An analysis of the massless planet approximation in transit light curve models

NASA Astrophysics Data System (ADS)

Millholland, Sarah; Ruch, Gerry

2015-08-01

Many extrasolar planet transit light curve models use the approximation of a massless planet. They approximate the planet as orbiting elliptically with the host star at the orbit’s focus instead of depicting the planet and star as both orbiting around a common center of mass. This approximation should generally be very good because the transit is a small fraction of the full-phase curve and the planet to stellar mass ratio is typically very small. However, to fully examine the legitimacy of this approximation, it is useful to perform a robust, all-parameter space-encompassing statistical comparison between the massless planet model and the more accurate model.Towards this goal, we establish two questions: (1) In what parameter domain is the approximation invalid? (2) If characterizing an exoplanetary system in this domain, what is the error of the parameter estimates when using the simplified model? We first address question (1). Given each parameter vector in a finite space, we can generate the simplified and more complete model curves. Associated with these model curves is a measure of the deviation between them, such as the root mean square (RMS). We use Gibbs sampling to generate a sample that is distributed according to the RMS surface. The high-density regions in the sample correspond to a large deviation between the models. To determine the domains of these high-density areas, we first employ the Ordering Points to Identify the Clustering Structure (OPTICS) algorithm. We then characterize the subclusters by performing the Patient Rule Induction Method (PRIM) on the transformed Principal Component spaces of each cluster. This process yields descriptors of the parameter domains with large discrepancies between the models.To consider question (2), we start by generating synthetic transit curve observations in the domains specified by the above analysis. We then derive the best-fit parameters of these synthetic light curves according to each model and examine the quality of agreement between the estimated parameters. Taken as a whole, these steps allow for a thorough analysis of the validity of the massless planet approximation.

A refinement of the combination equations for evaporation

USGS Publications Warehouse

Milly, P.C.D.

1991-01-01

Most combination equations for evaporation rely on a linear expansion of the saturation vapor-pressure curve around the air temperature. Because the temperature at the surface may differ from this temperature by several degrees, and because the saturation vapor-pressure curve is nonlinear, this approximation leads to a certain degree of error in those evaporation equations. It is possible, however, to introduce higher-order polynomial approximations for the saturation vapor-pressure curve and to derive a family of explicit equations for evaporation, having any desired degree of accuracy. Under the linear approximation, the new family of equations for evaporation reduces, in particular cases, to the combination equations of H. L. Penman (Natural evaporation from open water, bare soil and grass, Proc. R. Soc. London, Ser. A193, 120-145, 1948) and of subsequent workers. Comparison of the linear and quadratic approximations leads to a simple approximate expression for the error associated with the linear case. Equations based on the conventional linear approximation consistently underestimate evaporation, sometimes by a substantial amount. ?? 1991 Kluwer Academic Publishers.

Gene Scanning of an Internalin B Gene Fragment Using High-Resolution Melting Curve Analysis as a Tool for Rapid Typing of Listeria monocytogenes

PubMed Central

Pietzka, Ariane T.; Stöger, Anna; Huhulescu, Steliana; Allerberger, Franz; Ruppitsch, Werner

2011-01-01

The ability to accurately track Listeria monocytogenes strains involved in outbreaks is essential for control and prevention of listeriosis. Because current typing techniques are time-consuming, cost-intensive, technically demanding, and difficult to standardize, we developed a rapid and cost-effective method for typing of L. monocytogenes. In all, 172 clinical L. monocytogenes isolates and 20 isolates from culture collections were typed by high-resolution melting (HRM) curve analysis of a specific locus of the internalin B gene (inlB). All obtained HRM curve profiles were verified by sequence analysis. The 192 tested L. monocytogenes isolates yielded 15 specific HRM curve profiles. Sequence analysis revealed that these 15 HRM curve profiles correspond to 18 distinct inlB sequence types. The HRM curve profiles obtained correlated with the five phylogenetic groups I.1, I.2, II.1, II.2, and III. Thus, HRM curve analysis constitutes an inexpensive assay and represents an improvement in typing relative to classical serotyping or multiplex PCR typing protocols. This method provides a rapid and powerful screening tool for simultaneous preliminary typing of up to 384 samples in approximately 2 hours. PMID:21227395

Compression of contour data through exploiting curve-to-curve dependence

NASA Technical Reports Server (NTRS)

Yalabik, N.; Cooper, D. B.

1975-01-01

An approach to exploiting curve-to-curve dependencies in order to achieve high data compression is presented. One of the approaches to date of along curve compression through use of cubic spline approximation is taken and extended by investigating the additional compressibility achievable through curve-to-curve structure exploitation. One of the models under investigation is reported on.

Geometry of Quantum Computation with Qudits

PubMed Central

Luo, Ming-Xing; Chen, Xiu-Bo; Yang, Yi-Xian; Wang, Xiaojun

2014-01-01

The circuit complexity of quantum qubit system evolution as a primitive problem in quantum computation has been discussed widely. We investigate this problem in terms of qudit system. Using the Riemannian geometry the optimal quantum circuits are equivalent to the geodetic evolutions in specially curved parametrization of SU(dn). And the quantum circuit complexity is explicitly dependent of controllable approximation error bound. PMID:24509710

Spontaneous labor curves in women with pregnancies complicated by diabetes

PubMed Central

Timofeev, Julia; Huang, Chun-Chih; Singh, Jasbir; Driggers, Rita W.; Landy, Helain J.

2013-01-01

Objective To test the hypothesis that the first stage of labor will be longer in nulliparous and multiparous women with diabetes compared to non-diabetic counterparts. Methods A retrospective analysis was performed from 228,668 deliveries between 2002–2008 from the Consortium of Safe Labor (NICHD, NIH). Patients with spontaneous onset of labor from 37 0/7 – 41 6/7 weeks gestation were included (71,282) and classified as nulliparous or multiparous. Pregnancies were further subdivided regarding presence of preexisting diabetes (preDM) or gestational diabetes (GDM), and normal controls. Labor curves were created matching for body mass index (BMI) and neonatal birth weight. Statistical analysis was performed on descriptive variables using χ2 with significance designated as p<0.05. Results Among nulliparous patients, there were 118 women with preDM and 475 women with GDM; 25,771 patients served as normal controls. Among multiparous women, there were 311 with preDM and 1,079 with GDM and 43,528 in the control group. Although differences in dilatation rates were observed in nulliparous and multiparous women with and without diabetes, labor curves were similar between the subgroups when matched for maternal BMI and birth weight. Conclusions Labor curves of women with preDM and GDM approximate those of non-diabetics, regardless of BMI, birth weight, or parity. PMID:21955108

Comparison of three methods for wind turbine capacity factor estimation.

PubMed

Ditkovich, Y; Kuperman, A

2014-01-01

Three approaches to calculating capacity factor of fixed speed wind turbines are reviewed and compared using a case study. The first "quasiexact" approach utilizes discrete wind raw data (in the histogram form) and manufacturer-provided turbine power curve (also in discrete form) to numerically calculate the capacity factor. On the other hand, the second "analytic" approach employs a continuous probability distribution function, fitted to the wind data as well as continuous turbine power curve, resulting from double polynomial fitting of manufacturer-provided power curve data. The latter approach, while being an approximation, can be solved analytically thus providing a valuable insight into aspects, affecting the capacity factor. Moreover, several other merits of wind turbine performance may be derived based on the analytical approach. The third "approximate" approach, valid in case of Rayleigh winds only, employs a nonlinear approximation of the capacity factor versus average wind speed curve, only requiring rated power and rotor diameter of the turbine. It is shown that the results obtained by employing the three approaches are very close, enforcing the validity of the analytically derived approximations, which may be used for wind turbine performance evaluation.

Effect of advective flow in fractures and matrix diffusion on natural gas production

DOE PAGES

Karra, Satish; Makedonska, Nataliia; Viswanathan, Hari S.; ...

2015-10-12

Although hydraulic fracturing has been used for natural gas production for the past couple of decades, there are significant uncertainties about the underlying mechanisms behind the production curves that are seen in the field. A discrete fracture network based reservoir-scale work flow is used to identify the relative effect of flow of gas in fractures and matrix diffusion on the production curve. With realistic three dimensional representations of fracture network geometry and aperture variability, simulated production decline curves qualitatively resemble observed production decline curves. The high initial peak of the production curve is controlled by advective fracture flow of freemore » gas within the network and is sensitive to the fracture aperture variability. Matrix diffusion does not significantly affect the production decline curve in the first few years, but contributes to production after approximately 10 years. These results suggest that the initial flushing of gas-filled background fractures combined with highly heterogeneous flow paths to the production well are sufficient to explain observed initial production decline. Lastly, these results also suggest that matrix diffusion may support reduced production over longer time frames.« less

Numerical integration techniques for curved-element discretizations of molecule-solvent interfaces.

PubMed

Bardhan, Jaydeep P; Altman, Michael D; Willis, David J; Lippow, Shaun M; Tidor, Bruce; White, Jacob K

2007-07-07

Surface formulations of biophysical modeling problems offer attractive theoretical and computational properties. Numerical simulations based on these formulations usually begin with discretization of the surface under consideration; often, the surface is curved, possessing complicated structure and possibly singularities. Numerical simulations commonly are based on approximate, rather than exact, discretizations of these surfaces. To assess the strength of the dependence of simulation accuracy on the fidelity of surface representation, here methods were developed to model several important surface formulations using exact surface discretizations. Following and refining Zauhar's work [J. Comput.-Aided Mol. Des. 9, 149 (1995)], two classes of curved elements were defined that can exactly discretize the van der Waals, solvent-accessible, and solvent-excluded (molecular) surfaces. Numerical integration techniques are presented that can accurately evaluate nonsingular and singular integrals over these curved surfaces. After validating the exactness of the surface discretizations and demonstrating the correctness of the presented integration methods, a set of calculations are presented that compare the accuracy of approximate, planar-triangle-based discretizations and exact, curved-element-based simulations of surface-generalized-Born (sGB), surface-continuum van der Waals (scvdW), and boundary-element method (BEM) electrostatics problems. Results demonstrate that continuum electrostatic calculations with BEM using curved elements, piecewise-constant basis functions, and centroid collocation are nearly ten times more accurate than planar-triangle BEM for basis sets of comparable size. The sGB and scvdW calculations give exceptional accuracy even for the coarsest obtainable discretized surfaces. The extra accuracy is attributed to the exact representation of the solute-solvent interface; in contrast, commonly used planar-triangle discretizations can only offer improved approximations with increasing discretization and associated increases in computational resources. The results clearly demonstrate that the methods for approximate integration on an exact geometry are far more accurate than exact integration on an approximate geometry. A MATLAB implementation of the presented integration methods and sample data files containing curved-element discretizations of several small molecules are available online as supplemental material.

A Modified Formula of the First-order Approximation for Assessing the Contribution of Climate Change to Runoff Based on the Budyko Hypothesis

NASA Astrophysics Data System (ADS)

Liu, W.; Ning, T.; Han, X.

2015-12-01

The climate elasticity based on the Budyko curves has been widely used to evaluate the hydrological responses to climate change. The Mezentsev-Choudhury-Yang formula is one of the representative analytical equations for Budyko curves. Previous researches mostly used the variation of runoff (R) caused by the changes of annual precipitation (P) and potential evapotranspiration (ET0) as the hydrological response to climate change and evaluated it by a first-order approximation in a form of total differential, the major components of which include the partial derivatives of R to P and ET0, as well as climate elasticity on this basis. Based on analytic derivation and the characteristics of Budyko curves, this study proposed a modified formula of the first-order approximation to reduce the errors from the approximation. In the calculation of partial derivatives and climate elasticity, the values of P and ET0 were taken to the sum of their base values and half increments, respectively. The calculation was applied in 33 catchments of the Hai River basin in China and the results showed that the mean absolute value of relative error of approximated runoff change decreased from 8.4% to 0.4% and the maximum value, from 23.4% to 1.3%. Given the variation values of P, ET0 and the controlling parameter (n), the modified formula can exactly quantify the contributions of climate fluctuation and underlying surface change to runoff. Taking the Murray-Darling basin in Australia as an example of the contribution calculated by the modified formula, the reductions of mean annual runoff caused by changes of P, ET0 and n from 1895-1996 to 1997-2006 were 2.6, 0.6 and 2.9 mm, respectively, and the sum of them was 6.1 mm, which was completely consistent with the observed runoff. The modified formula of the first-order approximation proposed in this study can be not only used to assess the contributions of climate change to the runoff, but also widely used to analyze the effects of similar issues based on a certain functional relationship in hydrological and climate changes.

Effect of boundary representation on viscous, separated flows in a discontinuous-Galerkin Navier-Stokes solver

NASA Astrophysics Data System (ADS)

Nelson, Daniel A.; Jacobs, Gustaaf B.; Kopriva, David A.

2016-08-01

The effect of curved-boundary representation on the physics of the separated flow over a NACA 65(1)-412 airfoil is thoroughly investigated. A method is presented to approximate curved boundaries with a high-order discontinuous-Galerkin spectral element method for the solution of the Navier-Stokes equations. Multiblock quadrilateral element meshes are constructed with the grid generation software GridPro. The boundary of a NACA 65(1)-412 airfoil, defined by a cubic natural spline, is piecewise-approximated by isoparametric polynomial interpolants that represent the edges of boundary-fitted elements. Direct numerical simulation of the airfoil is performed on a coarse mesh and fine mesh with polynomial orders ranging from four to twelve. The accuracy of the curve fitting is investigated by comparing the flows computed on curved-sided meshes with those given by straight-sided meshes. Straight-sided meshes yield irregular wakes, whereas curved-sided meshes produce a regular Karman street wake. Straight-sided meshes also produce lower lift and higher viscous drag as compared with curved-sided meshes. When the mesh is refined by reducing the sizes of the elements, the lift decrease and viscous drag increase are less pronounced. The differences in the aerodynamic performance between the straight-sided meshes and the curved-sided meshes are concluded to be the result of artificial surface roughness introduced by the piecewise-linear boundary approximation provided by the straight-sided meshes.

Rational-Spline Subroutines

NASA Technical Reports Server (NTRS)

Schiess, James R.; Kerr, Patricia A.; Smith, Olivia C.

1988-01-01

Smooth curves drawn among plotted data easily. Rational-Spline Approximation with Automatic Tension Adjustment algorithm leads to flexible, smooth representation of experimental data. "Tension" denotes mathematical analog of mechanical tension in spline or other mechanical curve-fitting tool, and "spline" as denotes mathematical generalization of tool. Program differs from usual spline under tension, allows user to specify different values of tension between adjacent pairs of knots rather than constant tension over entire range of data. Subroutines use automatic adjustment scheme that varies tension parameter for each interval until maximum deviation of spline from line joining knots less than or equal to amount specified by user. Procedure frees user from drudgery of adjusting individual tension parameters while still giving control over local behavior of spline.

Shape Sensing a Morphed Wing with an Optical Fiber Bragg Grating

NASA Technical Reports Server (NTRS)

Tai, Hsiang

2005-01-01

We suggest using distributed fiber Bragg sensors systems which were developed locally at Langley Research Center carefully placed on the wing surface to collect strain component information at each location. Then we used the fact that the rate change of slope in the definition of linear strain is very small and can be treated as a constant. Thereby the strain distribution information of a morphed surface can be reduced into a distribution of local slope information of a flat surface. In other words a morphed curve surface is replaced by the collection of individual flat surface of different slope. By assembling the height of individual flat surface, the morphed curved surface can be approximated. A more sophisticated graphic routine can be utilized to restore the curved morphed surface. With this information, the morphed wing can be further adjusted and controlled. A numerical demonstration is presented.

Visual Tracking Using 3D Data and Region-Based Active Contours

DTIC Science & Technology

2016-09-28

adaptive control strategies which explicitly take uncertainty into account. Filtering methods ranging from the classical Kalman filters valid for...linear systems to the much more general particle filters also fit into this framework in a very natural manner. In particular, the particle filtering ...the number of samples required for accurate filtering increases with the dimension of the system noise. In our approach, we approximate curve

Numerical Integration Techniques for Curved-Element Discretizations of Molecule–Solvent Interfaces

PubMed Central

Bardhan, Jaydeep P.; Altman, Michael D.; Willis, David J.; Lippow, Shaun M.; Tidor, Bruce; White, Jacob K.

2012-01-01

Surface formulations of biophysical modeling problems offer attractive theoretical and computational properties. Numerical simulations based on these formulations usually begin with discretization of the surface under consideration; often, the surface is curved, possessing complicated structure and possibly singularities. Numerical simulations commonly are based on approximate, rather than exact, discretizations of these surfaces. To assess the strength of the dependence of simulation accuracy on the fidelity of surface representation, we have developed methods to model several important surface formulations using exact surface discretizations. Following and refining Zauhar’s work (J. Comp.-Aid. Mol. Des. 9:149-159, 1995), we define two classes of curved elements that can exactly discretize the van der Waals, solvent-accessible, and solvent-excluded (molecular) surfaces. We then present numerical integration techniques that can accurately evaluate nonsingular and singular integrals over these curved surfaces. After validating the exactness of the surface discretizations and demonstrating the correctness of the presented integration methods, we present a set of calculations that compare the accuracy of approximate, planar-triangle-based discretizations and exact, curved-element-based simulations of surface-generalized-Born (sGB), surface-continuum van der Waals (scvdW), and boundary-element method (BEM) electrostatics problems. Results demonstrate that continuum electrostatic calculations with BEM using curved elements, piecewise-constant basis functions, and centroid collocation are nearly ten times more accurate than planartriangle BEM for basis sets of comparable size. The sGB and scvdW calculations give exceptional accuracy even for the coarsest obtainable discretized surfaces. The extra accuracy is attributed to the exact representation of the solute–solvent interface; in contrast, commonly used planar-triangle discretizations can only offer improved approximations with increasing discretization and associated increases in computational resources. The results clearly demonstrate that our methods for approximate integration on an exact geometry are far more accurate than exact integration on an approximate geometry. A MATLAB implementation of the presented integration methods and sample data files containing curved-element discretizations of several small molecules are available online at http://web.mit.edu/tidor. PMID:17627358

Boundary curves of individual items in the distribution of total depressive symptom scores approximate an exponential pattern in a general population.

PubMed

Tomitaka, Shinichiro; Kawasaki, Yohei; Ide, Kazuki; Akutagawa, Maiko; Yamada, Hiroshi; Furukawa, Toshiaki A; Ono, Yutaka

2016-01-01

Previously, we proposed a model for ordinal scale scoring in which individual thresholds for each item constitute a distribution by each item. This lead us to hypothesize that the boundary curves of each depressive symptom score in the distribution of total depressive symptom scores follow a common mathematical model, which is expressed as the product of the frequency of the total depressive symptom scores and the probability of the cumulative distribution function of each item threshold. To verify this hypothesis, we investigated the boundary curves of the distribution of total depressive symptom scores in a general population. Data collected from 21,040 subjects who had completed the Center for Epidemiologic Studies Depression Scale (CES-D) questionnaire as part of a national Japanese survey were analyzed. The CES-D consists of 20 items (16 negative items and four positive items). The boundary curves of adjacent item scores in the distribution of total depressive symptom scores for the 16 negative items were analyzed using log-normal scales and curve fitting. The boundary curves of adjacent item scores for a given symptom approximated a common linear pattern on a log normal scale. Curve fitting showed that an exponential fit had a markedly higher coefficient of determination than either linear or quadratic fits. With negative affect items, the gap between the total score curve and boundary curve continuously increased with increasing total depressive symptom scores on a log-normal scale, whereas the boundary curves of positive affect items, which are not considered manifest variables of the latent trait, did not exhibit such increases in this gap. The results of the present study support the hypothesis that the boundary curves of each depressive symptom score in the distribution of total depressive symptom scores commonly follow the predicted mathematical model, which was verified to approximate an exponential mathematical pattern.

Boundary curves of individual items in the distribution of total depressive symptom scores approximate an exponential pattern in a general population

PubMed Central

Kawasaki, Yohei; Akutagawa, Maiko; Yamada, Hiroshi; Furukawa, Toshiaki A.; Ono, Yutaka

2016-01-01

Background Previously, we proposed a model for ordinal scale scoring in which individual thresholds for each item constitute a distribution by each item. This lead us to hypothesize that the boundary curves of each depressive symptom score in the distribution of total depressive symptom scores follow a common mathematical model, which is expressed as the product of the frequency of the total depressive symptom scores and the probability of the cumulative distribution function of each item threshold. To verify this hypothesis, we investigated the boundary curves of the distribution of total depressive symptom scores in a general population. Methods Data collected from 21,040 subjects who had completed the Center for Epidemiologic Studies Depression Scale (CES-D) questionnaire as part of a national Japanese survey were analyzed. The CES-D consists of 20 items (16 negative items and four positive items). The boundary curves of adjacent item scores in the distribution of total depressive symptom scores for the 16 negative items were analyzed using log-normal scales and curve fitting. Results The boundary curves of adjacent item scores for a given symptom approximated a common linear pattern on a log normal scale. Curve fitting showed that an exponential fit had a markedly higher coefficient of determination than either linear or quadratic fits. With negative affect items, the gap between the total score curve and boundary curve continuously increased with increasing total depressive symptom scores on a log-normal scale, whereas the boundary curves of positive affect items, which are not considered manifest variables of the latent trait, did not exhibit such increases in this gap. Discussion The results of the present study support the hypothesis that the boundary curves of each depressive symptom score in the distribution of total depressive symptom scores commonly follow the predicted mathematical model, which was verified to approximate an exponential mathematical pattern. PMID:27761346

Comparison of 1998 and 1999 Leonid Light Curve Morphology and Meteoroid Structure

NASA Technical Reports Server (NTRS)

Murray, Ian S.; Beech, Martin; Taylor, Michael J.; Jenniskens, Peter; Hawkes, Robert L.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

Photometric low-light level video observations of 1999 Leonid storm meteors have been obtained from airborne platforms during the Leonid multi-instrument aircraft campaign (Leonid MAC). The 1999 Leonid light curves tend to be skewed towards the end point of the trajectory, while the 1998 Leonid light curves were not. The variation in the light curves from 1998 and 1999 can be explained as an overall reduction in the mass distribution index, alpha from approximately 1.95 in 1998 to approximately 1.75 in 1999. We have interpreted this behavior as being either indicative of a gradual loss of the "glue" that keeps the grains together, or the fact that the meteoroids sampled in 1998 had a different morphological structure to those sampled in 1999. The early fragmentation of a dustball meteoroid results in a light curve that peaks sooner than that predicted by classical single body ablation theory.

Influence of air and water temperature on fill characteristics curve

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

Lefevre, M.R.

1985-01-01

In a previous paper, the author discussed approximations of the Merkel Theory, as well as other approximations included in the CTI recommended method of calculation of the Demand curves. The paper concluded that the familiar difference of enthalpies, used as a cooling potential, which is the Merkel Theory, could continue to be used by simply adding a corrective multiplying factor derived from a direct comparison of the exact theory and the Merkel Theory. At the end of the paper the author briefly showed that the corrections to the Demand curve was only one part of the picture and that theremore » was also an influence of the temperatures of the Characteristic curve side. The object of this paper is to now review the influence of the air and water temperature on the Characteristic curve. This completes the work presented last year.« less

Curve Modulation and Apex Migration Using Shilla Growth Guidance Rods for Early-onset Scoliosis at 5-Year Follow-up.

PubMed

Wilkinson, John T; Songy, Chad E; Bumpass, David B; McCullough, Francis L; McCarthy, Richard E

2017-04-03

The Shilla procedure was designed to correct and control early-onset spinal deformity while harnessing a child's remaining spinal growth. It allows for controlled axial skeletal growth within the construct, avoiding the need for frequent surgeries to lengthen implants. We hypothesized that curve characteristics evolve over time after initial apex fusion and placement of the Shilla implants. The purpose of this study was to identify trends in curve evolution after Shilla implantation and understand how these changes influence ultimate outcome. A single-center, retrospective review of all patients with Shilla implants in place for ≥5 years yielded 21 patients. Charts and radiographs were reviewed to compare coronal curve characteristics preoperatively, postoperatively, and at last follow-up to note changes in the apex of the primary curve. Also noted were the development of adjacent compensatory curves, the overall vertical spinal growth, and the need for definitive spinal fusion once skeletal maturity was reached. Of the 21 patients, the curve apex migrated caudally in 12 patients (57%) and cephalad in 1 patient (5%), with a mean migration of 2.7 vertebral levels. Two patients (10%) developed new, significant compensatory curves (1 caudal and 1 cephalad). All patients demonstrated spinal growth in T1-S1 length following index surgery (mean, 45 mm). At skeletal maturity, 10 patients underwent definitive posterior spinal fusion and instrumentation, and 3 underwent implant removal alone. This study constitutes the longest follow-up of Shilla patients evaluating curve and implant behavior. Results of this review suggest that the apex of the fused primary curve shifts in approximately 62% of patients, with nearly all of these (92%) involving a distal migration. Compensatory curves did develop after Shilla placement as well. Overall, these findings represent adding-on distal to the apex after Shilla instrumentation rather than a crankshaft phenomenon about the apex. A better understanding of spinal growth mechanics and outcomes after Shilla placement may improve our ability to appropriately select patients and instrumentation levels. Level III.

Statistical evaluation of the influence of the uncertainty budget on B-spline curve approximation

NASA Astrophysics Data System (ADS)

Zhao, Xin; Alkhatib, Hamza; Kargoll, Boris; Neumann, Ingo

2017-12-01

In the field of engineering geodesy, terrestrial laser scanning (TLS) has become a popular method for detecting deformations. This paper analyzes the influence of the uncertainty budget on free-form curves modeled by B-splines. Usually, free-form estimation is based on scanning points assumed to have equal accuracies, which is not realistic. Previous findings demonstrate that the residuals still contain random and systematic uncertainties caused by instrumental, object-related and atmospheric influences. In order to guarantee the quality of derived estimates, it is essential to be aware of all uncertainties and their impact on the estimation. In this paper, a more detailed uncertainty budget is considered, in the context of the "Guide to the Expression of Uncertainty in Measurement" (GUM), which leads to a refined, heteroskedastic variance covariance matrix (VCM) of TLS measurements. Furthermore, the control points of B-spline curves approximating a measured bridge are estimated. Comparisons are made between the estimated B-spline curves using on the one hand a homoskedastic VCM and on the other hand the refined VCM. To assess the statistical significance of the differences displayed by the estimates for the two stochastic models, a nested model misspecification test and a non-nested model selection test are described and applied. The test decisions indicate that the homoskedastic VCM should be replaced by a heteroskedastic VCM in the direction of the suggested VCM. However, the tests also indicate that the considered VCM is still inadequate in light of the given data set and should therefore be improved.

A study to mitigate rural high-speed horizontal curve crashes in Kansas.

DOT National Transportation Integrated Search

2015-05-01

Driving on horizontal curves is a more complicated task than on straight sections of a roadway, and poses more : workload on drivers as well. While a small portion of roadways are made up of horizontal curve sections, : approximately a quarter of all...

Prediction of dynamic and aerodynamic characteristics of the centrifugal fan with forward curved blades

NASA Astrophysics Data System (ADS)

Polanský, Jiří; Kalmár, László; Gášpár, Roman

2013-12-01

The main aim of this paper is determine the centrifugal fan with forward curved blades aerodynamic characteristics based on numerical modeling. Three variants of geometry were investigated. The first, basic "A" variant contains 12 blades. The geometry of second "B" variant contains 12 blades and 12 semi-blades with optimal length [1]. The third, control variant "C" contains 24 blades without semi-blades. Numerical calculations were performed by CFD Ansys. Another aim of this paper is to compare results of the numerical simulation with results of approximate numerical procedure. Applied approximate numerical procedure [2] is designated to determine characteristics of the turbulent flow in the bladed space of a centrifugal-flow fan impeller. This numerical method is an extension of the hydro-dynamical cascade theory for incompressible and inviscid fluid flow. Paper also partially compares results from the numerical simulation and results from the experimental investigation. Acoustic phenomena observed during experiment, during numerical simulation manifested as deterioration of the calculation stability, residuals oscillation and thus also as a flow field oscillation. Pressure pulsations are evaluated by using frequency analysis for each variant and working condition.

Effect of ultrasonic stimulation on particle transport and fate over different lengths of porous media

NASA Astrophysics Data System (ADS)

Chen, Xingxin; Wu, Zhonghan; Cai, Qipeng; Cao, Wei

2018-04-01

It is well established that seismic waves traveling through porous media stimulate fluid flow and accelerate particle transport. However, the mechanism remains poorly understood. To quantify the coupling effect of hydrodynamic force, transportation distance, and ultrasonic stimulation on particle transport and fate in porous media, laboratory experiments were conducted using custom-built ultrasonic-controlled soil column equipment. Three column lengths (23 cm, 33 cm, and 43 cm) were selected to examine the influence of transportation distance. Transport experiments were performed with 0 W, 600 W, 1000 W, 1400 W, and 1800 W of applied ultrasound, and flow rates of 0.065 cm/s, 0.130 cm/s, and 0.195 cm/s, to establish the roles of ultrasonic stimulation and hydrodynamic force. The laboratory results suggest that whilst ultrasonic stimulation does inhibit suspended-particle deposition and accelerate deposited-particle release, both hydrodynamic force and transportation distance are the principal controlling factors. The median particle diameter for the peak concentration was approximately 50% of that retained in the soil column. Simulated particle-breakthrough curves using extended traditional filtration theory effectively described the experimental curves, particularly the curves that exhibited a higher tailing concentration.

Management

Treesearch

L.J. Barrett

1934-01-01

The Station has received recent inquiries regarding site index curves for species other than the mixed hardwood stands for which such data are already available, The attached curves for second growth yellow poplar and white pine will be found suitable for approximate site determinations in the Southern Appachians. The white pine curves are based upon measurements of...

A NURBS-enhanced finite volume solver for steady Euler equations

NASA Astrophysics Data System (ADS)

Meng, Xucheng; Hu, Guanghui

2018-04-01

In Hu and Yi (2016) [20], a non-oscillatory k-exact reconstruction method was proposed towards the high-order finite volume methods for steady Euler equations, which successfully demonstrated the high-order behavior in the simulations. However, the degeneracy of the numerical accuracy of the approximate solutions to problems with curved boundary can be observed obviously. In this paper, the issue is resolved by introducing the Non-Uniform Rational B-splines (NURBS) method, i.e., with given discrete description of the computational domain, an approximate NURBS curve is reconstructed to provide quality quadrature information along the curved boundary. The advantages of using NURBS include i). both the numerical accuracy of the approximate solutions and convergence rate of the numerical methods are improved simultaneously, and ii). the NURBS curve generation is independent of other modules of the numerical framework, which makes its application very flexible. It is also shown in the paper that by introducing more elements along the normal direction for the reconstruction patch of the boundary element, significant improvement in the convergence to steady state can be achieved. The numerical examples confirm the above features very well.

Analysis of straw row in the image to control the trajectory of the agricultural combine harvester

NASA Astrophysics Data System (ADS)

Shkanaev, Aleksandr Yurievich; Polevoy, Dmitry Valerevich; Panchenko, Aleksei Vladimirovich; Krokhina, Darya Alekseevna; Nailevish, Sadekov Rinat

2018-04-01

The paper proposes a solution to the automatic operation of the combine harvester along the straw rows by means of the images from the camera, installed in the cab of the harvester. The U-Net is used to recognize straw rows in the image. The edges of the row are approximated in the segmented image by the curved lines and further converted into the harvester coordinate system for the automatic operating system. The "new" network architecture and approaches to the row approximation has improved the quality of the recognition task and the processing speed of the frames up to 96% and 7.5 fps, respectively. Keywords: Grain harvester,

Probability Density Functions of Observed Rainfall in Montana

NASA Technical Reports Server (NTRS)

Larsen, Scott D.; Johnson, L. Ronald; Smith, Paul L.

1995-01-01

The question of whether a rain rate probability density function (PDF) can vary uniformly between precipitation events is examined. Image analysis on large samples of radar echoes is possible because of advances in technology. The data provided by such an analysis easily allow development of radar reflectivity factors (and by extension rain rate) distribution. Finding a PDF becomes a matter of finding a function that describes the curve approximating the resulting distributions. Ideally, one PDF would exist for all cases; or many PDF's that have the same functional form with only systematic variations in parameters (such as size or shape) exist. Satisfying either of theses cases will, validate the theoretical basis of the Area Time Integral (ATI). Using the method of moments and Elderton's curve selection criteria, the Pearson Type 1 equation was identified as a potential fit for 89 percent of the observed distributions. Further analysis indicates that the Type 1 curve does approximate the shape of the distributions but quantitatively does not produce a great fit. Using the method of moments and Elderton's curve selection criteria, the Pearson Type 1 equation was identified as a potential fit for 89% of the observed distributions. Further analysis indicates that the Type 1 curve does approximate the shape of the distributions but quantitatively does not produce a great fit.

Microwave fixation versus formalin fixation of surgical and autopsy tissue.

PubMed

Login, G R

1978-05-01

Microwave irradiation of surgical and autopsy tissue penetrates, fixes, and hardens the tissue almost immediately (the fluid media used in the microwave consisted of saline, ten percent phosphate buffered formalin, and distilled water). Tissue sections from a representative sample of organs were tested. Comparable sections were simultaneously fixed in a phosphate buffered ten percent formalin bath in a vaccum oven as a control. Hematoxylin and eosin were used to stain the sections. Results equal to and superior to the control method were obtained. Saline microwave fixation was superior to formalin microwave fixation. Tissues placed in Zenker's solution and fixed in standard microwave oven (for approximately one minute) yielded results at least equal to conventional Zenker fixation (approximately two hours). No tissue hardening resulted from Zenker microwave fixation. A unique time versus temperature graph (microwave heating curve) reduces individual variation with this technique.

Approximations for column effect in airplane wing spars

NASA Technical Reports Server (NTRS)

Warner, Edward P; Short, Mac

1927-01-01

The significance attaching to "column effect" in airplane wing spars has been increasingly realized with the passage of time, but exact computations of the corrections to bending moment curves resulting from the existence of end loads are frequently omitted because of the additional labor involved in an analysis by rigorously correct methods. The present report represents an attempt to provide for approximate column effect corrections that can be graphically or otherwise expressed so as to be applied with a minimum of labor. Curves are plotted giving approximate values of the correction factors for single and two bay trusses of varying proportions and with various relationships between axial and lateral loads. It is further shown from an analysis of those curves that rough but useful approximations can be obtained from Perry's formula for corrected bending moment, with the assumed distance between points of inflection arbitrarily modified in accordance with rules given in the report. The discussion of general rules of variation of bending stress with axial load is accompanied by a study of the best distribution of the points of support along a spar for various conditions of loading.

Melting Curve of Molecular Crystal GeI4

NASA Astrophysics Data System (ADS)

Fuchizaki, Kazuhiro; Hamaya, Nozomu

2014-07-01

In situ synchrotron x-ray diffraction measurements were carried out to determine the melting curve of the molecular crystal GeI4. We found that the melting line rapidly increases with a pressure up to about 3 GPa, at which it abruptly breaks. Such a strong nonlinear shape of the melting curve can be approximately captured by the Kumari-Dass-Kechin equation. The parameters involved in the equation could be determined from the equation of state for the crystalline phase, which was also established in the present study. The melting curve predicted from the equation approaches the actual melting curve as the degree of approximation involved in obtaining the equation is improved. However, the treatment is justifiable only if the slope of the melting curve is everywhere continuous. We believe that this is not the case for GeI4's melting line at the breakpoint, as inferred from the nature of breakdown of the Kraut-Kennedy and the Magalinskii-Zubov relationships.The breakpoint may then be a triple point among the crystalline phase and two possible liquid phases.

Dual-porosity analysis of conservative tracer testing in saturated volcanic rocks at Yucca Mountain in Nye County, Nevada

USGS Publications Warehouse

Fahy, M.F.

1997-01-01

A radially convergent conservative tracer injection test was conducted between boreholes UE-25 #2 and UE-25 c #3 of the C-hole complex at Yucca Mountain to determine effective porosity and longitudinal dispersivity. Approximately 47% of the tracer mass was recovered and a dual-porosity analytical model replicates the breakthrough curve. Fractured-rock analyses focus on the fracture-porosity and geometry as the controlling factors in transport.

Data reduction using cubic rational B-splines

NASA Technical Reports Server (NTRS)

Chou, Jin J.; Piegl, Les A.

1992-01-01

A geometric method is proposed for fitting rational cubic B-spline curves to data that represent smooth curves including intersection or silhouette lines. The algorithm is based on the convex hull and the variation diminishing properties of Bezier/B-spline curves. The algorithm has the following structure: it tries to fit one Bezier segment to the entire data set and if it is impossible it subdivides the data set and reconsiders the subset. After accepting the subset the algorithm tries to find the longest run of points within a tolerance and then approximates this set with a Bezier cubic segment. The algorithm uses this procedure repeatedly to the rest of the data points until all points are fitted. It is concluded that the algorithm delivers fitting curves which approximate the data with high accuracy even in cases with large tolerances.

Joule-Thomson inversion curves and related coefficients for several simple fluids

NASA Technical Reports Server (NTRS)

Hendricks, R. C.; Peller, I. C.; Baron, A. K.

1972-01-01

The equations of state (PVT relations) for methane, oxygen, argon, carbon dioxide, carbon monoxide, neon, hydrogen, and helium were used to establish Joule-Thomson inversion curves for each fluid. The principle of corresponding states was applied to the inversion curves, and a generalized inversion curve for fluids with small acentric factors was developed. The quantum fluids (neon, hydrogen, and helium) were excluded from the generalization, but available data for the fluids xenon and krypton were included. The critical isenthalpic Joule-Thomson coefficient mu sub c was determined; and a simplified approximation mu sub c approximates T sub c divided by 6P sub c was found adequate, where T sub c and P sub c are the temperature and pressure at the thermodynamic critical point. The maximum inversion temperatures were obtained from the second virial coefficient (maximum (B/T)).

Cuckoo Search with Lévy Flights for Weighted Bayesian Energy Functional Optimization in Global-Support Curve Data Fitting

PubMed Central

Gálvez, Akemi; Iglesias, Andrés; Cabellos, Luis

2014-01-01

The problem of data fitting is very important in many theoretical and applied fields. In this paper, we consider the problem of optimizing a weighted Bayesian energy functional for data fitting by using global-support approximating curves. By global-support curves we mean curves expressed as a linear combination of basis functions whose support is the whole domain of the problem, as opposed to other common approaches in CAD/CAM and computer graphics driven by piecewise functions (such as B-splines and NURBS) that provide local control of the shape of the curve. Our method applies a powerful nature-inspired metaheuristic algorithm called cuckoo search, introduced recently to solve optimization problems. A major advantage of this method is its simplicity: cuckoo search requires only two parameters, many fewer than other metaheuristic approaches, so the parameter tuning becomes a very simple task. The paper shows that this new approach can be successfully used to solve our optimization problem. To check the performance of our approach, it has been applied to five illustrative examples of different types, including open and closed 2D and 3D curves that exhibit challenging features, such as cusps and self-intersections. Our results show that the method performs pretty well, being able to solve our minimization problem in an astonishingly straightforward way. PMID:24977175

Cuckoo search with Lévy flights for weighted Bayesian energy functional optimization in global-support curve data fitting.

PubMed

Gálvez, Akemi; Iglesias, Andrés; Cabellos, Luis

2014-01-01

The problem of data fitting is very important in many theoretical and applied fields. In this paper, we consider the problem of optimizing a weighted Bayesian energy functional for data fitting by using global-support approximating curves. By global-support curves we mean curves expressed as a linear combination of basis functions whose support is the whole domain of the problem, as opposed to other common approaches in CAD/CAM and computer graphics driven by piecewise functions (such as B-splines and NURBS) that provide local control of the shape of the curve. Our method applies a powerful nature-inspired metaheuristic algorithm called cuckoo search, introduced recently to solve optimization problems. A major advantage of this method is its simplicity: cuckoo search requires only two parameters, many fewer than other metaheuristic approaches, so the parameter tuning becomes a very simple task. The paper shows that this new approach can be successfully used to solve our optimization problem. To check the performance of our approach, it has been applied to five illustrative examples of different types, including open and closed 2D and 3D curves that exhibit challenging features, such as cusps and self-intersections. Our results show that the method performs pretty well, being able to solve our minimization problem in an astonishingly straightforward way.

INFLUENCE OF DEATH CRITERIA ON THE X-RAY SURVIVAL CURVES OF THE FUNGUS, NEUROSPORA

PubMed Central

Uber, Fred M.; Goddard, David R.

1934-01-01

1. When ascospores of Neurospora tetrasperma were irradiated with 11 kv. X-rays, the single spore cultures obtained displayed a wide variety of mutated forms. 2. Control germinations of ascospores showed uniform behavior, ranging from 92–95 per cent germination. 3. The shape of the survival curves was found to be a function of the criterion of death. The following criteria were used: germination, growth, production of mature ascospores, and the production of normal perithecia. 4. The germination survival curve exhibited a rhythmic variation with dosage. Germination is not a significant criterion of death. 5. Half-survival dosages for growth and ascospore production were approximately 30,000 and 20,000 roentgens, respectively. 6. Multiple hit-to-kill relations were found on the basis of the quantum hit theory; no accurate analysis was possible. 7. The studies indicate that ascospore death does not result from a single well defined reaction, but rather from the integrated effects of several deleterious processes initiated by the radiation. PMID:19872801

Spontaneous labor curves in women with pregnancies complicated by diabetes.

PubMed

Timofeev, Julia; Huang, Chun-Chih; Singh, Jasbir; Driggers, Rita W; Landy, Helain J

2012-01-01

To test the hypothesis that the first stage of labor will be longer in nulliparous and multiparous women with diabetes compared to non-diabetic counterparts. A retrospective analysis was performed from 228,668 deliveries between 2002-2008 from the Consortium of Safe Labor (National Institute of Child Health and Human Development, National Institutes of Health). Patients with spontaneous onset of labor from 37 0/7-41 6/7 weeks gestation were included (71,282) and classified as nulliparous or multiparous. Pregnancies were further subdivided regarding presence of preexisting diabetes (preDM) or gestational diabetes (GDM) and normal controls. Labor curves were created matching for body mass index (BMI) and neonatal birth weight. Statistical analysis was performed on descriptive variables using χ(2) with significance designated as p < 0.05. Among nulliparous patients, there were 118 women with preDM and 475 women with GDM; 25,771 patients served as normal controls. Among multiparous women, there were 311 with preDM, 1,079 with GDM and 43,528 in the control group. Although differences in dilatation rates were observed in nulliparous and multiparous women with and without diabetes, labor progression was similar between the subgroups when matched for maternal BMI and birth weight. Labor curves of women with preDM and GDM approximate those of non-diabetics, regardless of BMI, birth weight, or parity.

Evaluation of Strain-Life Fatigue Curve Estimation Methods and Their Application to a Direct-Quenched High-Strength Steel

NASA Astrophysics Data System (ADS)

Dabiri, M.; Ghafouri, M.; Rohani Raftar, H. R.; Björk, T.

2018-03-01

Methods to estimate the strain-life curve, which were divided into three categories: simple approximations, artificial neural network-based approaches and continuum damage mechanics models, were examined, and their accuracy was assessed in strain-life evaluation of a direct-quenched high-strength steel. All the prediction methods claim to be able to perform low-cycle fatigue analysis using available or easily obtainable material properties, thus eliminating the need for costly and time-consuming fatigue tests. Simple approximations were able to estimate the strain-life curve with satisfactory accuracy using only monotonic properties. The tested neural network-based model, although yielding acceptable results for the material in question, was found to be overly sensitive to the data sets used for training and showed an inconsistency in estimation of the fatigue life and fatigue properties. The studied continuum damage-based model was able to produce a curve detecting early stages of crack initiation. This model requires more experimental data for calibration than approaches using simple approximations. As a result of the different theories underlying the analyzed methods, the different approaches have different strengths and weaknesses. However, it was found that the group of parametric equations categorized as simple approximations are the easiest for practical use, with their applicability having already been verified for a broad range of materials.

[A modification of the Gompertz plot resulting from the age index by Ries and an approximation of the survivorship curve (author's transl)].

PubMed

Lohmann, W

1978-01-01

The shape of the survivorship curve can easily be interpreted on condition that the probability of death is proportional to an exponentially rising function of ageing. According to the formation of a sum for determining of the age index by Ries it was investigated to what extent the survivorship curve may be approximated by a sum of exponentials. It follows that the difference between the pure exponential function and a sum of exponentials by using possible values is lying within the random variation. Because the probability of death for different diseases is variable, the new statement is a better one.

Micturition patterns of an unrestrained chimpanzee under entrained and free running conditions.

NASA Technical Reports Server (NTRS)

Hoshizaki, T.; Mcnew, J. J.; Sabbot, I.; Adey, W. R.

1972-01-01

A young male chimpanzee was subjected to 30 days of isolation. Urine volumes and voiding times were recorded every hour beginning 14 days prior to isolation, ending 6 days after isolation, and approximately 2 months later for 10 days as a control. Observed during most periods of the experiment were (1) clear circadian micturition rhythms with the voiding peak occurring immediately after the subject awoke and (2) urine flow rhythms with the maximum volume voided in the morning hours. A 24-hour rhythm was seen when the subject was entrained to 12L:12D treatments and 24.8-hour rhythm when he was exposed to continuous light. A possible underlying 24-hour micturition rhythm was also seen during the continuous light period. Distorted rhythm curves indicating possible stress were obtained for the pre-isolation adaptation period and the initial period of isolation. As time passed, the curves were more like the controls, perhaps indicating a decrease in stress.

Comparison of Three Methods for Wind Turbine Capacity Factor Estimation

PubMed Central

Ditkovich, Y.; Kuperman, A.

2014-01-01

Three approaches to calculating capacity factor of fixed speed wind turbines are reviewed and compared using a case study. The first “quasiexact” approach utilizes discrete wind raw data (in the histogram form) and manufacturer-provided turbine power curve (also in discrete form) to numerically calculate the capacity factor. On the other hand, the second “analytic” approach employs a continuous probability distribution function, fitted to the wind data as well as continuous turbine power curve, resulting from double polynomial fitting of manufacturer-provided power curve data. The latter approach, while being an approximation, can be solved analytically thus providing a valuable insight into aspects, affecting the capacity factor. Moreover, several other merits of wind turbine performance may be derived based on the analytical approach. The third “approximate” approach, valid in case of Rayleigh winds only, employs a nonlinear approximation of the capacity factor versus average wind speed curve, only requiring rated power and rotor diameter of the turbine. It is shown that the results obtained by employing the three approaches are very close, enforcing the validity of the analytically derived approximations, which may be used for wind turbine performance evaluation. PMID:24587755

S-curve networks and an approximate method for estimating degree distributions of complex networks

NASA Astrophysics Data System (ADS)

Guo, Jin-Li

2010-12-01

In the study of complex networks almost all theoretical models have the property of infinite growth, but the size of actual networks is finite. According to statistics from the China Internet IPv4 (Internet Protocol version 4) addresses, this paper proposes a forecasting model by using S curve (logistic curve). The growing trend of IPv4 addresses in China is forecasted. There are some reference values for optimizing the distribution of IPv4 address resource and the development of IPv6. Based on the laws of IPv4 growth, that is, the bulk growth and the finitely growing limit, it proposes a finite network model with a bulk growth. The model is said to be an S-curve network. Analysis demonstrates that the analytic method based on uniform distributions (i.e., Barabási-Albert method) is not suitable for the network. It develops an approximate method to predict the growth dynamics of the individual nodes, and uses this to calculate analytically the degree distribution and the scaling exponents. The analytical result agrees with the simulation well, obeying an approximately power-law form. This method can overcome a shortcoming of Barabási-Albert method commonly used in current network research.

A new breakfast cereal containing guar gum reduces postprandial plasma glucose and insulin concentrations in normal-weight human subjects.

PubMed

Fairchild, R M; Ellis, P R; Byrne, A J; Luzio, S D; Mir, M A

1996-07-01

A new guar-containing wheatflake product was developed to assess its effect on carbohydrate tolerance in normal-weight, healthy subjects. The extruded wheatflake breakfast cereals containing 0 (control) or approximately 90 g guar gum/kg DM were fed to ten fasting, normal-weight, healthy subjects using a repeated measures design. The meals were similar in energy (approximately 1.8 MJ), available carbohydrate (78 g), protein (15 g) and fat (5.4 g) content. The guar gum content of the test meals was 6.3 g. Venous blood samples were taken fasting and at 15, 30, 45, 60, 90, 120, 150 and 240 min after commencing each breakfast and analysed for plasma glucose, insulin and C-peptide. The guar wheatflake meal produced a significant main effect for glucose and insulin at 0-60 min and 0-240 min time intervals respectively, but not for the C-peptide levels compared with the control meal. Significant reductions in postprandial glucose and insulin responses were seen following the guar wheatflake meal compared with the control meal at 15 and 60 min (glucose) and 15, 60, 90 and 120 min (insulin). The 60 and 120 min areas under the curve for glucose and insulin were significantly reduced by the guar gum meal, as was the 240 min area under the curve for insulin. Thus, it can be concluded that the use of a severe method of heat extrusion to produce guar wheatflakes does not diminish the physiological activity of the guar gum.

Limiting Forces on Transit Trucks in Steady-State Curving

DOT National Transportation Integrated Search

1981-05-01

This study develops conservative bounds on wheel/rail forces and flange forces for several types of rigid and flexible trucks in steady-state curving conditions. The approximate analysis presented provides closed-form relations for estimating forces,...

Constituent Effects on the Stress-Strain Behavior of Woven Melt-Infiltrated SiC Composites

NASA Technical Reports Server (NTRS)

Morscher, Gregory N.; Eldridge, Jeff I.; Levine, Stanley (Technical Monitor)

2001-01-01

The stress-strain behavior of 2D woven SiC fiber reinforced, melt-infiltrated SiC matrix composites with BN interphases were studied for composites fabricated with different fiber tow ends per unit length, different composite thickness, and different numbers of plies. In general, the stress-strain behavior, i.e., the 'knee' in the curve and the final slope of the stress-strain curve, was controlled by the volume fraction of fibers. Some of the composites exhibited debonding and sliding in between the interphase and the matrix rather than the more common debonding and sliding interface between the fiber and the interphase. Composites that exhibited this 'outside debonding' interface, in general, had lower elastic moduli and higher ultimate strains as well as longer pull-out lengths compared to the 'inside debonding' interface composites. Stress-strain curves were modeled where matrix crack formation as a function of stress was approximated from the acoustic emission activity and the measured crack density from the failed specimens. Interfacial shear strength measurements from individual fiber push-in tests were in good agreement with the interfacial shear strength values used to model the stress-strain curves.

Solidification Structure Synthesis in Undercooled Liquids

DTIC Science & Technology

1993-10-18

Diagrams 32 1. Supersaturation in Sn-Sb Alloys 32 2. Microstructural Transitions in Fe-Ni alloys 33 E. Droplet Nucleation Kinetics 36 F . Controlled...indicated as - F ,,. The curves correspond to the extrapolation of experimental data (exp.). (b) to the approximation of AGv and TAS=-O by Dubey and...Thermodynamic stability of oxide particles in Sn Oxide A Grxn1 A Grxn2 A F (XmOn) (kJ) (kJ) (°C) AI20 3 +1605 +810 144 TiO- +367 +372 142 Y203 +2119 +1067 136

A systematic resolution of sulfur in reticulated vitreous carbon using X-ray absorption spectroscopy.

PubMed

Frank, Patrick; George, Serena DeBeer; Anxolabéhère-Mallart, Elodie; Hedman, Britt; Hodgson, Keith O

2006-11-27

Sulfur K-edge X-ray absorption spectroscopy (XAS) was used to characterize the approximately 0.1% sulfur found both in native reticulated vitreous carbon (RVC) foam and in RVC oxidatively modified using 0.2 M KMnO4 in 2 M H2SO4. Sulfur valences and functional groups were assessed using K-edge XAS spectral curve-fitting and employing explicit sulfur compounds as models. For native RVC, these were episulfide (approximately 3%), thianthrene (approximately 9%), disulfide (approximately 10%), sulfenate ester (approximately 12%), benzothiophene (approximately 24%), N,N'-thiobisphthalimide (approximately 30%), alkyl sulfonate (approximately 1.2%), alkyl sulfate monoester (approximately 6%), and sulfate dianion (approximately 6%). Permanganate oxidation of RVC diminished sulfenic sulfur to approximately 9%, thianthrenic sulfur to approximately 7%, and sulfate dianion to approximately 1% but increased sulfate monoester to approximately 12%, and newly produced sulfone (approximately 2%) and sulfate diester (approximately 5%). A simple thermodynamic model was derived that allows proportionate functional group comparisons despite differing (approximately +/-15%) total sulfur contents between RVC batches. The limits of accuracy in the XAS curve-fitting analysis are discussed in terms of microenvironments and extended structures in RVC carbon that cannot be exactly modeled by small molecules. Sulfate esters cover approximately 0.15% of the RVC surface, increasing to approximately 0.51% following permanganate/sulfuric acid treatment. The detection of episulfide directly corroborates a proposed mechanism for the migration of elemental sulfur through carbon.

Spline approximation, Part 1: Basic methodology

NASA Astrophysics Data System (ADS)

Ezhov, Nikolaj; Neitzel, Frank; Petrovic, Svetozar

2018-04-01

In engineering geodesy point clouds derived from terrestrial laser scanning or from photogrammetric approaches are almost never used as final results. For further processing and analysis a curve or surface approximation with a continuous mathematical function is required. In this paper the approximation of 2D curves by means of splines is treated. Splines offer quite flexible and elegant solutions for interpolation or approximation of "irregularly" distributed data. Depending on the problem they can be expressed as a function or as a set of equations that depend on some parameter. Many different types of splines can be used for spline approximation and all of them have certain advantages and disadvantages depending on the approximation problem. In a series of three articles spline approximation is presented from a geodetic point of view. In this paper (Part 1) the basic methodology of spline approximation is demonstrated using splines constructed from ordinary polynomials and splines constructed from truncated polynomials. In the forthcoming Part 2 the notion of B-spline will be explained in a unique way, namely by using the concept of convex combinations. The numerical stability of all spline approximation approaches as well as the utilization of splines for deformation detection will be investigated on numerical examples in Part 3.

Design of an essentially non-oscillatory reconstruction procedure in finite-element type meshes

NASA Technical Reports Server (NTRS)

Abgrall, Remi

1992-01-01

An essentially non oscillatory reconstruction for functions defined on finite element type meshes is designed. Two related problems are studied: the interpolation of possibly unsmooth multivariate functions on arbitary meshes and the reconstruction of a function from its averages in the control volumes surrounding the nodes of the mesh. Concerning the first problem, the behavior of the highest coefficients of two polynomial interpolations of a function that may admit discontinuities of locally regular curves is studied: the Lagrange interpolation and an approximation such that the mean of the polynomial on any control volume is equal to that of the function to be approximated. This enables the best stencil for the approximation to be chosen. The choice of the smallest possible number of stencils is addressed. Concerning the reconstruction problem, two methods were studied: one based on an adaptation of the so called reconstruction via deconvolution method to irregular meshes and one that lies on the approximation on the mean as defined above. The first method is conservative up to a quadrature formula and the second one is exactly conservative. The two methods have the expected order of accuracy, but the second one is much less expensive than the first one. Some numerical examples are given which demonstrate the efficiency of the reconstruction.

Spitzer Space Telescope Mid-IR Light Curves of Neptune

NASA Technical Reports Server (NTRS)

Stauffer, John; Marley, Mark S.; Gizis, John E.; Rebull, Luisa; Carey, Sean J.; Krick, Jessica; Ingalls, James G.; Lowrance, Patrick; Glaccum, William; Kirkpatrick, J. Davy;

Section Curve Reconstruction and Mean-Camber Curve Extraction of a Point-Sampled Blade Surface

PubMed Central

Li, Wen-long; Xie, He; Li, Qi-dong; Zhou, Li-ping; Yin, Zhou-ping

2014-01-01

The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization. PMID:25551467

Section curve reconstruction and mean-camber curve extraction of a point-sampled blade surface.

PubMed

Li, Wen-long; Xie, He; Li, Qi-dong; Zhou, Li-ping; Yin, Zhou-ping

2014-01-01

The blade is one of the most critical parts of an aviation engine, and a small change in the blade geometry may significantly affect the dynamics performance of the aviation engine. Rapid advancements in 3D scanning techniques have enabled the inspection of the blade shape using a dense and accurate point cloud. This paper proposes a new method to achieving two common tasks in blade inspection: section curve reconstruction and mean-camber curve extraction with the representation of a point cloud. The mathematical morphology is expanded and applied to restrain the effect of the measuring defects and generate an ordered sequence of 2D measured points in the section plane. Then, the energy and distance are minimized to iteratively smoothen the measured points, approximate the section curve and extract the mean-camber curve. In addition, a turbine blade is machined and scanned to observe the curvature variation, energy variation and approximation error, which demonstrates the availability of the proposed method. The proposed method is simple to implement and can be applied in aviation casting-blade finish inspection, large forging-blade allowance inspection and visual-guided robot grinding localization.

Contact position sensor using constant contact force control system

NASA Technical Reports Server (NTRS)

Sturdevant, Jay (Inventor)

1995-01-01

A force control system (50) and method are provided for controlling a position contact sensor (10) so as to produce a constant controlled contact force therewith. The system (50) includes a contact position sensor (10) which has a contact probe (12) for contacting the surface of a target to be measured and an output signal (V.sub.o) for providing a position indication thereof. An actuator (30) is provided for controllably driving the contact position sensor (10) in response to an actuation control signal (I). A controller (52) receives the position indication signal (V.sub.o) and generates in response thereto the actuation control signal (I) so as to provide a substantially constant selective force (F) exerted by the contact probe (12). The actuation drive signal (I) is generated further in response to substantially linear approximation curves based on predetermined force and position data attained from the sensor (10) and the actuator (30).

