ethnicity. When anthropometry is used as a proxy for visceral fat in research, sex-specific models should be used. PMID:26448048

Topographic precursors and geological structures of deep-seated catastrophic landslides caused by Typhoon Talas

NASA Astrophysics Data System (ADS)

Chigira, Masahiro; Tsou, Ching-Ying; Matsushi, Yuki; Hiraishi, Narumi; Matsuzawa, Makoto

2013-11-01

Typhoon Talas crossed the Japanese Islands between 2 and 5 September 2011, causing more than 70 deep-seated catastrophic landslides in a Jurassic to Paleogene-lower Miocene accretion complex. Detailed examination of the topographic features of 10 large landslides before the event, recorded on 1-m DEMs based on airborne laser scanner surveys, showed that all landslides had small scarps near their future crowns prior to the slide, and one landslide had linear depressions along its future crown as precursor topographic features. These scarps and linear depressions were caused by gravitational slope deformation that preceded the catastrophic failure. Although the scarps may have been enlarged by degradation, their sizes relative to the whole slopes suggest that minimal slope deformation had occurred in the period immediately before the catastrophic failure. The scarp ratio, defined as the ratio of length of a scarp to that of the whole slope both measured along the slope line, ranged from 5% to 21%. Careful examination of aerial photographs from another four large landslides, for which no high-resolution DEMs were available, suggested that they also developed scarps at their heads beforehand. Twelve of the 14 landslides we surveyed in the field had sliding surfaces with wedge-shaped discontinuities that consisted of faults and bedding, suggesting that the buildup of pore pressure occurs readily on wedge-shaped discontinuities in a gravitationally deformed rock body. Most of the faults were undulatory and were probably thrust faults that formed during accretion. Other types of gravitational deformation were also active; e.g., flexural toppling and buckling were observed to have preceded one landslide.

The experimental study of matching between centrifugal compressor impeller and diffuser

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

Tamaki, H.; Nakao, H.; Saito, M.

1999-01-01

the centrifugal compressor for a marine use turbocharger with its design pressure ratio of 3.2 was tested with a vaneless diffuser and various vaned diffusers. Vaned diffusers were chosen to cover impeller operating range as broad as possible. The analysis of the static pressure ratio in the impeller and the diffusing system, consisting of the diffuser and scroll, showed that there were four possible combinations of characteristics of impeller pressure ratio and diffusing system pressure ratio. The flow rate, Q{sub P}, where the impeller achieved maximum static pressure ratio, was surge flow rate of the centrifugal compressor determined by themore » critical flow rate. In order to operate the compressor at a rate lower than Q{sub P}, the diffusing system, whose pressure recovery factor was steep negative slope near Q{sub P}, was needed. When the diffuser throat area was less than a certain value, the compressor efficiency deteriorated; however, the compressor stage pressure ratio was almost constant. In this study, by reducing the diffuser throat area, the compressor could be operated at a flow rate less than 40% of its design flow rate. Analysis of the pressure ratio in the impeller and diffusing systems at design and off-design speeds showed that the irregularities in surge line occurred when the component that controlled the negative slope on the compressor stage pressure ratio changed.« less

Assessment of dopamine receptor blockade by neuroleptic drugs in the living human brain

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

Wong, D.F.; Wagner, H.N. Jr.; Coyle, J.

1985-05-01

Positron emission tomography (PET) makes it possible to attempt to relate directly the antipsychotic effect of neuroleptic drugs and their blocking effect on dopamine receptors (D2) in vivo. The authors have examined the ability of haloperidol (HAL) and molindone (MOL) to block the binding of C-11 n-methylspiperone (NMSP) in 6 normal subjects. A dose of 0.05 mg/kg of HAL resulted in a 68% drop in the slope of the caudate/cerebellum (Ca/Cb) vs. time. This slope is related to the rate of specific binding of NMSP to the receptor. A dose response was seen with both drugs. With increasing doses ofmore » HAL from .05 to 0.082 mg/kg, CA/Cb vs. time slope fell from .235 to .156/min. (N=4), progressively. Similarly with increasing doses of MOL of .16-.44 mg/kg slopes decreased from .0335 to .0155/min. (N=4). Similar degrees of post injection Ca/Cb ratio were produced with quantities of MOL and HAL administered in the oral dose ratio of doses 3-5:1 times greater than HAL. This is also the dose ratio at which we found similar dopamine receptor blockade by PET in vivo. A question that arises is why the in vitro affinity of HAL for D2 is 30 times greater than that of MOL in the human brain. The results raise the possibility that MOL metabolites are not only active in blocking D2 but indeed may possibly be more potent than MOL itself. It also helps confirm the site of action of MOL and its in vivo metabolites.« less

Renal outcomes of agalsidase beta treatment for Fabry disease: role of proteinuria and timing of treatment initiation.

PubMed

Warnock, David G; Ortiz, Alberto; Mauer, Michael; Linthorst, Gabor E; Oliveira, João P; Serra, Andreas L; Maródi, László; Mignani, Renzo; Vujkovac, Bojan; Beitner-Johnson, Dana; Lemay, Roberta; Cole, J Alexander; Svarstad, Einar; Waldek, Stephen; Germain, Dominique P; Wanner, Christoph

2012-03-01

The purpose of this study was to identify determinants of renal disease progression in adults with Fabry disease during treatment with agalsidase beta. Renal function was evaluated in 151 men and 62 women from the Fabry Registry who received agalsidase beta at an average dose of 1 mg/kg/2 weeks for at least 2 years. Patients were categorized into quartiles based on slopes of estimated glomerular filtration rate (eGFR) during treatment. Multivariate logistic regression analyses were used to identify factors associated with renal disease progression. Men within the first quartile had a mean eGFR slope of -0.1 mL/min/1.73m(2)/year, whereas men with the most rapid renal disease progression (Quartile 4) had a mean eGFR slope of -6.7 mL/min/1.73m(2)/year. The risk factor most strongly associated with renal disease progression was averaged urinary protein:creatinine ratio (UP/Cr) ≥1 g/g (odds ratio 112, 95% confidence interval (95% CI) 4-3109, P = 0.0054). Longer time from symptom onset to treatment was also associated with renal disease progression (odds ratio 19, 95% CI 2-184, P = 0.0098). Women in Quartile 4 had the highest averaged UP/Cr (mean 1.8 g/g) and the most rapid renal disease progression: (mean slope -4.4 mL/min/1.73m(2)/year). Adults with Fabry disease are at risk for progressive loss of eGFR despite enzyme replacement therapy, particularly if proteinuria is ≥1 g/g. Men with little urinary protein excretion and those who began receiving agalsidase beta sooner after the onset of symptoms had stable renal function. These findings suggest that early intervention may lead to optimal renal outcomes.

Past Decline Versus Current eGFR and Subsequent ESRD Risk.

PubMed

Kovesdy, Csaba P; Coresh, Josef; Ballew, Shoshana H; Woodward, Mark; Levin, Adeera; Naimark, David M J; Nally, Joseph; Rothenbacher, Dietrich; Stengel, Benedicte; Iseki, Kunitoshi; Matsushita, Kunihiro; Levey, Andrew S

2016-08-01

eGFR is a robust predictor of ESRD risk. However, the prognostic information gained from the past trajectory (slope) beyond that of the current eGFR is unclear. We examined 22 cohorts to determine the association of past slopes and current eGFR level with subsequent ESRD. We modeled hazard ratios as a spline function of slopes, adjusting for demographic variables, eGFR, and comorbidities. We used random effects meta-analyses to combine results across studies stratified by cohort type. We calculated the absolute risk of ESRD at 5 years after the last eGFR using the weighted average baseline risk. Overall, 1,080,223 participants experienced 5163 ESRD events during a mean follow-up of 2.0 years. In CKD cohorts, a slope of -6 versus 0 ml/min per 1.73 m(2) per year over the previous 3 years (a decline of 18 ml/min per 1.73 m(2) versus no decline) associated with an adjusted hazard ratio of ESRD of 2.28 (95% confidence interval, 1.88 to 2.76). In contrast, a current eGFR of 30 versus 50 ml/min per 1.73 m(2) (a difference of 20 ml/min per 1.73 m(2)) associated with an adjusted hazard ratio of 19.9 (95% confidence interval, 13.6 to 29.1). Past decline contributed more to the absolute risk of ESRD at lower than higher levels of current eGFR. In conclusion, during a follow-up of 2 years, current eGFR associates more strongly with future ESRD risk than the magnitude of past eGFR decline, but both contribute substantially to the risk of ESRD, especially at eGFR<30 ml/min per 1.73 m(2). Copyright © 2016 by the American Society of Nephrology.

Automatic approach to deriving fuzzy slope positions

NASA Astrophysics Data System (ADS)

Zhu, Liang-Jun; Zhu, A.-Xing; Qin, Cheng-Zhi; Liu, Jun-Zhi

2018-03-01

Fuzzy characterization of slope positions is important for geographic modeling. Most of the existing fuzzy classification-based methods for fuzzy characterization require extensive user intervention in data preparation and parameter setting, which is tedious and time-consuming. This paper presents an automatic approach to overcoming these limitations in the prototype-based inference method for deriving fuzzy membership value (or similarity) to slope positions. The key contribution is a procedure for finding the typical locations and setting the fuzzy inference parameters for each slope position type. Instead of being determined totally by users in the prototype-based inference method, in the proposed approach the typical locations and fuzzy inference parameters for each slope position type are automatically determined by a rule set based on prior domain knowledge and the frequency distributions of topographic attributes. Furthermore, the preparation of topographic attributes (e.g., slope gradient, curvature, and relative position index) is automated, so the proposed automatic approach has only one necessary input, i.e., the gridded digital elevation model of the study area. All compute-intensive algorithms in the proposed approach were speeded up by parallel computing. Two study cases were provided to demonstrate that this approach can properly, conveniently and quickly derive the fuzzy slope positions.

Predicting Fatigue Lives Of Metal-Matrix/Fiber Composites

NASA Technical Reports Server (NTRS)

Bartolotta, Paul A.

1994-01-01

Method of prediction of fatigue lives of intermetallic-matrix/fiber composite parts at high temperatures styled after method of universal slopes. It suffices to perform relatively small numbers of fatigue tests. Data from fatigue tests correlated with tensile-test data by fitting universal-slopes equation to both sets of data. Thereafter, universal-slopes equation used to predict fatigue lives from tensile properties.

Zonation of Landslide-Prone Using Microseismic Method and Slope Analysis in Margoyoso, Magelang

NASA Astrophysics Data System (ADS)

Aditya, Muchamad Reza; Fauqi Romadlon, Arriqo’; Agra Medika, Reymon; Alfontius, Yosua; Delva Jannet, Zukhruf; Hartantyo, Eddy

2018-04-01

Margoyoso Village, Salaman Sub-district, Magelang Regency, Central Java is one of the villages that were included in landslide prone areas. The steep slopes and land use in this village were quite apprehensive. There were fractures with 5 cm in width and a length of 50 m. Moreover, these fractures appeared in the home residents. Although the local government has established a disaster response organization, this village is still not getting adequate information about the landslide prone areas. Based on the description before, we conducted research with geophysical methods and geotechnical analysis to minimize the danger of landslides. The geophysical method used in this research was microseismic method and geotechnical analysis. The microseismic measurement and slope stability analysis at Margoyoso village was a step in analysing the landslide-prone zone boundary. The results of this research indicated that landslide potential areas had a low peak ground acceleration values with a range from 36 gal to 46 gal. Measurement of slope stability indicated that a slope angle values between 55°-78° are a potential landslide slope because the soil in this village has very loose properties so it is very easy to move.

Slope stabilization guide for Minnesota local government engineers.

DOT National Transportation Integrated Search

2017-06-01

This user guide provides simple, costeffective methods for stabilizing locally maintained slopes along roadways in Minnesota. Eight slope stabilization techniques are presented that local government engineers can undertake using locally available ...

Effect of cement injection on sandy soil slope stability, case study: slope in Petang district, Badung regency

NASA Astrophysics Data System (ADS)

Arya, I. W.; Wiraga, I. W.; GAG Suryanegara, I.

2018-01-01

Slope is a part of soil topography formed due to elevation difference from two soil surface. Landslides is frequently occur in natural slope, it is because shear force is greater than shear strength in the soil. There are some factor that influence slope stability such as: rain dissipation, vibration from earthquake, construction and crack in the soil. Slope instability can cause risk in human activity or even threaten human lives. Every years in rainy season, landslides always occur in Indonesia. In 2016, there was some landslide occurred in Bali. One of the most damaging is landslide in Petang district, Badung regency. This landslide caused main road closed entirely. In order to overcome and prevent landslide, a lot of method have been practiced and still looking for more sophisticated method for forecasting slope stability. One of the method to strengthen soil stability is filling the soil pores with some certain material. Cement is one of the material that can be used to fill the soil pores because when it is in liquid form, it can infiltrate into soil pores and fill the gap between soil particles. And after it dry, it can formed a bond with soil particle so that soil become stronger and the slope as well. In this study, it will use experimental method, slope model in laboratory to simulate a real slope behavior in the field. The first model is the slope without any addition of cement. This model will be become a benchmark for the other models. The second model is a slope with improved soil that injects the slope with cement. Injection of cement is done with varying interval distance of injection point is 5 cm and 10 cm. Each slope model will be given a load until the slope collapses. The slope model will also be analyzed with slope stability program. The test results on the improved slope models will be compared with unimproved slope. In the initial test will consist of 3 model. First model is soil without improvement or cement injection, second model is soil with cement injection interval 5 cm and third model is soil with cement injection interval 10 cm. The result is the shear strength (ϕ value) the soil is increase from 32.02° to 47.57°. The increase value of internal friction angle (ϕ) shows that an increase in shear strength of the cement improved soil. While, the value of cohesion (c) is zero indicating there is no cohesion in the soil. This is common for sand soil or sandy soil. The calculation of safety factor with GeoStructural Analysis obtained an increase of safety factor from 0.78 if the soil without cement injection to 1.07 and 1.17 if the soil is injected with cement at a distance of 10 cm and 5 cm.

Delay-slope-dependent stability results of recurrent neural networks.

PubMed

Li, Tao; Zheng, Wei Xing; Lin, Chong

2011-12-01

By using the fact that the neuron activation functions are sector bounded and nondecreasing, this brief presents a new method, named the delay-slope-dependent method, for stability analysis of a class of recurrent neural networks with time-varying delays. This method includes more information on the slope of neuron activation functions and fewer matrix variables in the constructed Lyapunov-Krasovskii functional. Then some improved delay-dependent stability criteria with less computational burden and conservatism are obtained. Numerical examples are given to illustrate the effectiveness and the benefits of the proposed method.

Precision, Reliability, and Effect Size of Slope Variance in Latent Growth Curve Models: Implications for Statistical Power Analysis

PubMed Central

Brandmaier, Andreas M.; von Oertzen, Timo; Ghisletta, Paolo; Lindenberger, Ulman; Hertzog, Christopher

2018-01-01

Latent Growth Curve Models (LGCM) have become a standard technique to model change over time. Prediction and explanation of inter-individual differences in change are major goals in lifespan research. The major determinants of statistical power to detect individual differences in change are the magnitude of true inter-individual differences in linear change (LGCM slope variance), design precision, alpha level, and sample size. Here, we show that design precision can be expressed as the inverse of effective error. Effective error is determined by instrument reliability and the temporal arrangement of measurement occasions. However, it also depends on another central LGCM component, the variance of the latent intercept and its covariance with the latent slope. We derive a new reliability index for LGCM slope variance—effective curve reliability (ECR)—by scaling slope variance against effective error. ECR is interpretable as a standardized effect size index. We demonstrate how effective error, ECR, and statistical power for a likelihood ratio test of zero slope variance formally relate to each other and how they function as indices of statistical power. We also provide a computational approach to derive ECR for arbitrary intercept-slope covariance. With practical use cases, we argue for the complementary utility of the proposed indices of a study's sensitivity to detect slope variance when making a priori longitudinal design decisions or communicating study designs. PMID:29755377

Compositional maps and VIS-IR spectral indicators of Vesta's surface retrieved from VIR hyperspectral data

NASA Astrophysics Data System (ADS)

Filacchione, G.; Ammannito, E.; Coradini, A.; De sanctis, M.; Capaccioni, F.; Tosi, F.; Capria, M. T.; Palomba, E.; Magni, G.; Fonte, S.; Carraro, F.; McSween, H. Y.; Raymond, C. A.; Russell, C. T.; McCord, T. B.; Pieters, C. M.; Sunshine, J. M.; Titus, T. N.; Combe, J.; Dawn Science Team

2011-12-01

In July 2011, VIR-MS, Visible and Infrared Mapping Spectrometer, aboard the Dawn mission has started a systematic exploration of minor planet Vesta from a 5000 km polar orbit (approach phase). Since then, the instrument has returned hyperspectral cubes in the 0.25-5 μm range with both global and regional views of Vesta's surface. Thanks to the high spatial (250 μrad IFOV, corresponding to a 1.25 km/pixel scale from a 5000 km altitude orbit) and spectral resolution (2 nm/band between 0.25-1 μm and 10 nm/band in the 1-5 μm range), VIR has the capabilities to infer the mineralogical composition of the crust, to discriminate among the very different compositional units, to map their distribution across the surface and to correlate composition with geological features. Since the amount of information provided by each VIR pixel is very large (864 channels), we have developed the VIR Mineralogical Tool (VMT) with the scope of measuring some specific spectral quantities which are tuned to identify the different howarditic, eucritic and diogenitic (HED) components of the crust, thanks to laboratory measurements and ground-based observations of HED meteorites. Continuum levels, VIS-IR band ratios, band I-II properties (center, depth, width, asymmetry), spectral slopes and their mutual correlations are among the principal spectral indicators used to infer the crustal basaltic composition. As a general rule for basaltic materials: 1) the ratio of band I/II areas gives the Band Area Ratio (BAR) which is function of the relative abundance of olivine/orthopyroxene; 2) the value of the I Vs. II band depths is an indicator of the composition, allowing to discriminate among HEDs. An alternative method is based on the correlation between band I width and 0.7-1.3 μm slope or the band I depth Vs. the 0.67-0.95 μm slope; 3) the amount of Fs, Wo and Mg is retrieved from the band I center and band II minima wavelengths; 4) the alteration of the surface, induced by weathering processes, is recognizable through the changes on visible and near infrared slopes. Finally, we report about preliminary compositional maps to show the distribution of the different spectral indicators across the surface of Vesta. Dawn's VIR, Visible and Infrared Mapping Spectrometer was provided by ASI, the Italian Space Agency and is managed by INAF, Italy's National Institute for Astrophysics, in collaboration with Selex Galileo, where it was designed and built. Italian coauthors are supported by an ASI grant.

Digestive efficiency, free amino acid pools and quality of growth performance in Atlantic salmon (Salmo salar L.) affected by light regimes and vaccine types.

PubMed

Rungruangsak-Torrissen, Krisna; Sunde, Jan; Berg, Arne Erik; Nordgarden, Ulla; Fjelldal, Per Gunnar; Oppedal, Frode

2009-06-01

This study comprised the results of three different seawater trials using unique combination of techniques to study protease digestive efficiency and growth performance quality to illustrate the effects of light regimes and vaccine types in Atlantic salmon (Salmo salar L.). Fish with higher growth had higher trypsin (T) and chymotrypsin (C) specific activities with higher T/C ratio or slope T/C ratio [calculated from the regression between trypsin (y) and chymotrypsin (x) specific activities] in the pyloric caeca. The T/C ratios indicated fish growth rates over a period of 1-2 months, while the slope T/C ratios indicated fish growth rates at sampling. Adaptation period for adjustment to the new environment of continuous light was 70 days, indicated by the differences in trypsin specific activities and the crossing of slope T/C ratio regressions following with the changes in growth rate directions between the control and the treated group. Vaccine types affected fish vertebral growth, and additional continuous light enhanced the impact of vaccines on fish growth during springtime, indicated by differences in slope T/C ratios. Continuous light stimulated fish growth during winter to spring, when the natural day length was short, without significantly changing white muscle and oocyte qualities in the fish of about 500 g, except for significantly increased white muscle RNA concentration. Continuous light also reduced fish growth rate later during summer, when the natural day length was long, by precedently decreasing the T/C ratio in late spring. Interestingly, plasma levels of free lysine related to tryptic digestion were correlated with trypsin specific activity levels. Continuous light caused higher levels of most free amino acids (FAA) involved in nitrogen metabolism, higher incorporation of essential FAA for protein synthesis, and higher protein turnover rate (free hydroxyproline levels) in both plasma and white muscle. However, continuous light did not affect higher protein content, intracellular buffering capacity and RNA levels in the white muscle of the fish of about 1 kg, probably due to limitation of FAA available for protein synthesis. It is therefore suggested that enhancing fish growth by continuous light stimulation should be accompanied by increasing availability or content of dietary protein (and probably minerals), which in turn would improve the quality of fish growth performance through increasing fillet protein concentration, strengthening vertebral growth, and delaying oocyte development.

Integrating concepts and skills: Slope and kinematics graphs

NASA Astrophysics Data System (ADS)

Tonelli, Edward P., Jr.

The concept of force is a foundational idea in physics. To predict the results of applying forces to objects, a student must be able to interpret data representing changes in distance, time, speed, and acceleration. Comprehension of kinematics concepts requires students to interpret motion graphs, where rates of change are represented as slopes of line segments. Studies have shown that majorities of students who show proficiency with mathematical concepts fail accurately to interpret motion graphs. The primary aim of this study was to examine how students apply their knowledge of slope when interpreting kinematics graphs. To answer the research questions a mixed methods research design, which included a survey and interviews, was adopted. Ninety eight (N=98) high school students completed surveys which were quantitatively analyzed along with qualitative information collected from interviews of students (N=15) and teachers ( N=2). The study showed that students who recalled methods for calculating slopes and speeds calculated slopes accurately, but calculated speeds inaccurately. When comparing the slopes and speeds, most students resorted to calculating instead of visual inspection. Most students recalled and applied memorized rules. Students who calculated slopes and speeds inaccurately failed to recall methods of calculating slopes and speeds, but when comparing speeds, these students connected the concepts of distance and time to the line segments and the rates of change they represented. This study's findings will likely help mathematics and science educators to better assist their students to apply their knowledge of the definition of slope and skills in kinematics concepts.

Optimised frequency modulation for continuous-wave optical magnetic resonance sensing using nitrogen-vacancy ensembles.

PubMed

El-Ella, Haitham A R; Ahmadi, Sepehr; Wojciechowski, Adam M; Huck, Alexander; Andersen, Ulrik L

2017-06-26

Magnetometers based on ensembles of nitrogen-vacancy centres are a promising platform for continuously sensing static and low-frequency magnetic fields. Their combination with phase-sensitive (lock-in) detection creates a highly versatile sensor with a sensitivity that is proportional to the derivative of the optical magnetic resonance lock-in spectrum, which is in turn dependant on the lock-in modulation parameters. Here we study the dependence of the lock-in spectral slope on the modulation of the spin-driving microwave field. Given the presence of the intrinsic nitrogen hyperfine spin transitions, we experimentally show that when the ratio between the hyperfine linewidth and their separation is ≳ 1/4, square-wave based frequency modulation generates the steepest slope at modulation depths exceeding the separation of the hyperfine lines, compared to sine-wave based modulation. We formulate a model for calculating lock-in spectra which shows excellent agreement with our experiments, and which shows that an optimum slope is achieved when the linewidth/separation ratio is ≲ 1/4 and the modulation depth is less then the resonance linewidth, irrespective of the modulation function used.

The multi-line slope method for measuring the effective magnetic field of cool stars: an application to the solar-like cycle of ɛ Eri

NASA Astrophysics Data System (ADS)

Scalia, C.; Leone, F.; Gangi, M.; Giarrusso, M.; Stift, M. J.

2017-12-01

One method for the determination of integrated longitudinal stellar fields from low-resolution spectra is the so-called slope method, which is based on the regression of the Stokes V signal against the first derivative of Stokes I. Here we investigate the possibility of extending this technique to measure the magnetic fields of cool stars from high-resolution spectra. For this purpose we developed a multi-line modification to the slope method, called the multi-line slope method. We tested this technique by analysing synthetic spectra computed with the COSSAM code and real observations obtained with the high-resolution spectropolarimeters Narval, HARPSpol and the Catania Astrophysical Observatory Spectropolarimeter (CAOS). We show that the multi-line slope method is a fast alternative to the least squares deconvolution technique for the measurement of the effective magnetic fields of cool stars. Using a Fourier transform on the effective magnetic field variations of the star ε Eri, we find that the long-term periodicity of the field corresponds to the 2.95-yr period of the stellar dynamo, revealed by the variation of the activity index.

Walén test and de Hoffmann-Teller frame of interplanetary large-amplitude Alfvén waves

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

Chao, J. K.; Hsieh, Wen-Chieh; Lee, L. C.

2014-05-10

In this study, three methods of analysis are compared to test the Walén relation. Method 1 requires a good de Hoffmann-Teller (HT) frame. Method 2 uses three components separately to find the frame that is slightly modified from Method 1. This method is intended to improve the accuracy of the HT frame and able to demonstrate the anisotropic property of the fluctuations. The better the relation is, the closer the slope of a regression fitting the data of plasma versus Alfvén velocities is to 1. However, this criterion is based on an average HT frame, and the fitted slope doesmore » not always work for the Walén test because the HT frame can change so fast in the high-speed streams. We propose Method 3 to check the Walén relation using a sequence of data generated by taking the difference of two consecutive values of plasma and Alfvén velocities, respectively. The difference data are independent of the HT frame. We suggest that the ratio of the variances between plasma and Alfvén velocities is a better parameter to qualify the Walén relation. Four cases in two solar wind streams are studied using these three methods. Our results show that when the solar wind HT frame remains stable, all three methods can predict Alfvénic fluctuations well, but Method 3 can better predict the Walén relation when solar wind contains structures with several small streams. A simulated case also demonstrates that Method 3 is better and more robust than Methods 1 and 2. These results are important for a better understanding of Alfvénic fluctuations and turbulence in the solar wind.« less

Rock mass characterisation and stability analyses of excavated slopes

NASA Astrophysics Data System (ADS)

Zangerl, Christian; Lechner, Heidrun

2016-04-01

Excavated slopes in fractured rock masses are frequently designed for open pit mining, quarries, buildings, highways, railway lines, and canals. These slopes can reach heights of several hundreds of metres and in cases concerning open pit mines slopes larger than 1000 m are not uncommon. Given that deep-seated slope failures can cause large damage or even loss of life, the slope design needs to incorporate sufficient stability. Thus, slope design methods based on comprehensive approaches need to be applied. Excavation changes slope angle, groundwater flow, and blasting increases the degree of rock mass fracturing as well as rock mass disturbance. As such, excavation leads to considerable stress changes in the slopes. Generally, slope design rely on the concept of factor of safety (FOS), often a requirement by international or national standards. A limitation of the factor of safety is that time dependent failure processes, stress-strain relationships, and the impact of rock mass strain and displacement are not considered. Usually, there is a difficulty to estimate the strength of the rock mass, which in turn is controlled by an interaction of intact rock and discontinuity strength. In addition, knowledge about in-situ stresses for the failure criterion is essential. Thus, the estimation of the state of stress of the slope and the strength parameters of the rock mass is still challenging. Given that, large-scale in-situ testing is difficult and costly, back-calculations of case studies in similar rock types or rock mass classification systems are usually the methods of choice. Concerning back-calculations, often a detailed and standardised documentation is missing, and a direct applicability to new projects is not always given. Concerning rock mass classification systems, it is difficult to consider rock mass anisotropy and thus the empirical estimation of the strength properties possesses high uncertainty. In the framework of this study an approach based on numerical discrete element modelling (DEM) in combination with limit-equilibrium (LE) methods are presented. The advantage of DEM methods is that failure and displacement of discontinuities and the intact rock for the investigation of failure mechanisms and slope deformations are considered. Furthermore, DEM methods have its strength when rock masses are highly anisotropic and slope failure is structurally controlled. Herein DEM methods are applied to model potential failure geometries, which in turn serve as basis for further investigations by limit-equilibrium methods. LE-methods are used to determine the factor of safety for the pre-defined failure geometries where a sliding mechanism with a discrete and pre-defined basal shear zone is the most likely kinematical failure mode. In this study a parameter variation was performed to find the most reliable FOS based on field estimated strength parameters and the critical strength parameter where a FOS is equal to one (i.e. the lower limit for the parameters). Furthermore, the sensitivity of the shear strength parameters is studied, which enables plausibility checks with field measurements and back-calculated values. The combined approach can help to gain a better insight into failure processes and deformation mechanisms and facilitate to perform a parameter-variation study at a reasonable time frame.

Kaon-nucleus scattering

NASA Technical Reports Server (NTRS)

Hong, Byungsik; Maung, Khin Maung; Wilson, John W.; Buck, Warren W.

1989-01-01

The derivations of the Lippmann-Schwinger equation and Watson multiple scattering are given. A simple optical potential is found to be the first term of that series. The number density distribution models of the nucleus, harmonic well, and Woods-Saxon are used without t-matrix taken from the scattering experiments. The parameterized two-body inputs, which are kaon-nucleon total cross sections, elastic slope parameters, and the ratio of the real to the imaginary part of the forward elastic scattering amplitude, are presented. The eikonal approximation was chosen as our solution method to estimate the total and absorptive cross sections for the kaon-nucleus scattering.

Impact of vegetation on stability of slopes subjected to rainfall - numerical aspect

NASA Astrophysics Data System (ADS)

Switala, Barbara Maria; Tamagnini, Roberto; Sudan Acharya, Madhu; Wu, Wei

2015-04-01

Recent years brought a significant development of soil bioengineering methods, considered as an ecological and economically effective measure for slope stabilization. This work aims to show the advantages of the soil bioengineering solutions for a slope subjected to a heavy rainfall, with the help of a numerical model, which integrates most of the significant plant and slope features. There are basically two different ways in which vegetation can affect stability of a slope: root reinforcement (mechanical impact) and root water uptake (evapotranspiration). In the numerical model, the first factor is modelled using the Cam-Clay model extended for unsaturated conditions by Tamagnini (2004). The original formulation of a constitutive model is modified by introducing an additional constitutive parameter, which causes an expansion of the yield surface as a consequence of an increase in root mass in a representative soil element. The second factor is the root water uptake, which is defined as a volumetric sink term in the continuity equation of groundwater flow. Water removal from the soil mass causes an increase in suction in the vicinity of the root zone, which leads to an increase in the soil cohesion and provides additional strength to the soil-root composite. The developed numerical model takes into account the above mentioned effects of plants and thus considers the multi-phase nature of the soil-plant-water relationship. Using the developed method, stability of some vegetated and non-vegetated slopes subjected to rainfall are investigated. The performance of each slope is evaluated by the time at which slope failure occurs. Different slope geometries and soil mechanical and hydrological properties are considered. Comparison of the results obtained from the analyses of vegetated and non-vegetated slopes leads to the conclusion, that the use of soil bioengineering methods for slope stabilization can be effective and can significantly delay the occurrence of a rainfall induced landslide. On the contrary, vegetation removal can have serious consequences, especially on steep and forested slopes.

Geometric effects on mixing performance in a novel passive micromixer with trapezoidal-zigzag channels

NASA Astrophysics Data System (ADS)

Le The, Hai; Ta, Bao Quoc; Le Thanh, Hoa; Dong, Tao; Nguyen Thoi, Trung; Karlsen, Frank

2015-09-01

A novel passive micromixer, called a trapezoidal-zigzag micromixer (TZM), is reported. A TZM is composed of trapezoidal channels in a zigzag and split-recombine arrangement that enables multiple mixing mechanisms, including splitting-recombining, twisting, transversal flows, vortices, and chaotic advection. The effects of geometric parameters of the TZM on mixing performance are systematically investigated by the Taguchi method and numerical simulations in COMSOL Multiphysics. The number of mixing units, the slope angle of the trapezoidal channel, the height of the constriction element, and the width ratio between the middle-trapezoidal channel and the side-trapezoidal channel are the four parameters under study. The mixing performance of the TZM is investigated at three different Reynolds number (Re) values of 0.5, 5, and 50. The results showed that a TZM with six mixing units, a trapezoidal slope angle of 75°, a constricting height of 100 µm, and a width ratio of 0.5 has the highest mixing efficiency. This optimal TZM has a mixing efficiency greater than 85% for Re values from 0.1 to 80. In particular, for Re  ⩽  0.9 and Re  ⩾  20, the mixing efficiency of the optimal TZM is greater than 90%. The proposed TZM has a higher mixing efficiency and a smaller footprint than previously reported micromixers.

Left ventricular early diastolic inflow velocity and atrial ventricular plane downward velocity: useful parameters to test diastolic function in clinical practice? Diastolic parameters tested in a clinical setting.

PubMed

Winter, R; Gudmundsson, P; Ericsson, G; Willenheimer, R

2001-06-01

To study the clinical value of the colour-M-mode slope of the early diastolic left ventricular filling phase (Vp) and the early diastolic downward M-mode slope of the left atrioventricular plane displacement (EDS), compared with diastolic function assessed by traditional Doppler evaluation. In 65 consecutive patients EDS and Vp were compared with a four-degree traditional diastolic function classification, based on pulsed Doppler assessment of the early to atrial transmitral flow ratio (E/A), the E-wave deceleration time (Edt), and the systolic to diastolic (S/D) pulmonary venous inflow ratio. Vp (P=0.006) and EDS (P=0.045) were related to traditional diastolic function (Kruskal--Wallis analysis). EDS showed a trend brake between the moderate and severe diastolic dysfunction groups by traditional Doppler evaluation. Vp and EDS correlated weakly in simple linear regression analysis (r=0.33). Vp and EDS discriminated poorly between normal and highly abnormal diastolic function. Vp and EDS were significantly related to diastolic function by traditional Doppler evaluation. They were, however, not useful as single parameters of left ventricular diastolic function due to a small difference between normal and highly abnormal values, allowing for little between-measurement variability. Consequently, these methods for the evaluation of left ventricular diastolic function do not add significantly to traditional Doppler evaluation.

Site response variation due to the existence of near-field cracks based on strong motion records in the Shi-Wen river valley, southern Taiwan

NASA Astrophysics Data System (ADS)

Wu, Chi-Shin; Yu, Teng-To; Peng, Wen-Fei; Yeh, Yeoin-Tein; Lin, Sih-Siao

2014-10-01

Site effect analysis has been applied to investigate soil classification, alluvium depth, and fracture detection, although the majority of previous studies have typically focused only on the response of large-scale single structures. In contrast, we investigated the site effect for small-scale cracks using a case study in southern Taiwan to provide a means of monitoring slope stability or foundation integrity in situ using only an accelerometer. We adopted both the reference site and horizontal-to-vertical spectral ratio methods. We obtained seismographs associated with the typhoon-related development of a crack set (52 m long, 5 m deep) in a steep slope and compared the resonance frequency between two conditions (with and without cracks). Moreover, we divided the seismic waves into P, S, and coda waves and examined the seismic source effect. Our results demonstrate that frequencies of 14.5-17.5 Hz are most sensitive to these cracks, particularly for the E-W component of the P-waves, which coincides with the crack’s strike. Peak ground acceleration, which is controlled by seismic moment and attenuated distance, is another important factor determining the resonance results. Our results demonstrate that the ratio of temporal seismic waves can be used to detect the existence of nearby subsurface cracks.

Blood perfusion and pH monitoring in organs by laser-induced fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Vari, Sandor G.; Papazoglou, Theodore G.; Pergadia, Vani R.; Stavridi, Marigo; Snyder, Wendy J.; Papaioannou, Thanassis; Duffy, J. T.; Weiss, Andrew B.; Thomas, Reem; Grundfest, Warren S.

1994-01-01

Sensitivity of laser-induced fluorescence spectroscopy (LIFS) in detecting a change in tissue pH, and blood perfusion was determined. Rabbits were anesthetized, paralyzed, and mechanically ventilated. The arterial and venous blood supplies of the kidney were isolated and ligated to alter the perfusion. The femoral artery was cannulated to extract samples for blood gas analysis. A 308-nm XeCl was used as an excitation source. A 600 micrometers core diameter fiber was used for fluorescence acquisition, and the spectra analyzed by an optical multichannel analyzer (EG & G, OMA III). the corresponding intensity ratio R equals INADH / ICOLL was used as an index for respiratory acidosis. Blood perfusion was assessed using the following algorithm: (IELAS minus ICOLL) divided by (INADH minus ICOLL). The intensity ratio linearly decreased with the reduction of blood perfusion. When we totally occluded the artery the ratio decreased tenfold when compared to the ratio of a fully perfused kidney. Results of monitoring blood acidosis by laser-induced fluorescence spectroscopy shows a significant trend between pH and intensity ratio. Since all the slopes were negative, there is an obvious significant correlation between the pH and NADH.COLLAGEN RATIO. Blue-light-induced fluorescence measurements and ratio fluorometry is a sensitive method for monitoring blood perfusion and acidity or alkalinity of an organ.

Integrated Modeling and Analysis of Physical Oceanographic and Acoustic Processes

DTIC Science & Technology

2014-09-30

dependence of the energy conversion on the ratio of the IW beam slope to the topographic slope, SIW /Stopo. The top panel of Fig. 8 illustrates that...in the abyssal oceans, where typically SIW /Stopo > 1 for tall seamounts and ridges, the entire bottom topography contributes to the generation of...internal waves. In contrast, for (a) (b) 18 moderate ocean depths (say less than 4 km), where typically SIW /Stopo < 1 for seamounts and ridges, the

Finite Element analyses of soil bioengineered slopes

NASA Astrophysics Data System (ADS)

Tamagnini, Roberto; Switala, Barbara Maria; Sudan Acharya, Madhu; Wu, Wei; Graf, Frank; Auer, Michael; te Kamp, Lothar

2014-05-01

Soil Bioengineering methods are not only effective from an economical point of view, but they are also interesting as fully ecological solutions. The presented project is aimed to define a numerical model which includes the impact of vegetation on slope stability, considering both mechanical and hydrological effects. In this project, a constitutive model has been developed that accounts for the multi-phase nature of the soil, namely the partly saturated condition and it also includes the effects of a biological component. The constitutive equation is implemented in the Finite Element (FE) software Comes-Geo with an implicit integration scheme that accounts for the collapse of the soils structure due to wetting. The mathematical formulation of the constitutive equations is introduced by means of thermodynamics and it simulates the growth of the biological system during the time. The numerical code is then applied in the analysis of an ideal rainfall induced landslide. The slope is analyzed for vegetated and non-vegetated conditions. The final results allow to quantitatively assessing the impact of vegetation on slope stability. This allows drawing conclusions and choosing whenever it is worthful to use soil bioengineering methods in slope stabilization instead of traditional approaches. The application of the FE methods show some advantages with respect to the commonly used limit equilibrium analyses, because it can account for the real coupled strain-diffusion nature of the problem. The mechanical strength of roots is in fact influenced by the stress evolution into the slope. Moreover, FE method does not need a pre-definition of any failure surface. FE method can also be used in monitoring the progressive failure of the soil bio-engineered system as it calculates the amount of displacements and strains of the model slope. The preliminary study results show that the formulated equations can be useful for analysis and evaluation of different soil bio-engineering methods of slope stabilization.

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.

Analysis of real-time numerical integration methods applied to dynamic clamp experiments.

PubMed

Butera, Robert J; McCarthy, Maeve L

2004-12-01

Real-time systems are frequently used as an experimental tool, whereby simulated models interact in real time with neurophysiological experiments. The most demanding of these techniques is known as the dynamic clamp, where simulated ion channel conductances are artificially injected into a neuron via intracellular electrodes for measurement and stimulation. Methodologies for implementing the numerical integration of the gating variables in real time typically employ first-order numerical methods, either Euler or exponential Euler (EE). EE is often used for rapidly integrating ion channel gating variables. We find via simulation studies that for small time steps, both methods are comparable, but at larger time steps, EE performs worse than Euler. We derive error bounds for both methods, and find that the error can be characterized in terms of two ratios: time step over time constant, and voltage measurement error over the slope factor of the steady-state activation curve of the voltage-dependent gating variable. These ratios reliably bound the simulation error and yield results consistent with the simulation analysis. Our bounds quantitatively illustrate how measurement error restricts the accuracy that can be obtained by using smaller step sizes. Finally, we demonstrate that Euler can be computed with identical computational efficiency as EE.

Charged kaon and pion production at midrapidity in proton-nucleus and sulphur-nucleus collisions

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

Bo /ggild, H.; Hansen, K.H.; Boissevain, J.

1999-01-01

The NA44 Collaboration has measured charged kaon and pion distributions at midrapidity in sulphur and proton collisions with nuclear targets at 200 and 450 GeV/c per nucleon, respectively. The inverse slopes of kaons, are larger than those of pions. The difference in the inverse slopes of pions, kaons, and protons, all measured in our spectrometer, increases with system size and is consistent with the buildup of collective flow for larger systems. The target dependence of both the yields and inverse slopes is stronger for the sulphur beam, suggesting the increased importance of secondary rescattering for SA reactions. The rapidity densitymore » dN/dy of both K{sup +} and K{sup {minus}} increases more rapidly with system size than for {pi}{sup +} in a similar rapidity region. This trend continues with increasing centrality, and according to RQMD, it is caused by secondary reactions between mesons and baryons. The K{sup {minus}}/K{sup +} ratio falls with increasing system size but more slowly than the {bar p}/p ratio. The {pi}{sup {minus}}/{pi}{sup +} ratio is close to unity for all systems. From pBe to SPb the K{sup +}/p ratio decreases while K{sup {minus}}/{bar p} increases and {radical} ((K{sup +}{center_dot}K{sup {minus}})/(p{center_dot}{bar p})) stays constant. These data suggest that as larger nuclei collide, the resulting system has a larger transverse expansion and baryon density and an increasing fraction of strange quarks. {copyright} {ital 1999} {ital The American Physical Society}« less

/sup 99m/Tc-fibrinogen scanning in adult respiratory distress syndrome

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

Quinn, D.A.; Carvalho, A.C.; Geller, E.

1987-01-01

Fibrin is often seen occluding the lung vessels of patients dying from ARDS and is surrounded by regions of lung necrosis. To learn if we could observe increased or focal fibrin deposition and assess the kinetics of plasma fibrinogen turnover during severe acute respiratory failure, we injected technetium 99m-labeled human purified fibrinogen (Tc-HF) and used gamma camera scanning for as long as 12 h in 13 sequential patients as soon as possible after ICU admission. The fibrinogen uptake rates were determined by calculating the lung:heart radioactivity ratios at each time point. Slopes of the lung:heart ratio versus time were comparedmore » between ARDS and mild acute respiratory failure (ARF). The slope of the lung:heart Tc-HF ratio of the 9 patients with ARDS (2.9 +/- 0.4 units) was markedly higher (p less than 0.02) than the slope of the 4 patients with mild ARF (1.1 +/- 0.4) and the 3 patients studied 5 to 9 months after recovery from respiratory failure (0.7 +/- 0.07). In the 1 patient with ARDS and the 2 patients with mild ARF studied both during acute lung injury and after recovery, the lung:heart Tc-HF ratio had decreased at recovery. To compare the pulmonary uptake of Tc-HF to /sup 99m/Tc-labeled human serum albumin (Tc-HSA), 5 patients were injected with 10 mCi of Tc-HSA, and scanning of the thorax was performed with a similar sequential imaging protocol 24 h after conclusion of the Tc-HF study.« less

Bioavailability of zinc in two zinc sulfate by-products of the galvanizing industry.

PubMed

Edwards, H M; Boling, S D; Emmert, J L; Baker, D H

1998-10-01

Two Zn depletion/repletion assays were conducted with chicks to determine the relative bioavailability (RBV) of Zn from two new by-products of the galvanizing industry. Using a soy concentrate-dextrose diet, slope-ratio methodology was employed to evaluate two different products: Fe-ZnSO4 x H2O with 20.2% Fe and 13.0% Zn, and Zn-FeSO4 x H2O with 14.2% Fe and 20.2% Zn. Feed-grade ZnSO4 x H2O was used as a standard. Weight gain, tibia Zn concentration, and total tibia Zn responded linearly (P < 0.01) to Zn supplementation from all three sources. Slope-ratio calculations based on weight gain established average Zn RBV values of 98% for Fe-ZnSO4 x H2O and 102% for Zn-FeSO4 x H2O, and these values were not different (P > 0.10) from the ZnSO4 standard (100%). Slope-ratio calculations based on total tibia Zn established average Zn RBV values of 126% for Fe-ZnSO4 x H2O and 127% for Zn-FeSO4 x H2O, and these values were greater (P < 0.01) than those of the ZnSO4 standard (100%). It is apparent that both mixed sulfate products of Fe and Zn are excellent sources of bioavailable Zn.

Charged kaon ratios and yields measured with the STAR detector at the Relativistic Heavy Ion Collider

NASA Astrophysics Data System (ADS)

Kunz, Christopher Lee

The mid-rapidity charged kaon ratios and yields are reported for the 200 AGeV Au+Au, 130 AGeV Au+Au, and 200 GeV pp data sets. The K -/K+ ratios are shown to be flat as a function of rapidity, transverse momentum, and centrality for the ranges investigated. The integrated ratios are 0.928 +/- 0.0028 (stat.) +/- 0.03 (sys.), 0.953 +/- 0.0.0012 (stat.) +/- 0.01 (sys.), and 0.964 +/- 0.0039 (stat.) +/- 0.01 (sys.) for 130 AGeV Au+Au, 200 AGeV Au+Au, and 200 GeV pp respectively. Thermal fits are applied to the ratios to extract the baryo-chemical potential and chemical freeze-out temperature. The baryo-chemical potential, as well as the kaon ratio, suggest that the net-baryon density at mid-rapidity is approaching zero at RHIC energies. A quark coalescence model suggests quark degrees of freedom are important in the formation of the ratios. The corrected yields are fit with an exponential in mt and the dN/dy and inverse slope parameter are extracted. The inverse slope parameter is used along with the average collective flow velocity in a simple relationship to extract the thermal freeze-out temperature. A more sophisticated hydrodynamically motivated fit, using pion, kaon, and proton data, shows agreement with the trend from this simple relationship.

Hillslope-Riparian-Streamflow Interactions in a Discontinuous Permafrost Alpine Environment

NASA Astrophysics Data System (ADS)

Carey, S. K.

2004-12-01

Hillslope-riparian-streamflow interactions are poorly characterized in mountainous discontinuous permafrost environments. Permafrost underlain soils have a distinct soil profile, characterized by thick near-surface organic horizons atop ice-rich mineral substrates, whereas slopes without permafrost have thinner or absent organic soils overlying well drained mineral horizons. Riparian areas occur at the base of both seasonally frozen and permafrost slopes, yet a stronger hydrologic and soil transition occurs at slope bases with only seasonal frost. In a subarctic alpine catchment within the Wolf Creek Research Basin, Yukon, Canada, experiments were conducted between 2001 and 2003 to evaluate linkages along the slope-riparian-stream continuum during melt and post-melt periods. Water table, hydraulic head, stable isotope (d2H, d18O) and simple geochemical (pH, SpC, DOC) data were collected along transects during melt and summer periods. In soils with only seasonal frost, there was a downward piezometric gradient in slopes and upward gradient in riparian areas during melt. In contrast, permafrost soils did not show a recharge/discharge gradient between the slope and riparian zone. DOC declined and SpC increased with depth at all sites during melt. DOC was lower in riparian zones and areas without organic soils. SpC declined in soils as dilute meltwater entered the soil, yet it was difficult to establish spatial relations due to differences in melt timing. The similarity in stable isotope composition among sites indicated that the slopes were well flushed with snowmelt water to depth. DOC in streamflow was greatest on the ascending freshet hydrograph, and declined rapidly following melt. Streamflow SpC declined dramatically in response to dilute meltwater inputs and a decline in stream pH indicates flowpaths through organic horizons. Following melt, DOC concentrations declined rapidly in both slopes and riparian areas. In summer, water tables lowered in seasonally frozen slopes, yet an upward hydraulic gradient and near-surface water table was maintained in the riparian area. In permafrost slopes, water tables fell into mineral soils, increasing SpC and reducing DOC. Riparian water tables remained high and DOC was greater than the seasonally frozen soils, yet riparian zone hydraulic gradient reversed suggesting a small recharge gradient. In permafrost soil, riparian zone DOC was an order of magnitude higher than seasonally frozen riparian zones, which had DOC concentrations similar to streamflow. The similarity in stable isotope ratios among sites throughout the summer indicated that soil waters were dominated by water supplied during melt period. Rainfall waters had little long-term effect on slope and riparian isotopic ratios. Mixing analysis of geochemical and isotopic parameters indicates that during melt, most water was supplied via near surface organic layers, whereas later in the year, subsurface pathways predominated. Permafrost slope-riparian zones have a different hydraulic and geochemical interaction than seasonally frozen ones, yet their respective contribution to streamflow during different times of the year remains unclear at this time.

HAWC+/SOFIA observations of Rho Oph A: far-infrared polarization spectrum

NASA Astrophysics Data System (ADS)

Santos, Fabio; Dowell, Charles D.; Houde, Martin; Looney, Leslie; Lopez-Rodriguez, Enrique; Novak, Giles; Ward-Thompson, Derek; HAWC+ Science Team

2018-01-01

In this work, we present preliminary results from the HAWC+ far-infrared polarimeter that operates on the SOFIA airborne observatory. The densest portions of the Rho Ophiuchi molecular complex, known as Rho Oph A, have been mapped using HAWC+ bands C (89 microns) and D (155 microns). Rho Oph A is a well known nearby star forming region. At the target's distance of approximately 130 pc, our observations provide excellent spatial resolution (~5 mpc in band C).The magnetic field map suggests a compressed and distorted field morphology around Oph S1, a massive B3 star that is the main heat source of Rho Oph A. We compute the ratio p(D)/p(C), where p(C) and p(D) are the polarization degree maps at bands C and D, respectively. This ratio estimates the slope of the polarization spectrum in the far-infrared. Although the slope is predicted to be positive by dust grain models, previous observations of other molecular clouds have revealed that negative slopes are common. In Rho Oph A, we find that there is a smooth gradient of p(D)/p(C) across the mapped field. The change in p(D)/p(C) is well correlated with the integrated NH3 (1,1) emission. A positive slope dominates the lower density and well illuminated portions of the cloud, whereas a transition to a negative slope is observed at the denser and less evenly illuminated cloud core.We interpret the positive to negative slope transition as being consistent with the radiative torques (RATs) grain alignment theory. For the sight lines of higher column density, polarized emission from the warmer outer cloud layers is added to emission from the colder inner well-shielded layers lying along the same line-of-sight. Given that the outer layers receive more radiation from Oph S1, their grain alignment efficiency is expected to be higher according to RATs. The combination of warmer, well aligned grains with cooler, poorly aligned grains is what causes the negative slope. This effect is not present in the sight lines of lower column density, due to the much lower extinction.

Instability risk assessment of construction waste pile slope based on fuzzy entropy

NASA Astrophysics Data System (ADS)

Ma, Yong; Xing, Huige; Yang, Mao; Nie, Tingting

2018-05-01

Considering the nature and characteristics of construction waste piles, this paper analyzed the factors affecting the stability of the slope of construction waste piles, and established the system of the assessment indexes for the slope failure risks of construction waste piles. Based on the basic principles and methods of fuzzy mathematics, the factor set and the remark set were established. The membership grade of continuous factor indexes is determined using the "ridge row distribution" function, while that for the discrete factor indexes was determined by the Delphi Method. For the weight of factors, the subjective weight was determined by the Analytic Hierarchy Process (AHP) and objective weight by the entropy weight method. And the distance function was introduced to determine the combination coefficient. This paper established a fuzzy comprehensive assessment model of slope failure risks of construction waste piles, and assessed pile slopes in the two dimensions of hazard and vulnerability. The root mean square of the hazard assessment result and vulnerability assessment result was the final assessment result. The paper then used a certain construction waste pile slope as the example for analysis, assessed the risks of the four stages of a landfill, verified the assessment model and analyzed the slope's failure risks and preventive measures against a slide.

Slope stability analysis using limit equilibrium method in nonlinear criterion.

PubMed

Lin, Hang; Zhong, Wenwen; Xiong, Wei; Tang, Wenyu

2014-01-01

In slope stability analysis, the limit equilibrium method is usually used to calculate the safety factor of slope based on Mohr-Coulomb criterion. However, Mohr-Coulomb criterion is restricted to the description of rock mass. To overcome its shortcomings, this paper combined Hoek-Brown criterion and limit equilibrium method and proposed an equation for calculating the safety factor of slope with limit equilibrium method in Hoek-Brown criterion through equivalent cohesive strength and the friction angle. Moreover, this paper investigates the impact of Hoek-Brown parameters on the safety factor of slope, which reveals that there is linear relation between equivalent cohesive strength and weakening factor D. However, there are nonlinear relations between equivalent cohesive strength and Geological Strength Index (GSI), the uniaxial compressive strength of intact rock σ ci , and the parameter of intact rock m i . There is nonlinear relation between the friction angle and all Hoek-Brown parameters. With the increase of D, the safety factor of slope F decreases linearly; with the increase of GSI, F increases nonlinearly; when σ ci is relatively small, the relation between F and σ ci is nonlinear, but when σ ci is relatively large, the relation is linear; with the increase of m i , F decreases first and then increases.

Slope Stability Analysis Using Limit Equilibrium Method in Nonlinear Criterion

PubMed Central

Lin, Hang; Zhong, Wenwen; Xiong, Wei; Tang, Wenyu

2014-01-01

In slope stability analysis, the limit equilibrium method is usually used to calculate the safety factor of slope based on Mohr-Coulomb criterion. However, Mohr-Coulomb criterion is restricted to the description of rock mass. To overcome its shortcomings, this paper combined Hoek-Brown criterion and limit equilibrium method and proposed an equation for calculating the safety factor of slope with limit equilibrium method in Hoek-Brown criterion through equivalent cohesive strength and the friction angle. Moreover, this paper investigates the impact of Hoek-Brown parameters on the safety factor of slope, which reveals that there is linear relation between equivalent cohesive strength and weakening factor D. However, there are nonlinear relations between equivalent cohesive strength and Geological Strength Index (GSI), the uniaxial compressive strength of intact rock σ ci, and the parameter of intact rock m i. There is nonlinear relation between the friction angle and all Hoek-Brown parameters. With the increase of D, the safety factor of slope F decreases linearly; with the increase of GSI, F increases nonlinearly; when σ ci is relatively small, the relation between F and σ ci is nonlinear, but when σ ci is relatively large, the relation is linear; with the increase of m i, F decreases first and then increases. PMID:25147838

A rapid method for soil cement design : Louisiana slope value method : part II : evaluation.

DOT National Transportation Integrated Search

1966-05-01

This report is an evaluation of the recently developed "Louisiana Slope Value Method". : The conclusion drawn are based on data from 637 separate samples representing nearly all major soil groups in Louisiana that are suitable for cement stabilizatio...

Effects of V2O5/Au bi-layer electrodes on the top contact Pentacene-based organic thin film transistors

NASA Astrophysics Data System (ADS)

Borthakur, Tribeni; Sarma, Ranjit

2017-05-01

Top-contact Pentacene-based organic thin film transistors (OTFTs) with a thin layer of Vanadium Pent-oxide between Pentacene and Au layer are fabricated. Here we have found that the devices with V2O5/Au bi-layer source-drain electrode exhibit better field-effect mobility, high on-off ratio, low threshold voltage and low sub-threshold slope than the devices with Au only. The field-effect mobility, current on-off ratio, threshold voltage and sub-threshold slope of V2O5/Au bi-layer OTFT estimated from the device with 15 nm thick V2O5 layer is .77 cm2 v-1 s-1, 7.5×105, -2.9 V and .36 V/decade respectively.

Analysis of the effects of gravity and wall thickness in a model of blood flow through axisymmetric vessels.

PubMed

Payne, S J

2004-11-01

The effects of gravitational forces and wall thickness on the behaviour of a model of blood flow through axisymmetric vessels were studied. The governing fluid dynamic equations were derived from the Navier-Stokes equations for an incompressible fluid and linked to a simple model of the vessel wall. A closed form of the hyperbolic partial differential equations was found, including a significant source term from the gravitational forces. The inclination of the vessel is modelled using a slope parameter that varied between -1 and 1. The wave speed was shown to be related to the wall thickness, and the time to first shock formation was shown to be directly proportional to this thickness. Two non-dimensional parameters were derived for the ratio of gravitational forces to viscous and momentum forces, respectively, and their values were calculated for the different types of vessel found in the human vasculature, showing that gravitational forces were significant in comparison with either viscous or momentum forces for every type of vessel. The steady-state solution of the governing equations showed that gravitational forces cause an increase in area of approximately 5% per metre per unit slope. Numerical simulations of the flow field in the aorta showed that a positive slope causes a velocity pulse to change in amplitude approximately linearly with distance: -4% per metre and +5% per metre for vessels inclined vertically upwards and downwards, respectively, in comparison with only +0.5% for a horizontal vessel. These simulations also showed that the change relative to the zero slope condition in the maximum rate of change of area with distance, which was taken to be a measure of the rate of shock formation, is proportional to both the slope and the wall thickness-to-inner radius ratio, with a constant of proportionality of 1.2. At a ratio of 0.25, typical of that found in human arteries, the distance to shock formation is thus decreased and increased by 30% for vessels inclined vertically downwards and upwards, respectively. Gravity and wall thickness thus have a significant impact on a number of aspects of the fluid and wall behaviour, despite conventionally being neglected.

