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Sample records for predicting shear type

  1. Predicting km-scale shear zone formation

    NASA Astrophysics Data System (ADS)

    Gerbi, Christopher; Culshaw, Nicholas; Shulman, Deborah; Foley, Maura; Marsh, Jeffrey

    2015-04-01

    gradients but are insufficient to maintain them because the stress perturbations will dissipate with deformation. Metamorphism can unquestionably cause sufficient rheological change, but only in certain rock types: for example, granitoids have much less capacity for metamorphically induced rheologic change than do mafic rocks. The magnitude of phase geometry variation observed in natural systems suggests that morphological change (e.g., interconnection of weak phases) likely has little direct affect on strength changes, although other textural factors related to diffusion paths and crystallographic orientation could play a significant role. Thermal perturbation, mainly in the form of shear heating, remains potentially powerful but inconclusive. Taken together, these observations indicate that a simple algorithm predicting shear zone formation will not succeed in many geologically relevant instances. One significant reason may be that the inherent lithologic variation at the km scale, such as observed in the Central Gneiss belt, prevents the development of self-organized strain patterns that would form in more rheologically uniform systems.

  2. Wind shear predictive detector technology study status

    NASA Technical Reports Server (NTRS)

    Gandolfi, C.

    1990-01-01

    Among the different elements to be investigated when considering the Wind Shear hazard, the Aeronautical Navigation Technical Service (STNA/3E), whose task is to participate in the development of new technologies and equipments, focused its effort on airborne and ground sensors for the detection of low-level wind shear. The first task, initiated in 1986, consists in the evaluation of three candidate techniques for forward-looking sensors: lidar, sodar, and radar. No development is presently foreseen for an infrared based air turbulence advance warning system although some flight experiments took place in the 70's. A Thomson infrared radiometer was then installed on an Air France Boeing 707 to evaluate its capability of detecting clear air turbulence. The conclusion showed that this technique was apparently able to detect cloud layers but that additional experiments were needed; on the other hand, the rarity of the phenomenon and the difficulty in operating on a commercial aircraft were also mentioned.

  3. Advanced technology wind shear prediction system evaluation

    NASA Technical Reports Server (NTRS)

    Gering, Greg

    1992-01-01

    The program overviews: (1) American Airline (AA)/Turbulence Prediction Systems (TPS), which have installed forward looking infrared predictive windshear system on 3 MD-80 aircraft; (2) AA/TPS AWAS III evaluation, which is a joint effort and is installed in the noise landing gear (NLG) area and a data recorder installed in the E/E compartment.

  4. A Predictive Model of High Shear Thrombus Growth.

    PubMed

    Mehrabadi, Marmar; Casa, Lauren D C; Aidun, Cyrus K; Ku, David N

    2016-08-01

    The ability to predict the timescale of thrombotic occlusion in stenotic vessels may improve patient risk assessment for thrombotic events. In blood contacting devices, thrombosis predictions can lead to improved designs to minimize thrombotic risks. We have developed and validated a model of high shear thrombosis based on empirical correlations between thrombus growth and shear rate. A mathematical model was developed to predict the growth of thrombus based on the hemodynamic shear rate. The model predicts thrombus deposition based on initial geometric and fluid mechanic conditions, which are updated throughout the simulation to reflect the changing lumen dimensions. The model was validated by comparing predictions against actual thrombus growth in six separate in vitro experiments: stenotic glass capillary tubes (diameter = 345 µm) at three shear rates, the PFA-100(®) system, two microfluidic channel dimensions (heights = 300 and 82 µm), and a stenotic aortic graft (diameter = 5.5 mm). Comparison of the predicted occlusion times to experimental results shows excellent agreement. The model is also applied to a clinical angiography image to illustrate the time course of thrombosis in a stenotic carotid artery after plaque cap rupture. Our model can accurately predict thrombotic occlusion time over a wide range of hemodynamic conditions. PMID:26795978

  5. Doppler weather radar with predictive wind shear detection capabilities

    NASA Technical Reports Server (NTRS)

    Kuntman, Daryal

    1991-01-01

    The status of Bendix research on Doppler weather radar with predictive wind shear detection capability is given in viewgraph form. Information is given on the RDR-4A, a fully coherent, solid state transmitter having Doppler turbulence capability. Frequency generation data, plans, modifications, system characteristics and certification requirements are covered.

  6. Shear Strength Prediction By Modified Plasticity Theory For SFRC Beams

    SciTech Connect

    Colajanni, Piero; Recupero, Antonino; Spinella, Nino

    2008-07-08

    the plastic Crack Sliding Model (CSM) is extended for derivation of a physical model for the prediction of ultimate shear strength of SFRC beams, by assuming that the critical cracks is modeled by a yield lines. To this aim, the CSM is improved in order to take into account the strength increases due to the arch effect for deep beam. Then, the effectiveness factors for the concrete under biaxial stress are calibrated for fibrous concrete. The proposed model, able to provide the shear strength and the position of the critical cracks, is validate by a large set of test results collected in literature.

  7. Shear Wave Elastography and Cervical Lymph Nodes: Predicting Malignancy.

    PubMed

    Azizi, Ghobad; Keller, James M; Mayo, Michelle L; Piper, Kelé; Puett, David; Earp, Karly M; Malchoff, Carl D

    2016-06-01

    This prospective study evaluates the accuracy of virtual touch imaging quantification (VTIQ), a non-invasive shear wave elastography method for measuring cervical lymph nodes (LN) stiffness in differentiating benign from malignant LN. The study evaluated 270 LN in 236 patients with both conventional B-mode ultrasound and VTIQ shear wave elastography before fine-needle aspiration biopsy (FNAB). LN stiffness was measured as shear wave velocity (SWV) in m/s. Surgical resection was advised for FNAB results that were not clearly benign. Surgical pathology confirmed 54 malignant LN. The receiver operating curve (ROC) identified a single cut-off value of 2.93 m/s as the maximum SWV for predicting a malignant cervical LN. The sensitivity and specificity were 92.59% and 75.46%, respectively. Positive predictive value (PPV) was 48.54% and negative predictive value (NPV) was 97.60%. LN stiffness measured by VTIQ-generated shear wave elastography is an independent predictor of malignancy. PMID:26976785

  8. Shear Strength Prediction of RC Beams Wrapped with Frp

    NASA Astrophysics Data System (ADS)

    Wang, Suyan; Zhou, Yingwu; Li, Hongnan

    During past decades, substantial studies on the external bonding of fiber reinforced polymer (FRP) strips to deficient reinforced concrete (RC) beams have been carried out for the well-known superior properties of the FRP. Several shear prediction models have been established by using the effective strain of the FRP or introducing an ultimate stress discount coefficient. And the latest design concept is the use of stress distribution factor. In this paper, an equivalent effective strain model of the FRP is presented, which contains the concepts of maximum strain, stress distribution factor and critical shear crack angle influences. To develop a simple and accurate approach for such equivalent effective strain, major influenced factors are investigated and analyzed by the statistical independent hypothetic tests on a database of 128 RC beams wrapped by the FRP. Finally, a simple and rational shear design proposal is given, which is more accurate than the existing models using the above database.

  9. Prediction of the ionic polymer transducer sensing of shear loading

    NASA Astrophysics Data System (ADS)

    Zangrilli, U.; Weiland, L. M.

    2011-09-01

    While ionic polymer transducers (IPTs) have often been studied as actuators, they also show considerable promise as sensors. In addition to responding to bending, IPT sensors can also detect compression, tension and shear. Existing IPT models focus primarily on actuation, while the few available sensing models are limited to bending. This is due in part to the lack of a viable hypothesis for a physical mechanism that can explain the existence of a sensing signal in all deformation modes. Identification of the fundamental sensing mechanism is desirable as it could ultimately be exploited to design IPT sensors with an optimized response. Here it is hypothesized that the dominant physical mechanism for sensing is streaming potential, as it holds promise for explaining the existence of IPT sensing in any mode of deformation. We present a model for predicting the current developed when an IPT is subject to shear deformation, the creation of which has previously been elusive. The presented study employs a finite element approach to predict diluent flow with respect to the surrounding hydrophobic amorphous region under shear loading. Assessment of multiple flow path orientations with respect to load is used to impose volume averaging, and subsequently to project transducer current. Both peak and transient response are considered. Model predictions compare well with previously reported experimental results.

  10. Error propagation for velocity and shear stress prediction using 2D models for environmental management

    NASA Astrophysics Data System (ADS)

    Pasternack, Gregory B.; Gilbert, Andrew T.; Wheaton, Joseph M.; Buckland, Evan M.

    2006-08-01

    SummaryResource managers, scientists, government regulators, and stakeholders are considering sophisticated numerical models for managing complex environmental problems. In this study, observations from a river-rehabilitation experiment involving gravel augmentation and spawning habitat enhancement were used to assess sources and magnitudes of error in depth, velocity, and shear velocity predictions made at the 1-m scale with a commercial two-dimensional (depth-averaged) model. Error in 2D model depth prediction averaged 21%. This error was attributable to topographic survey resolution, which at 1 pt per 1.14 m 2, was inadequate to resolve small humps and depressions influencing point measurements. Error in 2D model velocity prediction averaged 29%. More than half of this error was attributable to depth prediction error. Despite depth and velocity error, 56% of tested 2D model predictions of shear velocity were within the 95% confidence limit of the best field-based estimation method. Ninety percent of the error in shear velocity prediction was explained by velocity prediction error. Multiple field-based estimates of shear velocity differed by up to 160%, so the lower error for the 2D model's predictions suggests such models are at least as accurate as field measurement. 2D models enable detailed, spatially distributed estimates compared to the small number measurable in a field campaign of comparable cost. They also can be used for design evaluation. Although such numerical models are limited to channel types adhering to model assumptions and yield predictions only accurate to ˜20-30%, they can provide a useful tool for river-rehabilitation design and assessment, including spatially diverse habitat heterogeneity as well as for pre- and post-project appraisal.

  11. Predicting boundary shear stress and sediment transport over bed forms

    USGS Publications Warehouse

    McLean, S.R.; Wolfe, S.R.; Nelson, J.M.

    1999-01-01

    To estimate bed-load sediment transport rates in flows over bed forms such as ripples and dunes, spatially averaged velocity profiles are frequently used to predict mean boundary shear stress. However, such averaging obscures the complex, nonlinear interaction of wake decay, boundary-layer development, and topographically induced acceleration downstream of flow separation and often leads to inaccurate estimates of boundary stress, particularly skin friction, which is critically important in predicting bed-load transport rates. This paper presents an alternative methodology for predicting skin friction over 2D bed forms. The approach is based on combining the equations describing the mechanics of the internal boundary layer with semiempirical structure functions to predict the velocity at the crest of a bedform, where the flow is most similar to a uniform boundary layer. Significantly, the methodology is directed toward making specific predictions only at the bed-form crest, and as a result it avoids the difficulty and questionable validity of spatial averaging. The model provides an accurate estimate of the skin friction at the crest where transport rates are highest. Simple geometric constraints can be used to derive the mean transport rates as long as bed load is dominant.To estimate bed-load sediment transport rates in flows over bed forms such as ripples and dunes, spatially averaged velocity profiles are frequently used to predict mean boundary shear stress. However, such averaging obscures the complex, nonlinear interaction of wake decay, boundary-layer development, and topographically induced acceleration downstream of flow separation and often leads to inaccurate estimates of boundary stress, particularly skin friction, which is critically important in predicting bed-load transport rates. This paper presents an alternative methodology for predicting skin friction over 2D bed forms. The approach is based on combining the equations describing the mechanics of

  12. Multiscale model for predicting shear zone structure and permeability in deforming rock

    NASA Astrophysics Data System (ADS)

    Cleary, Paul W.; Pereira, Gerald G.; Lemiale, Vincent; Piane, Claudio Delle; Clennell, M. Ben

    2016-04-01

    A novel multiscale model is proposed for the evolution of faults in rocks, which predicts their internal properties and permeability as strain increases. The macroscale model, based on smoothed particle hydrodynamics (SPH), predicts system scale deformation by a pressure-dependent elastoplastic representation of the rock and shear zone. Being a continuum method, SPH contains no intrinsic information on the grain scale structure or behaviour of the shear zone, so a series of discrete element method microscale shear cell models are embedded into the macroscale model at specific locations. In the example used here, the overall geometry and kinematics of a direct shear test on a block of intact rock is simulated. Deformation is imposed by a macroscale model where stresses and displacement rates are applied at the shear cell walls in contact with the rock. Since the microscale models within the macroscale block of deforming rock now include representations of the grains, the structure of the shear zone, the evolution of the size and shape distribution of these grains, and the dilatancy of the shear zone can all be predicted. The microscale dilatancy can be used to vary the macroscale model dilatancy both spatially and temporally to give a full two-way coupling between the spatial scales. The ability of this model to predict shear zone structure then allows the prediction of the shear zone permeability using the Lattice-Boltzmann method.

  13. Combined Resistivity and Shear Wave Velocity Soil-type Estimation Beneath a Coastal Protection Levee.

    NASA Astrophysics Data System (ADS)

    Lorenzo, J. M.; Goff, D.; Hayashi, K.

    2015-12-01

    Unconsolidated Holocene deltaic sediments comprise levee foundation soils in New Orleans, USA. Whereas geotechnical tests at point locations are indispensable for evaluating soil stability, the highly variable sedimentary facies of the Mississippi delta create difficulties to predict soil conditions between test locations. Combined electrical resistivity and seismic shear wave studies, calibrated to geotechnical data, may provide an efficient methodology to predict soil types between geotechnical sites at shallow depths (0- 10 m). The London Avenue Canal levee flank of New Orleans, which failed in the aftermath of Hurricane Katrina, 2005, presents a suitable site in which to pioneer these geophysical relationships. Preliminary cross-plots show electrically resistive, high-shear-wave velocity areas interpreted as low-permeability, resistive silt. In brackish coastal environments, low-resistivity and low-shear-wave-velocity areas may indicate both saturated, unconsolidated sands and low-rigidity clays. Via a polynomial approximation, soil sub-types of sand, silt and clay can be estimated by a cross-plot of S-wave velocity and resistivity. We confirm that existent boring log data fit reasonably well with the polynomial approximation where 2/3 of soil samples fall within their respective bounds—this approach represents a new classification system that could be used for other mid-latitude, fine-grained deltas.

  14. Damage identification in shear-type structures using a proper orthogonal decomposition approach

    NASA Astrophysics Data System (ADS)

    Wang, Dansheng; Xiang, Wei; Zeng, Peng; Zhu, Hongping

    2015-10-01

    Proper orthogonal modes (POMs) obtained through proper orthogonal decomposition (POD), as a statistical pattern analysis technique, have been physically demonstrated to represent the dominant structure of the dynamic response data in previous study. In this paper, a novel POMs-based damage identification approach for shear-type buildings is developed. First, POMs of acceleration dynamic response of a shear-type building under Gauss White Noise (GWN) ground motion are obtained using singular value decomposition; then, the dominant POMs of acceleration response are used to identify the damage locations and severities through particle swarm optimization (PSO) algorithm. This proposed approach is applied to two three-story shear-type buildings in numerical simulation and a three-story shear-type frame in experimental study. The results demonstrate that the locations and severities of structural damage in shear-type buildings can be effectively identified by using the proposed method.

  15. Predicting prognostic factors of breast cancer using shear wave elastography.

    PubMed

    Choi, Woo Jung; Kim, Hak Hee; Cha, Joo Hee; Shin, Hee Jung; Kim, Hyunji; Chae, Eun Young; Hong, Min Ji

    2014-02-01

    The purpose of the study described here was to investigate the correlation between histologic factors, including immunohistochemical factors, related to the prognosis of breast cancer and shear wave elastography (SWE) measurements. One hundred twenty-two breast cancers from 116 women were subjected to sonoelastography. Of the SWE features, mean and maximum elasticity and SWE ratio were extracted. The SWE ratio was calculated as the ratio of the stiffness of a portion of the lesion to that of a similar region of interest in fatty tissue. High ratios indicate stiffer lesions. The Mann-Whitney U-test, Kruskal-Wallis test and receiver operating characteristic (ROC) curve were used for statistical analysis. Estrogen receptor negativity, progesterone receptor negativity, p53 positivity, Ki-67 positivity, high nuclear grade, high histologic grade and large tumor (invasive) size were associated with a significantly high SWE ratio (p < 0.05). ROC curve analysis yielded SWE ratio cutoff values of 2.74-3.69 for significant immunohistochemical factors and 4.21 for the basal-like subtype by maximizing specificity while ensuring more than 80% sensitivity. Breast cancers with aggressive histologic features had high SWE ratios. Shear wave elastography may provide useful information for determining prognosis. PMID:24268451

  16. Predictions of axisymmetric free turbulent shear flows using a generalized eddy-viscosity approach

    NASA Technical Reports Server (NTRS)

    Morgenthaler, J. H.

    1973-01-01

    The generalized eddy viscosity approach is described and results are presented of test cases which show that predictions obtained by this approach are adequate for most engineering applications. Because of the importance of starting computations from the injection station where experimentally determined mean and turbulence parameters are rarely available, a very simple core model applicable to simple step-type (slug) profiles was developed. Agreement between predicted and experimental mean profiles was generally almost as good for calculations made by using this model throughout the core region and the transition model for all subsequent regions as predictions made by starting from experimental profiles in the transition region. The generalized eddy-viscosity model, which was developed in part through correlation of turbulence parameters, successfully predicted turbulent shear stress, turbulent intensity, and mean velocity profiles for a 0.040-inch-diameter microjet. Therefore, successful scaling by the model was demonstrated since data used in its development was for jet areas up to 90,000 times as large as the microjet and velocities only 1/20th as high.

  17. Prediction of the Shear Wave Velocity from Compressional Wave Velocity for Gachsaran Formation

    NASA Astrophysics Data System (ADS)

    Parvizi, Saeed; Kharrat, Riyaz; Asef, Mohammad R.; Jahangiry, Bijan; Hashemi, Abdolnabi

    2015-10-01

    Shear and compressional wave velocities, coupled with other petrophysical data, are very important for hydrocarbon reservoir characterization. In situ shear wave velocity (Vs) is measured by some sonic logging tools. Shear velocity coupled with compressional velocity is vitally important in determining geomechanical parameters, identifying the lithology, mud weight design, hydraulic fracturing, geophysical studies such as VSP, etc. In this paper, a correlation between compressional and shear wave velocity is obtained for Gachsaran formation in Maroon oil field. Real data were used to examine the accuracy of the prediction equation. Moreover, the genetic algorithm was used to obtain the optimal value for constants of the suggested equation. Furthermore, artificial neural network was used to inspect the reliability of this method. These investigations verify the notion that the suggested equation could be considered as an efficient, fast, and cost-effective method for predicting Vs from Vp.

  18. Prediction of Anomalous Blood Viscosity in Confined Shear Flow

    NASA Astrophysics Data System (ADS)

    Thiébaud, Marine; Shen, Zaiyi; Harting, Jens; Misbah, Chaouqi

    2014-06-01

    Red blood cells play a major role in body metabolism by supplying oxygen from the microvasculature to different organs and tissues. Understanding blood flow properties in microcirculation is an essential step towards elucidating fundamental and practical issues. Numerical simulations of a blood model under a confined linear shear flow reveal that confinement markedly modifies the properties of blood flow. A nontrivial spatiotemporal organization of blood elements is shown to trigger hitherto unrevealed flow properties regarding the viscosity η, namely ample oscillations of its normalized value [η]=(η-η0)/(η0ϕ) as a function of hematocrit ϕ (η0=solvent viscosity). A scaling law for the viscosity as a function of hematocrit and confinement is proposed. This finding can contribute to the conception of new strategies to efficiently detect blood disorders, via in vitro diagnosis based on confined blood rheology. It also constitutes a contribution for a fundamental understanding of rheology of confined complex fluids.

  19. Determining Flow Type and Shear Rate in Magmas From Bubble Shapes and Orientations

    NASA Astrophysics Data System (ADS)

    Rust, A. C.; Manga, M.; Cashman, K. V.

    2001-12-01

    To compare bubble geometries in obsidian to bubbles deformed under known conditions, we measure the deformation of air bubbles in corn syrup in simple shear. We use these experimental data and results of theoretical, numerical and experimental studies to interpret the shear environments that formed the textures preserved in obsidian samples. In particular, we use the shapes and orientations of bubbles in obsidian to estimate shear rates and assess flow type (simple vs. pure shear). This technique can be used to determine shear rates in volcanic conduits, the origin of pyroclastic obsidian, and the emplacement history and dynamics of obsidian flows. The deformation of a bubble is governed by the competing stresses from shearing that deforms, and surface tension that rerounds. The ratio of these stresses is the capillary number, Ca. An initially spherical bubble placed in a low Reynolds number, steady flow field deforms with a time-dependent shape and orientation until it reaches a steady geometry or breaks into smaller bubbles. A useful measure of the magnitude of flow-induced bubble deformation is the dimensionless parameter, D=(l-b)/(l+b) where l and b are the semi-major and semi-minor axes of the sheared bubble. For small deformations (Ca<< 1), low Reynolds number flow and bubble viscosity << suspending fluid viscosity, D ~ 2 Ca in pure shear and D ~ Ca in simple shear. In pure shear flow, bubble elongations are parallel to the shear direction regardless of the magnitude of bubble deformation. However, in simple shear flow, the angle between the bubble elongation and the flow varies with Ca, which is proportional to bubble radius and shear rate. Because the relationships between Ca and bubble orientation and shape for pure and simple shear differ, we can distinguish between these flow types using bubble geometries preserved in obsidian. Furthermore, because Ca is a function of shear rate, we can use relationships between Ca and D to calculate shear rates when

  20. Oscillatory shear response of dilute ferrofluids: predictions from rotational Brownian dynamics simulations and ferrohydrodynamics modeling.

    PubMed

    Soto-Aquino, D; Rosso, D; Rinaldi, C

    2011-11-01

    Ferrofluids are colloidal suspensions of magnetic nanoparticles that exhibit normal liquid behavior in the absence of magnetic fields but respond to imposed magnetic fields by changing their viscosity without loss of fluidity. The response of ferrofluids to constant shear and magnetic fields has received a lot of attention, but the response of ferrofluids to oscillatory shear remains largely unexplored. In the present work we used rotational Brownian dynamics to study the dynamic properties of ferrofluids with thermally blocked nanoparticles under oscillatory shear and constant magnetic fields. Comparisons between simulations and modeling using the ferrohydrodynamics equations were also made. Simulation results show that, for small rotational Péclet number, the in-phase and out-of-phase components of the complex viscosity depend on the magnitude of the magnetic field and frequency of the shear, following a Maxwell-like model with field-dependent viscosity and characteristic time equal to the field-dependent transverse magnetic relaxation time of the nanoparticles. Comparison between simulations and the numerical solution of the ferrohydrodynamic equations shows that the oscillatory rotational magnetoviscosity for an oscillating shear field obtained using the kinetic magnetization relaxation equation quantitatively agrees with simulations for a wide range of Péclet number and Langevin parameter but has quantitative deviations from the simulations at high values of the Langevin parameter. These predictions indicate an apparent elastic character to the rheology of these suspensions, even though we are considering the infinitely dilute limit in which there are negligible particle-particle interactions and, as such, chains do not form. Additionally, an asymptotic analytical solution of the ferrohydrodynamics equations, valid for Pe<2, was used to demonstrate that the Cox-Merz rule applies for dilute ferrofluids under conditions of small shear rates. At higher shear

  1. Compressional and shear-wave velocity versus depth relations for common rock types in northern California

    USGS Publications Warehouse

    Brocher, T.M.

    2008-01-01

    This article presents new empirical compressional and shear-wave velocity (Vp and Vs) versus depth relationships for the most common rock types in northern California. Vp versus depth relations were developed from borehole, laboratory, seismic refraction and tomography, and density measurements, and were converted to Vs versus depth relations using new empirical relations between Vp and Vs. The relations proposed here account for increasing overburden pressure but not for variations in other factors that can influence velocity over short distance scales, such as lithology, consolidation, induration, porosity, and stratigraphic age. Standard deviations of the misfits predicted by these relations thus provide a measure of the importance of the variability in Vp and Vs caused by these other factors. Because gabbros, greenstones, basalts, and other mafic rocks have a different Vp and Vs relationship than sedimentary and granitic rocks, the differences in Vs between these rock types at depths below 6 or 7 km are generally small. The new relations were used to derive the 2005 U.S. Geological Survey seismic velocity model for northern California employed in the broadband strong motion simulations of the 1989 Loma Prieta and 1906 San Francisco earthquakes; initial tests of the model indicate that the Vp model generally compares favorably to regional seismic tomography models but that the Vp and Vs values proposed for the Franciscan Complex may be about 5% too high.

  2. Predicting equilibrium states with Reynolds stress closures in channel flow and homogeneous shear flow

    NASA Technical Reports Server (NTRS)

    Abid, R.; Speziale, C. G.

    1993-01-01

    Turbulent channel flow and homogeneous shear flow have served as basic building block flows for the testing and calibration of Reynolds stress models. A direct theoretical connection is made between homogeneous shear flow in equilibrium and the log-layer of fully-developed turbulent channel flow. It is shown that if a second-order closure model is calibrated to yield good equilibrium values for homogeneous shear flow it will also yield good results for the log-layer of channel flow provided that the Rotta coefficient is not too far removed from one. Most of the commonly used second-order closure models introduce an ad hoc wall reflection term in order to mask deficient predictions for the log-layer of channel flow that arise either from an inaccurate calibration of homogeneous shear flow or from the use of a Rotta coefficient that is too large. Illustrative model calculations are presented to demonstrate this point which has important implications for turbulence modeling.

  3. Predicting equilibrium states with Reynolds stress closures in channel flow and homogeneous shear flow

    NASA Technical Reports Server (NTRS)

    Abid, R.; Speziale, C. G.

    1992-01-01

    Turbulent channel flow and homogeneous shear flow have served as basic building block flows for the testing and calibration of Reynolds stress models. A direct theoretical connection is made between homogeneous shear flow in equilibrium and the log-layer of fully-developed turbulent channel flow. It is shown that if a second-order closure model is calibrated to yield good equilibrium values for homogeneous shear flow it will also yield good results for the log-layer of channel flow provided that the Rotta coefficient is not too far removed from one. Most of the commonly used second-order closure models introduce an ad hoc wall reflection term in order to mask deficient predictions for the log-layer of channel flow that arise either from an inaccurate calibration of homogeneous shear flow or from the use of a Rotta coefficient that is too large. Illustrative model calculations are presented to demonstrate this point which has important implications for turbulence modeling.

  4. Prediction of Shear-induced Crack Initiation in AHSS Deep Drawing Operation with a Phenomenological Fracture Model

    NASA Astrophysics Data System (ADS)

    Luo, Meng; Li, Yaning; Gerlach, Joerg; Wierzbicki, Tomasz

    2010-06-01

    Advanced High Strength Steels (AHSS) draws enormous attentions in automotive industry because it has great potential in reducing weight and improving fuel efficiency. Nonetheless, their relatively low formability also causes many problems in manufacturing processes, such as shear-induced fracture during deep drawing or stamping. This type of fracture could not be predicted using traditional necking-based Forming Limit Diagram (FLD), which is commonly used by the forming community. In the present paper, a recently developed Modified Mohr-Coulomb (MMC)[1] ductile fracture model is employed to make up the deficiency of FLD. In the limiting case of plane stress, the MMC fracture locus consists of four branches when represented on the plane of the equivalent strain to fracture and the stress triaxiality. A transformation of above 2D fracture locus to the space of principal strains was performed which revealed the existence of two new branches not known before. The existence of those branches explains the formation of shear-induced fracture. As an illustration of this new approach, initiation and propagation of cracks in a series of deep drawing tests is predicted and compared with the experimental observations. It was shown that the location of fracture as well as the magnitude of punch travel corresponding to first fracture was correctly predicted by MMC fracture model for both square and circular punch cases.

  5. Interfacial shear modeling and flow predictions for internal film condesation flows

    NASA Technical Reports Server (NTRS)

    Narain, A.

    1992-01-01

    Internal flow of pure vapor experiencing film condesation on the walls of a straight duct is studied. The commonly occuring case of turbulent (or laminar) vapor flow in the core and laminar flow of the liquid condensate-with or without waves on the interface-is emphasized. We propose and implement a new first principle methodolgy which model interfacial shear with the help of reliable experimental data on heat transfer rates. Other details of the flow are predicted with the help of this model. These predictions are shown to be in agreement with relevant experimental data. Correlations for film thickness and heat transfer rates are also given.

  6. The effect of the second turbulence scale equation on the prediction of rotated homogeneous shear flows

    NASA Astrophysics Data System (ADS)

    Kassinos, S. C.; Reynolds, W. C.; Langer, C. A.

    2002-11-01

    Reynolds-averaged two equation turbulence models carry transport equations for two turbulence scales. The kinetic energy (k) equation provides a solid foundation for the energy scale. The exact transport equation for the energy dissipation rate (ɛ) is not useful as the basis for the second scale because ɛ is determined by large-scale turbulent interactions not represented in this equation. The transport equation for the large-scale enstrophy does provide a solid basis for modeling the evolution of the large-scale enstrophy, which together with k determines the spectral energy transfer that ultimately leads to dissipation by the small-scale motions. Here we close this equation using the new structure tensors and use it with our structure-based turbulence models (SBM) for homogeneous turbulence that is strained and sheared in fixed or rotating frames. Model predictions are in excellent agreement with results from large-scale Direct Numerical Simulations (DNS) that we are conducting for the ASCI program at Stanford. For shear in a rotating frame, of particular interest is the ratio of production over dissipation (P/ɛ) in the final equilibrium, and the dependence of this ratio on the ratio of frame rotation rate to shear rate (Ω^f/Γ). SBM predictions are in excellent agreement with DNS results; the traditional pair of the k and ɛ scale equations leads to wrong behavior for P/ɛ with Ω^f/Γ.

  7. Possibility of Shear Type Fracture in Viscoplastic Material under Confining Pressures

    NASA Astrophysics Data System (ADS)

    Yamaguchi, H.; Sakaguchi, K.; Sato, K.; Matsuki, K.; Hashida, T.

    2008-02-01

    Transition from opening-mode wing crack growth to shear type fracture has been investigated by conducting triaxial compression tests under confining pressures, using epoxy resin cylindrical specimens. The epoxy resin used exhibited viscoplastic deformation characteristics under confining pressures, which is expected to simulate the nonlinear deformation observed commonly for rocks at great depths and to provide useful insight in understanding of the fracture transition in rocks. Under the range of confining pressures, 10 MPa-30 MPa, an array of opening-mode wing cracks were initiated from a preexisting inclined penny-shaped crack, as the axial stress was increased. Only the extension of a wing crack was observed to take place under no confining pressure condition. It was shown that the growth of the wing cracks were suppressed when higher confining pressures were applied and shear type fracture consisting of several wing cracks was induced as the deformation progressed. The experimental observation suggests the possibility of occurrence of shear type fracture in such a homogeneous material under higher confining pressures, and the mechanical interaction between cracks plays a crucial role in the generation of shear type fracture rather than the inhomogeneity of rocks.

  8. The Effect of Impeller Type on Floc Size and Structure during Shear-Induced Flocculation

    PubMed

    Spicer; Keller; Pratsinis

    1996-12-01

    The effect of impeller type and shear rate on the evolution of floc size and structure during shear-induced flocculation of polystyrene particles with aluminum sulfate is investigated by image analysis. One radial flow (six-blade Rushton turbine) and two axial flow (three-blade fluid foil, four-blade 45° pitch) impeller configurations are examined. The steady state average floc size is shown to depend on the frequency of recirculation to the impeller zone and its characteristic velocity gradient. The concepts of fractal geometry are used to characterize the floc structure. For all impellers, the two-dimensional floc fractal dimension, Dpf, increases during floc growth, indicating formation of more open structures. Later on, Dpf levels off at a steady state value as breakage becomes significant and the floc size distribution approaches steady state. The shear rate does not affect the steady state Dpf of the flocs within experimental uncertainty. PMID:8954644

  9. Effects of different vegetation types on the shear strength of root-permeated soils

    NASA Astrophysics Data System (ADS)

    Yildiz, Anil; Graf, Frank; Rickli, Christian; Springman, Sarah M.

    2016-04-01

    The effects of vegetation and, in particular, of forests on the stability of slopes are well recognized and have been widely studied in recent decades. However, there is still a lack of understanding of the underlying processes that occur prior to triggering superficial failures in root-permeated soil. Thus, appropriate quantification of the vegetation effects on the shear strength of soil is crucial in order to be able to evaluate the stability of a vegetated slope. Direct shear testing is widely employed to determine the shearing response of root-permeated soil. However, mechanical aspects of direct shear apparatuses may affect the shear strength parameters derived, which often remains unnoticed and hampers direct comparison between different studies. A robust Inclinable Large-scale Direct Shear Apparatus (ILDSA), with dimensions of 500x500x400 mm, was built in order to shear root-permeated soil specimens and to analyse the influence of the machine setup on the results, too. Two different sets of planted specimens were prepared using moraine (SP-SM) from a recent landslide area in Central Switzerland: a first set consisting of Alnus incana, Trifolium pratense, Poa pratensis and a second set, consisting of these three species complemented with Salix appendiculata, Achillea millefolium, Anthyllis vulneraria. Direct shear tests were conducted on specimens planted with the different vegetation types, at a constant rate of horizontal displacement of 1 mm/min up to a maximum horizontal displacement of 190 mm, and under three different applied normal stresses: 6 kPa, 11 kPa and 16 kPa. Artificial rainfall was applied at a constant intensity (100 mm/h) prior to shearing. Tensiometers had been installed close to the shear surface and were monitored continuously to obtain the matric suction during the saturation process. Suctions were reduced as close to 0 kPa as possible, in order to simulate the loss of strength after a heavy period of rainfall. The analyses of the above

  10. A Pian-Sumihara type element for modeling shear bands at finite deformation

    NASA Astrophysics Data System (ADS)

    McAuliffe, Colin; Waisman, Haim

    2014-05-01

    A monolithic numerical solution of a partial differential equation (PDE) model for shear bands, which includes a thermal softening rate dependent plastic flow rule and finite thermal conductivity, is presented. The formulation accounts for large deformation kinematics and includes incrementally objective treatment of the hypoplastic constitutive relations. Regularization is achieved by including finite thermal conductivity, which informs the PDE system of a length scale, governed by competition between shear heating and thermal diffusion. The monolithic solution scheme is then used to eliminate splitting errors during the solution of the discretized system. The scheme is presented in a general, mixed formulation, which allows for many choices of shape functions. We study and compare two elements, which have been implemented with the monolithic nonlinear solver: the Irreducible Shear Band Quad (ISBQ) and the Pian Sumihara Shear Band Quad (PSSBQ). ISBQ employs the same interpolation as an irreducible four node quad while PSSBQ is a mixed, assumed stress element. The algorithmic approximations to the Lie derivative and Jaumann rate of Kirchhoff stress are available in the literature for ISBQ type elements, and are derived in this paper for the PSSBQ. These expressions are used to achieve an incrementally objective formulation. It is found that the PSSBQ converges faster than the ISBQ with mesh refinement, and that the convergence of the ISBQ can be improved with a remeshing procedure.

  11. EFFECT OF MEASUREMENT ERRORS ON PREDICTED COSMOLOGICAL CONSTRAINTS FROM SHEAR PEAK STATISTICS WITH LARGE SYNOPTIC SURVEY TELESCOPE

    SciTech Connect

    Bard, D.; Chang, C.; Kahn, S. M.; Gilmore, K.; Marshall, S.; Kratochvil, J. M.; Huffenberger, K. M.; May, M.; AlSayyad, Y.; Connolly, A.; Gibson, R. R.; Jones, L.; Krughoff, S.; Ahmad, Z.; Bankert, J.; Grace, E.; Hannel, M.; Lorenz, S.; Haiman, Z.; Jernigan, J. G.; and others

    2013-09-01

    We study the effect of galaxy shape measurement errors on predicted cosmological constraints from the statistics of shear peak counts with the Large Synoptic Survey Telescope (LSST). We use the LSST Image Simulator in combination with cosmological N-body simulations to model realistic shear maps for different cosmological models. We include both galaxy shape noise and, for the first time, measurement errors on galaxy shapes. We find that the measurement errors considered have relatively little impact on the constraining power of shear peak counts for LSST.

  12. Rock physics model-based prediction of shear wave velocity in the Barnett Shale formation

    NASA Astrophysics Data System (ADS)

    Guo, Zhiqi; Li, Xiang-Yang

    2015-06-01

    Predicting S-wave velocity is important for reservoir characterization and fluid identification in unconventional resources. A rock physics model-based method is developed for estimating pore aspect ratio and predicting shear wave velocity Vs from the information of P-wave velocity, porosity and mineralogy in a borehole. Statistical distribution of pore geometry is considered in the rock physics models. In the application to the Barnett formation, we compare the high frequency self-consistent approximation (SCA) method that corresponds to isolated pore spaces, and the low frequency SCA-Gassmann method that describes well-connected pore spaces. Inversion results indicate that compared to the surroundings, the Barnett Shale shows less fluctuation in the pore aspect ratio in spite of complex constituents in the shale. The high frequency method provides a more robust and accurate prediction of Vs for all the three intervals in the Barnett formation, while the low frequency method collapses for the Barnett Shale interval. Possible causes for this discrepancy can be explained by the fact that poor in situ pore connectivity and low permeability make well-log sonic frequencies act as high frequencies and thus invalidate the low frequency assumption of the Gassmann theory. In comparison, for the overlying Marble Falls and underlying Ellenburger carbonates, both the high and low frequency methods predict Vs with reasonable accuracy, which may reveal that sonic frequencies are within the transition frequencies zone due to higher pore connectivity in the surroundings.

  13. Turbulence Modeling Effects on the Prediction of Equilibrium States of Buoyant Shear Flows

    NASA Technical Reports Server (NTRS)

    Zhao, C. Y.; So, R. M. C.; Gatski, T. B.

    2001-01-01

    The effects of turbulence modeling on the prediction of equilibrium states of turbulent buoyant shear flows were investigated. The velocity field models used include a two-equation closure, a Reynolds-stress closure assuming two different pressure-strain models and three different dissipation rate tensor models. As for the thermal field closure models, two different pressure-scrambling models and nine different temperature variance dissipation rate, Epsilon(0) equations were considered. The emphasis of this paper is focused on the effects of the Epsilon(0)-equation, of the dissipation rate models, of the pressure-strain models and of the pressure-scrambling models on the prediction of the approach to equilibrium turbulence. Equilibrium turbulence is defined by the time rate (if change of the scaled Reynolds stress anisotropic tensor and heat flux vector becoming zero. These conditions lead to the equilibrium state parameters. Calculations show that the Epsilon(0)-equation has a significant effect on the prediction of the approach to equilibrium turbulence. For a particular Epsilon(0)-equation, all velocity closure models considered give an equilibrium state if anisotropic dissipation is accounted for in one form or another in the dissipation rate tensor or in the Epsilon(0)-equation. It is further found that the models considered for the pressure-strain tensor and the pressure-scrambling vector have little or no effect on the prediction of the approach to equilibrium turbulence.

  14. Full-field predictions of ice dynamic recrystallisation under simple shear conditions

    NASA Astrophysics Data System (ADS)

    Llorens, Maria-Gema; Griera, Albert; Bons, Paul D.; Lebensohn, Ricardo A.; Evans, Lynn A.; Jansen, Daniela; Weikusat, Ilka

    2016-09-01

    Understanding the flow of ice on the microstructural scale is essential for improving our knowledge of large-scale ice dynamics, and thus our ability to predict future changes of ice sheets. Polar ice behaves anisotropically during flow, which can lead to strain localisation. In order to study how dynamic recrystallisation affects to strain localisation in deep levels of polar ice sheets, we present a series of numerical simulations of ice polycrystals deformed under simple-shear conditions. The models explicitly simulate the evolution of microstructures using a full-field approach, based on the coupling of a viscoplastic deformation code (VPFFT) with dynamic recrystallisation codes. The simulations provide new insights into the distribution of stress, strain rate and lattice orientation fields with progressive strain, up to a shear strain of three. Our simulations show how the recrystallisation processes have a strong influence on the resulting microstructure (grain size and shape), while the development of lattice preferred orientations (LPO) appears to be less affected. Activation of non-basal slip systems is enhanced by recrystallisation and induces a strain hardening behaviour up to the onset of strain localisation and strain weakening behaviour. Simulations demonstrate that the strong intrinsic anisotropy of ice crystals is transferred to the polycrystalline scale and results in the development of strain localisation bands than can be masked by grain boundary migration. Therefore, the finite-strain history is non-directly reflected by the final microstructure. Masked strain localisation can be recognised in ice cores, such as the EDML, from the presence of stepped boundaries, microshear and grains with zig-zag geometries.

  15. Eolian reservoir characteristics predicted from dune type

    SciTech Connect

    Kocurek, G.; Nielson, J.

    1985-02-01

    The nature of eolian-dune reservoirs is strongly influenced by stratification types (in decreasing order of quality: grain-flow, grain-fall, wind-ripple deposits) and their packaging by internal bounding surfaces. These are, in turn, a function of dune surface processes and migration behavior, allowing for predictive models of reservoir behavior. Migrating, simple crescentic dunes produce tabular bodies consisting mainly of grain-flow cross-strata, and form the best, most predictable reservoirs. Reservoir character improves as both original dune height and preserved set thickness increase, because fewer grain-fall deposits and a lower percentage of dune-apron deposits occur in the cross-strata, respectively. It is probable that many linear and star dunes migrate laterally, leaving a blanket of packages of wind ripple laminae reflecting deposition of broad, shifting aprons. This is distinct from models generated by freezing large portions of these dunes in place. Trailing margins of linear and star dunes are prone to reworking by sand-sheet processes that decrease potential reservoir quality. The occurrence of parabolic dunes isolated on vegetated sand sheets results in a core of grain-flow and grain-fall deposits surrounded by less permeable and porous deposits. Compound crescentic dunes, perhaps the most preservable dune type, may yield laterally (1) single sets of cross-strate, (2) compound sets derived from superimposed simple dunes, or (3) a complex of diverse sets derived from superimposed transverse and linear elements.

  16. Systematic experimental study of pure shear type dielectric elastomer membranes with different electrode and film thicknesses

    NASA Astrophysics Data System (ADS)

    Hodgins, M.; Seelecke, S.

    2016-09-01

    An approach to reduce the voltage required for dielectric elastomer actuators is to reduce film thickness. However, if the electrode thickness is not similarly reduced, the electrode’s mechanical behavior can increasingly and negatively impact the overall actuator behavior. This effect is yet to be studied and quantified for pure shear type specimens; a type recommended in a recent DE standardization journal publication. Therefore, in this work, using pure shear specimens, a comparative study of membrane actuators of different film thickness (20, 50 and 100 μm) is performed. Electrodes of different thicknesses are screen printed and tested in a uniaxial test device. The stiffening effect due to the solid-state electrodes is demonstrated by performing force-elongation tests for specimens with and without electrodes. Additionally the importance of thin electrodes (relative to film thickness) was demonstrated through a number of electromechanical tests. Isotonic tests revealed a lower electro-mechanical sensitivity for the 20 μm film when compared with the 50 and 100 μm films. This was attributed to the relatively thick electrodes. Best actuation results were achieved when the total electrode thickness was at least 15x thinner than the dielectric membrane thickness.

  17. Shear-thinning and constant viscosity predictions for rotating sphere flows

    NASA Astrophysics Data System (ADS)

    Garduño, Isaías E.; Tamaddon-Jahromi, Hamid R.; Webster, Michael F.

    2016-02-01

    The steady motion of a rotating sphere is analysed through two contrasting viscoelastic models, a constant viscosity (FENE-CR) model and a shear-thinning (LPTT) model. Giesekus (Rheol. Acta 9:30-38, 1970) presented an intriguing rotating viscoelastic flow, which to date has not been completely explained. In order to investigate this flow, sets of parameters have been explored to analyse the significant differences introduced with the proposed models, while the momentum-continuity-stress equations are solved through a hybrid finite-element/finite volume numerical scheme. Solutions are discussed for first, sphere angular velocity increase (\\varOmega), and second, through material velocity-scale increase (α). Numerical predictions for different solvent-ratios (β) show significant differences as the sphere angular velocity increases. It is demonstrated that an emerging equatorial anticlockwise vortex emerges in a specific range of \\varOmega. As such, this solution matches closely with the Giesekus experimental findings. Additionally, inside the emerging inertial vortex, a contrasting positive second normal stress-difference (N2 ( dot{γ} ) = τ_{rr} - τ_{θθ}) region is found compared against the negative N2-enveloping layer.

  18. Prediction of shear wave velocity using empirical correlations and artificial intelligence methods

    NASA Astrophysics Data System (ADS)

    Maleki, Shahoo; Moradzadeh, Ali; Riabi, Reza Ghavami; Gholami, Raoof; Sadeghzadeh, Farhad

    2014-06-01

    Good understanding of mechanical properties of rock formations is essential during the development and production phases of a hydrocarbon reservoir. Conventionally, these properties are estimated from the petrophysical logs with compression and shear sonic data being the main input to the correlations. This is while in many cases the shear sonic data are not acquired during well logging, which may be for cost saving purposes. In this case, shear wave velocity is estimated using available empirical correlations or artificial intelligent methods proposed during the last few decades. In this paper, petrophysical logs corresponding to a well drilled in southern part of Iran were used to estimate the shear wave velocity using empirical correlations as well as two robust artificial intelligence methods knows as Support Vector Regression (SVR) and Back-Propagation Neural Network (BPNN). Although the results obtained by SVR seem to be reliable, the estimated values are not very precise and considering the importance of shear sonic data as the input into different models, this study suggests acquiring shear sonic data during well logging. It is important to note that the benefits of having reliable shear sonic data for estimation of rock formation mechanical properties will compensate the possible additional costs for acquiring a shear log.

  19. Predicting bed shear stress and its role in sediment dynamics and restoration potential of the Everglades and other vegetated flow systems

    USGS Publications Warehouse

    Larsen, L.G.; Harvey, J.W.; Crimaldi, J.P.

    2009-01-01

    Entrainment of sediment by flowing water affects topography, habitat suitability, and nutrient cycling in vegetated floodplains and wetlands, impacting ecosystem evolution and the success of restoration projects. Nonetheless, restoration managers lack simple decision-support tools for predicting shear stresses and sediment redistribution potential in different vegetation communities. Using a field-validated numerical model, we developed state-space diagrams that provide these predictions over a range of water-surface slopes, depths, and associated velocities in Everglades ridge and slough vegetation communities. Diminished bed shear stresses and a consequent decrease in bed sediment redistribution are hypothesized causes of a recent reduction in the topographic and vegetation heterogeneity of this ecosystem. Results confirmed the inability of present-day flows to entrain bed sediment. Further, our diagrams showed bed shear stresses to be highly sensitive to emergent vegetation density and water-surface slope but less sensitive to water depth and periphyton or floating vegetation abundance. These findings suggested that instituting a pulsing flow regime could be the most effective means to restore sediment redistribution to the Everglades. However, pulsing flows will not be sufficient to erode sediment from sloughs with abundant spikerush, unless spikerush density first decreases by natural or managed processes. Our methods provide a novel tool for identifying restoration parameters and performance measures in many types of vegetated aquatic environments where sediment erosion and deposition are involved.

  20. Incoherent holography by a Michelson type interferometer with a lens for a radial shear

    NASA Astrophysics Data System (ADS)

    Watanabe, Kaho; Nomura, Takanori

    2016-06-01

    The modified Michelson type interferometer with lenses for a radial shear to record incoherent holograms is proposed. It enables us to record a hologram by self-interference without coherent illumination such as a laser. The interferometer has two wave plates which can realize phase-shifting incoherent holography. The feature can avoid a very large bias term and the twin image, which are the inherent problem of incoherent holography by self-interference. The advantages of the proposed method using lenses and wave plates are easy adjustment of the zone plate and simplification of the optical system. A preliminary experiment using an LED as an incoherent object was performed to confirm the four step phase-shifting by wave plates.

  1. Type 1 diabetes: A predictable disease

    PubMed Central

    Simmons, Kimber M; Michels, Aaron W

    2015-01-01

    Type 1 diabetes (T1D) is an autoimmune disease characterized by loss of insulin producing beta cells and reliance on exogenous insulin for survival. T1D is one of the most common chronic diseases in childhood and the incidence is increasing, especially in children less than 5 years of age. In individuals with a genetic predisposition, an unidentified trigger initiates an abnormal immune response and the development of islet autoantibodies directed against proteins in insulin producing beta cells. There are currently four biochemical islet autoantibodies measured in the serum directed against insulin, glutamic decarboxylase, islet antigen 2, and zinc transporter 8. Development of islet autoantibodies occurs before clinical diagnosis of T1D, making T1D a predictable disease in an individual with 2 or more autoantibodies. Screening for islet autoantibodies is still predominantly done through research studies, but efforts are underway to screen the general population. The benefits of screening for islet autoantibodies include decreasing the incidence of diabetic ketoacidosis that can be life threatening, initiating insulin therapy sooner in the disease process, and evaluating safe and specific therapies in large randomized clinical intervention trials to delay or prevent progression to diabetes onset. PMID:25897349

  2. An equilibrium method for prediction of transverse shear stresses in a thick laminated plate

    NASA Technical Reports Server (NTRS)

    Chaudhuri, R. Z.

    1986-01-01

    First two equations of equilibrium are utilized to compute the transverse shear stress variation through thickness of a thick laminated plate after in-plane stresses have been computed using an assumed quadratic displacement triangular element based on transverse inextensibility and layerwise constant shear angle theory (LCST). Centroid of the triangle is the point of exceptional accuracy for transverse shear stresses. Numerical results indicate close agreement with elasticity theory. An interesting comparison between the present theory and that based on assumed stress hybrid finite element approach suggests that the latter does not satisfy the condition of free normal traction at the edge. Comparison with numerical results obtained by using constant shear angle theory suggests that LCST is close to the elasticity solution while the CST is closer to classical (CLT) solution. It is also demonstrated that the reduced integration gives faster convergence when the present theory is applied to a thin plate.

  3. Theory to Predict Shear Stress on Cells in Turbulent Blood Flow

    PubMed Central

    Morshed, Khandakar Niaz; Bark Jr., David; Forleo, Marcio; Dasi, Lakshmi Prasad

    2014-01-01

    Shear stress on blood cells and platelets transported in a turbulent flow dictates the fate and biological activity of these cells. We present a theoretical link between energy dissipation in turbulent flows to the shear stress that cells experience and show that for the case of physiological turbulent blood flow: (a) the Newtonian assumption is valid, (b) turbulent eddies are universal for the most complex of blood flow problems, and (c) shear stress distribution on turbulent blood flows is possibly universal. Further we resolve a long standing inconsistency in hemolysis between laminar and turbulent flow using the theoretical framework. This work demonstrates that energy dissipation as opposed to bulk shear stress in laminar or turbulent blood flow dictates local mechanical environment of blood cells and platelets universally. PMID:25171175

  4. Microfluidic shear stress-regulated surfactant secretion in alveolar epithelial type II cells in vitro.

    PubMed

    Mahto, Sanjeev Kumar; Tenenbaum-Katan, Janna; Greenblum, Ayala; Rothen-Rutishauser, Barbara; Sznitman, Josué

    2014-04-01

    We investigated the role of flow-induced shear stress on the mechanisms regulating surfactant secretion in type II alveolar epithelial cells (ATII) using microfluidic models. Following flow stimulation spanning a range of wall shear stress (WSS) magnitudes, monolayers of ATII (MLE-12 and A549) cells were examined for surfactant secretion by evaluating essential steps of the process, including relative changes in the number of fusion events of lamellar bodies (LBs) with the plasma membrane (PM) and intracellular redistribution of LBs. F-actin cytoskeleton and calcium levels were analyzed in A549 cells subjected to WSS spanning 4-20 dyn/cm(2). Results reveal an enhancement in LB fusion events with the PM in MLE-12 cells upon flow stimulation, whereas A549 cells exhibit no foreseeable changes in the monitored number of fusion events for WSS levels ranging up to a threshold of ∼8 dyn/cm(2); above this threshold, we witness instead a decrease in LB fusion events in A549 cells. However, patterns of LB redistribution suggest that WSS can potentially serve as a stimulus for A549 cells to trigger the intracellular transport of LBs toward the cell periphery. This observation is accompanied by a fragmentation of F-actin, indicating that disorganization of the F-actin cytoskeleton might act as a limiting factor for LB fusion events. Moreover, we note a rise in cytosolic calcium ([Ca(2+)]c) levels following stimulation of A549 cells with WSS magnitudes ranging near or above the experimental threshold. Overall, WSS stimulation can influence key components of molecular machinery for regulated surfactant secretion in ATII cells in vitro. PMID:24487389

  5. Ericksen number and Deborah number cascade predictions of a model for liquid crystalline polymers for simple shear flow

    NASA Astrophysics Data System (ADS)

    Klein, D. Harley; Leal, L. Gary; García-Cervera, Carlos J.; Ceniceros, Hector D.

    2007-02-01

    We consider the behavior of the Doi-Marrucci-Greco (DMG) model for nematic liquid crystalline polymers in planar shear flow. We found the DMG model to exhibit dynamics in both qualitative and quantitative agreement with experimental observations reported by Larson and Mead [Liq. Cryst. 15, 151 (1993)] for the Ericksen number and Deborah number cascades. For increasing shear rates within the Ericksen number cascade, the DMG model displays three distinct regimes: stable simple shear, stable roll cells, and irregular structure accompanied by disclination formation. In accordance with experimental observations, the model predicts both ±1 and ±1/2 disclinations. Although ±1 defects form via the ridge-splitting mechanism first identified by Feng, Tao, and Leal [J. Fluid Mech. 449, 179 (2001)], a new mechanism is identified for the formation of ±1/2 defects. Within the Deborah number cascade, with increasing Deborah number, the DMG model exhibits a streamwise banded texture, in the absence of disclinations and roll cells, followed by a monodomain wherein the mean orientation lies within the shear plane throughout the domain.

  6. Prediction and Observation of Sustained Oscillations in a Sheared Liquid Crystalline Polymer

    NASA Astrophysics Data System (ADS)

    Grosso, M.; Crescitelli, S.; Somma, E.; Vermant, J.; Moldenaers, P.; Maffettone, P. L.

    2003-03-01

    Experimental observations of sustained oscillations of both shear stress and first normal stress differences are reported in flowing liquid crystalline polymers in a limited range of shear rates. The results can be described by considering the response of a rigid-rod model. Depending on the initial conditions, the frequency spectrum of the stress signal contains either one or two characteristic frequencies. This can be explained by the occurrence of either pure “wagging” or the coexistence of wagging and “log-rolling” behavior of the director.

  7. Impact of turbulence on the prediction of linear aeroacoustic interactions: Acoustic response of a turbulent shear layer

    NASA Astrophysics Data System (ADS)

    Gikadi, Jannis; Föller, Stephan; Sattelmayer, Thomas

    2014-12-01

    A powerful model to predict aeroacoustic interactions in the linear regime is the perturbed compressible linearized Navier-Stokes equations. Thus far, the frequently employed derivation suggests that the effect of turbulence and its associated Reynolds stresses is neglected and a quasi-laminar model is employed. In this paper, dynamic perturbation equations are derived incorporating the effect of turbulence and its interaction with perturbation quantities. This is done by employing a triple decomposition of the instantaneous variables. The procedure results in a closure problem for the Reynolds stresses for which a linear eddy-viscosity model is proposed. The resulting perturbation equations are applied to a grazing flow in a T-joint for which strong shear layer instabilities at certain frequencies are experimentally observed. Passive scattering properties of the grazing flow are validated against the experiments performed by Karlsson and Åbom and perturbation equations being quasi-laminar. We find that prediction models must include the effect of Reynolds stresses to capture the aeroacoustic interaction effects correctly. Neglecting its effect naturally results in the over prediction of vortex growth at the frequencies of shear layer instability and therewith in an over prediction of aeroacoustic interactions.

  8. A study of the second and third order closure models of turbulence for prediction of separated shear flows

    NASA Technical Reports Server (NTRS)

    Amano, R. S.

    1985-01-01

    The hybrid model of the Reynolds-stress turbulence closure is tested for the computation of the flows over a step and disk. Here it is attempted to improve the redistributive action of the turbulence energy among the Reynolds stresses. By evaluating the existing models for the pressure-strain correlation, better coefficients are obtained for the prediction of separating shear flows. Furthermore, the diffusion rate of the Reynolds stresses is reevaluated adopting several algebraic correlations for the triple-velocity products. The models of Cormack et al., Daly-Harlow, Hanjalic-Launder, and Shir were tested for the reattaching shear flows. It was generally observed that all these algebraic models give considerably low values of the triple-velocity products. This is attributed to the fact that none of the algebraic models can take the convective effect of the triple-velocity products into account in the separating shear flows, thus resulting in much lower diffusion rate than Reynolds stresses. In order to improve the evaluation of these quantities correction factors are introduced based on the comparison with some experimental data.

  9. Establishment of a model predicting tensile shear strength and fracture portion of laser-welded lap joints

    NASA Astrophysics Data System (ADS)

    Furusako, Seiji; Miyazaki, Yasunobu; Hashimoto, Koji; Kobayashi, Junichi

    2003-03-01

    This study was aimed at establishment of a model that can predict tensile shear strength and fracture portion laser-welded lap joints in the tensile test. To clear influence of the bead length and width on them, the joints employed steel sheets with a thickness in the range of 0.8 mm to 1.2 mm were evaluated. It was found that the tensile shear strength increased with the bead size, and the fracture occurred at base metal (BM), weld metal (WM) or portion between them with a curvature (referred to as portion R). Also to clarify rotational deformation process around WM during the tensile test, joint cross-sections were observed at some applied load levels in the test. This observation derived the relationship between the radius, Ri, at the inner plane of portion R and the rotational angle, θ, of the center of sheet thickness, and the relationship between Ri and applied load. A plastic analysis based on these functions and assumptions that the joint consists of BM, WM and R, which are under simplified stress mode respectively, could estimate the tensile shear strength and the fracture portion of the joints. This estimation made good accord with experimental results.

  10. Predicting wind shear effects: A study of Minnesota wind data collected at heights up to 70 meters

    SciTech Connect

    Artig, R.

    1997-12-31

    The Minnesota Department of Public Service (DPS) collects wind data at carefully selected sites around the state and analyzes the data to determine Minnesota`s wind power potential. DPS recently installed advanced new monitoring equipment at these sites and began to collect wind data at 30, 50, and 70 meters above ground level, with two anemometers at each level. Previously, the Department had not collected data at heights above ground level higher than 30 meters. DPS also, with the U.S. Department of Energy (DOE), installed four sophisticated monitoring sites as part of a Tall Tower Wind Shear Study that is assessing the effects of wind shear on wind power potential. At these sites, wind data are being collected at the 10, 30, 40, 50, 60, and 70 meter heights. This paper presents the preliminary results of the analysis of wind data from all sites. These preliminary results indicate that the traditional 1/7 power law does not effectively predict wind shear in Minnesota, and the result is an underestimation of Minnesota`s wind power potential at higher heights. Using a power factor of 1/5 or 1/4 may be more accurate and provide sound justification for installing wind turbines on taller towers in Minnesota.

  11. Establishing Correlations for Predicting Tensile Properties Based on the Shear Punch Test and Vickers Microhardness data

    NASA Astrophysics Data System (ADS)

    Milot, Timothy S.

    A series of mechanical tests was performed on a matrix of pressure vessel alloys to establish correlations between shear punch tests (SPT), microhardness (Hv), and tensile data. The purpose is to estimate tensile properties from SPT and Hv data. Small specimen testing is central to characterization of irradiation-induced changes in alloys used for nuclear applications. SPT have the potential for estimating tensile yield and ultimate strengths, strain hardening and ductility data, by using TEM disks, for example. Additional insight into SPT was gained by performing finite element analysis (FEA) simulations.

  12. Energy consumption in terms of shear stress for two types of membrane bioreactors used for municipal wastewater treatment processes

    NASA Astrophysics Data System (ADS)

    Ratkovich, Nicolas; Bentzen, Thomas R.; Rasmussen, Michael R.

    2012-10-01

    Two types of submerged membrane bioreactors (MBR): hollow fiber (HF) and hollow sheet (HS), have been studied and compared in terms of energy consumption and average shear stress over the membrane wall. The analysis of energy consumption was made using the correlation to determine the blower power and the blower power demand per unit of permeate volume. Results showed that for the system geometries considered, in terms the of the blower power, the HF MBR requires less power compared to HS MBR. However, in terms of blower power per unit of permeate volume, the HS MBR requires less energy. The analysis of shear stress over the membrane surface was made using computational fluid dynamics (CFD) modelling. Experimental measurements for the HF MBR were compared with the CFD model and an error less that 8% was obtained. For the HS MBR, experimental measurements of velocity profiles were made and an error of 11% was found. This work uses an empirical relationship to determine the shear stress based on the ratio of aeration blower power to tank volume. This relationship is used in bubble column reactors and it is extrapolate to determine shear stress on MBR systems. This relationship proved to be overestimated by 28% compared to experimental measurements and CFD results. Therefore, a corrective factor is included in the relationship in order to account for the membrane placed inside the bioreactor.

  13. Prediction of shear damage of plasmid DNA in pump and centrifuge operations using an ultra scale-down device.

    PubMed

    Zhang, Hu; Kong, Simyee; Booth, Andrew; Boushaba, Rihab; Levy, M Susana; Hoare, Michael

    2007-01-01

    Supercoiled circular (SC) plasmid DNA is often subjected to fluid stress in large-scale manufacturing processes. It is thus important to characterize the engineering environment within a particular unit operation as well as within the associated ancillary equipment during process design for plasmid DNA manufacture so as to avoid shear-induced degradation of the SC isoform, which would compromise product efficacy in therapeutic applications. In the past few years, ultra scale-down (USD) tools were developed within our laboratory to mimic the engineering environments experienced by biomolecules within a range of manufacturing-scale ancillary, primary recovery, and purification operations, using milliliter quantities of material. Through the use of a USD shear device, the effect of elongational strain rate on SC plasmid DNA degradation was studied in this paper, and from that, the impact of a centrifugal pump, a Mono pump, and a disk-stack centrifuge feed zone on SC plasmid DNA degradation was predicted and experimentally verified at scale. Model predictions, over the range of conditions studied, were in good agreement with experimental values, demonstrating the potential of the USD approach as a decisional tool during bioprocess design. PMID:17672520

  14. Static compressive strength prediction of open-hole structure based on non-linear shear behavior and micro-mechanics

    NASA Astrophysics Data System (ADS)

    Li, Wangnan; Cai, Hongneng; Li, Chao

    2014-11-01

    This paper deals with the characterization of the strength of the constituents of carbon fiber reinforced plastic laminate (CFRP), and a prediction of the static compressive strength of open-hole structure of polymer composites. The approach combined with non-linear analysis in macro-level and a linear elastic micromechanical failure analysis in microlevel (non-linear MMF) is proposed to improve the prediction accuracy. A face-centered cubic micromechanics model is constructed to analyze the stresses in fiber and matrix in microlevel. Non-interactive failure criteria are proposed to characterize the strength of fiber and matrix. The non-linear shear behavior of the laminate is studied experimentally, and a novel approach of cubic spline interpolation is used to capture significant non-linear shear behavior of laminate. The user-defined material subroutine UMAT for the non-linear share behavior is developed and combined in the mechanics analysis in the macro-level using the Abaqus Python codes. The failure mechanism and static strength of open-hole compressive (OHC) structure of polymer composites is studied based on non-linear MMF. The UTS50/E51 CFRP is used to demonstrate the application of theory of non-linear MMF.

  15. Sheared-type G(anti).C(syn) base-pair: a unique d(GXC) loop closure motif.

    PubMed

    Chin, Ko-Hsin; Chou, Shan-Ho

    2003-05-30

    Stable DNA loop structures closed by a novel G.C base-pair have been determined for the single-residue d(GXC) loops (X=A, T, G or C) in low-salt solution by high-resolution nuclear magnetic resonance (NMR) techniques. The closing G.C base-pair in these loops is not of the canonical Watson-Crick type, but adopts instead a unique sheared-type (trans Watson-Crick/sugar-edge) pairing, like those occurring in the sheared mismatched G.A or A.C base-pair, to draw the two opposite strands together. The cytidine residue in the closing base-pair is transformed into the rare syn domain to form two H-bonds with the guanine base and to prevent the steric clash between the G 2NH(2) and the C H-5 protons. Besides, the sugar pucker of the syn cytidine is still located in the regular C2'-endo domain, unlike the C3'-endo domain adopted for the pyrimidines of the out-of-alternation left-handed Z-DNA structure. The facile formation of the compact d(GXC) loops closed by a unique sheared-type G(anti).C(syn) base-pair demonstrates the great potential of the single-stranded d(GXC) triplet repeats to fold into stable hairpins. PMID:12758081

  16. Tertiary creep test by ring shear apparatus in predicting initiation time of rainfall-induced-shallow landslide

    NASA Astrophysics Data System (ADS)

    Dok, A.; Fukuoka, H.

    2010-12-01

    Landslides are complex geo-disaters that frequently occur due to certain causes, but only one trigger such as earthquake or heavy rainfall or other related natural phenomenas. A slope failure seldom occurs without any creep deformation. Failure time of a slope as found by Fukuzono (1985) and Siato (1965) based on graphical analysis of extensometer monitoring data through large scale flume test for landslide studies, logarithm of acceleration is proportional to the logarithm of velocity of surface displacement immediately before the failure. It is expressed as d2x/dt2 = A(dx/dt)α, where x is surface displacement, t is time, and A and α are constant. And, Fukuzono (1985, 1989) proposed a simple method of predicting the time of falure by the inverse velocity (1/v) mean. The curve of inverse velocity is concave at 1< α<2, linear at α=2, and convex at α>2. Recently, Minamitani (2007) have researched on mechanism of Tertiary Creep deformation for landslide failure time prediction by increasing shear-stress development in order to understand the story behind the empirical relationship found by senior researcher Fukozono. He found a strong relationshp between constants A and α, expressed as α = 0.1781A+ 1.814. For deeper understanding, this study aims at learning in more detail on mechanism of landslides in tropical soils by ring shear apparatus (invented by DPRI, Disaster Prevention Research Institute) based on Tertiary Creep deformation theory in help issue warning on rainfall-induced landslides through back (pore-water) pressure control tests under combined conditions of particular normal stress and shear stress with pore-water pressure changes to simulate the potential sliding surface condition in the heavy rainfall, which no body experiences conducting such a test series, particularly by applying cyclic and actual groundwater change pattern to the soils. To reach the archivement, serie of back pressure control test were implemented by utilising stress

  17. Feasibility Study of Texture Analysis Using Ultrasound Shear Wave Elastography to Predict Malignancy in Thyroid Nodules.

    PubMed

    Bhatia, Kunwar Suryaveer Singh; Lam, Absalom Chung Lung; Pang, Sze Wing Angel; Wang, Defeng; Ahuja, Anil Tejbhan

    2016-07-01

    Textural analysis of ultrasound shear wave elastography (SWE) was evaluated to discriminate benign and malignant thyroid nodules. Sixteen papillary thyroid cancers and 89 benign hyperplastic nodules in 105 patients underwent SWE using four static pre-compression levels. Fifteen gray level co-occurrence matrix textural features and six absolute SWE indices were computed from SWE images. Diagnostic performances of each SWE index for malignancy were calculated and compared using the area under the receiver operating characteristic curve (AUC), and optimal models were generated at each pre-compression level. The optimal model comprised two SWE textural features at the highest pre-compression level, which attained AUC, sensitivity and specificity of 0.973, 97.5% and 90.0%, respectively. By comparison, absolute SWE indices attained AUC of 0.709 as well as 18.8% sensitivity and 95.8% specificity. These preliminary results suggest SWE textural analysis can distinguish benign and malignant thyroid nodules and SWE spatial heterogeneity is greater in malignant nodules. PMID:27126245

  18. A grillage model for predicting wrinkles in annular graphene under circular shearing

    SciTech Connect

    Zhang, Z.; Duan, W. H.; Wang, C. M.

    2013-01-07

    This paper is concerned with a Timoshenko grillage model for modeling the wrinkling phenomenon in annular graphene under circular shearing applied at its inner edge. By calibrating the grillage model results against the molecular mechanics (MM) results, the grillage model comprising beams of elliptical cross-section orientated along the carbon-carbon bond has section dimensions of 0.06 nm for the major axis length and 0.036 nm for the minor axis length. Moreover, the beams are connected to one another at 0.00212 nm from the geometric centric. This eccentric connection of beams allows the proposed grillage model to cater for the cross-couplings among bonds that produce the out-of-plane wrinkling pattern. The out-of-plane to in-plane bending stiffnesses' ratio is 0.36, and the cross bending stiffness provided by the ellipse eccentricity is 0.025 times that of the in-plane bending stiffness. Besides furnishing identical wave numbers as well as amplitudes and wavelengths that are in good agreement with MM results, the grillage model can capture wrinkling patterns with a boundary layer, whereas plate and membrane models could not mimic the boundary layer.

  19. A Method for Predicting Protein-Protein Interaction Types

    PubMed Central

    Silberberg, Yael

    2014-01-01

    Protein-protein interactions (PPIs) govern basic cellular processes through signal transduction and complex formation. The diversity of those processes gives rise to a remarkable diversity of interactions types, ranging from transient phosphorylation interactions to stable covalent bonding. Despite our increasing knowledge on PPIs in humans and other species, their types remain relatively unexplored and few annotations of types exist in public databases. Here, we propose the first method for systematic prediction of PPI type based solely on the techniques by which the interaction was detected. We show that different detection methods are better suited for detecting specific types. We apply our method to ten interaction types on a large scale human PPI dataset. We evaluate the performance of the method using both internal cross validation and external data sources. In cross validation, we obtain an area under receiver operating characteristic (ROC) curve ranging from 0.65 to 0.97 with an average of 0.84 across the predicted types. Comparing the predicted interaction types to external data sources, we obtained significant agreements for phosphorylation and ubiquitination interactions, with hypergeometric p-value = 2.3e−54 and 5.6e−28 respectively. We examine the biological relevance of our predictions using known signaling pathways and chart the abundance of interaction types in cell processes. Finally, we investigate the cross-relations between different interaction types within the network and characterize the discovered patterns, or motifs. We expect the resulting annotated network to facilitate the reconstruction of process-specific subnetworks and assist in predicting protein function or interaction. PMID:24625764

  20. Evaluation of carbonate pore system under texture control for prediction of microporosity aspect ratio and shear wave velocity

    NASA Astrophysics Data System (ADS)

    Lima Neto, Irineu A.; Misságia, Roseane M.; Ceia, Marco A.; Archilha, Nathaly L.; Hollis, Cathy

    2015-06-01

    This work evaluates a suite of carbonate rocks from Albian age in the Campos Basin - Brazil, complemented by data from the literature, totaling 472 samples with detailed description of diagenetic features, quantitative mineralogy analyses, and P- and S-wave velocities (Vp and Vs) measured at three ranges of effective pressure loading: low (5-7.5 MPa), moderate (20 MPa) and high (40-50 MPa) values. Digital image analysis (DIA) was applied on microtomography (μCT) images to quantitatively describe the macro-mesopore system of the Albian carbonates, and was extended to characterize different textures from literature data to estimate reference values for carbonates. The methodology utilized to predict the aspect ratio of microporosity assumes three pore-space scales in two representative scenarios: 1) measured macro-mesopore aspect ratio from DIA, and 2) predicted microporosity aspect ratio, using Vp measurement as the main input parameter. The differential effective medium model (DEMM) is combined with analytical theories of data analysis to characterize microporosity. Shear modulus and microporosity aspect ratio calibrated by this methodology were used to predict Vs, which was compared to experimental data, resulting in a good match for all samples. Polynomial curves are fitted with a variety of carbonate textures by velocities at effective pressure and bulk porosity crossplots, establishing important relationships for velocity prediction. The effects of effective pressure on the pore system within dry plugs of Albian samples were evaluated by combining triaxial measurements at 0-10 MPa, relative pore volume reduction (RPVR) and microporosity aspect ratio prediction. According to the results, micropores that exhibit low aspect ratio tend to close with stress and cause an increase on Vp and Vs. A wide textural heterogeneity of data base and different digital image analysis and resolutions were employed successfully, combining rock physics methodologies and concepts

  1. Prediction equations for Warner-Bratzler shear force using principal component regression analysis in Brahman-influenced Venezuelan cattle.

    PubMed

    Jerez-Timaure, N; Huerta-Leidenz, N; Ortega, J; Rodas-González, A

    2013-03-01

    A database consisting of 331 beef animals (Brahman-crossbred) was used to determine the multivariate relationships between carcass and beef palatability traits of Venezuelan cattle and to develop prediction equations for Warner-Bratzler shear force (WBSF). The first three principal components (PC) explained 77.53% of the standardized variance. Equations were obtained for each sex class and the total variability observed in WBSF could be explained by its orthogonal regression with carcass weight (CW), fat cover (FC), fat thickness (FT), and skeletal maturity (SM). Prediction equations were: WBSF(steers)=3.566+0.003(CW)-0.033(FC)-0.015(FT)+0.0004(SM); WBSF(heifers)=4.824+0.002(CW)-0.229(FC)+0.096(FT)-0.064(SM); WBSF(bulls)=3.516+0.009(CW)+0.154(FC)-0.129(FT)-0.006(SM). A higher proportion of the variation was explained by the PC when variables of greater weight were selected to define each PC. The equation set presented herein could become an important tool to improve the Venezuelan carcass grading system. PMID:23261538

  2. Stress Heterogeneities in Sheared Type-I Collagen Networks Revealed by Boundary Stress Microscopy

    PubMed Central

    Arevalo, Richard C.; Kumar, Pramukta; Urbach, Jeffrey S.; Blair, Daniel L.

    2015-01-01

    Disordered fiber networks provide structural support to a wide range of important materials, and the combination of spatial and dynamic complexity may produce large inhomogeneities in mechanical properties, an effect that is largely unexplored experimentally. In this work, we introduce Boundary Stress Microscopy to quantify the non-uniform surface stresses in sheared collagen gels. We find local stresses exceeding average stresses by an order of magnitude, with variations over length scales much larger than the network mesh size. The strain stiffening behavior observed over a wide range of network mesh sizes can be parameterized by a single characteristic strain and associated stress, which describes both the strain stiffening regime and network yielding. The characteristic stress is approximately proportional to network density, but the peak boundary stress at both the characteristic strain and at yielding are remarkably insensitive to concentration. PMID:25734484

  3. Predictive Effects of Online Peer Feedback Types on Performance Quality

    ERIC Educational Resources Information Center

    Yu, Fu-Yun; Wu, Chun-Ping

    2013-01-01

    This study examined the individual and combined predictive effects of two types of feedback (i.e., quantitative ratings and descriptive comments) in online peer-assessment learning systems on the quality of produced work. A total of 233 students participated in the study for six weeks. An online learning system that allows students to contribute…

  4. Do Different Facets of Impulsivity Predict Different Types of Aggression?

    PubMed Central

    Derefinko, Karen; DeWall, C. Nathan; Metze, Amanda V.; Walsh, Erin C.; Lynam, Donald R.