Flight Investigation at Low Angles of Attack to Determine the Longitudinal Stability and Control Characteristics of a Cruciform Canard Missile Configuration with a Low-Aspect-Ratio Wing and Blunt Nose at Mach Numbers from 1.2 to 2.1

NASA Technical Reports Server (NTRS)

Brown, Clarence A , Jr

1957-01-01

A full- scale rocket-powered model of a cruciform canard missile configuration with a low- aspect - ratio wing and blunt nose has been flight tested by the Langley Pilotless Aircraft Research Division. Static and dynamic longitudinal stability and control derivatives of this interdigitated canard-wing missile configuration were determined by using the pulsed- control technique at low angles of attack and for a Mach number range of 1.2 to 2.1. The lift - curve slope showed only small nonlinearities with changes in control deflection or angle of attack but indicated a difference in lift- .curve slope of approximately 7 percent for the two control deflections of delta = 3.0 deg and delta= -0.3 deg . The large tail length of the missile tested was effective in producing damping in pitch throughout the Mach number range tested. The aerodynamic- center location was nearly constant with Mach number for the two control deflections but was shown to be less stable with the larger control deflection. The increment of lift produced by the controls was small and positive throughout the Mach number range tested, whereas the pitching moment produced by the controls exhibited a normal trend of reduced effectiveness with increasing Mach number.The effectiveness of the controls in producing angle of attack, lift, and pitching moment was good at all Mach numbers tested.

Flight Investigation at Low Angles of Attack to Determine the Longitudinal Stability and Control Characteristics of a Cruciform Canard Missile Configuration with a Low-Aspect-Ratio Wing and Blunt Nose at Mach Numbers from 1.2 to 2.1

NASA Technical Reports Server (NTRS)

Brown, C. A., Jr.

1957-01-01

A full-scale rocket-powered model of a cruciform canard missile configuration with a low-aspect-ratio wing and blunt nose has been flight tested by the Langley Pilotless Aircraft Research Division. Static and dynamic longitudinal stability and control derivatives of this interdigitated canard-wing missile configuration were determined by using the pulsed-control technique at low angles of attack and for a Mach number range of 1.2 to 2.1. The lift-curve slope showed only small nonlinearities with changes in control deflection or angle of attack but indicated a difference in lift-curve slope of approximately 7 percent for the two control deflections of delta = 3.0 deg and delta = -0.3 deg. The large tail length of the missile tested was effective in producing damping in pitch throughout the Mach number range tested. The aerodynamic-center location was nearly constant with Mach number for the two control deflections but was shown to be less stable with the larger control deflection. The increment of lift produced by the controls was small and positive throughout the Mach number range tested, whereas the pitching moment produced by the controls exhibited a normal trend of reduced effectiveness with increasing Mach number. The effectiveness of the controls in producing angle of attack, lift, and pitching moment was good at all Mach numbers tested.

Gaussian-Beam/Physical-Optics Design Of Beam Waveguide

NASA Technical Reports Server (NTRS)

Veruttipong, Watt; Chen, Jacqueline C.; Bathker, Dan A.

1993-01-01

In iterative method of designing wideband beam-waveguide feed for paraboloidal-reflector antenna, Gaussian-beam approximation alternated with more nearly exact physical-optics analysis of diffraction. Includes curved and straight reflectors guiding radiation from feed horn to subreflector. For iterative design calculations, curved mirrors mathematically modeled as thin lenses. Each distance Li is combined length of two straight-line segments intersecting at one of flat mirrors. Method useful for designing beam-waveguide reflectors or mirrors required to have diameters approximately less than 30 wavelengths at one or more intended operating frequencies.

Polymorphism of paracetamol: relative stabilities of the monoclinic and orthorhombic phases inferred from topological pressure-temperature and temperature-volume phase diagrams.

PubMed

Espeau, Philippe; Céolin, René; Tamarit, Josep-Lluis; Perrin, Marc-Antoine; Gauchi, Jean-Pierre; Leveiller, Franck

2005-03-01

The thermodynamic relationships between the two known polymorphs of paracetamol have been investigated, and the subsequent pressure-temperature and temperature-volume phase diagrams were constructed using data from crystallographic and calorimetric measurements as a function of the temperature. Irrespective of temperature, monoclinic Form I and orthorhombic Form II are stable phases at ordinary and high pressures, respectively. The I and II phase regions in the pressure-temperature diagram are bordered by the I-II equilibrium curve, for which a negative slope (dp/dT approximately -0.3 MPa x K(-1)) was determined although it was not observed experimentally. This curve goes through the I-II-liquid triple point whose coordinates (p approximately 234 MPa, T approximately 505 K) correspond to the crossing point of the melting curves, for which dp/dT values of +3.75 MPa x K(-1) (I) and +3.14 MPa x K(-1) (II) were calculated from enthalpy and volume changes upon fusion. More generally, this case exemplifies how the stability hierarchy of polymorphs may be inferred from the difference in their sublimation curves, as topologically positioned with respect to each other, using the phase rule and simple inferences resorting to Gibbs equilibrium thermodynamics. Copyright 2004 Wiley-Liss, Inc. and the American Pharmacists Association.

Two-Term Asymptotic Approximation of a Cardiac Restitution Curve*

PubMed Central

Cain, John W.; Schaeffer, David G.

2007-01-01

If spatial extent is neglected, ionic models of cardiac cells consist of systems of ordinary differential equations (ODEs) which have the property of excitability, i.e., a brief stimulus produces a prolonged evolution (called an action potential in the cardiac context) before the eventual return to equilibrium. Under repeated stimulation, or pacing, cardiac tissue exhibits electrical restitution: the steady-state action potential duration (APD) at a given pacing period B shortens as B is decreased. Independent of ionic models, restitution is often modeled phenomenologically by a one-dimensional mapping of the form APDnext = f(B – APDprevious). Under some circumstances, a restitution function f can be derived as an asymptotic approximation to the behavior of an ionic model. In this paper, extending previous work, we derive the next term in such an asymptotic approximation for a particular ionic model consisting of two ODEs. The two-term approximation exhibits excellent quantitative agreement with the actual restitution curve, whereas the leading-order approximation significantly underestimates actual APD values. PMID:18080006

In vitro experiments of vessel wall apposition between the Enterprise and Enterprise 2 stents for treatment of cerebral aneurysms.

PubMed

Kono, Kenichi; Terada, Tomoaki

2016-02-01

A closed-cell stent called Enterprise has been used for stent-assisted coil embolization of cerebral aneurysms. The Enterprise stent tends to cause kinks and vessel wall malposition in curved vessels and may cause thromboembolic complications. We evaluated vessel wall apposition of a new closed-cell stent, Enterprise 2, compared with a previous Enterprise stent, using curved vascular silicone models. The Enterprise or Enterprise 2 stent was deployed in curved vascular models with various radii of approximately 5 to 10 mm. Stent deployment was performed 25 times in each stent. A push-pull technique was used to minimize incomplete wall apposition. To evaluate conformity of stents, gaps between a stent and a vessel wall were measured. The gap ratio (gap / a wall diameter) was 15 % ± 17 % (mean ± standard deviation) and 41 % ± 15 % with the Enterprise 2 stent and the Enterprise stent, respectively. Taking gap ratios and radii of vessel curvature into consideration, the Enterprise 2 stent had significantly better wall apposition than the Enterprise stent (p = 0.005). In the same radius of vessel curvature, the Enterprise 2 stent had approximately half of the gap compared with the Enterprise stent. There were no significant differences in vessel straightening effects between the two stents. The Enterprise 2 stent has better wall apposition in curved vessels than the Enterprise stent. The gap between a vessel wall and the Enterprise 2 stent is approximately half that of the Enterprise stent. However, gaps and kinks are still present in curved vessels with a small radius. Caution should be taken for kinks and malposition in acutely curved vessels, such as the siphon of the internal carotid artery.

Short-bearing approximation for full journal bearings

NASA Technical Reports Server (NTRS)

Ocvirk, F W

1952-01-01

A short-bearing approximation of pressure distribution in the oil film is presented which is an extension of the pressure-distribution function of Michell and Cardullo and includes end-leakage effects. Equations giving applied load, attitude angle, location and magnitude of peak film pressure, friction, and required oil flow rate as functions of the eccentricity ratio are also given. The capacity number, a basic non dimensional quantity resulting from this analysis is the product of the Sommerfeld number and the square of the length-diameter ratio. Curves determined by this analysis are compared with previously published experimental data and theoretical curves of Sommerfeld and Cameron and Wood. Conclusions reached indicate that this approximation is of practical value for analysis of short bearings.

Measurement And Shape Analysis Including Vertebral Rotation Of Scoliotic Spines From Single Plane Radiographs

NASA Astrophysics Data System (ADS)

Drerup, B.; Hierholzer, E.

1986-07-01

Radiological assessment and follow-up control of scoliosis, i.e. of a lateral and rotational deviation of the spine, is performed mainly by single plane radiographs. Additional information may be gained from these radiographs by introducing a parametrized vertebral model. By analyzing the radiographic contours according to this model, axial rotation can be determined for any position and orientation of the vertebra. In addition to rotation several other data are determined for each vertebra, such as the tilting angle and the two-dimensional coordinates of the centre. By handling the data as a function of the vertebral location in spine, characteristic curves are generated. In order to find simple shape parameters for these characteristics, a smooth curve has to be fitted to the data points by a least squares approximation. This problem may be solved by a Fourier decomposition of the spinal curves. It appears, that the Fourier coefficients (amplitudes and phases) and some derived shape parameters lend themselves to a medical interpretation, which is consistent with the existing classification of the scoliotic spine.

Fitting Richards' curve to data of diverse origins

USGS Publications Warehouse

Johnson, D.H.; Sargeant, A.B.; Allen, S.H.

1975-01-01

Published techniques for fitting data to nonlinear growth curves are briefly reviewed, most techniques require knowledge of the shape of the curve. A flexible growth curve developed by Richards (1959) is discussed as an alternative when the shape is unknown. The shape of this curve is governed by a specific parameter which can be estimated from the data. We describe in detail the fitting of a diverse set of longitudinal and cross-sectional data to Richards' growth curve for the purpose of determining the age of red fox (Vulpes vulpes) pups on the basis of right hind foot length. The fitted curve is found suitable for pups less than approximately 80 days old. The curve is extrapolated to pre-natal growth and shown to be appropriate only for about 10 days prior to birth.

An Adaptive B-Spline Neural Network and Its Application in Terminal Sliding Mode Control for a Mobile Satcom Antenna Inertially Stabilized Platform.

PubMed

Zhang, Xiaolei; Zhao, Yan; Guo, Kai; Li, Gaoliang; Deng, Nianmao

2017-04-28

The mobile satcom antenna (MSA) enables a moving vehicle to communicate with a geostationary Earth orbit satellite. To realize continuous communication, the MSA should be aligned with the satellite in both sight and polarization all the time. Because of coupling effects, unknown disturbances, sensor noises and unmodeled dynamics existing in the system, the control system should have a strong adaptability. The significant features of terminal sliding mode control method are robustness and finite time convergence, but the robustness is related to the large switching control gain which is determined by uncertain issues and can lead to chattering phenomena. Neural networks can reduce the chattering and approximate nonlinear issues. In this work, a novel B-spline curve-based B-spline neural network (BSNN) is developed. The improved BSNN has the capability of shape changing and self-adaption. In addition, the output of the proposed BSNN is applied to approximate the nonlinear function in the system. The results of simulations and experiments are also compared with those of PID method, non-singularity fast terminal sliding mode (NFTSM) control and radial basis function (RBF) neural network-based NFTSM. It is shown that the proposed method has the best performance, with reliable control precision.

Impact angle constrained three-dimensional integrated guidance and control for STT missile in the presence of input saturation.

PubMed

Wang, Sen; Wang, Weihong; Xiong, Shaofeng

2016-09-01

Considering a class of skid-to-turn (STT) missile with fixed target and constrained terminal impact angles, a novel three-dimensional (3D) integrated guidance and control (IGC) scheme is proposed in this paper. Based on coriolis theorem, the fully nonlinear IGC model without the assumption that the missile flies heading to the target at initial time is established in the three-dimensional space. For this strict-feedback form of multi-variable system, dynamic surface control algorithm is implemented combining with extended observer (ESO) to complete the preliminary design. Then, in order to deal with the problems of the input constraints, a hyperbolic tangent function is introduced to approximate the saturation function and auxiliary system including a Nussbaum function established to compensate for the approximation error. The stability of the closed-loop system is proven based on Lyapunov theory. Numerical simulations results show that the proposed integrated guidance and control algorithm can ensure the accuracy of target interception with initial alignment angle deviation and the input saturation is suppressed with smooth deflection curves. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Polymorphic site index curves for red fir in California and southern Oregon

Treesearch

K. Leroy Dolph

1991-01-01

Polymorphic site index curves were developed from stem analysis data of 194 dominant red fir trees in California and southern Oregon. Site index was based on breast-height age and total tree height, with a base age of 50 years at breast height. Site index curves for breast height ages 10 to 160 years are presented for approximate estimates of site index. For more...

UBVRI polarimetry of AM Herculis-type binaries. 5: The asynchronous (?) polar BY Camelopardalis (H0538+608)

NASA Astrophysics Data System (ADS)

Piirola, V.; Coyne, G. V.; Takalo, S. J.; Takalo, L.; Larsson, S.; Vilhu, O.

1994-03-01

The basic features of the light and circular polarization curves of BY Cam in 1990 Sep can be reproduced by a model with the inclination i = 40-60 deg of the magnetic white dwarf spin axis and two extended emission regions: a strong positive circular polarization region at the colatitude beta = 30-45 deg and a weaker negative circular polarization region at beta = 100-125 deg with a phase lag of about 0.5. The degree of linear polarization was small (approximately less than 1 %), but the observed position angle pattern is roughly consistent with the above geometric picture. However, in November 1990 the reduced amplitude of the position angle curve, and the self-eclipsing-type light curves with distinct bright and faint phases, suggest higher inclination (i approximately 85 deg). Precession with a period of 100-150 days is offered as a hypothetical mechanism for changing the inclination. Timings for the transit of the positive circular polarization region from 1992 Nov and 1993 Jan appear approximately 0.3 phase later than predicted from our linear ephemeris based on data from the time interval JD2446138-8155, indicating a possible period increase of dP/dt approximately 3.3 x 10-4, and a synchronization time scale of approximately 1200 y. This is longer than found for the only well established re-synchronizing magnetic binary V1500 Cyg (approximately 185 y). Further timings are needed to confirm and improve the rotational period of the magnetic white dwarf in BY Cam.

Modeling two strains of disease via aggregate-level infectivity curves.

PubMed

Romanescu, Razvan; Deardon, Rob

2016-04-01

Well formulated models of disease spread, and efficient methods to fit them to observed data, are powerful tools for aiding the surveillance and control of infectious diseases. Our project considers the problem of the simultaneous spread of two related strains of disease in a context where spatial location is the key driver of disease spread. We start our modeling work with the individual level models (ILMs) of disease transmission, and extend these models to accommodate the competing spread of the pathogens in a two-tier hierarchical population (whose levels we refer to as 'farm' and 'animal'). The postulated interference mechanism between the two strains is a period of cross-immunity following infection. We also present a framework for speeding up the computationally intensive process of fitting the ILM to data, typically done using Markov chain Monte Carlo (MCMC) in a Bayesian framework, by turning the inference into a two-stage process. First, we approximate the number of animals infected on a farm over time by infectivity curves. These curves are fit to data sampled from farms, using maximum likelihood estimation, then, conditional on the fitted curves, Bayesian MCMC inference proceeds for the remaining parameters. Finally, we use posterior predictive distributions of salient epidemic summary statistics, in order to assess the model fitted.

Variable effects of temperature on insect herbivory

PubMed Central

Burkepile, Deron E.; Parker, John D.

2014-01-01

Rising temperatures can influence the top-down control of plant biomass by increasing herbivore metabolic demands. Unfortunately, we know relatively little about the effects of temperature on herbivory rates for most insect herbivores in a given community. Evolutionary history, adaptation to local environments, and dietary factors may lead to variable thermal response curves across different species. Here we characterized the effect of temperature on herbivory rates for 21 herbivore-plant pairs, encompassing 14 herbivore and 12 plant species. We show that overall consumption rates increase with temperature between 20 and 30 °C but do not increase further with increasing temperature. However, there is substantial variation in thermal responses among individual herbivore-plant pairs at the highest temperatures. Over one third of the herbivore-plant pairs showed declining consumption rates at high temperatures, while an approximately equal number showed increasing consumption rates. Such variation existed even within herbivore species, as some species exhibited idiosyncratic thermal response curves on different host plants. Thus, rising temperatures, particularly with respect to climate change, may have highly variable effects on plant-herbivore interactions and, ultimately, top-down control of plant biomass. PMID:24860701

Thermotolerance in preirradiated intestine and its influence on time-temperature relationships

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

Hume, S.P.; Marigold, J.C.; Manjil, L.G.

The crypt compartment of mouse jejunum showed a transient increase in thermal susceptibility approximately 10 days after moderate X-ray doses to the abdomen (9-10 Gy). The increase in response was manifest as an increase in slope of the crypt dose-response curve but was limited to temperatures below 43/sup 0/C. As a result, the 43/sup 0/C inflexion in the Arrhenius plot (the relationship between treatment time and temperature) for thermal sensitivity of crypts was eliminated in preirradiated tissue, and the curve became monophasic over the range 42.0-44.5/sup 0/C. At temperatures below 42/sup 0/C, the curve again deviated. At supranormal temperatures ofmore » 42/sup 0/C and below, the durations of hyperthermia needed for measurable effect were sufficient to allow thermotolerance to be expressed within the heating period. Neither the threshold heating times nor this thermotolerance were affected by prior irradiation. In the temperature range 42-43/sup 0/C, an earlier development of thermotolerance could be demonstrated in control tissue by challenging with an acute high-temperature heat treatment. This thermotolerance was eliminated in preirradiated tissue, resulting in the apparent increase in sensitivity. The findings support the view that the complex nature of the time-temperature relationship seen in normal tissue in vivo is a manifestation of the ability of the tissue to progressively acquire a thermotolerant state during treatment at temperatures below approximately 43/sup 0/C, so that the intrinsic sensitivity is modulated while being assessed.« less

Multiband Optical Follow-Up Observations of GRB 020813 AT KISO and Bisei Observatories

NASA Astrophysics Data System (ADS)

Urata, Y.; Nishiura, S.; Miyata, T.; Mito, H.; Kawabata, T.; Nakada, Y.; Aoki, T.; Soyano, T.; Tarusawa, K.; Yoshida, A.; Tamagawa, T.; Makishima, K.

Four color (l B,V,R,I) photometric observations of the optical afterglow of GRB 020813 were obtained from 0.346 to 0.516 days after the burst. In order to investigate the early-time (<1 day) evolution of the afterglow, four-band light curves were produced by analyzing the data taken at these two sites, as well as publicly released data taken by the Magellan Baade telescope. The light curves can be approximated by a broken power law, of which the indices are approximately 0.46 and 1.33 before and after a break at ˜0.2 days, respectively. The optical spectral index stayed approximately constant at ˜0.9 over 0.17--4.07 days after the burst. Since the temporal decay index after the break and the spectral index measured at that time are both consistent with those predicted by a spherical expansion model, the early break is unlikely to be a jet break, but likely to represent the end of an early bump in the light curve as was observed in the optical afterglow of GRB 021004.

View of blind curve along National Old Trails Road, about ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

View of blind curve along National Old Trails Road, about 1,000 feet from top, facing north. - La Bajada Historic Trails and Roads, Approximately 1 mile East/Northeast of intersection of State Highway 16 and Indian Service Road 841, La Bajada, Santa Fe County, NM

Neck curve polynomials in neck rupture model

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

Kurniadi, Rizal; Perkasa, Yudha S.; Waris, Abdul

2012-06-06

The Neck Rupture Model is a model that explains the scission process which has smallest radius in liquid drop at certain position. Old fashion of rupture position is determined randomly so that has been called as Random Neck Rupture Model (RNRM). The neck curve polynomials have been employed in the Neck Rupture Model for calculation the fission yield of neutron induced fission reaction of {sup 280}X{sub 90} with changing of order of polynomials as well as temperature. The neck curve polynomials approximation shows the important effects in shaping of fission yield curve.

Growth curve for Propionibacterium acnes.

PubMed

Hall, G S; Pratt-Rippin, K; Meisler, D M; Washington, J A; Roussel, T J; Miller, D

1994-06-01

We established growth curves for Propionibacterium acnes isolates recovered from eyes with chronic postoperative endophthalmitis. The growth curve plotted the average of the duplicate bacterial concentration against time. The generation time for P. acnes calculated from the growth curves was approximately 5.1 hours. The growth of P. acnes is slower than other anaerobic bacteria. This may account for its delayed appearance in culture of ocular specimens. It may also explain treatment failure if the concentration of an antibiotic injected into the vitreous does not remain at an effective level during the critical replicative phase of the organism.

A Monte Carlo Application to Approximate the Integral from a to b of e Raised to the x Squared.

ERIC Educational Resources Information Center

Easterday, Kenneth; Smith, Tommy

1992-01-01

Proposes an alternative means of approximating the value of complex integrals, the Monte Carlo procedure. Incorporating a discrete approach and probability, an approximation is obtained from the ratio of computer-generated points falling under the curve to the number of points generated in a predetermined rectangle. (MDH)

Robotic partial nephrectomy shortens warm ischemia time, reducing suturing time kinetics even for an experienced laparoscopic surgeon: a comparative analysis.

PubMed

Faria, Eliney F; Caputo, Peter A; Wood, Christopher G; Karam, Jose A; Nogueras-González, Graciela M; Matin, Surena F

2014-02-01

Laparoscopic and robotic partial nephrectomy (LPN and RPN) are strongly related to influence of tumor complexity and learning curve. We analyzed a consecutive experience between RPN and LPN to discern if warm ischemia time (WIT) is in fact improved while accounting for these two confounding variables and if so by which particular aspect of WIT. This is a retrospective analysis of consecutive procedures performed by a single surgeon between 2002-2008 (LPN) and 2008-2012 (RPN). Specifically, individual steps, including tumor excision, suturing of intrarenal defect, and parenchyma, were recorded at the time of surgery. Multivariate and univariate analyzes were used to evaluate influence of learning curve, tumor complexity, and time kinetics of individual steps during WIT, to determine their influence in WIT. Additionally, we considered the effect of RPN on the learning curve. A total of 146 LPNs and 137 RPNs were included. Considering renal function, WIT, suturing time, renorrhaphy time were found statistically significant differences in favor of RPN (p < 0.05). In the univariate analysis, surgical procedure, learning curve, clinical tumor size, and RENAL nephrometry score were statistically significant predictors for WIT (p < 0.05). RPN decreased the WIT on average by approximately 7 min compared to LPN even when adjusting for learning curve, tumor complexity, and both together (p < 0.001). We found RPN was associated with a shorter WIT when controlling for influence of the learning curve and tumor complexity. The time required for tumor excision was not shortened but the time required for suturing steps was significantly shortened.

Asymmetry dependence of the caloric curve for mononuclei

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

Hoel, C.; Sobotka, L. G.; Charity, R. J.

2007-01-15

The asymmetry dependence of the caloric curve, for mononuclear configurations, is studied as a function of neutron-to-proton asymmetry with a model that allows for independent variation of the neutron and proton surface diffusenesses. The evolution of the effective mass with density and excitation is included in a schematic fashion and the entropies are extracted in a local density approximation. The plateau in the caloric curve displays only a slight sensitivity to the asymmetry.

Marginal abatement cost curves for NOx that account for ...

EPA Pesticide Factsheets

A marginal abatement cost curve (MACC) traces out the relationship between the quantity of pollution abated and the marginal cost of abating each additional unit. In the context of air quality management, MACCs typically are developed by sorting end-of-pipe controls by their respective cost effectiveness. Alternative measures, such as renewable electricity, energy efficiency, and fuel switching (RE/EE/FS), are not considered as it is difficult to quantify their abatement potential. In this paper, we demonstrate the use of an energy system model to develop a MACC for nitrogen oxides (NOx) that incorporates both end-of-pipe controls and these alternative measures. We decompose the MACC by sector, and evaluate the cost-effectiveness of RE/EE/FS relative to end-of-pipe controls. RE/EE/FS are shown to produce considerable emission reductions after end-of-pipe controls have been exhausted. Furthermore, some RE/EE/FS are shown to be cost-competitive with end-of-pipe controls. Demonstrate how the MARKAL energy system model can be used to evaluate the potential role of renewable electricity, energy efficiency and fuel switching (RE/EE/FS) in achieving NOx reductions. For this particular analysis, we show that RE/EE/FSs are able to increase the quantity of NOx reductions available for a particular marginal cost (ranging from $5k per ton to $40k per ton) by approximately 50%.

The 1974 AVCR Young Scholar Paper: An Open-System Model of Learning

ERIC Educational Resources Information Center

Winn, William

1975-01-01

Rejecting the cybernetic model of the learner, the author offers an open-system model based on von Bertalanffy's equation for growth of the living organism. The model produces four learning curves, not just the logarithmic curve produced by the successive approximations of the cybernetic model. (Editor)

B and V photometry and analysis of the eclipsing binary RZ CAS

NASA Astrophysics Data System (ADS)

Riazi, N.; Bagheri, M. R.; Faghihi, F.

1994-01-01

Photoelectric light curves of the eclipsing binary RZ Cas are presented for B and V filters. The light curves are analyzed for light and geometrical elements, starting with a previously suggested preliminary method. The approximate results thus obtained are then optimised through the Wilson-Devinney computer programs.

The complex variable boundary element method: Applications in determining approximative boundaries

USGS Publications Warehouse

Hromadka, T.V.

1984-01-01

The complex variable boundary element method (CVBEM) is used to determine approximation functions for boundary value problems of the Laplace equation such as occurs in potential theory. By determining an approximative boundary upon which the CVBEM approximator matches the desired constant (level curves) boundary conditions, the CVBEM is found to provide the exact solution throughout the interior of the transformed problem domain. Thus, the acceptability of the CVBEM approximation is determined by the closeness-of-fit of the approximative boundary to the study problem boundary. ?? 1984.

An efficient algorithm for choosing the degree of a polynomial to approximate discrete nonoscillatory data

NASA Technical Reports Server (NTRS)

Hedgley, D. R.

1978-01-01

An efficient algorithm for selecting the degree of a polynomial that defines a curve that best approximates a data set was presented. This algorithm was applied to both oscillatory and nonoscillatory data without loss of generality.

Classifying low flow hydrological regimes at a regional scale

NASA Astrophysics Data System (ADS)

Kirkby, M. J.; Gallart, F.; Kjeldsen, T. R.; Irvine, B. J.; Froebrich, J.; Lo Porto, A.; de Girolamo, A.; Mirage Team

2011-12-01

The paper uses a simple water balance model that partitions the precipitation between actual evapotranspiration, quick flow and delayed flow, and has sufficient complexity to capture the essence of climate and vegetation controls on this partitioning. Using this model, monthly flow duration curves have been constructed from climate data across Europe to address the relative frequency of ecologically critical low flow stages in semi-arid rivers, when flow commonly persists only in disconnected pools in the river bed. The hydrological model is based on a dynamic partitioning of precipitation to estimate water available for evapotranspiration and plant growth and for residual runoff. The duration curve for monthly flows has then been analysed to give an estimate of bankfull flow based on recurrence interval. Arguing from observed ratios of cross-sectional areas at flood and low flows, hydraulic geometry suggests that disconnected flow under "pool" conditions is approximately 0.1% of bankfull flow. Flow duration curves define a measure of bankfull discharge on the basis of frequency. The corresponding frequency for pools is then read from the duration curve, using this (0.1%) ratio to estimate pool discharge from bank full discharge. The flow duration curve then provides an estimate of the frequency of poorly connected pool conditions, corresponding to this discharge, that constrain survival of river-dwelling arthropods and fish. The methodology has here been applied across Europe at 15 km resolution, and the potential is demonstrated for applying the methodology under alternative climatic scenarios.

Constraining Relativistic Bow Shock Properties in Rotation-Powered Millisecond Pulsar Binaries

NASA Technical Reports Server (NTRS)

Wadiasingh, Zorawar; Harding, Alice K.; Venter, Christo; Bottcher, Markus; Baring, Matthew G.

2017-01-01

Multiwavelength follow-up of unidentified Fermi sources has vastly expanded the number of known galactic-field "black widow" and "redback" millisecond pulsar binaries. Focusing on their rotation-powered state, we interpret the radio to X-ray phenomenology in a consistent framework. We advocate the existence of two distinct modes differing in their intrabinary shock orientation, distinguished by the phase-centering of the double-peaked X-ray orbital modulation originating from mildly-relativistic Doppler boosting. By constructing a geometric model for radio eclipses, we constrain the shock geometry as functions of binary inclination and shock stand-off R(sub 0). We develop synthetic X-ray synchrotron orbital light curves and explore the model parameter space allowed by radio eclipse constraints applied on archetypal systems B1957+20 and J1023+0038. For B1957+20, from radio eclipses the stand-off is R(sub 0) approximately 0:15 - 0:3 fraction of binary separation from the companion center, depending on the orbit inclination. Constructed X-ray light curves for B1957+20 using these values are qualitatively consistent with those observed, and we find occultation of the shock by the companion as a minor influence, demanding significant Doppler factors to yield double peaks. For J1023+0038, radio eclipses imply R(sub 0) is approximately less than 0:4 while X-ray light curves suggest 0:1 is approximately less than R(sub 0) is approximately less than 0:3 (from the pulsar). Degeneracies in the model parameter space encourage further development to include transport considerations. Generically, the spatial variation along the shock of the underlying electron power-law index should yield energy-dependence in the shape of light curves motivating future X-ray phase-resolved spectroscopic studies to probe the unknown physics of pulsar winds and relativistic shock acceleration therein.

Simplified curve fits for the thermodynamic properties of equilibrium air

NASA Technical Reports Server (NTRS)

Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.

1987-01-01

New, improved curve fits for the thermodynamic properties of equilibrium air have been developed. The curve fits are for pressure, speed of sound, temperature, entropy, enthalpy, density, and internal energy. These curve fits can be readily incorporated into new or existing computational fluid dynamics codes if real gas effects are desired. The curve fits are constructed from Grabau-type transition functions to model the thermodynamic surfaces in a piecewise manner. The accuracies and continuity of these curve fits are substantially improved over those of previous curve fits. These improvements are due to the incorporation of a small number of additional terms in the approximating polynomials and careful choices of the transition functions. The ranges of validity of the new curve fits are temperatures up to 25 000 K and densities from 10 to the -7 to 10 to the 3d power amagats.

On the Power of Multivariate Latent Growth Curve Models to Detect Correlated Change

ERIC Educational Resources Information Center

Hertzog, Christopher; Lindenberger, Ulman; Ghisletta, Paolo; Oertzen, Timo von

2006-01-01

We evaluated the statistical power of single-indicator latent growth curve models (LGCMs) to detect correlated change between two variables (covariance of slopes) as a function of sample size, number of longitudinal measurement occasions, and reliability (measurement error variance). Power approximations following the method of Satorra and Saris…

Level dependence of distortion product otoacoustic emissions in the leopard frog, Rana pipiens pipiens.

PubMed

Meenderink, Sebastiaan W F; van Dijk, Pim

2004-06-01

The inner ear of frogs holds two papillae specialized in detecting airborne sound, the amphibian papilla (AP) and the basilar papilla (BP). We measured input-output (I/O) curves of distortion product otoacoustic emissions (DPOAEs) from both papillae, and compared their properties. As in other vertebrates, DPOAE I/O curves showed two distinct segments, separated by a notch or kneepoint. The slope of the low-level segment was conspicuously different between the AP and the BP. For DPOAE I/O curves from the AP, slopes were < or = 1 dB/dB, similar to what is found in mammals, birds and some lizards. For DPOAE I/O curves from the BP these slopes were much steeper (approximately 2 dB/dB). Slopes found at high stimulus levels were similar in the AP and the BP (approximately 2 dB/dB). This quantitative difference between the low-level slopes for DPOAEs from the AP and the BP may signify the involvement of different mechanisms in low-level DPOAE generation for the two papillae, respectively.

The NASA earth resources spectral information system: A data compilation

NASA Technical Reports Server (NTRS)

Leeman, V.; Earing, D.; Vincent, R. K.; Ladd, S.

1971-01-01

The NASA Earth Resources Spectral Information System and the information contained therein are described. It contains an ordered, indexed compilation of natural targets in the optical region from 0.3 to 45.0 microns. The data compilation includes approximately 100 rock and mineral, 2600 vegetation, 1000 soil, and 60 water spectral reflectance, transmittance, and emittance curves. Most of the data have been categorized by subject, and the curves in those subject areas have been plotted on a single graph. Those categories with too few curves and miscellaneous categories have been plotted as single-curve graphs. Each graph, composite of single, is fully titled to indicate curve source and is indexed by subject to facilitate user retrieval.

Shapes formed by interacting cracks

NASA Astrophysics Data System (ADS)

Daniels, Karen

2012-02-01

Brittle failure through multiple cracks occurs in a wide variety of contexts, from microscopic failures in dental enamel and cleaved silicon to geological faults and planetary ice crusts. In each of these situations, with complicated stress geometries and different microscopic mechanisms, pairwise interactions between approaching cracks nonetheless produce characteristically curved fracture paths. We investigate the origins of this widely observed ``en passant'' crack pattern by fracturing a rectangular slab which is notched on each long side and subjected to quasi-static uniaxial strain from the short side. The two cracks propagate along approximately straight paths until they pass each other, after which they curve and release a lens-shaped fragment. We find that, for materials with diverse mechanical properties, each curve has an approximately square-root shape, and that the length of each fragment is twice its width. We are able to explain the origins of this universal shape with a simple geometrical model.

Statistical Analyses for Probabilistic Assessments of the Reactor Pressure Vessel Structural Integrity: Building a Master Curve on an Extract of the 'Euro' Fracture Toughness Dataset, Controlling Statistical Uncertainty for Both Mono-Temperature and multi-temperature tests

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

Josse, Florent; Lefebvre, Yannick; Todeschini, Patrick

2006-07-01

Assessing the structural integrity of a nuclear Reactor Pressure Vessel (RPV) subjected to pressurized-thermal-shock (PTS) transients is extremely important to safety. In addition to conventional deterministic calculations to confirm RPV integrity, Electricite de France (EDF) carries out probabilistic analyses. Probabilistic analyses are interesting because some key variables, albeit conventionally taken at conservative values, can be modeled more accurately through statistical variability. One variable which significantly affects RPV structural integrity assessment is cleavage fracture initiation toughness. The reference fracture toughness method currently in use at EDF is the RCCM and ASME Code lower-bound K{sub IC} based on the indexing parameter RT{submore » NDT}. However, in order to quantify the toughness scatter for probabilistic analyses, the master curve method is being analyzed at present. Furthermore, the master curve method is a direct means of evaluating fracture toughness based on K{sub JC} data. In the framework of the master curve investigation undertaken by EDF, this article deals with the following two statistical items: building a master curve from an extract of a fracture toughness dataset (from the European project 'Unified Reference Fracture Toughness Design curves for RPV Steels') and controlling statistical uncertainty for both mono-temperature and multi-temperature tests. Concerning the first point, master curve temperature dependence is empirical in nature. To determine the 'original' master curve, Wallin postulated that a unified description of fracture toughness temperature dependence for ferritic steels is possible, and used a large number of data corresponding to nuclear-grade pressure vessel steels and welds. Our working hypothesis is that some ferritic steels may behave in slightly different ways. Therefore we focused exclusively on the basic french reactor vessel metal of types A508 Class 3 and A 533 grade B Class 1, taking the sampling level and direction into account as well as the test specimen type. As for the second point, the emphasis is placed on the uncertainties in applying the master curve approach. For a toughness dataset based on different specimens of a single product, application of the master curve methodology requires the statistical estimation of one parameter: the reference temperature T{sub 0}. Because of the limited number of specimens, estimation of this temperature is uncertain. The ASTM standard provides a rough evaluation of this statistical uncertainty through an approximate confidence interval. In this paper, a thorough study is carried out to build more meaningful confidence intervals (for both mono-temperature and multi-temperature tests). These results ensure better control over uncertainty, and allow rigorous analysis of the impact of its influencing factors: the number of specimens and the temperatures at which they have been tested. (authors)« less

Novel surgical performance evaluation approximates Standardized Incidence Ratio with high accuracy at simple means.

PubMed

Gabbay, Itay E; Gabbay, Uri

2013-01-01

Excess adverse events may be attributable to poor surgical performance but also to case-mix, which is controlled through the Standardized Incidence Ratio (SIR). SIR calculations can be complicated, resource consuming, and unfeasible in some settings. This article suggests a novel method for SIR approximation. In order to evaluate a potential SIR surrogate measure we predefined acceptance criteria. We developed a new measure - Approximate Risk Index (ARI). "Number Needed for Event" (NNE) is the theoretical number of patients needed "to produce" one adverse event. ARI is defined as the quotient of the group of patients needed for no observed events Ge by total patients treated Ga. Our evaluation compared 2500 surgical units and over 3 million heterogeneous risk surgical patients that were induced through a computerized simulation. Surgical unit's data were computed for SIR and ARI to evaluate compliance with the predefined criteria. Approximation was evaluated by correlation analysis and performance prediction capability by Receiver Operating Characteristics (ROC) analysis. ARI strongly correlates with SIR (r(2) = 0.87, p < 0.05). ARI prediction of excessive risk revealed excellent ROC (Area Under the Curve > 0.9) 87% sensitivity and 91% specificity. ARI provides good approximation of SIR and excellent prediction capability. ARI is simple and cost-effective as it requires thorough risk evaluation of only the adverse events patients. ARI can provide a crucial screening and performance evaluation quality control tool. The ARI method may suit other clinical and epidemiological settings where relatively small fraction of the entire population is affected. Copyright © 2013 Surgical Associates Ltd. Published by Elsevier Ltd. All rights reserved.

The development of prosociality from adolescence to early adulthood: the role of effortful control.

PubMed

Luengo Kanacri, Bernadette P; Pastorelli, Concetta; Eisenberg, Nancy; Zuffianò, Antonio; Caprara, Gian Vittorio

2013-06-01

The present longitudinal study examined the development of self-reported prosociality (i.e., the tendency to enact prosocial behaviors) from adolescence to early adulthood and its prediction from teacher-reported effortful control (i.e., dispositional regulation) at age 13. Participants were 573 (276 girls) Italian adolescents aged approximately 13 (M = 12.98, SD = 0.80) at the first assessment and 21 (M = 21.23, SD = 0.67) at the last assessment. The study used three different cohorts recruited across ten years (from 1994 to 2004) from a larger longitudinal project with a multiple-cohort design. Latent growth curve modeling indicated that the overall level of prosociality declined until approximately age 17 with a subsequent slight rebound until age 21. Significant inter-individual variability in developmental trends of prosociality in males and females was observed. Youths' effortful control was related to a lesser decline of prosociality in adolescence. Being able to regulate one's own emotions and behaviors in early adolescence may not only affect the tendency to behave prosocially, but also counter the self-centered tendencies observed across this phase of development. © 2012 Wiley Periodicals, Inc.

The VCS parameters: Potential hematological indicators for predicting antituberculosis drug-induced neutropenia.

PubMed

Shen, Tian; Gu, Delin; Zhu, Yihua; Shi, Junwei; Xu, Dongsheng; Cao, Xingjian

2016-08-01

The morphological changes in activated neutrophils associated with antituberculosis drugs can be measured by volume, conductivity, and scatter (VCS) technology on the Coulter LH750 hematology analyzer. We conducted the current study to further validate the clinical usefulness of the neutrophil VCS parameters in predicting drug-induced neutropenia. Peripheral blood samples were collected from 52 patients with drug-induced neutropenia, 309 patients without any abnormal CBC, and 237 healthy controls. The mean neutrophil volume (MNV) with its distribution width (NDW) and the mean neutrophil scatter (MNS) were studied. We observed a significant increase in the MNV and NDW as well as a significant decrease in the MNS in neutropenia patients approximately one week prior to development of neutropenia compared to healthy controls as well as to case controls. In addition, the delta MNV and delta MNS were respectively correlated well with delta absolute neutrophil counts when neutropenia occurred. The ROC curve analyses showed that the MNV、NDW and MNS had larger areas under curves compared to conventional parameters. With a cutoff of 150.15 for the MNV, a sensitivity of 84.4% and specificity of 75.7% were achieved prior to neutropenia. The neutrophil VCS parameters may be clinically useful as potential hematological indicators for predicting antituberculosis drug-induced neutropenia. Copyright © 2016 Elsevier B.V. All rights reserved.

Fitting by Orthonormal Polynomials of Silver Nanoparticles Spectroscopic Data

NASA Astrophysics Data System (ADS)

Bogdanova, Nina; Koleva, Mihaela

2018-02-01

Our original Orthonormal Polynomial Expansion Method (OPEM) in one-dimensional version is applied for first time to describe the silver nanoparticles (NPs) spectroscopic data. The weights for approximation include experimental errors in variables. In this way we construct orthonormal polynomial expansion for approximating the curve on a non equidistant point grid. The corridors of given data and criteria define the optimal behavior of searched curve. The most important subinterval of spectra data is investigated, where the minimum (surface plasmon resonance absorption) is looking for. This study describes the Ag nanoparticles produced by laser approach in a ZnO medium forming a AgNPs/ZnO nanocomposite heterostructure.

Collision for Li++He System. I. Potential Curves and Non-Adiabatic Coupling Matrix Elements

NASA Astrophysics Data System (ADS)

Yoshida, Junichi; O-Ohata, Kiyosi

1984-02-01

The potential curves and the non-adiabatic coupling matrix elements for the Li++He collision system were computed. The SCF molecular orbitals were constructed with the CGTO atomic bases centered on each nucleus and the center of mass of two nuclei. The SCF and CI calculations were done at various internuclear distances in the range of 0.1˜25.0 a.u. The potential energies and the wavefunctions were calculated with good approximation over whole internuclear distance. The non-adiabatic coupling matrix elements were calculated with the tentative method in which the ETF are approximately taken into account.

Geodesic survey and modernization of a route as the task of optimization

NASA Astrophysics Data System (ADS)

Nowak, Edward

2014-06-01

A geodesic survey of an existing route requires one to determine the approximation curve by means of optimization using the total least squares method (TLSM). The objective function of the LSM was found to be a square of the Mahalanobis distance in the adjustment field ν. In approximation tasks, the Mahalanobis distance is the distance from a survey point to the desired curve. In the case of linear regression, this distance is codirectional with a coordinate axis; in orthogonal regression, it is codirectional with the normal line to the curve. Accepting the Mahalanobis distance from the survey point as a quasi-observation allows us to conduct adjustment using a numerically exact parametric procedure. Analysis of the potential application of splines under the NURBS (non-uniform rational B-spline) industrial standard with respect to route approximation has identified two issues: a lack of the value of the localizing parameter for a given survey point and the use of vector parameters that define the shape of the curve. The value of the localizing parameter was determined by projecting the survey point onto the curve. This projection, together with the aforementioned Mahalanobis distance, splits the position vector of the curve into two orthogonal constituents within the local coordinate system of the curve. A similar system corresponds to points that form the control polygonal chain and allows us to find their position with the help of a scalar variable that determines the shape of the curve by moving a knot toward the normal line. Inwentaryzacja istniejącej tras y wymaga wyznaczenia krzywej aproksymującej w wyniku optymalizacji realizowanej metodą najmniejszych kwadratów (TLSM). Analiza funkcji celu LSM wykazała, że jest ona kwadratem odległości Mahalanobisa w przestrzeni poprawek. W zadaniach aproksymacyjnych odległość Mahalanobisa jest miarą odstępu pikiety od wyznaczanej krzywej, w przypadku regresji zwykłej odstęp ten ma kierunek osi układu współrzędnych a w przypadku regresji ortogonalnej odstęp ma kierunek normalnej do krzywej. Uznanie odległości Mahalanobisa pikiety od wyznaczanej krzywej za quasi-obserwację pozwala na wykonanie wyrównania dopracowaną numerycznie procedurą parametryczną. Badanie możliwości zastosowania funkcji sklejanych w przemysłowym standardzie NURBS do aprosymacji przebiegu trasy wykazało dwa problemy: brak wartości parametru lokalizującego dla pikiety oraz operowanie parametrami wektorowymi defi lującymi kształt krzywej. Wartość parametru lokalizującego wyznaczono przez rzut pikiety na krzywą - łącznie z opisaną wyżej odległością Mahalanobisa stanowi on rozkład wektora wodzącego pikiety na dwie składowe podłużną i poprzeczną w lokalnym układzie krzywej. Analogiczny układ w punktach tworzących łamaną kontrolną funkcji Beziera pozwala na wyznaczenie ich położenia za pośrednictwem niewiadomej skalarnej modelującej kształt krzywej poprzez przesunięcia węzła w kierunku normalnej.

Effective Clipart Image Vectorization through Direct Optimization of Bezigons.

PubMed

Yang, Ming; Chao, Hongyang; Zhang, Chi; Guo, Jun; Yuan, Lu; Sun, Jian

2016-02-01

Bezigons, i.e., closed paths composed of Bézier curves, have been widely employed to describe shapes in image vectorization results. However, most existing vectorization techniques infer the bezigons by simply approximating an intermediate vector representation (such as polygons). Consequently, the resultant bezigons are sometimes imperfect due to accumulated errors, fitting ambiguities, and a lack of curve priors, especially for low-resolution images. In this paper, we describe a novel method for vectorizing clipart images. In contrast to previous methods, we directly optimize the bezigons rather than using other intermediate representations; therefore, the resultant bezigons are not only of higher fidelity compared with the original raster image but also more reasonable because they were traced by a proficient expert. To enable such optimization, we have overcome several challenges and have devised a differentiable data energy as well as several curve-based prior terms. To improve the efficiency of the optimization, we also take advantage of the local control property of bezigons and adopt an overlapped piecewise optimization strategy. The experimental results show that our method outperforms both the current state-of-the-art method and commonly used commercial software in terms of bezigon quality.

General airplane performance

NASA Technical Reports Server (NTRS)

Rockfeller, W C

1939-01-01

Equations have been developed for the analysis of the performance of the ideal airplane, leading to an approximate physical interpretation of the performance problem. The basic sea-level airplane parameters have been generalized to altitude parameters and a new parameter has been introduced and physically interpreted. The performance analysis for actual airplanes has been obtained in terms of the equivalent ideal airplane in order that the charts developed for use in practical calculations will for the most part apply to any type of engine-propeller combination and system of control, the only additional material required consisting of the actual engine and propeller curves for propulsion unit. Finally, a more exact method for the calculation of the climb characteristics for the constant-speed controllable propeller is presented in the appendix.

Replace-approximation method for ambiguous solutions in factor analysis of ultrasonic hepatic perfusion

NASA Astrophysics Data System (ADS)

Zhang, Ji; Ding, Mingyue; Yuchi, Ming; Hou, Wenguang; Ye, Huashan; Qiu, Wu

2010-03-01

Factor analysis is an efficient technique to the analysis of dynamic structures in medical image sequences and recently has been used in contrast-enhanced ultrasound (CEUS) of hepatic perfusion. Time-intensity curves (TICs) extracted by factor analysis can provide much more diagnostic information for radiologists and improve the diagnostic rate of focal liver lesions (FLLs). However, one of the major drawbacks of factor analysis of dynamic structures (FADS) is nonuniqueness of the result when only the non-negativity criterion is used. In this paper, we propose a new method of replace-approximation based on apex-seeking for ambiguous FADS solutions. Due to a partial overlap of different structures, factor curves are assumed to be approximately replaced by the curves existing in medical image sequences. Therefore, how to find optimal curves is the key point of the technique. No matter how many structures are assumed, our method always starts to seek apexes from one-dimensional space where the original high-dimensional data is mapped. By finding two stable apexes from one dimensional space, the method can ascertain the third one. The process can be continued until all structures are found. This technique were tested on two phantoms of blood perfusion and compared to the two variants of apex-seeking method. The results showed that the technique outperformed two variants in comparison of region of interest measurements from phantom data. It can be applied to the estimation of TICs derived from CEUS images and separation of different physiological regions in hepatic perfusion.

Turtle Graphics of Morphic Sequences

NASA Astrophysics Data System (ADS)

Zantema, Hans

2016-02-01

The simplest infinite sequences that are not ultimately periodic are pure morphic sequences: fixed points of particular morphisms mapping single symbols to strings of symbols. A basic way to visualize a sequence is by a turtle curve: for every alphabet symbol fix an angle, and then consecutively for all sequence elements draw a unit segment and turn the drawing direction by the corresponding angle. This paper investigates turtle curves of pure morphic sequences. In particular, criteria are given for turtle curves being finite (consisting of finitely many segments), and for being fractal or self-similar: it contains an up-scaled copy of itself. Also space-filling turtle curves are considered, and a turtle curve that is dense in the plane. As a particular result we give an exact relationship between the Koch curve and a turtle curve for the Thue-Morse sequence, where until now for such a result only approximations were known.

Lack of post-exercise depression of corticospinal excitability in patients with Parkinson's disease.

PubMed

Khedr, E M; Galal, O; Said, A; Abd-elsameea, M; Rothwell, J C

2007-07-01

There is lack of clarity in the literature over whether patients with Parkinson's disease (PD) show the same post-exercise depression of corticospinal excitability as is usually observed in healthy control. This study set out to resolve the problem. Ten patients with idiopathic PD and 10 age-matched controls were included in this study. Each subject performed a submaximal sustained voluntary contraction of the right first dorsal interosseous muscle (FDI) for 10 min or until force could no longer be sustained. Resting motor threshold, motor-evoked potential (MEP), input-output curve, cortical silent period duration, interference pattern (IP) and M/F ratio were recorded at baseline, immediately after fatigue and after 20 min rest. Immediately after exercise, decreased MEP amplitude and increased cortical SP duration were observed in the control group whilst no such changes were observed in PD patients. The input-output curve was also significantly suppressed only in controls, but not in patients. The amplitude of IP was significantly reduced immediately after exercise in both PD patients and controls. Almost all these changes returned nearly to baseline values after 20 min rest. The amount of exercise was approximately equal in both groups because the effect on M-waves and EMG amplitude was similar. However, the expected decline in corticospinal excitability was absent in PD patients. The absence of this effect in PD patients may reflect reorganization of motor commands in response to basal ganglia deficit.

Interactive modeling and simulation of peripheral nerve cords in virtual environments

NASA Astrophysics Data System (ADS)

Ullrich, Sebastian; Frommen, Thorsten; Eckert, Jan; Schütz, Astrid; Liao, Wei; Deserno, Thomas M.; Ntouba, Alexandre; Rossaint, Rolf; Prescher, Andreas; Kuhlen, Torsten

2008-03-01

This paper contributes to modeling, simulation and visualization of peripheral nerve cords. Until now, only sparse datasets of nerve cords can be found. In addition, this data has not yet been used in simulators, because it is only static. To build up a more flexible anatomical structure of peripheral nerve cords, we propose a hierarchical tree data structure where each node represents a nerve branch. The shape of the nerve segments itself is approximated by spline curves. Interactive modeling allows for the creation and editing of control points which are used for branching nerve sections, calculating spline curves and editing spline representations via cross sections. Furthermore, the control points can be attached to different anatomic structures. Through this approach, nerve cords deform in accordance to the movement of the connected structures, e.g., muscles or bones. As a result, we have developed an intuitive modeling system that runs on desktop computers and in immersive environments. It allows anatomical experts to create movable peripheral nerve cords for articulated virtual humanoids. Direct feedback of changes induced by movement or deformation is achieved by visualization in real-time. The techniques and the resulting data are already used for medical simulators.

Singular perturbation analysis of the steady-state Poisson–Nernst–Planck system: Applications to ion channels

PubMed Central

SINGER, A.; GILLESPIE, D.; NORBURY, J.; EISENBERG, R. S.

2009-01-01

Ion channels are proteins with a narrow hole down their middle that control a wide range of biological function by controlling the flow of spherical ions from one macroscopic region to another. Ion channels do not change their conformation on the biological time scale once they are open, so they can be described by a combination of Poisson and drift-diffusion (Nernst–Planck) equations called PNP in biophysics. We use singular perturbation techniques to analyse the steady-state PNP system for a channel with a general geometry and a piecewise constant permanent charge profile. We construct an outer solution for the case of a constant permanent charge density in three dimensions that is also a valid solution of the one-dimensional system. The asymptotical current–voltage (I–V ) characteristic curve of the device (obtained by the singular perturbation analysis) is shown to be a very good approximation of the numerical I–V curve (obtained by solving the system numerically). The physical constraint of non-negative concentrations implies a unique solution, i.e., for each given applied potential there corresponds a unique electric current (relaxing this constraint yields non-physical multiple solutions for sufficiently large voltages). PMID:19809600

Hexamermis popilliae n. sp. (Nematoda: Mermithidae) parasitizing the Japanese beetle Popillia japonica Newman (Coleoptera: Scarabaeidae) in Italy.

PubMed

Mazza, Giuseppe; Paoli, Francesco; Strangi, Agostino; Torrini, Giulia; Marianelli, Leonardo; Peverieri, Giuseppino Sabbatini; Binazzi, Francesco; Bosio, Giovanni; Sacchi, Stefano; Benvenuti, Claudia; Venanzio, Davide; Giacometto, Emanuela; Roversi, Pio F; Poinar, George O

2017-10-01

A new species of mermithid nematode, Hexamermis popilliae n. sp. (Nematoda: Mermithidae) is described from the Japanese beetle Popillia japonica Newman in Italy, an area of new introduction for this invasive pest. The combination of the following characters separates H. popilliae from other members of the genus Hexamermis Steiner, 1924: adult head obtuse; amphidial pouches slightly posterior to lateral head papillae in female but adjacent to lateral head papillae in males; amphidial openings large, well developed; amphidial pouches elliptical in females and oblong in males; cuticular vulvar cone well developed, vulvar lips greatly reduced or lacking, vagina curved at tip where meeting uteri, without reverse bend (not S-shaped), spicules slightly curved, with a slight bend in the basal portion, approximately equal to body width at cloaca. This is the first record of a species of Hexamermis parasitizing the Japanese beetle Popillia japonica. The only previous mention of mermithid nematodes from P. japonica was an undescribed species of Psammomermis in North America. Hexamermis popilliae will be evaluated as a potential biological control agent in an integrated control program of the Japanese beetle in Italy.

The effect of grid transparency and finite collector size on determining ion temperature and density by the retarding potential analyzer

NASA Technical Reports Server (NTRS)

Troy, B. E., Jr.; Maier, E. J.

1973-01-01

The analysis of ion data from retarding potential analyzers (RPA's) is generally done under the planar approximation, which assumes that the grid transparency is constant with angle of incidence and that all ions reaching the plane of the collectors are collected. These approximations are not valid for situations in which the ion thermal velocity is comparable to the vehicle velocity, causing ions to enter the RPA with high average transverse velocity. To investigate these effects, the current-voltage curves for H+ at 4000 K were calculated, taking into account the finite collector size and the variation of grid transparency with angle. These curves are then analyzed under the planar approximation. The results show that only small errors in temperature and density are introduced for an RPA with typical dimensions; and that even when the density error is substantial for non-typical dimensions, the temperature error remains minimal.

The training and learning process of transseptal puncture using a modified technique.

PubMed

Yao, Yan; Ding, Ligang; Chen, Wensheng; Guo, Jun; Bao, Jingru; Shi, Rui; Huang, Wen; Zhang, Shu; Wong, Tom

2013-12-01

As the transseptal (TS) puncture has become an integral part of many types of cardiac interventional procedures, its technique that was initial reported for measurement of left atrial pressure in 1950s, continue to evolve. Our laboratory adopted a modified technique which uses only coronary sinus catheter as the landmark to accomplishing TS punctures under fluoroscopy. The aim of this study is prospectively to evaluate the training and learning process for TS puncture guided by this modified technique. Guided by the training protocol, TS puncture was performed in 120 consecutive patients by three trainees without previous personal experience in TS catheterization and one experienced trainer as a controller. We analysed the following parameters: one puncture success rate, total procedure time, fluoroscopic time, and radiation dose. The learning curve was analysed using curve-fitting methodology. The first attempt at TS crossing was successful in 74 (82%), a second attempt was successful in 11 (12%), and 5 patients failed to puncture the interatrial septal finally. The average starting process time was 4.1 ± 0.8 min, and the estimated mean learning plateau was 1.2 ± 0.2 min. The estimated mean learning rate for process time was 25 ± 3 cases. Important aspects of learning curve can be estimated by fitting inverse curves for TS puncture. The study demonstrated that this technique was a simple, safe, economic, and effective approach for learning of TS puncture. Base on the statistical analysis, approximately 29 TS punctures will be needed for trainee to pass the steepest area of learning curve.

Evapotranspiration Controls Imposed by Soil Moisture: A Spatial Analysis across the United States

NASA Astrophysics Data System (ADS)

Rigden, A. J.; Tuttle, S. E.; Salvucci, G.