Cervical Alignment Variations in Different Postures and Predictors of Normal Cervical Kyphosis: A New Understanding.

PubMed

Hey, Hwee Weng Dennis; Lau, Eugene Tze-Chun; Wong, Gordon Chengyuan; Tan, Kimberly-Anne; Liu, Gabriel Ka-Po; Wong, Hee-Kit

2017-11-01

Comparative study of prospectively collected radiographic data. To predict physiological alignment of the cervical spine and study its morphology in different postures. There is increasing evidence that normal cervical spinal alignment may vary from lordosis to neutral to kyphosis, or form S-shaped or reverse S-shaped curves. Standing, erect sitting, and natural sitting whole-spine radiographs were obtained from 26 consecutive patients without cervical spine pathology. Sagittal vertical axis (SVA), global cervical lordosis, lower cervical alignment C4-T1, C0-C2 angle, T1 slope, C0-C7 SVA and C2-7SVA, SVA, thoracic kyphosis, thoracolumbar junctional angle, lumbar lordosis, sacral slope, pelvic tilt, and pelvic incidence were measured. Statistical analysis was performed to elucidate differences in cervical alignment for all postures. Predictive values of T1 slope and SVA for cervical kyphosis were evaluated. Most patients (73.0%) do not have lordotic cervical alignment (C2-C7) upon standing (mean -0.6, standard deviation 11.1°). Lordosis increases significantly when transitioning from standing to erect sitting, as well as from erect to natural sitting (mean -17.2, standard deviation 12.1°). Transition from standing to natural sitting also produces concomitant increases in SVA (-8.8-65.2 mm) and T1-slope (17.4°-30.2°). T1 slope and SVA measured during standing significantly predicts angular cervical spine alignment in the same position. SVA < 10 mm significantly predicts C4-C7 kyphosis (P < 0.001), and to a lesser extent, C2-C7 kyphosis (P = 0.02). T1 slope <20° is both predictive of C2-C7 and C4-7 kyphosis (P = 0.001 and P = 0.023, respectively). For global cervical Cobb angle, T1 slope seems to be a more significant predictor of kyphosis than SVA (odds ratio 17.33, P = 0.001 vs odds ratio 11.67, P = 0.02, respectively). The cervical spine has variable normal morphology. Key determinants of its alignment include SVA and T1 slope. Lordotic correction of the cervical spine is not always physiological and thus correction targets should be individualized. 3.

Dynamics of Soil Organic Carbon and Microbial Biomass Carbon in Relation to Water Erosion and Tillage Erosion

PubMed Central

Xiaojun, Nie; Jianhui, Zhang; Zhengan, Su

2013-01-01

Dynamics of soil organic carbon (SOC) are associated with soil erosion, yet there is a shortage of research concerning the relationship between soil erosion, SOC, and especially microbial biomass carbon (MBC). In this paper, we selected two typical slope landscapes including gentle and steep slopes from the Sichuan Basin, China, and used the 137Cs technique to determine the effects of water erosion and tillage erosion on the dynamics of SOC and MBC. Soil samples for the determination of 137Cs, SOC, MBC and soil particle-size fractions were collected on two types of contrasting hillslopes. 137Cs data revealed that soil loss occurred at upper slope positions of the two landscapes and soil accumulation at the lower slope positions. Soil erosion rates as well as distribution patterns of the <0.002-mm clay shows that water erosion is the major process of soil redistribution in the gentle slope landscape, while tillage erosion acts as the dominant process of soil redistribution in the steep slope landscape. In gentle slope landscapes, both SOC and MBC contents increased downslope and these distribution patterns were closely linked to soil redistribution rates. In steep slope landscapes, only SOC contents increased downslope, dependent on soil redistribution. It is noticeable that MBC/SOC ratios were significantly lower in gentle slope landscapes than in steep slope landscapes, implying that water erosion has a negative effect on the microbial biomass compared with tillage erosion. It is suggested that MBC dynamics are closely associated with soil redistribution by water erosion but independent of that by tillage erosion, while SOC dynamics are influenced by soil redistribution by both water erosion and tillage erosion. PMID:23717530

Locating Critical Circular and Unconstrained Failure Surface in Slope Stability Analysis with Tailored Genetic Algorithm

NASA Astrophysics Data System (ADS)

Pasik, Tomasz; van der Meij, Raymond

2017-12-01

This article presents an efficient search method for representative circular and unconstrained slip surfaces with the use of the tailored genetic algorithm. Searches for unconstrained slip planes with rigid equilibrium methods are yet uncommon in engineering practice, and little publications regarding truly free slip planes exist. The proposed method presents an effective procedure being the result of the right combination of initial population type, selection, crossover and mutation method. The procedure needs little computational effort to find the optimum, unconstrained slip plane. The methodology described in this paper is implemented using Mathematica. The implementation, along with further explanations, is fully presented so the results can be reproduced. Sample slope stability calculations are performed for four cases, along with a detailed result interpretation. Two cases are compared with analyses described in earlier publications. The remaining two are practical cases of slope stability analyses of dikes in Netherlands. These four cases show the benefits of analyzing slope stability with a rigid equilibrium method combined with a genetic algorithm. The paper concludes by describing possibilities and limitations of using the genetic algorithm in the context of the slope stability problem.

Automated Measurement of Patient-Specific Tibial Slopes from MRI

PubMed Central

Amerinatanzi, Amirhesam; Summers, Rodney K.; Ahmadi, Kaveh; Goel, Vijay K.; Hewett, Timothy E.; Nyman, Edward

2017-01-01

Background: Multi-planar proximal tibial slopes may be associated with increased likelihood of osteoarthritis and anterior cruciate ligament injury, due in part to their role in checking the anterior-posterior stability of the knee. Established methods suffer repeatability limitations and lack computational efficiency for intuitive clinical adoption. The aims of this study were to develop a novel automated approach and to compare the repeatability and computational efficiency of the approach against previously established methods. Methods: Tibial slope geometries were obtained via MRI and measured using an automated Matlab-based approach. Data were compared for repeatability and evaluated for computational efficiency. Results: Mean lateral tibial slope (LTS) for females (7.2°) was greater than for males (1.66°). Mean LTS in the lateral concavity zone was greater for females (7.8° for females, 4.2° for males). Mean medial tibial slope (MTS) for females was greater (9.3° vs. 4.6°). Along the medial concavity zone, female subjects demonstrated greater MTS. Conclusion: The automated method was more repeatable and computationally efficient than previously identified methods and may aid in the clinical assessment of knee injury risk, inform surgical planning, and implant design efforts. PMID:28952547

Optimization of Region of Interest Drawing for Quantitative Analysis: Differentiation Between Benign and Malignant Breast Lesions on Contrast-Enhanced Sonography.

PubMed

Nakata, Norio; Ohta, Tomoyuki; Nishioka, Makiko; Takeyama, Hiroshi; Toriumi, Yasuo; Kato, Kumiko; Nogi, Hiroko; Kamio, Makiko; Fukuda, Kunihiko

2015-11-01

This study was performed to evaluate the diagnostic utility of quantitative analysis of benign and malignant breast lesions using contrast-enhanced sonography. Contrast-enhanced sonography using the perflubutane-based contrast agent Sonazoid (Daiichi Sankyo, Tokyo, Japan) was performed in 94 pathologically proven palpable breast mass lesions, which could be depicted with B-mode sonography. Quantitative analyses using the time-intensity curve on contrast-enhanced sonography were performed in 5 region of interest (ROI) types (manually traced ROI and circular ROIs of 5, 10, 15, and 20 mm in diameter). The peak signal intensity, initial slope, time to peak, positive enhancement integral, and wash-out ratio were investigated in each ROI. There were significant differences between benign and malignant lesions in the time to peak (P < .05), initial slope (P < .001), and positive enhancement integral (P < .05) for the manual ROI. Significant differences were found between benign and malignant lesions in the time to peak (P < .05) for the 5-mm ROI; the time to peak (P < .05) and initial slope (P< .05) for the 10-mm ROI; absolute values of the peak signal intensity (P< .05), time to peak (P< .01), and initial slope (P< .005) for the 15-mm ROI; and the time to peak (P < .05) and initial slope (P < .05) for the 20-mm ROI. There were no statistically significant differences in any wash-out ratio values for the 5 ROI types. Kinetic analysis using contrast-enhanced sonography is useful for differentiation between benign and malignant breast lesions. © 2015 by the American Institute of Ultrasound in Medicine.

The coupled response to slope-dependent basal melting

NASA Astrophysics Data System (ADS)

Little, C. M.; Goldberg, D. N.; Sergienko, O. V.; Gnanadesikan, A.

2009-12-01

Ice shelf basal melting is likely to be strongly controlled by basal slope. If ice shelves steepen in response to intensified melting, it suggests instability in the coupled ice-ocean system. The dynamic response of ice shelves governs what stable morphologies are possible, and thus the influence of melting on buttressing and grounding line migration. Simulations performed using a 3-D ocean model indicate that a simple form of slope-dependent melting is robust under more complex oceanographic conditions. Here we utilize this parameterization to investigate the shape and grounding line evolution of ice shelves, using a shallow-shelf approximation-based model that includes lateral drag. The distribution of melting substantially affects the shape and aspect ratio of unbuttressed ice shelves. Slope-dependent melting thins the ice shelf near the grounding line, reducing velocities throughout the shelf. Sharp ice thickness gradients evolve at high melting rates, yet grounding lines remain static. In foredeepened, buttressed ice shelves, changes in grounding line flux allow two additional options: stable or unstable retreat. Under some conditions, slope-dependent melting results in stable configurations even at high melt rates.

Scintigraphy for Pulmonary Capillary Protein Leak

DTIC Science & Technology

1982-09-01

called this rising ratio the "slope of injury" or "slope index" ýS1). In previous canine oloic acid studies, we have found that the SI was proportional...cannulation. 2. Canine Studios Dogs weighing approximately 20 kg, were anest•:etized with 30 mg/kg sodium pentobarbital, intubated, and ventilated at...SI was seen, analogous to that seen with 0.05 ml/kg ujeic acid and the SI was repro- ducible two hours following lCI. e. Canine Endotoxin Studies: Two

Evaluating the Effect of Rainfall Infiltration on the Slope Stability of T16 tower of Taipei Mao-kong Gondola by Numerical Methods

NASA Astrophysics Data System (ADS)

RUNG, J.

2013-12-01

In this study, a series of rainfall-stability analyses were performed to simulate the failure mechanism and the function of remediation works of the down slope of T-16 tower pier, Mao-Kong gondola (or T-16 Slope) at the hillside of Taipei City using two-dimensional finite element method. The failure mechanism of T-16 Slope was simulated using the rainfall hyetograph of Jang-Mi typhoon in 2008 based on the field investigation data, monitoring data, soil/rock mechanical testing data and detail design plots of remediation works. Eventually, the numerical procedures and various input parameters in the analysis were verified by comparing the numerical results with the field observations. In addition, 48 hrs design rainfalls corresponding to 5, 10, 25 and 50 years return periods were prepared using the 20 years rainfall data of Mu-Zha rainfall observation station, Central Weather Bureau for the rainfall-stability analyses of T-16 Slope to inspect the effect of the compound stabilization works on the overall stability of the slope. At T-16 Slope, without considering the longitudinal and transverse drainages on the ground surface, there totally 4 types of stabilization works were installed to stabilize the slope. From the slope top to the slope toe, the stabilization works of T-16 Slope consists of RC-retaining wall with micro-pile foundation at the up-segment, earth anchor at the up-middle-segment, soil nailing at the middle-segment and retaining pile at the down-segment of the slope. The effect of each individual stabilization work on the slope stability under rainfall condition was examined and evaluated by raising field groundwater level.

[Comparative study of N, P output and eutrophication risk in runoff water in cross ridge and longitudinal ridge].

PubMed

Yu, Xing-Xiu; Ma, Qian; Liu, Qian-Jin; Lü, Guo-An

2011-02-01

Field in-situ rainfall simulation tests with two rainfall intensities (40 mm x h(-1) and 70 mm x h(-1)), which were conducted at typical sloping cropland in Yimeng mountainous area, were designed to analyze the output characteristics of dissolved inorganic nitrogen, Inorganic-N (NO3(-)-N, NH4(+) -N) and dissolved phosphorus (DP) in runoff water, as well as to compare the eutrophication risk in this water by calculating three ratios of Inorganic-N/DP, NO3(-) -N/DP, and NH4(+)-N/DP, respectively, in cross ridge and longitudinal ridge tillage methods. Results showed that, under the same rainfall intensity, the DP level in runoff water was higher in cross ridge than longitudinal ridge, while the change of different Inorganic-N level between the two tillage methods were not consistent. Cross ridge could effectively reduce runoff and the output rate of Inorganic-N and DP when compared to the longitudinal ridge tillage, which would be more outstanding with the increases of rainfall intensities. The losses of Inorganic-N and DP in runoff water were 43% and 5% less, respectively, in cross ridge than longitudinal ridge at the 40 mm x h(-1) rainfall intensity, and were 68% and 55%, respectively, at 70 mm x h(-1). The higher Inorganic-N/DP and NO3(-) -N/DP ratios suggest that runoff water from either cross ridge or longitudinal ridge tillage have a certain eutrophication risk, which present an increasing trend during the precipitation-runoff process. Compared with longitudinal ridge, cross ridge can not only hinder the increasing trend of eutrophication risk, but also can significantly lower it, and thus effectively reduce the effect of sloping cropland runoff on the eutrophication processes of receiving waters.

Characterization of Unstable Rock Slopes Through Passive Seismic Measurements

NASA Astrophysics Data System (ADS)

Kleinbrod, Ulrike; Burjánek, Jan; Fäh, Donat

2014-05-01

Catastrophic rock slope failures have high social impact, causing significant damage to infrastructure and many casualties throughout the world each year. Both detection and characterization of rock instabilities are therefore of key importance. Analysing unstable rock slopes by means of ambient vibrations might be a new alternative to the already existing methods as for example geotechnical displacement measurements. A systematic measurement campaign has been initiated recently in Switzerland in order to study the seismic response of potential rockslides concerning a broad class of slope failure mechanisms and material conditions. First results are presented in this contribution. Small aperture seismic arrays were deployed at sites of interest for a short period of time (several hours) in order to record ambient vibrations. During each measurement a reference station was installed on a stable part close to the instability. The total number of stations used varies from 16 down to 2, depending on the site scope and resource availability. Instable rock slopes show a highly directional ground motion which is significantly amplified with respect to stable areas. These effects are strongest at certain frequencies which are identified as eigenfrequencies of the unstable rock mass. The eigenfrequencies and predominant directions have been estimated by frequency dependent polarization analysis. Site-to-reference spectral ratios have been calculated as well in order to estimate the relative amplification of ground motion at unstable parts. The retrieved results were compared with independent in-situ observations and other available data. The directions of maximum amplification are in most cases perpendicular to open cracks mapped on the surface and in good agreement with the deformation directions obtained by geodetic measurements. The interpretation of the observed wave field is done through numerical modelling of seismic wave propagation in fractured media with complex topography. For example, a potential relation between eigenfrequencies and unstable rock mass volume is investigated.

An improved CeO2 method for high-precision measurements of 17O/16O ratios for atmospheric carbon dioxide.

PubMed

Mahata, Sasadhar; Bhattacharya, Sourandra K; Wang, Chung-Ho; Liang, Mao-Chang

2012-09-15

The oxygen isotopic composition of carbon dioxide originating at the Earth's surface is modified in the stratosphere by interaction with ozone which has anomalous oxygen isotope ratio (Δ(17)O = 1000 * ln(1 + δ(17)O/1000) - 0.522 * 1000 * ln (1 + δ(18)O/1000) >0). The inherited anomaly provides a powerful tracer for studying biogeochemical cycles involving CO(2). However, the existing methods are either too imprecise or have difficulty in determining the small Δ(17)O variations found in the tropospheric CO(2). In this study an earlier published CeO(2) and CO(2) exchange method has been modified and improved for measuring the Δ(17)O values of atmospheric carbon dioxide with high precision. The CO(2) fraction from air samples was separated by cryogenic means and purified using gas chromatography. This CO(2) was first analyzed in an isotope ratio mass spectrometer, then artificially equilibrated with hot CeO(2) to alter its oxygen isotopes mass-dependently and re-analyzed. From these data the (17)O/(16)O and (18)O/(16)O ratios were calculated and the Δ(17)O value was determined. The validity of the method was established in several tests by using artificially prepared CO(2) with zero and non-zero Δ(17)O values. The published value of the CO(2)-H(2) O equilibrium slope was also reproduced. The CO(2)-CeO(2) equilibration method has been improved to measure the oxygen isotope anomaly (Δ(17)O value) of atmospheric CO(2) with an analytical precision of ±0.12‰ (2σ). Copyright © 2012 John Wiley & Sons, Ltd.

Estimation of fast and slow wave properties in cancellous bone using Prony's method and curve fitting.

PubMed

Wear, Keith A

2013-04-01

The presence of two longitudinal waves in poroelastic media is predicted by Biot's theory and has been confirmed experimentally in through-transmission measurements in cancellous bone. Estimation of attenuation coefficients and velocities of the two waves is challenging when the two waves overlap in time. The modified least squares Prony's (MLSP) method in conjuction with curve-fitting (MLSP + CF) is tested using simulations based on published values for fast and slow wave attenuation coefficients and velocities in cancellous bone from several studies in bovine femur, human femur, and human calcaneus. The search algorithm is accelerated by exploiting correlations among search parameters. The performance of the algorithm is evaluated as a function of signal-to-noise ratio (SNR). For a typical experimental SNR (40 dB), the root-mean-square errors (RMSEs) for one example (human femur) with fast and slow waves separated by approximately half of a pulse duration were 1 m/s (slow wave velocity), 4 m/s (fast wave velocity), 0.4 dB/cm MHz (slow wave attenuation slope), and 1.7 dB/cm MHz (fast wave attenuation slope). The MLSP + CF method is fast (requiring less than 2 s at SNR = 40 dB on a consumer-grade notebook computer) and is flexible with respect to the functional form of the parametric model for the transmission coefficient. The MLSP + CF method provides sufficient accuracy and precision for many applications such that experimental error is a greater limiting factor than estimation error.

Co-seismic landslide topographic analysis based on multi-temporal DEM-A case study of the Wenchuan earthquake.

PubMed

Ren, Zhikun; Zhang, Zhuqi; Dai, Fuchu; Yin, Jinhui; Zhang, Huiping

2013-01-01

Hillslope instability has been thought to be one of the most important factors for landslide susceptibility. In this study, we apply geomorphic analysis using multi-temporal DEM data and shake intensity analysis to evaluate the topographic characteristics of the landslide areas. There are many geomorphologic analysis methods such as roughness, slope aspect, which are also as useful as slope analysis. The analyses indicate that most of the co-seismic landslides occurred in regions with roughness, hillslope and slope aspect of >1.2, >30, and between 90 and 270, respectively. However, the intersection regions from the above three methods are more accurate than that derived by applying single topographic analysis method. The ground motion data indicates that the co-seismic landslides mainly occurred on the hanging wall side of Longmen Shan Thrust Belt within the up-down and horizontal peak ground acceleration (PGA) contour of 150 PGA and 200 gal, respectively. The comparisons of pre- and post-earthquake DEM data indicate that the medium roughness and slope increased, the roughest and steepest regions decreased after the Wenchuan earthquake. However, slope aspects did not even change. Our results indicate that co-seismic landslides mainly occurred at specific regions of high roughness, southward and steep sloping areas under strong ground motion. Co-seismic landslides significantly modified the local topography, especially the hillslope and roughness. The roughest relief and steepest slope are significantly smoothed; however, the medium relief and slope become rougher and steeper, respectively.

40 CFR 53.34 - Test procedure for methods for PM10 and Class I methods for PM2.5.

Code of Federal Regulations, 2011 CFR

2011-07-01

... linear regression parameters (slope, intercept, and correlation coefficient) describing the relationship... correlation coefficient. (2) To pass the test for comparability, the slope, intercept, and correlation...

Climate change influence on the internal structure of talus slopes in the Arctic - A case study from the southern Spitsbergen, Norway

NASA Astrophysics Data System (ADS)

Senderak, K.; Kondracka, M.; Gądek, B.

2017-12-01

Talus slopes are present in all geographical altitudes, but the most active and dynamic slopes occur in high-mountain and polar areas. Spitsbergen, Norwegian archipelago in the Arctic, combines these two environments, therefore, the talus slopes develop in specific environmental conditions that have changed since the beginning of deglaciation. On Spitsbergen, which is 60% glaciated, talus slope evolution depends frequently on the interaction with glaciers, as well as the size of sediment supply area, the lithology, and the intensive of rock weathering. The warming of climate in the Arctic cause the identifiable changes in the internal structures of talus slopes associated with i.e. the melting of glaciers and the high activity of many morphogenetic processes on slope surface. The identification of these changes is a key to understanding of climate change influence (direct and indirect influence) on talus slope evolution. Our work presents the results of research, mainly based on the measurements using electrical resistivity tomography method (ERT) and ground-penetrating radar method (GPR), which were made on the talus slopes of southern Spitsbergen in the vicinity of Polish Polar Station in Hornsund. The geophysical surveys and geomorphological observations show that the climatic factor plays the significant role in the development of slopes, what is clearly visible when analyzing the whole slope systems in the selected glacial valleys (partly glaciated). The differences in the internal structure can depend on distance from the glacier and age of form. This mainly concerns the volume of buried glacial ice in slope material, the thickness of talus slopes, the depth of permafrost and active layer, the stored sedimentological structures including e.g. the traces of fresh material supply. New data on the internal structure of talus slopes developing in the present glaciated area allow for discussions on the talus slope evolution, which, according to the authors, needs to be detailed.

Rockfall activity of cliff inferred from deposit and cone method

NASA Astrophysics Data System (ADS)

Jaboyedoff, M.; Baillifard, F.; Rouiller, J.-D.

2003-04-01

Assuming that fresh scree slopes are significant indicators of recent rockfall activity, they can be used as activity indicators for a given rockfall source area. Using simple geometric rules and a DTM (digital elevation model), the propagation zone can be estimated by considering that each potential rockfall source cell (corresponding to the entire cliff) can generate a scree slope within a cone with a slope ranging from 27° to 37°. Thus, the count of pixels representing rockfall deposits that are contained in this cone represents a relative scale of recent rockfall activity. According to Evans and Hungr (1993), the source cell can be chosen at the bottom of the cliff, with lower angles. Choosing the entire cliff or the bottom of the cliff as source area depends on the morphology of the slope situated below the cliff. The cone can also be laterally limited in order to avoid the counting of illogical rock slope trajectories (+-20°). In Switzerland, the vectorized 1:25,000 topographic map (vector25) can provide scree slope and cliff area data sets. Results obtained using this method show good agreement with field observations, although it is evident that the highest topographic reliefs are favored by this method, as verified in the Alps. Compared to the method of Menendéz Duarte and Marquínez (2002), which uses GIS-calculated watersheds as propagation areas, the present method does not take small changes of topography into account. References Evans, S.G. and Hungr, O. The assessment of rockfall hazard at the base of talus slopes. Canadian Geotechnical Journal, 30/4, 620-636, 1993. Menendéz Duarte, R. and Marquínez, J. The influence of environmental and lithologic factors on rockfall at a regional scale: an evaluation using GIS. Geomorphology, 43, 117-136, 2002.

Effect of photogrammetric reading error on slope-frequency distributions. [obtained from Apollo 17 mission

NASA Technical Reports Server (NTRS)

Moore, H. J.; Wu, S. C.

1973-01-01

The effect of reading error on two hypothetical slope frequency distributions and two slope frequency distributions from actual lunar data in order to ensure that these errors do not cause excessive overestimates of algebraic standard deviations for the slope frequency distributions. The errors introduced are insignificant when the reading error is small and the slope length is large. A method for correcting the errors in slope frequency distributions is presented and applied to 11 distributions obtained from Apollo 15, 16, and 17 panoramic camera photographs and Apollo 16 metric camera photographs.

Modeling an internal gear pump

NASA Astrophysics Data System (ADS)

Chen, Zongbin; Xu, Rongwu; He, Lin; Liao, Jian

2018-05-01

Considering the nature and characteristics of construction waste piles, this paper analyzed the factors affecting the stability of the slope of construction waste piles, and established the system of the assessment indexes for the slope failure risks of construction waste piles. Based on the basic principles and methods of fuzzy mathematics, the factor set and the remark set were established. The membership grade of continuous factor indexes is determined using the "ridge row distribution" function, while that for the discrete factor indexes was determined by the Delphi Method. For the weight of factors, the subjective weight was determined by the Analytic Hierarchy Process (AHP) and objective weight by the entropy weight method. And the distance function was introduced to determine the combination coefficient. This paper established a fuzzy comprehensive assessment model of slope failure risks of construction waste piles, and assessed pile slopes in the two dimensions of hazard and vulnerability. The root mean square of the hazard assessment result and vulnerability assessment result was the final assessment result. The paper then used a certain construction waste pile slope as the example for analysis, assessed the risks of the four stages of a landfill, verified the assessment model and analyzed the slope's failure risks and preventive measures against a slide.

A measurement system applicable for landslide experiments in the field.

PubMed

Guo, Wen-Zhao; Xu, Xiang-Zhou; Wang, Wen-Long; Yang, Ji-Shan; Liu, Ya-Kun; Xu, Fei-Long

2016-04-01

Observation of gravity erosion in the field with strong sunshine and wind poses a challenge. Here, a novel topography meter together with a movable tent addresses the challenge. With the topography meter, a 3D geometric shape of the target surface can be digitally reconstructed. Before the commencement of a test, the laser generator position and the camera sightline should be adjusted with a sight calibrator. Typically, the topography meter can measure the gravity erosion on the slope with a gradient of 30°-70°. Two methods can be used to obtain a relatively clear video, despite the extreme steepness of the slopes. One method is to rotate the laser source away from the slope to ensure that the camera sightline remains perpendicular to the laser plane. Another way is to move the camera farther away from the slope in which the measured volume of the slope needs to be corrected; this method will reduce distortion of the image. In addition, installation of tent poles with concrete columns helps to surmount the altitude difference on steep slopes. Results observed by the topography meter in real landslide experiments are rational and reliable.

Reconstruction of the energy and depth of maximum of cosmic-ray air showers from LOPES radio measurements

NASA Astrophysics Data System (ADS)

Apel, W. D.; Arteaga-Velazquez, J. C.; Bähren, L.; Bekk, K.; Bertaina, M.; Biermann, P. L.; Blümer, J.; Bozdog, H.; Brancus, I. M.; Cantoni, E.; Chiavassa, A.; Daumiller, K.; de Souza, V.; di Pierro, F.; Doll, P.; Engel, R.; Falcke, H.; Fuchs, B.; Fuhrmann, D.; Gemmeke, H.; Grupen, C.; Haungs, A.; Heck, D.; Hörandel, J. R.; Horneffer, A.; Huber, D.; Huege, T.; Isar, P. G.; Kampert, K.-H.; Kang, D.; Krömer, O.; Kuijpers, J.; Link, K.; Łuczak, P.; Ludwig, M.; Mathes, H. J.; Melissas, M.; Morello, C.; Oehlschläger, J.; Palmieri, N.; Pierog, T.; Rautenberg, J.; Rebel, H.; Roth, M.; Rühle, C.; Saftoiu, A.; Schieler, H.; Schmidt, A.; Schröder, F. G.; Sima, O.; Toma, G.; Trinchero, G. C.; Weindl, A.; Wochele, J.; Zabierowski, J.; Zensus, J. A.; Lopes Collaboration

2014-09-01

LOPES is a digital radio interferometer located at Karlsruhe Institute of Technology (KIT), Germany, that measures radio emission from extensive air showers at MHz frequencies in coincidence with KASCADE-Grande. In this article, we explore a method (slope method) that leverages the slope of the measured radio lateral distribution to reconstruct crucial attributes of primary cosmic rays. First, we present an investigation of the method on the basis of pure simulations. Second, we directly apply the slope method to LOPES measurements. Applying the slope method to simulations, we obtain uncertainties on the reconstruction of energy and depth of shower maximum (Xmax) of 13% and 50 g /cm2, respectively. Applying it to LOPES measurements, we are able to reconstruct energy and Xmax of individual events with upper limits on the precision of 20%-25% for the primary energy and 95 g /cm2 for Xmax, despite strong human-made noise at the LOPES site.

Model Optimization Planting Pattern Agroforestry Forest Land Based on Pine Tree

ERIC Educational Resources Information Center

Rajati, Tati

2015-01-01

This study aims to determine cropping patterns in class slopes 0 - <15% and the grade slope slopes 15% - <30% and the slopes> 30%. The method used in this study is a description of the dynamic system approach using a software power sim. Forest areas where the research, which is a type of plant that is cultivated by the people in the study…

Comparison of measured and computed Strehl ratios for light propagated through a channel flow of a He N 2 mixing layer at high Reynolds numbers

NASA Astrophysics Data System (ADS)

Gardner, Patrick J.; Roggemann, Michael C.; Welsh, Byron M.; Bowersox, Rodney D.; Luke, Theodore E.

1997-04-01

A lateral shearing interferometer was used to measure the slope of perturbed wave fronts after they propagated through a He N 2 mixing layer in a rectangular channel. Slope measurements were used to reconstruct the phase of the turbulence-corrupted wave front. The random phase fluctuations induced by the mixing layer were captured in a large ensemble of wave-front measurements. Phase structure functions, computed from the reconstructed phase surfaces, were stationary in first increments. A five-thirds power law is shown to fit streamwise and cross-stream slices of the structure function, analogous to the Kolmogorov model for isotropic turbulence, which describes the structure function with a single parameter. Strehl ratios were computed from the phase structure functions and compared with a measured experiment obtained from simultaneous point-spread function measurements. Two additional Strehl ratios were calculated by using classical estimates that assume statistical isotropy throughout the flow. The isotropic models are a reasonable estimate of the optical degradation only within a few centimeters of the initial mixing, where the Reynolds number is low. At higher Reynolds numbers, Strehl ratios calculated from the structure functions match the experiment much better than Strehl ratio calculations that assume isotropic flow.

[Effects of forest gap size on the architecture of Quercus variablis seedlings on the south slope of Qinling Mountains, west China].

PubMed

Yu, Bi-yun; Zhang, Wen-hui; He, Ting; You, Jian-jian; Li, Gang

2014-12-01

Typical sampling method was conducted to survey the effects of forest gap size on branch architecture, leaf characteristics and their vertical distribution of Quercus variablis seedlings from different size gaps in natural secondary Q. variablis thinning forest, on the south slope of Qinling Mountains. The results showed that gap size significantly affected the diameter, crown area of Q. variablis seedlings. The gap size positively correlated with diameter and negatively correlated with crown area, while it had no significant impact on seedling height, crown length and crown rates. The overall bifurcation ratio, stepwise bifurcation ratio, and ratio of branch diameter followed as large gap > middle gap > small gap > understory. The vertical distribution of first-order branches under different size gaps mainly concentrated at the middle and upper part of trunk, larger diameter first-order branches were mainly distributed at the lower part of trunk, and the angle of first-order branch increased at first and then declined with the increasing seedling height. With the increasing forest gap size, the leaf length, leaf width and average leaf area of seedlings all gradually declined, while the average leaf number per plant and relative total leaf number increased, the leaf length-width ratio kept stable, the relative leaf number was mainly distributed at the middle and upper parts of trunk, the changes of leaf area index was consistent with the change of the relative total number of leaves. There was no significant difference between the diameters of middle gap and large gap seedlings, but the diameter of middle gap seedlings was higher than that of large gap, suggesting the middle gap would benefit the seedlings regeneration and high-quality timber cultivation. To promote the regeneration of Q. variabilis seedlings, and to cultivate high-quality timber, appropriate thinning should be taken to increase the number of middle gaps in the management of Q. variabilis forest.

Chemical transfers along slowly eroding catenas developed on granitic cratons in southern Africa

USGS Publications Warehouse

Khomo, Lesego; Bern, Carleton R.; Hartshorn, Anthony S.; Rogers, Kevin H.; Chadwick, Oliver A.

2013-01-01

A catena is a series of distinct but co-evolving soils arrayed along a slope. On low-slope, slowly eroding catenas the redistribution of mass occurs predominantly as plasma, the dissolved and suspended constituents in soil water. We applied mass balance methods to track how redistribution via plasma contributed to physical and geochemical differentiation of nine slowly eroding (~ 5 mm ky− 1) granitic catenas. The catenas were arrayed in a 3 × 3 climate by relief matrix and located in Kruger National Park, South Africa. Most of the catenas contained at least one illuviated soil profile that had undergone more volumetric expansion and less mass loss, and these soils were located in the lower halves of the slopes. By comparison, the majority of slope positions were eluviated. Soils from the wetter climates (550 and 730 mm precipitation yr− 1) generally had undergone greater collapse and lost more mass, while soils in the drier climate (470 mm yr− 1) had undergone expansion and lost less mass. Effects of differences in catena relief were less clear. Within each climate zone, soil horizon mass loss and strain were correlated, as were losses of most major elements, illustrating the predominant influence of primary mineral weathering. Nevertheless, mass loss and volumetric collapse did not become extreme because of the skeleton of resistant primary mineral grains inherited from the granite. Colloidal clay redistribution, as traced by the ratio of Ti to Zr in soil, suggested clay losses via suspension from catena eluvial zones. Thus illuviation of colloidal clays into downslope soils may be crucial to catena development by restricting subsurface flow there. Our analysis provides quantitative support for the conceptual understanding of catenas in cratonic landscapes and provides an endmember reference point in understanding the development of slowly eroding soil landscapes.

Fractional Models Simulating Non-Fickian Behavior in Four-Stage Single-Well Push-Pull Tests

NASA Astrophysics Data System (ADS)

Chen, Kewei; Zhan, Hongbin; Yang, Qiang

2017-11-01

Four-stage single-well push-pull (SWPP) tracer tests, including injection, chasing, resting, and pumping, were conducted in a fractured aquifer at Newark basin. An anomalous transport phenomenon observed in the SWPP tests is the linear decline of breakthrough curves (BTCs) at late time with slope of -1.8 in log-log plots. A time-dependent fractional model is developed to interpret the anomalous transport behavior. This model considers a time-dependent power law memory function and a time-dependent fractional advection-dispersion operator. The fractional advection-dispersion equations (fADE) are solved in a radial coordinate system using the implicit Euler method. A semi-analytical solution of the first-order rate-limited mobile-immobile model (FORMIM) is derived for comparison. It is found that both the nonlocal transport in time and space can produce the long-tailed BTC. A smaller time-fractional or space-fractional index leads to a lower peak concentration and a larger late-time slope. The mass distribution of the fractional-in-space (FS) model exhibits power law decline at the leading plume edge. Early breakthrough during pumping is not observed because the mobile mass at the start of pumping is nonzero and more concentrated near the wellbore. The capacity ratio is an important factor that affects the peak concentration. A larger capacity ratio leads to greater peak concentration. A smaller time-fractional index in the injection, chasing, or resting stage will move the BTC downward and the slope of the late time BTC is determined by the space-fractional index over all stages and the time-fractional index in the pumping stage. The capability of the existing models to recover the BTC of the SWPP test is discussed and some guidelines for how to choose the appropriate model to interpret the SWPP test data are proposed.

Improved Surgical Outcomes for ACS NSQIP Hospitals Over Time: Evaluation of Hospital Cohorts With up to 8 Years of Participation.

PubMed

Cohen, Mark E; Liu, Yaoming; Ko, Clifford Y; Hall, Bruce L

2016-02-01

The American College of Surgeons, National Surgical Quality Improvement Program (ACS NSQIP) surgical quality feedback models are recalibrated every 6 months, and each hospital is given risk-adjusted, hierarchical model, odds ratios that permit comparison to an estimated average NSQIP hospital at a particular point in time. This approach is appropriate for "relative" benchmarking, and for targeting quality improvement efforts, but does not permit evaluation of hospital or program-wide changes in quality over time. We report on long-term improvement in surgical outcomes associated with participation in ACS NSQIP. ACS NSQIP data (2006-2013) were used to create prediction models for mortality, morbidity (any of several distinct adverse outcomes), and surgical site infection (SSI). For each model, for each hospital, and for year of first participation (hospital cohort), hierarchical model observed/expected (O/E) ratios were computed. The primary performance metric was the within-hospital trend in logged O/E ratios over time (slope) for mortality, morbidity, and SSI. Hospital-averaged log O/E ratio slopes were generally negative, indicating improving performance over time. For all hospitals, 62%, 70%, and 65% of hospitals had negative slopes for mortality, morbidity, and any SSI, respectively. For hospitals currently in the program for at least 3 years, 69%, 79%, and 71% showed improvement in mortality, morbidity, and SSI, respectively. For these hospitals, we estimate 0.8%, 3.1%, and 2.6% annual reductions (with respect to prior year's rates) for mortality, morbidity, and SSI, respectively. Participation in ACS NSQIP is associated with reductions in adverse events after surgery. The magnitude of quality improvement increases with time in the program.

An experimental topographic amplification study at Los Alamos National Laboratory using ambient vibrations

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

Stolte, Andrew C.; Cox, Brady R.; Lee, Richard C.

An experimental study aimed at investigating potential topographic amplification of seismic waves was conducted on a 50-m-tall and 185-m-wide soft-rock ridge located at Los Alamos National Laboratory near Los Alamos, New Mexico. Ten portable broadband seismograph stations were placed in arrays across the ridge and left to record ambient vibration data for ~9 hours. Clear evidence of topographic amplification was observed by comparing spectral ratios calculated from ambient noise recordings at the toe, slope, and crest of the instrumented ridge. The inferred resonance frequency of the ridge obtained from the experimental recordings was found to agree well with several simplemore » estimates of the theoretical resonance frequency based on its geometry and stiffness. Results support the feasibility of quantifying the frequency range of topographic amplification solely using ambient vibrations, rather than strong or weak ground motions. Additionally, comparisons have been made between a number of widely used experimental methods for quantifying topographic effects, such as the standard spectral ratio, median reference method, and horizontal-to-vertical spectral ratio. As a result, differences in the amplification and frequency range of topographic effects indicated by these methods highlight the importance of choosing a reference condition that is appropriate for the site-specific conditions and goals associated with an experimental topographic amplification study.« less

An experimental topographic amplification study at Los Alamos National Laboratory using ambient vibrations

DOE PAGES

Stolte, Andrew C.; Cox, Brady R.; Lee, Richard C.

2017-03-14

An experimental study aimed at investigating potential topographic amplification of seismic waves was conducted on a 50-m-tall and 185-m-wide soft-rock ridge located at Los Alamos National Laboratory near Los Alamos, New Mexico. Ten portable broadband seismograph stations were placed in arrays across the ridge and left to record ambient vibration data for ~9 hours. Clear evidence of topographic amplification was observed by comparing spectral ratios calculated from ambient noise recordings at the toe, slope, and crest of the instrumented ridge. The inferred resonance frequency of the ridge obtained from the experimental recordings was found to agree well with several simplemore » estimates of the theoretical resonance frequency based on its geometry and stiffness. Results support the feasibility of quantifying the frequency range of topographic amplification solely using ambient vibrations, rather than strong or weak ground motions. Additionally, comparisons have been made between a number of widely used experimental methods for quantifying topographic effects, such as the standard spectral ratio, median reference method, and horizontal-to-vertical spectral ratio. As a result, differences in the amplification and frequency range of topographic effects indicated by these methods highlight the importance of choosing a reference condition that is appropriate for the site-specific conditions and goals associated with an experimental topographic amplification study.« less

Accurate measurements of the thermal diffusivity of thin filaments by lock-in thermography

NASA Astrophysics Data System (ADS)

Salazar, Agustín; Mendioroz, Arantza; Fuente, Raquel; Celorrio, Ricardo

2010-02-01

In lock-in (modulated) thermography the lateral thermal diffusivity can be obtained from the slope of the linear relation between the phase of the surface temperature and the distance to the heating spot. However, this slope is greatly affected by heat losses, leading to an overestimation of the thermal diffusivity, especially for thin samples of poor thermal conducting materials. In this paper, we present a complete theoretical model to calculate the surface temperature of filaments heated by a focused and modulated laser beam. All heat losses have been included: conduction to the gas, convection, and radiation. Monofilaments and coated wires have been studied. Conduction to the gas has been identified as the most disturbing effect preventing from the direct use of the slope method to measure the thermal diffusivity. As a result, by keeping the sample in vacuum a slope method combining amplitude and phase can be used to obtain the accurate diffusivity value. Measurements performed in a wide variety of filaments confirm the validity of the conclusion. On the other hand, in the case of coated wires, the slope method gives an effective thermal diffusivity, which verifies the in-parallel thermal resistor model. As an application, the slope method has been used to retrieve the thermal conductivity of thin tubes by filling them with a liquid of known thermal properties.

A Numerical Study on Toppling Failure of a Jointed Rock Slope by Using the Distinct Lattice Spring Model

NASA Astrophysics Data System (ADS)

Lian, Ji-Jian; Li, Qin; Deng, Xi-Fei; Zhao, Gao-Feng; Chen, Zu-Yu

2018-02-01

In this work, toppling failure of a jointed rock slope is studied by using the distinct lattice spring model (DLSM). The gravity increase method (GIM) with a sub-step loading scheme is implemented in the DLSM to mimic the loading conditions of a centrifuge test. A classical centrifuge test for a jointed rock slope, previously simulated by the finite element method and the discrete element model, is simulated by using the GIM-DLSM. Reasonable boundary conditions are obtained through detailed comparisons among existing numerical solutions with experimental records. With calibrated boundary conditions, the influences of the tensional strength of the rock block, cohesion and friction angles of the joints, as well as the spacing and inclination angles of the joints, on the flexural toppling failure of the jointed rock slope are investigated by using the GIM-DLSM, leading to some insight into evaluating the state of flexural toppling failure for a jointed slope and effectively preventing the flexural toppling failure of jointed rock slopes.

The role of observer variation in determining Rosgen stream types in northeastern Oregon mountain streams

Treesearch

Brett B. Roper; John M. Buffington; Eric Archer; Chris Moyer; Mike Ward

2008-01-01

Consistency in determining Rosgen stream types was evaluated in 12 streams within the John Day Basin, northeastern Oregon. The Rosgen classification system is commonly used in the western United States and is based on the measurement of five stream attributes: entrenchment ratio, width-to-depth ratio, sinuosity, slope, and substrate size. Streams were classified from...

Prediction of intracranial hypertension through noninvasive intracranial pressure waveform analysis in pediatric hydrocephalus.

PubMed

Ballestero, Matheus Fernando Manzolli; Frigieri, Gustavo; Cabella, Brenno Caetano Troca; de Oliveira, Sergio Mascarenhas; de Oliveira, Ricardo Santos

2017-09-01

The purpose of this study is to evaluate a noninvasive device to assess intracranial pressure wave form in children with hydrocephalus. A prospective and non-experimental descriptive-analytic study was performed. Fifty-six patients were enrolled in this study. They were divided in four groups: group A, children with clinically compensated hydrocephalus; B, surgically treated hydrocephalus; C, patients with acute intracranial hypertension due to hydrocephalus; and D, children without neurological disease (control). Data were collected through the installation of an extracranial deformation sensor, coupled to the children's scalp, which allowed registration of noninvasive intracranial pressure curves. Parameters obtained were analyzed: P2/P1 ratio, "classification P1 and P2 and P1 slope. P2/P1 index and "classification of P1 and P2" had a sensitivity of 80% and specificity of 100% for predicting intracranial hypertension. "P1 slope" presented no statistical difference. This study showed a useful and noninvasive method for monitoring intracranial pressure, which was able to indicate the intracranial hypertension in children with hydrocephalus and, thus, should be further investigated for clinical applications.

Methods for Meeting the Intent of the ADA in Sidewalk Cross-Slope Design

DOT National Transportation Integrated Search

2000-01-01

This summary report is a review of research undertaken to determine appropriate sidewalk cross-slope design in accordance wit the Americans with Disabilities Act (ADA). The research methods used are described and specific recommendations are provided...

Growth, spectroscopy and continuous-wave laser performance of Nd3+:LiLu0.65Y0.35F4 crystal

NASA Astrophysics Data System (ADS)

Demesh, M. P.; Kurilchik, S. V.; Gusakova, N. V.; Yasukevich, A. S.; Kisel, V. E.; Nizamutdinov, A. S.; Marisov, M. M.; Aglyamov, R. D.; Korableva, S. L.; Naumov, A. K.; Semashko, V. V.; Kuleshov, N. V.

2018-04-01

A mixed fluoride crystal of LiLu0.65Y0.35F4 doped with Nd3+ ions was grown by the Bridgman-Stockbarger method. Polarized absorption and luminescence spectra as well as luminescence lifetime were measured at room temperature. Emission probabilities, branching ratios and radiative lifetime were studied within the Judd-Ofelt theory and the emission cross section spectra were calculated. Efficient continuous wave laser operation was demonstrated with the crystal. A maximum output power of 7.7 W and slope efficiency of 60% were achieved at 1047 nm for the TEM00 mode.

Changes in Atmospheric Butanes and Pentanes and Their Isomeric Ratios in the Continental United States

NASA Astrophysics Data System (ADS)

Rossabi, Sam; Helmig, Detlev

2018-04-01

Nonmethane hydrocarbons have been used as tracers in research on emissions and atmospheric oxidation chemistry. This research investigates source region mixing ratio trends of the nonmethane hydrocarbons i-butane, n-butane, i-pentane, and n-pentane, and the (i/n) isomeric ratios of these compounds between 2001 and 2015. Data collected at Photochemical Assessment Monitoring Stations, mandated by the U.S. Environmental Protection Agency in ozone nonattainment areas, and data collected at Global Greenhouse Gas Reference Network sites within the National Oceanic and Atmospheric Administration network, and analyzed at the Institute of Arctic and Alpine Research at the University of Colorado-Boulder, were examined. Among all considered species, linear regression analyses on concentration time series had negative slopes at 81% of sites, indicating predominantly declining butane and pentane atmospheric concentrations. Mostly negative slopes (78% of sites) were found for the (i/n) butane and pentane isomeric ratios, including all six and seven statistically significant (i/n) butane and pentane trends, respectively. Over the 15 year investigation period and averaged over all sites, total relative changes were 30 and 45% for the (i/n) ratios of butanes and pentanes, respectively, with a relative increase in the prominence of the n-isomers. Most likely causes include changing isomeric ratios in gasoline sector emissions, and increasing influence of oil and natural gas industry emissions. Changes in concentrations and isomeric ratios depend on proximity of contributing emission sources to measurement sites.

Reliability-Based Stability Analysis of Rock Slopes Using Numerical Analysis and Response Surface Method

NASA Astrophysics Data System (ADS)

Dadashzadeh, N.; Duzgun, H. S. B.; Yesiloglu-Gultekin, N.

2017-08-01

While advanced numerical techniques in slope stability analysis are successfully used in deterministic studies, they have so far found limited use in probabilistic analyses due to their high computation cost. The first-order reliability method (FORM) is one of the most efficient probabilistic techniques to perform probabilistic stability analysis by considering the associated uncertainties in the analysis parameters. However, it is not possible to directly use FORM in numerical slope stability evaluations as it requires definition of a limit state performance function. In this study, an integrated methodology for probabilistic numerical modeling of rock slope stability is proposed. The methodology is based on response surface method, where FORM is used to develop an explicit performance function from the results of numerical simulations. The implementation of the proposed methodology is performed by considering a large potential rock wedge in Sumela Monastery, Turkey. The accuracy of the developed performance function to truly represent the limit state surface is evaluated by monitoring the slope behavior. The calculated probability of failure is compared with Monte Carlo simulation (MCS) method. The proposed methodology is found to be 72% more efficient than MCS, while the accuracy is decreased with an error of 24%.

Methods for assessing the stability of slopes during earthquakes-A retrospective

USGS Publications Warehouse

Jibson, R.W.

2011-01-01

During the twentieth century, several methods to assess the stability of slopes during earthquakes were developed. Pseudostatic analysis was the earliest method; it involved simply adding a permanent body force representing the earthquake shaking to a static limit-equilibrium analysis. Stress-deformation analysis, a later development, involved much more complex modeling of slopes using a mesh in which the internal stresses and strains within elements are computed based on the applied external loads, including gravity and seismic loads. Stress-deformation analysis provided the most realistic model of slope behavior, but it is very complex and requires a high density of high-quality soil-property data as well as an accurate model of soil behavior. In 1965, Newmark developed a method that effectively bridges the gap between these two types of analysis. His sliding-block model is easy to apply and provides a useful index of co-seismic slope performance. Subsequent modifications to sliding-block analysis have made it applicable to a wider range of landslide types. Sliding-block analysis provides perhaps the greatest utility of all the types of analysis. It is far easier to apply than stress-deformation analysis, and it yields much more useful information than does pseudostatic analysis. ?? 2010.

Novel Control Scheme of Power Assisted Wheelchair for Preventing Overturn (Part II)-Variable Assistance Ratio Control Based on Estimation of Center-of-Gravity Angle and Phase Plane-

NASA Astrophysics Data System (ADS)

Hata, Naoki; Seki, Hirokazu; Koyasu, Yuichi; Hori, Yoichi

Aged people and disabled people who have difficulty in walking are increasing. As one of mobility support, significance of a power assisted wheelchair which assists driving force using electric motors and spreads their living areas has been enhanced. However, the increased driving force often causes a dangerous overturn of wheelchair. This paper proposes a novel control method to prevent power assisted wheelchair from overturning. The man-wheelchair system can be regarded as an inverse pendulum model when the front wheels are rising. The center-of-gravity (COG) angle of the model is the most important information directly-linked to overturn. Behavior of the system can be analyzed using phase plane as shown in this paper. The COG angle cannot be directly measured using a sensor, therefore, COG observer based on its velocity is proposed. On the basis of the analysis on phase plane, a novel control method with variable assistance ratio to prevent a dangerous overturn is proposed. The effectiveness of the proposed method is verified by the practical experiments on the flat ground and uphill slope.

Study of Disseminating Landslide Early Warning Information in Malaysia

NASA Astrophysics Data System (ADS)

Koay, Swee Peng; Lateh, Habibah; Tien Tay, Lea; Ahamd, Jamilah; Chan, Huah Yong; Sakai, Naoki; Jamaludin, Suhaimi

2015-04-01

In Malaysia, rain induced landslides are occurring more often than before. The Malaysian Government allocates millions of Malaysian Ringgit for slope monitoring and slope failure remedial measures in the budget every year. In rural areas, local authorities also play a major role in monitoring the slope to prevent casualty by giving information to the residents who are staying near to the slopes. However, there are thousands of slopes which are classified as high risk slopes in Malaysia. Implementing site monitoring system in these slopes to monitor the movement of the soil in the slopes, predicting the occurrence of slopes failure and establishing early warning system are too costly and almost impossible. In our study, we propose Accumulated Rainfall vs. Rainfall Intensity prediction method to predict the slope failure by referring to the predicted rainfall data from radar and the rain volume from rain gauges. The critical line which determines if the slope is in danger, is generated by simulator with well-surveyed the soil property in the slope and compared with historical data. By establishing such predicting system, the slope failure warning information can be obtained and disseminated to the surroundings via SMS, internet and siren. However, establishing the early warning dissemination system is not enough in disaster prevention, educating school children and the community by giving knowledge on landslides, such as landslide's definition, how and why does the slope failure happen and when will it fail, to raise the risk awareness on landslides will reduce landslides casualty, especially in rural area. Moreover, showing video on the risk and symptom of landslides in school will also help the school children gaining the knowledge of landslides. Generating hazard map and landslides historical data provides further information on the occurrence of the slope failure. In future, further study on fine tuning of landslides prediction method, applying IT technology to educate school children and disseminate warning information will assist the government authorities to reduce landslide casualty by disseminating prompt slope failure warning and improving the community's awareness of disaster prevention.

Stability Calculation Method of Slope Reinforced by Prestressed Anchor in Process of Excavation

PubMed Central

Li, Zhong; Wei, Jia; Yang, Jun

2014-01-01

This paper takes the effect of supporting structure and anchor on the slope stability of the excavation process into consideration; the stability calculation model is presented for the slope reinforced by prestressed anchor and grillage beam, and the dynamic search model of the critical slip surface also is put forward. The calculation model of the optimal stability solution of each anchor tension of the whole process is also given out, through which the real-time analysis and checking of slope stability in the process of excavation can be realized. The calculation examples indicate that the slope stability is changed with the dynamic change of the design parameters of anchor and grillage beam. So it is relatively more accurate and reasonable by using dynamic search model to determine the critical slip surface of the slope reinforced by prestressed anchor and grillage beam. Through the relationships of each anchor layout and the slope height of various stages of excavation, and the optimal stability solution of prestressed bolt tension design value in various excavation stages can be obtained. The arrangement of its prestressed anchor force reflects that the layout of the lower part of bolt and the calculation of slope reinforcement is in line with the actual. These indicate that the method is reasonable and practical. PMID:24683319

Stability calculation method of slope reinforced by prestressed anchor in process of excavation.

PubMed

Li, Zhong; Wei, Jia; Yang, Jun

2014-01-01

This paper takes the effect of supporting structure and anchor on the slope stability of the excavation process into consideration; the stability calculation model is presented for the slope reinforced by prestressed anchor and grillage beam, and the dynamic search model of the critical slip surface also is put forward. The calculation model of the optimal stability solution of each anchor tension of the whole process is also given out, through which the real-time analysis and checking of slope stability in the process of excavation can be realized. The calculation examples indicate that the slope stability is changed with the dynamic change of the design parameters of anchor and grillage beam. So it is relatively more accurate and reasonable by using dynamic search model to determine the critical slip surface of the slope reinforced by prestressed anchor and grillage beam. Through the relationships of each anchor layout and the slope height of various stages of excavation, and the optimal stability solution of prestressed bolt tension design value in various excavation stages can be obtained. The arrangement of its prestressed anchor force reflects that the layout of the lower part of bolt and the calculation of slope reinforcement is in line with the actual. These indicate that the method is reasonable and practical.

Automated system measuring triple oxygen and nitrogen isotope ratios in nitrate using the bacterial method and N2 O decomposition by microwave discharge.

PubMed

Hattori, Shohei; Savarino, Joel; Kamezaki, Kazuki; Ishino, Sakiko; Dyckmans, Jens; Fujinawa, Tamaki; Caillon, Nicolas; Barbero, Albane; Mukotaka, Arata; Toyoda, Sakae; Well, Reinhard; Yoshida, Naohiro

2016-12-30

Triple oxygen and nitrogen isotope ratios in nitrate are powerful tools for assessing atmospheric nitrate formation pathways and their contribution to ecosystems. N 2 O decomposition using microwave-induced plasma (MIP) has been used only for measurements of oxygen isotopes to date, but it is also possible to measure nitrogen isotopes during the same analytical run. The main improvements to a previous system are (i) an automated distribution system of nitrate to the bacterial medium, (ii) N 2 O separation by gas chromatography before N 2 O decomposition using the MIP, (iii) use of a corundum tube for microwave discharge, and (iv) development of an automated system for isotopic measurements. Three nitrate standards with sample sizes of 60, 80, 100, and 120 nmol were measured to investigate the sample size dependence of the isotope measurements. The δ 17 O, δ 18 O, and Δ 17 O values increased with increasing sample size, although the δ 15 N value showed no significant size dependency. Different calibration slopes and intercepts were obtained with different sample amounts. The slopes and intercepts for the regression lines in different sample amounts were dependent on sample size, indicating that the extent of oxygen exchange is also dependent on sample size. The sample-size-dependent slopes and intercepts were fitted using natural log (ln) regression curves, and the slopes and intercepts can be estimated to apply to any sample size corrections. When using 100 nmol samples, the standard deviations of residuals from the regression lines for this system were 0.5‰, 0.3‰, and 0.1‰, respectively, for the δ 18 O, Δ 17 O, and δ 15 N values, results that are not inferior to those from other systems using gold tube or gold wire. An automated system was developed to measure triple oxygen and nitrogen isotopes in nitrate using N 2 O decomposition by MIP. This system enables us to measure both triple oxygen and nitrogen isotopes in nitrate with comparable precision and sample throughput (23 min per sample on average), and minimal manual treatment. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

[Effects and mechanisms of plant roots on slope reinforcement and soil erosion resistance: a research review].