    2011-01-01

    The current study examined the relations between impulsivity-related traits (as assessed by the UPPS-P Impulsive Behavior Scale) and aggressive behaviors. Results indicated that UPPS-P Lack of Premeditation and Sensation Seeking were important in predicting general violence. In contrast, UPPS-P Urgency was most useful in predicting intimate partner violence. To further explore relations between intimate partner violence and Urgency, a measure of autonomic response to pleasant and aversive stimuli and facets of Neuroticism from the NEO PI-R were used as control variables. Autonomic responsivity was correlated with intimate partner violence at the zero-order level, and predicted significant variance in intimate partner violence in regression equations. However, UPPS-P Urgency was able to account for unique variance in intimate partner violence above and beyond measures of Neuroticism and arousal. Implications regarding the use of a multifaceted conceptualization of impulsivity in the prediction of different types of violent behavior are discussed. PMID:21259270

  5. Do different facets of impulsivity predict different types of aggression?

    PubMed

    Derefinko, Karen; DeWall, C Nathan; Metze, Amanda V; Walsh, Erin C; Lynam, Donald R

    2011-01-01

    This study examined the relations between impulsivity-related traits (as assessed by the UPPS-P Impulsive Behavior Scale) and aggressive behaviors. Results indicated that UPPS-P Lack of Premeditation and Sensation Seeking were important in predicting general violence. In contrast, UPPS-P Urgency was most useful in predicting intimate partner violence. To further explore relations between intimate partner violence and Urgency, a measure of autonomic response to pleasant and aversive stimuli and facets of Neuroticism from the NEO PI-R were used as control variables. Autonomic responsivity was correlated with intimate partner violence at the zero-order level, and predicted significant variance in intimate partner violence in regression equations. However, UPPS-P Urgency was able to account for unique variance in intimate partner violence, above and beyond measures of Neuroticism and arousal. Implications regarding the use of a multifaceted conceptualization of impulsivity in the prediction of different types of violent behavior are discussed. PMID:21259270

  6. Prediction of Type II Burst Radiation for Large CME Events

    NASA Astrophysics Data System (ADS)

    Cairns, I. H.; Schmidt, J. M.

    2013-12-01

    Type IIs are associated with shocks in the corona and solar wind, either driven by CMEs or else blast waves. Recent quantitative theories for type II radiation show that the amount of radiation depends on the speed and spatial extent of the 3D shock, as well as on the background plasma, magnetic field configuration, and the number of superthermal electrons available for acceleration by the shock. In principle, then, Type II bursts may provide 1-3 day warnings of large and fast CMEs that might produce space weather at Earth. In this paper we couple the advanced 3D MHD BATS-R-US code of Toth, Gombosi, and colleagues with our new ``bolt-on'' theory for type II emission. The modeling includes initialization with coronal and active region magnetic fields reconstructed from solar magnetograms, coronal densities determined by 1 AU data, and CMEs modelled using STEREO coronagraph data. Two events with type IIs and strong CMEs are analyzed: 15 February 2011 and 7 March 2012. We demonstrate impressive accuracy in time, frequency, and intensity for both type II bursts. This strongly supports the type II theory, implies real understanding of the physics involved, and supports the near-term development of a capability to predict and track these events for space weather prediction.

  7. The shear bond strength of MTA with three different types of adhesive systems: An in vitro study

    PubMed Central

    Tyagi, Nimish; Chaman, Chandrakar; Tyagi, Shashi Prabha; Singh, Udai Pratap; Sharma, Apoorv

    2016-01-01

    Aim: To evaluate the shear bond strength of MTA with three different types of adhesive systems- self-adhering flowable composite, etch and rinse adhesive system and self etch adhesive system. Methodology: MTA specimens (n = 60) were prepared using cylindrical acrylic blocks, having a central cavity with 4 mm diameter and 2 mm depth. MTA was mixed and placed in the prepared cavity, and was covered with a moist cotton pellet and temporary filling material. The specimens were divided into 3 groups which were further divided into 2 sub-groups (45 Minutes and 24 hours). After the application of bonding agents composite resin was placed over the MTA surface. The specimens were tested for shear bond strength and readings were statically analyzed. Result: After 24 hrs the mean value of etch and rinse group was significantly higher than self etch and the self adhering composite groups. Among the 45 minutes groups there were no significant difference. Conclusion: In single visit after 45 minutes self adhering flowable can be used successfully as a final restorative material in place of conventional flowable composite without using any alternative adhesive system over MTA. PMID:27099417

  8. Alterations in wall shear stress predict sites of neointimal hyperplasia after stent implantation in rabbit iliac arteries.

    PubMed

    LaDisa, John F; Olson, Lars E; Molthen, Robert C; Hettrick, Douglas A; Pratt, Phillip F; Hardel, Michael D; Kersten, Judy R; Warltier, David C; Pagel, Paul S

    2005-05-01

    Restenosis resulting from neointimal hyperplasia (NH) limits the effectiveness of intravascular stents. Rates of restenosis vary with stent geometry, but whether stents affect spatial and temporal distributions of wall shear stress (WSS) in vivo is unknown. We tested the hypothesis that alterations in spatial WSS after stent implantation predict sites of NH in rabbit iliac arteries. Antegrade iliac artery stent implantation was performed under angiography, and blood flow was measured before casting 14 or 21 days after implantation. Iliac artery blood flow domains were obtained from three-dimensional microfocal X-ray computed tomography imaging and reconstruction of the arterial casts. Indexes of WSS were determined using three-dimensional computational fluid dynamics. Vascular histology was unchanged proximal and distal to the stent. Time-dependent NH was localized within the stented region and was greatest in regions exposed to low WSS and acute elevations in spatial WSS gradients. The lowest values of WSS spatially localized to the stented area of a theoretical artery progressively increased after 14 and 21 days as NH occurred within these regions. This NH abolished spatial disparity in distributions of WSS. The results suggest that stents may introduce spatial alterations in WSS that modulate NH in vivo. PMID:15653759

  9. Predictive data modeling of human type II diabetes related statistics

    NASA Astrophysics Data System (ADS)

    Jaenisch, Kristina L.; Jaenisch, Holger M.; Handley, James W.; Albritton, Nathaniel G.

    2009-04-01

    During the course of routine Type II treatment of one of the authors, it was decided to derive predictive analytical Data Models of the daily sampled vital statistics: namely weight, blood pressure, and blood sugar, to determine if the covariance among the observed variables could yield a descriptive equation based model, or better still, a predictive analytical model that could forecast the expected future trend of the variables and possibly eliminate the number of finger stickings required to montior blood sugar levels. The personal history and analysis with resulting models are presented.

  10. Application Of A New Semi-Empirical Model For Forming Limit Prediction Of Sheet Material Including Superposed Loads Of Bending And Shearing

    SciTech Connect

    Held, Christian; Liewald, Mathias; Schleich, Ralf; Sindel, Manfred

    2010-06-15

    The use of lightweight materials offers substantial strength and weight advantages in car body design. Unfortunately such kinds of sheet material are more susceptible to wrinkling, spring back and fracture during press shop operations. For characterization of capability of sheet material dedicated to deep drawing processes in the automotive industry, mainly Forming Limit Diagrams (FLD) are used. However, new investigations at the Institute for Metal Forming Technology have shown that High Strength Steel Sheet Material and Aluminum Alloys show increased formability in case of bending loads are superposed to stretching loads. Likewise, by superposing shearing on in plane uniaxial or biaxial tension formability changes because of materials crystallographic texture. Such mixed stress and strain conditions including bending and shearing effects can occur in deep-drawing processes of complex car body parts as well as subsequent forming operations like flanging. But changes in formability cannot be described by using the conventional FLC. Hence, for purpose of improvement of failure prediction in numerical simulation codes significant failure criteria for these strain conditions are missing. Considering such aspects in defining suitable failure criteria which is easy to implement into FEA a new semi-empirical model has been developed considering the effect of bending and shearing in sheet metals formability. This failure criterion consists of the combination of the so called cFLC (combined Forming Limit Curve), which considers superposed bending load conditions and the SFLC (Shear Forming Limit Curve), which again includes the effect of shearing on sheet metal's formability.

  11. Application Of A New Semi-Empirical Model For Forming Limit Prediction Of Sheet Material Including Superposed Loads Of Bending And Shearing

    NASA Astrophysics Data System (ADS)

    Held, Christian; Liewald, Mathias; Schleich, Ralf; Sindel, Manfred

    2010-06-01

    The use of lightweight materials offers substantial strength and weight advantages in car body design. Unfortunately such kinds of sheet material are more susceptible to wrinkling, spring back and fracture during press shop operations. For characterization of capability of sheet material dedicated to deep drawing processes in the automotive industry, mainly Forming Limit Diagrams (FLD) are used. However, new investigations at the Institute for Metal Forming Technology have shown that High Strength Steel Sheet Material and Aluminum Alloys show increased formability in case of bending loads are superposed to stretching loads. Likewise, by superposing shearing on in plane uniaxial or biaxial tension formability changes because of materials crystallographic texture. Such mixed stress and strain conditions including bending and shearing effects can occur in deep-drawing processes of complex car body parts as well as subsequent forming operations like flanging. But changes in formability cannot be described by using the conventional FLC. Hence, for purpose of improvement of failure prediction in numerical simulation codes significant failure criteria for these strain conditions are missing. Considering such aspects in defining suitable failure criteria which is easy to implement into FEA a new semi-empirical model has been developed considering the effect of bending and shearing in sheet metals formability. This failure criterion consists of the combination of the so called cFLC (combined Forming Limit Curve), which considers superposed bending load conditions and the SFLC (Shear Forming Limit Curve), which again includes the effect of shearing on sheet metal's formability.

  12. BETTY: prediction of beta-strand type from sequence.

    PubMed

    Zimmermann, Olav; Wang, Longhui; Hansmann, Ulrich H E

    2007-01-01

    Most secondary structure prediction programs do not distinguish between parallel and antiparallel beta-sheets. However, such knowledge would constrain the available topologies of a protein significantly, and therefore aid existing fold recognition algorithms. For this reason, we propose a technique which, in combination with existing secondary structure programs such as PSIPRED, allows one to distinguish between parallel and antiparallel beta-sheets. We propose the use of a support vector machine (SVM) procedure, BETTY, to predict parallel and antiparallel sheets from sequence. We found that there is a strong signal difference in the sequence profiles which SVMs can efficiently extract. With strand type assignment accuracies of 90.7% and 83.3% for antiparallel and parallel strands, respectively, our method adds considerably to existing information on current 3-class secondary structure predictions. BETTY has been implemented as an online service which academic researchers can access from our website http://www.fz-juelich.de/nic/cbb/service/service.php. PMID:18391242

  13. The Effect of Test Machine Compliance on the Measured Shear Punch Yield Stress as Predicted Using Finite Element Analysis

    SciTech Connect

    Toloczko, Mychailo; Abe, Katsunori; Hamilton, Margaret L.; Garner, Francis A.; Kurtz, Richard J.

    2001-10-01

    In previous research involving the use of the shear punch test, it was assumed that the displacement of the punch tip was only slightly different than the crosshead displacement. The present work explores this assumption and its ramifications by simulating the shear punch test with finite element analysis (FEA). The simulations suggest that punch tip displacement is much less than previously assumed, and that for the test frames which have been used, crosshead displacement is over an order of magnitude greater than punch tip displacement. This difference in displacements is thought to be due to test machine and punch compliance, and a simple elasticity calculation of the compliance of the punch, the test machine, and a specimen gives a result which is in agreement with the FEA simulations. The effect of using punch tip displacement on the observed effective shear yield stress was evaluated using FEA simulated shear punch tests on several different metals. Yield was measured at several different offset shear strains with a 1.0% offset shear yield strength measurement providing the best correlation with 0.2% offset uniaxial yield strength. When using the 1.0% offset shear yield values, the previously observed material-to-material variability in the tensile-shear correlation all but disappeared. Based on this work, it appears that the material-to-material variations in prior correlations between uniaxial yield strength and shear yield strength is due to a combination of large test machine compliance and material-to-material differences in the work hardening exponent.

  14. WASHOUT CONDITION OF CLUMP-TYPE GRASS CONSIDERING THE CHANGE OF THE REFERENCE VELOCITY AND SHEAR STRESS IN THE VEGETATED AREA

    NASA Astrophysics Data System (ADS)

    Hara, Tatsuaki; Tanaka, Norio

    Threshold shear stress for removing grasses by flood is important but is not well understood quantitatively for clump-type vegetation, Eragrostis curvula. New model for calculating the velocities in the vegetated layer and the surface layer was proposed and the model was validated with flume experiments. The bed shear stress in vegetation was calculated by the momentum balance in the vegetated layer, and was applied for evaluating the wash-out conditions of the grass. The threshold value for removing the clump-type vegetation was evaluated as a rate of shear stress of d90, grain diameter at which 90% volume passed through the sieve, and the critical shear stress of d90, WOI. The critical WOI for removing the grass is 1.9-2.1, and 1.8-1.9 for one layer analysis, and two layer analysis, respectively. The critical shear stress inside the vegetated region does not decrease much because there is bare land between each clump-type grass, and the flow is accelerated in the region by the momentum exchange.

  15. On the appearance of vorticity and gradient shear bands in wormlike micellar solutions of different CPCl/salt systems

    SciTech Connect

    Mütze, Annekathrin Heunemann, Peggy; Fischer, Peter

    2014-11-01

    Wormlike micellar salt/surfactant solutions (X-salicylate, cetylpyridinium chloride) are studied with respect to the applied shear stress, concentration, temperature, and composition of the counterions (X = lithium, sodium, potassium, magnesium, and calcium) of the salicylate salt solute to determine vorticity and gradient shear bands. A combination of rheological measurements, laser technique, video analysis, and rheo-small-angle neutron scattering allow for a detailed exploration of number and types of shear bands. Typical flow curves of the solutions show Newtonian, shear-thinning, and shear-thickening flow behavior. In the shear-thickening regime, the solutions show vorticity and gradient shear bands simultaneously, in which vorticity shear bands dominate the visual effect, while gradient shear bands always coexist and predominate the rheological response. It is shown that gradient shear bands change their phases (turbid, clear) with the same frequency as the shear rate oscillates, whereas vorticity shear bands change their phases with half the frequency of the shear rate. Furthermore, we show that with increasing molecular mass of the counterions the number of gradient shear bands increases, while the number of vorticity shear bands remains constant. The variation of temperature, shear stress, concentration, and counterions results in a predictable change in the rheological behavior and therefore allows adjustment of the number of vorticity shear bands in the shear band regime.

  16. Diagnostic accuracy of shear wave elastography for prediction of breast malignancy in patients with pathological nipple discharge

    PubMed Central

    Guo, Xiaobo; Liu, Ying; Li, Wanhu

    2016-01-01

    Objectives Pathological nipple discharge (PND) may indicate malignant breast lesions. As the role of shear wave elastography (SWE) in predicting these malignant lesions has not yet been evaluated, we aim to evaluate the diagnostic value of SWE for this condition. Design Prospective diagnostic accuracy study comparing a combination of qualitative and quantitative measurements of SWE (index test) to a ductoscopy and microdochectomy for histological diagnosis (reference test). Setting Fuzhou General Hospital of Nanjing military command. Participants A total of 379 patients with PND were finally included from January, 2011 to March 2014, after we screened 1084 possible candidates. All participants were evaluated through SWE, with qualitative parameters generated by Virtual Touch tissue imaging (VTI) and quantitative parameters generated by Virtual Touch tissue quantification (VTQ). All the patients were consented to receive a ductoscopy and microdochectomy for histological diagnosis, and the results were set as a reference test. Outcome measures Sensitivity and specificity of the combined VTI and VTQ of the SWE for detection of malignancy in patients with PND. Results The 379 participants presented with 404 lesions. The results of pathological examination showed that 326 (80.7%) of the 404 lesions were benign and the other 78 (19.3%) were malignant. An area under the curve of elasticity score, VTQm and VTQc, were 0.872, 0.825 and 0.857, respectively, with the corresponding cut-off point as 2.50, 2.860 m/s and 3.015 m/s, respectively. After a combination of these measurements, the sensitivity, specificity, and positive and negative predictive value (PPV and NPV), were 89.7%, 72.1%, 43.5% and 96.7%, respectively. The sensitivity analysis showed 82% of the sensitivity and 96.8% of the specificity, in which patients with no pathological findings in ductoscopy were excluded. Conclusions Ultrasonographic elastography is sensitive for patients with PND and could be used

  17. Predicting aphasia type from brain damage measured with structural MRI.

    PubMed

    Yourganov, Grigori; Smith, Kimberly G; Fridriksson, Julius; Rorden, Chris

    2015-12-01

    Chronic aphasia is a common consequence of a left-hemisphere stroke. Since the early insights by Broca and Wernicke, studying the relationship between the loci of cortical damage and patterns of language impairment has been one of the concerns of aphasiology. We utilized multivariate classification in a cross-validation framework to predict the type of chronic aphasia from the spatial pattern of brain damage. Our sample consisted of 98 patients with five types of aphasia (Broca's, Wernicke's, global, conduction, and anomic), classified based on scores on the Western Aphasia Battery (WAB). Binary lesion maps were obtained from structural MRI scans (obtained at least 6 months poststroke, and within 2 days of behavioural assessment); after spatial normalization, the lesions were parcellated into a disjoint set of brain areas. The proportion of damage to the brain areas was used to classify patients' aphasia type. To create this parcellation, we relied on five brain atlases; our classifier (support vector machine - SVM) could differentiate between different kinds of aphasia using any of the five parcellations. In our sample, the best classification accuracy was obtained when using a novel parcellation that combined two previously published brain atlases, with the first atlas providing the segmentation of grey matter, and the second atlas used to segment the white matter. For each aphasia type, we computed the relative importance of different brain areas for distinguishing it from other aphasia types; our findings were consistent with previously published reports of lesion locations implicated in different types of aphasia. Overall, our results revealed that automated multivariate classification could distinguish between aphasia types based on damage to atlas-defined brain areas. PMID:26465238

  18. Magnetohydrodynamic equilibria in the vicinity of an X -type neutral line specified by footpoint shear

    SciTech Connect

    Finn, J.M.; Lau, Y. )

    1991-09-01

    Results pertaining to two-dimensional ({partial derivative}/{partial derivative}{ital z}=0) magnetohydrodynamic equilibria in the presence of an {ital X}-type neutral line are presented. Naive analyses indicate that there may be tangential discontinuities in {bold B}, specifically discontinuities in {ital B}{sub {ital z}} across the separatrix connected to the {ital X} line. However, such analyses indicate an infinite {ital z} component of footpoint displacement (or safety factor {ital q} in the toroidal case) at the separatrix. The solutions presented here allow the specification of footpoint displacement (or safety factor {ital q}) that is finite as the separatrix is approached. These solutions are scale-invariant, or similarity, solutions. They are appropriate near the {ital X} line on length scales intermediate between the boundary layer width because of resistivity (or other nonideal effects) and the macroscopic length scale. Force balance across the separatrix implies identical radial dependence in all four quadrants and continuity of {ital B}{sup 2}{sub {ital z}} across the separatrix. The latter shows that there are two classes of solutions: those with {ital B}{sub {ital z}} continuous across the separatrix and those with {vert bar}{ital B}{sub {ital z}}{vert bar} continuous but with a sign change in {ital B}{sub {ital z}}. The former class has fractional power-law singularities at the separatrix. The latter class has, in addition, a sheet current along the separatrix in the {ital x}-{ital y} plane associated with the jump in {ital B}{sub {ital z}}. Detailed properties of these solutions are explored. In particular, sheetlike one-dimensional solutions are found to be limiting cases of the general solutions. Except for one special case, these sheet solutions cannot have finite footpoint displacement if they are force free, but can in the presence of pressure gradient.

  19. Increased Inlet Blood Flow Velocity Predicts Low Wall Shear Stress in the Cephalic Arch of Patients with Brachiocephalic Fistula Access

    PubMed Central

    Boghosian, Michael; Cassel, Kevin; Watson, Sydeaka; Funaki, Brian; Doshi, Taral; Mahmoudzadeh Akherat, S. M. Javid; Hines, Jane; Coe, Fredric

    2016-01-01

    Background An autogenous arteriovenous fistula is the optimal vascular access for hemodialysis. In the case of brachiocephalic fistula, cephalic arch stenosis commonly develops leading to access failure. We have hypothesized that a contribution to fistula failure is low wall shear stress resulting from post-fistula creation hemodynamic changes that occur in the cephalic arch. Methods Twenty-two subjects with advanced renal failure had brachiocephalic fistulae placed. The following procedures were performed at mapping (pre-operative) and at fistula maturation (8–32 weeks post-operative): venogram, Doppler to measure venous blood flow velocity, and whole blood viscosity. Geometric and computational modeling was performed to determine wall shear stress and other geometric parameters. The relationship between hemodynamic parameters and clinical findings was examined using univariate analysis and linear regression. Results The percent low wall shear stress was linearly related to the increase in blood flow velocity (p < 0.01). This relationship was more significant in non-diabetic patients (p < 0.01) than diabetic patients. The change in global measures of arch curvature and asymmetry also evolve with time to maturation (p < 0.05). Conclusions The curvature and hemodynamic changes during fistula maturation increase the percentage of low wall shear stress regions within the cephalic arch. Low wall shear stress may contribute to subsequent neointimal hyperplasia and resultant cephalic arch stenosis. If this hypothesis remains tenable with further studies, ways of protecting the arch through control of blood flow velocity may need to be developed. PMID:27074019

  20. Shear Thinning in Xenon

    NASA Technical Reports Server (NTRS)

    Bergm Robert F.; Moldover, Michael R.; Yao, Minwu; Zimmerli, Gregory A.

    2009-01-01

    We measured shear thinning, a viscosity decrease ordinarily associated with complex liquids such as molten plastics or ketchup, near the critical point of xenon. The data span a wide range of dimensionless shear rate: the product of the shear rate and the relaxation time of critical fluctuations was greater than 0.001 and was less than 700. As predicted by theory, shear thinning occurred when this product was greater than 1. The measurements were conducted aboard the Space Shuttle Columbia to avoid the density stratification caused by Earth's gravity.

  1. An approximate semi-analytical method for prediction of interlaminar shear stresses in an arbitrarily laminated thick plate

    NASA Technical Reports Server (NTRS)

    Chaudhuri, Reaz A.; Seide, Paul

    1987-01-01

    An approximate semianalytical method for determination of interlaminar shear stress distribution through the thickness of an arbitrarily laminated thick plate has been presented. The method is based on the assumptions of transverse inextensibility and layerwise constant shear angle theory (LCST) and utilizes an assumed quadratic displacement potential energy based finite element method (FEM). Centroid of the triangular surface has been proved from a rigorous mathematical point of view (Aubin-Nitsche theory), to be the point of exceptional accuracy for the interlaminar shear stresses. Numerical results indicate close agreement with the available three-dimensional elasticity theory solutions. A comparison between the present theory and that due to an assumed stress hybrid FEM suggest that the (normal) traction-free-edge condition is not satisfied in the latter approach. Furthermore, the present paper is the first to present the results for interlaminar shear stresses in a two-layer thick square plate of balanced unsymmetric angle-ply construction. A comparison with the recently proposed Equilibrium Method (EM) indicates the superiority of the present method, because the latter assures faster convergence as well as simultaneous vanishing of the transverse shear stresses on both of the exposed surfaces of the laminate. Superiority of the present method over the EM, in the case of a symmetric laminate, is limited to faster convergence alone. It has also been demonstrated that the combination of the present method and the reduced (quadratic order) numerical integration scheme yields convergence of the interlaminar shear stresses almost as rapidly as that of the nodal displacements, in the case of a thin plate.

  2. Application of a soft computing technique in predicting the percentage of shear force carried by walls in a rectangular channel with non-homogeneous roughness.

    PubMed

    Khozani, Zohreh Sheikh; Bonakdari, Hossein; Zaji, Amir Hossein

    2016-01-01

    Two new soft computing models, namely genetic programming (GP) and genetic artificial algorithm (GAA) neural network (a combination of modified genetic algorithm and artificial neural network methods) were developed in order to predict the percentage of shear force in a rectangular channel with non-homogeneous roughness. The ability of these methods to estimate the percentage of shear force was investigated. Moreover, the independent parameters' effectiveness in predicting the percentage of shear force was determined using sensitivity analysis. According to the results, the GP model demonstrated superior performance to the GAA model. A comparison was also made between the GP program determined as the best model and five equations obtained in prior research. The GP model with the lowest error values (root mean square error ((RMSE) of 0.0515) had the best function compared with the other equations presented for rough and smooth channels as well as smooth ducts. The equation proposed for rectangular channels with rough boundaries (RMSE of 0.0642) outperformed the prior equations for smooth boundaries. PMID:26744942

  3. A- to B-Type Olivine Fabric Transitions Associated with Hydration, Dehydration and Shear Above the Farallon Flat Slab

    NASA Astrophysics Data System (ADS)

    Behr, W. M.; Smith, D.

    2014-12-01

    We investigate mantle rocks associated with hydration, dehydration and shear above the Farallon flat-slab at its contact with the base of North America. The rocks we focus on are ultramafic inclusions hosted within serpentinized ultramafic microbreccia diatremes of the Navajo Volcanic Field (New Mexico) that erupted to the surface at the waning stages of the Laramide orogeny. A large number of petrological and geochronological studies have pinpointed the origin of these rocks to the hydrated mantle wedge above the Farallon slab as well as tectonically eroded and entrained fragments of the plate interface. We combine petrological observations and EBSD measurements of olivine grainsize and LPO to examine the effects of hydration on olivine fabric development in different parts of the supra-subduction zone mantle. The rocks examined include weakly deformed to strongly foliated tectonites we interpret to represent partially hydrated fragments of the upper plate mantle; and mylonites and ultramylonites we interpret to represent deformed fragments of the plate interface. The rocks deformed at temperatures ranging from 500-900°C based on thermometry, and olivine compositions in some record heating just before incorporation in the diatreme mix. We observe the following: Tectonites exhibit A-type bulk olivine LPOs, but show transitions to B-type LPO in local, fine-grained, dynamically recrystallized regions associated with hydrous minerals. Mylonites and ultramylonites with stable chlorite and/or antigorite and recrystallized grainsizes of less than 10μm show strong B-type olivine LPOs. A single mylonite with recrystallized grainsizes of ~35μm shows evidence for prograde metamorphism and dehydration through the chlorite breakdown reaction at temperatures above ~770°C. It contains no hydrous minerals and shows a strong A-type olivine LPO. Together these rocks demonstrate a strong correlation between hydration under high stress conditions, and B-type olivine LPO

  4. Replicability and 40-Year Predictive Power of Childhood ARC Types

    PubMed Central

    Chapman, Benjamin P.; Goldberg, Lewis R.

    2011-01-01

    We examined three questions surrounding the Undercontrolled, Overcontrolled, and Resilient--or Asendorpf-Robins-Caspi (ARC)--personality types originally identified by Block (1971). In analyses of the teacher personality assessments of over 2,000 children in 1st through 6th grade in 1959-1967, and follow-up data on general and cardiovascular health outcomes in over 1,100 adults recontacted 40 years later, we found: (1) Bootstrapped internal replication clustering suggested that Big Five scores were best characterized by a tripartite cluster structure corresponding to the ARC types; (2) this cluster structure was fuzzy, rather than discrete, indicating that ARC constructs are best represented as gradients of similarity to three prototype Big Five profiles; and (3) ARC types and degrees of ARC prototypicality showed associations with multiple health outcomes 40 years later. ARC constructs were more parsimonious, but neither better nor more consistent predictors than the dimensional Big Five traits. Forty-year incident cases of heart disease could be correctly identified with 68% accuracy by personality information alone, a figure approaching the 12-year accuracy of a leading medical cardiovascular risk model. Findings support the theoretical validity of ARC constructs, their treatment as continua of prototypicality rather than discrete categories, and the need for further understanding the robust predictive power of childhood personality traits for mid-life health. PMID:21744975

  5. Replicability and 40-year predictive power of childhood ARC types.

    PubMed

    Chapman, Benjamin P; Goldberg, Lewis R

    2011-09-01

    We examined 3 questions surrounding the undercontrolled, overcontrolled, and resilient-or Asendorpf-Robins-Caspi (ARC)-personality types originally identified by Block (1971). In analyses of the teacher personality assessments of over 2,000 children in 1st through 6th grade in 1959-1967 and follow-up data on general and cardiovascular health outcomes in over 1,100 adults recontacted 40 years later, we found bootstrapped internal replication clustering suggesting that Big Five scores were best characterized by a tripartite cluster structure corresponding to the ARC types. This cluster structure was fuzzy rather than discrete, indicating that ARC constructs are best represented as gradients of similarity to 3 prototype Big Five profiles; ARC types and degrees of ARC prototypicality showed associations with multiple health outcomes 40 years later. ARC constructs were more parsimonious but, depending on the outcome, comparable or slightly worse classifiers than the dimensional Big Five traits. Forty-year incident cases of heart disease could be correctly identified with 67% accuracy by childhood personality information alone and stroke incidence with over 70% accuracy. Findings support the theoretical validity of ARC constructs, their treatment as continua of prototypicality rather than discrete categories, and the need for further understanding the robust predictive power of childhood personality for midlife health. PMID:21744975

  6. Computational simulations predict a key role for oscillatory fluid shear stress in de novo valvular tissue formation.

    PubMed

    Salinas, Manuel; Ramaswamy, Sharan

    2014-11-01

    Previous efforts in heart valve tissue engineering demonstrated that the combined effect of cyclic flexure and steady flow on bone marrow derived stem cell-seeded scaffolds resulted in significant increases in engineered collagen formation [Engelmayr et al. Cyclic flexure and laminar flow synergistically accelerate mesenchymal stem cell-mediated engineered tissue formation: Implications for engineered heart valve tissues. Biomaterials 2006; 27(36): 6083-95]. Here, we provide a new interpretation for the underlying reason for this observed effect. In addition, another related investigation demonstrated the impact of fluid flow on DNA content and quantified the fluid-induced shear stresses on the engineered heart valve tissue specimens [Engelmayr et al. A Novel Flex-Stretch-Flow Bioreactor for the Study of Engineered Heart Valve Tissue Mechanobiology]. Annals of Biomedical Engineering 2008, 36, 1-13]. In this study, we performed more advanced CFD analysis with an emphasis on oscillatory wall shear stresses imparted on specimens when mechanically conditioned by a combination of cyclic flexure and steady flow. Specifically, we hypothesized that the dominant stimulatory regulator of the bone marrow stem cells is fluid-induced and depends on both the magnitude and temporal directionality of surface stresses, i.e., oscillatory shear stresses (OSS) acting on the developing tissues. Therefore, we computationally quantified the (i) magnitude of fluid-induced shear stresses as well as (ii) the extent of temporal fluid oscillations in the flow field using the oscillatory shear index (OSI) parameter. Noting that sample cyclic flexure induces a high degree of OSS, we incorporated moving boundary computational fluid dynamic simulations of samples housed within a bioreactor to consider the effects of: (1) No Flow, No Flexure (control group), (2) Steady Flow-alone, (3) Cyclic Flexure-alone and (4) Combined Steady flow and Cyclic Flexure environments. Indeed we found that the

  7. Flight in low-level wind shear

    NASA Technical Reports Server (NTRS)

    Frost, W.

    1983-01-01

    Results of studies of wind shear hazard to aircraft operation are summarized. Existing wind shear profiles currently used in computer and flight simulator studies are reviewed. The governing equations of motion for an aircraft are derived incorporating the variable wind effects. Quantitative discussions of the effects of wind shear on aircraft performance are presented. These are followed by a review of mathematical solutions to both the linear and nonlinear forms of the governing equations. Solutions with and without control laws are presented. The application of detailed analysis to develop warning and detection systems based on Doppler radar measuring wind speed along the flight path is given. A number of flight path deterioration parameters are defined and evaluated. Comparison of computer-predicted flight paths with those measured in a manned flight simulator is made. Some proposed airborne and ground-based wind shear hazard warning and detection systems are reviewed. The advantages and disadvantages of both types of systems are discussed.

  8. Predicting erythropoietin resistance in hemodialysis patients with type 2 diabetes

    PubMed Central

    2013-01-01

    Background Resistance to ESAs (erythropoietin stimulating agents) is highly prevalent in hemodialysis patients with diabetes and associated with an increased mortality. The aim of this study was to identify predictors for ESA resistance and to develop a prediction model for the risk stratification in these patients. Methods A post-hoc analysis was conducted of the 4D study, including 1015 patients with type 2 diabetes undergoing hemodialysis. Determinants of ESA resistance were identified by univariate logistic regression analyses. Subsequently, multivariate models were performed with stepwise inclusion of significant predictors from clinical parameters, routine laboratory and specific biomarkers. Results In the model restricted to clinical parameters, male sex, shorter dialysis vintage, lower BMI, history of CHF, use of ACE-inhibitors and a higher heart rate were identified as independent predictors of ESA resistance. In regard to routine laboratory markers, lower albumin, lower iron saturation, higher creatinine and higher potassium levels were independently associated with ESA resistance. With respect to specific biomarkers, higher ADMA and CRP levels as well as lower Osteocalcin levels were predictors of ESA resistance. Conclusions Easily obtainable clinical parameters and routine laboratory parameters can predict ESA resistance in diabetic hemodialysis patients with good discrimination. Specific biomarkers did not meaningfully further improve the risk prediction of ESA resistance. Routinely assessed data can be used in clinical practice to stratify patients according to the risk of ESA resistance, which may help to assign appropriate treatment strategies. Clinical trial registration The study was registered at the German medical authority (BfArM; registration number 401 3206). The sponsor protocol ID and clinical trial unique identified number was CT-981-423-239. The results of the study are published and available at http

  9. Tryptophan Predicts the Risk for Future Type 2 Diabetes.

    PubMed

    Chen, Tianlu; Zheng, Xiaojiao; Ma, Xiaojing; Bao, Yuqian; Ni, Yan; Hu, Cheng; Rajani, Cynthia; Huang, Fengjie; Zhao, Aihua; Jia, Weiping; Jia, Wei

    2016-01-01

    Recently, 5 amino acids were identified and verified as important metabolites highly associated with type 2 diabetes (T2D) development. This report aims to assess the association of tryptophan with the development of T2D and to evaluate its performance with existing amino acid markers. A total of 213 participants selected from a ten-year longitudinal Shanghai Diabetes Study (SHDS) were examined in two ways: 1) 51 subjects who developed diabetes and 162 individuals who remained metabolically healthy in 10 years; 2) the same 51 future diabetes and 23 strictly matched ones selected from the 162 healthy individuals. Baseline fasting serum tryptophan concentrations were quantitatively measured using ultra-performance liquid chromatography triple quadruple mass spectrometry. First, serum tryptophan level was found significantly higher in future T2D and was positively and independently associated with diabetes onset risk. Patients with higher tryptophan level tended to present higher degree of insulin resistance and secretion, triglyceride and blood pressure. Second, the prediction potential of tryptophan is non-inferior to the 5 existing amino acids. The predictive performance of the combined score improved after taking tryptophan into account. Our findings unveiled the potential of tryptophan as a new marker associated with diabetes risk in Chinese populations. The addition of tryptophan provided complementary value to the existing amino acid predictors. PMID:27598004

  10. GPIbα-vWF rolling under shear stress shows differences between type 2B and 2M von Willebrand disease.

    PubMed

    Coburn, L A; Damaraju, V S; Dozic, S; Eskin, S G; Cruz, M A; McIntire, L V

    2011-01-19

    Both type 2B and type 2M von Willebrand disease result in bleeding disorders; however, whereas type 2B has increased binding affinity between platelet glycoprotein Ibα and von Willebrand factor (vWF), type 2M has decreased binding affinity between these two molecules. We used R687E type 2B and G561S type 2M vWF-A1 mutations to study binding between flowing platelets and insolubilized vWF mutants. We measured rolling velocities, mean stop times, and mean go times at 37°C using high-speed video microscopy. The rolling velocities for wt-wt interactions first decrease, reach a minimum, and then increase with increasing shear stress, indicating a catch-slip transition. By changing the viscosity, we were able to quantify the effects of force versus shear rate for rolling velocities and mean stop times. Platelet interactions with loss-of-function vWF-A1 retain the catch-slip bond transition seen in wt-wt interactions, but at a higher shear stress compared with the wt-wt transition. The mean stop time for all vWF-A1 molecules reveals catch-slip transitions at different shear stresses (gain-of-function vWF-A1 < wt vWF-A1< loss-of-function vWF-A1). The shift in the catch-slip transition may indicate changes in how the different mutants become conformationally active, indicating different mechanisms leading to similar bleeding characteristics. PMID:21244826

  11. Predicting the liquefaction phenomena from shear velocity profiling: Empirical approach to 6.3 Mw, May 2006 Yogyakarta earthquake

    NASA Astrophysics Data System (ADS)

    Hartantyo, Eddy; Brotopuspito, Kirbani S.; Sismanto, Waluyo

    2015-04-01

    The liquefactions phenomena have been reported after a shocking 6.5Mw earthquake hit Yogyakarta province in the morning at 27 May 2006. Several researchers have reported the damage, casualties, and soil failure due to the quake, including the mapping and analyzing the liquefaction phenomena. Most of them based on SPT test. The study try to draw the liquefaction susceptibility by means the shear velocity profiling using modified Multichannel Analysis of Surface Waves (MASW). This paper is a preliminary report by using only several measured MASW points. The study built 8-channel seismic data logger with 4.5 Hz geophones for this purpose. Several different offsets used to record the high and low frequencies of surface waves. The phase-velocity diagrams were stacked in the frequency domain rather than in time domain, for a clearer and easier dispersion curve picking. All codes are implementing in Matlab. From these procedures, shear velocity profiling was collected beneath each geophone's spread. By mapping the minimum depth of shallow water table, calculating PGA with soil classification, using empirical formula for saturated soil weight from shear velocity profile, and calculating CRR and CSR at every depth, the liquefaction characteristic can be identify in every layer. From several acquired data, a liquefiable potential at some depth below water table was obtained.

  12. Predicting the liquefaction phenomena from shear velocity profiling: Empirical approach to 6.3 Mw, May 2006 Yogyakarta earthquake

    SciTech Connect

    Hartantyo, Eddy; Brotopuspito, Kirbani S.; Sismanto; Waluyo

    2015-04-24

    The liquefactions phenomena have been reported after a shocking 6.5Mw earthquake hit Yogyakarta province in the morning at 27 May 2006. Several researchers have reported the damage, casualties, and soil failure due to the quake, including the mapping and analyzing the liquefaction phenomena. Most of them based on SPT test. The study try to draw the liquefaction susceptibility by means the shear velocity profiling using modified Multichannel Analysis of Surface Waves (MASW). This paper is a preliminary report by using only several measured MASW points. The study built 8-channel seismic data logger with 4.5 Hz geophones for this purpose. Several different offsets used to record the high and low frequencies of surface waves. The phase-velocity diagrams were stacked in the frequency domain rather than in time domain, for a clearer and easier dispersion curve picking. All codes are implementing in Matlab. From these procedures, shear velocity profiling was collected beneath each geophone’s spread. By mapping the minimum depth of shallow water table, calculating PGA with soil classification, using empirical formula for saturated soil weight from shear velocity profile, and calculating CRR and CSR at every depth, the liquefaction characteristic can be identify in every layer. From several acquired data, a liquefiable potential at some depth below water table was obtained.

  13. von Willebrand disease type 2A phenotypes IIC, IID and IIE: A day in the life of shear-stressed mutant von Willebrand factor.

    PubMed

    Brehm, M A; Huck, V; Aponte-Santamaría, C; Obser, T; Grässle, S; Oyen, F; Budde, U; Schneppenheim, S; Baldauf, C; Gräter, F; Schneider, S W; Schneppenheim, R

    2014-07-01

    The bleeding disorder von Willebrand disease (VWD) is caused by mutations of von Willebrand factor (VWF), a multimeric glycoprotein essential for platelet-dependent primary haemostasis. VWD type 2A-associated mutations each disrupt VWF biosynthesis and function at different stages, depending on the VWF domain altered by the mutation. These effects cause considerable heterogeneity in phenotypes and symptoms. To characterise the molecular mechanisms underlying the specific VWF deficiencies in VWD 2A/IIC, IID and IIE, we investigated VWF variants with patient-derived mutations either in the VWF pro-peptide or in domains D3 or CK. Additionally to static assays and molecular dynamics (MD) simulations we used microfluidic approaches to perform a detailed investigation of the shear-dependent function of VWD 2A mutants. For each group, we found distinct characteristics in their intracellular localisation visualising specific defects in biosynthesis which are correlated to respective multimer patterns. Using microfluidic assays we further determined shear flow-dependent characteristics in polymer-platelet-aggregate formation, platelet binding and string formation for all mutants. The phenotypes observed under flow conditions were not related to the mutated VWF domain. By MD simulations we further investigated how VWD 2A/IID mutations might alter the ability of VWF to form carboxy-terminal dimers. In conclusion, our study offers a comprehensive picture of shear-dependent and shear-independent dysfunction of VWD type 2A mutants. Furthermore, our microfluidic assay might open new possibilities for diagnosis of new VWD phenotypes and treatment choice for VWD patients with shear-dependent VWF dysfunctions that are currently not detectable by static tests. PMID:24598842

  14. Prediction of self-diffusion coefficient and shear viscosity of water and its binary mixtures with methanol and ethanol by molecular simulation.

    PubMed

    Guevara-Carrion, Gabriela; Vrabec, Jadran; Hasse, Hans

    2011-02-21

    Density, self-diffusion coefficient, and shear viscosity of pure liquid water are predicted for temperatures between 280 and 373 K by molecular dynamics simulation and the Green-Kubo method. Four different rigid nonpolarizable water models are assessed: SPC, SPC/E, TIP4P, and TIP4P/2005. The pressure dependence of the self-diffusion coefficient and the shear viscosity for pure liquid water is also calculated and the anomalous behavior of these properties is qualitatively well predicted. Furthermore, transport properties as well as excess volume and excess enthalpy of aqueous binary mixtures containing methanol or ethanol, based on the SPC/E and TIP4P/2005 water models, are calculated. Under the tested conditions, the TIP4P/2005 model gives the best quantitative and qualitative agreement with experiments for the regarded transport properties. The deviations from experimental data are of 5% to 15% for pure liquid water and 5% to 20% for the water + alcohol mixtures. Moreover, the center of mass power spectrum of water as well as the investigated mixtures are analyzed and the hydrogen-bonding structure is discussed for different states. PMID:21341860

  15. Prediction of self-diffusion coefficient and shear viscosity of water and its binary mixtures with methanol and ethanol by molecular simulation

    NASA Astrophysics Data System (ADS)

    Guevara-Carrion, Gabriela; Vrabec, Jadran; Hasse, Hans

    2011-02-01

    Density, self-diffusion coefficient, and shear viscosity of pure liquid water are predicted for temperatures between 280 and 373 K by molecular dynamics simulation and the Green-Kubo method. Four different rigid nonpolarizable water models are assessed: SPC, SPC/E, TIP4P, and TIP4P/2005. The pressure dependence of the self-diffusion coefficient and the shear viscosity for pure liquid water is also calculated and the anomalous behavior of these properties is qualitatively well predicted. Furthermore, transport properties as well as excess volume and excess enthalpy of aqueous binary mixtures containing methanol or ethanol, based on the SPC/E and TIP4P/2005 water models, are calculated. Under the tested conditions, the TIP4P/2005 model gives the best quantitative and qualitative agreement with experiments for the regarded transport properties. The deviations from experimental data are of 5% to 15% for pure liquid water and 5% to 20% for the water + alcohol mixtures. Moreover, the center of mass power spectrum of water as well as the investigated mixtures are analyzed and the hydrogen-bonding structure is discussed for different states.

  16. A Discrete Element Model for Predicting Shear Strength and Degradation of Rock Joint by Using Compressive and Tensile Test Data

    NASA Astrophysics Data System (ADS)

    Kazerani, T.; Yang, Z. Y.; Zhao, J.

    2012-09-01

    A discrete element model is proposed to examine rock strength and failure. The model is implemented by UDEC, which is developed for this purpose. The material is represented as a collection of irregular-sized deformable particles interacting at their cohesive boundaries. The interface between two adjacent particles is viewed as a flexible contact whose constitutive law controls the material fracture and fragmentation properties. To reproduce rock anisotropy, an orthotropic cohesive law is developed for the contacts, which allows their shear and tensile behaviors to be different from each other. Using a combination of original closed-form expressions and statistical calibrations, a unique set of the contact microparameters are found based on the uniaxial/triaxial compression and Brazilian tension test data of a plaster. Applying the obtained microparameters, joint specimens, made of the same plaster, are simulated, where the comparison of the obtained results to laboratory data shows a reasonable agreement.

  17. Very High Resolution Numerical Weather Prediction of Wind Shear Event in the Complex Terrain Around Juneau Alaska

    NASA Astrophysics Data System (ADS)

    Morton, D.; Arnold, D.; Schicker, I.; Dierking, C.; Harrison, K.

    2011-12-01

    Juneau International Airport is surrounded by complex terrain, often presenting challenging conditions to departing aircraft. General aviation departure procedures for Runway 08 include a 180-degree right turn "as soon as practical" in order to avoid steeply rising terrain. Under strong wind conditions characterized by post-frontal topographically enhanced wind shear, aircraft following these procedures may encounter turbulence or wind shear classified as severe. In January 1993, a Boeing 727 aircraft at a 30-degree bank encountered extreme crosswinds resulting in departure from controlled flight, with successful recovery occurring within only 50 meters of the ground. In this work, we focus on a similar event at Juneau from December 2009. This case has been modeled with WRF at very high resolutions down to 111 m horizontal, with mixed results. The focus of this work is to investigate in more detail the problems, costs and benefits of using very high resolution topography and model runs in a high-wind event in complex terrain. Several model runs will be performed, and results will be compared with each other and station observations available through the Juneau Airport Wind System (JAWS). Two high resolution topographies - the USGS National Elevation Dataset (NED) and the Shuttle Radar Topography Mission (SRTM) - will be compared with the USGS 30s topography in their ability to match the real topography and their influence on forecast winds. Additionally, an attempt will be made to push the model into the realm of Large Eddy Simulation (LES) with a 50 m horizontal resolution in a limited region.

  18. Elevation in blood flow and shear rate prevents hyperglycemia-induced endothelial dysfunction in healthy subjects and those with type 2 diabetes.

    PubMed

    Greyling, Arno; Schreuder, Tim H A; Landman, Thijs; Draijer, Richard; Verheggen, Rebecca J H M; Hopman, Maria T E; Thijssen, Dick H J

    2015-03-01

    Hyperglycemia, commonly present after a meal, causes transient impairment in endothelial function. We examined whether increases in blood flow (BF) protect against the hyperglycemia-mediated decrease in endothelial function in healthy subjects and patients with type 2 diabetes mellitus (T2DM). Ten healthy subjects and 10 age- and sex-matched patients with T2DM underwent simultaneous bilateral assessment of brachial artery endothelial function by means of flow-mediated dilation (FMD) using high-resolution echo-Doppler. FMD was examined before and 60, 120, and 150 min after a 75-g oral glucose challenge. We unilaterally manipulated BF by heating one arm between minute 30 and minute 60. Oral glucose administration caused a statistically significant, transient increase in blood glucose in both groups (P < 0.001). Forearm skin temperature, brachial artery BF, and shear rate significantly increased in the heated arm (P < 0.001), and to a greater extent compared with the nonheated arm in both groups (interaction effect P < 0.001). The glucose load caused a transient decrease in FMD% (P < 0.05), whereas heating significantly prevented the decline (interaction effect P < 0.01). Also, when correcting for changes in diameter and shear rate, we found that the hyperglycemia-induced decrease in FMD can be prevented by local heating (P < 0.05). These effects on FMD were observed in both groups. Our data indicate that nonmetabolically driven elevation in BF and shear rate can similarly prevent the hyperglycemia-induced decline in conduit artery endothelial function in healthy volunteers and in patients with type 2 diabetes. Additional research is warranted to confirm that other interventions that increase BF and shear rate equally protect the endothelium when challenged by hyperglycemia. PMID:25593286

  19. Wavenumber prediction and measurement of axisymmetric waves in buried fluid-filled pipes: Inclusion of shear coupling at a lubricated pipe/soil interface

    NASA Astrophysics Data System (ADS)

    Muggleton, J. M.; Yan, J.

    2013-03-01

    Acoustic methods have been widely used to detect water leaks in buried fluid-filled pipes, and these technologies also have the potential to locate buried pipes and cables. Relatively predictable for metal pipes, there is considerably more uncertainty with plastic pipes, as the wave propagation behaviour becomes highly coupled between the pipe wall, the contained fluid and surrounding medium. Based on the fully three-dimensional effect of the surrounding soil, pipe equations for n=0 axisymmetric wave motion are derived for a buried, fluid-filled pipe. The characteristics of propagation and attenuation are analysed for two n=0 waves, the s=1 wave and s=2 wave, which correspond to a predominantly fluid-borne wave and a compressional wave predominantly in the shell, respectively. At the pipe/soil interface, two extreme cases may be considered in order to investigate the effects of shear coupling: the "slip" condition representing lubricated contact; and the "no slip" condition representing compact contact. Here, the "slip" case is considered, for which, at low frequencies, analytical expressions can be derived for the two wavenumbers, corresponding to the s=1 and s=2 waves. These are both then compared with the situations in which there is no surrounding soil and in which the pipe is surrounded by fluid only, which cannot support shear. It is found that the predominant effect of shear at the pipe/soil interface is to add stiffness along with damping due to radiation. For the fluid-dominated wave, this causes the wavespeed to increase and increases the wave attenuation. For the shell-dominated wave there is little effect on the wavespeed but a marked increase in wave attenuation. Comparison with experimental measurements confirms the theoretical findings.

  20. Prediction of fracture healing under axial loading, shear loading and bending is possible using distortional and dilatational strains as determining mechanical stimuli

    PubMed Central

    Steiner, Malte; Claes, Lutz; Ignatius, Anita; Niemeyer, Frank; Simon, Ulrich; Wehner, Tim

    2013-01-01

    Numerical models of secondary fracture healing are based on mechanoregulatory algorithms that use distortional strain alone or in combination with either dilatational strain or fluid velocity as determining stimuli for tissue differentiation and development. Comparison of these algorithms has previously suggested that healing processes under torsional rotational loading can only be properly simulated by considering fluid velocity and deviatoric strain as the regulatory stimuli. We hypothesize that sufficient calibration on uncertain input parameters will enhance our existing model, which uses distortional and dilatational strains as determining stimuli, to properly simulate fracture healing under various loading conditions including also torsional rotation. Therefore, we minimized the difference between numerically simulated and experimentally measured courses of interfragmentary movements of two axial compressive cases and two shear load cases (torsional and translational) by varying several input parameter values within their predefined bounds. The calibrated model was then qualitatively evaluated on the ability to predict physiological changes of spatial and temporal tissue distributions, based on respective in vivo data. Finally, we corroborated the model on five additional axial compressive and one asymmetrical bending load case. We conclude that our model, using distortional and dilatational strains as determining stimuli, is able to simulate fracture-healing processes not only under axial compression and torsional rotation but also under translational shear and asymmetrical bending loading conditions. PMID:23825112

  1. Prediction of fracture healing under axial loading, shear loading and bending is possible using distortional and dilatational strains as determining mechanical stimuli.

    PubMed

    Steiner, Malte; Claes, Lutz; Ignatius, Anita; Niemeyer, Frank; Simon, Ulrich; Wehner, Tim

    2013-09-01

    Numerical models of secondary fracture healing are based on mechanoregulatory algorithms that use distortional strain alone or in combination with either dilatational strain or fluid velocity as determining stimuli for tissue differentiation and development. Comparison of these algorithms has previously suggested that healing processes under torsional rotational loading can only be properly simulated by considering fluid velocity and deviatoric strain as the regulatory stimuli. We hypothesize that sufficient calibration on uncertain input parameters will enhance our existing model, which uses distortional and dilatational strains as determining stimuli, to properly simulate fracture healing under various loading conditions including also torsional rotation. Therefore, we minimized the difference between numerically simulated and experimentally measured courses of interfragmentary movements of two axial compressive cases and two shear load cases (torsional and translational) by varying several input parameter values within their predefined bounds. The calibrated model was then qualitatively evaluated on the ability to predict physiological changes of spatial and temporal tissue distributions, based on respective in vivo data. Finally, we corroborated the model on five additional axial compressive and one asymmetrical bending load case. We conclude that our model, using distortional and dilatational strains as determining stimuli, is able to simulate fracture-healing processes not only under axial compression and torsional rotation but also under translational shear and asymmetrical bending loading conditions. PMID:23825112

  2. Prediction of Vocal Severity within and across Voice Types.

    ERIC Educational Resources Information Center

    Wolfe, Virginia I.; Steinfatt, Thomas M.

    1987-01-01

    Evaluation of the /a/ and /i/ sounds of 51 adult subjects with various laryngeal disorders indicated that spectrographic noise and curvilinear derivatives of the period standard deviation provided the best predictions of disorder severity. (Author/DB)

  3. Predicting Student Academic Performance in an Engineering Dynamics Course: A Comparison of Four Types of Predictive Mathematical Models

    ERIC Educational Resources Information Center

    Huang, Shaobo; Fang, Ning

    2013-01-01

    Predicting student academic performance has long been an important research topic in many academic disciplines. The present study is the first study that develops and compares four types of mathematical models to predict student academic performance in engineering dynamics--a high-enrollment, high-impact, and core course that many engineering…

  4. Generation of SH-type waves due to shearing stress discontinuity in a sandy layer overlying an isotropic and inhomogeneous elastic half-space

    NASA Astrophysics Data System (ADS)

    Pal, Prakash; Mandal, Dinbandhu

    2014-02-01

    The generation of SH-type waves due to sudden application of a stress discontinuity which moves after creation at the sandy layer of finite thickness overlying an isotropic and inhomogeneous elastic half-space is considered. The displacements are obtained in exact form by the method due to Cagniard modified by De Hoop. The numerical calculations are obtained. Two cases of shearing stress discontinuities are considered for different sandiness parameters. The graphs are drawn to show the effect of sandiness in the displacement components.

  5. A Leonard-Sanders-Budiansky-Koiter-Type Nonlinear Shell Theory with a Hierarchy of Transverse-Shearing Deformations

    NASA Technical Reports Server (NTRS)

    Nemeth, Michael P.

    2013-01-01

    A detailed exposition on a refined nonlinear shell theory suitable for nonlinear buckling analyses of laminated-composite shell structures is presented. This shell theory includes the classical nonlinear shell theory attributed to Leonard, Sanders, Koiter, and Budiansky as an explicit proper subset. This approach is used in order to leverage the exisiting experience base and to make the theory attractive to industry. In addition, the formalism of general tensors is avoided in order to expose the details needed to fully understand and use the theory. The shell theory is based on "small" strains and "moderate" rotations, and no shell-thinness approximations are used. As a result, the strain-displacement relations are exact within the presumptions of "small" strains and "moderate" rotations. The effects of transverse-shearing deformations are included in the theory by using analyst-defined functions to describe the through-the-thickness distributions of transverse-shearing strains. Constitutive equations for laminated-composite shells are derived without using any shell-thinness approximations, and simplified forms and special cases are presented.

  6. Representation of Vegetation and Other Nonerodible Elements in Aeolian Shear Stress Partitioning Models for Predicting Transport Threshold

    NASA Technical Reports Server (NTRS)

    King, James; Nickling, William G.; Gillies, John A.

    2005-01-01

    The presence of nonerodible elements is well understood to be a reducing factor for soil erosion by wind, but the limits of its protection of the surface and erosion threshold prediction are complicated by the varying geometry, spatial organization, and density of the elements. The predictive capabilities of the most recent models for estimating wind driven particle fluxes are reduced because of the poor representation of the effectiveness of vegetation to reduce wind erosion. Two approaches have been taken to account for roughness effects on sediment transport thresholds. Marticorena and Bergametti (1995) in their dust emission model parameterize the effect of roughness on threshold with the assumption that there is a relationship between roughness density and the aerodynamic roughness length of a surface. Raupach et al. (1993) offer a different approach based on physical modeling of wake development behind individual roughness elements and the partition of the surface stress and the total stress over a roughened surface. A comparison between the models shows the partitioning approach to be a good framework to explain the effect of roughness on entrainment of sediment by wind. Both models provided very good agreement for wind tunnel experiments using solid objects on a nonerodible surface. However, the Marticorena and Bergametti (1995) approach displays a scaling dependency when the difference between the roughness length of the surface and the overall roughness length is too great, while the Raupach et al. (1993) model's predictions perform better owing to the incorporation of the roughness geometry and the alterations to the flow they can cause.

  7. Vibration of shear deformable rings: Theory and experiment†

    NASA Astrophysics Data System (ADS)

    Gardner, T. G.; Bert, C. W.

    1985-12-01

    A new first-approximation theory is presented for analysis of the in-plane dynamic behavior of shear deformable ring structures. This theory may be applied to curved beams as well as complete rings. Natural frequencies and associated vibrational modes for a complete ring are investigated experimentally using modern instrumentation and experimental techniques. The natural frequencies predicted by the new theory are compared with the new experimental data as well as some previously reported data and predictions from thin-ring theory, various other shear deformable theories, elasticity theory, and various finite element analyses. The present theory includes a description of transverse shear strain which permits satisfaction of the physical requirements of zero shear stress at the inner-and outer-ring surfaces. Transverse shear strain is an important effect when analyzing thick, homogeneous, material rings and even more significant for rings made of composite materials. This theory is an advancement over Bresse-type, shear-correction theories, which utilize a shear correction factor determined in an ad hoc fashion.

  8. Predicted Unusual Magnetoresponse in Type-II Weyl Semimetals

    NASA Astrophysics Data System (ADS)

    Yu, Zhi-Ming; Yao, Yugui; Yang, Shengyuan A.

    2016-08-01

    We show several distinct signatures in the magnetoresponse of type-II Weyl semimetals. The energy tilt tends to squeeze the Landau levels (LLs), and, for a type-II Weyl node, there always exists a critical angle between the B field and the tilt, at which the LL spectrum collapses, regardless of the field strength. Before the collapse, signatures also appear in the magneto-optical spectrum, including the invariable presence of intraband peaks, the absence of absorption tails, and the special anisotropic field dependence.

  9. Predicted Unusual Magnetoresponse in Type-II Weyl Semimetals.

    PubMed

    Yu, Zhi-Ming; Yao, Yugui; Yang, Shengyuan A

    2016-08-12

    We show several distinct signatures in the magnetoresponse of type-II Weyl semimetals. The energy tilt tends to squeeze the Landau levels (LLs), and, for a type-II Weyl node, there always exists a critical angle between the B field and the tilt, at which the LL spectrum collapses, regardless of the field strength. Before the collapse, signatures also appear in the magneto-optical spectrum, including the invariable presence of intraband peaks, the absence of absorption tails, and the special anisotropic field dependence. PMID:27563994

  10. Using Situational Factors to Predict Types of Prison Violence.

    ERIC Educational Resources Information Center

    Steinke, Pamela

    1991-01-01

    Tested situational factors as predictors of types of individual aggressive incidents in male prison population. Categorized incidents of violence by whether occurrence of infraction involved aggressive behavior directed at staff, another inmate, self, or property. Found that situational variables did serve as predictors of these categories of…

  11. Slide rule-type color chart predicts reproduced photo tones

    NASA Technical Reports Server (NTRS)

    Griffin, J. D.

    1966-01-01

    Slide rule-type color chart determines the final reproduced gray tones in the production of briefing charts that are photographed in black and white. The chart shows both the color by drafting paint manufacturers name and mixture number, and the gray tone resulting from black and white photographic reproduction.

  12. Shear wave anisotropy beneath the volcanic front in South Kyushu area, Japan: Development of C-type olivine CPO under H2O-rich conditions

    NASA Astrophysics Data System (ADS)

    Terada, Tadashi; Hiramatsu, Yoshihiro; Mizukami, Tomoyuki

    2013-08-01

    wave splitting from local intermediate-depth earthquakes is investigated to detect the anisotropic structure in the mantle wedge beneath the South Kyushu area, Japan. We observed shear wave splitting with NEE-SWW to NWW-SEE polarization directions and delay times of 0.04-0.63 s. Trench-normal shear wave polarization anisotropy with a delay time greater than 0.3 s probably overlaps in the high VP/VS region at a depth of 100-150 km beneath the volcanic front. Model calculations for the cause of the anisotropy suggest that the development of "C-type" olivine crystallographic preferred orientation (CPO) with a trench-parallel b axis concentration and a trench-normal a axis concentration best reproduces observations compared to A-, B-, or E-type olivine CPOs and antigorite CPO. We conclude that a thick anisotropic layer, approximately 50 km, is formed by concentration of interstitial fluid in peridotite. We briefly discuss the mechanism carrying water to the deep mantle wedge. A possible explanation is that interstitial fluids in the mantle wedge are effectively released because of a decrease in dihedral angles of olivine-fluid interfaces at 150 km depth. Our results imply a close relation between the high density of explosive volcanoes in the South Kyushu area and the underlying water-rich mantle.

  13. NAP1 Strain Type Predicts Outcomes from Clostridium difficile Infection

    PubMed Central

    See, Isaac; Mu, Yi; Cohen, Jessica; Beldavs, Zintars G.; Winston, Lisa G.; Dumyati, Ghinwa; Holzbauer, Stacy; Dunn, John; Farley, Monica M.; Lyons, Carol; Johnston, Helen; Phipps, Erin; Perlmutter, Rebecca; Anderson, Lydia; Gerding, Dale N.; Lessa, Fernanda C.

    2015-01-01

    Background Studies conflict regarding the importance of the fluoroquinolone-resistant North American pulsed-field gel electrophoresis type 1 (NAP1) strain in Clostridium difficile infection (CDI) outcome. We describe strain types causing CDI and evaluate their association with patient outcomes. Methods CDI cases were identified from population-based surveillance. Multivariate regression models were used to evaluate the associations of strain type with severe disease (ileus, toxic megacolon, or pseudomembranous colitis within 5 days; or white blood cell count ≥15,000/mm3 within one day of positive test), severe outcome (intensive care unit admission after positive test, colectomy for C. difficile infection, or death within 30 days of positive test), and death within 14 days of positive test. Results Strain typing results were available for 2,057 cases. Severe disease occurred in 363 (17.7%) cases, severe outcome in 100 (4.9%), and death within 14 days in 56 (2.7%). The most common strain types were NAP1 (28.4%), NAP4 (10.2%) and NAP11 (9.1%). In unadjusted analysis, NAP1 was associated with greater odds of severe disease than other strains. After controlling for patient risk factors, healthcare exposure, and antibiotic use, NAP1 was associated with severe disease (adjusted odds ratio [aOR] 1.74, 95% confidence interval [CI], 1.36–2.22), severe outcome (aOR 1.66, 95% CI, 1.09–2.54), and death within 14 days (aOR 2.12, 95% CI, 1.22–3.68). Conclusion NAP1 was the most prevalent strain and a predictor of severe disease, severe outcome, and death. Strategies to reduce NAP1 prevalence, such as antibiotic stewardship to reduce fluoroquinolone use, might reduce CDI morbidity. PMID:24604900

  14. Evaluation of Shear-Induced Platelet Activation Models Under Constant and Dynamic Shear Stress Loading Conditions Relevant to Devices

    PubMed Central

    Sheriff, Jawaad; Soares, João Silva; Xenos, Michalis; Jesty, Jolyon; Bluestein, Danny

    2013-01-01

    The advent of implantable blood-recirculating devices such as left ventricular assist devices and prosthetic heart valves provides a viable therapy for patients with end-stage heart failure and valvular disease. However, device-generated pathological flow patterns result in thromboembolic complications that require complex and lifelong anticoagulant therapy, which entails hemorrhagic risks and is not appropriate for certain patients. Optimizing the thrombogenic performance of such devices utilizing numerical simulations requires the development of predictive platelet activation models that account for variations in shear-loading rates characterizing blood flow through such devices. Platelets were exposed in vitro to both dynamic and constant shear stress conditions emulating those found in blood-recirculating devices in order to determine their shear-induced activation and sensitization response. Both these behaviors were found to be dependent on the shear loading rates, in addition to shear stress magnitude and exposure time. We then critically examined several current models and evaluated their predictive capabilities using these results. Shear loading rate terms were then included to account for dynamic aspects that are either ignored or partially considered by these models, and model parameters were optimized. Independent optimization for each of the two types of shear stress exposure conditions tested resulted in different sets of best-fit constants, indicating that universal optimization may not be possible. Inherent limitations of the current models require a paradigm shift from these integral-based discretized power law models to better address the dynamic conditions encountered in blood-recirculating devices. PMID:23400312

  15. Using Word Prediction Software to Increase Typing Fluency with Students with Physical Disabilities

    ERIC Educational Resources Information Center

    Tumlin, Jennifer; Heller, Kathryn Wolff

    2004-01-01

    The purpose of this study was to examine the use of word prediction software to increase typing speed and decrease spelling errors for students who have physical disabilities that affect hand use. Student perceptions regarding the effectiveness of word prediction was examined as well as their typing rates and spelling accuracy. Four students with…

  16. Micromechanical poroelastic finite element and shear-lag models of tendon predict large strain dependent Poisson's ratios and fluid expulsion under tensile loading.

    PubMed

    Ahmadzadeh, Hossein; Freedman, Benjamin R; Connizzo, Brianne K; Soslowsky, Louis J; Shenoy, Vivek B

    2015-08-01

    As tendons are loaded, they reduce in volume and exude fluid to the surrounding medium. Experimental studies have shown that tendon stretching results in a Poisson's ratio greater than 0.5, with a maximum value at small strains followed by a nonlinear decay. Here we present a computational model that attributes this macroscopic observation to the microscopic mechanism of the load transfer between fibrils under stretch. We develop a finite element model based on the mechanical role of the interfibrillar-linking elements, such as thin fibrils that bridge the aligned fibrils or macromolecules such as glycosaminoglycans (GAGs) in the interfibrillar sliding and verify it with a theoretical shear-lag model. We showed the existence of a previously unappreciated structure-function mechanism whereby the Poisson's ratio in tendon is affected by the strain applied and interfibrillar-linker properties, and together these features predict tendon volume shrinkage under tensile loading. During loading, the interfibrillar-linkers pulled fibrils toward each other and squeezed the matrix, leading to the Poisson's ratio larger than 0.5 and fluid expulsion. In addition, the rotation of the interfibrillar-linkers with respect to the fibrils at large strains caused a reduction in the volume shrinkage and eventual nonlinear decay in Poisson's ratio at large strains. Our model also predicts a fluid flow that has a radial pattern toward the surrounding medium, with the larger fluid velocities in proportion to the interfibrillar sliding. PMID:25934322

  17. Dynamics of Sheared Granular Materials

    NASA Astrophysics Data System (ADS)

    Kondic, Lou; Utter, Brian; Behringer, Robert P.

    2002-11-01

    characterize the transition region in an earth-bound experiment. In the DE modeling, we analyze dynamics of a sheared granular system in Couette geometry in two (2D) and three (3D) space dimensions. Here, the idea is to both better understand what we might encounter in a reduced-g environment, and at a deeper level to deduce the physics of sheared systems in a density regime that has not been addressed by past experiments or simulations. One aspect of the simulations addresses sheared 2D system in zero-g environment. For low volume fractions, the expected dynamics of this type of system is relatively well understood. However, as the volume fraction is increased, the system undergoes a phase transition, as explained above. The DES concentrate on the evolution of the system as the solid volume fraction is slowly increased, and in particular on the behavior of very dense systems. For these configurations, the simulations show that polydispersity of the sheared particles is a crucial factor that determines the system response. Figures 1 and 2 below, that present the total force on each grain, show that even relatively small (10 %) nonuniformity of the size of the grains (expected in typical experiments) may lead to significant modifications of the system properties, such as velocity profiles, temperature, force propagation, and formation shear bands. The simulations are extended in a few other directions, in order to provide additional insight to the experimental system analyzed above. In one direction, both gravity, and driving due to vibrations are included. These simulations allow for predictions on the driving regime that is required in the experiments in order to analyze the jamming transition. Furthermore, direct comparison of experiments and DES will allow for verification of the modeling assumptions. We have also extended our modeling efforts to 3D. The (preliminary) results of these simulations of an annular system in zero-g environment will conclude the presentation.

  18. Dynamics of Sheared Granular Materials

    NASA Technical Reports Server (NTRS)

    Kondic, Lou; Utter, Brian; Behringer, Robert P.

    2002-01-01

    characterize the transition region in an earth-bound experiment. In the DE modeling, we analyze dynamics of a sheared granular system in Couette geometry in two (2D) and three (3D) space dimensions. Here, the idea is to both better understand what we might encounter in a reduced-g environment, and at a deeper level to deduce the physics of sheared systems in a density regime that has not been addressed by past experiments or simulations. One aspect of the simulations addresses sheared 2D system in zero-g environment. For low volume fractions, the expected dynamics of this type of system is relatively well understood. However, as the volume fraction is increased, the system undergoes a phase transition, as explained above. The DES concentrate on the evolution of the system as the solid volume fraction is slowly increased, and in particular on the behavior of very dense systems. For these configurations, the simulations show that polydispersity of the sheared particles is a crucial factor that determines the system response. Figures 1 and 2 below, that present the total force on each grain, show that even relatively small (10 %) nonuniformity of the size of the grains (expected in typical experiments) may lead to significant modifications of the system properties, such as velocity profiles, temperature, force propagation, and formation shear bands. The simulations are extended in a few other directions, in order to provide additional insight to the experimental system analyzed above. In one direction, both gravity, and driving due to vibrations are included. These simulations allow for predictions on the driving regime that is required in the experiments in order to analyze the jamming transition. Furthermore, direct comparison of experiments and DES will allow for verification of the modeling assumptions. We have also extended our modeling efforts to 3D. The (preliminary) results of these simulations of an annular system in zero-g environment will conclude the presentation.

  19. Spontaneous activity does not predict morphological type in cerebellar interneurons.

    PubMed

    Haar, Shlomi; Givon-Mayo, Ronit; Barmack, Neal H; Yakhnitsa, Vadim; Donchin, Opher

    2015-01-28

    The effort to determine morphological and anatomically defined neuronal characteristics from extracellularly recorded physiological signatures has been attempted with varying success in different brain areas. Recent studies have attempted such classification of cerebellar interneurons (CINs) based on statistical measures of spontaneous activity. Previously, such efforts in different brain areas have used supervised clustering methods based on standard parameterizations of spontaneous interspike interval (ISI) histograms. We worried that this might bias researchers toward positive identification results and decided to take a different approach. We recorded CINs from anesthetized cats. We used unsupervised clustering methods applied to a nonparametric representation of the ISI histograms to identify groups of CINs with similar spontaneous activity and then asked how these groups map onto different cell types. Our approach was a fuzzy C-means clustering algorithm applied to the Kullbach-Leibler distances between ISI histograms. We found that there is, in fact, a natural clustering of the spontaneous activity of CINs into six groups but that there was no relationship between this clustering and the standard morphologically defined cell types. These results proved robust when generalization was tested to completely new datasets, including datasets recorded under different anesthesia conditions and in different laboratories and different species (rats). Our results suggest the importance of an unsupervised approach in categorizing neurons according to their extracellular activity. Indeed, a reexamination of such categorization efforts throughout the brain may be necessary. One important open question is that of functional differences of our six spontaneously defined clusters during actual behavior. PMID:25632121

  20. Mineralization stages of the unique shear zone-hosted "Felsit-type" Sn-polymetallic mineralization in the eastern Erzgebirge, Germany

    NASA Astrophysics Data System (ADS)

    Járóka, Tom; Seifert, Thomas

    2014-05-01

    The polymetallic cassiterite-bearing mineralization of the "Felsit-type" is located in the NW of the Freiberg mining district within the Großschirma area. The mineralization is hosted by metamorphic rocks of the Preßnitzer Group unit that form the most northeastern part of the Erzgebirge metamorphic core complex. This geological unit is in the Großschirma area predominantly composed of two-mica gneisses and mica schists, whereas intercalations of muscovite-gneiss ("red gneiss"), amphibolites and metacarbonates occur less commonly. These metamorphic rocks were deformed by several NE-SW striking fault zones. The hydrothermal Sn-bearing fluids migrated within shear zones that developed primarily at the contact between different lithotypes. The shear zones are characterized by strong pervasive metasomatic alterations which were triggered by small chlorite-cassiterite-quartz-sulfide-veins. The rock-forming minerals are strongly corroded and displaced by the ore and gangue minerals within the shear zones. The bulk geochemistry of selected drill core samples feature grades up to 0.28 wt. % Sn, 0.15 wt. % Cu, 300 ppm Pb, 140 ppm Zn, 1.1 wt. % F, 250 ppm Li, 820 ppm Rb, 90 ppm Cs, and 130 ppm W. Microscopic and geochemical studies of the samples show that the Sn-polymetallic mineralization of the "Felsit-type" can be distinguished into three different mineralization stages. The first one is dominated by chlorite and quartz. Cassiterite probably appears in two generations with different grain shapes: acicular (< 1 - 100 µm) and isometric cassiterite (< 10 - 650 µm). Smaller amounts of fluorite, rutile, apatite, and scheelite are also associated with the first stage. The second mineralization stage is dominated by pyrite which is the most abundant ore mineral of this paragenesis, while marcasite, chalcopyrite, pyrrhotite, galena, sphalerite, arsenopyrite, bismuthinite, and magnetite appear only subordinately. The third stage is dominated by carbonates that are often

  1. A refined nonlinear theory of plates with transverse shear deformation

    NASA Technical Reports Server (NTRS)

    Reddy, J. N.

    1984-01-01

    A higher-order shear deformation theory of plates accounting for the von Karman strains is presented. The theory contains the same dependent unknowns as in the Hencky-Mindlin type first-order shear deformation theory and accounts for parabolic distribution of the transverse shear strains through the thickness of the plate. Exact solutions of simply supported plates are obtained using the linear theory and the results are compared with the exact solutions of three-dimensional elasticity theory, the first order shear deformation theory, and the classical plate theory. The present theory predicts the deflections, stresses, and frequencies more accurately when compared to the first-order theory and the classical plate theory.

  2. Prediction of Heat Transfer Characteristics of Binary Refrigerant Mixtures in a Falling Film Type Plate-fin Evaporator

    NASA Astrophysics Data System (ADS)

    Yara, Tomoyasu; Koyama, Shigeru

    This paper deals with the characteristics of heat transfer and pressure drop of R 22, R 134a pure refrigerant and R 134a/R123 refrigerant mixtures in a falling film type plate-fin evaporator. The refrigerants have been tested in the ranges of heat flux from 3 to 20 kW/m2 and mass velocity from 50 to 100 kg/m2s. It is clarified that heat transfer characteristics of evaporation in the present experimental range are not affected by shear stress. Taking the fin efficiency into consideration, a correlation equation of heat transfer coefficient is proposed. The characteristic of pressure drop is also proposed by modifying friction factor of Soliman's equation. Furthermore, a prediction model for evaporation of mixtures in a plate fin heat exchanger is developed based on the assumption that the phase equilibrium in a cross-section of the refrigerant path is established. The prediction results are in good agreement with the experimental data.

  3. 29 CFR 570.65 - Occupations involved in the operations of circular saws, band saws, and guillotine shears (Order...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... include other types of shearing machines, using a different form of shearing action, such as alligator... machines, using a different form of shearing action, such as alligator shears or circular shears....

  4. Application of a model of plastic porous materials including void shape effects to the prediction of ductile failure under shear-dominated loadings

    NASA Astrophysics Data System (ADS)

    Morin, Léo; Leblond, Jean-Baptiste; Tvergaard, Viggo

    2016-09-01

    An extension of Gurson's famous model (Gurson, 1977) of porous plastic solids, incorporating void shape effects, has recently been proposed by Madou and Leblond (Madou and Leblond, 2012a, 2012b, 2013; Madou et al., 2013). In this extension the voids are no longer modelled as spherical but ellipsoidal with three different axes, and changes of the magnitude and orientation of these axes are accounted for. The aim of this paper is to show that the new model is able to predict softening due essentially to such changes, in the absence of significant void growth. This is done in two steps. First, a numerical implementation of the model is proposed and incorporated into the SYSTUS® and ABAQUS® finite element programmes (through some freely available UMAT (Leblond, 2015) in the second case). Second, the implementation in SYSTUS® is used to simulate previous "numerical experiments" of Tvergaard and coworkers (Tvergaard, 2008, 2009, 2012, 2015a; Dahl et al., 2012; Nielsen et al., 2012) involving the shear loading of elementary porous cells, where softening due to changes of the void shape and orientation was very apparent. It is found that with a simple, heuristic modelling of the phenomenon of mesoscopic strain localization, the model is indeed able to reproduce the results of these numerical experiments, in contrast to Gurson's model disregarding void shape effects.