2014-12-01

We spatially analyze the control over evapotranspiration (ET) imposed by soil moisture across the United States using daily estimates of satellite-derived soil moisture and data-driven ET over a nine-year period (June 2002-June 2011) at 305 locations. The soil moisture data are developed using 0.25-degree resolution satellite observations from the Advanced Microwave Scanning Radiometer for the Earth Observing System (AMSR-E), where the 9-year time series for each 0.25-degree pixel was selected from three potential algorithms (VUA-NASA, U. Montana, & NASA) based on the maximum mutual information between soil moisture and precipitation (Tuttle & Salvucci (2014), Remote Sens Environ, 114: 207-222). The ET data are developed independent of soil moisture using an emergent relationship between the diurnal cycle of the relative humidity profile and ET. The emergent relation is that the vertical variance of the relative humidity profile is less than what would occur for increased or decreased ET rates, suggesting that land-atmosphere feedback processes minimize this variance (Salvucci and Gentine (2013), PNAS, 110(16): 6287-6291). The key advantage of using this approach to estimate ET is that no measurements of surface limiting factors (soil moisture, leaf area, canopy conductance) are required; instead, ET is estimated from meteorological data measured at 305 common weather stations that are approximately uniformly distributed across the United States. The combination of these two independent datasets allows for a unique spatial analysis of the control on ET imposed by the availability of soil moisture. We fit evaporation efficiency curves across the United States at each of the 305 sites during the summertime (May-June-July-August-September). Spatial patterns are visualized by mapping optimal curve fitting coefficients across the Unites States. An analysis of efficiency curves and their spatial patterns will be presented.

The ASCA PV phase observation of FO Aquarii

NASA Technical Reports Server (NTRS)

Mukai, Koji; Ishida, Manabu; Osborne, Julian P.

1994-01-01

We report on a approximately 1-day Advanced Satellite for Cosmology and Astrophysics (ASCA) observation of the intermediate polar FO Aquarii. We find two distinctive spectral components, one unabsorbed and the other strongly absorbed; the observed 2-10 keV flux severely underestimates the total system luminosity, due to this strong absorption intrinsic to the binary. The absorbed component is dominant in terms of luminosity, and its light curve is simple. The unabsorbed component accounts for approximately 2% of the luminosity, and shows a much more complicated light curve. As the dominant component predominantly shows a sinusoidal modulation at the white dwarf spin period, it provides a strong evidence for a partial accretion disk in the system.

Traveltime and dispersion in the Shenandoah River and its tributaries, Waynesboro, Virginia, to Harpers Ferry, West Virginia

USGS Publications Warehouse

Taylor, K.R.; James, R.W.; Helinsky, B.M.

1986-01-01

Two traveltime and dispersion measurements using rhodamin dye were conducted on a 178-mile reach of the Shenandoah River between Waynesboro, Virginia, and Harpers Ferry, West Virginia. The flows during the two measurements were at approximately the 85% and 45% flow durations. The two sets of data were used to develop a generalized procedure for predicting traveltimes and downstream concentrations resulting from spillage of water soluble substances at any point along the river reach studied. The procedure can be used to calculate traveltime and concentration data for almost any spillage that occurs during relatively steady flow between a 40% to 95% flow duration. Based on an analogy between the general shape of a time concentration curve and a scalene triangle, the procedures can be used on long river reaches to approximate the conservative time concentration curve for instantaneous spills of contaminants. The triangular approximation technique can be combined with a superposition technique to predict the approximate, conservative time concentration curve for constant rate and variable rate injections of contaminants. The procedure was applied to a hypothetical situation in which 5,000 pounds of contaminants is spilled instantaneously at Island Ford, Virginia. The times required for the leading edge, the peak concentration, and the trailing edge of the contaminant cloud to reach the water intake at Front Royal, Virginia (85 miles downstream), are 234,280, and 340 hrs, respectively, for a flow at an 80% flow duration. The conservative peak concentration would be approximately 940 micrograms/L at Front Royal. The procedures developed cannot be depended upon when a significant hydraulic wave or other unsteady flow condition exists in the flow system or when the spilled material floats or is immiscible in water. (Author 's abstract)

Copper nanoparticles impinging on a curved channel with compliant walls and peristalsis

NASA Astrophysics Data System (ADS)

Akbar, Noreen Sher; Maraj, E. N.; Butt, Adil Wahid

2014-08-01

In the present article peristaltic transport of copper nanofluids in a curved channel with compliant walls is analytically studied. The mathematical analysis is carried out under the low Reynolds number and long wavelenght approximation. The exact solutions are computed for fluid velocity and temperature profile. The effect of meaningful parameters are shown graphically in the last section.

Dynamics of curved fronts in systems with power-law memory

NASA Astrophysics Data System (ADS)

Abu Hamed, M.; Nepomnyashchy, A. A.

2016-08-01

The dynamics of a curved front in a plane between two stable phases with equal potentials is modeled via two-dimensional fractional in time partial differential equation. A closed equation governing a slow motion of a small-curvature front is derived and applied for two typical examples of the potential function. Approximate axisymmetric and non-axisymmetric solutions are obtained.

Thermoluminescence kinetics of pyrite (FeS2)

NASA Astrophysics Data System (ADS)

Silverman, A. N.; Levy, P. W.; Kierstead, J. A.

Thermoluminescence of pyrite (FeS2) was investigated to study the kinetics of single peak glow curves. The material used normally exhibits one large and four small peaks. However a glow curve can be obtained with only the large single peak that is suitable for testing thermoluminescence kinetics. Glow curves from aliquots of a single natural pyrite crystal studied in detail contain two low intensity thermoluminescence (TL) peaks at approximately 90 and 250 C, and two chemiluminescence (CL) peaks at approximately 350 and 430 C. The CL peaks are largely removable by initially heating the sample chamber under vacuum, pumping through liquid nitrogen traps, and recording glow curves immediately after helium is introduced, procedures which reduce system contaminants that react with pyrite. The shape, the variation of the temperature of the peak maximum (T(sub max)) with dose, and the retrapping to recombination cross section ratio (sigma) of the large 250 C peak are better described by the general one trap (GOT) kinetic equation, the basic equation from which the 1st and 2nd order kinetic equations are obtained as special cases, than by the 1st and 2nd order equations.

A phase response curve to single bright light pulses in human subjects

NASA Technical Reports Server (NTRS)

Khalsa, Sat Bir S.; Jewett, Megan E.; Cajochen, Christian; Czeisler, Charles A.

2003-01-01

The circadian pacemaker is differentially sensitive to the resetting effects of retinal light exposure, depending upon the circadian phase at which the light exposure occurs. Previously reported human phase response curves (PRCs) to single bright light exposures have employed small sample sizes, and were often based on relatively imprecise estimates of circadian phase and phase resetting. In the present study, 21 healthy, entrained subjects underwent pre- and post-stimulus constant routines (CRs) in dim light (approximately 2-7 lx) with maintained wakefulness in a semi-recumbent posture. The 6.7 h bright light exposure stimulus consisted of alternating 6 min fixed gaze (approximately 10 000 lx) and free gaze (approximately 5000-9000 lx) exposures. Light exposures were scheduled across the circadian cycle in different subjects so as to derive a PRC. Plasma melatonin was used to determine the phase of the onset, offset, and midpoint of the melatonin profiles during the CRs. Phase shifts were calculated as the difference in phase between the pre- and post-stimulus CRs. The resultant PRC of the midpoint of the melatonin rhythm revealed a characteristic type 1 PRC with a significant peak-to-trough amplitude of 5.02 h. Phase delays occurred when the light stimulus was centred prior to the critical phase at the core body temperature minimum, phase advances occurred when the light stimulus was centred after the critical phase, and no phase shift occurred at the critical phase. During the subjective day, no prolonged 'dead zone' of photic insensitivity was apparent. Phase shifts derived using the melatonin onsets showed larger magnitudes than those derived from the melatonin offsets. These data provide a comprehensive characterization of the human PRC under highly controlled laboratory conditions.

Methylation-sensitive high-resolution melting-curve analysis of the SNRPN gene as a diagnostic screen for Prader-Willi and Angelman syndromes.

PubMed

White, Helen E; Hall, Victoria J; Cross, Nicholas C P

2007-11-01

Angelman syndrome (AS) and Prader-Willi syndrome (PWS) are 2 distinct neurodevelopmental disorders caused primarily by deficiency of specific parental contributions at an imprinted domain within the chromosomal region 15q11.2-13. Lack of paternal contribution results in PWS either by paternal deletion (approximately 70%) or maternal uniparental disomy (UPD) (approximately 25%). Most cases of AS result from the lack of a maternal contribution from this same region, by maternal deletion (70%) or paternal UPD (approximately 5%). Analysis of allelic methylation differences at the small nuclear ribonucleoprotein polypeptide N (SNRPN) locus differentiates the maternally and paternally inherited chromosome 15 and can be used as a diagnostic test for AS and PWS. Methylation-sensitive high-resolution melting-curve analysis (MS-HRM) using the DNA binding dye EvaGreen was used to analyze methylation differences at the SNRPN locus in anonymized DNA samples from individuals with PWS (n = 39) or AS (n = 31) and from healthy control individuals (n = 95). Results from the MS-HRM assay were compared to those obtained by use of a methylation-specific PCR (MSP) protocol that is used commonly in diagnostic practice. With the MS-HRM assay 97.6% of samples were unambiguously assigned to the 3 diagnostic categories (AS, PWS, normal) by use of automated calling with an 80% confidence percentage threshold, and the failure rate was 0.6%. One PWS sample showed a discordant result for the MS-HRM assay compared to MSP data. MS-HRM is a simple, rapid, and robust method for screening methylation differences at the SNRPN locus and could be used as a diagnostic screen for PWS and AS.

New Bernstein type inequalities for polynomials on ellipses

NASA Technical Reports Server (NTRS)

Freund, Roland; Fischer, Bernd

1990-01-01

New and sharp estimates are derived for the growth in the complex plane of polynomials known to have a curved majorant on a given ellipse. These so-called Bernstein type inequalities are closely connected with certain constrained Chebyshev approximation problems on ellipses. Also presented are some new results for approximation problems of this type.

Interior Temperature Measurement Using Curved Mercury Capillary Sensor Based on X-ray Radiography

NASA Astrophysics Data System (ADS)

Chen, Shuyue; Jiang, Xing; Lu, Guirong

2017-07-01

A method was presented for measuring the interior temperature of objects using a curved mercury capillary sensor based on X-ray radiography. The sensor is composed of a mercury bubble, a capillary and a fixed support. X-ray digital radiography was employed to capture image of the mercury column in the capillary, and a temperature control system was designed for the sensor calibration. We adopted livewire algorithms and mathematical morphology to calculate the mercury length. A measurement model relating mercury length to temperature was established, and the measurement uncertainty associated with the mercury column length and the linear model fitted by least-square method were analyzed. To verify the system, the interior temperature measurement of an autoclave, which is totally closed, was taken from 29.53°C to 67.34°C. The experiment results show that the response of the system is approximately linear with an uncertainty of maximum 0.79°C. This technique provides a new approach to measure interior temperature of objects.

Measurement of fracture stress for 6000-series extruded aluminum alloy tube using multiaxial tube expansion testing method

NASA Astrophysics Data System (ADS)

Nagai, Keisuke; Kuwabara, Toshihiko; Ilinich, Andrey; Luckey, George

2018-05-01

A servo-controlled tension-internal pressure testing machine with an optical 3D digital image correlation system (DIC) is used to measure the multiaxial deformation behavior of an extruded aluminum alloy tube for a strain range from initial yield to fracture. The outer diameter of the test sample is 50.8 mm and wall thickness 2.8 mm. Nine linear stress paths are applied to the specimens: σɸ (axial true stress component) : σθ (circumferential true stress component) = 1:0, 4:1, 2:1, 4:3, 1:1, 3:4, 1:2, 1:4, and 0:1. The equivalent strain rate is approximately 5 × 10-4 s-1 constant. The forming limit curve (FLC) and forming limit stress curve (FLSC) are also measured. Moreover, the average true stress components inside a localized necking area are determined for each specimen from the thickness strain data for the localized necking area and the geometry of the fracture surface.

Numerical approximations of the mean absorption cross-section of a variety of randomly oriented microalgal shapes.

PubMed

Baird, Mark E

2003-10-01

The size, shape, and absorption coefficient of a microalgal cell determines, to a first order approximation, the rate at which light is absorbed by the cell. The rate of absorption determines the maximum amount of energy available for photosynthesis, and can be used to calculate the attenuation of light through the water column, including the effect of packaging pigments within discrete particles. In this paper, numerical approximations are made of the mean absorption cross-section of randomly oriented cells, aA. The shapes investigated are spheroids, rectangular prisms with a square base, cylinders, cones and double cones with aspect ratios of 0.25, 0.5, 1, 2, and 4. The results of the numerical simulations are fitted to a modified sigmoid curve, and take advantage of three analytical solutions. The results are presented in a non-dimensionalised format and are independent of size. A simple approximation using a rectangular hyperbolic curve is also given, and an approach for obtaining the upper and lower bounds of aA for more complex shapes is outlined.

Structure and phase behavior of a confined nanodroplet composed of the flexible chain molecules.

PubMed

Kim, Soon-Chul; Kim, Eun-Young; Seong, Baek-Seok

2011-04-28

A polymer density functional theory has been employed for investigating the structure and phase behaviors of the chain polymer, which is modelled as the tangentially connected sphere chain with an attractive interaction, inside the nanosized pores. The excess free energy of the chain polymer has been approximated as the modified fundamental measure-theory for the hard spheres, the Wertheim's first-order perturbation for the chain connectivity, and the mean-field approximation for the van der Waals contribution. For the value of the chemical potential corresponding to a stable liquid phase in the bulk system and a metastable vapor phase, the flexible chain molecules undergo the liquid-vapor transition as the pore size is reduced; the vapor is the stable phase at small volume, whereas the liquid is the stable phase at large volume. The wide liquid-vapor coexistence curve, which explains the wide range of metastable liquid-vapor states, is observed at low temperature. The increase of temperature and decrease of pore size result in a narrowing of liquid-vapor coexistence curves. The increase of chain length leads to a shift of the liquid-vapor coexistence curve towards lower values of chemical potential. The coexistence curves for the confined phase diagram are contained within the corresponding bulk liquid-vapor coexistence curve. The equilibrium capillary phase transition occurs at a higher chemical potential than in the bulk phase.

Expression, crosslinking, and developing modulus master curves of recombinant resilin.

PubMed

Khandaker, Md Shahriar K; Dudek, Daniel M; Beers, Eric P; Dillard, David A

2017-05-01

Resilin is a disordered elastomeric protein found in specialized regions of insect cuticles, where low stiffness and high resilience are required. Having a wide range of functions that vary among insect species, resilin operates across a wide frequency range, from 5Hz for locomotion to 13kHz for sound production. We synthesize and crosslink a recombinant resilin from clone-1 (exon-1+exon-2) of the gene, and determine the water content (approximately 80wt%) and dynamic mechanical properties, along with estimating surface energies relevant for adhesion. Dynamic moduli master curves have been developed, by applying the time-temperature superposition principle (TTSP) and time-temperature concentration superposition principle (TTCSP), and compared with reported master curves for natural resilin from locusts, dragonflies, and cockroaches. To our knowledge, this is the first time dynamic moduli master curves have been developed to explore the dynamic mechanical properties of recombinant resilin and compare with resilin behavior. The resulting master curves show that the synthetic resilin undergoes a pronounced transition with increasing ethanol concentrations, with the storage modulus increasing by approximately three orders of magnitude. Although possibly a glass transition, alternate explanations include the formation of intramolecular hydrogen bonds or that the chitin binding domain (ChBD) in exon-2 might change the secondary structure of the normally disordered exon-1 into more ordered conformations that limit deformation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Classification of ASKAP Vast Radio Light Curves

NASA Technical Reports Server (NTRS)

Rebbapragada, Umaa; Lo, Kitty; Wagstaff, Kiri L.; Reed, Colorado; Murphy, Tara; Thompson, David R.

2012-01-01

The VAST survey is a wide-field survey that observes with unprecedented instrument sensitivity (0.5 mJy or lower) and repeat cadence (a goal of 5 seconds) that will enable novel scientific discoveries related to known and unknown classes of radio transients and variables. Given the unprecedented observing characteristics of VAST, it is important to estimate source classification performance, and determine best practices prior to the launch of ASKAP's BETA in 2012. The goal of this study is to identify light curve characterization and classification algorithms that are best suited for archival VAST light curve classification. We perform our experiments on light curve simulations of eight source types and achieve best case performance of approximately 90% accuracy. We note that classification performance is most influenced by light curve characterization rather than classifier algorithm.

On the validity of the dispersion model of hepatic drug elimination when intravascular transit time densities are long-tailed.

PubMed

Weiss, M; Stedtler, C; Roberts, M S

1997-09-01

The dispersion model with mixed boundary conditions uses a single parameter, the dispersion number, to describe the hepatic elimination of xenobiotics and endogenous substances. An implicit a priori assumption of the model is that the transit time density of intravascular indicators is approximately by an inverse Gaussian distribution. This approximation is limited in that the model poorly describes the tail part of the hepatic outflow curves of vascular indicators. A sum of two inverse Gaussian functions is proposed as an alternative, more flexible empirical model for transit time densities of vascular references. This model suggests that a more accurate description of the tail portion of vascular reference curves yields an elimination rate constant (or intrinsic clearance) which is 40% less than predicted by the dispersion model with mixed boundary conditions. The results emphasize the need to accurately describe outflow curves in using them as a basis for determining pharmacokinetic parameters using hepatic elimination models.

Optimal landing of a helicopter in autorotation

NASA Technical Reports Server (NTRS)

Lee, A. Y. N.

1985-01-01

Gliding descent in autorotation is a maneuver used by helicopter pilots in case of engine failure. The landing of a helicopter in autorotation is formulated as a nonlinear optimal control problem. The OH-58A helicopter was used. Helicopter vertical and horizontal velocities, vertical and horizontal displacement, and the rotor angle speed were modeled. An empirical approximation for the induced veloctiy in the vortex-ring state were provided. The cost function of the optimal control problem is a weighted sum of the squared horizontal and vertical components of the helicopter velocity at touchdown. Optimal trajectories are calculated for entry conditions well within the horizontal-vertical restriction curve, with the helicopter initially in hover or forwared flight. The resultant two-point boundary value problem with path equality constraints was successfully solved using the Sequential Gradient Restoration Technique.

Numerical analysis of interface debonding detection in bonded repair with Rayleigh waves

NASA Astrophysics Data System (ADS)

Xu, Ying; Li, BingCheng; Lu, Miaomiao

2017-01-01

This paper studied how to use the variation of the dispersion curves of Rayleigh wave group velocity to detect interfacial debonding damage between FRP plate and steel beam. Since FRP strengthened steel beam is two layers medium, Rayleigh wave velocity dispersion phenomenon will happen. The interface debonding damage of FRP strengthened steel beam have an obvious effect on the Rayleigh wave velocity dispersion curve. The paper first put forward average Euclidean distance and Angle separation degree to describe the relationship between the different dispersion curves. Numerical results indicate that there is a approximate linear mapping relationship between the average Euclidean distance of dispersion curves and the length of interfacial debonding damage.

Modeling the effect of control on the wake of a utility-scale turbine via large-eddy simulation

NASA Astrophysics Data System (ADS)

Yang, Xiaolei; Annoni, Jennifer; Seiler, Pete; Sotiropoulos, Fotis

2014-06-01

A model of the University of Minnesota EOLOS research turbine (Clipper Liberty C96) is developed, integrating the C96 torque control law with a high fidelity actuator line large- eddy simulation (LES) model. Good agreement with the blade element momentum theory is obtained for the power coefficient curve under uniform inflow. Three different cases, fixed rotor rotational speed ω, fixed tip-speed ratio (TSR) and generator torque control, have been simulated for turbulent inflow. With approximately the same time-averaged ω, the time- averaged power is in good agreement with measurements for all three cases. Although the time-averaged aerodynamic torque is nearly the same for the three cases, the root-mean-square (rms) of the aerodynamic torque fluctuations is significantly larger for the case with fixed ω. No significant differences have been observed for the time-averaged flow fields behind the turbine for these three cases.

Boolean Operations with Prism Algebraic Patches

PubMed Central

Bajaj, Chandrajit; Paoluzzi, Alberto; Portuesi, Simone; Lei, Na; Zhao, Wenqi

2009-01-01

In this paper we discuss a symbolic-numeric algorithm for Boolean operations, closed in the algebra of curved polyhedra whose boundary is triangulated with algebraic patches (A-patches). This approach uses a linear polyhedron as a first approximation of both the arguments and the result. On each triangle of a boundary representation of such linear approximation, a piecewise cubic algebraic interpolant is built, using a C1-continuous prism algebraic patch (prism A-patch) that interpolates the three triangle vertices, with given normal vectors. The boundary representation only stores the vertices of the initial triangulation and their external vertex normals. In order to represent also flat and/or sharp local features, the corresponding normal-per-face and/or normal-per-edge may be also given, respectively. The topology is described by storing, for each curved triangle, the two triples of pointers to incident vertices and to adjacent triangles. For each triangle, a scaffolding prism is built, produced by its extreme vertices and normals, which provides a containment volume for the curved interpolating A-patch. When looking for the result of a regularized Boolean operation, the 0-set of a tri-variate polynomial within each such prism is generated, and intersected with the analogous 0-sets of the other curved polyhedron, when two prisms have non-empty intersection. The intersection curves of the boundaries are traced and used to decompose each boundary into the 3 standard classes of subpatches, denoted in, out and on. While tracing the intersection curves, the locally refined triangulation of intersecting patches is produced, and added to the boundary representation. PMID:21516262

The Buckling of Curved Tension-field Girders

NASA Technical Reports Server (NTRS)

Limpert, G

1938-01-01

The present paper reports on experiments made to determine the buckling load under shear of circular curved tension-field webs. The buckling load of the webs may be expressed with reference to the buckling load of the stiffeners. It is found that within the explored range the buckling load is approximately twice as great as that of the identically stiffened flat wall of equal web depth.

Preliminary Investigation of Several Root Designs for Cermet Turbine Blades in Turbojet Engine III : Curved-root Design

NASA Technical Reports Server (NTRS)

Pinkel, Benjamin; Deutsch, George C; Morgan, William C

1955-01-01

Stresses om tje root fastenings of turbine blades were appreciably reduced by redesign of the root. The redesign consisted in curving the root to approximately conform to the camber of the airfoil and elimination of the blade platform. Full-scale jet-engine tests at rated speed using cermet blades of the design confirmed the improvement.

Quasi-radial modes of rotating stars in general relativity

NASA Astrophysics Data System (ADS)

Yoshida, Shin'ichirou; Eriguchi, Yoshiharu

2001-04-01

By using the Cowling approximation, quasi-radial modes of rotating general relativistic stars are computed along equilibrium sequences from non-rotating to maximally rotating models. The eigenfrequencies of these modes are decreasing functions of the rotational frequency. The eigenfrequency curve of each mode as a function of the rotational frequency has discontinuities, which arise from the avoided crossing with other curves of axisymmetric modes.

HgCdTe Surface Study Program

DTIC Science & Technology

1982-09-01

which the virtual crystal approximation breaks down using PES. This is well understood and was confirmed theoretically , working with Arden Sher of SRI...Quasistatic Capacitance of SiC on Hg07 Cd0 Te Treated with HF to Remove Native Oxide, Compared to Theoretical Curve...MIS devices show near ideal behav- ior. Figure I shows capacitance data taken quasistatically and at 1 MHz (dashed curves), compared to a theoretically

Adapting Shape Parameters for Cubic Bezier Curves

NASA Technical Reports Server (NTRS)

Isacoff, D.; Bailey, M. J.

1985-01-01

Bezier curves are an established tool in Computer Aided Geometric Design. One of the drawbacks of the Bezier method is that the curves often bear little resemblance to their control polygons. As a result, it becomes increasingly difficult to obtain anything but a rough outline of the desired shape. One possible solution is tomanipulate the curve itself instead of the control polygon. The standard cubic Bezier curve form has introduced into it two shape parameters, gamma 1 and 2. These parameters give the user the ability to manipulate the curve while the control polygon retains its original form, thereby providing a more intuitive feel for the necessary changes to the curve in order to achieve the desired shape.

Nested taxa-area curves for eastern United States floras

USGS Publications Warehouse

Bennett, J.P.

1997-01-01

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

Linearization of Positional Response Curve of a Fiber-optic Displacement Sensor

NASA Astrophysics Data System (ADS)

Babaev, O. G.; Matyunin, S. A.; Paranin, V. D.

2018-01-01

Currently, the creation of optical measuring instruments and sensors for measuring linear displacement is one of the most relevant problems in the area of instrumentation. Fiber-optic contactless sensors based on the magneto-optical effect are of special interest. They are essentially contactless, non-electrical and have a closed optical channel not subject to contamination. The main problem of this type of sensors is the non-linearity of their positional response curve due to the hyperbolic nature of the magnetic field intensity variation induced by moving the magnetic source mounted on the controlled object relative to the sensing element. This paper discusses an algorithmic method of linearizing the positional response curve of fiber-optic displacement sensors in any selected range of the displacements to be measured. The method is divided into two stages: 1 - definition of the calibration function, 2 - measurement and linearization of the positional response curve (including its temperature stabilization). The algorithm under consideration significantly reduces the number of points of the calibration function, which is essential for the calibration of temperature dependence, due to the use of the points that randomly deviate from the grid points with uniform spacing. Subsequent interpolation of the deviating points and piecewise linear-plane approximation of the calibration function reduces the microcontroller storage capacity for storing the calibration function and the time required to process the measurement results. The paper also presents experimental results of testing real samples of fiber-optic displacement sensors.

Compound windows of the Hénon-map

NASA Astrophysics Data System (ADS)

Lorenz, Edward N.

2008-08-01

For the two-parameter second-order Hénon map, the shapes and locations of the periodic windows-continua of parameter values for which solutions x0,x1,… can be stably periodic, embedded in larger regions where chaotic solutions or solutions of other periods prevail-are found by a random searching procedure and displayed graphically. Many windows have a typical shape, consisting of a central “body” from which four narrow “antennae” extend. Such windows, to be called compound windows, are often arranged in bands, to be called window streets, that are made up largely of small detected but poorly resolved compound windows. For each fundamental subwindow-the portion of a window where a fundamental period prevails-a stability measure U is introduced; where the solution is stable, |U|<1. Curves of constant U are found by numerical integration. Along one line in parameter space the Hénon-map reduces to the one-parameter first-order logistic map, and two antennae from each compound window intersect this line. The curves where U=1 and U=-1 that bound either antenna are close together within these intersections, but, as either curve with U=-1 leaves the line, it diverges from the curve where U=1, crosses the other curve where U=-1, and nears the other curve where U=1, forming another antenna. The region bounded by the numerically determined curves coincides with the subwindow as found by random searching. A fourth-degree equation for an idealized curve of constant U is established. Points in parameter space producing periodic solutions where x0=xm=0, for given values of m, are found to lie on Cantor sets of curves that closely fit the window streets. Points producing solutions where x0=xm=0 and satisfying a third condition, approximating the condition that xn be bounded as n→-∞, lie on curves, to be called street curves of order m, that approximate individual members of the Cantor set and individual window streets. Compound windows of period m+m‧ tend to occur near the intersections of street curves of orders m and m‧. Some exceptions to what appear to be fairly general results are noted. The exceptions render it difficult to establish general theorems.

The Relationship between Root Mean Square Error of Approximation and Model Misspecification in Confirmatory Factor Analysis Models

ERIC Educational Resources Information Center

Savalei, Victoria

2012-01-01

The fit index root mean square error of approximation (RMSEA) is extremely popular in structural equation modeling. However, its behavior under different scenarios remains poorly understood. The present study generates continuous curves where possible to capture the full relationship between RMSEA and various "incidental parameters," such as…

A New Approach for Obtaining Cosmological Constraints from Type Ia Supernovae using Approximate Bayesian Computation

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

Jennings, Elise; Wolf, Rachel; Sako, Masao

2016-11-09

Cosmological parameter estimation techniques that robustly account for systematic measurement uncertainties will be crucial for the next generation of cosmological surveys. We present a new analysis method, superABC, for obtaining cosmological constraints from Type Ia supernova (SN Ia) light curves using Approximate Bayesian Computation (ABC) without any likelihood assumptions. The ABC method works by using a forward model simulation of the data where systematic uncertainties can be simulated and marginalized over. A key feature of the method presented here is the use of two distinct metrics, the `Tripp' and `Light Curve' metrics, which allow us to compare the simulated data to the observed data set. The Tripp metric takes as input the parameters of models fit to each light curve with the SALT-II method, whereas the Light Curve metric uses the measured fluxes directly without model fitting. We apply the superABC sampler to a simulated data set ofmore » $$\\sim$$1000 SNe corresponding to the first season of the Dark Energy Survey Supernova Program. Varying $$\\Omega_m, w_0, \\alpha$$ and $$\\beta$$ and a magnitude offset parameter, with no systematics we obtain $$\\Delta(w_0) = w_0^{\\rm true} - w_0^{\\rm best \\, fit} = -0.036\\pm0.109$$ (a $$\\sim11$$% 1$$\\sigma$$ uncertainty) using the Tripp metric and $$\\Delta(w_0) = -0.055\\pm0.068$$ (a $$\\sim7$$% 1$$\\sigma$$ uncertainty) using the Light Curve metric. Including 1% calibration uncertainties in four passbands, adding 4 more parameters, we obtain $$\\Delta(w_0) = -0.062\\pm0.132$$ (a $$\\sim14$$% 1$$\\sigma$$ uncertainty) using the Tripp metric. Overall we find a $17$% increase in the uncertainty on $$w_0$$ with systematics compared to without. We contrast this with a MCMC approach where systematic effects are approximately included. We find that the MCMC method slightly underestimates the impact of calibration uncertainties for this simulated data set.« less

Experimental Observation of Two Features Unexpected from the Classical Theories of Rubber Elasticity

NASA Astrophysics Data System (ADS)

Nishi, Kengo; Fujii, Kenta; Chung, Ung-il; Shibayama, Mitsuhiro; Sakai, Takamasa

2017-12-01

Although the elastic modulus of a Gaussian chain network is thought to be successfully described by classical theories of rubber elasticity, such as the affine and phantom models, verification experiments are largely lacking owing to difficulties in precisely controlling of the network structure. We prepared well-defined model polymer networks experimentally, and measured the elastic modulus G for a broad range of polymer concentrations and connectivity probabilities, p . In our experiment, we observed two features that were distinct from those predicted by classical theories. First, we observed the critical behavior G ˜|p -pc|1.95 near the sol-gel transition. This scaling law is different from the prediction of classical theories, but can be explained by analogy between the electric conductivity of resistor networks and the elasticity of polymer networks. Here, pc is the sol-gel transition point. Furthermore, we found that the experimental G -p relations in the region above C* did not follow the affine or phantom theories. Instead, all the G /G0-p curves fell onto a single master curve when G was normalized by the elastic modulus at p =1 , G0. We show that the effective medium approximation for Gaussian chain networks explains this master curve.

Spatially varying dispersion to model breakthrough curves.

PubMed

Li, Guangquan

2011-01-01

Often the water flowing in a karst conduit is a combination of contaminated water entering at a sinkhole and cleaner water released from the limestone matrix. Transport processes in the conduit are controlled by advection, mixing (dilution and dispersion), and retention-release. In this article, a karst transport model considering advection, spatially varying dispersion, and dilution (from matrix seepage) is developed. Two approximate Green's functions are obtained using transformation of variables, respectively, for the initial-value problem and for the boundary-value problem. A numerical example illustrates that mixing associated with strong spatially varying conduit dispersion can cause strong skewness and long tailing in spring breakthrough curves. Comparison of the predicted breakthrough curve against that measured from a dye-tracing experiment between Ames Sink and Indian Spring, Northwest Florida, shows that the conduit dispersivity can be as large as 400 m. Such a large number is believed to imply strong solute interaction between the conduit and the matrix and/or multiple flow paths in a conduit network. It is concluded that Taylor dispersion is not dominant in transport in a karst conduit, and the complicated retention-release process between mobile- and immobile waters may be described by strong spatially varying conduit dispersion. Copyright © 2010 The Author(s). Journal compilation © 2010 National Ground Water Association.

Modeling, control, and simulation of grid connected intelligent hybrid battery/photovoltaic system using new hybrid fuzzy-neural method.

PubMed

Rezvani, Alireza; Khalili, Abbas; Mazareie, Alireza; Gandomkar, Majid

2016-07-01

Nowadays, photovoltaic (PV) generation is growing increasingly fast as a renewable energy source. Nevertheless, the drawback of the PV system is its dependence on weather conditions. Therefore, battery energy storage (BES) can be considered to assist for a stable and reliable output from PV generation system for loads and improve the dynamic performance of the whole generation system in grid connected mode. In this paper, a novel topology of intelligent hybrid generation systems with PV and BES in a DC-coupled structure is presented. Each photovoltaic cell has a specific point named maximum power point on its operational curve (i.e. current-voltage or power-voltage curve) in which it can generate maximum power. Irradiance and temperature changes affect these operational curves. Therefore, the nonlinear characteristic of maximum power point to environment has caused to development of different maximum power point tracking techniques. In order to capture the maximum power point (MPP), a hybrid fuzzy-neural maximum power point tracking (MPPT) method is applied in the PV system. Obtained results represent the effectiveness and superiority of the proposed method, and the average tracking efficiency of the hybrid fuzzy-neural is incremented by approximately two percentage points in comparison to the conventional methods. It has the advantages of robustness, fast response and good performance. A detailed mathematical model and a control approach of a three-phase grid-connected intelligent hybrid system have been proposed using Matlab/Simulink. Copyright © 2016 ISA. Published by Elsevier Ltd. All rights reserved.

Functional approach to exploring climatic and landscape controls of runoff generation: 1. Behavioral constraints on runoff volume

NASA Astrophysics Data System (ADS)

Li, Hong-Yi; Sivapalan, Murugesu; Tian, Fuqiang; Harman, Ciaran

2014-12-01

Inspired by the Dunne diagram, the climatic and landscape controls on the partitioning of annual runoff into its various components (Hortonian and Dunne overland flow and subsurface stormflow) are assessed quantitatively, from a purely theoretical perspective. A simple distributed hydrologic model has been built sufficient to simulate the effects of different combinations of climate, soil, and topography on the runoff generation processes. The model is driven by a sequence of simple hypothetical precipitation events, for a large combination of climate and landscape properties, and hydrologic responses at the catchment scale are obtained through aggregation of grid-scale responses. It is found, first, that the water balance responses, including relative contributions of different runoff generation mechanisms, could be related to a small set of dimensionless similarity parameters. These capture the competition between the wetting, drying, storage, and drainage functions underlying the catchment responses, and in this way, provide a quantitative approximation of the conceptual Dunne diagram. Second, only a subset of all hypothetical catchment/climate combinations is found to be "behavioral," in terms of falling sufficiently close to the Budyko curve, describing mean annual runoff as a function of climate aridity. Furthermore, these behavioral combinations are mostly consistent with the qualitative picture presented in the Dunne diagram, indicating clearly the commonality between the Budyko curve and the Dunne diagram. These analyses also suggest clear interrelationships amongst the "behavioral" climate, soil, and topography parameter combinations, implying these catchment properties may be constrained to be codependent in order to satisfy the Budyko curve.

Simplified curve fits for the thermodynamic properties of equilibrium air

NASA Technical Reports Server (NTRS)

Srinivasan, S.; Tannehill, J. C.; Weilmuenster, K. J.

1986-01-01

New improved curve fits for the thermodynamic properties of equilibrium air were developed. The curve fits are for p = p(e,rho), a = a(e,rho), T = T(e,rho), s = s(e,rho), T = T(p,rho), h = h(p,rho), rho = rho(p,s), e = e(p,s) and a = a(p,s). These curve fits can be readily incorporated into new or existing Computational Fluid Dynamics (CFD) codes if real-gas effects are desired. The curve fits were constructed using Grabau-type transition functions to model the thermodynamic surfaces in a piecewise manner. The accuracies and continuity of these curve fits are substantially improved over those of previous curve fits appearing in NASA CR-2470. These improvements were due to the incorporation of a small number of additional terms in the approximating polynomials and careful choices of the transition functions. The ranges of validity of the new curve fits are temperatures up to 25,000 K and densities from 10 to the minus 7th to 100 amagats (rho/rho sub 0).

Toucan hand feeding and nestling growth.

PubMed

St Leger, Judy; Vince, Martin; Jennings, Jerry; McKerney, Erin; Nilson, Erika

2012-05-01

A retrospective analysis of hand-feeding records and growth data from 3 facilities was performed to determine the growth pattern for 8 toucan species raised in captivity. General philosophies of breeding and rearing were similar but approaches to hand-feeding varied. General hand-feeding and chick management records from hatch to fledging were reviewed for 2 of the 3 facilities. Effective hand-feeding formulas were commercially available and minimally modified. Growth curves were developed. Curves approximated typical expected patterns of nestling growth with no loss of weight at fledging. This study provides a basis for hand-feeding protocols and growth curves to assess development.

On measuring the scattering coefficient in a nondiffuse sound field

NASA Astrophysics Data System (ADS)

Kanev, N. G.

2017-11-01

The laws of sound decay in a cubic room, one wall of which is absorbing and the other scattering, are obtained. It is shown that under certain conditions, sound decay in a room occurs nonexponentially and the shape of the decay curve depends on the scattering coefficient of the walls. This makes it possible to suggest a method for measuring the scattering coefficient by the analysis the decay curve when the walls have sound-scattering materials and structures. Expressions are obtained for approximating the measured decay curve, and the boundaries of the method's applicability are determined.

Average Emissivity Curve of Batse Gamma-Ray Bursts with Different Intensities

NASA Technical Reports Server (NTRS)

Mitrofanov, Igor G.; Litvak, Maxim L.; Briggs, Michael S.; Paciesas, William S.; Pendleton, Geoffrey N.; Preece, Robert D.; Meegan, Charles A.

1999-01-01

Six intensity groups with approximately 150 BATSE gamma-ray bursts each are compared using average emissivity curves. Time stretch factors for each of the dimmer groups are estimated with respect to the brightest group, which serves as the reference, taking into account the systematics of counts-produced noise effects and choice statistics. A stretching/intensity anticorrelation is found with good statistical significance during the average back slopes of bursts. A stretch factor approximately 2 is found between the 150 dimmest bursts, with peak flux less than 0.45 photons/sq cm.s, and the 147 brightest bursts, with peak flux greater than 4.1 photons/sq cm.s. On the other hand, while a trend of increasing stretching factor may exist for rise fronts for bursts with decreasing peak flux from greater than 4.1 photons/sq cm.s down to 0.7 photons/sq cm.s, the magnitude of the stretching factor is less than approximately 1.4 and is therefore inconsistent with stretching factor of back slope.

Reformulation of the CBR Procedure, Report 2: Design, Construction, and Behavior Under Traffic of the Pavement Test Sections

DTIC Science & Technology

2013-12-01

shows the clay moisture- density curve. The design subgrade CBR values selected for the test section construction were 4%, 10%, and 15%. The high...9  Figure 7. Subgrade moisture- density curve...view of Hangar 4. (a) (b) The in situ soil was a lean clay (loess) deposit, and the depth to the groundwater table was approximately 6 ft

Lactation curve and milk quality of goats experimentally infected with Trypanosoma vivax.

PubMed

Lopes, Francisco Canindé; de Paiva, Kaliane Alessandra Rodrigues; Coelho, Wesley Adson Costa; Nunes, Francisco Vítor Aires; da Silva, Jardel Bezerra; de Gouveia Mendes da Escóssia Pinheiro, Carolina; de Macêdo Praça, Layanne; Silva, Jean Berg Alves; Alves Freitas, Carlos Iberê; Batista, Jael Soares

2016-08-01

The present study aimed to evaluate the effects of Trypanosoma vivax infection on the shape of the lactation curve and the milk quality of dairy goats experimentally infected with T. vivax. In total, twenty Saanen goats, aged 26-30 months and the same number of calving (two calvings), were divided into two experimental groups: an infected group, consisting of ten goats intravenously infected with 0.5 ml of blood containing approximately 1.25 × 10(5) trypomastigotes of T. vivax and ten uninfected animals as the control group. Clinical tests and hematocrit, parasitemia, and serum biochemistry evaluations were performed on all of the goats. Milk production was measured daily for 152 days by hand milking the goats and weighing the milk. Every seven days, physiochemical analyses were performed to evaluate the milk. Wood's nonlinear model was used to analyze the lactation curve parameters. The infected goats had high levels of parasitemia and hyperthermia, significantly reduced hematocrit, serum total protein, albumin, and glucose levels and increased cholesterol and urea concentrations. Wood's model indicated that the milk production of goats in the infected group declined sharply over a short period of time and produced a flattened yield curve and significant difference (P < 0.05) in the rate of increase of peak milk production, rate of decrease of milk production after the peak, day of peak milk production, and maximum peak milk production compared with that of the control group. Trypanosomiasis also affected the persistency of lactation, which was significantly reduced in goats in the infected group. In addition, the physico-chemical properties of the milk, including the fat content, defatted dry extracts (DDE) and protein content, decreased significantly (P < 0.05) in the goats in the infected group compared with those in the control group. The T. vivax-infected goats showed reduction in milk production, persistence of lactation, and fat levels, the defatted dry extract (DDE) content, and protein, changing the quality of milk. Copyright © 2016 Elsevier Inc. All rights reserved.

Deviations in expected price impact for small transaction volumes under fee restructuring

NASA Astrophysics Data System (ADS)

Harvey, M.; Hendricks, D.; Gebbie, T.; Wilcox, D.

2017-04-01

We report on the occurrence of an anomaly in the price impacts of small transaction volumes following a change in the fee structure of an electronic market. We first review evidence for the existence of a master curve for price impact on the Johannesburg Stock Exchange (JSE). On attempting to re-estimate a master curve after fee reductions, it is found that the price impact corresponding to smaller volume trades is greater than expected relative to prior estimates for a range of listed stocks. We show that a master curve for price impact can be found following rescaling by an appropriate liquidity proxy, providing a means for practitioners to approximate price impact curves without onerous processing of tick data.

Modeling the adiabatic connection in H2.

PubMed

Peach, Michael J G; Teale, Andrew M; Tozer, David J

2007-06-28

Full configuration interaction (FCI) data are used to quantify the accuracy of approximate adiabatic connection (AC) forms in describing the ground state potential energy curve of H2, within spin-restricted density functional theory (DFT). For each internuclear separation R, accurate properties of the AC are determined from large basis set FCI calculations. The parameters in the approximate AC form are then determined so as to reproduce these FCI values exactly, yielding an exchange-correlation energy expressed entirely in terms of FCI-derived quantities. This is combined with other FCI-derived energy components to give the total electronic energy; comparison with the FCI energy quantifies the accuracy of the AC form. Initial calculations focus on a [1/1]-Padé-based form. The potential energy curve determined using the procedure is a notable improvement over those from existing DFT functionals. The accuracy near equilibrium is quantified by calculating the bond length and vibrational wave numbers; errors in the latter are below 0.5%. The molecule dissociates correctly, which can be traced to the use of virtual orbital eigenvalues in the slope in the noninteracting limit, capturing static correlation. At intermediate R, the potential energy curve exhibits an unphysical barrier, similar to that noted previously using the random phase approximation. Alternative forms of the AC are also considered, paying attention to size extensivity and the behavior in the strong-interaction limit; none provide an accurate potential energy curve for all R, although good accuracy can be achieved near equilibrium. The study demonstrates how data from correlated ab initio calculations can provide valuable information about AC forms and highlight areas where further theoretical progress is required.

Magnetic-Field Density-Functional Theory (BDFT): Lessons from the Adiabatic Connection.

PubMed

Reimann, Sarah; Borgoo, Alex; Tellgren, Erik I; Teale, Andrew M; Helgaker, Trygve

2017-09-12

We study the effects of magnetic fields in the context of magnetic field density-functional theory (BDFT), where the energy is a functional of the electron density ρ and the magnetic field B. We show that this approach is a worthwhile alternative to current-density functional theory (CDFT) and may provide a viable route to the study of many magnetic phenomena using density-functional theory (DFT). The relationship between BDFT and CDFT is developed and clarified within the framework of the four-way correspondence of saddle functions and their convex and concave parents in convex analysis. By decomposing the energy into its Kohn-Sham components, we demonstrate that the magnetizability is mainly determined by those energy components that are related to the density. For existing density functional approximations, this implies that, for the magnetizability, improvements of the density will be more beneficial than introducing a magnetic-field dependence in the correlation functional. However, once a good charge density is achieved, we show that high accuracy is likely only obtainable by including magnetic-field dependence. We demonstrate that adiabatic-connection (AC) curves at different field strengths resemble one another closely provided each curve is calculated at the equilibrium geometry of that field strength. In contrast, if all AC curves are calculated at the equilibrium geometry of the field-free system, then the curves change strongly with increasing field strength due to the increasing importance of static correlation. This holds also for density functional approximations, for which we demonstrate that the main error encountered in the presence of a field is already present at zero field strength, indicating that density-functional approximations may be applied to systems in strong fields, without the need to treat additional static correlation.

Effects of lipopolysaccharide from Pseudomonas aeruginosa on airway smooth muscle functions in guinea pigs.

PubMed

Yamawaki, I; Tamaoki, J; Kanemura, T; Horii, S; Takizawa, T

1990-01-01

To elucidate the mechanisms of airway hyperreactivity induced by lipopolysaccharide (LPS), we studied isolated tracheal segments from guinea pigs under isometric conditions in vitro. Guinea pigs were injected intraperitoneally with endotoxin (1 mg/kg; LPS from Pseudomonas aeruginosa, serotype 10) for 4 days, and animals treated with sterile nonpyrogenic saline served as controls. Histological examination of trachea revealed moderate structural damage of epithelial layer in the LPS-treated group. Treatment with LPS potentiated the contractile responses of tracheal smooth muscle to acetylcholine, causing a leftward displacement of dose-response curves so that the EC50 values decreased from 1.1 +/- 3.7 x 10(-5) to 4.4 +/- 3.7 x 10(-7) M (mean +/- SE, p less than 0.01). Likewise, LPS shifted the dose-response curves for histamine and substance P to lower concentrations by approximately 0.5-1.0 log U. Each of these potentiations was not affected by pretreatment of tissues with indomethacin or propranolol. Addition of isoproterenol to tracheal segments precontracted with acetylcholine caused concentration-dependent relaxation, an effect that was significantly greater in controls than in the LPS-treated group. These results suggest that airway hyperreactivity induced by LPS in guinea pigs may be attributed to a decreased ability of respiratory epithelial cells to generate a relaxing factor.

Multiband Optical Follow-up Observations of GRB 020813 at the Kiso and Bisei Observatories

NASA Astrophysics Data System (ADS)

Urata, Y.; Nishiura, S.; Miyata, T.; Mito, H.; Kawabata, T.; Nakada, Y.; Aoki, T.; Soyano, T.; Tarusawa, K.; Yoshida, A.; Tamagawa, T.; Makishima, K.

2003-09-01

Observations were made of the optical afterglow of GRB 020813 (Fox, Blake, & Price) with the Kiso observatory 1.05 m Schmidt telescope and the Bisei astronomical observatory 1.01 m telescope. Four-band (B, V, R, and I) photometric data points were obtained on 2002 August 13 (10:52-16:46 UT), or 0.346-0.516 days after the burst. In order to investigate the early-time (<1 day) evolution of the afterglow, four-band light curves were produced by analyzing the data taken at these two astronomical observatories as well as the publicly released data taken using the Magellan Baade telescope (Gladders & Hall). The light curves can be approximated by a broken power law, of which the indices are approximately 0.46 and 1.33 before and after a break at ~0.2 days, respectively. The optical spectral index stayed approximately constant at ~0.9 over 0.17-4.07 days after the burst. Since the temporal decay index after the break and the spectral index measured at that time are both consistent with those predicted by a spherical expansion model, the early break is unlikely to be a jet break but is likely to represent the end of an early bump in the light curve, as was observed in the optical afterglow of GRB 021004.

Stability Investigation of a Blunted Cone and a Blunted Ogive with a Flared Cylinder Afterbody at Mach Numbers from 0.30 to 2.85

NASA Technical Reports Server (NTRS)

Coltrane, Lucille C.

1959-01-01

A cone with a blunt nose tip and a 10.7 deg cone half angle and an ogive with a blunt nose tip and a 20 deg flared cylinder afterbody have been tested in free flight over a Mach number range of 0.30 to 2.85 and a Reynolds number range of 1 x 10(exp 6) to 23 x 10(exp 6). Time histories, cross plots of force and moment coefficients, and plots of the longitudinal force,coefficient, rolling velocity, aerodynamic center, normal- force-curve slope, and dynamic stability are presented. With the center-of-gravity location at about 50 percent of the model length, the models were both statically and dynamically stable throughout the Mach number range. For the cone, the average aerodynamic center moved slightly forward with decreasing speeds and the normal-force-curve slope was fairly constant throughout the speed range. For the ogive, the average aerodynamic center remained practically constant and the normal-force-curve slope remained practically constant to a Mach number of approximately 1.6 where a rising trend is noted. Maximum drag coefficient for the cone, with reference to the base area, was approximately 0.6, and for the ogive, with reference to the area of the cylindrical portion, was approximately 2.1.

Photoluminescence Analysis of White-Light-Emitting Si Nanoparticles Using Effective Mass Approximation Method

NASA Astrophysics Data System (ADS)

Lee, Soojin; Cho, Woon Jo; Kim, Yang Do; Kim, Eun Kyu; Park, Jae Gwan

2005-07-01

White-light-emitting Si nanoparticles were prepared from the sodium silicide (NaSi) precursor. The photoluminescence of colloidal Si nanoparticles has been fitted by effective mass approximation (EMA). We analyzed the correlation between experimental photoluminescence and simulated fitting curves. Both the mean diameter and the size dispersion of the white-light-emitting Si nanoparticles were estimated.

Fast neutrons measured in copper from the Hiroshima atomic bomb dome.

PubMed

Marchetti, A A; McAninch, J E; Rugel, G; Rühm, W; Korschinek, G; Martinelli, R E; Faestermann, T; Knie, K; Egbert, S D; Wallner, A; Wallner, C; Tanaka, K; Endo, S; Hoshi, M; Shizuma, K; Fujita, S; Hasai, H; Imanaka, T; Straume, T

2009-01-01

The first measurements of (63)Ni produced by A-bomb fast neutrons (above approximately 1 MeV) in copper samples from Hiroshima encompassed distances from approximately 380 to 5062 m from the hypocenter (the point on the ground directly under the bomb). They included the region of interest to survivor studies (approximately 900 to 1500 m) and provided the first direct validation of fast neutrons in that range. However, a significant measurement gap remained between the hypocenter and 380 m. Measurements close to the hypocenter are important as a high-value anchor for the slope of the curve for neutron activation as a function of distance. Here we report measurements of (63)Ni in copper samples from the historic Hiroshima Atomic Bomb Dome, which is located approximately 150 m from the hypocenter. These measurements extend the range of our previously published data for (63)Ni providing a more comprehensive and consistent A-bomb activation curve. The results are also in good agreement with calculations based on the current dosimetry system (DS02) and give further experimental support to the accuracy of this system that forms the basis for radiation risk estimates worldwide.

An Approximate Solution and Master Curves for Buckling of Symmetrically Laminated Composite Cylinders

NASA Technical Reports Server (NTRS)

Nemeth, Michael P.

2013-01-01

Nondimensional linear-bifurcation buckling equations for balanced, symmetrically laminated cylinders with negligible shell-wall anisotropies and subjected to uniform axial compression loads are presented. These equations are solved exactly for the practical case of simply supported ends. Nondimensional quantities are used to characterize the buckling behavior that consist of a stiffness-weighted length-to-radius parameter, a stiffness-weighted shell-thinness parameter, a shell-wall nonhomogeneity parameter, two orthotropy parameters, and a nondimensional buckling load. Ranges for the nondimensional parameters are established that encompass a wide range of laminated-wall constructions and numerous generic plots of nondimensional buckling load versus a stiffness-weighted length-to-radius ratio are presented for various combinations of the other parameters. These plots are expected to include many practical cases of interest to designers. Additionally, these plots show how the parameter values affect the distribution and size of the festoons forming each response curve and how they affect the attenuation of each response curve to the corresponding solution for an infinitely long cylinder. To aid in preliminary design studies, approximate formulas for the nondimensional buckling load are derived, and validated against the corresponding exact solution, that give the attenuated buckling response of an infinitely long cylinder in terms of the nondimensional parameters presented herein. A relatively small number of "master curves" are identified that give a nondimensional measure of the buckling load of an infinitely long cylinder as a function of the orthotropy and wall inhomogeneity parameters. These curves reduce greatly the complexity of the design-variable space as compared to representations that use dimensional quantities as design variables. As a result of their inherent simplicity, these master curves are anticipated to be useful in the ongoing development of buckling-design technology.

CURV 3: Characteristics and mission applications

NASA Astrophysics Data System (ADS)

Perkins, W. W.; Brady, L. K.

1984-03-01

The Cable-Controlled Underwater Recovery Vehicle (CURV) program was begun by NOSC for the specific purpose of developing economical systems to recover test ordnance at NOSC's Long Beach and San Clemente Island test ranges. CURV 3 is the latest in this series of tethered, unmanned, remotely controlled vehicles and its present capabilities far exceed the original CURV 1. Originally conceived for use as a search and recovery vehicle, CURV has evolved into a versatile and easily adaptable multipurpose work vehicle capable of performing search and recovery tasks as well as pursuing test, evaluation, exploration, and work projects. Basically, CURV is a composite of integrated subsystems including such items as propulsion, search and navigation, optics, hydraulics, and tools. Because it is unmanned and does not require life support or other complex support systems, CURV is able to perform most undersea tasks more economically and efficiently than maned systems. Also, since it is powered and controlled from the surface, CURV has a continuous, unlimited operating capability. Under emergency conditions, the vehicle can operate to 10,000-foot depths. CURV can be easily transported to any spot in the world. Upon arrival of the vehicle, control van, cable, and support gear can be mounted on a suitable ship of opportunity.

Effect of type of concentrated sweet cream buttermilk on the manufacture, yield, and functionality of pizza cheese.

PubMed

Govindasamy-Lucey, S; Lin, T; Jaeggi, J J; Martinelli, C J; Johnson, M E; Lucey, J A

2007-06-01

Sweet cream buttermilk (SCB) is a rich source of phospholipids (PL). Most SCB is sold in a concentrated form. This study was conducted to determine if different concentration processes could affect the behavior of SCB as an ingredient in cheese. Sweet cream buttermilk was concentrated by 3 methods: cold ( < 7 degrees C) UF, cold reverse osmosis (RO), and evaporation (EVAP). A washed, stirred-curd pizza cheese was manufactured using the 3 different types of concentrated SCB as an ingredient in standardized milk. Cheesemilks of casein:fat ratio of 1.0 and final casein content approximately 2.7% were obtained by blending ultrafiltered (UF)-SCB retentate (19.9% solids), RO-SCB retentate (21.9% solids), or EVAP-SCB retentate (36.6% solids) with partially skimmed milk (11.2% solids) and cream (34.6% fat). Control milk (11.0% solids) was standardized by blending partially skimmed milk with cream. Cheese functionality was assessed using dynamic low-amplitude oscillatory rheology, UW Meltprofiler (degree of flow after heating to 60 degrees C), and performance of cheese on pizza. Initial trials with SCB-fortified cheeses resulted in approximately 4 to 5% higher moisture (51 to 52%) than control cheese (approximately 47%). In subsequent trials, procedures were altered to obtain similar moisture content in all cheeses. Fat recoveries were significantly lower in RO- and EVAP-SCB cheeses than in control or UF-SCB cheeses. Nitrogen recoveries were not significantly different but tended to be slightly lower in control cheeses than the various SCB cheeses. Total PL recovered in SCB cheeses ( approximately 32 to 36%) were lower than control ( approximately 41%), even though SCB is high in PL. From the rheology test, the loss tangent curves at temperatures > 40 degrees C increased as cheese aged up to a month and were significantly lower in SCB cheeses than the control, indicating lower meltability. Degree of flow in all the cheeses was similar regardless of the treatment used, and as cheese ripened, it increased for all cheeses. Trichloroacetic acid-soluble N levels were similar in the control and SCB-fortified cheese. On baked pizza, cheese made from milk fortified with UF-SCB tended to have the lowest amount of free oil, but flavor attributes of all cheeses were similar. Addition of concentrated SCB to standardize cheesemilk for pizza cheese did not adversely affect functional properties of cheese but increased cheese moisture without changes in manufacturing procedure.

Hunting stability analysis of high-speed train bogie under the frame lateral vibration active control

NASA Astrophysics Data System (ADS)

Yao, Yuan; Wu, Guosong; Sardahi, Yousef; Sun, Jian-Qiao

2018-02-01

In this paper, we study a multi-objective optimal design of three different frame vibration control configurations and compare their performances in improving the lateral stability of a high-speed train bogie. The existence of the time-delay in the control system and its impact on the bogie hunting stability are also investigated. The continuous time approximation method is used to approximate the time-delay system dynamics and then the root locus curves of the system before and after applying control are depicted. The analysis results show that the three control cases could improve the bogie hunting stability effectively. But the root locus of low- frequency hunting mode of bogie which determinates the system critical speed is different, thus affecting the system stability with the increasing of speed. Based on the stability analysis at different bogie dynamics parameters, the robustness of the control case (1) is the strongest. However, the case (2) is more suitable for the dynamic performance requirements of bogie. For the case (1), the time-delay over 10 ms may lead to instability of the control system which will affect the bogie hunting stability seriously. For the case (2) and (3), the increasing time-delay reduces the hunting stability gradually over the high-speed range. At a certain speed, such as 200 km/h, an appropriate time-delay is favourable to the bogie hunting stability. The mechanism is proposed according to the root locus analysis of time-delay system. At last, the nonlinear bifurcation characteristics of the bogie control system are studied by the numerical integration methods to verify the effects of these active control configurations and the delay on the bogie hunting stability.

Inelastic behavior of structural components

NASA Technical Reports Server (NTRS)

Hussain, N.; Khozeimeh, K.; Toridis, T. G.