PubMed

Xiong, Yan-Mei; Xia, Han-Ping; Li, Zhi-An; Cai, Xi-An

2007-04-01

Plant roots play an important role in resisting the shallow landslip and topsoil erosion of slopes by raising soil shear strength. Among the models in interpreting the mechanisms of slope reinforcement by plant roots, Wu-Waldron model is a widely accepted one. In this model, the reinforced soil strength by plant roots is positively proportional to average root tensile strength and root area ratio, the two most important factors in evaluating slope reinforcement effect of plant roots. It was found that soil erosion resistance increased with the number of plant roots, though no consistent quantitative functional relationship was observed between them. The increase of soil erosion resistance by plant roots was mainly through the actions of fiber roots less than 1 mm in diameter, while fiber roots enhanced the soil stability to resist water dispersion via increasing the number and diameter of soil water-stable aggregates. Fine roots could also improve soil permeability effectively to decrease runoff and weaken soil erosion.

Optimization of two-dimensional gas chromatography time-of-flight mass spectrometry for separation and estimation of the residues of 160 pesticides and 25 persistent organic pollutants in grape and wine.

PubMed

Dasgupta, Soma; Banerjee, Kaushik; Patil, Sangram H; Ghaste, Manoj; Dhumal, K N; Adsule, Pandurang G

2010-06-11

Two-dimensional gas chromatography (GCxGC) coupled with time-of-flight mass spectrometric (TOFMS) method was optimized for simultaneous analysis of 160 pesticides, 12 dioxin-like polychlorinated biphenyls (PCBs), 12 polyaromatic hydrocarbons (PAHs) and bisphenol A in grape and wine. GCxGC-TOFMS could separate all the 185 analytes within 38min with >85% NIST library-based mass spectral confirmations. The matrix effect quantified as the ratio of the slope of matrix-matched to solvent calibrations was within 0.5-1.5 for most analytes. LOQ of most of the analytes was < or =10microg/L with nine exceptions having LOQs of 12.5-25microg/L. Recoveries ranged between 70 and 120% with <20% expanded uncertainties for 151 and 148 compounds in grape and wine, respectively, with intra-laboratory Horwitz ratio <0.2 for all analytes. The method was evaluated in the incurred grape samples where residues of cypermethrin, permethrin, chlorpyriphos, metalaxyl and etophenprox were detected at below MRL. Copyright 2010 Elsevier B.V. All rights reserved.

Efficient technical solution for recycling textile materials by manufacturing nonwoven geotextiles

NASA Astrophysics Data System (ADS)

Leon, A. L.; Potop, G. L.; Hristian, L.; Manea, L. R.

2016-08-01

This paper aims to support the concept "circular economy" that was developed recently. It presents an efficient method for creating a closed loop in the Romanian textile industry by recycling textile materials, such as polyacrylonitrile knitted old products (collected from population) and small polyester woven patches from pre-consumer waste (garments manufacturing companies). Because of their properties, nonwoven geotextiles have many advantages in railways reinforcement, slopes stabilization, erosion control, drainage, filtration, paving roads, crops coverings, etc. The nonwoven geotextiles were obtained from three fibrous blends based on recovered fibers (PES and PAN) and fibers at first usage (PP) in different ratios. All experimental variants were processed on the same manufacturing line with the same technological parameters. There were tested the main physical and mechanical parameters and it was applied single factor ANOVA method for thickness, bulk density, air permeability and static puncture strength. The conclusion is that adding PP fibers in the blends represents a very important factor for geotextiles characteristics but it possible to decrease the ratio from economical reasons and still maintain a high quality level of nonwovens.

Spatial prediction of landslide susceptibility using an adaptive neuro-fuzzy inference system combined with frequency ratio, generalized additive model, and support vector machine techniques

NASA Astrophysics Data System (ADS)

Chen, Wei; Pourghasemi, Hamid Reza; Panahi, Mahdi; Kornejady, Aiding; Wang, Jiale; Xie, Xiaoshen; Cao, Shubo

2017-11-01

The spatial prediction of landslide susceptibility is an important prerequisite for the analysis of landslide hazards and risks in any area. This research uses three data mining techniques, such as an adaptive neuro-fuzzy inference system combined with frequency ratio (ANFIS-FR), a generalized additive model (GAM), and a support vector machine (SVM), for landslide susceptibility mapping in Hanyuan County, China. In the first step, in accordance with a review of the previous literature, twelve conditioning factors, including slope aspect, altitude, slope angle, topographic wetness index (TWI), plan curvature, profile curvature, distance to rivers, distance to faults, distance to roads, land use, normalized difference vegetation index (NDVI), and lithology, were selected. In the second step, a collinearity test and correlation analysis between the conditioning factors and landslides were applied. In the third step, we used three advanced methods, namely, ANFIS-FR, GAM, and SVM, for landslide susceptibility modeling. Subsequently, the results of their accuracy were validated using a receiver operating characteristic curve. The results showed that all three models have good prediction capabilities, while the SVM model has the highest prediction rate of 0.875, followed by the ANFIS-FR and GAM models with prediction rates of 0.851 and 0.846, respectively. Thus, the landslide susceptibility maps produced in the study area can be applied for management of hazards and risks in landslide-prone Hanyuan County.

A Polymorphism Within the Promoter of the TGF{beta}1 Gene Is Associated With Radiation Sensitivity Using an Objective Radiologic Endpoint

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

Kelsey, Chris R., E-mail: kelse003@mc.duke.edu; Jackson, Lauren; Langdon, Scott

2012-02-01

Purpose: To evaluate whether single nucleotide polymorphisms (SNPs) in the transforming growth factor-{beta}1 (TGF{beta}1) gene are associated with radiation sensitivity using an objective radiologic endpoint. Methods and Materials: Preradiation therapy and serial postradiation therapy single photon emission computed tomography (SPECT) lung perfusion scans were obtained in patients undergoing treatment for lung cancer. Serial blood samples were obtained to measure circulating levels of TGF{beta}1. Changes in regional perfusion were related to regional radiation dose yielding a patient-specific dose-response curve, reflecting the patient's inherent sensitivity to radiation therapy. Six TGF{beta}1 SNPs (-988, -800, -509, 869, 941, and 1655) were assessed using high-resolutionmore » melting assays and DNA sequencing. The association between genotype and slope of the dose-response curve, and genotype and TGF{beta}1 ratio (4-week/preradiation therapy), was analyzed using the Kruskal-Wallis test. Results: 39 white patients with preradiation therapy and {>=}6-month postradiation therapy SPECT scans and blood samples were identified. Increasing slope of the dose-response curve was associated with the C(-509)T SNP (p = 0.035), but not the other analyzed SNPs. This SNP was also associated with higher TGF{beta}1 ratios. Conclusions: This study suggests that a polymorphism within the promoter of the TGF{beta}1 gene is associated with increased radiation sensitivity (defined objectively by dose-dependent changes in SPECT lung perfusion).« less

Rheological model analysis on depth of toppling deformation in the anti-dip rock slope

NASA Astrophysics Data System (ADS)

Zheng, Da

2017-04-01

The failure of the toppling deformation occurred in the layered rock mass, it is a kind of mode of deformation and failure, which is bent towards free direction and gradually develops into the slope under the combined forces of in-situ stress, gravity, and groundwater dynamic (hydrostatic) pressure and so on. The most common toppling deformation is the toppling of ductile bending. Obtaining the developmental depth of bending deformation is of great significance for judging the development scale of the plasmodium and the stability of the slope. At present, the developmental depth of toppling deformation mainly depends on the survey and statistic of the exploration adit, or the simulation of the deformation and failure process through the numerical simulation method, there is little research on the developmental depth of toppling deformation from mechanics point of view. In this paper, with the consideration of the time-sensitive characteristics of developmental process of the toppling deformation, the anti-dip layered slope can be considered as a multi-layer superposition cantilever with fixed end and free end, bending under self-weight and inter-layer stress. Under the premise of the initial stage of rheology of the rock slopes, which is considered to be the limit position of the toppling deformation and development, the Kelvin rheological model, which is usually used to describe the decay creep, is chosen to describe the time-sensitive process of rock slopes. The stress-strain analysis calculation is used to obtain the time-varying expression of a certain point on the rock beam. Furthermore, taking the time to infinity, the depth of the layered rock slopes is calculated as x=4Ccosβ/[2γcosαcosβ - γ2(cos (α + β)+2sin(α + β)tanφ)*((1+n) /2+(1-n) cos2α/ 2)] , which is obtained by using the strain reaches zero as the criterion of the depth at toppling deformation development limit position, combining the time-varying expression of a certain point on the beam. we obtain the mathematic analysis conditions by using the constant positive characteristic of depth of the toppling deformation, The result shows that the depth of the slope toppling deformation is influenced by the rock mass, strata inclination, rock thickness, interfacial friction coefficient, interlayer internal friction angle, slope angel and Poisson 's ratio of rock slopes. The toppling deformation only occurs when 2cosαcosβ-[cos(α + β)+2sin(α + β)tanφ][(1+n)/2+(1-n) cos2α/2]≥0. This study is an exploration to explain the time-sensitive characteristics of toppling deformation by using rheological theory. The conclusion is of great significance for the study of the location of the bending zone, the size of the toppling deformation, the stability analysis and the early identification of the toppling deformation based on the deformation characteristics.

GaN Nanowire MOSFET with Near-Ideal Subthreshold Slope.

PubMed

Li, Wenjun; Brubaker, Matt D; Spann, Bryan T; Bertness, Kris A; Fay, Patrick

2018-02-01

Wrap-around gate GaN nanowire MOSFETs using Al 2 O 3 as gate oxide have been experimentally demonstrated. The fabricated devices exhibit a minimum subthreshold slope of 60 mV/dec, an average subthreshold slope of 68 mV/dec over three decades of drain current, drain-induced barrier lowering of 27 mV/V, an on-current of 42 μA/μm (normalized by nanowire circumference), on/off ratio over 10 8 , an intrinsic transconductance of 27.8 μS/μm, for a switching efficiency figure of merit, Q=g m /SS of 0.41 μS/μm-dec/mV. These performance metrics make GaN nanowire MOSFETs a promising candidate for emerging low-power applications such as sensors and RF for the internet of things.

A New Methodology for Open Pit Slope Design in Karst-Prone Ground Conditions Based on Integrated Stochastic-Limit Equilibrium Analysis

NASA Astrophysics Data System (ADS)

Zhang, Ke; Cao, Ping; Ma, Guowei; Fan, Wenchen; Meng, Jingjing; Li, Kaihui

2016-07-01

Using the Chengmenshan Copper Mine as a case study, a new methodology for open pit slope design in karst-prone ground conditions is presented based on integrated stochastic-limit equilibrium analysis. The numerical modeling and optimization design procedure contain a collection of drill core data, karst cave stochastic model generation, SLIDE simulation and bisection method optimization. Borehole investigations are performed, and the statistical result shows that the length of the karst cave fits a negative exponential distribution model, but the length of carbonatite does not exactly follow any standard distribution. The inverse transform method and acceptance-rejection method are used to reproduce the length of the karst cave and carbonatite, respectively. A code for karst cave stochastic model generation, named KCSMG, is developed. The stability of the rock slope with the karst cave stochastic model is analyzed by combining the KCSMG code and the SLIDE program. This approach is then applied to study the effect of the karst cave on the stability of the open pit slope, and a procedure to optimize the open pit slope angle is presented.

Rock Slope Stability Evaluation in a Steep-Walled Canyon: Application to Elevator Construction in the Yunlong River Valley, Enshi, China

NASA Astrophysics Data System (ADS)

Xiao, Lili; Chai, Bo; Yin, Kunlong

2015-09-01

A passenger elevator is to be built on a nearly vertical slope in the National Geological Park in Enshi, Hubei province, China. Three steps comprise the construction: excavating the slope toe for the elevator platform, building the elevator on the platform, and affixing the elevator to the slope using anchors. To evaluate the rock slope stability in the elevator area and the safety of the elevator construction, we applied three techniques: qualitative analysis, formula calculation, and numerical simulation methods, based on field investigation and parameter selection, and considering both wet and dry conditions, pre- and post-construction. Qualitative stability factors for sliding and falling were calculated using the limit equilibrium method; the results show that the slope as a whole is stable, with a few unstable blocks, notably block BT1. Formula-based stability factors were calculated for four sections on block BT1, revealing the following: anchors will decrease the stability of certain rock pieces; the lowest average stability factor after anchoring will be K f = 1.36 in wet conditions; block BT1 should be reinforced during elevator construction, up to a first-class slope stability factor of K f = 1.40; and the slope as a whole is stable. Numerical simulation using FLAC3D indicated that the stress distribution will reach equilibrium for all steps before and after construction, and that the factor of safety (FOS) is within the general slope safety range (FOS > 1.05). We suggest that unstable pieces in block BT1 be reinforced during construction to a first-class slope safety range (FOS > 1.3), and that deformation monitoring on the slope surface be implemented.

Correction of broadband albedo measurements affected by unknown slope and sensor tilts

NASA Astrophysics Data System (ADS)

Weiser, Ursula; Olefs, Marc; Schöner, Wolfgang; Weyss, Gernot; Hynek, Bernhard

2017-02-01

Geometric effects induced by the underlying terrain slope or by tilt errors of radiation sensors lead to an erroneous measurement of snow or ice albedo. Consequently, diurnal albedo variations are observed. A general method to correct tilt errors of albedo measurements in cases where tilts of both the sensors and the slopes are not accurately measured or known is presented. Atmospheric parameters for this correction method can either be taken from a nearby well-maintained and horizontally levelled measurement of global radiation or alternatively from a solar radiation model. In a next step the model is fitted to the measured data to determine tilts and directions of the sensors and the underlying terrain slope. This then allows to correct the measured albedo, the radiative balance and the energy balance. Depending on the direction of the slope and the sensors a comparison between measured and corrected albedo values reveals obvious over-or underestimations of albedo.

Innovative techniques with multi-purpose survey vehicle for automated analysis of cross-slope data.

DOT National Transportation Integrated Search

2007-11-02

Manual surveying methods have long been used in the field of highway engineering to determine : the cross-slope, and longitudinal grade of an existing roadway. However, these methods are : slow, tedious and labor intensive. Moreover, manual survey me...

Determination of slope failure using 2-D resistivity method

NASA Astrophysics Data System (ADS)

Muztaza, Nordiana Mohd; Saad, Rosli; Ismail, Nur Azwin; Bery, Andy Anderson

2017-07-01

Landslides and slope failure may give negative economic effects including the cost to repair structures, loss of property value and medical costs in the event of injury. To avoid landslide, slope failure and disturbance of the ecosystem, good and detailed planning must be done when developing hilly area. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. The study on landslide and slope failure was conducted at Site A and Site B, Selangor using 2-D resistivity method. The implications of the anticipated ground conditions as well as the field observation of the actual conditions are discussed. Nine 2-D resistivity survey lines were conducted in Site A and six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed in Site B. The data were processed using Res2Dinv and Surfer10 software to evaluate the subsurface characteristics. 2-D resistivity results from both locations show that the study areas consist of two main zones. The first zone is alluvium or highly weathered with the resistivity of 100-1000 Ωm at 20-70 m depth. This zone consists of saturated area (1-100 Ωm) and boulders with resistivity value of 1200-3000 Ωm. The second zone with resistivity values of > 3000 Ωm was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. Based on the results obtained from the study findings, it can be concluded that 2-D resistivity method is useful method in determination of slope failure.

Assessment of Rainfall-induced Landslide Potential and Spatial Distribution

NASA Astrophysics Data System (ADS)

Chen, Yie-Ruey; Tsai, Kuang-Jung; Chen, Jing-Wen; Chiang, Jie-Lun; Hsieh, Shun-Chieh; Chue, Yung-Sheng

2016-04-01

Recently, due to the global climate change, most of the time the rainfall in Taiwan is of short duration but with high intensity. Due to Taiwan's steep terrain, rainfall-induced landslides often occur and lead to human causalities and properties loss. Taiwan's government has invested huge reconstruction funds to the affected areas. However, after rehabilitation they still face the risk of secondary sediment disasters. Therefore, this study assesses rainfall-induced (secondary) landslide potential and spatial distribution in watershed of Southern Taiwan under extreme climate change. The study areas in this research are Baolai and Jianshan villages in the watershed of the Laonongxi River Basin in the Southern Taiwan. This study focused on the 3 years after Typhoon Morakot (2009 to 2011). During this period, the study area experienced six heavy rainfall events including five typhoons and one heavy rainfall. The genetic adaptive neural network, texture analysis and GIS were implemented in the analysis techniques for the interpretation of satellite images and to obtain surface information and hazard log data and to analyze land use change. A multivariate hazards evaluation method was applied to quantitatively analyze the weights of various natural environmental and slope development hazard factors. Furthermore, this study established a slope landslide potential assessment model and depicted a slope landslide potential diagram by using the GIS platform. The interaction between (secondary) landslide mechanism, scale, and location was analyzed using association analysis of landslide historical data and regional environmental characteristics. The results of image classification before and after six heavy rainfall events show that the values of coefficient of agreement are at medium-high level. By multivariate hazards evaluation method, geology and the effective accumulative rainfall (EAR) are the most important factors. Slope, distance from fault, aspect, land disturbance, and elevation are the secondary important factors. Under the different rainfall, the greater the average of EAR, the more the landslide occurrence and area increments. The determination coefficients of trend lines on the charts of the average of EAR versus number and area of landslide increment are 0.83 and 0.92, respectively. The relations between landslide potential level, degree of land disturbance, and the ratio of number and area of landslide increment corresponding six heavy rainfall events are positive and the determination coefficients of trend lines are 0.82 and 0.72, respectively. The relation between the average of EAR and the area of landslide increment corresponding five heavy rainfall events (excluding Morakot) is positive and the determination coefficient of trend line is 0.98. Furthermore, the relation between the area increment of secondary landslide, average of EAR or the slope disturbance is positive. Under the same slope disturbance, the greater the EAR, the more the area increment of secondary landslide. Contrarily, under the same EAR, the greater the slope disturbance, the more the area increment of secondary landslide. The results of the analysis of this study can be a reference for the government for subsequent countermeasures for slope sediment disaster sensitive area to reduce the number of casualties and significantly reduce the social cost of post-disaster.

Synchrony measure for a neuron driven by excitatory and inhibitory inputs and its adaptation to experimentally-recorded data.

PubMed

Zavou, Christina; Kkoushi, Antria; Koutsou, Achilleas; Christodoulou, Chris

2017-11-01

The aim of the current work is twofold: firstly to adapt an existing method measuring the input synchrony of a neuron driven only by excitatory inputs in such a way so as to account for inhibitory inputs as well and secondly to further appropriately adapt this measure so as to be correctly utilised on experimentally-recorded data. The existing method uses the normalized pre-spike slope (NPSS) of the membrane potential, resulting from observing the slope of depolarization of the membrane potential of a neuron prior to the moment of crossing the threshold within a short period of time, to identify the response-relevant input synchrony and through it to infer the operational mode of a neuron. The first adaptation of NPSS is made such that its upper bound calculation accommodates for the higher possible slope values caused by the lower average and minimum membrane potential values due to inhibitory inputs. Results indicate that when the input spike trains arrive randomly, the modified NPSS works as expected inferring that the neuron is operating as a temporal integrator. When the input spike trains arrive in perfect synchrony though, the modified NPSS works as expected only when the level of inhibition is much higher than the level of excitation. This suggests that calculation of the upper bound of the NPSS should be a function of the ratio between excitatory and inhibitory inputs in order to be able to correctly capture perfect synchrony at a neuron's input. In addition, we effectively demonstrate a process which has to be followed when aiming to use the NPSS on real neuron recordings. This process, which relies on empirical observations of the slope of depolarisation for estimating the bounds for the range of observed interspike interval lengths, is successfully applied to experimentally-recorded data showing that through it both a real neuron's operational mode and the amount of input synchrony that caused its firing can be inferred. Copyright © 2017 Elsevier B.V. All rights reserved.

Characterization of retentivity of reversed phase liquid chromatography columns.

PubMed

Ying, P T; Dorsey, J G

1991-03-01

There are dozens of commercially available reversed phase columns, most marketed as C-8 or C-18 materials, but with no useful way of classifying their retentivity. A useful way of ranking these columns in terms of column "strength" or retentivity is presented. The method utilizes a value for ln k'(w), the estimated retention of a solute from a mobile phase of 100% water, and the slope of the plot of ln k' vsE(T)(30), the solvent polarity. The method is validated with 26 solutes varying in ln k'(w) from about 2 to over 20, on 14 different reversed phase columns. In agreement with previous work, it is found that the phase volume ratio of the column is the most important parameter in determining retentivity. It is strongly suggested that manufacturers adopt a uniform method of calculating this value and that it be made available in advertising, rather than the uninterpretable "% carbon".

Efficient Meshfree Large Deformation Simulation of Rainfall Induced Soil Slope Failure

NASA Astrophysics Data System (ADS)

Wang, Dongdong; Li, Ling

2010-05-01

An efficient Lagrangian Galerkin meshfree framework is presented for large deformation simulation of rainfall-induced soil slope failure. Detailed coupled soil-rainfall seepage equations are given for the proposed formulation. This nonlinear meshfree formulation is featured by the Lagrangian stabilized conforming nodal integration method where the low cost nature of nodal integration approach is kept and at the same time the numerical stability is maintained. The initiation and evolution of progressive failure in the soil slope is modeled by the coupled constitutive equations of isotropic damage and Drucker-Prager pressure-dependent plasticity. The gradient smoothing in the stabilized conforming integration also serves as a non-local regularization of material instability and consequently the present method is capable of effectively capture the shear band failure. The efficacy of the present method is demonstrated by simulating the rainfall-induced failure of two typical soil slopes.

VLT-MAD Observations of Trumpler 14

NASA Astrophysics Data System (ADS)

Rochau, B.; Brandner, W.; Stolte, A.; Henning, T.; da Rio, N.; Gennaro, M.; Hormuth, F.; Marchetti, E.; Amico, P.

We present H and KS observations of the young massive cluster Trumpler 14 obtained with the MCAO system VLT-MAD which provides homogeneous Strehl ratios over a large field of view. We derived maximum Strehl ratios of 9.8% and 12.6% with mean Strehl ratios of 6.0% and 5.9% with in H and K_S, respectively, revealing significant improvement of the spatial PSF stability compared to SCAO systems. We detected 2-3 times more sources than comparable seeing-limited observations, and comparison of the colour-magnitude diagram with isochrones reveals a very young cluster that originated in a starburst-like event 1 ± 0.5 Myr ago. We also tentatively detect hints for an older population of 3 Myr. The mass function between 0.25 Msun and 3.2 Msun appears as a broken power law with a change of the power law slope at m_c ˜ 0.53+0.12-0.10 Msun. Shallow power law slopes are found to be Gamma_{PD,PMS1} = ˜ 0.48 ± 0.11 above m_c and Gamma_{PD,PMS2} = 0.68 ± 0.30 below m_c.

Exercise oscillatory breathing and increased ventilation to carbon dioxide production slope in heart failure: an unfavorable combination with high prognostic value.

PubMed

Guazzi, Marco; Arena, Ross; Ascione, Aniello; Piepoli, Massimo; Guazzi, Maurizio D

2007-05-01

Increased slope of exercise ventilation to carbon dioxide production (VE/VCO2) is an established prognosticator in patients with heart failure. Recently, the occurrence of exercise oscillatory breathing (EOB) has emerged as an additional strong indicator of survival. The aim of this study is to define the respective prognostic significance of these variables and whether excess risk may be identified when either respiratory disorder is present. In 288 stable chronic HF patients (average left ventricular ejection fraction, 33 +/- 13%) who underwent cardiopulmonary exercise testing, the prognostic relevance of VE/VCO2 slope, EOB, and peak VO2 was evaluated by multivariate Cox regression. During a mean interval of 28 +/- 13 months, 62 patients died of cardiac reasons. Thirty-five percent presented with EOB. Among patients exhibiting EOB, 54% had an elevated VE/VCO2 slope. The optimal threshold value for the VE/VCO2 slope identified by receiver operating characteristic analysis was < 36.2 or > or = 36.2 (sensitivity, 77%; specificity, 64%; P < .001). Univariate predictors of death included low left ventricular ejection fraction, low peak VO2, high VE/VCO2 slope, and EOB presence. Multivariate analysis selected EOB as the strongest predictor (chi2, 46.5; P < .001). The VE/VCO2 slope (threshold, < 36.2 or > or = 36.2) was the only other exercise test variable retained in the regression (residual chi2, 5.9; P = .02). The hazard ratio for subjects with EOB and a VE/VCO2 slope > or = 36.2 was 11.4 (95% confidence interval, 4.9-26.5; P < .001). These findings identify EOB as a strong survival predictor even more powerful than VE/VCO2 slope. Exercise oscillatory breathing presence does not necessarily imply an elevated VE/VCO2 slope, but combination of either both yields to a burden of risk remarkably high.

Method for Making Measurements of the Post-Combustion Residence Time in a Gas Turbine Engine

NASA Technical Reports Server (NTRS)

Miles, Jeffrey H. (Inventor)

2017-01-01

A method of measuring a residence time in a gas-turbine engine is disclosed that includes measuring a combustor pressure signal at a combustor entrance and a turbine exit pressure signal at a turbine exit. The method further includes computing a cross-spectrum function between the combustor pressure signal and the turbine exit pressure signal, calculating a slope of the cross-spectrum function, shifting the turbine exit pressure signal an amount corresponding to a time delay between the measurement of the combustor pressure signal and the turbine exit pressure signal, and recalculating the slope of the cross-spectrum function until the slope reaches zero.

Standard line slopes as a measure of a relative matrix effect in quantitative HPLC-MS bioanalysis.

PubMed

Matuszewski, B K

2006-01-18

A simple experimental approach for studying and identifying the relative matrix effect (for example "plasma-to-plasma" and/or "urine-to-urine") in quantitative analyses by HPLC-MS/MS is described. Using as a database a large number of examples of methods developed in recent years in our laboratories, the relationship between the precision of standard line slopes constructed in five different lots of a biofluid (for example plasma) and the reliability of determination of concentration of an analyte in a particular plasma lot (or subject) was examined. In addition, the precision of standard line slopes was compared when stable isotope-labeled analytes versus analogs were used as internal standards (IS). Also, in some cases, a direct comparison of standard line slopes was made when different HPLC-MS interfaces (APCI versus ESI) were used for the assay of the same compound, using the same IS and the same sample preparation and chromatographic separation conditions. In selected cases, the precision of standard line slopes in five different lots of a biofluid was compared with precision values determined five times in a single lot. The results of these studies indicated that the variability of standard line slopes in different lots of a biofluid [precision of standard line slopes expressed as coefficient of variation, CV (%)] may serve as a good indicator of a relative matrix effect and, it is suggested, this precision value should not exceed 3-4% for the method to be considered reliable and free from the relative matrix effect liability. Based on the results presented, in order to assess the relative matrix effect in bioanalytical methods, it is recommended to perform assay precision and accuracy determination in five different lots of a biofluid, instead of repeat (n=5) analysis in the same, single biofluid lot, calculate standard line slopes and precision of these slopes, and to use <3-4% slope precision value as a guide for method applicability to support clinical studies. It was also demonstrated that when stable isotope-labeled analytes were used as internal standards, the precision of standard line slopes in five different lots of a biofluid was

l0 regularization based on a prior image incorporated non-local means for limited-angle X-ray CT reconstruction.

PubMed

Zhang, Lingli; Zeng, Li; Guo, Yumeng

2018-01-01

Restricted by the scanning environment in some CT imaging modalities, the acquired projection data are usually incomplete, which may lead to a limited-angle reconstruction problem. Thus, image quality usually suffers from the slope artifacts. The objective of this study is to first investigate the distorted domains of the reconstructed images which encounter the slope artifacts and then present a new iterative reconstruction method to address the limited-angle X-ray CT reconstruction problem. The presented framework of new method exploits the structural similarity between the prior image and the reconstructed image aiming to compensate the distorted edges. Specifically, the new method utilizes l0 regularization and wavelet tight framelets to suppress the slope artifacts and pursue the sparsity. New method includes following 4 steps to (1) address the data fidelity using SART; (2) compensate for the slope artifacts due to the missed projection data using the prior image and modified nonlocal means (PNLM); (3) utilize l0 regularization to suppress the slope artifacts and pursue the sparsity of wavelet coefficients of the transformed image by using iterative hard thresholding (l0W); and (4) apply an inverse wavelet transform to reconstruct image. In summary, this method is referred to as "l0W-PNLM". Numerical implementations showed that the presented l0W-PNLM was superior to suppress the slope artifacts while preserving the edges of some features as compared to the commercial and other popular investigative algorithms. When the image to be reconstructed is inconsistent with the prior image, the new method can avoid or minimize the distorted edges in the reconstructed images. Quantitative assessments also showed that applying the new method obtained the highest image quality comparing to the existing algorithms. This study demonstrated that the presented l0W-PNLM yielded higher image quality due to a number of unique characteristics, which include that (1) it utilizes the structural similarity between the reconstructed image and prior image to modify the distorted edges by slope artifacts; (2) it adopts wavelet tight frames to obtain the first and high derivative in several directions and levels; and (3) it takes advantage of l0 regularization to promote the sparsity of wavelet coefficients, which is effective for the inhibition of the slope artifacts. Therefore, the new method can address the limited-angle CT reconstruction problem effectively and have practical significance.

The physico-chemical properties and structural characteristics of artificial soil for cut slope restoration in Southwestern China

PubMed Central

Chen, Shunan; Ai, Xiaoyan; Dong, Tengyun; Li, Binbin; Luo, Ruihong; Ai, Yingwei; Chen, Zhaoqiong; Li, Chuanren

2016-01-01

Cut slopes are frequently generated by construction work in hilly areas, and artificial soil is often sprayed onto them to promote ecological rehabilitation. The artificial soil properties are very important for effective management of the slopes. This paper uses fractal and moment methods to characterize soil particle size distribution (PSD) and aggregates composition. The fractal dimension (D) showed linear relationships between clay, silt, and sand contents, with coefficients of determination from 0.843 to 0.875, suggesting that using of D to evaluate the PSD of artificial soils is reasonable. The bias (CS) and peak convex (CE) coefficients showed significant correlations with structure failure rate, moisture content, and total porosity, which validated the moment method to quantitatively describe soil structure. Railway slope (RS) soil has lower organic carbon and soil moisture, and higher pH than natural slope soil. Overall, RS exhibited poor soil structure and physicochemical properties, increasing the risk of soil erosion. Hence, more effective management measures should be adopted to promote the restoration of cut slopes. PMID:26883986

Fitting psychometric functions using a fixed-slope parameter: an advanced alternative for estimating odor thresholds with data generated by ASTM E679.

PubMed

Peng, Mei; Jaeger, Sara R; Hautus, Michael J

2014-03-01

Psychometric functions are predominately used for estimating detection thresholds in vision and audition. However, the requirement of large data quantities for fitting psychometric functions (>30 replications) reduces their suitability in olfactory studies because olfactory response data are often limited (<4 replications) due to the susceptibility of human olfactory receptors to fatigue and adaptation. This article introduces a new method for fitting individual-judge psychometric functions to olfactory data obtained using the current standard protocol-American Society for Testing and Materials (ASTM) E679. The slope parameter of the individual-judge psychometric function is fixed to be the same as that of the group function; the same-shaped symmetrical sigmoid function is fitted only using the intercept. This study evaluated the proposed method by comparing it with 2 available methods. Comparison to conventional psychometric functions (fitted slope and intercept) indicated that the assumption of a fixed slope did not compromise precision of the threshold estimates. No systematic difference was obtained between the proposed method and the ASTM method in terms of group threshold estimates or threshold distributions, but there were changes in the rank, by threshold, of judges in the group. Overall, the fixed-slope psychometric function is recommended for obtaining relatively reliable individual threshold estimates when the quantity of data is limited.

Investigation of upper mantle seismic discontinuities beneath the Indian Ocean using array seismology methods

NASA Astrophysics Data System (ADS)

van Driel, J.; Reiss, A. S.; Thomas, C.

2016-12-01

The topography of upper mantle seismic discontinuities can be used to constrain regional variations in composition and temperature of the Earths mantle. The 410 km discontinuity is caused by the solid-solid phase transition from olivine to wadsleyite. Due to its positive Clapeyron slope, the discontinuity is depressed in hot regimes. The phase transition from ringwoodite to bridgemanite and magnesiowüstite in contrast has a negative Clapeyron slope and therefore is elevated when hot material is present. Cold material is expected to yield an opposing topographic signature, culminating in an elevated 410 km and a depressed 660 km discontinuity. As part of the RHUM-RUM project (Réunion Hotspot and Upper Mantle - Réunions Unterer Mantel) we extract relevant geophysical parameters, by investigating the properties of upper mantle seismic discontinuities beneath the Indian Ocean. The topography of the 410 and 660 km discontinuities, which define the upper and lower bounds of the mantle transition zone, have been mapped using PP and SS underside reflections. This study has utilised over 8500 events with Mw ≥ 5.8, distributed over the entire Indian Ocean. Our robust data set yields a dense coverage of points, which are defined by consistently crossing ray paths. Array seismology methods, such as vespagrams and slowness-backazimuth analysis, are used to enhance the signal-to-noise-ratio and detect and identify weak precursor signals. The differential travel times are corrected for crustal features and converted into depth values of the discontinuities by comparing the measured travel times with theoretical ones derived from ray tracing through the 1D reference Earth model ak135. A `travel-time' stacking method has also been applied for 4° radius bins around each of the bounce points. The addition of a secondary method derives greater stability of our results and allows an enhanced error analysis procedure. In order to better constrain the mineralogical processes taking place within the mantle transition zone, amplitude ratios, polarities and velocity gradients have also been investigated.

Radial dependence of the dark matter distribution in M33

NASA Astrophysics Data System (ADS)

López Fune, E.; Salucci, P.; Corbelli, E.

2017-06-01

The stellar and gaseous mass distributions, as well as the extended rotation curve, in the nearby galaxy M33 are used to derive the radial distribution of dark matter density in the halo and to test cosmological models of galaxy formation and evolution. Two methods are examined to constrain the dark mass density profiles. The first method deals directly with fitting the rotation curve data in the range of galactocentric distances 0.24 ≤ r ≤ 22.72 kpc. Using the results of collisionless Λ cold dark matter numerical simulations, we confirm that the Navarro-Frenkel-White (NFW) dark matter profile provides a better fit to the rotation curve data than the cored Burkert profile (BRK) profile. The second method relies on the local equation of centrifugal equilibrium and on the rotation curve slope. In the aforementioned range of distances, we fit the observed velocity profile, using a function that has a rational dependence on the radius, and we derive the slope of the rotation curve. Then, we infer the effective matter densities. In the radial range 9.53 ≤ r ≤ 22.72 kpc, the uncertainties induced by the luminous matter (stars and gas) become negligible, because the dark matter density dominates, and we can determine locally the radial distribution of dark matter. With this second method, we tested the NFW and BRK dark matter profiles and we can confirm that both profiles are compatible with the data, even though in this case the cored BRK density profile provides a more reasonable value for the baryonic-to-dark matter ratio.

Favourable Changes of the Risk-Benefit Ratio in Alpine Skiing

PubMed Central

Burtscher, Martin; Ruedl, Gerhard

2015-01-01

During the past five decades recreational alpine skiing has become increasingly safer. The numerous annual media reports on ski injuries have to be interpreted on the basis of the tremendous numbers of skiers. These favourable changes seem primarily be due to the introduction of short carving skis, more rigid and comfortable ski boots, the use of protective gear like helmets, and the optimized preparation of ski slopes. The associated health benefits from skiing, especially arising from its association with a healthier life style, and possibly also from effects related to hypoxia preconditioning and increasing subjective vitality by natural elements clearly outweigh the health hazards. Technical improvements will likely help further reducing the injury risk. At least hypothetically, each individual skier could help to prevent injuries by the development of an appropriate physical fitness and responsible behaviour on ski slopes thereby optimizing the risk-benefit ratio of alpine skiing. PMID:26035659

[Effects of land use type on the distribution of organic carbon in different sized soil particles effects of land use type on the distribution of organic carbon in different sized soil particles and its relationships to herb biomass in hilly red soil region of South China].

PubMed

Li, Zhong-Wu; Guo, Wang; Wang, Xiao-Yan; Shen, Wei-Ping; Zhang, Xue; Chen, Xiao-Lin; Zhang, Yue-Nan

2012-04-01

The changes in organic carbon content in different sized soil particles under different land use patterns partly reflect the variation of soil carbon, being of significance in revealing the process of soil organic carbon cycle. Based on the long-term monitoring of soil erosion, and by the methods of soil particle size fractionation, this paper studied the effects of different land use types (wasteland, pinewood land, and grassland) on the distribution of organic carbon content in different sized soil particles and its relationships to the herb biomass. Land use type and slope position had obvious effects on the organic carbon content in different sized soil particles, and the organic carbon content was in the order of grassland > pinewood land > wasteland. The proportion of the organic carbon in different sized soil particles was mainly depended on the land use type, and had little relationships with slope position. According to the analysis of the ratio of particle-associated organic carbon to mineral-associated organic carbon (POC/MOC), the soil organic carbon in grassland was easily to be mineralized, whereas that in wasteland and pinewood land was relatively stable. On the slopes mainly in hilly red soil region, the soil organic carbon in sand fraction had great effects on herb biomass.

Changes in organic aerosol composition with aging inferred from aerosol mass spectra

NASA Astrophysics Data System (ADS)

Ng, N. L.; Canagaratna, M. R.; Jimenez, J. L.; Chhabra, P. S.; Seinfeld, J. H.; Worsnop, D. R.

2011-03-01

Organic aerosols (OA) can be separated with factor analysis of aerosol mass spectrometer (AMS) data into hydrocarbon-like OA (HOA) and oxygenated OA (OOA). We develop a new method to parameterize H:C of OOA in terms of f43 (ratio of m/z 43, mostly C2H3O+, to total signal in the component mass spectrum). Such parameterization allows the transformation of large database of ambient OOA components from the f44 (mostly CO2+, likely from acid groups) vs. f43 space ("triangle plot") (Ng et al., 2010) into the Van Krevelen diagram (H:C vs. O:C). Heald et al. (2010) suggested that the bulk composition of OA line up in the Van Krevelen diagram with a slope ~ -1; such slope can potentially arise from the physical mixing of HOA and OOA, and/or from chemical aging of these components. In this study, we find that the OOA components from all sites occupy an area in the Van Krevelen space, with the evolution of OOA following a shallower slope of ~ -0.5, consistent with the additions of both acid and alcohol functional groups without fragmentation, and/or the addition of acid groups with C-C bond breakage. The importance of acid formation in OOA evolution is consistent with increasing f44 in the triangle plot with photochemical age. These results provide a framework for linking the bulk aerosol chemical composition evolution to molecular-level studies.

Effect on long-term average spectrum of pop singers' vocal warm-up with vocal function exercises.

PubMed

Guzman, Marco; Angulo, Mabel; Muñoz, Daniel; Mayerhoff, Ross

2013-04-01

Abstract This case-control study aimed to investigate if there is any change on the spectral slope declination immediately after vocal function exercises (VFE) vs traditional vocal warm-up exercises in normal singers. Thirty-eight pop singers with perceptually normal voices were divided into two groups: an experimental group (n = 20) and a control group (n = 18). One single session with VFE for the experimental group and traditional singing warm-up exercises for the control group was applied. Voice was recorded before and after the exercises. The recorded tasks were to read a phonetically balanced text and to sing a song. Long-term average spectrum (LTAS) analysis included alpha ratio, L1-L0 ratio, and singing power ratio (SPR). Acoustic parameters of voice samples pre- and post-training were compared. Comparison between VFE and control group was also performed. Significant changes after treatment included the alpha ratio and singing power ratio in speaking voice, and SPR in the singing voice for VFE group. The traditional vocal warm-up of the control group also showed pre-post changes. Significant differences between VFE group and control group for alpha ratio and SPR were found in speaking voice samples. This study demonstrates that VFE have an immediate effect on the spectrum of the voice, specifically a decrease on the spectral slope declination. The results of this study provide support for the advantageous effect of VFE as vocal warm-up on voice quality.

Soil radium, soil gas radon and indoor radon empirical relationships to assist in post-closure impact assessment related to near-surface radioactive waste disposal.

PubMed

Appleton, J D; Cave, M R; Miles, J C H; Sumerling, T J

2011-03-01

Least squares (LS), Theil's (TS) and weighted total least squares (WTLS) regression analysis methods are used to develop empirical relationships between radium in the ground, radon in soil and radon in dwellings to assist in the post-closure assessment of indoor radon related to near-surface radioactive waste disposal at the Low Level Waste Repository in England. The data sets used are (i) estimated ²²⁶Ra in the < 2 mm fraction of topsoils (eRa226) derived from equivalent uranium (eU) from airborne gamma spectrometry data, (ii) eRa226 derived from measurements of uranium in soil geochemical samples, (iii) soil gas radon and (iv) indoor radon data. For models comparing indoor radon and (i) eRa226 derived from airborne eU data and (ii) soil gas radon data, some of the geological groupings have significant slopes. For these groupings there is reasonable agreement in slope and intercept between the three regression analysis methods (LS, TS and WTLS). Relationships between radon in dwellings and radium in the ground or radon in soil differ depending on the characteristics of the underlying geological units, with more permeable units having steeper slopes and higher indoor radon concentrations for a given radium or soil gas radon concentration in the ground. The regression models comparing indoor radon with soil gas radon have intercepts close to 5 Bq m⁻³ whilst the intercepts for those comparing indoor radon with eRa226 from airborne eU vary from about 20 Bq m⁻³ for a moderately permeable geological unit to about 40 Bq m⁻³ for highly permeable limestone, implying unrealistically high contributions to indoor radon from sources other than the ground. An intercept value of 5 Bq m⁻³ is assumed as an appropriate mean value for the UK for sources of indoor radon other than radon from the ground, based on examination of UK data. Comparison with published data used to derive an average indoor radon: soil ²²⁶Ra ratio shows that whereas the published data are generally clustered with no obvious correlation, the data from this study have substantially different relationships depending largely on the permeability of the underlying geology. Models for the relatively impermeable geological units plot parallel to the average indoor radon: soil ²²⁶Ra model but with lower indoor radon: soil ²²⁶Ra ratios, whilst the models for the permeable geological units plot parallel to the average indoor radon: soil ²²⁶Ra model but with higher than average indoor radon: soil ²²⁶Ra ratios. Copyright © 2010 Natural Environment Research Council. Published by Elsevier Ltd.. All rights reserved.

Spline based least squares integration for two-dimensional shape or wavefront reconstruction

DOE PAGES

Huang, Lei; Xue, Junpeng; Gao, Bo; ...

2016-12-21

In this paper, we present a novel method to handle two-dimensional shape or wavefront reconstruction from its slopes. The proposed integration method employs splines to fit the measured slope data with piecewise polynomials and uses the analytical polynomial functions to represent the height changes in a lateral spacing with the pre-determined spline coefficients. The linear least squares method is applied to estimate the height or wavefront as a final result. Numerical simulations verify that the proposed method has less algorithm errors than two other existing methods used for comparison. Especially at the boundaries, the proposed method has better performance. Themore » noise influence is studied by adding white Gaussian noise to the slope data. Finally, experimental data from phase measuring deflectometry are tested to demonstrate the feasibility of the new method in a practical measurement.« less

Spline based least squares integration for two-dimensional shape or wavefront reconstruction

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

Huang, Lei; Xue, Junpeng; Gao, Bo

In this paper, we present a novel method to handle two-dimensional shape or wavefront reconstruction from its slopes. The proposed integration method employs splines to fit the measured slope data with piecewise polynomials and uses the analytical polynomial functions to represent the height changes in a lateral spacing with the pre-determined spline coefficients. The linear least squares method is applied to estimate the height or wavefront as a final result. Numerical simulations verify that the proposed method has less algorithm errors than two other existing methods used for comparison. Especially at the boundaries, the proposed method has better performance. Themore » noise influence is studied by adding white Gaussian noise to the slope data. Finally, experimental data from phase measuring deflectometry are tested to demonstrate the feasibility of the new method in a practical measurement.« less

Analysis of slope stabilization by soil bioengineering method

NASA Astrophysics Data System (ADS)

Switala, Barbara Maria; Wu, Wei

2013-04-01

The aim of the project is to create a numerical model which will include the impact of vegetation on the slope stability analysis, considering both mechanical and hydrological factors. This will enrich the current knowledge about how roots reinforce the soil layers on the slope and how it influences the increase of shear strength of the soil. This has to be combined together with hydrological effects caused by evapotranspiration: modified soil moisture regime, dissipation of excess pore pressure and established matric suction. Coupled analyses (mechanical and hydrological) are rarely conducted, or only outdated models are used, which leads to overestimation of the additional shear strength of soil. That is why there is a need to support this branch of landslide hazard assessment and develop a new model. This research will help to raise awareness, that soil bioengineering methods of slope stabilization can in some cases be more appropriate and less expensive than traditional methods. As an input to the model, the appropriate slope geometry and soil properties have to be chosen. It is also important to consider different plant types and root properties, as well as different levels of groundwater table. To assess the effect of evapotranspiration it is necessary to know the geographical location of the slope and the weather conditions in the chosen region. The final output of the model, which will help to quantitatively assess the impact of vegetation on the slope stability, is the factor of safety (FOS) for vegetated slope for different types of soil and degrees of saturation. Results may then be compared with different conditions and factors of safety, calculated for the corresponding non-vegetated slope. It will be possible to specify the most favorable and unfavorable conditions. Moreover, the calculations provide also information on changes of cohesion, caused by mechanical and hydrological effects, as well as the change in the friction angle of soil.

The effect of plant root system on temperature and moisture of road cutting slope in seasonal frozen regions

NASA Astrophysics Data System (ADS)

Shan, W.; Guo, Y.

2009-04-01

In recent years, in the seasonal frozen regions of Northeast China, the construction of highway improved enormously people's journey condition, but also brought a series of environmental question. In order to meet the route requirement, it is inevitable to excavate the mountain slope, which damage the surface vegetation and cut off the runoff passage of groundwater, cause the outcrop of underground water on the cutting slope and affecte the intrinsic ground stress equilibrium of the slope body, lead to the redistribution of ground stress and the heat balance change in near-surface of the cutting slope. Under influence of rainfall in autumn and the cold climate in winter, the moisture transfer to frozen zone of cutting slope and lead to the frost heave in shallow depth of the slope. During the thawing period in spring, with effect of integrated factors including rainfall and increasing temperature, ice kernels both on the surface and near the surface of cut slope thaw quickly. The water melting from frozen soil, will hampered by frozen layer in process of infiltration. As a result, the water content of the intersection between the freezing and melting layer is high enough to be saturation or even over-saturation, and accordingly cause the intrinsic effective stress on the slope body decreased. Under the function of gravity, near-surface slope collapses partially or entirely. As experience of highway construction accumulated, and the consciousness of environmental protection strengthen, the efficiency and the rationality of plant protection slope was realized gradually, slope protection method has transited gradually from masonry body to combined with plant protection, or complete plant protection. Adopted the method combined field test and lab test, this article analyzed the effect of plant system on the temperature and moisture of soil body, especially the root-soil system in freezing process. The results showed that compared with non plant, the soil body protected by plant had lower moisture content and freeze slowly, which indicated the plant could made the condition of moisture and temperature in the slope better, then reduced the destruction of freezing and thawing to the road slope. The study result could provide theory support for the design of plant protection in the slope of seasonal frozen regions. Key words: road slope, season frozen regions, plant protection, temperature, moisture

Field instrumentation, monitoring of drilled shafts for landslide stabilization and development of pertinent design method.

DOT National Transportation Integrated Search

2010-11-01

The design method for using a single row, spaced drilled shafts, socketed into a firm rock strata, to stabilize : an unstable slope has been developed in this research. The soil arching due to the presence of spaced : drilled shafts in a slope was ob...

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.

A Hybrid FEM-ANN Approach for Slope Instability Prediction

NASA Astrophysics Data System (ADS)

Verma, A. K.; Singh, T. N.; Chauhan, Nikhil Kumar; Sarkar, K.

2016-09-01

Assessment of slope stability is one of the most critical aspects for the life of a slope. In any slope vulnerability appraisal, Factor Of Safety (FOS) is the widely accepted index to understand, how close or far a slope from the failure. In this work, an attempt has been made to simulate a road cut slope in a landslide prone area in Rudrapryag, Uttarakhand, India which lies near Himalayan geodynamic mountain belt. A combination of Finite Element Method (FEM) and Artificial Neural Network (ANN) has been adopted to predict FOS of the slope. In ANN, a three layer, feed- forward back-propagation neural network with one input layer and one hidden layer with three neurons and one output layer has been considered and trained using datasets generated from numerical analysis of the slope and validated with new set of field slope data. Mean absolute percentage error estimated as 1.04 with coefficient of correlation between the FOS of FEM and ANN as 0.973, which indicates that the system is very vigorous and fast to predict FOS for any slope.

Searching for the signatures of terrestrial planets in F-, G-type main-sequence stars

NASA Astrophysics Data System (ADS)

González Hernández, J. I.; Delgado-Mena, E.; Sousa, S. G.; Israelian, G.; Santos, N. C.; Adibekyan, V. Zh.; Udry, S.

2013-04-01

Context. Detailed chemical abundances of volatile and refractory elements have been discussed in the context of terrestrial-planet formation during in past years. Aims: The HARPS-GTO high-precision planet-search program has provided an extensive database of stellar spectra, which we have inspected in order to select the best-quality spectra available for late type stars. We study the volatile-to-refractory abundance ratios to investigate their possible relation with the low-mass planetary formation. Methods: We present a fully differential chemical abundance analysis using high-quality HARPS and UVES spectra of 61 late F- and early G-type main-sequence stars, where 29 are planet hosts and 32 are stars without detected planets. Results: As for the previous sample of solar analogs, these stars slightly hotter than the Sun also provide very accurate Galactic chemical abundance trends in the metallicity range -0.3 < [Fe/H] < 0.4. Stars with and without planets show similar mean abundance ratios. Moreover, when removing the Galactic chemical evolution effects, these mean abundance ratios, Δ [X/Fe] SUN - STARS, against condensation temperature, tend to exhibit less steep trends with nearly zero or slightly negative slopes. We have also analyzed a subsample of 26 metal-rich stars, 13 with and 13 without known planets, with spectra at S/N ~ 850, on average, in the narrow metallicity range 0.04 < [Fe/H] < 0.19. We find the similar, although not equal, abundance pattern with negative slopes for both samples of stars with and without planets. Using stars at S/N ≥ 550 provides equally steep abundance trends with negative slopes for stars both with and without planets. We revisit the sample of solar analogs to study the abundance patterns of these stars, in particular, 8 stars hosting super-Earth-like planets. Among these stars having very low-mass planets, only four of them reveal clear increasing abundance trends versus condensation temperature. Conclusions: Finally, we compared these observed slopes with those predicted using a simple model that enables us to compute the mass of rocks that have formed terrestrial planets in each planetary system. We do not find any evidence supporting the conclusion that the volatile-to-refractory abundance ratio is related to the presence of rocky planets. Based on observations collected with the HARPS spectrograph at the 3.6-m telescope (072.C-0488(E)), installed at the La Silla Observatory, ESO (Chile), with the UVES spectrograph at the 8-m Very Large Telescope (VLT) - program IDs: 67.C-0206(A), 074.C-0134(A), 075.D-0453(A) -, installed at the Cerro Paranal Observatory, ESO (Chile), and with the UES spectrograph at the 4.2-m William Herschel Telescope (WHT), installed at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias, on the island of La Palma.Tables A.1-A.8 are only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/552/A6

Downward Slope Driving Control for Electric Powered Wheelchair Based on Capacitor Regenerative Brake

NASA Astrophysics Data System (ADS)

Seki, Hirokazu; Takahashi, Yoshiaki

This paper describes a novel capacitor regenerative braking control scheme of electric powered wheelchairs for efficient driving on downward slopes. An electric powered wheelchair, which generates the driving force by electric motors, is expected to be widely used as a mobility support system for elderly people and disabled people; however the energy efficiency has to be further improved because it is driven only by battery energy. This study proposes a capacitor regenerative braking circuit and two types of velocity control schemes with variable duty ratio. The proposed regenerative braking circuit is based on the step-up/down circuit with additional resistance and connects right and left motors in series in order to obtain a larger braking power. Some driving experiments on a practical downward slope show the effectiveness of the proposed control system.

A quantification method for peroxyacetyl nitrate (PAN) using gas chromatography (GC) with a non-radioactive pulsed discharge detector (PDD)

NASA Astrophysics Data System (ADS)

Zhang, Lei; Jaffe, Daniel A.; Gao, Xin; McClure, Crystal D.

2018-04-01

In this study, we developed a method for continuous PAN measurements by gas chromatography (GC) with a non-radioactive pulsed discharge detector (PDD). Operational parameters were optimized based on the ratio of peak height over baseline noise (P/N ratio). The GC/PDD system was compared with a traditional radioactive electron-capture detector (ECD). In the lab, the method detection limit (MDL) of the new GC/PDD method (9 pptv) was lower than the radioactive GC/ECD method (15 pptv), demonstrating its excellent potential. The MDL of GC/PDD in the field campaign at the Mt. Bachelor Observatory (MBO) was 23 pptv, higher than in the lab. This was caused in part by the decreased slope of the calibration curve resulting from the low air pressure level at MBO. However, the MDL level of GC/PDD at MBO is still low enough for accurate PAN measurements, although special attention should be paid to its application at high-elevation sites. Observations of PAN were conducted at MBO in the summer of 2016 with the GC/PDD system, and provided more evidence of the performance of the system. PAN was found to be highly correlated with CO. The promising performance of GC/PDD which does not require a radioactive source makes it a useful approach for accurate PAN measurements in the field.

Influence of slope on subtalar pronation in submaximal running performance

PubMed Central

de Oliveira, Vinicius Machado; Detoni, Guilherme Cesca; Ferreira, Cristhian; Portela, Bruno Sergio; Queiroga, Marcos Roberto; Tartaruga, Marcus Peikriszwili

2013-01-01

OBJECTIVE : To investigate the slope influence on the maximal subtalar pronation in submaximal running speeds. METHODS : Sixteen endurance runners participated of a running economy (RE) test in a treadmill with different slopes (+1%, +5%, +10%, +15%). For each slope a 4-minute run was performed with no rest break for the purpose of measuring the magnitude of kinematic variables by means of a high frequency video camera positioned in a frontal-posterior plane of the individual. RESULTS : No significant differences were verified in maximal subtalar pronation between legs and between the slopes adopted, showing that changes of running technique due to modifications of slope aren't enough to modify the behavior of maximum subtalar pronation. CONCLUSION : The subtalar pronation is independent of slope, which may be influenced by other intervening variables. Level of Evidence II, Diagnostic Study PMID:24453662

Spiny Mice Modulate Eumelanin to Pheomelanin Ratio to Achieve Cryptic Coloration in “Evolution Canyon,” Israel

PubMed Central

Singaravelan, Natarajan; Pavlicek, Tomas; Beharav, Alex; Wakamatsu, Kazumasa; Ito, Shosuke; Nevo, Eviatar

2010-01-01

Background Coat coloration in mammals is an explicit adaptation through natural selection. Camouflaging with the environment is the foremost evolutionary drive in explaining overall coloration. Decades of enquiries on this topic have been limited to repetitive coat color measurements to correlate the morphs with background/habitat blending. This led to an overwhelming endorsement of concealing coloration as a local phenotypic adaptation in animals, primarily rodents to evade predators. However, most such studies overlooked how rodents actually achieve such cryptic coloration. Cryptic coloration could be attained only through optimization between the yellow- to brown-colored “pheomelanin” and gray to black-colored “eumelanin” in the hairs. However, no study has explored this conjecture yet. “Evolution Canyon” (EC) in Israel is a natural microscale laboratory where the relationship between organism and environment can be explored. EC is comprised of an “African” slope (AS), which exhibits a yellow-brownish background habitat, and a “European” slope (ES), exhibiting a dark grayish habitat; both slopes harbor spiny mice (Acomys cahirinus). Here, we examine how hair melanin content of spiny mice living in the opposing slopes of EC evolves toward blending with their respective background habitat. Methodology/Principal Findings We measured hair-melanin (both eumelanin and pheomelanin) contents of 30 spiny mice from the EC using high-performance liquid chromatography (HPLC) that detects specific degradation products of eumelanin and pheomelanin. The melanin pattern of A. cahirinus approximates the background color of the slope on which they dwell. Pheomelanin is slightly (insignificantly) higher in individuals found on the AS to match the brownish background, whereas individuals of the ES had significantly greater eumelanin content to mimic the dark grayish background. This is further substantiated by a significantly higher eumelanin and pheomelanin ratio on the ES than on the AS. Conclusion/Significance It appears that rodents adaptively modulate eumelanin and pheomelanin contents to achieve cryptic coloration in contrasting habitats even at a microscale. PMID:20090935

Benthic Community Structure and Sediment Geochemical Properties at Hydrocarbon Seeps Along the Continental Slope of the Western North Atlantic

NASA Astrophysics Data System (ADS)

Demopoulos, A. W.; Bourque, J. R.; Brooke, S.