  5. Type-D Personality Can Predict Suicidality in Patients with Major Depressive Disorder

    PubMed Central

    Ko, Young-Hoon; Lee, Moon-Soo; Lee, Heon-Jeong; Kim, Leen

    2014-01-01

    Objective This study investigated the putative association between type-D personality and suicidality, including the history of suicide attempt and suicidal ideation in patients with major depressive disorder (MDD). Methods Eighty-six outpatients aged between 18 and 65 years with MDD were recruited for this study from Ilsan Paik Hospital. The cohort was stratified into two subgroups according to the presence of type-D personality and history of suicide attempt (yes vs. no). Depression severity was evaluated using the Hamilton Depression Rating Scale. The type-D Personality Scale-14 (DS-14), the Beck Hopelessness Scale (BHS), the Barratt Impulsiveness Scale (BIS), the Hamilton Anxiety Scale, and the Beck Scale for Suicidal Ideation (BSS) were also applied. Results The total BSS, BHS, and BIS scores were higher for the group with type-D personality than for the group without this personality (p=0.004, 0.01, and 0.003, respectively). In addition, the total scores for the BSS, BHS, and social inhibition (SI; subscale of DS-14) were higher for the group with a history of suicide attempt than for the group without this history (p=0.0000004, 0.003, and 0.033, respectively). There were positive correlations between the total DS-14 score and the total BSS, BHS, and BIS scores (r=0.413 and p=0.000077, r=0.404 and p=0.00012, and r=0.245 and p=0.024, respectively). Conclusion Depressed patients with type-D personality are more vulnerable to suicidality than those without type-D personality, even when the MDD severity is identical. In addition, the SI score was higher in patients with a history of suicide attempt than in those without this history. PMID:25110494

  6. Recycling and utilisation of industrial solid waste: an explorative study on gold deposit tailings of ductile shear zone type in China.

    PubMed

    Liu, Rui; Huang, Fei; Du, Runxiang; Zhao, Chunming; Li, Yongli; Yu, Haoran

    2015-06-01

    Tailings are solid waste arising from mineral processing. This type of waste can cause severe damage to the environment during stockpiling as a result of the leaching of something harmful into the ecosystem. Gold deposit of ductile shear zone type is an important type of gold deposit, and the recycling of its tailings has been challenging researchers for a long time. In this article, the characteristics of this type of tailings were systematically studied by using modern technical means. Considering the characteristics of the tailings, clay was selected to make up for the shortcomings of the tailings and improve their performance. Water and raw materials were mixed to produce green bodies, which are subsequently sintered into ceramic bodies at 980 °C~1020 °C (sintering temperature). The results showed that some new kinds of mineral phases, such as mullite, anorthite and orthoclase, appear in ceramic bodies. Furthermore, the ceramic bodies have a surface hardness of 5 to 6 (Mohs scale), and their water absorption and modulus of rupture can meet some technical requirements of ceramic materials described in ISO 13006-2012 and GB 5001-1985. These gold mine tailings can be made into ceramic tiles, domestic ceramic bodies, and other kinds of ceramic bodies for commercial and industrial purposes after further improvements. PMID:26060235

  7. Predicting The Type Of Pregnancy Using Flexible Discriminate Analysis And Artificial Neural Networks: A Comparison Study

    NASA Astrophysics Data System (ADS)

    Hooman, A.; Mohammadzadeh, M.

    2008-01-01

    Some medical and epidemiological surveys have been designed to predict a nominal response variable with several levels. With regard to the type of pregnancy there are four possible states: wanted, unwanted by wife, unwanted by husband and unwanted by couple. In this paper, we have predicted the type of pregnancy, as well as the factors influencing it using three different models and comparing them. Regarding the type of pregnancy with several levels, we developed a multinomial logistic regression, a neural network and a flexible discrimination based on the data and compared their results using tow statistical indices: Surface under curve (ROC) and kappa coefficient. Based on these tow indices, flexible discrimination proved to be a better fit for prediction on data in comparison to other methods. When the relations among variables are complex, one can use flexible discrimination instead of multinomial logistic regression and neural network to predict the nominal response variables with several levels in order to gain more accurate predictions.

  8. Predicting The Type Of Pregnancy Using Flexible Discriminate Analysis And Artificial Neural Networks: A Comparison Study

    SciTech Connect

    Hooman, A.; Mohammadzadeh, M

    2008-01-30

    Some medical and epidemiological surveys have been designed to predict a nominal response variable with several levels. With regard to the type of pregnancy there are four possible states: wanted, unwanted by wife, unwanted by husband and unwanted by couple. In this paper, we have predicted the type of pregnancy, as well as the factors influencing it using three different models and comparing them. Regarding the type of pregnancy with several levels, we developed a multinomial logistic regression, a neural network and a flexible discrimination based on the data and compared their results using tow statistical indices: Surface under curve (ROC) and kappa coefficient. Based on these tow indices, flexible discrimination proved to be a better fit for prediction on data in comparison to other methods. When the relations among variables are complex, one can use flexible discrimination instead of multinomial logistic regression and neural network to predict the nominal response variables with several levels in order to gain more accurate predictions.

  9. The stress profile in a sheared granular column

    NASA Astrophysics Data System (ADS)

    Nott, Prabhu; Mehandia, Vishwajeet; Jyotsna Gutam, Kamala

    2011-11-01

    It has been known for several centuries that the normal stress at the base of a column of granular material deviates from the value dictated by the hydrostatic balance. This was explained by Janssen (1895) as being due to the shear stress imposed by the confining walls on the granular column, as a result of grain-wall friction. The question we address in this presentation is, what is the stress field when the column is sheared? Depending on the assumptions on the kinematics, plasticity theories predict that the stress profile is similar either to that in a static column, or to that in a sheared fluid column. Here, we report the results of our experimental study of slow shear of a granular material in a cylindrical Couette cell, in which all components of the stress were measured at the stationary outer cylinder. The stress was measured as a function of distance from the free surface. The results of our experiments are intriguing: the radial normal stress deviates strongly from the predictions of all available theories and previous experimental measurements. The axial shear stress changes sign when a static column is sheared. We describe these results, and speculate as to which type of theory might explain the observations. Support from the DST, India is gratefully acknowledged.

  10. Importance of Tensile Strength on the Shear Behavior of Discontinuities

    NASA Astrophysics Data System (ADS)

    Ghazvinian, A. H.; Azinfar, M. J.; Geranmayeh Vaneghi, R.

    2012-05-01

    In this study, the shear behavior of discontinuities possessing two different rock wall types with distinct separate compressive strengths was investigated. The designed profiles consisted of regular artificial joints molded by five types of plaster mortars, each representing a distinct uniaxial compressive strength. The compressive strengths of plaster specimens ranged from 5.9 to 19.5 MPa. These specimens were molded considering a regular triangular asperity profile and were designed so as to achieve joint walls with different strength material combinations. The results showed that the shear behavior of discontinuities possessing different joint wall compressive strengths (DDJCS) tested under constant normal load (CNL) conditions is the same as those possessing identical joint wall strengths, but the shear strength of DDJCS is governed by minor joint wall compressive strength. In addition, it was measured that the predicted values obtained by Barton's empirical criterion are greater than the experimental results. The finding indicates that there is a correlation between the joint roughness coefficient (JRC), normal stress, and mechanical strength. It was observed that the mode of failure of asperities is either pure tensile, pure shear, or a combination of both. Therefore, Barton's strength criterion, which considers the compressive strength of joint walls, was modified by substituting the compressive strength with the tensile strength. The validity of the modified criterion was examined by the comparison of the predicted shear values with the laboratory shear test results reported by Grasselli (Ph.D. thesis n.2404, Civil Engineering Department, EPFL, Lausanne, Switzerland, 2001). These comparisons infer that the modified criterion can predict the shear strength of joints more precisely.

  11. A shear deformable theory of laminated composite shallow shell-type panels and their response analysis. II - Static response

    NASA Technical Reports Server (NTRS)

    Khdeir, A. A.; Librescu, L.; Frederick, D.

    1989-01-01

    In the second part of this paper, by using the static counterparts of the governing equations derived in Librescu (1989), the static response of shallow composite shell-type panels subjected to a sinusoidal transverse load is investigated. The numerical applications, encompassing a large number of boundary conditions and various lamination schemes, allow one to obtain some conclusions which are formulated in the paper.

  12. A multi-label classifier for prediction membrane protein functional types in animal.

    PubMed

    Zou, Hong-Liang

    2014-11-01

    Membrane protein is an important composition of cell membrane. Given a membrane protein sequence, how can we identify its type(s) is very important because the type keeps a close correlation with its functions. According to previous studies, membrane protein can be divided into the following eight types: single-pass type I, single-pass type II, single-pass type III, single-pass type IV, multipass, lipid-anchor, GPI-anchor, peripheral membrane protein. With the avalanche of newly found protein sequences in the post-genomic age, it is urgent to develop an automatic and effective computational method to rapid and reliable prediction of the types of membrane proteins. At present, most of the existing methods were based on the assumption that one membrane protein only belongs to one type. Actually, a membrane protein may simultaneously exist at two or more different functional types. In this study, a new method by hybridizing the pseudo amino acid composition with multi-label algorithm called LIFT (multi-label learning with label-specific features) was proposed to predict the functional types both singleplex and multiplex animal membrane proteins. Experimental result on a stringent benchmark dataset of membrane proteins by jackknife test show that the absolute-true obtained was 0.6342, indicating that our approach is quite promising. It may become a useful high-through tool, or at least play a complementary role to the existing predictors in identifying functional types of membrane proteins. PMID:25107302

  13. Prediction of clathrate structure type and guest position by molecular mechanics.

    PubMed

    Fleischer, Everly B; Janda, Kenneth C

    2013-05-16

    The clathrate hydrates occur in various types in which the number, size, and shape of the various cages differ. Usually the clathrate type of a specific guest is predicted by the size and shape of the molecular guest. We have developed a methodology to determine the clathrate type employing molecular mechanics with the MMFF force field employing a strategy to calculate the energy of formation of the clathrate from the sum of the guest/cage energies. The clathrate type with the most negative (most stable) energy of formation would be the type predicted (we mainly focused on type I, type II, or bromine type). This strategy allows for a calculation to predict the clathrate type for any cage guest in a few minutes on a laptop computer. It proved successful in predicting the clathrate structure for 46 out of 47 guest molecules. The molecular mechanics calculations also provide a prediction of the guest position within the cage and clathrate structure. These predictions are generally consistent with the X-ray and neutron diffraction studies. By supplementing the diffraction study with molecular mechanics, we gain a more detailed insight regarding the details of the structure. We have also compared MM calculations to studies of the multiple occupancy of the cages. Finally, we present a density functional calculation that demonstrates that the inside of the clathrates cages have a relatively uniform and low electrostatic potential in comparison with the outside oxygen and hydrogen atoms. This implies that van der Waals forces will usually be dominant in the guest-cage interactions. PMID:23600658

  14. A predictive computational framework for direct reprogramming between human cell types.

    PubMed

    Rackham, Owen J L; Firas, Jaber; Fang, Hai; Oates, Matt E; Holmes, Melissa L; Knaupp, Anja S; Suzuki, Harukazu; Nefzger, Christian M; Daub, Carsten O; Shin, Jay W; Petretto, Enrico; Forrest, Alistair R R; Hayashizaki, Yoshihide; Polo, Jose M; Gough, Julian

    2016-03-01

    Transdifferentiation, the process of converting from one cell type to another without going through a pluripotent state, has great promise for regenerative medicine. The identification of key transcription factors for reprogramming is currently limited by the cost of exhaustive experimental testing of plausible sets of factors, an approach that is inefficient and unscalable. Here we present a predictive system (Mogrify) that combines gene expression data with regulatory network information to predict the reprogramming factors necessary to induce cell conversion. We have applied Mogrify to 173 human cell types and 134 tissues, defining an atlas of cellular reprogramming. Mogrify correctly predicts the transcription factors used in known transdifferentiations. Furthermore, we validated two new transdifferentiations predicted by Mogrify. We provide a practical and efficient mechanism for systematically implementing novel cell conversions, facilitating the generalization of reprogramming of human cells. Predictions are made available to help rapidly further the field of cell conversion. PMID:26780608

  15. Epstein-Barr virus latency type and spontaneous reactivation predict lytic induction levels.

    PubMed

    Phan, An T; Fernandez, Samantha G; Somberg, Jessica J; Keck, Kristin M; Miranda, Jj L

    2016-05-20

    The human Epstein-Barr virus (EBV) evades the immune system by entering a transcriptionally latent phase in B cells. EBV in tumor cells expresses distinct patterns of genes referred to as latency types. Viruses in tumor cells also display varying levels of lytic transcription resulting from spontaneous reactivation out of latency. We measured this dynamic range of lytic transcription with RNA deep sequencing and observed no correlation with EBV latency types among genetically different viruses, but type I cell lines reveal more spontaneous reactivation than isogenic type III cultures. We further determined that latency type and spontaneous reactivation levels predict the relative amount of induced reactivation generated by cytotoxic chemotherapy drugs. Our work has potential implications for personalizing medicine against EBV-transformed malignancies. Identifying latency type or measuring spontaneous reactivation may provide predictive power in treatment contexts where viral production should be either avoided or coerced. PMID:27091426

  16. Are quartz LPOs predictably oriented with respect to the shear zone boundary?: A test from the Alpine Fault mylonites, New Zealand

    NASA Astrophysics Data System (ADS)

    Little, Timothy A.; Prior, David J.; Toy, Virginia G.

    2016-03-01

    The Alpine fault self-exhumes its own ductile shear zone roots and has a known slip kinematics. Within ˜1 km of the fault, the mylonitic foliation is subparallel to the boundary of the amphibolite-facies ductile shear zone in which it formed. Using EBSD, we analyzed quartz Lattice Preferred Orientations [LPOs) of mylonites along a central part of the Alpine Fault. All LPOs feature a strongest girdle of [c]-axes that is forward-inclined ˜28 ± 4° away from the pole to the fault. A maximum of axes is inclined at the same angle relative the fault. The [c]-axis girdle is perpendicular to extensional (C') shear bands and the maximum is parallel to their slip direction. [c]-axis girdles do not form perpendicular to the SZB. Schmid factor analysis suggests that σ1 was arranged at 60-80° to the Alpine Fault. These observations indicate ductile transpression in the shear zone. The inclined arrangement of [c]-axis girdles, axes, and C' planes relative to the fault can be explained by their alignment relative to planes of maximum shear-strain-rate in a general shear zone, a significant new insight regarding shear zones and how LPO fabrics may generally develop within them. For the Alpine mylonite zone, our data imply a kinematic vorticity number (Wk) of ˜0.7 to ˜0.85. Inversions of seismic focal mechanisms in the brittle crust of the Southern Alps indicate that σ1 is oriented ˜60° to the Alpine Fault; that shear bands form at ˜30° to this direction, and that σ2 and σ3 flip positions between the brittle and ductile parts of the crust.

  17. Comparative evaluation of compressive strength, diametral tensile strength and shear bond strength of GIC type IX, chlorhexidine-incorporated GIC and triclosan-incorporated GIC: An in vitro study

    PubMed Central

    Jaidka, Shipra; Somani, Rani; Singh, Deepti J.; Shafat, Shazia

    2016-01-01

    Aim: To comparatively evaluate the compressive strength, diametral tensile strength, and shear bond strength of glass ionomer cement type IX, chlorhexidine-incorporated glass ionomer cement, and triclosan-incorporated glass ionomer cement. Materials and Methods: In this study, glass ionomer cement type IX was used as a control. Chlorhexidine diacetate, and triclosan were added to glass ionomer cement type IX powder, respectively, in order to obtain 0.5, 1.25, and 2.5% concentrations of the respective experimental groups. Compressive strength, diametral tensile strength, and shear bond strength were evaluated after 24 h using Instron Universal Testing Machine. The results obtained were statistically analyzed using the independent t-test, Dunnett test, and Tukey test. Results: There was no statistical difference in the compressive strength, diametral tensile strength, and shear bond strength of glass ionomer cement type IX (control), 0.5% triclosan-glass ionomer cement, and 0.5% chlorhexidine-glass ionomer cement. Conclusion: The present study suggests that the compressive strength, diametral tensile strength, and shear bond strength of 0.5% triclosan-glass ionomer cement and 0.5% chlorhexidine-glass ionomer cement were similar to those of the glass ionomer cement type IX, discernibly signifying that these can be considered as viable options for use in pediatric dentistry with the additional value of antimicrobial property along with physical properties within the higher acceptable range. PMID:27195231

  18. Comparison of the push-out shear bond strength of four types of glass ionomers when used to bond amalgam: An in vitro study

    PubMed Central

    Mathew, Vinod Babu; Ramachandran, S; Indira, R; Shankar, P

    2011-01-01

    Background: Dental amalgam is the primary direct posterior restorative material used worldwide, but it have certain shortcomings due to the lack of adhesiveness to the cavity. The introduction of the concept of bonded amalgam helped improve the use of amalgam as a restorative material. Aim: Evaluation of the comparative push-out shear bond strength of four types of conventional glass ionomers used to bond amalgam to tooth in simulated class I situations. Materials and Methods: Four chemical cure glass ionomers are used: GC Fuji I, GC Fuji II, GC Fuji III and GC Fuji VII, and are compared with unbonded amalgam. The push-out bond strength was tested using the Instron Universal Testing Machine at a crosshead speed of 0.5 mm/min. Statistical Analysis: One-way ANOVA and post hoc Bonferroni tests were used to analyze the data. Results: The results showed that the use of glass ionomer to bond amalgam resulted in an increase in the bond strength of amalgam. The Type VII glass ionomer showed the highest bond strength in comparison with the other glass ionomers. Conclusions: Conventional glass ionomer bonds to amalgam and shows a beneficial increase in the bond strength of the restoration in comparison with unbonded amalgam. PMID:22144798

  19. Zipper and freeway shear zone junctions

    NASA Astrophysics Data System (ADS)

    Passchier, Cees; Platt, John

    2016-04-01

    Ductile shear zones are usually presented as isolated planar high-strain domains in a less deformed wall rock, characterised by shear sense indicators such as characteristic deflected foliation traces. Many shear zones, however, form branched systems and if movement on such branches is contemporaneous, the resulting geometry can be complicated and lead to unusual fabric geometries in the wall rock. For Y-shaped shear zone junctions with three simultaneously operating branches, and with slip directions at a high angle to the branch line, eight basic types of shear zone triple junctions are possible, divided into three groups. The simplest type, called freeway junctions, have similar shear sense on all three branches. If shear sense is different on the three branches, this can lead to space problems. Some of these junctions have shear zone branches that join to form a single branch, named zipper junctions, or a single shear zone which splits to form two, known as wedge junctions. Closing zipper junctions are most unusual, since they form a non-active high-strain zone with opposite deflection of foliations. Shear zipper and shear wedge junctions have two shear zones with similar shear sense, and one with the opposite sense. All categories of shear zone junctions show characteristic flow patterns in the shear zone and its wall rock. Shear zone junctions with slip directions normal to the branch line can easily be studied, since ideal sections of shear sense indicators lie in the plane normal to the shear zone branches and the branch line. Expanding the model to allow slip oblique and parallel to the branch line in a full 3D setting gives rise to a large number of geometries in three main groups. Slip directions can be parallel on all branches but oblique to the branch line: two slip directions can be parallel and a third oblique, or all three branches can have slip in different directions. Such more complex shear zone junctions cannot be studied to advantage in a

  20. Prediction of Multi-Type Membrane Proteins in Human by an Integrated Approach

    PubMed Central

    Chen, Lei; Zhang, Ning; Huang, Tao; Cai, Yu-Dong

    2014-01-01

    Membrane proteins were found to be involved in various cellular processes performing various important functions, which are mainly associated to their types. However, it is very time-consuming and expensive for traditional biophysical methods to identify membrane protein types. Although some computational tools predicting membrane protein types have been developed, most of them can only recognize one kind of type. Therefore, they are not as effective as one membrane protein can have several types at the same time. To our knowledge, few methods handling multiple types of membrane proteins were reported. In this study, we proposed an integrated approach to predict multiple types of membrane proteins by employing sequence homology and protein-protein interaction network. As a result, the prediction accuracies reached 87.65%, 81.39% and 70.79%, respectively, by the leave-one-out test on three datasets. It outperformed the nearest neighbor algorithm adopting pseudo amino acid composition. The method is anticipated to be an alternative tool for identifying membrane protein types. New metrics for evaluating performances of methods dealing with multi-label problems were also presented. The program of the method is available upon request. PMID:24676214

  1. Response of hot element wall shear stress gages in laminar oscillating flows

    NASA Technical Reports Server (NTRS)

    Cook, W. J.; Murphy, J. D.; Giddings, T. A.

    1986-01-01

    An experimental investigation of the time-dependent response of hot element wall shear stress gages in unsteady periodic air flows is reported. The study has focused on wall shear stress in laminar oscillating flows produced on a flat plate by a free stream velocity composed of a mean component and a superposed sinusoidal variation. Two types of hot element gages, platinum film and flush wire, were tested for values of reduced frequency ranging from 0.14 to 2.36. Values of the phase angle of the wall shear stress variation relative to the free stream velocity, as indicated by the hot element gages, are compared with numerical prediction. The comparisons show that the gages indicate a wall shear stress variation that lags the true variation, and that the gages will also not indicate the correct wall shear stress variation in periodic turbulent flows.

  2. Impaired Spatio-Temporal Predictive Motor Timing Associated with Spinocerebellar Ataxia Type 6.

    PubMed

    Broersen, Robin; Onuki, Yoshiyuki; Abdelgabar, Abdel R; Owens, Cullen B; Picard, Samuel; Willems, Jessica; Boele, Henk-Jan; Gazzola, Valeria; Van der Werf, Ysbrand D; De Zeeuw, Chris I

    2016-01-01

    Many daily life activities demand precise integration of spatial and temporal information of sensory inputs followed by appropriate motor actions. This type of integration is carried out in part by the cerebellum, which has been postulated to play a central role in learning and timing of movements. Cerebellar damage due to atrophy or lesions may compromise forward-model processing, in which both spatial and temporal cues are used to achieve prediction for future motor states. In the present study we sought to further investigate the cerebellar contribution to predictive and reactive motor timing, as well as to learning of sequential order and temporal intervals in these tasks. We tested patients with spinocerebellar ataxia type 6 (SCA6) and healthy controls for two related motor tasks; one requiring spatio-temporal prediction of dynamic visual stimuli and another one requiring reactive timing only. We found that healthy controls established spatio-temporal prediction in their responses with high temporal precision, which was absent in the cerebellar patients. SCA6 patients showed lower predictive motor timing, coinciding with a reduced number of correct responses during the 'anticipatory' period on the task. Moreover, on the task utilizing reactive motor timing functions, control participants showed both sequence order and temporal interval learning, whereas patients only showed sequence order learning. These results suggest that SCA6 affects predictive motor timing and temporal interval learning. Our results support and highlight cerebellar contribution to timing and argue for cerebellar engagement during spatio-temporal prediction of upcoming events. PMID:27571363

  3. Impaired Spatio-Temporal Predictive Motor Timing Associated with Spinocerebellar Ataxia Type 6

    PubMed Central

    Onuki, Yoshiyuki; Abdelgabar, Abdel R.; Owens, Cullen B.; Picard, Samuel; Willems, Jessica; Boele, Henk-Jan; Gazzola, Valeria; Van der Werf, Ysbrand D.; De Zeeuw, Chris I.

    2016-01-01

    Many daily life activities demand precise integration of spatial and temporal information of sensory inputs followed by appropriate motor actions. This type of integration is carried out in part by the cerebellum, which has been postulated to play a central role in learning and timing of movements. Cerebellar damage due to atrophy or lesions may compromise forward-model processing, in which both spatial and temporal cues are used to achieve prediction for future motor states. In the present study we sought to further investigate the cerebellar contribution to predictive and reactive motor timing, as well as to learning of sequential order and temporal intervals in these tasks. We tested patients with spinocerebellar ataxia type 6 (SCA6) and healthy controls for two related motor tasks; one requiring spatio-temporal prediction of dynamic visual stimuli and another one requiring reactive timing only. We found that healthy controls established spatio-temporal prediction in their responses with high temporal precision, which was absent in the cerebellar patients. SCA6 patients showed lower predictive motor timing, coinciding with a reduced number of correct responses during the ‘anticipatory’ period on the task. Moreover, on the task utilizing reactive motor timing functions, control participants showed both sequence order and temporal interval learning, whereas patients only showed sequence order learning. These results suggest that SCA6 affects predictive motor timing and temporal interval learning. Our results support and highlight cerebellar contribution to timing and argue for cerebellar engagement during spatio-temporal prediction of upcoming events. PMID:27571363

  4. Relationship Between Onset Thresholds, Trigger Types, and Rotation Shear for the m/n=2/1 Neoclassical Tearing Mode in a High-β Spherical Torus

    SciTech Connect

    Gerhardt, S. P.; Brennan, D. P.; Buttery, R.; La Haye, R. J.; Sabbagh, S.; Strait, E.; Bell, M.; Bell, R.; Fredrickson, E.; Gates, D.; LeBlanc, B.; Menard, J.; Stutman, D.; Tritz, K.; Yuh, H.

    2009-02-24

    The onset conditions for the m/n=2/1 neoclassical tearing mode (NTM) are studied in terms of neoclassical drive, triggering instabilities, and toroidal rotation or rotation shear, in the spherical torus NSTX [M. Ono, et al., Nuclear Fusion 40, 557 (2000)]. There are three typical onset conditions for these modes, given in order of increasing neoclassical drive required for mode onset: triggering by energetic particle modes, triggering by edge localized modes, and cases where the modes appear to grow without a trigger. In all cases, the required drive increases with toroidal rotation shear, implying a stabilizing effect from the shear.

  5. Exchangeable lead from prediction models relates to vetiver lead uptake in different soil types.

    PubMed

    Andra, Syam S; Sarkar, Dibyendu; Saminathan, Sumathi K M; Datta, Rupali

    2011-12-01

    Prediction models for exchangeable soil lead, published earlier in this journal (Andra et al. 2010a), were developed using a suite of native lead (Pb) paint-contaminated residential soils from two US cities heavily populated with homes constructed prior to Pb ban in paints. In this study, we tested the feasibility and practical applications of these prediction models for developing a phytoremediation design using vetiver grass (Vetiveria zizanioides), a Pb-tolerant plant. The models were used to estimate the exchangeable fraction of Pb available for vetiver uptake in four lead-spiked soil types, both acidic and alkaline, with varying physico-chemical properties and that are different from those used to build the prediction models. Results indicate a strong correlation for predictable exchangeable Pb with the observed fraction and as well with total Pb accumulated by vetiver grass grown in these soils. The correlation coefficient for the predicted vs. observed exchangeable Pb with p < 0.001 was 0.999, 0.996, 0.949, and 0.998 in the Immokalee, Millhopper, Pahokee Muck, and Tobosa soil type, respectively. Similarly, the correlation coefficient for the predicted exchangeable Pb vs. accumulated Pb in vetiver grass with p < 0.001 was 0.948, 0.983, 0.929, and 0.969 for each soil type, respectively. This study suggests that the success of a phytoremediation design could be assessed upfront by predicting the exchangeable Pb fraction in a given soil type based on its properties. This helps in modifying the soil conditions to enhance phytoextraction of Pb from contaminated soils. PMID:21359998

  6. Does Self-Determination Predict the School Engagement of Four Different Motivation Types in Adolescence?

    ERIC Educational Resources Information Center

    Raufelder, Diana; Regner, Nicola; Drury, Kate; Eid, Michael

    2016-01-01

    In order to enhance our understanding of inter-individual differences in scholastic motivation, this study examined if self-determination predicts the school engagement of four different motivation types (MT) in a large sample of adolescent students (N = 1088) from Brandenburg, Germany: (1) peer-dependent MT, (2) teacher-dependent MT, (3)…

  7. Types of Parent Verbal Responsiveness that Predict Language in Young Children with Autism Spectrum Disorder

    ERIC Educational Resources Information Center

    McDuffie, Andrea; Yoder, Paul

    2010-01-01

    Purpose: This study examined short-term predictive associations between 5 different types of parent verbal responsiveness and later spoken vocabulary for 32 young children with a confirmed diagnosis of autism spectrum disorder (ASD). Method: Parent verbal utterances were coded from videotapes of naturalistic parent-child play sessions using…

  8. Predicted 25-hydroxyvitamin D Score and incident type 2 diabetes in the Framingham Offspring Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accumulating evidence suggests that vitamin D is involved in the development of type 2 diabetes (T2D). Our objective was to examine the relation between vitamin D status and incidence of T2D. We used a subsample of 1972 Framingham Offspring Study participants to develop a regression model to predict...

  9. Predicted 25-hydroxyvitamin D score and incident type 2 diabetes in the Framingham Offspring Study

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Accumulating evidence suggests that vitamin D is involved in the development of type 2 diabetes (T2D). Our objective was to examine the relation between vitamin D status and incidence of T2D. We used a subsample of 1972 Framingham Offspring Study participants to develop a regression model to predict...

  10. Prediction of Type II Radio Bursts Associated with Large CME Events

    NASA Astrophysics Data System (ADS)

    Cairns, Iver; Schmidt, Joachim

    Type II radio bursts are associated with shocks in the corona and solar wind, either driven by CMEs or else by blast waves. Recently we coupled the advanced 3D MHD BATS-R-US code of Toth, Gombosi, and colleagues with our kinetic ``bolt-on'' theory for type II emission. Initialising the simulation code with event specific coronal and CME data, the combined code can be used to predict the dynamic spectrum of type II emission for a specific radio event. We demonstrate very good agreement with Wind spacecraft observations for three type II bursts, one on 15 February 2011 and two on 7 March 2012 (associated with successive CMEs from different sides of the same active region). The intensities, frequencies, and times of fundamental and harmonic type II emission are predicted very well from the high corona to 1 AU (frequencies ~ 20 MHz - 30 kHz). The islands of increased emission correspond to different regions of the shock interacting with coronal structures, with streamers typically corresponding to reduced emission. The results provide strong evidence that both the type II theory and the BATS-R-US (driven with event-specific data) are accurate. They also provide strong evidence that the observation and detailed theoretical modelling of type II bursts can in principle provide warnings with lead-times of over a day for large and fast CMEs that might produce space weather at Earth. The MHD code can also predict whether the CME will hit Earth's magnetopause and the magnetic field direction at the magnetopause as the shock, sheath, and CME, vital quantities for predicting space weather at Earth.

  11. Nucleosynthesis Predictions for Intermediate-Mass AGB Stars: Comparison to Observations of Type I Planetary Nebulae

    NASA Technical Reports Server (NTRS)

    Karakas, Amanda I.; vanRaai, Mark A.; Lugaro, Maria; Sterling, Nicholas C.; Dinerstein, Harriet L.

    2008-01-01

    Type I planetary nebulae (PNe) have high He/H and N/O ratios and are thought to be descendants of stars with initial masses of approx. 3-8 Stellar Mass. These characteristics indicate that the progenitor stars experienced proton-capture nucleosynthesis at the base of the convective envelope, in addition to the slow neutron capture process operating in the He-shell (the s-process). We compare the predicted abundances of elements up to Sr from models of intermediate-mass asymptotic giant branch (AGB) stars to measured abundances in Type I PNe. In particular, we compare predictions and observations for the light trans-iron elements Se and Kr, in order to constrain convective mixing and the s-process in these stars. A partial mixing zone is included in selected models to explore the effect of a C-13 pocket on the s-process yields. The solar-metallicity models produce enrichments of [(Se, Kr)/Fe] less than or approx. 0.6, consistent with Galactic Type I PNe where the observed enhancements are typically less than or approx. 0.3 dex, while lower metallicity models predict larger enrichments of C, N, Se, and Kr. O destruction occurs in the most massive models but it is not efficient enough to account for the greater than or approx. 0.3 dex O depletions observed in some Type I PNe. It is not possible to reach firm conclusions regarding the neutron source operating in massive AGB stars from Se and Kr abundances in Type I PNe; abundances for more s-process elements may help to distinguish between the two neutron sources. We predict that only the most massive (M grester than or approx.5 Stellar Mass) models would evolve into Type I PNe, indicating that extra-mixing processes are active in lower-mass stars (3-4 Stellar Mass), if these stars are to evolve into Type I PNe.

  12. Population-Level Prediction of Type 2 Diabetes From Claims Data and Analysis of Risk Factors.

    PubMed

    Razavian, Narges; Blecker, Saul; Schmidt, Ann Marie; Smith-McLallen, Aaron; Nigam, Somesh; Sontag, David

    2015-12-01

    We present a new approach to population health, in which data-driven predictive models are learned for outcomes such as type 2 diabetes. Our approach enables risk assessment from readily available electronic claims data on large populations, without additional screening cost. Proposed model uncovers early and late-stage risk factors. Using administrative claims, pharmacy records, healthcare utilization, and laboratory results of 4.1 million individuals between 2005 and 2009, an initial set of 42,000 variables were derived that together describe the full health status and history of every individual. Machine learning was then used to methodically enhance predictive variable set and fit models predicting onset of type 2 diabetes in 2009-2011, 2010-2012, and 2011-2013. We compared the enhanced model with a parsimonious model consisting of known diabetes risk factors in a real-world environment, where missing values are common and prevalent. Furthermore, we analyzed novel and known risk factors emerging from the model at different age groups at different stages before the onset. Parsimonious model using 21 classic diabetes risk factors resulted in area under ROC curve (AUC) of 0.75 for diabetes prediction within a 2-year window following the baseline. The enhanced model increased the AUC to 0.80, with about 900 variables selected as predictive (p < 0.0001 for differences between AUCs). Similar improvements were observed for models predicting diabetes onset 1-3 years and 2-4 years after baseline. The enhanced model improved positive predictive value by at least 50% and identified novel surrogate risk factors for type 2 diabetes, such as chronic liver disease (odds ratio [OR] 3.71), high alanine aminotransferase (OR 2.26), esophageal reflux (OR 1.85), and history of acute bronchitis (OR 1.45). Liver risk factors emerge later in the process of diabetes development compared with obesity-related factors such as hypertension and high hemoglobin A1c. In conclusion

  13. Tensile-shear correlations obtained from shear punch test technique using a modified experimental approach

    NASA Astrophysics Data System (ADS)

    Karthik, V.; Visweswaran, P.; Vijayraghavan, A.; Kasiviswanathan, K. V.; Raj, Baldev

    2009-09-01

    Shear punch testing has been a very useful technique for evaluating mechanical properties of irradiated alloys using a very small volume of material. The load-displacement data is influenced by the compliance of the fixture components. This paper describes a modified experimental approach where the compliances of the punch and die components are eliminated. The analysis of the load-displacement data using the modified setup for various alloys like low carbon steel, SS316, modified 9Cr-1Mo, 2.25Cr-1Mo indicate that the shear yield strength evaluated at 0.2% offset of normalized displacement relates to the tensile YS as per the Von Mises yield relation ( σys = 1.73 τys). A universal correlation of type UTS = mτmax where m is a function of strain hardening exponent, is seen to be obeyed for all the materials in this study. The use of analytical models developed for blanking process are explored for evaluating strain hardening exponent from the load-displacement data. This study is directed towards rationalizing the tensile-shear empirical correlations for a more reliable prediction of tensile properties from shear punch tests.

  14. Apparatus for shearing spent nuclear fuel assemblies

    DOEpatents

    Weil, Bradley S.; Metz, III, Curtis F.

    1980-01-01

    A method and apparatus are described for shearing spent nuclear fuel assemblies of the type comprising an array of fuel pins disposed within an outer metal shell or shroud. A spent fuel assembly is first compacted in a known manner and then incrementally sheared using fixed and movable shear blades having matched laterally projecting teeth which slidably intermesh to provide the desired shearing action. Incremental advancement of the fuel assembly after each shear cycle is limited to a distance corresponding to the lateral projection of the teeth to ensure fuel assembly breakup into small uniform segments which are amenable to remote chemical processing.

  15. Higher Fibrinogen Levels Predict Progression of Coronary Artery Calcification in Adults with Type 1 Diabetes

    PubMed Central

    Rodrigues, T.C.; Snell-Bergeon, J.K.; Maahs, D.M; Kinney, G.L.; Rewers, M.

    2010-01-01

    Aim To determine whether fibrinogen levels predict independently progression of coronary artery calcification (CAC) in adults with type 1 diabetes. Methods Data from a prospective cohort - the Coronary Artery Calcification in Type 1 Diabetes Study - were evaluated. Fibrinogen levels at baseline were separated into quartiles. CAC was measured twice and averaged at baseline and at follow-up 2.4 ± 0.4 years later. CAC progressors were defined as participants whose square-root transformed CAC volume increased by ≥ 2.53 or development mm of clinical coronary artery disease during the follow-up period. Results Fibrinogen levels were higher in progressors than in non-progressors (276 ± 61 mg/dl versus 259 ± 61 mg/dl, p = 0.0003). CAC progression, adjusted for known cardiovascular risk factors, increased in the highest quartile. Conclusions Higher fibrinogen levels predict CAC progression in type 1 diabetes subjects, independent of standard cardiovascular risk factors. PMID:20079495

  16. Dominant simple-shear deformation during peak metamorphism for the lower portion of the Greater Himalayan Sequence in West Nepal: New implications for hybrid channel flow-type mechanisms in the Dolpo region

    NASA Astrophysics Data System (ADS)

    Frassi, Chiara

    2015-12-01

    I conducted new vorticity and deformation temperatures studies to test competing models of the exhumation of the mid-crustal rocks exposed in the Dolpo region (West Nepal). My results indicate that the Main Central Thrust is located ∼5 km structurally below the previous mapped locations. Deformation temperature increasing up structural section from ∼450 °C to ∼650 °C and overlap with peak metamorphic temperature indicating that penetrative shearing was responsible for the exhumation of the GHS occurred at "close" to peak metamorphic conditions. I interpreted the telescoping and the inversion of the paleo-isotherms at the base of the GHS as produced mainly by a sub-simple shearing (Wm = 0.88-1) pervasively distributed through the lower portion of the GHS. My results are consistent with hybrid channel flow-type models where the boundary between lower and upper portions of the GHS, broadly corresponding to the tectonometamorphic discontinuity recently documented in west Nepal, represents the limit between buried material, affected by dominant simple shearing, and exhumed material affected by a general flow dominates by pure shearing. This interpretation is consistent with the recent models suggesting the simultaneous operation of channel flow- and critical wedge-type processes at different structural depth.

  17. Computational prediction of type III and IV secreted effectors in Gram-negative bacteria

    SciTech Connect

    McDermott, Jason E.; Corrigan, Abigail L.; Peterson, Elena S.; Oehmen, Christopher S.; Niemann, George; Cambronne, Eric; Sharp, Danna; Adkins, Joshua N.; Samudrala, Ram; Heffron, Fred

    2011-01-01

    In this review, we provide an overview of the methods employed by four recent papers that described novel methods for computational prediction of secreted effectors from type III and IV secretion systems in Gram-negative bacteria. The results of the studies in terms of performance at accurately predicting secreted effectors and similarities found between secretion signals that may reflect biologically relevant features for recognition. We discuss the web-based tools for secreted effector prediction described in these studies and announce the availability of our tool, the SIEVEserver (http://www.biopilot.org). Finally, we assess the accuracy of the three type III effector prediction methods on a small set of proteins not known prior to the development of these tools that we have recently discovered and validated using both experimental and computational approaches. Our comparison shows that all methods use similar approaches and, in general arrive at similar conclusions. We discuss the possibility of an order-dependent motif in the secretion signal, which was a point of disagreement in the studies. Our results show that there may be classes of effectors in which the signal has a loosely defined motif, and others in which secretion is dependent only on compositional biases. Computational prediction of secreted effectors from protein sequences represents an important step toward better understanding the interaction between pathogens and hosts.

  18. Comparison of Methods for Renal Risk Prediction in Patients with Type 2 Diabetes (ZODIAC-36)

    PubMed Central

    Riphagen, Ineke J.; Kleefstra, Nanne; Drion, Iefke; Alkhalaf, Alaa; van Diepen, Merel; Cao, Qi; Groenier, Klaas H.; Landman, Gijs W. D.; Navis, Gerjan; Bilo, Henk J. G.; Bakker, Stephan J. L.

    2015-01-01

    Background Patients with diabetes are at high risk of death prior to reaching end-stage renal disease, but most models predicting the risk of kidney disease do not take this competing risk into account. We aimed to compare the performance of Cox regression and competing risk models for prediction of early- and late-stage renal complications in type 2 diabetes. Methods Patients with type 2 diabetes participating in the observational ZODIAC study were included. Prediction models for (micro)albuminuria and 50% increase in serum creatinine (SCr) were developed using Cox regression and competing risk analyses. Model performance was assessed by discrimination and calibration. Results During a total follow-up period of 10 years, 183 out of 640 patients (28.6%) with normoalbuminuria developed (micro)albuminuria, and 22 patients (3.4%) died without developing (micro)albuminuria (i.e. experienced the competing event). Seventy-nine out of 1,143 patients (6.9%) reached the renal end point of 50% increase in SCr, while 219 (19.2%) died without developing the renal end point. Performance of the Cox and competing risk models predicting (micro)albuminuria was similar and differences in predicted risks were small. However, the Cox model increasingly overestimated the risk of increase in SCr in presence of a substantial number of competing events, while the performance of the competing risk model was quite good. Conclusions In this study, we demonstrated that, in case of substantial numbers of competing events, it is important to account for the competing risk of death in renal risk prediction in patients with type 2 diabetes. PMID:25775414

  19. The value of surrogate endpoints for predicting real-world survival across five cancer types.

    PubMed

    Shafrin, Jason; Brookmeyer, Ron; Peneva, Desi; Park, Jinhee; Zhang, Jie; Figlin, Robert A; Lakdawalla, Darius N

    2016-04-01

    Objective It is unclear how well different outcome measures in randomized controlled trials (RCTs) perform in predicting real-world cancer survival. We assess the ability of RCT overall survival (OS) and surrogate endpoints - progression-free survival (PFS) and time to progression (TTP) - to predict real-world OS across five cancers. Methods We identified 20 treatments and 31 indications for breast, colorectal, lung, ovarian, and pancreatic cancer that had a phase III RCT reporting median OS and median PFS or TTP. Median real-world OS was determined using a Kaplan-Meier estimator applied to patients in the Surveillance and Epidemiology End Results (SEER)-Medicare database (1991-2010). Performance of RCT OS and PFS/TTP in predicting real-world OS was measured using t-tests, median absolute prediction error, and R(2) from linear regressions. Results Among 72,600 SEER-Medicare patients similar to RCT participants, median survival was 5.9 months for trial surrogates, 14.1 months for trial OS, and 13.4 months for real-world OS. For this sample, regression models using clinical trial OS and trial surrogates as independent variables predicted real-world OS significantly better than models using surrogates alone (P = 0.026). Among all real-world patients using sample treatments (N = 309,182), however, adding trial OS did not improve predictive power over predictions based on surrogates alone (P = 0.194). Results were qualitatively similar using median absolute prediction error and R(2) metrics. Conclusions Among the five tumor types investigated, trial OS and surrogates were each independently valuable in predicting real-world OS outcomes for patients similar to trial participants. In broader real-world populations, however, trial OS added little incremental value over surrogates alone. PMID:26743800

  20. Prediction of spurious HLA class II typing results using probabilistic classification.

    PubMed

    Schöfl, Gerhard; Schmidt, Alexander H; Lange, Vinzenz

    2016-03-01

    While modern high-throughput sequence-based HLA genotyping methods generally provide highly accurate typing results, artefacts may nonetheless arise for numerous reasons, such as sample contamination, sequencing errors, read misalignments, or PCR amplification biases. To help detecting spurious typing results, we tested the performance of two probabilistic classifiers (binary logistic regression and random forest models) based on population-specific genotype frequencies. We trained the model using high-resolution typing results for HLA-DRB1, DQB1, and DPB1 from large samples of German, Polish and UK-based donors. The high predictive capacity of the best models replicated both in 10-fold cross-validation for each gene and in using independent evaluation data (AUC 0.820-0.893). While genotype frequencies alone provide enough predictive power to render the model generally useful for highlighting potentially spurious typing results, the inclusion of workflow-specific predictors substantially increases prediction specificity. Low initial DNA concentrations in combination with low-volume PCR reactions form a major source of stochastic error specific to the Fluidigm chip-based workflow at DKMS Life Science Lab. The addition of DNA concentrations as a predictor variable thus substantially increased AUC (0.947-0.959) over purely frequency-based models. PMID:26826450

  1. JPPRED: Prediction of Types of J-Proteins from Imbalanced Data Using an Ensemble Learning Method

    PubMed Central

    Zhang, Lina; Zhang, Chengjin; Gao, Rui; Yang, Runtao

    2015-01-01

    Different types of J-proteins perform distinct functions in chaperone processes and diseases development. Accurate identification of types of J-proteins will provide significant clues to reveal the mechanism of J-proteins and contribute to developing drugs for diseases. In this study, an ensemble predictor called JPPRED for J-protein prediction is proposed with hybrid features, including split amino acid composition (SAAC), pseudo amino acid composition (PseAAC), and position specific scoring matrix (PSSM). To deal with the imbalanced benchmark dataset, the synthetic minority oversampling technique (SMOTE) and undersampling technique are applied. The average sensitivity of JPPRED based on above-mentioned individual feature spaces lies in the range of 0.744–0.851, indicating the discriminative power of these features. In addition, JPPRED yields the highest average sensitivity of 0.875 using the hybrid feature spaces of SAAC, PseAAC, and PSSM. Compared to individual base classifiers, JPPRED obtains more balanced and better performance for each type of J-proteins. To evaluate the prediction performance objectively, JPPRED is compared with previous study. Encouragingly, JPPRED obtains balanced performance for each type of J-proteins, which is significantly superior to that of the existing method. It is anticipated that JPPRED can be a potential candidate for J-protein prediction. PMID:26587542

  2. Factors Predictive of Type of Powered Mobility Received by Veterans with Disability

    PubMed Central

    Rabadi, Meheroz H.; Vincent, Andrea S.

    2015-01-01

    Background The goal of this observational study was to determine factors predictive of the type of powered mobility prescribed to veterans with disability. Material/Methods A retrospective chart review was conducted for all veterans (n=170) who received powered mobility from a designated power mobility clinic. Logistic regression analysis was used to determined factors predictive of the type of powered mobility provided. Results Sixty-four (38%) veterans were provided powered wheelchairs and 106 (62%) were provided powered scooters. Of the variables examined, only primary medical conditions for referral and disability severity (as measured by the 2-minute timed walk test; 2-MWT) were predictive of the types of powered mobility prescribed. Veterans who were able to walk longer distances were more likely to be prescribed powered scooters. Age, gender, race, level of education, marital and employment status, number of chronic medical conditions, and upper and lower limb muscle strength were not significant predictors. Conclusions This study suggests that the primary medical conditions for referral and 2-MWT can assist clinicians in the determination of the type of powered mobility to prescribe to veterans with disability. PMID:25955214

  3. Computational approaches for classification and prediction of P-type ATPase substrate specificity in Arabidopsis.

    PubMed

    Zinati, Zahra; Alemzadeh, Abbas; KayvanJoo, Amir Hossein

    2016-01-01

    As an extended gamut of integral membrane (extrinsic) proteins, and based on their transporting specificities, P-type ATPases include five subfamilies in Arabidopsis, inter alia, P4ATPases (phospholipid-transporting ATPase), P3AATPases (plasma membrane H(+) pumps), P2A and P2BATPases (Ca(2+) pumps) and P1B ATPases (heavy metal pumps). Although, many different computational methods have been developed to predict substrate specificity of unknown proteins, further investigation needs to improve the efficiency and performance of the predicators. In this study, various attribute weighting and supervised clustering algorithms were employed to identify the main amino acid composition attributes, which can influence the substrate specificity of ATPase pumps, classify protein pumps and predict the substrate specificity of uncharacterized ATPase pumps. The results of this study indicate that both non-reduced coefficients pertaining to absorption and Cys extinction within 280 nm, the frequencies of hydrogen, Ala, Val, carbon, hydrophilic residues, the counts of Val, Asn, Ser, Arg, Phe, Tyr, hydrophilic residues, Phe-Phe, Ala-Ile, Phe-Leu, Val-Ala and length are specified as the most important amino acid attributes through applying the whole attribute weighting models. Here, learning algorithms engineered in a predictive machine (Naive Bays) is proposed to foresee the Q9LVV1 and O22180 substrate specificities (P-type ATPase like proteins) with 100 % prediction confidence. For the first time, our analysis demonstrated promising application of bioinformatics algorithms in classifying ATPases pumps. Moreover, we suggest the predictive systems that can assist towards the prediction of the substrate specificity of any new ATPase pumps with the maximum possible prediction confidence. PMID:27186030

  4. Surface and downhole shear wave seismic methods for thick soil site investigations

    USGS Publications Warehouse

    Hunter, J.A.; Benjumea, B.; Harris, J.B.; Miller, R.D.; Pullan, S.E.; Burns, R.A.; Good, R.L.

    2002-01-01

    Shear wave velocity-depth information is required for predicting the ground motion response to earthquakes in areas where significant soil cover exists over firm bedrock. Rather than estimating this critical parameter, it can be reliably measured using a suite of surface (non-invasive) and downhole (invasive) seismic methods. Shear wave velocities from surface measurements can be obtained using SH refraction techniques. Array lengths as large as 1000 m and depth of penetration to 250 m have been achieved in some areas. High resolution shear wave reflection techniques utilizing the common midpoint method can delineate the overburden-bedrock surface as well as reflecting boundaries within the overburden. Reflection data can also be used to obtain direct estimates of fundamental site periods from shear wave reflections without the requirement of measuring average shear wave velocity and total thickness of unconsolidated overburden above the bedrock surface. Accurate measurements of vertical shear wave velocities can be obtained using a seismic cone penetrometer in soft sediments, or with a well-locked geophone array in a borehole. Examples from thick soil sites in Canada demonstrate the type of shear wave velocity information that can be obtained with these geophysical techniques, and show how these data can be used to provide a first look at predicted ground motion response for thick soil sites. ?? 2002 Published by Elsevier Science Ltd.

  5. Modelling the effects of horizontal and vertical shear in stratified turbulent flows

    NASA Astrophysics Data System (ADS)

    Umlauf, Lars

    2005-05-01

    Direct numerical simulations (DNS) and model results from a number of one-point turbulence models are compared for homogeneous, stably stratified flows. Because of their wide spread use in numerical ocean modelling, only explicit algebraic second-moment models are investigated. Considered are two types of shear flows with either purely vertical or purely horizontal shear. The dissipation rate is evaluated from the observation that the shear-number becomes independent of stratification for low to moderate Richardson numbers as soon as the flow approaches self-similarity. For the cases with vertical shear, it is found that all statistical models essentially reproduced the DNS results, though with different accuracy. In contrast, only the most recent model was able to predict the salient features of horizontally sheared flows, i.e. a steady-state Richardson number that is about an order of magnitude larger and a vertical mixing efficiency that is about twice as large compared to the case with vertical shear. This model also reproduced other key parameters like the turbulent Froude number and the turbulent Prandtl number with good accuracy, but it failed to predict quantitatively the reduction of the shear anisotropy with increasing stratification. For strong stratification, none of the models was able to describe the rapid decrease of the mixing efficiency associated with the collapse and fossilisation of turbulence.

  6. Geometrical analysis of the Punta del Pedrón shear zone (Asturias, Spain): Implications related to exploration of Salave Gold-type mineralization

    NASA Astrophysics Data System (ADS)

    Gumiel, Pablo; Martín-Izard, Agustín; Arias, Mónica; Rodríguez-Terente, Luis

    2008-03-01

    The Salave Gold deposit is located at the northern end of the Oscos Gold Belt which forms part of the Asturian-Leonese Zone of the Variscan Massif. The Gold Belt and the Salave deposit are genetically related to the emplacement of post-kinematic granitoids which were largely controlled by Variscan fracture systems. A geometrical analysis following the McCoss [McCoss, A.M., 1986. Simple construction for deformation in transpression/transtension zones. Journal of Structural Geology 8(6), 715-718] method has been utilized to discriminate the transpressional, transtensional, and simple shear components, and the displacement vectors (S-vectors) of the Punta del Pedrón shear zone. A contour map of the S-vector orientations is consistent with the contour map of the calculated extension of the whole area, and shows those shear zones where extensional and contractional components have been determined. Extension is higher ( E = 15%) towards the east where transtension is predominant near the Salave gold deposit. This deposit is located at the intersection of the extensional sinistral shear zones striking between 130° and 140°, which promoted dilation and the emplacement of the Salave granodiorite, with the dextral shear zones striking between 070° and 080°. Extension was transferred to the dextral shear zones, and associated 030° pinnate veins, in a transtensional stage which promoted connected vein systems and localized fluid-flow. This gave rise to the alteration patterns of the deposit and ore deposition in an area previously affected by the Mondoñedo thrust system. The use of this geometrical method, with limitations and several assumptions discussed in the text, and the analysis of the scaling properties of the vein sets in traverses can be utilized in the field to aid in mineral exploration.

  7. A Gram-Negative Bacterial Secreted Protein Types Prediction Method Based on PSI-BLAST Profile

    PubMed Central

    2016-01-01

    Prediction of secreted protein types based solely on sequence data remains to be a challenging problem. In this study, we extract the long-range correlation information and linear correlation information from position-specific score matrix (PSSM). A total of 6800 features are extracted at 17 different gaps; then, 309 features are selected by a filter feature selection method based on the training set. To verify the performance of our method, jackknife and independent dataset tests are performed on the test set and the reported overall accuracies are 93.60% and 100%, respectively. Comparison of our results with the existing method shows that our method provides the favorable performance for secreted protein type prediction. PMID:27563663

  8. A shear deformable theory of laminated composite shallow shell-type panels and their response analysis. I - Free vibration and buckling

    NASA Technical Reports Server (NTRS)

    Librescu, L.; Khdeir, A. A.; Frederick, D.

    1989-01-01

    This paper deals with the substantiation of a shear deformable theory of cross-ply laminated composite shallow shells. While the developed theory preserves all the advantages of the first order transverse shear deformation theory it succeeds in eliminating some of its basic shortcomings. The theory is further employed in the analysis of the eigenvibration and static buckling problems of doubly curved shallow panels. In this context, the state space concept is used in conjunction with the Levy method, allowing one to analyze these problems in a unified manner, for a variety of boundary conditions. Numerical results are presented and some pertinent conclusions are formulated.

  9. Correlation of predicted and measured thermal stresses on a truss-type aircraft structure

    NASA Technical Reports Server (NTRS)

    Jenkins, J. M.; Schuster, L. S.; Carter, A. L.

    1978-01-01

    A test structure representing a portion of a hypersonic vehicle was instrumented with strain gages and thermocouples. This test structure was then subjected to laboratory heating representative of supersonic and hypersonic flight conditions. A finite element computer model of this structure was developed using several types of elements with the NASA structural analysis (NASTRAN) computer program. Temperature inputs from the test were used to generate predicted model thermal stresses and these were correlated with the test measurements.

  10. Partition dataset according to amino acid type improves the prediction of deleterious non-synonymous SNPs

    SciTech Connect

    Yang, Jing; Li, Yuan-Yuan; Li, Yi-Xue; Ye, Zhi-Qiang

    2012-03-02

    Highlights: Black-Right-Pointing-Pointer Proper dataset partition can improve the prediction of deleterious nsSNPs. Black-Right-Pointing-Pointer Partition according to original residue type at nsSNP is a good criterion. Black-Right-Pointing-Pointer Similar strategy is supposed promising in other machine learning problems. -- Abstract: Many non-synonymous SNPs (nsSNPs) are associated with diseases, and numerous machine learning methods have been applied to train classifiers for sorting disease-associated nsSNPs from neutral ones. The continuously accumulated nsSNP data allows us to further explore better prediction approaches. In this work, we partitioned the training data into 20 subsets according to either original or substituted amino acid type at the nsSNP site. Using support vector machine (SVM), training classification models on each subset resulted in an overall accuracy of 76.3% or 74.9% depending on the two different partition criteria, while training on the whole dataset obtained an accuracy of only 72.6%. Moreover, the dataset was also randomly divided into 20 subsets, but the corresponding accuracy was only 73.2%. Our results demonstrated that partitioning the whole training dataset into subsets properly, i.e., according to the residue type at the nsSNP site, will improve the performance of the trained classifiers significantly, which should be valuable in developing better tools for predicting the disease-association of nsSNPs.

  11. Type II solar radio bursts predicted by 3-D MHD CME and kinetic radio emission simulations

    NASA Astrophysics Data System (ADS)

    Schmidt, J. M.; Cairns, Iver H.

    2014-01-01

    Impending space weather events at Earth are often signaled by type II solar radio bursts. These bursts are generated upstream of shock waves driven by coronal mass ejections (CMEs) that move away from the Sun. We combine elaborate three-dimensional (3-D) magnetohydrodynamic predictions of realistic CMEs near the Sun with a recent analytic kinetic radiation theory in order to simulate two type II bursts. Magnetograms of the Sun are used to reconstruct initial solar magnetic and active region fields for the modeling. STEREO spacecraft data are used to dimension the flux rope of the initial CME, launched into an empirical data-driven corona and solar wind. We demonstrate impressive accuracy in time, frequency, and intensity for the two type II bursts observed by the Wind spacecraft on 15 February 2011 and 7 March 2012. Propagation of the simulated CME-driven shocks through coronal plasmas containing preexisting density and magnetic field structures that stem from the coronal setup and CME initiation closely reproduce the isolated islands of type II emission observed. These islands form because of a competition between the growth of the radio source due to spherical expansion and a fragmentation of the radio source due to increasingly radial fields in the nose region of the shock and interactions with streamers in the flank regions of the shock. Our study provides strong support for this theory for type II bursts and implies that the physical processes involved are understood. It also supports a near-term capability to predict and track these events for space weather predictions.

  12. Nucleation of shear bands in amorphous alloys

    PubMed Central

    Perepezko, John H.; Imhoff, Seth D.; Chen, Ming-Wei; Wang, Jun-Qiang; Gonzalez, Sergio

    2014-01-01

    The initiation and propagation of shear bands is an important mode of localized inhomogeneous deformation that occurs in a wide range of materials. In metallic glasses, shear band development is considered to center on a structural heterogeneity, a shear transformation zone that evolves into a rapidly propagating shear band under a shear stress above a threshold. Deformation by shear bands is a nucleation-controlled process, but the initiation process is unclear. Here we use nanoindentation to probe shear band nucleation during loading by measuring the first pop-in event in the load–depth curve which is demonstrated to be associated with shear band formation. We analyze a large number of independent measurements on four different bulk metallic glasses (BMGs) alloys and reveal the operation of a bimodal distribution of the first pop-in loads that are associated with different shear band nucleation sites that operate at different stress levels below the glass transition temperature, Tg. The nucleation kinetics, the nucleation barriers, and the density for each site type have been determined. The discovery of multiple shear band nucleation sites challenges the current view of nucleation at a single type of site and offers opportunities for controlling the ductility of BMG alloys. PMID:24594599

  13. Diabetic Retinopathy Is Strongly Predictive of Cardiovascular Autonomic Neuropathy in Type 2 Diabetes

    PubMed Central

    Huang, Chih-Cheng; Lee, Jong-Jer; Lin, Tsu-Kung; Tsai, Nai-Wen; Huang, Chi-Ren; Chen, Shu-Fang; Lu, Cheng-Hsien; Liu, Rue-Tsuan

    2016-01-01

    A well-established, comprehensive, and simple test battery was used here to re-evaluate risk factors for cardiovascular autonomic neuropathy (CAN) in type 2 diabetes. One hundred and seventy-four patients with type 2 diabetes were evaluated through the methods of deep breathing and Valsalva maneuver for correlation with factors that might influence the presence and severity of CAN. The Composite Autonomic Scoring Scale (CASS) was used to grade the severity of autonomic impairment, and CAN was defined as a CASS score ≥2. Results showed that nephropathy, duration of diabetes, blood pressure, uric acid, and the presence of retinopathy and metabolic syndrome significantly correlated with the CASS score. Age may not be a risk factor for diabetic CAN. However, the effects of diabetes on CAN are more prominent in younger patients than in older ones. Diabetic retinopathy is the most significant risk factor predictive of the presence of CAN in patients with type 2 diabetes. PMID:26955641

  14. Shear Mechanics of the TMJ Disc

    PubMed Central

    Juran, C.M.; Dolwick, M.F.; McFetridge, P.S.

    2012-01-01

    The temporomandibular joint (TMJ) is a complex hinge and gliding joint that induces significant shear loads onto the fibrocartilage TMJ disc during jaw motion. The purpose of this study was to assess regional variation in the disc’s shear loading characteristics under physiologically relevant loads and to associate those mechanical findings with common clinical observations of disc fatigue and damage. Porcine TMJ discs were compressed between an axially translating bottom platen and a 2.5-cm-diameter indenter within a hydrated testing chamber. Discs were cyclically sheared at 0.5, 1, or 5 Hz to 1, 3, or 5% shear strain. Within the anterior and intermediate regions of the disc when sheared in the anteroposterior direction, both shear and compressive moduli experienced a significant decrease from instantaneous to steady state, while the posterior region’s compressive modulus decreased approximately 5%, and no significant loss of shear modulus was noted. All regions retained their shear modulus within 0.5% of instantaneous values when shear was applied in the mediolateral direction. The results of the disc’s regional shear mechanics suggest an observable and predictable link with the common clinical observation that the posterior region of the disc is most often the zone in which fatigue occurs, which may lead to disc damage and perforation. PMID:23166043

  15. Mem-PHybrid: hybrid features-based prediction system for classifying membrane protein types.

    PubMed

    Hayat, Maqsood; Khan, Asifullah

    2012-05-01

    Membrane proteins are a major class of proteins and encoded by approximately 20% to 30% of genes in most organisms. In this work, a two-layer novel membrane protein prediction system, called Mem-PHybrid, is proposed. It is able to first identify the protein query as a membrane or nonmembrane protein. In the second level, it further identifies the type of membrane protein. The proposed Mem-PHybrid prediction system is based on hybrid features, whereby a fusion of both the physicochemical and split amino acid composition-based features is performed. This enables the proposed Mem-PHybrid to exploit the discrimination capabilities of both types of feature extraction strategy. In addition, minimum redundancy and maximum relevance has also been applied to reduce the dimensionality of a feature vector. We employ random forest, evidence-theoretic K-nearest neighbor, and support vector machine (SVM) as classifiers and analyze their performance on two datasets. SVM using hybrid features yields the highest accuracy of 89.6% and 97.3% on dataset1 and 91.5% and 95.5% on dataset2 for jackknife and independent dataset tests, respectively. The enhanced prediction performance of Mem-PHybrid is largely attributed to the exploitation of the discrimination power of the hybrid features and of the learning capability of SVM. Mem-PHybrid is accessible at http://www.111.68.99.218/Mem-PHybrid. PMID:22342883

  16. Hydraulic jumps with upstream shear

    NASA Astrophysics Data System (ADS)

    Ogden, Kelly; Helfrich, Karl

    2013-11-01

    Hydraulic jumps in flows with background shear are investigated, motivated by applications such as the flow over sills in Knight Inlet and the Pre-Bosphorus Channel. The full solution space and allowable solutions to several two-layer theories for hydraulic jumps with upstream shear are identified. The two-layer theories considered, including a recent theory by Borden et al. (JFM, 2012), are distinguished by how dissipation is partitioned between the layers. It is found that upstream shear with a faster and thinner lower layer causes an increase in bore speed, for a given jump height. Further, these two-layer solutions only exist for a limited range of upstream shear. 2D numerical simulations are conducted, guided by the two-layer theory solution space, and the results are compared to the theories. The simulations show the qualitative types of hydraulic transitions that occur, including undular bores, fully turbulent jumps, and conjugate state-like solutions; the type depends on the jump height and upstream shear for fixed upstream layer depths. Numerical simulations are used to investigate the mixing. Finally, a few 3D numerical simulations were made and are found to be consistent with the 2D results.

  17. Prediction of the characteristics of two types of pressure waves in the cochlea: Theoretical considerations

    NASA Astrophysics Data System (ADS)

    Andoh, Masayoshi; Wada, Hiroshi

    2004-07-01

    The aim of this study was to predict the characteristics of two types of cochlear pressure waves, so-called fast and slow waves. A two-dimensional finite-element model of the organ of Corti (OC), including fluid-structure interaction with the surrounding lymph fluid, was constructed. The geometry of the OC at the basal turn was determined from morphological measurements of others in the gerbil hemicochlea. As far as mechanical properties of the materials within the OC are concerned, previously determined mechanical properties of portions within the OC were adopted, and unknown mechanical features were determined from the published measurements of static stiffness. Time advance of the fluid-structure scheme was achieved by a staggered approach. Using the model, the magnitude and phase of the fast and slow waves were predicted so as to fit the numerically obtained pressure distribution in the scala tympani with what is known about intracochlear pressure measurement. When the predicted pressure waves were applied to the model, the numerical result of the velocity of the basilar membrane showed good agreement with the experimentally obtained velocity of the basilar membrane documented by others. Thus, the predicted pressure waves appeared to be reliable. Moreover, it was found that the fluid-structure interaction considerably influences the dynamic behavior of the OC at frequencies near the characteristic frequency.

  18. Mechanical properties of graphynes under shearing and bending

    NASA Astrophysics Data System (ADS)

    Yi, Lijun; Zhang, Yingyan; Feng, Xiqiao; Chang, Tienchong; Wang, Ji; Du, Jianke; Zhou, Jianxin

    2016-05-01

    Graphynes are the allotrope of graphene. In this work, extensive molecular dynamics simulations are performed on four different graphynes ( α - , β - , γ - , and 6,6,12-graphynes) to explore their mechanical properties (shear modulus, shear strength, and bending rigidity) under shearing and bending. While the shearing properties are anisotropic, the bending rigidity is almost independent of the chirality of graphynes. We also find that the shear modulus and shear fracture strength of graphynes decrease with increasing temperature. The effect of the percentage of the acetylenic linkages on the shear mechanical properties and bending rigidity is investigated. It is shown that the fracture shear strengths and bending rigidities of the four types of graphynes decrease, while the fracture shear strain increases, with increasing percentages of the acetylenic linkages. Significant wrinkling is observed in graphyne under shear strain. The influence of the temperatures and percentages of the acetylenic linkages on the ratio of amplitude-to-wavelength in the wrinkles are examined.

  19. Organized motions underlying turbulent shear flows

    NASA Technical Reports Server (NTRS)

    Waleffe, F.

    1990-01-01

    The objective of this project is to determine the nature and significance of the organized motions underlying turbulent shear flow. There is considerable experimental evidence for the existence of such motions. In particular, one consistently observes longitudinal streaks with a spacing of about 100 in wall units in the near-wall region of wall-bounded shear flows. Recently, an analysis based on the direct resonance mechanism has predicted the appearance of streaks with precisely such a spacing. Also, the minimum channel simulations of Jimenez and Moin have given a strong dynamical significance to that spanwise length scale. They have shown that turbulent-like flows can not be maintained when the spanwise wavelength of the motion is constrained to be less than about that critical number. A critical review of the direct resonance ideas and the non-linear theory of Benney and Gustavsson is presented first. It is shown how this leads to the later mean flow-first harmonic theory of Benney. Finally, we note that a different type of analysis has led to the prediction streaks with a similar spacing. This latter approach consists of looking for optimum fields and directly provides deep insights into why a particular structure or a particular scale should be preferred.

  20. [Prediction of lipases types by different scale pseudo-amino acid composition].

    PubMed

    Zhang, Guangya; Li, Hongchun; Gao, Jiaqiang; Fang, Baishan

    2008-11-01

    Lipases are widely used enzymes in biotechnology. Although they catalyze the same reaction, their sequences vary. Therefore, it is highly desired to develop a fast and reliable method to identify the types of lipases according to their sequences, or even just to confirm whether they are lipases or not. By proposing two scales based pseudo amino acid composition approaches to extract the features of the sequences, a powerful predictor based on k-nearest neighbor was introduced to address the problems. The overall success rates thus obtained by the 10-fold cross-validation test were shown as below: for predicting lipases and nonlipase, the success rates were 92.8%, 91.4% and 91.3%, respectively. For lipase types, the success rates were 92.3%, 90.3% and 89.7%, respectively. Among them, the Z scales based pseudo amino acid composition was the best, T scales was the second. They outperformed significantly than 6 other frequently used sequence feature extraction methods. The high success rates yielded for such a stringent dataset indicate predicting the types of lipases is feasible and the different scales pseudo amino acid composition might be a useful tool for extracting the features of protein sequences, or at lease can play a complementary role to many of the other existing approaches. PMID:19256347

  1. Predicting hydration free energies of amphetamine-type stimulants with a customized molecular model

    NASA Astrophysics Data System (ADS)

    Li, Jipeng; Fu, Jia; Huang, Xing; Lu, Diannan; Wu, Jianzhong

    2016-09-01

    Amphetamine-type stimulants (ATS) are a group of incitation and psychedelic drugs affecting the central nervous system. Physicochemical data for these compounds are essential for understanding the stimulating mechanism, for assessing their environmental impacts, and for developing new drug detection methods. However, experimental data are scarce due to tight regulation of such illicit drugs, yet conventional methods to estimate their properties are often unreliable. Here we introduce a tailor-made multiscale procedure for predicting the hydration free energies and the solvation structures of ATS molecules by a combination of first principles calculations and the classical density functional theory. We demonstrate that the multiscale procedure performs well for a training set with similar molecular characteristics and yields good agreement with a testing set not used in the training. The theoretical predictions serve as a benchmark for the missing experimental data and, importantly, provide microscopic insights into manipulating the hydrophobicity of ATS compounds by chemical modifications.

  2. Predicting hydration free energies of amphetamine-type stimulants with a customized molecular model.

    PubMed

    Li, Jipeng; Fu, Jia; Huang, Xing; Lu, Diannan; Wu, Jianzhong

    2016-09-01

    Amphetamine-type stimulants (ATS) are a group of incitation and psychedelic drugs affecting the central nervous system. Physicochemical data for these compounds are essential for understanding the stimulating mechanism, for assessing their environmental impacts, and for developing new drug detection methods. However, experimental data are scarce due to tight regulation of such illicit drugs, yet conventional methods to estimate their properties are often unreliable. Here we introduce a tailor-made multiscale procedure for predicting the hydration free energies and the solvation structures of ATS molecules by a combination of first principles calculations and the classical density functional theory. We demonstrate that the multiscale procedure performs well for a training set with similar molecular characteristics and yields good agreement with a testing set not used in the training. The theoretical predictions serve as a benchmark for the missing experimental data and, importantly, provide microscopic insights into manipulating the hydrophobicity of ATS compounds by chemical modifications. PMID:27367616

  3. Mapping between atomistic simulations and Eshelby inclusions in the shear deformation of an amorphous silicon model.

    PubMed

    Albaret, T; Tanguy, A; Boioli, F; Rodney, D

    2016-05-01

    In this paper we perform quasistatic shear simulations of model amorphous silicon bulk samples with Stillinger-Weber-type potentials. Local plastic rearrangements identified based on local energy variations are fitted through their displacement fields on collections of Eshelby spherical inclusions, allowing determination of their transformation strain tensors. The latter are then used to quantitatively reproduce atomistic stress-strain curves, in terms of both shear and pressure components. We demonstrate that our methodology is able to capture the plastic behavior predicted by different Stillinger-Weber potentials, in particular, their different shear tension coupling. These calculations justify the decomposition of plasticity into shear transformations used so far in mesoscale models and provide atomic-scale parameters that can be used to limit the empiricism needed in such models up to now. PMID:27300968

  4. Mapping between atomistic simulations and Eshelby inclusions in the shear deformation of an amorphous silicon model

    NASA Astrophysics Data System (ADS)

    Albaret, T.; Tanguy, A.; Boioli, F.; Rodney, D.

    2016-05-01

    In this paper we perform quasistatic shear simulations of model amorphous silicon bulk samples with Stillinger-Weber-type potentials. Local plastic rearrangements identified based on local energy variations are fitted through their displacement fields on collections of Eshelby spherical inclusions, allowing determination of their transformation strain tensors. The latter are then used to quantitatively reproduce atomistic stress-strain curves, in terms of both shear and pressure components. We demonstrate that our methodology is able to capture the plastic behavior predicted by different Stillinger-Weber potentials, in particular, their different shear tension coupling. These calculations justify the decomposition of plasticity into shear transformations used so far in mesoscale models and provide atomic-scale parameters that can be used to limit the empiricism needed in such models up to now.

  5. Horizontal shear zones: physical modeling of formation and structure

    NASA Astrophysics Data System (ADS)

    Bokun, A. N.

    2009-11-01

    On examples of ductile viscous materials (pastes), which demonstrated the deformational type of coagulation behavior and the reproduced zones of the horizontal shear of a brittle fracture, ductile flow, and intermediate types. The formation of coagulation agglomerates appeared well organized, both in terms of time and structurally. The found systems of fractures revealed a sequential course of the deformation process and the contribution of each system in the total structural transformation was established. By virtue of rheological analysis of coagulation structures, the basic parameters (yield strength, viscosity), and their input into the model of the deformational response (brittle, ductile), were determined. The substantial composition and its deformational properties of the material under question appeared to dictate the structure of shear zones and their general mutual organization. The rheological analysis of coagulation clusters of model materials allowed for the justified interpretation of experimental data to regulate deformation processes effectively and predict their results.