1980-01-01

A more accurate procedure was developed for the determination of the inelastic behavior of structural components. The actual stress-strain curve for the mathematical of the structure was utilized to generate the force-deformation relationships for the structural elements, rather than using simplified models such as elastic-plastic, bilinear and trilinear approximations. relationships were generated for beam elements with various types of cross sections. In the generational of these curves, stress or load reversals, kinematic hardening and hysteretic behavior were taken into account. Intersections between loading and unloading branches were determined through an iterative process. Using the inelastic properties obtained, the plastic static response of some simple structural systems composed of beam elements was computed. Results were compared with known solutions, indicating a considerable improvement over response predictions obtained by means of simplified approximations used in previous investigations.

A cloud physics investigation utilizing Skylab data

NASA Technical Reports Server (NTRS)

Alishouse, J.; Jacobowitz, H.; Wark, D. (Principal Investigator)

1975-01-01

The author has identified the following significant results. The Lowtran 2 program, S191 spectral response, and solar spectrum were used to compute the expected absorption by 2.0 micron band for a variety of cloud pressure levels and solar zenith angles. Analysis of the three long wavelength data channels continued in which it was found necessary to impose a minimum radiance criterion. It was also found necessary to modify the computer program to permit the computation of mean values and standard deviations for selected subsets of data on a given tape. A technique for computing the integrated absorption in the A band was devised. The technique normalizes the relative maximum at approximately .78 micron to the solar irradiance curve and then adjusts the relative maximum at approximately .74 micron to fit the solar curve.

Designing of skull defect implants using C1 rational cubic Bezier and offset curves

NASA Astrophysics Data System (ADS)

Mohamed, Najihah; Majid, Ahmad Abd; Piah, Abd Rahni Mt; Rajion, Zainul Ahmad

2015-05-01

Some of the reasons to construct skull implant are due to head trauma after an accident or an injury or an infection or because of tumor invasion or when autogenous bone is not suitable for replacement after a decompressive craniectomy (DC). The main objective of our study is to develop a simple method to redesign missing parts of the skull. The procedure begins with segmentation, data approximation, and estimation process of the outer wall by a C1 continuous curve. Its offset curve is used to generate the inner wall. A metaheuristic algorithm, called harmony search (HS) is a derivative-free real parameter optimization algorithm inspired from the musical improvisation process of searching for a perfect state of harmony. In this study, data approximation by a rational cubic Bézier function uses HS to optimize position of middle points and value of the weights. All the phases contribute significantly in making our proposed technique automated. Graphical examples of several postoperative skulls are displayed to show the effectiveness of our proposed method.

Optical properties of randomly distributed soot: improved polarimetric and intensity scattering functions

NASA Astrophysics Data System (ADS)

Renard, Jean-Baptiste; Daugeron, Daniel; Personne, Pascal; Legros, Guillaume; Baillargeat, Jacques; Hadamcik, Edith; Worms, Jean-Claude

2005-02-01

Reference scattering curves for polarization and intensity produced by aggregates and agglomerates of ethylene and kerosene soot are obtained for scattering angles in the 10-170° range. The polarization measurements were obtained with the Propriétés Optiques des Grains Astronomiques et Atmosphèriques instrument for particles that levitate in microgravity during parabolic flights and on the ground by an air draught technique. The intensity measurements were obtained also on the ground with a Laboratoire de Metéorologie Physique nephelometer. The maximum polarization is of the order of 80% at a scattering angle of 80° at lambda = 632.8 nm and approximately 75% at an angle of 90° at lambda = 543.5 nm. The polarization increases by approximately 10% when the size of the agglomerate increases from 10 μm to a few hundred micrometers. The intensity curve exhibits a strong increase at small scattering angles. These reference curves will be used in the near future for the detection of stratospheric soot by remote-sensing measurement techniques.

Cholesterol Curves to Identify Population Norms by Age and Sex in Healthy Weight Children

PubMed Central

Skinner, Asheley Cockrell; Steiner, Michael J.; Chung, Arlene E.; Perrin, Eliana M.

2012-01-01

Objective Develop clinically applicable charts of lipid values illustrating fluctuations throughout childhood and by sex among healthy weight children. Methods The National Health and Nutrition Examination Survey (1999–2008) was used to estimate total cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL), and triglycerides by age and sex in healthy weight children age 3 to 17 years. Using LMS procedures, the authors created smoothed curves demonstrating population-based 50th percentile for age and the 75th and 95th percentiles. Results The curves were based on 7681 children meeting inclusion criteria. Total cholesterol, HDL, and LDL demonstrated peaks at approximately 8 to 12 years for boys. Similar peaks were evident for girls at slightly younger ages, approximately 7 to 11 years. Triglycerides showed peaks for girls, but values were similar across ages for boys. Conclusions The use of fixed lipid value cutoffs in established guidelines regardless of age or sex likely mislabels many children as abnormal. The authors’ charts may allow for a more nuanced interpretation based on population norms. PMID:22157422

Smooth time-dependent receiver operating characteristic curve estimators.

PubMed

Martínez-Camblor, Pablo; Pardo-Fernández, Juan Carlos

2018-03-01

The receiver operating characteristic curve is a popular graphical method often used to study the diagnostic capacity of continuous (bio)markers. When the considered outcome is a time-dependent variable, two main extensions have been proposed: the cumulative/dynamic receiver operating characteristic curve and the incident/dynamic receiver operating characteristic curve. In both cases, the main problem for developing appropriate estimators is the estimation of the joint distribution of the variables time-to-event and marker. As usual, different approximations lead to different estimators. In this article, the authors explore the use of a bivariate kernel density estimator which accounts for censored observations in the sample and produces smooth estimators of the time-dependent receiver operating characteristic curves. The performance of the resulting cumulative/dynamic and incident/dynamic receiver operating characteristic curves is studied by means of Monte Carlo simulations. Additionally, the influence of the choice of the required smoothing parameters is explored. Finally, two real-applications are considered. An R package is also provided as a complement to this article.

Microscopic processes controlling the Herschel-Bulkley exponent

NASA Astrophysics Data System (ADS)

Lin, Jie; Wyart, Matthieu

2018-01-01

The flow curve of various yield stress materials is singular as the strain rate vanishes and can be characterized by the so-called Herschel-Bulkley exponent n =1 /β . A mean-field approximation due to Hebraud and Lequeux (HL) assumes mechanical noise to be Gaussian and leads to β =2 in rather good agreement with observations. Here we prove that the improved mean-field model where the mechanical noise has fat tails instead leads to β =1 with logarithmic correction. This result supports that HL is not a suitable explanation for the value of β , which is instead significantly affected by finite-dimensional effects. From considerations on elastoplastic models and on the limitation of speed at which avalanches of plasticity can propagate, we argue that β =1 +1 /(d -df) , where df is the fractal dimension of avalanches and d the spatial dimension. Measurements of df then supports that β ≈2.1 and β ≈1.7 in two and three dimensions, respectively. We discuss theoretical arguments leading to approximations of β in finite dimensions.

Development and validation of an ultra-performance liquid chromatography quadrupole time of flight mass spectrometry method for rapid quantification of free amino acids in human urine.

PubMed

Joyce, Richard; Kuziene, Viktorija; Zou, Xin; Wang, Xueting; Pullen, Frank; Loo, Ruey Leng

2016-01-01

An ultra-performance liquid chromatography quadrupole time of flight mass spectrometry (UPLC-qTOF-MS) method using hydrophilic interaction liquid chromatography was developed and validated for simultaneous quantification of 18 free amino acids in urine with a total acquisition time including the column re-equilibration of less than 18 min per sample. This method involves simple sample preparation steps which consisted of 15 times dilution with acetonitrile to give a final composition of 25 % aqueous and 75 % acetonitrile without the need of any derivatization. The dynamic range for our calibration curve is approximately two orders of magnitude (120-fold from the lowest calibration curve point) with good linearity (r (2) ≥ 0.995 for all amino acids). Good separation of all amino acids as well as good intra- and inter-day accuracy (<15 %) and precision (<15 %) were observed using three quality control samples at a concentration of low, medium and high range of the calibration curve. The limits of detection (LOD) and lower limit of quantification of our method were ranging from approximately 1-300 nM and 0.01-0.5 µM, respectively. The stability of amino acids in the prepared urine samples was found to be stable for 72 h at 4 °C, after one freeze thaw cycle and for up to 4 weeks at -80 °C. We have applied this method to quantify the content of 18 free amino acids in 646 urine samples from a dietary intervention study. We were able to quantify all 18 free amino acids in these urine samples, if they were present at a level above the LOD. We found our method to be reproducible (accuracy and precision were typically <10 % for QCL, QCM and QCH) and the relatively high sample throughput nature of this method potentially makes it a suitable alternative for the analysis of urine samples in clinical setting.

Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film.

PubMed

Gotanda, Tatsuhiro; Katsuda, Toshizo; Gotanda, Rumi; Kuwano, Tadao; Akagawa, Takuya; Tanki, Nobuyoshi; Tabuchi, Akihiko; Shimono, Tetsunori; Kawaji, Yasuyuki

2016-01-01

Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were -32.336 and -33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range.

Simplified method for creating a density-absorbed dose calibration curve for the low dose range from Gafchromic EBT3 film

PubMed Central

Gotanda, Tatsuhiro; Katsuda, Toshizo; Gotanda, Rumi; Kuwano, Tadao; Akagawa, Takuya; Tanki, Nobuyoshi; Tabuchi, Akihiko; Shimono, Tetsunori; Kawaji, Yasuyuki

2016-01-01

Radiochromic film dosimeters have a disadvantage in comparison with an ionization chamber in that the dosimetry process is time-consuming for creating a density-absorbed dose calibration curve. The purpose of this study was the development of a simplified method of creating a density-absorbed dose calibration curve from radiochromic film within a short time. This simplified method was performed using Gafchromic EBT3 film with a low energy dependence and step-shaped Al filter. The simplified method was compared with the standard method. The density-absorbed dose calibration curves created using the simplified and standard methods exhibited approximately similar straight lines, and the gradients of the density-absorbed dose calibration curves were −32.336 and −33.746, respectively. The simplified method can obtain calibration curves within a much shorter time compared to the standard method. It is considered that the simplified method for EBT3 film offers a more time-efficient means of determining the density-absorbed dose calibration curve within a low absorbed dose range such as the diagnostic range. PMID:28144120

Numerical approach in defining milling force taking into account curved cutting-edge of applied mills

NASA Astrophysics Data System (ADS)

Bondarenko, I. R.

2018-03-01

The paper tackles the task of applying the numerical approach to determine the cutting forces of carbon steel machining with curved cutting edge mill. To solve the abovementioned task the curved surface of the cutting edge was subject to step approximation, and the chips section was split into discrete elements. As a result, the cutting force was defined as the sum of elementary forces observed during the cut of every element. Comparison and analysis of calculations with regard to the proposed method and the method with Kienzle dependence showed its sufficient accuracy, which makes it possible to apply the method in practice.

The NASA earth resources spectral information system: A data compilation, second supplement

NASA Technical Reports Server (NTRS)

Vincent, R. K.

1973-01-01

The NASA Earth Resources Spectral Information System (ERSIS) and the information contained therein are described. It is intended for use as a second supplement to the NASA Earth Resources Spectral Information System: A Data Compilation, NASA CR-31650-24-T, May 1971. The current supplement includes approximately 100 rock and mineral, and 375 vegetation directional reflectance spectral curves in the optical region from 0.2 to 22.0 microns. The data were categorized by subject and each curve plotted on a single graph. Each graph is fully titled to indicate curve source and indexed by subject to facilitate user retrieval from ERSIS magnetic tape records.

Electrorheological suspensions of laponite in oil: rheometry studies.

PubMed

Parmar, K P S; Méheust, Y; Schjelderupsen, Børge; Fossum, J O

2008-03-04

We have studied the effect of an external direct current (DC) electric field ( approximately 1 kV/mm) on the rheological properties of colloidal suspensions consisting of aggregates of laponite particles in a silicone oil. Microscopy observations show that, under application of an electric field greater than a triggering electric field Ec approximately 0.6 kV/mm, laponite aggregates assemble into chain- and/or columnlike structures in the oil. Without an applied electric field, the steady-state shear behavior of such suspensions is Newtonian-like. Under application of an electric field larger than Ec, it changes dramatically as a result of the changes in the microstructure: a significant yield stress is measured, and under continuous shear the fluid is shear-thinning. The rheological properties, in particular the dynamic and static shear stress, were studied as a function of particle volume fraction for various strengths (including null) of the applied electric field. The flow curves at constant shear rate can be scaled with respect to both the particle fraction and electric field strength onto a master curve. This scaling is consistent with simple scaling arguments. The shape of the master curve accounts for the system's complexity; it approaches a standard power-law model at high Mason numbers. Both dynamic and static yield stresses are observed to depend on the particle fraction Phi and electric field E as PhibetaEalpha, with alpha approximately 1.85 and beta approximately 1 and 1.70 for the dynamic and static yield stresses, respectively. The yield stress was also determined as the critical stress at which there occurs a bifurcation in the rheological behavior of suspensions that are submitted to a constant shear stress; a scaling law with alpha approximately 1.84 and beta approximately 1.70 was obtained. The effectiveness of the latter technique confirms that such electrorheological (ER) fluids can be studied in the framework of thixotropic fluids. The method is very reproducible; we suggest that it could be used routinely for studying ER fluids. The measured overall yield stress behavior of the suspensions may be explained in terms of standard conduction models for electrorheological systems. Interesting prospects include using such systems for guided self-assembly of clay nanoparticles.

Kinetic Characteristics of Hydrogen Transfer Through Palladium-Modified Membrane

NASA Astrophysics Data System (ADS)

Petriev, I. S.; Frolov, V. Yu.; Bolotin, S. N.; Baryshev, M. G.; Kopytov, G. F.

2018-01-01

The paper deals with hydrogen transfer through Pd-23%Ag alloy membrane, the surface of which is modified by the electrolytic deposition of highly dispersed palladium. The dependence between the density of hydrogen flow and its excess pressure on the input surface of membrane is well approximated by the first-order curve. This fact indicates that the process of hydrogen permeability is defined by its dissociation on the input surface. Activation energy of this process is 47.9 kJ/mol which considerably exceeds that of the process of hydrogen transfer through palladium (22-30 kJ/mol). This confirms the fact that the chemisorption is a rate-controlling step of the hydrogen transfer through membrane.

Enhanced secondary analysis of survival data: reconstructing the data from published Kaplan-Meier survival curves.

PubMed

Guyot, Patricia; Ades, A E; Ouwens, Mario J N M; Welton, Nicky J

2012-02-01

The results of Randomized Controlled Trials (RCTs) on time-to-event outcomes that are usually reported are median time to events and Cox Hazard Ratio. These do not constitute the sufficient statistics required for meta-analysis or cost-effectiveness analysis, and their use in secondary analyses requires strong assumptions that may not have been adequately tested. In order to enhance the quality of secondary data analyses, we propose a method which derives from the published Kaplan Meier survival curves a close approximation to the original individual patient time-to-event data from which they were generated. We develop an algorithm that maps from digitised curves back to KM data by finding numerical solutions to the inverted KM equations, using where available information on number of events and numbers at risk. The reproducibility and accuracy of survival probabilities, median survival times and hazard ratios based on reconstructed KM data was assessed by comparing published statistics (survival probabilities, medians and hazard ratios) with statistics based on repeated reconstructions by multiple observers. The validation exercise established there was no material systematic error and that there was a high degree of reproducibility for all statistics. Accuracy was excellent for survival probabilities and medians, for hazard ratios reasonable accuracy can only be obtained if at least numbers at risk or total number of events are reported. The algorithm is a reliable tool for meta-analysis and cost-effectiveness analyses of RCTs reporting time-to-event data. It is recommended that all RCTs should report information on numbers at risk and total number of events alongside KM curves.

Using the area under the curve to reduce measurement error in predicting young adult blood pressure from childhood measures.

PubMed

Cook, Nancy R; Rosner, Bernard A; Chen, Wei; Srinivasan, Sathanur R; Berenson, Gerald S

2004-11-30

Tracking correlations of blood pressure, particularly childhood measures, may be attenuated by within-person variability. Combining multiple measurements can reduce this error substantially. The area under the curve (AUC) computed from longitudinal growth curve models can be used to improve the prediction of young adult blood pressure from childhood measures. Quadratic random-effects models over unequally spaced repeated measures were used to compute the area under the curve separately within the age periods 5-14 and 20-34 years in the Bogalusa Heart Study. This method adjusts for the uneven age distribution and captures the underlying or average blood pressure, leading to improved estimates of correlation and risk prediction. Tracking correlations were computed by race and gender, and were approximately 0.6 for systolic, 0.5-0.6 for K4 diastolic, and 0.4-0.6 for K5 diastolic blood pressure. The AUC can also be used to regress young adult blood pressure on childhood blood pressure and childhood and young adult body mass index (BMI). In these data, while childhood blood pressure and young adult BMI were generally directly predictive of young adult blood pressure, childhood BMI was negatively correlated with young adult blood pressure when childhood blood pressure was in the model. In addition, racial differences in young adult blood pressure were reduced, but not eliminated, after controlling for childhood blood pressure, childhood BMI, and young adult BMI, suggesting that other genetic or lifestyle factors contribute to this difference. 2004 John Wiley & Sons, Ltd.

WORM - WINDOWED OBSERVATION OF RELATIVE MOTION

NASA Technical Reports Server (NTRS)

Bauer, F.

1994-01-01

The Windowed Observation of Relative Motion, WORM, program is primarily intended for the generation of simple X-Y plots from data created by other programs. It allows the user to label, zoom, and change the scale of various plots. Three dimensional contour and line plots are provided, although with more limited capabilities. The input data can be in binary or ASCII format, although all data must be in the same format. A great deal of control over the details of the plot is provided, such as gridding, size of tick marks, colors, log/semilog capability, time tagging, and multiple and phase plane plots. Many color and monochrome graphics terminals and hard copy printer/plotters are supported. The WORM executive commands, menu selections and macro files can be used to develop plots and tabular data, query the WORM Help library, retrieve data from input files, and invoke VAX DCL commands. WORM generated plots are displayed on local graphics terminals and can be copied using standard hard copy capabilities. Some of the graphics features of WORM include: zooming and dezooming various portions of the plot; plot documentation including curve labeling and function listing; multiple curves on the same plot; windowing of multiple plots and insets of the same plot; displaying a specific on a curve; and spinning the curve left, right, up, and down. WORM is written in PASCAL for interactive execution and has been implemented on a DEC VAX computer operating under VMS 4.7 with a virtual memory requirement of approximately 392K of 8 bit bytes. It uses the QPLOT device independent graphics library included with WORM. It was developed in 1988.

The effect of pavement markings on driving behaviour in curves: a simulator study.

PubMed

Ariën, Caroline; Brijs, Kris; Vanroelen, Giovanni; Ceulemans, Wesley; Jongen, Ellen M M; Daniels, Stijn; Brijs, Tom; Wets, Geert

2017-05-01

This study investigates the effect of two pavement markings (transverse rumble strips (TRS) and a backward pointing herringbone pattern (HP)) on speed and lateral control in and nearby curves. Two real-world curves with strong indications of a safety problem were replicated as realistic as possible in the simulator. Results show that both speed and lateral control differ between the curves. These behavioural differences are probably due to curve-related dissimilarities with respect to geometric alignment, cross-sectional design and speed limit. TRS and HP both influenced mean speed and mean acceleration/deceleration but not lateral control. TRS generated an earlier and more stable speed reduction than HP which induced significant speed reductions along the curve. The TRS gives drivers more time to generate the right expectations about the upcoming curve. When accidents occur primarily near the curve entry, TRS is recommended. The HP has the potential to reduce accidents at the curve end. Practitioner Summary: Two pavement markings (transversal rumble strips and HP) nearby dangerous curves were investigated in the driving simulator. TRS generated an earlier and more stable speed reduction than HP which induced speed reductions along the curve. The TRS gives drivers more time to generate right expectations about the upcoming curve.

SU-F-T-144: Analytical Closed Form Approximation for Carbon Ion Bragg Curves in Water

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

Tuomanen, S; Moskvin, V; Farr, J

2016-06-15

Purpose: Semi-empirical modeling is a powerful computational method in radiation dosimetry. A set of approximations exist for proton ion depth dose distribution (DDD) in water. However, the modeling is more complicated for carbon ions due to fragmentation. This study addresses this by providing and evaluating a new methodology for DDD modeling of carbon ions in water. Methods: The FLUKA, Monte Carlo (MC) general-purpose transport code was used for simulation of carbon DDDs for energies of 100–400 MeV in water as reference data model benchmarking. Based on Thomas Bortfeld’s closed form equation approximating proton Bragg Curves as a basis, we derivedmore » the critical constants for a beam of Carbon ions by applying models of radiation transport by Lee et. al. and Geiger to our simulated Carbon curves. We hypothesized that including a new exponential (κ) residual distance parameter to Bortfeld’s fluence reduction relation would improve DDD modeling for carbon ions. We are introducing an additional term to be added to Bortfeld’s equation to describe fragmentation tail. This term accounts for the pre-peak dose from nuclear fragments (NF). In the post peak region, the NF transport will be treated as new beams utilizing the Glauber model for interaction cross sections and the Abrasion- Ablation fragmentation model. Results: The carbon beam specific constants in the developed model were determined to be : p= 1.75, β=0.008 cm-1, γ=0.6, α=0.0007 cm MeV, σmono=0.08, and the new exponential parameter κ=0.55. This produced a close match for the plateau part of the curve (max deviation 6.37%). Conclusion: The derived semi-empirical model provides an accurate approximation of the MC simulated clinical carbon DDDs. This is the first direct semi-empirical simulation for the dosimetry of therapeutic carbon ions. The accurate modeling of the NF tail in the carbon DDD will provide key insight into distal edge dose deposition formation.« less

Compact Instruments Measure Helium-Leak Rates

NASA Technical Reports Server (NTRS)

Stout, Stephen; Immer, Christopher

2003-01-01

Compact, lightweight instruments have been developed for measuring small flows of helium and/or detecting helium leaks in solenoid valves when the valves are nominally closed. These instruments do not impede the flows when the valves are nominally open. They can be integrated into newly fabricated valves or retrofitted to previously fabricated valves. Each instrument includes an upstream and a downstream thermistor separated by a heater, plus associated analog and digital heater-control, signal- conditioning, and data-processing circuits. The thermistors and heater are off-the-shelf surface mount components mounted on a circuit board in the flow path. The operation of the instrument is based on a well-established thermal mass-flow-measurement technique: Convection by the flow that one seeks to measure gives rise to transfer of heat from the heater to the downstream thermistor. The temperature difference measured by the thermistors is directly related to the rate of flow. The calibration curve from temperature gradient to helium flow is closely approximated via fifth-order polynomial. A microprocessor that is part of the electronic circuitry implements the calibration curve to compute the flow rate from the thermistor readings.

Robust Spatial Approximation of Laser Scanner Point Clouds by Means of Free-form Curve Approaches in Deformation Analysis

NASA Astrophysics Data System (ADS)

Bureick, Johannes; Alkhatib, Hamza; Neumann, Ingo

2016-03-01

In many geodetic engineering applications it is necessary to solve the problem of describing a measured data point cloud, measured, e. g. by laser scanner, by means of free-form curves or surfaces, e. g., with B-Splines as basis functions. The state of the art approaches to determine B-Splines yields results which are seriously manipulated by the occurrence of data gaps and outliers. Optimal and robust B-Spline fitting depend, however, on optimal selection of the knot vector. Hence we combine in our approach Monte-Carlo methods and the location and curvature of the measured data in order to determine the knot vector of the B-Spline in such a way that no oscillating effects at the edges of data gaps occur. We introduce an optimized approach based on computed weights by means of resampling techniques. In order to minimize the effect of outliers, we apply robust M-estimators for the estimation of control points. The above mentioned approach will be applied to a multi-sensor system based on kinematic terrestrial laserscanning in the field of rail track inspection.

Meta-analysis of Diagnostic Accuracy and ROC Curves with Covariate Adjusted Semiparametric Mixtures.

PubMed

Doebler, Philipp; Holling, Heinz

2015-12-01

Many screening tests dichotomize a measurement to classify subjects. Typically a cut-off value is chosen in a way that allows identification of an acceptable number of cases relative to a reference procedure, but does not produce too many false positives at the same time. Thus for the same sample many pairs of sensitivities and false positive rates result as the cut-off is varied. The curve of these points is called the receiver operating characteristic (ROC) curve. One goal of diagnostic meta-analysis is to integrate ROC curves and arrive at a summary ROC (SROC) curve. Holling, Böhning, and Böhning (Psychometrika 77:106-126, 2012a) demonstrated that finite semiparametric mixtures can describe the heterogeneity in a sample of Lehmann ROC curves well; this approach leads to clusters of SROC curves of a particular shape. We extend this work with the help of the [Formula: see text] transformation, a flexible family of transformations for proportions. A collection of SROC curves is constructed that approximately contains the Lehmann family but in addition allows the modeling of shapes beyond the Lehmann ROC curves. We introduce two rationales for determining the shape from the data. Using the fact that each curve corresponds to a natural univariate measure of diagnostic accuracy, we show how covariate adjusted mixtures lead to a meta-regression on SROC curves. Three worked examples illustrate the method.

A Phase 2 Study of Continuous Subcutaneous Hydrocortisone Infusion in Adults With Congenital Adrenal Hyperplasia.

PubMed

Nella, Aikaterini A; Mallappa, Ashwini; Perritt, Ashley F; Gounden, Verena; Kumar, Parag; Sinaii, Ninet; Daley, Lori-Ann; Ling, Alexander; Liu, Chia-Ying; Soldin, Steven J; Merke, Deborah P

2016-12-01

Classic congenital adrenal hyperplasia (CAH) management remains challenging, given that supraphysiologic glucocorticoid doses are often needed to optimally suppress the ACTH-driven adrenal androgen overproduction. This study sought to approximate physiologic cortisol secretion via continuous subcutaneous hydrocortisone infusion (CSHI) and evaluate the safety and efficacy of CSHI in patients with difficult-to-treat CAH. Eight adult patients with classic CAH participated in a single-center open-label phase I-II study comparing CSHI to conventional oral glucocorticoid treatment. All patients had elevated adrenal steroids and one or more comorbidities at study entry. Assessment while receiving conventional therapy at baseline and 6 months following CSHI included: 24-hour hormonal sampling, metabolic and radiologic evaluation, health-related quality-of-life (HRQoL), and fatigue questionnaires. The ability of CSHI to approximate physiologic cortisol secretion and the percent of patients with 0700-hour 17-hydroxyprogesterone (17-OHP) ≤1200 ng/dL was measured. CSHI approximated physiologic cortisol secretion. Compared with baseline, 6 months of CSHI resulted in decreased 0700-hour and 24-hour area under the curve 17-OHP, androstenedione, ACTH, and progesterone, increased osteocalcin, c-telopeptide and lean mass, and improved HRQoL (and SF-36 Vitality Score), and fatigue. One of three amenorrheic women resumed menses. One man had reduction of testicular adrenal rest tissue. CSHI is a safe and well-tolerated modality of cortisol replacement that effectively approximates physiologic cortisol secretion in patients with classic CAH poorly controlled on conventional therapy. Improved adrenal steroid control and positive effects on HRQoL suggest that CSHI should be considered a treatment option for classic CAH. The long-term effect on established comorbidities requires further study.

A Phase 2 Study of Continuous Subcutaneous Hydrocortisone Infusion in Adults With Congenital Adrenal Hyperplasia

PubMed Central

Mallappa, Ashwini; Perritt, Ashley F.; Gounden, Verena; Kumar, Parag; Sinaii, Ninet; Daley, Lori-Ann; Ling, Alexander; Liu, Chia-Ying; Soldin, Steven J.; Merke, Deborah P.

2016-01-01

Context: Classic congenital adrenal hyperplasia (CAH) management remains challenging, given that supraphysiologic glucocorticoid doses are often needed to optimally suppress the ACTH-driven adrenal androgen overproduction. Objective: This study sought to approximate physiologic cortisol secretion via continuous subcutaneous hydrocortisone infusion (CSHI) and evaluate the safety and efficacy of CSHI in patients with difficult-to-treat CAH. Design: Eight adult patients with classic CAH participated in a single-center open-label phase I–II study comparing CSHI to conventional oral glucocorticoid treatment. All patients had elevated adrenal steroids and one or more comorbidities at study entry. Assessment while receiving conventional therapy at baseline and 6 months following CSHI included: 24-hour hormonal sampling, metabolic and radiologic evaluation, health-related quality-of-life (HRQoL), and fatigue questionnaires. Main Outcome Measures: The ability of CSHI to approximate physiologic cortisol secretion and the percent of patients with 0700-hour 17-hydroxyprogesterone (17-OHP) ≤1200 ng/dL was measured. Results: CSHI approximated physiologic cortisol secretion. Compared with baseline, 6 months of CSHI resulted in decreased 0700-hour and 24-hour area under the curve 17-OHP, androstenedione, ACTH, and progesterone, increased osteocalcin, c-telopeptide and lean mass, and improved HRQoL (and SF-36 Vitality Score), and fatigue. One of three amenorrheic women resumed menses. One man had reduction of testicular adrenal rest tissue. Conclusions: CSHI is a safe and well-tolerated modality of cortisol replacement that effectively approximates physiologic cortisol secretion in patients with classic CAH poorly controlled on conventional therapy. Improved adrenal steroid control and positive effects on HRQoL suggest that CSHI should be considered a treatment option for classic CAH. The long-term effect on established comorbidities requires further study. PMID:27680873

Distribution of curvature of 3D nonrotational surfaces approximating the corneal topography

NASA Astrophysics Data System (ADS)

Kasprzak, Henryk T.

1998-10-01

The first part of the paper presents the analytical curves used to approximate the corneal profile. Next, some definition of 3D surfaces curvature, like main normal sections, main radii of curvature and their orientations are given. The examples of four nonrotational 3D surfaces such as: ellipsoidal, surface based on hyperbolic cosine function, sphero-cylindrical and toroidal, approximating the corneal topography are proposed. The 3D surface and the contour plots of main radii of curvature and their orientation for four nonrotational approximation of the cornea are shown. Results of calculations are discussed from the point of view of videokeratometric images.

Design and development of LED-based irregular leather area measuring machine

NASA Astrophysics Data System (ADS)

Adil, Rehan; Khan, Sarah Jamal

2012-01-01

Using optical sensor array, a precision motion control system in a conveyer follows the irregular shaped leather sheet to measure its surface area. In operation, irregular shaped leather sheet passes on conveyer belt and optical sensor array detects the leather sheet edge. In this way outside curvature of the leather sheet is detected and is then feed to the controller to measure its approximate area. Such system can measure irregular shapes, by neglecting rounded corners, ellipses etc. To minimize the error in calculating surface area of irregular curve to the above mentioned system, the motion control system only requires the footprint of the optical sensor to be small and the distance between the sensors is to be minimized. In the proposed technique surface area measurement of irregular shaped leather sheet is done by defining velocity and detecting position of the move. The motion controller takes the information and creates the necessary edge profile on point-to-point bases. As a result irregular shape of leather sheet is mapped and is then feed to the controller to calculate surface area.

Précis of Breakdown of Will.

PubMed

Ainslie, George

2005-10-01

Behavioral science has long been puzzled by the experience of temptation, the resulting impulsiveness, and the variably successful control of this impulsiveness. In conventional theories, a governing faculty like the ego evaluates future choices consistently over time, discounting their value for delay exponentially, that is, by a constant rate; impulses arise when this ego is confronted by a conditioned appetite. Breakdown of Will (Ainslie 2001) presents evidence that contradicts this model. Both people and nonhuman animals spontaneously discount the value of expected events in a curve where value is divided approximately by expected delay, a hyperbolic form that is more bowed than the rational, exponential curve. With hyperbolic discounting, options that pay off quickly will be temporarily preferred to richer but slower-paying alternatives, a phenomenon that, over periods from minutes to days, can account for impulsive behaviors, and over periods of fractional seconds can account for involuntary behaviors. Contradictory reward-getting processes can in effect bargain with each other, and stable preferences can be established by the perception of recurrent choices as test cases (precedents) in recurrent intertemporal prisoner's dilemmas. The resulting motivational pattern resembles traditional descriptions of the will, as well as of compulsive phenomena that can now be seen as side-effects of will: over-concern with precedent, intractable but circumscribed failures of self-control, a motivated ("dynamic") unconscious, and an inability to exploit emotional rewards. Hyperbolic curves also suggest a means of reducing classical conditioning to motivated choice, the last necessary step for modeling many involuntary processes like emotion and appetite as reward-seeking behaviors; such modeling, in turn, provides a rationale for empathic reward and the "construction" of reality.

Response analysis of curved bridge with unseating failure control system under near-fault ground motions

NASA Astrophysics Data System (ADS)

Zuo, Ye; Sun, Guangjun; Li, Hongjing

2018-01-01

Under the action of near-fault ground motions, curved bridges are prone to pounding, local damage of bridge components and even unseating. A multi-scale fine finite element model of a typical three-span curved bridge is established by considering the elastic-plastic behavior of piers and pounding effect of adjacent girders. The nonlinear time-history method is used to study the seismic response of the curved bridge equipped with unseating failure control system under the action of near-fault ground motion. An in-depth analysis is carried to evaluate the control effect of the proposed unseating failure control system. The research results indicate that under the near-fault ground motion, the seismic response of the curved bridge is strong. The unseating failure control system perform effectively to reduce the pounding force of the adjacent girders and the probability of deck unseating.

Temporal distribution of rainfall in Virginia : final report.

DOT National Transportation Integrated Search

1984-01-01

The temporal distribution of Virginia rainstorms was examined by statistically analyzing approximately 1,400 storm events recorded throughout the state. Rainfall time distribution curves were constructed and were compared with several nationally reco...

A Multi-Resolution Nonlinear Mapping Technique for Design and Analysis Applications

NASA Technical Reports Server (NTRS)

Phan, Minh Q.

1998-01-01

This report describes a nonlinear mapping technique where the unknown static or dynamic system is approximated by a sum of dimensionally increasing functions (one-dimensional curves, two-dimensional surfaces, etc.). These lower dimensional functions are synthesized from a set of multi-resolution basis functions, where the resolutions specify the level of details at which the nonlinear system is approximated. The basis functions also cause the parameter estimation step to become linear. This feature is taken advantage of to derive a systematic procedure to determine and eliminate basis functions that are less significant for the particular system under identification. The number of unknown parameters that must be estimated is thus reduced and compact models obtained. The lower dimensional functions (identified curves and surfaces) permit a kind of "visualization" into the complexity of the nonlinearity itself.

A Multi-Resolution Nonlinear Mapping Technique for Design and Analysis Application

NASA Technical Reports Server (NTRS)

Phan, Minh Q.

1997-01-01

This report describes a nonlinear mapping technique where the unknown static or dynamic system is approximated by a sum of dimensionally increasing functions (one-dimensional curves, two-dimensional surfaces, etc.). These lower dimensional functions are synthesized from a set of multi-resolution basis functions, where the resolutions specify the level of details at which the nonlinear system is approximated. The basis functions also cause the parameter estimation step to become linear. This feature is taken advantage of to derive a systematic procedure to determine and eliminate basis functions that are less significant for the particular system under identification. The number of unknown parameters that must be estimated is thus reduced and compact models obtained. The lower dimensional functions (identified curves and surfaces) permit a kind of "visualization" into the complexity of the nonlinearity itself.

Boundary element analysis of corrosion problems for pumps and pipes

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

Miyasaka, M.; Amaya, K.; Kishimoto, K.

1995-12-31

Three-dimensional (3D) and axi-symmetric boundary element methods (BEM) were developed to quantitatively estimate cathodic protection and macro-cell corrosion. For 3D analysis, a multiple-region method (MRM) was developed in addition to a single-region method (SRM). The validity and usefulness of the BEMs were demonstrated by comparing numerical results with experimental data from galvanic corrosion systems of a cylindrical model and a seawater pipe, and from a cathodic protection system of an actual seawater pump. It was shown that a highly accurate analysis could be performed for fluid machines handling seawater with complex 3D fields (e.g. seawater pump) by taking account ofmore » flow rate and time dependencies of polarization curve. Compared to the 3D BEM, the axi-symmetric BEM permitted large reductions in numbers of elements and nodes, which greatly simplified analysis of axi-symmetric fields such as pipes. Computational accuracy and CPU time were compared between analyses using two approximation methods for polarization curves: a logarithmic-approximation method and a linear-approximation method.« less

Breakdown of the single-exchange approximation in third-order symmetry-adapted perturbation theory.

PubMed

Lao, Ka Un; Herbert, John M

2012-03-22

We report third-order symmetry-adapted perturbation theory (SAPT) calculations for several dimers whose intermolecular interactions are dominated by induction. We demonstrate that the single-exchange approximation (SEA) employed to derive the third-order exchange-induction correction (E(exch-ind)((30))) fails to quench the attractive nature of the third-order induction (E(ind)((30))), leading to one-dimensional potential curves that become attractive rather than repulsive at short intermolecular separations. A scaling equation for (E(exch-ind)((30))), based on an exact formula for the first-order exchange correction, is introduced to approximate exchange effects beyond the SEA, and qualitatively correct potential energy curves that include third-order induction are thereby obtained. For induction-dominated systems, our results indicate that a "hybrid" SAPT approach, in which a dimer Hartree-Fock calculation is performed in order to obtain a correction for higher-order induction, is necessary not only to obtain quantitative binding energies but also to obtain qualitatively correct potential energy surfaces. These results underscore the need to develop higher-order exchange-induction formulas that go beyond the SEA. © 2012 American Chemical Society

Closed loop engine control for regulating NOx emissions, using a two-dimensional fuel-air curve

DOEpatents

Bourn, Gary D.; Smith, Jack A.; Gingrich, Jess W.

2007-01-30

An engine control strategy that ensures that NOx emissions from the engine will be maintained at an acceptable level. The control strategy is based on a two-dimensional fuel-air curve, in which air manifold pressure (AMP) is a function of fuel header pressure and engine speed. The control strategy provides for closed loop NOx adjustment to a base AMP value derived from the fuel-air curve.

Efficiency of herbal medicine Dai-kenchu-to on portal blood flow in rat models.

PubMed

Muraoka, Izumi; Takatsuki, Mitsuhisa; Soyama, Akihiko; Yamaguchi, Izumi; Tanaka, Shiro; Tanaka, Takayuki; Kinoshita, Ayaka; Hara, Takanobu; Kuroki, Tamotsu; Eguchi, Susumu

2015-09-01

To clarify the influence of Dai-Kenchu-To (DKT) on portal blood flow (PBF), PBF was continuously measured with Doppler ultrasound. Normal liver rats were divided into a DKT 90 mg/kg, DKT 270 mg/kg administered group, and control, while cirrhotic liver rats were divided into a DKT-LC 90 mg/kg administered group and Control-LC. The PBF was measured after the administration of either DKT or water for 60 min by laser Doppler flowmetry system. The PBF in the DKT 90 increased approximately 10 min after DKT was administrated, and elevated levels were maintained for approximately 10 min. A comparison of the increase in PBF by the calculating the area under the curve (AUC) revealed that flow was significantly higher in the DKT 90 compared to either the control or the DKT 270 (p < 0.05). The cirrhotic liver group showed stable PBF in both the DKT-LC and Control-LC. The AUC, revealed no significant difference between the DKT-LC and Control-LC. DKT induced an increase in PBF in normal livers; however, its effects were insufficient to increase PBF in the cirrhotic livers. No increase in the portal blood flow in the cirrhotic liver rats was probably the result of the cirrhotic liver, which had fibrotic change, and, therefore, may not have had sufficient compliance to accept the increasing blood flow volume from the intestinal tract. We suggested DKT has the potential to protect the liver by increasing PBF when the liver has either normal or mild to moderate dysfunction.

Longitudinal Stability Characteristics of the Consolidated Vultee XFY-1 Airplane with Windmilling Propellers as Obtained from Flight of 0.133-Scale Rocket-Propelled Model at Mach Numbers from 0.70 to 1.13

NASA Technical Reports Server (NTRS)

Hastings, Earl C.; Mitcham, Grady L.

1954-01-01

A flight test has been conducted to determine the longitudinal stability and control characteristics of a 0.133-scale model of the Consolidated Vultee XFY-1 airplane with windmilling propellers for the Mach number range between 0.70 and 1.13. The variation of lift-curve slope C(sub L(sub alpha) with Mach number was gradual with a maximum value of 0.074 occurring at a Mach number of 0.97. Propellers had little effect upon the values of lift-curve slope or the linearity of lift coefficient with angle of attack. At lift coefficients between approximately 0.25 and 0.45 with an elevon angle of approximately -l0 deg, there was a region of neutral longitudinal stability at Mach numbers below 0.93 introduced by the addition of windmilling propellers. Below a lift coefficient of 0.10 and above a lift coefficient of 0.45, the model was longitudinally stable throughout the Mach number range of the test. There was a forward shift in the aerodynamic center of about 3-percent mean aerodynamic chord introduced by the addition of propellers. The aerodynamic center as determined at low lift moved gradually from a value of 28.5-percent mean aerodynamic chord at a Mach number of 0.75 to a value of 47-percent mean aerodynamic chord at a Mach number of 1.10. There was an abrupt decrease in pitch damping between Mach numbers of 0.88 and 0.99 followed by a rapid increase in damping to a Mach number of 1.06. The propellers had little effect upon the pitch damping characteristics . The transonic trim change was a large pitching-down tendency with and without windmilling propellers. The elevons were effective pitch controls throughout the speed range; however, their effectiveness was reduced about 50 percent at supersonic speeds. The propellers had no appreciable effect upon the control effectiveness.

Insect-like flapping wing mechanism based on a double spherical Scotch yoke.

PubMed

Galiński, Cezary; Zbikowski, Rafał

2005-06-22

We describe the rationale, concept, design and implementation of a fixed-motion (non-adjustable) mechanism for insect-like flapping wing micro air vehicles in hover, inspired by two-winged flies (Diptera). This spatial (as opposed to planar) mechanism is based on the novel idea of a double spherical Scotch yoke. The mechanism was constructed for two main purposes: (i) as a test bed for aeromechanical research on hover in flapping flight, and (ii) as a precursor design for a future flapping wing micro air vehicle. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forwards and backwards. During this motion the wing tip approximately traces a "figure-of-eight" or a "banana" and the wing changes the angle of attack (pitching) significantly. The kinematic and aerodynamic data from free-flying insects are sparse and uncertain, and it is not clear what aerodynamic consequences different wing motions have. Since acquiring the necessary kinematic and dynamic data from biological experiments remains a challenge, a synthetic, controlled study of insect-like flapping is not only of engineering value, but also of biological relevance. Micro air vehicles are defined as flying vehicles approximately 150 mm in size (hand-held), weighing 50-100g, and are developed to reconnoitre in confined spaces (inside buildings, tunnels, etc.). For this application, insect-like flapping wings are an attractive solution and hence the need to realize the functionality of insect flight by engineering means. Since the semi-span of the insect wing is constant, the kinematics are spatial; in fact, an approximate figure-of-eight/banana is traced on a sphere. Hence a natural mechanism implementing such kinematics should be (i) spherical and (ii) generate mathematically convenient curves expressing the figure-of-eight/banana shape. The double spherical Scotch yoke design has property (i) by definition and achieves (ii) by tracing spherical Lissajous curves.

Insect-like flapping wing mechanism based on a double spherical Scotch yoke

PubMed Central

Galiński, Cezary; Żbikowski, Rafał

2005-01-01

We describe the rationale, concept, design and implementation of a fixed-motion (non-adjustable) mechanism for insect-like flapping wing micro air vehicles in hover, inspired by two-winged flies (Diptera). This spatial (as opposed to planar) mechanism is based on the novel idea of a double spherical Scotch yoke. The mechanism was constructed for two main purposes: (i) as a test bed for aeromechanical research on hover in flapping flight, and (ii) as a precursor design for a future flapping wing micro air vehicle. Insects fly by oscillating (plunging) and rotating (pitching) their wings through large angles, while sweeping them forwards and backwards. During this motion the wing tip approximately traces a ‘figure-of-eight’ or a ‘banana’ and the wing changes the angle of attack (pitching) significantly. The kinematic and aerodynamic data from free-flying insects are sparse and uncertain, and it is not clear what aerodynamic consequences different wing motions have. Since acquiring the necessary kinematic and dynamic data from biological experiments remains a challenge, a synthetic, controlled study of insect-like flapping is not only of engineering value, but also of biological relevance. Micro air vehicles are defined as flying vehicles approximately 150 mm in size (hand-held), weighing 50–100 g, and are developed to reconnoitre in confined spaces (inside buildings, tunnels, etc.). For this application, insect-like flapping wings are an attractive solution and hence the need to realize the functionality of insect flight by engineering means. Since the semi-span of the insect wing is constant, the kinematics are spatial; in fact, an approximate figure-of-eight/banana is traced on a sphere. Hence a natural mechanism implementing such kinematics should be (i) spherical and (ii) generate mathematically convenient curves expressing the figure-of-eight/banana shape. The double spherical Scotch yoke design has property (i) by definition and achieves (ii) by tracing spherical Lissajous curves. PMID:16849181

Detection of KIT Genotype in Pigs by TaqMan MGB Real-Time Quantitative Polymerase Chain Reaction.

PubMed

Li, Xiuxiu; Li, Xiaoning; Luo, Rongrong; Wang, Wenwen; Wang, Tao; Tang, Hui

2018-05-01

The dominant white phenotype in domestic pigs is caused by two mutations in the KIT gene: a 450 kb duplication containing the entire KIT gene together with flanking sequences and one splice mutation with a G:A substitution in intron 17. The purpose of this study was to establish a simple, rapid method to determine KIT genotype in pigs. First, to detect KIT copy number variation (CNV), primers for exon 2 of the KIT gene, along with a TaqMan minor groove binder (MGB) probe, were designed. The single-copy gene, estrogen receptor (ESR), was used as an internal control. A real-time fluorescence-based quantitative PCR (FQ-PCR) protocol was developed to accurately detect KIT CNVs. Second, to detect the splice mutation ratio of the G:A substitution in intron 17, a 175 bp region, including the target mutation, was amplified from genomic DNA. Based on the sequence of the resulting amplified fragment, an MGB probe set was designed to detect the ratio of splice mutation to normal using FQ-PCR. A series of parallel amplification curves with the same internal distances were obtained using gradually diluted DNA as templates. The CT values among dilutions were significantly different (p < 0.001) and the coefficients of variation from each dilution were low (from 0.13% to 0.26%). The amplification efficiencies for KIT and ESR were approximately equal, indicating ESR was an appropriate control gene. Furthermore, use of the MGB probe set resulted in detection of the target mutation at a high resolution and stability; standard curves illustrated that the amplification efficiencies of KIT1 (G) and KIT2 (A) were approximately equal (98.8% and 97.2%). In conclusion, a simple, rapid method, with high specificity and stability, for the detection of the KIT genotype in pigs was established using TaqMan MGB probe real-time quantitative PCR.

An Analysis of the Time Course of Lexical Processing During Reading

PubMed Central

Sheridan, Heather; Reichle, Erik D.

2016-01-01

Reingold, Reichle, Glaholt, and Sheridan (2012) reported a gaze-contingent eye-movement experiment in which survival-curve analyses were used to examine the effects of word frequency, the availability of parafoveal preview, and initial fixation location on the time course of lexical processing. The key results of these analyses suggest that lexical processing begins very rapidly (after approximately 120 ms), and is supported by substantial parafoveal processing (more than 100 ms). Because it is not immediately obvious that these results are congruent with the theoretical assumption that words are processed and identified in a strictly serial manner, we attempted to simulate the experiment using the E-Z Reader model of eye-movement control (Reichle, 2011). These simulations were largely consistent with the empirical results, suggesting that parafoveal processing does play an important functional role by allowing lexical processing to occur rapidly enough to mediate direct control over when the eyes move during reading. PMID:25939443

The Nasa earth resources spectral information system: A data compilation, first supplement

NASA Technical Reports Server (NTRS)

Leeman, V.

1972-01-01

The NASA Earth Resources Spectral Information System and the information contained therein are described. It is intended to be used as a supplement to the NASA Earth Resources Spectral Information System: A Data Compilation, N72-28366. This supplement includes approximately 500 rock and mineral, 100 soil, and 30 vegetation bidirectional and directional reflectance, transmittance, emittance, and degree-of-polarization curves in the optical region from 0.2 to 22.0 microns. The data have been categorized by subject and each curve plotted on a single graph. For some rocks and minerals, all curves of the same type, differing only in particle size, have been plotted on one grid as a composite plot. Each graph, composite or single, is fully titled to indicate curve source and is indexed by subject to facilitate user retrieval.

Preventing conflicts among bid curves used with transactive controllers in a market-based resource allocation system

DOEpatents

Fuller, Jason C.; Chassin, David P.; Pratt, Robert G.; Hauer, Matthew; Tuffner, Francis K.

2017-03-07

Disclosed herein are representative embodiments of methods, apparatus, and systems for distributing a resource (such as electricity) using a resource allocation system. One of the disclosed embodiments is a method for operating a transactive thermostatic controller configured to submit bids to a market-based resource allocation system. According to the exemplary method, a first bid curve is determined, the first bid curve indicating a first set of bid prices for corresponding temperatures and being associated with a cooling mode of operation for a heating and cooling system. A second bid curve is also determined, the second bid curve indicating a second set of bid prices for corresponding temperatures and being associated with a heating mode of operation for a heating and cooling system. In this embodiment, the first bid curve, the second bid curve, or both the first bid curve and the second bid curve are modified to prevent overlap of any portion of the first bid curve and the second bid curve.

An extended CFD model to predict the pumping curve in low pressure plasma etch chamber

NASA Astrophysics Data System (ADS)

Zhou, Ning; Wu, Yuanhao; Han, Wenbin; Pan, Shaowu

2014-12-01

Continuum based CFD model is extended with slip wall approximation and rarefaction effect on viscosity, in an attempt to predict the pumping flow characteristics in low pressure plasma etch chambers. The flow regime inside the chamber ranges from slip wall (Kn ˜ 0.01), and up to free molecular (Kn = 10). Momentum accommodation coefficient and parameters for Kn-modified viscosity are first calibrated against one set of measured pumping curve. Then the validity of this calibrated CFD models are demonstrated in comparison with additional pumping curves measured in chambers of different geometry configurations. More detailed comparison against DSMC model for flow conductance over slits with contraction and expansion sections is also discussed.

Modification of Einstein A Coefficient in Dissipative Gas Medium

NASA Technical Reports Server (NTRS)

Cao, Chang-Qi; Cao, Hui; Qin, Ke-Cheng

1996-01-01

Spontaneous radiation in dissipative gas medium such as plasmas is investigated by Langevin equations and the modified Weisskopf-Wigner approximation. Since the refractive index of gas medium is expected to be nearly unity, we shall first neglect the medium polarization effect. We show that absorption in plasmas may in certain case modify the Einstein A coefficient significantly and cause a pit in the A coefficient-density curves for relatively low temperature plasmas and also a pit in the A coefficient-temperature curves. In the next, the effect of medium polarization is taken into account in addition. To our surprise, its effect in certain case is quite significant. The dispersive curves show different behaviors in different region of parameters.

Active motion on curved surfaces

NASA Astrophysics Data System (ADS)

Castro-Villarreal, Pavel; Sevilla, Francisco J.

2018-05-01

A theoretical analysis of active motion on curved surfaces is presented in terms of a generalization of the telegrapher equation. Such a generalized equation is explicitly derived as the polar approximation of the hierarchy of equations obtained from the corresponding Fokker-Planck equation of active particles diffusing on curved surfaces. The general solution to the generalized telegrapher equation is given for a pulse with vanishing current as initial data. Expressions for the probability density and the mean squared geodesic displacement are given in the limit of weak curvature. As an explicit example of the formulated theory, the case of active motion on the sphere is presented, where oscillations observed in the mean squared geodesic displacement are explained.

Molecular dynamics study of the melting curve of NiTi alloy under pressure

NASA Astrophysics Data System (ADS)

Zeng, Zhao-Yi; Hu, Cui-E.; Cai, Ling-Cang; Chen, Xiang-Rong; Jing, Fu-Qian

2011-02-01

The melting curve of NiTi alloy was predicted by using molecular dynamics simulations combining with the embedded atom model potential. The calculated thermal equation of state consists well with our previous results obtained from quasiharmonic Debye approximation. Fitting the well-known Simon form to our Tm data yields the melting curves for NiTi: 1850(1 + P/21.938)0.328 (for one-phase method) and 1575(1 + P/7.476)0.305 (for two-phase method). The two-phase simulations can effectively eliminate the superheating in one-phase simulations. At 1 bar, the melting temperature of NiTi is 1575 ± 25 K and the corresponding melting slope is 64 K/GPa.

Entropy and caloric curve for mononuclei considering both surface diffuseness and self-similar expansion degrees of freedom

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

Sobotka, L.G.; Department of Physics, Washington University, St. Louis, Missouri 63130; Charity, R.J.

2006-01-15

The caloric curve for mononuclear configurations is studied with a model that allows for both increased surface diffusness and self-similar expansion. The evolution of the effective mass with density and excitation is included in a schematic fashion. The entropies, extracted in a local-density approximation, confirm that nuclei posess a soft mode that is predominately a surface expansion. We also find that the mononuclear caloric curve (temperature versus excitation energy) exhibits a plateau. Thus a plateau should be the expectation with or without a multifragmentationlike phase transition. This conclusion is relevant only for reactions that populate the mononuclear region of phasemore » space.« less

SPIDERMAN: Fast code to simulate secondary transits and phase curves

NASA Astrophysics Data System (ADS)

Louden, Tom; Kreidberg, Laura

2017-11-01

SPIDERMAN calculates exoplanet phase curves and secondary eclipses with arbitrary surface brightness distributions in two dimensions. The code uses a geometrical algorithm to solve exactly the area of sections of the disc of the planet that are occulted by the star. Approximately 1000 models can be generated per second in typical use, which makes making Markov Chain Monte Carlo analyses practicable. The code is modular and allows comparison of the effect of multiple different brightness distributions for a dataset.

12. CONCRETE LINING ON A CURVING SEGMENT OF THE LATERAL ...

Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

12. CONCRETE LINING ON A CURVING SEGMENT OF THE LATERAL NEAR THE NORTHEAST END OF LAKE LADORA (SECTION 2). - Highline Canal, Sand Creek Lateral, Beginning at intersection of Peoria Street & Highline Canal in Arapahoe County (City of Aurora), Sand Creek lateral Extends 15 miles Northerly through Araphoe County, City & County of Denver, & Adams County to its end point, approximately 1/4 mile Southest of intersectioin of D Street & Ninth Avenue in Adams County (Rocky Mountain Arsenal, Commerce City Vicinity), Commerce City, Adams County, CO

Photometric behavior and general characteristics of the nova HR Delphini

NASA Astrophysics Data System (ADS)

Raikova, D.

The light curve and the B-V color-index curve of HR Del were constructed on the basis of published UBV observations. From the normal color indices, the effective photosphere temperature and radius were determined using calibrations for normal stars. As the brightness reached its peak, the effective photosphere was expanding with a velocity of approximately 23 km/s, which is more than 10 times less than the gas velocity. This phenomenon is explained by decreasing continuous opacity as the ejected gas expands.

J-Resistance Curves of Aluminum Specimens Using Moire Interferometry

DTIC Science & Technology

1989-04-01

elastic-plastic fracture mechanics ( EPFM ) methodologies are based on the J-integral or the crack opening displacement (COD) approach. The J-resistance curve...in the HRR field [13,141. In this paper, we present further application of the approximate J-evaluation procedure in large 2024-0 and 5052-H32 aluminum...Davis, J. A. Joyce, and R. A. Hays, " Application of the J-Integral and the Modified J-Integral to Cases of Large Crack Extension and High Toughness

Development of Genuine Neural Network Prototype Chip

DTIC Science & Technology

1991-01-28

priori distribution is equivalent, and more readily visualized with a rank curve . The sonar signal data consisted of approximately 85% class Target and...15% class Clutter. For this reason, the rank curves for the class Clutter were used for device parameter analysis. R & D STATUS REPORT 1/28/91 N00014...the signal CLASSLD#. Four 10-bit class probabilities are available on the output bus (C0-C9, C16-C25, C32-C41 and C48- C57 ) at each clock cycle. A

Identifying traction-separation behavior of self-adhesive polymeric films from in situ digital images under T-peeling

NASA Astrophysics Data System (ADS)

Nase, Michael; Rennert, Mirko; Naumenko, Konstantin; Eremeyev, Victor A.

2016-06-01

In this paper procedures are developed to identify traction-separation curves from digital images of the deformed flexible films during peeling. T-peel tests were performed for self-adhesive polymeric films. High quality photographs of the deformed shape within and outside the zone of adhesive interaction were made in situ by the digital light microscope. The deformed line is approximated by a power series with coefficients computed by minimizing a least squares functional. Two approaches to identify the traction-separation curve for the given deformation line are proposed. The first one is based on the energy integral of the non-linear theory of rods and allows the direct evaluation of the adhesion force potential. The second one utilizes the complementary energy type variational equation and the Ritz method to compute the adhesion force. The accuracy of both approaches is analyzed with respect to different approximations for the deformed line and the force of interaction. The obtained traction vs. axial coordinate and the traction-separation curves provide several properties of the adhesive system including the maximum adhesion force, the length of the adhesive zone and the equilibrium position, where the adhesive force is zero while the separation is positive.

Choice of no-slip curved boundary condition for lattice Boltzmann simulations of high-Reynolds-number flows.

PubMed

Sanjeevi, Sathish K P; Zarghami, Ahad; Padding, Johan T

2018-04-01

Various curved no-slip boundary conditions available in literature improve the accuracy of lattice Boltzmann simulations compared to the traditional staircase approximation of curved geometries. Usually, the required unknown distribution functions emerging from the solid nodes are computed based on the known distribution functions using interpolation or extrapolation schemes. On using such curved boundary schemes, there will be mass loss or gain at each time step during the simulations, especially apparent at high Reynolds numbers, which is called mass leakage. Such an issue becomes severe in periodic flows, where the mass leakage accumulation would affect the computed flow fields over time. In this paper, we examine mass leakage of the most well-known curved boundary treatments for high-Reynolds-number flows. Apart from the existing schemes, we also test different forced mass conservation schemes and a constant density scheme. The capability of each scheme is investigated and, finally, recommendations for choosing a proper boundary condition scheme are given for stable and accurate simulations.