2015-12-01

Hydrocarbon seeps support distinct benthic communities capable of utilizing reduced chemical compounds for nutrition. In recent years, methane seepage has been increasingly documented along the continental slope of the U.S. Atlantic margin. In 2012 and 2013, two seeps were investigated in this region: a shallow site near Baltimore Canyon (410-450 m) and a deep site near Norfolk Canyon (1600 m). Both sites contain extensive mussel beds and microbial mats. Sediment cores and grab samples were collected to quantify the abundance, diversity, and community structure of benthic macrofauna (>300 mm) in relationship to the associated sediment environment (organic carbon and nitrogen, stable isotopes 13C and 15N, grain size, and depth) of mussel beds, mats, and slope habitats. Macrofaunal densities in microbial mats were four times greater than those present in mussel beds and slope sediments. Macrofaunal communities were distinctly different both between depths and among habitat types. Specifically, microbial mat sediments were dominated by the annelid families Dorvilleidae, Capitellidae, and Tubificidae, while mussel habitats had higher proportions of crustaceans. Diversity was lower in Baltimore microbial mat habitats, but higher in mussel and slope sediments compared to Norfolk seep habitats found at deeper depths. Multivariate statistical analysis identified sediment carbon:nitrogen (C:N) ratios and 13C values as important variables for structuring the macrofaunal communities. Higher C:N ratios were present within microbial mat habitats and depleted 13C values occurred in sediments adjacent to mussel beds found in Norfolk Canyon seeps. Differences in the quality and source of organic matter present in the seep habitats are known to be important drivers in macrofaunal community structure and associated food webs. The multivariate analysis provides new insight into the relative importance of the seep sediment quality in supporting dense macrofaunal communities compared to other seeps found throughout the region.

Trends of improved water and sanitation coverage around the globe between 1990 and 2010: inequality among countries and performance of official development assistance

PubMed Central

Cha, Seungman; Mankadi, Paul Mansiangi; Elhag, Mousab Siddig; Lee, Yongjoo; Jin, Yan

2017-01-01

ABSTRACT Background: As the Millennium Development Goals ended, and were replaced by the Sustainable Development Goals, efforts have been made to evaluate the achievements and performance of official development assistance (ODA) in the health sector. In this study, we explore trends in the expansion of water and sanitation coverage in developing countries and the performance of ODA. Design: We explored inequality across developing countries by income level, and investigated how ODA for water and sanitation was committed by country, region, and income level. Changes in inequality were tested via slope changes by investigating the interaction of year and income level with a likelihood ratio test. A random effects model was applied according to the results of the Hausman test. Results: The slope of the linear trend between economic level and sanitation coverage has declined over time. However, a random effects model suggested that the change in slope across years was not significant (e.g. for the slope change between 2000 and 2010: likelihood ratio χ2 = 2.49, probability > χ2 = 0.1146). A similar pro-rich pattern across developing countries and a non-significant change in the slope associated with different economic levels were demonstrated for water coverage. Our analysis shows that the inequality of water and sanitation coverage among countries across the world has not been addressed effectively during the past decade. Our findings demonstrate that the countries with the least coverage persistently received far less ODA per capita than did countries with much more extensive water and sanitation coverage, suggesting that ODA for water and sanitation is poorly targeted. Conclusion: The most deprived countries should receive more attention for water and sanitation improvements from the world health community. A strong political commitment to ODA targeting the countries with the least coverage is needed at the global level. PMID:28604256

Measuring OVOCs and VOCs by PTR-MS in an urban roadside microenvironment of Hong Kong: relative humidity and temperature dependence, and field intercomparisons

NASA Astrophysics Data System (ADS)

Cui, Long; Zhang, Zhou; Huang, Yu; Lee, Shun Cheng; Blake, Donald Ray; Ho, Kin Fai; Wang, Bei; Gao, Yuan; Wang, Xin Ming; Kwok Keung Louie, Peter

2016-12-01

Volatile organic compound (VOC) control is an important issue of air quality management in Hong Kong because ozone formation is generally VOC limited. Several oxygenated volatile organic compound (OVOC) and VOC measurement techniques - namely, (1) offline 2,4-dinitrophenylhydrazine (DNPH) cartridge sampling followed by high-performance liquid chromatography (HPLC) analysis; (2) online gas chromatography (GC) with flame ionization detection (FID); and (3) offline canister sampling followed by GC with mass spectrometer detection (MSD), FID, and electron capture detection (ECD) - were applied during this study. For the first time, the proton transfer reaction-mass spectrometry (PTR-MS) technique was also introduced to measured OVOCs and VOCs in an urban roadside area of Hong Kong. The integrated effect of ambient relative humidity (RH) and temperature (T) on formaldehyde measurements by PTR-MS was explored in this study. A Poly 2-D regression was found to be the best nonlinear surface simulation (r = 0.97) of the experimental reaction rate coefficient ratio, ambient RH, and T for formaldehyde measurement. This correction method was found to be better than correcting formaldehyde concentrations directly via the absolute humidity of inlet sample, based on a 2-year field sampling campaign at Mong Kok (MK) in Hong Kong. For OVOC species, formaldehyde, acetaldehyde, acetone, and MEK showed good agreements between PTR-MS and DNPH-HPLC with slopes of 1.00, 1.10, 0.76, and 0.88, respectively, and correlation coefficients of 0.79, 0.75, 0.60, and 0.93, respectively. Overall, fair agreements were found between PTR-MS and online GC-FID for benzene (slope = 1.23, r = 0.95), toluene (slope = 1.01, r = 0.96) and C2-benzenes (slope = 1.02, r = 0.96) after correcting benzene and C2-benzenes levels which could be affected by fragments formed from ethylbenzene. For the intercomparisons between PTR-MS and offline canister measurements by GC-MSD/FID/ECD, benzene showed good agreement, with a slope of 1.05 (r = 0.62), though PTR-MS had lower values for toluene and C2-benzenes with slopes of 0.78 (r = 0.96) and 0.67 (r = 0.92), respectively. All in all, the PTR-MS instrument is suitable for OVOC and VOC measurements in urban roadside areas.

Atlas-based automatic measurements of the morphology of the tibiofemoral joint

NASA Astrophysics Data System (ADS)

Brehler, M.; Thawait, G.; Shyr, W.; Ramsay, J.; Siewerdsen, J. H.; Zbijewski, W.

2017-03-01

Purpose: Anatomical metrics of the tibiofemoral joint support assessment of joint stability and surgical planning. We propose an automated, atlas-based algorithm to streamline the measurements in 3D images of the joint and reduce userdependence of the metrics arising from manual identification of the anatomical landmarks. Methods: The method is initialized with coarse registrations of a set of atlas images to the fixed input image. The initial registrations are then refined separately for the tibia and femur and the best matching atlas is selected. Finally, the anatomical landmarks of the best matching atlas are transformed onto the input image by deforming a surface model of the atlas to fit the shape of the tibial plateau in the input image (a mesh-to-volume registration). We apply the method to weight-bearing volumetric images of the knee obtained from 23 subjects using an extremity cone-beam CT system. Results of the automated algorithm were compared to an expert radiologist for measurements of Static Alignment (SA), Medial Tibial Slope (MTS) and Lateral Tibial Slope (LTS). Results: Intra-reader variability as high as 10% for LTS and 7% for MTS (ratio of standard deviation to the mean in repeated measurements) was found for expert radiologist, illustrating the potential benefits of an automated approach in improving the precision of the metrics. The proposed method achieved excellent registration of the atlas mesh to the input volumes. The resulting automated measurements yielded high correlations with expert radiologist, as indicated by correlation coefficients of 0.72 for MTS, 0.8 for LTS, and 0.89 for SA. Conclusions: The automated method for measurement of anatomical metrics of the tibiofemoral joint achieves high correlation with expert radiologist without the need for time consuming and error prone manual selection of landmarks.

Preliminary study on differentiation between glaucomatous and non-glaucomatous eyes on stereo fundus images using cup gradient models

NASA Astrophysics Data System (ADS)

Muramatsu, Chisako; Hatanaka, Yuji; Ishida, Kyoko; Sawada, Akira; Yamamoto, Tetsuya; Fujita, Hiroshi

2014-03-01

Glaucoma is one of the leading causes of blindness in Japan and the US. One of the indices for diagnosis of glaucoma is the cup-to-disc ratio (CDR). We have been developing a computerized method for measuring CDR on stereo fundus photographs. Although our previous study indicated that the method may be useful, cup determination was not always successful, especially for the normal eyes. In this study, we investigated a new method to quantify the likelihood of glaucomatous disc based on the similarity scores to the glaucoma and non-glaucoma models. Eighty-seven images, including 40 glaucomatous eyes, were used in this study. Only one eye from each patient was used. Using a stereo fundus camera, two images were captured from different angles, and the depth image was created by finding the local corresponding points. One of the characteristics of a glaucomatous disc can be not only that the cup is enlarged but it has an acute slope. On the other hand, a non-glaucomatous cup generally has a gentle slope. Therefore, our models were constructed by averaging the depth gradient images. In order to account for disc size, disc outline was automatically detected, and all images were registered by warping the disc outline to a circle with a predetermined diameter using thin plate splines. Similarity scores were determined by multiplying a test case with both models. At the sensitivity of 90.0%, the specificity was improved from 83.0% using the CDR to 97.9% by the model-based method. The proposed method may be useful for differentiation of glaucomatous eyes.

Correlation between river slope and meandering variability (obtained by DGPS data) and morphotectonics for two Andean tributaries of the Amazon river: the case of Beni (Bolivia) and Napo (Ecuador-Peru) rivers.

NASA Astrophysics Data System (ADS)

Bourrel, L.; Darrozes, J.; Guyot, J.; Christophoul, F.; Bondoux, F.

2007-05-01

The Beni river drains a catchment area of 282 000 km2 of which 40 percent are located in the Cordillera of the Bolivian and Peruvian Andes, and the rest in the Amazonian plain : the studied reaches runs from Guanay (Andean Piedmont) to Riberalta (junction with Madre de Dios river) that represents a distance by the river of 1055 km. The Napo river starts in the Ecuadorian Andes and leaves Ecuador in Nuevo Rocafuerte (27 400 km2) and enters in Peru until its junction with the Amazon river : the studied section runs from Misahualli (Andean Piedmont) to this junction, that represents a distance by the river of 995 km. The GPS data were acquired using a mobile GPS embarked on a boat and 4 fixed bases located along the Beni river, 6 along the Napo river and the two rivers profile calculated from post-treated differential GPS solutions. For the Beni river, two sectors were identified: - the upstream sector (~230 km) between Guanay (414 m) and 50 km downstream Rurrenabaque (245 m) is located in Andean Piedmont, which consists in a series of thrusts associated with anticlines and synclines (the subandean zone), and presents slope values range between 135 cm/km and 10 cm/km and an average index of sinuosity (IS) of 1.29, - the downstream sector (~ 820 km) which runs in Amazonian plain (until Riberalta -165 m-), is characterized by an average slope of 8 cm/km and an average IS of 2.06 (this sector is much more homogeneous and the Beni river shows a meandering channel). For the Napo River, three sectors were identified: - the first sector (~140 km) between Misahualli (401 m) and Coca (265 m), is located in Andean Piedmont (subandean zone) and presents slope values range between 170 cm/km and 30 cm/km and an average IS of 1.6, - the second sector (~250 km) between Coca (when the Napo river enters in the Amazonian plain) and Nuevo Rocafuerte (190 m), presents slope values range between 30 cm/km and 20 cm/km and an average IS of 1.2, and a convex-up shape profile corresponding to the preserved part of the Pastaza-Napo Megafan, not yet affected by headwater erosion, - the third sector (~600 km) between Nuevo Rocafuerte and the confluence with the Amazon river (101 m), where the Napo river flows through the quaternary deposits of the Pastaza-Napo Megafan, presents slope values ranging from 20 to 10 cm/km and an average IS of 1.2, and is characterized by a more classical concave-up shape profile. Our main results established using DGPS data (an important difference between the slope and IS averages of the Napo and the Beni rivers in their Amazonian part, respectively ~20 cm/km and ~8 cm/km, ie a ratio ~2.5, 1.2 and 2.06, ie a ratio ~0.6) bring an additional explanation to the results obtained by the preceding authors, with balance methods, and confirm respectively the erosion and the sedimentation behaviour of the Napo and the Beni rivers.

Porosity determination from 2-D resistivity method in studying the slope failures

NASA Astrophysics Data System (ADS)

Maslinda, Umi; Nordiana, M. M.; Bery, A. A.

2017-07-01

Slope failures have become the main focus for infrastructures development on hilly areas in Malaysia especially the development of tourism and residential. Lack of understanding and information of the subsoil conditions and geotechnical issues are the main cause of the slope failures. The failures happened are due to a combination of few factors such as topography, climate, geology and land use. 2-D resistivity method was conducted at the collapsed area in Selangor. The 2-D resistivity was done to study the instability of the area. The collapsed occurred because of the subsurface materials was unstable. Pole-dipole array was used with 5 m minimum electrode spacing for the 2-D resistivity method. The data was processed using Res2Dinv software and the porosity was calculated using Archie's law equation. The results show that the saturated zone (1-100 Ωm), alluvium or highly weathered rock (100-1000 Ωm), boulders (1600-7000 Ωm) and granitic bedrock (>7000 Ωm). Generally, the slope failures or landslides occur during the wet season or after rainfall. It is because of the water infiltrate to the slope and cause the saturation of the slope which can lead to landslides. Then, the porosity of saturated zone is usually high because of the water content. The area of alluvium or highly weathered rock and saturated zone have high porosity (>20%) and the high porosity also dominated at almost all the collapsed area which means that the materials with porosity >20% is potential to be saturated, unstable and might trigger slope failures.

Prediction of zeolite-cement-sand unconfined compressive strength using polynomial neural network

NASA Astrophysics Data System (ADS)

MolaAbasi, H.; Shooshpasha, I.

2016-04-01

The improvement of local soils with cement and zeolite can provide great benefits, including strengthening slopes in slope stability problems, stabilizing problematic soils and preventing soil liquefaction. Recently, dosage methodologies are being developed for improved soils based on a rational criterion as it exists in concrete technology. There are numerous earlier studies showing the possibility of relating Unconfined Compressive Strength (UCS) and Cemented sand (CS) parameters (voids/cement ratio) as a power function fits. Taking into account the fact that the existing equations are incapable of estimating UCS for zeolite cemented sand mixture (ZCS) well, artificial intelligence methods are used for forecasting them. Polynomial-type neural network is applied to estimate the UCS from more simply determined index properties such as zeolite and cement content, porosity as well as curing time. In order to assess the merits of the proposed approach, a total number of 216 unconfined compressive tests have been done. A comparison is carried out between the experimentally measured UCS with the predictions in order to evaluate the performance of the current method. The results demonstrate that generalized polynomial-type neural network has a great ability for prediction of the UCS. At the end sensitivity analysis of the polynomial model is applied to study the influence of input parameters on model output. The sensitivity analysis reveals that cement and zeolite content have significant influence on predicting UCS.

Hα kinematics of S4G spiral galaxies - III. Inner rotation curves

NASA Astrophysics Data System (ADS)

Erroz-Ferrer, Santiago; Knapen, Johan H.; Leaman, Ryan; Díaz-García, Simón; Salo, Heikki; Laurikainen, Eija; Querejeta, Miguel; Muñoz-Mateos, Juan Carlos; Athanassoula, E.; Bosma, Albert; Comerón, Sebastien; Elmegreen, Bruce G.; Martínez-Valpuesta, Inma

2016-05-01

We present a detailed study of the shape of the innermost part of the rotation curves of a sample of 29 nearby spiral galaxies, based on high angular and spectral resolution kinematic Hα Fabry-Perot observations. In particular, we quantify the steepness of the rotation curve by measuring its slope dRvc(0). We explore the relationship between the inner slope and several galaxy parameters, such as stellar mass, maximum rotational velocity, central surface brightness (μ0), bar strength and bulge-to-total ratio. Even with our limited dynamical range, we find a trend for low-mass galaxies to exhibit shallower rotation curve inner slopes than high-mass galaxies, whereas steep inner slopes are found exclusively in high-mass galaxies. This trend may arise from the relationship between the total stellar mass and the mass of the bulge, which are correlated among them. We find a correlation between the inner slope of the rotation curve and the morphological T-type, complementary to the scaling relation between dRvc(0) and μ0 previously reported in the literature. Although we find that the inner slope increases with the Fourier amplitude A2 and decreases with the bar torque Qb, this may arise from the presence of the bulge implicit in both A2 and Qb. As previously noted in the literature, the more compact the mass in the central parts of a galaxy (more concretely, the presence of a bulge), the steeper the inner slopes. We conclude that the baryonic matter dominates the dynamics in the central parts of our sample galaxies.

Modeling landslide recurrence in Seattle, Washington, USA

USGS Publications Warehouse

Salciarini, Diana; Godt, Jonathan W.; Savage, William Z.; Baum, Rex L.; Conversini, Pietro

2008-01-01

To manage the hazard associated with shallow landslides, decision makers need an understanding of where and when landslides may occur. A variety of approaches have been used to estimate the hazard from shallow, rainfall-triggered landslides, such as empirical rainfall threshold methods or probabilistic methods based on historical records. The wide availability of Geographic Information Systems (GIS) and digital topographic data has led to the development of analytic methods for landslide hazard estimation that couple steady-state hydrological models with slope stability calculations. Because these methods typically neglect the transient effects of infiltration on slope stability, results cannot be linked with historical or forecasted rainfall sequences. Estimates of the frequency of conditions likely to cause landslides are critical for quantitative risk and hazard assessments. We present results to demonstrate how a transient infiltration model coupled with an infinite slope stability calculation may be used to assess shallow landslide frequency in the City of Seattle, Washington, USA. A module called CRF (Critical RainFall) for estimating deterministic rainfall thresholds has been integrated in the TRIGRS (Transient Rainfall Infiltration and Grid-based Slope-Stability) model that combines a transient, one-dimensional analytic solution for pore-pressure response to rainfall infiltration with an infinite slope stability calculation. Input data for the extended model include topographic slope, colluvial thickness, initial water-table depth, material properties, and rainfall durations. This approach is combined with a statistical treatment of rainfall using a GEV (General Extreme Value) probabilistic distribution to produce maps showing the shallow landslide recurrence induced, on a spatially distributed basis, as a function of rainfall duration and hillslope characteristics.

Quantification of Shear-Relative Asymmetries in Eyewall Slope Using Airborne Doppler Radar Composites

NASA Astrophysics Data System (ADS)

Hazelton, A.; Rogers, R.; Hart, R. E.

2013-12-01

Recently, it has become apparent that typical methods for analyzing tropical cyclones (TCs), such as track and intensity, are insufficient for evaluating TC structural evolution and numerical model forecasts of that evolution. Many studies have analyzed different metrics related to TC inner-core structure in an attempt to better understand the processes that drive changes in core structure. One important metric related to vertical TC structure is the slope of the eyewall. Hazelton and Hart (2013) discussed azimuthal mean eyewall slope based on radar reflectivity data, and its relationship with TC intensity and core structure. That study also noted significant azimuthal variation in slopes, but did not significantly explore reasons for this variation. Accordingly, in this study, we attempt to quantify the role of vertical wind shear in causing azimuthal variance of slope, using research quality Doppler radar composites from the NOAA Hurricane Research Division (HRD). We analyze the slope of the 20 dBZ surface as in Hazelton and Hart (2013), and also look at azimuthal variation in other measures of eyewall slope, such as the slope of the radius of maximum winds (RMW), which has been analyzed in an azimuthal mean sense by Stern and Nolan (2009), and an angular momentum surface. The shear-relative slopes are quantified by separating the radar data into four quadrants relative to the vertical shear vector: Downshear Left (DSL), Upshear Left (USL), Upshear Right (USR), and Downshear Right (DSR). This follows the method employed in shear-relative analyses of other aspects of TC core structure, such as Rogers et al. (2013) and Reasor et al. (2013). The data suitable for use in this study consist of 36 flights into 15 different TCs (14 Atlantic, 1 Eastern Pacific) between 1997 and 2010. Preliminary results show apparent shear-induced asymmetries in eyewall slope. The slope of the RMW shows an asymmetry due to the tilt of the vortex approximately along the shear vector, with an average slope (in ° from vertical) in the two downshear quadrants of 36.5° and an average slope of 16.3° in the two upshear quadrants (p < 0.05). This result is consistent with a case-study analysis by Rogers and Uhlhorn (2008) of changes in RMW slope in the lower levels of Hurricane Rita. In addition, the slope of an angular momentum surface shows a similar pattern to the RMW. The slope of the 20 dBZ surface does not show as well-defined a signal. However, by separating the cases into TCs that were strengthening or weakening/steady, we found that the difference between dBZ slope and M slope is important in distinguishing between the sets. The 20 dBZ surface tended to be more upright than an M surface in the azimuthal mean and in two of the four quadrants for intensifying cases, and less upright than the M surface for weakening/steady-state cases (p < 0.05). This result is consistent with a conceptual model for intensifying vs. steady-state TCs described in Rogers et al. (2013). Further analysis will continue to explore methods to quantify the effects of vertical shear on the TC secondary circulation using the metric of eyewall slope.

Proceedings, Seminar on Probabilistic Methods in Geotechnical Engineering

NASA Astrophysics Data System (ADS)

Hynes-Griffin, M. E.; Buege, L. L.

1983-09-01

Contents: Applications of Probabilistic Methods in Geotechnical Engineering; Probabilistic Seismic and Geotechnical Evaluation at a Dam Site; Probabilistic Slope Stability Methodology; Probability of Liquefaction in a 3-D Soil Deposit; Probabilistic Design of Flood Levees; Probabilistic and Statistical Methods for Determining Rock Mass Deformability Beneath Foundations: An Overview; Simple Statistical Methodology for Evaluating Rock Mechanics Exploration Data; New Developments in Statistical Techniques for Analyzing Rock Slope Stability.

On the concept of sloped motion for free-floating wave energy converters.

PubMed

Payne, Grégory S; Pascal, Rémy; Vaillant, Guillaume

2015-10-08

A free-floating wave energy converter (WEC) concept whose power take-off (PTO) system reacts against water inertia is investigated herein. The main focus is the impact of inclining the PTO direction on the system performance. The study is based on a numerical model whose formulation is first derived in detail. Hydrodynamics coefficients are obtained using the linear boundary element method package WAMIT. Verification of the model is provided prior to its use for a PTO parametric study and a multi-objective optimization based on a multi-linear regression method. It is found that inclining the direction of the PTO at around 50° to the vertical is highly beneficial for the WEC performance in that it provides a high capture width ratio over a broad region of the wave period range.

On the concept of sloped motion for free-floating wave energy converters

PubMed Central

Payne, Grégory S.; Pascal, Rémy; Vaillant, Guillaume

2015-01-01

A free-floating wave energy converter (WEC) concept whose power take-off (PTO) system reacts against water inertia is investigated herein. The main focus is the impact of inclining the PTO direction on the system performance. The study is based on a numerical model whose formulation is first derived in detail. Hydrodynamics coefficients are obtained using the linear boundary element method package WAMIT. Verification of the model is provided prior to its use for a PTO parametric study and a multi-objective optimization based on a multi-linear regression method. It is found that inclining the direction of the PTO at around 50° to the vertical is highly beneficial for the WEC performance in that it provides a high capture width ratio over a broad region of the wave period range. PMID:26543397

[Responses of accumulation-loss patterns for soil organic carbon and its fractions to tillage and water erosion in black soil area].

PubMed

Zhao, Peng Zhi; Chen, Xiang Wei; Wang, En Heng

2017-11-01

Tillage and water erosion have been recognized as the main factors causing degradation in soil organic carbon (SOC) pools of black soil. To further explore the response of SOC and its fractions to different driving forces of erosion (tillage and water), geostatistical methods were used to analyze spatial patterns of SOC and its three fractions at a typical sloping farmland based on tillage and water erosion rates calculated by local models. The results showed that tillage erosion and deposition rates changed according to the slope positions, decreasing in the order: upper-slope > lower-slope > middle-slope > toe-slope and toe-slope > lower-slope > middle-slope > upper-slope, respectively; while the order of water erosion rates decreased in the order: lower-slope > toe-slope > middle-slope > upper-slope. Tillage and water erosion cooperatively triggered intense soil loss in the lower-slope areas with steep slope gradient. Tillage erosion could affect C cycling through the whole slope at different levels, although the rate of tillage erosion (0.02-7.02 t·hm -2 ·a -1 ) was far less than that of water erosion (5.96-101.17 t·hm -2 ·a -1 ) in black soil area. However, water erosion only played a major role in controlling C dynamics in the runoff-concentrated lower slope area. Affected by water erosion and tillage erosion-deposition disturbance, the concentrations of SOC, particulate organic carbon and dissolved organic carbon in depositional areas were higher than in erosional areas, however, microbial biomass carbon showed an opposite trend. Tillage erosion dominated SOC dynamic by depleting particulate organic carbon.

Method of Preparation AZP4330 PR Pattern with Edge Slope 40°

NASA Astrophysics Data System (ADS)

Wu, Jie; Zhao, Hongyuan; Yu, Yuanwei; Zhu, Jian

2018-03-01

When the edge which is under the multi-film is more steep or angular, the stress in the multilayer film near the edge is concentrated, this situation will greatly reduce the reliability of electronic components. And sometimes, we need some special structure such as a slope with a specific angle in the MEMS, so that the metal line can take the signal to the output pad through the slope instead of deep step. To cover these problems, the lithography method of preparing the structure with edge slope is studied. In this paper, based on the Kirchhoff scalar diffraction theory we try to change the contact exposure gap and the post-baking time at the specific temperature to find out the effect about the edge angle of the photoresist. After test by SEM, the results were presented by using AZP4330 photoresist, we can get the PR Pattern with edge slope 40° of the process and the specific process parameters.

Characteristics of large particles and their effects on the submarine light field

NASA Astrophysics Data System (ADS)

Hou, Weilin

Large particles play important roles in the ocean by modifying the underwater light field and effecting material transfer. The particle size distribution of large particles has been measured in-situ with multiple- camera video microscopy and the automated particle sizing and recognition software developed. Results show that there are more large particles in coastal waters than previously thaught, based upon by a hyperbolic size- distribution curve with a (log-log) slope parameter of close to 3 instead of 4 for the particles larger than 100μm diameter. Larger slopes are more typical for particles in the open ocean. This slope permits estimation of the distribution into the small-particle size range for use in correcting the beam-attenuation measurements for near-forward scattering. The large- particle slope and c-meter were used to estimate the small-particle size distributions which nearly matched those measured with a Coulter Counteroler (3.05%). There is also a fair correlation (r2=0.729) between the slope of the distribution and its concentration parameters. Scattering by large particles is influenced by not only the concentrations of these particles, but also the scattering phase functions. This first in-situ measurement of large-particle scattering with multiple angles reveals that they scatter more in the backward direction than was previously believed, and the enhanced backscattering can be explained in part by multiple scattering of aggregated particles. Proper identification of these large particles can be of great help in understanding the status of the ecosystem. By extracting particle features using high-resolution video images via moment-invariant functions and applying this information to lower-resolution images, we increase the effective sample volume without severely degrading classification efficiency. Traditional pattern recognition algorithms of images classified zooplankton with results within 24% of zooplankton collected using bottle samples. A faster particle recognition scheme using optical scattering is introduced and test results are satisfactory with an average error of 32%. This method promises given that the signal-to-noise ratio of the observations can be improved.

Landslide susceptibility mapping along PLUS expressways in Malaysia using probabilistic based model in GIS

NASA Astrophysics Data System (ADS)

Yusof, Norbazlan M.; Pradhan, Biswajeet

2014-06-01

PLUS Berhad holds the concession for a total of 987 km of toll expressways in Malaysia, the longest of which is the North-South Expressway or NSE. Acting as the backbone' of the west coast of the peninsula, the NSE stretches from the Malaysian-Thai border in the north to the border with neighbouring Singapore in the south, linking several major cities and towns along the way. North-South Expressway in Malaysia contributes to the country economic development through trade, social and tourism sector. Presently, the highway is good in terms of its condition and connection to every state but some locations need urgent attention. Stability of slopes at these locations is of most concern as any instability can cause danger to the motorist. In this paper, two study locations have been analysed; they are Gua Tempurung (soil slope) and Jelapang (rock slope) which are obviously having two different characteristics. These locations passed through undulating terrain with steep slopes where landslides are common and the probability of slope instability due to human activities in surrounding areas is high. A combination of twelve (12) landslide conditioning factors database on slope stability such as slope degree and slope aspect were extracted from IFSAR (interoferometric synthetic aperture radar) while landuse, lithology and structural geology were constructed from interpretation of high resolution satellite data from World View II, Quickbird and Ikonos. All this information was analysed in geographic information system (GIS) environment for landslide susceptibility mapping using probabilistic based frequency ratio model. Consequently, information on the slopes such as inventories, condition assessments and maintenance records were assessed through total expressway maintenance management system or better known as TEMAN. The above mentioned system is used by PLUS as an asset management and decision support tools for maintenance activities along the highways as well as for data quality checking and integrity. In this study, TEMAN data were further analysed and subsequently integrated with landslide susceptible map for Gua Tempurung and Jelapang area in Perak.

Threshold setting by the surround of cat retinal ganglion cells.

PubMed

Barlow, H B; Levick, W R

1976-08-01

1. The slope of curves relating the log increment threshold to log background luminance in cat retinal ganglion cells is affected by the area and duration of the test stimulus, as it is in human pyschophysical experiments. 2. Using large area, long duration stimuli the slopes average 0-82 and approach close to 1 (Weber's Law) in the steepest cases. Small stimuli gave an average of 0-53 for on-centre units using brief stimuli, and 0-56 for off-centre units, using long stimuli. Slopes under 0-5 (square root law) were not found over an extended range of luminances. 3. On individual units the slope was generally greater for larger and longer test stimulus, but no unit showed the full extent of change from slope of 0-5 to slope of 1. 4. The above differences hold for objective measures of quantum/spike ratio, as well as for thresholds either judged by ear or assessed by calculation. 5. The steeper slope of the curves for large area, long duration test stimuli compared with small, long duration stimuli, is associated with the increased effectiveness of antagonism from the surround at high backgrounds. This change may be less pronounced in off-centre units, one of which (probably transient Y-type) showed no difference of slope, and gave parallel area-threshold curves at widely separated background luminances, confirming the importance of differential surround effectiveness in changing the slope of the curves. 6. In on-centre units, the increased relative effectiveness of the surround is associated with the part of the raised background light that falls on the receptive field centre. 7. It is suggested that the variable surround functions as a zero-offset control that sets the threshold excitation required for generating impulses, and that this is separate from gain-setting adaptive mechanisms. This may be how ganglion cells maintain high incremental sensitivity in spite of a strong maintained excitatory drive that would otherwise cause compressive response non-linearities.

Electron density and electron temperature measurement in a bi-Maxwellian electron distribution using a derivative method of Langmuir probes

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

Choi, Ikjin; Chung, ChinWook; Youn Moon, Se

2013-08-15

In plasma diagnostics with a single Langmuir probe, the electron temperature T{sub e} is usually obtained from the slope of the logarithm of the electron current or from the electron energy probability functions of current (I)-voltage (V) curve. Recently, Chen [F. F. Chen, Phys. Plasmas 8, 3029 (2001)] suggested a derivative analysis method to obtain T{sub e} by the ratio between the probe current and the derivative of the probe current at a plasma potential where the ion current becomes zero. Based on this method, electron temperatures and electron densities were measured and compared with those from the electron energymore » distribution function (EEDF) measurement in Maxwellian and bi-Maxwellian electron distribution conditions. In a bi-Maxwellian electron distribution, we found the electron temperature T{sub e} obtained from the method is always lower than the effective temperatures T{sub eff} derived from EEDFs. The theoretical analysis for this is presented.« less

Analytical quality assurance in veterinary drug residue analysis methods: matrix effects determination and monitoring for sulfonamides analysis.

PubMed

Hoff, Rodrigo Barcellos; Rübensam, Gabriel; Jank, Louise; Barreto, Fabiano; Peralba, Maria do Carmo Ruaro; Pizzolato, Tânia Mara; Silvia Díaz-Cruz, M; Barceló, Damià

2015-01-01

In residue analysis of veterinary drugs in foodstuff, matrix effects are one of the most critical points. This work present a discuss considering approaches used to estimate, minimize and monitoring matrix effects in bioanalytical methods. Qualitative and quantitative methods for estimation of matrix effects such as post-column infusion, slopes ratios analysis, calibration curves (mathematical and statistical analysis) and control chart monitoring are discussed using real data. Matrix effects varying in a wide range depending of the analyte and the sample preparation method: pressurized liquid extraction for liver samples show matrix effects from 15.5 to 59.2% while a ultrasound-assisted extraction provide values from 21.7 to 64.3%. The matrix influence was also evaluated: for sulfamethazine analysis, losses of signal were varying from -37 to -96% for fish and eggs, respectively. Advantages and drawbacks are also discussed considering a workflow for matrix effects assessment proposed and applied to real data from sulfonamides residues analysis. Copyright © 2014 Elsevier B.V. All rights reserved.

Analysis of Infiltration-Suction Response in Unsaturated Residual Soil Slope in Gelugor, Penang

NASA Astrophysics Data System (ADS)

Ashraf Mohamad Ismail, Mohd; Hasliza Hamzah, Nur; Min, Ng Soon; Hazreek Zainal Abidin, Mohd; Tajudin, Saiful Azhar Ahmad; Madun, Aziman

2018-04-01

Rainfall infiltration on residual soil slope may impair slope stability by altering the pore-water pressure in the soil. A study has been carried out on unsaturated residual soil slope in Gelugor, Penang to determine the changes in matric suction of residual soils at different depth due to rainwater infiltration. The sequence of this study includes the site investigation, field instrumentation, laboratory experiment and numerical modeling. Void ratio and porosity of soil were found to be decreasing with depth while the bulk density and dry density of soil increased due to lower porosity of soil at greater depth. Soil infiltration rate and matric suction of all depths decrease with the increase of volumetric water content as well as the degree of saturation. Numerical modeling was used to verify and predict the relationship between infiltration-suction response and degree of saturation. Numerical models can be used to integrate the rainfall scenarios into quantitative landslide hazard assessments. Thus, development plans and mitigation measures can be designed for estimated impacts from hazard assessments based on collected data.

Analytical Study of the Mechanical Behavior of Fully Grouted Bolts in Bedding Rock Slopes

NASA Astrophysics Data System (ADS)

Liu, C. H.; Li, Y. Z.

2017-09-01

Bolting is widely used as a reinforcement means for rock slopes. The support force of a fully grouted bolt is often provided by the combination of the axial and shear forces acting at the cross section of the bolt, especially for bedding rock slopes. In this paper, load distribution and deformation behavior of the deflecting section of a fully grouted bolt were analyzed, and a structural mechanical model was established. Based on force method equations and deformation compatibility relationships, an analytical approach, describing the contribution of the axial and shear forces acting at the intersection between the bolt and the joint plane to the stability of a rock slope, was developed. Influence of the inclination of the bolt to the joint plane was discussed. Laboratory tests were conducted with different inclinations of the bolt to the joint plane. Comparisons between the proposed approach, the experimental data and a code method were made. The calculation results are in good agreement with the test data. It is shown that transverse shear resistance plays a significant role to the bolting contribution and that the bigger the dip of the bolt to the joint plane, the more significant the dowel effect. It is also shown that the design method suggested in the code overestimates the resistance of the bolt. The proposed model considering dowel effect provides a more precise description on bolting properties of bedding rock slopes than the code method and will be helpful to improve bolting design methods.

Predicting reading outcomes with progress monitoring slopes among middle grade students

PubMed Central

Tolar, Tammy D.; Barth, Amy E.; Fletcher, Jack M.; Francis, David J.; Vaughn, Sharon

2013-01-01

Effective implementation of response-to-intervention (RTI) frameworks depends on efficient tools for monitoring progress. Evaluations of growth (i.e., slope) may be less efficient than evaluations of status at a single time point, especially if slopes do not add to predictions of outcomes over status. We examined progress monitoring slope validity for predicting reading outcomes among middle school students by evaluating latent growth models for different progress monitoring measure-outcome combinations. We used multi-group modeling to evaluate the effects of reading ability, reading intervention, and progress monitoring administration condition on slope validity. Slope validity was greatest when progress monitoring was aligned with the outcome (i.e., word reading fluency slope was used to predict fluency outcomes in contrast to comprehension outcomes), but effects varied across administration conditions (viz., repeated reading of familiar vs. novel passages). Unless the progress monitoring measure is highly aligned with outcome, slope may be an inefficient method for evaluating progress in an RTI context. PMID:24659899

Semi-Automated Classification of Seafloor Data Collected on the Delmarva Inner Shelf

NASA Astrophysics Data System (ADS)

Sweeney, E. M.; Pendleton, E. A.; Brothers, L. L.; Mahmud, A.; Thieler, E. R.

2017-12-01

We tested automated classification methods on acoustic bathymetry and backscatter data collected by the U.S. Geological Survey (USGS) and National Oceanic and Atmospheric Administration (NOAA) on the Delmarva inner continental shelf to efficiently and objectively identify sediment texture and geomorphology. Automated classification techniques are generally less subjective and take significantly less time than manual classification methods. We used a semi-automated process combining unsupervised and supervised classification techniques to characterize seafloor based on bathymetric slope and relative backscatter intensity. Statistical comparison of our automated classification results with those of a manual classification conducted on a subset of the acoustic imagery indicates that our automated method was highly accurate (95% total accuracy and 93% Kappa). Our methods resolve sediment ridges, zones of flat seafloor and areas of high and low backscatter. We compared our classification scheme with mean grain size statistics of samples collected in the study area and found that strong correlations between backscatter intensity and sediment texture exist. High backscatter zones are associated with the presence of gravel and shells mixed with sand, and low backscatter areas are primarily clean sand or sand mixed with mud. Slope classes further elucidate textural and geomorphologic differences in the seafloor, such that steep slopes (>0.35°) with high backscatter are most often associated with the updrift side of sand ridges and bedforms, whereas low slope with high backscatter correspond to coarse lag or shell deposits. Low backscatter and high slopes are most often found on the downdrift side of ridges and bedforms, and low backscatter and low slopes identify swale areas and sand sheets. We found that poor acoustic data quality was the most significant cause of inaccurate classification results, which required additional user input to mitigate. Our method worked well along the primarily sandy Delmarva inner continental shelf, and outlines a method that can be used to efficiently and consistently produce surficial geologic interpretations of the seafloor from ground-truthed geophysical or hydrographic data.

SINMAP Modeling of an active landslide area in the Swabian Alb

NASA Astrophysics Data System (ADS)

Terhorst, Birgit; Jaeger, Daniel

2015-04-01

Landslides are a common hazard in German low mountain areas such as the Swabian Alb. As areas of former landslides are highly prone to secondary movements, this study aims to assess the susceptibility for landslide hazard around Mössingen-Öschingen, a region consistently affected by landslides during the last decades. Based on the history and development of mass movements and a detailed geomorphological map, slope stability was calculated using SINMAP (Stability Index Mapping). SINMAP (Pack et al., 1998; Tarboton, 1997) is based on the "infinite slope stability model" by Hammond et al. (1992) and Montgomery and Dietrich (1994) describing the ratio of slope stabilizing factors (e.g. cohesion) and slope destabilizing factors (e.g. gravitation) on a slip surface parallel to the slope. Most input parameters are determined by the relief and therefore, can be calculated from a digital terrain model (DTM, resolution 5 m). Based on the local morphology and geology, a total of 10 'calibration regions', each with similar hydrogeological characteristics, were defined. Further input parameters were: Shear strength via friction angle (Phi), cohesion (C) and hydraulic conductivity (T/R). The data was obtained from soil mechanical assessments and field/laboratory analyses. As a result, a specific stability index is calculated, describing the susceptibility of a slope movement. In a first step, the 'topographic wetness index' (derived from catchment area, slope gradient and hydraulic conductivity) was calculated. Results show several preferred (natural) drainage channels with generally higher water saturations in morphological depressions. Several of them can be linked to the location of damaged houses in the settlement area on the lower slope. The SINMAP calculation clearly revealed the impermeable Callovian clay layers as most prone to slope movements. A comparison of the susceptibility map with slide masses which were mapped during a field survey showed generally good agreements. This was in particular true for the slopes of the "Landhaussiedlung", a small settlement area east of Mössingen-Öschingen. In the uphill areas, a large landslide was triggered on June 3rd, 2013, mainly caused by heavy rainfalls during the days before. The scarp/slip surface was situated in the Callovian clay layers and in an area which was shown as susceptible for slope movements by the SINMAP model earlier Terhorst and Kreja (2009). The movement processes reactivated an old slide mass, which reached the outermost parts of the settlement area and damaged the densely built-up underground of the Landhaussiedlung. Although no house was destroyed completely by the slide mass, the induced pressure caused severe damages, rendering the buildings uninhabitable and leading to the evacuation of the Landhaussiedlung. The results show, that the modeling provided a solid identification of the vulnerable slope areas. The recent landslide area is almost completely situated in a region modeled as vulnerable for slope movements. Therefore, the landslide event of 2013 practically validated the susceptibility map. On the base of solid data and under consideration of detailed and differentiated information, SINMAP is a powerful tool for the assessment of susceptibilities for translational slides. Hammond, C., Hall, D., Miller, S., Swetik, P., 1992. Level I Stability Analysis (LISA) documentation for version 2.0. General Technical Report, INT-285. U.S. Deptartment of Agriculture, Forest Service, Intermountain Research Station, Ogden. Montgomery, D.R., Dietrich, W.E., 1994. A Physically Based Model for the Topographic Control on Shallow Landsliding. Water Resources Research, 30(4), 1153-1171. Pack, R.T., Tarboton, D.G., Goodwin, C.N., 1998. The SINMAP approach to terrain stability mapping, 8th Congress of the International Association of Engineering Geology, Vancouver, Canada, pp. 8. Tarboton, D.G., 1997. A new method for the determination of flow directions and upslope areas in grid digital elevation models. Water Resources Research, 33(2), 309-319. Terhorst, B., Kreja, R., 2009. Slope stability modelling with SINMAP in a settlement area of the Swabian Alb. Landslides, 6(4), 309-319.

Structural Damage Detection Using Slopes of Longitudinal Vibration Shapes

DOE PAGES

Xu, W.; Zhu, W. D.; Smith, S. A.; ...

2016-03-18

While structural damage detection based on flexural vibration shapes, such as mode shapes and steady-state response shapes under harmonic excitation, has been well developed, little attention is paid to that based on longitudinal vibration shapes that also contain damage information. This study originally formulates a slope vibration shape for damage detection in bars using longitudinal vibration shapes. To enhance noise robustness of the method, a slope vibration shape is transformed to a multiscale slope vibration shape in a multiscale domain using wavelet transform, which has explicit physical implication, high damage sensitivity, and noise robustness. These advantages are demonstrated in numericalmore » cases of damaged bars, and results show that multiscale slope vibration shapes can be used for identifying and locating damage in a noisy environment. A three-dimensional (3D) scanning laser vibrometer is used to measure the longitudinal steady-state response shape of an aluminum bar with damage due to reduced cross-sectional dimensions under harmonic excitation, and results show that the method can successfully identify and locate the damage. Slopes of longitudinal vibration shapes are shown to be suitable for damage detection in bars and have potential for applications in noisy environments.« less

Change Analysis of Laser Scans of Laboratory Rock Slopes Subject to Wave Attack Testing

NASA Astrophysics Data System (ADS)

Shen, Y.; Lindenbergh, R.; Hofland, B.; Kramer, R.

2017-09-01

For better understanding how coastal structures with gentle slopes behave during high energy events, a wave attack experiment representing a storm of 3000 waves was performed in a flume facility. Two setups with different steepness of slope were compared under the same conditions. In order to quantify changes in the rock slopes after the wave attack, a terrestrial laser scanner was used to obtain 3D coordinates of the rock surface before and after each experiment. Next, through a series of processing steps, the point clouds were converted to a suitable 2D raster for change analysis. This allowed to estimate detailed and quantitative change information. The results indicate that the area around the artificial coast line, defined as the intersection between sloped surface and wave surface, is most strongly affected by wave attacks. As the distances from the sloped surface to the waves are shorter, changes for the mildly sloped surface, slope 1 (1 : 10), are distributed over a larger area compared to the changes for the more steeply sloped surface, slope 2 (1 : 5). The results of this experiment show that terrestrial laser scanning is an effective and feasible method for change analysis of rock slopes in a laboratory setting. Most striking results from a process point of view is that the transport direction of the rocks change between the two different slopes: from seaward transport for the steeper slope to landward transport for the milder slope.

Estimating Slopes In Images Of Terrain By Use Of BRDF

NASA Technical Reports Server (NTRS)

Scholl, Marija S.

1995-01-01

Proposed method of estimating slopes of terrain features based on use of bidirectional reflectivity distribution function (BRDF) in analyzing aerial photographs, satellite video images, or other images produced by remote sensors. Estimated slopes integrated along horizontal coordinates to obtain estimated heights; generating three-dimensional terrain maps. Method does not require coregistration of terrain features in pairs of images acquired from slightly different perspectives nor requires Sun or other source of illumination to be low in sky over terrain of interest. On contrary, best when Sun is high. Works at almost all combinations of illumination and viewing angles.

An Unconditionally Monotone C 2 Quartic Spline Method with Nonoscillation Derivatives

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

Yao, Jin; Nelson, Karl E.

Here, a one-dimensional monotone interpolation method based on interface reconstruction with partial volumes in the slope-space utilizing the Hermite cubic-spline, is proposed. The new method is only quartic, however is C 2 and unconditionally monotone. A set of control points is employed to constrain the curvature of the interpolation function and to eliminate possible nonphysical oscillations in the slope space. An extension of this method in two-dimensions is also discussed.

An Unconditionally Monotone C 2 Quartic Spline Method with Nonoscillation Derivatives

DOE PAGES

Yao, Jin; Nelson, Karl E.

2018-01-24

Here, a one-dimensional monotone interpolation method based on interface reconstruction with partial volumes in the slope-space utilizing the Hermite cubic-spline, is proposed. The new method is only quartic, however is C 2 and unconditionally monotone. A set of control points is employed to constrain the curvature of the interpolation function and to eliminate possible nonphysical oscillations in the slope space. An extension of this method in two-dimensions is also discussed.

The Contribution of Particle Swarm Optimization to Three-Dimensional Slope Stability Analysis

PubMed Central

A Rashid, Ahmad Safuan; Ali, Nazri

2014-01-01

Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to two-dimensional (2D) slope stability analysis. This paper applied PSO in three-dimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI-3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes. PMID:24991652

The contribution of particle swarm optimization to three-dimensional slope stability analysis.

PubMed

Kalatehjari, Roohollah; Rashid, Ahmad Safuan A; Ali, Nazri; Hajihassani, Mohsen

2014-01-01

Over the last few years, particle swarm optimization (PSO) has been extensively applied in various geotechnical engineering including slope stability analysis. However, this contribution was limited to two-dimensional (2D) slope stability analysis. This paper applied PSO in three-dimensional (3D) slope stability problem to determine the critical slip surface (CSS) of soil slopes. A detailed description of adopted PSO was presented to provide a good basis for more contribution of this technique to the field of 3D slope stability problems. A general rotating ellipsoid shape was introduced as the specific particle for 3D slope stability analysis. A detailed sensitivity analysis was designed and performed to find the optimum values of parameters of PSO. Example problems were used to evaluate the applicability of PSO in determining the CSS of 3D slopes. The first example presented a comparison between the results of PSO and PLAXI-3D finite element software and the second example compared the ability of PSO to determine the CSS of 3D slopes with other optimization methods from the literature. The results demonstrated the efficiency and effectiveness of PSO in determining the CSS of 3D soil slopes.

Mechanisms of nitrogen heterocycle influence on turbine fuel stability

NASA Technical Reports Server (NTRS)

Daniel, S. R.; Worstell, J. H.

1980-01-01

Lewis bases were extracted from a Utah COED syncrude via ligand exchange. Addition of this extract to Jet A at levels as low as 5 ppm N produced deterioration of stability in both JFTOT and accelerated storage tests (7 days at 394 K with 13:1air to fuel ratio). Comparable effects on Jet A stability were obtained by addition of pyridine and quinoline, while pyrrole and indole were less detrimental at the same concentration level. The weight of deposit produced accelerated storage tests was found to be proportional to the concentration of added nitrogen compound. Over the narrow temperature range accessible with the experimental method, Arrhenius plots obtained by assuming specific rate to be proportional to the weight of material deposited in seven days exhibit greater slopes in the presence of those nitrogen compounds producing the greater deposition rates. It is shown that despite variation in appearance the elemental composition and spectral characteristics of the deposits are unaffected by addition of the nitrogen compounds. The linearity of the Arrhenius plots and of a plot of Arrhenius slope versus intercept for all the compounds suggests a constancy of mechanism over the range of temperature and heterocycles studied.

Deimos: A featureless asteroid-like spectrum

NASA Technical Reports Server (NTRS)

Grundy, W. M.; Fink, Uwe

1991-01-01

High quality CCD spectra were obtained of Deimos from 0.5 to 1.0 micron at a spectral resolution of 15A at the time of the 1988 Mars opposition. The data acquisition and reduction methods allowed the quantitative prevention of scattered light from Mars contaminating the spectra. Solar analog stars BS560, BS2007, and BS8931 were observed the same night to allow removal of telluric absorptions. The ratio spectrum of Deimos has a red slope, increasing in reflectance by a factor of approx. 50 pct. over the one octave wavelength interval observed. Other than this slope, the spectrum is remarkably featureless. The absence of absorption bands in the spectrum of Deimos is in marked contrast with the spectra of Martian surface materials. No trace of the Fe(2+) charge transfer absorption band around 1 micron is observed, which rules out the presence of significant quantities of minerals such as the pyroxenes or olivine at the surface of Deimos. The featureless red spectrum of Deimos appears to be consistent with a surface composition of fine grained carbonaceous chondrite type material. An analysis is presented of the spectrum of Deimos which makes use of the Hapke scattering surface model.

SAM 2.1—A computer program for plotting and formatting surveying data for estimating peak discharges by the slope-area method

USGS Publications Warehouse

Hortness, J.E.

2004-01-01

The U.S. Geological Survey (USGS) measures discharge in streams using several methods. However, measurement of peak discharges is often impossible or impractical due to difficult access, inherent danger of making measurements during flood events, and timing often associated with flood events. Thus, many peak discharge values often are calculated after the fact by use of indirect methods. The most common indirect method for estimating peak dis- charges in streams is the slope-area method. This, like other indirect methods, requires measuring the flood profile through detailed surveys. Processing the survey data for efficient entry into computer streamflow models can be time demanding; SAM 2.1 is a program designed to expedite that process. The SAM 2.1 computer program is designed to be run in the field on a portable computer. The program processes digital surveying data obtained from an electronic surveying instrument during slope- area measurements. After all measurements have been completed, the program generates files to be input into the SAC (Slope-Area Computation program; Fulford, 1994) or HEC-RAS (Hydrologic Engineering Center-River Analysis System; Brunner, 2001) computer streamflow models so that an estimate of the peak discharge can be calculated.

A Partially Saturated Constitutive Theory for Compacted Fills

DTIC Science & Technology

2004-06-01

degree of Doctor of Philosophy. COL James R. Rowan, EN , was Commander and Executive Director of ERDC, and Dr. James R. Houston was Director. CHAPTER...Reconsolidation Index CR Slope of the reconsolidation line Maximum Friction Angle of3 Friction Angle PHILIM traMaterial Ratio of minimum to maximum4 Phi Ratio PH ...Josa, A., (1988). "Un modelo elastoplastico para suelos no saturados," Tesis Doctorae, Universitat Politecnica de Catalunya, Barcelons, Spain. Lawton

Triple oxygen isotope data characterize oxidation processes that produce sulfate on Earth (and Mars?)

NASA Astrophysics Data System (ADS)

Christensen, J.; Kohl, I.; Coleman, M. L.

2011-12-01

The Rio Tinto, a river in southwest Spain, has a long history of acid, iron and sulfate rich water resulting primarily from the oxidation of pyrite (ferrous iron sulfide). Its geochemistry and extremophile microbiology make it an exciting and ideal mars-analogue research site, as relatively recent discoveries have shown Mars to be rich in sulfates believed to have formed in an acidic environment. Current models for the oxidation pathways of pyrite sulfur to sulfate, and the microbial influences on those pathways are incomplete. Traditionally, studies have only focused on d18O as a tracer for the oxygen sources in sulfate and determination of the oxidation pathways. The d18O method has always been fraught with uncertainty due to isotope fractionation during oxygen incorporation from the two dominant sources, atmospheric oxygen and water. A relatively new method utilizing 17O measures the relationship between d17O/d18O. The average relationship has been defined as the Terrestrial Fractionation Line, with a slope of 0.52. Deviations from this relationship are represented as Cap delta 17O, the difference of delta 17O from the expected value. Cap17O values are useful because they depend only on the relationship between d17O/d18O, which remains constant during mass dependent fractionation. During O2 generation from solid BaSO4, some fractionation can occur due to incomplete oxygen yield. This can produce uncertainties in d17O and d18O, but Cap17O is dependent only on the d17O/d18O ratio and is therefore not affected. The relationship mentioned above between d17O/d18O (slope=0.52) is an average for terrestrial materials and it is becoming increasingly clear that process specific slopes can be defined. This offers an exciting opportunity to characterize potential biomarkers on Mars. If a biologically specific slope could be determined, then its signature will be preserved through subsequent mass dependent fractionation processes. Our approach is to use Río Tinto field and laboratory data to define a process specific slope for natural sulfate, produced via oxidation of pyrite. This study presents field data collected in May of 2011 from various inputs on the Rio Tinto system. The pH range was 0.91-3.18, Eh ranged from 556-831mV. Iron and sulfate were the major ionic species and range from 0.105-587mM and 9.6-989mM, respectively. Initial d18O values are between (-1.5 to +6.0) and are reproducible to (0.8). Cap17O values (calculated with a slope=0.528) range between (0.07-0.192) and are reproducible to (0.007). There is a strong linear relationship between d17O and d18O, which defines a slope or maybe process specific slope of 0.5184, with an R squared value of 0.9995. We will present our update on this ongoing work and our conclusion on whether we have developed a new signature of either or both inorganic and biological oxidation to characterize terrestrial and martian sulfates.

Revegetation of Acid Rock Drainage (ARD) Producing Slope Surface Using Phosphate Microencapsulation and Artificial Soil

NASA Astrophysics Data System (ADS)

Kim, Jae Gon

2017-04-01

Oxidation of sulfides produces acid rock drainage (ARD) upon their exposure to oxidation environment by construction and mining activities. The ARD causes the acidification and metal contamination of soil, surface water and groundwater, the damage of plant, the deterioration of landscape and the reduction of slope stability. The revegetation of slope surface is one of commonly adopted strategies to reduce erosion and to increase slope stability. However, the revegetation of the ARD producing slope surface is frequently failed due to its high acidity and toxic metal content. We developed a revegetation method consisting of microencapsualtion and artificial soil in the laboratory. The revegetation method was applied on the ARD producing slope on which the revegetation using soil coverage and seeding was failed and monitored the plant growth for one year. The phosphate solution was applied on sulfide containing rock to form stable Fe-phosphate mineral on the surface of sulfide, which worked as a physical barrier to prevent contacting oxidants such as oxygen and Fe3+ ion to the sulfide surface. After the microencapsulation, two artificial soil layers were constructed. The first layer containing organic matter, dolomite powder and soil was constructed at 2 cm thickness to neutralize the rising acidic capillary water from the subsurface and to remove the dissolved oxygen from the percolating rain water. Finally, the second layer containing seeds, organic matter, nutrients and soil was constructed at 3 cm thickness on the top. After application of the method, the pH of the soil below the artificial soil layer increased and the ARD production from the rock fragments reduced. The plant growth showed an ordinary state while the plant died two month after germination for the previous revegetation trial. No soil erosion occurred from the slope during the one year field test.

Galileo support observations of Asteroid 951 Gaspra

NASA Technical Reports Server (NTRS)

Goldader, Jeffrey D.; Tholen, David J.; Cruikshank, Dale P.; Hartmann, William K.

1991-01-01

Observations of 951 Gaspra in support of the Galileo spacecraft encounter are reported. Photometric observations of the asteroid yield a synodic rotational period of 7.042 46 and a slope parameter G of 0.285 + or - 0.005. It is inferred from data obtained on May 18, 1990, that the subearth latitude was higher at that time than it was earlier in the opposition. This places a limit on the possible pole orientation of the asteroid. A slope parameter of 0.25 is proposed on the basis of a comparison of the present result for the slope parameter with that of Barucci et al. (1990). A low-quality 0.8-2.5-micron spectrum of 951 Gaspra suggests a high olivine/pyroxene ratio, which is indicative of a source region in the lower mantle of a differentiated asteroid, and similarities to 8 Flora and particularly 15 Eunomia.