  6. Prediction of bacterial type IV secreted effectors by C-terminal features

    PubMed Central

    2014-01-01

    Background Many bacteria can deliver pathogenic proteins (effectors) through type IV secretion systems (T4SSs) to eukaryotic cytoplasm, causing host diseases. The inherent property, such as sequence diversity and global scattering throughout the whole genome, makes it a big challenge to effectively identify the full set of T4SS effectors. Therefore, an effective inter-species T4SS effector prediction tool is urgently needed to help discover new effectors in a variety of bacterial species, especially those with few known effectors, e.g., Helicobacter pylori. Results In this research, we first manually annotated a full list of validated T4SS effectors from different bacteria and then carefully compared their C-terminal sequential and position-specific amino acid compositions, possible motifs and structural features. Based on the observed features, we set up several models to automatically recognize T4SS effectors. Three of the models performed strikingly better than the others and T4SEpre_Joint had the best performance, which could distinguish the T4SS effectors from non-effectors with a 5-fold cross-validation sensitivity of 89% at a specificity of 97%, based on the training datasets. An inter-species cross prediction showed that T4SEpre_Joint could recall most known effectors from a variety of species. The inter-species prediction tool package, T4SEpre, was further used to predict new T4SS effectors from H. pylori, an important human pathogen associated with gastritis, ulcer and cancer. In total, 24 new highly possible H. pylori T4S effector genes were computationally identified. Conclusions We conclude that T4SEpre, as an effective inter-species T4SS effector prediction software package, will help find new pathogenic T4SS effectors efficiently in a variety of pathogenic bacteria. PMID:24447430

  7. T346Hunter: A Novel Web-Based Tool for the Prediction of Type III, Type IV and Type VI Secretion Systems in Bacterial Genomes

    PubMed Central

    Martínez-García, Pedro Manuel; Ramos, Cayo; Rodríguez-Palenzuela, Pablo

    2015-01-01

    T346Hunter (Type Three, Four and Six secretion system Hunter) is a web-based tool for the identification and localisation of type III, type IV and type VI secretion systems (T3SS, T4SS and T6SS, respectively) clusters in bacterial genomes. Non-flagellar T3SS (NF-T3SS) and T6SS are complex molecular machines that deliver effector proteins from bacterial cells into the environment or into other eukaryotic or prokaryotic cells, with significant implications for pathogenesis of the strains encoding them. Meanwhile, T4SS is a more functionally diverse system, which is involved in not only effector translocation but also conjugation and DNA uptake/release. Development of control strategies against bacterial-mediated diseases requires genomic identification of the virulence arsenal of pathogenic bacteria, with T3SS, T4SS and T6SS being major determinants in this regard. Therefore, computational methods for systematic identification of these specialised machines are of particular interest. With the aim of facilitating this task, T346Hunter provides a user-friendly web-based tool for the prediction of T3SS, T4SS and T6SS clusters in newly sequenced bacterial genomes. After inspection of the available scientific literature, we constructed a database of hidden Markov model (HMM) protein profiles and sequences representing the various components of T3SS, T4SS and T6SS. T346Hunter performs searches of such a database against user-supplied bacterial sequences and localises enriched regions in any of these three types of secretion systems. Moreover, through the T346Hunter server, users can visualise the predicted clusters obtained for approximately 1700 bacterial chromosomes and plasmids. T346Hunter offers great help to researchers in advancing their understanding of the biological mechanisms in which these sophisticated molecular machines are involved. T346Hunter is freely available at http://bacterial-virulence-factors.cbgp.upm.es/T346Hunter. PMID:25867189

  8. Predicting hospice appropriateness for patients with dementia of the Alzheimer's type.

    PubMed

    Marsh, G W; Prochoda, K P; Pritchett, E; Vojir, C P

    2000-11-01

    The appropriateness of admitting individuals to hospice services is determined by assessing the individual's 6-month survival prognosis. Clinical parameters that guide clinicians in assessing prognosis, however, are not well defined in cases of dementia of the Alzheimer's type (DAT) when compared to other illnesses. The Alzheimer's-Hospice Placement Evaluation Scale (AHOPE) was developed to assess the 6-month prognosis of individuals with late-stage DAT. The purposes of this study were to estimate the reliability and predictive validity of AHOPE and to test additional demographic and clinical indicators to determine their added contribution to predicting 6-month survival and hospice appropriateness. Data were collected on 112 long-term care residents with DAT at enrollment and 6 months following enrollment. Initial reliability and predictive validity of AHOPE were supported. Other demographic and clinical indicators were not predictors of 6-month survival. Although additional research is indicated, nurses can use AHOPE to enhance clinical observation and decision making for implementing appropriate care strategies for patients with end-stage DAT and their families. PMID:11078784

  9. Characterization, prediction and evolution of plant peroxisomal targeting signals type 1 (PTS1s).

    PubMed

    Reumann, S; Chowdhary, G; Lingner, T

    2016-05-01

    Our knowledge of the proteome of plant peroxisomes and their functional plasticity is far from being complete, primarily due to major technical challenges in experimental proteome research of the fragile cell organelle. Several unexpected novel plant peroxisome functions, for instance in biotin and phylloquinone biosynthesis, have been uncovered recently. Nevertheless, very few regulatory and membrane proteins of plant peroxisomes have been identified and functionally described up to now. To define the matrix proteome of plant peroxisomes, computational methods have emerged as important powerful tools. Novel prediction approaches of high sensitivity and specificity have been developed for peroxisome targeting signals type 1 (PTS1) and have been validated by in vivo subcellular targeting analyses and thermodynamic binding studies with the cytosolic receptor, PEX5. Accordingly, the algorithms allow the correct prediction of many novel peroxisome-targeted proteins from plant genome sequences and the discovery of additional organelle functions. In this review, we provide an overview of methodologies, capabilities and accuracies of available prediction algorithms for PTS1 carrying proteins. We also summarize and discuss recent quantitative, structural and mechanistic information of the interaction of PEX5 with PTS1 carrying proteins in relation to in vivo import efficiency. With this knowledge, we develop a model of how proteins likely evolved peroxisomal targeting signals in the past and still nowadays, in which order the two import pathways might have evolved in the ancient eukaryotic cell, and how the secondary loss of the PTS2 pathway probably happened in specific organismal groups. PMID:26772785

  10. Reduced shear power spectrum

    SciTech Connect

    Dodelson, Scott; Shapiro, Charles; White, Martin J.; /UC, Berkeley, Astron. Dept. /UC, Berkeley

    2005-08-01

    Measurements of ellipticities of background galaxies are sensitive to the reduced shear, the cosmic shear divided by (1-{kappa}) where {kappa} is the projected density field. They compute the difference between shear and reduced shear both analytically and with simulations. The difference becomes more important an smaller scales, and will impact cosmological parameter estimation from upcoming experiments. A simple recipe is presented to carry out the required correction.

  11. [Prediction of B cell epitopes of human papillomavirus type 16 L1 protein].

    PubMed

    Wang, Aiping; Jiang, Min; Li, Ning; Zhang, Gaiping; Qi, Yanhua; Liu, Yankai; Xi, Yu; Zhou, Jingming

    2016-04-01

    Objective To predict the B cell epitopes of human papillomavirus type 16 (HPV-16) L1 protein. Methods After fetching the sequence of HPV-16 L1 from the protein data bank of NCBI, we used Protean software of DNAStar package to analyze the secondary structures, flexibility, hydrophilicity, surface accessibility and antigenicity of the protein. Then average antigen index (AI) of dominant regions was calculated using Wu Yuzhang's method. The potential B cell epitopes of HPV-16 L1 were predicted based on a comprehensive consideration of the above parameters. Finally, the homologies of the epitopes were analyzed with BLAST online. Results The B cell epitopes of HPV-16 L1 might exist at amino acids NO. 51-58, 87-97, 214-220, 290-296, 335-341, 351-366, 408-418, 430-442 and 475-496. Analysis of homologies indicated that the dominant B cell epitopes of the HPV-16 L1 protein might present at amino acids NO. 51-58, 335-341, 351-366, 408-418, 430-442 and 475-496. The sequences, such as 51(PIKKPNNN)58, 351(SETTYKNTNFKEYLRH)366, 408(PPPGGTLEDTY)418 and 430(KHTPPAPKEDPLK)442, were unique to HPV-16 L1, while amino acids 475(KAKPKFTLGKRKATPTTSSTST)496 were identical to amino acids in HPV-16 E1, and the amino acids 335(DTTRSTN)341 were identical to amino acids in other types of HPV L1. Conclusion The B cell epitopes of HPV-16 L1 were predicted using multiple schemes. The results will provide a foundation for the further study and development of broadly protective HPV-16 vaccines. PMID:27053606

  12. Rotatable shear plate interferometer

    DOEpatents

    Duffus, Richard C.

    1988-01-01

    A rotatable shear plate interferometer comprises a transparent shear plate mounted obliquely in a tubular supporting member at 45.degree. with respect to its horizontal center axis. This tubular supporting member is supported rotatably around its center axis and a collimated laser beam is made incident on the shear plate along this center axis such that defocus in different directions can be easily measured.

  13. Weak Intraplate Volcanism Caused by Shear-Driven Upwelling

    NASA Astrophysics Data System (ADS)

    Bianco, T. A.; Conrad, C. P.; Smith, E. I.; Wessel, P.

    2011-12-01

    Statistical analysis shows that there is an unusually high incidence of recent (<10 Ma), intraplate volcanism over asthenosphere that is predicted to be rapidly shearing. This result is heavily influenced by the large number of small seamounts west of the Eastern Pacific Rise, and small-volume basaltic volcanism throughout the Western United States. Here we explore one relationship that may explain why small-volume volcanism preferentially occurs above rapidly-shearing asthenosphere. Numerical models show that asthenospheric shear can be deflected upward by lateral viscosity variations within the asthenosphere, producing "shear-driven upwelling" (SDU). To constrain the rate, duration, and surface expression of intraplate volcanism caused by SDU, we simulated 2D flow and peridotite melting in the upper 200 km of the mantle. Asthenospheric shear is driven by lithospheric plates with different thicknesses moving at 3 to 9 cm/yr, and the initial low-viscosity region is a rectangular-shaped pocket with an imposed viscosity that is two orders of magnitude smaller than the surrounding asthenosphere. Melting decreases as the pocket deforms, and reaches steady state after 3 to 12 Myr. The age progression of surface volcanism is nearly stationary in the reference frame of the plate, which distinguishes SDU from hotspot volcanism. Similar steady-state behavior occurs if the viscosity heterogeneity is induced by variations in the water content of mantle peridotite. If the pocket's low viscosity is caused by excess temperature, buoyant upwelling of the entire pocket dominates volcanism, which decreases exponentially with time. Differences in the time dependence of volcanism associated with damp and warm pockets may help identify which type of mantle heterogeneity and associated dynamic process best explains weak, intermittent, intraplate volcanism with no obvious age progression. We suggest that asthenospheric shear induced by plate motions and global mantle flow, by exciting

  14. Comparing various artificial neural network types for water temperature prediction in rivers

    NASA Astrophysics Data System (ADS)

    Piotrowski, Adam P.; Napiorkowski, Maciej J.; Napiorkowski, Jaroslaw J.; Osuch, Marzena

    2015-10-01

    A number of methods have been proposed for the prediction of streamwater temperature based on various meteorological and hydrological variables. The present study shows a comparison of few types of data-driven neural networks (multi-layer perceptron, product-units, adaptive-network-based fuzzy inference systems and wavelet neural networks) and nearest neighbour approach for short time streamwater temperature predictions in two natural catchments (mountainous and lowland) located in temperate climate zone, with snowy winters and hot summers. To allow wide applicability of such models, autoregressive inputs are not used and only easily available measurements are considered. Each neural network type is calibrated independently 100 times and the mean, median and standard deviation of the results are used for the comparison. Finally, the ensemble aggregation approach is tested. The results show that simple and popular multi-layer perceptron neural networks are in most cases not outperformed by more complex and advanced models. The choice of neural network is dependent on the way the models are compared. This may be a warning for anyone who wish to promote own models, that their superiority should be verified in different ways. The best results are obtained when mean, maximum and minimum daily air temperatures from the previous days are used as inputs, together with the current runoff and declination of the Sun from two recent days. The ensemble aggregation approach allows reducing the mean square error up to several percent, depending on the case, and noticeably diminishes differences in modelling performance obtained by various neural network types.

  15. A probability score for preoperative prediction of type 2 diabetes remission following RYGB surgery

    PubMed Central

    Still, Christopher D.; Wood, G. Craig; Benotti, Peter; Petrick, Anthony T.; Gabrielsen, Jon; Strodel, William E.; Ibele, Anna; Seiler, Jamie; Irving, Brian A.; Celaya, Melisa P.; Blackstone, Robin; Gerhard, Glenn S.; Argyropoulos, George

    2014-01-01

    BACKGROUND Type 2 diabetes (T2D) is a metabolic disease with significant medical complications. Roux-en-Y gastric bypass (RYGB) surgery is one of the few interventions that remit T2D in ~60% of patients. However, there is no accurate method for predicting preoperatively the probability for T2D remission. METHODS A retrospective cohort of 2,300 RYGB patients at Geisinger Clinic was used to identify 690 patients with T2D and complete electronic data. Two additional T2D cohorts (N=276, and N=113) were used for replication at 14 months following RYGB. Kaplan-Meier analysis was used in the primary cohort to create survival curves until remission. A Cox proportional hazards model was used to estimate the hazard ratios on T2D remission. FINDINGS Using 259 preoperative clinical variables, four (use of insulin, age, HbA1c, and type of antidiabetic medication) were sufficient to develop an algorithm that produces a type 2 diabetes remission (DiaRem) score over five years. The DiaRem score spans from 0 to 22 and was divided into five groups corresponding to five probability-ranges for T2D remission: 0–2 (88%–99%), 3–7 (64%–88%), 8–12 (23%–49%), 13–17 (11%–33%), 18–22 (2%–16%). The DiaRem scores in the replication cohorts, as well as under various definitions of diabetes remission, conformed to the DiaRem score of the primary cohort. INTERPRETATION The DiaRem score is a novel preoperative method for predicting the probability (from 2% to 99%) for T2D remission following RYGB surgery. FUNDING This research was supported by the Geisinger Health System and the National Institutes of Health. PMID:24579062

  16. Predicting major outcomes in type 1 diabetes: a model development and validation study

    PubMed Central

    Soedamah-Muthu, Sabita S.; Vergouwe, Yvonne; Costacou, Tina; Miller, Rachel G.; Zgibor, Janice; Chaturvedi, Nish; Snell-Bergeon, Janet K.; Maahs, David M.; Rewers, Marian; Forsblom, Carol; Harjutsalo, Valma; Groop, Per-Henrik; Fuller, John H.; Moons, Karel G.M.; Orchard, Trevor J.

    2015-01-01

    Aims/hypothesis Type 1 diabetes is associated with a higher risk of major vascular complications and death. A reliable method that predicts these outcomes early in the disease process would be helpful in risk classification. We therefore developed such a prognostic model and quantified its performance in independent cohorts. Methods Data were analysed of 1,973 participants with type 1 diabetes who were followed for seven years in the EURODIAB Prospective Complications Study. Strong prognostic factors of major outcomes were combined in a Weibull regression model. The model performance was tested in three different prospective cohorts: Pittsburgh Epidemiology of Diabetes Complications study (EDC, n=554), Finnish Diabetic Nephropathy study (FinnDiane, n=2,999) and Coronary Artery Calcification in Type 1 Diabetes study (CACTI, n=580). Major outcomes included major coronary heart disease, stroke, end-stage renal failure, amputations, blindness and all-cause death. Results 95 EURODIAB patients with type 1 diabetes developed major outcomes during follow-up. Prognostic factors were age, glycated haemoglobin, waist-hip ratio, albumin/creatinine ratio, and HDL cholesterol. A high risk group could be identified with 15% risk after 3-years of follow-up, 24% after 5-years and 32% after 7-years. The discriminative ability of the model was adequate with a C-statistic of 0.74. Discrimination was similar or even better in the independent cohorts: EDC, C-statistic = 0.79; FinnDiane, 0.82; and CACTI, 0.73. Conclusions/Interpretation Our prognostic model that uses easily accessible clinical features can discriminate between type 1 diabetes patients with good and poor prognosis. Such a prognostic model may be helpful in clinical practice and for risk stratification in clinical trials. PMID:25186291

  17. Identifying Precipitation Types Using Dual-Polarization-Based Radar and Numerical Weather Prediction Model Data

    NASA Astrophysics Data System (ADS)

    Seo, B. C.; Bradley, A.; Krajewski, W. F.

    2015-12-01

    The recent upgrade of dual-polarization with NEXRAD radars has assisted in improving the characterization of microphysical processes in precipitation and thus has enabled precipitation estimation based on the identified precipitation types. While this polarimetric capability promises the potential for the enhanced accuracy in quantitative precipitation estimation (QPE), recent studies show that the polarimetric estimates are still affected by uncertainties arising from the radar beam geometry/sampling space associated with the vertical variability of precipitation. The authors, first of all, focus on evaluating the NEXRAD hydrometeor classification product using ground reference data (e.g., ASOS) that provide simple categories of the observed precipitation types (e.g., rain, snow, and freezing rain). They also investigate classification uncertainty features caused by the variability of precipitation between the ground and the altitudes where radar samples. Since this variability is closely related to the atmospheric conditions (e.g., temperature) at near surface, useful information (e.g., critical thickness and temperature profile) that is not available in radar observations is retrieved from the numerical weather prediction (NWP) model data such as Rapid Refresh (RAP)/High Resolution Rapid Refresh (HRRR). The NWP retrieved information and polarimetric radar data are used together to improve the accuracy of precipitation type identification at near surface. The authors highlight major improvements and discuss limitations in the real-time application.

  18. Predicting days of high allergenic risk during Betula pollination using weather types

    NASA Astrophysics Data System (ADS)

    Laaidi, K.

      The aim of this study was to build up a picture of the influence of meteorological conditions on pollen and pollinosis, taking account of weather types, pollen concentrations in the air and pollinosis symptoms, with the aim of preventing allergic responses. The study took place in Burgundy from 1996 to 1998, during the pollination of the birch (Betula), which is the most important arborean allergen in this region. We used daily pollen data from four Hirst volumetric traps, identified weather types by Bénichou's classification, and obtained data on the occurrence of rhinitis, conjunctivitis, asthma and coughing from a sample of 100 patients. These data were analysed by multiple-component analysis. The results show that pollen dispersal is favoured by windy conditions, low relative humidity, precipitation below 2 mm and temperatures above 6°C. Such weather also favours pollinosis, but other particular meteorological situations, even if they do not assist pollen dispersal, can act directly on the development of symptoms: a decrease of temperature (3°C) led to the development of rhinitis and conjunctivitis, while strong winds were associated with many cases of conjunctivitis and asthma, owing to the irritant effect of cold or wind; asthma was favoured by temperature inversions with fog, probably because such weather corresponds to high levels of pollution, which act on bronchial hyperreactivity. Because the weather types favouring pollination and pollinosis are predicted by the meteorological office, this can constitute a tool for reducing the effect of high-risk allergenic days.

  19. A Novel Method for KIR-ligand Typing by Pyrosequencing to Predict NK Cell Alloreactivity

    PubMed Central

    Yun, Gong; Tolar, Jakub; Yerich, Anton K.; Marsh, Steven G.E.; Robinson, James; Noreen, Harriet; Blazar, Bruce R.; Miller, Jeffrey S.

    2007-01-01

    Studies have shown that KIR-ligand mismatching to predict NK cell alloreactivity may result in less relapse and better survival in patients with AML. KIR-ligands are distinguished by single nucleotide polymorphisms (SNPs) from HLA-B and HLA-C sequences. We hypothesized that pyrosequencing to determine KIR-ligand status by direct sequencing of the ligand epitope can be done as an alternative to high resolution HLA-typing. Pyrosequencing is rapid and would be particularly useful in analysis of retrospective cohorts where high resolution HLA-typing is unavailable or too expensive. To validate this assay, RNA and DNA from 70 clinical samples were tested for KIR-ligand by pyrosequencing. Primer binding to invariant regions without known SNPs was critical for KIR-ligand assignment by pyrosequencing to be in full concordance with high resolution HLA-typing. Pyrosequencing is sensitive, specific, high-throughput, inexpensive, and can rapidly screen KIR-ligand status to evaluate potential alloreactive NK cell or transplant donors. PMID:17446137

  20. Modelling the type and timing of consecutive events: application to predicting preterm birth in repeated pregnancies

    PubMed Central

    Shih, Joanna H.; Albert, Paul S.; Mendola, Pauline; Grantz, Katherine L.

    2016-01-01

    Summary Predicting the occurrence and timing of adverse pregnancy events such as preterm birth is an important analytical challenge in obstetrical practice. Developing statistical approaches that can be used to assess the risk and timing of these adverse events will provide clinicians with tools for individualized risk assessment that account for a woman’s prior pregnancy history. Often adverse pregnancy outcomes are subject to competing events; for example, interest may focus on the occurrence of pre-eclampsia-related preterm birth, where preterm birth for other reasons may serve as a competing event. We propose modelling the type and timing of adverse outcomes in repeated pregnancies. We formulate a joint model, where types of adverse outcomes across repeated pregnancies are modelled by using a polychotomous logistic regression model with random effects, and gestational ages at delivery are modelled conditionally on the types of adverse outcome. The correlation between gestational ages conditional on the adverse pregnancies is modelled by the semiparametric normal copula function. We present a two-stage estimation method and develop the asymptotic theory for the estimators proposed. The model and estimation procedure proposed are applied to the National Institute of Child Health and Human Development consecutive pregnancies study data and evaluated by simulations.

  1. Predicting days of high allergenic risk during Betula pollination using weather types.

    PubMed

    Laaidi, K

    2001-09-01

    The aim of this study was to build up a picture of the influence of meteorological conditions on pollen and pollinosis, taking account of weather types, pollen concentrations in the air and pollinosis symptoms, with the aim of preventing allergic responses. The study took place in Burgundy from 1996 to 1998, during the pollination of the birch (Betula), which is the most important arborean allergen in this region. We used daily pollen data from four Hirst volumetric traps, identified weather types by Bénichou's classification, and obtained data on the occurrence of rhinitis, conjunctivitis, asthma and coughing from a sample of 100 patients. These data were analysed by multiple-component analysis. The results show that pollen dispersal is favoured by windy conditions, low relative humidity, precipitation below 2 mm and temperatures above 6 degrees C. Such weather also favours pollinosis, but other particular meteorological situations, even if they do not assist pollen dispersal, can act directly on the development of symptoms: a decrease of temperature (3 degrees C) led to the development of rhinitis and conjunctivitis, while strong winds were associated with many cases of conjunctivitis and asthma, owing to the irritant effect of cold or wind; asthma was favoured by temperature inversions with fog, probably because such weather corresponds to high levels of pollution, which act on bronchial hyperreactivity. Because the weather types favouring pollination and pollinosis are predicted by the meteorological office, this can constitute a tool for reducing the effect of high-risk allergenic days. PMID:11594632

  2. What catches a radiologist's eye? A comprehensive comparison of feature types for saliency prediction

    NASA Astrophysics Data System (ADS)

    Alzubaidi, Mohammad; Balasubramanian, Vineeth; Patel, Ameet; Panchanathan, Sethuraman; Black, John A., Jr.

    2010-03-01

    Experienced radiologists are in short supply, and are sometimes called upon to read many images in a short amount of time. This leaves them with a limited amount of time to read images, and can lead to fatigue and stress which can be sources of error, as they overlook subtle abnormalities that they otherwise might not miss. Another factor in error rates is called satisfaction of search, where a radiologist misses a second (typically subtle) abnormality after finding the first. These types of errors are due primarily to a lack of attention to an important region of the image during the search. In this paper we discuss the use of eye tracker technology, in combination with image analysis and machine learning techniques, to learn what types of features catch the eye experienced radiologists when reading chest x-rays for diagnostic purposes, and to then use that information to produce saliency maps that predict what regions of each image might be most interesting to radiologists. We found that, out of 13 popular features types that are widely extracted to characterize images, 4 are particularly useful for this task: (1) Localized Edge Orientation Histograms (2) Haar Wavelets, (3) Gabor Filters, and (4) Steerable Filters.

  3. Predictions for mass-loss rates and terminal wind velocities of massive O-type stars

    NASA Astrophysics Data System (ADS)

    Muijres, L. E.; Vink, Jorick S.; de Koter, A.; Müller, P. E.; Langer, N.

    2012-01-01

    Context. Mass loss from massive stars forms an important aspect of the evolution of massive stars, as well as for the enrichment of the surrounding interstellar medium. Aims: Our goal is to predict accurate mass-loss rates and terminal wind velocities. These quantities can be compared to empirical values, thereby testing radiation-driven wind models. One specific topical issue is that of the so-called "weak-wind problem", where empirically derived mass-loss rates and (modified) wind momenta fall orders of magnitude short of predicted values. Methods: We employ an established Monte Carlo model and a recently suggested new line acceleration formalism to solve the wind dynamics more consistently. Results: We provide a new grid of mass-loss rates and terminal wind velocities of O-type stars, and compare the values to empirical results. Our models fail to provide mass-loss rates for main-sequence stars below a luminosity of log(L/L⊙) = 5.2, where we appear to run into a fundamental limit. At luminosities below this critical value there is insufficient momentum transferred to the wind in the region below the sonic point in order to kick-start the acceleration of the flow. This problem occurs at almost the exact location of the onset of the weak-wind problem. For O dwarfs, the boundary between being able to start a wind, and failing to do so, is at spectral type O6/O6.5. The direct cause of this failure for O6.5 stars is a combination of the lower luminosity and a lack of Fe v lines at the base of the wind. This might indicate that - in addition to radiation pressure - another mechanism is required to provide the necessary driving to initiate the wind acceleration. Conclusions: For stars more luminous than 105.2 L⊙, our new mass-loss rates are in excellent agreement with the mass-loss prescription by Vink et al. (2000, A&A, 362, 295) using our terminal wind velocities as input to this recipe. This implies that the main assumption entering the method of the Vink et al

  4. Shear layer excitation, experiment versus theory

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.; Stahl, B.

    1984-01-01

    The acoustical excitation of shear layers is investigated. Acoustical excitation causes the so-called orderly structures in shear layers and jets. Also, the deviations in the spreading rate between different shear layer experiments are due to the same excitation mechanism. Measurements in the linear interaction region close to the edge from which the shear layer is shed are examined. Two sets of experiments (Houston 1981 and Berlin 1983/84) are discussed. The measurements were carried out with shear layers in air using hot wire anemometers and microphones. The agreement between these measurements and the theory is good. Even details of the fluctuating flow field correspond to theoretical predictions, such as the local occurrence of negative phase speeds.

  5. Iosipescu shear properties of graphite fabric/epoxy composite laminates

    NASA Technical Reports Server (NTRS)

    Walrath, D. E.; Adams, D. F.

    1985-01-01

    The Iosipescu shear test method is used to measure the in-plane and interlaminar shear properties of four T300 graphite fabric/934 epoxy composite materials. Different weave geometries tested include an Oxford weave, a 5-harness satin weave, an 8-harness satin weave, and a plain weave with auxiliary warp yarns. Both orthogonal and quasi-isotropic layup laminates were tested. In-plane and interlaminar shear properties are obtained for laminates of all four fabric types. Overall, little difference in shear properties attributable to the fabric weave pattern is observed. The auxiliary warp material is significantly weaker and less stiff in interlaminar shear parallel to its fill direction. A conventional strain gage extensometer is modified to measure shear strains for use with the Iosipescu shear test. While preliminary results are encouraging, several design iterations failed to produce a reliable shear transducer prototype. Strain gages are still the most reliable shear strain transducers for use with this test method.

  6. Modeling Shear-Enhanced Permeability as the Mechanism for Fluid Flow in Fractured Reservoirs - A Promising Improvement to Predicting Reservoir Production

    NASA Astrophysics Data System (ADS)

    Barton, C.; Moos, D.

    2011-12-01

    An accurate geomechanical reservoir model including constraints on stress magnitudes and orientations, mechanical rock properties, and the orientations and characteristics of natural fractures is essential to understanding reservoir response to stimulation and production in low permeability reservoirs such as crystalline basement geothermal or oil and gas reservoirs. In these low permeability reservoirs, stimulation response is controlled largely by the properties of natural and induced fracture networks which are in turn controlled by the in situ stresses, the fracture distribution and the hydraulic behavior of the fractures. These hydraulic properties of the fractures, their width, stiffness and strength are often difficult to quantify, leading to large uncertainties in predicted response to stimulation of fractured reservoirs. A well-constrained and calibrated fracture model makes it possible not only to predict reservoir response to stimulation, including the shape and orientation of the stimulated region, but also to predict the required stimulation pressure. Such a model also makes it possible to predict the change in flow properties during production due to depletion, resulting in better predictions of production rate and ultimate recovery. As part of the evaluation process of a compartmentalized fractured basement reservoir, wellbore image and other data were used to develop a 3D geomechanical model of stress and natural fractures through the reservoir volume. Although the results clearly defined the optimal directions in which to drill wells to exploit pre-existing natural fractures, large uncertainties in the models resulted in significant uncertainties in predictions of stimulation response. Because the pre-existing natural fractures were insufficiently permeable and operational constraints precluded the use of hydraulic fracturing to stimulate the reservoir, an innovative approach was taken to determine the extent to which injection at pressures below

  7. An approximate solution to improve computational efficiency of impedance-type payload load prediction

    NASA Technical Reports Server (NTRS)

    White, C. W.

    1981-01-01

    The computational efficiency of the impedance type loads prediction method was studied. Three goals were addressed: devise a method to make the impedance method operate more efficiently in the computer; assess the accuracy and convenience of the method for determining the effect of design changes; and investigate the use of the method to identify design changes for reduction of payload loads. The method is suitable for calculation of dynamic response in either the frequency or time domain. It is concluded that: the choice of an orthogonal coordinate system will allow the impedance method to operate more efficiently in the computer; the approximate mode impedance technique is adequate for determining the effect of design changes, and is applicable for both statically determinate and statically indeterminate payload attachments; and beneficial design changes to reduce payload loads can be identified by the combined application of impedance techniques and energy distribution review techniques.

  8. Prediction of Giant Thermoelectric Power Factor in Type-VIII Clathrate Si46

    NASA Astrophysics Data System (ADS)

    Norouzzadeh, Payam; Myles, Charles W.; Vashaee, Daryoosh

    2014-11-01

    Clathrate materials have been the subject of intense interest and research for thermoelectric application. Nevertheless, from the very large number of conceivable clathrate structures, only a small fraction of them have been examined. Since the thermal conductivity of clathrates is inherently small due to their large unit cell size and open-framework structure, the current research on clathrates is focused on finding the ones with large thermoelectric power factor. Here we predict an extraordinarily large power factor for type-VIII clathrate Si46. We show the existence of a large density of closely packed elongated ellipsoidal carrier pockets near the band edges of this so far hypothetical material structure, which is higher than that of the best thermoelectric materials known today. The high crystallographic symmetry near the energy band edges for Si46-VIII clathrates is responsible for the formation of such a large number of carrier pockets.

  9. Prediction of giant thermoelectric power factor in type-VIII clathrate Si46.

    PubMed

    Norouzzadeh, Payam; Myles, Charles W; Vashaee, Daryoosh

    2014-01-01

    Clathrate materials have been the subject of intense interest and research for thermoelectric application. Nevertheless, from the very large number of conceivable clathrate structures, only a small fraction of them have been examined. Since the thermal conductivity of clathrates is inherently small due to their large unit cell size and open-framework structure, the current research on clathrates is focused on finding the ones with large thermoelectric power factor. Here we predict an extraordinarily large power factor for type-VIII clathrate Si(46). We show the existence of a large density of closely packed elongated ellipsoidal carrier pockets near the band edges of this so far hypothetical material structure, which is higher than that of the best thermoelectric materials known today. The high crystallographic symmetry near the energy band edges for Si(46)-VIII clathrates is responsible for the formation of such a large number of carrier pockets. PMID:25391971

  10. Theoretical prediction of the damping of a railway wheel with sandwich-type dampers

    NASA Astrophysics Data System (ADS)

    Merideno, Inaki; Nieto, Javier; Gil-Negrete, Nere; Giménez Ortiz, José Germán; Landaberea, Aitor; Iartza, Jon

    2014-09-01

    This paper presents a procedure for predicting the damping added to a railway wheel when sandwich-type dampers are installed. Although there are different ways to reduce the noise generated by a railway wheel, most devices are based on the mechanism of increasing wheel damping. This is why modal damping ratios are a clear indicator of the efficiency of the damping device and essential when a vibro-acoustic study of a railway wheel is carried out. Based on a number of output variables extracted from the wheel and damper models, the strategy explained herein provides the final damping ratios of the damped wheel. Several different configurations are designed and experimentally tested. Theoretical and experimental results agree adequately, and it is demonstrated that this procedure is a good tool for qualitative comparison between different solutions in the design stages.

  11. Earthquake prediction

    NASA Technical Reports Server (NTRS)

    Turcotte, Donald L.

    1991-01-01

    The state of the art in earthquake prediction is discussed. Short-term prediction based on seismic precursors, changes in the ratio of compressional velocity to shear velocity, tilt and strain precursors, electromagnetic precursors, hydrologic phenomena, chemical monitors, and animal behavior is examined. Seismic hazard assessment is addressed, and the applications of dynamical systems to earthquake prediction are discussed.

  12. Factors Motivating Individuals to Consider Genetic Testing for Type 2 Diabetes Risk Prediction.

    PubMed

    Wessel, Jennifer; Gupta, Jyoti; de Groot, Mary

    2016-01-01

    The purpose of this study was to identify attitudes and perceptions of willingness to participate in genetic testing for type 2 diabetes (T2D) risk prediction in the general population. Adults (n = 598) were surveyed on attitudes about utilizing genetic testing to predict future risk of T2D. Participants were recruited from public libraries (53%), online registry (37%) and a safety net hospital emergency department (10%). Respondents were 37 ± 11 years old, primarily White (54%), female (69%), college educated (46%), with an annual income ≥$25,000 (56%). Half of participants were interested in genetic testing for T2D (52%) and 81% agreed/strongly agreed genetic testing should be available to the public. Only 57% of individuals knew T2D is preventable. A multivariate model to predict interest in genetic testing was adjusted for age, gender, recruitment location and BMI; significant predictors were motivation (high perceived personal risk of T2D [OR = 4.38 (1.76, 10.9)]; family history [OR = 2.56 (1.46, 4.48)]; desire to know risk prior to disease onset [OR = 3.25 (1.94, 5.42)]; and knowing T2D is preventable [OR = 2.11 (1.24, 3.60)], intention (if the cost is free [OR = 10.2 (4.27, 24.6)]; and learning T2D is preventable [OR = 5.18 (1.95, 13.7)]) and trust of genetic testing results [OR = 0.03 (0.003, 0.30)]. Individuals are interested in genetic testing for T2D risk which offers unique information that is personalized. Financial accessibility, validity of the test and availability of diabetes prevention programs were identified as predictors of interest in T2D testing. PMID:26789839

  13. A Predictive Metabolic Signature for the Transition From Gestational Diabetes Mellitus to Type 2 Diabetes.

    PubMed

    Allalou, Amina; Nalla, Amarnadh; Prentice, Kacey J; Liu, Ying; Zhang, Ming; Dai, Feihan F; Ning, Xian; Osborne, Lucy R; Cox, Brian J; Gunderson, Erica P; Wheeler, Michael B

    2016-09-01

    Gestational diabetes mellitus (GDM) affects 3-14% of pregnancies, with 20-50% of these women progressing to type 2 diabetes (T2D) within 5 years. This study sought to develop a metabolomics signature to predict the transition from GDM to T2D. A prospective cohort of 1,035 women with GDM pregnancy were enrolled at 6-9 weeks postpartum (baseline) and were screened for T2D annually for 2 years. Of 1,010 women without T2D at baseline, 113 progressed to T2D within 2 years. T2D developed in another 17 women between 2 and 4 years. A nested case-control design used 122 incident case patients matched to non-case patients by age, prepregnancy BMI, and race/ethnicity. We conducted metabolomics with baseline fasting plasma and identified 21 metabolites that significantly differed by incident T2D status. Machine learning optimization resulted in a decision tree modeling that predicted T2D incidence with a discriminative power of 83.0% in the training set and 76.9% in an independent testing set, which is far superior to measuring fasting plasma glucose levels alone. The American Diabetes Association recommends T2D screening in the early postpartum period via oral glucose tolerance testing after GDM, which is a time-consuming and inconvenient procedure. Our metabolomics signature predicted T2D incidence from a single fasting blood sample. This study represents the first metabolomics study of the transition from GDM to T2D validated in an independent testing set, facilitating early interventions. PMID:27338739

  14. Factors Motivating Individuals to Consider Genetic Testing for Type 2 Diabetes Risk Prediction

    PubMed Central

    Wessel, Jennifer; Gupta, Jyoti; de Groot, Mary

    2016-01-01

    The purpose of this study was to identify attitudes and perceptions of willingness to participate in genetic testing for type 2 diabetes (T2D) risk prediction in the general population. Adults (n = 598) were surveyed on attitudes about utilizing genetic testing to predict future risk of T2D. Participants were recruited from public libraries (53%), online registry (37%) and a safety net hospital emergency department (10%). Respondents were 37±11 years old, primarily White (54%), female (69%), college educated (46%), with an annual income ≥$25,000 (56%). Half of participants were interested in genetic testing for T2D (52%) and 81% agreed/strongly agreed genetic testing should be available to the public. Only 57% of individuals knew T2D is preventable. A multivariate model to predict interest in genetic testing was adjusted for age, gender, recruitment location and BMI; significant predictors were motivation (high perceived personal risk of T2D [OR = 4.38 (1.76, 10.9)]; family history [OR = 2.56 (1.46, 4.48)]; desire to know risk prior to disease onset [OR = 3.25 (1.94, 5.42)]; and knowing T2D is preventable [OR = 2.11 (1.24, 3.60)], intention (if the cost is free [OR = 10.2 (4.27, 24.6)]; and learning T2D is preventable [OR = 5.18 (1.95, 13.7)]) and trust of genetic testing results [OR = 0.03 (0.003, 0.30)]. Individuals are interested in genetic testing for T2D risk which offers unique information that is personalized. Financial accessibility, validity of the test and availability of diabetes prevention programs were identified as predictors of interest in T2D testing. PMID:26789839

  15. B-Type Natriuretic Peptide Levels Predict Ventricular Arrhythmia Post Left Ventricular Assist Device Implantation.

    PubMed

    Hellman, Yaron; Malik, Adnan S; Lin, Hongbo; Shen, Changyu; Wang, I-Wen; Wozniak, Thomas C; Hashmi, Zubair A; Pickrell, Jeanette; Jani, Milena; Caccamo, Marco A; Gradus-Pizlo, Irmina; Hadi, Azam

    2015-12-01

    B-type natriuretic peptide (BNP) levels have been shown to predict ventricular arrhythmia (VA) and sudden death in patients with heart failure. We sought to determine whether BNP levels before left ventricular assist device (LVAD) implantation can predict VA post LVAD implantation in advanced heart failure patients. We conducted a retrospective study consisting of patients who underwent LVAD implantation in our institution during the period of May 2009-March 2013. The study was limited to patients receiving a HeartMate II or HeartWare LVAD. Acute myocardial infarction patients were excluded. We compared between the patients who developed VA within 15 days post LVAD implantation to the patients without VA. A total of 85 patients underwent LVAD implantation during the study period. Eleven patients were excluded (five acute MI, four without BNP measurements, and two discharged earlier than 13 days post LVAD implantation). The incidence of VA was 31%, with 91% ventricular tachycardia (VT) and 9% ventricular fibrillation. BNP remained the single most powerful predictor of VA even after adjustment for other borderline significant factors in a multivariate logistic regression model (P < 0.05). BNP levels are a strong predictor of VA post LVAD implantation, surpassing previously described risk factors such as age and VT in the past. PMID:25864448

  16. Predicting Disease-Related Subnetworks for Type 1 Diabetes Using a New Network Activity Score

    PubMed Central

    Gao, Shouguo; Jia, Shuang; Hessner, Martin J.

    2012-01-01

    Abstract In this study we investigated the advantage of including network information in prioritizing disease genes of type 1 diabetes (T1D). First, a naïve Bayesian network (NBN) model was developed to integrate information from multiple data sources and to define a T1D-involvement probability score (PS) for each individual gene. The algorithm was validated using known functional candidate genes as a benchmark. Genes with higher PS were found to be more likely to appear in T1D-related publications. Next a new network activity metric was proposed to evaluate the T1D relevance of protein-protein interaction (PPI) subnetworks. The metric considered the contribution both from individual genes and from network topological characteristics. The predictions were confirmed by several independent datasets, including a genome wide association study (GWAS), and two large-scale human gene expression studies. We found that novel candidate genes in the T1D subnetworks showed more significant associations with T1D than genes predicted using PS alone. Interestingly, most novel candidates were not encoded within the human leukocyte antigen (HLA) region, and their expression levels showed correlation with disease only in cohorts with low-risk HLA genotypes. The results suggested the importance of mapping disease gene networks in dissecting the genetics of complex diseases, and offered a general approach to network-based disease gene prioritization from multiple data sources. PMID:22917479

  17. Computational and Experimental Prediction of Human C-Type Lectin Receptor Druggability

    PubMed Central

    Aretz, Jonas; Wamhoff, Eike-Christian; Hanske, Jonas; Heymann, Dario; Rademacher, Christoph

    2014-01-01

    Mammalian C-type lectin receptors (CTLRS) are involved in many aspects of immune cell regulation such as pathogen recognition, clearance of apoptotic bodies, and lymphocyte homing. Despite a great interest in modulating CTLR recognition of carbohydrates, the number of specific molecular probes is limited. To this end, we predicted the druggability of a panel of 22 CTLRs using DoGSiteScorer. The computed druggability scores of most structures were low, characterizing this family as either challenging or even undruggable. To further explore these findings, we employed a fluorine-based nuclear magnetic resonance screening of fragment mixtures against DC-SIGN, a receptor of pharmacological interest. To our surprise, we found many fragment hits associated with the carbohydrate recognition site (hit rate = 13.5%). A surface plasmon resonance-based follow-up assay confirmed 18 of these fragments (47%) and equilibrium dissociation constants were determined. Encouraged by these findings we expanded our experimental druggability prediction to Langerin and MCL and found medium to high hit rates as well, being 15.7 and 10.0%, respectively. Our results highlight limitations of current in silico approaches to druggability assessment, in particular, with regard to carbohydrate-binding proteins. In sum, our data indicate that small molecule ligands for a larger panel of CTLRs can be developed. PMID:25071783

  18. Established and emerging biomarkers for the prediction of type 1 diabetes: a systematic review

    PubMed Central

    WATKINS, RENECIA A.; EVANS-MOLINA, CARMELLA; BLUM, JANICE S.; DIMEGLIO, LINDA A.

    2015-01-01

    Type 1 diabetes (T1D) is an autoimmune disease with a prolonged and variable latent period that culminates in the destruction of pancreatic β-cells and the development of hyperglycemia. There is a need for diagnostic biomarkers to detect more accurately detect individuals with prediabetes to expedite targeting for prevention and intervention strategies. To assess the current ability to predict the insidious development of T1D, we conducted a comprehensive systematic review for established and prospective predictive markers of T1D using the Medline, OVID, and EMBASE databases. Resulting citations were screened for relevance to subject. Our research generated five major categories of markers that are either currently used or forthcoming: genetic, autoantibodies, risk score quantification, cellular immunity, and β-cell function. The current standard used to assess T1D onset or predisposition focuses on autoimmune pathology and disease-associated autoantibodies. Research studies in general go beyond autoantibody screening and assess genetic predisposition, and quantitate risk of developing disease based on additional factors. However, there are few currently used techniques that assess the root of T1D: β-cell destruction. Thus, novel techniques are discussed with the potential to gauge degrees of β-cell stress and failure via protein, RNA, and DNA analyses. PMID:24662515

  19. Prediction of moisture content of natural gases using simple Arrhenius-type function

    NASA Astrophysics Data System (ADS)

    Bahadori, Alireza

    2011-03-01

    Natural gas extracted from underground reservoirs is saturated with water. The accurate prediction of moisture content in natural gas is extremely important. The presence of water vapor can lead to potentially disastrous consequences. The lifetime of a pipeline is governed by the rate at which corrosion occurs, which is directly linked to the available moisture in the gas resulting in oxidation. In addition, the formation of hydrates due to presence of water in natural gas can lead to safety hazards to production/transportation systems and to substantial economic risks. In this paper, an attempt has been made to develop an easy-to-use Arrhenius-type asymptotic exponential function combined with the Vandermonde matrix to arrive at an appropriate estimation of saturated water content of sour natural gases for pressures up to 69000 kPa and the temperature range between 20 to 180°C. Percent average absolute deviation of the proposed method is found to be around 2%, demonstrating the excellent performance of the developed predictive tool. The tool will be of great practical value for chemical and petroleum engineers to have a quick check on the water content of sour natural gases at various temperatures and pressures without performing any experimental measurements.

  20. Dynamic pore-pressure fluctuations in rapidly shearing granular materials

    USGS Publications Warehouse

    Iverson, R.M.; LaHusen, R.G.

    1989-01-01

    Results from two types of experiments show that intergranular pore pressures fluctuated dynamically during rapid, steady shear deformation of water-saturated granular materials. During some fluctuations, the pore water locally supported all normal and shear stresses, while grain-contact stresses transiently fell to zero. Fluctuations also propagated outward from the shear zone; this process modifies grain-contact stresses in adjacent areas and potentially instigates shear-zone growth.

  1. Modeling of shear localization in materials

    SciTech Connect

    Lesuer, D.; LeBlanc, M.; Riddle, B.; Jorgensen, B.

    1998-02-11

    The deformation response of a Ti alloy, Ti-6Al-4V, has been studied during shear localization. The study has involved well-controlled laboratory tests involving a double-notch shear sample. The results have been used to provide a comparison between experiment and the predicted response using DYNA2D and two material models (the Johnson-Cook model and an isotropic elastic-plastic-hydrodynamic model). The work will serve as the basis for the development of a new material model which represents the different deformation mechanisms active during shear localization.

  2. Periodic Viscous Shear Heating Instability in Fine-Grained Shear Zones: Mechanism for Intermediate Depth Earthquakes

    NASA Astrophysics Data System (ADS)

    Coon, E.; Kelemen, P.; Hirth, G.; Spiegelman, M.

    2005-12-01

    initial T of 600 to 850 C, this produced periodic viscous shear heating events with periods of 100's to 1000's of years. Strain rates during these events approach 1 per second as temperatures reach 1400. Cooling between events returns the shear zone almost to its initial temperature, though ultimately shear zone temperature between events exceeds 850 C resulting in stable viscous creep. Analysis shows that our system of equations jumps from one steady state to another, depending on a non-dimensional number relating the rate of shear heating to the rate of diffusive cooling. This year, Kelemen and Hirth show that the rate of stress drop during shear heating events is greater than the rate of elastic stress relaxation, so that shear heating events are a runaway instability. Rather than capping the temperature at 1400 C, we parameterize melt fraction as a function of T, and shear viscosity as a function of melt fraction. A problem with our 1D model is that predicted displacements are too large (1 to 20 m) during shear heating events, essentially because there is no resistance at shear zone ends. To address this, Coon and Spiegelman have embarked on a 3D model, incorporating a pre-existing fine-grained, tabular shear zone of finite extent, with a visco-elastic rheology for both shear zone and wall rocks. Preliminary 1D models using this approach show that the more complicated rheology yields the same result as the simpler model. We will present preliminary results, and determine the Maxwell time for this problem, since low strain rates could produce viscous relaxation in both shear zone and wall rocks with negligible shear heating.

  3. Prediction of protective sensory loss, neuropathy and foot ulceration in type 2 diabetes

    PubMed Central

    Paisey, R B; Darby, T; George, A M; Waterson, M; Hewson, P; Paisey, C F; Thomson, M P

    2016-01-01

    Objectives To prospectively determine clinical and biochemical characteristics associated with the development of peripheral neuropathy, loss of protective sensation, and foot ulceration in persons with type 2 diabetes mellitus (DM) over 7 years. Research design and methods Graded monofilament (MF) testing, vibration perception threshold, and neuropathy symptom questionnaires were undertaken in 206 participants with type 2 DM without peripheral vascular disease or history of foot ulceration and 71 healthy participants without DM at baseline and after 7 years. 6 monthly glycosylated hemoglobin (HbA1c) levels and annual serum lipid profiles were measured during follow-up of those with DM. Incident foot ulceration was recorded at follow-up. Results Taller stature and higher quartiles of serum triglyceride and HbA1c levels were associated with neuropathy at follow-up (p=0.008). Remission of baseline neuropathy was observed in 7 participants at follow-up. 9 participants with type 2 DM developed foot ulcers by the end of the study, only 1 at low risk. Mean HbA1c levels were higher in those who developed foot ulceration (p<0.0001). 1 participant with neuropathy throughout developed a Charcot foot. Failure to perceive 2 or more 2, 4 and 6 g MF stimuli at baseline predicted loss of protective sensation at follow-up. Conclusions Tall stature and worse metabolic control were associated with progression to neuropathy. Mean HbA1c levels were higher in those who developed foot ulcers. Graded MF testing may enrich recruitment to clinical trials and assignation of high risk for foot ulceration. PMID:27239314

  4. Simple shear of deformable square objects

    NASA Astrophysics Data System (ADS)

    Treagus, Susan H.; Lan, Labao

    2003-12-01

    Finite element models of square objects in a contrasting matrix in simple shear show that the objects deform to a variety of shapes. For a range of viscosity contrasts, we catalogue the changing shapes and orientations of objects in progressive simple shear. At moderate simple shear ( γ=1.5), the shapes are virtually indistinguishable from those in equivalent pure shear models with the same bulk strain ( RS=4), examined in a previous study. In theory, differences would be expected, especially for very stiff objects or at very large strain. In all our simple shear models, relatively competent square objects become asymmetric barrel shapes with concave shortened edges, similar to some types of boudin. Incompetent objects develop shapes surprisingly similar to mica fish described in mylonites.

  5. The inward bulge type buckling of monocoque cylinders I : calculation of the effect upon the buckling stress of a compressive force, a nonlinear direct stress distribution, and a shear force

    NASA Technical Reports Server (NTRS)

    Hoff, N J; Klein, Bertram

    1944-01-01

    In the present part I of a series of reports on the inward bulge type buckling of monocoque cylinders the buckling load in combined bending and compression is first derived. Next the reduction in the buckling load because of a nonlinear direct stress distribution is determined. In experiments nonlinearity may result from an inadequate stiffness of the end attachments in actual airplanes from the existence of concentrated loads or cut-outs. The effect of a shearing force upon the critical load is investigated through an analysis of the results of tests carried out at GALCIT with 55 reinforced monocoque cylinders. Finally, a simple criterion of general instability is presented in the form of a buckling inequality which should be helpful to the designer of a monocoque in determining the sizes of the rings required for excluding the possibility of inward bulge type buckling.

  6. Shearing stability of lubricants

    NASA Technical Reports Server (NTRS)

    Shiba, Y.; Gijyutsu, G.

    1984-01-01

    Shearing stabilities of lubricating oils containing a high mol. wt. polymer as a viscosity index improver were studied by use of ultrasound. The oils were degraded by cavitation and the degradation generally followed first order kinetics with the rate of degradation increasing with the intensity of the ultrasonic irradiation and the cumulative energy applied. The shear stability was mainly affected by the mol. wt. of the polymer additive and could be determined in a short time by mechanical shearing with ultrasound.

  7. Intelligent approaches for prediction of compressional, shear and Stoneley wave velocities from conventional well log data: A case study from the Sarvak carbonate reservoir in the Abadan Plain (Southwestern Iran)

    NASA Astrophysics Data System (ADS)

    Rajabi, Mojtaba; Bohloli, Bahman; Gholampour Ahangar, Esmaeil

    2010-05-01

    Compressional, shear and Stoneley wave velocities ( Vp, Vs and Vst, respectively) are important reservoir characteristics that have many applications in petrophysical, geophysical and geomechanical studies. In this study Vp, Vs and Vst were predicted from well log data using genetic algorithms, fuzzy logic and neuro-fuzzy techniques in an Iranian carbonate reservoir (Sarvak Formation). A total of 3030 data points from the Sarvak carbonate reservoir which have Vp, Vs, Vst and conventional well log data were used. These data were divided into two groups; one group included 2047 data points used for constructing intelligent models, and the other included 983 data points used for models testing. The measured mean squared errors (MSEs) of predicted Vp in the test data, using genetic algorithms, fuzzy logic and neuro-fuzzy techniques, were 0.0296, 0.0148 and 0.029, respectively, for Vs these errors were 0.0153, 0.0084 and 0.0184, respectively, and for Vst they were 0.00035, 0.00020 and 0.00062, respectively. Despite different concepts in these intelligent techniques, the results (especially those from fuzzy logic) seem to be reliable.

  8. Postprandial Hypertriglyceridemia Predicts Development of Insulin Resistance Glucose Intolerance and Type 2 Diabetes

    PubMed Central

    Aslam, Mohammad; Aggarwal, Sarla; Sharma, Krishna Kumar; Galav, Vikas; Madhu, Sri Venkata

    2016-01-01

    Insulin resistance (IR) and type 2 diabetes mellitus (T2DM) have been found to be associated with postprandial hypertriglyceridemia (PPHTg). However, whether PPHTg can cause IR and diabetes is not clear. We therefore investigated the role of PPHTg in development of T2DM in rat model of T2DM. 96 male Wistar rats were randomized into four groups (24 rats each). Control Group A, high sucrose diet (HSD) Group B, HSD+Pioglitazone (10mg/kg/day) Group C and HSD+Atorvastatin (20mg/kg/day) Group D. Fat and glucose tolerance tests were done at regular intervals in all groups besides insulin and body weight measurement. At 26 weeks, low dose streptozotocin (15mg/kg,i.p.) was given to half of the rats. All rats were followed up till 48 weeks. PPHTg developed as early as week 2 in Group B and stabilized by week 14. Group B displayed highest PPHTg compared to other groups. Atorvastatin treatment (Group D) abolished PPHTg which became comparable to controls, pioglitazone treatment partially blunted PPHTg resulting in intermediate PPHTg. Group B with highest PPHTg showed highest subsequent IR, glucose intolerance (GI) and highest incidence of prediabetes at week 26 and diabetes at week 34 and 46 compared to other groups. Group D rats displayed lower IR, GI, low incidence of prediabetes and diabetes at these time points compared to Groups B and C. ROC analysis showed that triglyceride area under the curve of each time point significantly predicts the risk of diabetes. Present study provides the evidence that PPHTg predicts the development of IR, GI and T2DM in rat model of diet induced T2DM. PMID:26808523

  9. Postprandial Hypertriglyceridemia Predicts Development of Insulin Resistance Glucose Intolerance and Type 2 Diabetes.

    PubMed

    Aslam, Mohammad; Aggarwal, Sarla; Sharma, Krishna Kumar; Galav, Vikas; Madhu, Sri Venkata

    2016-01-01

    Insulin resistance (IR) and type 2 diabetes mellitus (T2DM) have been found to be associated with postprandial hypertriglyceridemia (PPHTg). However, whether PPHTg can cause IR and diabetes is not clear. We therefore investigated the role of PPHTg in development of T2DM in rat model of T2DM. 96 male Wistar rats were randomized into four groups (24 rats each). Control Group A, high sucrose diet (HSD) Group B, HSD+Pioglitazone (10 mg/kg/day) Group C and HSD+Atorvastatin (20 mg/kg/day) Group D. Fat and glucose tolerance tests were done at regular intervals in all groups besides insulin and body weight measurement. At 26 weeks, low dose streptozotocin (15 mg/kg, i.p.) was given to half of the rats. All rats were followed up till 48 weeks. PPHTg developed as early as week 2 in Group B and stabilized by week 14. Group B displayed highest PPHTg compared to other groups. Atorvastatin treatment (Group D) abolished PPHTg which became comparable to controls, pioglitazone treatment partially blunted PPHTg resulting in intermediate PPHTg. Group B with highest PPHTg showed highest subsequent IR, glucose intolerance (GI) and highest incidence of prediabetes at week 26 and diabetes at week 34 and 46 compared to other groups. Group D rats displayed lower IR, GI, low incidence of prediabetes and diabetes at these time points compared to Groups B and C. ROC analysis showed that triglyceride area under the curve of each time point significantly predicts the risk of diabetes. Present study provides the evidence that PPHTg predicts the development of IR, GI and T2DM in rat model of diet induced T2DM. PMID:26808523

  10. Health-risk behaviors among a sample of US pre- adolescents: Types, frequency, and predictive factors

    PubMed Central

    Riesch, Susan K.; Kedrowski, Karen; Brown, Roger L.; Temkin, Barbara Myers; Wang, Kevin; Henriques, Jeffrey; Jacobson, Gloria; Giustino-Kluba, Nina

    2012-01-01

    Background Children as young as 10 years old report curiosity and participation in health-risk behaviors, yet most studies focus upon adolescent samples. Objective To document the types and frequencies of health risk behavior among pre-adolescents and to examine the child, family, and environment factors that predict them. Method A sample of 297 pre-adolescents (mean age = 10.5, SD = 0.6) from two Midwestern US cities and their parents (child-parent dyads) provided data about demographic characteristics, health risk behavior participation, child self-esteem, child pubertal development, child and adult perception of their neighborhood, and parent monitoring. Their participation was at intake to a 5-year clustered randomized controlled trial. Results Pre-adolescents participated in an average of 3.7 health-risk behaviors (SD = 2.0), primarily those that lead to unintentional (helmet and seatbelt use) and intentional (feeling unsafe, having something stolen, and physical fighting) injury. Factors predictive of unintentional injury risk behavior were self-esteem, pubertal development, parent monitoring, and parent perception of the neighborhood environment. Boys were 1.8 times less likely than girls to use helmets and seatbelts. Pre-adolescents whose parents were not partnered were 2.8 times more likely than pre-adolescents whose parents were partnered to report intentional risk behavior. Recommendations These data demonstrate trends that cannot be ignored. We recommend, focused specifically upon boys and non-partnered families, that (a) developmentally-appropriate, appealing prevention messages be developed and delivered for parents and pre-adolescents and community interventions targeting both parent and pre-adolescent together be provided to help them establish and monitor behavioral expectations and (b) organized nursing endorse policy in the US and globally that assures adequate family environments for children. PMID:23177901

  11. TURBULENT SHEAR ACCELERATION

    SciTech Connect

    Ohira, Yutaka

    2013-04-10

    We consider particle acceleration by large-scale incompressible turbulence with a length scale larger than the particle mean free path. We derive an ensemble-averaged transport equation of energetic charged particles from an extended transport equation that contains the shear acceleration. The ensemble-averaged transport equation describes particle acceleration by incompressible turbulence (turbulent shear acceleration). We find that for Kolmogorov turbulence, the turbulent shear acceleration becomes important on small scales. Moreover, using Monte Carlo simulations, we confirm that the ensemble-averaged transport equation describes the turbulent shear acceleration.

  12. Nonlinear forcing singular vector -type tendency errors of the Zebiak-Cane model and its effect on ENSO predictability

    NASA Astrophysics Data System (ADS)

    Duan, Wansuo; Zhao, Peng

    2014-05-01

    Within the framework of the Zebiak-Cane model, the nonlinear forcing singular vector (NFSV) approach is used to explore the constant tendency error that has the largest effect on prediction uncertainties for El Niño events. The results showed only one NFSV to exist for each of the predictions for the predetermined model El Niño events. It was found that the NFSVs often present large-scale zonal dipolar structures and are insensitive to the intensities of El Niño events, but are dependent on the prediction period. In particular, the NFSVs associated with the predictions crossing through the growth phase of El Niño tend to exhibit a zonal dipolar pattern with positive anomalies in the equatorial central-western Pacific and negative anomalies in the equatorial eastern Pacific (denoted as "type-1 NFSVs"). Meanwhile, those associated with the predictions through the decaying phase of El Niño are inclined to present another zonal dipolar pattern (denoted as "type-2 NFSVs"), which is almost opposite to the type-1 NFSVs. The FSVs, i.e. the linear counterpart of the NFSVs, can also be classified into two types, which are of almost the same signs as in type-1 NFSVs and type-2 NFSVs, and which we similarly denoted as "type-1 FSVs" and "type-2 FSVs", respectively. We found that both type-1 FSVs and type-1 NFSVs often cause negative prediction errors for Niño-3 SSTA of the El Niño events, while the type-2 FSVs and type-2 NFSVs usually yield positive prediction errors. However, due to the effect of nonlinearities, the NFSVs usually have the western pole of the zonal dipolar pattern much farther west, and covering much broader region. Correspondingly, the NFSVs cause much larger prediction errors than the FSVs and show themselves to be much more applicable in describing the optimal tendency errors in the nonlinear Zebiak-Cane model. Our results also show that the nonlinearities have a suppression effect on the growth of the prediction errors caused by the FSVs. Furthermore

  13. Effects of shearing, forage type and feed value, concentrate feed level, and protein concentration on the performance of housed finishing lambs.

    PubMed

    Keady, T W J; Hanrahan, J P

    2015-01-01

    The effects of high and medium feed value grass silage or maize silage (MS), each offered with a range of concentrate feed levels, and ad libitum concentrate on the performance of finishing lambs, which were either shorn or unshorn, were evaluated. Three silages were used: 1 medium feed value (MFV) and 1 high feed value (HFV) grass silage (DM digestibility [DMD] of 71.3% and 74.5%, respectively) and 1 MS (DM and starch concentrations of 30.9% and 35.3% DM, respectively). The 3 silages were offered ad libitum with daily allowances of 0.4, 0.8, or 1.2 kg concentrate per lamb. Two additional treatments were: 1) MS supplemented with 0.4 kg of a low CP (LP) concentrate and 2) concentrate offered ad libitum with 0.5 kg/d of HFV grass silage. These 11 dietary treatments were offered to 264 crossbred Suffolk lambs (initial BW = 39.0 kg), half of which were unshorn and half of which were shorn, for a 54-d finishing period, resulting in 22 treatments. Shearing increased forage DMI (P < 0.001) but did not alter (P > 0.05) carcass weight, carcass gain, or ADG, and there was no interaction with dietary treatment. Reducing CP concentration of the concentrate offered with MS did not alter (P > 0.05) feed intake or lamb performance. Increasing concentrate feed level increased feed DMI and lamb performance (P < 0.001). The linear response in ADG to increased concentrate supplementation was greater (P = 0.012) for MFV than HFV grass silage, and a corresponding difference in carcass gain approached significance (P = 0.075). The linear response was greater for grass silage than for MS for ADG (P < 0.01) and carcass gain (P = 0.019). The response in lamb performance from increased concentrate supplementation was linear for HFV grass silage and MS but quadratic (P < 0.05) for the MFV grass silage, reflecting the large response for this silage when concentrate supplement was increased from 0.4 to 0.8 kg. Relative to the MFV grass silage supplemented with 0.8 kg concentrate, the potential

  14. Estimated insulin sensitivity predicts regression of albuminuria in Type 1 diabetes

    PubMed Central

    Bjornstad, P.; Maahs, D. M.; Johnson, R. J.; Rewers, M.; Snell-Bergeon, J. K.

    2014-01-01

    Aim To test the hypothesis that greater baseline insulin sensitivity would predict regression of albuminuria over 6 years in adults with Type 1 diabetes. Method We enrolled 81 people aged 30–48 years with albuminuria at baseline in the present study and re-examined them 6 years later. Urinary albumin excretion rate was measured and albuminuria was defined as urinary albumin excretion rate ≥20 µg/min. Regression of albuminuria was defined as normoalbuminuria (urinary albumin excretion rate <20µg/min) at follow-up. Predictors of regression of albuminuria were examined in stepwise logistic regression. The variables age, diabetes duration, sex, serum uric acid, HbA1c, systolic blood pressure, LDL cholesterol, HDL cholesterol, BMI, baseline albumin excretion rate, estimated insulin sensitivity at baseline, change in estimated insulin sensitivity from baseline to follow-up and angiotensinconverting enzyme inhibitor/angiotensin receptor blocker use were considered for inclusion in the model. Results Estimated insulin sensitivity was significantly higher at both baseline (4.6±1.2 vs 3.4±1.7; P=0.002) and follow-up (5.2±1.9 vs. 3.5±1.7; P<0.0001) in people who had regression of albuminuria vs those who did not. HbA1c (odds ratio 0.4, 95% CI 0.2–0.8; P=0.006), estimated insulin sensitivity (odds ratio 2.5, 95% CI 1.3–4.9; P=0.006) at baseline and change in estimated insulin sensitivity from baseline to follow-up (odds ratio 2.7, 95% CI 1.4–5.3; P=0.003) were independently associated with regression of albuminuria in a multivariable stepwise model. Conclusions In conclusion, over 6 years, higher baseline estimated insulin sensitivity and change in estimated insulin sensitivity independently predicted regression of albuminuria. Improving insulin sensitivity in people with Type 1 diabetes is a potential therapeutic target to increase rates of regression of albuminuria. PMID:25303233

  15. Steel shear walls, behavior, modeling and design

    SciTech Connect

    Astaneh-Asl, Abolhassan

    2008-07-08

    In recent years steel shear walls have become one of the more efficient lateral load resisting systems in tall buildings. The basic steel shear wall system consists of a steel plate welded to boundary steel columns and boundary steel beams. In some cases the boundary columns have been concrete-filled steel tubes. Seismic behavior of steel shear wall systems during actual earthquakes and based on laboratory cyclic tests indicates that the systems are quite ductile and can be designed in an economical way to have sufficient stiffness, strength, ductility and energy dissipation capacity to resist seismic effects of strong earthquakes. This paper, after summarizing the past research, presents the results of two tests of an innovative steel shear wall system where the boundary elements are concrete-filled tubes. Then, a review of currently available analytical models of steel shear walls is provided with a discussion of capabilities and limitations of each model. We have observed that the tension only 'strip model', forming the basis of the current AISC seismic design provisions for steel shear walls, is not capable of predicting the behavior of steel shear walls with length-to-thickness ratio less than about 600 which is the range most common in buildings. The main reasons for such shortcomings of the AISC seismic design provisions for steel shear walls is that it ignores the compression field in the shear walls, which can be significant in typical shear walls. The AISC method also is not capable of incorporating stresses in the shear wall due to overturning moments. A more rational seismic design procedure for design of shear walls proposed in 2000 by the author is summarized in the paper. The design method, based on procedures used for design of steel plate girders, takes into account both tension and compression stress fields and is applicable to all values of length-to-thickness ratios of steel shear walls. The method is also capable of including the effect of

  16. Soil respiration at mean annual temperature predicts annual total across vegetation types and biomes

    PubMed Central

    Bahn, M.; Reichstein, M.; Davidson, E. A.; Grünzweig, J.; Jung, M.; Carbone, M. S.; Epron, D.; Misson, L.; Nouvellon, Y.; Roupsard, O.; Savage, K.; Trumbore, S. E.; Gimeno, C.; Yuste, J. Curiel; Tang, J.; Vargas, R.; Janssens, I. A.

    2011-01-01

    Soil respiration (SR) constitutes the largest flux of CO2 from terrestrial ecosystems to the atmosphere. However, there still exist considerable uncertainties as to its actual magnitude, as well as its spatial and interannual variability. Based on a reanalysis and synthesis of 80 site-years for 57 forests, plantations, savannas, shrublands and grasslands from boreal to tropical climates we present evidence that total annual SR is closely related to SR at mean annual soil temperature (SRMAT), irrespective of the type of ecosystem and biome. This is theoretically expected for non water-limited ecosystems within most of the globally occurring range of annual temperature variability and sensitivity (Q10). We further show that for seasonally dry sites where annual precipitation (P) is lower than potential evapotranspiration (PET), annual SR can be predicted from wet season SRMAT corrected for a factor related to P/PET. Our finding indicates that it can be sufficient to measure SRMAT for obtaining a well constrained estimate of its annual total. This should substantially increase our capacity for assessing the spatial distribution of soil CO2 emissions across ecosystems, landscapes and regions, and thereby contribute to improving the spatial resolution of a major component of the global carbon cycle. PMID:23293656

  17. Prediction of the radiation situation during conditioned radioactive waste storage in hangar-type storage facilities

    NASA Astrophysics Data System (ADS)

    Rosnovskii, S. V.; Bulka, S. K.

    2014-02-01

    An original technology for the conditioning of solidified radioactive waste was developed by the Novovoronezh nuclear power plant (NPP) staff. The technology provides for waste placement inside NZK-150-1.5P containers with their further storage at light hangar-type storage facilities. A number of technical solutions were developed that allow for reducing the gamma-radiation dose rate from the package formed. A methodology for prediction of the radiation situation around hangars, depending on the radiation characteristics of irrecoverable shielding containers (ISCs) located in the peripheral row of a storage facility, was developed with the purpose of assuring safe storage. Based on empirical data, the field background gamma-radiation dose rate at an area as a function of the average dose rate at the hangar surface and the average dose rate close packages, placed in the peripheral row of the storage facility, was calculated. The application of the developed methodology made it possible to reduce by ten times the expenditures for the conditioning and holding of solidified radioactive waste (SRW) while unconditionally providing storage safety.

  18. Modeling transversely isotropic, viscoelastic, incompressible tissue-like materials with application in ultrasound shear wave elastography

    NASA Astrophysics Data System (ADS)

    Qiang, Bo; Brigham, John C.; Aristizabal, Sara; Greenleaf, James F.; Zhang, Xiaoming; Urban, Matthew W.

    2015-02-01

    In this paper, we propose a method to model the shear wave propagation in transversely isotropic, viscoelastic and incompressible media. The targeted application is ultrasound-based shear wave elastography for viscoelasticity measurements in anisotropic tissues such as the kidney and skeletal muscles. The proposed model predicts that if the viscoelastic parameters both across and along fiber directions can be characterized as a Voigt material, then the spatial phase velocity at any angle is also governed by a Voigt material model. Further, with the aid of Taylor expansions, it is shown that the spatial group velocity at any angle is close to a Voigt type for weakly attenuative materials within a certain bandwidth. The model is implemented in a finite element code by a time domain explicit integration scheme and shear wave simulations are conducted. The results of the simulations are analyzed to extract the shear wave elasticity and viscosity for both the spatial phase and group velocities. The estimated values match well with theoretical predictions. The proposed theory is further verified by an ex vivo tissue experiment measured in a porcine skeletal muscle by an ultrasound shear wave elastography method. The applicability of the Taylor expansion to analyze the spatial velocities is also discussed. We demonstrate that the approximations from the Taylor expansions are subject to errors when the viscosities across or along the fiber directions are large or the maximum frequency considered is beyond the bandwidth defined by radii of convergence of the Taylor expansions.

  19. Modeling Transversely Isotropic, Viscoelastic, Incompressible Tissue-like Materials with Application in Ultrasound Shear Wave Elastography

    PubMed Central

    Qiang, Bo; Brigham, John C.; Aristizabal, Sara; Greenleaf, James F.; Zhang, Xiaoming; Urban, Matthew W.

    2015-01-01

    In this paper, we propose a method to model the shear wave propagation in transversely isotropic, viscoelastic and incompressible media. The targeted application is ultrasound-based shear wave elastography for viscoelasticity measurements in anisotropic tissues such as the kidney and skeletal muscles. The proposed model predicts that if the viscoelastic parameters both across and along fiber directions can be characterized as a Voigt material, then the spatial phase velocity at any angle is also governed by a Voigt material model. Further, with the aid of Taylor expansions, it is shown that the spatial group velocity at any angle is close to a Voigt type for weakly attenuative materials within a certain bandwidth. The model is implemented in a finite element code by a time domain explicit integration scheme and shear wave simulations are conducted. The results of the simulations are analyzed to extract the shear wave elasticity and viscosity for both the spatial phase and group velocities. The estimated values match well with theoretical predictions. The proposed theory is further verified by an ex vivo tissue experiment measured in a porcine skeletal muscle by an ultrasound shear wave elastography method. The applicability of the Taylor expansion to analyze the spatial velocities is also discussed. We demonstrate that the approximations from the Taylor expansions are subject to errors when the viscosities across or along the fiber directions are large or the maximum frequency considered is beyond the bandwidth defined by radii of convergence of the Taylor expansions. PMID:25591921

  20. Third-moment closure of turbulence for predictions of separating and reattaching shear flows: A study of Reynolds-stress closure model

    NASA Technical Reports Server (NTRS)

    Amano, R. S.; Goel, P.

    1986-01-01

    A numerical study of computations in backward-facing steps with flow separation and reattachment, using the Reynolds stress closure is presented. The highlight of this study is the improvement of the Reynold-stress model (RSM) by modifying the diffusive transport of the Reynolds stresses through the formulation, solution and subsequent incorporation of the transport equations of the third moments, bar-u(i)u(j)u(k), into the turbulence model. The diffusive transport of the Reynolds stresses, represented by the gradients of the third moments, attains greater significance in recirculating flows. The third moments evaluated by the development and solution of the complete transport equations are superior to those obtained by existing algebraic correlations. A low-Reynolds number model for the transport equations of the third moments is developed and considerable improvement in the near-wall profiles of the third moments is observed. The values of the empirical constants utilized in the development of the model are recommended. The Reynolds-stress closure is consolidated by incorporating the equations of k and e, containing the modified diffusion coefficients, and the transport equations of the third moments into the Reynolds stress equations. Computational results obtained by the original k-e model, the original RSM and the consolidated and modified RSM are compared with experimental data. Overall improvement in the predictions is seen by consolidation of the RMS and a marked improvement in the profiles of bar-u(i)u(j)u(k) is obtained around the reattachment region.

  1. Method for shearing spent nuclear fuel assemblies

    DOEpatents

    Weil, Bradley S.; Watson, Clyde D.

    1977-01-01

    A method is disclosed for shearing spent nuclear fuel assemblies of the type wherein a plurality of long metal tubes packed with ceramic fuel are supported in a spaced apart relationship within an outer metal shell or shroud which provides structural support to the assembly. Spent nuclear fuel assemblies are first compacted in a stepwise manner between specially designed gag-compactors and then sheared into short segments amenable to chemical processing by shear blades contoured to mate with the compacted surface of the fuel assembly.

  2. Shear flexibility for structures

    NASA Technical Reports Server (NTRS)

    Stangeland, Maynard L. (Inventor)

    1976-01-01

    This device comprises a flexible sheet member having cross convolutions oriented 45.degree. to the shear vector with spherical reliefs at the convolution junctions. The spherical reliefs are essential to the shear flexibility by interrupting the principal stress lines that act along the ridges of the convolutions. The spherical reliefs provide convolutions in both directions in the plane of the cross-convolution ridges.

  3. Shear flexibility for structures

    NASA Technical Reports Server (NTRS)

    Stangeland, Maynard L. (Inventor)

    1977-01-01

    This device comprises a flexible sheet member having cross convolutions oriented 45.degree. to the shear vector with spherical reliefs at the convolution junctions. The spherical reliefs are essential to the shear flexibility by interrupting the principal stress lines that act along the ridges of the convolutions. The spherical reliefs provide convolutions in both directions in the plane of the cross-convolution ridges.

  4. T-type calcium channels promote predictive homeostasis of input-output relations in thalamocortical neurons of lateral geniculate nucleus

    PubMed Central

    Hong, Su Z.; Kim, Haram R.; Fiorillo, Christopher D.

    2014-01-01

    A general theory views the function of all neurons as prediction, and one component of this theory is that of “predictive homeostasis” or “prediction error.” It is well established that sensory systems adapt so that neuronal output maintains sensitivity to sensory input, in accord with information theory. Predictive homeostasis applies the same principle at the cellular level, where the challenge is to maintain membrane excitability at the optimal homeostatic level so that spike generation is maximally sensitive to small gradations in synaptic drive. Negative feedback is a hallmark of homeostatic mechanisms, as exemplified by depolarization-activated potassium channels. In contrast, T-type calcium channels exhibit positive feedback that appears at odds with the theory. In thalamocortical neurons of lateral geniculate nucleus (LGN), T-type channels are capable of causing bursts of spikes with an all-or-none character in response to excitation from a hyperpolarized potential. This “burst mode” would partially uncouple visual input from spike output and reduce the information spikes convey about gradations in visual input. However, past observations of T-type-driven bursts may have resulted from unnaturally high membrane excitability. Here we have mimicked within rat brain slices the patterns of synaptic conductance that occur naturally during vision. In support of the theory of predictive homeostasis, we found that T-type channels restored excitability toward its homeostatic level during periods of hyperpolarization. Thus, activation of T-type channels allowed two retinal input spikes to cause one output spike on average, and we observed almost no instances in which output count exceeded input count (a “burst”). T-type calcium channels therefore help to maintain a single optimal mode of transmission rather than creating a second mode. More fundamentally our results support the general theory, which seeks to predict the properties of a neuron's ion

  5. Determining Shear Stress Distribution in a Laminate

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.