Low-frequency noise assessment metrics -- What do we know?

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

Broner, N.

1994-12-31

The issue of sound quality in offices and other occupied spaces has been of continuing interest since the 1950s. Existing assessment methods do not adequately account for the low-frequency background sound (< 250 Hz) produced by operating heating, ventilating, and air-conditioning (HVAC) systems, in particular, low-frequency rumble. This paper discusses the results of ASHRAE-sponsored research in which more than 75 HVAC noise samples were collected, normalized, and categorized in terms of sound quality. The results support previous findings that a neutral curve has a slope of approximately {minus}5 decibels (dB) per octave. There is also support for the contention thatmore » the balanced noise criterion B (NCB) curves are overly conservative in the region from 63 to 500 Hz and overly permissive below 63 Hz when compared with the room criteria (RC) curves. A modified set of room sound quality (RSQ) curves -- the room sound quality (RSQ) curves -- is proposed.« less

Choice of no-slip curved boundary condition for lattice Boltzmann simulations of high-Reynolds-number flows

NASA Astrophysics Data System (ADS)

Sanjeevi, Sathish K. P.; Zarghami, Ahad; Padding, Johan T.

2018-04-01

Various curved no-slip boundary conditions available in literature improve the accuracy of lattice Boltzmann simulations compared to the traditional staircase approximation of curved geometries. Usually, the required unknown distribution functions emerging from the solid nodes are computed based on the known distribution functions using interpolation or extrapolation schemes. On using such curved boundary schemes, there will be mass loss or gain at each time step during the simulations, especially apparent at high Reynolds numbers, which is called mass leakage. Such an issue becomes severe in periodic flows, where the mass leakage accumulation would affect the computed flow fields over time. In this paper, we examine mass leakage of the most well-known curved boundary treatments for high-Reynolds-number flows. Apart from the existing schemes, we also test different forced mass conservation schemes and a constant density scheme. The capability of each scheme is investigated and, finally, recommendations for choosing a proper boundary condition scheme are given for stable and accurate simulations.

A curved piezo-structure model: implications on active structural acoustic control.

PubMed

Henry, J K; Clark, R L

1999-09-01

Current research in Active Structural Acoustic Control (ASAC) relies heavily upon accurately capturing the application physics associated with the structure being controlled. The application of ASAC to aircraft interior noise requires a greater understanding of the dynamics of the curved panels which compose the skin of an aircraft fuselage. This paper presents a model of a simply supported curved panel with attached piezoelectric transducers. The model is validated by comparison to previous work. Further, experimental results for a simply supported curved panel test structure are presented in support of the model. The curvature is shown to affect substantially the dynamics of the panel, the integration of transducers, and the bandwidth required for structural acoustic control.

Comparison between two scalar field models using rotation curves of spiral galaxies

NASA Astrophysics Data System (ADS)

Fernández-Hernández, Lizbeth M.; Rodríguez-Meza, Mario A.; Matos, Tonatiuh

2018-04-01

Scalar fields have been used as candidates for dark matter in the universe, from axions with masses ∼ 10-5eV until ultra-light scalar fields with masses ∼ Axions behave as cold dark matter while the ultra-light scalar fields galaxies are Bose-Einstein condensate drops. The ultra-light scalar fields are also called scalar field dark matter model. In this work we study rotation curves for low surface brightness spiral galaxies using two scalar field models: the Gross-Pitaevskii Bose-Einstein condensate in the Thomas-Fermi approximation and a scalar field solution of the Klein-Gordon equation. We also used the zero disk approximation galaxy model where photometric data is not considered, only the scalar field dark matter model contribution to rotation curve is taken into account. From the best-fitting analysis of the galaxy catalog we use, we found the range of values of the fitting parameters: the length scale and the central density. The worst fitting results (values of χ red2 much greater than 1, on the average) were for the Thomas-Fermi models, i.e., the scalar field dark matter is better than the Thomas- Fermi approximation model to fit the rotation curves of the analysed galaxies. To complete our analysis we compute from the fitting parameters the mass of the scalar field models and two astrophysical quantities of interest, the dynamical dark matter mass within 300 pc and the characteristic central surface density of the dark matter models. We found that the value of the central mass within 300 pc is in agreement with previous reported results, that this mass is ≈ 107 M ⊙/pc2, independent of the dark matter model. And, on the contrary, the value of the characteristic central surface density do depend on the dark matter model.

The properties of coke breeze briquettes produced by ram briquetting

NASA Astrophysics Data System (ADS)

Loginov, Yu. N.; Babailov, N. A.; Polyansky, L. I.

2017-12-01

The paper reports on the results of briquetting coke breeze with a binder in a closed cylindrical press-die. Liquid glass is used as a binder. Approximating curves for the "compaction ratio vs. compaction pressure" dependences are plotted from experimental data. The mechanical properties of the briquettes are determined, namely, drop damage resistance and breaking stress. The results are presented as approximating dependences in the form of a power function.

Integrated Sensing and Processing (ISP) Phase 2: Demonstration and Evaluation for Distributed Sensor Networks and Missile Seeker Systems

DTIC Science & Technology

2007-05-29

International Conference Acoustics Speech and Signal Processing (ICASSP 2007) conference 15 − 20 April 2007 in Honolulu, Hawaii. 1. E. Near Term...from the sensor measured in feet. The detection performance of the footstep in the presence of interfering speech was characterized in previously...investigation, we developed a simple piecewise linear approximation to the probability of detection curve with no interfering speech . This approximation was

Technology innovations and experience curves for nitrogen oxides control technologies.

PubMed

Yeh, Sonia; Rubin, Edward S; Taylor, Margaret R; Hounshell, David A

2005-12-01

This paper reviews the regulatory history for nitrogen oxides (NOx) pollutant emissions from stationary sources, primarily in coal-fired power plants. Nitrogen dioxide (NO2) is one of the six criteria pollutants regulated by the 1970 Clean Air Act where National Ambient Air Quality Standards were established to protect public health and welfare. We use patent data to show that in the cases of Japan, Germany, and the United States, innovations in NOx control technologies did not occur until stringent government regulations were in place, thus "forcing" innovation. We also demonstrate that reductions in the capital and operation and maintenance (O&M) costs of new generations of high-efficiency NOx control technologies, selective catalytic reduction (SCR), are consistently associated with the increasing adoption of the control technology: the so-called learning-by-doing phenomena. The results show that as cumulative world coal-fired SCR capacity doubles, capital costs decline to approximately 86% and O&M costs to 58% of their original values. The observed changes in SCR technology reflect the impact of technological advance as well as other factors, such as market competition and economies of scale.

The end-Triassic mass extinction: A new correlation between extinction events and δ13C fluctuations from a Triassic-Jurassic peritidal succession in western Sicily

NASA Astrophysics Data System (ADS)

Todaro, Simona; Rigo, Manuel; Randazzo, Vincenzo; Di Stefano, Pietro

2018-06-01

A new δ13Ccarb curve was obtained from an expanded peritidal succession in western Sicily and was used to investigate the relationships between isotopic signatures and biological events on carbonate platforms across the Triassic-Jurassic boundary (TJB). The resulting curve shows two main negative carbon isotopic excursions (CIEs) that fit well with the "Initial" and "Main" CIEs that are recognized worldwide and linked to the End-Triassic Extinction (ETE). In the studied section, the first negative CIE marks the disappearance of the large megalodontids, which were replaced by small and thin-shelled specimens, while the "Main" CIE corresponds to the last occurrence (LO) of the megalodontids and, approximately 50 m upsection, to the total demise of the Rhaetian benthic foraminifer community. Upward, the carbon curve shows a positive trend (ca. +1‰) and a gradual recovery of the benthic communities after an approximately 10 m-thick barren interval populated only by the problematic alga Thaumatoporella parvovesiculifera. A comparison between the Mt. Sparagio δ13Ccarb curve and other coeval Ccarb and Corg curves from carbonate platform, ramp and deep basin successions indicates similar isotopic trends; however, the diverse magnitudes and responses of benthic communities confirm that the carbon cycle perturbations have been globally significant, and were influenced by external forces such as CAMP volcanism. The multiphase nature of the extinction pulses could have been caused by local environmental changes related to transgression/regression phenomena. Overall, this study adds new data and a new timing to the effect of the acidification process on carbon productivity and benthic communities in different environments across the TJB.

Erratum: ``The Internal Energy for Molecular Hydrogen in Gravitationally Unstable Protoplanetary Disks'' (ApJ, 656, L89 [2007])

NASA Astrophysics Data System (ADS)

Boley, Aaron C.; Hartquist, Thomas W.; Durisen, Richard H.; Michael, Scott

2007-05-01

In the above-mentioned Letter, we stated that Boss uses a discontinuous internal energy for H2, where H2 contributes 3kT/4mp to the specific internal energy e for T<=100 K and 5kT/4mp for T>100 K, based on his own citations to A. P. Boss (ApJ, 277, 768 [1984]). It was brought to our attention by A. P. Boss (2007, private communication) that he now uses a quadratic interpolation for e between 100 and 200 K (see Fig. 1, left panel). This change is not mentioned in the literature but is alluded to in A. P. Boss (ApJ, 346, 336 [1989]). According to Boss, the interpolation has been used in all his simulations since Boss (1989). In Figure 1 (right panel), we also illustrate the consequences for Γ1 of Boss's latest e approximation by calculating the specific heat at constant volume cv=de/dT and by relating that to Γ1 (see J. P. Cox & R. T. Giuli, Principles of Stellar Structure [New York: Gordon & Breach, 1968]). This curve is compared with curves for pure para-hydrogen (short-dashed curve), a 3:1 ortho/para-hydrogen mixture (long-dashed curve), where the species are treated as independent, and an equilibrium mixture (solid curve). Because fragmentation becomes more likely as Γ1 is lowered (W. K. M. Rice, G. Lodato, & P. J. Armitage, MNRAS, 364, L56 [2005]), Boss's approximation between 100 and 200 K is likely to make his disks susceptible to fragmentation for that temperature range. We would like to thank A. P. Boss for his discussions and clarification of his code.

Theoretical evaluation of the radiative lifetimes of LiCs and NaCs in the A1Σ+ state

NASA Astrophysics Data System (ADS)

Mabrouk, N.; Berriche, H.

2017-08-01

Calculations of the adiabatic potential energy curves and the transition dipole moments between the ground (A1Σ+) and the first excited (A1Σ+) states have been determined for the LiCs and NaCs molecules. The calculations are performed using an ab initio approach based on non-empirical pseudopotentials for Cs+, Li+ and Na+ cores, parameterized l-dependent polarization potentials and full configuration interaction calculations. The potential energy curves and the transition dipole moment are used to estimate the radiative lifetimes of the vibrational levels of the A+Σ+ state using the Franck-Condon (FC) approximation and the approximate sum rule method. The radiative lifetimes associated with the A+Σ+ state are presented here for the first time. These data can help experimentalists to optimize photoassociative formation of ultracold molecules and their longevity in a trap or in an optical lattice.

Interactions between Ground State Oxygen Atoms and Molecules: O - O and O (sub2) - O (sub2)

NASA Technical Reports Server (NTRS)

Vanderslice, Joseph T.; Mason, Edward A.; Maisch, William G.

1960-01-01

Potential energy curves for O - O interactions corresponding to the X (sup 3) Sigma - g, 1 delta g, 1 Sigma plus g, 3 delta u, A3 Sigma plus u, 1 Sigma - u, and B3 Sigma states of O (sub 2) have been calculated from spectroscopic data by the Rydberg-Klein-Rees method. Curves for the remaining twelve states of O (sub 2) dissociating to ground state atoms have been obtained from relations derived from approximate quantum-mechanical calculations, and checked against the meager experimental information available. Two semi-independent calculations have been made, and are in good agreement with each other. The quantum-mechanical relations also lead to an approximate O (sub 2) - O (sub 2) interaction, which is consistent with interactions derived from vibrational relaxation times and from high-temperature gas viscosity data.

Indirect synthesis of multidegree-of-freedom transient systems

NASA Technical Reports Server (NTRS)

Chen, Y. H.; Pilkey, W. D.; Kalinowski, A. J.

1976-01-01

The indirect synthesis method is developed and shown to be capable of leading a near-optimal design of multidegree-of-freedom and multidesign-element transient nonlinear dynamical systems. The basis of the approach is to select the open design parameters such that the response of the portion of the system being designed approximates the limiting performances solution. The limiting performance problem can be formulated as one of linear programming by replacing all portions of the system subject to transient disturbances by control forces and supposing that the remaining portions are linear as are the overall kinematic constraints. One then selects the design parameters that respond most closely to the limiting performance solution, which can be achieved by unconstrained curve-fitting techniques.

Gravity Waves and Linear Inflation From Axion Monodromy

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

McAllister, Liam; /Cornell U., LEPP /Cornell U., Phys. Dept.; Silverstein, Eva

2010-08-26

Wrapped branes in string compactifications introduce a monodromy that extends the field range of individual closed-string axions to beyond the Planck scale. Furthermore, approximate shift symmetries of the system naturally control corrections to the axion potential. This suggests a general mechanism for chaotic inflation driven by monodromy-extended closed-string axions. We systematically analyze this possibility and show that the mechanism is compatible with moduli stabilization and can be realized in many types of compactifications, including warped Calabi-Yau manifolds and more general Ricci-curved spaces. In this broad class of models, the potential is linear in the canonical inflaton field, predicting a tensormore » to scalar ratio r {approx} 0.07 accessible to upcoming cosmic microwave background (CMB) observations.« less

Application of TL dosemeters for dose distribution measurements at high temperatures in nuclear reactors.

PubMed

Osvay, M; Deme, S

2006-01-01

Al2O3:Mg,Y ceramic thermoluminescence dosemeters were developed at the Institute of Isotopes for high dose applications at room temperatures. The glow curve of Al2O3:Mg,Y exhibits two peaks--one at 250 degrees C (I) and another peak at approximately 400 degrees C (II). In order to extend the application of these dosemeters to high temperatures, the effect of irradiation temperature was investigated using temperature controlled heating system during high dose irradiation at various temperatures (20-100 degrees C). The new calibration and measuring method has been successfully applied for dose mapping within the hermetic zone of the Paks Nuclear Power Plant even at high temperature parts of blocks.

Regional Cerebral Blood Flow In Dementia: Receiver-Operating-Characteristic Analysis

NASA Astrophysics Data System (ADS)

Zemcov, Alexander; Barclay, Laurie; Sansone, Joseph; Blass, John P.; Metz, Charles E.

1985-06-01

The coupling of mentation to regional cerebral blood flow (rCBF) has prompted the application of the Xe-133 inhalation method of measuring rCBF in the differential diagnosis of the two most common dementing diseases, Alzheimer's disease and multi-infarct dementia (MID). In this study receiver-operating-characteristic (ROC) curve analysis was used to assess the effectiveness of a 32 detector Xe-133 inhalation system in discriminating between patients with Alzheimer's disease and normal controls, MID patients and normal controls and between patients with Alzheimer's disease and MID. The populations were clinically evaluated as 1) normal (age 63.1 + 13.1, n=23), 2) Alzheimer's disease (age 72.7 + 7.0, n=82), 3) MID (age 76.4 + 7.6, n=27): The mean flow values for all detectors were lowest for the Alzheimer's disease group, larger for the MID group and largest for the normal controls. The dynamic relationship between the correct identifications (true posi-tives) versus incorrect identifications (false positives) per detector for any 2 pairs of clinical groups varies as the cutoff value of flow is changed over the range of experimental blood flow values. Therefore a quantitative characterization of the "decision" or ROC curve (TP vs FP) for each detector and for each pair of clinical groups provides a measure of the overall diagnostic efficacy of the detector. Detectors directed approximately toward the speech, auditory and association cortices were most effective in disciminatinq between each of the dementia groups and the controls. Frontal detectors were diagnostically inefficient. The Xe-133 inhalation system provided virtually no diagnostic power in discriminating between the two forms of dementia, however. Therefore this imaging technology is most useful when assessing the general diagnostic state of dementia (Alz-heimer's disease and MID) from normal cognitive function.

Physical Properties of the X-Ray-Luminous SN 1978K in NGC 1313 from Multiwavelength Observations

NASA Astrophysics Data System (ADS)

Schlegel, Eric M.; Ryder, Stuart; Staveley-Smith, L.; Petre, R.; Colbert, E.; Dopita, M.; Campbell-Wilson, D.

1999-12-01

We update the light curves from the X-ray, optical, and radio bandpasses which we have assembled over the past decade and present two observations in the ultraviolet using the Hubble Space Telescope Faint Object Spectrograph. The HRI X-ray light curve is constant within the errors over the entire observation period. This behavior is confirmed in the ASCA GIS data obtained in 1993 and 1995. In the ultraviolet, we detected Lyα, the [Ne IV] 2422/2424 Å doublet, the Mg II doublet at 2800 Å, and a line at approximately 3190 Å that we attribute to He I 3187. Only the Mg II and He I lines are detected at SN 1978K's position. The optical light curve is formally constant within the errors, although a slight upward trend may be present. The radio light curve continues its steep decline. The longer time span of our radio observations compared to previous studies shows that SN 1978K is in the same class of highly X-ray and radio-luminous supernovae as SN 1986J and SN 1988Z. The [Ne IV] emission is spatially distant from the location of SN 1978K and originates in the preshocked matter. The Mg II doublet flux ratio implies the quantity of line optical depth times density of approximately 1014 cm-3 for its emission region. The emission site must lie in the shocked gas.

Comparison of heavy metal loads in stormwater runoff from major and minor urban roads using pollutant yield rating curves.

PubMed

Davis, Brett; Birch, Gavin

2010-08-01

Trace metal export by stormwater runoff from a major road and local street in urban Sydney, Australia, is compared using pollutant yield rating curves derived from intensive sampling data. The event loads of copper, lead and zinc are well approximated by logarithmic relationships with respect to total event discharge owing to the reliable appearance of a first flush in pollutant mass loading from urban roads. Comparisons of the yield rating curves for these three metals show that copper and zinc export rates from the local street are comparable with that of the major road, while lead export from the local street is much higher, despite a 45-fold difference in traffic volume. The yield rating curve approach allows problematic environmental data to be presented in a simple yet meaningful manner with less information loss. Copyright 2010 Elsevier Ltd. All rights reserved.

Remarkable modification of light curves for shadowing effects on irregular surfaces - The case of the asteroid 37 Fides

NASA Technical Reports Server (NTRS)

Zappala, V.; Di Martino, M.; Scaltriti, F.; Burchi, R.; Milano, L.; Young, J. W.; Wahlgren, G.; Pavlovski, K.

1983-01-01

Photometric observations of the asteroid 37 Fides carried out at four observatories are reported. The data were taken at phase angles ranging from approximately 2-23 deg. A composite of the light curves obtained revealed that, considering a period of 7.33 hr, the full cycle light curve exhibits one maximum and one minimum. An increase in brightness was observed following a primary minimum, a factor that indicated the cyclical appearance and disappearance of a large topographical feature. It is concluded that the 7.33 hr period is the rotational speed of the asteroid, in contrast with a previously held 14.66 hr rotational period. The method is concluded useful for identifying rotational periods of asteroids when only partial light curve data from different sources is available, and when the projections can be checked observationally.

Lattice dynamics of Ru2FeX (X = Si, Ge) Full Heusler alloys

NASA Astrophysics Data System (ADS)

Rizwan, M.; Afaq, A.; Aneeza, A.

2018-05-01

In present work, the lattice dynamics of Ru2FeX (X = Si, Ge) full Heusler alloys are investigated using density functional theory (DFT) within generalized gradient approximation (GGA) in a plane wave basis, with norm-conserving pseudopotentials. Phonon dispersion curves and phonon density of states are obtained using first-principles linear response approach of density functional perturbation theory (DFPT) as implemented in Quantum ESPRESSO code. Phonon dispersion curves indicates for both Heusler alloys that there is no imaginary phonon in whole Brillouin zone, confirming dynamical stability of these alloys in L21 type structure. There is a considerable overlapping between acoustic and optical phonon modes predicting no phonon band gap exists in dispersion curves of alloys. The same result is shown by phonon density of states curves for both Heusler alloys. Reststrahlen band for Ru2FeSi is found smaller than Ru2FeGe.

It's time to move on from the bell curve.

PubMed

Robinson, Lawrence R

2017-11-01

The bell curve was first described in the 18th century by de Moivre and Gauss to depict the distribution of binomial events, such as coin tossing, or repeated measures of physical objects. In the 19th and 20th centuries, the bell curve was appropriated, or perhaps misappropriated, to apply to biologic and social measures across people. For many years we used it to derive reference values for our electrophysiologic studies. There is, however, no reason to believe that electrophysiologic measures should approximate a bell-curve distribution, and empiric evidence suggests they do not. The concept of using mean ± 2 standard deviations should be abandoned. Reference values are best derived by using non-parametric analyses, such as percentile values. This proposal aligns with the recommendation of the recent normative data task force of the American Association of Neuromuscular & Electrodiagnostic Medicine and follows sound statistical principles. Muscle Nerve 56: 859-860, 2017. © 2017 Wiley Periodicals, Inc.

Atlas of the Light Curves and Phase Plane Portraits of Selected Long-Period Variables

NASA Astrophysics Data System (ADS)

Kudashkina, L. S.; Andronov, I. L.

2017-12-01

For a group of the Mira-type stars, semi-regular variables and some RV Tau - type stars the limit cycles were computed and plotted using the phase plane diagrams. As generalized coordinates x and x', we have used φ - the brightness of the star and its phase derivative. We have used mean phase light curves using observations of various authors from the databases of AAVSO, AFOEV, VSOLJ, ASAS and approximated using a trigonometric polynomial of statistically optimal degree. For a simple sine-like light curve, the limit cycle is a simple ellipse. In a case of more complicated light curve, in which harmonics are statistically significant, the limit cycle has deviations from the ellipse. In an addition to a classical analysis, we use the error estimates of the smoothing function and its derivative to constrain an "error corridor" in the phase plane.

A curve fitting method for solving the flutter equation. M.S. Thesis

NASA Technical Reports Server (NTRS)

Cooper, J. L.

1972-01-01

A curve fitting approach was developed to solve the flutter equation for the critical flutter velocity. The psi versus nu curves are approximated by cubic and quadratic equations. The curve fitting technique utilized the first and second derivatives of psi with respect to nu. The method was tested for two structures, one structure being six times the total mass of the other structure. The algorithm never showed any tendency to diverge from the solution. The average time for the computation of a flutter velocity was 3.91 seconds on an IBM Model 50 computer for an accuracy of five per cent. For values of nu close to the critical root of the flutter equation the algorithm converged on the first attempt. The maximum number of iterations for convergence to the critical flutter velocity was five with an assumed value of nu relatively distant from the actual crossover.

Light Curves and Analyses of the Eclipsing Overcontact Binaries V546 And & V566 And & the Discovery of a New Variable Star

NASA Astrophysics Data System (ADS)

Bradstreet, David H.; Sanders, S. J.; Volpert, C. G.

2013-01-01

New precision V & Rc light curves of the eclipsing binaries V546 And and V566 And have been obtained using the 41-cm telescopes at the Eastern University Observatory equipped with SBIG ST-10XME CCD’s. V546 And (GSC 2828:18, P = 0.3831 days, m = 11.2) has only one published discovery light curve with significant scatter in the data. The system was observed on seven nights from 30 Aug - 20 Sep 2012, accumulating approximately 900 observations in both V and Rc. The light curves show distinctly that the system is totally eclipsing and preliminary analysis indicates that the binary is W-type (the larger, more massive star is the cooler component), has a mass ratio of 0.34, small temperature difference between the stars of 300 K, and a fillout of 0.30. There is also strong evidence of the presence of starspots influencing the slopes of both eclipses. V566 And (GSC 2321:257, P = 0.3897 days, m = 10.9) is a totally eclipsing overcontact system likewise showing obvious O’Connell effects likely due to starspots. V566 And was observed on seven nights from 30 Aug - 25 Sep 2012, accumulating more than 900 observations in both V and Rc. Preliminary light curve models indicate a W-type system with a small temperature difference between the stars of 200 K and a mass ratio of only 0.20. The original comparison star for V566 And, GSC 2321:911 (m = 12.0), turned out to be a previously unknown variable star with a period of approximately 0.466 days and a light amplitude in Rc of 0.15 mag. This new variable has no information concerning it in the online archives and initial analysis seems to indicate that this may be an ellipsoidal variable. The complete light curve analyses will be presented for both systems and the new variable’s light curves will also be discussed.

Excitation energies of dissociating H2: A problematic case for the adiabatic approximation of time-dependent density functional theory

NASA Astrophysics Data System (ADS)

Gritsenko, O. V.; van Gisbergen, S. J. A.; Görling, A.; Baerends, E. J.

2000-11-01

Time-dependent density functional theory (TDDFT) is applied for calculation of the excitation energies of the dissociating H2 molecule. The standard TDDFT method of adiabatic local density approximation (ALDA) totally fails to reproduce the potential curve for the lowest excited singlet 1Σu+ state of H2. Analysis of the eigenvalue problem for the excitation energies as well as direct derivation of the exchange-correlation (xc) kernel fxc(r,r',ω) shows that ALDA fails due to breakdown of its simple spatially local approximation for the kernel. The analysis indicates a complex structure of the function fxc(r,r',ω), which is revealed in a different behavior of the various matrix elements K1c,1cxc (between the highest occupied Kohn-Sham molecular orbital ψ1 and virtual MOs ψc) as a function of the bond distance R(H-H). The effect of nonlocality of fxc(r,r') is modeled by using different expressions for the corresponding matrix elements of different orbitals. Asymptotically corrected ALDA (ALDA-AC) expressions for the matrix elements K12,12xc(στ) are proposed, while for other matrix elements the standard ALDA expressions are retained. This approach provides substantial improvement over the standard ALDA. In particular, the ALDA-AC curve for the lowest singlet excitation qualitatively reproduces the shape of the exact curve. It displays a minimum and approaches a relatively large positive energy at large R(H-H). ALDA-AC also produces a substantial improvement for the calculated lowest triplet excitation, which is known to suffer from the triplet instability problem of the restricted KS ground state. Failure of the ALDA for the excitation energies is related to the failure of the local density as well as generalized gradient approximations to reproduce correctly the polarizability of dissociating H2. The expression for the response function χ is derived to show the origin of the field-counteracting term in the xc potential, which is lacking in the local density and generalized gradient approximations and which is required to obtain a correct polarizability.

A Model for the Quiescent Phase of the Recurrent Nova U Scorpii.

PubMed

Hachisu; Kato; Kato; Matsumoto; Nomoto

2000-05-10

A theoretical light curve is constructed for the quiescent phase of the recurrent nova U Scorpii in order to resolve the existing distance discrepancy between the outbursts (d approximately 6 kpc) and the quiescences (d approximately 14 kpc). Our U Sco model consists of a very massive white dwarf (WD), an accretion disk (ACDK) with a flaring-up rim, and a lobe-filling, slightly evolved, main-sequence star (MS). The model properly includes an accretion luminosity of the WD, a viscous luminosity of the ACDK, and a reflection effect of the MS and the ACDK irradiated by the WD photosphere. The B light curve is well reproduced by a model of 1.37 M middle dot in circle WD + 1.5 M middle dot in circle MS (0.8-2.0 M middle dot in circle MS is acceptable) with an ACDK having a flaring-up rim and the inclination angle of the orbit i approximately 80&j0;. The calculated color is rather blue (B-V approximately 0.0) for a suggested mass accretion rate of 2.5x10-7 M middle dot in circle yr-1, thus indicating a large color excess of E(B-V) approximately 0.56 with the observational color of B-V=0.56 in quiescence. Such a large color excess corresponds to an absorption of AV approximately 1.8 and AB approximately 2.3, which reduces the distance to 6-8 kpc. This is in good agreement with the distance estimation of 4-6 kpc for the latest outburst. Such a large intrinsic absorption is very consistent with the recently detected period change of U Sco, which is indicating a mass outflow of approximately 3x10-7 M middle dot in circle yr-1 through the outer Lagrangian points in quiescence.

Relevance Vector Machine and Support Vector Machine Classifier Analysis of Scanning Laser Polarimetry Retinal Nerve Fiber Layer Measurements

PubMed Central

Bowd, Christopher; Medeiros, Felipe A.; Zhang, Zuohua; Zangwill, Linda M.; Hao, Jiucang; Lee, Te-Won; Sejnowski, Terrence J.; Weinreb, Robert N.; Goldbaum, Michael H.

2010-01-01

Purpose To classify healthy and glaucomatous eyes using relevance vector machine (RVM) and support vector machine (SVM) learning classifiers trained on retinal nerve fiber layer (RNFL) thickness measurements obtained by scanning laser polarimetry (SLP). Methods Seventy-two eyes of 72 healthy control subjects (average age = 64.3 ± 8.8 years, visual field mean deviation =−0.71 ± 1.2 dB) and 92 eyes of 92 patients with glaucoma (average age = 66.9 ± 8.9 years, visual field mean deviation =−5.32 ± 4.0 dB) were imaged with SLP with variable corneal compensation (GDx VCC; Laser Diagnostic Technologies, San Diego, CA). RVM and SVM learning classifiers were trained and tested on SLP-determined RNFL thickness measurements from 14 standard parameters and 64 sectors (approximately 5.6° each) obtained in the circumpapillary area under the instrument-defined measurement ellipse (total 78 parameters). Tenfold cross-validation was used to train and test RVM and SVM classifiers on unique subsets of the full 164-eye data set and areas under the receiver operating characteristic (AUROC) curve for the classification of eyes in the test set were generated. AUROC curve results from RVM and SVM were compared to those for 14 SLP software-generated global and regional RNFL thickness parameters. Also reported was the AUROC curve for the GDx VCC software-generated nerve fiber indicator (NFI). Results The AUROC curves for RVM and SVM were 0.90 and 0.91, respectively, and increased to 0.93 and 0.94 when the training sets were optimized with sequential forward and backward selection (resulting in reduced dimensional data sets). AUROC curves for optimized RVM and SVM were significantly larger than those for all individual SLP parameters. The AUROC curve for the NFI was 0.87. Conclusions Results from RVM and SVM trained on SLP RNFL thickness measurements are similar and provide accurate classification of glaucomatous and healthy eyes. RVM may be preferable to SVM, because it provides a Bayesian-derived probability of glaucoma as an output. These results suggest that these machine learning classifiers show good potential for glaucoma diagnosis. PMID:15790898

Approximate Genealogies Under Genetic Hitchhiking

PubMed Central

Pfaffelhuber, P.; Haubold, B.; Wakolbinger, A.

2006-01-01

The rapid fixation of an advantageous allele leads to a reduction in linked neutral variation around the target of selection. The genealogy at a neutral locus in such a selective sweep can be simulated by first generating a random path of the advantageous allele's frequency and then a structured coalescent in this background. Usually the frequency path is approximated by a logistic growth curve. We discuss an alternative method that approximates the genealogy by a random binary splitting tree, a so-called Yule tree that does not require first constructing a frequency path. Compared to the coalescent in a logistic background, this method gives a slightly better approximation for identity by descent during the selective phase and a much better approximation for the number of lineages that stem from the founder of the selective sweep. In applications such as the approximation of the distribution of Tajima's D, the two approximation methods perform equally well. For relevant parameter ranges, the Yule approximation is faster. PMID:17182733

Investigation of new radar-data-reduction techniques used to determine drag characteristics of a free-flight vehicle

NASA Technical Reports Server (NTRS)

Woodbury, G. E.; Wallace, J. W.

1974-01-01

An investigation was conducted of new techniques used to determine the complete transonic drag characteristics of a series of free-flight drop-test models using principally radar tracking data. The full capabilities of the radar tracking and meteorological measurement systems were utilized. In addition, preflight trajectory design, exact kinematic equations, and visual-analytical filtering procedures were employed. The results of this study were compared with the results obtained from analysis of the onboard, accelerometer and pressure sensor data of the only drop-test model that was instrumented. The accelerometer-pressure drag curve was approximated by the radar-data drag curve. However, a small amplitude oscillation on the latter curve precluded a precise definition of its drag rise.

Anharmonic Potential Constants and Their Dependence Upon Bond Length

DOE R&D Accomplishments Database

Herschbach, D. R.; Laurie, V. W.

1961-01-01

Empirical study of cubic and quartic vibrational force constants for diatomic molecules shows them to be approximately exponential functions of internuclear distance. A family of curves is obtained, determined by the location of the bonded atoms in rows of the periodic table. Displacements between successive curves correspond closely to those in Badger's rule for quadratic force constants (for which the parameters are redetermined to accord with all data now available). Constants for excited electronic and ionic states appear on practically the same curves as those for the ground states. Predictions based on the diatomic correlations agree with the available cubic constants for bond stretching in polyatomic molecules, regardless of the type of bonding involved. Implications of these regularities are discussed. (auth)

Lane changing trajectory planning and tracking control for intelligent vehicle on curved road.

PubMed

Wang, Lukun; Zhao, Xiaoying; Su, Hao; Tang, Gongyou

2016-01-01

This paper explores lane changing trajectory planning and tracking control for intelligent vehicle on curved road. A novel arcs trajectory is planned for the desired lane changing trajectory. A kinematic controller and a dynamics controller are designed to implement the trajectory tracking control. Firstly, the kinematic model and dynamics model of intelligent vehicle with non-holonomic constraint are established. Secondly, two constraints of lane changing on curved road in practice (LCCP) are proposed. Thirdly, two arcs with same curvature are constructed for the desired lane changing trajectory. According to the geometrical characteristics of arcs trajectory, equations of desired state can be calculated. Finally, the backstepping method is employed to design a kinematic trajectory tracking controller. Then the sliding-mode dynamics controller is designed to ensure that the motion of the intelligent vehicle can follow the desired velocity generated by kinematic controller. The stability of control system is proved by Lyapunov theory. Computer simulation demonstrates that the desired arcs trajectory and state curves with B-spline optimization can meet the requirements of LCCP constraints and the proposed control schemes can make tracking errors to converge uniformly.

Applications of Adaptive Learning Controller to Synthetic Aperture Radar.

DTIC Science & Technology

1985-02-01

FIGURE 37. Location of Two Sub- Phase Histories to be Utilized in Estimating Misfocus Coefficients A and C . . . A8 FIGURES 38.-94. ALC Learning Curves ...FIGURES (Concl uded) FIGURE 23. ALC Learning Curve .... .................. ... 45 .- " FIGURE 24. ALC Learning Curve ......... ................. 47 FIGURE...25. ALC Learning Curve .... .................. ... 48 FIGURE 26. ALC Learning Curve ....... .... ... .... 50 FIGURE 27. ALC Learning Curve

Asymptotic Properties of the Sequential Empirical ROC, PPV and NPV Curves Under Case-Control Sampling.

PubMed

Koopmeiners, Joseph S; Feng, Ziding

2011-01-01

The receiver operating characteristic (ROC) curve, the positive predictive value (PPV) curve and the negative predictive value (NPV) curve are three measures of performance for a continuous diagnostic biomarker. The ROC, PPV and NPV curves are often estimated empirically to avoid assumptions about the distributional form of the biomarkers. Recently, there has been a push to incorporate group sequential methods into the design of diagnostic biomarker studies. A thorough understanding of the asymptotic properties of the sequential empirical ROC, PPV and NPV curves will provide more flexibility when designing group sequential diagnostic biomarker studies. In this paper we derive asymptotic theory for the sequential empirical ROC, PPV and NPV curves under case-control sampling using sequential empirical process theory. We show that the sequential empirical ROC, PPV and NPV curves converge to the sum of independent Kiefer processes and show how these results can be used to derive asymptotic results for summaries of the sequential empirical ROC, PPV and NPV curves.

Asymptotic Properties of the Sequential Empirical ROC, PPV and NPV Curves Under Case-Control Sampling

PubMed Central

Koopmeiners, Joseph S.; Feng, Ziding

2013-01-01

The receiver operating characteristic (ROC) curve, the positive predictive value (PPV) curve and the negative predictive value (NPV) curve are three measures of performance for a continuous diagnostic biomarker. The ROC, PPV and NPV curves are often estimated empirically to avoid assumptions about the distributional form of the biomarkers. Recently, there has been a push to incorporate group sequential methods into the design of diagnostic biomarker studies. A thorough understanding of the asymptotic properties of the sequential empirical ROC, PPV and NPV curves will provide more flexibility when designing group sequential diagnostic biomarker studies. In this paper we derive asymptotic theory for the sequential empirical ROC, PPV and NPV curves under case-control sampling using sequential empirical process theory. We show that the sequential empirical ROC, PPV and NPV curves converge to the sum of independent Kiefer processes and show how these results can be used to derive asymptotic results for summaries of the sequential empirical ROC, PPV and NPV curves. PMID:24039313

APPROXIMATION OF ROTATIONAL STRENGTHS FROM MOLAR ROTATION DATA AND GENERATION OF ROTATORY DISPERSION CURVES FOR D-CAMPHOR-10-SULFONATE

PubMed Central

Urry, Dan W.

1969-01-01

Starting with the expression for optical rotatory dispersion in the absorption region that was arrived at by Condon, two series were considered for the purpose of achieving the experimentally observed, steeper wavelength dependence in the absorption region while retaining the established 1/λ2 law in regions removed from absorption. The first two terms of one series in which the second term exhibits a 1/λ6 wavelength dependence were found to calculate satisfactorily the optical rotatory dispersion curve of d-camphor-10-sulfonate from 400 mμ to 190 mμ when only three bands were considered. Evaluated at the extrema, the two-term expression can be approximated by a simple equation which allows calculation of the rotational strength of a nonoverlapping band by using only the wavelength and molar rotation of the extrema and the index of refraction of the solution. The rotational strengths calculated from optical rotatory dispersion data in this manner closely agree with those calculated from corresponding circular dichroism data. Thus when position and magnitude of rotatory dispersion extrema alone are reported for carbonyls, it is suggested that such published data may be converted to approximate rotational strengths. PMID:5257123

The Role of Oxygen in Avascular Tumor Growth

PubMed Central

Grimes, David Robert; Kannan, Pavitra; McIntyre, Alan; Kavanagh, Anthony; Siddiky, Abul; Wigfield, Simon; Harris, Adrian; Partridge, Mike

2016-01-01

The oxygen status of a tumor has significant clinical implications for treatment prognosis, with well-oxygenated subvolumes responding markedly better to radiotherapy than poorly supplied regions. Oxygen is essential for tumor growth, yet estimation of local oxygen distribution can be difficult to ascertain in situ, due to chaotic patterns of vasculature. It is possible to avoid this confounding influence by using avascular tumor models, such as tumor spheroids, a much better approximation of realistic tumor dynamics than monolayers, where oxygen supply can be described by diffusion alone. Similar to in situ tumours, spheroids exhibit an approximately sigmoidal growth curve, often approximated and fitted by logistic and Gompertzian sigmoid functions. These describe the basic rate of growth well, but do not offer an explicitly mechanistic explanation. This work examines the oxygen dynamics of spheroids and demonstrates that this growth can be derived mechanistically with cellular doubling time and oxygen consumption rate (OCR) being key parameters. The model is fitted to growth curves for a range of cell lines and derived values of OCR are validated using clinical measurement. Finally, we illustrate how changes in OCR due to gemcitabine treatment can be directly inferred using this model. PMID:27088720

Manufacturing of ionic polymer-metal composites (IPMCs) that can actuate into complex curves

NASA Astrophysics Data System (ADS)

Stoimenov, Boyko L.; Rossiter, Jonathan M.; Mukai, Toshiharu

2007-04-01

Ionic polymer-metal composites (IPMC) are soft actuators with potential applications in the fields of medicine and biologically inspired robotics. Typically, an IPMC bends with approximately constant curvature when voltage is applied to it. More complex shapes were achieved in the past by pre-shaping the actuator or by segmentation and separate actuation of each segment. There are many applications for which fully independent control of each segment of the IPMC is not required and the use of external wiring is objectionable. In this paper we propose two key elements needed to create an IPMC, which can actuate into a complex curve. The first is a connection between adjacent segments, which enables opposite curvature. This can be achieved by reversing the polarity applied on each side of the IPMC, for example by a through-hole connection. The second key element is a variable curvature segment. The segment is designed to bend with any fraction of its full bending ability under given electrical input by changing the overlap of opposite charge electrodes. We demonstrated the usefulness of these key elements in two devices. One is a bi-stable buckled IPMC beam, also used as a building block in a linear actuator device. The other one is an IPMC, actuating into an S-shaped curve with gradually increasing curvature near the ends. The proposed method of manufacturing holds promise for a wide range of new applications of IPMCs, including applications in which IPMCs are used for sensing.

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

Li, Hongyi; Sivapalan, Murugesu; Tian, Fuqiang

Inspired by the Dunne diagram, the climatic and landscape controls on the partitioning of annual runoff into its various components (Hortonian and Dunne overland flow and subsurface stormflow) are assessed quantitatively, from a purely theoretical perspective. A simple distributed hydrologic model has been built sufficient to simulate the effects of different combinations of climate, soil, and topography on the runoff generation processes. The model is driven by a sequence of simple hypothetical precipitation events, for a large combination of climate and landscape properties, and hydrologic responses at the catchment scale are obtained through aggregation of grid-scale responses. It is found,more » first, that the water balance responses, including relative contributions of different runoff generation mechanisms, could be related to a small set of dimensionless similarity parameters. These capture the competition between the wetting, drying, storage, and drainage functions underlying the catchment responses, and in this way, provide a quantitative approximation of the conceptual Dunne diagram. Second, only a subset of all hypothetical catchment/climate combinations is found to be ‘‘behavioral,’’ in terms of falling sufficiently close to the Budyko curve, describing mean annual runoff as a function of climate aridity. Furthermore, these behavioral combinations are mostly consistent with the qualitative picture presented in the Dunne diagram, indicating clearly the commonality between the Budyko curve and the Dunne diagram. These analyses also suggest clear interrelationships amongst the ‘‘behavioral’’ climate, soil, and topography parameter combinations, implying these catchment properties may be constrained to be codependent in order to satisfy the Budyko curve.« less

Numerical simulations of flow fields through conventionally controlled wind turbines & wind farms

NASA Astrophysics Data System (ADS)

Emre Yilmaz, Ali; Meyers, Johan

2014-06-01

In the current study, an Actuator-Line Model (ALM) is implemented in our in-house pseudo-spectral LES solver SP-WIND, including a turbine controller. Below rated wind speed, turbines are controlled by a standard-torque-controller aiming at maximum power extraction from the wind. Above rated wind speed, the extracted power is limited by a blade pitch controller which is based on a proportional-integral type control algorithm. This model is used to perform a series of single turbine and wind farm simulations using the NREL 5MW turbine. First of all, we focus on below-rated wind speed, and investigate the effect of the farm layout on the controller calibration curves. These calibration curves are expressed in terms of nondimensional torque and rotational speed, using the mean turbine-disk velocity as reference. We show that this normalization leads to calibration curves that are independent of wind speed, but the calibration curves do depend on the farm layout, in particular for tightly spaced farms. Compared to turbines in a lone-standing set-up, turbines in a farm experience a different wind distribution over the rotor due to the farm boundary-layer interaction. We demonstrate this for fully developed wind-farm boundary layers with aligned turbine arrangements at different spacings (5D, 7D, 9D). Further we also compare calibration curves obtained from full farm simulations with calibration curves that can be obtained at a much lower cost using a minimal flow unit.

Gaussian mixture models for detection of autism spectrum disorders (ASD) in magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Almeida, Javier; Velasco, Nelson; Alvarez, Charlens; Romero, Eduardo

2017-11-01

Autism Spectrum Disorder (ASD) is a complex neurological condition characterized by a triad of signs: stereotyped behaviors, verbal and non-verbal communication problems. The scientific community has been interested on quantifying anatomical brain alterations of this disorder. Several studies have focused on measuring brain cortical and sub-cortical volumes. This article presents a fully automatic method which finds out differences among patients diagnosed with autism and control patients. After the usual pre-processing, a template (MNI152) is registered to an evaluated brain which becomes then a set of regions. Each of these regions is the represented by the normalized histogram of intensities which is approximated by mixture of Gaussian (GMM). The gray and white matter are separated to calculate the mean and standard deviation of each Gaussian. These features are then used to train, region per region, a binary SVM classifier. The method was evaluated in an adult population aged from 18 to 35 years, from the public database Autism Brain Imaging Data Exchange (ABIDE). Highest discrimination values were found for the Right Middle Temporal Gyrus, with an Area Under the Curve (AUC) of the Receiver Operating Characteristic (ROC) the curve of 0.72.

Single cigar-shaped nanopores functionalized with amphoteric amino acid chains: experimental and theoretical characterization.

PubMed

Ali, Mubarak; Ramirez, Patricio; Nguyen, Hung Quoc; Nasir, Saima; Cervera, Javier; Mafe, Salvador; Ensinger, Wolfgang

2012-04-24

We present an experimental and theoretical characterization of single cigar-shaped nanopores with pH-responsive carboxylic acid and lysine chains functionalized on the pore surface. The nanopore characterization includes (i) optical images of the nanostructure obtained by FESEM; (ii) different chemical procedures for the nanopore preparation (etching time and functionalizations; pH and electrolyte concentration of the external solution) allowing externally tunable nanopore responses monitored by the current-voltage (I-V) curves; and (iii) transport simulations obtained with a multilayer nanopore model. We show that a single, approximately symmetric nanopore can be operated as a reconfigurable diode showing different rectifying behaviors by applying chemical and electrical signals. The remarkable characteristics of the new nanopore are the sharp response observed in the I-V curves, the improved tunability (with respect to previous designs of symmetric nanopores) which is achieved because of the direct external access to the nanostructure mouths, and the broad range of rectifying properties. The results concern both fundamental concepts useful for the understanding of transport processes in biological systems (ion channels) and applications relevant for tunable nanopore technology (information processing and drug controlled release).

Efficiency of herbal medicine Dai-kenchu-to on portal blood flow in rat models

PubMed Central

Muraoka, Izumi; Takatsuki, Mitsuhisa; Soyama, Akihiko; Yamaguchi, Izumi; Tanaka, Shiro; Tanaka, Takayuki; Kinoshita, Ayaka; Hara, Takanobu; Kuroki, Tamotsu; Eguchi, Susumu

2015-01-01

Introduction To clarify the influence of Dai-Kenchu-To (DKT) on portal blood flow (PBF), PBF was continuously measured with Doppler ultrasound. Methods Normal liver rats were divided into a DKT 90 mg/kg, DKT 270 mg/kg administered group, and control, while cirrhotic liver rats were divided into a DKT-LC 90 mg/kg administered group and Control-LC. The PBF was measured after the administration of either DKT or water for 60 min by laser Doppler flowmetry system. Results The PBF in the DKT 90 increased approximately 10 min after DKT was administrated, and elevated levels were maintained for approximately 10 min. A comparison of the increase in PBF by the calculating the area under the curve (AUC) revealed that flow was significantly higher in the DKT 90 compared to either the control or the DKT 270 (p < 0.05). The cirrhotic liver group showed stable PBF in both the DKT-LC and Control-LC. The AUC, revealed no significant difference between the DKT-LC and Control-LC. Discussion DKT induced an increase in PBF in normal livers; however, its effects were insufficient to increase PBF in the cirrhotic livers. No increase in the portal blood flow in the cirrhotic liver rats was probably the result of the cirrhotic liver, which had fibrotic change, and, therefore, may not have had sufficient compliance to accept the increasing blood flow volume from the intestinal tract. Conclusion We suggested DKT has the potential to protect the liver by increasing PBF when the liver has either normal or mild to moderate dysfunction. PMID:26155361

[Study on quantitative model for suspended sediment concentration in Taihu Lake].

PubMed

Chen, Jun; Zhou, Guan-hua; Wen, Zhen-he; Ma, Jin-Feng; Zhang, Xu; Peng, Dan-qing; Yang, Song-lin

2010-01-01

The complicated compositions of Case II waters result in the complex properties of spectral curves. The present paper analyzed the in situ measurements data of spectral curves, and further realized the relationships between the properties of spectral curves and suspended sediment concentration. The study found that the max peak of spectral curves was moving to the direction of shortwavelength as increasing suspended sediment concentration, namely the blue shift of wavelength; the area enclosed by spectral curve and coordinate axis in the range of sensitive bands had preferably linear relationship with the suspended sediment concentration (curve area model); the trapezoidal area model which was an approximation of curve area model could also excellently reflect those relationships, and be greatly suitable for multi-spectral satellite imagery retrieval such as LandSat/TM, MODIS and so on. The inversion results of trapezoidal area model for LandSat/TM imagery on October 27, 2003 in Taihu Lake showed that the suspended sediment concentration ranged from 30 to 80 mg x L(-1), the distribution pattern was higher in the west, south and central lake and lower in the east lake; compared with the in situ measurements in the regions, and the relative error of retrieval model was 6.035%.

A new methodology for free wake analysis using curved vortex elements

NASA Technical Reports Server (NTRS)

Bliss, Donald B.; Teske, Milton E.; Quackenbush, Todd R.

1987-01-01

A method using curved vortex elements was developed for helicopter rotor free wake calculations. The Basic Curve Vortex Element (BCVE) is derived from the approximate Biot-Savart integration for a parabolic arc filament. When used in conjunction with a scheme to fit the elements along a vortex filament contour, this method has a significant advantage in overall accuracy and efficiency when compared to the traditional straight-line element approach. A theoretical and numerical analysis shows that free wake flows involving close interactions between filaments should utilize curved vortex elements in order to guarantee a consistent level of accuracy. The curved element method was implemented into a forward flight free wake analysis, featuring an adaptive far wake model that utilizes free wake information to extend the vortex filaments beyond the free wake regions. The curved vortex element free wake, coupled with this far wake model, exhibited rapid convergence, even in regions where the free wake and far wake turns are interlaced. Sample calculations are presented for tip vortex motion at various advance ratios for single and multiple blade rotors. Cross-flow plots reveal that the overall downstream wake flow resembles a trailing vortex pair. A preliminary assessment shows that the rotor downwash field is insensitive to element size, even for relatively large curved elements.

Minimal entropy approximation for cellular automata

NASA Astrophysics Data System (ADS)

Fukś, Henryk

2014-02-01

We present a method for the construction of approximate orbits of measures under the action of cellular automata which is complementary to the local structure theory. The local structure theory is based on the idea of Bayesian extension, that is, construction of a probability measure consistent with given block probabilities and maximizing entropy. If instead of maximizing entropy one minimizes it, one can develop another method for the construction of approximate orbits, at the heart of which is the iteration of finite-dimensional maps, called minimal entropy maps. We present numerical evidence that the minimal entropy approximation sometimes outperforms the local structure theory in characterizing the properties of cellular automata. The density response curve for elementary CA rule 26 is used to illustrate this claim.

Towards a universal master curve in magnetorheology

NASA Astrophysics Data System (ADS)

Ruiz-López, José Antonio; Hidalgo-Alvarez, Roque; de Vicente, Juan

2017-05-01

We demonstrate that inverse ferrofluids behave as model magnetorheological fluids. A universal master curve is proposed, using a reduced Mason number, under the frame of a structural viscosity model where the magnetic field strength dependence is solely contained in the Mason number and the particle concentration is solely contained in the critical Mason number (i.e. the yield stress). A linear dependence of the critical Mason number with the particle concentration is observed that is in good agreement with a mean (average) magnetization approximation, particle level dynamic simulations and micromechanical models available in the literature.

Micro-combustor for gas turbine engine

DOEpatents

Martin, Scott M.

2010-11-30

An improved gas turbine combustor (20) including a basket (26) and a multiplicity of micro openings (29) arrayed across an inlet wall (27) for passage of a fuel/air mixture for ignition within the combustor. The openings preferably have a diameter on the order of the quenching diameter; i.e. the port diameter for which the flame is self-extinguishing, which is a function of the fuel mixture, temperature and pressure. The basket may have a curved rectangular shape that approximates the shape of the curved rectangular shape of the intake manifolds of the turbine.

Statistical Analysis and Storm Sampling Approach for Lakes Michigan and St. Clair, Great Lakes Coastal Flood Study, 2012 Federal Inter-Agency Initiative

DTIC Science & Technology

2012-09-01

Originally, Resio and Vincent (1977) used theoretical results derived from Cardone (1969) to develop curves relating overland to overlake wind speeds...Later, Schwab (1978) proposed the following equation as an approximation to the Cardone curves: ERDC/CHL TR-12-19 13 /Δ. Δ . ΔW L L TTU U U T...1992), the CEM (USACE 2002), and in Smith (1991); Schwab and Morton (1984); Donelan (1980); Schwab (1978); Resio and Vincent (1977); and Cardone

Plasmonic cloak using graphene at infrared frequencies

NASA Astrophysics Data System (ADS)

Li, Yan Xiu; Kong, Fan Min; Li, Kang; Zhuang, Hua Wei

2015-11-01

A carpet cloak based on graphene is designed and realized by making an approximate hemisphere surface which behaves as a flat surface, and the performances of the cloak are simulated by finite element method. The cloak performs perfectly through tuning conductivity of the graphene. The incident wave can propagate on the curved surface without being disturbed, and an object under the curved surface will be cloaked. It is indicated that graphene can be a platform for "on-atom-thick" cloaks, and the proposed methods can be applied in the practical design.

Effects of high-intensity interval exercise versus continuous moderate-intensity exercise on postprandial glycemic control assessed by continuous glucose monitoring in obese adults.

PubMed

Little, Jonathan P; Jung, Mary E; Wright, Amy E; Wright, Wendi; Manders, Ralph J F

2014-07-01

The purpose of this study was to examine the impact of acute high-intensity interval training (HIIT) compared with continuous moderate-intensity (CMI) exercise on postprandial hyperglycemia in overweight or obese adults. Ten inactive, overweight or obese adults (41 ± 11 yrs, BMI = 36 ± 7 kg/m(2)) performed an acute bout of HIIT (10 × 1 min at approximately 90% peak heart rate (HRpeak) with 1-min recovery periods) or matched work CMI (30 min at approximately 65% HRpeak) in a randomized, counterbalanced fashion. Exercise was performed 2 h after breakfast, and glucose control was assessed by continuous glucose monitoring under standardized dietary conditions over 24 h. Postprandial glucose (PPG) responses to lunch, dinner, and the following day's breakfast were analyzed and compared with a no-exercise control day. Exercise did not affect the PPG responses to lunch, but performing both HIIT and CMI in the morning significantly reduced the PPG incremental area under the curve (AUC) following dinner when compared with control (HIIT = 110 ± 35, CMI = 125 ± 34, control = 162 ± 46 mmol/L × 2 h, p < 0.05). The PPG AUC (HIIT = 125 ± 53, CMI = 186 ± 55, control = 194 ± 96 mmol/L × 2 h) and the PPG spike (HIIT = Δ2.1 ± 0.9, CMI = Δ3.0 ± 0.9, control = Δ3.0 ± 1.5 mmol/l) following breakfast on the following day were significantly lower following HIIT compared with both CMI and control (p < 0.05). Absolute AUC and absolute glucose spikes were not different between HIIT, CMI, or control for any meal (p > 0.05 for all). We conclude that a single session of HIIT has greater and more lasting effects on reducing incremental PPG when compared with CMI.

Changes in airway configuration with different head and neck positions using magnetic resonance imaging of normal airways: a new concept with possible clinical applications.

PubMed

Greenland, K B; Edwards, M J; Hutton, N J; Challis, V J; Irwin, M G; Sleigh, J W

2010-11-01

The sniffing position is often considered optimal for direct laryngoscopy. Another concept of airway configuration involving a laryngeal vestibule axis and two curves has also been suggested. We investigated whether this theory can be supported mathematically and if it supports the sniffing position as being optimal for direct laryngoscopy. Magnetic resonance imaging scans were performed in 42 normal adult volunteers. The airway passage was divided into two curves-primary (oro-pharyngeal curve) and secondary (pharyngo-glotto-tracheal curve). Airway configuration was evaluated in the neutral, extension, head lift, and sniffing positions. The airway passage, point of inflection (where the two curves meet), its tangent, and the line of sight were plotted on each scan. The point of inflection lay within the laryngeal vestibule in all positions. The head lift and sniffing positions caused the tangent to the point of inflection to approximate the horizontal plane. The sniffing, extension, and head lift positions caused a reduction in the area between the line of sight and the airway curve compared with the neutral position. A two-curve theory is proposed as a basis for explaining airway configuration. The changes in these curves with head and neck positioning support the sniffing position as optimal for direct laryngoscopy. Application of this new concept to other forms of laryngoscopy should be investigated.

High-resolution mapping of yield curve shape and evolution for high porosity sandstones

NASA Astrophysics Data System (ADS)

Bedford, J. D.; Faulkner, D.; Wheeler, J.; Leclere, H.

2017-12-01

The onset of permanent inelastic deformation for porous rock is typically defined by a yield curve plotted in P-Q space, where P is the effective mean stress and Q is the differential stress. Sandstones usually have broadly elliptical shaped yield curves, with the low pressure side of the ellipse associated with localized brittle faulting (dilation) and the high pressure side with distributed ductile deformation (compaction). However recent works have shown that these curves might not be perfectly elliptical and that significant evolution in shape occurs with continued deformation. We therefore use a novel stress-probing methodology to map in high-resolution the yield curve shape for Boise and Idaho Gray sandstones (36-38% porosity) and also investigate curve evolution with increasing deformation. The data reveal yield curves with a much flatter geometry than previously recorded for porous sandstone and that the compactive side of the curve is partly comprised of a near vertical limb. The yield curve evolution is found to be strongly dependent on the nature of inelastic strain. Samples that were compacted under a deviatoric load, with a component of inelastic shear strain, were found to have yield curves with peaks that are approximately 50% higher than similar porosity samples that were hydrostatically compacted (i.e. purely volumetric strain). The difference in yield curve evolution along the different loading paths is attributed to mechanical anisotropy that develops during deviatoric loading by the closure of preferentially orientated fractures. Increased shear strain also leads to the formation of a plateau at the peak of the yield curve as samples deform along the deviatoric loading path. These results have important implications for understanding how the strength of porous rock evolves along different stress paths, including during fluid extraction from hydrocarbon reservoirs where the stress state is rarely isotropic.