Coordinated Control of Slip Ratio for Wheeled Mobile Robots Climbing Loose Sloped Terrain

PubMed Central

Li, Zhengcai; Wang, Yang

2014-01-01

A challenging problem faced by wheeled mobile robots (WMRs) such as planetary rovers traversing loose sloped terrain is the inevitable longitudinal slip suffered by the wheels, which often leads to their deviation from the predetermined trajectory, reduced drive efficiency, and possible failures. This study investigates this problem using terramechanics analysis of the wheel-soil interaction. First, a slope-based wheel-soil interaction terramechanics model is built, and an online slip coordinated algorithm is designed based on the goal of optimal drive efficiency. An equation of state is established using the coordinated slip as the desired input and the actual slip as a state variable. To improve the robustness and adaptability of the control system, an adaptive neural network is designed. Analytical results and those of a simulation using Vortex demonstrate the significantly improved mobile performance of the WMR using the proposed control system. PMID:25276849

Coordinated control of slip ratio for wheeled mobile robots climbing loose sloped terrain.

PubMed

Li, Zhengcai; Wang, Yang

2014-01-01

A challenging problem faced by wheeled mobile robots (WMRs) such as planetary rovers traversing loose sloped terrain is the inevitable longitudinal slip suffered by the wheels, which often leads to their deviation from the predetermined trajectory, reduced drive efficiency, and possible failures. This study investigates this problem using terramechanics analysis of the wheel-soil interaction. First, a slope-based wheel-soil interaction terramechanics model is built, and an online slip coordinated algorithm is designed based on the goal of optimal drive efficiency. An equation of state is established using the coordinated slip as the desired input and the actual slip as a state variable. To improve the robustness and adaptability of the control system, an adaptive neural network is designed. Analytical results and those of a simulation using Vortex demonstrate the significantly improved mobile performance of the WMR using the proposed control system.

Computerized scintigraphic technique for the evaluation of adult respiratory distress syndrome: initial clinical trials

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

Tatum, J.L.; Burke, T.S.; Sugerman, H.T.

1982-04-01

Eleven patients with suspected adult respiratory distress syndrome (ARDS) and five control patients were studied using a computerized gamma imaging and analysis technique and /sup 99m/Tc-labeled human serum albumin. The heart and right lung were imaged, lung:heart ratio was plotted vs. time, and a linear regression was fitted to the data points displayed. The slope of this fit was termed the ''slope index.'' An index value of 2 standard deviations greater than the control mean was considered positive. Radiographs from the six positive studies revealed typical diffuse air-space disease. Radiographs from two of the five negative studies demonstrated air-space consolidation.more » Both of these patients had elevated pulmonary capillary wedge pressure, cardiomegaly, and clinical course consistent with cardiogenic pulmonary edema. These preliminary data demonstrated a good correlation between positive slope index and clinical ARDS.« less

Computerized scintigraphic technique for the evaluation of adult respiratory distress syndrome: initial clinical trials

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

Tatum, J.L.; Burke, T.S.; Sugerman, H.J.

1982-04-01

Eleven patients with suspected adult respiratory distress syndrome (ARDS) and five control patients were studied using a computerized gamma imaging and analysis technique and 99mTc-labeled human serum albumin. The heart and right lung were imaged, lung:heart ratio was plotted vs. time, and a linear regression was fitted to the data points displayed. The slope of this fit was termed the ''slope index.'' An index value of 2 standard deviations greater than the control mean was considered positive. Radiographs from the six positive studies revealed typical diffuse air-space disease. Radiographs from two of the five negative studies demonstrated air-space consolidation. Bothmore » of these patients had elevated pulmonary capillary wedge pressure, cardiomegaly, and clinical course consistent with cardiogenic pulmonary edema. These preliminary data demonstrated a good correlation between positive slope index and clinical ARDS.« less

On the energy density of helical proteins.

PubMed

Barros, Manuel; Ferrández, Angel

2014-12-01

We solve the problem of determining the energy actions whose moduli space of extremals contains the class of Lancret helices with a prescribed slope. We first see that the energy density should be linear both in the total bending and in the total twisting, such that the ratio between the weights of them is the prescribed slope. This will give an affirmative answer to the conjecture stated in Barros and Ferrández (J Math Phys 50:103529, 2009). Then, we normalize to get the best choice for the helical energy. It allows us to show that the energy, for instance of a protein chain, does not depend on the slope and is invariant under homotopic changes of the cross section which determines the cylinder where the helix is lying. In particular, the energy of a helix is not arbitrary, but it is given as natural multiples of some basic quantity of energy.

Comparing methods to estimate Reineke’s maximum size-density relationship species boundary line slope

Treesearch

Curtis L. VanderSchaaf; Harold E. Burkhart

2010-01-01

Maximum size-density relationships (MSDR) provide natural resource managers useful information about the relationship between tree density and average tree size. Obtaining a valid estimate of how maximum tree density changes as average tree size changes is necessary to accurately describe these relationships. This paper examines three methods to estimate the slope of...

A new method based on the Butler-Volmer formalism to evaluate voltammetric cation and anion sensors.

PubMed

Cano, Manuel; Rodríguez-Amaro, Rafael; Fernández Romero, Antonio J

2008-12-11

A new method based on the Butler-Volmer formalism is applied to assess the capability of two voltammetric ion sensors based on polypyrrole films: PPy/DBS and PPy/ClO4 modified electrodes were studied as voltammetric cation and anion sensors, respectively. The reversible potential versus electrolyte concentrations semilogarithm plots provided positive calibration slopes for PPy/DBS and negative ones for PPy/ClO4, as was expected from the proposed method and that based on the Nernst equation. The slope expressions deduced from Butler-Volmer include the electron-transfer coefficient, which allows slope values different from the ideal Nernstian value to be explained. Both polymeric films exhibited a degree of ion-selectivity when they were immersed in mixed-analyte solutions. Selectivity coefficients for the two proposed voltammetric cation and anion sensors were obtained by several experimental methods, including the separated solution method (SSM) and matched potential method (MPM). The K values acquired by the different methods were very close for both polymeric sensors.

Modeling Fluvial Incision and Transient Landscape Evolution: Influence of Dynamic Channel Adjustment

NASA Astrophysics Data System (ADS)

Attal, M.; Tucker, G. E.; Cowie, P. A.; Whittaker, A. C.; Roberts, G. P.

2007-12-01

Channel geometry exerts a fundamental control on fluvial processes. Recent work has shown that bedrock channel width (W) depends on a number of parameters, including channel slope, and is not only a function of drainage area (A) as is commonly assumed. The present work represents the first attempt to investigate the consequences, for landscape evolution, of using a static expression of channel width (W ~ A0.5) versus a relationship that allows channels to dynamically adjust to changes in slope. We consider different models for the evolution of the channel geometry, including constant width-to-depth ratio (after Finnegan et al., Geology, v. 33, no. 3, 2005), and width-to-depth ratio varying as a function of slope (after Whittaker et al., Geology, v. 35, no. 2, 2007). We use the Channel-Hillslope Integrated Landscape Development (CHILD) model to analyze the response of a catchment to a given tectonic disturbance. The topography of a catchment in the footwall of an active normal fault in the Apennines (Italy) is used as a template for the study. We show that, for this catchment, the transient response can be fairly well reproduced using a simple detachment-limited fluvial incision law. We also show that, depending on the relationship used to express channel width, initial steady-state topographies differ, as do transient channel width, slope, and the response time of the fluvial system. These differences lead to contrasting landscape morphologies when integrated at the scale of a whole catchment. Our results emphasize the importance of channel width in controlling fluvial processes and landscape evolution. They stress the need for using a dynamic hydraulic scaling law when modeling landscape evolution, particularly when the uplift field is non-uniform.

Trajectories of Childhood Blood Pressure and Adult Left Ventricular Hypertrophy: The Bogalusa Heart Study.

PubMed

Zhang, Tao; Li, Shengxu; Bazzano, Lydia; He, Jiang; Whelton, Paul; Chen, Wei

2018-07-01

This longitudinal study aims to characterize longitudinal blood pressure (BP) trajectories from childhood and examine the impact of level-independent childhood BP trajectories on adult left ventricular hypertrophy (LVH) and remodeling patterns. The longitudinal cohort consisted of 1154 adults (787 whites and 367 blacks) who had repeated measurements of BP 4 to 15 times from childhood (4-19 years) to adulthood (20-51 years) and assessment of echocardiographic LV dimensions in adulthood. Model-estimated levels and linear slopes of BP at childhood age points were calculated in 1-year intervals using the growth curve parameters and their first derivatives, respectively. Linear and nonlinear curve parameters of BP showed significant race and sex differences from age 15 years onwards. Adults with LVH had higher long-term BP levels than adults with normal LVM in race-sex groups. Linear and nonlinear slope parameters of BP differed consistently and significantly between LVH and normal groups. Associations of level-independent linear slopes of systolic BP with adult LVH were significantly inverse (odds ratio=0.75-0.82; P =0.001-0.015) in preadolescent children of 4 to 9 years but significantly positive (odds ratio=1.29-1.46; P =0.001-0.008) in adolescents of 13 to 19 years, adjusting for covariates. These associations were consistent across race-sex groups. Of note, the association of childhood BP linear slopes with concentric LVH was significantly stronger than that with eccentric LVH during the adolescence period of 12 to 19 years. These observations indicate that the impact of BP trajectories on adult LVH and geometric patterns originates in childhood. Adolescence is a crucial period for the development of LVH in later life, which has implications for early prevention. © 2018 American Heart Association, Inc.

The Regional Water Cycle and Water Ice Clouds in the Tharsis - Valles Marineris System

NASA Astrophysics Data System (ADS)

Leung, C. W. S.; Rafkin, S. C.

2017-12-01

The regional atmospheric circulation on Mars is highly influenced by local topographic gradients. Terrain-following air parcels forced along the slopes of the major Tharsis volcanoes and the steep canyon walls of Valles Marineris significantly impact the local water vapor concentration and the associated conditions for cloud formation. Using a non-hydrostatic mesoscale atmospheric model with aerosol & cloud microphysics, we investigate the meteorological conditions for water ice cloud formation in the coupled Tharsis - Valles Marineris system near the aphelion season. The usage of a limited area regional model ensures that topographic slopes are well resolved compared to the typical resolutions of a global-coverage general circulation model. The effects of shadowing and slope angle geometries on the energy budget is also taken into account. Diurnal slope winds in complex terrains are typically characterized by the reversal of wind direction twice per sol: upslope during the day, and downslope at night. However, our simulation results of the regional circulation and diurnal water cycle indicate substantial asymmetries in the day-night circulation. The convergence of moist air masses enters Valles Marineris via easterly flows, whereas dry air sweep across the plateau of the canyon system from the south towards the north. We emphasize the non-uniform vertical distribution of water vapor in our model results. Water vapor mixing ratios in the lower planetary boundary layer may be factors greater than the mixing ratio aloft. Water ice clouds are important contributors to the climatic forcing on Mars, and their effects on the mesoscale circulations in the Tharsis - Valles Marineris region significantly contribute to the regional perturbations in the large-scale global atmospheric circulation.

Relation between D/H ratios and 18O /16O ratios in cellulose from linen and maize - Implications for paleoclimatology and for sindonology

NASA Astrophysics Data System (ADS)

DeNiro, Michael J.; Sternberg, Leonel D.; Marino, Bruno D.; Druzik, James R.

1988-09-01

The 18O /16O ratios of cellulose and the D/H ratios of cellulose nitrate were determined for linen, a textile produced from the fibers of the flax plant Linum usitatissimum, and for maize ( Zea mays) from a variety of geographic locations in Europe, the Middle East, and North and South America. The regression lines of δD values on δ 18O values had slopes of 5.4 and 5.8 for the two species. Statistical analysis of results reported in the only other study in which samples of a single species (the silver fir Abies pindrow) that grew under a variety of climatic conditions were analyzed yielded slopes of ~6 when δD values of cellulose nitrate were regressed on δ 18O values of cellulose. The occurrence of this previously unrecognized relationship in three species suggests it may obtain in other plants as well. Determining the basis for this relationship, which is not possible given current understanding of fractionation of the isotopes of oxygen and hydrogen by plants, should lead to increased understanding of how D/H and 18O /16O ratios in cellulose isolated from fossil plants are related to paleoclimates. The separation of most linen samples from Europe from those originating in the Middle East when δD values are plotted against δ 18O values suggests it may be possible to use the isotope ratios of cellulose prepared from the Shroud of Turin to resolve the controversy concerning its geographic origin.

Sub-microradian Surface Slope Metrology with the ALS Developmental Long Trace Profiler

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

Yashchuk, Valeriy V.; Barber, Samuel; Domning, Edward E.

2009-06-15

Development of X-ray optics for 3rd and 4th generation X-ray light sources with a level of surface slope precision of 0.1-0.2 {micro}rad requires the development of adequate fabrication technologies and dedicated metrology instrumentation and methods. Currently, the best performance of surface slope measurement has been achieved with the NOM (Nanometer Optical Component Measuring Machine) slope profiler at BESSY (Germany) [1] and the ESAD (Extended Shear Angle Difference) profiler at the PTB (Germany) [2]. Both instruments are based on electronic autocollimators (AC) precisely calibrated for the specific application [3] with small apertures of 2.5-5 mm in diameter. In the present work,more » we describe the design, initial alignment and calibration procedures, the instrumental control and data acquisition system, as well as the measurement performance of the Developmental Long Trace Profiler (DLTP) slope measuring instrument recently brought into operation at the Advanced Light Source (ALS) Optical Metrology Laboratory (OML). Similar to the NOM and ESAD, the DLTP is based on a precisely calibrated autocollimator. However, this is a reasonably low budget instrument used at the ALS OML for the development and testing of new measuring techniques and methods. Some of the developed methods have been implemented into the ALS LTP-II (slope measuring long trace profiler [4]) which was recently upgraded and has demonstrated a capability for 0.25 {micro}rad surface metrology [5]. Performance of the DLTP was verified via a number of measurements with high quality reference mirrors. A comparison with the corresponding results obtained with the world's best slope measuring instrument, the BESSY NOM, proves the accuracy of the DLTP measurements on the level of 0.1-0.2 {micro}rad depending on the curvature of a surface under test. The directions of future work to develop a surface slope measuring profiler with nano-radian performance are also discussed.« less

Extracting environmental information from lake water isotopes - a novel approac

NASA Astrophysics Data System (ADS)

Kopec, B. G.; Feng, X.; Lauder, A. M.; Virginia, R. A.; Posmentier, E. S.

2014-12-01

It is well known that hydrogen (δD) and oxygen (δ18O) isotopic composition in precipitation defines a meteoric water line with a slope close to 8 and an intercept of 10, and that evaporation causes water to deviate from the line, acquiring a d-excess value different from 10. It has also been observed that a group of lakes subject to significant evaporation often define a line, which we refer to as the lake line, with a slope lower than 8. While there has been much discussion about the slope of lake lines and its dependence on relative humidity, little attention has been given to the scatter around these lines. We show that this seemingly random scatter contains systematic environmental information. Water in over 20 lakes around Kangerlussuaq, Greenland, was collected in the summers of 2009 to 2013, and the δD and δ18O values were determined. Each year's isotopic data were used to find: 1) the slope of the lake line; 2) the displacement of each lake parallel to the lake line, which we refer to as the "enrichment"; and 3) the distance between a given lake and the lake line, which we call the "deviance". The enrichment and deviance are the values of the principal components, PC1 and PC2, respectively, of the set of δD and δ18O coordinates. When comparing the climate and environmental variables, we observed the following. A) The lake line slope varies from 4.12 to 4.63 among the 5 years. B) The enrichment is, in some years, significantly correlated with lake size and longitude (which increases along the moisture and temperature gradient). C) The deviance is significantly correlated with both lake size and longitude every year. A simple water and isotopic mass balance model suggests that the enrichment is largely controlled by the lake to basin area ratio, while the deviance is controlled predominantly by the humidity and isotopic ratios of air above the lake. The latter variables systematically change from east to west (glacial margin to coast), so longitude is a relevant explanatory variable. In addition, it appears the interannual variations of the lake line slope are controlled by the regional water balance, including precipitation, evaporation and humidity. Interestingly, the lake slope correlates quite well with the NAO index, which, according to our previous work, significantly influences the regional hydrological balance.

Large-scale Mass Transport Deposits in the Valencia Basin (Western Mediterranean): slope instability induced by rapid sea-level drawdown?

NASA Astrophysics Data System (ADS)

Cameselle, Alejandra L.; Urgeles, Roger; Llopart, Jaume

2014-05-01

The Messinian Salinity Crisis (MSC) strongly affected the physiography of the Mediterranean margins at the end of the Miocene. The sharp sea-level fall gave a new configuration to the Mediterranean basin and created dramatic morphological and sedimentological changes: margins have been largely eroded whereas the deep basins accumulated thick evaporitic and detrital units. Amongst these detrital units, there are evidences on seismic reflection data for major large-scale slope failure of the Mediterranean continental margins. About 2700 km of seismic reflection profiles in the southwestern part of the Valencia Basin (Western Mediterranean) have enabled us the detailed mapping of distinctive Messinian erosional surfaces, evaporites and deep detrital deposits. The detrital deposits occur in a distinct unit that is made of chaotic, roughly-bedded or transparent seismic bodies, which have been mainly mapped in the basin domain. Locally, the seismic unit shows discontinuous high-amplitude reflections and/or an imbricate internal structure. This unit is interpreted to be formed by a series of Mass Transport Deposits (MTDs). Rapid drawdown has long been recognized as one of the most severe loadings conditions that a slope can be subjected to. Several large historical slope failures have been documented to occur due to rapid drawdown in dams, riverbanks and slopes. During drawdown, the stabilizing effect of the water on the upstream face is lost, but the pore-water pressures within the slope may remain high. The dissipation of these pore pressures in the slope is controlled by the permeability and the storage characteristics of the slope sediments. We hypothesize that the MTDs observed in our data formed under similar conditions and represent a large-scale equivalent of this phenomenon. Therefore, these MTDs can be used to put some constraints on the duration of the drawdown phase of the MSC. We have performed a series of slope stability analysis under rapid Messinian sea-level drawdown using slope geotechnical properties and pre-conditioning factors related to the geological setting of the Valencia Basin. Using several sea-level fall ratios, the variation of the safety factor with respect to successive positions of the sea-level during drawdown has been evaluated.

Acropora interbranch skeleton Sr/Ca ratios: Evaluation of a potential new high-resolution paleothermometer

NASA Astrophysics Data System (ADS)

Sadler, James; Nguyen, Ai D.; Leonard, Nicole D.; Webb, Gregory E.; Nothdurft, Luke D.

2016-04-01

The majority of coral geochemistry-based paleoclimate reconstructions in the Indo-Pacific are conducted on selectively cored colonies of massive Porites. This restriction to a single genus may make it difficult to amass the required paleoclimate data for studies that require deep reef coring techniques. Acropora, however, is a highly abundant coral genus in both modern and fossil reef systems and displays potential as a novel climate archive. Here we present a calibration study for Sr/Ca ratios recovered from interbranch skeleton in corymbose Acropora colonies from Heron Reef, southern Great Barrier Reef. Significant intercolony differences in absolute Sr/Ca ratios were normalized by producing anomaly plots of both coral geochemistry and instrumental water temperature records. Weighted linear regression of these anomalies from the lagoon and fore-reef slope provide a sensitivity of -0.05 mmol/mol °C-1, with a correlation coefficient (r2 = 0.65) comparable to those of genera currently used in paleoclimate reconstructions. Reconstructions of lagoon and reef slope mean seasonality in water temperature accurately identify the greater seasonal amplitude observed in the lagoon of Heron Reef. A longer calibration period is, however, required for reliable reconstructions of annual mean water temperatures.

Slope monitoring by using 2-D resistivity method at Sungai Batu, Pulau Pinang, Malaysia

NASA Astrophysics Data System (ADS)

Azman, Muhamad Iqbal Mubarak Faharul; Yusof, Azim Hilmy Mohd; Ismail, Nur Azwin; Ismail, Noer El Hidayah

2017-07-01

Slope is a dynamic system of geo-environmental phenomena that related to the movement of the soil and rock masses. In Pulau Pinang, the occurrence of slope related phenomena such as landslide and rock fall has become a huge issue especially during rainy season as the government would have to invest more for the people safety. 2-D resistivity method is one of the geophysical methods that can be applied to overcome this issue thus prepare countermeasure actions. Monitoring is one of the common acquisition technique that has been used in solving such issue. This technique was applied to identify and monitor changes at the suspected area and thus, countermeasure steps can be taken accordingly and not blindfolded. Starting from August until November 2016, a 200 m survey line of 2-D resistivity survey had been conducted monthly at Sungai Batu, Pulau Pinang slope for monitoring purpose. Three resistivity ranges were able to detect within the subsurface. Resistivity value of 250 - 400 Ωm indicated the low resistivity value and interpreted as the weak zone located at distance of 90 - 120 m with depth of 10 m. Intermediate resistivity value was interpreted as weathered granite zone with resistivity value of 400 - 1500 Ωm was found at almost along survey line. High resistivity value was > 5000 Ωm and interpreted as granitic bedrock located at depth of > 20 m. Aside from weathered granite zone and weak zone, a fracture was found develop over time at distance of 130 - 140 m. The features found have the potential to be the cause for slope failure phenomena to occur. As a conclusion, monitoring slope using 2-D resistivity method is a success and indeed helpful in overcome landslide and rock fall issue as a pre-countermeasure action.

An in situ method to quantitatively determine dissolved free drug concentrations in vitro in the presence of polymer excipients using pulsatile microdialysis (PMD).

PubMed

Vejani, Charchil; Bellantone, Robert A

2015-12-30

In drug formulations containing polymer excipients, the effects of the polymer on the dissolved free drug concentration and resulting dissolution or release can be important, especially for poorly soluble drugs. In this study, an in vitro method based on pulsatile microdialysis (PMD) was developed to quantitatively determine dissolved free concentrations of drugs in the presence of polymers in aqueous media in situ (e.g., in place within the system being characterized). Formulations were made by dissolving various ratios of the drug griseofulvin and polymer PVP K30 in water and allowing the mix to equilibrate. A PMD probe was immersed in each mixture and the dissolved free drug concentrations were determined in the PMD samples. The experimental procedure and the equations used for data analysis are presented. To assess the consistency of data, a binding model was fit to the data obtained using PMD by calculating the dissolved free drug fraction fD for each drug-polymer ratio in solution, and obtaining the product of the binding stoichiometry and binding constant (νK per mole of polymer) from the slope of a plot of (1-fD)/fD vs. the molar polymer concentration. For comparison, equilibrium binding experiments were also performed at 23C, and the determined value of νK was similar to the value found using PMD. Experiments were performed at three temperatures, and a plot of ln (νK) vs. 1/T was linear and a binding enthalpy of -110.9±4.4J/mol of monomer was calculated from its slope. It was concluded that PMD can be used to determine the dissolved free drug concentrations in situ, which allows characterization of the drug-polymer interaction, even for low drug concentrations. This information may be important in modeling the dissolution or release of drugs from formulations containing polymers. Copyright © 2015 Elsevier B.V. All rights reserved.

UPmag: MATLAB software for viewing and processing u channel or other pass-through paleomagnetic data

NASA Astrophysics Data System (ADS)

Xuan, Chuang; Channell, James E. T.

2009-10-01

With the development of pass-through cryogenic magnetometers and the u channel sampling method, large volumes of paleomagnetic data can be accumulated within a short time period. It is often critical to visualize and process these data in "real time" as measurements proceed, so that the measurement plan can be dictated accordingly. We introduce new MATLAB™ software (UPmag) that is designed for easy and rapid analysis of natural remanent magnetization (NRM) and laboratory-induced remanent magnetization data for u channel samples or core sections. UPmag comprises three MATLAB™ graphic user interfaces: UVIEW, UDIR, and UINT. UVIEW allows users to open and check through measurement data from the magnetometer as well as to correct detected flux jumps in the data, and to export files for further treatment. UDIR reads the *.dir file generated by UVIEW, automatically calculates component directions using selectable demagnetization range(s) with anchored or free origin, and displays vector component plots and stepwise intensity plots for any position along the u channel sample. UDIR can also display data on equal area stereographic projections and draw virtual geomagnetic poles on various map projections. UINT provides a convenient platform to evaluate relative paleointensity (RPI) estimates using the *.int files that can be exported from UVIEW. Two methods are used for RPI estimation: the calculated slopes of the best fit line between the NRM and the respective normalizer (using paired demagnetization data for both parameters) and the averages of the NRM/normalizer ratios. Linear correlation coefficients (of slopes) and standard deviations (of ratios) can be calculated simultaneously to monitor the quality of the RPI estimates. All resulting data and plots from UPmag can be exported into various file formats. UPmag software, data format files, and test data can be downloaded from http://earthref.org/cgi-bin/er.cgi?s=erda.cgi?n=985.

Negative correlation between altitudes and oxygen isotope ratios of seeds: exploring its applicability to assess vertical seed dispersal.

PubMed

Naoe, Shoji; Tayasu, Ichiro; Masaki, Takashi; Koike, Shinsuke

2016-10-01

Vertical seed dispersal, which plays a key role in plant escape and/or expansion under climate change, was recently evaluated for the first time using negative correlation between altitudes and oxygen isotope ratio of seeds. Although this method is innovative, its applicability to other plants is unknown. To explore the applicability of the method, we regressed altitudes on δ 18 O of seeds of five woody species constituting three families in temperate forests in central Japan. Because climatic factors, including temperature and precipitation that influence δ 18 O of plant materials, demonstrate intensive seasonal fluctuation in the temperate zone, we also evaluated the effect of fruiting season of each species on δ 18 O of seeds using generalized linear mixed models (GLMM). Negative correlation between altitudes and δ 18 O of seeds was found in four of five species tested. The slope of regression lines tended to be lower in late-fruiting species. The GLMM analysis revealed that altitudes and date of fruiting peak negatively affected δ 18 O of seeds. These results indicate that the estimation of vertical seed dispersal using δ 18 O of seeds can be applicable for various species, not just confined to specific taxa, by identifying the altitudes of plants that produced seeds. The results also suggest that the regression line between altitudes and δ 18 O of seeds is rather species specific and that vertical seed dispersal in late-fruiting species is estimated at a low resolution due to their small regression slopes. A future study on the identification of environmental factors and plant traits that cause a difference in δ 18 O of seeds, combined with an improvement of analysis, will lead to effective evaluation of vertical seed dispersal in various species and thereby promote our understanding about the mechanism and ecological functions of vertical seed dispersal.

Two models for evaluating landslide hazards

USGS Publications Warehouse

Davis, J.C.; Chung, C.-J.; Ohlmacher, G.C.

2006-01-01

Two alternative procedures for estimating landslide hazards were evaluated using data on topographic digital elevation models (DEMs) and bedrock lithologies in an area adjacent to the Missouri River in Atchison County, Kansas, USA. The two procedures are based on the likelihood ratio model but utilize different assumptions. The empirical likelihood ratio model is based on non-parametric empirical univariate frequency distribution functions under an assumption of conditional independence while the multivariate logistic discriminant model assumes that likelihood ratios can be expressed in terms of logistic functions. The relative hazards of occurrence of landslides were estimated by an empirical likelihood ratio model and by multivariate logistic discriminant analysis. Predictor variables consisted of grids containing topographic elevations, slope angles, and slope aspects calculated from a 30-m DEM. An integer grid of coded bedrock lithologies taken from digitized geologic maps was also used as a predictor variable. Both statistical models yield relative estimates in the form of the proportion of total map area predicted to already contain or to be the site of future landslides. The stabilities of estimates were checked by cross-validation of results from random subsamples, using each of the two procedures. Cell-by-cell comparisons of hazard maps made by the two models show that the two sets of estimates are virtually identical. This suggests that the empirical likelihood ratio and the logistic discriminant analysis models are robust with respect to the conditional independent assumption and the logistic function assumption, respectively, and that either model can be used successfully to evaluate landslide hazards. ?? 2006.

The morphology of transverse aeolian ridges on Mars

NASA Astrophysics Data System (ADS)

Geissler, Paul E.; Wilgus, Justin T.

2017-06-01

A preliminary survey of publicly released high resolution digital terrain models (DTMs) produced by the High Resolution Imaging Science Experiment (HiRISE) camera on Mars Reconnaissance Orbiter identified transverse aeolian ridges (TARs) in 154 DTMs in latitudes from 50°S to 40°N. Consistent with previous surveys, the TARs identified in HiRISE DTMs are found at all elevations, irrespective of the regional thermal inertia of the surface. Ten DTMs were selected for measuring the characteristics of the TARs, including maximum height, mean height, mean spacing (wavelength), and the slope of the surface where they are located. We confined our measurements to features that were taller than 1 m and spaced more than 10 m apart. We found a surprisingly wide variability of TAR sizes within each local region (typically 5 km by 25 km), with up to a factor of 7 difference in TAR wavelengths in a single DTM. The TAR wavelengths do not appear to be correlated to latitude or elevation, but the largest TARs in our small survey were found at lower elevations. The tallest TARs we measured were on the flat floor of Moni crater, within Kaiser crater in the southern highlands. These TARs are up to 14 m tall, with a typical wavelength of 120 m. TAR heights are weakly correlated with their wavelengths. The height-to-wavelength ratios for most TARs are far less than 1/2π (the maximum predicted for antidunes), however in two cases the ratio is close to 1/2π, and in one case (in the bend of a channel) the ratio exceeds 1/2π. TAR wavelengths are uncorrelated with surface slope, both on local and regional scales. TAR heights are weakly anti-correlated with local slope. These results help constrain models of TAR formation, particularly a new hypothesis (Geissler, 2014) that suggests that TARs were formed from micron-sized dust that was transported in suspension. The lack of correlation between TAR wavelength and surface slope seems to rule out formation by gravity-driven dust flows such as avalanches or density currents, and suggests that the TARs were instead produced by the Martian winds.

Flock sizes and sex ratios of canvasbacks in Chesapeake Bay and North Carolina

USGS Publications Warehouse

Haramis, G.M.; Derleth, E.L.; Link, W.A.

1994-01-01

Knowledge of the distribution, size, and sex ratios of flocks of wintering canvasbacks (Aythya valisineria) is fundamental to understanding the species' winter ecology and providing guidelines for management. Consequently, in winter 1986-87, we conducted 4 monthly aerial photographic surveys to investigate temporal changes in distribution, size, and sex ratios of canvasback flocks in traditional wintering areas of Chesapeake Bay and coastal North Carolina. Surveys yielded 35mm imagery of 194,664 canvasbacks in 842 flocks. Models revealed monthly patterns of flock size in North Carolina and Virginia, but no pattern of change in Maryland. A stepwise analysis of flock size and sex ratio fit a common positive slope (increasing proportion male) for all state-month datasets, except for North Carolina in February where the slope was larger (P lt 0.001). State and month effects on intercepts were significant (P lt 0.001) and confirmed a previously identified latitudinal gradient in sex ratio in the survey region. There was no relationship between flock purity (% canvasbacks vs. other species) and flock size except in North Carolina in January, February, and March when flock purity was related to flock size. Contrasting characteristics in North Carolina with regard to flock size (larger flocks) and flock purity suggested that proximate factors were reinforcing flocking behavior and possibly species fidelity there. Of possible factors, the need to locate foraging sites within this large, open-water environment was hypothesized to be of primary importance. Comparison of January 1981 and 1987 sex ratios indicated no change in Maryland, but lower (P lt 0.05) canvasback sex ratios (proportion male) in Virginia and North Carolina.

Flow in a planar convergent-divergent nozzle

NASA Astrophysics Data System (ADS)

Kotteda, V. M. K.; Mittal, S.

2017-05-01

Flow in a convergent-divergent nozzle is studied for pressure ratios (NPR) of 1-11 and exit-to-throat area ratios of 1.2 to 2.0. The unsteady compressible Navier-Stokes equations along with the Spalart-Allmaras turbulence model are solved using a stabilized finite element method in two dimensions. Asymmetric flow is observed at moderate NPR. The side loads due to the flow asymmetry increase with increases in NPR and area ratio. Various flow regimes that are possible in the entire parameter space are identified. The introduction of boundary layer bleed results in steady and symmetric flow conditions at all NPR. Consequently, the nozzle does not experience a lateral force for any NPR. Application of bleed leads to a significant downstream shift in the shock location at low to moderate NPR. Compared to no-bleed, the nozzle experiences a loss of thrust in this regime. The thrust performance for {NPR} > 6 is, however, unaffected by bleed. The effect of nozzle geometry on the flow at various NPR is studied. Four different geometries with the same area ratio and nozzle length are considered. These geometries differ from each other in terms of the nozzle surface profile, including the discontinuity in slope of the surface. Barring some minor differences at low to moderate NPR, the flow is similar for all the geometries considered.

Acoustic and Perceptual Effects of Left–Right Laryngeal Asymmetries Based on Computational Modeling

PubMed Central

Samlan, Robin A.; Story, Brad H.; Lotto, Andrew J.; Bunton, Kate

2015-01-01

Purpose Computational modeling was used to examine the consequences of 5 different laryngeal asymmetries on acoustic and perceptual measures of vocal function. Method A kinematic vocal fold model was used to impose 5 laryngeal asymmetries: adduction, edge bulging, nodal point ratio, amplitude of vibration, and starting phase. Thirty /a/ and /I/ vowels were generated for each asymmetry and analyzed acoustically using cepstral peak prominence (CPP), harmonics-to-noise ratio (HNR), and 3 measures of spectral slope (H1*-H2*, B0-B1, and B0-B2). Twenty listeners rated voice quality for a subset of the productions. Results Increasingly asymmetric adduction, bulging, and nodal point ratio explained significant variance in perceptual rating (R2 = .05, p < .001). The same factors resulted in generally decreasing CPP, HNR, and B0-B2 and in increasing B0-B1. Of the acoustic measures, only CPP explained significant variance in perceived quality (R2 = .14, p < .001). Increasingly asymmetric amplitude of vibration or starting phase minimally altered vocal function or voice quality. Conclusion Asymmetries of adduction, bulging, and nodal point ratio drove acoustic measures and perception in the current study, whereas asymmetric amplitude of vibration and starting phase demonstrated minimal influence on the acoustic signal or voice quality. PMID:24845730

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.

An Upscaling Method for Cover-Management Factor and Its Application in the Loess Plateau of China

PubMed Central

Zhao, Wenwu; Fu, Bojie; Qiu, Yang

2013-01-01

The cover-management factor (C-factor) is important for studying soil erosion. In addition, it is important to use sampling plot data to estimate the regional C-factor when assessing erosion and soil conservation. Here, the loess hill and gully region in Ansai County, China, was studied to determine a method for computing the C-factor. This C-factor is used in the Universal Soil Loss Equation (USLE) at a regional scale. After upscaling the slope-scale computational equation, the C-factor for Ansai County was calculated by using the soil loss ratio, precipitation and land use/cover type. The multi-year mean C-factor for Ansai County was 0.36. The C-factor values were greater in the eastern region of the county than in the western region. In addition, the lowest C-factor values were found in the southern region of the county near its southern border. These spatial differences were consistent with the spatial distribution of the soil loess ratios across areas with different land uses. Additional research is needed to determine the effects of seasonal vegetation growth changes on the C-factor, and the C-factor upscaling uncertainties at a regional scale. PMID:24113551

An upscaling method for cover-management factor and its application in the loess Plateau of China.

PubMed

Zhao, Wenwu; Fu, Bojie; Qiu, Yang

2013-10-09

The cover-management factor (C-factor) is important for studying soil erosion. In addition, it is important to use sampling plot data to estimate the regional C-factor when assessing erosion and soil conservation. Here, the loess hill and gully region in Ansai County, China, was studied to determine a method for computing the C-factor. This C-factor is used in the Universal Soil Loss Equation (USLE) at a regional scale. After upscaling the slope-scale computational equation, the C-factor for Ansai County was calculated by using the soil loss ratio, precipitation and land use/cover type. The multi-year mean C-factor for Ansai County was 0.36. The C-factor values were greater in the eastern region of the county than in the western region. In addition, the lowest C-factor values were found in the southern region of the county near its southern border. These spatial differences were consistent with the spatial distribution of the soil loess ratios across areas with different land uses. Additional research is needed to determine the effects of seasonal vegetation growth changes on the C-factor, and the C-factor upscaling uncertainties at a regional scale.

Intercomparison of infrared cavity leak-out spectroscopy and gas chromatography-flame ionization for trace analysis of ethane.

PubMed

Thelen, Sven; Miekisch, Wolfram; Halmer, Daniel; Schubert, Jochen; Hering, Peter; Mürtz, Manfred

2008-04-15

Comparison of two different methods for the measurement of ethane at the parts-per-billion (ppb) level is reported. We used cavity leak-out spectroscopy (CALOS) in the 3 microm wavelength region and gas chromatography-flame ionization detection (GC-FID) for the analysis of various gas samples containing ethane fractions in synthetic air. Intraday and interday reproducibilities were studied. Intercomparing the results of two series involving seven samples with ethane mixing ratios ranging from 0.5 to 100 ppb, we found a reasonable agreement between both methods. The scatter plot of GC-FID data versus CALOS data yields a linear regression slope of 1.07 +/- 0.03. Furthermore, some of the ethane mixtures were checked over the course of 1 year, which proved the long-term stability of the ethane mixing ratio. We conclude that CALOS shows equivalent ethane analysis precision compared to GC-FID, with the significant advantage of a much higher time resolution (<1 s) since there is no requirement for sample preconcentration. This opens new analytical possibilities, e.g., for real-time monitoring of ethane traces in exhaled human breath.

Validating urinary measurement of beta-2-microglobulin with a Roche reagent kit designed for serum measurements.

PubMed

Chan, Pak Cheung R; Kulasingam, Vathany; Lem-Ragosnig, Bonny

2012-11-01

To validate the use of a Roche serum beta-2-microglobulin (B2MG) kit for urinary B2MG measurements, and to establish reference limits for urinary B2MG/creatinine ratio from healthy individuals. The Roche B2MG Tina-Quant serum kit was used to measure urinary B2MG immunoturbidimetrically. Using human urine as a diluent, the B2MG method was linear from 73-2156 μg/L. The imprecision on a commercially available urine QC was 4.4% at a concentration of 380 μg/L. Limit of quantification at <20% CV was 40 μg/L. Method comparison with Immulite 2000 (Siemens) yielded slope=1.180 (95% CI 1.14-1.22), intercept=11.5 (95% CI -3.6-26.6), SEE=27.6 and r=0.99 (n=26) by the Deming regression analysis. The upper reference limit of B2MG/creatinine ratio determined from 195 healthy adults was 29 μg/mmol (97.5th centile). The serum B2MG Tina Quant reagent kit is acceptable to measure urinary B2MG. Copyright © 2012. Published by Elsevier Inc.

Efficient, nonlinear phase estimation with the nonmodulated pyramid wavefront sensor.

PubMed

Frazin, Richard A

2018-04-01

The sensitivity of the pyramid wavefront sensor (PyWFS) has made it a popular choice for astronomical adaptive optics (AAO) systems. The PyWFS is at its most sensitive when it is used without modulation of the input beam. In nonmodulated mode, the device is highly nonlinear. Hence, all PyWFS implementations on current AAO systems employ modulation to make the device more linear. The upcoming era of 30-m class telescopes and the demand for ultra-precise wavefront control stemming from science objectives that include direct imaging of exoplanets make using the PyWFS without modulation desirable. This article argues that nonlinear estimation based on Newton's method for nonlinear optimization can be useful for mitigating the effects of nonlinearity in the nonmodulated PyWFS. The proposed approach requires all optical modeling to be pre-computed, which has the advantage of avoiding real-time simulations of beam propagation. Further, the required real-time calculations are amenable to massively parallel computation. Numerical experiments simulate a PyWFS with faces sloped 3.7° to the horizontal, operating at a wavelength of 0.85 μm, and with an index of refraction of 1.45. A singular value analysis shows that the common practice of calculating two "slope" images from the four PyWFS pupil images discards critical information and is unsuitable for the nonmodulated PyWFS simulated here. Instead, this article advocates estimators that use the raw pixel values not only from the four geometrical images of the pupil, but from surrounding pixels as well. The simulations indicate that nonlinear estimation can be effective when the Strehl ratio of the input beam is greater than 0.3, and the improvement relative to linear estimation tends to increase at larger Strehl ratios. At Strehl ratios less than about 0.5, the performances of both the nonlinear and linear estimators are relatively insensitive to noise since they are dominated by nonlinearity error.

Distribution of black carbon in Ponderosa pine litter and soils following the High Park wildfire

NASA Astrophysics Data System (ADS)

Boot, C. M.; Haddix, M.; Paustian, K.; Cotrufo, M. F.

2014-12-01

Black carbon (BC), the heterogeneous product of burned biomass, is a critical component in the global carbon cycle, yet timescales and mechanisms for incorporation into the soil profile are not well understood. The High Park Fire, which took place in northwestern Colorado in the summer of 2012, provided an opportunity to study the effects of both fire intenstiy and geomorphology on properties of carbon (C), nitrogen (N), and BC in the Cache La Poudre River drainage. We sampled montane Ponderosa pine litter, 0-5 cm soils, and 5-15 cm soils four months post-fire in order to examine the effects of slope and burn intensity on %C, C stocks, %N and black carbon (g kg-1 C, and g m-2). We developed and implemented the benzene polycarboxylic acid (BPCA) method for quantifying BC. With regard to slope, we found that steeper slopes had higher C : N than shallow slopes, but that there was no difference in black carbon content or stocks. BC content was greatest in the litter in burned sites (19 g kg-1 C), while BC stocks were greatest in the 5-15 cm subsurface soils (23 g m-2). At the time of sampling, none of the BC deposited on the land surface post-fire had been incorporated into to either the 0-5 cm or 5-15 cm soil layers. The ratio of B5CA : B6CA (less condensed to more condensed BC) indicated there was significantly more older, more processed BC at depth. Total BC soil stocks were relatively low compared to other fire-prone grassland and boreal forest systems, indicating most of the BC produced in this system is likely transported off the surface through erosion events. Future work examining mechanisms for BC transport will be required for understanding the role BC plays in the global carbon cycle.

Association of slopes of estimated GFR with post-ESRD mortality in advanced CKD patients transitioning to dialysis

PubMed Central

Sumida, Keiichi; Molnar, Miklos Z.; Potukuchi, Praveen K.; Thomas, Fridtjof; Lu, Jun L.; Jing, Jennie; Ravel, Vanessa A.; Soohoo, Melissa; Rhee, Connie M.; Streja, Elani; Kalantar-Zadeh, Kamyar; Kovesdy, Csaba P.

2016-01-01

Objective To investigate the association of estimated glomerular filtration rate (eGFR) slopes prior to dialysis initiation with cause-specific mortality following dialysis initiation. Patients and Methods In this retrospective cohort study of 18,874 United States veterans who had transitioned to dialysis from October 1, 2007, through September 30, 2011, we examined the association of pre-end-stage renal disease (ESRD) eGFR slopes with all-cause, cardiovascular, and infection-related mortality during the post-ESRD period over a median follow-up of 2.0 years (interquartile range; 1.1–3.2 years). Associations were examined using Cox models with adjustment for potential confounders. Results Prior to transitioning to dialysis, 4,485 (23.8%), 5,633 (29.8%), and 7,942 (42.1%) patients experienced fast, moderate, and slow eGFR decline, respectively, and 814 (4.3%) had increasing eGFR (defined as eGFR slopes of <−10, −10 to <−5, −5 to <0, and ≥0 mL/min/1.73 m2/year). During the study period, a total of 9,744 all-cause, 2,702 cardiovascular, and 604 infection-related deaths were observed. Compared with patients with slow eGFR decline, those with moderate and fast eGFR decline had a higher risk of all-cause (adjusted hazard ratio [HR]: 1.06; 95% confidence interval [CI] 1.00–1.11 and HR: 1.11; 95%CI 1.04–1.18, respectively) and cardiovascular mortality (HR: 1.11; 95%CI 1.01–1.23 and HR: 1.13; 95%CI 1.00–1.27, respectively). In contrast, increasing eGFR was only associated with higher infection-related mortality (HR: 1.49; 95%CI 1.03–2.17). Conclusion Rapid eGFR decline is associated with higher all-cause and cardiovascular mortality, and increasing eGFR is associated with higher infection-related mortality among incident dialysis patients. PMID:26848002

An inversion-based self-calibration for SIMS measurements: Application to H, F, and Cl in apatite

NASA Astrophysics Data System (ADS)

Boyce, J. W.; Eiler, J. M.

2011-12-01

Measurements of volatile abundances in igneous apatites can provide information regarding the abundances and evolution of volatiles in magmas, with applications to terrestrial volcanism and planetary evolution. Secondary ion mass spectrometry (SIMS) measurements can produce accurate and precise measurements of H and other volatiles in many materials including apatite. SIMS standardization generally makes use of empirical linear transfer functions that relate measured ion ratios to independently known concentrations. However, this approach is often limited by the lack of compositionally diverse, well-characterized, homogeneous standards. In general, SIMS calibrations are developed for minor and trace elements, and any two are treated as independent of one another. However, in crystalline materials, additional stoichiometric constraints may apply. In the case of apatite, the sum of concentrations of abundant volatile elements (H, Cl, and F) should closely approach 100% occupancy of their collective structural site. Here we propose and document the efficacy of a method for standardizing SIMS analyses of abundant volatiles in apatites that takes advantage of this stoichiometric constraint. The principle advantage of this method is that it is effectively self-standardizing; i.e., it requires no independently known homogeneous reference standards. We define a system of independent linear equations relating measured ion ratios (H/P, Cl/P, F/P) and unknown calibration slopes. Given sufficient range in the concentrations of the different elements among apatites measured in a single analytical session, solving this system of equations allows for the calibration slope for each element to be determined without standards, using only blank-corrected ion ratios. In the case that a data set of this kind lacks sufficient range in measured compositions of one or more of the relevant ion ratios, one can employ measurements of additional apatites of a variety of compositions to increase the statistical range and make the inversion more accurate and precise. These additional non-standard apatites need only be wide-ranging in composition: They need not be homogenous nor have known H, F, or Cl concentrations. Tests utilizing synthetic data and data generated in the laboratory indicate that this method should yield satisfactory results provided apatites meet the criteria of the model. The inversion method is able to reproduce conventional calibrations to within <2.5%, a level of accuracy comparable to or even better than the uncertainty of the conventional calibration, and one that includes both error in the inversion method as well as any true error in the independently determined values of the standards. Uncertainties in the inversion calibrations range from 0.1-1.7% (2σ), typically an order of magnitude smaller than the uncertainties in conventional calibrations (~4-5% for H2O, 1-19% for F and Cl). However, potential systematic errors stem from the model assumption of 100% occupancy of this site by the measured elements. Use of this method simplifies analysis of H, F, and Cl in apatites by SIMS, and may also be amenable to other stoichiometrically limited substitution groups, including P+As+S+Si+C in apatite, and Zr+Hf+U+Th in non-metamict zircon.

SPECTRAL PROPERTIES OF LARGE GRADUAL SOLAR ENERGETIC PARTICLE EVENTS. I. FE, O, AND SEED MATERIAL

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

Desai, M. I.; Dayeh, M. A.; Ebert, R. W.

We have surveyed ∼0.1–100 MeV nucleon{sup −1} O and Fe fluence spectra during 46 isolated, large gradual SEP events observed at ACE during solar cycles 23 and 24. Most SEP spectra are well represented by the four-parameter Band function with a normalization constant, low-energy spectral slope, high-energy spectral slope, and break energy. The O and Fe spectral slopes are similar and most spectra steepen above the break energy, probably due to common acceleration and transport processes affecting different ion species. SEP spectra above the break energies depend on the origin of the seed population; larger contributions of suprathermal flare materialmore » result in higher Fe/O ratios and flatter spectra at higher energies. SEP events with steeper O spectra at low energies and higher break energies are associated with slower coronal mass ejections (CMEs), while those associated with fast (>2000 km s{sup −1}) CMEs and ground level enhancements have harder or flatter spectra at low and high energies, and O break energies between ∼1 and 10 MeV nucleon{sup −1}. The latter events are enriched in {sup 3}He and higher-energy Fe, and have Fe spectra that rollover at significantly lower energies compared with O, probably because Fe ions with smaller Q/M ratios can escape from the distant shock more easily than O ions with larger Q/M ratios. We conclude that SEP spectral properties result from many complex and competing effects, namely Q/M-dependent scattering, shock properties, and the origin of the seed populations, all of which must be taken into account to develop a comprehensive picture of CME-driven shock acceleration of large gradual SEP events.« less

The universal relation of galactic chemical evolution: the origin of the mass-metallicity relation

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

Zahid, H. Jabran; Dima, Gabriel I.; Kudritzki, Rolf-Peter

2014-08-20

We examine the mass-metallicity relation for z ≲ 1.6. The mass-metallicity relation follows a steep slope with a turnover, or 'knee', at stellar masses around 10{sup 10} M {sub ☉}. At stellar masses higher than the characteristic turnover mass, the mass-metallicity relation flattens as metallicities begin to saturate. We show that the redshift evolution of the mass-metallicity relation depends only on the evolution of the characteristic turnover mass. The relationship between metallicity and the stellar mass normalized to the characteristic turnover mass is independent of redshift. We find that the redshift-independent slope of the mass-metallicity relation is set by themore » slope of the relationship between gas mass and stellar mass. The turnover in the mass-metallicity relation occurs when the gas-phase oxygen abundance is high enough that the amount of oxygen locked up in low-mass stars is an appreciable fraction of the amount of oxygen produced by massive stars. The characteristic turnover mass is the stellar mass, where the stellar-to-gas mass ratio is unity. Numerical modeling suggests that the relationship between metallicity and the stellar-to-gas mass ratio is a redshift-independent, universal relationship followed by all galaxies as they evolve. The mass-metallicity relation originates from this more fundamental universal relationship between metallicity and the stellar-to-gas mass ratio. We test the validity of this universal metallicity relation in local galaxies where stellar mass, metallicity, and gas mass measurements are available. The data are consistent with a universal metallicity relation. We derive an equation for estimating the hydrogen gas mass from measurements of stellar mass and metallicity valid for z ≲ 1.6 and predict the cosmological evolution of galactic gas masses.« less

The Influence of Terrestrial Matter in Marine Food Webs of the Beaufort Sea Shelf and Slope

NASA Astrophysics Data System (ADS)

Bell, L.; Iken, K.; Bluhm, B.

2016-02-01

Forecasted increases in terrestrial organic matter (OMterr) inputs to the Beaufort Sea necessitate a better understanding of the contribution of this organic matter food source to the trophic structure of marine communities. This study investigated the relative ecological importance of OMterr across the Beaufort Sea shelf and slope by examining differences in community trophic structure concurrent with variation in terrestrial versus marine organic matter influence. Interannual variability in organism trophic level was assessed to confirm the persistent impact of these large-scale patterns in food source distribution on marine consumers. Oxygen stable isotope ratios (δ18O) of surface water confirmed the widespread influence of Canada's Mackenzie River plume across the Beaufort Sea. Carbon stable isotope ratios (δ13C values) of pelagic particulate organic matter (pPOM) and marine consumers from locations ranging from 20 to 1000 m bottom depth revealed a strong isotopic imprint of OMterr in the eastern Beaufort Sea, which decreased westward from the Mackenzie River. Food web length, based on the nitrogen stable isotope ratios (δ15N values) of marine consumers, was greater closer to the Mackenzie River outflow both in shelf and slope locations due to relatively higher δ15N values of pelagic and benthic primary consumers. Strong microbial processing of OMterr in the eastern regions of the Beaufort Sea is inferred based on a trophic gap between sources and lower trophic consumers. A large proportion of epifaunal biomass occupying higher trophic levels suggests that OMterr as a basal food source can provide substantial energetic support for higher marine trophic levels. These findings support the concept that terrestrial matter is an important source in the Arctic marine food web, and compel a more specific understanding of energy transfer through the OMterr-associated microbial loop.

Morphometry of terrestrial shield volcanoes

NASA Astrophysics Data System (ADS)

Grosse, Pablo; Kervyn, Matthieu

2018-03-01

Shield volcanoes are described as low-angle edifices built primarily by the accumulation of successive lava flows. This generic view of shield volcano morphology is based on a limited number of monogenetic shields from Iceland and Mexico, and a small set of large oceanic islands (Hawaii, Galápagos). Here, the morphometry of 158 monogenetic and polygenetic shield volcanoes is analyzed quantitatively from 90-meter resolution SRTM DEMs using the MORVOLC algorithm. An additional set of 24 lava-dominated 'shield-like' volcanoes, considered so far as stratovolcanoes, are documented for comparison. Results show that there is a large variation in shield size (volumes from 0.1 to > 1000 km3), profile shape (height/basal width (H/WB) ratios mostly from 0.01 to 0.1), flank slope gradients (average slopes mostly from 1° to 15°), elongation and summit truncation. Although there is no clear-cut morphometric difference between shield volcanoes and stratovolcanoes, an approximate threshold can be drawn at 12° average slope and 0.10 H/WB ratio. Principal component analysis of the obtained database enables to identify four key morphometric descriptors: size, steepness, plan shape and truncation. Hierarchical cluster analysis of these descriptors results in 12 end-member shield types, with intermediate cases defining a continuum of morphologies. The shield types can be linked in terms of growth stages and shape evolution, related to (1) magma composition and rheology, effusion rate and lava/pyroclast ratio, which will condition edifice steepness; (2) spatial distribution of vents, in turn related to the magmatic feeding system and the tectonic framework, which will control edifice plan shape; and (3) caldera formation, which will condition edifice truncation.

Evaluation of Shiryaev-Roberts procedure for on-line environmental radiation monitoring.

PubMed

Watson, Mara M; Seliman, Ayman F; Bliznyuk, Valery N; DeVol, Timothy A

2018-04-30

Water can become contaminated as a result of a leak from a nuclear facility, such as a waste facility, or from clandestine nuclear activity. Low-level on-line radiation monitoring is needed to detect these events in real time. A Bayesian control chart method, Shiryaev-Roberts (SR) procedure, was compared with classical methods, 3-σ and cumulative sum (CUSUM), for quantifying an accumulating signal from an extractive scintillating resin flow-cell detection system. Solutions containing 0.10-5.0 Bq/L of 99 Tc, as T99cO 4 - were pumped through a flow cell packed with extractive scintillating resin used in conjunction with a Beta-RAM Model 5 HPLC detector. While T99cO 4 - accumulated on the resin, time series data were collected. Control chart methods were applied to the data using statistical algorithms developed in MATLAB. SR charts were constructed using Poisson (Poisson SR) and Gaussian (Gaussian SR) probability distributions of count data to estimate the likelihood ratio. Poisson and Gaussian SR charts required less volume of radioactive solution at a fixed concentration to exceed the control limit in most cases than 3-σ and CUSUM control charts, particularly solutions with lower activity. SR is thus the ideal control chart for low-level on-line radiation monitoring. Once the control limit was exceeded, activity concentrations were estimated from the SR control chart using the control chart slope on a semi-logarithmic plot. A linear regression fit was applied to averaged slope data for five activity concentration groupings for Poisson and Gaussian SR control charts. A correlation coefficient (R 2 ) of 0.77 for Poisson SR and 0.90 for Gaussian SR suggest this method will adequately estimate activity concentration for an unknown solution. Copyright © 2018 Elsevier Ltd. All rights reserved.

Atlas-based automatic measurements of the morphology of the tibiofemoral joint.

PubMed

Brehler, M; Thawait, G; Shyr, W; Ramsay, J; Siewerdsen, J H; Zbijewski, W

2017-02-11

Anatomical metrics of the tibiofemoral joint support assessment of joint stability and surgical planning. We propose an automated, atlas-based algorithm to streamline the measurements in 3D images of the joint and reduce user-dependence of the metrics arising from manual identification of the anatomical landmarks. The method is initialized with coarse registrations of a set of atlas images to the fixed input image. The initial registrations are then refined separately for the tibia and femur and the best matching atlas is selected. Finally, the anatomical landmarks of the best matching atlas are transformed onto the input image by deforming a surface model of the atlas to fit the shape of the tibial plateau in the input image (a mesh-to-volume registration). We apply the method to weight-bearing volumetric images of the knee obtained from 23 subjects using an extremity cone-beam CT system. Results of the automated algorithm were compared to an expert radiologist for measurements of Static Alignment (SA), Medial Tibial Slope (MTS) and Lateral Tibial Slope (LTS). Intra-reader variability as high as ~10% for LTS and 7% for MTS (ratio of standard deviation to the mean in repeated measurements) was found for expert radiologist, illustrating the potential benefits of an automated approach in improving the precision of the metrics. The proposed method achieved excellent registration of the atlas mesh to the input volumes. The resulting automated measurements yielded high correlations with expert radiologist, as indicated by correlation coefficients of 0.72 for MTS, 0.8 for LTS, and 0.89 for SA. The automated method for measurement of anatomical metrics of the tibiofemoral joint achieves high correlation with expert radiologist without the need for time consuming and error prone manual selection of landmarks.

Comparing four non-invasive methods to determine the ventilatory anaerobic threshold during cardiopulmonary exercise testing in children with congenital heart or lung disease.