    2010-01-01

    A "simplified shear solution" method approximates the through-thickness shear stress distribution within a composite laminate based on an extension of laminated beam theory. The method does not consider the solution of a particular boundary value problem; rather, it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply-level stresses can be efficiently determined from global load resultants at a given location in a structure and used to evaluate the margin of safety on a ply-by-ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. The method has been incorporated within the HyperSizer commercial structural sizing software to improve its predictive capability for designing composite structures. The HyperSizer structural sizing software is used extensively by NASA to design composite structures. In the case of through-thickness shear loading on panels, HyperSizer previously included a basic, industry-standard, method for approximating the resulting shear stress distribution in sandwich panels. However, no such method was employed for solid laminate panels. The purpose of the innovation is to provide an approximation of the through-thickness shear stresses in a solid laminate given the through-thickness shear loads (Qx and Qy) on the panel. The method was needed for implementation within the HyperSizer structural sizing software so that the approximated ply-level shear stresses could be utilized in a failure theory to assess the adequacy of a panel design. The simplified shear solution method was developed based on extending and generalizing bi-material beam theory to plate-like structures. It is assumed that the through-thickness shear stresses arise due to local bending of the laminate induced by the through-thickness shear load, and by imposing

  6. The Research of Improved Grey GM (1, 1) Model to Predict the Postprandial Glucose in Type 2 Diabetes

    PubMed Central

    Wang, Yannian; Wei, Fenfen; Sun, Changqing; Li, Quanzhong

    2016-01-01

    Diabetes may result in some complications and increase the risk of many serious health problems. The purpose of clinical treatment is to carefully manage the blood glucose concentration. If the blood glucose concentration is predicted, treatments can be taken in advance to reduce the harm to patients. For this purpose, an improved grey GM (1, 1) model is applied to predict blood glucose with a small amount of data, and especially in terms of improved smoothness it can get higher prediction accuracy. The original data of blood glucose of type 2 diabetes is acquired by CGMS. Then the prediction model is established. Finally, 50 cases of blood glucose from the Henan Province People's Hospital are predicted in 5, 10, 15, 20, 25, and 30 minutes, respectively, in advance to verify the prediction model. The prediction result of blood glucose is evaluated by the EGA, MSE, and MAE. Particularly, the prediction results of postprandial blood glucose are presented and analyzed. The result shows that the improved grey GM (1, 1) model has excellent performance in postprandial blood glucose prediction. PMID:27314034

  7. Preeclampsia Prediction in Type 1 Diabetes and Diurnal Blood Pressure Methodology.

    PubMed

    Lauszus, Finn Friis

    2016-01-01

    The most recent Cochrane reviews on oral antihypertensive drugs in pregnancy conclude that no substantial benefits for the mother or fetus are demonstrated so far. Whether this applies for a high-risk and diabetic pregnancy is doubtful. The aim of this short review is an introduction to the field of ambulatory blood pressure measurements in pregnancy and in particular in women with type 1 diabetes. Diabetic pregnancy is complicated with a 50% risk of hypertension/preeclampsia. In the nonpregnant, diabetic women minute increases in blood pressure as well as in albuminuria are forerunners for incipient and overt nephropathy. Medication is essential and can conserve renal function, modifying the risk of renal insufficiency. During pregnancy, renal insufficiency in women with diabetes leads to termination of pregnancy. Therefore, detection of minute changes based on reliable measurements in this high-risk population is invaluable to protect the mother's kidney function and, if possible, prolong pregnancy for the benefit of the fetus. Estimates of risk by blood pressure evaluation in these women are influenced by pregnancy per se and diabetes vasculopathy. Several factors have to be considered as few monitors are validated for use in pregnancy and not many of the different methodologies have undergone thorough investigation. The use of absolute values of blood pressure have the advantage that fewer assumptions are necessary on how blood pressure behaves due to modes of evaluation and biological rhythm. Monitors should be chosen with care considering the clinical setting, timing, and population, which influences the outcome, thus, the monitors ought to be validated for the specific condition they are applied for. The strategy for the studies used for safe conclusions in this brief review was chosen with priority of the papers with the best, validated methodology on BP measurements, which is by no way guaranteed in numerous recent publications. Inherent characteristics of

  8. Prediction of protein secondary structure based on residue pair types and conformational states using dynamic programming algorithm.

    PubMed

    Sadeghi, Mehdi; Parto, Sahar; Arab, Shahriar; Ranjbar, Bijan

    2005-06-20

    We have used a statistical approach for protein secondary structure prediction based on information theory and simultaneously taking into consideration pairwise residue types and conformational states. Since the prediction of residue secondary structure by one residue window sliding make ambiguity in state prediction, we used a dynamic programming algorithm to find the path with maximum score. A score system for residue pairs in particular conformations is derived for adjacent neighbors up to ten residue apart in sequence. The three state overall per-residue accuracy, Q3, of this method in a jackknife test with dataset created from PDBSELECT is more than 70%. PMID:15936021

  9. Computational modeling of shear forces and experimental validation of endothelial cell responses in an orbital well shaker system.

    PubMed

    Filipovic, Nenad; Ghimire, Kedar; Saveljic, Igor; Milosevic, Zarko; Ruegg, Curzio

    2016-01-01

    Vascular endothelial cells are continuously exposed to hemodynamic shear stress. Intensity and type of shear stress are highly relevant to vascular physiology and pathology. Here, we modeled shear stress distribution in a tissue culture well (R = 17.5 mm, fill volume 2 ml) under orbital translation using computational fluid dynamics with the finite element method. Free surface distribution, wall shear stress, inclination angle, drag force, and oscillatory index on the bottom surface were modeled. Obtained results predict nonuniform shear stress distribution during cycle, with higher oscillatory shear index, higher drag force values, higher circular component, and larger inclination angle of the shear stress at the periphery of the well compared with the center of the well. The oscillatory index, inclination angle, and drag force are new quantitative parameters modeled in this system, which provide a better understanding of the hydrodynamic conditions experienced and reflect the pulsatile character of blood flow in vivo. Validation experiments revealed that endothelial cells at the well periphery aligned under flow and increased Kruppel-like Factor 4 (KLF-4), cyclooxygenase-2 (COX-2) expression and endothelial nitric oxide synthase (eNOS) phosphorylation. In contrast, endothelial cells at the center of the well did not show clear directional alignment, did not induce the expression of KLF-4 and COX-2 nor increased eNOS phosphorylation. In conclusion, this improved computational modeling predicts that the orbital shaker model generates different hydrodynamic conditions at the periphery versus the center of the well eliciting divergent endothelial cell responses. The possibility of generating different hydrodynamic conditions in the same well makes this model highly attractive to study responses of distinct regions of the same endothelial monolayer to different types of shear stresses thereby better reflecting in vivo conditions. PMID:26096592

  10. Influence of magnetic shear on impurity transport

    SciTech Connect

    Nordman, H.; Fueloep, T.; Candy, J.; Strand, P.; Weiland, J.

    2007-05-15

    The magnetic shear dependence of impurity transport in tokamaks is studied using a quasilinear fluid model for ion temperature gradient (ITG) and trapped electron (TE) mode driven turbulence in the collisionless limit and the results are compared with nonlinear gyrokinetic results using GYRO [J. Candy and R. E. Waltz, J. Comput. Phys 186, 545 (2003)]. It is shown that the impurity transport is sensitive to the magnetic shear, in particular for weak, negative, and large positive shear where a strong reduction of the effective impurity diffusivity is obtained. The fluid and gyrokinetic results are in qualitative agreement, with the gyrokinetic diffusivities typically a factor 2 larger than the fluid diffusivities. The steady state impurity profiles in source-free plasmas are found to be considerably less peaked than the electron density profiles for moderate shear. Comparisons between anomalous and neoclassical transport predictions are performed for ITER-like profiles [R. Aymar, P. Barabaschi, and Y. Shimomura, Plasma Phys. Controlled Fusion 44, 519 (2002)].

  11. Turbulent diffusion with memories and intrinsic shear

    NASA Technical Reports Server (NTRS)

    Tchen, C. M.

    1974-01-01

    The first part of the present theory is devoted to the derivation of a Fokker-Planck equation. The eddies smaller than the hydrodynamic scale of the diffusion cloud form a diffusivity, while the inhomogeneous, bigger eddies give rise to a nonuniform migratory drift. This introduces an eddy-induced shear which reflects on the large-scale diffusion. The eddy-induced shear does not require the presence of a permanent wind shear and is intrinsic to the diffusion. Secondly, a transport theory of diffusivity is developed by the method of repeated-cascade and is based upon a relaxation of a chain of memories with decreasing information. The full range of diffusion consists of inertia, composite, and shear subranges, for which variance and eddy diffusivities are predicted. The coefficients are evaluated. Comparison with experiments in the upper atmosphere and oceans is made.

  12. Dental age estimation and different predictive ability of various tooth types in the Czech population: data mining methods.

    PubMed

    Velemínská, Jana; Pilný, Ales; Cepek, Miroslav; Kot'ová, Magdaléna; Kubelková, Radka

    2013-01-01

    Dental development is frequently used to estimate age in many anthropological specializations. The aim of this study was to extract an accurate predictive age system for the Czech population and to discover any different predictive ability of various tooth types and their ontogenetic stability during infancy and adolescence. A cross-sectional panoramic X-ray study was based on developmental stages assessment of mandibular teeth (Moorrees et al. 1963) using 1393 individuals aged from 3 to 17 years. Data mining methods were used for dental age estimation. These are based on nonlinear relationships between the predicted age and data sets. Compared with other tested predictive models, the GAME method predicted age with the highest accuracy. Age-interval estimations between the 10th and 90th percentiles ranged from -1.06 to +1.01 years in girls and from -1.13 to +1.20 in boys. Accuracy was expressed by RMS error, which is the average deviation between estimated and chronological age. The predictive value of individual teeth changed during the investigated period from 3 to 17 years. When we evaluated the whole period, the second molars exhibited the best predictive ability. When evaluating partial age periods, we found that the accuracy of biological age prediction declines with increasing age (from 0.52 to 1.20 years in girls and from 0.62 to 1.22 years in boys) and that the predictive importance of tooth types changes, depending on variability and the number of developmental stages in the age interval. GAME is a promising tool for age-interval estimation studies as they can provide reliable predictive models. PMID:24466642

  13. Analysis of some predictive factors of quality of life among type 2 diabetic patients

    PubMed Central

    Tol, Azar; Sharifirad, Gholamreza; Eslami, Ahmadali; Shojaeizadeh, Davoud; Alhani, Fatemeh; Tehrani, Mohamadreza Mohajeri

    2015-01-01

    Introduction: Considering the chronic nature of diabetes and its significant effect on quality of life of patients, the present study was conducted to evaluate predictors of quality of life in these patients in order to facilitate planning health promotion intervention programs. Materials and Methods: The present study was designed as a cross-sectional study on 140 type 2 diabetic patients of Om-ol-Banin Diabetes Center of Isfahan. Data collection tool was a multidimensional questionnaire including demographic and disease related data (12 items), the standard scale for diabetes distress (17 items), the standard scale for self-efficacy in diabetic patients (8 items), and standard scale for specific quality of life of diabetic patients (15 items). Collected data were evaluated by SPSS version 11.5 using the Chi-square test, Independent T-test, ANOVA, Pearson correlation and multivariate regression analysis. Results: Results showed that the quality of life of diabetic patients had a statistically significant correlation with diabetes distress variable (P < 0.001) and self-efficacy variable (P < 0.001). In this study R2 (predictive power) was 0.66. Multivariate regression model indicated diabetes distress (β = -0.277, P = 0.01) and self-efficacy (β = -0.161, P < 0.001) as variables influencing adjusted self-management for other variables. Conclusion: The result of the present study urges that in planning health promotion interventions in the field of diabetes, more attention be paid to self-efficacy and diabetes distress variables in order to improve the efficiency and effectiveness of the interventions carried out. PMID:25767820

  14. Measuring Type Ia Supernova Populations of Stretch and Color and Predicting Distance Biases

    NASA Astrophysics Data System (ADS)

    Scolnic, D.; Kessler, R.

    2016-05-01

    Simulations of Type Ia supernovae (SNe Ia) surveys are a critical tool for correcting biases in the analysis of SNe Ia to infer cosmological parameters. Large-scale Monte Carlo simulations include a thorough treatment of observation history, measurement noise, intrinsic scatter models, and selection effects. In this Letter, we improve simulations with a robust technique to evaluate the underlying populations of SN Ia color and stretch that correlate with luminosity. In typical analyses, the standardized SN Ia brightness is determined from linear “Tripp” relations between the light curve color and luminosity and between stretch and luminosity. However, this solution produces Hubble residual biases because intrinsic scatter and measurement noise result in measured color and stretch values that do not follow the Tripp relation. We find a 10σ bias (up to 0.3 mag) in Hubble residuals versus color and 5σ bias (up to 0.2 mag) in Hubble residuals versus stretch in a joint sample of 920 spectroscopically confirmed SN Ia from PS1, SNLS, SDSS, and several low-z surveys. After we determine the underlying color and stretch distributions, we use simulations to predict and correct the biases in the data. We show that removing these biases has a small impact on the low-z sample, but reduces the intrinsic scatter σ int from 0.101 to 0.083 in the combined PS1, SNLS, and SDSS sample. Past estimates of the underlying populations were too broad, leading to a small bias in the equation of state of dark energy w of Δw = 0.005.

  15. Transthyretin Predicts Cardiovascular Outcome in Hemodialysis Patients With Type 2 Diabetes

    PubMed Central

    Henze, Andrea; Espe, Katharina M.; Wanner, Christoph; Krane, Vera; Raila, Jens; Hocher, Berthold; Schweigert, Florian J.; Drechsler, Christiane

    2012-01-01

    OBJECTIVE BMI and albumin are commonly accepted parameters to recognize wasting in dialysis patients and are powerful predictors of morbidity and mortality. However, both parameters reveal limitations and may not cover the entire range of patients with wasting. The visceral protein transthyretin (TTR) may be helpful in overcoming the diagnostic and prognostic gap. Therefore, the aim of this study was to assess the association of TTR with morbidity and mortality in hemodialysis patients. RESEARCH DESIGN AND METHODS The TTR concentration was determined in plasma samples of 1,177 hemodialysis patients with type 2 diabetes. Cox regression analyses were used to determine hazard ratios (HRs) for the risk of cardiovascular end points (CVEs) and mortality according to quartiles of TTR concentration for the total study cohort and the subgroups BMI ≥23 kg/m2, albumin concentration ≥3.8 g/dL, and a combination of both. RESULTS A low TTR concentration was associated with an increased risk for CVE for the total study cohort (HR 1.65 [95% CI 1.27–2.14]), patients with BMI ≥23 kg/m2 (1.70 [1.22–2.37]), albumin ≥3.8 g/dL (1.68 [1.17–2.42]), and the combination of both (1.69 [1.13–2.53]). Additionally, a low TTR concentration predicted mortality for the total study cohort (1.79 [1.43–2.24]) and patients with BMI ≥23 kg/m2 (1.46 [1.09–1.95]). CONCLUSIONS The current study demonstrated that TTR is a useful predictor for cardiovascular outcome and mortality in diabetic hemodialysis patients. TTR was particularly useful in patients who were not identified to be at risk by BMI or albumin status. PMID:22923667

  16. Urinary MicroRNA Profiling Predicts the Development of Microalbuminuria in Patients with Type 1 Diabetes

    PubMed Central

    Argyropoulos, Christos; Wang, Kai; Bernardo, Jose; Ellis, Demetrius; Orchard, Trevor; Galas, David; Johnson, John P.

    2015-01-01

    Microalbuminuria provides the earliest clinical marker of diabetic nephropathy among patients with Type 1 diabetes, yet it lacks sensitivity and specificity for early histological manifestations of disease. In recent years microRNAs have emerged as potential mediators in the pathogenesis of diabetes complications, suggesting a possible role in the diagnosis of early stage disease. We used quantiative polymerase chain reaction (qPCR) to evaluate the expression profile of 723 unique microRNAs in the normoalbuminuric urine of patients who did not develop nephropathy (n = 10) relative to patients who subsequently developed microalbuminuria (n = 17). Eighteen microRNAs were strongly associated with the subsequent development of microalbuminuria, while 15 microRNAs exhibited gender-related differences in expression. The predicted targets of these microRNAs map to biological pathways known to be involved in the pathogenesis and progression of diabetic renal disease. A microRNA signature (miR-105-3p, miR-1972, miR-28-3p, miR-30b-3p, miR-363-3p, miR-424-5p, miR-486-5p, miR-495, miR-548o-3p and for women miR-192-5p, miR-720) achieved high internal validity (cross-validated misclassification rate of 11.1%) for the future development of microalbuminuria in this dataset. Weighting microRNA measurements by their number of kidney-relevant targets improved the prognostic performance of the miRNA signature (cross-validated misclassification rate of 7.4%). Future studies are needed to corroborate these early observations in larger cohorts. PMID:26239688

  17. Haptic Edge Detection Through Shear

    NASA Astrophysics Data System (ADS)

    Platkiewicz, Jonathan; Lipson, Hod; Hayward, Vincent

    2016-03-01

    Most tactile sensors are based on the assumption that touch depends on measuring pressure. However, the pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium. Currently, there is no consensus as to which components of strain are most informative for tactile sensing. Here, we propose that shape-related tactile information is more suitably recovered from shear strain than normal strain. Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals.

  18. Haptic Edge Detection Through Shear

    PubMed Central

    Platkiewicz, Jonathan; Lipson, Hod; Hayward, Vincent

    2016-01-01

    Most tactile sensors are based on the assumption that touch depends on measuring pressure. However, the pressure distribution at the surface of a tactile sensor cannot be acquired directly and must be inferred from the deformation field induced by the touched object in the sensor medium. Currently, there is no consensus as to which components of strain are most informative for tactile sensing. Here, we propose that shape-related tactile information is more suitably recovered from shear strain than normal strain. Based on a contact mechanics analysis, we demonstrate that the elastic behavior of a haptic probe provides a robust edge detection mechanism when shear strain is sensed. We used a jamming-based robot gripper as a tactile sensor to empirically validate that shear strain processing gives accurate edge information that is invariant to changes in pressure, as predicted by the contact mechanics study. This result has implications for the design of effective tactile sensors as well as for the understanding of the early somatosensory processing in mammals. PMID:27009331

  19. Fighting wind shear

    NASA Astrophysics Data System (ADS)

    A “coherent and sustained program” of improved radar detection of weather, pilot training, and better communication between pilots and air controllers can greatly reduce the risk of wind shear to airplanes landing or taking off, according to a National Research Council (NRC) committee.Wind shear, characterized by winds rapidly changing direction and speed, has caused several serious accidents in recent years; among the most notable is the July 8, 1982, crash of a Pan American World Airlines jetliner at the New Orleans International Airport, which killed 153 persons. Following the accident, Congress directed the Federal Aviation Administration (FAA) to contract with the NRC to study wind shear.

  20. Predicting the Use of Single Versus Multiple Types of Violence Towards Children in a Representative Sample of Quebec Families

    ERIC Educational Resources Information Center

    Clement, Marie-Eve; Bouchard, Camil

    2005-01-01

    Objective: The purpose of this study is to determine which factors best predict parental use of single versus multiple types of violence. Methodology: The study uses data from a Quebec telephone survey conducted with a representative sample of 2,469 mothers of children aged 0-17 years. The interview covered topics such as mother's attitudes and…

  1. Haptoglobin genotype predicts development of coronary artery calcification in a prospective cohort of patients with type 1 diabetes

    PubMed Central

    2011-01-01

    Background Coronary artery disease has been linked with genotypes for haptoglobin (Hp) which modulates extracorpuscular hemoglobin. We hypothesized that the Hp genotype would predict progression of coronary artery calcification (CAC), a marker of subclinical atherosclerosis. Methods CAC was measured three times in six years among 436 subjects with type 1 diabetes and 526 control subjects participating in the Coronary Artery Calcification in Type 1 Diabetes (CACTI) study. Hp typing was performed on plasma samples by polyacrylamide gel electrophoresis. Results The Hp 2-2 genotype predicted development of significant CAC only in subjects with diabetes who were free of CAC at baseline (OR: 1.95, 95% CI: 1.07-3.56, p = 0.03), compared to those without the Hp 2-2 genotype, controlling for age, sex, blood pressure and HDL-cholesterol. Hp 2 appeared to have an allele-dose effect on development of CAC. Hp genotype did not predict CAC progression in individuals without diabetes. Conclusions Hp genotype may aid prediction of accelerated coronary atherosclerosis in subjects with type 1 diabetes. PMID:22098782

  2. Inability to Predict Cardiovascular Disease from Hostility Scores or MMPI Related to Type A Behavior.

    ERIC Educational Resources Information Center

    Leon, Gloria R.; And Others

    1988-01-01

    Evaluated medical and psychological data collected over 36 years on 280 men to identify personality characteristics and attitudes possibly predictive of development of coronary heart disorder (CHD). Minnesota Multiphasic Personality Inventory (MMPI) Hostility scores did not predict CHD, nor did 35-item scale derived from MMPI items judged to…

  3. Correlation of densities with shear wave velocities and SPT N values

    NASA Astrophysics Data System (ADS)

    Anbazhagan, P.; Uday, Anjali; Moustafa, Sayed S. R.; Al-Arifi, Nassir S. N.

    2016-06-01

    Site effects primarily depend on the shear modulus of subsurface layers, and this is generally estimated from the measured shear wave velocity (V s) and assumed density. Very rarely, densities are measured for amplification estimation because drilling and sampling processes are time consuming and expensive. In this study, an attempt has been made to derive the correlation between the density (dry and wet density) and V s/SPT (standard penetration test) N values using measured data. A total of 354 measured V s and density data sets and 364 SPT N value and density data sets from 23 boreholes have been used in the study. Separate relations have been developed for all soil types as well as fine-grained and coarse-grained soil types. The correlations developed for bulk density were compared with the available data and it was found that the proposed relation matched well with the existing data. A graphical comparison and validation based on the consistency ratio and cumulative frequency curves was performed and the newly developed relations were found to demonstrate good prediction performance. An attempt has also been made to propose a relation between the bulk density and shear wave velocity applicable for a wide range of soil and rock by considering data from this study as well as that of previous studies. These correlations will be useful for predicting the density (bulk and dry) of sites having measured the shear wave velocity and SPT N values.

  4. Novel Composites for Wing and Fuselage Applications: Speedy Nonlinear Analysis of Postbuckled Panels in Shear (SNAPPS)

    NASA Technical Reports Server (NTRS)

    Sharp, Dave; Sobel, Larry

    1997-01-01

    A simple and rapid analysis method, consisting of a number of modular, 'strength-of-materials-type' models, is presented for predicting the nonlinear response and stiffener separation of postbuckled, flat, composite, shear panels. The analysis determines the maximum principal tensile stress in the skin surface layer under to toe. Failure is said to occur when this stress reaches the mean transverse tensile strength of the layer. The analysis methodology consists of a number of closed-form equations that can easily be used in a 'hand analysis. For expediency, they have been programmed into a preliminary design code called SNAPPS (Speedy Nonlinear Analysis of Postbuckled Panels in Shear), which rapidly predicts postbuckling response of the panel for each value of the applied shear load. SNAPPS response and failure predictions were found to agree well with test results for three panels with widely different geometries, laminates and stiffnesses. Design guidelines are given for increasing the load-carrying capacity of stiffened, composite shear panels.

  5. Type D Personality Predicts Poor Medication Adherence in Chinese Patients with Type 2 Diabetes Mellitus: A Six-Month Follow-Up Study

    PubMed Central

    Li, Xuemei; Zhang, Shengfa; Xu, Huiwen; Tang, Xinfeng; Zhou, Huixuan; Yuan, Jiaqi; Wang, Xiaohua; Qu, Zhiyong; Wang, Fugang; Zhu, He; Guo, Shuai

    2016-01-01

    Background Type D personality and medication nonadherence have been shown to be associated with poor health outcomes. Type D personality is associated with poor medication adherence in patients with coronary artery disease, myocardial infarction, and heart failure. However, the relationship between type D personality and medication adherence in patients with Type 2 Diabetes Mellitus (T2DM) remains unknown. This study aims to examine whether type D personality was associated with medication adherence in patients with T2DM. Design and Settings A follow-up study was conducted in general hospital of the People's Liberation Army in Beijing. Methods 412 T2DM patients (205 females), who were recruited by circular systematic random sampling, provided demographic and baseline data about medical information and completed measures of Type D personality. Then, 330 patients went on to complete a self-report measure of medication adherence at the sixth month after baseline data collection. Chi-square test, t tests, and hierarchical multiple regression analyses were conducted, as needed. Results Patients with type D personality were significantly more likely to have poor medication adherence (p<0.001). Type D personality predicts poor medication adherence before and after controlling for covariates when it was analyzed as a categorical variable. However, the dimensional construct of type D personality was not associated with medication adherence when analyzed as a continuous variable. Conclusion Although, as a dimensional construct, type D personality may not reflect the components of the personality associated with poor medication adherence in patients with T2DM, screening for type D personality may help to identify those who are at higher risk of poor medication adherence. Interventions, aiming to improve medication adherence, should be launched for these high-risk patients. PMID:26894925

  6. Instability predictions for circumferentially cracked Type-304 stainless steel pipes under dynamic loading. Volume 2. Appendixes. Final report. [BWR

    SciTech Connect

    Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

    1982-04-01

    This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models.

  7. Instability predictions for circumferentially cracked Type-304 stainless-steel pipes under dynamic loading. Final report. [BWR

    SciTech Connect

    Zahoor, A.; Wilkowski, G.; Abou-Sayed, I.; Marschall, C.; Broek, D.; Sampath, S.; Rhee, H.; Ahmad, J.

    1982-04-01

    This report provides methods to predict margins of safety for circumferentially cracked Type 304 stainless steel pipes subjected to applied bending loads. An integrated combination of experimentation and analysis research was pursued. Two types of experiments were performed: (1) laboratory-scale tests on center-cracked panels and bend specimens to establish the basic mechanical and fracture properties of Type 304 stainless steel, and (2) full-scale pipe fracture tests under quasi-static and dynamic loadings to assess the analysis procedures. Analyses were based upon the simple plastic collapse criterion, a J-estimation procedure, and elastic-plastic large-deformation finite element models.

  8. Serum uric acid predicts vascular complications in adults with type 1 diabetes: the coronary artery calcification in type 1 diabetes study.

    PubMed

    Bjornstad, Petter; Maahs, David M; Rivard, Christopher J; Pyle, Laura; Rewers, Marian; Johnson, Richard J; Snell-Bergeon, Janet K

    2014-10-01

    Epidemiologic evidence supports a link between serum uric acid (SUA) and vascular complications in diabetes, but it remains unclear whether SUA improves the ability of conventional risk factor to predict complications. We hypothesized that SUA at baseline would independently predict the development of vascular complications over 6 years and that the addition of SUA to American Diabetes Association's ABC risk factors (HbA1c, BP, LDL-C) would improve vascular complication prediction over 6 years in adults with type 1 diabetes. Study participants (N = 652) were 19-56 year old at baseline and re-examined 6 years later. Diabetic nephropathy was defined as incident albuminuria or rapid GFR decline (>3.3 %/year) estimated by the CKD-EPI cystatin C. Diabetic retinopathy (DR) was based on self-reported history, and proliferative diabetic retinopathy (PDR) was defined as laser eye therapy; coronary artery calcium (CAC) was measured using electron-beam computed tomography. Progression of CAC (CACp) was defined as a change in the square-root-transformed CAC volume ≥2.5. Predictors of each complication were examined in stepwise logistic regression with subjects with complications at baseline excluded from analyses. C-statistics, integrated discrimination indices and net-reclassification improvement were utilized for prediction performance analyses. SUA independently predicted development of incident albuminuria (OR 1.8, 95 % CI 1.2-2.7), rapid GFR decline (1.9, 1.1-3.3), DR (1.4, 1.1-1.9), PDR (2.1, 1.4-3.0) and CACp (1.5, 1.1-1.9). SUA improved the discrimination and net-classification risk of vascular complications over 6 years. SUA independently predicted the development of vascular complications in type 1 diabetes and also improved the reclassification of vascular complications. PMID:24929955

  9. Serum Uric Acid Predicts Vascular Complications in Adults with Type 1 Diabetes: the Coronary Artery Calcification in Type 1 Diabetes Study

    PubMed Central

    Bjornstad, Petter; Maahs, David M.; Rivard, Christopher J.; Pyle, Laura; Rewers, Marian; Johnson, Richard J.; Snell-Bergeon, Janet K.

    2015-01-01

    Hypothesis Epidemiologic evidence support a link between serum uric acid (SUA) and vascular complications in diabetes, but it remains unclear whether SUA improves the ability of conventional risk factor to predict complications. We hypothesized that SUA at baseline would independently predict the development of vascular complications over 6 years, and that the addition of SUA to American Diabetes Association’s ABC risk factors (HbA1c, BP, LDL-C) would improve vascular complication prediction over 6-years in adults with type 1 diabetes. Methods Study participants (N=652) were 19–56 year old at baseline and re-examined 6-years later. Diabetic nephropathy (DN) was defined as incident albuminuria or rapid GFR decline (>3.3%/year) estimated by the CKD-EPI cystatin C. Diabetic retinopathy (DR) was based on self-reported history, proliferative diabetic retinopathy (PDR) was defined as laser eye therapy; coronary artery calcium (CAC) was measured using electron-beam computed-tomography. Progression of CAC (CACp) was defined as a change in the square-root transformed CAC-volume ≥ 2.5. Predictors of each complication were examined in stepwise logistic regression with subjects with complications at baseline excluded from analyses. C-statistics, integrated-discrimination indices and net-reclassification improvement were utilized for prediction performance analyses. Results SUA independently predicted development of incident albuminuria (OR: 1.8, 95% CI 1.2–2.7), rapid GFR decline (1.9, 1.1–3.3), DR (1.4, 1.1–1.9), PDR (2.1, 1.4–3.0) and CACp (1.5 (1.1–1.9). SUA improved the discrimination and net-classification risk of vascular complications over 6-years. Conclusion SUA independently predicted the development of vascular complications in type 1 diabetes, and also improved the reclassification of vascular complications. PMID:24929955

  10. Does albuminuria predict renal risk and/or cardiovascular risk in obese type 2 diabetic patients?

    PubMed

    Bentata, Yassamine; Abouqal, Redouane

    2014-01-01

    Increased urinary albumin excretion (UAE) is a marker of renal and cardiovascular risk in patients with type 2 diabetes (DT2). What about the obese patient with DT2? Does albuminuria predict the progression of renal disease and/or cardiovascular disease? The objective of this study is to determine the link between albuminuria, renal risk and cardiovascular risk in a cohort of obese DT2 patients. This is a prospective study begun in September 2006. It included DT2 patients presenting obesity defined by a body mass index (BMI)>30 Kg/m(2). Three groups of patients were defined: normo-albuminuria (Urinary Albumin Excretion UAE<30 mg/day or Albumin Creatinine Ratio ACR<30 mg/g), micro-albuminuria (UAE=30-300 mg/day or ACR=30-300 mg/g) and macro-albuminuria (UAE>300 mg/day or ACR>300 mg/g). Data on 144 obese DT2 patients were compiled: The mean age of our patients was 59 ± 9 years and the sex ratio 0.26. The incidence of ESRD was higher in the macro-albuminuria group than in the two other groups (26.5% vs. 1.2%, p<0.001). The incidence of cardiovascular events was 15.4%, 14.3% and 23.5% in the normo, micro and macro-albuminuria groups (p=0.48). A history of cardiovascular comorbidities was the main cardiovascular risk in multivariate analysis (0R=15.07; 95% CI=5.30-42.82; p<0.001) and the low admission GFR (0R=5.67; 95% CI=1.23-9.77; p=0.008) was the main factor for progression of kidney disease in multivariate analysis. Albuminuria may be a better marker of kidney disease progression than of cardiovascular risk in the obese DT2 patient, according to our results. However, to accurately demonstrate the link albuminuria - renal risk and albuminuria - cardiovascular risk in the obese DT2 patient, additional studies using very strict criteria of selection and judgment are needed. PMID:24551483

  11. Viscous shear dampers

    SciTech Connect

    Zilahi-Szabo, I.

    1980-10-07

    In a viscous shear damper, the seismic mass is chamfered at all its corners. Thus, the clearances between the seismic mass and its casing are gaps with oppositely widening out sections separated by middle sections of smallest widths.

  12. Complex shear modulus of a magnetorheological elastomer

    NASA Astrophysics Data System (ADS)

    Zhou, G. Y.

    2004-10-01

    In our previous study (Zhou 2003 Smart Mater. Struct. 12 139-46), a technique to extract the field-induced shear modulus through an experiment testing the responded acceleration of a system composed of a magnetorheological elastomer (MRE) and a cuprous mass was introduced. In this paper, we present a different data processing method, based on the Steiglitz-McBride iteration method, to recover the complex shear modulus of an MRE in the frequency domain through the measured force excitation and responded acceleration of the mass in the above-mentioned experiment. The recovered complex shear modulus is analyzed in three ranges of the frequency domain: low-frequency range, moderate-frequency range, and high-frequency range. In the low-frequency range (<250 Hz), the shear modulus is a bell-type curve rising with the applied magnetic field. The average shear modulus over this frequency range is proportional to the applied magnetic field until magnetic saturation is reached. The maximum change of the average shear modulus over this range is found to be above 55% of the zero-field value. The above phenomenon reaffirms that the subquadratic field dependence, which arises from the saturation of the magnetization near the poles of closely spaced pairs of spheres, must be taken into account. In the moderate-frequency range and high-frequency range, the shear modulus is too complex to be analyzed completely by the proposed method. However, some interesting phenomena are also revealed by the proposed method. For instance, the shear modulus increases with frequency at least with the order of a quadratic polynomial, and the shear modulus is not significantly affected by the applied magnetic field.

  13. PREDICTION OF TYPE II SOLAR RADIO BURSTS BY THREE-DIMENSIONAL MHD CORONAL MASS EJECTION AND KINETIC RADIO EMISSION SIMULATIONS

    SciTech Connect

    Schmidt, J. M.; Cairns, Iver H.; Hillan, D. S.

    2013-08-20

    Type II solar radio bursts are the primary radio emissions generated by shocks and they are linked with impending space weather events at Earth. We simulate type II bursts by combining elaborate three-dimensional MHD simulations of realistic coronal mass ejections (CMEs) at the Sun with an analytic kinetic radiation theory developed recently. The modeling includes initialization with solar magnetic and active region fields reconstructed from magnetograms of the Sun, a flux rope of the initial CME dimensioned with STEREO spacecraft observations, and a solar wind driven with averaged empirical data. We demonstrate impressive accuracy in time, frequency, and intensity for the CME and type II burst observed on 2011 February 15. This implies real understanding of the physical processes involved regarding the radio emission excitation by shocks and supports the near-term development of a capability to predict and track these events for space weather prediction.

  14. Chaotic Boundaries of Nematic Polymers in Mixed Shear and Extensional Flows

    NASA Astrophysics Data System (ADS)

    Forest, M. Gregory; Zhou, Ruhai; Wang, Qi

    2004-08-01

    Chaotic orientational dynamics of sheared nematic polymers is documented in laboratory experiments and predicted by Doi-Hess kinetic theory for infinitely thin rods. We address robustness of rheochaos when simple shear is modified by a planar straining flow, and the macromolecules have finite aspect ratio. We predict persistence of sheared chaotic response up to a threshold straining flow strength and minimum aspect ratio, beyond which chaotic behavior is arrested. More intriguing, a straining component can induce chaos from periodic shear responses.

  15. When is a type III functional response stabilizing? Theory and practice of predicting plankton dynamics under enrichment.

    PubMed

    Uszko, Wojciech; Diehl, Sebastian; Pitsch, Nadine; Lengfellner, Kathrin; Müller, Thomas

    2015-12-01

    The curvature of generalized Holling type functional response curves is controlled by a shape parameter b yielding hyperbolic type II (b = 1) to increasingly sigmoid type III (b > 1) responses. Empirical estimates of b vary considerably across taxa. Larger consumer-resource body mass ratios have been suggested to generate more pronounced type III responses and therefore to promote dynamic stability. The dependence of consumer- resource stability on b has, however, not been systematically explored, and the accurate empirical determination of b is challenging. Specifically, the shape of the functional response of the pelagic grazer Daphnia feeding on phytoplankton, and its consequences for stability, remain controversial. We derive a novel analytical condition relating b to local stability of consumer-resource interactions and use it to predict stability of empirically parameterized models of Daphnia and phytoplankton under enrichment. Functional response parameters were experimentally derived for two species of Daphnia feeding separately on single cultures of two different phytoplankton species. All experimentally studied Daphnia-algae systems exhibited type III responses. Parameterized type III responses are predicted to stabilize the modeled Daphnia-phytoplankton dynamics in some species pairs but not in others. Remarkably, stability predictions differ depending on whether functional response parameters are derived from clearance vs. ingestion rates. Accurate parameter estimation may therefore require fitting to both rates. In addition, our estimates of b for filter-feeding Daphnia are much smaller than predicted for actively hunting predators at similar consumer-resource body mass ratios. This suggests that the relationship between functional response shape and body mass ratios may vary with predation mode. PMID:26909430

  16. Shear strength of municipal solid waste for stability analyses

    NASA Astrophysics Data System (ADS)

    Stark, Timothy D.; Huvaj-Sarihan, Nejan; Li, Guocheng

    2009-06-01

    This paper investigates the shear strength of municipal solid waste (MSW) using the back analysis of failed waste slopes as well as field and laboratory test results. Shear strength of MSW is a function of many factors such as waste type, composition, compaction, daily cover, moisture conditions, age, decomposition, overburden pressure, etc. These factors together with non-standardized sampling methods, insufficient sample size to be representative of in situ conditions, and limited shear displacement or axial strain imposed during the laboratory shear testing have created considerable scatter in reported results. Based on the data presented herein, large shear displacements are required to mobilize the peak shear strength of MSW which can lead to displacement incompatibility between MSW and the underlying material(s) such as geosynthetic interfaces and foundation soils. The data presented herein are used to develop displacement compatible shear strength parameters for MSW. Recommendations are presented for modeling the displacement and stress dependent strength envelope in stability analyses.

  17. Critical shear stress for erosion of cohesive soils subjected to temperatures typical of wildfires

    USGS Publications Warehouse

    Moody, J.A.; Dungan, Smith J.; Ragan, B.W.

    2005-01-01

    [1] Increased erosion is a well-known response after wildfire. To predict and to model erosion on a landscape scale requires knowledge of the critical shear stress for the initiation of motion of soil particles. As this soil property is temperature-dependent, a quantitative relation between critical shear stress and the temperatures to which the soils have been subjected during a wildfire is required. In this study the critical shear stress was measured in a recirculating flume using samples of forest soil exposed to different temperatures (40??-550??C) for 1 hour. Results were obtained for four replicates of soils derived from three different types of parent material (granitic bedrock, sandstone, and volcanic tuffs). In general, the relation between critical shear stress and temperature can be separated into three different temperature ranges (275??C), which are similar to those for water repellency and temperature. The critical shear stress was most variable (1.0-2.0 N m-2) for temperatures 2.0 N m-2) between 175?? and 275??C, and was essentially constant (0.5-0.8 N m-2) for temperatures >275??C. The changes in critical shear stress with temperature were found to be essentially independent of soil type and suggest that erosion processes in burned watersheds can be modeled more simply than erosion processes in unburned watersheds. Wildfire reduces the spatial variability of soil erodibility associated with unburned watersheds by eliminating the complex effects of vegetation in protecting soils and by reducing the range of cohesion associated with different types of unburned soils. Our results indicate that modeling the erosional response after a wildfire depends primarily on determining the spatial distribution of the maximum soil temperatures that were reached during the wildfire. Copyright 2005 by the American Geophysical Union.

  18. Type and token bigram frequencies for two-through nine-letter words and the prediction of anagram difficulty.

    PubMed

    Knight, David; Muncer, Steven J

    2011-06-01

    Recent research on anagram solution has produced two original findings. First, it has shown that a new bigram frequency measure called top rank, which is based on a comparison of summed bigram frequencies, is an important predictor of anagram difficulty. Second, it has suggested that the measures from a type count are better than token measures at predicting anagram difficulty. Testing these hypotheses has been difficult because the computation of the bigram statistics is difficult. We present a program that calculates bigram measures for two-to nine-letter words. We then show how the program can be used to compare the contribution of top rank and other bigram frequency measures derived from both a token and a type count. Contrary to previous research, we report that type measures are not better at predicting anagram solution times and that top rank is not the best predictor of anagram difficulty. Lastly we use this program to show that type bigram frequencies are not as good as token bigram frequencies at predicting word identification reaction time. PMID:21416304

  19. Determination of the Shear Stress Distribution in a Laminate from the Applied Shear Resultant--A Simplified Shear Solution

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.

    2007-01-01

    The simplified shear solution method is presented for approximating the through-thickness shear stress distribution within a composite laminate based on laminated beam theory. The method does not consider the solution of a particular boundary value problem, rather it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply level stresses can be efficiently determined from global load resultants (as determined, for instance, by finite element analysis) at a given location in a structure and used to evaluate the margin of safety on a ply by ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. Comparisons to existing theories are made for a variety of laminates, and design examples are provided illustrating the use of the method for determining through-thickness shear stress margins in several types of composite panels and in the context of a finite element structural analysis.

  20. Simplified Shear Solution for Determination of the Shear Stress Distribution in a Composite Panel from the Applied Shear Resultant

    NASA Technical Reports Server (NTRS)

    Bednarcyk, Brett A.; Aboudi, Jacob; Yarrington, Phillip W.; Collier, Craig S.

    2008-01-01

    The simplified shear solution method is presented for approximating the through-thickness shear stress distribution within a composite laminate or panel based on laminated beam theory. The method does not consider the solution of a particular boundary value problem; rather it requires only knowledge of the global shear loading, geometry, and material properties of the laminate or panel. It is thus analogous to lamination theory in that ply level stresses can be efficiently determined from global load resultants (as determined, for instance, by finite element analysis) at a given location in a structure and used to evaluate the margin of safety on a ply by ply basis. The simplified shear solution stress distribution is zero at free surfaces, continuous at ply boundaries, and integrates to the applied shear load. Comparisons to existing theories are made for a variety of laminates, and design examples are provided illustrating the use of the method for determining through-thickness shear stress margins in several types of composite panels and in the context of a finite element structural analysis.

  1. Effects of movement distance, duration, velocity, and type on action prediction in 12-month-olds.

    PubMed

    Daum, Moritz M; Gampe, Anja; Wronski, Caroline; Attig, Manja

    2016-05-01

    The goal of the present study was to test the influence of the spatial and temporal dynamics of observed manual actions on infants' action prediction. Twelve-month-old infants were presented with reach-and-transport actions performed by a human agent. Movement distance, duration, and - resulting from the two - movement velocity were systematically varied. Action prediction was measured via the latency of gaze arrival at target in relation to agent's hand. The results showed a general effect of all parameters on the infants' perception of goal-directed actions: Infants were more likely to predict the action goal the longer the movement distance was, the longer the movement duration was, and the slower the movement velocity was. In addition, they were more likely to predict the goal of a reaching than a transport action. The present findings extent previous findings by showing that infants are not only sensitive to differences in distances, durations, and velocities at early age but that these factors have a strong impact on the prediction of the goal of observed actions. PMID:27175908

  2. Types of Workplace Social Support in the Prediction of Job Satisfaction

    ERIC Educational Resources Information Center

    Harris, J. Irene; Winskowski, Ann Marie; Engdahl, Brian E.

    2007-01-01

    Research on social support and job satisfaction has yielded mixed results, partly because studies have rarely examined different types of workplace social support, such as collegial support, task support, coaching, and career mentoring. This study identified the relative contributions of different types of social support to job satisfaction and…

  3. Predicting the Types of J-Proteins Using Clustered Amino Acids

    PubMed Central

    Feng, Pengmian; Zuo, Yongchun

    2014-01-01

    J-proteins are molecular chaperones and present in a wide variety of organisms from prokaryote to eukaryote. Based on their domain organizations, J-proteins can be classified into 4 types, that is, Type I, Type II, Type III, and Type IV. Different types of J-proteins play distinct roles in influencing cancer properties and cell death. Thus, reliably annotating the types of J-proteins is essential to better understand their molecular functions. In the present work, a support vector machine based method was developed to identify the types of J-proteins using the tripeptide composition of reduced amino acid alphabet. In the jackknife cross-validation, the maximum overall accuracy of 94% was achieved on a stringent benchmark dataset. We also analyzed the amino acid compositions by using analysis of variance and found the distinct distributions of amino acids in each family of the J-proteins. To enhance the value of the practical applications of the proposed model, an online web server was developed and can be freely accessed. PMID:24804260

  4. Weakly sheared active suspensions: hydrodynamics, stability, and rheology.

    PubMed

    Cui, Zhenlu

    2011-03-01

    We present a kinetic model for flowing active suspensions and analyze the behavior of a suspension subjected to a weak steady shear. Asymptotic solutions are sought in Deborah number expansions. At the leading order, we explore the steady states and perform their stability analysis. We predict the rheology of active systems including an activity thickening or thinning behavior of the apparent viscosity and a negative apparent viscosity depending on the particle type, flow alignment, and the anchoring conditions, which can be tested on bacterial suspensions. We find remarkable dualities that show that flow-aligning rodlike contractile (extensile) particles are dynamically and rheologically equivalent to flow-aligning discoid extensile (contractile) particles for both tangential and homeotropic anchoring conditions. Another key prediction of this work is the role of the concentration of active suspensions in controlling the rheological behavior: the apparent viscosity may decrease with the increase of the concentration. PMID:21517529

  5. Weakly sheared active suspensions: Hydrodynamics, stability, and rheology

    NASA Astrophysics Data System (ADS)

    Cui, Zhenlu

    2011-03-01

    We present a kinetic model for flowing active suspensions and analyze the behavior of a suspension subjected to a weak steady shear. Asymptotic solutions are sought in Deborah number expansions. At the leading order, we explore the steady states and perform their stability analysis. We predict the rheology of active systems including an activity thickening or thinning behavior of the apparent viscosity and a negative apparent viscosity depending on the particle type, flow alignment, and the anchoring conditions, which can be tested on bacterial suspensions. We find remarkable dualities that show that flow-aligning rodlike contractile (extensile) particles are dynamically and rheologically equivalent to flow-aligning discoid extensile (contractile) particles for both tangential and homeotropic anchoring conditions. Another key prediction of this work is the role of the concentration of active suspensions in controlling the rheological behavior: The apparent viscosity may decrease with the increase of the concentration.

  6. Electrochemical Li insertion studies on WNb{sub 12}O{sub 33}-A shear ReO{sub 3} type structure

    SciTech Connect

    Saritha, D.; Pralong, V.; Varadaraju, U.V.; Raveau, B.

    2010-05-15

    Electrochemical lithium insertion studies on WNb{sub 12}O{sub 33} synthesized by solid state reaction (SSR) are carried out in the voltage range 1.0-3.2 V. During first discharge 15.6 Li are inserted with a specific capacity of 221 mAh/g. WNb{sub 12}O{sub 33} is also synthesized by sol-gel (SG) technique with a view to enhance the rate capability and cycling properties. The SSR and SG samples are characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and galvanostatic cycling. Electrochemical cycling performance of SG samples is superior to that of the SSR sample at high 'C' rates. The sample synthesized by SG method exhibits high specific capacity of 142 mAh/g after 20 cycles at 20C rate. - Graphical abstract: The projected structure can be described as 3x4xinfinity ReO{sub 3} type blocks of NbO{sub 6} octahedra sharing corners, joined with identical blocks via tetrahedrally coordinated tungsten atoms.

  7. Converging shear rheometer

    NASA Astrophysics Data System (ADS)

    Baek, Hyung M.; Mix, Adam W.; Giacomin, A. Jeffrey

    2014-05-01

    For highly viscous fluids that slip in parallel sliding plate rheometers, we want to use a slightly converging flow to suppress this wall slip. In this work, we first attack the steady shear flow of a highly viscous Newtonian fluid between two gently converging plates with no slip boundaries using the equation of motion in cylindrical coordinates, which yields no analytical solution. Then we treat the same problem using the lubrication approximation in Cartesian coordinates to yield exact, explicit solutions for dimensionless velocity, pressure and shear stress. This work deepens our understanding of a drag flow through a gently converging slit of arbitrary convergence angle. We also employ the corotational Maxwell model to explore the role of viscoelasticity in this converging shear flow. We then compare these analytical solutions to finite element calculations for both Newtonian and corotational Maxwell cases. A worked example for determining the Newtonian viscosity using a converging shear rheometer is also included. With this work, we provide the framework for exploring other constitutive equations or other boundary conditions in future work. Our results can also be used to design the linear bearings used for the parallel sliding plate rheometer (SPR). This work can also be used to evaluate the error in the shear stress that is caused by bearing misalignment and specify the parallelism tolerance for the linear bearings incorporated into a SPR.

  8. Two-dimensional magnetic colloids under shear.

    PubMed

    Mohorič, Tomaž; Dobnikar, Jure; Horbach, Jürgen

    2016-04-01

    Complex rheological properties of soft disordered solids, such as colloidal gels or glasses, inspire a range of novel applications. However, the microscopic mechanisms of their response to mechanical loading are not well understood. Here, we elucidate some aspects of these mechanisms by studying a versatile model system, i.e. two-dimensional superparamagnetic colloids in a precessing magnetic field, whose structure can be tuned from a hexagonal crystal to a disordered gel network by varying the external field opening angle θ. We perform Langevin dynamics simulations subjecting these structures to a constant shear rate and observe three qualitatively different types of material response. In hexagonal crystals (θ = 0°), at a sufficiently low shear rate, plastic flow occurs via successive stress drops at which the stress releases due to the formation of dislocation defects. The gel network at θ = 48°, on the contrary, via bond rearrangement and transient shear banding evolves into a homogeneously stretched network at large strains. The latter structure remains metastable after switching off of the shear. At θ = 50°, the external shear makes the system unstable against phase separation and causes a failure of the network structure leading to the formation of hexagonal close packed clusters interconnected by particle chains. At a microcopic level, our simulations provide insight into some of the mechanisms by which strain localization as well as material failure occur in a simple gel-like network. Furthermore, we demonstrate that new stretched network structures can be generated by the application of shear. PMID:26877059

  9. Behavior of Tilted Angle Shear Connectors

    PubMed Central

    Khorramian, Koosha; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N. H.

    2015-01-01

    According to recent researches, angle shear connectors are appropriate to transfer longitudinal shear forces across the steel-concrete interface. Angle steel profile has been used in different positions as L-shaped or C-shaped shear connectors. The application of angle shear connectors in tilted positions is of interest in this study. This study investigates the behaviour of tilted-shaped angle shear connectors under monotonic loading using experimental push out tests. Eight push-out specimens are tested to investigate the effects of different angle parameters on the ultimate load capacity of connectors. Two different tilted angles of 112.5 and 135 degrees between the angle leg and steel beam are considered. In addition, angle sizes and lengths are varied. Two different failure modes were observed consisting of concrete crushing-splitting and connector fracture. By increasing the size of connector, the maximum load increased for most cases. In general, the 135 degrees tilted angle shear connectors have a higher strength and stiffness than the 112.5 degrees type. PMID:26642193

  10. TCLP: an online cancer cell line catalogue integrating HLA type, predicted neo-epitopes, virus and gene expression.

    PubMed

    Scholtalbers, Jelle; Boegel, Sebastian; Bukur, Thomas; Byl, Marius; Goerges, Sebastian; Sorn, Patrick; Loewer, Martin; Sahin, Ugur; Castle, John C

    2015-01-01

    Human cancer cell lines are an important resource for research and drug development. However, the available annotations of cell lines are sparse, incomplete, and distributed in multiple repositories. Re-analyzing publicly available raw RNA-Seq data, we determined the human leukocyte antigen (HLA) type and abundance, identified expressed viruses and calculated gene expression of 1,082 cancer cell lines. Using the determined HLA types, public databases of cell line mutations, and existing HLA binding prediction algorithms, we predicted antigenic mutations in each cell line. We integrated the results into a comprehensive knowledgebase. Using the Django web framework, we provide an interactive user interface with advanced search capabilities to find and explore cell lines and an application programming interface to extract cell line information. The portal is available at http://celllines.tron-mainz.de. PMID:26589293

  11. PREDICTION OF SEROTONERGIC TREATMENT EFFICACY USING AGE OF ONSET AND TYPE A/B TYPOLOGIES OF ALCOHOLISM

    PubMed Central

    Roache, John D.; Wang, Yanmei; Ait-Daoud, Nassima; Johnson, Bankole A.

    2009-01-01

    Background Previously, we reported that ondansetron was efficacious at treating early-onset (≤25 years old) but not late-onset (≥26 years old) alcoholics in a double-blind, randomized, placebo-controlled clinical trial (n = 321 enrolled patients, 271 of them randomized). Randomized participants underwent 11 weeks of treatment with ondansetron (1, 4, or 16 µg/kg twice daily; n = 67, 77, and 71, respectively) or identical placebo (n = 56), plus weekly standardized group cognitive behavioral therapy. Methods For this study, we reanalyzed the original sample to determine whether the Type A/B typological classification predicts ondansetron treatment response. In this comparative analysis, k-means clustering was applied to 19 baseline measures of drinking behavior, psychopathology, and social functioning, similar to those used by Babor in the original typological derivation. A two-factor solution described robustly two groups phenomenologically consistent with Type A/B classification. Subjects were subdivided into early- and late-onset alcoholics. Results Seventy-two percent of Type B subjects had early-onset alcoholism; 67% of Type A subjects had late-onset alcoholism. The A/B typology better discriminated two clusters based upon baseline severity of alcoholism. There was a significant effect (p < 0.05) for Type B alcoholics to respond to ondansetron (4 µg/kg); however, Type A alcoholics receiving ondansetron showed no beneficial effect. Early-vs. late-onset classification predicted ondansetron response substantially better than Type A/B classification, which did not add to the prediction of treatment outcome. Further analyses showed that ondansetron was effective in the 33% of Type A alcoholics with early-onset alcoholism but ineffective in the 28% of Type B alcoholics with late-onset alcoholism. Conclusions Type A/B classification best discriminates alcoholic subtypes based upon baseline severity. Early- vs. late-onset classification is, however, a better

  12. Application of Strainrange Partitioning to the prediction of creep-fatigue lives of AISI Types 304 and 316 stainless steel

    NASA Technical Reports Server (NTRS)

    Saltsman, J. F.; Halford, G. R.

    1977-01-01

    As a demonstration of the predictive capabilities of the method of Strainrange Partitioning, published high-temperature, low cycle, creep-fatigue test results on AISI Types 304 and 316 stainless steel were analyzed and calculated cyclic lives compared with observed lives. Predicted lives agreed with observed lives within factors of two for 76 percent, factors of three for 93 percent, and factors of four for 98 percent of the laboratory tests analyzed. Agreement between observed and predicted lives is judged satisfactory considering that the data are associated with a number of variables (two alloys, several heats and heat treatments, a range of temperatures, different testing techniques, etc.) that are not directly accounted for in the calculations.

  13. Application of strainrange partitioning to the prediction of creep-fatigue lives of AISI types 304 and 316 stainless steel

    NASA Technical Reports Server (NTRS)

    Saltsman, J. F.; Halford, G. R.

    1976-01-01

    As a demonstration of the predictive capabilities of the method of Strainrange Partitioning, published high-temperature, low cycle, creep-fatigue test results on AISI Types 304 and 316 stainless steel were analyzed and calculated, cyclic lives compared with observed lives. Predicted lives agreed with observed lives within factors of two for 76 percent, factors of three for 93 percent, and factors of four for 98 percent of the laboratory tests analyzed. Agreement between observed and predicted lives is judged satisfactory considering that the data are associated with a number of variables (two alloys, several heats and heat treatments, a range of temperatures, different testing techniques, etc.) that are not directly accounted for in the calculations.

  14. Wind shear and wet and dry thermodynamic indices as predictors of thunderstorm motion and severity and application to the AVE 4 experimental data

    NASA Technical Reports Server (NTRS)

    Connell, J. R.; Ey, L.

    1977-01-01

    Two types of parameters are computed and mapped for use in assessing their individual merits as predictors of occurrence and severity of thunderstorms. The first group is comprised of equivalent potential temperature, potential temperature, water vapor mixing ratio, and wind speed. Equivalent potential temperature maxima and strong gradients of equivalent potential temperature at the surface correlate well with regions of thunderstorm activity. The second type, comprised of the energy index, shear index, and energy shear index, incorporates some model dynamics of thunderstorms, including nonthermodynamic forcing. The energy shear index is found to improve prediction of tornadic and high-wind situations slightly better than other indices. It is concluded that further development and refinement of nonthermodynamic aspects of predictive indices are definitely warranted.

  15. Predicting three types of dissociation in female survivors of intimate partner violence.

    PubMed

    Fleming, C J Eubanks; Resick, Patricia A

    2016-01-01

    Previous research suggests that studying the effect of dissociation is particularly important in survivors of intimate partner violence because of the risk of revictimization. The current study investigated demographic variables, child and current abuse characteristics, coping style, and cognitive distortions as predictors of peritraumatic, trait, and posttraumatic stress disorder (PTSD)-related dissociation in a sample of female intimate partner violence survivors. The sample consisted of 372 women, the majority African American, with an average age of 34.41 years (SD = 8.09). Peritraumatic dissociation was significantly predicted by child physical abuse, current abuse injury, cognitive distortions about safety, and problem disengagement coping. Trait dissociation was significantly predicted by minority race, personal income, and cognitive distortions about safety and self-worth. PTSD-related dissociation was significantly predicted by cognitive distortions about self-worth, problem and emotion disengagement coping, and peritraumatic dissociation. In the models predicting both trait and PTSD-related dissociation, abuse characteristics significantly predicted dissociation until the entry of cognitive variables into the model. The analysis indicated a significant indirect effect of cognitive distortions on the relationship between current sexual aggression and trait dissociation. Results also suggested that there were indirect effects of both cognitive distortions and peritraumatic dissociation on the relationships between current psychological abuse/injury and PTSD-related dissociation. Findings point to the importance of cognitions in the development and maintenance of dissociation and suggest that treatments designed to help clients accept and process traumatic events may help reduce dissociation and in turn prevent future revictimization. PMID:26274868

  16. Case history of FAA/SRI wind shear models

    NASA Technical Reports Server (NTRS)

    Schlickenmaier, Herbert

    1987-01-01

    In order to understand the development of the FAA/SRI wind fields, it is important to understand the operating philosophy of the FAA's Wind Shear Program Office. The goal of the office was to ensure an integrated solution to the wind shear problem which addressed three area: ground based equipment and coordination; airborne systems and procedures; and weather prediction. This triply addressed goal was central to the development of the wind fields. The primary user of the wind shear modeling during the FAA's program was airborne simulation. The project requirement was to use wind shear models that resulted from accidents so that effective procedures and/or equipment could be found for hazardous wind shear encounters. The wind shear model development is discussed in detail.

  17. Plasma Triglycerides Predict Incident Albuminuria and Progression of Coronary Artery Calcification in Adults with Type 1 Diabetes: the Coronary Artery Calcification in Type 1 Diabetes Study

    PubMed Central

    Bjornstad, Petter; Maahs, David M.; Wadwa, R. Paul; Pyle, Laura; Rewers, Marian; Eckel, Robert H.; Snell-Bergeon, Janet K.

    2014-01-01

    Background Coronary artery disease and diabetic nephropathy, which are thought to share pathogenic mechanisms, remain the most common causes of mortality in type 1 diabetes (T1D). Data from basic and clinical studies indicate that hypertriglyceridemia plays an important role in the pathogenesis of vascular complications, but the role of triglycerides (TG) in the normal range remains unresolved in T1D. Objective We hypothesized that fasting TG would independently predict cardiorenal disease in adults with T1D and normal-to-low levels of TG. Methods Subjects (N=652) were 19–56 years old at baseline and reexamined 6-years later. Urinary albumin excretion was measured, and categorized as microalbuminuria or greater. Progression of coronary artery calcification (CACp), measured using electron beam CT, was defined as a change in the square root transformed CAC volume ≥2.5. The association of low-density-lipoprotein-C (LDL-C), high-density-lipoprotein-C (HDL-C), apolipoprotein B, nonHDL-C, lnTG, ln(TG/HDL-C) ratio with CACp and incident albuminuria were examined in logistic regression. The models were adjusted for age, sex, T1D-duration, hemoglobin A1c, SBP, DBP, BP-medications, statins and smoking status. Integrated discrimination index and net-reclassification improvement were used to examine prediction performance. Results Incident albuminuria was independently associated with CACp. LnTG independently predicted both incident albuminuria (OR: 1.53, 1.02–2.30, p=0.04) and CACp (1.41, 1.11–1.80, p=0.006). The addition of lnTG to ABC risk factors (HbA1c, SBP, DBP and LDL-C) moderately improved discrimination and reclassification of CACp and incident albuminuria. Conclusion In adults with type 1 diabetes, fasting TG independently predicted cardiorenal disease over 6 years and improved reclassification of risk by conventional risk factors. PMID:25499940

  18. Quantitative prediction of type II solar radio emission from the Sun to 1 AU

    NASA Astrophysics Data System (ADS)

    Schmidt, J. M.; Cairns, Iver H.

    2016-01-01

    Coronal mass ejections (CMEs) are frequently associated with shocks and type II solar radio bursts. Despite involving fundamental plasma physics and being the archetype for collective radio emission from shocks, type II bursts have resisted detailed explanation for over 60 years. Between 29 November and 1 December 2013 the two widely separated spacecraft STEREO A and B observed a long lasting, intermittent, type II radio burst from ≈4 MHz to 30 kHz (harmonic), including an intensification when the CME-driven shock reached STEREO A. We demonstrate the first accurate and quantitative simulation of a type II burst from the high corona (near 11 solar radii) to 1 AU for this event with a combination of a data-driven three-dimensional magnetohydrodynamic simulation for the CME and plasma background and an analytic quantitative kinetic model for the radio emission.

  19. Free volume under shear.

    PubMed

    Maiti, Moumita; Vinutha, H A; Sastry, Srikanth; Heussinger, Claus

    2015-10-14

    Using an athermal quasistatic simulation protocol, we study the distribution of free volumes in sheared hard-particle packings close to, but below, the random-close packing threshold. We show that under shear, and independent of volume fraction, the free volumes develop features similar to close-packed systems - particles self-organize in a manner as to mimick the isotropically jammed state. We compare athermally sheared packings with thermalized packings and show that thermalization leads to an erasure of these structural features. The temporal evolution in particular the opening-up and the closing of free-volume patches is associated with the single-particle dynamics, showing a crossover from ballistic to diffusive behavior. PMID:26472384

  20. Bulk and shear viscosities of partially molten rocks: Experimental approach using analogue material

    NASA Astrophysics Data System (ADS)

    Suzuki, A. M.; Watanabe, S.; Takei, Y.

    2012-12-01

    Deformation of partially molten rock has two types: shear deformation and compaction/decompaction. The former is controlled by shear viscosity, and the latter by bulk viscosity. While shear viscosity has been measured extensively, relatively few experimental studies have investigated bulk viscosity (Renner et al., 2003). Bulk viscosity and its ratio to shear viscosity, ξ/η, play an important role in melt segregation dynamics (Katz, 2008). Most numerical studies has used the theoretically predicted value of ξ/η~φ-1, where φ is the melt fraction. However, Takei and Holtzman (2009) theoretically obtained a value of ξ/η=1.7 by taking into account a diffusion creep mechanism. The discrepancy between two models is significant at small φ. To discuss the validity of these models based on the experimental data, it is highly important to measure both bulk and shear viscosities by using identical samples. In this study, we measured experimentally bulk and shear viscosities as functions of melt fraction using a partially molten rock analogue. Samples were polycrystalline aggregates of borneol-diphenylamine binary with eutectic temperature of 316K, which has a quite similar equilibrium microstructure to olivine + basalt system (Takei, 2000). Initial melt fraction can be controlled precisely by the amount of diphenylamine because of its simple eutectic reaction. Before deformation experiments, samples were annealed at 320K for ~100 hours in a sealed capsule to make those grain size large enough (~30μm), resulted in negligible grain growth during the successive deformation tests at the same temperature. To measure the bulk and shear viscosities, we carried out two separate experiments. For bulk viscosity, we performed compaction experiments in which melt was squeezed from the partially molten sample. A cylindrical sample contacted with porous metals at the top and bottom ends was compacted uniaxially in a rigid sleeve (ɛzz ≠ 0, ɛxx = ɛyy = 0). Melt can flow out

  1. Metal shearing energy absorber

    NASA Technical Reports Server (NTRS)

    Fay, R. J.; Wittrock, E. P. (Inventor)

    1973-01-01

    A metal shearing energy absorber is described. The absorber is composed of a flat thin strip of metal which is pulled through a slot in a cutter member of a metal, harder than the metal of the strip. The slot's length, in the direction perpendicular to the pull direction, is less than the strip's width so that as the strip is pulled through the slot, its edges are sheared off, thereby absorbing some of the pulling energy. In one embodiment the cutter member is a flat plate of steel, while in another embodiment the cutter member is U-shaped with the slot at its base.

  2. Ultrasonic shear wave couplant

    DOEpatents

    Kupperman, D.S.; Lanham, R.N.

    1984-04-11

    Ultrasonically testing of an article at high temperatures is accomplished by the use of a compact layer of a dry ceramic powder as a couplant in a method which involves providing an ultrasonic transducer as a probe capable of transmitting shear waves, coupling the probe to the article through a thin compact layer of a dry ceramic powder, propagating a shear wave from the probe through the ceramic powder and into the article to develop echo signals, and analyzing the echo signals to determine at least one physical characteristic of the article.

  3. Ultrasonic shear wave couplant

    DOEpatents

    Kupperman, David S.; Lanham, Ronald N.

    1985-01-01

    Ultrasonically testing of an article at high temperatures is accomplished by the use of a compact layer of a dry ceramic powder as a couplant in a method which involves providing an ultrasonic transducer as a probe capable of transmitting shear waves, coupling the probe to the article through a thin compact layer of a dry ceramic powder, propagating a shear wave from the probe through the ceramic powder and into the article to develop echo signals, and analyzing the echo signals to determine at least one physical characteristic of the article.

  4. Infrared lateral shearing interferometers

    NASA Astrophysics Data System (ADS)

    Kwon, O.

    1980-04-01

    Recently IR interferometry has received much attention for its special capabilities of testing IR materials, diamond-turned metal mirrors, deep aspherics, unpolished rough surface optics, and other unconventional optics. A CW CO2 laser is used as a coherent light source at 10.6 microns, and germanium and zinc selenide optics are used for lenses and beam splitters. A pyroelectric vidicon (PEV) detects the modulated interference pattern through a TV monitor and video recorder-player. This paper presents three methods of IR lateral shear interferometry using (1) a germanium plane-parallel plate, (2) a Ronchi ruling, and (3) a double-grating lateral shear interferometer.

  5. Magnetogenesis through Relativistic Velocity Shear

    NASA Astrophysics Data System (ADS)

    Miller, Evan

    Magnetic fields at all scales are prevalent in our universe. However, current cosmological models predict that initially the universe was bereft of large-scale fields. Standard magnetohydrodynamics (MHD) does not permit magnetogenesis; in the MHD Faraday's law, the change in magnetic field B depends on B itself. Thus if B is initially zero, it will remain zero for all time. A more accurate physical model is needed to explain the origins of the galactic-scale magnetic fields observed today. In this thesis, I explore two velocity-driven mechanisms for magnetogenesis in 2-fluid plasma. The first is a novel kinematic 'battery' arising from convection of vorticity. A coupling between thermal and plasma oscillations, this non-relativistic mechanism can operate in flows that are incompressible, quasi-neutral and barotropic. The second mechanism results from inclusion of thermal effects in relativistic shear flow instabilities. In such flows, parallel perturbations are ubiquitously unstable at small scales, with growth rates of order with the plasma frequency over a defined range of parameter-space. Of these two processes, instabilities seem far more likely to account for galactic magnetic fields. Stable kinematic effects will, at best, be comparable to an ideal Biermann battery, which is suspected to be orders of magnitude too weak to produce the observed galactic fields. On the other hand, instabilities grow until saturation is reached, a topic that has yet to be explored in detail on cosmological scales. In addition to investigating these magnetogenesis sources, I derive a general dispersion relation for three dimensional, warm, two species plasma with discontinuous shear flow. The mathematics of relativistic plasma, sheared-flow instability and the Biermann battery are also discussed.

  6. Online elicitation of Mamdani-type fuzzy rules via TSK-based generalized predictive control.

    PubMed

    Mahfouf, M; Abbod, M F; Linkens, D A

    2003-01-01

    Many synergies have been proposed between soft-computing techniques, such as neural networks (NNs), fuzzy logic (FL), and genetic algorithms (GAs), which have shown that such hybrid structures can work well and also add more robustness to the control system design. In this paper, a new control architecture is proposed whereby the on-line generated fuzzy rules relating to the self-organizing fuzzy logic controller (SOFLC) are obtained via integration with the popular generalized predictive control (GPC) algorithm using a Takagi-Sugeno-Kang (TSK)-based controlled autoregressive integrated moving average (CARIMA) model structure. In this approach, GPC replaces the performance index (PI) table which, as an incremental model, is traditionally used to discover, amend, and delete the rules. Because the GPC sequence is computed using predicted future outputs, the new hybrid approach rewards the time-delay very well. The new generic approach, named generalized predictive self-organizing fuzzy logic control (GPSOFLC), is simulated on a well-known nonlinear chemical process, the distillation column, and is shown to produce an effective fuzzy rule-base in both qualitative (minimum number of generated rules) and quantitative (good rules) terms. PMID:18238192

  7. Predicting Type 2 diabetes using an electronic nose-based artificial neural network analysis.

    PubMed

    Mohamed, E I; Linder, R; Perriello, G; Di Daniele, N; Pöppl, S J; De Lorenzo, A

    2002-08-01

    Diabetes is a major health problem in both industrial and developing countries, and its incidence is rising. Although detection of diabetes is improving, about half of the patients with Type 2 diabetes are undiagnosed and the delay from disease onset to diagnosis may exceed 10 yr. Thus, earlier detection of Type 2 diabetes and treatment of hyperglycaemia and related metabolic abnormalities is of vital importance. The objectives of the present study were to examine urine samples from Type 2 diabetic patients and healthy volunteers using the electronic nose technology and to evaluate possible application of data classification methods such as self-learning artificial neural networks (ANN) and logistic regression (LR) in comparison with principal components analysis (PCA). Urine samples from Type 2 diabetic patients and healthy controls were processed randomly using a simple 8-sensors electronic nose and individual electronic nose patterns were qualitatively classified using the "Approximation and Classification of Medical Data" (ACMD) network based on 2 output neurons, binary LR analysis and PCA. Distinct classes were found for Type 2 diabetic subjects and controls using PCA, which had a 96.0% successful classification percentage mean while qualitative ANN analysis and LR analysis had successful classification percentages of 92.0% and 88.0%, respectively. Therefore, the ACMD network is suitable for classifying medical and clinical data. PMID:12416658

  8. Prediction of Type II Toxin-Antitoxin Loci in Klebsiella pneumoniae Genome Sequences.

    PubMed

    Wei, Yi-Qing; Bi, De-Xi; Wei, Dong-Qing; Ou, Hong-Yu

    2016-06-01

    Klebsiella pneumoniae is an increasingly important bacterial pathogen to human. This Gram-negative bacterium species has become a serious concern due to its dramatic increase in the levels of multiple antibiotic resistances, particularly to carbapenems. The toxin-antitoxin (TA) system has recently been reported to be involved in the formation of drug-tolerant persister cells. The type II TA system is composed of a stable toxin protein and a relatively unstable antitoxin protein that is able to inhibit the toxin. Here, we examine the type II TA locus distribution and compare the TA diversity throughout ten completely sequenced K. pneumoniae genomes by using bioinformatics approaches. Two hundred and twelve putative type II TA loci were identified in 30 replicons of these K. pneumoniae strains. The amino acid sequence similarity-based grouping shows that these loci distribute differently not only among different K. pneumoniae strains isolated from diverse sources, but also between their chromosomes and plasmids. PMID:26662948

  9. Heterogeneity of Pre-diabetes and Type 2 Diabetes: Implications for Prediction, Prevention and Treatment Responsiveness.

    PubMed

    Faerch, Kristine; Hulmán, Adam; Solomon, Thomas P J

    2016-01-01

    Type 2 diabetes is a heterogeneous disease with large variation in the relative contributions of insulin resistance and beta cell dysfunction between subgroups and individuals. Some of these differences are reflected in the way people are diagnosed. However, differences in glucose regulation exist among individuals even in those with comparable diagnostic glucose levels. In this review we address the heterogeneity of pre-diabetes and type 2 diabetes with special emphasis on differences in the pathophysiology and treatment responses related to the diagnostic criteria. We also discuss whether novel glycaemic markers of diabetes risk can provide additional information to the established diagnostic criteria. A better understanding of the underlying mechanisms responsible for elevated fasting versus postprandial glucose concentration, as well as knowledge about the expected responsiveness to treatment in individuals with different clinical characteristics at diagnosis, may contribute to optimising strategies for management of hyperglycaemia in both pre-diabetes and type 2 diabetes. PMID:25877695

  10. Drought prediction using a wavelet based approach to model the temporal consequences of different types of droughts

    NASA Astrophysics Data System (ADS)

    Maity, Rajib; Suman, Mayank; Verma, Nitesh Kumar

    2016-08-01

    Droughts are expected to propagate from one type to another - meteorological to agricultural to hydrological to socio-economic. However, they do not possess a universal, straightforward temporal dependence. Rather, assessment of one type of drought (successor) from another (predecessor) is a complex problem depending on the basin's physiographic and climatic characteristics, such as, spatial extent, topography, land use, land cover and climate regime. In this paper, a wavelet decomposition based approach is proposed to model the temporal dependence between different types of droughts. The idea behind is to separate the rapidly and slowly moving components of drought indices. It is shown that the temporal dependence of predecessor (say meteorological drought) on the successor (say hydrological drought) can be better captured at its constituting components level. Such components are obtained through wavelet decomposition retaining its temporal correspondence. Thus, in the proposed approach, predictand drought index is predicted using the decomposed components of predecessor drought. Several alternative models are investigated to arrive at the best possible model structure for predicting different types of drought. The proposed approach is found to be very useful for foreseeing the agricultural or hydrological droughts knowing the meteorological drought status, offering the scope for better management of drought consequences. The mathematical framework of the proposed approach is general in nature and can be applied to different basins. However, the limitation is the requirement of region/catchment specific calibration of some parameters before using the proposed model, which is not very difficult and uncommon though.

  11. Shear wave transmissivity measurement by color Doppler shear wave imaging

    NASA Astrophysics Data System (ADS)

    Yamakoshi, Yoshiki; Yamazaki, Mayuko; Kasahara, Toshihiro; Sunaguchi, Naoki; Yuminaka, Yasushi

    2016-07-01

    Shear wave elastography is a useful method for evaluating tissue stiffness. We have proposed a novel shear wave imaging method (color Doppler shear wave imaging: CD SWI), which utilizes a signal processing unit in ultrasound color flow imaging in order to detect the shear wave wavefront in real time. Shear wave velocity is adopted to characterize tissue stiffness; however, it is difficult to measure tissue stiffness with high spatial resolution because of the artifact produced by shear wave diffraction. Spatial average processing in the image reconstruction method also degrades the spatial resolution. In this paper, we propose a novel measurement method for the shear wave transmissivity of a tissue boundary. Shear wave wavefront maps are acquired by changing the displacement amplitude of the shear wave and the transmissivity of the shear wave, which gives the difference in shear wave velocity between two mediums separated by the boundary, is measured from the ratio of two threshold voltages required to form the shear wave wavefronts in the two mediums. From this method, a high-resolution shear wave amplitude imaging method that reconstructs a tissue boundary is proposed.

  12. Acute Shear Stress Direction Dictates Adherent Cell Remodeling and Verifies Shear Profile of Spinning Disc Assays

    PubMed Central

    Fuhrmann, Alexander; Engler, Adam J.