Numerical study on the influence of boss cap fins on efficiency of controllable-pitch propeller

NASA Astrophysics Data System (ADS)

Xiong, Ying; Wang, Zhanzhi; Qi, Wanjiang

2013-03-01

Numerical simulation is investigated to disclose how propeller boss cap fins (PBCF) operate utilizing Reynolds-averaged Navier-Stokes (RANS) method. In addition, exploration of the influencing mechanism of PBCF on the open water efficiency of one controllable-pitch propeller is analyzed through the open water characteristic curves, blade surface pressure distribution and hub streamline distribution. On this basis, the influence of parameters including airfoil profile, diameter, axial position of installation and circumferential installation angle on the open water efficiency of the controllable-pitch propeller is investigated. Numerical results show: for the controllable-pitch propeller, the thrust generated is at the optimum when the radius of boss cap fins is 1.5 times of propeller hub with an optimal installation position in the axial direction, and its optimal circumferential installation position is the midpoint of the extension line of the front and back ends of two adjacent propeller roots in the front of fin root. Under these optimal parameters, the gain of open water efficiency of the controllable-pitch propeller with different advance velocity coefficients is greater than 0.01, which accounts for approximately an increase of 1%-5% of open water efficiency.

Visual demand of curves and fog-limited sight distance and its relationship to brake response time.

DOT National Transportation Integrated Search

2006-05-01

Driver distraction is a major contributing factor to automobile crashes. National Highway Traffic Safety Administration (NHTSA) has estimated that approximately 25% of crashes are attributed to driver distraction and inattention (Wang, Knipling, & Go...

VatuximabTM: Optimizing Therapeutic Strategies for Prostate Cancer Based on Dynamic MR Tumor Oximetry

DTIC Science & Technology

2007-12-01

Figure 19 Growth curves for H tumors with respect to bavituximab therapy. Growth curves for groups of control and bavituximab...a large tumor designated by green label received equivalent dose of control , antibody rituximab. 0.1 1 10 1 3 5 8 11 13 15 17 19 21 days...Figure 22 Growth curves for groups of treated AT1 tumors Purple * control untreated tumors; brown ● bavituximab at 2.5 mg/kg thrice weekly

Reader strategies: variability and error- methodology, findings, and health policy implications from a study of the U.S. population of mammographers

NASA Astrophysics Data System (ADS)

Beam, Craig A.

2002-04-01

Each year, approximately 60% of all US women over the age of 40 utilize mammography. Through the matrix of an imaging technology, this Population of Patients (POP) interacts with a population of approximately 20,000 physicians who interpret mammograms in the US. This latter Population of Diagnosticians (POD) operationally serves as the interface between an image-centric healthcare technology system and patient. Methods: using data collected from a large POD and POP based study, I evaluate the distribution of several ROC curve-related parameters in the POD and explore the health policy implications of a population ROC curve for mammography. Results and Conclusions: Principal Components Analysis suggests that two Binormal parameters are sufficient to explain variation in the POD and implies that the Binormal model is foundational to Health Policy Research in Mammography. A population ROC curve based on percentiles of the POD can be used to set targets to achieve national health policy goals. Medical Image Perception science provides the framework. Alternatively, a restrictive policy can be envisioned using performance criteria based on area. However, the data suggests this sort of policy would be too costly in terms of reduced healthcare service capacity in the US in the face of burgeoning demands.

Light extraction block with curved surface

DOEpatents

Levermore, Peter; Krall, Emory; Silvernail, Jeffrey; Rajan, Kamala; Brown, Julia J.

2016-03-22

Light extraction blocks, and OLED lighting panels using light extraction blocks, are described, in which the light extraction blocks include various curved shapes that provide improved light extraction properties compared to parallel emissive surface, and a thinner form factor and better light extraction than a hemisphere. Lighting systems described herein may include a light source with an OLED panel. A light extraction block with a three-dimensional light emitting surface may be optically coupled to the light source. The three-dimensional light emitting surface of the block may includes a substantially curved surface, with further characteristics related to the curvature of the surface at given points. A first radius of curvature corresponding to a maximum principal curvature k.sub.1 at a point p on the substantially curved surface may be greater than a maximum height of the light extraction block. A maximum height of the light extraction block may be less than 50% of a maximum width of the light extraction block. Surfaces with cross sections made up of line segments and inflection points may also be fit to approximated curves for calculating the radius of curvature.

Ultrasonic velocity profiling rheometry based on a widened circular Couette flow

NASA Astrophysics Data System (ADS)

Shiratori, Takahisa; Tasaka, Yuji; Oishi, Yoshihiko; Murai, Yuichi

2015-08-01

We propose a new rheometry for characterizing the rheological properties of fluids. The technique produces flow curves, which represent the relationship between the fluid shear rate and shear stress. Flow curves are obtained by measuring the circumferential velocity distribution of tested fluids in a circular Couette system, using an ultrasonic velocity profiling technique. By adopting a widened gap of concentric cylinders, a designed range of the shear rate is obtained so that velocity profile measurement along a single line directly acquires flow curves. To reduce the effect of ultrasonic noise on resultant flow curves, several fitting functions and variable transforms are examined to best approximate the velocity profile without introducing a priori rheological models. Silicone oil, polyacrylamide solution, and yogurt were used to evaluate the applicability of this technique. These substances are purposely targeted as examples of Newtonian fluids, shear thinning fluids, and opaque fluids with unknown rheological properties, respectively. We find that fourth-order Chebyshev polynomials provide the most accurate representation of flow curves in the context of model-free rheometry enabled by ultrasonic velocity profiling.

Seismic fragility curves of bridge piers accounting for ground motions in Korea

NASA Astrophysics Data System (ADS)

Nguyen, Duy-Duan; Lee, Tae-Hyung

2018-04-01

Korea is located in a slight-to-moderate seismic zone. Nevertheless, several studies pointed that the peak earthquake magnitude in the region can be reached to approximately 6.5. Accordingly, a seismic vulnerability evaluation of the existing structures accounting for ground motions in Korea is momentous. The purpose of this paper is to develop seismic fragility curves for bridge piers of a steel box girder bridge equipped with and without base isolators based on a set of ground motions recorded in Korea. A finite element simulation platform, OpenSees, is utilized to perform nonlinear time history analyses of the bridges. A series of damage states is defined based on a damage index which is expressed in terms of the column displacement ductility ratio. The fragility curves based on Korean motions were thereafter compared with the fragility curves generated using worldwide earthquakes to assess the effect of the two ground motion groups on the seismic fragility curves of the bridge piers. The results reveal that both non- and base-isolated bridge piers are less vulnerable during the Korean ground motions than that under worldwide earthquakes.

Local Orthogonal Cutting Method for Computing Medial Curves and Its Biomedical Applications

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

Jiao, Xiangmin; Einstein, Daniel R.; Dyedov, Volodymyr

2010-03-24

Medial curves have a wide range of applications in geometric modeling and analysis (such as shape matching) and biomedical engineering (such as morphometry and computer assisted surgery). The computation of medial curves poses significant challenges, both in terms of theoretical analysis and practical efficiency and reliability. In this paper, we propose a definition and analysis of medial curves and also describe an efficient and robust method for computing medial curves. Our approach is based on three key concepts: a local orthogonal decomposition of objects into substructures, a differential geometry concept called the interior center of curvature (ICC), and integrated stabilitymore » and consistency tests. These concepts lend themselves to robust numerical techniques including eigenvalue analysis, weighted least squares approximations, and numerical minimization, resulting in an algorithm that is efficient and noise resistant. We illustrate the effectiveness and robustness of our approach with some highly complex, large-scale, noisy biomedical geometries derived from medical images, including lung airways and blood vessels. We also present comparisons of our method with some existing methods.« less

Demagnetizing correction in fluxmetric measurements of magnetization curves and hysteresis loops of ferromagnetic cylinders

NASA Astrophysics Data System (ADS)

Chen, Du-Xing; Pardo, Enric; Zhu, Yong-Hong; Xiang, Li-Xiong; Ding, Jia-Quan

2018-03-01

A technique is proposed for demagnetizing correction of the measured magnetization curve and hysteresis loop, i.e., the M∗ (Ha) curve, of a ferromagnetic cylinder into the true M (H) curve of the material, where Ha is the uniform applied field provided by a long solenoid and M∗ is the magnetization measured by a fluxmeter with the measuring coil surrounding the cylinder midplane. Different from ordinary demagnetizing correction by using a fixed demagnetizing factor, an (Ha,M∗) -dependent fluxmetric demagnetizing factor Nf (γ,χd) is used in this technique, where γ is the ratio of cylinder length to diameter, χd is the differential susceptibility on the corrected M (H) curve, and Nf (γ,χd) is approximated by accurately calculated Nf (γ, χ) of paramagnetic cylinders of the same γ and χ =χd . The validity of the technique is studied by comparing results for several samples of different lengths cut from the same cylinder. Such a demagnetizing correction is unambiguous but its success requires very high accuracy in the Nf determination and M∗ (Ha) measurements.

Ambient noise tomography of Lo'ihi

NASA Astrophysics Data System (ADS)

McClement, K.; Thurber, C. H.; Teel, A.; Caplan-Auerbach, J.

2012-12-01

Lo'ihi seamount, the youngest volcano in the Hawaiian-Emperor chain, lies approximately 30 km south of Hawai'i Island with its summit still approximately 1 km below sea level. Lo'ihi offers a unique opportunity to study the early formation of a hotspot volcano and can provide insight into the deep internal structure of the other volcanoes that make up the Hawaiian Islands. This study uses Ambient Noise Tomography (ANT) to create a 3D tomographic image of Lo'ihi's S-wave velocity structure from ocean bottom seismometer (OBS) data. ANT has been used in many subaerial studies but has seen very few applications to OBS data. This study uses continuous data recorded in 2010 to 2011 from 12 short-period OBS instruments deployed on and around Lo'ihi. With the farthest distance between stations being just over 30 km, the stations provide a fairly dense coverage mainly for the northern half of the volcano. Following the approach of Masterlark et al. [2010], we computed vertical-vertical and vertical-radial cross-correlations using 97 days of continuous data from the 12 stations to produce the ambient noise Green's functions. From these, dispersion curves were produced over a frequency range from .04 Hz to 0.65 Hz . After a quality control analysis, checkerboard tests were used to determine a suitable cell size for the 2D group velocity inversions. The final step is the inversion of the group velocity dispersion curves to create a 3D Vs model. The 3D Vs image produced through this method does not provide clear evidence of a shallow magma chamber; however, when compared to a previous P-wave velocity (Vp) model [Caplan-Auerbach, 2001], a high Vp/Vs ratio is evident especially at depths from 1 km to 5 km, indicating the presence of highly fractured rock.

Estimation of local scale dispersion from local breakthrough curves during a tracer test in a heterogeneous aquifer: the Lagrangian approach.

PubMed

Vanderborght, Jan; Vereecken, Harry

2002-01-01

The local scale dispersion tensor, Dd, is a controlling parameter for the dilution of concentrations in a solute plume that is displaced by groundwater flow in a heterogeneous aquifer. In this paper, we estimate the local scale dispersion from time series or breakthrough curves, BTCs, of Br concentrations that were measured at several points in a fluvial aquifer during a natural gradient tracer test at Krauthausen. Locally measured BTCs were characterized by equivalent convection dispersion parameters: equivalent velocity, v(eq)(x) and expected equivalent dispersivity, [lambda(eq)(x)]. A Lagrangian framework was used to approximately predict these equivalent parameters in terms of the spatial covariance of log(e) transformed conductivity and the local scale dispersion coefficient. The approximate Lagrangian theory illustrates that [lambda(eq)(x)] increases with increasing travel distance and is much larger than the local scale dispersivity, lambda(d). A sensitivity analysis indicates that [lambda(eq)(x)] is predominantly determined by the transverse component of the local scale dispersion and by the correlation scale of the hydraulic conductivity in the transverse to flow direction whereas it is relatively insensitive to the longitudinal component of the local scale dispersion. By comparing predicted [lambda(eq)(x)] for a range of Dd values with [lambda(eq)(x)] obtained from locally measured BTCs, the transverse component of Dd, DdT, was estimated. The estimated transverse local scale dispersivity, lambda(dT) = DdT/U1 (U1 = mean advection velocity) is in the order of 10(1)-10(2) mm, which is relatively large but realistic for the fluvial gravel sediments at Krauthausen.

Asymptotic approximations for pure bending of thin cylindrical shells

NASA Astrophysics Data System (ADS)

Coman, Ciprian D.

2017-08-01

A simplified partial wrinkling scenario for in-plane bending of thin cylindrical shells is explored by using several asymptotic strategies. The eighth-order boundary eigenvalue problem investigated here originates in the Donnel-Mushtari-Vlasov shallow shell theory coupled with a linear membrane pre-bifurcation state. It is shown that the corresponding neutral stability curve is amenable to a detailed asymptotic analysis based on the method of multiple scales. This is further complemented by an alternative WKB approximation that provides comparable information with significantly less effort.

Numerical Simulation of Turbulent Combustion Using Vortex Methods

DTIC Science & Technology

1988-09-27

laminar burning velocity times the flame length measured along the line of maximum reaction rate. Following the burning of the eddy core, the strain...is approximately the same as the flame length at t - 0. In the second stage, and as the eddy starts to roll up, the flame front forms a fold within the...Rp, which is the slope of the curve in Fig. 9, can be approximated by the product of the flame length times the average burning velocity along the

The ground state of the Frenkel-Kontorova model

NASA Astrophysics Data System (ADS)

Babushkin, A. Yu.; Abkaryan, A. K.; Dobronets, B. S.; Krasikov, V. S.; Filonov, A. N.

2016-09-01

The continual approximation of the ground state of the discrete Frenkel-Kontorova model is tested using a symmetric algorithm of numerical simulation. A "kaleidoscope effect" is found, which means that the curves representing the dependences of the relative extension of an N-atom chain vary periodically with increasing N. Stairs of structural transitions for N ≫ 1 are analyzed by the channel selection method with the approximation N = ∞. Images of commensurable and incommensurable structures are constructed. The commensurable-incommensurable phase transitions are stepwise.

Validation of diagnostic tests for depressive disorder in drug-resistant mesial temporal lobe epilepsy.

PubMed

de Lemos Zingano, Bianca; Guarnieri, Ricardo; Diaz, Alexandre Paim; Schwarzbold, Marcelo Liborio; Bicalho, Maria Alice Horta; Claudino, Lucia Sukys; Markowitsch, Hans J; Wolf, Peter; Lin, Katia; Walz, Roger

2015-09-01

This study aimed to evaluate the diagnostic accuracy of the Hamilton Rating Scale for Depression (HRSD), the Beck Depression Inventory (BDI), the Hospital Anxiety and Depression Scale (HADS), and the Hospital Anxiety and Depression Scale-Depression subscale (HADS-D) as diagnostic tests for depressive disorder in drug-resistant mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HS). One hundred three patients with drug-resistant MTLE-HS were enrolled. All patients underwent a neurological examination, interictal and ictal video-electroencephalogram (V-EEG) analyses, and magnetic resonance imaging (MRI). Psychiatric interviews were based on DSM-IV-TR criteria and ILAE Commission of Psychobiology classification as a gold standard; HRSD, BDI, HADS, and HADS-D were used as psychometric diagnostic tests, and receiver operating characteristic (ROC) curves were used to determine the optimal threshold scores. For all the scales, the areas under the curve (AUCs) were approximately 0.8, and they were able to identify depression in this sample. A threshold of ≥9 on the HRSD and a threshold of ≥8 on the HADS-D showed a sensitivity of 70% and specificity of 80%. A threshold of ≥19 on the BDI and HADS-D total showed a sensitivity of 55% and a specificity of approximately 90%. The instruments showed a negative predictive value of approximately 87% and a positive predictive value of approximately 65% for the BDI and HADS total and approximately 60% for the HRSD and HADS-D. HRSD≥9 and HADS-D≥8 had the best balance between sensitivity (approximately 70%) and specificity (approximately 80%). However, with these thresholds, these diagnostic tests do not appear useful in identifying depressive disorder in this population with epilepsy, and their specificity (approximately 80%) and PPV (approximately 55%) were lower than those of the other scales. We believe that the BDI and HADS total are valid diagnostic tests for depressive disorder in patients with MTLE-HS, as both scales showed acceptable (though not high) specificity and PPV for this type of study. Copyright © 2015 Elsevier Inc. All rights reserved.

Least Squares Procedures.

ERIC Educational Resources Information Center

Hester, Yvette

Least squares methods are sophisticated mathematical curve fitting procedures used in all classical parametric methods. The linear least squares approximation is most often associated with finding the "line of best fit" or the regression line. Since all statistical analyses are correlational and all classical parametric methods are least…

Evaluation of an in vitro method for acaricidal effect. Activity of parathion, phosmet and phoxim against Sarcoptes scabiei.

PubMed

Brimer, L; Henriksen, S A; Gyrd-Hansen, N; Rasmussen, F

1993-12-01

An in vitro test to determine the acaricidal effect of organophosphorous insecticides (OP) is described. The effect of parathion, phoxim and phosmet against the pig mange mite Sarcoptes scabiei var. suis was evaluated. The test is based on the migration ability of mites on the surface of agar gels containing the acaricide. The mite activity is expressed as a migration index (MI) and compared with the OP concentration in the agar. Good dose-response data were obtained for all three OPs tested, although the instability of phosmet required special precautions concerning the analysis of the agar. The test was found to be accurate, sensitive, easy to carry out and applicable for routine determinations. However, the test requires that the actual concentrations of the OPs in the gel batches are determined. For the three OPs used analytical methods were developed. While the lower threshold for acaricidal effect in vitro was approximately 1-2 micrograms g-1 for all three OPs tested, a significant difference in the higher concentration range was seen between the dose-response curve for parathion and the curves for phoxim and phosmet. While the latter curves decreased only slightly at concentrations above 3-6 micrograms g-1 (corresponding to MI values around 5-10), the curve for parathion was linear down to an MI value of 1, corresponding to a parathion concentration of approximately 30 micrograms g-1. This discrepancy was ascribed to different rates of uptake through the cuticula due to differences in the lipophilicity of the OPs.

Minor planets and related objects. XIX - Shape and pole orientation of /39/ Laetitia

NASA Technical Reports Server (NTRS)

Sather, R. E.

1976-01-01

Results are reported for analyses of UBV photoelectric photometric data and light curves of the asteroid Laetitia. The pole orientation is determined using a technique for reducing the scatter in the magnitude-phase relation. No significant variations in color are found over the surface, and the light curves are found to indicate topographic elements (peaks, scarps, or depressions) approximately 10 km in radius. It is shown that the light-curve amplitudes as well as the wide scatter in observed magnitude and phase relation can be explained by a triaxial ellipsoidal figure with a dimensional ratio of about 15:9:5. It is concluded that the size, shape, and composition of this asteroid are highly suggestive of a major collisional fragment from a substantially more massive differentiated parent body.

Photoelectric photometry of the RS CVn binary EI Eridani = HD 26337

NASA Technical Reports Server (NTRS)

Hooten, J. T.; Strassmeier, K. G.; Hall, D. S.; Barksdale, W. S., Jr.; Bertoglio, A.

1989-01-01

Differential UBV(RI)sub KC and UBVRI photometry of the RS CVn binary EI Eridani obtained during December 1987 and January 1988 at fourteen different observatories is presented. A combined visual bandpass light curve, corrected for systematic errors of different observatories, utilizes the photometric period of 1,945 days to produce useful results. The analysis shows the visual light curve to have twin maxima, separated by about 0.4 phase, and a full amplitude of approximately 0.06 mag for the period of observation, a smaller amplitude than reported in the past. The decrease in amplitude may be due to a decrease or homogenization of spot coverage. To fit the asymmetrical light curve, a starspot model would have to employ at least two spotted regions separated in longitude.

Estimating Dense Cardiac 3D Motion Using Sparse 2D Tagged MRI Cross-sections*

PubMed Central

Ardekani, Siamak; Gunter, Geoffrey; Jain, Saurabh; Weiss, Robert G.; Miller, Michael I.; Younes, Laurent

2015-01-01

In this work, we describe a new method, an extension of the Large Deformation Diffeomorphic Metric Mapping to estimate three-dimensional deformation of tagged Magnetic Resonance Imaging Data. Our approach relies on performing non-rigid registration of tag planes that were constructed from set of initial reference short axis tag grids to a set of deformed tag curves. We validated our algorithm using in-vivo tagged images of normal mice. The mapping allows us to compute root mean square distance error between simulated tag curves in a set of long axis image planes and the acquired tag curves in the same plane. Average RMS error was 0.31±0.36(SD) mm, which is approximately 2.5 voxels, indicating good matching accuracy. PMID:25571140

Modeling of Continuum Manipulators Using Pythagorean Hodograph Curves.

PubMed

Singh, Inderjeet; Amara, Yacine; Melingui, Achille; Mani Pathak, Pushparaj; Merzouki, Rochdi

2018-05-10

Research on continuum manipulators is increasingly developing in the context of bionic robotics because of their many advantages over conventional rigid manipulators. Due to their soft structure, they have inherent flexibility, which makes it a huge challenge to control them with high performances. Before elaborating a control strategy of such robots, it is essential to reconstruct first the behavior of the robot through development of an approximate behavioral model. This can be kinematic or dynamic depending on the conditions of operation of the robot itself. Kinematically, two types of modeling methods exist to describe the robot behavior; quantitative methods describe a model-based method, and qualitative methods describe a learning-based method. In kinematic modeling of continuum manipulator, the assumption of constant curvature is often considered to simplify the model formulation. In this work, a quantitative modeling method is proposed, based on the Pythagorean hodograph (PH) curves. The aim is to obtain a three-dimensional reconstruction of the shape of the continuum manipulator with variable curvature, allowing the calculation of its inverse kinematic model (IKM). It is noticed that the performances of the PH-based kinematic modeling of continuum manipulators are considerable regarding position accuracy, shape reconstruction, and time/cost of the model calculation, than other kinematic modeling methods, for two cases: free load manipulation and variable load manipulation. This modeling method is applied to the compact bionic handling assistant (CBHA) manipulator for validation. The results are compared with other IKMs developed in case of CBHA manipulator.

A conformal mapping based fractional order approach for sub-optimal tuning of PID controllers with guaranteed dominant pole placement

NASA Astrophysics Data System (ADS)

Saha, Suman; Das, Saptarshi; Das, Shantanu; Gupta, Amitava

2012-09-01

A novel conformal mapping based fractional order (FO) methodology is developed in this paper for tuning existing classical (Integer Order) Proportional Integral Derivative (PID) controllers especially for sluggish and oscillatory second order systems. The conventional pole placement tuning via Linear Quadratic Regulator (LQR) method is extended for open loop oscillatory systems as well. The locations of the open loop zeros of a fractional order PID (FOPID or PIλDμ) controller have been approximated in this paper vis-à-vis a LQR tuned conventional integer order PID controller, to achieve equivalent integer order PID control system. This approach eases the implementation of analog/digital realization of a FOPID controller with its integer order counterpart along with the advantages of fractional order controller preserved. It is shown here in the paper that decrease in the integro-differential operators of the FOPID/PIλDμ controller pushes the open loop zeros of the equivalent PID controller towards greater damping regions which gives a trajectory of the controller zeros and dominant closed loop poles. This trajectory is termed as "M-curve". This phenomena is used to design a two-stage tuning algorithm which reduces the existing PID controller's effort in a significant manner compared to that with a single stage LQR based pole placement method at a desired closed loop damping and frequency.

Muscle contraction during electro-muscular incapacitation: A comparison between square-wave pulses and the TASER(®) X26 Electronic control device.

PubMed

Comeaux, James A; Jauchem, James R; Cox, D Duane; Crane, Carrie C; D'Andrea, John A

2011-01-01

Electronic control devices (including the Advanced TASER(®) X26 model produced by TASER International) incapacitate individuals by causing muscle contractions. To provide information relevant to development of future potential devices, effects of monophasic square waves with different parameters were compared with those of the X26 electronic control device, using two animal models (frogs and swine). Pulse power, electrical pulse charge, pulse duration, and pulse repetition frequency affected muscle contraction. There was no difference in the charge required, between the square waveform and the X26 waveform, to cause approximately the same muscle-contraction response (in terms of the strength-duration curve). Thus, on the basis of these initial studies, the detailed shape of a waveform may not be important in terms of generating electro-muscular incapacitation. More detailed studies, however, may be required to thoroughly test all potential waveforms to be considered for future use in ECDs. 2010 American Academy of Forensic Sciences. Published 2010. This article is a U.S. Government work and is in the public domain in the U.S.A.

Evaluation of fiber Bragg grating sensor interrogation using InGaAs linear detector arrays and Gaussian approximation on embedded hardware.

PubMed

Kumar, Saurabh; Amrutur, Bharadwaj; Asokan, Sundarrajan

2018-02-01

Fiber Bragg Grating (FBG) sensors have become popular for applications related to structural health monitoring, biomedical engineering, and robotics. However, for successful large scale adoption, FBG interrogation systems are as important as sensor characteristics. Apart from accuracy, the required number of FBG sensors per fiber and the distance between the device in which the sensors are used and the interrogation system also influence the selection of the interrogation technique. For several measurement devices developed for applications in biomedical engineering and robotics, only a few sensors per fiber are required and the device is close to the interrogation system. For these applications, interrogation systems based on InGaAs linear detector arrays provide a good choice. However, their resolution is dependent on the algorithms used for curve fitting. In this work, a detailed analysis of the choice of algorithm using the Gaussian approximation for the FBG spectrum and the number of pixels used for curve fitting on the errors is provided. The points where the maximum errors occur have been identified. All comparisons for wavelength shift detection have been made against another interrogation system based on the tunable swept laser. It has been shown that maximum errors occur when the wavelength shift is such that one new pixel is included for curve fitting. It has also been shown that an algorithm with lower computation cost compared to the more popular methods using iterative non-linear least squares estimation can be used without leading to the loss of accuracy. The algorithm has been implemented on embedded hardware, and a speed-up of approximately six times has been observed.

Evaluation of fiber Bragg grating sensor interrogation using InGaAs linear detector arrays and Gaussian approximation on embedded hardware

NASA Astrophysics Data System (ADS)

Kumar, Saurabh; Amrutur, Bharadwaj; Asokan, Sundarrajan

2018-02-01

Fiber Bragg Grating (FBG) sensors have become popular for applications related to structural health monitoring, biomedical engineering, and robotics. However, for successful large scale adoption, FBG interrogation systems are as important as sensor characteristics. Apart from accuracy, the required number of FBG sensors per fiber and the distance between the device in which the sensors are used and the interrogation system also influence the selection of the interrogation technique. For several measurement devices developed for applications in biomedical engineering and robotics, only a few sensors per fiber are required and the device is close to the interrogation system. For these applications, interrogation systems based on InGaAs linear detector arrays provide a good choice. However, their resolution is dependent on the algorithms used for curve fitting. In this work, a detailed analysis of the choice of algorithm using the Gaussian approximation for the FBG spectrum and the number of pixels used for curve fitting on the errors is provided. The points where the maximum errors occur have been identified. All comparisons for wavelength shift detection have been made against another interrogation system based on the tunable swept laser. It has been shown that maximum errors occur when the wavelength shift is such that one new pixel is included for curve fitting. It has also been shown that an algorithm with lower computation cost compared to the more popular methods using iterative non-linear least squares estimation can be used without leading to the loss of accuracy. The algorithm has been implemented on embedded hardware, and a speed-up of approximately six times has been observed.

High temperature, low-cycle fatigue of copper-base alloys for rocket nozzles. Part 2: Strainrange partitioning and low-cycle fatigue results at 538 deg C

NASA Technical Reports Server (NTRS)

Conway, J. B.; Stentz, R. H.; Berling, J. T.

1976-01-01

Low-cycle fatigue tests of 1/2 Hard AMZIRC Copper and NARloy Z were performed in argon at 538 C to determine partitioned strain range versus life relationships. Strain-controlled low-cycle fatigue tests of a Zr-Cr-Mg copper-base alloy were also performed. Strain ranges, lower than those employed in previous tests, were imposed in order to extend the fatigue life curve out to approximately 400,000 cycles. An experimental copper alloy and an experimental silver alloy were also studied. Tensile tests were performed in air at room temperature and in argon at 538 C. Strain-controlled low-cycle fatigue tests were performed at 538 C in argon to define the fatigue life over the regime from 300 to 3,000 cycles. For the silver alloy, three additional heat treatments were introduced, and a limited evaluation of the short-term tensile and low-cycle fatigue behavior at 538 C was performed.

An Analysis of the Time Course of Lexical Processing During Reading.

PubMed

Sheridan, Heather; Reichle, Erik D

2016-04-01

Reingold, Reichle, Glaholt, and Sheridan (2012) reported a gaze-contingent eye-movement experiment in which survival-curve analyses were used to examine the effects of word frequency, the availability of parafoveal preview, and initial fixation location on the time course of lexical processing. The key results of these analyses suggest that lexical processing begins very rapidly (after approximately 120 ms) and is supported by substantial parafoveal processing (more than 100 ms). Because it is not immediately obvious that these results are congruent with the theoretical assumption that words are processed and identified in a strictly serial manner, we attempted to simulate the experiment using the E-Z Reader model of eye-movement control (Reichle, 2011). These simulations were largely consistent with the empirical results, suggesting that parafoveal processing does play an important functional role by allowing lexical processing to occur rapidly enough to mediate direct control over when the eyes move during reading. Copyright © 2015 Cognitive Science Society, Inc.

Properties of gamma-ray burst progenitor stars.

PubMed

Kumar, Pawan; Narayan, Ramesh; Johnson, Jarrett L

2008-07-18

We determined some basic properties of stars that produce spectacular gamma-ray bursts at the end of their lives. We assumed that accretion of the outer portion of the stellar core by a central black hole fuels the prompt emission and that fall-back and accretion of the stellar envelope later produce the plateau in the x-ray light curve seen in some bursts. Using x-ray data for three bursts, we estimated the radius of the stellar core to be approximately (1 - 3) x 10(10) cm and that of the stellar envelope to be approximately (1 - 2) x 10(11) cm. The density profile in the envelope is fairly shallow, with rho approximately r(-2) (where rho is density and r is distance from the center of the explosion). The rotation speeds of the core and envelope are approximately 0.05 and approximately 0.2 of the local Keplerian speed, respectively.

NMR signal analysis to characterize solid, aqueous, and lipid phases in baked cakes.

PubMed

Le Grand, F; Cambert, M; Mariette, F

2007-12-26

Proton mobility was studied in molecular fractions of some model systems and of cake using a 1H nuclear magnetic resonance (NMR) relaxation technique. For cake, five spin-spin relaxation times (T2) were obtained from transverse relaxation curves: T2 (1) approximately 20 micros, T2 (2) approximately 0.2 ms, T2 (3) approximately 3 ms, T2 (4) approximately 50 ms, and T2 (2) approximately 165 ms. The faster component was attributed to the solid phase, components 2 and 3 were associated with the aqueous phase, and the two slowest components were linked to the lipid phase. After cooking, the crust contained more fat but less water than the center part of the cake. The amount of gelatinized starch was lower in the crust, and water was more mobile due to less interaction with macromolecules. This preliminary study revealed different effects of storage on the center and crust.

Use of HyperCard to Simulate a Tissue Culture Laboratory.

ERIC Educational Resources Information Center

Nester, Bradley S.; Turney, Tully H.

1992-01-01

Describes the use of a Macintosh computer and HyperCard software to create an introduction to cell culture techniques that closely approximates a hands-on laboratory experiment. Highlights include data acquisition, data analysis, the generation of growth curves, and electronic modeling. (LRW)

Antibacterial Efficacy of a New Sonic Irrigation Device for Root Canal Disinfection.

PubMed

Neuhaus, Klaus W; Liebi, Melanie; Stauffacher, Simone; Eick, Sigrun; Lussi, Adrian

2016-12-01

Passive ultrasonic irrigation (PUI) is the most widespread method used to activate irrigation solutions. Concerns have been raised that PUI is less effective in curved root canals and is not passive at all. Our aim was to compare a novel passive sonic irrigation (PSI) device (6000 Hz) with PUI and manual irrigation (MI) with respect to their efficiency in removing different endodontic microorganisms from curved and straight root canals. We performed 2 experiments as follows. In a 3-day infection model, we included 8 groups of single or dual microbial species that were rinsed with 0.9% sodium chloride using PSI, PUI, or MI. Colony-forming units (CFUs) were counted after incubation, and log 10 transformations were performed for statistical comparisons. In a 21-d infection model, we tested the same irrigation protocols on 4 groups of microorganisms and used 1.5% sodium hypochlorite as an irrigant. Infection control samples were taken at day 0, 3, 5, and 7 after treatment and were subsequently reincubated. Using sodium chloride as an irrigant, the amount of reduction in CFUs compared with the negative control was approximately 3 log 10 units for PSI at 6000 Hz, 2 log 10 units for PUI, and 1 log 10 unit for MI. PSI reduced the microorganism CFUs significantly better than PUI. Using sodium hypochlorite led to a significant reduction in microorganism CFUs even with MI. After 3 days, compared with MI, microorganism regrowth significantly reduced after PSI and PUI treatment, but in these groups, in at least half of the samples, microorganisms were detectable after 7 days. PSI at 6000 Hz might be at least equal to PUI with respect to reduction of the microbial load in curved and straight root canals. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

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

Wintermeyer, Niklas; Winters, Andrew R., E-mail: awinters@math.uni-koeln.de; Gassner, Gregor J.

We design an arbitrary high-order accurate nodal discontinuous Galerkin spectral element approximation for the non-linear two dimensional shallow water equations with non-constant, possibly discontinuous, bathymetry on unstructured, possibly curved, quadrilateral meshes. The scheme is derived from an equivalent flux differencing formulation of the split form of the equations. We prove that this discretization exactly preserves the local mass and momentum. Furthermore, combined with a special numerical interface flux function, the method exactly preserves the mathematical entropy, which is the total energy for the shallow water equations. By adding a specific form of interface dissipation to the baseline entropy conserving schememore » we create a provably entropy stable scheme. That is, the numerical scheme discretely satisfies the second law of thermodynamics. Finally, with a particular discretization of the bathymetry source term we prove that the numerical approximation is well-balanced. We provide numerical examples that verify the theoretical findings and furthermore provide an application of the scheme for a partial break of a curved dam test problem.« less

Numerical Investigation of the Microscopic Heat Current Inside a Nanofluid System Based on Molecular Dynamics Simulation and Wavelet Analysis.

PubMed

Jia, Tao; Gao, Di

2018-04-03

Molecular dynamics simulation is employed to investigate the microscopic heat current inside an argon-copper nanofluid. Wavelet analysis of the microscopic heat current inside the nanofluid system is conducted. The signal of the microscopic heat current is decomposed into two parts: one is the approximation part; the other is the detail part. The approximation part is associated with the low-frequency part of the signal, and the detail part is associated with the high-frequency part of the signal. Both the probability distributions of the high-frequency and the low-frequency parts of the signals demonstrate Gaussian-like characteristics. The curves fit to data of the probability distribution of the microscopic heat current are established, and the parameters including the mean value and the standard deviation in the mathematical formulas of the curves show dramatic changes for the cases before and after adding copper nanoparticles into the argon base fluid.

Prior-knowledge-based feedforward network simulation of true boiling point curve of crude oil.

PubMed

Chen, C W; Chen, D Z

2001-11-01

Theoretical results and practical experience indicate that feedforward networks can approximate a wide class of functional relationships very well. This property is exploited in modeling chemical processes. Given finite and noisy training data, it is important to encode the prior knowledge in neural networks to improve the fit precision and the prediction ability of the model. In this paper, as to the three-layer feedforward networks and the monotonic constraint, the unconstrained method, Joerding's penalty function method, the interpolation method, and the constrained optimization method are analyzed first. Then two novel methods, the exponential weight method and the adaptive method, are proposed. These methods are applied in simulating the true boiling point curve of a crude oil with the condition of increasing monotonicity. The simulation experimental results show that the network models trained by the novel methods are good at approximating the actual process. Finally, all these methods are discussed and compared with each other.

Influence of the starting temperature of calorimetric measurements on the accuracy of determined magnetocaloric effect

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

Moreno-Ramirez, L. M.; Franco, V.; Conde, A.

Availability of a restricted heat capacity data range has a clear influence on the accuracy of calculated magnetocaloric effect, as confirmed by both numerical simulations and experimental measurements. Simulations using the Bean-Rodbell model show that, in general, the approximated magnetocaloric effect curves calculated using a linear extrapolation of the data starting from a selected temperature point down to zero kelvin deviate in a non-monotonic way from those correctly calculated by fully integrating the data from near zero temperatures. However, we discovered that a particular temperature range exists where the approximated magnetocaloric calculation provides the same result as the fully integratedmore » one. These specific truncated intervals exist for both first and second order phase transitions and are the same for the adiabatic temperature change and magnetic entropy change curves. Here, the effect of this truncated integration in real samples was confirmed using heat capacity data of Gd metal and Gd 5Si 2Ge 2 compound measured from near zero temperatures.« less

Learning the ideal observer for SKE detection tasks by use of convolutional neural networks (Cum Laude Poster Award)

NASA Astrophysics Data System (ADS)

Zhou, Weimin; Anastasio, Mark A.

2018-03-01

It has been advocated that task-based measures of image quality (IQ) should be employed to evaluate and optimize imaging systems. Task-based measures of IQ quantify the performance of an observer on a medically relevant task. The Bayesian Ideal Observer (IO), which employs complete statistical information of the object and noise, achieves the upper limit of the performance for a binary signal classification task. However, computing the IO performance is generally analytically intractable and can be computationally burdensome when Markov-chain Monte Carlo (MCMC) techniques are employed. In this paper, supervised learning with convolutional neural networks (CNNs) is employed to approximate the IO test statistics for a signal-known-exactly and background-known-exactly (SKE/BKE) binary detection task. The receiver operating characteristic (ROC) curve and the area under the ROC curve (AUC) are compared to those produced by the analytically computed IO. The advantages of the proposed supervised learning approach for approximating the IO are demonstrated.

Human behavioral complexity peaks at age 25

PubMed Central

Brugger, Peter

2017-01-01

Random Item Generation tasks (RIG) are commonly used to assess high cognitive abilities such as inhibition or sustained attention. They also draw upon our approximate sense of complexity. A detrimental effect of aging on pseudo-random productions has been demonstrated for some tasks, but little is as yet known about the developmental curve of cognitive complexity over the lifespan. We investigate the complexity trajectory across the lifespan of human responses to five common RIG tasks, using a large sample (n = 3429). Our main finding is that the developmental curve of the estimated algorithmic complexity of responses is similar to what may be expected of a measure of higher cognitive abilities, with a performance peak around 25 and a decline starting around 60, suggesting that RIG tasks yield good estimates of such cognitive abilities. Our study illustrates that very short strings of, i.e., 10 items, are sufficient to have their complexity reliably estimated and to allow the documentation of an age-dependent decline in the approximate sense of complexity. PMID:28406953

A Deterministic Interfacial Cyclic Oxidation Spalling Model. Part 2; Algebraic Approximation, Descriptive Parameters, and Normalized Universal Curve

NASA Technical Reports Server (NTRS)

Smialek, James L.

2002-01-01

A cyclic oxidation interfacial spalling model has been developed in Part 1. The governing equations have been simplified here by substituting a new algebraic expression for the series (Good-Smialek approximation). This produced a direct relationship between cyclic oxidation weight change and model input parameters. It also allowed for the mathematical derivation of various descriptive parameters as a function of the inputs. It is shown that the maximum in weight change varies directly with the parabolic rate constant and cycle duration and inversely with the spall fraction, all to the 1/2 power. The number of cycles to reach maximum and zero weight change vary inversely with the spall fraction, and the ratio of these cycles is exactly 1:3 for most oxides. By suitably normalizing the weight change and cycle number, it is shown that all cyclic oxidation weight change model curves can be represented by one universal expression for a given oxide scale.

Influence of the starting temperature of calorimetric measurements on the accuracy of determined magnetocaloric effect

DOE PAGES

Moreno-Ramirez, L. M.; Franco, V.; Conde, A.; ...

2018-02-27

Availability of a restricted heat capacity data range has a clear influence on the accuracy of calculated magnetocaloric effect, as confirmed by both numerical simulations and experimental measurements. Simulations using the Bean-Rodbell model show that, in general, the approximated magnetocaloric effect curves calculated using a linear extrapolation of the data starting from a selected temperature point down to zero kelvin deviate in a non-monotonic way from those correctly calculated by fully integrating the data from near zero temperatures. However, we discovered that a particular temperature range exists where the approximated magnetocaloric calculation provides the same result as the fully integratedmore » one. These specific truncated intervals exist for both first and second order phase transitions and are the same for the adiabatic temperature change and magnetic entropy change curves. Here, the effect of this truncated integration in real samples was confirmed using heat capacity data of Gd metal and Gd 5Si 2Ge 2 compound measured from near zero temperatures.« less

Method for characterization of a spherically bent crystal for K.alpha. X-ray imaging of laser plasmas using a focusing monochromator geometry

DOEpatents

Kugland, Nathan; Doeppner, Tilo; Glenzer, Siegfried; Constantin, Carmen; Niemann, Chris; Neumayer, Paul

2015-04-07

A method is provided for characterizing spectrometric properties (e.g., peak reflectivity, reflection curve width, and Bragg angle offset) of the K.alpha. emission line reflected narrowly off angle of the direct reflection of a bent crystal and in particular of a spherically bent quartz 200 crystal by analyzing the off-angle x-ray emission from a stronger emission line reflected at angles far from normal incidence. The bent quartz crystal can therefore accurately image argon K.alpha. x-rays at near-normal incidence (Bragg angle of approximately 81 degrees). The method is useful for in-situ calibration of instruments employing the crystal as a grating by first operating the crystal as a high throughput focusing monochromator on the Rowland circle at angles far from normal incidence (Bragg angle approximately 68 degrees) to make a reflection curve with the He-like x-rays such as the He-.alpha. emission line observed from a laser-excited plasma.

A New Development in the Method of Measurement of Reciprocity-Law Failure and Its Application to Screen/Green-Sensitive X-Ray Film Systems

NASA Astrophysics Data System (ADS)

Fujita, Hiroshi; Uchida, Suguru

1981-01-01

Since it has been confirmed by experiment that the intensity of X-rays varies approximately as the focus-film distance (FFD) to the minus 2.12th power, the X-ray intensity can be changed by varying the FFD. It is shown in this paper that two types of reciprocity failure curve, density vs. exposure time for constant exposure and relative exposure vs. exposure time for constant density, can easily be obtained from several time-scale characteristic curves taken experimentally for several FFD’s in the rare-earth screen-film systems used. Only low-intensity reciprocity failure is present for exposure times of more than about 0.1 sec for one film, but both low-intensity and high-intensity reciprocity failures occur in the other one. The effects of reciprocity failure on the H & D curves can be seen in the shape of the curves and the relative speed.

Melting Behavior of a Model Molecular Crystalline GeI4

NASA Astrophysics Data System (ADS)

Fuchizaki, Kazuhiro; Asano, Yuta

2015-06-01

A model molecular crystalline GeI4 was examined using molecular dynamics simulation. The model was constructed in such a way that rigid tetrahedral molecules interact with each other via Lennard-Jones potentials whose centers are located at the vertices of a tetrahedron. Because no other interaction that can "soften" the intermolecular interaction was introduced, the melting curve of the model crystalline material does not exhibit the anomaly that was found for the real substance. However, the current investigation is useful in that it could settle the upper bound of pressure below which the model can predict properties of the molecular liquid. Moreover, singularity-free nature of the melting curve allowed us to analytically treat the melting curve in the light of the Kumari-Dass-Kechin equation. As a result, we could definitely conclude that the well-known Simon equation for the melting curve is merely an approximate expression. The condition for the validity of Simon's equation was identified.

Ray-theory approach to electrical-double-layer interactions.

PubMed

Schnitzer, Ory

2015-02-01

A novel approach is presented for analyzing the double-layer interaction force between charged particles in electrolyte solution, in the limit where the Debye length is small compared with both interparticle separation and particle size. The method, developed here for two planar convex particles of otherwise arbitrary geometry, yields a simple asymptotic approximation limited to neither small zeta potentials nor the "close-proximity" assumption underlying Derjaguin's approximation. Starting from the nonlinear Poisson-Boltzmann formulation, boundary-layer solutions describing the thin diffuse-charge layers are asymptotically matched to a WKBJ expansion valid in the bulk, where the potential is exponentially small. The latter expansion describes the bulk potential as superposed contributions conveyed by "rays" emanating normally from the boundary layers. On a special curve generated by the centers of all circles maximally inscribed between the two particles, the bulk stress-associated with the ray contributions interacting nonlinearly-decays exponentially with distance from the center of the smallest of these circles. The force is then obtained by integrating the traction along this curve using Laplace's method. We illustrate the usefulness of our theory by comparing it, alongside Derjaguin's approximation, with numerical simulations in the case of two parallel cylinders at low potentials. By combining our result and Derjaguin's approximation, the interaction force is provided at arbitrary interparticle separations. Our theory can be generalized to arbitrary three-dimensional geometries, nonideal electrolyte models, and other physical scenarios where exponentially decaying fields give rise to forces.

Is the learning curve endless? One surgeon's experience with robotic prostatectomy

NASA Astrophysics Data System (ADS)

Patel, Vipul; Thaly, Rahul; Shah, Ketul

2007-02-01

Introduction: After performing 1,000 robotic prostatectomies we reflected back on our experience to determine what defined the learning curve and the essential elements that were the keys to surmounting it. Method: We retrospectively assessed our experience to attempt to define the learning curve(s), key elements of the procedure, technical refinements and changes in technology that facilitated our progress. Result: The initial learning curve to achieve basic competence and the ability to smoothly perform the procedure in less than 4 hours with acceptable outcomes was approximately 25 cases. A second learning curve was present between 75-100 cases as we approached more complicated patients. At 200 cases we were comfortably able to complete the procedure routinely in less than 2.5 hours with no specific step of the procedure hindering our progression. At 500 cases we had the introduction of new instrumentation (4th arm, biopolar Maryland, monopolar scissors) that changed our approach to the bladder neck and neurovascular bundle dissection. The most challenging part of the procedure was the bladder neck dissection. Conclusion: There is no single parameter that can be used to assess or define the learning curve. We used a combination of factors to make our subjective definition this included: operative time, smoothness of technical progression during the case along with clinical outcomes. The further our case experience progressed the more we expected of our outcomes, thus we continually modified our technique and hence embarked upon yet a new learning curve.

Scoliosis convexity and organ anatomy are related.

PubMed

Schlösser, Tom P C; Semple, Tom; Carr, Siobhán B; Padley, Simon; Loebinger, Michael R; Hogg, Claire; Castelein, René M

2017-06-01

Primary ciliary dyskinesia (PCD) is a respiratory syndrome in which 'random' organ orientation can occur; with approximately 46% of patients developing situs inversus totalis at organogenesis. The aim of this study was to explore the relationship between organ anatomy and curve convexity by studying the prevalence and convexity of idiopathic scoliosis in PCD patients with and without situs inversus. Chest radiographs of PCD patients were systematically screened for existence of significant lateral spinal deviation using the Cobb angle. Positive values represented right-sided convexity. Curve convexity and Cobb angles were compared between PCD patients with situs inversus and normal anatomy. A total of 198 PCD patients were screened. The prevalence of scoliosis (Cobb >10°) and significant spinal asymmetry (Cobb 5-10°) was 8 and 23%, respectively. Curve convexity and Cobb angle were significantly different within both groups between situs inversus patients and patients with normal anatomy (P ≤ 0.009). Moreover, curve convexity correlated significantly with organ orientation (P < 0.001; ϕ = 0.882): In 16 PCD patients with scoliosis (8 situs inversus and 8 normal anatomy), except for one case, matching of curve convexity and orientation of organ anatomy was observed: convexity of the curve was opposite to organ orientation. This study supports our hypothesis on the correlation between organ anatomy and curve convexity in scoliosis: the convexity of the thoracic curve is predominantly to the right in PCD patients that were 'randomized' to normal organ anatomy and to the left in patients with situs inversus totalis.

The feedback control research on straight and curved road with car-following model

NASA Astrophysics Data System (ADS)

Zheng, Yi-Ming; Cheng, Rong-Jun; Ge, Hong-Xia

2017-07-01

Taking account of the road consisting of curved part and straight part, an extended car-following model is proposed in this paper. A control signal including the velocity difference between the considered vehicle and the vehicle in front is taken into account. The control theory method is applied into analysis of the stability condition for the model. Numerical simulations are implemented to prove that the stability of the traffic flow strengthens effectively with an increase of the radius of curved road, and the control signal can suppress the traffic congestion. The results are in good agree with the theoretical analysis.

Power of tests for comparing trend curves with application to national immunization survey (NIS).

PubMed

Zhao, Zhen

2011-02-28

To develop statistical tests for comparing trend curves of study outcomes between two socio-demographic strata across consecutive time points, and compare statistical power of the proposed tests under different trend curves data, three statistical tests were proposed. For large sample size with independent normal assumption among strata and across consecutive time points, the Z and Chi-square test statistics were developed, which are functions of outcome estimates and the standard errors at each of the study time points for the two strata. For small sample size with independent normal assumption, the F-test statistic was generated, which is a function of sample size of the two strata and estimated parameters across study period. If two trend curves are approximately parallel, the power of Z-test is consistently higher than that of both Chi-square and F-test. If two trend curves cross at low interaction, the power of Z-test is higher than or equal to the power of both Chi-square and F-test; however, at high interaction, the powers of Chi-square and F-test are higher than that of Z-test. The measurement of interaction of two trend curves was defined. These tests were applied to the comparison of trend curves of vaccination coverage estimates of standard vaccine series with National Immunization Survey (NIS) 2000-2007 data. Copyright © 2011 John Wiley & Sons, Ltd.

Physical characteristics of faint meteors by light curve and high-resolution observations, and the implications for parent bodies

NASA Astrophysics Data System (ADS)

Subasinghe, Dilini; Campbell-Brown, Margaret D.; Stokan, Edward

2016-04-01

Optical observations of faint meteors (10-7 < mass < 10-4 kg) were collected by the Canadian Automated Meteor Observatory between 2010 April and 2014 May. These high-resolution (metre scale) observations were combined with two-station light-curve observations and the meteoroid orbit to classify meteors and attempt to answer questions related to meteoroid fragmentation, strength, and light-curve shape. The F parameter was used to classify the meteor light-curve shape; the observed morphology was used to classify the fragmentation mode; and the Tisserand parameter described the origin of the meteoroid. We find that most meteor light curves are symmetric (mean F parameter 0.49), show long distinct trails (continuous fragmentation), and are cometary in origin. Meteors that show no obvious fragmentation (presumably single body objects) show mostly symmetric light curves, surprisingly, and this indicates that light-curve shape is not an indication of fragility or fragmentation behaviour. Approximately 90 per cent of meteors observed with high-resolution video cameras show some form of fragmentation. Our results also show, unexpectedly, that meteors which show negligible fragmentation are more often on high-inclination orbits (I > 60°) than low-inclination ones. We also find that dynamically asteroidal meteors fragment as often as dynamically cometary meteors, which may suggest mixing in the early Solar system, or contamination between the dynamic groups.

Methods and computer program documentation for determining anisotropic transmissivity tensor components of two-dimensional ground-water flow

USGS Publications Warehouse

Maslia, M.L.; Randolph, R.B.

1986-01-01

The theory of anisotropic aquifer hydraulic properties and a computer program, written in Fortran 77, developed to compute the components of the anisotropic transmissivity tensor of two-dimensional groundwater flow are described. To determine the tensor components using one pumping well and three observation wells, the type-curve and straight-line approximation methods are developed. These methods are based on the equation of drawdown developed for two-dimensional nonsteady flow in an infinite anisotropic aquifer. To determine tensor components using more than three observation wells, a weighted least squares optimization procedure is described for use with the type-curve and straight-line approximation methods. The computer program described in this report allows the type-curve, straight-line approximation, and weighted least squares optimization methods to be used in conjunction with data from observation and pumping wells. Three example applications using the computer program and field data gathered during geohydrologic investigations at a site near Dawsonville, Georgia , are provided to illustrate the use of the computer program. The example applications demonstrate the use of the type-curve method using three observation wells, the weighted least squares optimization method using eight observation wells and equal weighting, and the weighted least squares optimization method using eight observation wells and unequal weighting. Results obtained using the computer program indicate major transmissivity in the range of 347-296 sq ft/day, minor transmissivity in the range of 139-99 sq ft/day, aquifer anisotropy in the range of 3.54 to 2.14, principal direction of flow in the range of N. 45.9 degrees E. to N. 58.7 degrees E., and storage coefficient in the range of 0.0063 to 0.0037. The numerical results are in good agreement with field data gathered on the weathered crystalline rocks underlying the investigation site. Supplemental material provides definitions of variables, data requirements and corresponding formats, input data and output results for the example applications, and a listing of the Fortran 77 computer code. (Author 's abstract)

Forced expirations and maximum expiratory flow-volume curves during sustained microgravity on SLS-1.

PubMed

Elliott, A R; Prisk, G K; Guy, H J; Kosonen, J M; West, J B

1996-07-01

Gravity is known to influence the mechanical behavior of the lung and chest wall. However, the effect of sustained microgravity (microG) on forced expirations has not previously been reported. Tests were carried out by four subjects in both the standing and supine postures during each of seven preflight and four postflight data-collection sessions and four times during the 9 days of microG exposure on Spacelab Life Sciences-1. Compared with preflight standing values, peak expiratory flow rate (PEFR) was significantly reduced by 12.5% on flight day 2 (FD2), 11.6% on FD4, and 5.0% on FD5 but returned to standing values by FD9. The supine posture caused a 9% reduction in PEFR. Forced vital capacity and forced expired volume in 1 s were slightly reduced (approximately 3-4%) on FD2 but returned to preflight standing values on FD4 and FD5, and by FD9 both values were slightly but significantly greater than standing values. Forced vital capacity and forced expiratory volume in 1 s were both reduced in the supine posture (approximately 8-10%). Forced expiratory flows at 50% and between 25 and 75% of vital capacity did not change during microG but were reduced in the supine posture. Analysis of the maximum expiratory flow-volume curve showed that microG caused no consistent change in the curve configuration when individual in-flight days were compared with preflight standing curves, although two subjects did show a slight reduction in flows at low lung volumes from FD2 to FD9. The interpretation of the lack of change in curve configuration must be made cautiously because the lung volumes varied from day to day in flight. Therefore, the flows at absolute lung volumes in microG and preflight standing are not being compared. The supine curves showed a subtle but consistent reduction in flows at low lung volumes. The mechanism responsible for the reduction in PEFR is not clear. It could be due to a lack of physical stabilization when performing the maneuver in the absence of gravity or a transient reduction in respiratory muscle strength.

High-pressure melting of molybdenum.

PubMed

Belonoshko, A B; Simak, S I; Kochetov, A E; Johansson, B; Burakovsky, L; Preston, D L

2004-05-14

The melting curve of the body-centered cubic (bcc) phase of Mo has been determined for a wide pressure range using both direct ab initio molecular dynamics simulations of melting as well as a phenomenological theory of melting. These two methods show very good agreement. The simulations are based on density functional theory within the generalized gradient approximation. Our calculated equation of state of bcc Mo is in excellent agreement with experimental data. However, our melting curve is substantially higher than the one determined in diamond anvil cell experiments up to a pressure of 100 GPa. An explanation is suggested for this discrepancy.

On the compressible Taylor?Couette problem

NASA Astrophysics Data System (ADS)

Manela, A.; Frankel, I.

We consider the linear temporal stability of a Couette flow of a Maxwell gas within the gap between a rotating inner cylinder and a concentric stationary outer cylinder both maintained at the same temperature. The neutral curve is obtained for arbitrary Mach (Ma) and arbitrarily small Knudsen (Kn) numbers by use of a continuum model and is verified via comparison to direct simulation Monte Carlo results. At subsonic rotation speeds we find, for the radial ratios considered here, that the neutral curve nearly coincides with the constant-Reynolds-number curve pertaining to the critical value for the onset of instability in the corresponding incompressible-flow problem. With increasing Mach number, transition is deferred to larger Reynolds numbers. It is remarkable that for a fixed Reynolds number, instability is always eventually suppressed beyond some supersonic rotation speed. To clarify this we examine the variation with increasing (Ma) of the reference Couette flow and analyse the narrow-gap limit of the compressible TC problem. The results of these suggest that, as in the incompressible problem, the onset of instability at supersonic speeds is still essentially determined through the balance of inertial and viscous-dissipative effects. Suppression of instability is brought about by increased rates of dissipation associated with the elevated bulk-fluid temperatures occurring at supersonic speeds. A useful approximation is obtained for the neutral curve throughout the entire range of Mach numbers by an adaptation of the familiar incompressible stability criteria with the critical Reynolds (or Taylor) numbers now based on average fluid properties. The narrow-gap analysis further indicates that the resulting approximate neutral curve obtained in the (Ma, Kn) plane consists of two branches: (i) the subsonic part corresponding to a constant ratio (Ma/Kn) (i.e. a constant critical Reynolds number) and (ii) a supersonic branch which at large Ma values corresponds to a constant product Ma Kn. Finally, our analysis helps to resolve some conflicting views in the literature regarding apparently destabilizing compressibility effects.