PubMed

Visschers, Naomi C A; Hulzebos, Erik H; van Brussel, Marco; Takken, Tim

2015-11-01

The ventilatory anaerobic threshold (VAT) is an important method to assess the aerobic fitness in patients with cardiopulmonary disease. Several methods exist to determine the VAT; however, there is no consensus which of these methods is the most accurate. To compare four different non-invasive methods for the determination of the VAT via respiratory gas exchange analysis during a cardiopulmonary exercise test (CPET). A secondary objective is to determine the interobserver reliability of the VAT. CPET data of 30 children diagnosed with either cystic fibrosis (CF; N = 15) or with a surgically corrected dextro-transposition of the great arteries (asoTGA; N = 15) were included. No significant differences were found between conditions or among testers. The RER = 1 method differed the most compared to the other methods, showing significant higher results in all six variables. The PET-O2 method differed significantly on five of six and four of six exercise variables with the V-slope method and the VentEq method, respectively. The V-slope and the VentEq method differed significantly on one of six exercise variables. Ten of thirteen ICCs that were >0.80 had a 95% CI > 0.70. The RER = 1 method and the V-slope method had the highest number of significant ICCs and 95% CIs. The V-slope method, the ventilatory equivalent method and the PET-O2 method are comparable and reliable methods to determine the VAT during CPET in children with CF or asoTGA. © 2014 Scandinavian Society of Clinical Physiology and Nuclear Medicine. Published by John Wiley & Sons Ltd.

Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope.

PubMed

Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie

2017-03-15

By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes.

Application of FBG Sensing Technology in Stability Analysis of Geogrid-Reinforced Slope

PubMed Central

Sun, Yijie; Xu, Hongzhong; Gu, Peng; Hu, Wenjie

2017-01-01

By installing FBG sensors on the geogrids, smart geogrids can both reinforce and monitor the stability for geogrid-reinforced slopes. In this paper, a geogrid-reinforced sand slope model test is conducted in the laboratory and fiber Bragg grating (FBG) sensing technology is used to measure the strain distribution of the geogrid. Based on the model test, the performance of the reinforced soil slope is simulated by finite element software Midas-GTS, and the stability of the reinforced soil slope is analyzed by strength reduction method. The relationship between the geogrid strain and the factor of safety is set up. The results indicate that the measured strain and calculated results agree very well. The geogrid strain measured by FBG sensor can be applied to evaluate the stability of geogrid-reinforced sand slopes. PMID:28294995

Attentional Bias to Negative Affect Moderates Negative Affect’s Relationship with Smoking Abstinence

PubMed Central

Etcheverry, Paul E.; Waters, Andrew J.; Lam, Cho; Correa-Fernandez, Virmarie; Vidrine, Jennifer Irvin; Cinciripini, Paul M.; Wetter, David W.

2016-01-01

Objective To examine whether initial orienting (IO) and inability to disengage attention (ITD) from negative affective stimuli moderate the association of negative affect with smoking abstinence during a quit attempt. Methods Data were from a longitudinal cohort study of smoking cessation (N=424). A negative affect modified Stroop was administered one week before and on quit day to measure IO and ITD. Ecological Momentary Assessments were used to create negative affect intercepts and linear slopes for the week before quitting and on quit day. Quit day and long-term abstinence measures were collected. Results Continuation ratio (CR) logit model analyses found significant interactions of pre-quit negative affect slope with pre-quit ITD [OR = .738(.57, .96), p= .02] and quit day negative affect intercept with quit day ITD [OR = .62(.41, 950), p= .03] predicting abstinence. The interaction of pre-quit negative affect intercept and pre-quit IO predicting quit day abstinence was significant [OR = 1.42(1.06, 1.90), p= .02], as was the interaction of quit day negative affect slope and quit day IO predicting long-term abstinence [OR = 1.45(1.02, 2.08), p= .04]. Conclusions The hypothesis that the association of negative affect with smoking abstinence would be moderated by ITD was generally supported. Among individuals with high ITD, negative affect was inversely related to abstinence, but unrelated to abstinence among individuals with lower levels of ITD. Unexpectedly, among individuals with low IO negative affect was inversely related to abstinence, but unrelated to abstinence among individuals with higher levels of ITD. PMID:27505211

Using the Secondary Electrons (SE) of scanning electron microscope with NIST`s MONSEL-II program to obtain improved linewidth measurements and slope angles of line edges on a MMIC GaAs device

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

Sartore, R.G.

1996-12-31

In the evaluation of GaAs devices from the MMIC (Monolithic Microwave Integrated Circuits) program for Army applications, there was a requirement to obtain accurate linewidth measurements on the nominal 0.5 micrometer gate lengths used to fabricate these devices. Preliminary measurements indicated a significant variation (typically 10% to 30% but could be more) in the critical dimensional measurements of the gate length, gate to source distance and gate to drain distance. Passivation introduced a margin of error, which was removed by plasma etching. Additionally, the high aspect ratio (4-5) of the thick gold (Au) conductors also introduced measurement difficulties. The finalmore » measurements were performed were performed after the thick gold conductor was removed and only the barrier metal remained, which was approximately 250 nanometer thick platinum on GaAs substrate. The thickness was measured using the penetration voltage method. Linescan of the secondary electron signal as it scans across the gate is shown in Figure 1. This linescan is an average of 5 linescans in the immediate vicinity to reduce noise levels. A SEM image of the area is shown in Figure 2. To obtain a rough estimate of the slopes of the gate lines at the edges, the sample was tilted to 75 degrees and the image in Figure 3 was obtained. From this figure a rough estimate of the sloped edges, using a protractor, was obtained, approximately 27 degrees, +/-5 degrees.« less

Hydromorphological parameters of natural channel behavior in conditions of the Hercynian System and the flysch belt of the Western Carpathians on the territory of the Czech Republic

NASA Astrophysics Data System (ADS)

Kujanová, Kateřina; Matoušková, Milada; Kliment, Zdeněk

2016-04-01

A fundamental prerequisite for assessing the current ecological status of streams is the establishment of reference conditions for each stream type that serve as a benchmark. The hydromorphological reference conditions reflect the natural channel behavior, which is extremely variable. Significant parameters of natural channel behavior were determined using a combination of four selected statistical methods: Principal Component Analysis, Agglomerative Hierarchical Clustering, correlation, and regression. Macroscale analyses of data about altitude, stream order, channel slope, valley floor slope, sinuosity, and characteristics of the hydrological regime were conducted for 3197 reaches of major rivers in the Czech Republic with total length of 15,636 km. On the basis of selected significant parameters and their threshold values, channels were classified into groups of river characteristics based on shared behaviors. The channel behavior within these groups was validated using hydromorphological characteristics of natural channels determined during field research at reference sites. Classification of channels into groups confirmed the fundamental differences between channel behavior under conditions of the Hercynian System and the flysch belt of the Western Carpathians in the Czech Republic and determined a specific group in the flattened high areas of mountains in the Bohemian Massif. Validating confirmed the distinctions between groups of river characteristics and the uniqueness of each one; it also emphasized the benefits of using qualitative data and riparian zone characteristics for describing channel behavior. Channel slope, entrenchment ratio, bed structure, and d50 were determined as quantitative characteristics of natural channel behavior.

Fatigue properties of JIS H3300 C1220 copper for strain life prediction

NASA Astrophysics Data System (ADS)

Harun, Muhammad Faiz; Mohammad, Roslina

2018-05-01

The existing methods for estimating strain life parameters are dependent on the material's monotonic tensile properties. However, a few of these methods yield quite complicated expressions for calculating fatigue parameters, and are specific to certain groups of materials only. The Universal Slopes method, Modified Universal Slopes method, Uniform Material Law, the Hardness method, and Medians method are a few existing methods for predicting strain-life fatigue based on monotonic tensile material properties and hardness of material. In the present study, nine methods for estimating fatigue life and properties are applied on JIS H3300 C1220 copper to determine the best methods for strain life estimation of this ductile material. Experimental strain-life curves are compared to estimations obtained using each method. Muralidharan-Manson's Modified Universal Slopes method and Bäumel-Seeger's method for unalloyed and low-alloy steels are found to yield batter accuracy in estimating fatigue life with a deviation of less than 25%. However, the prediction of both methods only yield much better accuracy for a cycle of less than 1000 or for strain amplitudes of more than 1% and less than 6%. Manson's Original Universal Slopes method and Ong's Modified Four-Point Correlation method are found to predict the strain-life fatigue of copper with better accuracy for a high number of cycles of strain amplitudes of less than 1%. The differences between mechanical behavior during monotonic and cyclic loading and the complexity in deciding the coefficient in an equation are probably the reason for the lack of a reliable method for estimating fatigue behavior using the monotonic properties of a group of materials. It is therefore suggested that a differential approach and new expressions be developed to estimate the strain-life fatigue parameters for ductile materials such as copper.

"Turn-of-the-Nut" Method Is Not Appropriate for Use in Cancellous Bone.

PubMed

Ryan, Melissa K; Mohtar, Aaron A; Costi, John J; Reynolds, Karen J

2015-11-01

The level to which bone screws are tightened is determined subjectively by the operating surgeon. It is likely that the tactile feedback that surgeons rely on is based on localized tissue yielding, which may predispose the screw-bone interface to failure. A limited number of studies have investigated the ratio between clinical tightening torque and stripping torque. The purpose of this study was to measure, for the first time, the ratio between yield torque (T yield) and stripping torque (T max) during screw insertion into the cancellous bone and to compare these torques with clinical levels of tightening reported in the literature. Additionally, a rotational limit was investigated as a potential end point for screw insertion in cancellous bone. A 6.5-mm outer diameter commercial cancellous bone screw was inserted into human femoral head specimens (n = 89). Screws were inserted to failure, while recording insertion torque, compression under the screw head, and rotation angle. The median, interquartile ranges, and coefficient of variation were calculated for each of the following parameters: T yield, T max, T yield/T max, slope, T plateau, and rotation angle. The median ratio of T yield/T max and rotation angle was 85.45% and 96.5 degrees, respectively. The coefficient of variation was greatest for the rotation angle compared with the ratio of T yield/T max (0.37 vs. 0.12). The detection of yield may be a more precise method than the rotation angle in cancellous bone; however, bone-screw constructs that exhibit a T yield close to T max may be more susceptible to stripping during insertion. Future work can identify factors that influence the ratio of T yield/T max may help to reduce the incidence of screw stripping.

Hepatic Blood Perfusion Estimated by Dynamic Contrast-Enhanced Computed Tomography in Pigs Limitations of the Slope Method

PubMed Central

Winterdahl, Michael; Sørensen, Michael; Keiding, Susanne; Mortensen, Frank V.; Alstrup, Aage K. O.; Hansen, Søren B.; Munk, Ole L.

2012-01-01

Objective To determine whether dynamic contrast-enhanced computed tomography (DCE-CT) and the slope method can provide absolute measures of hepatic blood perfusion from hepatic artery (HA) and portal vein (PV) at experimentally varied blood flow rates. Materials and Methods Ten anesthetized 40-kg pigs underwent DCE-CT during periods of normocapnia (normal flow), hypocapnia (decreased flow), and hypercapnia (increased flow), which was induced by adjusting the ventilation. Reference blood flows in HA and PV were measured continuously by surgically-placed ultrasound transit-time flowmeters. For each capnic condition, the DCE-CT estimated absolute hepatic blood perfusion from HA and PV were calculated using the slope method and compared with flowmeter based absolute measurements of hepatic perfusions and relative errors were analyzed. Results The relative errors (mean±SEM) of the DCE-CT based perfusion estimates were −21±23% for HA and 81±31% for PV (normocapnia), 9±23% for HA and 92±42% for PV (hypocapnia), and 64±28% for HA and −2±20% for PV (hypercapnia). The mean relative errors for HA were not significantly different from zero during hypo- and normocapnia, and the DCE-CT slope method could detect relative changes in HA perfusion between scans. Infusion of contrast agent led to significantly increased hepatic blood perfusion, which biased the PV perfusion estimates. Conclusions Using the DCE-CT slope method, HA perfusion estimates were accurate at low and normal flow rates whereas PV perfusion estimates were inaccurate and imprecise. At high flow rate, both HA perfusion estimates were significantly biased. PMID:22836307

Modeling of microclimatic characteristics of highland area

NASA Astrophysics Data System (ADS)

Sitdikova, Iuliia; Rusin, Igor

2013-04-01

Microclimatic characteristics of highlands may vary considerably over distances of a few meters depending on slope and aspect. There is a problem of estimation of components of surface energy balance based on observation of single stations for description of microclimate highlands. The aim of this paper is to develop a method that would restore microclimatic characteristics of terrain, based on observations of the single station, by physical extrapolation. The input parameters to obtain the microclimatic characteristics are as follows: air temperature, relative humidity, and wind speed on two vertical levels, air pressure, surface temperature, direct and diffused solar radiation and surface albedo. The recent version of the Meteorological Radiation Model (MRM) has been used to calculate a solar radiation over the area and to estimate an influence of cloudiness amounts. The height, slope and aspect were accounted at each point with using a digital elevation model. Have been supposed that air temperature and specific humidity vary with altitude only. Net radiation was calculated at all points of the area. Supposed that the difference between the surface temperature and the air temperature is a linear function of net radiation. The empirical coefficient, which depends on wind speed with adjustment of given area. Latent and sensible fluxes are calculated by using the modified Bowen ratio, which varies on the area. Method was tested on field research in Krasnodar region (RF). The meteorological observations were made every three hour on actinometric and gradient sites. The editional gradient site with different orientation of the slope was organized from 400 meters of the main site. Topographic survey of area was made 1x1,3 km in size for a digital elevation model constructing. At all points of the area of radiation and heat balance were calculated. The results of researches are the maps of surface temperature, net radiation, latent and sensible fluxes. The calculations showed that the average value of components of heat balance by area differ significantly from the data observed on meteorological station.

Stability of submarine slopes in the northern South China Sea: a numerical approach

NASA Astrophysics Data System (ADS)

Zhang, Liang; Luan, Xiwu

2013-01-01

Submarine landslides occur frequently on most continental margins. They are effective mechanisms of sediment transfer but also a geological hazard to seafloor installations. In this paper, submarine slope stability is evaluated using a 2D limit equilibrium method. Considerations of slope, sediment, and triggering force on the factor of safety (FOS) were calculated in drained and undrained ( Φ=0) cases. Results show that submarine slopes are stable when the slope is <16° under static conditions and without a weak interlayer. With a weak interlayer, slopes are stable at <18° in the drained case and at <9° in the undrained case. Earthquake loading can drastically reduce the shear strength of sediment with increased pore water pressure. The slope became unstable at >13° with earthquake peak ground acceleration (PGA) of 0.5 g; whereas with a weak layer, a PGA of 0.2 g could trigger instability at slopes >10°, and >3° for PGA of 0.5 g. The northern slope of the South China Sea is geomorphologically stable under static conditions. However, because of the possibility of high PGA at the eastern margin of the South China Sea, submarine slides are likely on the Taiwan Bank slope and eastern part of the Dongsha slope. Therefore, submarine slides recognized in seismic profiles on the Taiwan Bank slope would be triggered by an earthquake, the most important factor for triggering submarine slides on the northern slope of the South China Sea. Considering the distribution of PGA, we consider the northern slope of the South China Sea to be stable, excluding the Taiwan Bank slope, which is tectonically active.

Estimating Discharge, Depth and Bottom Friction in Sand Bed Rivers Using Surface Currents and Water Surface Elevation Observations

NASA Astrophysics Data System (ADS)

Simeonov, J.; Czapiga, M. J.; Holland, K. T.

2017-12-01

We developed an inversion model for river bathymetry estimation using measurements of surface currents, water surface elevation slope and shoreline position. The inversion scheme is based on explicit velocity-depth and velocity-slope relationships derived from the along-channel momentum balance and mass conservation. The velocity-depth relationship requires the discharge value to quantitatively relate the depth to the measured velocity field. The ratio of the discharge and the bottom friction enter as a coefficient in the velocity-slope relationship and is determined by minimizing the difference between the predicted and the measured streamwise variation of the total head. Completing the inversion requires an estimate of the bulk friction, which in the case of sand bed rivers is a strong function of the size of dune bedforms. We explored the accuracy of existing and new empirical closures that relate the bulk roughness to parameters such as the median grain size diameter, ratio of shear velocity to sediment fall velocity or the Froude number. For given roughness parameterization, the inversion solution is determined iteratively since the hydraulic roughness depends on the unknown depth. We first test the new hydraulic roughness parameterization using estimates of the Manning roughness in sand bed rivers based on field measurements. The coupled inversion and roughness model is then tested using in situ and remote sensing measurements of the Kootenai River east of Bonners Ferry, ID.

Reduction of matrix interferences in furnace atomic absorption with the L'vov Platform

USGS Publications Warehouse

Kaiser, M.L.; Koirtyohann, S.R.; Hinderberger, E.J.; Taylor, Howard E.

1981-01-01

Use of a modified L'vov Platform and ammonium phosphate as a matrix modifier greatly reduced matrix interferences in a commercial Massmann-type atomic absorption furnace. Platforms were readily fabricated from furnace tubes and, once positioned in the furnace, caused no inconvenience in operation. Two volatile elements (Pb, Cd), two of intermediate volatility (Co, Cr) and two which form stable oxides (Al, Sn) were tested in natural water and selected synthetic matrices. In every case for which there was a significant matrix effect during atomization from the tube wall, the platform and platform plus modifier gave improved performance. With lead, for example, an average ratio of 0.48 ?? 0.11 was found when the slope of the standard additions plot for six different natural water samples was compared to the slope of the standard working curve in dilute acid. The average slope ratio between the natural water matrices and the dilute acid matrix was 0.94 ?? 0.03 with the L'vov Platform and 0.96 ?? 0.03 with the platform and matrix modifier. In none of the cases studied did the use of the platform or platform plus modifier cause an interference problem where none existed while atomizing from the tube wall. An additional benefit of the platform was a factor of about two improvement in peak height precision. ?? 1981.

Remote ultrasound detection with a quasi-balanced confocal Fabry-Perot interferometer

NASA Astrophysics Data System (ADS)

Reitinger, B.; Roither, J.; Berer, T.; Hornhuber, C.; Burgholzer, P.

2011-09-01

In this article, we show the benefits of a quasi-balanced fringe hopping confocal Fabry-Perot interferometer (CFPI) with broadband common mode rejection ratio (CMRR) for remote ultrasound detection. In laser ultrasound, the ultrasonic information, in general, lies in the phase modulation of laser light which in this case is demodulated using the CFPI at a certain working point on a fringe. By hopping from the positive to the negative slope on the same fringe, the detected ultrasonic signals are inverted. In contrary, interference signals - such crosstalk from the generation, ghosts or noise correlated to pulse laser excitation - are not influenced and hence get rejected by subtracting the signals measured at both slopes. Hence, a minimum of two measurements is needed for common mode rejection. The fringe hopping from the positive to the negative slope is done by changing the distance of the CFPI mirrors with a precise piezoelectric-stack and a fast high-resolution digital controller. As only one photodetector with a transimpedance amplifier is needed, a high CMRR can be accomplished. The CMRR is not affected by the symmetry of the fringe but only by pulse-to-pulse energy fluctuations of the generation laser. We show that with fringe hopping and averaging the signal-to-noise ratio increases much faster than with averaging without fringe hopping. This is due to the correlation of the quasi-noise with the generation cycle.

Rejection of crosstalk and noise by a quasi balanced CFPI for remote ultrasound detection

NASA Astrophysics Data System (ADS)

Reitinger, B.; Berer, T.; Hornhuber, C.; Burgholzer, P.

2011-01-01

In this paper we show the benefits of a quasi balanced fringe hopping CFPI (confocal Fabry-Pérot interferometer) with broadband CMRR (common mode rejection ratio) for remote ultrasound detection. Ultrasonic information in general lies in the phase modulation of laser light which in this case is demodulated by using the CFPI at a certain working point on a fringe. By hopping from the positive to the negative slope on the same fringe the detected ultrasonic signals are inverted. In contrary interference signals like crosstalk from the generation, ghosts, or noise correlated to pulse laser excitation are not influenced and hence get rejected by subtracting the signals from both slopes. Hence, a minimum of two measurements is needed for common mode rejection. The fringe hopping from the positive to the negative slope is done by changing the distance of the CFPI mirrors with a precise piezoelectric-stack and a fast high resolution digital controller. As only one photo-detector with a transimpedance-amplifier is needed a high CMRR can be accomplished which is not affected by the symmetry of the fringe but only by pulse to pulse energy fluctuations of the generation laser. We show that with fringe hopping and averaging the signal to noise ratio increases much faster than with averaging without fringe hopping. This is due to the correlation of the quasi-noise with the generation cycle.

Spectral characteristics of caries-related autofluorescence spectra and their use for diagnosis of caries stage

NASA Astrophysics Data System (ADS)

Son, Sung-Ae; Jung, Kyeong-Hoon; Ko, Ching-Chang; Kwon, Yong Hoon

2016-01-01

The purpose of the present study was to identify factors useful for diagnosis of the caries stage from laser-induced autofluorescence (AF) spectra. Affected teeth were accurately staged and allocated to four groups: sound, stage II, stage III, or stage IV. A 405-nm laser was used to produce AF spectra. The spectrum factors analyzed were spectrum slope at 550 to 600 nm, spectral area from 500 and 590 nm, and intensity ratio of peaks 625 and 667 nm (625/667 nm). DIAGNOdent was used as control measurement. AF spectra of sound teeth had a peak near 500 nm followed by a smooth decline to 800 nm. As caries progressed, some specimens in stages II to IV showed one or two peak(s) near 625 and 667 nm. Slopes at 550 to 600 nm and areas under the curve at 500 to 590 nm were significantly different (p<0.001) for each stage. Two-peak ratios were also significantly different (p<0.001) except for stage III and stage IV. DIAGNOdent readings for sound and stage II and stage III and IV were not significantly different. Among the studied factors, the spectrum slope at 550 to 600 nm and area under curve at 500 to 590 nm could be useful treatment decision-making tools for carious lesions.

An artificial bee colony algorithm for locating the critical slip surface in slope stability analysis

NASA Astrophysics Data System (ADS)

Kang, Fei; Li, Junjie; Ma, Zhenyue

2013-02-01

Determination of the critical slip surface with the minimum factor of safety of a slope is a difficult constrained global optimization problem. In this article, an artificial bee colony algorithm with a multi-slice adjustment method is proposed for locating the critical slip surfaces of soil slopes, and the Spencer method is employed to calculate the factor of safety. Six benchmark examples are presented to illustrate the reliability and efficiency of the proposed technique, and it is also compared with some well-known or recent algorithms for the problem. The results show that the new algorithm is promising in terms of accuracy and efficiency.

The susceptibility analysis of landslides induced by earthquake in Aso volcanic area, Japan, scoping the prediction

NASA Astrophysics Data System (ADS)

Kubota, Tetsuya; Takeda, Tsuyoshi

2017-04-01

Kumamoto earthquake on April 16th 2016 in Kumamoto prefecture, Kyushu Island, Japan with intense seismic scale of M7.3 (maximum acceleration = 1316 gal in Aso volcanic region) yielded countless instances of landslide and debris flow that induced serious damages and causalities in the area, especially in the Aso volcanic mountain range. Hence, field investigation and numerical slope stability analysis were conducted to delve into the characteristics or the prediction factors of the landslides induced by this earthquake. For the numerical analysis, Finite Element Method (FEM) and CSSDP (Critical Slip Surface analysis by Dynamic Programming theory based on limit equilibrium method) were applied to the landslide slopes with seismic acceleration observed. These numerical analysis methods can automatically detect the landslide slip surface which has minimum Fs (factor of safety). The various results and the information obtained through this investigation and analysis were integrated to predict the landslide susceptible slopes in volcanic area induced by earthquakes and rainfalls of their aftermath, considering geologic-geomorphologic features, geo-technical characteristics of the landslides and vegetation effects on the slope stability. Based on the FEM or CSSDP results, the landslides occurred in this earthquake at the mild gradient slope on the ridge have the safety factor of slope Fs=2.20 approximately (without rainfall nor earthquake, and Fs>=1.0 corresponds to stable slope without landslide) and 1.78 2.10 (with the most severe rainfall in the past) while they have approximately Fs=0.40 with the seismic forces in this earthquake (horizontal direction 818 gal, vertical direction -320 gal respectively, observed in the earthquake). It insists that only in case of earthquakes the landslide in volcanic sediment apt to occur at the mild gradient slopes as well as on the ridges with convex cross section. Consequently, the following results are obtained. 1) At volcanic hillside, mild slopes of 7-10 ° gradient with volcanic sediment such as pumice are prone to collapse to be landslide by strong earthquake. 2) The slopes at the mountain ridge with convex cross section where the seismic vibration tends to concentrate are prone to form landslides in case of earthquake. 3) Due to the most severe precipitation of the past or in the aftermath of earthquake, no landslides occurred in these mild gradient slopes or on the mountain ridges with convex cross section. This information will be a great help in the aspect of landslide prediction.

Infiltration on sloping terrain and its role on runoff generation and slope stability

NASA Astrophysics Data System (ADS)

Loáiciga, Hugo A.; Johnson, J. Michael

2018-06-01

A modified Green-and-Ampt model is formulated to quantify infiltration on sloping terrain underlain by homogeneous soil wetted by surficial water application. This paper's theory for quantifying infiltration relies on the mathematical statement of the coupled partial differential equations (pdes) governing infiltration and runoff. These pdes are solved by employing an explicit finite-difference numerical method that yields the infiltration, the infiltration rate, the depth to the wetting front, the rate of runoff, and the depth of runoff everywhere on the slope during external wetting. Data inputs consist of a water application rate or the rainfall hyetograph of a storm of arbitrary duration, soil hydraulic characteristics and antecedent moisture, and the slope's hydraulic and geometric characteristics. The presented theory predicts the effect an advancing wetting front has on slope stability with respect to translational sliding. This paper's theory also develops the 1D pde governing suspended sediment transport and slope degradation caused by runoff influenced by infiltration. Three examples illustrate the application of the developed theory to calculate infiltration and runoff on a slope and their role on the stability of cohesive and cohesionless soils forming sloping terrain.

Volcano collapse promoted by hydrothermal alteration and edifice shape, Mount Rainier, Washington

USGS Publications Warehouse

Reid, M.E.; Sisson, T.W.; Brien, D.L.

2001-01-01

Catastrophic collapses of steep volcano flanks threaten many populated regions, and understanding factors that promote collapse could save lives and property. Large collapses of hydrothermally altered parts of Mount Rainier have generated far-traveled debris flows; future flows would threaten densely populated parts of the Puget Sound region. We evaluate edifice collapse hazards at Mount Rainier using a new three-dimensional slope stability method incorporating detailed geologic mapping and subsurface geophysical imaging to determine distributions of strong (fresh) and weak (altered) rock. Quantitative three-dimensional slope stability calculations reveal that sizeable flank collapse (>0.1 km3) is promoted by voluminous, weak, hydrothermally altered rock situated high on steep slopes. These conditions exist only on Mount Rainier's upper west slope, consistent with the Holocene debris-flow history. Widespread alteration on lower flanks or concealed in regions of gentle slope high on the edifice does not greatly facilitate collapse. Our quantitative stability assessment method can also provide useful hazard predictions using reconnaissance geologic information and is a potentially rapid and inexpensive new tool for aiding volcano hazard assessments.

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

Xu, W.; Zhu, W. D.; Smith, S. A.

While structural damage detection based on flexural vibration shapes, such as mode shapes and steady-state response shapes under harmonic excitation, has been well developed, little attention is paid to that based on longitudinal vibration shapes that also contain damage information. This study originally formulates a slope vibration shape for damage detection in bars using longitudinal vibration shapes. To enhance noise robustness of the method, a slope vibration shape is transformed to a multiscale slope vibration shape in a multiscale domain using wavelet transform, which has explicit physical implication, high damage sensitivity, and noise robustness. These advantages are demonstrated in numericalmore » cases of damaged bars, and results show that multiscale slope vibration shapes can be used for identifying and locating damage in a noisy environment. A three-dimensional (3D) scanning laser vibrometer is used to measure the longitudinal steady-state response shape of an aluminum bar with damage due to reduced cross-sectional dimensions under harmonic excitation, and results show that the method can successfully identify and locate the damage. Slopes of longitudinal vibration shapes are shown to be suitable for damage detection in bars and have potential for applications in noisy environments.« less

Testing the Success Rate of Establishing Multitrophic Vegetation for Stream Buffer Mitigation According to Georgia DOT Specifications on Different Slope Ratios

DOT National Transportation Integrated Search

2017-02-01

Multitrophic vegetative mitigation is required for stream buffers, wetlands, and retention basins within state waters. Downslopes adjacent to linear road construction are typically steep, which creates challenges for establishment and erosion control...

Regional potential evapotranspiration in arid climates based on temperature, topography and calculated solar radiation

NASA Astrophysics Data System (ADS)

Shevenell, Lisa

1999-03-01

Values of evapotranspiration are required for a variety of water planning activities in arid and semi-arid climates, yet data requirements are often large, and it is costly to obtain this information. This work presents a method where a few, readily available data (temperature, elevation) are required to estimate potential evapotranspiration (PET). A method using measured temperature and the calculated ratio of total to vertical radiation (after the work of Behnke and Maxey, 1969) to estimate monthly PET was applied for the months of April-October and compared with pan evaporation measurements. The test area used in this work was in Nevada, which has 124 weather stations that record sufficient amounts of temperature data. The calculated PET values were found to be well correlated (R2=0·940-0·983, slopes near 1·0) with mean monthly pan evaporation measurements at eight weather stations.In order to extrapolate these calculated PET values to areas without temperature measurements and to sites at differing elevations, the state was divided into five regions based on latitude, and linear regressions of PET versus elevation were calculated for each of these regions. These extrapolated PET values generally compare well with the pan evaporation measurements (R2=0·926-0·988, slopes near 1·0). The estimated values are generally somewhat lower than the pan measurements, in part because the effects of wind are not explicitly considered in the calculations, and near-freezing temperatures result in a calculated PET of zero at higher elevations in the spring months. The calculated PET values for April-October are 84-100% of the measured pan evaporation values. Using digital elevation models in a geographical information system, calculated values were adjusted for slope and aspect, and the data were used to construct a series of maps of monthly PET. The resultant maps show a realistic distribution of regional variations in PET throughout Nevada which inversely mimics topography. The general methods described here could be used to estimate regional PET in other arid western states (e.g. New Mexico, Arizona, Utah) and arid regions world-wide (e.g. parts of Africa).

The preparation of new perfluoro ether fluids exhibiting excellent thermal-oxidative stabilities

NASA Technical Reports Server (NTRS)

Jones, William R., Jr.; Bierschenk, Thomas R.; Juhlke, Timothy J.; Kawa, Hajima; Lagow, Richard J.

1988-01-01

A series of low molecular weight perfluoroalkyl ethers (PFAEs) were synthesized by direct fluorination. Viscosity-temperature properties and oxidation stabilities were determined. Viscosity-temperature correlations indicated that increases in branching and increases in the size of the branching substituent caused a deterioration in viscometric properties (i.e., an increase in ASTM slope). In addition, increasing the ratio of carbon to oxygen in these compounds also increased the ASTM slope. Preliminary oxidation stability measurements indicated that highly branched PFAE fluids (i.e., those containing quaternary carbons) may be less stable than either those containing a single trifluoromethyl pendant group or those containing no branching at all.

The preparation of new perfluoroether fluids exhibiting excellent thermal-oxidative stabilities

NASA Technical Reports Server (NTRS)

Jones, W. R., Jr.; Bierschenk, T. R.; Juhlke, T. J.; Kawa, H.; Lagow, R. J.

1986-01-01

A series of low molecular weight perfluoroalkylethers (PFAE) were synthesized by direct fluorination. Viscosity-temperature properties and oxidation stabilities were determined. Viscosity-temperature correlations indicated that increases in branching and increases in the size of the branching substituent caused a deterioration in viscometric properties (i.e., an increase in ASTM slope). In addition, increasing the ratio of carbon to oxygen in these compounds also increased the ASTM slope. Preliminary oxidation stability tests indicated that highly branched PFAE fluids. (i.e., those containing quaternary carbons) may be less stable than either those containing a single trifluoromethyl pendant group or those containing no branching at all.

Spectroscopic thermoacoustic imaging of water and fat composition

NASA Astrophysics Data System (ADS)

Bauer, Daniel R.; Wang, Xiong; Vollin, Jeff; Xin, Hao; Witte, Russell S.

2012-07-01

During clinical studies, thermoacoustic imaging (TAI) failed to reliably identify malignant breast tissue. To increase detection capability, we propose spectroscopic TAI to differentiate samples based on the slope of their dielectric absorption. Phantoms composed of different ratios of water and fat were imaged using excitation frequencies between 2.7 and 3.1 GHz. The frequency-dependent slope of the TA signal was highly correlated with that of its absorption coefficient (R2 = 0.98 and p < 0.01), indicating spectroscopic TAI can distinguish materials based on their intrinsic dielectric properties. This approach potentially enhances cancer detection due to the increased water content of many tumors.

Monitoring changes in the structure and properties of humic substances following ozonation using UV-Vis, FTIR and (1)H NMR techniques.

PubMed

Rodríguez, Francisco J; Schlenger, Patrick; García-Valverde, María

2016-01-15

The main objective of this work is to conduct a comprehensive structural characterization of humic substances using the following experimental techniques: FTIR, 1H NMR and several UV–Vis parameters (Specific UV Absorbance at 254 nm or SUVA254, SUVA280, A400, the absorbance ratios A210/254, A250/365, A254/203, A254/436, A265/465, A270/400, A280/350, A465/665, the Absorbance Slope Index (ASI), the spectral slopes S275–295, S350–400 and the slope ratio SR). These UV–Vis parameters have also been correlated with key properties of humic substances such as aromaticity, molecular weight (MW) and trihalomethane formation potential (THMFP). An additional objective of this work is also to evaluate the usefulness of these techniques to monitor structural changes in humic substances produced by the ozonation treatment. Four humic substances were studied in this work: three of them were provided by the International Humic Substances Society (Suwannee River Fulvic Acid Standard: SRFA, Suwannee River Humic Acid Standard: SRHA and Nordic Reservoir Fulvic Acid Reference: NLFA) and the other one was a terrestrial humic acid widely used as a surrogate for aquatic humic substances in various studies (Aldrich Humic Acid: AHA). The UV–Vis parameters showing the best correlations with aromaticity in this study were SUVA254, SUVA280, A280/A350 ratio and A250/A364 ratio. The best correlations with molecular weight were for SUVA254, SUVA280 and A280/A350 ratio. Finally, in the case of the THMFP it was STHMFP-per mol HS the parameter showing good correlations with most of the UV–Vis parameters studied (especially with A280/A350 ratio, A265/A465 ratio and A270/A400 ratio) whereas STHMFP-per mg C showed poor correlations in most cases. On the whole, the UV–Vis parameter showing the best results was A280/A350 ratio as it showed excellent correlations for the three properties studied (aromaticity, MW and THMFP). A decrease in aromaticity following ozonation of humic substances can be readily monitored by 1H NMR and FTIR; the latter technique also allows to monitor an increase in carboxylic acidity with ozone dosage. This organic matter originated following ozonation (more aliphatic in character and more polar) is expected to be recalcitrant to further oxidation. The terrestrial humic acid (AHA) showed some structural differences with the aquatic humic substances and its behavior upon ozonation also differed in some extent from that shown by them.

A qualitative comparison of fire spread models incorporating wind and slope effects

Treesearch

David R. Weise; Gregory S. Biging

1997-01-01

Wind velocity and slope are two critical variables that affect wildland fire rate of spread. The effects of these variables on rate of spread are often combined in rate-of-spread models using vector addition. The various methods used to combine wind and slope effects have seldom been validated or compared due to differences in the models or to lack of data. In this...

Application of Soil Nailing Technique for Protection and Preservation Historical Buildings

NASA Astrophysics Data System (ADS)

Kulczykowski, Marek; Przewłócki, Jarosław; Konarzewska, Bogusława

2017-10-01

Soil nailing is one of the recent in situ techniques used for soil improvement and in stabilizing slopes. The process of soil nailing consists of reinforcing the natural ground with relatively small steel bars or metal rods, grouted in the pre-drilled holes. This method has a wide range of applications for stabilizing deep excavations and steep slopes. Soil nailing has recently become a very common method of slope stabilisation especially where situated beneath or adjacent to historical buildings. Stabilisation by nails drilled into existing masonry structures such as failing retaining walls abutments, provide long term stability without demolition and rebuilding costs. Two cases of soil nailing technology aimed at stabilising slopes beneath old buildings in Poland are presented in this paper. The first concerns application of this technology to repair a retaining wall supporting the base of the dam at the historic hydroelectric power plant in Rutki. The second regards a concept of improving the slope of the Castle Hill in Sandomierz. An analysis of the slope stability for the latter case, using stabilisation technique with the piling system and soil nailing was performed. Some advantages of soil nailing especially for protection of historical buildings, are also underlined. And, the main results of an economic comparison analysis are additionally presented.

Construction of a Dry Ash Dam with Soilbags and Slope Stability Analysis

NASA Astrophysics Data System (ADS)

Li, Hui; Song, Yingjun; Gao, Jiaorong; Li, Longhua; Zhou, Yuqi; Qi, Hui

2017-12-01

In thermal power plants, it is necessary to build ash dams to store fly ash, which is the by-product after the combustion of coals. To solve the problem of lacking rockfill materials in Africa, A new technology of constructing ash dams using solibags filled with local sands is proposed and the method of analyzing its slope stability is suggested. The design of the ash dam using soilbags in Lamb Thermal Power Plant of Kenya is introduced in detail. The slope stability of the soilbags-constructed ash dam was analyzed by adopting the suggested method. The results show that the soilbags filled with ash or sands have high compressive strength, and the primary dam constructed with soilbags can effectively retain the backfill ash and the stacking dam reinforced with soilbags can stand stable even with the slope of 1:1.5.

High sensitivity optical measurement of skin gloss

PubMed Central

Ezerskaia, Anna; Ras, Arno; Bloemen, Pascal; Pereira, Silvania F.; Urbach, H. Paul; Varghese, Babu

2017-01-01

We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on the sum over the intensities of pixels above threshold, derived from a camera image obtained using unpolarized white light illumination. We demonstrate the improved sensitivity of the two proposed methods using Monte Carlo simulations and experiments performed on ISO gloss calibration standards with an optical prototype. The performance and linearity of the method was compared with different professional gloss measurement devices based on the ratio of specular to diffuse intensity. We demonstrate the feasibility for in-vivo skin gloss measurements by quantifying the temporal evolution of skin gloss after application of standard paraffin cream bases on skin. The presented method opens new possibilities in the fields of cosmetology and dermatopharmacology for measuring the skin gloss and resorption kinetics and the pharmacodynamics of various external agents. PMID:29026683

High sensitivity optical measurement of skin gloss.

PubMed

Ezerskaia, Anna; Ras, Arno; Bloemen, Pascal; Pereira, Silvania F; Urbach, H Paul; Varghese, Babu

2017-09-01

We demonstrate a low-cost optical method for measuring the gloss properties with improved sensitivity in the low gloss regime, relevant for skin gloss properties. The gloss estimation method is based on, on the one hand, the slope of the intensity gradient in the transition regime between specular and diffuse reflection and on the other on the sum over the intensities of pixels above threshold, derived from a camera image obtained using unpolarized white light illumination. We demonstrate the improved sensitivity of the two proposed methods using Monte Carlo simulations and experiments performed on ISO gloss calibration standards with an optical prototype. The performance and linearity of the method was compared with different professional gloss measurement devices based on the ratio of specular to diffuse intensity. We demonstrate the feasibility for in-vivo skin gloss measurements by quantifying the temporal evolution of skin gloss after application of standard paraffin cream bases on skin. The presented method opens new possibilities in the fields of cosmetology and dermatopharmacology for measuring the skin gloss and resorption kinetics and the pharmacodynamics of various external agents.

A new method of carboxyhaemoglobin determination.

PubMed Central

Sanderson, J H; Sotheran, M F; Stattersfield, J P

1978-01-01

A quick and accurate method of determining the concentration of carboxyhaemoglobin (COHb) in blood has been developed. The method uses a dual wavelength double beam spectrophotometer in the 1st derivative mode, linked to a digital voltmeter (DVM), with the two beams set 3 nm apart around an isobestic point of reduced haemoglobin (Hbred) and carboxyhaemoglobin at 579 nm. The 1st derivative mode measures the slope, and this slope is proportional to the concentration of COHb. PMID:629892

40 CFR Figure C-2 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM 2.5 Candidate...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM 2.5 Candidate Equivalent Methods C Figure C-2 to Subpart C of Part... Candidate Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-2 Figure C-2 to Subpart C of Part 53...

40 CFR Figure C-2 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM 2.5 Candidate...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM 2.5 Candidate Equivalent Methods C Figure C-2 to Subpart C of Part... Candidate Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-2 Figure C-2 to Subpart C of Part 53...

Performance evaluation of setback buildings with open ground storey on plain and sloping ground under earthquake loadings and mitigation of failure

NASA Astrophysics Data System (ADS)

Ghosh, Rahul; Debbarma, Rama

2017-06-01

Setback structures are highly vulnerable during earthquakes due to its vertical geometrical and mass irregularity, but the vulnerability becomes higher if the structures also have stiffness irregularity in elevation. The risk factor of such structure may increase, if the structure rests on sloping ground. In this paper, an attempt has been made to evaluate the seismic performance of setback structures resting on plain ground as well as in the slope of a hill, with soft storey configuration. The analysis has been performed in three individual methods, equivalent static force method, response spectrum method and time history method and extreme responses have been recorded for open ground storeyed setback building. To mitigate this soft storey effect and the extreme responses, three individual mitigation techniques have been adopted and the best solution among these three techniques is presented.

Identification of potential rockfall source areas at a regional scale using a DEM-based geomorphometric analysis

NASA Astrophysics Data System (ADS)

Loye, A.; Jaboyedoff, M.; Pedrazzini, A.

2009-10-01

The availability of high resolution Digital Elevation Models (DEM) at a regional scale enables the analysis of topography with high levels of detail. Hence, a DEM-based geomorphometric approach becomes more accurate for detecting potential rockfall sources. Potential rockfall source areas are identified according to the slope angle distribution deduced from high resolution DEM crossed with other information extracted from geological and topographic maps in GIS format. The slope angle distribution can be decomposed in several Gaussian distributions that can be considered as characteristic of morphological units: rock cliffs, steep slopes, footslopes and plains. A terrain is considered as potential rockfall sources when their slope angles lie over an angle threshold, which is defined where the Gaussian distribution of the morphological unit "Rock cliffs" become dominant over the one of "Steep slopes". In addition to this analysis, the cliff outcrops indicated by the topographic maps were added. They contain however "flat areas", so that only the slope angles values above the mode of the Gaussian distribution of the morphological unit "Steep slopes" were considered. An application of this method is presented over the entire Canton of Vaud (3200 km2), Switzerland. The results were compared with rockfall sources observed on the field and orthophotos analysis in order to validate the method. Finally, the influence of the cell size of the DEM is inspected by applying the methodology over six different DEM resolutions.

Tensile stress-strain behavior of graphite/epoxy laminates

NASA Technical Reports Server (NTRS)

Garber, D. P.

1982-01-01

The tensile stress-strain behavior of a variety of graphite/epoxy laminates was examined. Longitudinal and transverse specimens from eleven different layups were monotonically loaded in tension to failure. Ultimate strength, ultimate strain, and strss-strain curves wee obtained from four replicate tests in each case. Polynominal equations were fitted by the method of least squares to the stress-strain data to determine average curves. Values of Young's modulus and Poisson's ratio, derived from polynomial coefficients, were compared with laminate analysis results. While the polynomials appeared to accurately fit the stress-strain data in most cases, the use of polynomial coefficients to calculate elastic moduli appeared to be of questionable value in cases involving sharp changes in the slope of the stress-strain data or extensive scatter.

Simulation of decelerating landing approaches on an externally blown flap STOL transport airplane

NASA Technical Reports Server (NTRS)

Grantham, W. D.; Nguyen, L. T.; Deal, P. L.

1974-01-01

A fixed-base simulator program was conducted to define the problems and methods for solution associated with performing decelerating landing approaches on a representative STOL transport having a high wing and equipped with an external-flow jet flap in combination with four high-bypass-ratio fan-jet engines. Real-time digital simulation techniques were used. The computer was programed with equations of motion for six degrees of freedom and the aerodynamic inputs were based on measured wind-tunnel data. The pilot's task was to capture the localizer and the glide slope and to maintain them as closely as possible while decelerating from an initial airspeed of 140 knots to a final airspeed of 75 knots, while under IFR conditions.

High-order optical vortex position detection using a Shack-Hartmann wavefront sensor.

PubMed

Luo, Jia; Huang, Hongxin; Matsui, Yoshinori; Toyoda, Haruyoshi; Inoue, Takashi; Bai, Jian

2015-04-06

Optical vortex (OV) beams have null-intensity singular points, and the intensities in the region surrounding the singular point are quite low. This low intensity region influences the position detection accuracy of phase singular point, especially for high-order OV beam. In this paper, we propose a new method for solving this problem, called the phase-slope-combining correlation matching method. A Shack-Hartmann wavefront sensor (SH-WFS) is used to measure phase slope vectors at lenslet positions of the SH-WFS. Several phase slope vectors are combined into one to reduce the influence of low-intensity regions around the singular point, and the combined phase slope vectors are used to determine the OV position with the aid of correlation matching with a pre-calculated database. Experimental results showed that the proposed method works with high accuracy, even when detecting an OV beam with a topological charge larger than six. The estimated precision was about 0.15 in units of lenslet size when detecting an OV beam with a topological charge of up to 20.

Numerical study of dam-break induced tsunami-like bore with a hump of different slopes

NASA Astrophysics Data System (ADS)

Cheng, Du; Zhao, Xi-zeng; Zhang, Da-ke; Chen, Yong

2017-12-01

Numerical simulation of dam-break wave, as an imitation of tsunami hydraulic bore, with a hump of different slopes is performed in this paper using an in-house code, named a Constrained Interpolation Profile (CIP)-based model. The model is built on a Cartesian grid system with the Navier Stokes equations using a CIP method for the flow solver, and employs an immersed boundary method (IBM) for the treatment of solid body boundary. A more accurate interface capturing scheme, the Tangent of hyperbola for interface capturing/Slope weighting (THINC/SW) scheme, is adopted as the interface capturing method. Then, the CIP-based model is applied to simulate the dam break flow problem in a bumpy channel. Considerable attention is paid to the spilling type reflected bore, the following spilling type wave breaking, free surface profiles and water level variations over time. Computations are compared with available experimental data and other numerical results quantitatively and qualitatively. Further investigation is conducted to analyze the influence of variable slopes on the flow features of the tsunami-like bore.

Reinforcing mechanism of anchors in slopes: a numerical comparison of results of LEM and FEM

NASA Astrophysics Data System (ADS)

Cai, Fei; Ugai, Keizo

2003-06-01

This paper reports the limitation of the conventional Bishop's simplified method to calculate the safety factor of slopes stabilized with anchors, and proposes a new approach to considering the reinforcing effect of anchors on the safety factor. The reinforcing effect of anchors can be explained using an additional shearing resistance on the slip surface. A three-dimensional shear strength reduction finite element method (SSRFEM), where soil-anchor interactions were simulated by three-dimensional zero-thickness elasto-plastic interface elements, was used to calculate the safety factor of slopes stabilized with anchors to verify the reinforcing mechanism of anchors. The results of SSRFEM were compared with those of the conventional and proposed approaches for Bishop's simplified method for various orientations, positions, and spacings of anchors, and shear strengths of soil-grouted body interfaces. For the safety factor, the proposed approach compared better with SSRFEM than the conventional approach. The additional shearing resistance can explain the influence of the orientation, position, and spacing of anchors, and the shear strength of soil-grouted body interfaces on the safety factor of slopes stabilized with anchors.

Performance analysis of a Hartmann wavefront sensor used for sensing atmospheric turbulence statistics

NASA Astrophysics Data System (ADS)

Welsh, Byron M.; Reeves, Toby D.; Roggemann, Michael C.

1997-09-01

The ability to measure atmospheric turbulence characteristics such as Fried's coherence diameter, the outer scale of turbulence, and the turbulence power law are critical for the optimized operation of adaptive optical telescopes. One approach for sensing these turbulence parameters is to use a Hartmann wavefront sensor (H-WFS) array to measure the wavefront slope structure function (SSF) . The SSF is defined as the second moment of the wavefront slope difference between any two subapertures separated in time and/or space. Accurate knowledge of the SSF allows turbulence parameters to be estimated. The H-WFS slope measurements, composed of a true slope signal corrupted by noise, are used to estimate the SSF by computing a mean square difference of slope signals from different subapertures. This computation is typically performed over a large number of H-WFS measurement frames. The quality of the SSF estimate is quantified by the signal-to-noise ratio (SNR) of the estimator. The quality of the SSF estimate then can in turn be related to the quality of the atmospheric turbulence parameter estimates. This research develops a theoretical SNR expression for the SSF estimator. This SNR is a function of H-WFS geometry, the number of temporal measurement frames, the outer scale of turbulence, the turbulence spectrum power law, and the temporal properties of the turbulence. Results are presented for various H-WFS configurations and atmospheric turbulence properties.

Tracer Kinetic Analysis of (S)-¹⁸F-THK5117 as a PET Tracer for Assessing Tau Pathology.

PubMed

Jonasson, My; Wall, Anders; Chiotis, Konstantinos; Saint-Aubert, Laure; Wilking, Helena; Sprycha, Margareta; Borg, Beatrice; Thibblin, Alf; Eriksson, Jonas; Sörensen, Jens; Antoni, Gunnar; Nordberg, Agneta; Lubberink, Mark

2016-04-01

Because a correlation between tau pathology and the clinical symptoms of Alzheimer disease (AD) has been hypothesized, there is increasing interest in developing PET tracers that bind specifically to tau protein. The aim of this study was to evaluate tracer kinetic models for quantitative analysis and generation of parametric images for the novel tau ligand (S)-(18)F-THK5117. Nine subjects (5 with AD, 4 with mild cognitive impairment) received a 90-min dynamic (S)-(18)F-THK5117 PET scan. Arterial blood was sampled for measurement of blood radioactivity and metabolite analysis. Volume-of-interest (VOI)-based analysis was performed using plasma-input models; single-tissue and 2-tissue (2TCM) compartment models and plasma-input Logan and reference tissue models; and simplified reference tissue model (SRTM), reference Logan, and SUV ratio (SUVr). Cerebellum gray matter was used as the reference region. Voxel-level analysis was performed using basis function implementations of SRTM, reference Logan, and SUVr. Regionally averaged voxel values were compared with VOI-based values from the optimal reference tissue model, and simulations were made to assess accuracy and precision. In addition to 90 min, initial 40- and 60-min data were analyzed. Plasma-input Logan distribution volume ratio (DVR)-1 values agreed well with 2TCM DVR-1 values (R(2)= 0.99, slope = 0.96). SRTM binding potential (BP(ND)) and reference Logan DVR-1 values were highly correlated with plasma-input Logan DVR-1 (R(2)= 1.00, slope ≈ 1.00) whereas SUVr(70-90)-1 values correlated less well and overestimated binding. Agreement between parametric methods and SRTM was best for reference Logan (R(2)= 0.99, slope = 1.03). SUVr(70-90)-1 values were almost 3 times higher than BP(ND) values in white matter and 1.5 times higher in gray matter. Simulations showed poorer accuracy and precision for SUVr(70-90)-1 values than for the other reference methods. SRTM BP(ND) and reference Logan DVR-1 values were not affected by a shorter scan duration of 60 min. SRTM BP(ND) and reference Logan DVR-1 values were highly correlated with plasma-input Logan DVR-1 values. VOI-based data analyses indicated robust results for scan durations of 60 min. Reference Logan generated quantitative (S)-(18)F-THK5117 DVR-1 parametric images with the greatest accuracy and precision and with a much lower white-matter signal than seen with SUVr(70-90)-1 images. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Turbulent flow separation in three-dimensional asymmetric diffusers

NASA Astrophysics Data System (ADS)

Jeyapaul, Elbert

2011-12-01

Turbulent three-dimensional flow separation is more complicated than 2-D. The physics of the flow is not well understood. Turbulent flow separation is nearly independent of the Reynolds number, and separation in 3-D occurs at singular points and along convergence lines emanating from these points. Most of the engineering turbulence research is driven by the need to gain knowledge of the flow field that can be used to improve modeling predictions. This work is motivated by the need for a detailed study of 3-D separation in asymmetric diffusers, to understand the separation phenomena using eddy-resolving simulation methods, assess the predictability of existing RANS turbulence models and propose modeling improvements. The Cherry diffuser has been used as a benchmark. All existing linear eddy-viscosity RANS models k--o SST,k--epsilon and v2- f fail in predicting such flows, predicting separation on the wrong side. The geometry has a doubly-sloped wall, with the other two walls orthogonal to each other and aligned with the diffuser inlet giving the diffuser an asymmetry. The top and side flare angles are different and this gives rise to different pressure gradient in each transverse direction. Eddyresolving simulations using the Scale adaptive simulation (SAS) and Large Eddy Simulation (LES) method have been used to predict separation in benchmark diffuser and validated. A series of diffusers with the same configuration have been generated, each having the same streamwise pressure gradient and parametrized only by the inlet aspect ratio. The RANS models were put to test and the flow physics explored using SAS-generated flow field. The RANS model indicate a transition in separation surface from top sloped wall to the side sloped wall at an inlet aspect ratio much lower than observed in LES results. This over-sensitivity of RANS models to transverse pressure gradients is due to lack of anisotropy in the linear Reynolds stress formulation. The complexity of the flow separation is due to effects of lateral straining, streamline curvature, secondary flow of second kind, transverse pressure gradient on turbulence. Resolving these effects is possible with anisotropy turbulence models as the Explicit Algebraic Reynolds stress model (EARSM). This model has provided accurate prediction of streamwise and transverse velocity, however the wall pressure is under predicted. An improved EARSM model is developed by correcting the coefficients, which predicts a more accurate wall pressure. There exists scope for improvement of this model, by including convective effects and dynamics of velocity gradient invariants.

Extinction Maps and Dust-to-gas Ratios in Nearby Galaxies with LEGUS

NASA Astrophysics Data System (ADS)

Kahre, L.; Walterbos, R. A.; Kim, H.; Thilker, D.; Calzetti, D.; Lee, J. C.; Sabbi, E.; Ubeda, L.; Aloisi, A.; Cignoni, M.; Cook, D. O.; Dale, D. A.; Elmegreen, B. G.; Elmegreen, D. M.; Fumagalli, M.; Gallagher, J. S., III; Gouliermis, D. A.; Grasha, K.; Grebel, E. K.; Hunter, D. A.; Sacchi, E.; Smith, L. J.; Tosi, M.; Adamo, A.; Andrews, J. E.; Ashworth, G.; Bright, S. N.; Brown, T. M.; Chandar, R.; Christian, C.; de Mink, S. E.; Dobbs, C.; Evans, A. S.; Herrero, A.; Johnson, K. E.; Kennicutt, R. C.; Krumholz, M. R.; Messa, M.; Nair, P.; Nota, A.; Pellerin, A.; Ryon, J. E.; Schaerer, D.; Shabani, F.; Van Dyk, S. D.; Whitmore, B. C.; Wofford, A.

2018-03-01

We present a study of the dust-to-gas ratios in five nearby galaxies: NGC 628 (M74), NGC 6503, NGC 7793, UGC 5139 (Holmberg I), and UGC 4305 (Holmberg II). Using Hubble Space Telescope broadband WFC3/UVIS UV and optical images from the Treasury program Legacy ExtraGalactic UV Survey (LEGUS) combined with archival HST/Advanced Camera for Surveys data, we correct thousands of individual stars for extinction across these five galaxies using an isochrone-matching (reddening-free Q) method. We generate extinction maps for each galaxy from the individual stellar extinctions using both adaptive and fixed resolution techniques and correlate these maps with neutral H I and CO gas maps from the literature, including the H I Nearby Galaxy Survey and the HERA CO-Line Extragalactic Survey. We calculate dust-to-gas ratios and investigate variations in the dust-to-gas ratio with galaxy metallicity. We find a power-law relationship between dust-to-gas ratio and metallicity, consistent with other studies of dust-to-gas ratio compared to metallicity. We find a change in the relation when H2 is not included. This implies that underestimation of {N}{{{H}}2} in low-metallicity dwarfs from a too-low CO-to-H2 conversion factor X CO could have produced too low a slope in the derived relationship between dust-to-gas ratio and metallicity. We also compare our extinctions to those derived from fitting the spectral energy distribution (SED) using the Bayesian Extinction and Stellar Tool for NGC 7793 and find systematically lower extinctions from SED fitting as compared to isochrone matching.