    2015-01-01

    Several methods have been developed to quantify population level changes in cell attachment strength given its large heterogeneity. One such method is the rotating disc chamber or “spinning disc” in which a range of shear forces are applied to attached cells to quantify detachment force, i.e. attachment strength, which can be heterogeneous within cell populations. However, computing the exact force vectors that act upon cells is complicated by complex flow fields and variable cell morphologies. Recent observations suggest that cells may remodel their morphology and align during acute shear exposure, but contrary to intuition, shear is not orthogonal to the radial direction. Here we theoretically derive the magnitude and direction of applied shear and demonstrate that cells, under certain physiological conditions, align in this direction within minutes. Shear force magnitude is also experimentally verified which validates that for spread cells shear forces and not torque or drag dominate in this assay, and demonstrates that the applied force per cell area is largely independent of initial morphology. These findings suggest that direct quantified comparison of the effects of shear on a wide array of cell types and conditions can be made with confidence using this assay without the need for computational or numerical modeling. PMID:25619322

  13. Using the SMOTE technique and hybrid features to predict the types of ion channel-targeted conotoxins.

    PubMed

    Zhang, Lina; Zhang, Chengjin; Gao, Rui; Yang, Runtao; Song, Qing

    2016-08-21

    Conotoxins targeting different ion channels play distinct physiological functions and therapeutic potentials in organisms. Accurate identification of types of ion channel-targeted conotoxins will provide significant clues to reveal the physiological mechanism and pharmacological therapeutic potential of conotoxins. In this study, a random forest based predictor called ICTCPred for the types of ion channel-targeted conotoxin prediction is proposed with hybrid features incorporating CTD (Composition, Transition, and Distribution), g-Gap DC (g-Gap Dipeptide Composition), PP (Physicochemical Properties), and SSI (Secondary Structure Information). To deal with the imbalanced benchmark dataset, the SMOTE Technique (Synthetic Minority Over-sampling Technique) is applied. Based on the above-mentioned individual feature spaces, the average accuracy of ICTCPred lies in the range of 0.729-0.886, indicating the discriminative power of these features. In addition, ICTCPred yields the highest average accuracy of 0.895 using the hybrid feature space of CTD, g-Gap DC, PP and SSI. The Relief-IFS (Incremental Feature Selection) method is adopted to further improve the prediction performance of ICTCPred. Based on the training dataset, ICTCPred achieves satisfactory performance with an average accuracy of 0.910. To evaluate the prediction performance objectively, ICTCPred is compared with previous studies on the same independent testing dataset. Encouragingly, our proposed method performs better than previous studies to identify types of ion channel-targeted conotoxins, with the highest sensitivity of 0.919 for Na(+)-targeted conotoxins, the highest sensitivity of 1 for K(+)-targeted conotoxins, and the highest sensitivity of 1 for Ca(2+)-targeted conotoxins. It is anticipated that ICTCPred can be a potential candidate for the ion channel-targeted conotoxin prediction. PMID:27142776

  14. Testing projected wild bee distributions in agricultural habitats: predictive power depends on species traits and habitat type.

    PubMed

    Marshall, Leon; Carvalheiro, Luísa G; Aguirre-Gutiérrez, Jesús; Bos, Merijn; de Groot, G Arjen; Kleijn, David; Potts, Simon G; Reemer, Menno; Roberts, Stuart; Scheper, Jeroen; Biesmeijer, Jacobus C

    2015-10-01

    Species distribution models (SDM) are increasingly used to understand the factors that regulate variation in biodiversity patterns and to help plan conservation strategies. However, these models are rarely validated with independently collected data and it is unclear whether SDM performance is maintained across distinct habitats and for species with different functional traits. Highly mobile species, such as bees, can be particularly challenging to model. Here, we use independent sets of occurrence data collected systematically in several agricultural habitats to test how the predictive performance of SDMs for wild bee species depends on species traits, habitat type, and sampling technique. We used a species distribution modeling approach parametrized for the Netherlands, with presence records from 1990 to 2010 for 193 Dutch wild bees. For each species, we built a Maxent model based on 13 climate and landscape variables. We tested the predictive performance of the SDMs with independent datasets collected from orchards and arable fields across the Netherlands from 2010 to 2013, using transect surveys or pan traps. Model predictive performance depended on species traits and habitat type. Occurrence of bee species specialized in habitat and diet was better predicted than generalist bees. Predictions of habitat suitability were also more precise for habitats that are temporally more stable (orchards) than for habitats that suffer regular alterations (arable), particularly for small, solitary bees. As a conservation tool, SDMs are best suited to modeling rarer, specialist species than more generalist and will work best in long-term stable habitats. The variability of complex, short-term habitats is difficult to capture in such models and historical land use generally has low thematic resolution. To improve SDMs' usefulness, models require explanatory variables and collection data that include detailed landscape characteristics, for example, variability of crops and

  15. The Role of Vocabulary Size in Predicting Performance on TOEFL Reading Item Types

    ERIC Educational Resources Information Center

    Alavi, Seyyed Mohammad; Akbarian, Is'haaq

    2012-01-01

    This study aims to examine a) whether vocabulary knowledge, captured in the Vocabulary Levels Test (VLT), is related to the performance on the five types of reading comprehension items tested in TOEFL, i.e., Guessing Vocabulary, Main Idea, Inference, Reference, and Stated Detail; and b) whether EFL learners with different levels of vocabulary…

  16. Cardiovascular Autonomic Dysfunction Predicts Diabetic Foot Ulcers in Patients With Type 2 Diabetes Without Diabetic Polyneuropathy

    PubMed Central

    Yun, Jae-Seung; Cha, Seon-Ah; Lim, Tae-Seok; Lee, Eun-Young; Song, Ki-Ho; Ahn, Yu-Bae; Yoo, Ki-Dong; Kim, Joon-Sung; Park, Yong-Moon; Ko, Seung-Hyun

    2016-01-01

    Abstract We investigated the factors that might influence the development of diabetic foot ulcers (DFUs) in type 2 diabetes patients without diabetic polyneuropathy (DPN). From January 2000 to December 2005, a total of 595 patients who had type 2 diabetes without DPN between the ages of 25 and 75 years, and had no prior history of DFUs were consecutively enrolled in the study. A cardiovascular autonomic function test was performed to diagnose cardiovascular autonomic neuropathy (CAN) using heart rate variability parameters. The median follow-up time was 13.3 years. Among the 449 (75.4%) patients who completed the follow-up evaluation, 22 (4.9%) patients developed new ulcers, and 6 (1.3%) patients underwent the procedure for lower extremity amputations. The patients in the DFUs group had a longer duration of diabetes, higher baseline HbA1c levels, higher rates of nephropathy, and CAN. A Cox hazard regression analysis results revealed that the development of DFUs was significantly associated with the presence of CAN (normal vs definite CAN; HR, 4.45; 95% confidence interval, 1.29–15.33) after adjusting for possible confounding factors. The development of DFUs was independently associated with CAN in patients with type 2 diabetes without DPN. We suggested the importance of CAN as a predictor of DFUs even in the patients without DPN, and the need to pay attention to patients with definite CAN and type 2 diabetes. PMID:27015188

  17. Cell Type Specific Analysis of Human Brain Transcriptome Data to Predict Alterations in Cellular Composition

    PubMed Central

    Xu, Xiaoxiao; Nehorai, Arye; Dougherty, Joseph

    2013-01-01

    The central nervous system (CNS) is composed of hundreds of distinct cell types, each expressing different subsets of genes from the genome. High throughput gene expression analysis of the CNS from patients and controls is a common method to screen for potentially pathological molecular mechanisms of psychiatric disease. One mechanism by which gene expression might be seen to vary across samples would be alterations in the cellular composition of the tissue. While the expressions of gene ‘markers’ for each cell type can provide certain information of cellularity, for many rare cell types markers are not well characterized. Moreover, if only small sets of markers are known, any substantial variation of a marker’s expression pattern due to experiment conditions would result in poor sensitivity and specificity. Here, our proposed method combines prior information from mice cell-specific transcriptome profiling experiments with co-expression network analysis, to select large sets of potential cell type-specific gene markers in a systematic and unbiased manner. The method is efficient and robust, and identifies sufficient markers for further cellularity analysis. We then employ the markers to analytically detect changing cellular composition in human brain. Application of our method to temporal human brain microarray data successfully detects changes in cellularity over time that roughly correspond to known epochs of human brain development. Furthermore, application of our method to human brain samples with the neurodevelopmental disorder of autism supports the interpretation that the changes in astrocytes and neurons might contribute to the disorder. PMID:25340014

  18. Searching algorithm for type IV secretion system effectors 1.0: a tool for predicting type IV effectors and exploring their genomic context.

    PubMed

    Meyer, Damien F; Noroy, Christophe; Moumène, Amal; Raffaele, Sylvain; Albina, Emmanuel; Vachiéry, Nathalie

    2013-11-01

    Type IV effectors (T4Es) are proteins produced by pathogenic bacteria to manipulate host cell gene expression and processes, divert the cell machinery for their own profit and circumvent the immune responses. T4Es have been characterized for some bacteria but many remain to be discovered. To help biologists identify putative T4Es from the complete genome of α- and γ-proteobacteria, we developed a Perl-based command line bioinformatics tool called S4TE (searching algorithm for type-IV secretion system effectors). The tool predicts and ranks T4E candidates by using a combination of 13 sequence characteristics, including homology to known effectors, homology to eukaryotic domains, presence of subcellular localization signals or secretion signals, etc. S4TE software is modular, and specific motif searches are run independently before ultimate combination of the outputs to generate a score and sort the strongest T4Es candidates. The user keeps the possibility to adjust various searching parameters such as the weight of each module, the selection threshold or the input databases. The algorithm also provides a GC% and local gene density analysis, which strengthen the selection of T4E candidates. S4TE is a unique predicting tool for T4Es, finding its utility upstream from experimental biology. PMID:23945940

  19. Prediction of an U2S3-type polymorph of Al2O3 at 3.7 Mbar.

    PubMed

    Umemoto, Koichiro; Wentzcovitch, Renata M

    2008-05-01

    We predict by first principles a phase transition in alumina at approximately 3.7 Mbar and room temperature from the CaIrO(3)-type polymorph to another with the U(2)S(3)-type structure. Because alumina is used as window material in shock-wave experiments, this transformation should be important for the analysis of shock data in this pressure range. Comparison of our results on all high-pressure phases of alumina with shock data suggests the presence of two phase transitions in shock experiments: the corundum to Rh(2)O(3)(II)-type structure and the Rh(2)O(3)(II)-type to CaIrO(3)-type structure. The transformation to the U(2)S(3)-type polymorph is in the pressure range reached in the mantle of recently discovered terrestrial exoplanets and suggests that the multi-megabar crystal chemistry of planet-forming minerals might be related to that of the rare-earth sulfides. PMID:18451030

  20. Prediction of an U2S3-type polymorph of Al2O3 at 3.7 Mbar

    PubMed Central

    Umemoto, Koichiro; Wentzcovitch, Renata M.

    2008-01-01

    We predict by first principles a phase transition in alumina at ≈3.7 Mbar and room temperature from the CaIrO3-type polymorph to another with the U2S3-type structure. Because alumina is used as window material in shock-wave experiments, this transformation should be important for the analysis of shock data in this pressure range. Comparison of our results on all high-pressure phases of alumina with shock data suggests the presence of two phase transitions in shock experiments: the corundum to Rh2O3(II)-type structure and the Rh2O3(II)-type to CaIrO3-type structure. The transformation to the U2S3-type polymorph is in the pressure range reached in the mantle of recently discovered terrestrial exoplanets and suggests that the multi-megabar crystal chemistry of planet-forming minerals might be related to that of the rare-earth sulfides. PMID:18451030

  1. Sheared Electroconvective Instability

    NASA Astrophysics Data System (ADS)

    Kwak, Rhokyun; Pham, Van Sang; Lim, Kiang Meng; Han, Jongyoon

    2012-11-01

    Recently, ion concentration polarization (ICP) and related phenomena draw attention from physicists, due to its importance in understanding electrochemical systems. Researchers have been actively studying, but the complexity of this multiscale, multiphysics phenomenon has been limitation for gaining a detailed picture. Here, we consider electroconvective(EC) instability initiated by ICP under pressure-driven flow, a scenario often found in electrochemical desalinations. Combining scaling analysis, experiment, and numerical modeling, we reveal unique behaviors of sheared EC: unidirectional vortex structures, its size selection and vortex propagation. Selected by balancing the external pressure gradient and the electric body force, which generates Hagen-Poiseuille(HP) flow and vortical EC, the dimensionless EC thickness scales as (φ2 /UHP)1/3. The pressure-driven flow(or shear) suppresses unfavorably-directed vortices, and simultaneously pushes favorably-directed vortices with constant speed, which is linearly proportional to the total shear of HP flow. This is the first systematic characterization of sheared EC, which has significant implications on the optimization of electrodialysis and other electrochemical systems.

  2. A Refined Shear Deformation Plate Theory

    NASA Astrophysics Data System (ADS)

    Liu, Yucheng

    2011-04-01

    An improved higher-order shear deformation theory of plates is presented in this paper. The theory is developed from the transverse shear deformation theory presented by Ambartsumian [11]. The present plate theory contains kinematics of higher-order displacement field of plates, a system of higher-order differential equilibrium equations in terms of the three generalized displacements of bending plates, and a system of boundary conditions at each edge of plate boundaries. The present shear deformation theory of plates is validated by applying it to solve torsional plates and simply supported plates. The obtained solutions using the present theory are compared with the solutions of other shear-deformation theories. A good agreement is achieved through these comparisons and the advantages of the present theory are clearly verified. The shear deformation plate theory presented here can be applied to the analysis of laminated composite plates to better predict their dynamic and static behaviors. The proposed theory should also be supplemented to the theory of finite element analysis for developing new shell elements.

  3. Evaluation of shear mounted elastomeric damper

    NASA Technical Reports Server (NTRS)

    Zorzi, E.; Walton, J.

    1982-01-01

    Viton-70 elastomeric shear mounted damper was built and tested on a T-55 power turbine spool in the rotor's high speed balancing rig. This application of a shear mounted elastomeric damper demonstrated for the first time, the feasibility of using elastomers as the primary rotor damping source in production turbine engine hardware. The shear damper design was selected because it was compatible with actual gas turbine engine radial space constraints, could accommodate both the radial and axial thrust loads present in gas turbine engines, and was capable of controlled axial preload. The shear damper was interchangeable with the production T-55 power turbine roller bearing support so that a direct comparison between the shear damper and the production support structure could be made. Test results show that the Viton-70 elastomer damper operated successfully and provided excellent control of both synchronous and nonsynchronous vibrations through all phases of testing up to the maximum rotor speed of 16,000 rpm. Excellent correlation between the predicted and experienced critical speeds, mode shapes and log decrements for the power turbine rotor and elastomer damper assembly was also achieved.

  4. History of wind shear turbulence models

    NASA Technical Reports Server (NTRS)

    Cusimano, Lou

    1987-01-01

    The Office of Flight Operations, Flight Technical Programs Div., at the FAA Headquarters, interfaces with industry, R&D communities and air carriers during the introduction of new types of equipment into operational services. A brief highlight of the need which FAA operations sees for new wind shear and turbulence data sets from the viewpoint of equipment certification and simulation is presented.

  5. BOUNDARY SHEAR STRESS ALONG VEGETATED STREAMBANKS

    EPA Science Inventory

    This research is intended to improve our understanding of the role of riparian vegetation in stream morphology by evaluating the effects of vegetation on boundary shear stress, providing insight to the type and density of vegetation required for streambank stability. The resu...

  6. Prediction of Foreign Object Debris/Damage (FOD) type for elimination in the aeronautics manufacturing environment through logistic regression model

    NASA Astrophysics Data System (ADS)

    Espino, Natalia V.

    Foreign Object Debris/Damage (FOD) is a costly and high-risk problem that aeronautics industries such as Boeing, Lockheed Martin, among others are facing at their production lines every day. They spend an average of $350 thousand dollars per year fixing FOD problems. FOD can put pilots, passengers and other crews' lives into high-risk. FOD refers to any type of foreign object, particle, debris or agent in the manufacturing environment, which could contaminate/damage the product or otherwise undermine quality control standards. FOD can be in the form of any of the following categories: panstock, manufacturing debris, tools/shop aids, consumables and trash. Although aeronautics industries have put many prevention plans in place such as housekeeping and "clean as you go" philosophies, trainings, use of RFID for tooling control, etc. none of them has been able to completely eradicate the problem. This research presents a logistic regression statistical model approach to predict probability of FOD type under given specific circumstances such as workstation, month and aircraft/jet being built. FOD Quality Assurance Reports of the last three years were provided by an aeronautical industry for this study. By predicting type of FOD, custom reduction/elimination plans can be put in place and by such means being able to diminish the problem. Different aircrafts were analyzed and so different models developed through same methodology. Results of the study presented are predictions of FOD type for each aircraft and workstation throughout the year, which were obtained by applying proposed logistic regression models. This research would help aeronautic industries to address the FOD problem correctly, to be able to identify root causes and establish actual reduction/elimination plans.

  7. Ngram time series model to predict activity type and energy cost from wrist, hip and ankle accelerometers: implications of age

    PubMed Central

    Strath, Scott J; Kate, Rohit J; Keenan, Kevin G; Welch, Whitney A; Swartz, Ann M

    2016-01-01

    To develop and test time series single site and multi-site placement models, we used wrist, hip and ankle processed accelerometer data to estimate energy cost and type of physical activity in adults. Ninety-nine subjects in three age groups (18–39, 40–64, 65 + years) performed 11 activities while wearing three triaxial accelereometers: one each on the non-dominant wrist, hip, and ankle. During each activity net oxygen cost (METs) was assessed. The time series of accelerometer signals were represented in terms of uniformly discretized values called bins. Support Vector Machine was used for activity classification with bins and every pair of bins used as features. Bagged decision tree regression was used for net metabolic cost prediction. To evaluate model performance we employed the jackknife leave-one-out cross validation method. Single accelerometer and multi-accelerometer site model estimates across and within age group revealed similar accuracy, with a bias range of −0.03 to 0.01 METs, bias percent of −0.8 to 0.3%, and a rMSE range of 0.81–1.04 METs. Multi-site accelerometer location models improved activity type classification over single site location models from a low of 69.3% to a maximum of 92.8% accuracy. For each accelerometer site location model, or combined site location model, percent accuracy classification decreased as a function of age group, or when young age groups models were generalized to older age groups. Specific age group models on average performed better than when all age groups were combined. A time series computation show promising results for predicting energy cost and activity type. Differences in prediction across age group, a lack of generalizability across age groups, and that age group specific models perform better than when all ages are combined needs to be considered as analytic calibration procedures to detect energy cost and type are further developed. PMID:26449155

  8. Ngram time series model to predict activity type and energy cost from wrist, hip and ankle accelerometers: implications of age.

    PubMed

    Strath, Scott J; Kate, Rohit J; Keenan, Kevin G; Welch, Whitney A; Swartz, Ann M

    2015-11-01

    To develop and test time series single site and multi-site placement models, we used wrist, hip and ankle processed accelerometer data to estimate energy cost and type of physical activity in adults. Ninety-nine subjects in three age groups (18-39, 40-64, 65 +  years) performed 11 activities while wearing three triaxial accelereometers: one each on the non-dominant wrist, hip, and ankle. During each activity net oxygen cost (METs) was assessed. The time series of accelerometer signals were represented in terms of uniformly discretized values called bins. Support Vector Machine was used for activity classification with bins and every pair of bins used as features. Bagged decision tree regression was used for net metabolic cost prediction. To evaluate model performance we employed the jackknife leave-one-out cross validation method. Single accelerometer and multi-accelerometer site model estimates across and within age group revealed similar accuracy, with a bias range of -0.03 to 0.01 METs, bias percent of -0.8 to 0.3%, and a rMSE range of 0.81-1.04 METs. Multi-site accelerometer location models improved activity type classification over single site location models from a low of 69.3% to a maximum of 92.8% accuracy. For each accelerometer site location model, or combined site location model, percent accuracy classification decreased as a function of age group, or when young age groups models were generalized to older age groups. Specific age group models on average performed better than when all age groups were combined. A time series computation show promising results for predicting energy cost and activity type. Differences in prediction across age group, a lack of generalizability across age groups, and that age group specific models perform better than when all ages are combined needs to be considered as analytic calibration procedures to detect energy cost and type are further developed. PMID:26449155

  9. Measuring the reduced shear

    SciTech Connect

    Zhang, Jun

    2011-11-01

    Neglecting the second order corrections in weak lensing measurements can lead to a few percent uncertainties on cosmic shears, and becomes more important for cluster lensing mass reconstructions. Existing methods which claim to measure the reduced shears are not necessarily accurate to the second order when a point spread function (PSF) is present. We show that the method of Zhang (2008) exactly measures the reduced shears at the second order level in the presence of PSF. A simple theorem is provided for further confirming our calculation, and for judging the accuracy of any shear measurement method at the second order based on its properties at the first order. The method of Zhang (2008) is well defined mathematically. It does not require assumptions on the morphologies of galaxies and the PSF. To reach a sub-percent level accuracy, the CCD pixel size is required to be not larger than 1/3 of the Full Width at Half Maximum (FWHM) of the PSF, regardless of whether the PSF has a power-law or exponential profile at large distances. Using a large ensemble (∼>10{sup 7}) of mock galaxies of unrestricted morphologies, we study the shear recovery accuracy under different noise conditions. We find that contaminations to the shear signals from the noise of background photons can be removed in a well defined way because they are not correlated with the source shapes. The residual shear measurement errors due to background noise are consistent with zero at the sub-percent level even when the amplitude of such noise reaches about 1/10 of the source flux within the half-light radius of the source. This limit can in principle be extended further with a larger galaxy ensemble in our simulations. On the other hand, the source Poisson noise remains to be a cause of systematic errors. For a sub-percent level accuracy, our method requires the amplitude of the source Poisson noise to be less than 1/80 ∼ 1/100 of the source flux within the half-light radius of the source

  10. Response of wind shear warning systems to turbulence with implication of nuisance alerts

    NASA Technical Reports Server (NTRS)

    Bowles, Roland L.

    1988-01-01

    The objective was to predict the inherent turbulence response characteristics of candidate wind shear warning system concepts and to assess the potential for nuisance alerts. Information on the detection system and associated signal processing, physical and mathematical models, wind shear factor root mean square turbulence response and the standard deviation of the wind shear factor due to turbulence is given in vugraph form.

  11. Predicting fish community properties within estuaries: Influence of habitat type and other environmental features

    NASA Astrophysics Data System (ADS)

    França, Susana; Vasconcelos, Rita P.; Fonseca, Vanessa F.; Tanner, Susanne E.; Reis-Santos, Patrick; Costa, Maria José; Cabral, Henrique N.

    2012-07-01

    Statistical models predicting species distributions are essential not only to increase knowledge on species but for their application in conservation and ecologically-based management. The variation of fish species richness and abundance in the most representative habitats (saltmarsh, mudflat and subtidal) in five estuaries along the Portuguese coast was analysed through seasonal sampling surveys in 2009. Generalized additive models (GAM) were developed to describe the variation of species richness and abundances with a set of geomorphologic, hydrologic and environmental characteristics from the sampled estuaries and habitats. GAM were chosen as the complex interactions dominating these ecosystems and species distribution are non-linear. Final models built for each estuary and for all estuaries together performed well during the calibration phase and also during the validation phase, where an unused data sub-set from each estuary was used. There was not a similar combination of variables retained by the models for the studied estuaries but factors such as the area of the habitat, the distance to estuary mouth, percentage of mud in the sediment and depth were commonly retained. The partial effect of these predictor variables on the variation of species richness and abundance in the estuaries varied markedly and the importance of preserving the heterogeneity of habitats within estuaries was highlighted. Models for each individual estuary performed better than models for estuaries combined. Predictive models could be useful as a preliminary tool to prepare long-term conservation plans at different scales.

  12. Prediction of Lung Cancer Histological Types by RT-qPCR Gene Expression in FFPE Specimens

    PubMed Central

    Wilkerson, Matthew D.; Schallheim, Jason M.; Hayes, D. Neil; Roberts, Patrick J.; Bastien, Roy R.L.; Mullins, Michael; Yin, Xiaoying; Miller, C. Ryan; Thorne, Leigh B.; Geiersbach, Katherine B.; Muldrew, Kenneth L.; Funkhouser, William K.; Fan, Cheng; Hayward, Michele C.; Bayer, Steven; Perou, Charles M.; Bernard, Philip S.

    2014-01-01

    Lung cancer histologic diagnosis is clinically relevant because there are histology-specific treatment indications and contraindications. Histologic diagnosis can be challenging owing to tumor characteristics, and it has been shown to have less-than-ideal agreement among pathologists reviewing the same specimens. Microarray profiling studies using frozen specimens have shown that histologies exhibit different gene expression trends; however, frozen specimens are not amenable to routine clinical application. Herein, we developed a gene expression–based predictor of lung cancer histology for FFPE specimens, which are routinely available in clinical settings. Genes predictive of lung cancer histologies were derived from published cohorts that had been profiled by microarrays. Expression of these genes was measured by quantitative RT-PCR (RT-qPCR) in a cohort of patients with FFPE lung cancer. A histology expression predictor (HEP) was developed using RT-qPCR expression data for adenocarcinoma, carcinoid, small cell carcinoma, and squamous cell carcinoma. In cross-validation, the HEP exhibited mean accuracy of 84% and κ = 0.77. In separate independent validation sets, the HEP was compared with pathologist diagnoses on the same tumor block specimens, and the HEP yielded similar accuracy and precision as the pathologists. The HEP also exhibited good performance in specimens with low tumor cellularity. Therefore, RT-qPCR gene expression from FFPE specimens can be effectively used to predict lung cancer histology. PMID:23701907

  13. The relative influence of soil moisture and SST in climate predictability explored within ensembles of AMIP type experiments

    NASA Astrophysics Data System (ADS)

    Conil, S.; Douville, H.; Tyteca, S.

    2007-02-01

    Three ensembles of AMIP-type simulations using the Arpege-climat coupled land atmosphere model have been designed to assess the relative influence of SST and soil moisture (SM) on climate variability and predictability. The study takes advantage of the GSWP2 land surface reanalysis covering the 1986 1995 period. The GSWP2 forcings have been used to derive a global SM climatology that is fully consistent with the model used in this study. One ensemble of ten simulations has been forced by climatological SST and the simulated SM is relaxed toward the GSWP2 reanalysis. Another ensemble has been forced by observed SST and SM is evolving freely. The last ensemble combines the observed SST forcing and the relaxation toward GSWP2. Two complementary aspects of the predictability have been explored, the potential predictability (analysis of variance) and the effective predictability (skill score). An analysis of variance has revealed the effects of the SST and SM boundary forcings on the variability and potential predictability of near-surface temperature, precipitation and surface evaporation. While in the tropics SST anomalies clearly maintain a potentially predictable variability throughout the annual cycle, in the mid-latitudes the SST forced variability is only dominant in winter and SM plays a leading role in summer. In a similar fashion, the annual cycle of the hindcast skill (evaluated as the anomalous correlation coefficient of the three ensemble means with respect to the “observations”) indicates that the SST forcing is the dominant contributor over the tropical continents and in the winter mid-latitudes but that SM is supporting a significant part of the skill in the summer mid-latitudes. Focusing on boreal summer, we have then investigated different aspects of the SM and SST contribution to climate variations in terms of spatial distribution and time-evolution. Our experiments suggest that SM is potentially an additional source of climate predictability. A

  14. Bistability of Cell Adhesion in Shear Flow

    PubMed Central

    Efremov, Artem; Cao, Jianshu

    2011-01-01

    Cell adhesion plays a central role in multicellular organisms helping to maintain their integrity and homeostasis. This complex process involves many different types of adhesion proteins, and synergetic behavior of these proteins during cell adhesion is frequently observed in experiments. A well-known example is the cooperation of rolling and stationary adhesion proteins during the leukocytes extravasation. Despite the fact that such cooperation is vital for proper functioning of the immune system, its origin is not fully understood. In this study we constructed a simple analytic model of the interaction between a leukocyte and the blood vessel wall in shear flow. The model predicts existence of cell adhesion bistability, which results from a tug-of-war between two kinetic processes taking place in the cell-wall contact area—bond formation and rupture. Based on the model results, we suggest an interpretation of several cytoadhesion experiments and propose a simple explanation of the existing synergy between rolling and stationary adhesion proteins, which is vital for effective cell adherence to the blood vessel walls in living organisms. PMID:21889439

  15. Epigenetic age predictions based on buccal swabs are more precise in combination with cell type-specific DNA methylation signatures.

    PubMed

    Eipel, Monika; Mayer, Felix; Arent, Tanja; Ferreira, Marcelo R P; Birkhofer, Carina; Gerstenmaier, Uwe; Costa, Ivan G; Ritz-Timme, Stefanie; Wagner, Wolfgang

    2016-05-01

    Aging is reflected by highly reproducible DNA methylation (DNAm) changes that open new perspectives for estimation of chronological age in legal medicine. DNA can be harvested non-invasively from cells at the inside of a person's cheek using buccal swabs - but these specimens resemble heterogeneous mixtures of buccal epithelial cells and leukocytes with different epigenetic makeup. In this study, we have trained an age predictor based on three age-associated CpG sites (associated with the genesPDE4C, ASPA, and ITGA2B) for swab samples to reach a mean absolute deviation (MAD) between predicted and chronological age of 4.3 years in a training set and of 7.03 years in a validation set. Subsequently, the composition of buccal epithelial cells versus leukocytes was estimated by two additional CpGs (associated with the genes CD6 and SERPINB5). Results of this "Buccal-Cell-Signature" correlated with cell counts in cytological stains (R2 = 0.94). Combination of cell type-specific and age-associated CpGs into one multivariate model enabled age predictions with MADs of 5.09 years and 5.12 years in two independent validation sets. Our results demonstrate that the cellular composition in buccal swab samples can be determined by DNAm at two cell type-specific CpGs to improve epigenetic age predictions. PMID:27249102

  16. Epigenetic age predictions based on buccal swabs are more precise in combination with cell type-specific DNA methylation signatures

    PubMed Central

    Eipel, Monika; Mayer, Felix; Arent, Tanja; Ferreira, Marcelo R. P.; Birkhofer, Carina; Gerstenmaier, Uwe; Costa, Ivan G.; Ritz-Timme, Stefanie; Wagner, Wolfgang

    2016-01-01

    Aging is reflected by highly reproducible DNA methylation (DNAm) changes that open new perspectives for estimation of chronological age in legal medicine. DNA can be harvested non-invasively from cells at the inside of a person's cheek using buccal swabs – but these specimens resemble heterogeneous mixtures of buccal epithelial cells and leukocytes with different epigenetic makeup. In this study, we have trained an age predictor based on three age-associated CpG sites (associated with the genes PDE4C, ASPA, and ITGA2B) for swab samples to reach a mean absolute deviation (MAD) between predicted and chronological age of 4.3 years in a training set and of 7.03 years in a validation set. Subsequently, the composition of buccal epithelial cells versus leukocytes was estimated by two additional CpGs (associated with the genes CD6 and SERPINB5). Results of this “Buccal-Cell-Signature” correlated with cell counts in cytological stains (R2 = 0.94). Combination of cell type-specific and age-associated CpGs into one multivariate model enabled age predictions with MADs of 5.09 years and 5.12 years in two independent validation sets. Our results demonstrate that the cellular composition in buccal swab samples can be determined by DNAm at two cell type-specific CpGs to improve epigenetic age predictions. PMID:27249102

  17. Prediction of auto-ignition temperatures of hydrocarbons by neural network based on atom-type electrotopological-state indices.

    PubMed

    Pan, Yong; Jiang, Juncheng; Wang, Rui; Cao, Hongyin; Zhao, Jinbo

    2008-09-15

    A quantitative structure-property relationship (QSPR) model was constructed to predict the auto-ignition temperature (AIT) of 118 hydrocarbons by means of artificial neural network (ANN). Atom-type electrotopological-state indices were used as molecular structure descriptors which combined together both electronic and topological characteristics of the analyzed molecules. The typical back-propagation (BP) neural network was employed for fitting the possible non-linear relationship existed between the atom-type electrotopological-state indices and AIT. The dataset of 118 hydrocarbons was randomly divided into a training set (60), a validation set (16) and a testing set (42). The optimal condition of the neural network was obtained by adjusting various parameters by trial-and-error. Simulated with the final optimum BP neural network [16-8-1], the results show that most of the predicted AIT values are in good agreement with the experimental data, with the average absolute error being 21.6 degrees C, and the root mean square error (RMS) being 31.09 for the testing set, which are superior to those obtained by multiple linear regression analysis and traditional group contribution method. The model proposed can be used not only to reveal the quantitative relation between AIT and molecular structures of hydrocarbons, but also to predict the AIT values of hydrocarbons for chemical engineering. PMID:18280036

  18. Influences of word predictability and type of masker noise on intelligibility of sung text in live concerts.

    PubMed

    Heinrich, Antje; Knight, Sarah; Hawkins, Sarah

    2015-10-01

    Vocal music is often intended to convey meaning, but how effectively this is achieved is poorly understood. This study systematically assessed the influence of three non-phonetic factors on the intelligibility of sung words in six public concerts in different venues: word predictability from sentence context, type of masker noise (spoken babble, sung vowels, [∫(w)]), and signal-to-noise ratio (SNR). Stimuli were sung live by a professional a cappella ensemble with one male singing target sentences and five others (two female) producing the masker sounds. The concert audiences (N = 319) reported the final word of each sentence using a handheld voting device, from four phonetically- and semantically-controlled written alternatives projected onto a screen after the sentence was sung. Although overall accuracy differed between performances, intelligibility patterns were robust across concerts. They included predicted main effects of masker noise type ([∫(w)] masking least disruptive, babble most), SNR (high > low), semantic predictability (high > low), listener age (young > old), and listener language status (native > non-native), and some strong interactions. These results suggest that, despite acoustic differences between sung and spoken words and the unusual and varied experimental venues, key findings from traditional speech research apply to sung words, given appropriate musical composition. PMID:26520319

  19. Human nephrotoxicity prediction models for three types of kidney injury based on data sets of pharmacological compounds and their metabolites.

    PubMed

    Lee, Sehan; Kang, Young-Mook; Park, Hyejin; Dong, Mi-Sook; Shin, Jae-Min; No, Kyoung Tai

    2013-11-18

    The kidney is the most important organ for the excretion of pharmaceuticals and their metabolites. Among the complex structures of the kidney, the proximal tubule and renal interstitium are major targets of nephrotoxins. Despite its importance, there are only a few in silico models for predicting human nephrotoxicity for drug candidates. Here, we present quantitative structure-activity relationship (QSAR) models for three common patterns of drug-induced kidney injury, i.e., tubular necrosis, interstitial nephritis, and tubulo-interstitial nephritis. A support vector machine (SVM) was used to build the binary classification models of nephrotoxin versus non-nephrotoxin with eight fingerprint descriptors. To build the models, we constructed two types of data sets, i.e., parent compounds of pharmaceuticals (251 nephrotoxins and 387 non-nephrotoxins) and their major urinary metabolites (307 nephrotoxins and 233 non-nephrotoxins). Information on the nephrotoxicity of the pharmaceuticals was taken from clinical trial and postmarketing safety data. Though the mechanisms of nephrotoxicity are very complex, by using the metabolite information, the predictive accuracies of the best models for each type of kidney injury were better than 83% for external validation sets. Software to predict nephrotoxicity is freely available from our Web site at http://bmdrc.org/DemoDownload . PMID:24138086

  20. Analysis and prediction of lightning strike distributions associated with synoptic map types over Florida

    SciTech Connect

    Reap, R.M.

    1994-08-01

    The temporal and spatial distributions of lightning activity associated with specific synoptic regimes of low-level wind flow were analyzed as part of an experiment to develop improved statistical thunderstorm forecasts for Florida. The synoptic regimes were identified by means of a linear correlation technique that was used to perform pattern classification or `map typing` of 18- and 30-h sea level pressure forecasts from the National Meteorological Center`s Nested Grid Model (NGM). Lightning location data for the 1987-90 warm seasons were subsequently analyzed on a 12-km grid to determine the thunderstorm distribution for each of the predetermined map types. The analysis revealed organized coastal maxima in lightning activity related to land-sea-breeze convergence zones that form in direct response to the low-level wind flow. Surface effects were also indicated by the persistent minima in lightning activity over Lake Okeechobee and by the lightning maxima found in regions with shoreline curvature favoring localized convergence. Experimental thunderstorm probability equations for Florida were subsequently developed from climatological lightning frequencies and NGM forecast fields. The lightning frequencies were combined with the K stability index to form interactive predictors that take into account the temporal and spatial variations in lightning occurrence for each map type but modulate the climatology in response to the daily large-scale synoptic situation. The statistical forecast equations were developed for each map type in an attempt to simulate the effects of small-scale processes, such as land-sea-breeze convergence zones, on the subsequent development of peninsular-scale convection.

  1. PREDICTING THE DETECTABILITY OF OSCILLATIONS IN SOLAR-TYPE STARS OBSERVED BY KEPLER

    SciTech Connect

    Chaplin, W. J.; Elsworth, Y.; Verner, G. A.; Kjeldsen, H.; Christensen-Dalsgaard, J.; Karoff, C.; Bedding, T. R.; Gilliland, R. L.; Kawaler, S. D.; Appourchaux, T.; Garcia, R. A.; Metcalfe, T. S.; Thompson, M. J.; Molenda-Zakowicz, J.; Monteiro, M. J. P. F. G.; Batalha, N.; Borucki, W. J.; Bryson, S. T.; Brown, T. M.

    2011-05-01

    Asteroseismology of solar-type stars has an important part to play in the exoplanet program of the NASA Kepler Mission. Precise and accurate inferences on the stellar properties that are made possible by the seismic data allow very tight constraints to be placed on the exoplanetary systems. Here, we outline how to make an estimate of the detectability of solar-like oscillations in any given Kepler target, using rough estimates of the temperature and radius, and the Kepler apparent magnitude.

  2. ABC goal achievement predicts microvascular but not macrovascular complications over 6-years in adults with type 1 diabetes: the Coronary Artery Calcification in Type 1 Diabetes Study

    PubMed Central

    Bjornstad, Petter; Maahs, David M.; Rewers, Marian; Johnson, Richard J.; Snell-Bergeon, Janet K.

    2014-01-01

    Hypothesis Vascular complications of type 1 diabetes are thought to cluster. We examined the prevalence and incidence of vascular complications and American Diabetes Association’s ABC goal achievements in a prospective cohort of adults with type 1 diabetes. We hypothesized that ABC achievement at baseline would predict both micro- and macrovascular complications over 6-years. Methods Participants (N=652) were 19–56 year old at baseline and re-examined 6-years later. Microvascular complications included diabetic nephropathy (DN), defined as incident albuminuria (AER≥20μg/min) or rapid GFR decline (>3.3%/year) by CKD-EPI cystatin C and proliferative diabetic retinopathy (PDR), defined as laser eye-therapy. Macrovascular complications were defined as coronary artery calcium progression (CACp), measured by electron-beam computed-tomography. ABC goals were defined as HbA1c<7.0%, BP<130/80 mmHg, LDL-C<100mg/dL. Results ABC control was suboptimal with only 6% meeting all goals. Meeting no ABC goals at baseline compared to meeting all goals was associated with increased odds of developing microvascular complications (OR: 8.5, 2.3–31.5, p=0.001), but did not reach significance for CACp (OR: 1.7, 0.8–3.9, p=0.19). Conclusion ABC achievement at baseline strongly predicted microvascular but not macrovascular complications over 6-years in adults with type 1 diabetes, suggesting a need for novel therapeutic targets to complement conventional risk factors in treating macrovascular complications. PMID:25270733

  3. Prediction of the age at onset in spinocerebellar ataxia type 1, 2, 3 and 6

    PubMed Central

    Tezenas du Montcel, Sophie; Durr, Alexandra; Rakowicz, Maria; Nanetti, Lorenzo; Charles, Perrine; Sulek, Anna; Mariotti, Caterina; Rola, Rafal; Schols, Ludger; Bauer, Peter; Dufaure-Garé, Isabelle; Jacobi, Heike; Forlani, Sylvie; Schmitz-Hübsch, Tanja; Filla, Alessandro; Timmann, Dagmar; van de Warrenburg, Bart P; Marelli, Cecila; Kang, Jun-Suk; Giunti, Paola; Cook, Arron; Baliko, Laszlo; Bela, Melegh; Boesch, Sylvia; Szymanski, Sandra; Berciano, José; Infante, Jon; Buerk, Katrin; Masciullo, Marcella; Di Fabio, Roberto; Depondt, Chantal; Ratka, Susanne; Stevanin, Giovanni; Klockgether, Thomas; Brice, Alexis; Golmard, Jean-Louis

    2014-01-01

    Background The most common spinocerebellar ataxias (SCA)—SCA1, SCA2, SCA3, and SCA6—are caused by (CAG)n repeat expansion. While the number of repeats of the coding (CAG)n expansions is correlated with the age at onset, there are no appropriate models that include both affected and preclinical carriers allowing for the prediction of age at onset. Methods We combined data from two major European cohorts of SCA1, SCA2, SCA3, and SCA6 mutation carriers: 1187 affected individuals from the EUROSCA registry and 123 preclinical individuals from the RISCA cohort. For each SCA genotype, a regression model was fitted using a log-normal distribution for age at onset with the repeat length of the alleles as covariates. From these models, we calculated expected age at onset from birth and conditionally that this age is greater than the current age. Results For SCA2 and SCA3 genotypes, the expanded allele was a significant predictor of age at onset (−0.105±0.005 and −0.056±0.003) while for SCA1 and SCA6 genotypes both the size of the expanded and normal alleles were significant (expanded: −0.049±0.002 and −0.090±0.009, respectively; normal: +0.013±0.005 and −0.029±0.010, respectively). According to the model, we indicated the median values (90% critical region) and the expectancy (SD) of the predicted age at onset for each SCA genotype according to the CAG repeat size and current age. Conclusions These estimations can be valuable in clinical and research. However, results need to be confirmed in other independent cohorts and in future longitudinal studies. ClinicalTrials.gov, number NCT01037777 and NCT00136630 for the French patients. PMID:24780882

  4. Predicting Absolute Risk of Type 2 Diabetes Using Age and Waist Circumference Values in an Aboriginal Australian Community

    PubMed Central

    2015-01-01

    Objectives To predict in an Australian Aboriginal community, the 10-year absolute risk of type 2 diabetes associated with waist circumference and age on baseline examination. Method A sample of 803 diabetes-free adults (82.3% of the age-eligible population) from baseline data of participants collected from 1992 to 1998 were followed-up for up to 20 years till 2012. The Cox-proportional hazard model was used to estimate the effects of waist circumference and other risk factors, including age, smoking and alcohol consumption status, of males and females on prediction of type 2 diabetes, identified through subsequent hospitalisation data during the follow-up period. The Weibull regression model was used to calculate the absolute risk estimates of type 2 diabetes with waist circumference and age as predictors. Results Of 803 participants, 110 were recorded as having developed type 2 diabetes, in subsequent hospitalizations over a follow-up of 12633.4 person-years. Waist circumference was strongly associated with subsequent diagnosis of type 2 diabetes with P<0.0001 for both genders and remained statistically significant after adjusting for confounding factors. Hazard ratios of type 2 diabetes associated with 1 standard deviation increase in waist circumference were 1.7 (95%CI 1.3 to 2.2) for males and 2.1 (95%CI 1.7 to 2.6) for females. At 45 years of age with baseline waist circumference of 100 cm, a male had an absolute diabetic risk of 10.9%, while a female had a 14.3% risk of the disease. Conclusions The constructed model predicts the 10-year absolute diabetes risk in an Aboriginal Australian community. It is simple and easily understood and will help identify individuals at risk of diabetes in relation to waist circumference values. Our findings on the relationship between waist circumference and diabetes on gender will be useful for clinical consultation, public health education and establishing WC cut-off points for Aboriginal Australians. PMID:25876058

  5. Chronic weight dissatisfaction predicts type 2 diabetes risk: Aerobic Center Longitudinal Study

    PubMed Central

    Wirth, Michael; Blake, Christine E.; Hébert, James R.; Sui, Xuemei; Blair, Steven N

    2014-01-01

    Objective Weight dissatisfaction, defined as discordance between actual and goal weight, may be associated with increased risk for several obesity-related comorbidities. The purpose of the study was to examine the association between weight dissatisfaction and risk of developing type 2 diabetes. Methods This longitudinal study used data from 9,584 adults enrolled in the Aerobics Center Longitudinal Study with an average of 5.1±4.1 years of follow-up. Key variables included multiple measures of measured weight, self-reported goal weight, and incident diabetes. Weight dissatisfaction was defined as being above the median of measured weight minus goal weight. Cox proportional hazards regression estimated hazard ratios (HR) and 95% confidence intervals (95%CI) for diabetes incidence by weight dissatisfaction. Results HRs for time-until-diabetes diagnosis revealed that family history of diabetes (HR=1.46, 95%CI=1.13-1.90), age (HR=1.03, 95%CI=1.02-1.04), and weight dissatisfaction (HR=1.83, 95%CI=1.50-2.25) at baseline were statistically significant predictors. Longitudinally, higher risk was observed in individuals who either stayed dissatisfied (HR=2.98, 95%CI=1.98-4.48) or became dissatisfied (HR=1.51, 95%CI=0.79-2.89), compared to those who either stayed satisfied (HR=1.00, referent) or became satisfied (HR=0.98, 95%CI=0.46-2.10). After additional adjustment for BMI, the elevated HR for those who remained dissatisfied compared to those who remained satisfied persisted (HR=2.85, 95%CI=1.89-4.31). Conclusions Chronic weight dissatisfaction increased type 2 diabetes risk. Weight dissatisfaction, regardless of BMI, represents a potentially important psychophysiological modifier of the relationships between BMI and risk of type 2 diabetes and warrants greater attention in future studies of chronic disease risk. PMID:24588630

  6. Prediction of free-volume-type correlations in glassy chalcogenides from positron annihilation lifetime measurements

    NASA Astrophysics Data System (ADS)

    Shpotyuk, O.; Ingram, A.; Shpotyuk, M.; Filipecki, J.

    2014-11-01

    A newly modified correlation equation between defect-related positron lifetime determined within two-state trapping model and radius of corresponding free-volume-type defects was proposed to describe compositional variations in atomic-deficient structure of covalent-bonded chalcogenides like binary As-S/Se glasses. Specific chemical environment of free-volume voids around neighboring network-forming polyhedrons was shown to play a decisive role in this correlation, leading to systematically enhanced volumes in comparison with typical molecular substrates, such as polymers.

  7. Predicting factors of hypoglycaemia in elderly type 2 diabetes patients: Contributions of the GERODIAB study.

    PubMed

    Bordier, L; Buysschaert, M; Bauduceau, B; Doucet, J; Verny, C; Lassmann Vague, V; Le Floch, J P

    2015-09-01

    The burden of hypoglycaemia is important, particularly in elderly type 2 diabetes (T2D) patients. Unfortunately, however, few studies are available concerning this population. GERODIAB is a prospective, multicentre, observational study that aims to describe the 5-year morbidity and mortality of 987 T2D patients aged 70 years and older. After analyzing the frequency of and factors associated with hypoglycaemia in the 6 months prior to study inclusion, it was found that hypoglycaemia was associated with retinopathy, lower levels of LDL cholesterol and altered mini-Geriatric Depression Scale (GDS) scores. PMID:25845279

  8. Prediction of clinical outcomes using B-type natriuretic peptides in the general population: a systematic review.

    PubMed

    Don-Wauchope, Andrew C; Santaguida, Pasqualina L; McKelvie, Robert; Brown, Judy A; Oremus, Mark; Ali, Usman; Bustamam, Amy; Sohel, Nazmul; Hill, Stephen A; Booth, Ronald A; Balion, Cynthia; Raina, Parminder

    2014-08-01

    The use of B-type natriuretic peptides to predict outcomes in general populations has been investigated in a number of primary studies. A previous systematic review considering natriuretic peptides in cardiovascular disease included a subgroup of general population studies, which suggested an association with a number of clinical outcomes. We electronically searched Medline, Embase, AMED, Cochrane Central Register of Controlled Trials, Cochrane Database of Systematic Reviews, and CINAHL for English-language articles published between 1989 and mid-2012. We utilized trained reviewers and standardized forms to screen articles for inclusion and extract data from included articles. All included studies (n = 7) were summarized in narrative and tabular form. A general population was defined as one that was randomly selected from a community setting where no specific inclusion or exclusion criteria were specified. The seven included studies all used FDA approved assays for NT-proBNP. The range of clinical outcomes and heterogeneity did not allow for meta-analysis. The hazard ratios for predicting outcomes in the included studies ranged from 1.0 to 4.1 (all p values <0.05). The discrimination statistics reported in four studies all demonstrated statistically significant improvements in predicting outcomes. NT-proBNP is associated with heart failure, all-cause and cardiovascular mortality, and other combined cardiovascular events in a general unselected population. The discrimination statistics suggest modest improvements in risk stratification. No prospective studies exist to demonstrate the clinical utility of using B-type natriuretic peptides to predict clinical outcomes in a general population. PMID:25052419

  9. Novel Urinary Protein Biomarkers Predicting the Development of Microalbuminuria and Renal Function Decline in Type 1 Diabetes

    PubMed Central

    Schlatzer, Daniela; Maahs, David M.; Chance, Mark R.; Dazard, Jean-Eudes; Li, Xiaolin; Hazlett, Fred; Rewers, Marian; Snell-Bergeon, Janet K.

    2012-01-01

    OBJECTIVE To define a panel of novel protein biomarkers of renal disease. RESEARCH DESIGN AND METHODS Adults with type 1 diabetes in the Coronary Artery Calcification in Type 1 Diabetes study who were initially free of renal complications (n = 465) were followed for development of micro- or macroalbuminuria (MA) and early renal function decline (ERFD, annual decline in estimated glomerular filtration rate of ≥3.3%). The label-free proteomic discovery phase was conducted in 13 patients who progressed to MA by the 6-year visit and 11 control subjects, and four proteins (Tamm-Horsfall glycoprotein, α-1 acid glycoprotein, clusterin, and progranulin) identified in the discovery phase were measured by enzyme-linked immunosorbent assay in 74 subjects: group A, normal renal function (n = 35); group B, ERFD without MA (n = 15); group C, MA without ERFD (n = 16); and group D, both ERFD and MA (n = 8). RESULTS In the label-free analysis, a model of progression to MA was built using 252 peptides, yielding an area under the curve (AUC) of 84.7 ± 5.3%. In the validation study, ordinal logistic regression was used to predict development of ERFD, MA, or both. A panel including Tamm-Horsfall glycoprotein (odds ratio 2.9, 95% CI 1.3–6.2, P = 0.008), progranulin (1.9, 0.8–4.5, P = 0.16), clusterin (0.6, 0.3–1.1, P = 0.09), and α-1 acid glycoprotein (1.6, 0.7–3.7, P = 0.27) improved the AUC from 0.841 to 0.889. CONCLUSIONS A panel of four novel protein biomarkers predicted early renal damage in type 1 diabetes. These findings require further validation in other populations for prediction of renal complications and treatment monitoring. PMID:22238279

  10. Cardiovascular disease and type 1 diabetes: prevalence, prediction and management in an ageing population.

    PubMed

    Lee, Siang Ing; Patel, Mitesh; Jones, Christopher M; Narendran, Parth

    2015-11-01

    Cardiovascular disease (CVD) is a major cause of mortality in type 1 diabetes mellitus (T1D). However, evidence of its risks and management is often extrapolated from studies in type 2 diabetic (T2D) patients or the general population. This approach is unsatisfactory given that the underlying pathology, demographics and natural history of the disease differ between T1D and T2D. Furthermore, with a rising life expectancy, a greater number of T1D patients are exposed to the cardiovascular (CV) risk factors associated with an ageing population. The aim of this review is to examine the existing literature around CVD in T1D. We pay particular attention to CVD prevalence, how well we manage risk, potential biomarkers, and whether the studies included the older aged patients (defined as aged over 65). We also discuss approaches to the management of CV risk in the older aged. The available data suggest a significant CVD burden in patients with T1D and poor management of CV risk factors. This is underpinned by a poor evidence base for therapeutic management of CV risk specifically for patients with T1D, and in the most relevant population - the older aged patients. We would suggest that important areas remain to be addressed, particularly exploring the risks and benefits of therapeutic approaches to CVD management in the older aged. PMID:26568811

  11. Cardiovascular disease and type 1 diabetes: prevalence, prediction and management in an ageing population

    PubMed Central

    Lee, Siang Ing; Patel, Mitesh; Jones, Christopher M.; Narendran, Parth

    2015-01-01

    Cardiovascular disease (CVD) is a major cause of mortality in type 1 diabetes mellitus (T1D). However, evidence of its risks and management is often extrapolated from studies in type 2 diabetic (T2D) patients or the general population. This approach is unsatisfactory given that the underlying pathology, demographics and natural history of the disease differ between T1D and T2D. Furthermore, with a rising life expectancy, a greater number of T1D patients are exposed to the cardiovascular (CV) risk factors associated with an ageing population. The aim of this review is to examine the existing literature around CVD in T1D. We pay particular attention to CVD prevalence, how well we manage risk, potential biomarkers, and whether the studies included the older aged patients (defined as aged over 65). We also discuss approaches to the management of CV risk in the older aged. The available data suggest a significant CVD burden in patients with T1D and poor management of CV risk factors. This is underpinned by a poor evidence base for therapeutic management of CV risk specifically for patients with T1D, and in the most relevant population – the older aged patients. We would suggest that important areas remain to be addressed, particularly exploring the risks and benefits of therapeutic approaches to CVD management in the older aged. PMID:26568811

  12. Prediction of optimal peptide mixtures to induce broadly neutralizing antibodies to human immunodeficiency virus type 1.

    PubMed Central

    Holley, L H; Goudsmit, J; Karplus, M

    1991-01-01

    Sequences of the principal neutralizing determinant (PND) of the external envelope protein, gp120, from 245 isolates of human immunodeficiency virus type 1 are analyzed. The minimal set of peptides that would elicit antibodies to neutralize a majority of U.S. and European isolates of human immunodeficiency virus type 1 is determined with the assumption that peptides of a given length including the central Gly-Pro-Gly triad are required. In spite of the hypervariability of the PND, 90% of these 245 sequences include peptides from a set of 7 pentapeptides, 13 hexapeptides, or 17 heptapeptides. Tests of these peptide sets on 78 additional PND sequences show that 95% are covered by the 7 pentapeptides, 94% by the 13 hexapeptides, and 86% by the 17 heptapeptides. To anticipate variants not yet observed, single amino acid mutation frequencies from the 245 isolates are used to calculate an expanded set of the 10,000 most probable PND sequences. These sequences cover 86% of the total distribution expected for the central portion of the PND. Peptide lists derived from this expanded set when tested on the 78 additional sequences show that 7 pentapeptides cover 95%, 13 hexapeptides cover 94%, and 17 heptapeptides cover 94%. These results suggest that peptide cocktails of limited size with the potential to cover a large fraction of PND sequence variation may be feasible vaccine candidates. PMID:1862103

  13. Influence of Accelerometer Type and Placement on Physical Activity Energy Expenditure Prediction in Manual Wheelchair Users

    PubMed Central

    Nightingale, Tom Edward; Walhin, Jean-Philippe; Thompson, Dylan; Bilzon, James Lee John

    2015-01-01

    Purpose To assess the validity of two accelerometer devices, at two different anatomical locations, for the prediction of physical activity energy expenditure (PAEE) in manual wheelchair users (MWUs). Methods Seventeen MWUs (36 ± 10 yrs, 72 ± 11 kg) completed ten activities; resting, folding clothes, propulsion on a 1% gradient (3,4,5,6 and 7 km·hr-1) and propulsion at 4km·hr-1 (with an additional 8% body mass, 2% and 3% gradient) on a motorised wheelchair treadmill. GT3X+ and GENEActiv accelerometers were worn on the right wrist (W) and upper arm (UA). Linear regression analysis was conducted between outputs from each accelerometer and criterion PAEE, measured using indirect calorimetry. Subsequent error statistics were calculated for the derived regression equations for all four device/location combinations, using a leave-one-out cross-validation analysis. Results Accelerometer outputs at each anatomical location were significantly (p < .01) associated with PAEE (GT3X+-UA; r = 0.68 and GT3X+-W; r = 0.82. GENEActiv-UA; r = 0.87 and GENEActiv-W; r = 0.88). Mean ± SD PAEE estimation errors for all activities combined were 15 ± 45%, 14 ± 50%, 3 ± 25% and 4 ± 26% for GT3X+-UA, GT3X+-W, GENEActiv-UA and GENEActiv-W, respectively. Absolute PAEE estimation errors for devices varied, 19 to 66% for GT3X+-UA, 17 to 122% for GT3X+-W, 15 to 26% for GENEActiv-UA and from 17.0 to 32% for the GENEActiv-W. Conclusion The results indicate that the GENEActiv device worn on either the upper arm or wrist provides the most valid prediction of PAEE in MWUs. Variation in error statistics between the two devices is a result of inherent differences in internal components, on-board filtering processes and outputs of each device. PMID:25955304

  14. Repeated buckling of composite shear panels

    NASA Technical Reports Server (NTRS)

    Singer, Josef; Weller, Tanchum

    1990-01-01

    Failures in service of aerospace structures and research at the Technion Aircraft Structures Laboratory have revealed that repeatedly buckled stiffened shear panels might be susceptible to premature fatigue failures. Extensive experimental and analytical studies have been performed at Technion on repeated buckling, far in excess of initial buckling, for both metal and composite shear panels with focus on the influence of the surrounding structure. The core of the experimental investigation consisted of repeated buckling and postbuckling tests on Wagner beams in a three-point loading system under realistic test conditions. The effects of varying sizes of stiffeners, of the magnitude of initial buckling loads, of the panel aspect ratio and of the cyclic shearing force, V sub cyc, were studied. The cyclic to critical shear buckling ratios, (V sub cyc/V sub cr) were on the high side, as needed for efficient panel design, yet all within possible flight envelopes. The experiments were supplemented by analytical and numerical analyses. For the metal shear panels the test and numerical results were synthesized into prediction formulas, which relate the life of the metal shear panels to two cyclic load parameters. The composite shear panels studied were hybrid beams with graphite/epoxy webs bonded to aluminum alloy frames. The test results demonstrated that composite panels were less fatigue sensitive than comparable metal ones, and that repeated buckling, even when causing extensive damage, did not reduce the residual strength by more than 20 percent. All the composite panels sustained the specified fatigue life of 250,000 cycles. The effect of local unstiffened holes on the durability of repeatedly buckled shear panels was studied for one series of the metal panels. Tests on 2024 T3 aluminum panels with relatively small unstiffened holes in the center of the panels demonstrated premature fatigue failure, compared to panels without holes. Preliminary tests on two graphite

  15. Development of Risk Score for Predicting 3-Year Incidence of Type 2 Diabetes: Japan Epidemiology Collaboration on Occupational Health Study

    PubMed Central

    Nanri, Akiko; Nakagawa, Tohru; Kuwahara, Keisuke; Yamamoto, Shuichiro; Honda, Toru; Okazaki, Hiroko; Uehara, Akihiko; Yamamoto, Makoto; Miyamoto, Toshiaki; Kochi, Takeshi; Eguchi, Masafumi; Murakami, Taizo; Shimizu, Chii; Shimizu, Makiko; Tomita, Kentaro; Nagahama, Satsue; Imai, Teppei; Nishihara, Akiko; Sasaki, Naoko; Hori, Ai; Sakamoto, Nobuaki; Nishiura, Chihiro; Totsuzaki, Takafumi; Kato, Noritada; Fukasawa, Kenji; Huanhuan, Hu; Akter, Shamima; Kurotani, Kayo; Kabe, Isamu; Mizoue, Tetsuya; Sone, Tomofumi; Dohi, Seitaro

    2015-01-01

    Objective Risk models and scores have been developed to predict incidence of type 2 diabetes in Western populations, but their performance may differ when applied to non-Western populations. We developed and validated a risk score for predicting 3-year incidence of type 2 diabetes in a Japanese population. Methods Participants were 37,416 men and women, aged 30 or older, who received periodic health checkup in 2008–2009 in eight companies. Diabetes was defined as fasting plasma glucose (FPG) ≥126 mg/dl, random plasma glucose ≥200 mg/dl, glycated hemoglobin (HbA1c) ≥6.5%, or receiving medical treatment for diabetes. Risk scores on non-invasive and invasive models including FPG and HbA1c were developed using logistic regression in a derivation cohort and validated in the remaining cohort. Results The area under the curve (AUC) for the non-invasive model including age, sex, body mass index, waist circumference, hypertension, and smoking status was 0.717 (95% CI, 0.703–0.731). In the invasive model in which both FPG and HbA1c were added to the non-invasive model, AUC was increased to 0.893 (95% CI, 0.883–0.902). When the risk scores were applied to the validation cohort, AUCs (95% CI) for the non-invasive and invasive model were 0.734 (0.715–0.753) and 0.882 (0.868–0.895), respectively. Participants with a non-invasive score of ≥15 and invasive score of ≥19 were projected to have >20% and >50% risk, respectively, of developing type 2 diabetes within 3 years. Conclusions The simple risk score of the non-invasive model might be useful for predicting incident type 2 diabetes, and its predictive performance may be markedly improved by incorporating FPG and HbA1c. PMID:26558900

  16. Colloidal Aggregate Structure under Shear by USANS

    NASA Astrophysics Data System (ADS)

    Chatterjee, Tirtha; van Dyk, Antony K.; Ginzburg, Valeriy V.; Nakatani, Alan I.

    2015-03-01

    Paints are complex formulations of polymeric binders, inorganic pigments, dispersants, surfactants, colorants, rheology modifiers, and other additives. A commercially successful paint exhibits a desired viscosity profile over a wide shear rate range from 10-5 s-1 for settling to >104 s-1 for rolling, and spray applications. Understanding paint formulation structure is critical as it governs the paint viscosity profile. However, probing paint formulation structure under shear is a challenging task due to the formulation complexity containing structures with different hierarchical length scales and their alterations under the influence of an external flow field. In this work mesoscale structures of paint formulations under shear are investigated using Ultra Small-Angle Neutron Scattering (rheo-USANS). Contrast match conditions were utilized to independently probe the structure of latex binder particle aggregates and the TiO2 pigment particle aggregates. Rheo-USANS data revealed that the aggregates are fractal in nature and their self-similarity dimensions and correlations lengths depend on the chemistry of the binder particles, the type of rheology modifier present and the shear stress imposed upon the formulation. These results can be explained in the framework of diffusion and reaction limited transient aggregates structure evolution under simple shear.

  17. Sheath fold morphology in simple shear

    NASA Astrophysics Data System (ADS)

    Reber, Jacqueline E.; Dabrowski, Marcin; Galland, Olivier; Schmid, Daniel W.

    2013-08-01

    Sheath folds are highly non-cylindrical structures often associated with shear zones. We investigate the formation of sheath folds around a weak inclusion acting as a slip surface in simple shear by means of an analytical model. We present results for different slip surface orientations and shapes. Cross-sections perpendicular to the shear direction through the sheath fold display closed contours, so called eye-structures. The aspect ratio of the outermost closed contour is strongly dependent on the initial slip surface configuration. The center of the eye-structure is subject to change in height with respect to the upper edge of the outermost closed contour for different cross-sections perpendicular to the shear direction. This results in a large variability in layer thickness across the sheath fold length, questioning the usefulness of eye-structures as shear sense indicators. The location of the center of the eye structure is largely invariant to the initial configurations of the slip surface as well as to strain. The values of the aspect ratios of the closed contours within the eye-pattern are dependent on the strain and the cross-section location. The ratio (R') of the aspect ratios of the outermost closed contour (Ryz) and the innermost closed contour (Ry'z') shows values above and below 1. R' shows dependence on the slip surface shape and orientation but not on the number of involved contours. Using R' measurements to deduce the bulk strain type may be erroneous.

  18. Shear-enhanced adhesion of Pseudomonas aeruginosa

    NASA Astrophysics Data System (ADS)

    Lecuyer, Sigolene; Rusconi, Roberto; Shen, Yi; Forsyth, Alison; Stone, Howard

    2010-03-01

    Bacterial adhesion is the first step in the development of surface-associated communities known as biofilms, which are the cause of many problems in medical devices and industrial water systems. However the underlying mechanisms of initial bacterial attachment are not fully understood. We have investigated the effects of hydrodynamics on the probability of adsorption and detachment of Pseudomonas aeruginosa strain PA14 on model surfaces under flow, in straight microfluidic channels, and measured the distribution of bacteria residence time as a function of the shear rate. Our main discovery is a counter-intuitive enhanced adhesion as the shear stress is increased over a wide range of shear rates. In order to identify the origin of this phenomenon, we have performed experiments with several mutant strains. Our results show that shear-enhanced adhesion is not regulated by primary surface organelles, and that this process is not specific to a certain type of surface, but rather appears a general feature of the adhesive behavior of P. aeruginosa. These results suggest that shear-induced adhesion could be a very widespread strategy in nature.

  19. Relationship of quartz LPO fabrics in mylonites near the Alpine Fault, New Zealand to the attitude of the shear zone boundary

    NASA Astrophysics Data System (ADS)

    Little, T. A.; Prior, D. J.; Toy, V.

    2015-12-01

    The active Alpine fault self-exhumes its own ductile shear zone roots and has known kinematics. Within ~1 km of the fault, the foliation is subparallel to the shear zone boundary in which it formed at amphibolite-facies conditions. Using EBSD, we analysed quartz Lattice Preferred Orientations (LPOs) of mylonites along a central part of the fault. The samples were mostly taken from naturally outcropping rocks, complemented by a few sections from core from the DFDP-2B hole—rocks that accommodated a range of finite strains and that have diverse quartz contents. All the LPOs feature a single (or strongest) girdle of c-axes hat is inclined ~28 ±4° away from the pole to the shear zone boundary (SZB) in a sense that is synthetic to the bulk shear. A point maximum of a-axes is inclined at the same angle relative to the shearing direction. This girdle is perpendicular to C' extensional shear bands in the rock, not to the bulk shear zone boundary, whereas the maximum is parallel to the slip direction of the shear bands. These relationships prevail across large variations in quartz content and finite shear strain magnitude. We infer that quartz LPOs are not always reliable indicators of SZB attitude, and they do not necessarily undergo an obvious rotation relative to the SZB as a function of increasing finite strain. Both the C' shears and the LPOs formed as late-incremental features at orientations controlled by the instantaneous geometry of a non-simple shear flow. We suggest that that the C' planes were aligned to planes of maximum shear-strain-rate. The data can be explained by flow in a thinning and stretching shear zone that deforms in plane strain at a Wk of ~0.7 to ~0.85. In support of this, inversions of seismic focal mechanism data yield an orientation of σ1 for the brittle crust of the central Southern Alps "natural laboratory" that approximately coincides with the predicted orientation of the contractional instantaneous stretching axis for the above

  20. CAT LIDAR wind shear studies

    NASA Technical Reports Server (NTRS)

    Goff, R. W.

    1978-01-01

    The studies considered the major meteorological factors producing wind shear, methods to define and classify wind shear in terms significant from an aircraft perturbation standpoint, the significance of sensor location and scan geometry on the detection and measurement of wind shear, and the tradeoffs involved in sensor performance such as range/velocity resolution, update frequency and data averaging interval.

  1. Combining Information from Common Type 2 Diabetes Risk Polymorphisms Improves Disease Prediction

    PubMed Central

    Weedon, Michael N; McCarthy, Mark I; Hitman, Graham; Walker, Mark; Groves, Christopher J; Zeggini, Eleftheria; Rayner, N. William; Shields, Beverley; Owen, Katharine R; Hattersley, Andrew T; Frayling, Timothy M

    2006-01-01

    Background A limited number of studies have assessed the risk of common diseases when combining information from several predisposing polymorphisms. In most cases, individual polymorphisms only moderately increase risk (~20%), and they are thought to be unhelpful in assessing individuals' risk clinically. The value of analyzing multiple alleles simultaneously is not well studied. This is often because, for any given disease, very few common risk alleles have been confirmed. Methods and Findings Three common variants (Lys23 of KCNJ11, Pro12 of PPARG, and the T allele at rs7903146 of TCF7L2) have been shown to predispose to type 2 diabetes mellitus across many large studies. Risk allele frequencies ranged from 0.30 to 0.88 in controls. To assess the combined effect of multiple susceptibility alleles, we genotyped these variants in a large case-control study (3,668 controls versus 2,409 cases). Individual allele odds ratios (ORs) ranged from 1.14 (95% confidence interval [CI], 1.05 to 1.23) to 1.48 (95% CI, 1.36 to 1.60). We found no evidence of gene-gene interaction, and the risks of multiple alleles were consistent with a multiplicative model. Each additional risk allele increased the odds of type 2 diabetes by 1.28 (95% CI, 1.21 to 1.35) times. Participants with all six risk alleles had an OR of 5.71 (95% CI, 1.15 to 28.3) compared to those with no risk alleles. The 8.1% of participants that were double-homozygous for the risk alleles at TCF7L2 and Pro12Ala had an OR of 3.16 (95% CI, 2.22 to 4.50), compared to 4.3% with no TCF7L2 risk alleles and either no or one Glu23Lys or Pro12Ala risk alleles. Conclusions Combining information from several known common risk polymorphisms allows the identification of population subgroups with markedly differing risks of developing type 2 diabetes compared to those obtained using single polymorphisms. This approach may have a role in future preventative measures for common, polygenic diseases. PMID:17020404

  2. A Risk Prediction Model Based on Lymph-Node Metastasis in Poorly Differentiated–Type Intramucosal Gastric Cancer

    PubMed Central

    Pyo, Jeung Hui; Lee, Hyuk; Min, Byung-Hoon; Lee, Jun Haeng; Choi, Min Gew; Lee, Jun Ho; Sohn, Tae Sung; Bae, Jae Moon; Kim, Kyoung-Mee; Ahn, Hyeon Seon; Jung, Sin-Ho; Kim, Sung; Kim, Jae J.

    2016-01-01

    Background and Aim Endoscopic submucosal dissection (ESD) for undifferentiated type early gastric cancer is regarded as an investigational treatment. Few studies have tried to identify the risk factors that predict lymph-node metastasis (LNM) in intramucosal poorly differentiated adenocarcinomas (PDC). This study was designed to develop a risk scoring system (RSS) for predicting LNM in intramucosal PDC. Methods From January 2002 to July 2015, patients diagnosed with mucosa-confined PDC, among those who underwent curative gastrectomy with lymph node dissection were reviewed. A risk model based on independent predicting factors of LNM was developed, and its performance was internally validated using a split sample approach. Results Overall, LNM was observed in 5.2% (61) of 1169 patients. Four risk factors [Female sex, tumor size ≥ 3.2 cm, muscularis mucosa (M3) invasion, and lymphatic-vascular involvement] were significantly associated with LNM, which were incorporated into the RSS. The area under the receiver operating characteristic curve for predicting LNM after internal validation was 0.69 [95% confidence interval (CI), 0.59–0.79]. A total score of 2 points corresponded to the optimal RSS threshold with a discrimination of 0.75 (95% CI 0.69–0.81). The LNM rates were 1.6% for low risk (<2 points) and 8.9% for high-risk (≥2 points) patients, with a negative predictive value of 98.6% (95% CI 0.98–1.00). Conclusions A RSS could be useful in clinical practice to determine which patients with intramucosal PDC have low risk of LNM. PMID:27228258

  3. Using synoptic weather types to predict visitor attendance at Atlanta and Indianapolis zoological parks

    NASA Astrophysics Data System (ADS)

    Perkins, David R.

    2016-02-01

    Defining an ideal "tourism climate" has been an often-visited research topic where explanations have evolved from global- to location-specific indices tailored to tourists' recreational behavior. Unfortunately, as indices become increasingly specific, they are less translatable across geographies because they may only apply to specific activities, locales, climates, or populations. A key need in the future development of weather and climate indices for tourism has been a translatable, meteorologically based index capturing the generalized ambient atmospheric conditions yet considering local climatology. To address this need, this paper tests the applicability of the spatial synoptic classification (SSC) as a tool to predict visitor attendance response in the tourism, recreation, and leisure (TRL) sector across different climate regimes. Daily attendance data is paired with the prevailing synoptic weather condition at Atlanta and Indianapolis zoological parks from September 2001 to June 2011, to review potential impacts ambient atmospheric conditions may have on visitor attendances. Results indicate that "dry moderate" conditions are most associated with high levels of attendance and "moist polar" synoptic conditions are most associated with low levels of attendance at both zoological parks. Comparing visitor response at these zoo locations, visitors in Indianapolis showed lower levels of tolerance to synoptic conditions which were not "ideal." Visitors in Indianapolis also displayed more aversion to "polar" synoptic regimes while visitors in Atlanta displayed more tolerance to "moist tropical" synoptic regimes. Using a comprehensive atmospheric measure such as the SSC may be a key to broadening application when assessing tourism climates across diverse geographies.

  4. Collagen Type XI Alpha 1 Expression in Intraductal Papillomas Predicts Malignant Recurrence

    PubMed Central

    Freire, Javier; García-Berbel, Lucia; García-Berbel, Pilar; Pereda, Saray; Azueta, Ainara; García-Arranz, Pilar; De Juan, Ana; Vega, Alfonso; Hens, Ángela; Enguita, Ana; Muñoz-Cacho, Pedro; Gómez-Román, Javier

    2015-01-01

    Despite the progress achieved in the treatment of breast cancer, there are still many unsolved clinical issues, being the diagnosis, prognosis, and treatment of papillary diseases, one of the highest challenges. Because of its unpredictable clinical behavior, treatment of intraductal papilloma has generated a great controversy. Even though considered as a benign lesion, it presents high rate of malignant recurrence. This is the reason why there are clinicians supporting a complete excision of the lesion, while others support an only expectant follow-up. Previous results of our group suggested that procollagen 11 alpha 1 (pro-COL11A1) expression correlates with infiltrating phenotype in breast lesions. We analyzed the correlation between expression of pro-COL11A1 in intraductal papilloma and their risk of malignant recurrence. Immunohistochemistry of pro-COL11A1 was performed in 62 samples of intraductal papilloma. Ten out 11 cases relapsed as carcinoma presents positive staining for COL11A1, while just 17 out of 51 cases with benign behaviour present immunostaining. There were significant differences (P < 0.0001) when comparing patients with malignant recurrence versus nonmalignant relapse patients. These data suggest that pro-COL11A1 expression is a highly sensitive biomarker to predict malignant relapse of intraductal papilloma and it can be used as indicative factor for prevention programs. PMID:26448946

  5. Temperature-Dependent Young's modulus, shear modulus and Poisson's ratio of p-type Ce0.9Fe3.5Co0.5Sb12 and n-type Co0.95Pd0.05Te0.05Sb3 Skutterudite Thermoelectric Materials

    SciTech Connect

    Schmidt, Robert; Case, Eldon D; Ni, Jennifer E.; Trejo, Rosa M; Lara-Curzio, Edgar

    2012-01-01

    Effective models of the mechanical behavior of thermoelectric materials under device conditions require knowledge of the temperature-dependent elastic properties.Between room temperature and 600 K, Resonant Ultrasound Spectroscopy (RUS) measurements of the Young s and shear moduli of three skutterudite thermoelectric materials, n-type Co0.95Pd0.05Te0.05Sb3(both with and without 0.1 atomic % cerium dopant) and p-type Ce0.9Fe3.5Co0.5Sb12, decreased linearly with temperature at a rate between -0.011 GPa/K and -0.013 GPa/K. In contrast the Poisson s ratio was approximately 0.22 for the three materials and was relatively insensitive to temperature.For temperatures > 600 K, the elastic moduli decreased more rapidly and resonance peaks broadened indicating the onset of viscoelastic behavior.The viscoelastic relaxation of the moduli was least for Ce-doped n-type material, for which grain boundary precipitates may inhibit grain boundary sliding which in turn has important implications concerning creep resistance. In addition, powder processing of the n- and p-type materials should be done cautiously since submicron-sized powders of both the n- and p-type powders were pyrophoric

  6. Predicting lipase types by improved Chou's pseudo-amino acid composition.

    PubMed

    Zhang, Guang-Ya; Li, Hong-Chun; Gao, Jia-Qiang; Fang, Bai-Shan

    2008-01-01

    By proposing a improved Chou's pseudo amino acid composition approach to extract the features of the sequences, a powerful predictor based on k-nearest neighbor was introduced to identify the types of lipases according to their sequences. To avoid redundancy and bias, demonstrations were performed on a dataset where none of the proteins has > or =25% sequence identity to any other. The overall success rate thus obtained by the 10-fold cross-validation test was over 90%, indicating that the improved Chou's pseudo amino acid composition might be a useful tool for extracting the features of protein sequences, or at lease can play a complementary role to many of the other existing approaches. PMID:19075826

  7. Predicting Gene Function from Uncontrolled Expression Variation among Individual Wild-Type Arabidopsis Plants[W

    PubMed Central

    Bhosale, Rahul; Jewell, Jeremy B.; Hollunder, Jens; Koo, Abraham J.K.; Vuylsteke, Marnik; Michoel, Tom; Hilson, Pierre; Goossens, Alain; Howe, Gregg A.; Browse, John; Maere, Steven

    2013-01-01

    Gene expression profiling studies are usually performed on pooled samples grown under tightly controlled experimental conditions to suppress variability among individuals and increase experimental reproducibility. In addition, to mask unwanted residual effects, the samples are often subjected to relatively harsh treatments that are unrealistic in a natural context. Here, we show that expression variations among individual wild-type Arabidopsis thaliana plants grown under the same macroscopic growth conditions contain as much information on the underlying gene network structure as expression profiles of pooled plant samples under controlled experimental perturbations. We advocate the use of subtle uncontrolled variations in gene expression between individuals to uncover functional links between genes and unravel regulatory influences. As a case study, we use this approach to identify ILL6 as a new regulatory component of the jasmonate response pathway. PMID:23943861

  8. Shear-thinning Fluid

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Whipped cream and the filling for pumpkin pie are two familiar materials that exhibit the shear-thinning effect seen in a range of industrial applications. It is thick enough to stand on its own atop a piece of pie, yet flows readily when pushed through a tube. This demonstrates the shear-thinning effect that was studied with the Critical Viscosity of Xenon Experiment (CVX-2) on the STS-107 Research 1 mission in 2002. CVX observed the behavior of xenon, a heavy inert gas used in flash lamps and ion rocket engines, at its critical point. The principal investigator was Dr. Robert Berg of the National Institutes of Standards and Technology in Gaithersburg, MD.