Pluto's Atmosphere, Then and Now

NASA Astrophysics Data System (ADS)

Elliot, J. L.; Buie, M.; Person, M. J.; Qu, S.

2002-09-01

The KAO light curve for the 1988 stellar occultation by Pluto exhibits a sharp drop just below half light, but above this level the light curve is consistent with that of an isothermal atmosphere (T = 105 +/- 8 K, with N2 as its major constituent). The sharp drop in the light curve has been interpreted as being caused by: (i) a haze layer, (ii) a large thermal gradient, or (iii) some combination of these two. Modeling Pluto's atmosphere with a haze layer yields a normal optical depth >= 0.145 (Elliot & Young 1992, AJ 103, 991). On the other hand, if Pluto's atmosphere is assumed to be clear, the occultation light curve can be inverted with a new method that avoids the large-body approximations. Inversion of the KAO light curve with this method yields an upper isothermal part, followed by a sharp thermal gradient that reaches a maximum magnitude of -3.9 +/- 0.6 K km-1 at the end of the inversion (r = 1206 +/- 10 km). Even though we do not yet understand the cause of the sharp drop, the KAO light curve can be used as a benchmark for examining subsequent Pluto occultation light curves to determine whether Pluto's atmospheric structure has changed since 1988. As an example, the Mamiña light curve for the 2002 July 20 Pluto occultation of P126A was compared with the KAO light curve by Buie et al. (this conference), who concluded that Pluto's atmospheric structure has changed significantly since 1988. Further analysis and additional light curves from this and subsequent occultations (e.g. 2002 August 21) will allow us to elucidate the nature of these changes. This work was supported, in part, by grants from NASA (NAG5-9008 and NAG5-10444) and NSF (AST-0073447).

Diffraction and imaging study of imperfections of crystallized lysozyme with coherent X-rays

NASA Technical Reports Server (NTRS)

Hu, Z. W.; Chu, Y. S.; Lai, B.; Thomas, B. R.; Chernov, A. A.

2004-01-01

Phase-contrast X-ray diffraction imaging and high-angular-resolution diffraction combined with phase-contrast radiographic imaging were employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in the symmetric Laue case. The full-width at half-maximum (FWHM) of a 4 4 0 rocking curve measured from the original crystal was approximately 16.7 arcsec and imperfections including line defects, inclusions and other microdefects were observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the <1 1 0> growth front and have been found to originate mostly in a central growth area and occasionally in outer growth regions. Inclusions of impurities or formations of foreign particles in the central growth region are resolved in the images with high sensitivity to defects. Slow dehydration led to the broadening of a fairly symmetric 4 4 0 rocking curve by a factor of approximately 2.6, which was primarily attributed to the dehydration-induced microscopic effects that are clearly shown in X-ray diffraction images. The details of the observed defects and the significant change in the revealed microstructures with drying provide insight into the nature of imperfections, nucleation and growth, and the properties of protein crystals.

X-Ray Diffraction and Imaging Study of Imperfections of Crystallized Lysozyme with Coherent X-Rays

NASA Technical Reports Server (NTRS)

Hu, Zheng-Wei; Chu, Y. S.; Lai, B.; Cai, Z.; Thomas, B. R.; Chernov, A. A.

2003-01-01

Phase-sensitive x-ray diffraction imaging and high angular-resolution diffraction combined with phase contrast radiographic imaging are employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in symmetric Laue case. The fill width at half-maximum (FWHM) of a 4 4 0 rocking curve measured from the original crystal is approximately 16.7 arcseconds, and defects, which include point defects, line defects, and microscopic domains, have been clearly observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the <110> growth front, and they have been found to originate mostly at a central growth area and occasionally at outer growth regions. Individual point defects trapped at a crystal nucleus are resolved in the images of high sensitivity to defects. Slow dehydration has led to the broadening of the 4 4 0 rocking curve by a factor of approximately 2.4. A significant change of the defect structure and configuration with drying has been revealed, which suggests the dehydration induced migration and evolution of dislocations and lattice rearrangements to reduce overall strain energy. The sufficient details of the observed defects shed light upon perfection, nucleation and growth, and properties of protein crystals.

New Method for the Approximation of Corrected Calcium Concentrations in Chronic Kidney Disease Patients.

PubMed

Kaku, Yoshio; Ookawara, Susumu; Miyazawa, Haruhisa; Ito, Kiyonori; Ueda, Yuichirou; Hirai, Keiji; Hoshino, Taro; Mori, Honami; Yoshida, Izumi; Morishita, Yoshiyuki; Tabei, Kaoru

2016-02-01

The following conventional calcium correction formula (Payne) is broadly applied for serum calcium estimation: corrected total calcium (TCa) (mg/dL) = TCa (mg/dL) + (4 - albumin (g/dL)); however, it is inapplicable to chronic kidney disease (CKD) patients. A total of 2503 venous samples were collected from 942 all-stage CKD patients, and levels of TCa (mg/dL), ionized calcium ([iCa(2+) ] mmol/L), phosphate (mg/dL), albumin (g/dL), and pH, and other clinical parameters were measured. We assumed corrected TCa (the gold standard) to be equal to eight times the iCa(2+) value (measured corrected TCa). Then, we performed stepwise multiple linear regression analysis by using the clinical parameters and derived a simple formula for corrected TCa approximation. The following formula was devised from multiple linear regression analysis: Approximated  corrected TCa (mg/dL) = TCa + 0.25 × (4 - albumin) + 4 × (7.4 - p H) + 0.1 × (6 - phosphate) + 0.3. Receiver operating characteristic curves analysis illustrated that area under the curve of approximated corrected TCa for detection of measured corrected TCa ≥ 8.4 mg/dL and ≤ 10.4 mg/dL were 0.994 and 0.919, respectively. The intraclass correlation coefficient demonstrated superior agreement using this new formula compared to other formulas (new formula: 0.826, Payne: 0.537, Jain: 0.312, Portale: 0.582, Ferrari: 0.362). In CKD patients, TCa correction should include not only albumin but also pH and phosphate. The approximated corrected TCa from this formula demonstrates superior agreement with the measured corrected TCa in comparison to other formulas. © 2016 International Society for Apheresis, Japanese Society for Apheresis, and Japanese Society for Dialysis Therapy.

Soil-Moisture Retention Curves, Capillary Pressure Curves, and Mercury Porosimetry: A Theoretical and Computational Investigation of the Determination of the Geometric Properties of the Pore Space

NASA Astrophysics Data System (ADS)

Strand, T. E.; Wang, H. F.

2003-12-01

Immiscible displacement protocols have long been used to infer the geometric properties of the void space in granular porous media. The three most commonly used experimental techniques are the measurement of soil-moisture retention curves and relative permeability-capillary pressure-saturation relations, as well as mercury intrusion porosimetry experiments. A coupled theoretical and computational investigation was performed that provides insight into the limitations associated with each technique and quantifies the relationship between experimental observations and the geometric properties of the void space. It is demonstrated that the inference of the pore space geometry from both mercury porosimetry experiments and measurements of capillary pressure curves is influenced by trapping/mobilization phenomena and subject to scaling behavior. In addition, both techniques also assume that the capillary pressure at a location on the meniscus can be approximated by a pressure difference across a region or sample. For example, when performing capillary pressure measurements, the capillary pressure, taken to be the difference between the injected fluid pressure at the inlet and the defending fluid pressure at the outlet, is increased in a series of small steps and the fluid saturation is measured each time the system reaches steady. Regions of defending fluid that become entrapped by the invading fluid can be subsequently mobilized at higher flow rates (capillary pressures), contributing to a scale-dependence of the capillary pressure-saturation curve that complicates the determination of the properties of the pore space. This scale-dependence is particularly problematic for measurements performed at the core scale. Mercury porosimetry experiments are subject to similar limitations. Trapped regions of defending fluid are also present during the measurement of soil-moisture retention curves, but the effects of scaling behavior on the evaluation of the pore space properties from the immiscible displacement structure are much simpler to account for due to the control of mobilization phenomena. Some mobilization may occur due to film flow, but this can be limited by keeping time scales relatively small or exploited at longer time scales in order to quantify the rate of film flow. Computer simulations of gradient-stabilized drainage and imbibition to the (respective) equilibrium positions were performed using a pore-scale modified invasion percolation (MIP) model in order to quantify the relationship between the saturation profile and the geometric properties of the void space. These simulations are similar to the experimental measurement of soil-moisture retention curves. Results show that the equilibrium height and the width of the equilibrium fringe depend on two length scale distributions, one controlling the imbibition equilibrium structure and the other controlling the drainage structure. The equilibrium height is related to the mean value of the appropriate distribution as described by Jurin's law, and the width of the equilibrium fringe scales as a function of a combined parameter, the Bond number, Bo, divided by the coefficient of variation (cov). Simulations also demonstrate that the apparent radius distribution obtained from saturation profiles using direct inversion by Jurin's law is a subset of the actual distribution in the porous medium. The relationship between the apparent and actual radius distributions is quantified in terms of the combined parameter, Bo/cov, and the mean coordination number of the porous medium.

Wheelset curving guidance using H∞ control

NASA Astrophysics Data System (ADS)

Qazizadeh, Alireza; Stichel, Sebastian; Feyzmahdavian, Hamid Reza

2018-03-01

This study shows how to design an active suspension system for guidance of a rail vehicle wheelset in curve. The main focus of the study is on designing the controller and afterwards studying its effect on the wheel wear behaviour. The controller is designed based on the closed-loop transfer function shaping method and ? control strategy. The study discusses designing of the controller for both nominal and uncertain plants and considers both stability and performance. The designed controllers in Simulink are then applied to the vehicle model in Simpack to study the wheel wear behaviour in curve. The vehicle type selected for this study is a two-axle rail vehicle. This is because this type of vehicle is known to have very poor curving performance and high wheel wear. On the other hand, the relative simpler structure of this type of vehicle compared to bogie vehicles make it a more economic choice. Hence, equipping this type of vehicle with the active wheelset steering is believed to show high enough benefit to cost ratio to remain attractive to rail vehicle manufacturers and operators.

Weight-Handling Equipment. Design Manual 38.1.

DTIC Science & Technology

1982-06-01

Contact Rails ....... ................... 38.1-153 B-1. Torque-Speed Curves of Wound- Rotor Motor with Single-Phase Dynamic Braking Control...38.1-B-4 B-2. Torque-Speed Curves for Wound- Rotor Motor with DC Dynamic -Braking Lowering Control ... ........... . 38.1-B-6 B-3. Torque-Speed Curves...AC hoist and DC dynamic -braking lowering). (b) Wound- rotor motors. (i) Heavy-duty cranes using AC motors should have motors of the wound- rotor (slip

Planetary spectra for anisotropic scattering

NASA Technical Reports Server (NTRS)

Chamberlain, J. W.

1976-01-01

Some effects on planetary spectra that would be produced by departures from isotropic scattering are examined. The phase function is the simplest departure to handle analytically and the only phase function, other than the isotropic one, that can be incorporated into a Chandrasekhar first approximation. This approach has the advantage of illustrating effects resulting from anisotropies while retaining the simplicity that yields analytic solutions. The curve of growth is the sine qua non of planetary spectroscopy. The discussion emphasizes the difficulties and importance of ascertaining curves of growth as functions of observing geometry. A plea is made to observers to analyze their empirical curves of growth, whenever it seems feasible, in terms of coefficients of which are the leading terms in radiative-transfer analysis. An algebraic solution to the two sets of anisotropic H functions is developed which gives emergent intensities accurate to 0.3%.

Elastic stability of laminated, flat and curved, long rectangular plates subjected to combined inplane loads

NASA Technical Reports Server (NTRS)

Viswanathan, A. V.; Tamekuni, M.; Baker, L. L.

1974-01-01

A method is presented to predict theoretical buckling loads of long, rectangular flat and curved laminated plates with arbitrary orientation of orthotropic axes each lamina. The plate is subjected to combined inplane normal and shear loads. Arbitrary boundary conditions may be stipulated along the longitudinal sides of the plate. In the absence of inplane shear loads and extensional-shear coupling, the analysis is also applicable to finite length plates. Numerical results are presented for curved laminated composite plates with boundary conditions and subjected to various loadings. These results indicate some of the complexities involved in the numerical solution of the analysis for general laminates. The results also show that the reduced bending stiffness approximation when applied to buckling problems could lead to considerable error in some cases and therefore must be used with caution.

Propagation of waves from an arbitrary shaped surface-A generalization of the Fresnel diffraction integral

NASA Astrophysics Data System (ADS)

Feshchenko, R. M.; Vinogradov, A. V.; Artyukov, I. A.

2018-04-01

Using the method of Laplace transform the field amplitude in the paraxial approximation is found in the two-dimensional free space using initial values of the amplitude specified on an arbitrary shaped monotonic curve. The obtained amplitude depends on one a priori unknown function, which can be found from a Volterra first kind integral equation. In a special case of field amplitude specified on a concave parabolic curve the exact solution is derived. Both solutions can be used to study the light propagation from arbitrary surfaces including grazing incidence X-ray mirrors. They can find applications in the analysis of coherent imaging problems of X-ray optics, in phase retrieval algorithms as well as in inverse problems in the cases when the initial field amplitude is sought on a curved surface.

Resonance charge transfer, transport cross sections, and collision integrals for N(+)(3P)-N(4S0) and O(+)(4S0)-O(3P) interactions

NASA Technical Reports Server (NTRS)

Stallcop, James R.; Partridge, Harry; Levin, Eugene

1991-01-01

N2(+) and O2(+) potential energy curves have been constructed by combining measured data with the results from electronic structure calculations. These potential curves have been employed to determine accurate charge exchange cross sections, transport cross sections, and collision integrals for ground state N(+)-N and O(+)-O interactions. The cross sections have been calculated from a semiclassical approximation to the scattering using a computer code that fits a spline curve through the discrete potential data and incorporates the proper long-range behavior of the interactions forces. The collision integrals are tabulated for a broad range of temperatures 250-100,000 K and are intended to reduce the uncertainty in the values of the transport properties of nonequilibrium air, particularly at high temperatures.

Internal jugular vein blood flow in multiple sclerosis patients and matched controls.

PubMed

Mancini, Marcello; Lanzillo, Roberta; Liuzzi, Raffaele; Di Donato, Orlando; Ragucci, Monica; Monti, Serena; Salvatore, Elena; Morra, Vincenzo Brescia; Salvatore, Marco

2014-01-01

The aim of the study was to investigate the Internal Jugular Veins dynamics using contrast enhanced ultrasonography in Multiple Sclerosis patients, clinically isolated syndrome patients and healthy controls. Contrast enhanced ultrasonography imaging of the Internal Jugular Vein was performed in fifty-eight patients with Multiple Sclerosis, seven clinically isolated syndrome patients and in thirteen healthy controls. Time-intensity curves were quantified using a semi-automated method and compared with clinical disease outcomes. Wash-out parameters were calculated and six Time-intensity curves shapes were created. Significantly reduction of wash-out rate in Internal Jugular Veins was detected in Multiple Sclerosis patients compared to healthy controls [22.2% (2.7%-65.9%) vs. 33.4% (16.2%-76.8%); P<0.005]. Internal Jugular Vein enhancement was heterogeneous in patients with Multiple Sclerosis and consisted of slow wash-out Time-intensity curves shapes, compared with almost only one type of Time-intensity curves shape in control subjects that correspond to fast enhancement and fast wash-out. The vein wash-in parameters were similar in Multiple Sclerosis group compared with controls. A significant correlation was found between Internal Jugular Vein wash-out and level of disability (R =  -0.402, p<0.05). Contrast enhanced ultrasonography of the Internal Jugular Vein with time intensity curve analysis revealed alterations of cerebral venous outflow in Multiple Sclerosis patients, however mechanisms that determine this condition remains unclear.

A system of equations to approximate the pharmacokinetic parameters of lacosamide at steady state from one plasma sample.

PubMed

Cawello, Willi; Schäfer, Carina

2014-08-01

Frequent plasma sampling to monitor pharmacokinetic (PK) profile of antiepileptic drugs (AEDs), is invasive, costly and time consuming. For drugs with a well-defined PK profile, such as AED lacosamide, equations can accurately approximate PK parameters from one steady-state plasma sample. Equations were derived to approximate steady-state peak and trough lacosamide plasma concentrations (Cpeak,ss and Ctrough,ss, respectively) and area under concentration-time curve during dosing interval (AUCτ,ss) from one plasma sample. Lacosamide (ka: ∼2 h(-1); ke: ∼0.05 h(-1), corresponding to half-life of 13 h) was calculated to reach Cpeak,ss after ∼1 h (tmax,ss). Equations were validated by comparing approximations to reference PK parameters obtained from single plasma samples drawn 3-12h following lacosamide administration, using data from double-blind, placebo-controlled, parallel-group PK study. Values of relative bias (accuracy) between -15% and +15%, and root mean square error (RMSE) values≤15% (precision) were considered acceptable for validation. Thirty-five healthy subjects (12 young males; 11 elderly males, 12 elderly females) received lacosamide 100mg/day for 4.5 days. Equation-derived PK values were compared to reference mean Cpeak,ss, Ctrough,ss and AUCτ,ss values. Equation-derived PK data had a precision of 6.2% and accuracy of -8.0%, 2.9%, and -0.11%, respectively. Equation-derived versus reference PK values for individual samples obtained 3-12h after lacosamide administration showed correlation (R2) range of 0.88-0.97 for AUCτ,ss. Correlation range for Cpeak,ss and Ctrough,ss was 0.65-0.87. Error analyses for individual sample comparisons were independent of time. Derived equations approximated lacosamide Cpeak,ss, Ctrough,ss and AUCτ,ss using one steady-state plasma sample within validation range. Approximated PK parameters were within accepted validation criteria when compared to reference PK values. Copyright © 2014 Elsevier B.V. All rights reserved.

Interaction function of oscillating coupled neurons

PubMed Central

Dodla, Ramana; Wilson, Charles J.

2013-01-01

Large scale simulations of electrically coupled neuronal oscillators often employ the phase coupled oscillator paradigm to understand and predict network behavior. We study the nature of the interaction between such coupled oscillators using weakly coupled oscillator theory. By employing piecewise linear approximations for phase response curves and voltage time courses, and parameterizing their shapes, we compute the interaction function for all such possible shapes and express it in terms of discrete Fourier modes. We find that reasonably good approximation is achieved with four Fourier modes that comprise of both sine and cosine terms. PMID:24229210

Flight evaluation of the terminal guidance system

NASA Technical Reports Server (NTRS)

Sandlin, D. R.

1981-01-01

The terminal guidance system (TGS) is avionic equipment which gives guidance along a curved descending flight path to a landing. A Cessna 182 was used as the test aircraft and the TGS was installed and connected to the altimeter, DME, RMI, and gyro compass. Approaches were flown by three different pilots. When the aircraft arrives at the termination point, it is set up on final approach for a landing. The TGS provides guidance for curved descending approaches with guideslopes of 6 deg which required, for experienced pilots, workloads that are approximately the same as for an ILS. The glideslope is difficult to track within 1/2 n.m. of the VOR/DME station. The system permits, for experienced pilots, satisfactory approaches with a turn radius as low as 1/2 n.m. and a glideslope of 6 deg. Turn angles have little relation to pilot workload for curved approaches. Pilot experience is a factor for curved approaches. Pilots with low instrument time have difficulty flying steep approaches with small turn radius. Turbulence increases the pilot workload for curved approaches. The TGS does not correct to a given flight path over the ground nor does it adequately compensate for wind drift.

A Holocene paleosecular variation from 14C-dated volcanic rocks in Western North America

USGS Publications Warehouse

Hagstrum, J.T.; Champion, D.E.

2002-01-01

A paleosecular variation (PSV) curve for western North America is presented on the basis of 94 virtual geomagnetic poles (VGPs) from dated volcanic rocks sampled at 446 sites. Approximately 60% of the paleomagnetic database has been previously published. A curve defined by "spherical smoothed splines" is fitted to the VGPs, ranked by the quality of the age determinations, where the data density is highest between 3690 and -30 years before present (B.P.) (A.D. 1950), between 7800 and 7050 years B.P., and between 14,060 and 12,700 years B.P. The younger segments of the curve derived from volcanic rocks are similar but less complex than other high-resolution PSV curves derived from lacustrine sediments, particularly the record at Fish Lake, Oregon. The PSV record from lava flows (PSVL), however, is perhaps more reliable in its general shape and chronology because of the higher fidelity of volcanic rocks as magnetic field recorders and because of the greater density of 14C dates. The new PSVL record provides a partial Holocene master curve for western North America and will be of particular value in dating geological and archeological materials using paleomagnetic directions.

Applications of species accumulation curves in large-scale biological data analysis.

PubMed

Deng, Chao; Daley, Timothy; Smith, Andrew D

2015-09-01

The species accumulation curve, or collector's curve, of a population gives the expected number of observed species or distinct classes as a function of sampling effort. Species accumulation curves allow researchers to assess and compare diversity across populations or to evaluate the benefits of additional sampling. Traditional applications have focused on ecological populations but emerging large-scale applications, for example in DNA sequencing, are orders of magnitude larger and present new challenges. We developed a method to estimate accumulation curves for predicting the complexity of DNA sequencing libraries. This method uses rational function approximations to a classical non-parametric empirical Bayes estimator due to Good and Toulmin [Biometrika, 1956, 43, 45-63]. Here we demonstrate how the same approach can be highly effective in other large-scale applications involving biological data sets. These include estimating microbial species richness, immune repertoire size, and k -mer diversity for genome assembly applications. We show how the method can be modified to address populations containing an effectively infinite number of species where saturation cannot practically be attained. We also introduce a flexible suite of tools implemented as an R package that make these methods broadly accessible.

Applications of species accumulation curves in large-scale biological data analysis

PubMed Central

Deng, Chao; Daley, Timothy; Smith, Andrew D

2016-01-01

The species accumulation curve, or collector’s curve, of a population gives the expected number of observed species or distinct classes as a function of sampling effort. Species accumulation curves allow researchers to assess and compare diversity across populations or to evaluate the benefits of additional sampling. Traditional applications have focused on ecological populations but emerging large-scale applications, for example in DNA sequencing, are orders of magnitude larger and present new challenges. We developed a method to estimate accumulation curves for predicting the complexity of DNA sequencing libraries. This method uses rational function approximations to a classical non-parametric empirical Bayes estimator due to Good and Toulmin [Biometrika, 1956, 43, 45–63]. Here we demonstrate how the same approach can be highly effective in other large-scale applications involving biological data sets. These include estimating microbial species richness, immune repertoire size, and k-mer diversity for genome assembly applications. We show how the method can be modified to address populations containing an effectively infinite number of species where saturation cannot practically be attained. We also introduce a flexible suite of tools implemented as an R package that make these methods broadly accessible. PMID:27252899

Defining the learning curve in laparoscopic paraesophageal hernia repair: a CUSUM analysis.

PubMed

Okrainec, Allan; Ferri, Lorenzo E; Feldman, Liane S; Fried, Gerald M

2011-04-01

There are numerous reports in the literature documenting high recurrence rates after laparoscopic paraesophageal hernia repair. The purpose of this study was to determine the learning curve for this procedure using the Cumulative Summation (CUSUM) technique. Forty-six consecutive patients with paraesophageal hernia were evaluated prospectively after laparoscopic paraesophageal hernia repair. Upper GI series was performed 3 months postoperatively to look for recurrence. Patients were stratified based on the surgeon's early (first 20 cases) and late experience (>20 cases). The CUSUM method was then used to further analyze the learning curve. Nine patients (21%) had anatomic recurrence. There was a trend toward a higher recurrence rate during the first 20 cases, although this did not achieve statistical significance (33% vs. 13%, p = 0.10). However, using a CUSUM analysis to plot the learning curve, we found that the recurrence rate diminishes after 18 cases and reaches an acceptable rate after 26 cases. Surgeon experience is an important predictor of recurrence after laparoscopic paraesophageal hernia repair. CUSUM analysis revealed there is a significant learning curve to become proficient at this procedure, with approximately 20 cases required before a consistent decrease in hernia recurrence rate is observed.

Difference equation state approximations for nonlinear hereditary control problems

NASA Technical Reports Server (NTRS)

Rosen, I. G.

1982-01-01

Discrete approximation schemes for the solution of nonlinear hereditary control problems are constructed. The methods involve approximation by a sequence of optimal control problems in which the original infinite dimensional state equation has been approximated by a finite dimensional discrete difference equation. Convergence of the state approximations is argued using linear semigroup theory and is then used to demonstrate that solutions to the approximating optimal control problems in some sense approximate solutions to the original control problem. Two schemes, one based upon piecewise constant approximation, and the other involving spline functions are discussed. Numerical results are presented, analyzed and used to compare the schemes to other available approximation methods for the solution of hereditary control problems.

Comparative evaluation of Kodak EDR2 and XV2 films for verification of intensity modulated radiation therapy.

PubMed

Dogan, Nesrin; Leybovich, Leonid B; Sethi, Anil

2002-11-21

Film dosimetry provides a convenient tool to determine dose distributions, especially for verification of IMRT plans. However, the film response to radiation shows a significant dependence on depth, energy and field size that compromise the accuracy of measurements. Kodak's XV2 film has a low saturation dose (approximately 100 cGy) and, consequently, a relatively short region of linear dose-response. The recently introduced Kodak extended range EDR2 film was reported to have a linear dose-response region extending to 500 cGy. This increased dose range may be particularly useful in the verification of IMRT plans. In this work, the dependence of Kodak EDR2 film's response on the depth, field size and energy was evaluated and compared with Kodak XV2 film. Co-60, 6 MV, 10 MV and 18 MV beams were used. Field sizes were 2 x 2, 6 x 6, 10 x 10, 14 x 14, 18 x 18 and 24 x 24 cm2. Doses for XV2 and EDR2 films were 80 cGy and 300 cGy, respectively. Optical density was converted to dose using depth-corrected sensitometric (Hurter and Driffield, or H&D) curves. For each field size, XV2 and EDR2 depth-dose curves were compared with ion chamber depth-dose curves. Both films demonstrated similar (within 1%) field size dependence. The deviation from the ion chamber for both films was small forthe fields ranging from 2 x 2 to 10 x 10 cm2: < or =2% for 6, 10 and 18 MV beams. No deviation was observed for the Co-60 beam. As the field size increased to 24 x 24 cm2, the deviation became significant for both films: approximately 7.5% for Co-60, approximately 5% for 6 MV and 10 MV, and approximately 6% for 18 MV. During the verification of IMRT plans, EDR2 film showed a better agreement with the calculated dose distributions than the XV2 film.

Shear wave velocities in the upper mantle of the Western Alps: new constraints using array analysis of seismic surface waves

NASA Astrophysics Data System (ADS)

Lyu, Chao; Pedersen, Helle A.; Paul, Anne; Zhao, Liang; Solarino, Stefano

2017-07-01

It remains challenging to obtain absolute shear wave velocities of heterogeneities of small lateral extension in the uppermost mantle. This study presents a cross-section of Vs across the strongly heterogeneous 3-D structure of the western European Alps, based on array analysis of data from 92 broad-band seismic stations from the CIFALPS experiment and from permanent networks in France and Italy. Half of the stations were located along a dense sublinear array. Using a combination of these stations and off-profile stations, fundamental-mode Rayleigh wave dispersion curves were calculated using a combined frequency-time beamforming approach. We calculated dispersion curves for seven arrays of approximately 100 km aperture and 14 arrays of approximately 50 km aperture, the latter with the aim of obtaining a 2-D vertical cross-section of Vs beneath the western Alps. The dispersion curves were inverted for Vs(z), with crustal interfaces imposed from a previous receiver function study. The array approach proved feasible, as Vs(z) from independent arrays vary smoothly across the profile length. Results from the seven large arrays show that the shear velocity of the upper mantle beneath the European plate is overall low compared to AK135 with the lowest velocities in the internal part of the western Alps, and higher velocities east of the Alps beneath the Po plain. The 2-D Vs model is coherent with (i) a ∼100 km thick eastward-dipping European lithosphere west of the Alps, (ii) very high velocities beneath the Po plain, coherent with the presence of the Alpine (European) slab and (iii) a narrow low-velocity anomaly beneath the core of the western Alps (from the Briançonnais to the Dora Maira massif), and approximately colocated with a similar anomaly observed in a recent teleseismic P-wave tomography. This intriguing anomaly is also supported by traveltime variations of subvertically propagating body waves from two teleseismic events that are approximately located on the profile great circle.

The Academic Trajectories of Children of Immigrants and Their School Environments

ERIC Educational Resources Information Center

Han, Wen-Jui

2008-01-01

Data from approximately 14,000 children in the Early Childhood Longitudinal Survey--Kindergarten Cohort were analyzed to examine the associations between children's immigrant status and their academic trajectories from kindergarten to 3rd grade, with particular attention to the effects of school environments. Growth curve modeling results…

Cranberry magnetite deposits Avery County, N.C., and Carter County, Tenn.

USGS Publications Warehouse

Kline, M.H.; Ballard, T.J.

1948-01-01

The Cranberry magnetite deposits occur in pre-Cambrian granite-gneiss in a belt extending from 3 miles southeast of Cranberry, N.C., to about 6 miles southwest of Magnetic City, Tenn. The belt forms a curve, elongated to the north, approximately 26 miles in length.

Two Propositions on the Application of Point Elasticities to Finite Price Changes.

ERIC Educational Resources Information Center

Daskin, Alan J.

1992-01-01

Considers counterintuitive propositions about using point elasticities to estimate quantity changes in response to price changes. Suggests that elasticity increases with price along a linear demand curve, but falling quantity demand offsets it. Argues that point elasticity with finite percentage change in price only approximates percentage change…

Pharmacokinetic Correlates of the Effects of a Heroin Vaccine on Heroin Self-Administration in Rats

PubMed Central

Raleigh, Michael D.; Pentel, Paul R.; LeSage, Mark G.

2014-01-01

The purpose of this study was to evaluate the effects of a morphine-conjugate vaccine (M-KLH) on the acquisition, maintenance, and reinstatement of heroin self-administration (HSA) in rats, and on heroin and metabolite distribution during heroin administration that approximated the self-administered dosing rate. Vaccination with M-KLH blocked heroin-primed reinstatement of heroin responding. Vaccination also decreased HSA at low heroin unit doses but produced a compensatory increase in heroin self-administration at high unit doses. Vaccination shifted the heroin dose-response curve to the right, indicating reduced heroin potency, and behavioral economic demand curve analysis further confirmed this effect. In a separate experiment heroin was administered at rates simulating heroin exposure during HSA. Heroin and its active metabolites, 6-acetylmorphine (6-AM) and morphine, were retained in plasma and metabolite concentrations were reduced in brain in vaccinated rats compared to controls. Reductions in 6-AM concentrations in brain after vaccination were consistent with the changes in HSA rates accompanying vaccination. These data provide evidence that 6-AM is the principal mediator of heroin reinforcement, and the principal target of the M-KLH vaccine, in this model. While heroin vaccines may have potential as therapies for heroin addiction, high antibody to drug ratios appear to be important for obtaining maximal efficacy. PMID:25536404

Mask data processing in the era of multibeam writers

NASA Astrophysics Data System (ADS)

Abboud, Frank E.; Asturias, Michael; Chandramouli, Maesh; Tezuka, Yoshihiro

2014-10-01

Mask writers' architectures have evolved through the years in response to ever tightening requirements for better resolution, tighter feature placement, improved CD control, and tolerable write time. The unprecedented extension of optical lithography and the myriad of Resolution Enhancement Techniques have tasked current mask writers with ever increasing shot count and higher dose, and therefore, increasing write time. Once again, we see the need for a transition to a new type of mask writer based on massively parallel architecture. These platforms offer a step function improvement in both dose and the ability to process massive amounts of data. The higher dose and almost unlimited appetite for edge corrections open new windows of opportunity to further push the envelope. These architectures are also naturally capable of producing curvilinear shapes, making the need to approximate a curve with multiple Manhattan shapes unnecessary.

Fitting Curves by Fractal Interpolation: AN Application to the Quantification of Cognitive Brain Processes

NASA Astrophysics Data System (ADS)

Navascues, M. A.; Sebastian, M. V.

Fractal interpolants of Barnsley are defined for any continuous function defined on a real compact interval. The uniform distance between the function and its approximant is bounded in terms of the vertical scale factors. As a general result, the density of the affine fractal interpolation functions of Barnsley in the space of continuous functions in a compact interval is proved. A method of data fitting by means of fractal interpolation functions is proposed. The procedure is applied to the quantification of cognitive brain processes. In particular, the increase in the complexity of the electroencephalographic signal produced by the execution of a test of visual attention is studied. The experiment was performed on two types of children: a healthy control group and a set of children diagnosed with an attention deficit disorder.

Correcting AUC for Measurement Error.

PubMed

Rosner, Bernard; Tworoger, Shelley; Qiu, Weiliang

2015-12-01

Diagnostic biomarkers are used frequently in epidemiologic and clinical work. The ability of a diagnostic biomarker to discriminate between subjects who develop disease (cases) and subjects who do not (controls) is often measured by the area under the receiver operating characteristic curve (AUC). The diagnostic biomarkers are usually measured with error. Ignoring measurement error can cause biased estimation of AUC, which results in misleading interpretation of the efficacy of a diagnostic biomarker. Several methods have been proposed to correct AUC for measurement error, most of which required the normality assumption for the distributions of diagnostic biomarkers. In this article, we propose a new method to correct AUC for measurement error and derive approximate confidence limits for the corrected AUC. The proposed method does not require the normality assumption. Both real data analyses and simulation studies show good performance of the proposed measurement error correction method.

Curvature effects on the electronic and transport properties of semiconductor films

NASA Astrophysics Data System (ADS)

Batista, F. F.; Chaves, Andrey; da Costa, D. R.; Farias, G. A.

2018-05-01

Within the effective mass approximation, we study the curvature effects on the electronic and transport properties of semiconductor films. We investigate how the geometry-induced potential resulting exclusively from periodic ripples in the film induces electronic confinement and a superlattice band structure. For fixed curvature parameters, such a confinement can be easily tuned by an external electric field, hence features of the superlattice band structure such as its energy gaps and band curvature can be controlled by an external parameter. We also show that, for some values of curvature and electric field, it is possible to obtain massless Dirac bands for a smooth curved structure. Moreover, we use a wave packet propagation method to demonstrate that the ripples are responsible for a significant inter-sub-band transition, specially for moderate values of the ripple height.

Semi-analytical solutions of the Schnakenberg model of a reaction-diffusion cell with feedback

NASA Astrophysics Data System (ADS)

Al Noufaey, K. S.

2018-06-01

This paper considers the application of a semi-analytical method to the Schnakenberg model of a reaction-diffusion cell. The semi-analytical method is based on the Galerkin method which approximates the original governing partial differential equations as a system of ordinary differential equations. Steady-state curves, bifurcation diagrams and the region of parameter space in which Hopf bifurcations occur are presented for semi-analytical solutions and the numerical solution. The effect of feedback control, via altering various concentrations in the boundary reservoirs in response to concentrations in the cell centre, is examined. It is shown that increasing the magnitude of feedback leads to destabilization of the system, whereas decreasing this parameter to negative values of large magnitude stabilizes the system. The semi-analytical solutions agree well with numerical solutions of the governing equations.

Nonlinear mathematical modeling and sensitivity analysis of hydraulic drive unit

NASA Astrophysics Data System (ADS)

Kong, Xiangdong; Yu, Bin; Quan, Lingxiao; Ba, Kaixian; Wu, Liujie

2015-09-01

The previous sensitivity analysis researches are not accurate enough and also have the limited reference value, because those mathematical models are relatively simple and the change of the load and the initial displacement changes of the piston are ignored, even experiment verification is not conducted. Therefore, in view of deficiencies above, a nonlinear mathematical model is established in this paper, including dynamic characteristics of servo valve, nonlinear characteristics of pressure-flow, initial displacement of servo cylinder piston and friction nonlinearity. The transfer function block diagram is built for the hydraulic drive unit closed loop position control, as well as the state equations. Through deriving the time-varying coefficient items matrix and time-varying free items matrix of sensitivity equations respectively, the expression of sensitivity equations based on the nonlinear mathematical model are obtained. According to structure parameters of hydraulic drive unit, working parameters, fluid transmission characteristics and measured friction-velocity curves, the simulation analysis of hydraulic drive unit is completed on the MATLAB/Simulink simulation platform with the displacement step 2 mm, 5 mm and 10 mm, respectively. The simulation results indicate that the developed nonlinear mathematical model is sufficient by comparing the characteristic curves of experimental step response and simulation step response under different constant load. Then, the sensitivity function time-history curves of seventeen parameters are obtained, basing on each state vector time-history curve of step response characteristic. The maximum value of displacement variation percentage and the sum of displacement variation absolute values in the sampling time are both taken as sensitivity indexes. The sensitivity indexes values above are calculated and shown visually in histograms under different working conditions, and change rules are analyzed. Then the sensitivity indexes values of four measurable parameters, such as supply pressure, proportional gain, initial position of servo cylinder piston and load force, are verified experimentally on test platform of hydraulic drive unit, and the experimental research shows that the sensitivity analysis results obtained through simulation are approximate to the test results. This research indicates each parameter sensitivity characteristics of hydraulic drive unit, the performance-affected main parameters and secondary parameters are got under different working conditions, which will provide the theoretical foundation for the control compensation and structure optimization of hydraulic drive unit.

Difference equation state approximations for nonlinear hereditary control problems

NASA Technical Reports Server (NTRS)

Rosen, I. G.

1984-01-01

Discrete approximation schemes for the solution of nonlinear hereditary control problems are constructed. The methods involve approximation by a sequence of optimal control problems in which the original infinite dimensional state equation has been approximated by a finite dimensional discrete difference equation. Convergence of the state approximations is argued using linear semigroup theory and is then used to demonstrate that solutions to the approximating optimal control problems in some sense approximate solutions to the original control problem. Two schemes, one based upon piecewise constant approximation, and the other involving spline functions are discussed. Numerical results are presented, analyzed and used to compare the schemes to other available approximation methods for the solution of hereditary control problems. Previously announced in STAR as N83-33589

The heat rate index indicator

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

Lasasso, M.; Runyan, B.; Napoli, J.

1995-06-01

This paper describes a method of tracking unit performance through the use of a reference number called the Heat Rate Index Indicator. The ABB Power Plant Controls OTIS performance monitor is used to determine when steady load conditions exist and then to collect controllable and equipment loss data which significantly impact thermal efficiency. By comparing these loss parameters to those found during the previous heat balance, it is possible to develop a new adjusted heat rate curve. These impacts on heat rate are used to changes the shape of the tested heat rate curve by the appropriate percentages over amore » specified load range. Mathcad is used to determine the Heat Rate Index by integrating for the areas beneath the adjusted heat rate curve and a heat rate curve that represents the unit`s ideal heat rate curve is the Heat Rate Index. An index of 1.0 indicates that the unit is operating at an ideal efficiency, while an index of less than 1.0 indicates that the unit is operating at less than ideal conditions. A one per cent change in the Heat Rate Index is equivalent to a one percent change in heat rate. The new shape of the adjusted heat rate curve and the individual curves generated from the controllable and equipment loss parameters are useful for determining performance problems in specific load ranges.« less

Dynamics of the exponential integrate-and-fire model with slow currents and adaptation.

PubMed

Barranca, Victor J; Johnson, Daniel C; Moyher, Jennifer L; Sauppe, Joshua P; Shkarayev, Maxim S; Kovačič, Gregor; Cai, David

2014-08-01

In order to properly capture spike-frequency adaptation with a simplified point-neuron model, we study approximations of Hodgkin-Huxley (HH) models including slow currents by exponential integrate-and-fire (EIF) models that incorporate the same types of currents. We optimize the parameters of the EIF models under the external drive consisting of AMPA-type conductance pulses using the current-voltage curves and the van Rossum metric to best capture the subthreshold membrane potential, firing rate, and jump size of the slow current at the neuron's spike times. Our numerical simulations demonstrate that, in addition to these quantities, the approximate EIF-type models faithfully reproduce bifurcation properties of the HH neurons with slow currents, which include spike-frequency adaptation, phase-response curves, critical exponents at the transition between a finite and infinite number of spikes with increasing constant external drive, and bifurcation diagrams of interspike intervals in time-periodically forced models. Dynamics of networks of HH neurons with slow currents can also be approximated by corresponding EIF-type networks, with the approximation being at least statistically accurate over a broad range of Poisson rates of the external drive. For the form of external drive resembling realistic, AMPA-like synaptic conductance response to incoming action potentials, the EIF model affords great savings of computation time as compared with the corresponding HH-type model. Our work shows that the EIF model with additional slow currents is well suited for use in large-scale, point-neuron models in which spike-frequency adaptation is important.

Average size of random polygons with fixed knot topology.

PubMed

Matsuda, Hiroshi; Yao, Akihisa; Tsukahara, Hiroshi; Deguchi, Tetsuo; Furuta, Ko; Inami, Takeo

2003-07-01

We have evaluated by numerical simulation the average size R(K) of random polygons of fixed knot topology K=,3(1),3(1) musical sharp 4(1), and we have confirmed the scaling law R(2)(K) approximately N(2nu(K)) for the number N of polygonal nodes in a wide range; N=100-2200. The best fit gives 2nu(K) approximately 1.11-1.16 with good fitting curves in the whole range of N. The estimate of 2nu(K) is consistent with the exponent of self-avoiding polygons. In a limited range of N (N greater, similar 600), however, we have another fit with 2nu(K) approximately 1.01-1.07, which is close to the exponent of random polygons.

Adatom lifetime in film growth at solid surfaces in the framework of the Johnson Mehl Avrami Kolmogorov model

NASA Astrophysics Data System (ADS)

Tomellini, M.; Fanfoni, M.

1999-10-01

On the basis of the quasi-static approximation and for simultaneous nucleation the adatom lifetime, τ, during film growth at solid surfaces has been computed by Monte Carlo (MC) simulation. The quantity DN0τ, N0 and D being respectively the cluster density and the adatom diffusion coefficient, is found to depend upon the portion of surface covered by clusters and, very weakly, on N0. Moreover, a stochastic approach based on the Johnson-Mehl-Avrami-Kolmogorov (JMAK) theory has been developed to obtain the analytical expression of the MC curve. The collision factor of the mean island has been calculated and compared with those previously obtained from the uniform depletion approximation and the lattice approximation.

Frequent Flaring in the TRAPPIST-1 System—Unsuited for Life?

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

Vida, K.; Kővári, Zs.; Pál, A.

2017-06-01

We analyze the K2 light curve of the TRAPPIST-1 system. The Fourier analysis of the data suggests P {sub rot} = 3.295 ± 0.003 days. The light curve shows several flares, of which we analyzed 42 events with integrated flare energies of 1.26 × 10{sup 30}–1.24 × 10{sup 33} erg. Approximately 12% of the flares were complex, multi-peaked eruptions. The flaring and the possible rotational modulation shows no obvious correlation. The flaring activity of TRAPPIST-1 probably continuously alters the atmospheres of the orbiting exoplanets, which makes these less favorable for hosting life.

Disease prevalence and the index of detectability: a survey of studies of lung cancer detection by chest radiography

NASA Astrophysics Data System (ADS)

Kundel, Harold L.

2000-04-01

A survey of 12 studies of lung cancer detection with cancer prevalence ranging from 0.9 to 476 cancers per 1000 showed that the unit-slope index of detectability, d', decreased from a high value of 3.9 at low prevalence to 1.4 at high prevalence. A proposed explanation is that the readers are operating on an ROC curve with a slope that is less than unity approximating 0.6. On such a curve, a shift to more stringent criteria that occurs with decreasing prevalence in order to minimize false positives, would result in a increased unity- slope d'.

Effect of radial magnetic field on peristaltic transport of Jeffrey fluid in curved channel with heat / mass transfer

NASA Astrophysics Data System (ADS)

Abdulhadi, Ahmed M.; Ahmed, Tamara S.

2018-05-01

In this paper, we deals with the impact of radialiy magnetic field on the peristaltic transport of Jeffrey fluid through a curved channel with two dimensional. The effect of slip condition on velocity, the non-slip condition on temperature and conversation is performed. The heat and mass transfer are considered under the influence of various parameters. The flow is investigated under the assumption of long wave length and low Reynolds number approximations. The distribution of temperature and concentration are discussed for various parameters governing the flow with the simultaneous effects of Brinkman number, Soret number and Schmidt number.

A LAGRANGIAN GAUSS-NEWTON-KRYLOV SOLVER FOR MASS- AND INTENSITY-PRESERVING DIFFEOMORPHIC IMAGE REGISTRATION.

PubMed

Mang, Andreas; Ruthotto, Lars

2017-01-01

We present an efficient solver for diffeomorphic image registration problems in the framework of Large Deformations Diffeomorphic Metric Mappings (LDDMM). We use an optimal control formulation, in which the velocity field of a hyperbolic PDE needs to be found such that the distance between the final state of the system (the transformed/transported template image) and the observation (the reference image) is minimized. Our solver supports both stationary and non-stationary (i.e., transient or time-dependent) velocity fields. As transformation models, we consider both the transport equation (assuming intensities are preserved during the deformation) and the continuity equation (assuming mass-preservation). We consider the reduced form of the optimal control problem and solve the resulting unconstrained optimization problem using a discretize-then-optimize approach. A key contribution is the elimination of the PDE constraint using a Lagrangian hyperbolic PDE solver. Lagrangian methods rely on the concept of characteristic curves. We approximate these curves using a fourth-order Runge-Kutta method. We also present an efficient algorithm for computing the derivatives of the final state of the system with respect to the velocity field. This allows us to use fast Gauss-Newton based methods. We present quickly converging iterative linear solvers using spectral preconditioners that render the overall optimization efficient and scalable. Our method is embedded into the image registration framework FAIR and, thus, supports the most commonly used similarity measures and regularization functionals. We demonstrate the potential of our new approach using several synthetic and real world test problems with up to 14.7 million degrees of freedom.

An avionics sensitivity study. Volume 1: Operational considerations

NASA Technical Reports Server (NTRS)

Scott, R. W.; Mcconkey, E. D.

1976-01-01

Equipment and operational concepts affecting aircraft in the terminal area are reported. Curved approach applications and modified climb and descent procedures for minimum fuel consumption are considered. The curved approach study involves the application of MLS guidance to enable execution of the current visual approach to Washington National Airport under instrument flight conditions. The operational significance and the flight path control requirements involved in the application of curved approach paths to this situation are considered. Alternative flight path control regimes are considered to achieve minimum fuel consumption subject to constraints related to air traffic control requirements, flight crew and passenger reactions, and airframe and powerplant limitations.

Preliminary experience and learning curve for laparoendoscopic single-site retroperitoneal pyeloplasty.

PubMed

Ou, Zhenyu; Qi, Lin; Yang, Jinrui; Chen, Xiang; Cao, Zhenzhen; Zu, Xiongbing; Liu, Longfei; Wang, Long

2013-09-01

To report our preliminary experience and to assess the learning curve for laparoendoscopic single-site retroperitoneal pyeloplasty (LESS-RP) for ureteropelvic junction obstruction (UPJO). From July 2010 to February 2012, LESS-RP was performed in 27 patients affected with UPJO by a single surgeon. A homemade single-access platform and both conventional and prebent instruments were applied. Patient characteristics and perioperative outcomes were analyzed. The cumulative sum (CUSUM) method was used to evaluate the learning curve. The LESS-RP was successfully accomplished in all 27 patients. The mean operative time (OT) was 175.9±22.5 minutes, and the mean estimated blood loss was 83.3±27.1 mL. We used the OT as a proxy to assess the learning curve. The CUSUM learning curve can be divided into two distinct phases: the initial 12 cases and the last 15 cases. There were significant differences in the mean OT (195.6 minutes versus 159.1 minutes, P<.001) and mean estimated blood loss (97.2 mL versus 72.2 mL, P=.014) between the two phases. The two phases did not differ in other parameters. LESS-RP is a safe and feasible procedure. The learning curve of a single surgeon suggests that the initial learning phase for LESS-RP can be completed after approximately 12 cases.

The late behavior of supernova 1987A. I - The light curve. II - Gamma-ray transparency of the ejecta

NASA Technical Reports Server (NTRS)

Arnett, W. David; Fu, Albert

1989-01-01

Observations of the late (t = 20-1500 days) bolometric light curve and the gamma-lines and X-rays from supernova 1987A are compared to theoretical models. It is found that 0.073 + or - 0.015 solar masses of freshly synthesized Ni-56 must be present to fit the bolometric light curve. The results place limits on the luminosity and presumed period of the newly formed pulsar/neutron star. In the second half of the paper, the problem of computing the luminosities in gamma-ray lines and in X-rays from supernova 1987A is addressed. High-energy observations suggest the development of large-scale clumping and bubbling of radioactive material in the ejecta. A model is proposed with a hydrogen envelope mass of about 7 solar masses, homologous scale expansion velocities of about 3000 km/s, and an approximately uniform mass distribution.

An elementary theory of eclipsing depths of the light curve and its application to Beta Lyrae

NASA Technical Reports Server (NTRS)

Huang, S.-S.; Brown, D. A.

1976-01-01

An elementary theory of the ratio of depths of secondary and primary eclipses of a light curve has been proposed for studying the nature of component stars. It has been applied to light curves of Beta Lyrae in the visual, blue, and far-ultraviolet regions with the purpose of investigating the energy sources for the luminosity of the disk surrounding the secondary component and determining the dominant radiative process in the disk. No trace of the spectrum of primary radiation has been found in the disk. Therefore, it is suggested that LTE is the main radiative process in the disk, which radiates at a temperature of approximately 12,000 K in the portion that undergoes eclipse. A small source corresponding to 14,500 K has also been tentatively detected and may represent a hot spot caused by hydrodynamic flow of matter from the primary component to the disk.

Dispersion analysis and measurement of circular cylindrical wedge-like acoustic waveguides.

PubMed

Yu, Tai-Ho

2015-09-01

This study investigated the propagation of flexural waves along the outer edge of a circular cylindrical wedge, the phase velocities, and the corresponding mode displacements. Thus far, only approximate solutions have been derived because the corresponding boundary-value problems are complex. In this study, dispersion curves were determined using the bi-dimensional finite element method and derived through the separation of variables and the Hamilton principle. Modal displacement calculations clarified that the maximal deformations appeared at the outer edge of the wedge tip. Numerical examples indicated how distinct thin-film materials deposited on the outer surface of the circular cylindrical wedge influenced the dispersion curves. Additionally, dispersion curves were measured using a laser-induced guided wave, a knife-edge measurement scheme, and a two-dimensional fast Fourier transform method. Both the numerical and experimental results correlated closely, thus validating the numerical solution. Copyright © 2015 Elsevier B.V. All rights reserved.

Lightweight Solar Paddle with High Specific Power of 150 W/Kg

NASA Astrophysics Data System (ADS)

Shimazaki, Kazunori; Takahashi, Masato; Imaizumi, Mitsuru; Takamoto, Tatsuya; Ito, Takehiko; Nozaki, Yukishige; Kusawake, Hiroaki

2014-08-01

A lightweight solar paddle using space solar sheet (SSS) is currently being developed, which uses glass-type SSS (G-SSS) comprising InGaP/GaAs/InGaAs triple- junction high-efficiency thin-film solar cells. To avoid damage to the G-SSS due to vibration during launch, we adopted a new architecture on a panel. This panel employed a curved frame-type structure, on which the G-SSS is mounted and test models were manufactured to evaluate the vibration tolerance. The dimensions of the 1.0-cm-thick unit panel were about 1.0 × 1.0 m. Acoustic and sine vibration tests were performed on the model and the results demonstrated the high durability of the curved panel in an acoustic and vibration environments. The specific power of the solar paddle using the curved panel is estimated at approximately 150 W/kg at an array power of about 10 kW.

Human Bile Reduces Antimicrobial Activity of Selected Antibiotics against Enterococcus faecalis and Escherichia coli In Vitro.

PubMed

Wulkersdorfer, Beatrix; Jaros, David; Eberl, Sabine; Poschner, Stefan; Jäger, Walter; Cosentini, Enrico; Zeitlinger, Markus; Schwameis, Richard

2017-08-01

It has been known from previous studies that body fluids, such as cerebrospinal fluid, lung surfactant, and urine, have a strong impact on the bacterial killing of many anti-infective agents. However, the influence of human bile on the antimicrobial activity of antibiotics is widely unknown. Human bile was obtained and pooled from 11 patients undergoing cholecystectomy. After sterilization of the bile fluid by gamma irradiation, its effect on bacterial killing was investigated for linezolid (LZD) and tigecycline (TGC) against Enterococcus faecalis ATCC 29212. Further, ciprofloxacin (CIP), meropenem (MEM), and TGC were tested against Escherichia coli ATCC 25922. Time-kill curves were performed in pooled human bile and Mueller-Hinton broth (MHB) over 24 h. Bacterial counts (in CFU per milliliter after 24 h) of bile growth controls were approximately equal to MHB growth controls for E. coli and approximately 2-fold greater for E. faecalis , indicating a promotion of bacterial growth by bile for the latter strain. Bile reduced the antimicrobial activity of CIP, MEM, and TGC against E. coli as well as the activity of LZD and TGC against E. faecalis This effect was strongest for TGC against the two strains. Degradation of TGC in bile was identified as the most likely explanation. These findings may have important implications for the treatment of bacterial infections of the gallbladder and biliary tract and should be explored in more detail. Copyright © 2017 American Society for Microbiology.

Fabricating small-scale, curved, polymeric structures with convex and concave menisci through interfacial free energy equilibrium.

PubMed

Cheng, Chao-Min; Matsuura, Koji; Wang, I-Jan; Kuroda, Yuka; LeDuc, Philip R; Naruse, Keiji

2009-11-21

Polymeric curved structures are widely used in imaging systems including optical fibers and microfluidic channels. Here, we demonstrate that small-scale, poly(dimethylsiloxane) (PDMS)-based, curved structures can be fabricated through controlling interfacial free energy equilibrium. Resultant structures have a smooth, symmetric, curved surface, and may be convex or concave in form based on surface tension balance. Their curvatures are controlled by surface characteristics (i.e., hydrophobicity and hydrophilicity) of the molds and semi-liquid PDMS. In addition, these structures are shown to be biocompatible for cell culture. Our system provides a simple, efficient and economical method for generating integrateable optical components without costly fabrication facilities.

Robust, open-source removal of systematics in Kepler data

NASA Astrophysics Data System (ADS)

Aigrain, S.; Parviainen, H.; Roberts, S.; Reece, S.; Evans, T.

2017-10-01

We present ARC2 (Astrophysically Robust Correction 2), an open-source python-based systematics-correction pipeline, to correct for the Kepler prime mission long-cadence light curves. The ARC2 pipeline identifies and corrects any isolated discontinuities in the light curves and then removes trends common to many light curves. These trends are modelled using the publicly available co-trending basis vectors, within an (approximate) Bayesian framework with 'shrinkage' priors to minimize the risk of overfitting and the injection of any additional noise into the corrected light curves, while keeping any astrophysical signals intact. We show that the ARC2 pipeline's performance matches that of the standard Kepler PDC-MAP data products using standard noise metrics, and demonstrate its ability to preserve astrophysical signals using injection tests with simulated stellar rotation and planetary transit signals. Although it is not identical, the ARC2 pipeline can thus be used as an open-source alternative to PDC-MAP, whenever the ability to model the impact of the systematics removal process on other kinds of signal is important.

Testing Modified Newtonian Dynamics with Low Surface Brightness Galaxies: Rotation Curve FITS

NASA Astrophysics Data System (ADS)

de Blok, W. J. G.; McGaugh, S. S.

1998-11-01

We present modified Newtonian dynamics (MOND) fits to 15 rotation curves of low surface brightness (LSB) galaxies. Good fits are readily found, although for a few galaxies minor adjustments to the inclination are needed. Reasonable values for the stellar mass-to-light ratios are found, as well as an approximately constant value for the total (gas and stars) mass-to-light ratio. We show that the LSB galaxies investigated here lie on the one, unique Tully-Fisher relation, as predicted by MOND. The scatter on the Tully-Fisher relation can be completely explained by the observed scatter in the total mass-to-light ratio. We address the question of whether MOND can fit any arbitrary rotation curve by constructing a plausible fake model galaxy. While MOND is unable to fit this hypothetical galaxy, a normal dark-halo fit is readily found, showing that dark matter fits are much less selective in producing fits. The good fits to rotation curves of LSB galaxies support MOND, especially because these are galaxies with large mass discrepancies deep in the MOND regime.

Stochastic simulation of soil particle-size curves in heterogeneous aquifer systems through a Bayes space approach

NASA Astrophysics Data System (ADS)

Menafoglio, A.; Guadagnini, A.; Secchi, P.

2016-08-01

We address the problem of stochastic simulation of soil particle-size curves (PSCs) in heterogeneous aquifer systems. Unlike traditional approaches that focus solely on a few selected features of PSCs (e.g., selected quantiles), our approach considers the entire particle-size curves and can optionally include conditioning on available data. We rely on our prior work to model PSCs as cumulative distribution functions and interpret their density functions as functional compositions. We thus approximate the latter through an expansion over an appropriate basis of functions. This enables us to (a) effectively deal with the data dimensionality and constraints and (b) to develop a simulation method for PSCs based upon a suitable and well defined projection procedure. The new theoretical framework allows representing and reproducing the complete information content embedded in PSC data. As a first field application, we demonstrate the quality of unconditional and conditional simulations obtained with our methodology by considering a set of particle-size curves collected within a shallow alluvial aquifer in the Neckar river valley, Germany.

New limb-darkening coefficients for modeling binary star light curves

NASA Technical Reports Server (NTRS)

Van Hamme, W.