Kennicutt-Schmidt Relation Variety and Star-forming Cloud Fraction

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

Morokuma-Matsui, Kana; Muraoka, Kazuyuki, E-mail: kana.matsui@nao.ac.jp

2017-03-10

The observationally derived Kennicutt-Schmidt (KS) relation slopes differ from study to study, ranging from sublinear to superlinear. We investigate the KS-relation variety (slope and normalization) as a function of integrated intensity ratio, R {sub 31} = CO( J = 3–2)/CO( J = 1–0) using spatially resolved CO( J = 1–0), CO( J = 3–2), H i, H α, and 24 μ m data of three nearby spiral galaxies (NGC 3627, NGC 5055, and M83). We find that (1) the slopes for each subsample with a fixed R {sub 31} are shallower, but the slope for all data sets combined becomesmore » steeper, (2) normalizations for high R {sub 31} subsamples tend to be high, (3) R {sub 31} correlates with star formation efficiency, therefore the KS relation depends on the distribution in R {sub 31}–Σ{sub gas} space of the samples: no Σ{sub gas} dependence of R {sub 31} results in a linear slope of the KS relation, whereas a positive correlation between Σ{sub gas} and R {sub 31} results in a superlinear slope of the KS relation, and (4) R {sub 31}–Σ{sub gas} distributions are different from galaxy to galaxy and within a galaxy: galaxies with prominent galactic structure tend to have large R {sub 31} and Σ{sub gas}. Our results suggest that the formation efficiency of a star-forming cloud from molecular gas is different among galaxies as well as within a galaxy, and it is one of the key factors inducing the variety in galactic KS relation.« less

Assessments of the QT/QRS restitution in perfused guinea-pig heart can discriminate safe and arrhythmogenic drugs.

PubMed

Osadchii, Oleg E

2017-09-01

Drug-induced arrhythmia remains a matter of serious clinical concern, partly due to low prognostic value of currently available arrhythmic biomarkers. This study examined whether arrhythmogenic risks can be predicted through assessments of the rate adaptation of QT interval, ventricular effective refractory period (ERP), or the QT/QRS ratio, in perfused guinea-pig hearts. When the maximum restitution slope was taken as a metric of proarrhythmia, neither QT interval nor ERP measurements at progressively increased pacing rates were found to fully discriminate arrhythmogenic drugs (dofetilide, quinidine, flecainide, and procainamide) from those recognized as safe antiarrhythmics (lidocaine and mexiletine). For example, the slope of QT restitution was increased by dofetilide and quinidine, but remained unchanged by flecainide, procainamide, lidocaine, and mexiletine. With ERP rate adaptation, even though the restitution slope was increased by dofetilide, all class I agents reduced the slope value independently of their safety profile. The QRS measurements revealed variable drug effects, ranging from significant use-dependent conduction slowing (flecainide, quinidine, and procainamide) to only modest increase in QRS (lidocaine and mexiletine), or no change at all (dofetilide). However, with the QT/QRS rate adaptation, the restitution slope was significantly increased by all agents which have been reported to produce proarrhythmic effects (dofetilide, quinidine, flecainide, and procainamide), but not changed by lidocaine and mexiletine. These findings suggest that the slope of the QT/QRS rate adaptation can be considered as a novel electrophysiological biomarker in predicting potential arrhythmic risks associated with pharmacotherapy in cardiac patients. Copyright © 2017 Elsevier Inc. All rights reserved.

Slope-Area Computation Program Graphical User Interface 1.0—A Preprocessing and Postprocessing Tool for Estimating Peak Flood Discharge Using the Slope-Area Method

USGS Publications Warehouse

Bradley, D. Nathan

2012-01-01

The slope-area method is a technique for estimating the peak discharge of a flood after the water has receded (Dalrymple and Benson, 1967). This type of discharge estimate is called an “indirect measurement” because it relies on evidence left behind by the flood, such as high-water marks (HWMs) on trees or buildings. These indicators of flood stage are combined with measurements of the cross-sectional geometry of the stream, estimates of channel roughness, and a mathematical model that balances the total energy of the flow between cross sections. This is in contrast to a “direct” measurement of discharge during the flood where cross-sectional area is measured and a current meter or acoustic equipment is used to measure the water velocity. When a direct discharge measurement cannot be made at a gage during high flows because of logistics or safety reasons, an indirect measurement of a peak discharge is useful for defining the high-flow section of the stage-discharge relation (rating curve) at the stream gage, resulting in more accurate computation of high flows. The Slope-Area Computation program (SAC; Fulford, 1994) is an implementation of the slope-area method that computes a peak-discharge estimate from inputs of water-surface slope (from surveyed HWMs), channel geometry, and estimated channel roughness. SAC is a command line program written in Fortran that reads input data from a formatted text file and prints results to another formatted text file. Preparing the input file can be time-consuming and prone to errors. This document describes the SAC graphical user interface (GUI), a crossplatform “wrapper” application that prepares the SAC input file, executes the program, and helps the user interpret the output. The SAC GUI is an update and enhancement of the slope-area method (SAM; Hortness, 2004; Berenbrock, 1996), an earlier spreadsheet tool used to aid field personnel in the completion of a slope-area measurement. The SAC GUI reads survey data, develops a plan-view plot, water-surface profile, cross-section plots, and develops the SAC input file. The SAC GUI also develops HEC-2 files that can be imported into HEC–RAS.

Slope-assisted BOTDA based on vector SBS and frequency-agile technique for wide-strain-range dynamic measurements.

PubMed

Zhou, Dengwang; Dong, Yongkang; Wang, Benzhang; Jiang, Taofei; Ba, Dexin; Xu, Pengbai; Zhang, Hongying; Lu, Zhiwei; Li, Hui

2017-02-06

We present a slope-assisted BOTDA system based on the vector stimulated Brillouin scattering (SBS) and frequency-agile technique (FAT) for the wide-strain-range dynamic measurement. A dimensionless coefficient K defined as the ratio of Brillouin phase-shift to gain is employed to demodulate the strain of the fiber, and it is immune to the power fluctuation of pump pulse and has a linear relation of the frequency detuning for the continuous pump and Stokes waves. For a 30ns-square pump pulse, the available frequency span of the K spectrum can reach up to 200MHz, which is larger than fourfold of 48MHz-linewidth of Brillouin gain spectrum. For a single-slope assisted BOTDA, dynamic strain measurement with the maximum strain of 2467.4με and the vibration frequency components of 10.44Hz and 20.94Hz is obtained. For a multi-slope-assisted BOTDA, dynamic measurement with the strain variation up to 5372.9με and the vibration frequency components of 5.58Hz and 11.14Hz is achieved by using FAT to extend the strain range.

Quasi-analytical treatment of spatially averaged radiation transfer in complex terrain

NASA Astrophysics Data System (ADS)

LöWe, H.; Helbig, N.

2012-10-01

We provide a new quasi-analytical method to compute the subgrid topographic influences on the shortwave radiation fluxes and the effective albedo in complex terrain as required for large-scale meteorological, land surface, or climate models. We investigate radiative transfer in complex terrain via the radiosity equation on isotropic Gaussian random fields. Under controlled approximations we derive expressions for domain-averaged fluxes of direct, diffuse, and terrain radiation and the sky view factor. Domain-averaged quantities can be related to a type of level-crossing probability of the random field, which is approximated by long-standing results developed for acoustic scattering at ocean boundaries. This allows us to express all nonlocal horizon effects in terms of a local terrain parameter, namely, the mean-square slope. Emerging integrals are computed numerically, and fit formulas are given for practical purposes. As an implication of our approach, we provide an expression for the effective albedo of complex terrain in terms of the Sun elevation angle, mean-square slope, the area-averaged surface albedo, and the ratio of atmospheric direct beam to diffuse radiation. For demonstration we compute the decrease of the effective albedo relative to the area-averaged albedo in Switzerland for idealized snow-covered and clear-sky conditions at noon in winter. We find an average decrease of 5.8% and spatial patterns which originate from characteristics of the underlying relief. Limitations and possible generalizations of the method are discussed.

Estimation of penetration of forest canopies by Interferometric SAR measurements

NASA Technical Reports Server (NTRS)

Rodriguez, Ernesto; Michel, Thierry R.; Harding, David J.

1995-01-01

In contrast to traditional Synthetic Aperture Radar (SAR), an Interferometric SAR (INSAR) yields two additional measurements: the phase difference and the correlation between the two interferometric channels. The phase difference has been used to estimate topographic height. For homogeneous surfaces, the correlation depends on the system signal-to-noise (SNR) ratio, the interferometer parameters, and the local slope. In the presence of volume scattering, such as that encountered in vegetation canopies, the correlation between the two channels is also dependent on the degree of penetration of the radiation into the scattering medium. In this paper, we propose a method for removing system and slope effects in order to obtain the decorrelation due to penetration alone. The sensitivities and accuracy of the proposed method are determined by Monte Carlo experiments, and we show that the proposed technique has sufficient sensitivity to provide penetration measurements for airborne SAR systems. Next, we provide a theoretical model to estimate the degree of penetration in a way which is independent of the details of the scattering medium. We also present a model for the correlation from non-homogeneous layers. We assess the sensitivity of the proposed inversion technique to these inhomogeneous situations. Finally, we present a comparison of the interferometric results against in situ data obtained by an airborne laser profilometer which provides a direct measurement of tree height and an estimate of the vegetation density profile in the forested areas around Mt. Adams, WA.

Derivation of martian surface slope characteristics from directional thermal infrared radiometry

NASA Astrophysics Data System (ADS)

Bandfield, Joshua L.; Edwards, Christopher S.

2008-01-01

Directional thermal infrared measurements of the martian surface is one of a variety of methods that may be used to characterize surface roughness and slopes at scales smaller than can be obtained by orbital imagery. Thermal Emission Spectrometer (TES) emission phase function (EPF) observations show distinct apparent temperature variations with azimuth and emission angle that are consistent with the presence of warm, sunlit and cool, shaded slopes at typically ˜0.1 m scales. A surface model of a Gaussian distribution of azimuth independent slopes (described by θ-bar) is combined with a thermal model to predict surface temperature from each viewing angle and azimuth of the TES EPF observation. The models can be used to predict surface slopes using the difference in measured apparent temperature from 2 separate 60-70° emission angle observations taken ˜180° in azimuth relative to each other. Most martian surfaces are consistent with low to moderate slope distributions. The slope distributions display distinct correlations with latitude, longitude, and albedo. Exceptionally smooth surfaces are located at lower latitudes in both the southern highlands as well as in high albedo dusty terrains. High slopes are associated with southern high-latitude patterned ground and north polar sand dunes. There is little apparent correlation between high resolution imagery and the derived θ-bar, with exceptions such as duneforms. This method can be used to characterize potential landing sites by assuming fractal scaling behavior to meter scales. More precisely targeted thermal infrared observations from other spacecraft instruments are capable of significantly reducing uncertainty as well as reducing measurement spot size from 10s of kilometers to sub-kilometer scales.

Effect of the slope and initial moisture content on soil loss, aggregate and particle size distribution

NASA Astrophysics Data System (ADS)

Szabó, Judit Alexandra; Jakab, Gergely; Szabó, Boglárka

2015-04-01

Soil structure degradation has effect through the soil water balance and nutrient supply on the agricultural potential of an area. The soil erosion process comprises two phases: detachment and transport by water. To study the transport phase nozzle type laboratory-scale rainfall simulator was used with constant 80 mmhr-1 intensity on an arable haplic Cambisol. Measuring the aggregate and particle size distribution of the soil loss gives a good approach the erosion process. The primary objective of this study was to examine the sediment concentration, and detect the quality and quantity change of the soil loss during a single precipitation under six treatment combinations (recently tilled and crusty soil surface on two different slope steepness, inland inundation and drought soil conditions). Soil loss were collected continually, and separated per aggregate size fractions with sieves in three rounds during a rain to measure the weights. The particle size distribution was measured with Horiba LA-950 particle size analyzer. In general the ratio of the macro aggregates decreases and the ratio of the micro aggregates and clay fraction increases in the sediment with time during the precipitation due to the raindrop impact. Sediment concentration depends on the slope steepness, as from steeper slopes the runoff can transport bigger amount of sediment, but from the tilled surface bigger aggregates were washing down. Micro aggregate fraction is one of the indicators of good soil structure. The degradation of micro aggregates occurs in steeper slopes and the most erosive time period depends on the micromorphology of the surface. And while the aggregate size distribution of the soil loss of the treatments shows high variety of distribution and differs from the original soil, the particle size distribution of each aggregate size fraction shows similar trends except the 50-250 µm fraction where the fine sand fraction is dominating instead of the loam. This anomaly may be connected with the TC content of this fraction, but more research is needed. In agricultural areas micro aggregate fraction plays important role in nutrient supply thus understanding the erosion process is necessary because of the better protection in the future.

A comparative study on seismic response of two unstable rock slopes within same tectonic setting but different activity level

NASA Astrophysics Data System (ADS)

Kleinbrod, Ulrike; Burjánek, Jan; Hugentobler, Marc; Amann, Florian; Fäh, Donat

2017-12-01

In this study, the seismic response of two slope instabilities is investigated with seismic ambient vibration analysis. Two similar sites have been chosen: an active deep-seated slope instability at Cuolm da Vi and the geologically, structurally and morphologically similar, but presently not moving Alp Caschlè slope. Both slopes are located at the upper Vorderrheintal (Canton Graubünden, Switzerland). Ambient vibrations were recorded on both slopes and processed by time-frequency polarization and site-to-reference spectral ratio analysis. The data interpretation shows correlations between degree of disintegration of the rock mass and amplification. However, the ambient vibration analysis conducted, does not allow retrieving a resonance frequency that can be related to the total depth of the instability of Cuolm da Vi. Even though seismic waves can be hardly traced in rock instabilities containing open fractures, it was possible to retrieve a dispersion curve and a velocity profile from the array measurement at Cuolm da Vi due to the high level of disintegration of the rock material down to a depth of about 100 m. From the similar amplification pattern at the two sites, we expect a similar structure, indicating that also the slope at Alp Caschlè was active in the past in a similar manner as Cuolm da Vi. However, a smoother increase of amplification with frequency is observed at Alp Caschlè, which might indicate less disintegration of the rock mass in a particular depth range at this site, when comparing to Cuolm da Vi where a high level of disintegration is observed, resulting from the high activity at the slope. From the frequency-dependent amplification, we can distinguish between two parts within both instabilities, one part showing decreasing disintegration of the rock mass with increasing depth, for the other parts less-fractured blocks are observed. Since the block structures are found in the lower part of the instabilities, they might contribute to the stability of the slopes. Using the velocity profiles, it was possible to estimate the depth of the two largest open fractures (i.e. tension cracks) at Cuolm da Vi.

Optimization of gold ore Sumbawa separation using gravity method: Shaking table

NASA Astrophysics Data System (ADS)

Ferdana, Achmad Dhaefi; Petrus, Himawan Tri Bayu Murti; Bendiyasa, I. Made; Prijambada, Irfan Dwidya; Hamada, Fumio; Sachiko, Takahi

2018-04-01

Most of artisanal small gold mining in Indonesia has been using amalgamation method, which caused negative impact to the environment around ore processing area due to the usage of mercury. One of the more environmental-friendly method for gold processing is gravity method. Shaking table is one of separation equipment of gravity method used to increase concentrate based on difference of specific gravity. The optimum concentration result is influenced by several variables, such as rotational speed shaking, particle size and deck slope. In this research, the range of rotational speed shaking was between 100 rpm and 200 rpm, the particle size was between -100 + 200 mesh and -200 + 300 mesh and deck slope was between 3° and 7°. Gold concentration in concentrate was measured by EDX. The result shows that the optimum condition is obtained at a shaking speed of 200 rpm, with a slope of 7° and particle size of -100 + 200 mesh.

The Influence of Increasing Rain and Earthquake Activities on Landslide Slope Stability in Forest Areas

NASA Astrophysics Data System (ADS)

Kubota, T.; Aditian, A.

2014-12-01

Deriving the analysis of rainfall data in various mountainous locations, increase in rainfall that is deemed to be induced by the global climate change is obvious in Kyushu district, western Japan. On this point of view, its long term impact on the forest slope stability is analyzed with field investigation and numerical simulation such as finite element method (FEM). On the other hand, the influence of earthquake such as cracks on the slope due to seismic vibration was also analyzed with FEM. In this case, the slope stability analysis to obtain the factor of safety "Fs" is conducted. Here, in case of the Fs > 1.0, the slope is stable. In addition, the slope stabilizing effect of the forest mainly due to the roots strength is evaluated on some unstable slopes. Simultaneously, a holistic estimation over landslide groups is conducted by comparing "Fs" on forest slopes with non- forest slopes. Therefore, the following conclusions are obtained: 1) Comparing the Fs without increased rainfall from the previous decade and the one with actual rainfall, the former case is 1.04 ~1.06 times more stable than the latter. 2) On the other hand, the forest slopes are estimated to be up to approximately 1.5 to 2.5 times more stable than the slope without forest. Therefore, the slope stabilizing effect by the forest is much higher than the increasing rainfall influence i.e. the climate change effect. These results imply that an appropriate forest existence is important under the climate change condition to prevent forest slope degradation. 3) Comparing with the destabilization of the slope by seismic activities (vibration) due to the reduction of soil strength and "cracks = slope deformation" (8~9 % to 30% reduction in Fs even after an earthquake of 490gal), the influence of the long term rainfall increase on slopes (such as 1% decrease in Fs) is relatively small in the study area.

Spatial variability and its main controlling factors of the permafrost soil-moisture on the northern-slope of Bayan Har Mountains in Qinghai-Tibet Plateau

NASA Astrophysics Data System (ADS)

Cao, W.; Sheng, Y.

2017-12-01

The soil moisture movement is an important carrier of material cycle and energy flow among the various geo-spheres in the cold regions. It is very critical to protect the alpine ecology and hydrologic cycle in Qinghai-Tibet Plateau. Especially, it becomes one of the key problems to reveal the spatial-temporal variability of soil moisture movement and its main influence factors in earth system science. Thus, this research takes the north slope of Bayan Har Mountains in Qinghai-Tibet Plateau as a case study. The present study firstly investigates the change of permafrost moisture in different slope positions and depths. Based on this investigation, this article attempts to investigate the spatial variability of permafrost moisture and identifies the key influence factors in different terrain conditions. The method of classification and regression tree (CART) is adopted to identify the main controlling factors influencing the soil moisture movement. And the relationships between soil moisture and environmental factors are revealed by the use of the method of canonical correspondence analysis (CCA). The results show that: 1) the change of the soil moisture on the permafrost slope is divided into 4 stages, including the freezing stability phase, the rapid thawing phase, the thawing stability phase and the fast freezing phase; 2) this greatly enhances the horizontal flow in the freezing period due to the terrain slope and the freezing-thawing process. Vertical migration is the mainly form of the soil moisture movement. It leads to that the soil-moisture content in the up-slope is higher than that in the down-slope. On the contrary, the soil-moisture content in the up-slope is lower than that in the down-slope during the melting period; 3) the main environmental factors which affect the slope-permafrost soil-moisture are elevation, soil texture, soil temperature and vegetation coverage. But there are differences in the impact factors of the soil moisture in different freezing-thawing stages; 4) the main factors that affect the slope-permafrost soil-moisture at the shallow depth of 0-20cm are slope, elevation and vegetation coverage. And the main factors influencing the soil moisture at the middle and lower depth are complex.

Galaxy structure from multiple tracers - III. Radial variations in M87's IMF

NASA Astrophysics Data System (ADS)

Oldham, Lindsay; Auger, Matthew

2018-03-01

We present the first constraints on stellar mass-to-light ratio gradients in an early-type galaxy (ETG) using multiple dynamical tracer populations to model the dark and luminous mass structure simultaneously. We combine the kinematics of the central starlight, two globular cluster populations and satellite galaxies in a Jeans analysis to obtain new constraints on M87's mass structure, employing a flexible mass model which allows for radial gradients in the stellar-mass-to-light ratio. We find that, in the context of our model, a radially declining stellar-mass-to-light ratio is strongly favoured. Modelling the stellar-mass-to-light ratio as following a power law, ϒ⋆ ˜ R-μ, we infer a power-law slope μ = -0.54 ± 0.05; equally, parametrizing the stellar-mass-to-light ratio via a central mismatch parameter relative to a Salpeter initial mass function (IMF), α, and scale radius RM, we find α > 1.48 at 95% confidence and RM = 0.35 ± 0.04 kpc. We use stellar population modelling of high-resolution 11-band HST photometry to show that such a steep gradient cannot be achieved by variations in only the metallicity, age, dust extinction and star formation history if the stellar IMF remains spatially constant. On the other hand, the stellar-mass-to-light ratio gradient that we find is consistent with an IMF whose inner slope changes such that it is Salpeter-like in the central ˜0.5 kpc and becomes Chabrier-like within the stellar effective radius. This adds to recent evidence that the non-universality of the IMF in ETGs may be confined to their core regions, and points towards a picture in which the stars in these central regions may have formed in fundamentally different physical conditions.

Influence of extensive compressed natural gas (CNG) usage on air quality

NASA Astrophysics Data System (ADS)

Suthawaree, Jeeranut; Sikder, Helena Akhter; Jones, Charlotte Emily; Kato, Shungo; Kunimi, Hitoshi; Mohammed Hamidul Kabir, Abu Naser; Kajii, Yoshizumi

2012-07-01

Compressed Natural Gas (CNG) is an inexpensive, indigenous energy resource which currently accounts for the majority of automobile and domestic energy consumption in Bangladesh. This extensive CNG usage, particularly within the capital city, Dhaka, heavily influences the atmospheric composition (and hence air quality), yet to date measurements of trace gases in regions dominated by CNG emissions are relatively limited. Here we report continuous observations of the atmospherically important trace gases O3, CO, SO2, NOx and volatile organic compounds (VOC), in ambient air in Dhaka City, Bangladesh, during May 2011. The average mixing ratios of O3, CO, SO2, and NOx for the measurement period were 18.9, 520.9, 7.6 and 21.5 ppbv, respectively. The ratios of CO to NO reveal that emissions from gasoline and CNG-fuelled vehicles were dominant during the daytime (slope of ˜26), while in contrast, owing to restrictions imposed on diesel fuelled vehicles entering Dhaka City, emissions from these vehicles only became significant during the night (slope of ˜10). The total VOC mixing ratio in Dhaka was ˜5-10 times higher than the levels reported in more developed Asian cities such as Tokyo and Bangkok, which consequently gives rise to a higher ozone formation potential (OFP). However, the most abundant VOC in Dhaka were the relatively long-lived ethane and propane (with mean mixing ratios of ˜115 and ˜30 ppbv, respectively), and as a consequence, the ozone formation potential per ppb carbon (ppbC) was lower in Dhaka than in Tokyo and Bangkok. Thus the atmospheric composition of air influenced by extensive CNG combustion may be characterized by high VOC mixing ratios, yet mixing ratios of the photochemical pollutant ozone do not drastically exceed the levels typical of Asian cities with considerably lower VOC levels.

Mechanical Properties of Misers Bluff Sand.

DTIC Science & Technology

1986-09-01

in Chapter 4. 4 .7 Y~ e -~1 % CHAPTER 2 LABORATORY TESTS 2.1 CONVENTIONAL SOIL TESTS Samples of MB sand were split from the available supply of...air Va , and void ratio e (the ratio of void volume to solid volume). These composition data are listed in Table 2.1 for each test. 5 2.3 MECHANICAL...and diameter changes are made. The data can be plotted as principal stress difference versus axial strain, the slope of which is Young’s modulus E

Slope failures evaluation and landslides investigation using 2-D resistivity method

NASA Astrophysics Data System (ADS)

Nordiana, M. M.; Azwin, I. N.; Nawawi, M. N. M.; Khalil, A. E.

2018-06-01

Slope failure is a complex phenomenon that may caused to landslides. Buildings and infrastructure such as transportation facilities and pipelines located within the boundaries of a landslide can be damaged or destroyed. Slope failure classification and various factors contributing to the instability using 2-D resistivity survey conducted in Selangor, Malaysia are described. Six 2-D resistivity survey lines with 5 m minimum electrode spacing using Pole-dipole array were performed. The data were processed using Res2Dinv and surfer10 software to evaluate the subsurface characteristics. The 2-D resistivity results show that the subsurface consist of two main zones. The first zone was alluvium or highly weathered with resistivity value of 100-1000 Ω m and depth of >30 m. This zone consists of saturated area with resistivity value of 1-100 Ω m and boulders with resistivity value of 1200-7000 Ω m. The second zone with resistivity value of >7000 Ω m was interpreted as granitic bedrock. The study area was characterized by saturated zones, highly weathered zone, highly contain of sand and boulders that will trigger slope failure in the survey area. This will cause to low strength of soil, debris flow and movement of earth. On the basis of the case examples described, 2-D resistivity method is categorized into desirable and useful method in determination of slope failure and future assessments.

A GIS-based automated procedure for landslide susceptibility mapping by the Conditional Analysis method: the Baganza valley case study (Italian Northern Apennines)

NASA Astrophysics Data System (ADS)

Clerici, Aldo; Perego, Susanna; Tellini, Claudio; Vescovi, Paolo

2006-08-01

Among the many GIS based multivariate statistical methods for landslide susceptibility zonation, the so called “Conditional Analysis method” holds a special place for its conceptual simplicity. In fact, in this method landslide susceptibility is simply expressed as landslide density in correspondence with different combinations of instability-factor classes. To overcome the operational complexity connected to the long, tedious and error prone sequence of commands required by the procedure, a shell script mainly based on the GRASS GIS was created. The script, starting from a landslide inventory map and a number of factor maps, automatically carries out the whole procedure resulting in the construction of a map with five landslide susceptibility classes. A validation procedure allows to assess the reliability of the resulting model, while the simple mean deviation of the density values in the factor class combinations, helps to evaluate the goodness of landslide density distribution. The procedure was applied to a relatively small basin (167 km2) in the Italian Northern Apennines considering three landslide types, namely rotational slides, flows and complex landslides, for a total of 1,137 landslides, and five factors, namely lithology, slope angle and aspect, elevation and slope/bedding relations. The analysis of the resulting 31 different models obtained combining the five factors, confirms the role of lithology, slope angle and slope/bedding relations in influencing slope stability.

A hybrid method for quasi-three-dimensional slope stability analysis in a municipal solid waste landfill.

PubMed

Yu, L; Batlle, F

2011-12-01

Limited space for accommodating the ever increasing mounds of municipal solid waste (MSW) demands the capacity of MSW landfill be maximized by building landfills to greater heights with steeper slopes. This situation has raised concerns regarding the stability of high MSW landfills. A hybrid method for quasi-three-dimensional slope stability analysis based on the finite element stress analysis was applied in a case study at a MSW landfill in north-east Spain. Potential slides can be assumed to be located within the waste mass due to the lack of weak foundation soils and geosynthetic membranes at the landfill base. The only triggering factor of deep-seated slope failure is the higher leachate level and the relatively high and steep slope in the front. The valley-shaped geometry and layered construction procedure at the site make three-dimensional slope stability analyses necessary for this landfill. In the finite element stress analysis, variations of leachate level during construction and continuous settlement of the landfill were taken into account. The "equivalent" three-dimensional factor of safety (FoS) was computed from the individual result of the two-dimensional analysis for a series of evenly spaced cross sections within the potential sliding body. Results indicate that the hybrid method for quasi-three-dimensional slope stability analysis adopted in this paper is capable of locating roughly the spatial position of the potential sliding mass. This easy to manipulate method can serve as an engineering tool in the preliminary estimate of the FoS as well as the approximate position and extent of the potential sliding mass. The result that FoS obtained from three-dimensional analysis increases as much as 50% compared to that from two-dimensional analysis implies the significance of the three-dimensional effect for this study-case. Influences of shear parameters, time elapse after landfill closure, leachate level as well as unit weight of waste on FoS were also investigated in this paper. These sensitivity analyses serve as the guidelines of construction practices and operating procedures for the MSW landfill under study. Copyright © 2011 Elsevier Ltd. All rights reserved.

40 CFR Figure C-2 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM2.5 Candidate...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM2.5 Candidate Equivalent Methods C Figure C-2 to Subpart C of Part 53... Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-2 Figure C-2 to Subpart C of Part 53—Illustration...

40 CFR Figure C-3 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM 10-2,5 Candidate...

Code of Federal Regulations, 2013 CFR

2013-07-01

... 40 Protection of Environment 6 2013-07-01 2013-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM 10-2,5 Candidate Equivalent Methods C Figure C-3 to Subpart C of... Candidate Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-3 Figure C-3 to Subpart C of Part 53...

40 CFR Figure C-3 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM10−2.5 Candidate...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM10â2.5 Candidate Equivalent Methods C Figure C-3 to Subpart C of Part... Candidate Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-3 Figure C-3 to Subpart C of Part 53...

40 CFR Figure C-3 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM10−2.5 Candidate...

Code of Federal Regulations, 2012 CFR

2012-07-01

... 40 Protection of Environment 6 2012-07-01 2012-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM10â2.5 Candidate Equivalent Methods C Figure C-3 to Subpart C of Part... Candidate Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-3 Figure C-3 to Subpart C of Part 53...

40 CFR Figure C-2 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM2.5 Candidate...

Code of Federal Regulations, 2011 CFR

2011-07-01

... 40 Protection of Environment 5 2011-07-01 2011-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM2.5 Candidate Equivalent Methods C Figure C-2 to Subpart C of Part 53... Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-2 Figure C-2 to Subpart C of Part 53—Illustration...

40 CFR Figure C-3 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM 10-2.5 Candidate...

Code of Federal Regulations, 2014 CFR

2014-07-01

... 40 Protection of Environment 6 2014-07-01 2014-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM 10-2.5 Candidate Equivalent Methods C Figure C-3 to Subpart C of... Candidate Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-3 Figure C-3 to Subpart C of Part 53...

40 CFR Figure C-2 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM2.5 Candidate...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM2.5 Candidate Equivalent Methods C Figure C-2 to Subpart C of Part 53... Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-2 Figure C-2 to Subpart C of Part 53—Illustration...

40 CFR Figure C-3 to Subpart C of... - Illustration of the Slope and Intercept Limits for Class II and Class III PM10−2.5 Candidate...

Code of Federal Regulations, 2010 CFR

2010-07-01

... 40 Protection of Environment 5 2010-07-01 2010-07-01 false Illustration of the Slope and Intercept Limits for Class II and Class III PM10â2.5 Candidate Equivalent Methods C Figure C-3 to Subpart C of Part... Candidate Methods and Reference Methods Pt. 53, Subpt. C, Fig. C-3 Figure C-3 to Subpart C of Part 53...

Extension of a GIS procedure for calculating the RUSLE equation LS factor

NASA Astrophysics Data System (ADS)

Zhang, Hongming; Yang, Qinke; Li, Rui; Liu, Qingrui; Moore, Demie; He, Peng; Ritsema, Coen J.; Geissen, Violette

2013-03-01

The Universal Soil Loss Equation (USLE) and revised USLE (RUSLE) are often used to estimate soil erosion at regional landscape scales, however a major limitation is the difficulty in extracting the LS factor. The geographic information system-based (GIS-based) methods which have been developed for estimating the LS factor for USLE and RUSLE also have limitations. The unit contributing area-based estimation method (UCA) converts slope length to unit contributing area for considering two-dimensional topography, however is not able to predict the different zones of soil erosion and deposition. The flowpath and cumulative cell length-based method (FCL) overcomes this disadvantage but does not consider channel networks and flow convergence in two-dimensional topography. The purpose of this research was to overcome these limitations and extend the FCL method through inclusion of channel networks and convergence flow. We developed LS-TOOL in Microsoft's.NET environment using C♯ with a user-friendly interface. Comparing the LS factor calculated with the three methodologies (UCA, FCL and LS-TOOL), LS-TOOL delivers encouraging results. In particular, LS-TOOL uses breaks in slope identified from the DEM to locate soil erosion and deposition zones, channel networks and convergence flow areas. Comparing slope length and LS factor values generated using LS-TOOL with manual methods, LS-TOOL corresponds more closely with the reality of the Xiannangou catchment than results using UCA or FCL. The LS-TOOL algorithm can automatically calculate slope length, slope steepness, L factor, S factor, and LS factors, providing the results as ASCII files which can be easily used in some GIS software. This study is an important step forward in conducting more accurate large area erosion evaluation.

A template-based approach to semi-quantitative SPECT myocardial perfusion imaging: Independent of normal databases.

PubMed

Hughes, Tyler; Shcherbinin, Sergey; Celler, Anna

2011-07-01

Normal patient databases (NPDs) are used to distinguish between normal and abnormal perfusion in SPECT myocardial perfusion imaging (MPI) and have gained wide acceptance in the clinical environment, yet there are limitations to this approach. This study introduces a template-based method for semi-quantitative MPI, which attempts to overcome some of the NPD limitations. Our approach involves the construction of a 3D digital healthy heart template from the delineation of the patient's left ventricle in the SPECT image. This patient-specific template of the heart, filled with uniform activity, is then analytically projected and reconstructed using the same algorithm as the original image. Subsequent to generating bulls-eye maps for the patient image (PB) and the template image (TB), a ratio (PB/TB) is calculated, which produces a reconstruction-artifact corrected image (CB). Finally, a threshold is used to define defects within CB enabling measurements of the perfusion defect extent (EXT). The SPECT-based template (Ts) measurements were compared to those of a CT-based "ideal" template (TI). Twenty digital phantoms were simulated: male and female, each with one healthy heart and nine hearts with various defects. Four physical phantom studies were performed modeling a healthy heart and three hearts with different defects. The phantom represented a thorax with spine, lung, and left ventricle inserts. Images were acquired on General Electric's (GE) Infinia Hawkeye SPECT/CT camera using standard clinical MPI protocol. Finally, our method was applied to 14 patient MPI rest/stress studies acquired on the GE Infinia Hawkeye SPECT/CT camera and compared to the results obtained from Cedars-Sinai's QPS software. In the simulation studies, the true EXT correlated well with the TI (slope= 1.08; offset = -0.40%; r = 0.99) and Ts (slope = 0.90; offset = 0.27%; r = 0.99) methods with no significant differences between them. Similarly, strong correlations were measured for EXT obtained from QPS and the template method for patient studies (slope =0.91; offset = 0.45%; r = 0.98). Mean errors in extent for the Ts method using simulation, physical phantom, and patient data were 2.7% +/- 2.4%, 0.9% +/- 0.5%, 2.0% +/- 2.7%, respectively. The authors introduced a method for semi-quantitative SPECT MPI, which offers a patient-specific approach to define the perfusion defect regions within the heart, as opposed to the patient-averaged NPD methodology.

Tensile and fatigue data for irradiated and unirradiated AISI 310 stainless steel and titanium - 5 percent aluminum - 2.5 percent tin: Application of the method of universal slopes

NASA Technical Reports Server (NTRS)

Debogdan, C. E.

1973-01-01

Irradiated and unirradiated tensile and fatigue specimens of AISI 310 stainless steel and Ti-5Al-2.5Sn were tested in the range of 100 to 10,000 cycles to failure to determine the applicability of the method of universal slopes to irradiated materials. Tensile data for both materials showed a decrease in ductility and increase in ultimate tensile strength due to irradiation. Irradiation caused a maximum change in fatigue life of only 15 to 20 percent for both materials. The method of universal slopes predicted all the fatigue data for the 310 SS (irradiated as well as unirradiated) within a life factor of 2. For the titanium alloy, 95 percent of the data was predicted within a life factor of 3.

A landslide susceptibility prediction on a sample slope in Kathmandu Nepal associated with the 2015's Gorkha Earthquake

NASA Astrophysics Data System (ADS)

Kubota, Tetsuya; Prasad Paudel, Prem

2016-04-01

In 2013, some landslides induced by heavy rainfalls occurred in southern part of Kathmandu, Nepal which is located southern suburb of Kathmandu, the capital. These landslide slopes hit by the strong Gorkha Earthquake in April 2015 and seemed to destabilize again. Hereby, to clarify their susceptibility of landslide in the earthquake, one of these landslide slopes was analyzed its slope stability by CSSDP (Critical Slip Surface analysis by Dynamic Programming based on limit equilibrium method, especially Janbu method) against slope failure with various seismic acceleration observed around Kathmandu in the Gorkha Earthquake. The CSSDP can detect the landslide slip surface which has minimum Fs (factor of safety) automatically using dynamic programming theory. The geology in this area mainly consists of fragile schist and it is prone to landslide occurrence. Field survey was conducted to obtain topological data such as ground surface and slip surface cross section. Soil parameters obtained by geotechnical tests with field sampling were applied. Consequently, the slope has distinctive characteristics followings in terms of slope stability: (1) With heavy rainfall, it collapsed and had a factor of safety Fs <1.0 (0.654 or more). (2) With seismic acceleration of 0.15G (147gal) observed around Kathmandu, it has Fs=1.34. (3) With possible local seismic acceleration of 0.35G (343gal) estimated at Kathmandu, it has Fs=0.989. If it were very shallow landslide and covered with cedars, it could have Fs =1.055 due to root reinforcement effect to the soil strength. (4) Without seismic acceleration and with no rainfall condition, it has Fs=1.75. These results can explain the real landslide occurrence in this area with the maximum seismic acceleration estimated as 0.15G in the vicinity of Kathmandu by the Gorkha Earthquake. Therefore, these results indicate landslide susceptibility of the slopes in this area with strong earthquake. In this situation, it is possible to predict efficiently the landslide susceptibility in earthquakes in this area by this method.

GIS/RS-based Rapid Reassessment for Slope Land Capability Classification

NASA Astrophysics Data System (ADS)

Chang, T. Y.; Chompuchan, C.

2014-12-01

Farmland resources in Taiwan are limited because about 73% is mountainous and slope land. Moreover, the rapid urbanization and dense population resulted in the highly developed flat area. Therefore, the utilization of slope land for agriculture is more needed. In 1976, "Slope Land Conservation and Utilization Act" was promulgated to regulate the slope land utilization. Consequently, slope land capability was categorized into Class I-IV according to 4 criteria, i.e., average land slope, effective soil depth, degree of soil erosion, and parent rock. The slope land capability Class I-VI are suitable for cultivation and pasture. Whereas, Class V should be used for forestry purpose and Class VI should be the conservation land which requires intensive conservation practices. The field survey was conducted to categorize each land unit as the classification scheme. The landowners may not allow to overuse land capability limitation. In the last decade, typhoons and landslides frequently devastated in Taiwan. The rapid post-disaster reassessment of the slope land capability classification is necessary. However, the large-scale disaster on slope land is the constraint of field investigation. This study focused on using satellite remote sensing and GIS as the rapid re-evaluation method. Chenyulan watershed in Nantou County, Taiwan was selected to be a case study area. Grid-based slope derivation, topographic wetness index (TWI) and USLE soil loss calculation were used to classify slope land capability. The results showed that GIS-based classification give an overall accuracy of 68.32%. In addition, the post-disaster areas of Typhoon Morakot in 2009, which interpreted by SPOT satellite imageries, were suggested to classify as the conservation lands. These tools perform better in the large coverage post-disaster update for slope land capability classification and reduce time-consuming, manpower and material resources to the field investigation.

Seismic response of rock slopes: Numerical investigations on the role of internal structure

NASA Astrophysics Data System (ADS)

Arnold, L.; Applegate, K.; Gibson, M.; Wartman, J.; Adams, S.; Maclaughlin, M.; Smith, S.; Keefer, D. K.

2013-12-01

The stability of rock slopes is significantly influenced and often controlled by the internal structure of the slope created by such discontinuities as joints, shear zones, and faults. Under seismic conditions, these discontinuities influence both the resistance of a slope to failure and its response to dynamic loading. The dynamic response, which can be characterized by the slope's natural frequency and amplification of ground motion, governs the loading experienced by the slope in a seismic event and, therefore, influences the slope's stability. In support of the Network for Earthquake Engineering Simulation (NEES) project Seismically-Induced Rock Slope Failure: Mechanisms and Prediction (NEESROCK), we conducted a 2D numerical investigation using the discrete element method (DEM) coupled with simple discrete fracture networks (DFNs). The intact rock mass is simulated with a bonded assembly of discrete particles, commonly referred to as the bonded-particle model (BPM) for rock. Discontinuities in the BPM are formed by the insertion of smooth, unbonded contacts along specified planes. The influence of discontinuity spacing, orientation, and stiffness on slope natural frequency and amplification was investigated with the commercially available Particle Flow Code (PFC2D). Numerical results indicate that increased discontinuity spacing has a non-linear effect in decreasing the amplification and increasing the natural frequency of the slope. As discontinuity dip changes from sub-horizontal to sub-vertical, the slope's level of amplification increases while the natural frequency of the slope decreases. Increased joint stiffness decreases amplification and increases natural frequency. The results reveal that internal structure has a strong influence on rock slope dynamics that can significantly change the system's dynamic response and stability during seismic loading. Financial support for this research was provided by the United States National Science Foundation (NSF) under grant CMMI-1156413.

The Triton: Design concepts and methods

NASA Technical Reports Server (NTRS)

Meholic, Greg; Singer, Michael; Vanryn, Percy; Brown, Rhonda; Tella, Gustavo; Harvey, Bob

1992-01-01

During the design of the C & P Aerospace Triton, a few problems were encountered that necessitated changes in the configuration. After the initial concept phase, the aspect ratio was increased from 7 to 7.6 to produce a greater lift to drag ratio (L/D = 13) which satisfied the horsepower requirements (118 hp using the Lycoming O-235 engine). The initial concept had a wing planform area of 134 sq. ft. Detailed wing sizing analysis enlarged the planform area to 150 sq. ft., without changing its layout or location. The most significant changes, however, were made just prior to inboard profile design. The fuselage external diameter was reduced from 54 to 50 inches to reduce drag to meet the desired cruise speed of 120 knots. Also, the nose was extended 6 inches to accommodate landing gear placement. Without the extension, the nosewheel received an unacceptable percentage (25 percent) of the landing weight. The final change in the configuration was made in accordance with the stability and control analysis. In order to reduce the static margin from 20 to 13 percent, the horizontal tail area was reduced from 32.02 to 25.0 sq. ft. The Triton meets all the specifications set forth in the design criteria. If time permitted another iteration of the calculations, two significant changes would be made. The vertical stabilizer area would be reduced to decrease the aircraft lateral stability slope since the current value was too high in relation to the directional stability slope. Also, the aileron size would be decreased to reduce the roll rate below the current 106 deg/second. Doing so would allow greater flap area (increasing CL(sub max)) and thus reduce the overall wing area. C & P would also recalculate the horsepower and drag values to further validate the 120 knot cruising speed.

Relationships between lead biomarkers and diurnal salivary cortisol indices in pregnant women from Mexico City: a cross-sectional study

PubMed Central

2014-01-01

Background Lead (Pb) exposure during pregnancy may increase the risk of adverse maternal, infant, or childhood health outcomes by interfering with hypothalamic-pituitary-adrenal-axis function. We examined relationships between maternal blood or bone Pb concentrations and features of diurnal cortisol profiles in 936 pregnant women from Mexico City. Methods From 2007–11 we recruited women from hospitals/clinics affiliated with the Mexican Social Security System. Pb was measured in blood (BPb) during the second trimester and in mothers’ tibia and patella 1-month postpartum. We characterized maternal HPA-axis function using 10 timed salivary cortisol measurements collected over 2-days (mean: 19.7, range: 14–35 weeks gestation). We used linear mixed models to examine the relationship between Pb biomarkers and cortisol area under the curve (AUC), awakening response (CAR), and diurnal slope. Results After adjustment for confounders, women in the highest quintile of BPb concentrations had a reduced CAR (Ratio: −13%; Confidence Interval [CI]: −24, 1, p-value for trend < 0.05) compared to women in the lowest quintile. Tibia/patella Pb concentrations were not associated with CAR, but diurnal cortisol slopes were suggestively flatter among women in the highest patella Pb quantile compared to women in the lowest quantile (Ratio: 14%; CI: −2, 33). BPb and bone Pb concentrations were not associated with cortisol AUC. Conclusions Concurrent blood Pb levels were associated with cortisol awakening response in these pregnant women and this might explain adverse health outcomes associated with Pb. Further research is needed to confirm these results and determine if other environmental chemicals disrupt hypothalamic-pituitary-adrenal-axis function during pregnancy. PMID:24916609

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.

Photopolymerized materials and patterning for improved performance of neural prosthetics

NASA Astrophysics Data System (ADS)

Tuft, Bradley William

Neural prosthetics are used to replace or substantially augment remaining motor and sensory functions of neural pathways that were lost or damaged due to physical trauma, disease, or genetics. However, due to poor spatial signal resolution, neural prostheses fail to recapitulate the intimate, precise interactions inherent to neural networks. Designing materials and interfaces that direct de novo nerve growth to spatially specific stimulating elements is, therefore, a promising method to enhance signal specificity and performance of prostheses such as the successful cochlear implant (CI) and the developing retinal implant. In this work, the spatial and temporal reaction control inherent to photopolymerization was used to develop methods to generate micro and nanopatterned materials that direct neurite growth from prosthesis relevant neurons. In particular, neurite growth and directionality has been investigated in response to physical, mechanical, and chemical cues on photopolymerized surfaces. Spiral ganglion neurons (SGNs) serve as the primary neuronal model as they are the principal target for CI stimulation. The objective of the research is to rationally design materials that spatially direct neurite growth and to translate fundamental understanding of nerve cell-material interactions into methods of nerve regeneration that improve neural prosthetic performance. A rapid, single-step photopolymerization method was developed to fabricate micro and nanopatterned physical cues on methacrylate surfaces by selectively blocking light with photomasks. Feature height is readily tuned by modulating parameters of the photopolymerizaiton including initiator concentration and species, light intensity, separation distance from the photomask, and radiation exposure time. Alignment of neural elements increases significantly with increasing feature amplitude and constant periodicity, as well as with decreasing periodicity and constant amplitude. SGN neurite alignment strongly correlates with the maximum feature slope. Neurite alignment is compared on unpatterned, unidirectional, and multidirectional photopolymerized micropatterns. The effect of substrate rigidity on neurite alignment to physical cues was determined by maintaining equivalent pattern microfeatures, afforded by the reaction control of photopolymerization, while concomitantly altering the composition of several copolymer platforms to tune matrix stiffness. For each platform, neurite alignment to unidirectional patterns increases with increasing substrate rigidity. Interestingly, SGN neurites respond to material stiffness cues that are orders of magnitude higher (GPa) than what is typically ascribed to neural environments (kPa). Finally, neurite behavior at bioactive borders of various adhesion modulating molecules was evaluated on micropatterned materials to determine which cues took precedence in establishing neurite directionality. At low microfeatures aspect ratios, neurites align to the pattern direction but are then caused to turn and repel from or turn and align to bioactive borders. Conversely, physical cues dominate neurite path-finding as pattern feature slope increases, i.e. aspect ratio of sloping photopolymerized features increases, causing neurites to readily cross bioactive borders. The photopolymerization method developed in this work to generate micro and nanopatterned materials serves as an additional surface engineering tool that enables investigation of cell-material interactions including directed de novo neurite growth. The results of this interdisciplinary effort contribute substantially to polymer neural regeneration technology and will lead to development of advanced biomaterials that improve neural prosthetic tissue integration and performance by spatially directing nerve growth.

3D-profile measurement of advanced semiconductor features by using FIB as reference metrology

NASA Astrophysics Data System (ADS)

Takamasu, Kiyoshi; Iwaki, Yuuki; Takahashi, Satoru; Kawada, Hiroki; Ikota, Masami

2017-03-01

A novel method of sub-nanometer uncertainty for the 3D-profile measurement and LWR (Line Width Roughness) measurement by using FIB (Focused Ion Beam) processing, and TEM (Transmission Electron Microscope) and CD-SEM (Critical Dimension Scanning Electron Microscope) images measurement is proposed to standardize 3D-profile measurement through reference metrology. In this article, we apply the methodology to line profile measurements and roughness measurement of advanced FinFET (Fin-shaped Field-Effect Transistor) features. The FinFET features are horizontally sliced as a thin specimen by FIB micro sampling system. Horizontally images of the specimens are obtained then by a planar TEM. LWR is calculated from the edges positions on TEM images. Moreover, we already have demonstrated the novel on-wafer 3D-profile metrology as "FIB-to-CDSEM method" with FIB slope cut and CD-SEM measuring. Using the method, a few micrometers wide on a wafer is coated and cut by 45-degree slope using FIB tool. Then, the wafer is transferred to CD-SEM to measure the cross section image by top down CD-SEM measurement. We applied FIB-to-CDSEM method to a CMOS image sensor feature. The 45-degree slope cut surface is observed using AFM. The surface profile of slope cut surface and line profiles are analyzed for improving the accuracy of FIB-to-CDSEM method.

Developing Vs30 site-condition maps by combining observations with geologic and topographic constraints

USGS Publications Warehouse

Thompson, E.M.; Wald, D.J.

2012-01-01

Despite obvious limitations as a proxy for site amplification, the use of time-averaged shear-wave velocity over the top 30 m (VS30) remains widely practiced, most notably through its use as an explanatory variable in ground motion prediction equations (and thus hazard maps and ShakeMaps, among other applications). As such, we are developing an improved strategy for producing VS30 maps given the common observational constraints. Using the abundant VS30 measurements in Taiwan, we compare alternative mapping methods that combine topographic slope, surface geology, and spatial correlation structure. The different VS30 mapping algorithms are distinguished by the way that slope and geology are combined to define a spatial model of VS30. We consider the globally applicable slope-only model as a baseline to which we compare two methods of combining both slope and geology. For both hybrid approaches, we model spatial correlation structure of the residuals using the kriging-with-a-trend technique, which brings the map into closer agreement with the observations. Cross validation indicates that we can reduce the uncertainty of the VS30 map by up to 16% relative to the slope-only approach.

Design issue analysis for InAs nanowire tunnel FETs

NASA Astrophysics Data System (ADS)

Sylvia, Somaia S.; Khayer, M. Abul; Alam, Khairul; Lake, Roger K.

2011-10-01

InAs nanowire-tunnel eld eect transistors (NW-TFETs) are being considered for future, beyond-Si electronics. They oer the possibility of beating the ideal thermal limit to the inverse subthreshold slope of 60 mV/dec and thus promise reduced power operation. However, whether the tunneling can provide sucient on-current for high-speed operation is an open question. In this work, for a p-i-n device, we investigate the source doping level necessary to achieve a target on-current (1 A) while maintaining a high ION=IOFF ratio (1106) for a range of NW diameters (2 -8 nm). With a xed drain bias voltage and a maximum gate overdrive, we compare the performance in terms of the inverse subthreshold slope (SS) and ION=IOFF ratio as a function of NW- diameter and source doping. As expected, increasing the source doping level increases the current as a result of the reduced screening length and increased electric eld at source which narrows the tunnel barrier. However, since the degeneracy is also increasing, it moves the eective energy window for tunneling away from the barrier where it is the narrowest. This, in turn, tends to decrease the current for a given voltage which, along with the consideration of inverse SS and ION=IOFF ratio leads to an optimum choice of source doping.

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

Ward, W.F.; Kim, Y.T.; Molteni, A.

The ability of the angiotensin converting enzyme (ACE) inhibitor Captopril to modify radiation-induced pulmonary endothelial dysfunction was determined in male rats sacrificed 2 months after a single dose of 10-30 Gy of /sup 60/Co gamma rays to the right hemithorax. Half of each dose group consumed feed containing 0.12% w/w Captopril (60 mg/kg/day) continuously after irradiation, and half consumed control feed. Four markers of endothelial function were monitored: ACE activity, plasminogen activator (PLA) activity, and prostacyclin (PGI2) and thromboxane (TXA2) production. All data were plotted as dose-response curves, and subjected to linear regression analysis. The Captopril modifying effect was expressedmore » as the ratio of isoeffective doses at a common intermediate response (DRF), or as the ratio of the response curve slopes. Right lung ACE and PLA activity decreased linearly, and PGI2 and TXA2 production increased linearly with increasing radiation dose. Captopril exhibited DRF values of 1.4-2.1, and slope ratios of 1.4-5.1 for all four functional markers (p less than 0.05). Thus, the ACE inhibitor Captopril ameliorates radiation-induced pulmonary endothelial dysfunction in rats sacrificed 2 months postirradiation. Although the mechanism of Captopril action is not clear at present, these data suggest a novel application for this class of compounds as injury-modifying agents in irradiated lung.« less

Slope Estimation in Noisy Piecewise Linear Functions✩

PubMed Central

Ingle, Atul; Bucklew, James; Sethares, William; Varghese, Tomy

2014-01-01

This paper discusses the development of a slope estimation algorithm called MAPSlope for piecewise linear data that is corrupted by Gaussian noise. The number and locations of slope change points (also known as breakpoints) are assumed to be unknown a priori though it is assumed that the possible range of slope values lies within known bounds. A stochastic hidden Markov model that is general enough to encompass real world sources of piecewise linear data is used to model the transitions between slope values and the problem of slope estimation is addressed using a Bayesian maximum a posteriori approach. The set of possible slope values is discretized, enabling the design of a dynamic programming algorithm for posterior density maximization. Numerical simulations are used to justify choice of a reasonable number of quantization levels and also to analyze mean squared error performance of the proposed algorithm. An alternating maximization algorithm is proposed for estimation of unknown model parameters and a convergence result for the method is provided. Finally, results using data from political science, finance and medical imaging applications are presented to demonstrate the practical utility of this procedure. PMID:25419020

Coir geotextile for slope stabilization and cultivation - A case study in a highland region of Kerala, South India

NASA Astrophysics Data System (ADS)

Vishnudas, Subha; Savenije, Hubert H. G.; Van der Zaag, Pieter; Anil, K. R.

A sloping field is not only vulnerable to soil erosion it may also suffer from soil moisture deficiency. Farmers that cultivate on slopes everywhere face similar problems. Conservation technologies may reduce soil and nutrient losses, and thus enhance water holding capacity and soil fertility. But although these technologies promote sustainable crop production on steep slopes, the construction of physical structure such as bench terraces are often labour intensive and expensive to the farmers, since construction and maintenance require high investments. Here we studied the efficiency of coir geotextile with and without crop cultivation in reducing soil moisture deficiency on marginal slopes in Kerala, India. From the results it is evident that the slopes treated with geotextile and crops have the highest moisture retention capacity followed by geotextiles alone, and that the control plot has the lowest moisture retention capacity. As the poor and marginal farmers occupy the highland region, this method provides an economically viable option for income generation and food security along with slope stabilization.

Slope Estimation in Noisy Piecewise Linear Functions.

PubMed

Ingle, Atul; Bucklew, James; Sethares, William; Varghese, Tomy

2015-03-01

This paper discusses the development of a slope estimation algorithm called MAPSlope for piecewise linear data that is corrupted by Gaussian noise. The number and locations of slope change points (also known as breakpoints) are assumed to be unknown a priori though it is assumed that the possible range of slope values lies within known bounds. A stochastic hidden Markov model that is general enough to encompass real world sources of piecewise linear data is used to model the transitions between slope values and the problem of slope estimation is addressed using a Bayesian maximum a posteriori approach. The set of possible slope values is discretized, enabling the design of a dynamic programming algorithm for posterior density maximization. Numerical simulations are used to justify choice of a reasonable number of quantization levels and also to analyze mean squared error performance of the proposed algorithm. An alternating maximization algorithm is proposed for estimation of unknown model parameters and a convergence result for the method is provided. Finally, results using data from political science, finance and medical imaging applications are presented to demonstrate the practical utility of this procedure.

Research on a New Method of Estimating the Potential Depth of Slope Failure Using the Airborne Electromagnetic Survey

NASA Astrophysics Data System (ADS)

Seto, Shuji; Takahara, Teruyoshi; Kinoshita, Atsuhiko; Mizuno, Hideaki; Kawato, Katsushi; Okumura, Minoru; Kageura, Ryouta

2017-04-01

In Japan, at Ontake volcano in 1984 and Kurikoma volcano in 2008, parts of the volcanoes collapsed and large-scale sediment-related disasters occurred. These disasters were unrelated to volcanic eruption directly. We conducted the case studies by using the airborne electromagnetic surveys to investigate the slopes likely to induce landslides on such volcanoes. The airborne electromagnetic surveys are the effective exploration tool when we investigate in extreme environments that person can't enter and it's necessary to investigate with wide range by a short time. The surveys were conducted by using a helicopter carrying the survey instruments; this method of non-contact investigation acquires resistivity data by the electromagnetic induction. In Japan, the surveys were conducted of 15 active volcanoes where volcanic disasters could have serious social implications. These cases focused on the seeking for the possible slopes that landslides would occur. However, the depth of the slope failure was not evaluated. Therefore in the study, we proposed a new method to determine the potential depth of slope failure. First, we categorized the three characteristics as the cap rock type, the extended collapse type, and the landslide type on the basis of collapsed cases and paid attention to the slope of the cap rock type and also defined the collapse range based on the topography and geological properties. Second, we analyzed resistivity structure about collapsed cases with the differential filter and made clear that collapse occurred in the depth which resistivity suddenly changes. In other volcanoes, we could estimate failure depth by extracting the part which resistivity suddenly changes. In the study, we use the three volcanoes as the main cases, Hokkaido Komagatake, Asama Volcano, and Ontake volcano.