  9. Gelation under shear

    SciTech Connect

    Butler, B.D.; Hanley, H.J.M.; Straty, G.C.; Muzny, C.D.

    1995-12-31

    An experimental small angle neutron scattering (SANS) study of dense silica gels, prepared from suspensions of 24 nm colloidal silica particles at several volume fractions {theta} is discussed. Provided that {theta}{approx_lt}0.18, the scattered intensity at small wave vectors q increases as the gelation proceeds, and the structure factor S(q, t {yields} {infinity}) of the gel exhibits apparent power law behavior. Power law behavior is also observed, even for samples with {theta}>0.18, when the gel is formed under an applied shear. Shear also enhances the diffraction maximum corresponding to the inter-particle contact distance of the gel. Difficulties encountered when trying to interpret SANS data from these dense systems are outlined. Results of computer simulations intended to mimic gel formation, including computations of S(q, t), are discussed. Comments on a method to extract a fractal dimension characterizing the gel are included.

  10. Micromechanics of shear banding

    SciTech Connect

    Gilman, J.J.

    1992-08-01

    Shear-banding is one of many instabilities observed during the plastic flow of solids. It is a consequence of the dislocation mechanism which makes plastic flow fundamentally inhomogeneous, and is exacerbated by local adiabatic heating. Dislocation lines tend to be clustered on sets of neighboring glide planes because they are heterogeneously generated; especially through the Koehler multiple-cross-glide mechanism. Factors that influence their mobilities also play a role. Strain-hardening decreases the mobilities within shear bands thereby tending to spread (delocalize) them. Strain-softening has the inverse effect. This paper reviews the micro-mechanisms of these phenomena. It will be shown that heat production is also a consequence of the heterogeneous nature of the microscopic flow, and that dislocation dipoles play an important role. They are often not directly observable, but their presence may be inferred from changes in thermal conductivity. It is argued that after deformation at low temperatures dipoles are distributed a la Pareto so there are many more small than large ones. Instability at upper yield point, the shapes of shear-band fronts, and mechanism of heat generation are also considered. It is shown that strain-rate acceleration plays a more important role than strain-rate itself in adiabatic instability.

  11. Biomarkers predicting resistance to epidermal growth factor receptor-targeted therapy in metastatic colorectal cancer with wild-type KRAS

    PubMed Central

    Liu, Jiang; Hu, Jing; Cheng, Lei; Ren, Wei; Yang, Mi; Liu, Baorui; Xie, Li; Qian, Xiaoping

    2016-01-01

    EGFR pathway is an important therapeutic target in human tumors, including metastatic colorectal cancer (mCRC). The advent of EGFR-targeted monoclonal antibodies panitumumab and cetuximab has generated promise for the treatment of mCRC and has largely improved patients’ progression-free survival (PFS) and overall survival (OS). However, treatment with anti-EGFR monoclonal antibodies is only effective in a subset of mCRC patients with wild-type KRAS. This indicates that there are other factors affecting the efficacy of anti-EGFR monoclonal antibodies. Existing studies have demonstrated that among colorectal cancer patients with wild-type KRAS, harboring mutations of BRAF, PIK3CA, NRAS, or PTEN-null may demonstrate resistance to anti-EGFR-targeted therapy, and biomarkers detection can provide better-personalized treatment for mCRC patients. How to identify and reverse the secondary resistance to anti-EGFR monoclonal antibody therapy is also another great challenge to improve the anti-EGFR efficacy in wild-type KRAS mCRC patients. Finally, both of the molecular mechanisms of response and acquired resistance would be important for the directions of future research. This review focuses on how to further improve the predictive value of anti-EGFR therapies and how to also try and avoid futile treatment for wild-type KRAS colorectal cancer patients. PMID:26869800

  12. Numerical Prediction of Performance of Water Type Stirling Engine Considering Heat Exchange with Heat Sources

    NASA Astrophysics Data System (ADS)

    Yamaguchi, Yoshiyuki; Higuchi, Tetsuya

    Two different analytical models were developed on water type Stirling engine. One is the resonance model which qualitatively clarifies the relationship between performance and resonance tube length, and the other is the heat transfer model considering heat transfer between working gas and the tube walls of heating and cooling units. These analyses and experiments were carried out changing the resonance tube length variously, then it was confirmed that the resonance tube length which maximizes the water column amplitude of the power piston agrees well and the oscillations of water columns at that resonance tube length also agrees. In addition, a series of analysis using the heat transfer model was carried out with changing cross sectional area of the resonance tube, loss factors of the elbows, heat transfer area of heating and cooling unit, and pressure of working gas. By this numerical investigation, the effect on the resonance tube length and the work at the length in which these parameters maximize the amplitude of power piston water column was clarified.

  13. Do Personal Factors or Types of Physical Tasks Predict Workplace Injury?

    PubMed

    Oranye, Nelson Ositadimma; Wallis, Bernadine; Roer, Kim; Archer-Heese, Gail; Aguilar, Zaklina

    2016-04-01

    Occupational health research has shown that certain worker and job characteristics are risk factors for workplace injuries. Workers who engage in physically demanding jobs, especially those jobs that involve repetitive motion, are at greater risk for work-related musculoskeletal disorders (WMSD). These risks are particularly prevalent in the health care sector. It is often reported that nurses are at higher risk of workplace musculoskeletal injury than other health care workers due to frequent lifting and transfer of patients and the prevalence of workplace violence. However, many analyses of the physical requirements of jobs do not consider the modifying effect of time spent on a physical task and the risk of WMSD. This study compared the risks of WMSD among workers in health care facilities based on the type of physical tasks and amount of time workers spent on such tasks. Workers who worked longer on a physical task reported more WMSD than those who spent less time on the same physical task. The risk of WMSD was twice as high (odds ratio [OR] = 2.3) among workers who sit less than 2 hours each day compared with those who sit longer. This study found that physical tasks associated with health care jobs and the amount of time spent on these tasks constitutes serious risk factors for WMSD. PMID:27056936

  14. The evaluation of tools used to predict the impact of missense variants is hindered by two types of circularity

    PubMed Central

    Grimm, Dominik G.; Azencott, Chloé-Agathe; Aicheler, Fabian; Gieraths, Udo; MacArthur, Daniel G.; Samocha, Kaitlin E.; Cooper, David N.; Stenson, Peter D.; Daly, Mark J.; Smoller, Jordan W.; Duncan, Laramie E.; Borgwardt, Karsten M.

    2015-01-01

    Prioritizing missense variants for further experimental investigation is a key challenge in current sequencing studies for exploring complex and Mendelian diseases. A large number of in silico tools have been employed for the task of pathogenicity prediction, including PolyPhen-2, SIFT, FatHMM, MutationTaster-2, MutationAssessor, CADD, LRT, phyloP and GERP++, as well as optimized methods of combining tool scores, such as Condel and Logit. Due to the wealth of these methods, an important practical question to answer is which of these tools generalize best, that is, correctly predict the pathogenic character of new variants. We here demonstrate in a study of ten tools on five datasets that such a comparative evaluation of these tools is hindered by two types of circularity: they arise due to (1) the same variants or (2) different variants from the same protein occurring both in the datasets used for training and for evaluation of these tools, which may lead to overly optimistic results. We show that comparative evaluations of predictors that do not address these types of circularity may erroneously conclude that circularity-confounded tools are most accurate among all tools, and may even outperform optimized combinations of tools. PMID:25684150

  15. The evaluation of tools used to predict the impact of missense variants is hindered by two types of circularity.

    PubMed

    Grimm, Dominik G; Azencott, Chloé-Agathe; Aicheler, Fabian; Gieraths, Udo; MacArthur, Daniel G; Samocha, Kaitlin E; Cooper, David N; Stenson, Peter D; Daly, Mark J; Smoller, Jordan W; Duncan, Laramie E; Borgwardt, Karsten M

    2015-05-01

    Prioritizing missense variants for further experimental investigation is a key challenge in current sequencing studies for exploring complex and Mendelian diseases. A large number of in silico tools have been employed for the task of pathogenicity prediction, including PolyPhen-2, SIFT, FatHMM, MutationTaster-2, MutationAssessor, Combined Annotation Dependent Depletion, LRT, phyloP, and GERP++, as well as optimized methods of combining tool scores, such as Condel and Logit. Due to the wealth of these methods, an important practical question to answer is which of these tools generalize best, that is, correctly predict the pathogenic character of new variants. We here demonstrate in a study of 10 tools on five datasets that such a comparative evaluation of these tools is hindered by two types of circularity: they arise due to (1) the same variants or (2) different variants from the same protein occurring both in the datasets used for training and for evaluation of these tools, which may lead to overly optimistic results. We show that comparative evaluations of predictors that do not address these types of circularity may erroneously conclude that circularity confounded tools are most accurate among all tools, and may even outperform optimized combinations of tools. PMID:25684150

  16. Reduced Heart Rate Variability Predicts Progression of Coronary Artery Calcification in Adults with Type 1 Diabetes and Controls Without Diabetes

    PubMed Central

    Rodrigues, Ticiana C.; Ehrlich, James; Hunter, Cortney M.; Kinney, Gregory L.; Rewers, Marian

    2010-01-01

    Abstract Aim Reduced heart rate variability (HRV) is a manifestation of cardiac autonomic neuropathy, a known complication of type 1 diabetes (T1D). We evaluated whether HRV predicted coronary artery calcium (CAC) progression. Methods Subjects between 19 and 56 years of age with T1D or those without diabetes from the Coronary Artery Calcification in Type 1 Diabetes study underwent supine deep breathing 12-lead electrocardiograms. The SD of consecutive RR intervals was used as a measure of HRV. CAC was measured at two visits 6.0 ± 0.5 years apart. Progression of CAC was defined as an increase in square root transformed CAC volume of ≥2.5 mm3, excluding patients who had cardiovascular events during follow-up. Results Reduced HRV was associated with older age, higher hemoglobin A1c, elevated albuminuria, CAC volume at baseline, and increased fibrinogen. Higher HRV at baseline was associated with lower likelihood CAC progression (odds ratio = 0.71, 95% confidence interval 0.56–0.90, P = 0.005), and the adjustment for known cardiovascular risk factors did not change this strong association, including adjustment for inflammatory markers. Conclusions Reduced HRV predicted progression of CAC in adults with and without T1D. This association further supports the participation of autonomic neuropathy in the atherosclerosis process. PMID:21128843

  17. Development of an in Silico Model of DPPH• Free Radical Scavenging Capacity: Prediction of Antioxidant Activity of Coumarin Type Compounds.

    PubMed

    Goya Jorge, Elizabeth; Rayar, Anita Maria; Barigye, Stephen J; Jorge Rodríguez, María Elisa; Sylla-Iyarreta Veitía, Maité

    2016-01-01

    A quantitative structure-activity relationship (QSAR) study of the 2,2-diphenyl-l-picrylhydrazyl (DPPH•) radical scavenging ability of 1373 chemical compounds, using DRAGON molecular descriptors (MD) and the neural network technique, a technique based on the multilayer multilayer perceptron (MLP), was developed. The built model demonstrated a satisfactory performance for the training ( R 2 = 0.713 ) and test set ( Q ext 2 = 0.654 ) , respectively. To gain greater insight on the relevance of the MD contained in the MLP model, sensitivity and principal component analyses were performed. Moreover, structural and mechanistic interpretation was carried out to comprehend the relationship of the variables in the model with the modeled property. The constructed MLP model was employed to predict the radical scavenging ability for a group of coumarin-type compounds. Finally, in order to validate the model's predictions, an in vitro assay for one of the compounds (4-hydroxycoumarin) was performed, showing a satisfactory proximity between the experimental and predicted pIC50 values. PMID:27338348

  18. Development of an in Silico Model of DPPH• Free Radical Scavenging Capacity: Prediction of Antioxidant Activity of Coumarin Type Compounds

    PubMed Central

    Goya Jorge, Elizabeth; Rayar, Anita Maria; Barigye, Stephen J.; Jorge Rodríguez, María Elisa; Sylla-Iyarreta Veitía, Maité

    2016-01-01

    A quantitative structure-activity relationship (QSAR) study of the 2,2-diphenyl-l-picrylhydrazyl (DPPH•) radical scavenging ability of 1373 chemical compounds, using DRAGON molecular descriptors (MD) and the neural network technique, a technique based on the multilayer multilayer perceptron (MLP), was developed. The built model demonstrated a satisfactory performance for the training (R2=0.713) and test set (Qext2=0.654), respectively. To gain greater insight on the relevance of the MD contained in the MLP model, sensitivity and principal component analyses were performed. Moreover, structural and mechanistic interpretation was carried out to comprehend the relationship of the variables in the model with the modeled property. The constructed MLP model was employed to predict the radical scavenging ability for a group of coumarin-type compounds. Finally, in order to validate the model’s predictions, an in vitro assay for one of the compounds (4-hydroxycoumarin) was performed, showing a satisfactory proximity between the experimental and predicted pIC50 values. PMID:27338348

  19. Predictive Potential of Twenty-Two Biochemical Biomarkers for Coronary Artery Disease in Type 2 Diabetes Mellitus

    PubMed Central

    Pereira, Edimar Cristiano; Bertolami, Marcelo Chiara; Faludi, André Arpad; Monte, Osmar; Xavier, Hermes Toros; Pereira, Tiago Veiga

    2015-01-01

    We investigated the potential of a panel of 22 biomarkers to predict the presence of coronary artery disease (CAD) in type 2 diabetes mellitus (DM2) patients. The study enrolled 96 DM2 patients with (n = 75) and without (n = 21) evidence of CAD. We assessed a biochemical profile that included 22 biomarkers: total cholesterol, LDL, HDL, LDL/HDL, triglycerides, glucose, glycated hemoglobin, fructosamine, homocysteine, cysteine, methionine, reduced glutathione, oxidized glutathione, reduced glutathione/oxidized glutathione, L-arginine, asymmetric dimethyl-L-arginine, symmetric dimethyl-L-arginine, asymmetric dimethyl-L-arginine/L-arginine, nitrate plus nitrite, S-nitrosothiols, nitrotyrosine, and n-acetyl-β-glucosaminidase. Prediction models were built using logistic regression models. We found that eight biomarkers (methionine, nitratate plus nitrite, n-acetyl-β-glucosaminidase, BMI, LDL, HDL, reduced glutathione, and L-arginine/asymmetric dimethyl-L-arginine) along with gender and BMI were significantly associated with the odds of CAD in DM2. These preliminary findings support the notion that emerging biochemical markers might be used for CAD prediction in patients with DM2. Our findings warrant further investigation with large, well-designed studies. PMID:26089875

  20. The prediction of bacteria type and culture growth phase by an electronic nose with a multi-layer perceptron network

    NASA Astrophysics Data System (ADS)

    Gardner, J. W.; Craven, M.; Dow, C.; Hines, E. L.

    1998-01-01

    An investigation into the use of an electronic nose to predict the class and growth phase of two potentially pathogenic micro-organisms, Eschericha coli ( E. coli) and Staphylococcus aureus ( S. aureus), has been performed. In order to do this we have developed an automated system to sample, with a high degree of reproducibility, the head space of bacterial cultures grown in a standard nutrient medium. Head spaces have been examined by using an array of six different metal oxide semiconducting gas sensors and classified by a multi-layer perceptron (MLP) with a back-propagation (BP) learning algorithm. The performance of 36 different pre-processing algorithms has been studied on the basis of nine different sensor parameters and four different normalization techniques. The best MLP was found to classify successfully 100% of the unknown S. aureus samples and 92% of the unknown E. coli samples, on the basis of a set of 360 training vectors and 360 test vectors taken from the lag, log and stationary growth phases. The real growth phase of the bacteria was determined from optical cell counts and was predicted from the head space samples with an accuracy of 81%. We conclude that these results show considerable promise in that the correct prediction of the type and growth phase of pathogenic bacteria may help both in the more rapid treatment of bacterial infections and in the more efficient testing of new anti-biotic drugs.

  1. Predicted Aerodynamic Characteristics of a NACA 0015 Airfoil Having a 25% Integral-Type Trailing Edge Flap

    NASA Technical Reports Server (NTRS)

    Hassan, Ahmed

    1999-01-01

    Using the two-dimensional ARC2D Navier-Stokes flow solver analyses were conducted to predict the sectional aerodynamic characteristics of the flapped NACA-0015 airfoil section. To facilitate the analyses and the generation of the computational grids, the airfoil with the deflected trailing edge flap was treated as a single element airfoil with no allowance for a gap between the flap's leading edge and the base of the forward portion of the airfoil. Generation of the O-type computational grids was accomplished using the HYGRID hyperbolic grid generation program. Results were obtained for a wide range of Mach numbers, angles of attack and flap deflections. The predicted sectional lift, drag and pitching moment values for the airfoil were then cast in tabular format (C81) to be used in lifting-line helicopter rotor aerodynamic performance calculations. Similar were also generated for the flap. Mathematical expressions providing the variation of the sectional lift and pitching moment coefficients for the airfoil and for the flap as a function of flap chord length and flap deflection angle were derived within the context of thin airfoil theory. The airfoil's sectional drag coefficient were derived using the ARC2D drag predictions for equivalent two dimensional flow conditions.

  2. Mathematical analysis of mural thrombogenesis. Concentration profiles of platelet-activating agents and effects of viscous shear flow.

    PubMed Central

    Folie, B J; McIntire, L V

    1989-01-01

    The concentration profiles of adenosine diphosphate (ADP), thromboxane A2 (TxA2), thrombin, and von Willebrand factor (vWF) released extracellularly from the platelet granules or produced metabolically on the platelet membrane during thrombus growth, were estimated using finite element simulation of blood flow over model thrombi of various shapes and dimensions. The wall fluxes of these platelet-activating agents were estimated for each model thrombus at three different wall shear rates (100 s-1, 800 s-1, and 1,500 s-1), employing experimental data on thrombus growth rates and sizes. For that purpose, whole human blood was perfused in a parallel-plate flow chamber coated with type l fibrillar human collagen, and the kinetic data collected and analyzed by an EPl-fluorescence video microscopy system and a digital image processor. It was found that thrombin concentrations were large enough to cause irreversible platelet aggregation. Although heparin significantly accelerated thrombin inhibition by antithrombin lll, the remaining thrombin levels were still significantly above the minimum threshold required for irreversible platelet aggregation. While ADP concentrations were large enough to cause irreversible platelet aggregation at low shear rates and for small aggregate sizes, TxA2 concentrations were only sufficient to induce platelet shape change over the entire range of wall shear rates and thrombi dimensions studied. Our results also indicated that the local concentration of vWF multimers released from the platelet alpha-granules could be sufficient to modulate platelet aggregation at low and intermediate wall shear rates (less than 1,000 s-1). The sizes of standing vortices formed adjacent to a growing aggregate and the embolizing stresses and the torque, acting at the aggregate surface, were also estimated in this simulation. It was found that standing vortices developed on both sides of the thrombus even at low wall shear rates. Their sizes increased with

  3. A Panel of Novel Biomarkers Representing Different Disease Pathways Improves Prediction of Renal Function Decline in Type 2 Diabetes

    PubMed Central

    Pena, Michelle J.; Heinzel, Andreas; Heinze, Georg; Alkhalaf, Alaa; Bakker, Stephan J. L.; Nguyen, Tri Q.; Goldschmeding, Roel; Bilo, Henk J. G.; Perco, Paul; Mayer, Bernd; de Zeeuw, Dick; Lambers Heerspink, Hiddo J.

    2015-01-01

    Objective We aimed to identify a novel panel of biomarkers predicting renal function decline in type 2 diabetes, using biomarkers representing different disease pathways speculated to contribute to the progression of diabetic nephropathy. Research Design and Methods A systematic data integration approach was used to select biomarkers representing different disease pathways. Twenty-eight biomarkers were measured in 82 patients seen at an outpatient diabetes center in The Netherlands. Median follow-up was 4.0 years. We compared the cross-validated explained variation (R2) of two models to predict eGFR decline, one including only established risk markers, the other adding a novel panel of biomarkers. Least absolute shrinkage and selection operator (LASSO) was used for model estimation. The C-index was calculated to assess improvement in prediction of accelerated eGFR decline defined as <-3.0 mL/min/1.73m2/year. Results Patients’ average age was 63.5 years and baseline eGFR was 77.9 mL/min/1.73m2. The average rate of eGFR decline was -2.0 ± 4.7 mL/min/1.73m2/year. When modeled on top of established risk markers, the biomarker panel including matrix metallopeptidases, tyrosine kinase, podocin, CTGF, TNF-receptor-1, sclerostin, CCL2, YKL-40, and NT-proCNP improved the explained variability of eGFR decline (R2 increase from 37.7% to 54.6%; p=0.018) and improved prediction of accelerated eGFR decline (C-index increase from 0.835 to 0.896; p=0.008). Conclusions A novel panel of biomarkers representing different pathways of renal disease progression including inflammation, fibrosis, angiogenesis, and endothelial function improved prediction of eGFR decline on top of established risk markers in type 2 diabetes. These results need to be confirmed in a large prospective cohort. PMID:25973922

  4. Usefulness of Insulin Resistance Estimation and the Metabolic Syndrome in Predicting Coronary Atherosclerosis in Type 2 Diabetes Mellitus

    PubMed Central

    Mehta, Nehal N.; Krishnamoorthy, Parasuram; Martin, Seth S.; Clair, Caitlin St; Schwartz, Stanley; Iqbal, Nayyar; Braunstein, Seth; Schutta, Mark; Rader, Daniel J.; Reilly, Muredach P.

    2011-01-01

    Metabolic syndrome (MS) definitions predict cardiovascular events beyond traditional risk factors in type 2 diabetic (DM) as well as non-diabetics subjects. We and other have shown that apolipoprotein B (apoB) and non-HDL cholesterol (non-HDL-C) are associated with coronary artery calcification (CAC) in DM. However, the relative value of MS, apoB lipoproteins and estimates of insulin resistance is unknown in predicting atherosclerosis in DM. We performed cross sectional analyses of white subjects in 2 community based studies (N= 611 type 2 diabetic subjects, N= 803 non-diabetic subjects) using multivariate analysis of traditional risk factors and then adding MS, apoB and homeostatic model assessment for insulin resistance (HOMA-IR). Incremental value was tested with likelihood ratio testing. Beyond traditional risk, HOMA-IR [Tobit regression ratio 1.86 (p=0.002)], apoB [1.55 (p=0.001)] and MS [2.37 (p=0.007)] were independently associated with CAC. In nested models, HOMA-IR added value to apoB [1.72 (p=0.008)], MS [1.72 (p=0.011)] and both apoB and MS [1.64 (p=0.021)]. ApoB showed a similar pattern when added to HOMA-IR [1.51 (p=0.004)], MS [1.46 (p=0.005)] and both HOMA-IR and MS [1.48 (p=0.006)]. MS added to apoB [1.99 (p=0.032)], but not HOMA-IR [1.54 (p=0.221)] or both apoB and HOMA-IR [1.32 (p=0.434)]. In conclusion, insulin resistance estimates add value to MS and apoB in predicting CAC scores in DM and warrant further evaluation in clinic for identification of DM patients at higher risk for atherosclerotic cardiovascular disease. PMID:21257006

  5. Elasticity in portion selection is predicted by severity of anorexia and food type in adolescents.

    PubMed

    Herzog, M; Douglas, C R; Kissileff, H R; Brunstrom, J M; Halmi, K A

    2016-08-01

    The size of portions that people select is an indicator of underlying mechanisms controlling food intake. Fears of eating excessive portions drive down the sizes of portions patients with anorexia nervosa (AN) can tolerate eating significantly below those of healthy controls (HC) (Kissileff et al., 2016). To determine whether patients with AN will also reduce the sizes of typical or ideal portions below those of controls, ANOVA was used to compare maximum tolerable, typical, and ideal portions of four foods (potatoes, rice, pizza, and M&M's) in the same group of 24 adolescent AN patients and 10 healthy adolescent controls (HC), on which only the maximal portion data were previously reported. Typical and ideal portion sizes did not differ on any food for AN, but for HC, typical portions sizes (kcals) became larger than ideal as the energy density of the food increased, and were significant for the most energy dense food. Ideal portions of low energy dense foods were the same for AN as for in HC. There was a significant 3-way (group × food × portion type) interaction, such that HC selected larger maximum than typical portions only for pizza. We therefore proposed that individuals of certain groups, depending on the food, can be flexible in the amounts of food chosen to be eaten. We call this difference between maximum-tolerable, and typical portion sizes selected "elasticity." Elasticity was significantly smaller for AN patients compared to HC for pizza and was significantly inversely correlated with severity of illness. This index could be useful for clinical assessment of AN patients, and those with eating problems such as in obesity and bulimia nervosa and tracking their response to treatment. PMID:27037222

  6. Shear small-angle light scattering studies of shear-induced concentration fluctuations and steady state viscoelastic properties.

    PubMed

    Endoh, Maya K; Takenaka, Mikihito; Inoue, Tadashi; Watanabe, Hiroshi; Hashimoto, Takeji

    2008-04-28

    We aimed at elucidating the influence of shear-induced structures (shear-enhanced concentration fluctuations and/or shear-induced phase separation), as observed by rheo-optical methods with small-angle light scattering under shear flow (shear-SALS) and shear-microscopy, on viscoelastic properties in semidilute polystyrene (PS) solutions of 6.0 wt % concentration using dioctyl phthalate (DOP) as a Theta solvent and tricresyl phosphate (TCP) as a good solvent. In order to quantify the effects of the shear-induced structures, we conducted a numerical analysis of rheological properties in a homogeneous solution based on the constitutive equation developed by Kaye-Bernstein, Kearsley, and Zapas (K-BKZ). In the low-to-intermediate shear rate gamma region between tau(w) (-1) and tau(e) (-1), where tau(w) and tau(e) are, respectively, terminal relaxation time and the relaxation time for chain stretching, the steady state rheological properties, such as shear stress sigma and the first normal stress difference N(1), for the PS/DOP and PS/TCP solutions are found to be almost same and also well predicted by the K-BKZ equation, in spite of the fact that there is a significant difference in the shear-induced structures as observed by shear-SALS and shear-microscopy. This implies that the contribution of the concentration fluctuations built up by shear flow to the rheological properties seems very small in this gamma region. On the other hand, once gamma exceeds tau(e) (-1), sigma and N(1) for both PS/DOP and PS/TCP start to deviate from the predicted values. Moreover, when gamma further increases and becomes higher than gamma(a,DOP) (sufficiently higher than tau(e) (-1)), above which rheological and scattering anomalies are observed for PS/DOP, sigma and N(1) for PS/DOP and PS/TCP are significantly larger than those predicted by K-BKZ. Particularly, a steep increase of sigma and N(1) for PS/DOP above gamma(a,DOP) is attributed to an excess free energy stored in the system via

  7. Prediction of silo-vibrations using a modified lambdameter

    NASA Astrophysics Data System (ADS)

    Jäckel, Stefan; Schünemann, Ralf; Mütze, Thomas; Peuker, Urs A.

    2013-06-01

    Predicting silo-vibrations is not yet universally possible but only to a very limited extent. A mechanism of excitation of silo vibrations can be found in oscillating shear stresses between the bulk solid and the inner silo wall, the so-called "wall-stick-slip" effect. So if this wall-stick-slip occurs during shear experiments in shear testers, the probability of silo-vibrations in silos will be high. However if there is no slip-stick effect observed, this will not consequently exclude silo-vibrations. The influences on a stable stick-slip were studied in wall friction experiments with a rotational shear tester and in a specially developed silo model based on a lambdameter. The examined parameters are normal stress, shear velocity, wall roughness and particle shape. Plastic pellets which are known to honk (PET, PA) and plastic pellets that do not honk (PE) are considered [1]. It is shown that the silo model based on a lambdameter is more suitable for initiation and measurement of stable wall-stick-slip of granular media than the conventional rotational shear tester. The industrial experiences in respect of silo vibrations are proved in the silo model for all tested types of plastic pellets. So, if the origin of silo vibrations is wall-stick-slip, the silo model based on a lambdameter gives a better opportunity for predicting silo vibrations. This paper gives a summary on the results obtained with the new method.

  8. Differential effects of two types of formative assessment in predicting performance of first-year medical students.

    PubMed

    Krasne, Sally; Wimmers, Paul F; Relan, Anju; Drake, Thomas A

    2006-05-01

    Formative assessments are systematically designed instructional interventions to assess and provide feedback on students' strengths and weaknesses in the course of teaching and learning. Despite their known benefits to student attitudes and learning, medical school curricula have been slow to integrate such assessments into the curriculum. This study investigates how performance on two different modes of formative assessment relate to each other and to performance on summative assessments in an integrated, medical-school environment. Two types of formative assessment were administered to 146 first-year medical students each week over 8 weeks: a timed, closed-book component to assess factual recall and image recognition, and an un-timed, open-book component to assess higher order reasoning including the ability to identify and access appropriate resources and to integrate and apply knowledge. Analogous summative assessments were administered in the ninth week. Models relating formative and summative assessment performance were tested using Structural Equation Modeling. Two latent variables underlying achievement on formative and summative assessments could be identified; a "formative-assessment factor" and a "summative-assessment factor," with the former predicting the latter. A latent variable underlying achievement on open-book formative assessments was highly predictive of achievement on both open- and closed-book summative assessments, whereas a latent variable underlying closed-book assessments only predicted performance on the closed-book summative assessment. Formative assessments can be used as effective predictive tools of summative performance in medical school. Open-book, un-timed assessments of higher order processes appeared to be better predictors of overall summative performance than closed-book, timed assessments of factual recall and image recognition. PMID:16729243

  9. Sixty-five common genetic variants and prediction of type 2 diabetes.

    PubMed

    Talmud, Philippa J; Cooper, Jackie A; Morris, Richard W; Dudbridge, Frank; Shah, Tina; Engmann, Jorgen; Dale, Caroline; White, Jon; McLachlan, Stela; Zabaneh, Delilah; Wong, Andrew; Ong, Ken K; Gaunt, Tom; Holmes, Michael V; Lawlor, Debbie A; Richards, Marcus; Hardy, Rebecca; Kuh, Diana; Wareham, Nicholas; Langenberg, Claudia; Ben-Shlomo, Yoav; Wannamethee, S Goya; Strachan, Mark W J; Kumari, Meena; Whittaker, John C; Drenos, Fotios; Kivimaki, Mika; Hingorani, Aroon D; Price, Jacqueline F; Humphries, Steve E

    2015-05-01

    We developed a 65 type 2 diabetes (T2D) variant-weighted gene score to examine the impact on T2D risk assessment in a U.K.-based consortium of prospective studies, with subjects initially free from T2D (N = 13,294; 37.3% women; mean age 58.5 [38-99] years). We compared the performance of the gene score with the phenotypically derived Framingham Offspring Study T2D risk model and then the two in combination. Over the median 10 years of follow-up, 804 participants developed T2D. The odds ratio for T2D (top vs. bottom quintiles of gene score) was 2.70 (95% CI 2.12-3.43). With a 10% false-positive rate, the genetic score alone detected 19.9% incident cases, the Framingham risk model 30.7%, and together 37.3%. The respective area under the receiver operator characteristic curves were 0.60 (95% CI 0.58-0.62), 0.75 (95% CI 0.73 to 0.77), and 0.76 (95% CI 0.75 to 0.78). The combined risk score net reclassification improvement (NRI) was 8.1% (5.0 to 11.2; P = 3.31 × 10(-7)). While BMI stratification into tertiles influenced the NRI (BMI ≤24.5 kg/m(2), 27.6% [95% CI 17.7-37.5], P = 4.82 × 10(-8); 24.5-27.5 kg/m(2), 11.6% [95% CI 5.8-17.4], P = 9.88 × 10(-5); >27.5 kg/m(2), 2.6% [95% CI -1.4 to 6.6], P = 0.20), age categories did not. The addition of the gene score to a phenotypic risk model leads to a potentially clinically important improvement in discrimination of incident T2D. PMID:25475436

  10. Age at diagnosis predicts deterioration in glycaemic control among children and adolescents with type 1 diabetes

    PubMed Central

    Clements, Mark A; Lind, Marcus; Raman, Sripriya; Patton, Susana R; Lipska, Kasia J; Fridlington, Amanda G; Tang, Fengming; Jones, Phil G; Wu, Yue; Spertus, John A; Kosiborod, Mikhail

    2014-01-01

    Background Poor glycemic control early in the course of type 1 diabetes mellitus (T1DM) increases the risk for microvascular complications. However, predictors of deteriorating control after diagnosis have not been described, making it difficult to identify high-risk patients and proactively provide aggressive interventions. Objective We examined whether diagnostic age, gender, and race were associated with deteriorating glycemic control during the first 5 years after diagnosis. Participants 2218 pediatric patients with T1DM. Methods We conducted a longitudinal cohort study of pediatric patients with T1DM from the Midwest USA, 1993–2009, evaluating within-patient glycated hemoglobin (HbA1c) trajectories constructed from all available HbA1c values within 5 years of diagnosis. Results 52.6% of patients were male; 86.1% were non-Hispanic Caucasian. The mean diagnostic age was 9.0±4.1 years. The mean number of HbA1c values/year/participant was 2.4±0.9. HbA1c trajectories differed markedly across age groups, with older patients experiencing greater deterioration than their younger counterparts (p<0.001). HbA1c trajectories, stratified by age, varied markedly by race (p for race×diagnostic age <0.001). Non-Hispanic African-American patients experienced higher initial HbA1c (8.7% vs 7.6% (71.6 vs 59.6 mmol/mol); p<0.001), and greater deterioration in HbA1c than non-Hispanic Caucasian patients across diagnostic ages (rise of 2.04% vs 0.99% per year (22.3 vs 10.8 mmol/mol/year); p<0.0001). Conclusions Older diagnostic age and black race are major risk factors for deterioration in glycemic control early in the course of T1DM. These findings can inform efforts to explore the reasons behind these differences and develop preventive interventions for high-risk patients. PMID:25452876

  11. Sixty-Five Common Genetic Variants and Prediction of Type 2 Diabetes

    PubMed Central

    Cooper, Jackie A.; Morris, Richard W.; Dudbridge, Frank; Shah, Tina; Engmann, Jorgen; Dale, Caroline; White, Jon; McLachlan, Stela; Zabaneh, Delilah; Wong, Andrew; Ong, Ken K.; Gaunt, Tom; Holmes, Michael V.; Lawlor, Debbie A.; Richards, Marcus; Hardy, Rebecca; Kuh, Diana; Wareham, Nicholas; Langenberg, Claudia; Ben-Shlomo, Yoav; Wannamethee, S. Goya; Strachan, Mark W.J.; Kumari, Meena; Whittaker, John C.; Drenos, Fotios; Kivimaki, Mika; Hingorani, Aroon D.; Price, Jacqueline F.; Humphries, Steve E.

    2015-01-01

    We developed a 65 type 2 diabetes (T2D) variant–weighted gene score to examine the impact on T2D risk assessment in a U.K.-based consortium of prospective studies, with subjects initially free from T2D (N = 13,294; 37.3% women; mean age 58.5 [38–99] years). We compared the performance of the gene score with the phenotypically derived Framingham Offspring Study T2D risk model and then the two in combination. Over the median 10 years of follow-up, 804 participants developed T2D. The odds ratio for T2D (top vs. bottom quintiles of gene score) was 2.70 (95% CI 2.12–3.43). With a 10% false-positive rate, the genetic score alone detected 19.9% incident cases, the Framingham risk model 30.7%, and together 37.3%. The respective area under the receiver operator characteristic curves were 0.60 (95% CI 0.58–0.62), 0.75 (95% CI 0.73 to 0.77), and 0.76 (95% CI 0.75 to 0.78). The combined risk score net reclassification improvement (NRI) was 8.1% (5.0 to 11.2; P = 3.31 × 10−7). While BMI stratification into tertiles influenced the NRI (BMI ≤24.5 kg/m2, 27.6% [95% CI 17.7–37.5], P = 4.82 × 10−8; 24.5–27.5 kg/m2, 11.6% [95% CI 5.8–17.4], P = 9.88 × 10−5; >27.5 kg/m2, 2.6% [95% CI −1.4 to 6.6], P = 0.20), age categories did not. The addition of the gene score to a phenotypic risk model leads to a potentially clinically important improvement in discrimination of incident T2D. PMID:25475436

  12. Gamma-ray diagnostics of Type Ia supernovae. Predictions of observables from three-dimensional modeling

    NASA Astrophysics Data System (ADS)

    Summa, A.; Ulyanov, A.; Kromer, M.; Boyer, S.; Röpke, F. K.; Sim, S. A.; Seitenzahl, I. R.; Fink, M.; Mannheim, K.; Pakmor, R.; Ciaraldi-Schoolmann, F.; Diehl, R.; Maeda, K.; Hillebrandt, W.

    2013-06-01

    Context. Although the question of progenitor systems and detailed explosion mechanisms still remains a matter of discussion, it is commonly believed that Type Ia supernovae (SNe Ia) are production sites of large amounts of radioactive nuclei. Even though the gamma-ray emission due to radioactive decays is responsible for powering the light curves of SNe Ia, gamma rays themselves are of particular interest as a diagnostic tool because they directly lead to deeper insight into the nucleosynthesis and the kinematics of these explosion events. Aims: We study the evolution of gamma-ray line and continuum emission of SNe Ia with the objective of analyzing the relevance of observations in this energy range. We seek to investigate the chances for the success of future MeV missions regarding their capabilities for constraining the intrinsic properties and the physical processes of SNe Ia. Methods: Focusing on two of the most broadly discussed SN Ia progenitor scenarios - a delayed detonation in a Chandrasekhar-mass white dwarf (WD) and a violent merger of two WDs - we used three-dimensional explosion models and performed radiative transfer simulations to obtain synthetic gamma-ray spectra. Both chosen models produce the same mass of 56Ni and have similar optical properties that are in reasonable agreement with the recently observed supernova SN 2011fe. We examine the gamma-ray spectra with respect to their distinct features and draw connections to certain characteristics of the explosion models. Applying diagnostics, such as line and hardness ratios, the detection prospects for future gamma-ray missions with higher sensitivities in the MeV energy range are discussed. Results: In contrast to the optical regime, the gamma-ray emission of our two chosen models proves to be quite different. The almost direct connection of the emission of gamma rays to fundamental physical processes occurring in SNe Ia permits additional constraints concerning several explosion model properties

  13. Validating prediction scales of type 2 diabetes mellitus in Spain: the SPREDIA-2 population-based prospective cohort study protocol

    PubMed Central

    Salinero-Fort, Miguel Ángel; de Burgos-Lunar, Carmen; Mostaza Prieto, José; Lahoz Rallo, Carlos; Abánades-Herranz, Juan Carlos; Gómez-Campelo, Paloma; Laguna Cuesta, Fernando; Estirado De Cabo, Eva; García Iglesias, Francisca; González Alegre, Teresa; Fernández Puntero, Belén; Montesano Sánchez, Luis; Vicent López, David; Cornejo Del Río, Víctor; Fernández García, Pedro J; Sabín Rodríguez, Concesa; López López, Silvia; Patrón Barandío, Pedro

    2015-01-01

    Introduction The incidence of type 2 diabetes mellitus (T2DM) is increasing worldwide. When diagnosed, many patients already have organ damage or advance subclinical atherosclerosis. An early diagnosis could allow the implementation of lifestyle changes and treatment options aimed at delaying the progression of the disease and to avoid cardiovascular complications. Different scores for identifying undiagnosed diabetes have been reported, however, their performance in populations of southern Europe has not been sufficiently evaluated. The main objectives of our study are: to evaluate the screening performance and cut-off points of the main scores that identify the risk of undiagnosed T2DM and prediabetes in a Spanish population, and to develop and validate our own predictive models of undiagnosed T2DM (screening model), and future T2DM (prediction risk model) after 5-year follow-up. As a secondary objective, we will evaluate the atherosclerotic burden of the population with undiagnosed T2DM. Methods and analysis Population-based prospective cohort study with baseline screening, to evaluate the performance of the FINDRISC, DANISH, DESIR, ARIC and QDScore, against the gold standard tests: Fasting plasma glucose, oral glucose tolerance and/or HbA1c. The sample size will include 1352 participants between the ages of 45 and 74 years. Analysis: sensitivity, specificity, positive predictive value, negative predictive value, likelihood ratio positive, likelihood ratio negative and receiver operating characteristic curves and area under curve. Binary logistic regression for the first 700 individuals (derivation) and last 652 (validation) will be performed. All analyses will be calculated with their 95% CI; statistical significance will be p<0.05. Ethics and dissemination The study protocol has been approved by the Research Ethics Committee of the Carlos III Hospital (Madrid). The score performance and predictive model will be presented in medical conferences, workshops

  14. Accurate prediction of secreted substrates and identification of a conserved putative secretion signal for type III secretion systems

    SciTech Connect

    Samudrala, Ram; Heffron, Fred; McDermott, Jason E.

    2009-04-24

    The type III secretion system is an essential component for virulence in many Gram-negative bacteria. Though components of the secretion system apparatus are conserved, its substrates, effector proteins, are not. We have used a machine learning approach to identify new secreted effectors. The method integrates evolutionary measures, such as the pattern of homologs in a range of other organisms, and sequence-based features, such as G+C content, amino acid composition and the N-terminal 30 residues of the protein sequence. The method was trained on known effectors from Salmonella typhimurium and validated on a corresponding set of effectors from Pseudomonas syringae, after eliminating effectors with detectable sequence similarity. The method was able to identify all of the known effectors in P. syringae with a specificity of 84% and sensitivity of 82%. The reciprocal validation, training on P. syringae and validating on S. typhimurium, gave similar results with a specificity of 86% when the sensitivity level was 87%. These results show that type III effectors in disparate organisms share common features. We found that maximal performance is attained by including an N-terminal sequence of only 30 residues, which agrees with previous studies indicating that this region contains the secretion signal. We then used the method to define the most important residues in this putative secretion signal. Finally, we present novel predictions of secreted effectors in S. typhimurium, some of which have been experimentally validated, and apply the method to predict secreted effectors in the genetically intractable human pathogen Chlamydia trachomatis. This approach is a novel and effective way to identify secreted effectors in a broad range of pathogenic bacteria for further experimental characterization and provides insight into the nature of the type III secretion signal.

  15. Shear degradation in fiber reinforced laminates due to matrix damage

    NASA Astrophysics Data System (ADS)

    Salavatian, Mohammedmahdi

    The objective of this study was to develop and implement a shear modulus degradation model to improve the failure analysis of the fiber reinforced composite structures. Matrix damage, involving transverse and shear cracks, is a common failure mode for composite structures, yet little is known concerning their interaction. To understand the material behavior after matrix failure, the nonlinear response of the composite laminate was studied using pressure vessels made from a [+/-o] bias orientation, which tend to exhibit a matrix dominated failure. The result of this work showed laminate matrix hardening in shear and softening in the transverse direction. A modified Iosipescu coupon was proposed to study the evolution of shear and transverse damage and their mutual effects. The proposed method showed good agreement with tubular results and has advantages of simplified specimen fabrication using standard test fixtures. The proposed method was extended by introducing a novel experimental technique to study the shear degradation model under biaxial loading. Experimental results of the transverse modulus reduction were in good agreement with material degradation models, while the predicted shear modulus reduction was higher than experiment. The discrepancy between available models and observations was due to the presence of a traction between the crack surfaces. Accordingly, a closed form solution was proposed for the shear stress-strain field of a cracked laminate by replacing the cracks with cohesive zones. The constitutive equations of the crack laminate were derived including the effects of internal tractions and transverse stress on the shear modulus. The proposed analytical model was shown to be the most comprehensive model for shear modulus degradation reduction of the fiber reinforced laminates. A numerical implementation of the shear degradation model was done using continuum damage mechanics. Through this work it was shown the common assumption of a linear

  16. Contrasting magma types and steady-state, volume-predictable, basaltic volcanism along the Great Rift, Idaho.

    USGS Publications Warehouse

    Kuntz, M.A.; Champion, D.E.; Spiker, E. C.; Lefebvre, R.H.

    1986-01-01

    The Great Rift is an 85 km-long, 2-8 km-wide volcanic rift zone in the Snake River Plain, Idaho. Three basaltic lava fields, latest Pleistocene to Holocene, are located along the Great Rift: Craters of the Moon, Kings Bowl and Wapi. Craters of the Moon is the largest, covering 1600 km2 and containing approx 30 km3 of lava flows and pyroclastics. Field, radiocarbon and palaeomagnetic data show that this lava field formed in eight eruptive periods, each lasted several hundred years with a recurrence interval of several hundred to approx 3000 yr. The first eruption began approx 15 000 yr B.P. and the last ended at approx 2100 yr B.P. The other two lava fields formed approx 2250 yr B.P. Three magma types fed flows along the Great Rift. A contaminated and a fractionated type were erupted at the Craters of the Moon lava field. The third, little-fractionated Snake River Plain magma-type was erupted at the other two lava fields. The Craters of the Moon segment of the Great Rift has experienced quasi-steady state, volume-predictable volcanism for the last 15 000 yr. Based on this, about 5-6 km3 of lava will be erupted within the next 1000 yr.-L.C.H.

  17. Serum Vascular Adhesion Protein-1 Predicts End-Stage Renal Disease in Patients with Type 2 Diabetes

    PubMed Central

    Nien, Feng-Jung; Wu, Vin-Cent; Jiang, Yi-Der; Chang, Tien-Jyun; Kao, Hsien-Li; Lin, Mao-Shin; Wei, Jung-Nan; Lin, Cheng-Hsin; Shih, Shyang-Rong; Hung, Chi-Sheng; Chuang, Lee-Ming

    2016-01-01

    Background Diabetes is the leading cause of end-stage renal disease (ESRD) worldwide. Vascular adhesion protein-1 (VAP-1) participates in inflammation and catalyzes the deamination of primary amines into aldehydes, hydrogen peroxide, and ammonia, both of which are involved in the pathogenesis of diabetic complications. We have shown that serum VAP-1 is higher in patients with diabetes and in patients with chronic kidney disease (CKD), and can predict cardiovascular mortality in subjects with diabetes. In this study, we investigated if serum VAP-1 can predict ESRD in diabetic subjects. Methods In this prospective cohort study, a total of 604 type 2 diabetic subjects were enrolled between 1996 to 2003 at National Taiwan University Hospital, Taiwan, and were followed for a median of 12.36 years. The development of ESRD was ascertained by linking our database with the nationally comprehensive Taiwan Society Nephrology registry. Serum VAP-1 concentrations at enrollment were measured by time-resolved immunofluorometric assay. Results Subjects with serum VAP-1 in the highest tertile had the highest incidence of ESRD (p<0.001). Every 1-SD increase in serum VAP-1 was associated with a hazard ratio of 1.55 (95%CI 1.12–2.14, p<0.01) for the risk of ESRD, adjusted for smoking, history of cardiovascular disease, body mass index, hypertension, HbA1c, duration of diabetes, total cholesterol, use of statins, ankle-brachial index, estimated GFR, and proteinuria. We developed a risk score comprising serum VAP-1, HbA1c, estimated GFR, and proteinuria, which could predict ESRD with good performance (area under the ROC curve = 0.9406, 95%CI 0.8871–0.9941, sensitivity = 77.3%, and specificity = 92.8%). We also developed an algorithm based on the stage of CKD and a risk score including serum VAP-1, which can stratify these subjects into 3 categories with an ESRD risk of 0.101%/year, 0.131%/year, and 2.427%/year, respectively. Conclusions In conclusion, serum VAP-1 can predict ESRD

  18. Prediction of Golgi-resident protein types using general form of Chou's pseudo-amino acid compositions: Approaches with minimal redundancy maximal relevance feature selection.

    PubMed

    Jiao, Ya-Sen; Du, Pu-Feng

    2016-08-01

    Recently, several efforts have been made in predicting Golgi-resident proteins. However, it is still a challenging task to identify the type of a Golgi-resident protein. Precise prediction of the type of a Golgi-resident protein plays a key role in understanding its molecular functions in various biological processes. In this paper, we proposed to use a mutual information based feature selection scheme with the general form Chou's pseudo-amino acid compositions to predict the Golgi-resident protein types. The positional specific physicochemical properties were applied in the Chou's pseudo-amino acid compositions. We achieved 91.24% prediction accuracy in a jackknife test with 49 selected features. It has the best performance among all the present predictors. This result indicates that our computational model can be useful in identifying Golgi-resident protein types. PMID:27155042

  19. Free turbulent shear flows. Volume 2: Summary of data

    NASA Technical Reports Server (NTRS)

    Birch, S. F.

    1973-01-01

    The proceedings of a conference on free turbulent shear flows are presented. Objectives of the conference are as follows: (1) collect and process data for a variety of free mixing problems, (2) assess present theoretical capability for predicting mean velocity, concentration, and temperature distributions in free turbulent flows, (3) identify and recommend experimental studies to advance knowledge of free shear flows, and (4) increase understanding of basic turbulent mixing process for application to free shear flows. Examples of specific cases of jet flow are included.

  20. Modeling and analysis of electrorheological suspensions in shear flow

    NASA Astrophysics Data System (ADS)

    Seo, Youngwook P.; Chua, Wei Huan; Seo, Yongsok

    2015-05-01

    A new rheological model was applied to the analysis of the electrorheological behavior of a fluid containing silica nanoparticle-decorated polyaniline nanofibers. A model's predictions were compared with the experimental data, revealing that the proposed model correctly predicted the shear stress behavior both quantitatively and qualitatively. The shear stress data of the electrorheological fluid showing aligned fibers' structural reformation as a function of the shear rate agreed well with the new model which required fewer parameters than the CCJ (Cho-Choi-Jhon) model. The static yield stress was found to be quadratically dependent on the field strength, in agreement with the predictions of the polarization model. A scaling function was used to model the yield stress behavior of the electrorheological fluid over a range of electric fields, and it correctly predicted the static yield stress behavior both quantitatively and qualitatively.

  1. Predictive Validity of Personality Types versus Personality Dimensions from Early Childhood to Adulthood: Implications for the Distinction between Core and Surface Traits

    ERIC Educational Resources Information Center

    Asendorpf, Jens B.; Denissen, Jaap J. A.

    2006-01-01

    This study compared the long-term predictive validity of person-centered personality types and variable-centered personality dimensions assessed between ages 4-6 years in a population sample of 154 children. Results indicated that the predictive power of both approaches was remarkably robust between age 17 and 22, and even increased in the case of…

  2. TESTING A PREDICTION OF THE MERGER ORIGIN OF EARLY-TYPE GALAXIES: A CORRELATION BETWEEN STELLAR POPULATIONS AND ASYMMETRY

    SciTech Connect

    Gyory, Zsuzsanna; Bell, Eric F. E-mail: ericbell@umich.ed

    2010-11-20

    One of the key predictions of the merger hypothesis for the origin of early-type (elliptical and lenticular) galaxies is that tidally induced asymmetric structure should correlate with signatures of a relatively young stellar population. Such a signature was found by Schweizer and Seitzer at roughly 4{sigma} confidence. In this paper, we revisit this issue with a nearly ten-fold larger sample of 0.01 < z < 0.03 galaxies selected from the Two Micron All-Sky Survey and the Sloan Digital Sky Survey. We parameterize tidal structure using a repeatable algorithmic measure of asymmetry, and correlate this with color offset from the early-type galaxy color-magnitude relation. We recover the color offset-asymmetry correlation; furthermore, we demonstrate observationally for the first time that this effect is driven by a highly significant trend toward younger ages at higher asymmetry values. We present a simple model for the evolution of early-type galaxies through gas-rich major and minor mergers that reproduces their observed buildup from z = 1 to the present day and the distribution of present-day colors and ages. We show using this model that if both stellar populations and asymmetry were ideal 'clocks' measuring the time since last major or minor gas-rich interaction, then we would expect a rather tight correlation between age and asymmetry. We suggest that the source of extra scatter is natural diversity in progenitor star formation history, gas content, and merger mass ratio, but quantitative confirmation of this conjecture will require sophisticated modeling. We conclude that the asymmetry-age correlation is in basic accord with the merger hypothesis, and indicates that an important fraction of the early-type galaxy population is affected by major or minor mergers at cosmologically recent times.

  3. Established dietary estimates of net acid production do not predict measured net acid excretion in patients with Type 2 diabetes on Paleolithic-Hunter-Gatherer-type diets

    PubMed Central

    Frassetto, Lynda A; Shi, Lijie; Schloetter, Monique; Sebastian, Anthony; Remer, Thomas

    2014-01-01

    Background Formulas developed to estimate diet-dependent net acid excretion (NAE) generally agree with measured values for typical Western diets. Whether they can also appropriately predict NAE for "Paleolithic-type" (Paleo) diets – which contain very high amounts of fruits and vegetables (F&V) and concurrent high amounts of protein is unknown. Here we compare measured NAEs with established NAE-estimates in subjects with Type 2 diabetes (T2D). Methods Thirteen subjects with well controlled T2D were randomized to either a Paleo or American Diabetes Association (ADA) diet for 14 days. 24-hour urine collections were performed at baseline and end of the diet period, and analyzed for titratable acid, bicarbonate, and ammonium to calculate measured NAE. Three formulas for estimating NAE from dietary intake were used; two (NAE_diet R or L) that include dietary mineral intake and sulfate- and organic acid (OA) production, and one that is empirically-derived (NAE_diet F) only considering potassium and protein intake. Results Measured NAE on the Paleo diet was significantly lower than on the ADA diet (+31±22 vs. 112±52 mEq/day, p=0.002). Although all formula estimates showed similar and reasonable correlations (r=0.52–0.76) with measured NAE, each one underestimated measured values. The formula with the best correlation did not contain an estimate of dietary organic acid production. Conclusions Paleo diets are lower in NAE than typical Western diets. However, commonly used formulas clearly underestimate NAE, especially for diets with very high F&V (as the Paleo diet), and in subjects with T2D. This may be due to an inappropriate estimation of proton loads stemming from OAs, underlining the necessity for improved measures of OA-related proton sources. PMID:23859996

  4. Shear Capacity of C-Shaped and L-Shaped Angle Shear Connectors

    PubMed Central

    Tahmasbi, Farzad; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N. H.; Tahir, M. M.

    2016-01-01

    This paper investigates the behaviour of C-shaped and L-shaped angle shear connectors embedded in solid concrete slabs. An effective finite element model is proposed to simulate the push out tests of these shear connectors that encompass nonlinear material behaviour, large displacement and damage plasticity. The finite element models are validated against test results. Parametric studies using this nonlinear model are performed to investigate the variations in concrete strength and connector dimensions. The finite element analyses also confirm the test results that increasing the length of shear connector increases their shear strength proportionately. It is observed that the maximum stress in L-shaped angle connectors takes place in the weld attachment to the beam, whereas in the C-shaped angle connectors, it is in the attached leg. The location of maximum concrete compressive damage is rendered in each case. Finally, a new equation for prediction of the shear capacity of C-shaped angle connectors is proposed. PMID:27478894

  5. Shear Capacity of C-Shaped and L-Shaped Angle Shear Connectors.

    PubMed

    Tahmasbi, Farzad; Maleki, Shervin; Shariati, Mahdi; Ramli Sulong, N H; Tahir, M M

    2016-01-01

    This paper investigates the behaviour of C-shaped and L-shaped angle shear connectors embedded in solid concrete slabs. An effective finite element model is proposed to simulate the push out tests of these shear connectors that encompass nonlinear material behaviour, large displacement and damage plasticity. The finite element models are validated against test results. Parametric studies using this nonlinear model are performed to investigate the variations in concrete strength and connector dimensions. The finite element analyses also confirm the test results that increasing the length of shear connector increases their shear strength proportionately. It is observed that the maximum stress in L-shaped angle connectors takes place in the weld attachment to the beam, whereas in the C-shaped angle connectors, it is in the attached leg. The location of maximum concrete compressive damage is rendered in each case. Finally, a new equation for prediction of the shear capacity of C-shaped angle connectors is proposed. PMID:27478894

  6. Spatiotemporal dynamics of shear induced bands en route to rheochaos

    NASA Astrophysics Data System (ADS)

    Ganapathy, R.; Majumdar, S.; Sood, A. K.

    2008-08-01

    We show experimentally that the route to rheochaos in shear rate relaxation measurements is via Type-III intermittency and mixed mode oscillations in the shear-thinning wormlike micellar system of cetyltrimethylammonium tosylate in the presence of salt sodium chloride. Depolarised small angle light scattering measurements performed during flow show that scattered intensity temporally follows the shear rate/stress dynamics and portrays the crucial role played by nematic ordering. Direct visualization of the gap of the Couette cell, illuminated by an unpolarised laser sheet, in the (vorticity, velocity gradient) plane shows that the spatiotemporal dynamics of the shear induced structures is closely related to the temporal behaviour of shear rate/stress fluctuations.

  7. Shearing the Cold Dusty Plasma Liquid at Discrete Level

    NASA Astrophysics Data System (ADS)

    Yang, Chi; Chen, Meng-Chun; I, Lin

    The dynamics of the cold dusty plasma liquid sheared by a laser beam is investigated experimentally, through direct optical visualization. When the cold liquid is weakly sheared, a stick-slip type flow is found due to the presence of the crystalline ordered domain. The vortical cooperative motion of particle, identified by the analysis of bond angle variation, is found to be similar to the shear-free case. The rotation of large ordered patch through rupturing into multiple rotating patches followed by the healing process is the key mechanism of vortical motion. When the liquid is strongly sheared, the emergence of the fluidized band induced by the serious domain rupture makes the vortical motion different from the weakly sheared case.

  8. TUBE SHEARING VALVE

    DOEpatents

    Wilner, L.B.

    1960-05-24

    Explosive operated valves can be used to join two or more containers in fluid flow relationship, one such container being a sealed reservoir. The valve is most simply disposed by mounting it on the reservoir so thst a tube extends from the interior of the reservoir through the valve body, terminating at the bottom of the bore in a closed end; other containers may be similarly connected or may be open connected, as desired. The piston of the valve has a cutting edge at its lower end which shears off the closed tube ends and a recess above the cutting edge to provide a flow channel. Intermixing of the fluid being transferred with the explosion gases is prevented by a copper ring at the top of the piston which is force fitted into the bore at the beginning of the stroke. Although designed to avoid backing up of the piston at pressures up to 10,000 psi in the transferred fluid, proper operation is independent of piston position, once the tube ends were sheared.

  9. Cell-Type-Specific Predictive Network Yields Novel Insights into Mouse Embryonic Stem Cell Self-Renewal and Cell Fate

    PubMed Central

    Dowell, Karen G.; Simons, Allen K.; Wang, Zack Z.; Yun, Kyuson; Hibbs, Matthew A.

    2013-01-01

    Self-renewal, the ability of a stem cell to divide repeatedly while maintaining an undifferentiated state, is a defining characteristic of all stem cells. Here, we clarify the molecular foundations of mouse embryonic stem cell (mESC) self-renewal by applying a proven Bayesian network machine learning approach to integrate high-throughput data for protein function discovery. By focusing on a single stem-cell system, at a specific developmental stage, within the context of well-defined biological processes known to be active in that cell type, we produce a consensus predictive network that reflects biological reality more closely than those made by prior efforts using more generalized, context-independent methods. In addition, we show how machine learning efforts may be misled if the tissue specific role of mammalian proteins is not defined in the training set and circumscribed in the evidential data. For this study, we assembled an extensive compendium of mESC data: ∼2.2 million data points, collected from 60 different studies, under 992 conditions. We then integrated these data into a consensus mESC functional relationship network focused on biological processes associated with embryonic stem cell self-renewal and cell fate determination. Computational evaluations, literature validation, and analyses of predicted functional linkages show that our results are highly accurate and biologically relevant. Our mESC network predicts many novel players involved in self-renewal and serves as the foundation for future pluripotent stem cell studies. This network can be used by stem cell researchers (at http://StemSight.org) to explore hypotheses about gene function in the context of self-renewal and to prioritize genes of interest for experimental validation. PMID:23468881

  10. Cell-type-specific predictive network yields novel insights into mouse embryonic stem cell self-renewal and cell fate.

    PubMed

    Dowell, Karen G; Simons, Allen K; Wang, Zack Z; Yun, Kyuson; Hibbs, Matthew A

    2013-01-01

    Self-renewal, the ability of a stem cell to divide repeatedly while maintaining an undifferentiated state, is a defining characteristic of all stem cells. Here, we clarify the molecular foundations of mouse embryonic stem cell (mESC) self-renewal by applying a proven Bayesian network machine learning approach to integrate high-throughput data for protein function discovery. By focusing on a single stem-cell system, at a specific developmental stage, within the context of well-defined biological processes known to be active in that cell type, we produce a consensus predictive network that reflects biological reality more closely than those made by prior efforts using more generalized, context-independent methods. In addition, we show how machine learning efforts may be misled if the tissue specific role of mammalian proteins is not defined in the training set and circumscribed in the evidential data. For this study, we assembled an extensive compendium of mESC data: ∼2.2 million data points, collected from 60 different studies, under 992 conditions. We then integrated these data into a consensus mESC functional relationship network focused on biological processes associated with embryonic stem cell self-renewal and cell fate determination. Computational evaluations, literature validation, and analyses of predicted functional linkages show that our results are highly accurate and biologically relevant. Our mESC network predicts many novel players involved in self-renewal and serves as the foundation for future pluripotent stem cell studies. This network can be used by stem cell researchers (at http://StemSight.org) to explore hypotheses about gene function in the context of self-renewal and to prioritize genes of interest for experimental validation. PMID:23468881

  11. Variation in trait trade-offs allows differentiation among predefined plant functional types: implications for predictive ecology.

    PubMed

    Verheijen, Lieneke M; Aerts, Rien; Bönisch, Gerhard; Kattge, Jens; Van Bodegom, Peter M

    2016-01-01

    Plant functional types (PFTs) aggregate the variety of plant species into a small number of functionally different classes. We examined to what extent plant traits, which reflect species' functional adaptations, can capture functional differences between predefined PFTs and which traits optimally describe these differences. We applied Gaussian kernel density estimation to determine probability density functions for individual PFTs in an n-dimensional trait space and compared predicted PFTs with observed PFTs. All possible combinations of 1-6 traits from a database with 18 different traits (total of 18 287 species) were tested. A variety of trait sets had approximately similar performance, and 4-5 traits were sufficient to classify up to 85% of the species into PFTs correctly, whereas this was 80% for a bioclimatically defined tree PFT classification. Well-performing trait sets included combinations of correlated traits that are considered functionally redundant within a single plant strategy. This analysis quantitatively demonstrates how structural differences between PFTs are reflected in functional differences described by particular traits. Differentiation between PFTs is possible despite large overlap in plant strategies and traits, showing that PFTs are differently positioned in multidimensional trait space. This study therefore provides the foundation for important applications for predictive ecology. PMID:26352461

  12. Actual Performance Prediction of Split-type Room Air Conditioner which Considered Unsteady Operation Concerning Heat Island Problem

    NASA Astrophysics Data System (ADS)

    Shinomiya, Naruaki; Nishimura, Nobuya; Iyota, Hiroyuki; Nomura, Tomohiro

    Split type air conditioners are operated actually in the situation unlike the condition that was described in a product catalog. On the other hand, exhaust heat from air conditioner is considered as one of the causes of heat island problem in urban area, and the air conditioner performance and heat load affect exhaust heat amount. In this study, air conditioner performances in both standard summer day and severe hot day were examined by dynamic simulation which considered outdoor weather changes. As a result, actual performances of the air conditioner were demonstrated as a function of outdoor temperature, heat load and indoor temperature. The higher the outdoor temperature and heat load rise, the smaller influences of indoor temperature against COP became. In standard summer day, relative performance exceeded by 15 to 45% than that of JIS operating condition. Also, COP in severe hot day decreased about 6% at the peak time than that of standard day. As a result, the air conditioner exhaust heat during one day which was predicted by the proposed simulation model became about 16% smaller than the conventional prediction model.

  13. Excited waves in shear layers

    NASA Technical Reports Server (NTRS)

    Bechert, D. W.

    1982-01-01

    The generation of instability waves in free shear layers is investigated. The model assumes an infinitesimally thin shear layer shed from a semi-infinite plate which is exposed to sound excitation. The acoustical shear layer excitation by a source further away from the plate edge in the downstream direction is very weak while upstream from the plate edge the excitation is relatively efficient. A special solution is given for the source at the plate edge. The theory is then extended to two streams on both sides of the shear layer having different velocities and densities. Furthermore, the excitation of a shear layer in a channel is calculated. A reference quantity is found for the magnitude of the excited instability waves. For a comparison with measurements, numerical computations of the velocity field outside the shear layer were carried out.

  14. Shear wave speed dispersion and attenuation in granular marine sediments.

    PubMed

    Kimura, Masao

    2013-07-01

    The reported compressional wave speed dispersion and attenuation could be explained by a modified gap stiffness model incorporated into the Biot model (the BIMGS model). In contrast, shear wave speed dispersion and attenuation have not been investigated in detail. No measurements of shear wave speed dispersion have been reported, and only Brunson's data provide the frequency characteristics of shear wave attenuation. In this study, Brunson's attenuation measurements are compared to predictions using the Biot-Stoll model and the BIMGS model. It is shown that the BIMGS model accurately predicts the frequency dependence of shear wave attenuation. Then, the shear wave speed dispersion and attenuation in water-saturated silica sand are measured in the frequency range of 4-20 kHz. The vertical stress applied to the sample is 17.6 kPa. The temperature of the sample is set to be 5 °C, 20 °C, and 35 °C in order to change the relaxation frequency in the BIMGS model. The measured results are compared with those calculated using the Biot-Stoll model and the BIMGS model. It is shown that the shear wave speed dispersion and attenuation are predicted accurately by using the BIMGS model. PMID:23862793

  15. Inductive shearing of drilling pipe

    DOEpatents

    Ludtka, Gerard M.; Wilgen, John; Kisner, Roger; Mcintyre, Timothy

    2016-04-19

    Induction shearing may be used to cut a drillpipe at an undersea well. Electromagnetic rings may be built into a blow-out preventer (BOP) at the seafloor. The electromagnetic rings create a magnetic field through the drillpipe and may transfer sufficient energy to change the state of the metal drillpipe to shear the drillpipe. After shearing the drillpipe, the drillpipe may be sealed to prevent further leakage of well contents.

  16. True Shear Parallel Plate Viscometer

    NASA Technical Reports Server (NTRS)

    Ethridge, Edwin; Kaukler, William

    2010-01-01

    This viscometer (which can also be used as a rheometer) is designed for use with liquids over a large temperature range. The device consists of horizontally disposed, similarly sized, parallel plates with a precisely known gap. The lower plate is driven laterally with a motor to apply shear to the liquid in the gap. The upper plate is freely suspended from a double-arm pendulum with a sufficiently long radius to reduce height variations during the swing to negligible levels. A sensitive load cell measures the shear force applied by the liquid to the upper plate. Viscosity is measured by taking the ratio of shear stress to shear rate.

  17. Spurious Shear in Weak Lensing with LSST

    SciTech Connect

    Chang, C.; Kahn, S.M.; Jernigan, J.G.; Peterson, J.R.; AlSayyad, Y.; Ahmad, Z.; Bankert, J.; Bard, D.; Connolly, A.; Gibson, R.R.; Gilmore, K.; Grace, E.; Hannel, M.; Hodge, M.A.; Jee, M.J.; Jones, L.; Krughoff, S.; Lorenz, S.; Marshall, P.J.; Marshall, S.; Meert, A.

    2012-09-19

    The complete 10-year survey from the Large Synoptic Survey Telescope (LSST) will image {approx} 20,000 square degrees of sky in six filter bands every few nights, bringing the final survey depth to r {approx} 27.5, with over 4 billion well measured galaxies. To take full advantage of this unprecedented statistical power, the systematic errors associated with weak lensing measurements need to be controlled to a level similar to the statistical errors. This work is the first attempt to quantitatively estimate the absolute level and statistical properties of the systematic errors on weak lensing shear measurements due to the most important physical effects in the LSST system via high fidelity ray-tracing simulations. We identify and isolate the different sources of algorithm-independent, additive systematic errors on shear measurements for LSST and predict their impact on the final cosmic shear measurements using conventional weak lensing analysis techniques. We find that the main source of the errors comes from an inability to adequately characterise the atmospheric point spread function (PSF) due to its high frequency spatial variation on angular scales smaller than {approx} 10{prime} in the single short exposures, which propagates into a spurious shear correlation function at the 10{sup -4}-10{sup -3} level on these scales. With the large multi-epoch dataset that will be acquired by LSST, the stochastic errors average out, bringing the final spurious shear correlation function to a level very close to the statistical errors. Our results imply that the cosmological constraints from LSST will not be severely limited by these algorithm-independent, additive systematic effects.

  18. Unsteady behavior of a reattaching shear layer

    NASA Technical Reports Server (NTRS)

    Driver, D. M.; Seegmiller, H. L.; Marvin, J.

    1983-01-01

    A detailed investigation of the unsteadiness in a reattaching, turbulent shear layer is reported. Laser-Doppler velocimeter measurements were conditionally sampled on the basis of instantaneous flow direction near reattachment. Conditions of abnormally short reattachment and abnormally long reattachment were considered. Ensemble-averaging of measurements made during these conditions was used to obtain mean velocities and Rreynolds stresses. In the mean flow, conditional streamlines show a global change in flow pattern which correlates with wall-flow direction. This motion can loosely be described as a 'flapping' of the shear layer. Tuft probes show that the flow direction reversals occur quite randomly and are shortlived. Streses shown also vary with the change in flow pattern. Yet, the global'flapping' motion does not appear to contribute significantly to the stress in the flow. A second type of unsteady motion was identified. Spectral analysis of both wall static pressure and streamwise velocity shows that most of the energy in the flow resides in frequencies that are significantly lower than that of the turbulence. The dominant frequency is at a Strouhal number equal to 0.2, which is the characteristic frequency of roll-up and pairing of vortical structure seen in free shear layers. It is conjectured that the 'flapping' is a disorder of the roll-up and pairing process occurring in the shear layer.

  19. Shear rheological characterization of motor oils

    NASA Technical Reports Server (NTRS)

    Bair, Scott; Winer, Ward O.

    1988-01-01

    Measurements of high pressure viscosity, traction coefficient, and EHD film thickness were performed on twelve commercial automotive engine oils, a reference oil, two unformulated base oils and two unformated base oil and polymer blends. An effective high shear rate inlet viscosity was calculated from film thickness and pressure viscosity coefficient. The difference between measured and effective viscosity is a function of the polymer type and concentration. Traction measurements did not discriminate mileage formulated oils from those not so designated.

  20. The effects of transverse shearing and anisotropy on vibration frequencies of laminated cylinders

    NASA Technical Reports Server (NTRS)

    Jegley, D. C.

    1990-01-01

    The natural vibration frequencies of orthotropic and anisotropic, simply supported right circular cylinders are predicted using a theory which takes into account higher-order transverse shear deformation effects. A comparison between results based on first-order transverse shear deformation theory and the higher-order theory indicates that an additional allowance for transverse shear deformation has a negligible effect on the predicted natural vibration frequencies associated with long wavelengths, but significantly reduces the natural vibration frequencies associated with short wavelengths. Results of a parametric study of ply orientation for two classes of laminates indicates that while stacking sequence affects natural vibration frequencies, cylinder geometry and mode shape are more important in accurately predicting transverse shear deformation effects. Transverse shearing effects are less important in predicting natural vibration frequencies associated with long wavelength than in predicting axial compressive buckling loads.

  1. Turbulent Sediment Suspension and Induced Ripple Dynamics Absent Mean Shear

    NASA Astrophysics Data System (ADS)

    Johnson, B. A.; Cowen, E.

    2014-12-01

    The uprush and backwash phases in the swash zone, the region of the beach that is alternately covered and uncovered by wave run-up, are fundamentally different events. Backwash is dominated by a growing boundary layer where the turbulence is set by the bed shear stress. In this phase traditional boundary layer turbulence models and Shields-type critical stress pickup functions work well. However, the uprush phase, while often viewed in the context of traditional boundary layer turbulence models, has little in common with the backwash phase. During uprush, the entire water column is turbulent, as it rapidly advects well-stirred highly turbulent flow generated offshore from breaking waves or collapsing bores. Turbulence levels in the uprush are several times higher than turbulent boundary layer theory would predict and hence the use of a boundary layer model to predict turbulence levels during uprush grossly under predicts the turbulence and subsequent sediment suspension in the swash zone. To study the importance of this advected turbulence to sediment suspension we conduct experiments in a water tank designed to generate horizontally homogeneous isotropic turbulence absent mean shear using randomly actuated synthetic jet arrays suspended above both a solid glass plate and a narrowly graded sediment bed. Using jet arrays with different jet spacings allows the generation of high Reynolds number turbulence with variable integral length scales, which we hypothesize control the characteristic length scales in the induced ripple field. Particle image velocimetry and acoustic Doppler velocimetry measurements are used to characterize the near-bed flow and this unique turbulent boundary layer. Metrics include the mean flow and turbulence intensities and stresses, temporal and spatial spectra, dissipation of turbulent kinetic energy, and integral length scales of the turbulence. We leverage our unique dataset to compare the flows over impermeable fixed and permeable mobile

  2. Genetic markers predicting sulphonylurea treatment outcomes in type 2 diabetes patients: current evidence and challenges for clinical implementation.