Comparison of Regression Analysis and Transfer Function in Estimating the Parameters of Central Pulse Waves from Brachial Pulse Wave.

PubMed

Chai, Rui; Xu, Li-Sheng; Yao, Yang; Hao, Li-Ling; Qi, Lin

2017-01-01

This study analyzed ascending branch slope (A_slope), dicrotic notch height (Hn), diastolic area (Ad) and systolic area (As) diastolic blood pressure (DBP), systolic blood pressure (SBP), pulse pressure (PP), subendocardial viability ratio (SEVR), waveform parameter (k), stroke volume (SV), cardiac output (CO), and peripheral resistance (RS) of central pulse wave invasively and non-invasively measured. Invasively measured parameters were compared with parameters measured from brachial pulse waves by regression model and transfer function model. Accuracy of parameters estimated by regression and transfer function model, was compared too. Findings showed that k value, central pulse wave and brachial pulse wave parameters invasively measured, correlated positively. Regression model parameters including A_slope, DBP, SEVR, and transfer function model parameters had good consistency with parameters invasively measured. They had same effect of consistency. SBP, PP, SV, and CO could be calculated through the regression model, but their accuracies were worse than that of transfer function model.

Gamma scintigraphic analysis of albumin flux in patients with acute respiratory distress syndrome

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

Sugerman, H.J.; Tatum, J.L.; Burke, T.S.

1984-06-01

Computerized gamma-scintigraphy provides a new method for the analysis of albumin flux in patients with pulmonary permeability edema. In this technique, 10 mCi of /sup 99/mTc -tagged human serum albumin is administered and lung:heart radioactivity ratios are determined. This ratio remains constant unless there is a leak of albumin, when a rising ratio with time, called the ''slope index'' (SI), is seen. Thirty-five scintigraphic studies were obtained in 28 patients by means of a portable computerized gamma-camera. Thirteen of these patients had clinical evidence of the acute respiratory distress syndrome (ARDS) and six had or were recovering from left ventricularmore » induced congestive heart failure (CHF). Five of the patients with CHF and pulmonary capillary wedge pressure (PCWP) below 30 mm Hg had normal scintigraphic studies. The patients with ARDS were found to have significantly higher SIs than patients who did not have, or had recovered from, ARDS. Positive SIs were present from 1 to 8 days following the apparent onset of ARDS in seven studies in five patients. Recovery of gas exchange was associated with a return to a normal SI in four patients. In conclusion, computerized gamma-scintigraphy was a sensitive, noninvasive tool for the detection of a pathologic increase in pulmonary protein flux. Positive scintigraphic findings were associated with significantly impaired gas exchange. The method documented that the leak of albumin in patients with ARDS may last for days but resolves with recovery.« less

Longitudinal Change of Self-Perceptions of Aging and Mortality

PubMed Central

2014-01-01

Objective. To understand the association between self-perceptions of aging (SPA) and mortality in late life. Method. The sample (n = 1,507) was drawn from the Australian Longitudinal Study of Aging (baseline age = 65–103 years). We used joint growth curve and survival models on 5 waves of data for a period of 16 years to investigate the random intercept and slope of SPA for predicting all-cause mortality. Results. The unadjusted model revealed that poor SPA at baseline, as well as decline in SPA, increased the risk of mortality (SPA intercept hazard ratio [HR] = 1.21, 95% confidence interval [CI] = 1.13, 1.31; SPA slope HR = 1.17, 95% CI = 1.02, 1.33). This relationship remained significant for the SPA intercept after adjusting for other risk factors including demographics, physical health, cognitive functioning, and well-being. Conclusion. These findings suggest that a single measurement of SPA in late life may be very informative of future long-term vulnerability to health decline and mortality. Furthermore, a dynamic measure of SPA may be indicative of adaptation to age-related changes. This supports a “self-fulfilling” hypothesis, whereby SPA is a lens through which age-related changes are interpreted, and these interpretations can affect future health and health behaviors. PMID:23419867

Donor Hemodynamics as a Predictor of Outcomes After Kidney Transplantation From Donors After Cardiac Death.

PubMed

Allen, M B; Billig, E; Reese, P P; Shults, J; Hasz, R; West, S; Abt, P L

2016-01-01

Donation after cardiac death is an important source of transplantable organs, but evidence suggests donor warm ischemia contributes to inferior outcomes. Attempts to predict recipient outcome using donor hemodynamic measurements have not yielded statistically significant results. We evaluated novel measures of donor hemodynamics as predictors of delayed graft function and graft failure in a cohort of 1050 kidneys from 566 donors. Hemodynamics were described using regression line slopes, areas under the curve, and time beyond thresholds for systolic blood pressure, oxygen saturation, and shock index (heart rate divided by systolic blood pressure). A logistic generalized estimation equation model showed that area under the curve for systolic blood pressure was predictive of delayed graft function (above median: odds ratio 1.42, 95% confidence interval [CI] 1.06-1.90). Multivariable Cox regression demonstrated that slope of oxygen saturation during the first 10 minutes after extubation was associated with graft failure (below median: hazard ratio 1.30, 95% CI 1.03-1.64), with 5-year graft survival of 70.0% (95%CI 64.5%-74.8%) for donors above the median versus 61.4% (95%CI 55.5%-66.7%) for those below the median. Among older donors, increased shock index slope was associated with increased hazard of graft failure. Validation of these findings is necessary to determine the utility of characterizing donor warm ischemia to predict recipient outcome. © Copyright 2015 The American Society of Transplantation and the American Society of Transplant Surgeons.

Magma migration at the onset of the 2012-13 Tolbachik eruption revealed by Seismic Amplitude Ratio Analysis

NASA Astrophysics Data System (ADS)

Caudron, Corentin; Taisne, Benoit; Kugaenko, Yulia; Saltykov, Vadim

2015-12-01

In contrast of the 1975-76 Tolbachik eruption, the 2012-13 Tolbachik eruption was not preceded by any striking change in seismic activity. By processing the Klyuchevskoy volcano group seismic data with the Seismic Amplitude Ratio Analysis (SARA) method, we gain insights into the dynamics of magma movement prior to this important eruption. A clear seismic migration within the seismic swarm, started 20 hours before the reported eruption onset (05:15 UTC, 26 November 2012). This migration proceeded in different phases and ended when eruptive tremor, corresponding to lava flows, was recorded (at 11:00 UTC, 27 November 2012). In order to get a first order approximation of the magma location, we compare the calculated seismic intensity ratios with the theoretical ones. As expected, the observations suggest that the seismicity migrated toward the eruption location. However, we explain the pre-eruptive observed ratios by a vertical migration under the northern slope of Plosky Tolbachik volcano followed by a lateral migration toward the eruptive vents. Another migration is also captured by this technique and coincides with a seismic swarm that started 16-20 km to the south of Plosky Tolbachik at 20:31 UTC on November 28 and lasted for more than 2 days. This seismic swarm is very similar to the seismicity preceding the 1975-76 Tolbachik eruption and can be considered as a possible aborted eruption.

Estimating stochastic noise using in situ measurements from a linear wavefront slope sensor.

PubMed

Bharmal, Nazim Ali; Reeves, Andrew P

2016-01-15

It is shown how the solenoidal component of noise from the measurements of a wavefront slope sensor can be utilized to estimate the total noise: specifically, the ensemble noise variance. It is well known that solenoidal noise is orthogonal to the reconstruction of the wavefront under conditions of low scintillation (absence of wavefront vortices). Therefore, it can be retrieved even with a nonzero slope signal present. By explicitly estimating the solenoidal noise from an ensemble of slopes, it can be retrieved for any wavefront sensor configuration. Furthermore, the ensemble variance is demonstrated to be related to the total noise variance via a straightforward relationship. This relationship is revealed via the method of the explicit estimation: it consists of a small, heuristic set of four constants that do not depend on the underlying statistics of the incoming wavefront. These constants seem to apply to all situations-data from a laboratory experiment as well as many configurations of numerical simulation-so the method is concluded to be generic.

Application of LiDAR Date to Assess the Landslide Susceptibility Map Using Weights of Evidence Method - AN Example from Podhale Region (southern Poland)

NASA Astrophysics Data System (ADS)

Kamiński, Mirosław

2016-06-01

Podhale is a region in southern Poland, which is the northernmost part of the Central Carpathian Mountains. It is characterized by the presence of a large number of landslides that threaten the local infrastructure. In an article presents application of LiDAR data and geostatistical methods to assess landslides susceptibility map. Landslide inventory map were performed using LiDAR data and field work. The Weights of Evidence method was applied to assess landslides susceptibility map. Used factors for modeling: slope gradient, slope aspect, elevation, drainage density, faults density, lithology and curvature. All maps were subdivided into different classes. Then were converted to grid format in the ArcGIS 10.0. The conditional independence test was carried out to determine factors that are conditionally independent of each other with landslides. As a result, chi-square test for further GIS analysis used only five factors: slope gradient, slope aspect, elevation, drainage density and lithology. The final prediction results, it is concluded that the susceptibility map gives useful information both on present instability of the area and its possible future evolution in agreement with the morphological evolution of the area.

[Soil infiltration of snowmelt water in the southern Gurbantunggut Desert, Xinjiang, China].

PubMed

Hu, Shun-jun; Chen, Yong-bao; Zhu, Hai

2015-04-01

Soil infiltration of snow-melt water is an important income item of water balance in arid desert. The soil water content in west slope, east slope and interdune of sand dune in the southern Gurbantunggut Desert was monitored before snowfall and after snow melting during the winters of 2012-2013 and 2013-2014. According to the principle of water balance, soil infiltration of snow-melt in the west slope, east slope, interdune and landscape scale was calculated, and compared with the results measured by cylinder method. The results showed that the soil moisture recharge from unfrozen layer of unsaturated soil to surface frozen soil was negligible because the soil moisture content before snowfall was lower, soil infiltration of snow-melt water was the main source of soil water of shallow soil, phreatic water did not evaporate during freezing period, and did not get recharge after the snow melting. Snowmelt water in the west slope, east slope, interdune and landscape scale were 20-43, 27-43, 32-45, 26-45 mm, respectively.

Assessment of radar altimetry correction slopes for marine gravity recovery: A case study of Jason-1 GM data

NASA Astrophysics Data System (ADS)

Zhang, Shengjun; Li, Jiancheng; Jin, Taoyong; Che, Defu

2018-04-01

Marine gravity anomaly derived from satellite altimetry can be computed using either sea surface height or sea surface slope measurements. Here we consider the slope method and evaluate the errors in the slope of the corrections supplied with the Jason-1 geodetic mission data. The slope corrections are divided into three groups based on whether they are small, comparable, or large with respect to the 1 microradian error in the current sea surface slope models. (1) The small and thus negligible corrections include dry tropospheric correction, inverted barometer correction, solid earth tide and geocentric pole tide. (2) The moderately important corrections include wet tropospheric correction, dual-frequency ionospheric correction and sea state bias. The radiometer measurements are more preferred than model values in the geophysical data records for constraining wet tropospheric effect owing to the highly variable water-vapor structure in atmosphere. The items of dual-frequency ionospheric correction and sea state bias should better not be directly added to range observations for obtaining sea surface slopes since their inherent errors may cause abnormal sea surface slopes and along-track smoothing with uniform distribution weight in certain width is an effective strategy for avoiding introducing extra noises. The slopes calculated from radiometer wet tropospheric corrections, and along-track smoothed dual-frequency ionospheric corrections, sea state bias are generally within ±0.5 microradians and no larger than 1 microradians. (3) Ocean tide has the largest influence on obtaining sea surface slopes while most of ocean tide slopes distribute within ±3 microradians. Larger ocean tide slopes mostly occur over marginal and island-surrounding seas, and extra tidal models with better precision or with extending process (e.g. Got-e) are strongly recommended for updating corrections in geophysical data records.

Mapping on Slope Seepage Problem using Electrical Resistivity Imaging (ERI)

NASA Astrophysics Data System (ADS)

Hazreek, Z. A. M.; Nizam, Z. M.; Aziman, M.; Dan, M. F. Md; Shaylinda, M. Z. N.; Faizal, T. B. M.; Aishah, M. A. N.; Ambak, K.; Rosli, S.; Rais, Y.; Ashraf, M. I. M.; Alel, M. N. A.

2018-04-01

The stability of slope may influenced by several factors such as its geomaterial properties, geometry and environmental factors. Problematic slope due to seepage phenomenon will influenced the slope strength thus promoting to its failure. In the past, slope seepage mapping suffer from several limitation due to cost, time and data coverage. Conventional engineering tools to detect or mapped the seepage on slope experienced those problems involving large and high elevation of slope design. As a result, this study introduced geophysical tools for slope seepage mapping based on electrical resistivity method. Two spread lines of electrical resistivity imaging were performed on the slope crest using ABEM SAS 4000 equipment. Data acquisition configuration was based on long and short arrangement, schlumberger array and 2.5 m of equal electrode spacing interval. Raw data obtained from data acquisition was analyzed using RES2DINV software. Both of the resistivity results show that the slope studied consists of three different anomalies representing top soil (200 – 1000 Ωm), perched water (10 – 100 Ωm) and hard/dry layer (> 200 Ωm). It was found that seepage problem on slope studied was derived from perched water zones with electrical resistivity value of 10 – 100 Ωm. Perched water zone has been detected at 6 m depth from the ground level with varying thickness at 5 m and over. Resistivity results have shown some good similarity output with reference to borehole data, geological map and site observation thus verified the resistivity results interpretation. Hence, this study has shown that the electrical resistivity imaging was applicable in slope seepage mapping which consider efficient in term of cost, time, data coverage and sustainability.

Dissolved inorganic carbon and total alkalinity of a Hawaiian fringing reef: chemical techniques for monitoring the effects of ocean acidification on coral reefs

NASA Astrophysics Data System (ADS)

Lantz, C. A.; Atkinson, M. J.; Winn, C. W.; Kahng, S. E.

2014-03-01

There is an interest in developing approaches to "ecosystem-based" management for coral reefs. One aspect of ecosystem performance is to monitor carbon metabolism of whole communities. In an effort to explore robust techniques to monitor the metabolism of fringing reefs, especially considering the possible effects of ocean acidification, a yearlong study of the carbonate chemistry of a nearshore fringing reef in Hawaii was conducted. Diurnal changes in seawater carbonate chemistry were measured once a week in an algal-dominated and a coral-dominated reef flat on the Waimanalo fringing reef, Hawaii, from April of 2010 until May of 2011. Calculated rates of gross primary production (GPP) and net community calcification ( G) were similar to previous estimates of community metabolism for other coral reefs (GPP 971 mmol C m-2 d-1; G 186 mmol CaCO3 m-2 d-1) and indicated that this reef was balanced in terms of organic metabolism, exhibited net calcification, and was a net source of CO2 to the atmosphere. Average slopes of total alkalinity versus dissolved inorganic carbon (TA-DIC slope) for the coral-dominated reef flat exhibited a greater calcification-to-net photosynthesis ratio than for the algal-dominated reef flat (coral slope vs. algal slope). Over the course of the time series, TA-DIC slopes remained significantly different between sites and were not correlated with diurnal averages in reef-water residence time or solar irradiance. These characteristic slopes for each reef flat reflect the relationship between carbon and carbonate community metabolism and can be used as a tool to monitor ecosystem function in response to ocean acidification.

Long-term weight-change slope, weight fluctuation and risk of type 2 diabetes mellitus in middle-aged Japanese men and women: findings of Aichi Workers' Cohort Study.

PubMed

Zhang, Y; Yatsuya, H; Li, Y; Chiang, C; Hirakawa, Y; Kawazoe, N; Tamakoshi, K; Toyoshima, H; Aoyama, A

2017-03-20

This study aims to investigate the association of long-term weight-change slopes, weight fluctuation and the risk of type 2 diabetes mellitus (T2DM) in middle-aged Japanese men and women. A total of 4234 participants of Aichi Workers' Cohort Study who were aged 35-66 years and free of diabetes in 2002 were followed through 2014. Past body weights at the ages of 20, 25, 30, 40 years, and 5 years before baseline as well as measured body weight at baseline were regressed on the ages. Slope and root-mean-square-error of the regression line were obtained and used to represent the weight changes and the weight fluctuation, respectively. The associations of the weight-change slopes and the weight fluctuation with incident T2DM were estimated by Cox proportional hazards models. During the median follow-up of 12.2 years, 400 incident cases of T2DM were documented. After adjustment for baseline overweight and other lifestyle covariates, the weight-change slopes were significantly associated with higher incidence of T2DM (hazard ratio (HR): 1.80, 95% confident interval (CI): 1.17-2.77 for men; and HR: 2.78, 95% CI: 1.07-7.23 for women), while the weight fluctuation was not (HR: 1.08, 95% CI: 1.00-1.18 for men and HR: 1.02, 95% CI: 0.84-1.25 for women). Regardless of the presence of overweight, the long-term weight-change slopes were significantly associated with the increased risk of T2DM; however, the weight fluctuation was not associated with the risk of T2DM in middle-aged Japanese men and women.

Stability Analysis of Landslide on the R1 Expressway by Limit Equilibrium and Finite Element Methods

NASA Astrophysics Data System (ADS)

Janták, Viktor

2017-12-01

The most difficult problem by designing the superior infrastructure is tracing the expressways and higways in an environment of Quaternary and Neogene complexes of finegrained cohesive and non-cohesive soils. At the last time the typical examples are stability problems on the R1 Nitra - Tekovské Nemce Expressway. The article is focused on the description of reasons of stability loss in the deep earth cut in the 79,000 km of expressway R1, the course of the landslide, slide correction and especially slope-stability assessment before and after the occurrence of slope failures by limit equilibrium and finite elements methods by comparing the behaviour of the slope in the various model situations.

Implications of flume slope on discharge estimates from 0.762-meter H flumes used in edge-of-field monitoring

USGS Publications Warehouse

Komiskey, Matthew J.; Stuntebeck, Todd D.; Cox, Amanda L.; Frame, Dennis R.

2013-01-01

The effects of longitudinal slope on the estimation of discharge in a 0.762-meter (m) (depth at flume entrance) H flume were tested under controlled conditions with slopes from −8 to +8 percent and discharges from 1.2 to 323 liters per second. Compared to the stage-discharge rating for a longitudinal flume slope of zero, computed discharges were negatively biased (maximum −31 percent) when the flume was sloped downward from the front (entrance) to the back (exit), and positively biased (maximum 44 percent) when the flume was sloped upward. Biases increased with greater flume slopes and with lower discharges. A linear empirical relation was developed to compute a corrected reference stage for a 0.762-m H flume using measured stage and flume slope. The reference stage was then used to determine a corrected discharge from the stage-discharge rating. A dimensionally homogeneous correction equation also was developed, which could theoretically be used for all standard H-flume sizes. Use of the corrected discharge computation method for a sloped H flume was determined to have errors ranging from −2.2 to 4.6 percent compared to the H-flume measured discharge at a level position. These results emphasize the importance of the measurement of and the correction for flume slope during an edge-of-field study if the most accurate discharge estimates are desired.

Shape-based retrieval of CNV regions in read coverage data.

PubMed

Hong, Sangkyun; Yoon, Jeehee; Hong, Dongwan; Lee, Unjoo; Kim, Baeksop; Park, Sanghyun

2014-01-01

This study proposes a novel copy number variation (CNV) detection method, CNV_shape, based on variations in the shape of the read coverage data which are obtained from millions of short reads aligned to a reference sequence. The proposed method carries out two transforms, mean shift transform and mean slope transform, to extract the shape of a CNV more precisely from real human data, which are vulnerable to experimental and biological noises. The mean shift transform is a procedure for gaining a preliminary estimation of the CNVs by statistically evaluating moving averages of given read coverage data. The mean slope transform extracts candidate CNVs by filtering out non-stationary sub-regions from each of the primary CNVs pre-estimated in the mean shift procedure. Each of the candidate CNVs is merged with neighbours depending on the merging score to be finally identified as a putative CNV, where the merging score is estimated by the ratio of the positions with non-zero values of the mean shift transform to the total length of the region including two neighbouring candidate CNVs and the interval between them. The proposed CNV detection method was validated experimentally with simulated data and real human data. The simulated data with coverage in the range of 1x to 10x were generated for various sampling sizes and p-values. Five individual human genomes were used as real human data. The results show that relatively small CNVs (> 1 kbp) can be detected from low coverage (> 1.7x) data. The results also reveal that, in contrast to conventional methods, performance improvement from 8.18 to 87.90% was achieved in CNV_shape. The outcomes suggest that the proposed method is very effective in reducing noises inherent in real data as well as in detecting CNVs of various sizes and types.

A new method to identify the foot of continental slope based on an integrated profile analysis

NASA Astrophysics Data System (ADS)

Wu, Ziyin; Li, Jiabiao; Li, Shoujun; Shang, Jihong; Jin, Xiaobin

2017-06-01

A new method is proposed to identify automatically the foot of the continental slope (FOS) based on the integrated analysis of topographic profiles. Based on the extremum points of the second derivative and the Douglas-Peucker algorithm, it simplifies the topographic profiles, then calculates the second derivative of the original profiles and the D-P profiles. Seven steps are proposed to simplify the original profiles. Meanwhile, multiple identification methods are proposed to determine the FOS points, including gradient, water depth and second derivative values of data points, as well as the concave and convex, continuity and segmentation of the topographic profiles. This method can comprehensively and intelligently analyze the topographic profiles and their derived slopes, second derivatives and D-P profiles, based on which, it is capable to analyze the essential properties of every single data point in the profile. Furthermore, it is proposed to remove the concave points of the curve and in addition, to implement six FOS judgment criteria.

A constrained Delaunay discretization method for adaptively meshing highly discontinuous geological media

NASA Astrophysics Data System (ADS)

Wang, Yang; Ma, Guowei; Ren, Feng; Li, Tuo

2017-12-01

A constrained Delaunay discretization method is developed to generate high-quality doubly adaptive meshes of highly discontinuous geological media. Complex features such as three-dimensional discrete fracture networks (DFNs), tunnels, shafts, slopes, boreholes, water curtains, and drainage systems are taken into account in the mesh generation. The constrained Delaunay triangulation method is used to create adaptive triangular elements on planar fractures. Persson's algorithm (Persson, 2005), based on an analogy between triangular elements and spring networks, is enriched to automatically discretize a planar fracture into mesh points with varying density and smooth-quality gradient. The triangulated planar fractures are treated as planar straight-line graphs (PSLGs) to construct piecewise-linear complex (PLC) for constrained Delaunay tetrahedralization. This guarantees the doubly adaptive characteristic of the resulted mesh: the mesh is adaptive not only along fractures but also in space. The quality of elements is compared with the results from an existing method. It is verified that the present method can generate smoother elements and a better distribution of element aspect ratios. Two numerical simulations are implemented to demonstrate that the present method can be applied to various simulations of complex geological media that contain a large number of discontinuities.

Development and Application of Fiber Bragg Grating Clinometer

NASA Astrophysics Data System (ADS)

Guo, Xin; Li, Wen; Wang, Wentao; Feng, Xiaoyu

2017-06-01

Using FBG (fiber bragg grating) technology in clinometers can solve the technological problem facing by wireless transmission devices like big data transfer volume and poor stability, which has been receiving more and more attention. This paper discusses a new clinometer that is designed and transformed based on upgrading current clinometers, installing fiber grating strain gauges and fiber thermometers, and carrying out studies on such aspects as equipment upgrading, on-site setting, and data acquisition and analysis. In addition, it brings up the method of calculating displacement change based on wavelength change; this method is used in safety monitoring of the right side slope of Longyong Expressway ZK56+860 ~ ZK56+940 Section. Data shows that the device is operating well with a higher accuracy, and the slope is currently in a steady state. The equipment improvement and the method together provide reference data for safety analysis of the side slope.

Development of an reliable analytical method for synergistic extractive spectrophotometric determination of cobalt(II) from alloys and nano composite samples by using chromogenic chelating ligand

NASA Astrophysics Data System (ADS)

Kamble, Ganesh S.; Ghare, Anita A.; Kolekar, Sanjay S.; Han, Sung H.; Anuse, Mansing A.

2011-12-01

A synergistic simple and selective spectrophotometric method was developed for the determination of cobalt(II) with 1-(2',4'-dinitro aminophenyl)-4,4,6-trimethyl-1,4-dihydropyrimidine-2-thiol [2',4'-dinitro APTPT] as a chromogenic reagent. The proposed method has been described on the basis of synergistic effective extraction of cobalt(II) in presence of pyridine at pH range 9.5-10.2, showed orange-red coloured ternary complex having molar ratio 1:2:2 (M:L:Py). The equilibrium time is 10 min for extraction of cobalt(III) from organic phase. The absorbance of coloured organic layer in chloroform is measured spectrophotometrically at 490 nm against reagent blank. The Beer's law was obeyed in the concentration range 2.5-15 μg mL -1 of cobalt(II) and optimum concentration range was 5-12.5 μg mL -1 of cobalt(II) and it was evaluated from Ringbom's plot. The molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT-pyridine complex in chloroform are 1.109 × 10 3 L mol -1 cm -1 and 0.053 μg cm -2, respectively while molar absorptivity and Sandell's sensitivity of cobalt(II)-2',4'-dinitro APTPT complex in chloroform are 6.22 × 10 2 L mol -1 cm -1 and 0.096 μg cm -2, respectively. The composition of cobalt(II)-2',4'-dinitro APTPT-pyridine complex (1:2:2) was established by slope ratio method, mole ratio method and Job's method of continuous variation. The ternary complex was stable for more than 48 h. The interfering effects of various cations and anions were also studied, and use of suitable masking agents enhances the selectivity of the method. The method is successfully applied for the determination of cobalt(II) in binary, synthetic mixtures and real samples. A repetition of the method was checked by finding relative standard deviation (R.S.D.) for n = 5 which was 0.15%. The reliability of the method is confirmed by comparison of experimental results with atomic absorption spectrophotometer.

Changes in denudation rates and erosion processes in the transition from a low-relief, arid orogen interior to a high-relief, humid mountain-front setting, Toro Basin, southern Central Andes

NASA Astrophysics Data System (ADS)

Tofelde, S.; Düsing, W.; Schildgen, T. F.; Wittmann, H.; Alonso, R. N.; Strecker, M. R.

2017-12-01

In tectonically active mountain belts positive correlations between denudation rates and hillslope angles are commonly observed, supporting the notion that landscape morphology may reflect tectonic forcing. However, this relationship generally breaks down at 30°, when hillslopes reach threshold angles. Beyond this threshold, faster denudation may occur by an increased contribution from mass-wasting processes. We test this idea in the 4000 km2 Toro Basin, a fault-bounded basin in the Eastern Cordillera of the southern Central Andes. This N-S oriented basin is located between low-relief, arid conditions in the orogen interior (N) and a high-relief, humid setting at its fluvial outlet (S). We measured in-situ produced 10Be concentration in fluvial sediments, which can be converted into basin-mean denudation rates, assuming a spatially uniform contribution of sediment from the catchment. However, in landslide-influenced areas, this assumption is often violated. Previous studies have suggested that clast-size material is mainly contributed by mass-wasting processes, whereas sand is derived from a broad range of erosional processes. Hence, a combination of clast and sand samples can reveal information about the basin-mean denudation rate as well as the contribution of mass-wasting processes. We sampled 13 pebble (1-3 cm) and sand (250-500 µm) pairs across the basin. The sand-derived denudation rates increase from N to S, ranging from 0.010 mm/yr to 1.337 mm/yr, and reveal a non-linear positive correlation with median basin slope. The clast/sand ratios also increase from N to S, indicating amplified mass-wasting processes with increasing slopes. To test if our ratios represent a real shift in erosional processes, we mapped different erosional processes in the study area (e.g. deep-seated landslides, scree erosion,.., diffusion). We assume that today's distribution of processes has not changed over the integration time of 10Be derived denudation rates. This detailed erosion inventory indicates a shift in the dominant erosional processes with increasing clast/sand ratios and thus with increasing slopes. We provide empirical data supporting the hypothesis that higher denudation rates can be achieved by an increased contribution of mass-wasting processes after threshold slopes have been reached.

Assessing slope stability in unplanned settlements in developing countries.

PubMed

Anderson, Malcolm G; Holcombe, Liz; Renaud, Jean-Philippe

2007-10-01

Unplanned housing in developing countries is often located on steep slopes. Frequently no building code is enforced for such housing and mains water is provided with no drainage provision. Both of these factors can be particularly significant in terms of landslide risk if, as is so often the case, such slopes lack any planned drainage provision. There is thus a need to develop a model that facilitates the assessment of slope stability in an holistic context, incorporating a wide range of factors (including surface cover, soil water topographic convergence, slope loading and point source water leakage) in order that appropriate advice can be given as to the general controls on slope stability in such circumstances. This paper outlines a model configured for this specific purpose and describes an application to a site in St. Lucia, West Indies, where there is active slope movement in an unplanned housing development on relatively steep topography. The model findings are in accord with the nature of the current failure at the site, provide guidance as to the significance of slope drainage and correspond to inferences drawn from an application of resistance envelope methods to the site. In being able to scenario test a uniquely wide range of combinations of factors, the model structure is shown to be highly valuable in assessing dominant slope stability process controls in such complex environments.

Evaluation of the impact of matrix effect on quantification of pesticides in foods by gas chromatography-mass spectrometry using isotope-labeled internal standards.

PubMed

Yarita, Takashi; Aoyagi, Yoshie; Otake, Takamitsu

2015-05-29

The impact of the matrix effect in GC-MS quantification of pesticides in food using the corresponding isotope-labeled internal standards was evaluated. A spike-and-recovery study of nine target pesticides was first conducted using paste samples of corn, green soybean, carrot, and pumpkin. The observed analytical values using isotope-labeled internal standards were more accurate for most target pesticides than that obtained using the external calibration method, but were still biased from the spiked concentrations when a matrix-free calibration solution was used for calibration. The respective calibration curves for each target pesticide were also prepared using matrix-free calibration solutions and matrix-matched calibration solutions with blank soybean extract. The intensity ratio of the peaks of most target pesticides to that of the corresponding isotope-labeled internal standards was influenced by the presence of the matrix in the calibration solution; therefore, the observed slope varied. The ratio was also influenced by the type of injection method (splitless or on-column). These results indicated that matrix-matching of the calibration solution is required for very accurate quantification, even if isotope-labeled internal standards were used for calibration. Copyright © 2015 Elsevier B.V. All rights reserved.

[Mechanisms of grass in slope erosion control in Loess sandy soil region of Northwest China].

PubMed

Zhao, Chun-Hong; Gao, Jian-En; Xu, Zhen

2013-01-01

By adopting the method of simulated precipitation and from the viewpoint of slope hydrodynamics, in combining with the analysis of soil resistance to erosion, a quantitative study was made on the mechanisms of grass in controlling the slope erosion in the cross area of wind-water erosion in Loess Plateau of Northwest China under different combinations of rainfall intensity and slope gradient, aimed to provide basis to reveal the mechanisms of vegetation in controlling soil erosion and to select appropriate vegetation for the soil and water conservation in Loess Plateau. The grass Astragalus adsurgens with the coverage about 40% could effectively control the slope erosion. This grass had an efficiency of more than 70% in reducing sediment, and the grass root had a greater effect than grass canopy. On bare slope and on the slopes with the grass plant or only the grass root playing effect, there existed a functional relation between the flow velocity on the slopes and the rainfall intensity and slope gradient (V = DJ(0.33 i 0.5), where V is flow velocity, D is the comprehensive coefficient which varies with different underlying surfaces, i is rainfall intensity, and J is slope gradient). Both the grass root and the grass canopy could markedly decrease the flow velocity on the slopes, and increase the slope resistance, but the effect of grass root in decreasing flow velocity was greater while the effect in increasing resistance was smaller than that of grass canopy. The effect of grass root in increasing slope resistance was mainly achieved by increasing the sediment grain resistance, while the effect of canopy was mainly achieved by increasing the slope form resistance and wave resistance. The evaluation of the soil resistance to erosion by using a conceptual model of sediment generation by overland flow indicated that the critical shear stress value of bare slope and of the slopes with the grass plant or only the grass root playing effect was 0.533, 1.672 and 0.925 Pa, respectively.

Field instrumentation, monitoring of drilled shafts for landslide stabilization and development of pertinent design method : executive summary report.

DOT National Transportation Integrated Search

2010-11-01

The use of a row of spaced drilled shafts to stabilize unstable slopes along the highways offers many advantages compared to other slope stabilization techniques. Some of these advantages may include: (1) various construction techniques are available...

Revised tephra volumes for Cascade Range volcanoes

NASA Astrophysics Data System (ADS)

Nathenson, Manuel

2017-07-01

Isopach maps from tephra eruptions from Mount St. Helens were reported in Carey et al. (1995) and for tephra eruptions from Glacier Peak in Gardner et al. (1998). For exponential thinning, the isopach data only define a single slope on a log thickness versus square root of area plot. Carey et al. (1995) proposed a model that was used to estimate a second slope, and volumes were presented in both studies using this model. A study by Sulpizio (2005) for estimating the second slope and square root of area where the lines intersect involves a systematic analysis of many eruptions to provide correlation equations. The purpose of this paper is to recalculate the volumes of Cascades eruptions and compare results from the two methods. In order to gain some perspective on the methods for estimating the second slope, we use data for thickness versus distance beyond the last isopach that are available for some of the larger eruptions in the Cascades. The thickness versus square root of area method is extended to thickness versus distance by developing an approximate relation between the two assuming elliptical isopachs with the source at one of the foci. Based on the comparisons made between the Carey et al. (1995) and Sulpizio (2005) methods, it is felt that the later method provides a better estimate of the second slope. For Mount St. Helens, the estimates of total volume using the Sulpizio (2005) method are generally smaller than those using the Carey et al. (1995) method. For the volume estimates of Carey et al. (1995), the volume of the May 18, 1980, eruption of Mount St. Helens is smaller than six of the eight previous eruptions. With the new volumes using the Sulpizio (2005) method, the 1980 eruption is smaller in volume than the upper end of the range for only three of the layers (Wn, Ye, and Yn) and is the same size as layer We. Thus the 1980 eruption becomes representative of the mid-range of volumes rather than being in the lower range.

Revised tephra volumes for Cascade Range volcanoes

USGS Publications Warehouse

Nathenson, Manuel

2017-01-01

Isopach maps from tephra eruptions from Mount St. Helens were reported in Carey et al. (1995) and for tephra eruptions from Glacier Peak in Gardner et al. (1998). For exponential thinning, the isopach data only define a single slope on a log thickness versus square root of area plot. Carey et al. (1995) proposed a model that was used to estimate a second slope, and volumes were presented in both studies using this model. A study by Sulpizio (2005) for estimating the second slope and square root of area where the lines intersect involves a systematic analysis of many eruptions to provide correlation equations. The purpose of this paper is to recalculate the volumes of Cascades eruptions and compare results from the two methods. In order to gain some perspective on the methods for estimating the second slope, we use data for thickness versus distance beyond the last isopach that are available for some of the larger eruptions in the Cascades. The thickness versus square root of area method is extended to thickness versus distance by developing an approximate relation between the two assuming elliptical isopachs with the source at one of the foci. Based on the comparisons made between the Carey et al. (1995) and Sulpizio (2005) methods, it is felt that the later method provides a better estimate of the second slope. For Mount St. Helens, the estimates of total volume using the Sulpizio (2005) method are generally smaller than those using the Carey et al. (1995) method. For the volume estimates of Carey et al. (1995), the volume of the May 18, 1980, eruption of Mount St. Helens is smaller than six of the eight previous eruptions. With the new volumes using the Sulpizio (2005) method, the 1980 eruption is smaller in volume than the upper end of the range for only three of the layers (Wn, Ye, and Yn) and is the same size as layer We. Thus the 1980 eruption becomes representative of the mid-range of volumes rather than being in the lower range.

Slope Root biomechanical properties and their contribution to soil reinforcement in the Landslide-prone region, the Bailong River Basin

NASA Astrophysics Data System (ADS)

Wang, X.; Hong, M.; Huang, Z.; Zhao, Y.; Zhang, Y.

2016-12-01

The presence of vegetation increases soil burden stability along slopes and therefore reduces soil erosion. The contribution of the vegetation is due to the root's mechanical (reinforcing soil shear resistance) controls on superficial landslide. The study focused on the biotechnical characteristics of the root system of commonly grown shrub species in the Bailong River Basin, one of the most serious geo-hazards regions in China. The aim of this paper is to increase the understanding on slope root biomechanical properties of different shrubs species and their contribution to soil reinforcement. Field investigations were carried out to estimate the root density distribution with depth (root area ratio). Laboratory tests were conducted to measure the root tensile breaking force and the root tensile strength. Root tensile strength measurements were carried out on single root specimens and root area ratio was estimated analyzing the whole root system. The direct shear tests were used to quantify the soil mechanical reinforcement. The improvement of soil mechanical properties obtained by the presence of shrubs was estimated using two different models(the Fibrt Bundle Model and the Finite Element Model). The results indicates that the soil-root system shear strength of Robinia pseudoacacia Linn (L.), Populus simonii (L.), Olea europaea (L.), and Zanthoxylum bungeanum (L.) increment ranged from 62.4 to 26.3 kPa and its effect on the slope stability was significantly different. Robinia pseudoacacia Linn (L.) roots presented the highest tensile strength and soil reinforcement values. Similarly at each considered depth Robinia pseudoacacia Linn (L.) showed that the highest soil reinforcement effect (1461N) while Olea europaea (L.) presented the lowest soil reinforcement effect (1329N). The finite element model shows that the FoS of Zanthoxylum bungeanum (L.) is the largest of these plants when considering root additional cohesion. This research can provide a basic theory of afforestation mode in spatial distribution and hence control shallow landslide.

Direct observations of the Antarctic Slope Current transport at 113°E

NASA Astrophysics Data System (ADS)

Peña-Molino, B.; McCartney, M. S.; Rintoul, S. R.

2016-10-01

The Antarctic Slope Current (ASC), defined here as the region of westward flow along the continental slope off Antarctica, forms the southern limb of the subpolar gyres. It regulates the exchange of water across the shelf break and provides a path for interbasin westward transport. Despite its significance, the ASC remains largely unobserved around most of the Antarctic continent. Here we present direct velocity observations from a 17 month current meter moored array deployed across the continental slope between the 1000 and the 4200 m isobaths, in the southeastern Indian Ocean near 113°E. The observed time-mean flow consists of a surface-intensified jet associated with the Antarctic Slope Front (ASF) and a broader bottom-intensified westward flow that extends out to approximately the 4000 m isobath and is strongest along the upper slope. The time-mean transport of the ASC is -29.2 Sv. Fluctuations in the transport are large, typically exceeding the mean by a factor of 2. They are mainly due to changes in the northward extent of the current over the lower slope. However, seasonal changes in the wind also drive variations in the transport of the ASF and the flow in the upper slope. Both mean and variability are largely barotropic, thus invisible to traditional geostrophic methods.

Analysis of Local Slopes at the InSight Landing Site on Mars

NASA Astrophysics Data System (ADS)

Fergason, R. L.; Kirk, R. L.; Cushing, G.; Galuszka, D. M.; Golombek, M. P.; Hare, T. M.; Howington-Kraus, E.; Kipp, D. M.; Redding, B. L.

2017-10-01

To evaluate the topography of the surface within the InSight candidate landing ellipses, we generated Digital Terrain Models (DTMs) at lander scales and those appropriate for entry, descent, and landing simulations, along with orthoimages of both images in each stereopair, and adirectional slope images. These products were used to assess the distribution of slopes for each candidate ellipse and terrain type in the landing site region, paying particular attention to how these slopes impact InSight landing and engineering safety, and results are reported here. Overall, this region has extremely low slopes at 1-meter baseline scales and meets the safety constraints of the InSight lander. The majority of the landing ellipse has a mean slope at 1-meter baselines of 3.2°. In addition, a mosaic of HRSC, CTX, and HiRISE DTMs within the final landing ellipse (ellipse 9) was generated to support entry, descent, and landing simulations and evaluations. Several methods were tested to generate this mosaic and the NASA Ames Stereo Pipeline program dem_mosaic produced the best results. For the HRSC-CTX-HiRISE DTM mosaic, more than 99 % of the mosaic has slopes less than 15°, and the introduction of artificially high slopes along image seams was minimized.

Analysis of local slopes at the InSight landing site on Mars

USGS Publications Warehouse

Fergason, Robin L.; Kirk, Randolph L.; Cushing, Glen; Galuszka, Donna M.; Golombek, Matthew P.; Hare, Trent M.; Howington-Kraus, Elpitha; Kipp, Devin M; Redding, Bonnie L.

2017-01-01

To evaluate the topography of the surface within the InSight candidate landing ellipses, we generated Digital Terrain Models (DTMs) at lander scales and those appropriate for entry, descent, and landing simulations, along with orthoimages of both images in each stereopair, and adirectional slope images. These products were used to assess the distribution of slopes for each candidate ellipse and terrain type in the landing site region, paying particular attention to how these slopes impact InSight landing and engineering safety, and results are reported here. Overall, this region has extremely low slopes at 1-meter baseline scales and meets the safety constraints of the InSight lander. The majority of the landing ellipse has a mean slope at 1-meter baselines of 3.2°. In addition, a mosaic of HRSC, CTX, and HiRISE DTMs within the final landing ellipse (ellipse 9) was generated to support entry, descent, and landing simulations and evaluations. Several methods were tested to generate this mosaic and the NASA Ames Stereo Pipeline program dem_mosaic produced the best results. For the HRSC-CTX-HiRISE DTM mosaic, more than 99 % of the mosaic has slopes less than 15°, and the introduction of artificially high slopes along image seams was minimized.

The modelling influence of water content to mechanical parameter of soil in analysis of slope stability

NASA Astrophysics Data System (ADS)

Gusman, M.; Nazki, A.; Putra, R. R.

2018-04-01

One of the parameters in slope stability analysis is the shear strength of the soil. Changes in soil shear strength characteristics lead to a decrease in safety factors on the slopes. This study aims to see the effect of increased moisture content on soil mechanical parameters. The case study study was conducted on the slopes of Sitinjau Lauik Kota Padang. The research method was done by laboratory analysis and simple liniear regression analysis and multiple. Based on the test soil results show that the increase in soil water content causes a decrease in cohesion values and internal shear angle. The relationship of moisture content to cohesion is described in equation Y = 55.713-0,6X with R2 = 0.842. While the relationship of water content to shear angle in soil is described in the equation Y = 38.878-0.258X with R2 = 0.915. From several simulations of soil water level improvement, calculation of safety factor (SF) of slope. The calculation results show that the increase of groundwater content is very significant affect the safety factor (SF) slope. SF slope values are in safe condition when moisture content is 50% and when it reaches maximum water content 73.74% slope safety factor value potentially for landslide.

Solution algorithm of dwell time in slope-based figuring model

NASA Astrophysics Data System (ADS)

Li, Yong; Zhou, Lin

2017-10-01

Surface slope profile is commonly used to evaluate X-ray reflective optics, which is used in synchrotron radiation beam. Moreover, the measurement result of measuring instrument for X-ray reflective optics is usually the surface slope profile rather than the surface height profile. To avoid the conversion error, the slope-based figuring model is introduced introduced by processing the X-ray reflective optics based on surface height-based model. However, the pulse iteration method, which can quickly obtain the dell time solution of the traditional height-based figuring model, is not applied to the slope-based figuring model because property of the slope removal function have both positive and negative values and complex asymmetric structure. To overcome this problem, we established the optimal mathematical model for the dwell time solution, By introducing the upper and lower limits of the dwell time and the time gradient constraint. Then we used the constrained least squares algorithm to solve the dwell time in slope-based figuring model. To validate the proposed algorithm, simulations and experiments are conducted. A flat mirror with effective aperture of 80 mm is polished on the ion beam machine. After iterative polishing three times, the surface slope profile error of the workpiece is converged from RMS 5.65 μrad to RMS 1.12 μrad.

[Estimation of spur dike-affected fish habitat area].

PubMed

Ray-Shyan, Wu; Yan-Ru, Chen; Yi-Liang, Ge

2012-04-01

Based on the HEC-RAS and River 2D modes, and taking 5% change rate of weighted usable area (WUA) as the threshold to define the spur dike- affected area of target fish species Acrossocheilus paradoxus in Fazi River in Taiwan, this paper studied the affected area of the fish habitat by spur dike, and, in combining with the references about the installations of spur dikes in Taiwan in recent 10 years, analyzed the relative importance of related affecting factors such as dike height, dike length (water block rate), average slope gradient of river way, single or double spur dike, and flow discharge. In spite of the length of the dike, the affected area in downstream was farther, and was about 2-6 times as large as that in upstream. The ratio of the affected area in downstream / upstream decreased with increasing slope gradient, but increased with increasing dike length and flow discharge. When the discharge was approximate to 10 years return periods, the ratio of the affected area would be close to a constant of 2. Building double spur dike would produce a better WUA than building single spur dike.

Push Force Analysis of Anchor Block of the Oil and Gas Pipeline in a Single-Slope Tunnel Based on the Energy Balance Method

PubMed Central

Yan, Yifei; Zhang, Lisong; Yan, Xiangzhen

2016-01-01

In this paper, a single-slope tunnel pipeline was analysed considering the effects of vertical earth pressure, horizontal soil pressure, inner pressure, thermal expansion force and pipeline—soil friction. The concept of stagnation point for the pipeline was proposed. Considering the deformation compatibility condition of the pipeline elbow, the push force of anchor blocks of a single-slope tunnel pipeline was derived based on an energy method. Then, the theoretical formula for this force is thus generated. Using the analytical equation, the push force of the anchor block of an X80 large-diameter pipeline from the West—East Gas Transmission Project was determined. Meanwhile, to verify the results of the analytical method, and the finite element method, four categories of finite element codes were introduced to calculate the push force, including CAESARII, ANSYS, AutoPIPE and ALGOR. The results show that the analytical results agree well with the numerical results, and the maximum relative error is only 4.1%. Therefore, the results obtained with the analytical method can satisfy engineering requirements. PMID:26963097

Automated detection of ice cliffs within supraglacial debris cover

NASA Astrophysics Data System (ADS)

Herreid, Sam; Pellicciotti, Francesca

2018-05-01

Ice cliffs within a supraglacial debris cover have been identified as a source for high ablation relative to the surrounding debris-covered area. Due to their small relative size and steep orientation, ice cliffs are difficult to detect using nadir-looking space borne sensors. The method presented here uses surface slopes calculated from digital elevation model (DEM) data to map ice cliff geometry and produce an ice cliff probability map. Surface slope thresholds, which can be sensitive to geographic location and/or data quality, are selected automatically. The method also attempts to include area at the (often narrowing) ends of ice cliffs which could otherwise be neglected due to signal saturation in surface slope data. The method was calibrated in the eastern Alaska Range, Alaska, USA, against a control ice cliff dataset derived from high-resolution visible and thermal data. Using the same input parameter set that performed best in Alaska, the method was tested against ice cliffs manually mapped in the Khumbu Himal, Nepal. Our results suggest the method can accommodate different glaciological settings and different DEM data sources without a data intensive (high-resolution, multi-data source) recalibration.

An Improved Experimental Method for Simulating Erosion Processes by Concentrated Channel Flow

PubMed Central

Chen, Xiao-Yan; Zhao, Yu; Mo, Bin; Mi, Hong-Xing

2014-01-01

Rill erosion is an important process that occurs on hill slopes, including sloped farmland. Laboratory simulations have been vital to understanding rill erosion. Previous experiments obtained sediment yields using rills of various lengths to get the sedimentation process, which disrupted the continuity of the rill erosion process and was time-consuming. In this study, an improved experimental method was used to measure the rill erosion processes by concentrated channel flow. By using this method, a laboratory platform, 12 m long and 3 m wide, was used to construct rills of 0.1 m wide and 12 m long for experiments under five slope gradients (5, 10, 15, 20, and 25 degrees) and three flow rates (2, 4, and 8 L min−1). Sediment laden water was simultaneously sampled along the rill at locations 0.5 m, 1 m, 2 m, 3 m, 4 m, 5 m, 6 m, 7 m, 8 m, 10 m, and 12 m from the water inlet to determine the sediment concentration distribution. The rill erosion process measured by the method used in this study and that by previous experimental methods are approximately the same. The experimental data indicated that sediment concentrations increase with slope gradient and flow rate, which highlights the hydraulic impact on rill erosion. Sediment concentration increased rapidly at the initial section of the rill, and the rate of increase in sediment concentration reduced with the rill length. Overall, both experimental methods are feasible and applicable. However, the method proposed in this study is more efficient and easier to operate. This improved method will be useful in related research. PMID:24949621

A model study of sediment transport across the shelf break

NASA Astrophysics Data System (ADS)

Marchal, Olivier

2017-04-01

A variety of dynamical processes can contribute to the transport of material (e.g., particulate matter) across the shelf break - the region separating the continental shelf from the continental slope. Among these processes are (i) the reflection of internal waves on the outer shelf and upper slope, and (ii) the instability of hydrographic fronts, roughly aligned with isobaths, that are often present at the shelf break. On the one hand, internal waves reflecting on a sloping boundary can produce bottom shear stresses that are large enough to resuspend non-cohesive sediments into the water column. On the other hand, eddies shed from unstable shelf break fronts can incorporate into their core particle-rich waters from the outer shelf and upper slope, and transport these waters offshore. Here we present numerical experiments with a three-dimensional numerical model of ocean circulation and sediment transport, which illustrate the joint effect of internal waves and eddies on sediment transport across the shelf break. The model is based on the primitive equations and terrain-following coordinates. The model domain is square and idealized, comprising a flat continental shelf, a constant continental slope, and a flat abyssal basin. The model grid has O(1 km) horizontal resolution, so that (sub)mesoscale eddies observed in the vicinity of shelf breaks, such as south of New England, can be represented in detail. Internal waves are excited through the specification of a periodic variation in the across-slope component of velocity at the offshore boundary of the domain, and eddies are generated from the baroclinic instability of a shelf break jet that is initially in strict thermal wind balance. Numerical experiments are conducted that are characterized by (i) different slopes of internal wave characteristics relative to the continental slope, representing sub-critical, critical, and super-critical regimes, and (ii) different values for the dimensionless ratios that emerge from the linear stability analysis of shelf break fronts. Emphasis is placed on the physical conditions that are conducive to the formation and maintenance of bottom and intermediate nepheloid layers - the particle-rich layers that are often observed near oceanic margins in the traces of optical instruments.

Settling Velocity Specific SOC Distribution along Hillslopes - A field investigation in Denmark

NASA Astrophysics Data System (ADS)

Kuhn, N. J.; Hu, Y.

2015-12-01

The net effects of soil erosion by water, as a sink or source of atmospheric CO2, are decisively affected by the spatial re-distribution and stability of eroded soil organic carbon (SOC). The deposition position of eroded SOC, into terrestrial or aquatic systems, is actually decided by the transport distances of soil fractions where the SOC is stored. In theory, the transport distances of aggregated soil fractions are related to their settling velocities under given layer conditions. Yet, little field investigation has been conducted to examine the actual movement of eroded soil fractions along hillslopes, let alone the re-distribution pattern of functional SOC fractions. Eroding sandy soils and sediment were sampled after a series of rainfall events from different topographic positions along a slope on a freshly seeded cropland in Jutland, Denmark. All the soil samples from difference topographic positions along the slope were fractionated into five settling classes using a settling tube apparatus. The SOC content, 13C signature, and C:N ratios of all settling fractions were measured. Our results show that: 1) the spatial distribution of soil settling classes along the slope clearly shows a coarsening effect at the deposition area immediately below the eroding slope, followed by a fining trend on the deposition area at the slope tail. This proves the validity of the conceptual model in Starr et al. 2000 to predict SOC redistribution patterns along eroding hillslopes. 2) The isotopically enriched 13C on the slope back suggests greater decomposition rates possibly experienced by eroded SOC during transport, while the pronounced respiration rates at the slope tail indicate a great potential of CO2 emissions after deposition. Overall, our results illustrate that immediate deposition of fast settling soil fractions, and the thus induced preferential deposition of SOC at foot slope and potential CO2 emissions during transport, must be appropriately accounted for in current soil carbon balances. To achieve this, a SOC erodibility parameter based on the actual settling velocity distribution of eroded fractions (aggregated or not aggregated) is urgently needed to better parameterize soil erosion models with respect to SOC spatial redistribution.

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

Sitler, Steven J.; Raja, Krishnan S.; Charit, Indrajit

Spark plasma sintered transition metal diborides such as HfB 2, ZrB 2 and their solid solutions were investigated as electrode materials for electrochemical hydrogen evolutions reactions (HER) in 1 M H 2SO 4 and 1 M NaOH electrolytes. HfB 2 and ZrB 2 formed complete solid solutions when mixed in 1:1, 1:4, and 4:1 ratios and they were stable in both electrolytes. The HER kinetics of the diborides were slower in the basic solution than in the acidic solutions. The Tafel slopes in 1 M H 2SO 4 were in the range of 0.15 - 0.18 V/decade except for puremore » HfB 2 which showed a Tafel slope of 0.38 V/decade. In 1 M NaOH the Tafel slopes were in the range of 0.12 - 0.27 V/decade. The composition of Hf xZr 1-xB 2 solid solutions with x = 0.2 - 0.8, influenced the exchange current densities, overpotentials and Tafel slopes of the HER. As a result, the EIS data were fitted with a porous film equivalent circuit model in order to better understand the HER behavior. In addition, modeling calculations, using density functional theory approach, were carried out to estimate the density of states and band structure of the boride solid solutions.« less

Quantifying statistical relationships between commonly used in vitro models for estimating lead bioaccessibility.

PubMed

Yan, Kaihong; Dong, Zhaomin; Liu, Yanju; Naidu, Ravi

2016-04-01

Bioaccessibility to assess potential risks resulting from exposure to Pb-contaminated soils is commonly estimated using various in vitro methods. However, existing in vitro methods yield different results depending on the composition of the extractant as well as the contaminated soils. For this reason, the relationships between the five commonly used in vitro methods, the Relative Bioavailability Leaching Procedure (RBALP), the unified BioAccessibility Research Group Europe (BARGE) method (UBM), the Solubility Bioaccessibility Research Consortium assay (SBRC), a Physiologically Based Extraction Test (PBET), and the in vitro Digestion Model (RIVM) were quantified statistically using 10 soils from long-term Pb-contaminated mining and smelter sites located in Western Australia and South Australia. For all 10 soils, the measured Pb bioaccessibility regarding all in vitro methods varied from 1.9 to 106% for gastric phase, which is higher than that for intestinal phase: 0.2 ∼ 78.6%. The variations in Pb bioaccessibility depend on the in vitro models being used, suggesting that the method chosen for bioaccessibility assessment must be validated against in vivo studies prior to use for predicting risk. Regression studies between RBALP and SRBC, RBALP and RIVM (0.06) (0.06 g of soil in each tube, S:L ratios for gastric phase and intestinal phase are 1:375 and 1:958, respectively) showed that Pb bioaccessibility based on the three methods were comparable. Meanwhile, the slopes between RBALP and UBM, RBALP and RIVM (0.6) (0.6 g soil in each tube, S:L ratios for gastric phase and intestinal phase are 1:37.5 and 1:96, respectively) were 1.21 and 1.02, respectively. The findings presented in this study could help standardize in vitro bioaccessibility measurements and provide a scientific basis for further relating Pb bioavailability and soil properties.

The Mass-Metallicity Relation with the Direct Method on Stacked Spectra of SDSS Galaxies

NASA Astrophysics Data System (ADS)

Andrews, Brett H.; Martini, Paul

2013-03-01

The relation between galaxy stellar mass and gas-phase metallicity is a sensitive diagnostic of the main processes that drive galaxy evolution, namely cosmological gas inflow, metal production in stars, and gas outflow via galactic winds. We employed the direct method to measure the metallicities of ~200,000 star-forming galaxies from the Sloan Digital Sky Survey that were stacked in bins of (1) stellar mass and (2) both stellar mass and star formation rate (SFR) to significantly enhance the signal-to-noise ratio of the weak [O III] λ4363 and [O II] λλ7320, 7330 auroral lines required to apply the direct method. These metallicity measurements span three decades in stellar mass from log(M sstarf/M ⊙) = 7.4-10.5, which allows the direct method mass-metallicity relation to simultaneously capture the high-mass turnover and extend a full decade lower in mass than previous studies that employed more uncertain strong line methods. The direct method mass-metallicity relation rises steeply at low mass (O/H vprop M sstarf 1/2) until it turns over at log(M sstarf/M ⊙) = 8.9 and asymptotes to 12 + log(O/H) = 8.8 at high mass. The direct method mass-metallicity relation has a steeper slope, a lower turnover mass, and a factor of two to three greater dependence on SFR than strong line mass-metallicity relations. Furthermore, the SFR-dependence appears monotonic with stellar mass, unlike strong line mass-metallicity relations. We also measure the N/O abundance ratio, an important tracer of star formation history, and find the clear signature of primary and secondary nitrogen enrichment. N/O correlates tightly with oxygen abundance, and even more so with stellar mass.