    PubMed

    Loganadan, N K; Huri, H Z; Vethakkan, S R; Hussein, Z

    2016-06-01

    The clinical response to sulphonylurea, an oral antidiabetic agent often used in combination with metformin to control blood glucose in type 2 diabetes (T2DM) patients, has been widely associated with a number of gene polymorphisms, particularly those involved in insulin release. We have reviewed the genetic markers of CYP2C9, ABCC8, KCNJ11, TCF7L2 (transcription factor 7-like 2), IRS-1 (insulin receptor substrate-1), CDKAL1, CDKN2A/2B, KCNQ1 and NOS1AP (nitric oxide synthase 1 adaptor protein) genes that predict treatment outcomes of sulphonylurea therapy. A convincing pattern for poor sulphonylurea response was observed in Caucasian T2DM patients with rs7903146 and rs1801278 polymorphisms of the TCF7L2 and IRS-1 genes, respectively. However, limitations in evaluating the available studies including dissimilarities in study design, definitions of clinical end points, sample sizes and types and doses of sulphonylureas used as well as ethnic variability make the clinical applications challenging. Future studies need to address these limitations to develop personalized sulphonylurea medicine for T2DM management. PMID:26810132

  3. Excitation of fundamental shear horizontal wave by using face-shear (d36) piezoelectric ceramics

    NASA Astrophysics Data System (ADS)

    Miao, Hongchen; Dong, Shuxiang; Li, Faxin

    2016-05-01

    The fundamental shear horizontal (SH0) wave in plate-like structures is extremely useful for non-destructive testing (NDT) and structural health monitoring (SHM) as it is non-dispersive. However, currently, the SH0 wave is usually excited by electromagnetic acoustic transducers (EMAT) whose energy conversion efficiency is fairly low. The face-shear ( d 36 ) mode piezoelectrics is more promising for SH0 wave excitation, but this mode cannot appear in conventional piezoelectric ceramics. Recently, by modifying the symmetry of poled PbZr1-xTixO3 (PZT) ceramics via ferroelastic domain engineering, we realized the face-shear d 36 mode in both soft and hard PZT ceramics. In this work, we further improved the face-shear properties of PZT-4 and PZT-5H ceramics via lateral compression under elevated temperature. It was found that when bonded on a 1 mm-thick aluminum plate, the d 36 type PZT-4 exhibited better face-shear performance than PZT-5H. We then successfully excite SH0 wave in the aluminum plate using a face-shear PZT-4 square patch and receive the wave using a face-shear 0.72[Pb(Mg1/3Nb2/3)O3]-0.28[PbTiO3] (PMN-PT) patch. The frequency response and directionality of the excited SH0 wave were also investigated. The SH0 wave can be dominated over the Lamb waves (S0 and A0 waves) from 160 kHz to 280 kHz. The wave amplitude reaches its maxima along the two main directions (0° and 90°). The amplitude can keep over 80% of the maxima when the deviate angle is less than 30°, while it vanishes quickly at the 45° direction. The excited SH0 wave using piezoelectric ceramics could be very promising in the fields of NDT and SHM.

  4. The Degree of Predictability of Four Types of Sentences as Measured by the Eye-Voice Span of Graduate Student Readers.

    ERIC Educational Resources Information Center

    Lagotic, Diana Lynn

    In a study using eye-voice span (EVS) measures to determine the relationship between the types and numbers of transformations in sentences and the predictability of the sentences for readers, sentences with varying types and numbers of transformations were embedded in paragraphs projected onto a screen and read aloud by the subjects, 20 graduate…

  5. Visit-to-Visit Glucose Variability Predicts the Development of End-Stage Renal Disease in Type 2 Diabetes

    PubMed Central

    Yang, Ya-Fei; Li, Tsai-Chung; Li, Chia-Ing; Liu, Chiu-Shong; Lin, Wen-Yuan; Yang, Sing-Yu; Chiang, Jen-Huai; Huang, Chiu-Ching; Sung, Fung-Chang; Lin, Cheng-Chieh

    2015-01-01

    Abstract The purpose of this study was to examine the association of glucose variability using coefficient of variation of fasting plasma glucose (FPG-CV) and coefficient of variation of glycated hemoglobin (HbA1c-CV) to end-stage renal disease (ESRD) in 31,841 Chinese patients with type 2 diabetes. Patients with type 2 diabetes enrolled in National Diabetes Care Management Program, aged ≧30 years, and free of ESRD (n = 31,841) in January 1, 2002 to December 31, 2004 were included. Extended Cox proportional hazards regression models with competing risk of all-cause mortality were used to evaluate risk factors on ESRD incidence. Patients were followed till 2012. After a median follow-up period of 8.23 years, 1642 patients developed ESRD, giving a crude incidence rate of 6.27/1000 person-years (6.36 for men, 6.19 for women). After the multivariate adjustment, both FPG-CV and HbA1c-CV were independent predictors of ESRD with corresponding hazard ratios of 1.20 (95% confidence interval [CI] 1.01, 1.41), 1.24 (95% CI 1.05, 1.46) in HbA1c-CV from fourth to fifth quintile and 1.23 (95% CI 1.03, 1.47) in FPG-CV from fifth quintile. One-year visit-to-visit glucose variability expressed by FPG-CV and HbA1c-CV predicted development of ESRD in patients with type 2 diabetes, suggesting therapeutic strategies toward a goal to minimize glucose fluctuation. PMID:26554779

  6. Behavior of Rapidly Sheared Bubble Suspensions

    NASA Technical Reports Server (NTRS)

    Sangani, A. S.; Kushch, V. I.; Hoffmann, M.; Nahra, H.; Koch, D. L.; Tsang, Y.

    2002-01-01

    An experiment to be carried out aboard the International Space Station is described. A suspension consisting of millimeter-sized bubbles in water containing some dissolved salt, which prevents bubbles from coalescing, will be sheared in a Couette cylindrical cell. Rotation of the outer cylinder will produce centrifugal force which will tend to accumulate the bubbles near the inner wall. The shearing will enhance collisions among bubbles creating thereby bubble phase pressure that will resist the tendency of the bubbles to accumulate near the inner wall. The bubble volume fraction and velocity profiles will be measured and compared with the theoretical predictions. Ground-based research on measurement of bubble phase properties and flow in vertical channel are described.

  7. Self-healing pulse-like shear ruptures in the laboratory.

    PubMed

    Lykotrafitis, George; Rosakis, Ares J; Ravichandran, Guruswami

    2006-09-22

    Models predict that dynamic shear ruptures during earthquake faulting occur as either sliding cracks, where a large section of the interface slides behind a fast-moving rupture front, or self-healing slip pulses, where the fault relocks shortly behind the rupture front. We report experimental visualizations of crack-like, pulse-like, and mixed rupture modes propagating along frictionally held, "incoherent" interfaces separating identical solids, and we describe the conditions under which those modes develop. A combination of simultaneously performed measurements via dynamic photoelasticity and laser interferometry reveals the rupture mode type, the exact point of rupture initiation, the sliding velocity history, and the rupture propagation speed. PMID:16990544

  8. Shear strength of irradiated insulation under combined shear/compression loading

    SciTech Connect

    Reed, R.; Fabian, P.; Hazelton, C.

    1997-06-01

    The shear strengths of irradiated insulation systems were measured at 4 K under combined shear and compression loads. Sandwich-type (316LN/bonded insulation/316LN) specimens were irradiated at 4 K and tested at 4 K after storage at room temperature. Some specimens were stored at room temperature; others, at 77 K. Insulation systems included diglycidylether of bisphenol-A and tetraglycidyl diaminodiphenyl methane epoxies and polyimide resins reinforced with S-2 glass. Some contained polyimide film or mica electrical barriers. All specimens were irradiated to a fast neutron fluence of 1.8 X 10{sup 22} n/m{sup 2}. Insulation systems are compared on the basis of their irradiated and unirradiated shear strengths.

  9. Magnetic resonance elastography of slow and fast shear waves illuminates differences in shear and tensile moduli in anisotropic tissue.

    PubMed

    Schmidt, J L; Tweten, D J; Benegal, A N; Walker, C H; Portnoi, T E; Okamoto, R J; Garbow, J R; Bayly, P V

    2016-05-01

    Mechanical anisotropy is an important property of fibrous tissues; for example, the anisotropic mechanical properties of brain white matter may play a key role in the mechanics of traumatic brain injury (TBI). The simplest anisotropic material model for small deformations of soft tissue is a nearly incompressible, transversely isotropic (ITI) material characterized by three parameters: minimum shear modulus (µ), shear anisotropy (ϕ=µ1µ-1) and tensile anisotropy (ζ=E1E2-1). These parameters can be determined using magnetic resonance elastography (MRE) to visualize shear waves, if the angle between the shear-wave propagation direction and fiber direction is known. Most MRE studies assume isotropic material models with a single shear (µ) or tensile (E) modulus. In this study, two types of shear waves, "fast" and "slow", were analyzed for a given propagation direction to estimate anisotropic parameters µ, ϕ, and ζ in two fibrous soft materials: turkey breast ex vivo and aligned fibrin gels. As expected, the speed of slow shear waves depended on the angle between fiber direction and propagation direction. Fast shear waves were observed when the deformations due to wave motion induced stretch in the fiber direction. Finally, MRE estimates of anisotropic mechanical properties in turkey breast were compared to estimates from direct mechanical tests. PMID:26920505

  10. Simultaneous shear and pressure sensor array for assessing pressure and shear at foot/ground interface.

    PubMed

    Mackey, Jeffrey R; Davis, Brian L

    2006-01-01

    Foot ulceration is a diabetic complication estimated to result in over $1 billion worth of medical expenses per year in the United States alone. This multifaceted problem involves the response of plantar soft tissue to both external forces applied to the epidermis and internal changes such as vascular supply and neuropathy. Increasing evidence indicates that a combination of elevated external forces (pressure and shear) and altered tissue properties is key to the etiology of foot ulcers. The overall goal of this research is to develop a platform-type hardware system that will allow a clinician to measure three-dimensional stress tensors (i.e. pressure and shear patterns) on the plantar surface and identify areas of concern. Experimental results have demonstrated that an optical approach can provide clear indication of both shear and pressure from 50 to 400 kPa with a frequency response of 100 Hz, a stress measurement accuracy of 100 Pa and a spatial resolution of 8.0mm. Initial evaluation of the system shows strong correlation between (i) applied shear and normal stress loads and (ii) the optical phase retardance computed for each stress axis of the polymer-based stress-sensing elements. These special sensing elements are designed to minimize the need for repeated calibration procedures-an issue that has plagued other attempts to develop multisensor shear and pressure systems. PMID:16297920

  11. An Experimental Investigation into Failure and Localization Phenomena in the Extension to Shear Fracture Transition in Rock

    NASA Astrophysics Data System (ADS)

    Choens, R. C., II; Chester, F. M.; Bauer, S. J.; Flint, G. M.

    2014-12-01

    Fluid-pressure assisted fracturing can produce mesh and other large, interconnected and complex networks consisting of both extension and shear fractures in various metamorphic, magmatic and tectonic systems. Presently, rock failure criteria for tensile and low-mean compressive stress conditions is poorly defined, although there is accumulating evidence that the transition from extension to shear fracture with increasing mean stress is continuous. We report on the results of experiments designed to document failure criteria, fracture mode, and localization phenomena for several rock types (sandstone, limestone, chalk and marble). Experiments were conducted in triaxial extension using a necked (dogbone) geometry to achieve mixed tension and compression stress states with local component-strain measurements in the failure region. The failure envelope for all rock types is similar, but are poorly described using Griffith or modified Griffith (Coulomb or other) failure criteria. Notably, the mode of fracture changes systematically from pure extension to shear with increase in compressive mean stress and display a continuous change in fracture orientation with respect to principal stress axes. Differential stress and inelastic strain show a systematic increase with increasing mean stress, whereas the axial stress decreases before increasing with increasing mean stress. The stress and strain data are used to analyze elastic and plastic strains leading to failure and compare the experimental results to predictions for localization using constitutive models incorporating on bifurcation theory. Although models are able to describe the stability behavior and onset of localization qualitatively, the models are unable to predict fracture type or orientation. Constitutive models using single or multiple yield surfaces are unable to predict the experimental results, reflecting the difficulty in capturing the changing micromechanisms from extension to shear failure. Sandia

  12. A modification of Murray's law for shear-thinning rheology.

    PubMed

    McGah, Patrick M; Capobianchi, Massimo

    2015-05-01

    This study reformulates Murray's well-known principle of minimum work as applied to the cardiovascular system to include the effects of the shear-thinning rheology of blood. The viscous behavior is described using the extended modified power law (EMPL), which is a time-independent, but shear-thinning rheological constitutive equation. The resulting minimization problem is solved numerically for typical parameter ranges. The non-Newtonian analysis still predicts the classical cubic diameter dependence of the volume flow rate and the cubic branching law. The current analysis also predicts a constant wall shear stress throughout the vascular tree, albeit with a numerical value about 15-25% higher than the Newtonian analysis. Thus, experimentally observed deviations from the cubic branching law or the predicted constant wall shear stress in the vasculature cannot likely be attributed to blood's shear-thinning behavior. Further differences between the predictions of the non-Newtonian and the Newtonian analyses are highlighted, and the limitations of the Newtonian analysis are discussed. Finally, the range and limits of applicability of the current results as applied to the human arterial tree are also discussed. PMID:25565456

  13. Numerical analysis of stiffened shear webs in the postbuckling range

    NASA Technical Reports Server (NTRS)

    Stein, M.; Starnes, J. H., Jr.

    1973-01-01

    The postbuckling behavior of shear webs divided into rectangular panels by stiffeners (uprights) was studied numerically, using the STAGS program in which two-dimensional finite differences are used to solve buckling and nonlinear problems. Universal nondimensional parameters, suggested by linear buckling data, are found to hold for the postbuckling range. Results indicate that the postbuckling stiffness of shear webs with isotropic panels is roughly two thirds of the prebuckling stiffness. The postbuckling behavior of shear webs with isotropic and orthotropic material properties is compared. Some practical aspects of solving nonlinear problems of this type by the numerical method employed are examined.

  14. Application of Photon Correlation Spectroscopy to Uniform Shear Flow

    NASA Astrophysics Data System (ADS)

    Pak, Hyuk K.; Sur, Jeanman; Lee, Sangjun; Kim, Kipom

    1996-11-01

    We study the application of photon correlation spectroscopy to a system of randomly diffusing particles suspended in a uniform shear flow fluid. Unifrom shear flow is generated in Zimm viscometer type Taylor Couette cell. Detecting the scattered intensity from the diffusing particles through a single slit or multiple slit, one can not only study the uniform shear nature of Taylor-Couette flow but also transform the spatial information of the scattering volume into the time information using a photon correlation technique. We discuss useful applications of this technique.

  15. Application of a computer model to predict optimum slaughter end points for different biological types of feeder cattle.

    PubMed

    Williams, C B; Bennett, G L

    1995-10-01

    A bioeconomic model was developed to predict slaughter end points of different genotypes of feeder cattle, where profit/rotation and profit/day were maximized. Growth, feed intake, and carcass weight and composition were simulated for 17 biological types of steers. Distribution of carcass weight and proportion in four USDA quality and five USDA yield grades were obtained from predicted carcass weights and composition. Average carcass value for each genotype was calculated from these distributions under four carcass pricing systems that varied from value determined on quality grade alone to value determined on yield grade alone. Under profitable market conditions, rotation length was shorter and carcass weights lighter when the producer's goal was maximum profit/day, compared with maximum profit/rotation. A carcass value system based on yield grade alone resulted in greater profit/rotation and in lighter and leaner carcasses than a system based on quality grade alone. High correlations ( > .97) were obtained between breed profits obtained with different sets of input/output prices and carcass price discount weight ranges. This suggests that breed rankings on the basis of breed profits may not be sensitive to changes in input/output market prices. Steers that were on a grower-stocker system had leaner carcasses, heavier optimum carcass weight, greater profits, and less variation in optimum carcass weights between genotypes than steers that were started on a high-energy finishing diet at weaning. Overall results suggest that breed choices may change with different carcass grading and value systems and postweaning production systems. This model has potential to provide decision support in marketing fed cattle. PMID:8617660

  16. The PCC assay can be used to predict radiosensitivity in biopsy cultures irradiated with different types of radiation.

    PubMed

    Suzuki, Masao; Tsuruoka, Chizuru; Nakano, Takashi; Ohno, Tatsuya; Furusawa, Yoshiya; Okayasu, Ryuichi

    2006-12-01

    The aim of this study was to identify potential biomarkers for radiosensitivity using the relationship between cell killing and the yield of excess chromatin fragments detected with the premature chromosome condensation (PCC) technique. This method was applied to primary cultured cells obtained from biopsies from patients. Six primary culture biopsies were obtained from 6 patients with carcinoma of the cervix before starting radiotherapy. The cultures were irradiated with two different LET carbon-ion beams (LET = 13 keV/microm, 77.1+/-2.8 keV/microm) and 200 kV X-rays. The carbon-ion beams were produced by Heavy Ion Medical Accelerator in Chiba (HIMAC). PCC was performed using the polyethylene glycol-mediated cell fusion technique. The yield of excess chromatin fragments were measured by counting the number of unrejoined chromatin fragments detected with the PCC technique after a 24-h post-irradiation incubation period. Obtained results indicated that cultures which were more sensitive to killing were also more susceptible to the induction of excess chromatin fragments. Furthermore there was a good correlation between cell killing and excess chromatin fragments among the 6 cell cultures examined. There is also evidence that the induction of excess chromatin fragments increased with increasing LET as well as cell-killing effect in the same cell culture. The data reported here support the idea that the yield of excess chromatin fragments detected with the PCC technique might be useful for predicting the radiosensitivity of cells contained in tumor tissue, and to predict responses to different radiation types. PMID:17089052

  17. APPARATUS FOR SHEARING TUBULAR JACKETS

    DOEpatents

    Simon, J.P.

    1962-09-01

    A machine is designed for removing the jacket from the core of a used rod-like fuel element by shearing the jacket into a spiral ribbon. Three skewed rolls move the fuel element axially and rotatively, and a tool cooperates with one of the rolls to carry out the shearing action. (AEC)

  18. Three-dimensional structures and turbulence closure of the wake developing in a wall shear layer

    NASA Technical Reports Server (NTRS)

    Hah, C.

    1981-01-01

    The turbulent wake interacting with the rotating wall shear layer is investigated analytically and numerically. The turbulent wakes of the rotating blades in a compressor which are interacting with the rotating hub-wall boundary layer are analyzed. A modified version of the closure model of the pressure-strain correlation term in the Reynolds stress transport equation is developed to predict the effect of rotation, which is appreciable for the present flow because the thick hub-wall boundary layer is interacting with the rotor wake. It is noted that the Poisson type equation for the pressure-strain correlation has an extra rotation term when the entire flow field is rotating. This extra rotation term is modeled to accommodate the effect of rotation. In addition, the standard correction for the wall effect is incorporated for the utilized Reynolds stress closure model. The rotation-modified Reynolds stress closure model is used to predict the present flow, and the predictions are compared with the experimental data. The experimental data reveal that the characteristics of the three-dimensional turbulent wake interacting with the wall shear layer are considerably altered by the effects of the wall and the rotation. These features are predicted with good accuracy by the turbulence closure model developed.

  19. Impacts of different plant functional types on ambient ozone predictions in the Seoul Metropolitan Areas (SMAs), Korea

    NASA Astrophysics Data System (ADS)

    Kim, H.-K.; Woo, J.-H.; Park, R. S.; Song, C. H.; Kim, J.-H.; Ban, S.-J.; Park, J.-H.

    2014-07-01

    Plant functional type (PFT) distributions affect the results of biogenic emission modeling as well as O3 and particulate matter (PM) simulations using chemistry-transport models (CTMs). This paper analyzes the variations of both surface biogenic volatile organic compound (BVOC) emissions and O3 concentrations due to changes in the PFT distributions in the Seoul Metropolitan Areas, Korea. The Fifth-Generation NCAR/Pennsylvania State Meso-scale Model (MM5)/the Model of Emissions of Gases and Aerosols from Nature (MEGAN)/the Sparse Matrix Operator Kernel Emissions (SMOKE)/the Community Multiscale Air Quality (CMAQ) model simulations were implemented over the Seoul Metropolitan Areas in Korea to predict surface O3 concentrations for the period of 1 May to 31 June 2008. Starting from a performance check of CTM predictions, we consecutively assessed the effects of PFT area deviations on the MEGAN BVOC and CTM O3 predictions, and we further considered the basis of geospatial and statistical analyses. The three PFT data sets considered were (1) the Korean PFT, developed with Korea-specific vegetation database; (2) the CDP PFT, adopted from the community data portal (CDP) of US National Center for Atmospheric Research in the United States (NCAR); (3) MODIS PFT, reclassified from the NASA Terra and Aqua combined land cover products. Although the CMAQ performance check reveals that all of the three different PFT data sets are applicable choices for regulatory modeling practice, noticeable primary data (i.e., PFT and Leaf Area Index (LAI)) was observed to be missing in many geographic locations. Based on the assessed effect of such missing data on CMAQ O3 predictions, we found that this missing data can cause spatially increased bias in CMAQ O3. Thus, it must be resolved in the near future to obtain more accurate biogenic emission and chemistry transport modeling results. Comparisons of MEGAN biogenic emission results with the three different PFT data showed that broadleaf

  20. Development and validation of a predictive model of acute glucose response to exercise in individuals with type 2 diabetes

    PubMed Central

    2013-01-01

    Background Our purpose was to develop and test a predictive model of the acute glucose response to exercise in individuals with type 2 diabetes. Design and methods Data from three previous exercise studies (56 subjects, 488 exercise sessions) were combined and used as a development dataset. A mixed-effects Least Absolute Shrinkage Selection Operator (LASSO) was used to select predictors among 12 potential predictors. Tests of the relative importance of each predictor were conducted using the Lindemann Merenda and Gold (LMG) algorithm. Model structure was tested using likelihood ratio tests. Model accuracy in the development dataset was assessed by leave-one-out cross-validation. Prospectively captured data (47 individuals, 436 sessions) was used as a test dataset. Model accuracy was calculated as the percentage of predictions within measurement error. Overall model utility was assessed as the number of subjects with ≤1 model error after the third exercise session. Model accuracy across individuals was assessed graphically. In a post-hoc analysis, a mixed-effects logistic regression tested the association of individuals’ attributes with model error. Results Minutes since eating, a non-linear transformation of minutes since eating, post-prandial state, hemoglobin A1c, sulfonylurea status, age, and exercise session number were identified as novel predictors. Minutes since eating, its transformations, and hemoglobin A1c combined to account for 19.6% of the variance in glucose response. Sulfonylurea status, age, and exercise session each accounted for <1.0% of the variance. In the development dataset, a model with random slopes for pre-exercise glucose improved fit over a model with random intercepts only (likelihood ratio 34.5, p < 0.001). Cross-validated model accuracy was 83.3%. In the test dataset, overall accuracy was 80.2%. The model was more accurate in pre-prandial than postprandial exercise (83.6% vs. 74.5% accuracy respectively). 31/47 subjects had

  1. Monitoring of thermal therapy based on shear modulus changes: II. Shear wave imaging of thermal lesions.

    PubMed

    Arnal, Bastien; Pernot, Mathieu; Tanter, Mickael

    2011-08-01

    The clinical applicability of high-intensity focused ultrasound (HIFU) for noninvasive therapy is currently hampered by the lack of robust and real-time monitoring of tissue damage during treatment. The goal of this study is to show that the estimation of local tissue elasticity from shear wave imaging (SWI) can lead to a precise mapping of the lesion. HIFU treatment and monitoring were respectively performed using a confocal setup consisting of a 2.5-MHz single element transducer focused at 34 mm on ex vivo samples and an 8-MHz ultrasound diagnostic probe. Ultrasound-based strain imaging was combined with shear wave imaging on the same device. The SWI sequences consisted of 2 successive shear waves induced at different lateral positions. Each wave was created with pushing beams of 100 μs at 3 depths. The shear wave propagation was acquired at 17,000 frames/s, from which the elasticity map was recovered. HIFU sonications were interleaved with fast imaging acquisitions, allowing a duty cycle of more than 90%. Thus, elasticity and strain mapping was achieved every 3 s, leading to real-time monitoring of the treatment. When thermal damage occurs, tissue stiffness was found to increase up to 4-fold and strain imaging showed strong shrinkages that blur the temperature information. We show that strain imaging elastograms are not easy to interpret for accurate lesion characterization, but SWI provides a quantitative mapping of the thermal lesion. Moreover, the concept of shear wave thermometry (SWT) developed in the companion paper allows mapping temperature with the same method. Combined SWT and shear wave imaging can map the lesion stiffening and temperature outside the lesion, which could be used to predict the eventual lesion growth by thermal dose calculation. Finally, SWI is shown to be robust to motion and reliable in vivo on sheep muscle. PMID:21859579

  2. A Piezoelectric Shear Stress Sensor

    NASA Technical Reports Server (NTRS)

    Kim, Taeyang; Saini, Aditya; Kim, Jinwook; Gopalarathnam, Ashok; Zhu, Yong; Palmieri, Frank L.; Wohl, Christopher J.; Jiang, Xiaoning

    2016-01-01

    In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress suppressing effects of normal stress generated from the vortex lift-up by applying opposite poling vectors to the: piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces and it showed high sensitivity to shear stress (=91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of PMN-33%PT (d31=-1330 pC/N). The sensor also showed almost no sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is 0-800 Hz. Keywords: Piezoelectric sensor, shear stress, floating element, electromechanical symmetry

  3. Roles of wind shear at different vertical levels: Cloud system organization and properties

    NASA Astrophysics Data System (ADS)

    Chen, Qian; Fan, Jiwen; Hagos, Samson; Gustafson, William I.; Berg, Larry K.

    2015-07-01

    Understanding critical processes that contribute to the organization of mesoscale convective systems (MCSs) is important for accurate weather forecasts and climate predictions. In this study, we investigate the effects of wind shear at different vertical levels on the organization and properties of convective systems using the Weather Research and Forecasting model with spectral bin microphysics. Based on a control run for a MCS with weak wind shear (Ctrl), we find that increasing wind shear at the lower troposphere (L-shear) leads to a more organized quasi-line convective system. Strong wind shear in the middle troposphere (M-shear) tends to produce large vorticity and form a mesocyclone circulation and an isolated strong storm that leans toward supercellular structure. By increasing wind shear at the upper vertical levels only (U-shear), the organization of the convection is not changed much, but the convective intensity is weakened. Increasing wind shear in the middle troposphere for the selected case results in a significant drying, and the drying is more significant when conserving moisture advection at the lateral boundaries, contributing to the suppressed convective strength and precipitation relative to Ctrl. Precipitation in the L-shear and U-shear does not change much from Ctrl. Evident changes of cloud macrophysical and microphysical properties in the strong wind shear cases are mainly due to large changes in convective organization and water vapor. The insights obtained from this study help us better understand the major factors contributing to convective organization and precipitation.

  4. An observation of PKJKP: inferences on inner core shear properties.

    PubMed

    Cao, Aimin; Romanowicz, Barbara; Takeuchi, Nozomu

    2005-06-01

    The seismic phase PKJKP, which traverses the inner core as a shear wave and would provide direct evidence for its solidity, has been difficult to detect. Using stacked broadband records from the Grafenberg array in Germany, we documented a high signal-to-noise phase, the arrival time and slowness of which agree with theoretical predictions for PKJKP. The back azimuth of this arrival is also consistent with predictions for PKJKP, as is the comparison with a pseudoliquid inner core model. Envelope modeling of the PKJKP waveform implies a shear velocity gradient with depth in the inner core that is slightly larger than that in the preliminary reference Earth model. PMID:15831719

  5. Interaction between a normal shock wave and a turbulent boundary layer at high transonic speeds. Part 1: Pressure distribution. Part 2: Wall shear stress. Part 3: Simplified formulas for the prediction of surface pressures and skin friction

    NASA Technical Reports Server (NTRS)

    Adamson, T. C., Jr.; Liou, M. S.; Messiter, A. F.

    1980-01-01

    An asymptotic description is derived for the interaction between a shock wave and a turbulent boundary layer in transonic flow, for a particular limiting case. The dimensionless difference between the external flow velocity and critical sound speed is taken to be much smaller than one, but large in comparison with the dimensionless friction velocity. The basic results are derived for a flat plate, and corrections for longitudinal wall curvature and for flow in a circular pipe are also shown. Solutions are given for the wall pressure distribution and the shape of the shock wave. Solutions for the wall shear stress are obtained, and a criterion for incipient separation is derived. Simplified solutions for both the wall pressure and skin friction distributions in the interaction region are given. These results are presented in a form suitable for use in computer programs.

  6. Imaging Faults and Shear Zones Using Receiver Functions

    NASA Astrophysics Data System (ADS)

    Schulte-Pelkum, Vera; Mahan, Kevin H.

    2014-11-01

    The geometry of faults at seismogenic depths and their continuation into the ductile zone is of interest for a number of applications ranging from earthquake hazard to modes of lithospheric deformation. Teleseismic passive source imaging of faults and shear zones can be useful particularly where faults are not outlined by local seismicity. Passive seismic signatures of faults may arise from abrupt changes in lithology or foliation orientation in the upper crust, and from mylonitic shear zones at greater depths. Faults and shear zones with less than near-vertical dip lend themselves to detection with teleseismic mode-converted waves (receiver functions) provided that they have either a contrast in isotropic shear velocity ( V s), or a contrast in orientation or strength of anisotropic compressional velocity ( V p). We introduce a detection method for faults and shear zones based on receiver functions. We use synthetic seismograms to demonstrate common features of dipping isotropic interfaces and contrasts in dipping foliation that allows determination of their strike and depth without making further assumptions about the model. We proceed with two applications. We first image a Laramide thrust fault in the western U.S. (the Wind River thrust fault) as a steeply dipping isotropic velocity contrast in the middle crust near the surface trace of the fault; further downdip and across the range, where basin geometry suggests the fault may sole into a subhorizontal shear zone, we identify a candidate shear zone signal from midcrustal depths. The second application is the use of microstructural data from exhumed ductile shear zones in Scotland and in the western Canadian Shield to predict the character of seismic signatures of present-day deep crustal shear zones. Realistic anisotropy in observed shear fabrics generates a signal in receiver functions that is comparable in amplitude to first-order features like the Moho. Observables that can be robustly constrained without

  7. Inter-individual variation in fronto-temporal connectivity predicts the ability to learn different types of associations.

    PubMed

    Alm, Kylie H; Rolheiser, Tyler; Olson, Ingrid R

    2016-05-15

    The uncinate fasciculus connects portions of the anterior and medial temporal lobes to the lateral orbitofrontal cortex, so it has long been thought that this limbic fiber pathway plays an important role in episodic memory. Some types of episodic memory are impaired after damage to the uncinate, while others remain intact. Because of this, the specific role played by the uncinate fasciculus in episodic memory remains undetermined. In the present study, we tested the hypothesis that the uncinate fasciculus is involved in episodic memory tasks that have high competition between representations at retrieval. To test this hypothesis, healthy young adults performed three tasks: Experiment 1 in which they learned to associate names with faces through feedback provided at the end of each trial; Experiment 2 in which they learned to associate fractals with cued locations through feedback provided at the end of each trial; and Experiment 3 in which unique faces were remembered in a paradigm with low retrieval competition. Diffusion tensor imaging and deterministic tractography methods were used to extract measures of uncinate fasciculus microstructure. Results revealed that microstructural properties of the uncinate, but not a control tract, the inferior longitudinal fasciculus, significantly predicted individual differences in performance on the face-name and fractal-location tasks. However, no relationship was observed for simple face memory (Experiment 3). These findings suggest that the uncinate fasciculus may be important for adjudicating between competing memory representations at the time of episodic retrieval. PMID:26908315

  8. Performance of DFT+U method for prediction of structural and thermodynamic parameters of monazite-type ceramics.

    PubMed

    Blanca Romero, Ariadna; Kowalski, Piotr M; Beridze, George; Schlenz, Hartmut; Bosbach, Dirk

    2014-07-01

    We performed a density functional theory (DFT) study of the monazite-type ceramics using DFT+U method, where the Hubbard U parameters are derived ab initio, with the main goal in testing the predictive power of this computational method for modeling of f-electron materials that are of interest in nuclear waste management. We show that DFT+U approach with PBEsol as the exchange-correlation functional significantly improves description of structures and thermodynamic parameters of lanthanide-bearing oxides and monazites over commonly used standard DFT (PBE) approach. We found that it is essential to use the Hubbard U parameter derived for a given element and a given structure to reproduce the structural parameters of the measured materials. We obtained exceptionally good description of the structural parameters with U parameter derived using the linear response approach of Cococcioni and de Gironcoli (Phys. Rev. B 2005, 71, 035105). This shows that affordable methods, such as DFT+U with a clever choice of exchange-correlation functional and the Hubbard U parameter can lead to a good description of f-electron materials. PMID:24760757

  9. Flocculation of model algae under shear.

    SciTech Connect

    Pierce, Flint; Lechman, Jeremy B.

    2010-11-01

    We present results of molecular dynamics simulations of the flocculation of model algae particles under shear. We study the evolution of the cluster size distribution as well as the steady-state distribution as a function of shear rates and algae interaction parameters. Algal interactions are modeled through a DLVO-type potential, a combination of a HS colloid potential (Everaers) and a yukawa/colloid electrostatic potential. The effect of hydrodynamic interactions on aggregation is explored. Cluster strucuture is determined from the algae-algae radial distribution function as well as the structure factor. DLVO parameters including size, salt concentration, surface potential, initial volume fraction, etc. are varied to model different species of algae under a variety of environmental conditions.

  10. Recrystallization fabrics of sheared quartz veins with a strong pre-existing crystallographic preferred orientation from a seismogenic shear zone

    NASA Astrophysics Data System (ADS)

    Price, Nancy A.; Song, Won Joon; Johnson, Scott E.; Gerbi, Christopher C.; Beane, Rachel J.; West, David P.

    2016-07-01

    Microstructural investigations were carried out on quartz veins in schist, protomylonite, and mylonite samples from an ancient seismogenic strike-slip shear zone (Sandhill Corner shear zone, Norumbega fault system, Maine, USA). We interpret complexities in the microstructural record to show that: (1) pre-existing crystallographic preferred orientations (CPO) in the host rock may persist in the new CPO patterns of the shear zone and (2) the inner and outer parts of the shear zone followed diverging paths of fabric development. The host rocks bounding the shear zone contain asymmetrically-folded quartz veins with a strong CPO. These veins are increasingly deformed and recrystallized with proximity to the shear zone core. Matrix-accommodated rotation and recrystallization may position an inherited c-axis maximum in an orientation coincident with rhomb < a > or basal < a > slip. This inherited CPO likely persists in the shear zone fabric as a higher concentration of poles in one hemisphere of the c-axis pole figure, leading to asymmetric crossed girdle or paired maxima c-axis patterns about the foliation plane. Three observed quartz grain types indicate a general trend of localization with decreasing temperature: (1) large (> 100 μm), low aspect ratio (<~5) and (2) high aspect ratio (~ 5-20) grains overprinted by (3) smaller (<~80 μm), low aspect ratio (<~4) grains through subgrain rotation-dominated recrystallization. In the outer shear zone, subgrain rotation recrystallization led to a well-developed c-axis crossed girdle pattern. In the inner shear zone, the larger grains are completely overprinted by smaller grains, but the CPO patterns are relatively poorly developed and are associated with distinctively different misorientation angle histogram profiles ("flat" neighbor-pair profile with similar number fraction for angles from 10 to 90°). This may reflect the preferential activation of grain size sensitive deformation processes in the inner-most part of the

  11. Impacts of different plant functional types on ambient ozone predictions in the Seoul Metropolitan Areas (SMA), Korea

    NASA Astrophysics Data System (ADS)

    Kim, H.-K.; Woo, J.-H.; Park, R. S.; Song, C. H.; Kim, J.-H.; Ban, S.-J.; Park, J.-H.

    2013-09-01

    Plant functional type (PFT) distributions affect the results of biogenic emission modeling as well as O3 and PM simulations using chemistry-transport models (CTMs). This paper analyzes the variations of both surface biogenic VOC emissions and O3 concentrations due to changes in the PFT distributions in the Seoul Metropolitan Areas, Korea. Also, this paper attempts to provide important implications for biogenic emissions modeling studies for CTM simulations. MM5-MEGAN-SMOKE-CMAQ model simulations were implemented over the Seoul Metropolitan Areas in Korea to predict surface O3 concentrations for the period of 1 May to 31 June 2008. Starting from MEGAN biogenic emissions analysis with three different sources of PFT input data, US EPA CMAQ O3 simulation results were evaluated by surface O3 monitoring datasets and further considered on the basis of geospatial and statistical analyses. The three PFT datasets considered were "(1)KORPFT", developed with a region specific vegetation database; (2) CDP, adopted from US NCAR; and (3) MODIS, reclassified from the NASA Terra and Aqua combined land cover products. Comparisons of MEGAN biogenic emission results with the three different PFT data showed that broadleaf trees (BT) are the most significant contributor, followed by needleleaf trees (NT), shrub (SB), and herbaceous plants (HB) to the total biogenic volatile organic compounds (BVOCs). In addition, isoprene from BT and terpene from NT were recognized as significant primary and secondary BVOC species in terms of BVOC emissions distributions and O3-forming potentials in the study domain. Multiple regression analyses with the different PFT data (δO3 vs. δPFTs) suggest that KORPFT can provide reasonable information to the framework of MEGAN biogenic emissions modeling and CTM O3 predictions. Analyses of the CMAQ performance statistics suggest that deviations of BT areas can significantly affect CMAQ isoprene and O3 predictions. From further evaluations of the isoprene and O

  12. Wave anisotropy of shear viscosity and elasticity

    NASA Astrophysics Data System (ADS)

    Rudenko, O. V.; Sarvazyan, A. P.

    2014-11-01

    The paper presents the theory of shear wave propagation in a "soft solid" material possessing anisotropy of elastic and dissipative properties. The theory is developed mainly for understanding the nature of the low-frequency acoustic characteristics of skeletal muscles, which carry important diagnostic information on the functional state of muscles and their pathologies. It is shown that the shear elasticity of muscles is determined by two independent moduli. The dissipative properties are determined by the fourth-rank viscosity tensor, which also has two independent components. The propagation velocity and attenuation of shear waves in muscle depend on the relative orientation of three vectors: the wave vector, the polarization vector, and the direction of muscle fiber. For one of the many experiments where attention was distinctly focused on the vector character of the wave process, it was possible to make a comparison with the theory, estimate the elasticity moduli, and obtain agreement with the angular dependence of the wave propagation velocity predicted by the theory.

  13. Smectic Edge Dislocations under Shear

    NASA Astrophysics Data System (ADS)

    Chen, Peilong; Lu, Chun-Yi David

    2011-09-01

    Layer structures around an edge dislocation in a smectic phase under shear are studied with both phase field and order parameter models. It is shown that, contrast to a crystal solid, the conventional picture of the Peach--Koehler force experienced by dislocations when the sample is under a shear stress cannot be readily applied to the smectic phases. Under a uniform shear flow, we obtain the phase field and order parameter solutions around an edge dislocation. The solutions elucidate properties such as the layer distortion range around the dislocation and scaling of inter-dislocation interaction on dislocation separation. Calculations on energy dissipation indicate the extreme shear-thinning behavior that an edge dislocation induces a shear stress independent of the shear rate. Finally in a bulk sample with dislocation forming loops and networks, we argue that the uniform flow component around the dislocation is important to the energy dissipation and we show that its scaling exponent with the shear rate is very close to results from many previous rheology measurements.

  14. Surface temperatures and glassy state investigations in tribology, part 3. [limiting shear stress rheological model

    NASA Technical Reports Server (NTRS)

    Bair, S.; Winer, W. O.

    1980-01-01

    Research related to the development of the limiting shear stress rheological model is reported. Techniques were developed for subjecting lubricants to isothermal compression in order to obtain relevant determinations of the limiting shear stress and elastic shear modulus. The isothermal compression limiting shear stress was found to predict very well the maximum traction for a given lubricant. Small amounts of side slip and twist incorporated in the model were shown to have great influence on the rising portion of the traction curve at low slide-roll ratio. The shear rheological model was also applied to a Grubin-like elastohydrodynamic inlet analysis for predicting film thicknesses when employing the limiting shear stress model material behavior.

  15. Multidirectional direct simple shear apparatus

    SciTech Connect

    DeGroot, D.J.; Germaine, J.T.; Ladd, C.C.

    1993-09-01

    The paper describes a new simple shear testing device, the multidirectional direct simple shear (MDSS) apparatus, for testing soil specimens under conditions that simulate, at the element level, the state of stress acting within the foundation soil of an offshore Arctic gravity structure. The MDSS uses a circular specimen that is consolidated under both a vertical effective stress ({sigma}{sub vc}{prime}) and a horizontal shear stress ({tau}{sub 1}). The specimen is subsequently sheared undrained by applying a second independent horizontal shear stress ({tau}{sub 2}) at an angle {theta} relative to the horizontal consolidation shear stress {tau}{sub 1}. Evaluation of the MDSS first compares conventional K{sub D}-consolidated undrained direct simple shear (CK{sub 0}UDSS) test data ({tau}{sub 1} = 0) on normally consolidated Boston blue clay (BBC) with results obtained in the Geonor DSS device. The MDSS gives lower secant Young`s modulus values and on average 8% lower strengths, but produces remarkably less scatter in the test results than the Geonor DSS. Kinematic proof tests with an elastic material (rubber) confirm that the setup procedure, application of forces, and strain measurement systems in the MDSS work properly and produce repeatable results. Results from a MDSS test program on BBC wherein specimens were first normally consolidated with {sigma}{sub vc}{prime} and {tau}{sub 1} = 0.2{sigma}{sub vc}{prime} and then sheared undrained at {theta} varing in 30{degree} increments from zero (shear in same direction) to 150{degree} show dramatic differences in the response of the soil as a function of {theta}. The peak undrained strength varies almost twofold from 0 = 0 to 120{degree}, while the deformation behavior varies from very brittle at low {theta} angles to becoming ductile at higher angles. 11 refs., 15 figs.

  16. Effects of Fluid Shear Stress on Cancer Stem Cell Viability

    NASA Astrophysics Data System (ADS)

    Sunday, Brittney; Triantafillu, Ursula; Domier, Ria; Kim, Yonghyun

    2014-11-01

    Cancer stem cells (CSCs), which are believed to be the source of tumor formation, are exposed to fluid shear stress as a result of blood flow within the blood vessels. It was theorized that CSCs would be less susceptible to cell death than non-CSCs after both types of cell were exposed to a fluid shear stress, and that higher levels of fluid shear stress would result in lower levels of cell viability for both cell types. To test this hypothesis, U87 glioblastoma cells were cultured adherently (containing smaller populations of CSCs) and spherically (containing larger populations of CSCs). They were exposed to fluid shear stress in a simulated blood flow through a 125-micrometer diameter polyetheretherketone (PEEK) tubing using a syringe pump. After exposure, cell viability data was collected using a BioRad TC20 Automated Cell Counter. Each cell type was tested at three physiological shear stress values: 5, 20, and 60 dynes per centimeter squared. In general, it was found that the CSC-enriched U87 sphere cells had higher cell viability than the CSC-depleted U87 adherent cancer cells. Interestingly, it was also observed that the cell viability was not negatively affected by the higher fluid shear stress values in the tested range. In future follow-up studies, higher shear stresses will be tested. Furthermore, CSCs from different tumor origins (e.g. breast tumor, prostate tumor) will be tested to determine cell-specific shear sensitivity. National Science Foundation Grant #1358991 supported the first author as an REU student.

  17. Yielding of colloidal gels under steady and oscillatory shear

    NASA Astrophysics Data System (ADS)

    Petekidis, George; Moghimi, Esmaeel; Koumakis, Nick; Forth Team

    2015-03-01

    The structural and rheological properties of intermediate volume fraction colloid polymer gels are examined during and after steady and oscillatory shear flow using rheometry, confocal microscopy, light scattering and Brownian Dynamics simulations. Our main objective is to rationalize the microscopic mechanisms through which one can tune the mechanical properties of such metastable colloidal gels by imposing different types of external shear and flow. Experimentally, the gels consist of model hard sphere particle dispersions of φ = 0.44 with the addition of non-adsorbing linear chains, while BD simulations are conducted for hard spheres with the superposition of an AO potential for depletion attractions. Structural analysis shows that variation of the applied shear rate produces strong changes in the structure of the gels both when under shear and during gel reformation at cessation. Larger rates are characterized by disperse particles and the total breakage of structures at rest, which after cessation evolve with time into strong solids with relatively homogeneous structures. However, smaller rates show large inhomogeneous structures under flow, which do not evolve after cessation and additionally exhibit reduced elasticity and as such are weaker solids. Furthermore oscillatory shear is far more efficient than steady shear creating gels with stronger differences in their elastic modulus. Thus by tuning the way a gel is sheared, one may vary the final strength and structure of the resulting gel. Work in collaboration with R. Besseling, W. C. K. Poon and J. F. Brady

  18. Pure shear and simple shear calcite textures. Comparison of experimental, theoretical and natural data

    USGS Publications Warehouse

    Wenk, H.-R.; Takeshita, T.; Bechler, E.; Erskine, B.G.; Matthies, S.

    1987-01-01

    The pattern of lattice preferred orientation (texture) in deformed rocks is an expression of the strain path and the acting deformation mechanisms. A first indication about the strain path is given by the symmetry of pole figures: coaxial deformation produces orthorhombic pole figures, while non-coaxial deformation yields monoclinic or triclinic pole figures. More quantitative information about the strain history can be obtained by comparing natural textures with experimental ones and with theoretical models. For this comparison, a representation in the sensitive three-dimensional orientation distribution space is extremely important and efforts are made to explain this concept. We have been investigating differences between pure shear and simple shear deformation incarbonate rocks and have found considerable agreement between textures produced in plane strain experiments and predictions based on the Taylor model. We were able to simulate the observed changes with strain history (coaxial vs non-coaxial) and the profound texture transition which occurs with increasing temperature. Two natural calcite textures were then selected which we interpreted by comparing them with the experimental and theoretical results. A marble from the Santa Rosa mylonite zone in southern California displays orthorhombic pole figures with patterns consistent with low temperature deformation in pure shear. A limestone from the Tanque Verde detachment fault in Arizona has a monoclinic fabric from which we can interpret that 60% of the deformation occurred by simple shear. ?? 1987.

  19. Epitope Predictions Indicate the Presence of Two Distinct Types of Epitope-Antibody-Reactivities Determined by Epitope Profiling of Intravenous Immunoglobulins

    PubMed Central

    Luštrek, Mitja; Lorenz, Peter; Kreutzer, Michael; Qian, Zilliang; Steinbeck, Felix; Wu, Di; Born, Nadine; Ziems, Bjoern; Hecker, Michael; Blank, Miri; Shoenfeld, Yehuda; Cao, Zhiwei; Glocker, Michael O.; Li, Yixue; Fuellen, Georg; Thiesen, Hans-Jürgen

    2013-01-01

    Epitope-antibody-reactivities (EAR) of intravenous immunoglobulins (IVIGs) determined for 75,534 peptides by microarray analysis demonstrate that roughly 9% of peptides derived from 870 different human protein sequences react with antibodies present in IVIG. Computational prediction of linear B cell epitopes was conducted using machine learning with an ensemble of classifiers in combination with position weight matrix (PWM) analysis. Machine learning slightly outperformed PWM with area under the curve (AUC) of 0.884 vs. 0.849. Two different types of epitope-antibody recognition-modes (Type I EAR and Type II EAR) were found. Peptides of Type I EAR are high in tyrosine, tryptophan and phenylalanine, and low in asparagine, glutamine and glutamic acid residues, whereas for peptides of Type II EAR it is the other way around. Representative crystal structures present in the Protein Data Bank (PDB) of Type I EAR are PDB 1TZI and PDB 2DD8, while PDB 2FD6 and 2J4W are typical for Type II EAR. Type I EAR peptides share predicted propensities for being presented by MHC class I and class II complexes. The latter interaction possibly favors T cell-dependent antibody responses including IgG class switching. Peptides of Type II EAR are predicted not to be preferentially presented by MHC complexes, thus implying the involvement of T cell-independent IgG class switch mechanisms. The high extent of IgG immunoglobulin reactivity with human peptides implies that circulating IgG molecules are prone to bind to human protein/peptide structures under non-pathological, non-inflammatory conditions. A webserver for predicting EAR of peptide sequences is available at www.sysmed-immun.eu/EAR. PMID:24244326

  20. Soluble Urokinase-Type Plasminogen Activator Receptor Plasma Concentration May Predict Susceptibility to High Altitude Pulmonary Edema.

    PubMed

    Hilty, Matthias Peter; Zügel, Stefanie; Schoeb, Michele; Auinger, Katja; Dehnert, Christoph; Maggiorini, Marco

    2016-01-01

    Introduction. Acute exposure to high altitude induces inflammation. However, the relationship between inflammation and high altitude related illness such as high altitude pulmonary edema (HAPE) and acute mountain sickness (AMS) is poorly understood. We tested if soluble urokinase-type plasminogen activator receptor (suPAR) plasma concentration, a prognostic factor for cardiovascular disease and marker for low grade activation of leukocytes, will predict susceptibility to HAPE and AMS. Methods. 41 healthy mountaineers were examined at sea level (SL, 446 m) and 24 h after rapid ascent to 4559 m (HA). 24/41 subjects had a history of HAPE and were thus considered HAPE-susceptible (HAPE-s). Out of the latter, 10/24 HAPE-s subjects were randomly chosen to suppress the inflammatory cascade with dexamethasone 8 mg bid 24 h prior to ascent. Results. Acute hypoxic exposure led to an acute inflammatory reaction represented by an increase in suPAR (1.9 ± 0.4 at SL versus 2.3 ± 0.5 at HA, p < 0.01), CRP (0.7 ± 0.5 at SL versus 3.6 ± 4.6 at HA, p < 0.01), and IL-6 (0.8 ± 0.4 at SL versus 3.3 ± 4.9 at HA, p < 0.01) in all subjects except those receiving dexamethasone. The ascent associated decrease in PaO2 correlated with the increase in IL-6 (r = 0.46, p < 0.001), but not suPAR (r = 0.27, p = 0.08); the increase in IL-6 was not correlated with suPAR (r = 0.16, p = 0.24). Baseline suPAR plasma concentration was higher in the HAPE-s group (2.0 ± 0.4 versus 1.8 ± 0.4, p = 0.04); no difference was found for CRP and IL-6 and for subjects developing AMS. Conclusion. High altitude exposure leads to an increase in suPAR plasma concentration, with the missing correlation between suPAR and IL-6 suggesting a cytokine independent, leukocyte mediated mechanism of low grade inflammation. The correlation between IL-6 and PaO2 suggests a direct effect of hypoxia, which is not the case for suPAR. However, suPAR plasma concentration measured before hypoxic exposure may predict

  1. Soluble Urokinase-Type Plasminogen Activator Receptor Plasma Concentration May Predict Susceptibility to High Altitude Pulmonary Edema

    PubMed Central

    Zügel, Stefanie; Schoeb, Michele; Auinger, Katja; Dehnert, Christoph; Maggiorini, Marco

    2016-01-01

    Introduction. Acute exposure to high altitude induces inflammation. However, the relationship between inflammation and high altitude related illness such as high altitude pulmonary edema (HAPE) and acute mountain sickness (AMS) is poorly understood. We tested if soluble urokinase-type plasminogen activator receptor (suPAR) plasma concentration, a prognostic factor for cardiovascular disease and marker for low grade activation of leukocytes, will predict susceptibility to HAPE and AMS. Methods. 41 healthy mountaineers were examined at sea level (SL, 446 m) and 24 h after rapid ascent to 4559 m (HA). 24/41 subjects had a history of HAPE and were thus considered HAPE-susceptible (HAPE-s). Out of the latter, 10/24 HAPE-s subjects were randomly chosen to suppress the inflammatory cascade with dexamethasone 8 mg bid 24 h prior to ascent. Results. Acute hypoxic exposure led to an acute inflammatory reaction represented by an increase in suPAR (1.9 ± 0.4 at SL versus 2.3 ± 0.5 at HA, p < 0.01), CRP (0.7 ± 0.5 at SL versus 3.6 ± 4.6 at HA, p < 0.01), and IL-6 (0.8 ± 0.4 at SL versus 3.3 ± 4.9 at HA, p < 0.01) in all subjects except those receiving dexamethasone. The ascent associated decrease in PaO2 correlated with the increase in IL-6 (r = 0.46, p < 0.001), but not suPAR (r = 0.27, p = 0.08); the increase in IL-6 was not correlated with suPAR (r = 0.16, p = 0.24). Baseline suPAR plasma concentration was higher in the HAPE-s group (2.0 ± 0.4 versus 1.8 ± 0.4, p = 0.04); no difference was found for CRP and IL-6 and for subjects developing AMS. Conclusion. High altitude exposure leads to an increase in suPAR plasma concentration, with the missing correlation between suPAR and IL-6 suggesting a cytokine independent, leukocyte mediated mechanism of low grade inflammation. The correlation between IL-6 and PaO2 suggests a direct effect of hypoxia, which is not the case for suPAR. However, suPAR plasma concentration measured before hypoxic exposure may predict

  2. Usefulness of B-type Natriuretic Peptides to Predict Cardiovascular Events in Women (from the Women's Health Study).

    PubMed

    Everett, Brendan M; Ridker, Paul M; Cook, Nancy R; Pradhan, Aruna D

    2015-08-15

    Natriuretic peptides are positively associated with incident cardiovascular disease (CVD), but data in women, particularly with regard to improvements in risk prediction, are sparse. We measured the N-terminal prohormone form of B-type natriuretic peptide (NT-proBNP) in 480 cases of incident CVD (myocardial infarction, stroke, and cardiovascular death) and a reference subcohort of 564 women from the Women's Health Study who were followed for a median of 12.0 (interquartile range 7.6 to 13.4) years. Median (interquartile range) NT-proBNP concentrations were greater in women who developed CVD (81 ng/l [50 to 147]) than those who did not (64 ng/l [38 to 117]; p <0.0001). For women in the highest compared to the lowest quartile, NT-proBNP was 65% greater after adjusting for established cardiovascular risk factors and kidney function (adjusted hazard ratio [aHR] 1.65, 95% confidence interval [CI] 1.03 to 2.64, p trend = 0.03). When analyzed as a continuous variable, the aHR per 1 - SD difference in Ln(NT-proBNP) was 1.22 (1.03 to 1.44; p = 0.02). The per 1 - SD change in Ln(NT-proBNP) appeared stronger for cardiovascular death (aHR 1.43, 95% CI 1.05 to 1.94, p = 0.02) and stroke (aHR 1.24, 95% CI 1.03 to 1.50, p = 0.03) than myocardial infarction (aHR 1.09, 95% CI 0.87 to 1.37, p = 0.44). When added to traditional risk co-variables, NT-proBNP did not significantly improve the C-statistic (0.751 to 0.757; p = 0.09) or net reclassification into <5%, 5 to <7.5%, and ≥7.5% 10-year CVD risk categories (0.014; p = 0.18). In conclusion, in this prospective study of initially healthy women, NT-proBNP concentrations showed statistically significant association with incident CVD that was independent of traditional cardiovascular risk factors but did not substantially improve measures of CVD risk prediction. PMID:26081066

  3. Shear Banding of Complex Fluids

    NASA Astrophysics Data System (ADS)

    Divoux, Thibaut; Fardin, Marc A.; Manneville, Sebastien; Lerouge, Sandra

    2016-01-01

    Even in simple geometries, many complex fluids display nontrivial flow fields, with regions where shear is concentrated. The possibility for such shear banding has been known for several decades, but in recent years, we have seen an upsurge in studies offering an ever-more precise understanding of the phenomenon. The development of new techniques to probe the flow on multiple scales with increasing spatial and temporal resolution has opened the possibility for a synthesis of the many phenomena that could only have been thought of separately before. In this review, we bring together recent research on shear banding in polymeric and soft glassy materials and highlight their similarities and disparities.

  4. Fluid-Assisted Shear Failure Within a Ductile Shear Zone

    NASA Astrophysics Data System (ADS)

    Kirkpatrick, J. D.; Compton, K.; Holk, G. J.

    2015-12-01

    Exhumed shear zones often contain folded and/or dynamically recrystallized structures such as veins and pseudotachylytes that record contemporaneous brittle and ductile deformation representing mixed bulk rheology. Here, we constrain the conditions that promote the transitions between ductile and brittle deformation by investigating quartz veins with shear offsets in the Saddlebag Lake shear zone in the central Sierra Nevada, California. Mesozoic metasedimentary rocks within the shear zone contain transposed bedding, strong cleavage, dextrally rotated porphyroclasts, and a steep mineral lineation, which together suggest an overall transpressive kinematic regime for the ductile deformation. Foliation sub-parallel veins are one subset of the veins in the shear zone. They have observed horizontal trace lengths of up to around 5 meters, though most are obscured by limited exposure, and displacements range from ~3-30 mm, with 1-5 mm of opening. Foliation sub-parallel veins are folded with the foliation and quartz microstructures and fluid inclusion thermobarometry measurements from vein samples indicate temperatures during vein formation by fracture were between 300-680°C. Quartz δ18O values (+5.9 to +16.5) suggest extended fluid-rock interaction that involved magmatic (δ18O ~ +8 to +10) and meteoric (δ18O down to -1) fluids. Foliation sub-parallel veins are most abundant in relatively massive, quartz-rich rocks where they are boudinaged, indicating they were rigid inclusions after formation. Based on the orientation and spatial distribution of the veins, we infer that they formed under high differential stress with pore pressures sufficiently high for the rocks to be critically stressed for shear failure along mechanically weak foliation planes. These observations suggest high pore pressures and mechanical heterogeneity at a variety of scales are necessary conditions for nucleation of shear fractures within ductile shear zones.

  5. An improved shear beam method for the characterization of bonded composite joints

    NASA Technical Reports Server (NTRS)

    Hiel, Clem C.; Brinson, Hal F.

    1989-01-01

    Closed-form analytical solutions, which govern the displacements and stresses in an adhesive shear beam, are discussed. The remarkable precision with which the shear stresses in the adhesive can be predicted forms the basis of the proposed characterization procedure. The shear modulus of the adhesive is obtained by means of a parameter estimation procedure which requires a symbiosis of theoretical and experimental stress analysis.

  6. A microcomputer-based data acquisition and control system for the direct shear, ring shear, triaxial shear, and consolidation tests

    USGS Publications Warehouse

    Powers, Philip S.

    1983-01-01

    This report is intended to provide internal documentation for the U.S. Geological Survey laboratory's automatic data acquisition system. The operating procedures for each type of test are designed to independently lead a first-time user through the various stages of using the computer to control the test. Continuing advances in computer technology and the availability of desktop microcomputers with a wide variety of peripheral equipment at a reasonable cost can create an efficient automated geotechnical testing environment. A geotechnical testing environment is shown in figure 1. Using an automatic data acquisition system, laboratory test data from a variety of sensors can be collected, and manually or automatically recorded on a magnetic device at the same apparent time. The responses of a test can be displayed graphically on a CRT in a matter of seconds, giving the investigator an opportunity to evaluate the test data, and to make timely, informed decisions on such matters as whether to continue testing, abandon a test, or modify procedures. Data can be retrieved and results reported in tabular form, or graphic plots, suitable for publication. Thermistors, thermocouples, load cells, pressure transducers, and linear variable differential transformers are typical sensors which are incorporated in automated systems. The geotechnical tests which are most practical to automate are the long-term tests which often require readings to be recorded outside normal work hours and on weekends. Automation applications include incremental load consolidation tests, constant-rate-of-strain consolidation tests, direct shear tests, ring shear tests, and triaxial shear tests.

  7. Innovative biomarkers for predicting type 2 diabetes mellitus: relevance to dietary management of frailty in older adults.

    PubMed

    Ikwuobe, John; Bellary, Srikanth; Griffiths, Helen R

    2016-06-01

    Type 2 diabetes mellitus (T2DM) increases in prevalence in the elderly. There is evidence for significant muscle loss and accelerated cognitive impairment in older adults with T2DM; these comorbidities are critical features of frailty. In the early stages of T2DM, insulin sensitivity can be improved by a "healthy" diet. Management of insulin resistance by diet in people over 65 years of age should be carefully re-evaluated because of the risk for falling due to hypoglycaemia. To date, an optimal dietary programme for older adults with insulin resistance and T2DM has not been described. The use of biomarkers to identify those at risk for T2DM will enable clinicians to offer early dietary advice that will delay onset of disease and of frailty. Here we have used an in silico literature search for putative novel biomarkers of T2DM risk and frailty. We suggest that plasma bilirubin, plasma, urinary DPP4-positive microparticles and plasma pigment epithelium-derived factor merit further investigation as predictive biomarkers for T2DM and frailty risk in older adults. Bilirubin is screened routinely in clinical practice. Measurement of specific microparticle frequency in urine is less invasive than a blood sample so is a good choice for biomonitoring. Future studies should investigate whether early dietary changes, such as increased intake of whey protein and micronutrients that improve muscle function and insulin sensitivity, affect biomarkers and can reduce the longer term complication of frailty in people at risk for T2DM. PMID:26897532

  8. Shear instabilities in granular flows

    NASA Astrophysics Data System (ADS)

    Goldfarb, David J.; Glasser, Benjamin J.; Shinbrot, Troy

    2002-01-01

    Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial systems. Here we report that breaking waves can form at the interface between two streams of identical grains flowing on an inclined plane downstream of a splitter plate. Changes in either the shear rate or the angle of incline cause such waves to appear abruptly. We analyse a granular flow model that agrees qualitatively with our experimental data; the model suggests that the waves result from competition between shear and extensional strains in the flowing granular bed. We propose a dimensionless shear number that governs the transition between steady and wavy flows.

  9. Shear instabilities in granular flows.

    PubMed

    Goldfarb, David J; Glasser, Benjamin J; Shinbrot, Troy

    2002-01-17

    Unstable waves have been long studied in fluid shear layers. These waves affect transport in the atmosphere and oceans, in addition to slipstream stability behind ships, aeroplanes and heat-transfer devices. Corresponding instabilities in granular flows have not been previously documented, despite the importance of these flows in geophysical and industrial systems. Here we report that breaking waves can form at the interface between two streams of identical grains flowing on an inclined plane downstream of a splitter plate. Changes in either the shear rate or the angle of incline cause such waves to appear abruptly. We analyse a granular flow model that agrees qualitatively with our experimental data; the model suggests that the waves result from competition between shear and extensional strains in the flowing granular bed. We propose a dimensionless shear number that governs the transition between steady and wavy flows. PMID:11797003

  10. Proteins in a shear flow

    NASA Astrophysics Data System (ADS)

    Szymczak, P.; Cieplak, Marek

    2007-10-01

    The conformational dynamics of a single protein molecule in a shear flow is investigated using Brownian dynamics simulations. A structure-based coarse grained model of a protein is used. We consider two proteins, ubiquitin and integrin, and find that at moderate shear rates they unfold through a sequence of metastable states—a pattern which is distinct from a smooth unraveling found in homopolymers. Full unfolding occurs only at very large shear rates. Furthermore, the hydrodynamic interactions between the amino acids are shown to hinder the shear flow unfolding. The characteristics of the unfolding process depend on whether a protein is anchored or not, and if it is, on the choice of an anchoring point.

  11. Grafted polymer under shear flow

    NASA Astrophysics Data System (ADS)

    Kumar, Sanjiv; Foster, Damien P.; Giri, Debaprasad; Kumar, Sanjay

    2016-04-01

    A self-attracting-self-avoiding walk model of polymer chain on a square lattice has been used to gain an insight into the behaviour of a polymer chain under shear flow in a slit of width L. Using exact enumeration technique, we show that at high temperature, the polymer acquires the extended state continuously increasing with shear stress. However, at low temperature the polymer exhibits two transitions: a transition from the coiled to the globule state and a transition to a stem-flower like state. For a chain of finite length, we obtained the exact monomer density distributions across the layers at different temperatures. The change in density profile with shear stress suggests that the polymer under shear flow can be used as a molecular gate with potential application as a sensor.

  12. A piezoelectric shear stress sensor

    NASA Astrophysics Data System (ADS)

    Kim, Taeyang; Saini, Aditya; Kim, Jinwook; Gopalarathnam, Ashok; Zhu, Yong; Palmieri, Frank L.; Wohl, Christopher J.; Jiang, Xiaoning

    2016-04-01

    In this paper, a piezoelectric sensor with a floating element was developed for shear stress measurement. The piezoelectric sensor was designed to detect the pure shear stress, suppressing effects of normal stress components, by applying opposite poling vectors to the piezoelectric elements. The sensor was first calibrated in the lab by applying shear forces where it demonstrated high sensitivity to shear stress (91.3 +/- 2.1 pC/Pa) due to the high piezoelectric coefficients of 0.67Pb(Mg1/3Nb2/3)O3-0.33PbTiO3 (PMN-33%PT, d31=-1330 pC/N). The sensor also exhibited negligible sensitivity to normal stress (less than 1.2 pC/Pa) because of the electromechanical symmetry of the device. The usable frequency range of the sensor is up to 800 Hz.

  13. Cosmic Shear from Galaxy Spins.

    PubMed

    Lee; Pen

    2000-03-20

    We discuss the origin of galactic angular momentum and the statistics of the present-day spin distribution. It is expected that the galaxy spin axes are correlated with the intermediate principal axis of the gravitational shear tensor. This allows one to reconstruct the shear field and thereby the full gravitational potential from the observed galaxy spin fields. We use the direction of the angular momentum vector without any information of its magnitude, which requires a measurement of the position angle and inclination on the sky of each disk galaxy. We present the maximum likelihood shear inversion procedure, which involves a constrained linear minimization. The theory is tested against numerical simulations. We find the correlation strength of nonlinear structures with the initial shear field and show that accurate large-scale density reconstructions are possible at the expected noise level. PMID:10702119

  14. Flexible Micropost Arrays for Shear Stress Measurement

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J.; Palmieri, Frank L.; Hopkins, John W.; Jackson, Allen M.; Connell, John W.; Lin, Yi; Cisotto, Alexxandra A.

    2015-01-01

    Increased fuel costs, heightened environmental protection requirements, and noise abatement continue to place drag reduction at the forefront of aerospace research priorities. Unfortunately, shortfalls still exist in the fundamental understanding of boundary-layer airflow over aerodynamic surfaces, especially regarding drag arising from skin friction. For example, there is insufficient availability of instrumentation to adequately characterize complex flows with strong pressure gradients, heat transfer, wall mass flux, three-dimensionality, separation, shock waves, and transient phenomena. One example is the acoustic liner efficacy on aircraft engine nacelle walls. Active measurement of shear stress in boundary layer airflow would enable a better understanding of how aircraft structure and flight dynamics affect skin friction. Current shear stress measurement techniques suffer from reliability, complexity, and airflow disruption, thereby compromising resultant shear stress data. The state-of-the-art for shear stress sensing uses indirect or direct measurement techniques. Indirect measurements (e.g., hot-wire, heat flux gages, oil interferometry, laser Doppler anemometry, small scale pressure drag surfaces, i.e., fences) require intricate knowledge of the studied flow, restrictive instrument arrangements, large surface areas, flow disruption, or seeding material; with smaller, higher bandwidth probes under development. Direct measurements involve strain displacement of a sensor element and require no prior knowledge of the flow. Unfortunately, conventional "floating" recessed components for direct measurements are mm to cm in size. Whispering gallery mode devices and Fiber Bragg Gratings are examples of recent additions to this type of sensor with much smaller (?m) sensor components. Direct detection techniques are often single point measurements and difficult to calibrate and implement in wind tunnel experiments. In addition, the wiring, packaging, and installation

  15. The underexpanded jet Mach disk and its associated shear layer

    NASA Astrophysics Data System (ADS)

    Edgington-Mitchell, Daniel; Honnery, Damon R.; Soria, Julio

    2014-09-01

    High resolution planar particle image velocimetry is used to measure turbulent quantities in the region downstream of the Mach disk in an axisymmetric underexpanded jet issuing from a convergent nozzle. The internal annular shear layer generated by the slip line emanating from the triple point is shown to persist across multiple shock cells downstream. A triple decomposition based on Proper Orthogonal Decomposition shows that the external helical structure associated with the screech tone generated by the jet exerts a strong influence on velocity fluctuations in the initial region of the annular shear layer. This influence manifests as the external vortices producing oscillatory motion of the Mach disk, and thus a forcing of the internal annular shear layer. The internal shear layer is characterized by a number of azimuthal modes of varying wavenumber and type, including both helical and axisymmetric modes. Finally, the possibility of a previously hypothesized recirculation region behind the Mach disk is investigated, with no evidence found to support its existence.

  16. Spontaneous formation of densely packed shear bands of rotating fragments.

    PubMed

    Åström, J A; Timonen, J

    2012-05-01

    Appearance of self-similar space-filling ball bearings has been suggested to provide the explanation for seismic gaps, shear weakness, and lack of detectable frictional heat formation in mature tectonic faults (shear zones). As the material in a shear zone fractures and grinds, it could be thought to eventually form a conformation that allows fragments to largely roll against each other without much sliding. This type of space-filling "ball bearing" can be constructed artificially, but so far how such delicate structures may appear spontaneously has remained unexplained. It is demonstrated here that first-principles simulations of granular packing with fragmenting grains indeed display spontaneous formation of shear bands with fragment conformations very similar to those of densely packed ball bearings. PMID:22644135

  17. Simulation of three-dimensional shear flow around a nozzle-afterbody at high speeds

    SciTech Connect

    Baysal, O.; Hoffman, W.B. )

    1992-06-01

    In this paper, turbulent shear flows at supersonic and hypersonic speeds around a nozzle-afterbody are simulated. The three-dimensional, Reynolds-averaged Navier-Stokes equations are solved by a finite-volume and implicit method. The convective and the pressure terms are differenced by an upwind-biased algorithm. The effect of turbulence is incorporated by a modified Baldwin-Lomax eddy viscosity model. The success of the standard Baldwin-Lomax model for this flow type is shown by comparing it to a laminar case. These modifications made to the model are also shown to improve flow prediction when compared to the standard Baldwin-Lomax model. These modifications to the model reflect the effects of high compressibility, multiple walls, vortices near walls, and turbulent memory effects in the shear layer. This numerically simulated complex flowfield includes a supersonic duct flow, a hypersonic flow over an external double corner, a flow through a non-axisymmetric, internal-external nozzle, and a three-dimensional shear layer. The specific application is for the flow around the nozzle-afterbody of a generic hypersonic vehicle powered by a scramjet engine. The computed pressure distributions compared favorably with the experimentally obtained surface and off-surface flow surveys.

  18. Turbulent shear control with oscillatory bubble injection

    NASA Astrophysics Data System (ADS)

    Park, Hyun Jin; Oishi, Yoshihiko; Tasaka, Yuji; Murai, Yuichi; Takeda, Yasushi

    2009-02-01

    It is known that injecting bubbles into shear flow can reduce the frictional drag. This method has advantages in comparison to others in simplicity of installation and also in environment. The amount of drag reduction by bubbles depends on the void fraction provided in the boundary layer. It means, however, that certain power must be consumed to generate bubbles in water, worsening the total power-saving performance. We propose oscillatory bubble injection technique to improve the performance in this study. In order to prove this idea of new type of drag reduction, velocity vector field and shear stress profile in a horizontal channel flow are measured by ultrasonic velocity profiler (UVP) and shear stress transducer, respectively. We measure the gas-liquid interface from the UVP signal, as well. This compound measurement with different principles leads to deeper understanding of bubble-originated drag reduction phenomena, in particular for unsteady process of boundary layer alternation. At these experiments, the results have demonstrated that the intermittency promotes the drag reduction more than normal continuous injection for the same void fraction supplied.

  19. A compressive failure model for anisotropic plates with a cutout under compressive and shear loads

    NASA Technical Reports Server (NTRS)

    Gurdal, Z.; Haftka, R. T.

    1986-01-01

    The paper introduces a failure model for laminated composite plates with a cutout under combined compressive and shear loads. The model is based on kinking failure of the load-carrying fibers around a cutout, and includes the effect of local shearing and compressive stresses. Comparison of predictions of the model with available experimental results for quasi-isotropic and orthotropic plates with a circular hole indicated a good agreement. Predictions for orthotropic plates under combined loading are compared with the predictions of a point-stress model. The present model indicates significant reductions in axial load-carrying capacity due to shearing loads for plates with principal axis of orthotropy oriented along the axial load direction. A gain in strength is achieved by rotating the axis of orthotropy to counteract the shearing stress, or by eliminating the compressive-shear deformation coupling.

  20. COMPARISON OF SHEAR STRENGTH OF CERAMIC JOINTS DETERMINED BY VARIOUS TEST METHODS WITH SMALL SPECIMENS

    SciTech Connect

    Katoh, Yutai; Kiggans Jr, James O; Khalifa, Hesham; Back, Christina A.; Hinoki, Tatsuya; Ferraris, Monica

    2015-01-01

    Four different shear test methods i.e. doubled notched shear test, asymmetrical four point bend test, Iosipescu test, and torsion test, were investigated for their ability to evaluate one standard SiC to SiC ceramic brittle joint while using small size specimens. Double notched shear test showed higher stress concentration at the notch base and a lower nominal shear strength. Both asymmetrical four point bend test and Iosipescu test utilized epoxy jointed metal extensors, which failed during test and caused misalignment and tensile type of failure. Torsion test can deliver true shear loading. However, base material failure was observed for the torsion joint samples in this study. None of the tests can successfully induce true shear failure of the joint because the joint is stronger and tougher than the SiC substrate. Torsion test appears to be promising because of the pure shear loading, less stress concentration, and easy alignment.

  1. Composite Interlaminar Shear Fracture Toughness, G(sub 2c): Shear Measurement of Sheer Myth?

    NASA Technical Reports Server (NTRS)

    OBrien, T. Kevin

    1997-01-01

    The concept of G2c as a measure of the interlaminar shear fracture toughness of a composite material is critically examined. In particular, it is argued that the apparent G2c as typically measured is inconsistent with the original definition of shear fracture. It is shown that interlaminar shear failure actually consists of tension failures in the resin rich layers between plies followed by the coalescence of ligaments created by these failures and not the sliding of two planes relative to one another that is assumed in fracture mechanics theory. Several strain energy release rate solutions are reviewed for delamination in composite laminates and structural components where failures have been experimentally documented. Failures typically occur at a location where the mode 1 component accounts for at least one half of the total G at failure. Hence, it is the mode I and mixed-mode interlaminar fracture toughness data that will be most useful in predicting delamination failure in composite components in service. Although apparent G2c measurements may prove useful for completeness of generating mixed-mode criteria, the accuracy of these measurements may have very little influence on the prediction of mixed-mode failures in most structural components.

  2. An experimental investigation for external RC shear wall applications

    NASA Astrophysics Data System (ADS)

    Kaltakci, M. Y.; Ozturk, M.; Arslan, M. H.

    2010-09-01

    The strength and rigidity of most reinforced concrete (RC) buildings in Turkey, which are frequently hit by destructive earthquakes, is not at a sufficient level. Therefore, the result of earthquakes is a significant loss of life and property. The strengthening method most commonly preferred for these type of RC buildings is the application of RC infilled walls (shear walls) in the frame openings of the building. However, since the whole building has to be emptied and additional heavy costs arise during this type of strengthening, users prefer not to strengthen their buildings despite the heavy risk they are exposed to. Therefore, it is necessary to develop easier-to-apply and more effective methods for the rapid strengthening of housing and the heavily-used public buildings which cannot be emptied during the strengthening process (such as hospitals and schools). This study empirically analyses the different methods of a new system which can meet this need. In this new system, named "external shear wall application", RC shear walls are applied on the external surface of the building, along the frame plane rather than in the building. To this end, 7 test samples in 1/2 and 1/3 geometrical scale were designed to analyse the efficiency of the strengthening technique where the shear wall leans on the frame from outside of the building (external shear wall application) and of the strengthening technique where a specific space is left between the frame and the external shear wall by using a coupling beam to connect elements (application of external shear wall with coupling beam). Test results showed that the maximum lateral load capacity, initial rigidity and energy dissipation behaviours of the samples strengthened with external shear wall were much better than those of the bare frames.

  3. Surface shear rheology of saponin adsorption layers.

    PubMed

    Golemanov, Konstantin; Tcholakova, Slavka; Denkov, Nikolai; Pelan, Edward; Stoyanov, Simeon D

    2012-08-21

    Saponins are a wide class of natural surfactants, with molecules containing a rigid hydrophobic group (triterpenoid or steroid), connected via glycoside bonds to hydrophilic oligosaccharide chains. These surfactants are very good foam stabiliziers and emulsifiers, and show a range of nontrivial biological activities. The molecular