1993-01-01

We present monochromatic, passband-specific, and bolometric limb-darkening coefficients for a linear as well as nonlinear logarithmic and square root limb-darkening laws. These coefficients, including the bolometric ones, are needed when modeling binary star light curves with the latest version of the Wilson-Devinney light curve progam. We base our calculations on the most recent ATLAS stellar atmosphere models for solar chemical composition stars with a wide range of effective temperatures and surface gravitites. We examine how well various limb-darkening approximations represent the variation of the emerging specific intensity across a stellar surface as computed according to the model. For binary star light curve modeling purposes, we propose the use of a logarithmic or a square root law. We design our tables in such a manner that the relative quality of either law with respect to another can be easily compared. Since the computation of bolometric limb-darkening coefficients first requires monochromatic coefficients, we also offer tables of these coefficients (at 1221 wavelength values between 9.09 nm and 160 micrometer) and tables of passband-specific coefficients for commonly used photometric filters.

Development of a 3D Filling Model of Low-Pressure Die-Cast Aluminum Alloy Wheels

NASA Astrophysics Data System (ADS)

Duan, Jianglan; Maijer, Daan; Cockcroft, Steve; Reilly, Carl

2013-12-01

A two-phase computational fluid dynamics model of the low-pressure die-cast process for the production of A356 aluminum alloy wheels has been developed to predict the flow conditions during die filling. The filling model represents a 36-deg section of a production wheel, and was developed within the commercial finite-volume package, ANSYS CFX, assuming isothermal conditions. To fully understand the behavior of the free surface, a novel technique was developed to approximate the vent resistances as they impact on the development of a backpressure within the die cavity. The filling model was first validated against experimental data, and then was used to investigate the effects of venting conditions and pressure curves during die filling. It was found that vent resistance and vent location strongly affected die filling time, free surface topography, and air entrainment for a given pressure fill-curve. With regard to the pressure curve, the model revealed a strong relation between the pressure curve and the flow behavior in the hub, which is an area prone to defect formation.

Interactive contour delineation and refinement in treatment planning of image‐guided radiation therapy

PubMed Central

Zhou, Wu

2014-01-01

The accurate contour delineation of the target and/or organs at risk (OAR) is essential in treatment planning for image‐guided radiation therapy (IGRT). Although many automatic contour delineation approaches have been proposed, few of them can fulfill the necessities of applications in terms of accuracy and efficiency. Moreover, clinicians would like to analyze the characteristics of regions of interests (ROI) and adjust contours manually during IGRT. Interactive tool for contour delineation is necessary in such cases. In this work, a novel approach of curve fitting for interactive contour delineation is proposed. It allows users to quickly improve contours by a simple mouse click. Initially, a region which contains interesting object is selected in the image, then the program can automatically select important control points from the region boundary, and the method of Hermite cubic curves is used to fit the control points. Hence, the optimized curve can be revised by moving its control points interactively. Meanwhile, several curve fitting methods are presented for the comparison. Finally, in order to improve the accuracy of contour delineation, the process of the curve refinement based on the maximum gradient magnitude is proposed. All the points on the curve are revised automatically towards the positions with maximum gradient magnitude. Experimental results show that Hermite cubic curves and the curve refinement based on the maximum gradient magnitude possess superior performance on the proposed platform in terms of accuracy, robustness, and time calculation. Experimental results of real medical images demonstrate the efficiency, accuracy, and robustness of the proposed process in clinical applications. PACS number: 87.53.Tf PMID:24423846

Fractal structure of the interplanetary magnetic field

NASA Technical Reports Server (NTRS)

Burlaga, L. F.; Klein, L. W.

1985-01-01

Under some conditions, time series of the interplanetary magnetic field strength and components have the properties of fractal curves. Magnetic field measurements made near 8.5 AU by Voyager 2 from June 5 to August 24, 1981 were self-similar over time scales from approximately 20 sec to approximately 3 x 100,000 sec, and the fractal dimension of the time series of the strength and components of the magnetic field was D = 5/3, corresponding to a power spectrum P(f) approximately f sup -5/3. Since the Kolmogorov spectrum for homogeneous, isotropic, stationary turbulence is also f sup -5/3, the Voyager 2 measurements are consistent with the observation of an inertial range of turbulence extending over approximately four decades in frequency. Interaction regions probably contributed most of the power in this interval. As an example, one interaction region is discussed in which the magnetic field had a fractal dimension D = 5/3.

The Autoregressive Method: A Method of Approximating and Estimating Positive Functions

DTIC Science & Technology

1976-08-01

in drawing the curves, thanks to computer graphics. A few people ha’ very imaginatively pro- posed - td developed new ways of visualizing the data...k= -= it turns out that , , 0ki < 0 is a sufficient condition for all our k= -cc ( operations to be valid. Ii_ _ _ _ _ _ __ __ _ _ _ _ -106- We will

40 CFR 91.321 - NDIR analyzer calibration.

Code of Federal Regulations, 2010 CFR

2010-07-01

... curve for each range used as follows: (1) Zero the analyzer. (2) Span the analyzer to give a response of approximately 90 percent of full-scale chart deflection. (3) Recheck the zero response. If it has changed more... the form of equation (1) or (2). Include zero as a data point. Compensation for known impurities in...

Pharmacology of ketoconazole suspension in infants and children.

PubMed Central

Ginsburg, C M; McCracken, G H; Olsen, K

1983-01-01

The pharmacokinetics of ketoconazole administered as either a commercially prepared suspension or as a crushed tablet in applesauce were studied in 12 children. The mean peak plasma concentration of ketoconazole and the area under the plasma time-concentration curve were approximately twofold greater with the suspension than with the crushed tablets. PMID:6307138

Multispectral Analysis of Surface Wave (MASW) Analysis of Near-Surface Structure at Brady Hot Springs from Active Source and Ambient Noise Using a 8700-meter Distributed Acoustic Sensing (DAS) Array

NASA Astrophysics Data System (ADS)

Wang, H. F.; Lord, N. E.; Zeng, X.; Fratta, D.; Feigl, K. L.; Team, P.

2016-12-01

The Porotomo research team deployed 8700-meters of Distributed Acoustic Sensing (DAS) cable in a shallow trench on the surface and 400 meters down a borehole at Brady Hot Springs, Nevada in March 2016. The goal of the experiment was to detect changes in geophysical properties associated with hydrologic changes. The DAS cable occupied a natural laboratory of 1500-by-500-by-400-meters overlying a commercial, geothermal field operated by Ormat Technologies. The DAS cable was laid out in three parallel zig-zag lines with line segments approximately 120-meters in length. A large Vibroseis truck (T-Rex) provided the seismic source with a sweep frequency between 5 and 80 Hz over 20 seconds. Over the 15 days of the experiment, the Vibroseis truck re-occupied approximately 250 locations outside and within the array days while changes were made in water reinjection from the power plant into wells in the field. At each source location, one vertical and two orthogonal horizontal modes were excited. Dispersion curves were constructed using MASW and a Vibroseis source location approximately in line with each DAS cable segment or from ambient noise correlation functions. Representative fence diagrams of S-wave profiles were constructed by inverting the dispersion curves obtained for several different line segments.

Linear and non-linear kinetics in the synthesis and degradation of acrylamide in foods and model systems.

PubMed

Corradini, Maria G; Peleg, Micha

2006-01-01

Isothermal acrylamide formation in foods and asparagine-glucose model systems has ubiquitous features. On a time scale of about 60 min, at temperatures in the approximate range of 120-160 degrees C, the acrylamide concentration-time curve has a characteristic sigmoid shape whose asymptotic level and steepness increases with temperature while the time that corresponds to the inflection point decreases. In the approximate range of 160-200 degrees C, the curve has a clear peak, whose onset, height, width and degree of asymmetry depend on the system's composition and temperature. The synthesis-degradation of acrylamide in model systems has been recently described by traditional kinetic models. They account for the intermediate stages of the process and the fate of reactants involved at different levels of scrutiny. The resulting models have 2-6 rate constants, accounting for both the generation and elimination of the acrylamide. Their temperature dependence has been assumed to obey the Arrhenius equation, i.e., each step in the reaction was considered as having a fixed energy of activation. A proposed alternative is constructing the concentration curve by superimposing a Fermian decay term on a logistic growth function. The resulting model, which is not unique, has five parameters: a hypothetical uninterrupted generation-level, two steepness parameters; of the concentration climbs and fall and two time characteristics; of the acrylamide synthesis and elimination. According to this model, peak concentration is observed only when the two time constants are comparable. The peak's shape and height are determined by the gap between the two time constants and the relative magnitudes of the two "rate" parameters. The concept can be extended to create models of non-isothermal acrylamide formation. The basic assumption, which is yet to be verified experimentally, is that the momentary rate of the acrylamide synthesis or degradation is the isothermal rate at the momentary temperature, at a time that corresponds to its momentary concentration. The theoretical capabilities of a model of this kind are demonstrated with computer simulations. If the described model is correct, then by controlling temperature history, it is possible to reduce the acrylamide while still accomplishing much of the desirable effects of a heat process.

Geometric Model for a Parametric Study of the Blended-Wing-Body Airplane

NASA Technical Reports Server (NTRS)

Mastin, C. Wayne; Smith, Robert E.; Sadrehaghighi, Ideen; Wiese, Micharl R.

1996-01-01

A parametric model is presented for the blended-wing-body airplane, one concept being proposed for the next generation of large subsonic transports. The model is defined in terms of a small set of parameters which facilitates analysis and optimization during the conceptual design process. The model is generated from a preliminary CAD geometry. From this geometry, airfoil cross sections are cut at selected locations and fitted with analytic curves. The airfoils are then used as boundaries for surfaces defined as the solution of partial differential equations. Both the airfoil curves and the surfaces are generated with free parameters selected to give a good representation of the original geometry. The original surface is compared with the parametric model, and solutions of the Euler equations for compressible flow are computed for both geometries. The parametric model is a good approximation of the CAD model and the computed solutions are qualitatively similar. An optimal NURBS approximation is constructed and can be used by a CAD model for further refinement or modification of the original geometry.

On the Angular Dependence of the Vicinal Fluorine-Fluorine Coupling Constant in 1,2-Difluoroethane:  Deviation from a Karplus-like Shape.

PubMed

Provasi, Patricio F; Sauer, Stephan P A

2006-07-01

The angular dependence of the vicinal fluorine-fluorine coupling constant, (3)JFF, for 1,2-difluoroethane has been investigated with several polarization propagator methods. (3)JFF and its four Ramsey contributions were calculated using the random phase approximation (RPA), its multiconfigurational generalization, and both second-order polarization propagator approximations (SOPPA and SOPPA(CCSD)), using locally dense basis sets. The geometries were optimized for each dihedral angle at the level of density functional theory using the B3LYP functional and fourth-order Møller-Plesset perturbation theory. The resulting coupling constant curves were fitted to a cosine series with 8 coefficients. Our results are compared with those obtained previously and values estimated from experiment. It is found that the inclusion of electron correlation in the calculation of (3)JFF reduces the absolute values. This is mainly due to changes in the FC contribution, which for dihedral angles around the trans conformation even changes its sign. This sign change is responsible for the breakdown of the Karplus-like curve.

An entropy stable nodal discontinuous Galerkin method for the two dimensional shallow water equations on unstructured curvilinear meshes with discontinuous bathymetry

NASA Astrophysics Data System (ADS)

Wintermeyer, Niklas; Winters, Andrew R.; Gassner, Gregor J.; Kopriva, David A.

2017-07-01

We design an arbitrary high-order accurate nodal discontinuous Galerkin spectral element approximation for the non-linear two dimensional shallow water equations with non-constant, possibly discontinuous, bathymetry on unstructured, possibly curved, quadrilateral meshes. The scheme is derived from an equivalent flux differencing formulation of the split form of the equations. We prove that this discretization exactly preserves the local mass and momentum. Furthermore, combined with a special numerical interface flux function, the method exactly preserves the mathematical entropy, which is the total energy for the shallow water equations. By adding a specific form of interface dissipation to the baseline entropy conserving scheme we create a provably entropy stable scheme. That is, the numerical scheme discretely satisfies the second law of thermodynamics. Finally, with a particular discretization of the bathymetry source term we prove that the numerical approximation is well-balanced. We provide numerical examples that verify the theoretical findings and furthermore provide an application of the scheme for a partial break of a curved dam test problem.

Intensity of hydrostimulation for the induction of root hydrotropism and its sensing by the root cap

NASA Technical Reports Server (NTRS)

Takahashi, H.; Scott, T. K.

1993-01-01

Roots of Pisum sativum L. and Zea mays L. were exposed to different moisture gradients established by placing both wet cheesecloth (hydrostimulant) and saturated aqueous solutions of various salts in a closed chamber. Atmospheric conditions with different relative humidity (RH) in a range between 98 and 86% RH were obtained at root level, 2 to 3mm from the water-saturated hydrostimulant. Roots of Silver Queen corn placed vertically with the tips down curved sideways toward the hydrostimulant in response to approximately 94% RH but did not respond positively to RH higher than approximately 95%. The positive hydrotropic response increased linearly as RH was lowered from 95 to 90%. A maximum response was observed at RH between 90 and 86%. However, RH required for the induction of hydrotropism as well as the responsiveness differed among plant species used; gravitropically sensitive roots appeared to require a somewhat greater moisture gradient for the induction of hydrotropism. Decapped roots of corn failed to curve hydrotropically, suggesting the root cap as a major site of hydrosensing.

Self-consistent field calculations of conductance through conjugated molecules at finite bias

NASA Astrophysics Data System (ADS)

Paulsson, Magnus; Stafström, Sven

2001-03-01

Conductance through conjugated molecules have previously been calculated for a large number of systems using the Landauer formula but only a few calculations have included charging effects. In this study we present calculations in the mean field approximation of the conductance of metal-molecule-metal systems using two different kinds of molecules for a large number of configurations and applied biases. The molecules are described in the Pariser-Parr Pople model. Current-voltage (I-V) characteristics and charge distribution of the molecule connected by one dimensional leads to reservoirs is solved within the Hartree-Fock approximation. Charging of the molecule occurs when the chemical potential of the reservoirs approach the resonant tunneling levels. The ensuing potential difference, due to the charging, shifts the tunneling peaks which affects the I-V curves considerably. Asymmetrical interaction with the metal leads, e.g. molecule on a metal surface contacted with an STM-tip, also give asymmetrical I-V curves where the potential of the molecule is shown to more closely follow the potential of the surface. Negative differential conductance is discussed in systems consisting of two weakly coupled molecules.

Quadratic canonical transformation theory and higher order density matrices.

PubMed

Neuscamman, Eric; Yanai, Takeshi; Chan, Garnet Kin-Lic

2009-03-28

Canonical transformation (CT) theory provides a rigorously size-extensive description of dynamic correlation in multireference systems, with an accuracy superior to and cost scaling lower than complete active space second order perturbation theory. Here we expand our previous theory by investigating (i) a commutator approximation that is applied at quadratic, as opposed to linear, order in the effective Hamiltonian, and (ii) incorporation of the three-body reduced density matrix in the operator and density matrix decompositions. The quadratic commutator approximation improves CT's accuracy when used with a single-determinant reference, repairing the previous formal disadvantage of the single-reference linear CT theory relative to singles and doubles coupled cluster theory. Calculations on the BH and HF binding curves confirm this improvement. In multireference systems, the three-body reduced density matrix increases the overall accuracy of the CT theory. Tests on the H(2)O and N(2) binding curves yield results highly competitive with expensive state-of-the-art multireference methods, such as the multireference Davidson-corrected configuration interaction (MRCI+Q), averaged coupled pair functional, and averaged quadratic coupled cluster theories.

Qualitatively different coding of symbolic and nonsymbolic numbers in the human brain.

PubMed

Lyons, Ian M; Ansari, Daniel; Beilock, Sian L

2015-02-01

Are symbolic and nonsymbolic numbers coded differently in the brain? Neuronal data indicate that overlap in numerical tuning curves is a hallmark of the approximate, analogue nature of nonsymbolic number representation. Consequently, patterns of fMRI activity should be more correlated when the representational overlap between two numbers is relatively high. In bilateral intraparietal sulci (IPS), for nonsymbolic numbers, the pattern of voxelwise correlations between pairs of numbers mirrored the amount of overlap in their tuning curves under the assumption of approximate, analogue coding. In contrast, symbolic numbers showed a flat field of modest correlations more consistent with discrete, categorical representation (no systematic overlap between numbers). Directly correlating activity patterns for a given number across formats (e.g., the numeral "6" with six dots) showed no evidence of shared symbolic and nonsymbolic number-specific representations. Overall (univariate) activity in bilateral IPS was well fit by the log of the number being processed for both nonsymbolic and symbolic numbers. IPS activity is thus sensitive to numerosity regardless of format; however, the nature in which symbolic and nonsymbolic numbers are encoded is fundamentally different. © 2014 Wiley Periodicals, Inc.

Maximum safe speed estimation using planar quintic Bezier curve with C2 continuity

NASA Astrophysics Data System (ADS)

Ibrahim, Mohamad Fakharuddin; Misro, Md Yushalify; Ramli, Ahmad; Ali, Jamaludin Md

2017-08-01

This paper describes an alternative way in estimating design speed or the maximum speed allowed for a vehicle to drive safely on a road using curvature information from Bezier curve fitting on a map. We had tested on some route in Tun Sardon Road, Balik Pulau, Penang, Malaysia. We had proposed to use piecewise planar quintic Bezier curve while satisfying the curvature continuity between joined curves in the process of mapping the road. By finding the derivatives of quintic Bezier curve, the value of curvature was calculated and design speed was derived. In this paper, a higher order of Bezier Curve had been used. A higher degree of curve will give more freedom for users to control the shape of the curve compared to curve in lower degree.

Schroth Physiotherapeutic Scoliosis-Specific Exercises Added to the Standard of Care Lead to Better Cobb Angle Outcomes in Adolescents with Idiopathic Scoliosis – an Assessor and Statistician Blinded Randomized Controlled Trial

PubMed Central

Parent, Eric C.; Khodayari Moez, Elham; Hedden, Douglas M.; Hill, Douglas L.; Moreau, Marc; Lou, Edmond; Watkins, Elise M.; Southon, Sarah C.

2016-01-01

Background The North American non-surgical standard of care for adolescent idiopathic scoliosis (AIS) includes observation and bracing, but not exercises. Schroth physiotherapeutic scoliosis-specific exercises (PSSE) showed promise in several studies of suboptimal methodology. The Scoliosis Research Society calls for rigorous studies supporting the role of exercises before including it as a treatment recommendation for scoliosis. Objectives To determine the effect of a six-month Schroth PSSE intervention added to standard of care (Experimental group) on the Cobb angle compared to standard of care alone (Control group) in patients with AIS. Methods Fifty patients with AIS aged 10–18 years, with curves of 10°-45° and Risser grade 0–5 were recruited from a single pediatric scoliosis clinic and randomized to the Experimental or Control group. Outcomes included the change in the Cobb angles of the Largest Curve and Sum of Curves from baseline to six months. The intervention consisted of a 30–45 minute daily home program and weekly supervised sessions. Intention-to-treat and per protocol linear mixed effects model analyses are reported. Results In the intention-to-treat analysis, after six months, the Schroth group had significantly smaller Largest Curve than controls (-3.5°, 95% CI -1.1° to -5.9°, p = 0.006). Likewise, the between-group difference in the square root of the Sum of Curves was -0.40°, (95% CI -0.03° to -0.8°, p = 0.046), suggesting that an average patient with 51.2° at baseline, will have a 49.3° Sum of Curves at six months in the Schroth group, and 55.1° in the control group with the difference between groups increasing with severity. Per protocol analyses produced similar, but larger differences: Largest Curve = -4.1° (95% CI -1.7° to -6.5°, p = 0.002) and Sum of Curves=−0.5° (95% CI -0.8 to 0.2, p = 0.006). Conclusion Schroth PSSE added to the standard of care were superior compared to standard of care alone for reducing the curve severity in patients with AIS. Trial Registration NCT01610908 PMID:28033399

Supplementing suckling rats with whey protein concentrate modulates the immune response and ameliorates rat rotavirus-induced diarrhea.

PubMed

Pérez-Cano, Francisco J; Marín-Gallén, Silvia; Castell, Margarida; Rodríguez-Palmero, María; Rivero, Montserrat; Castellote, Cristina; Franch, Angels

2008-12-01

Group A rotaviruses (RV) are the most common causative agents of acute gastroenteritis in children <2 y. The present study was designed to establish the effect of a bovine whey protein concentrate (WPC) in a RV infection model in suckling rats. From d 3 of life, suckling Lewis rats received daily supplements of WPC, WPC plus lactoferrin (LF), standard infant formula (SIF), or water (RV-infected group and an untreated, uninfected reference group). On d 8 of life, heterologous simian RV SA-11 was inoculated orally in the WPC-RV, WPC+LF-RV, SIF-RV, and RV groups. WPC and WPC+LF reduced diarrhea incidence from approximately 90% in RV group to approximately 60% in WPC-RV and WPC+LF-RV groups (P < 0.05), whereas the area under the curve (AUC) of severity along time diminished from approximately 10 AUC in the RV group to approximately 6 AUC in both supplemented groups (P < 0.05). Serum levels of anti-RV antibodies, splenocyte proliferation, and interferon-gamma secretion after specific stimulation were significantly lower in the WPC-RV and WPC+LF-RV groups than in the SIF-RV and RV groups. In the intraepithelial intestinal compartment, RV infection increased the proportion of typical mucosal T cells (IE-T CD8alphaalpha+); however, this modification was controlled by WPC and WPC+LF supplementation. In general, for most of the parameters studied, the SIF-RV and RV groups did not differ. In summary, daily supplementation with WPC or WPC+LF in early life considerably reduces the severity of RV-induced acute gastroenteritis and modulates the immune response against the pathogen.

An accurate solution of the gas lubricated, flat sector thrust bearing

NASA Technical Reports Server (NTRS)

Etsion, I.; Fleming, D. P.

1976-01-01

A flat sector shaped pad geometry for gas lubricated thrust bearings is analyzed considering both pitch and roll angles of the pad and the true film thickness distribution. Maximum load capacity is achieved when the pad is tilted so as to create a uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves. A comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Analysis of the gas-lubricated flat-sector-pad thrust bearing

NASA Technical Reports Server (NTRS)

Etsion, I.

1976-01-01

A flat sector-shaped pad geometry for a gas-lubricated thrust bearing is analyzed considering both the pitch and roll of the pad. It is shown that maximum load capacity is achieved when the pad is tilted so as to create uniform minimum film thickness along the pad trailing edge. Performance characteristics for various geometries and operating conditions of gas thrust bearings are presented in the form of design curves, and a comparison is made with the rectangular slider approximation. It is found that this approximation is unsafe for practical design, since it always overestimates load capacity.

Composite prepreg application device

NASA Technical Reports Server (NTRS)

Sandusky, Donald A. (Inventor); Marchello, Joseph M. (Inventor)

1995-01-01

A heated shoe and cooled pressure roller assembly for composite prepreg application is provided. The shoe assembly includes a heated forward contact surface having a curved pressure surface. The following cooled roller provides a continuous pressure to the thermoplastic while reducing the temperature to approximately 5 C below glass transition temperature. Electric heating coils inside the forward portion of the shoe heat a thermoplastic workpiece to approximately 100 C above the glass transition. Immediately following the heated contact surface, a cooled roller cools the work. The end sharpened shape of the heated shoe trailing edge tends to prevent slag buildup and maintain a uniform, relaxed stress fabrication.

Formation of curved micrometer-sized single crystals.

PubMed

Koifman Khristosov, Maria; Kabalah-Amitai, Lee; Burghammer, Manfred; Katsman, Alex; Pokroy, Boaz

2014-05-27

Crystals in nature often demonstrate curved morphologies rather than classical faceted surfaces. Inspired by biogenic curved single crystals, we demonstrate that gold single crystals exhibiting curved surfaces can be grown with no need of any fabrication steps. These single crystals grow from the confined volume of a droplet of a eutectic composition melt that forms via the dewetting of nanometric thin films. We can control their curvature by controlling the environment in which the process is carried out, including several parameters, such as the contact angle and the curvature of the drops, by changing the surface tension of the liquid drop during crystal growth. Here we present an energetic model that explains this phenomenon and predicts why and under what conditions crystals will be forced to grow with the curvature of the microdroplet even though the energetic state of a curved single crystal is very high.

Compression-based integral curve data reuse framework for flow visualization

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

Hong, Fan; Bi, Chongke; Guo, Hanqi

Currently, by default, integral curves are repeatedly re-computed in different flow visualization applications, such as FTLE field computation, source-destination queries, etc., leading to unnecessary resource cost. We present a compression-based data reuse framework for integral curves, to greatly reduce their retrieval cost, especially in a resource-limited environment. In our design, a hierarchical and hybrid compression scheme is proposed to balance three objectives, including high compression ratio, controllable error, and low decompression cost. Specifically, we use and combine digitized curve sparse representation, floating-point data compression, and octree space partitioning to adaptively achieve the objectives. Results have shown that our data reusemore » framework could acquire tens of times acceleration in the resource-limited environment compared to on-the-fly particle tracing, and keep controllable information loss. Moreover, our method could provide fast integral curve retrieval for more complex data, such as unstructured mesh data.« less

The organization of LH2 complexes in membranes from Rhodobacter sphaeroides.

PubMed

Olsen, John D; Tucker, Jaimey D; Timney, John A; Qian, Pu; Vassilev, Cvetelin; Hunter, C Neil

2008-11-07

The mapping of the photosynthetic membrane of Rhodobacter sphaeroides by atomic force microscopy (AFM) revealed a unique organization of arrays of dimeric reaction center-light harvesting I-PufX (RC-LH1-PufX) core complexes surrounded and interconnected by light-harvesting LH2 complexes (Bahatyrova, S., Frese, R. N., Siebert, C. A., Olsen, J. D., van der Werf, K. O., van Grondelle, R., Niederman, R. A., Bullough, P. A., Otto, C., and Hunter, C. N. (2004) Nature 430, 1058-1062). However, membrane regions consisting solely of LH2 complexes were under-represented in these images because these small, highly curved areas of membrane rendered them difficult to image even using gentle tapping mode AFM and impossible with contact mode AFM. We report AFM imaging of membranes prepared from a mutant of R. sphaeroides, DPF2G, that synthesizes only the LH2 complexes, which assembles spherical intracytoplasmic membrane vesicles of approximately 53 nm diameter in vivo. By opening these vesicles and adsorbing them onto mica to form small, < or =120 nm, largely flat sheets we have been able to visualize the organization of these LH2-only membranes for the first time. The transition from highly curved vesicle to the planar sheet is accompanied by a change in the packing of the LH2 complexes such that approximately half of the complexes are raised off the mica surface by approximately 1 nm relative to the rest. This vertical displacement produces a very regular corrugated appearance of the planar membrane sheets. Analysis of the topographs was used to measure the distances and angles between the complexes. These data are used to model the organization of LH2 complexes in the original, curved membrane. The implications of this architecture for the light harvesting function and diffusion of quinones in native membranes of R. sphaeroides are discussed.

The Achromatic Light Curve of the Optical Afterglow of GRB 030226 at a Redshift of z Approximately 2

NASA Technical Reports Server (NTRS)

Klose, S.; Greiner, J.; Rau, A.; Henden, A. A.; Hartmann, D. H.; Zeh, A.; Masetti, N.; Guenther, E.; Stecklum, B.; Lindsay, K.

2003-01-01

Abstract. We report on optical and near-infrared (NIR) follow-up observations of the afterglow of GRB 030226, mainly performed with the telescopes at ESO La Silla and Paranal, with additional data obtained at other places. Our first observations started 0.2 days after the burst when the afterglow was at a magnitude of R approximately equal to 19 . One week later the magnitude of the afterglow had fallen to R=25, and at two weeks after the burst it could no longer be detected (R > 26). Our VLT blueband spectra show two absorption line systems at redshifts z = 1.962 +/- 0.001 and at z = 1.986 +/- 0.001, placing the redshift of the burster close to 2. Within our measurement errors no evidence for variations in the line strengths has been found between 0.2 and 1.2 days after the burst. An overabundance of alpha-group elements might indicate that the burst occurred in a chemically young interstellar region shaped by the nucleosynthesis from type II supernovae. The spectral slope of the afterglow shows no signs for cosmic dust along the line of sight in the GRB host galaxy, which itself remained undetected (R > 26.2). At the given redshift no supernova component affected the light from the GRB afterglow, so that the optical transient was essentially only powered by the radiation from the GRB fireball, allowing for a detailed investigation of the color evolution of the afterglow light. In our data set no obvious evidence for color changes has been found before, during, or after the smooth break in the light curve approximately 1 day after the burst. In comparison with investigations by others, our data favor the interpretation that the afterglow began to develop into a homogeneous interstellar medium before the break in the light curve became apparent.

Traveltime and dispersion in the Potomac River, Cumberland, Maryland, to Washington, D.C.

USGS Publications Warehouse

Taylor, Kenneth R.; James, Robert W.; Helinsky, Bernard M.

1985-01-01

A travel-time and dispersion study using rhodamine dye was conducted on the Potomac River between Cumberland, Maryland, and Washington, D.C., a distance of 189 miles. The flow during the study was at approximately the 90-percent flow-duration level. A similar study was conducted by Wilson and Forrest in 1964 at a flow duration of approximately 60 percent. The two sets of data were used to develop a generalized procedure for predicting travel-times and downstream concentrations resulting from spillage of water-soluble substances at any point along the river. The procedure will allow the user to calculate travel-time and concentration data for almost any spillage problem that occurs during periods of relatively steady flow between 50- and 95-percent flow duration. A new procedure for calculating unit peak concentration was derived. The new procedure depends on an analogy between a time-concentration curve and a scalene triangle. As a result of this analogy, the unit peak concentration can be expressed in terms of the length of the _lye or contaminant cloud. The new procedure facilitates the calculation of unit peak concentration for long reaches of river. Previously, there was no way to link unit peak concentration curves for studies in which the river was divided into subreaches for study. Variable dispersive characteristics caused mainly by low-head dams precluded useful extrapolation of the unit peak-concentration attenuation curves, as has been done in previous studies. The procedure is applied to a hypothetical situation in which 20,000 pounds of contaminant is spilled at a railroad crossing at Magnolia, West Virginia. The times required for the leading edge, the peak concentration, and the trailing edge of the contaminant cloud to reach Point of Rocks, Maryland (110 river miles downstream), are 295, 375, and 540 hours respectively, during a period when flow is at the 80-percent flow-duration level. The peak conservative concentration would be approximately 340 micrograms per liter at Point of Rocks.

Day-night fluctuation of pulse oximetry: an exploratory study in pediatric inpatients.

PubMed

Vargas, Mario H; Heyaime-Lalane, Jorge; Pérez-Rodríguez, Liliana; Zúñiga-Vázquez, Guillermo; Furuya, María Elena Y

2008-01-01

Pulse oximetry is a simple and non-invasive procedure widely used nowadays in the clinical practice. However, it is unclear if SpO2 values are constant throughout the 24 hours of the day or have periodic fluctuations. In the present study we evaluated if progressive day-night variations of SpO, values occur in children. Pulse oximetry (Nonin 2500) was carried out approximately every 2 hours during a 24-hours period in pediatric patients hospitalized due to different diseases but without acute or chronic respiratory diseases. Measurements were analyzed through the cosinor method (sinusoidal curve fitting). A total of 131 patients (23 days to 16 years old) were studied. A sinusoidal fitting of the SpO2 values was accomplished in 84.7% of children. According to these curves, maximal SpO2 values occurred in the late afternoon [4:53 PM (3:49-5:32 PM), median (quartile 1-quartile 3)], while minimal values appeared in the first hours of the day [3:06 AM (2:12-4:08 AM)]. This pattern was the same in sleeping or awake children. More than half of these sinusoidal curves had a period near to 24 hours (between 20 and 28 hours). An additional finding was that maximal and minimal SpO2 values diminished with age (approximately 0.15 and approximately 0.13% SpO2 per year, respectively). In children less than six years old 5th percentile of SpO2 values were 93.8% in the late afternoon and 89.8% in the early hours of the day, while corresponding figures for older children were 91.0% and 88.5%, respectively. Our results suggested that, regardless of the sleep influence, in most children the SpO2 follows a progressive fluctuation during a 24-hours cycle, a pattern which is suggestive of a circadian rhythm. A prospective study in healthy children is warranted.

Laminar and turbulent surgical plume characteristics generated from curved- and straight-blade laparoscopic ultrasonic dissectors.

PubMed

Kim, Fernando J; Sehrt, David; Pompeo, Alexandre; Molina, Wilson R

2014-05-01

To characterize laparoscopic ultrasonic dissector surgical plume emission (laminar or turbulent) and investigate plume settlement time between curved and straight blades. A straight and a curved blade laparoscopic ultrasonic dissector were activated on tissue and in a liquid environment to evaluate plume emission. Plume emission was characterized as either laminar or turbulent and the plume settlement times were compared. Devices were then placed in liquid to observed consistency in the fluid disruption. Two types of plume emission were identified generating different directions of plume: laminar flow causes minimal visual obstruction by directing the aerosol downwards, while turbulent flow directs plume erratically across the cavity. Laminar plume dissipates immediately while turbulent plume reaches a second maximum obstruction approximately 0.3 s after activation and clears after 2 s. Turbulent plume was observed with the straight blade in 10 % of activations, and from the curved blade in 47 % of activations. The straight blade emitted less obstructive plume. Turbulent flow is disruptive to laparoscopic visibility with greater field obstruction and requires longer settling than laminar plume. Ultrasonic dissectors with straight blades have more consistent oscillations and generate more laminar flow compared with curved blades. Surgeons may avoid laparoscope smearing from maximum plume generation depending on blade geometry.

Extended source effect on microlensing light curves by an Ellis wormhole

NASA Astrophysics Data System (ADS)

Tsukamoto, Naoki; Gong, Yungui

2018-04-01

We can survey an Ellis wormhole which is the simplest Morris-Thorne wormhole in our Galaxy with microlensing. The light curve of a point source microlensed by the Ellis wormhole shows approximately 4% demagnification while the total magnification of images lensed by a Schwarzschild lens is always larger than unity. We investigate an extended source effect on the light curves microlensed by the Ellis wormhole. We show that the depth of the gutter of the light curves of an extended source is smaller than the one of a point source since the magnified part of the extended source cancels the demagnified part out. We can, however, distinguish between the light curves of the extended source microlensed by the Ellis wormhole and the ones by the Schwarzschild lens in their shapes even if the size of the source is a few times larger than the size of an Einstein ring on a source plane. If the relative velocity of a star with the radius of 1 06 km at 8 kpc in the bulge of our Galaxy against an observer-lens system is smaller than 10 km /s on a source plane, we can detect microlensing of the star lensed by the Ellis wormhole with the throat radius of 1 km at 4 kpc.

A retrospective analysis of compact fluorescent lamp experience curves and their correlations to deployment programs

DOE PAGES

Smith, Sarah Josephine; Wei, Max; Sohn, Michael D.

2016-09-17

Experience curves are useful for understanding technology development and can aid in the design and analysis of market transformation programs. Here, we employ a novel approach to create experience curves, to examine both global and North American compact fluorescent lamp (CFL) data for the years 1990–2007. We move away from the prevailing method of fitting a single, constant, exponential curve to data and instead search for break points where changes in the learning rate may have occurred. Our analysis suggests a learning rate of approximately 21% for the period of 1990–1997, and 51% and 79% in global and North Americanmore » datasets, respectively, after 1998. We use price data for this analysis; therefore our learning rates encompass developments beyond typical “learning by doing”, including supply chain impacts such as market competition. We examine correlations between North American learning rates and the initiation of new programs, abrupt technological advances, and economic and political events, and find an increased learning rate associated with design advancements and federal standards programs. Our findings support the use of segmented experience curves for retrospective and prospective technology analysis, and may imply that investments in technology programs have contributed to an increase of the CFL learning rate.« less

A retrospective analysis of compact fluorescent lamp experience curves and their correlations to deployment programs

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

Smith, Sarah Josephine; Wei, Max; Sohn, Michael D.

Experience curves are useful for understanding technology development and can aid in the design and analysis of market transformation programs. Here, we employ a novel approach to create experience curves, to examine both global and North American compact fluorescent lamp (CFL) data for the years 1990–2007. We move away from the prevailing method of fitting a single, constant, exponential curve to data and instead search for break points where changes in the learning rate may have occurred. Our analysis suggests a learning rate of approximately 21% for the period of 1990–1997, and 51% and 79% in global and North Americanmore » datasets, respectively, after 1998. We use price data for this analysis; therefore our learning rates encompass developments beyond typical “learning by doing”, including supply chain impacts such as market competition. We examine correlations between North American learning rates and the initiation of new programs, abrupt technological advances, and economic and political events, and find an increased learning rate associated with design advancements and federal standards programs. Our findings support the use of segmented experience curves for retrospective and prospective technology analysis, and may imply that investments in technology programs have contributed to an increase of the CFL learning rate.« less

[Value of Immunohistochemical Methods in Detecting EML4-ALK Fusion Mutations: A Meta-analysis].

PubMed

Liu, Chang; Cai, Lu; Zhong, Diansheng; Wang, Jing

2016-01-01

The fusion between echinoderm microtubule-associated protein 4 (EML4) and anaplastic lymphatic tumor kinase (ALK) rearrangement is present in approximately 5% of non-small cell lung cancer (NSCLC) patients. It has been regarded as another new target gene after epidermal growth factor receptor (EGFR) and K-ras. Figures showed that the disease control rate could reach up to 80% in NSCLC patients with EML4-ALK fusion gene after treated with ALK inhibitors. Thus, exploring an accurate and rapid detecting method is the key in screening NSCLC patients with EML4-ALK expressions. The aim of this study is to analyze the specificity and sensitivity of IHC in detecting EML4-ALK fusion mutations. To evaluate the accuracy and clinical value of this method, and then provide basis for individual molecular therapy of NSCLC patients. Using Pubmed database to search all documents required. The deadline of retrieval was February 25, 2015. Then further screening the articles according to the inclusion and exclusion criteria. Using diagnostic test meta-analysis methods to analyze the sensitivity and specificity of the immunohistochemistry (IHC) method compared with fluorescence in situ hybridization (FISH) method. Eleven literatures were added into the meta analysis, there were 3,234 of total cases. The diagnostic odds ratio (DOR) was 1,135.00 (95%CI: 337.10-3,821.46); the area under curve (AUC) of summary receiver operating characteristic curve (SROC) curve was 0.992,3 (SEAUC=0.003,2), the Q* was 0.964,4 (SEQ*=0.008,7). Immunohistochemical detection of EML4-ALK fusion gene mutation with specific antibody is feasible. It has high sensitivity and specificity. IHC can be a simple and rapid way in screening EML4-ALK fusion gene mutation and exhibits important clinical values.

Measurement of Moisture Sorption Isotherm by DVS Hydrosorb

NASA Astrophysics Data System (ADS)

Kurniawan, Y. R.; Purwanto, Y. A.; Purwanti, N.; Budijanto, S.

2018-05-01

Artificial rice made from corn flour, sago, glycerol monostearate, vegetable oil, water and jelly powder was developed by extrusion method through the process stages of material mixing, extrusion, drying, packaging and storage. Sorption isotherm pattern information on food ingredients used to design and optimize the drying process, packaging, storage. Sorption isotherm of water of artificial rice was measured using humidity generating method with Dynamic Vapor Sorption device that has an advantage of equilibration time is about 10 to 100 times faster than saturated salt slurry method. Relative humidity modification technique are controlled automatically by adjusting the proportion of mixture of dry air and water saturated air. This paper aims to develop moisture sorption isotherm using the Hydrosorb 1000 Water Vapor Sorption Analyzer. Sample preparation was conducted by degassing sample in a heating mantle of 65°C. Analysis parameters need to be fulfilled were determination of Po, sample data, selection of water activity points, and equilibrium conditions. The selected analytical temperatures were 30°C and 45°C. Analysis lasted for 45 hours and curves of adsorption and desorption were obtained. Selected bottom point of water activity 0.05 at 30°C and 45°C yielded adsorbed mass of 0.1466 mg/g and 0.3455 mg/g, respectively, whereas selected top water activity point 0.95 at 30°C and 45°C yielded adsorbed mass of 190.8734 mg/g and 242.4161mg/g, respectively. Moisture sorption isotherm measurements of articial rice made from corn flour at temperature of 30°C and 45°C using Hydrosorb showed that the moisture sorption curve approximates sigmoid-shaped type II curve commonly found in corn-based foodstuffs (high- carbohydrate).

Poster — Thur Eve — 03: Application of the non-negative matrix factorization technique to [{sup 11}C]-DTBZ dynamic PET data for the early detection of Parkinson's disease

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

Lee, Dong-Chang; Jans, Hans; McEwan, Sandy

2014-08-15

In this work, a class of non-negative matrix factorization (NMF) technique known as alternating non-negative least squares, combined with the projected gradient method, is used to analyze twenty-five [{sup 11}C]-DTBZ dynamic PET/CT brain data. For each subject, a two-factor model is assumed and two factors representing the striatum (factor 1) and the non-striatum (factor 2) tissues are extracted using the proposed NMF technique and commercially available factor analysis software “Pixies”. The extracted factor 1 and 2 curves represent the binding site of the radiotracer and describe the uptake and clearance of the radiotracer by soft tissues in the brain, respectively.more » The proposed NMF technique uses prior information about the dynamic data to obtain sample time-activity curves representing the striatum and the non-striatum tissues. These curves are then used for “warm” starting the optimization. Factor solutions from the two methods are compared graphically and quantitatively. In healthy subjects, radiotracer uptake by factors 1 and 2 are approximately 35–40% and 60–65%, respectively. The solutions are also used to develop a factor-based metric for the detection of early, untreated Parkinson's disease. The metric stratifies healthy subjects from suspected Parkinson's patients (based on the graphical method). The analysis shows that both techniques produce comparable results with similar computational time. The “semi-automatic” approach used by the NMF technique allows clinicians to manually set a starting condition for “warm” starting the optimization in order to facilitate control and efficient interaction with the data.« less

Physical growth of the shuar: Height, Weight, and BMI references for an indigenous amazonian population.

PubMed

Urlacher, Samuel S; Blackwell, Aaron D; Liebert, Melissa A; Madimenos, Felicia C; Cepon-Robins, Tara J; Gildner, Theresa E; Snodgrass, J Josh; Sugiyama, Lawrence S

2016-01-01

Information concerning physical growth among small-scale populations remains limited, yet such data are critical to local health efforts and to foster basic understandings of human life history and variation in childhood development. Using a large dataset and robust modeling methods, this study aims to describe growth from birth to adulthood among the indigenous Shuar of Amazonian Ecuador. Mixed-longitudinal measures of height, weight, and body mass index (BMI) were collected from Shuar participants (n = 2,463; age: 0-29 years). Centile growth curves and tables were created for each anthropometric variable of interest using Generalized Additive Models for Location, Scale, and Shape (GAMLSS). Pseudo-velocity and Lambda-Mu-Sigma curves were generated to further investigate Shuar patterns of growth and to facilitate comparison with United States Center for Disease Control and Prevention and multinational World Health Organization growth references. The Shuar are small throughout life and exhibit complex patterns of growth that differ substantially from those of international references. Similar to other Amazonians, Shuar growth in weight compares more favorably to references than growth in height, resulting in BMI curves that approximate international medians. Several additional characteristics of Shuar development are noteworthy, including large observed variation in body size early in life, significant infant growth faltering, extended male growth into adulthood, and a markedly early female pubertal growth spurt in height. Phenotypic plasticity and genetic selection in response to local environmental factors may explain many of these patterns. Providing a detailed reference of growth for the Shuar and other Amazonian populations, this study possesses direct clinical application and affords valuable insight into childhood health and the ecology of human growth. © 2015 Wiley Periodicals, Inc.

Interactions between cilazapril and propranolol in man; plasma drug concentrations, hormone and enzyme responses, haemodynamics, agonist dose-effect curves and baroreceptor reflex.

PubMed Central

Belz, G G; Essig, J; Kleinbloesem, C H; Hoogkamer, J F; Wiegand, U W; Wellstein, A

1988-01-01

1. The pharmacokinetics, hormonal and haemodynamic responses at rest and during challenges with angiotensin I (blood pressure), isoprenaline (heart rate), and noradrenaline (blood pressure) were investigated in six healthy male volunteers following a 1 week treatment with placebo, propranolol (120 mg day-1), cilazapril (2, 5 mg day-1), and a combination of both in a double-blind cross-over design. 2. Both drugs reduced systolic and diastolic blood pressure by about 7 mm Hg as compared with placebo. After coadministration, this drop in blood pressure was doubled and lasted longer than after the administration of the individual components. 3. Following cilazapril, a pronounced increase in plasma renin activity (PRA) was found (factor approximately 10 at drug peak concentrations). Coadministration of both drugs resulted only in a moderate increase in the PRA (factor approximately 3). Significant changes in plasma catecholamines were not observed. 4. Propranolol shifted the isoprenaline dose-effect curve to the right, and cilazapril that of angiotensin I, irrespective of the presence of the other drug. Cilazapril tended to shift the noradrenaline dose-effect curve somewhat to the right. 5. The gain of the baroreceptor reflex (angiotensin-stimulation) was not influenced by cilazapril but was lowered by propranolol, irrespective of the presence of the ACE inhibitor. 6. Except for a statistically not significant decrease in the peak concentrations of each drug during the combined therapy, a pharmacokinetic interaction between the two drugs was not found. PMID:2974715

Detection of cavitated or non-cavitated approximal enamel caries lesions using CMOS and CCD digital X-ray sensors and conventional D and F-speed films at different exposure conditions.

PubMed

Bottenberg, Peter; Jacquet, Wolfgang; Stachniss, Vitus; Wellnitz, Johann; Schulte, Andreas G

2011-04-01

To determine the ability of digital sensors (CMOS and CCD sensors) and D and F-speed films to detect cavitated and non-cavitated enamel caries lesions at different exposure conditions compared to a gold standard. 100 extracted human molars and premolars were selected and mounted in a block between two neighboring teeth. Sensors or films were exposed with voltages of 60 or 70 kVp at varying times. Three observers assessed each approximal site independently. Lesion depth was rated according to an anatomical five-point scale (0 = no lesion to 4 = lesion reaching inner half of dentin). Serial sections of resin-embedded teeth were prepared. Gold-standard scores were established by consensus based on histological sectioning. A carious lesion was present at scores of 1 and higher. Statistical evaluation (sensitivity, specificity and receiver-operating curves) was based on caries-free surfaces and those presenting enamel caries (n=116). The ROC curves had "area under the curve" values (Az) from 0.50 (F-speed, 70 kVp, 0.20 seconds) to 0.58 (CCD 60 kVp, 0.08 seconds). The detection percentage of cavitated lesions was generally higher (0-52%, depending on technique and observer) than that of non-cavitated lesions (3-32%). The CMOS sensor showed Az values comparable to the CCD sensors but required higher exposure times. There was no significant difference between 60 and 70 kVp.

Toxicity of cadmium to goldfish, Carassius auratus, in hard, and soft water

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

McCarty, L.S.; Henry, J.A.C.; Houston, A.H.

1978-01-01

Variations in cadmium form and concentration and in selected water quality parameters (pH, dissolved oxygen, total hardness, total alkalinity, conductivity) were monitored during static bioassays conducted with relatively soft (approximately 20 mg/L as CaCO/sub 3/) and hard (approximately 140 mg/L as CaCO/sub 3/) waters. Cadmium concentrations were reasonably stable in soft water, and with the exception of total hardness, water quality was not greatly altered during assay. Cumulative mortality curves were of a simple sigmoidal type and readily analyzed by conventional procedures. LC50 values of 2.76, 2.13, and 1.78 mg Cd/L were estimated on the basis of 48-, 96-, andmore » 240-h periods of observation. During hard-water trials there were transient increases in the amount of particulate cadmium present and sharp decreases in total cadmium levels. Several parameters (pH, total alkalinity, conductivity) exhibited transient and/or sustained variations of a cadmium concentration-dependent type. Mortality curves were typically biphasic. The extent of first-phase mortality was significantly correlated with the magnitude of the initial pH decline and the amount of cadmium present in centrifugable form. Conventional procedures did not result in rectification of 240-h cumulative mortality curves, and the 240-h LC50 value (40.2 mg Cd/L) is considered to be inherently less precise than those obtained on the basis of 48- and 96-h periods of observation (46.9, 46.8 mg Cd/L).« less

Estimating the SCS runoff curve number in forest catchments of Korea

NASA Astrophysics Data System (ADS)

Choi, Hyung Tae; Kim, Jaehoon; Lim, Hong-geun

2016-04-01

To estimate flood runoff discharge is a very important work in design for many hydraulic structures in streams, rivers and lakes such as dams, bridges, culverts, and so on. So, many researchers have tried to develop better methods for estimating flood runoff discharge. The SCS runoff curve number is an empirical parameter determined by empirical analysis of runoff from small catchments and hillslope plots monitored by the USDA. This method is an efficient method for determining the approximate amount of runoff from a rainfall even in a particular area, and is very widely used all around the world. However, there is a quite difference between the conditions of Korea and USA in topography, geology and land use. Therefore, examinations in adaptability of the SCS runoff curve number need to raise the accuracy of runoff prediction using SCS runoff curve number method. The purpose of this study is to find the SCS runoff curve number based on the analysis of observed data from several experimental forest catchments monitored by the National Institute of Forest Science (NIFOS), as a pilot study to modify SCS runoff curve number for forest lands in Korea. Rainfall and runoff records observed in Gwangneung coniferous and broad leaves forests, Sinwol, Hwasoon, Gongju and Gyeongsan catchments were selected to analyze the variability of flood runoff coefficients during the last 5 years. This study shows that runoff curve numbers of the experimental forest catchments range from 55 to 65. SCS Runoff Curve number method is a widely used method for estimating design discharge for small ungauged watersheds. Therefore, this study can be helpful technically to estimate the discharge for forest watersheds in Korea with more accuracy.

On the Early-Time Excess Emission in Hydrogen-Poor Superluminous Supernovae

NASA Technical Reports Server (NTRS)

Vreeswijk, Paul M.; Leloudas, Giorgos; Gal-Yam, Avishay; De Cia, Annalisa; Perley, Daniel A.; Quimby, Robert M.; Waldman, Roni; Sullivan, Mark; Yan, Lin; Ofek, Eran O.;

Understanding the Scalability of Bayesian Network Inference Using Clique Tree Growth Curves

NASA Technical Reports Server (NTRS)

Mengshoel, Ole J.

2010-01-01

One of the main approaches to performing computation in Bayesian networks (BNs) is clique tree clustering and propagation. The clique tree approach consists of propagation in a clique tree compiled from a Bayesian network, and while it was introduced in the 1980s, there is still a lack of understanding of how clique tree computation time depends on variations in BN size and structure. In this article, we improve this understanding by developing an approach to characterizing clique tree growth as a function of parameters that can be computed in polynomial time from BNs, specifically: (i) the ratio of the number of a BN s non-root nodes to the number of root nodes, and (ii) the expected number of moral edges in their moral graphs. Analytically, we partition the set of cliques in a clique tree into different sets, and introduce a growth curve for the total size of each set. For the special case of bipartite BNs, there are two sets and two growth curves, a mixed clique growth curve and a root clique growth curve. In experiments, where random bipartite BNs generated using the BPART algorithm are studied, we systematically increase the out-degree of the root nodes in bipartite Bayesian networks, by increasing the number of leaf nodes. Surprisingly, root clique growth is well-approximated by Gompertz growth curves, an S-shaped family of curves that has previously been used to describe growth processes in biology, medicine, and neuroscience. We believe that this research improves the understanding of the scaling behavior of clique tree clustering for a certain class of Bayesian networks; presents an aid for trade-off studies of clique tree clustering using growth curves; and ultimately provides a foundation for benchmarking and developing improved BN inference and machine learning algorithms.

Emission characteristics of plastic syringes sterilized with ethylene oxide--a controlled study.

PubMed

Chien, Yeh-Chung; Su, Po-Chi; Lee, Lien-Hsiung; Chen, Chang-Yuh

2009-11-01

This study examined the emission characteristics of ethylene oxide (EO)-sterilized syringes under various environmental conditions, aiming to develop control strategies to minimize worker exposure. Experiments were performed in a facility in which temperature, relative humidity (RH), and air change rate (ACR) were controlled. Analytical results indicate that the main effects of the four test variables on kinetic parameters were statistically significant (p < 0.05), except for the effect of the product on the decay rate constant, the effect of ACR on maximum EO concentration, and effect of RH on the area under the curve-days 1 and 2. The interactive effects among test variables were also evident, indicating complex emission behaviors. The mean EO emission factors during the days 1 and 2 and at the 48th hour for the 1- and 30-ml products were 2302, 1301, and 1031 mg/m(3)/h, and 871, 490, and 381 mg/m(3)/h, respectively. The times required for air EO concentrations from tested products to return to approximately 0 and 1 ppm (permissible limit) were 417 and 218 h, respectively. Plastic content, temperature, RH, and ACR affected EO emissions. ACR is an achievable means of control; however, the aeration area/system should be isolated to ensure adequate ventilation is achieved.

EXPERIMENTAL MEASUREMENT AND INTERPRETATION OF VOLT-AMPERE CURVES

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

Gingrich, J.E.; Warner, C.; Weeks, C.C.

1962-07-01

Cylindrical and parallel-plane cesium vapor thermionic converters were used for obtaining volt-ampere curves for systematic variations of emitter, collector, and cesium reservoir temperatures, with electrode spacings ranging from a few to many mean free paths, and with space charge conditions varying from electron-rich to ion-rich. The resulting curves exhibit much variety. The saturation currents agree well with the data of Houston and Aamodt for the space charge neutralized, few-mean-free-path cases. Apparent'' saturation currents for space charge limited cases were observed and were always less than the currents predicted by Houston and Aamodt. Several discontinuities in slope were observed in themore » reverse current portion of the curves and these have tentatively been identified with volume ionization of atoms in both the ground and excited states. Similar processes may be important for obtaining the ignited mode. The methods used to measure static and dynamic volt-ampere curves are described. The use of a controlled-current load has yielded a negative resistance'' region in the curves which show the ignited mode. The curves obtained with poor current control do not show this phenomenon. Extinction is considered from the standpoint of Kaufmann' s criterion for stability. (auth)« less

Regional and sectoral marginal abatement cost curves for NOx incorporating controls, renewable electricity, energy efficiency and fuel switching

EPA Science Inventory

A marginal abatement cost curve (MACC) traces out the relationship between the quantity of pollution abated and the marginal cost of abating each additional unit. In the context of air quality management, MACCs typically are developed by sorting end-of-pipe controls by their resp...

Marginal abatement cost curve for NOx incorporating controls, renewable electricity, energy efficiency and fuel switching

EPA Science Inventory

A marginal abatement cost curve (MACC) traces out the relationship between the quantity of pollution abated and the marginal cost of abating each additional unit. In the context of air quality management, MACCs typically are developed by sorting end-of-pipe controls by their resp...

Marginal abatement cost curve for NOx incorporating controls, renewable electricity, energy efficiency and fuel switching

EPA Science Inventory

A marginal abatement cost curve (MACC) traces out the relationship between the quantity of pollution abated and the marginal cost of abating each additional unit. In the context of air quality management, MACCs typically are developed by sorting end-of-pipe controls by their rela...

On cyclic yield strength in definition of limits for characterisation of fatigue and creep behaviour

NASA Astrophysics Data System (ADS)

Gorash, Yevgen; MacKenzie, Donald

2017-06-01

This study proposes cyclic yield strength as a potential characteristic of safe design for structures operating under fatigue and creep conditions. Cyclic yield strength is defined on a cyclic stress-strain curve, while monotonic yield strength is defined on a monotonic curve. Both values of strengths are identified using a two-step procedure of the experimental stress-strain curves fitting with application of Ramberg-Osgood and Chaboche material models. A typical S-N curve in stress-life approach for fatigue analysis has a distinctive minimum stress lower bound, the fatigue endurance limit. Comparison of cyclic strength and fatigue limit reveals that they are approximately equal. Thus, safe fatigue design is guaranteed in the purely elastic domain defined by the cyclic yielding. A typical long-term strength curve in time-to-failure approach for creep analysis has two inflections corresponding to the cyclic and monotonic strengths. These inflections separate three domains on the long-term strength curve, which are characterised by different creep fracture modes and creep deformation mechanisms. Therefore, safe creep design is guaranteed in the linear creep domain with brittle failure mode defined by the cyclic yielding. These assumptions are confirmed using three structural steels for normal and high-temperature applications. The advantage of using cyclic yield strength for characterisation of fatigue and creep strength is a relatively quick experimental identification. The total duration of cyclic tests for a cyclic stress-strain curve identification is much less than the typical durations of fatigue and creep rupture tests at the stress levels around the cyclic yield strength.

Application of a lower-upper implicit scheme and an interactive grid generation for turbomachinery flow field simulations

NASA Technical Reports Server (NTRS)

Choo, Yung K.; Soh, Woo-Yung; Yoon, Seokkwan

1989-01-01

A finite-volume lower-upper (LU) implicit scheme is used to simulate an inviscid flow in a tubine cascade. This approximate factorization scheme requires only the inversion of sparse lower and upper triangular matrices, which can be done efficiently without extensive storage. As an implicit scheme it allows a large time step to reach the steady state. An interactive grid generation program (TURBO), which is being developed, is used to generate grids. This program uses the control point form of algebraic grid generation which uses a sparse collection of control points from which the shape and position of coordinate curves can be adjusted. A distinct advantage of TURBO compared with other grid generation programs is that it allows the easy change of local mesh structure without affecting the grid outside the domain of independence. Sample grids are generated by TURBO for a compressor rotor blade and a turbine cascade. The turbine cascade flow is simulated by using the LU implicit scheme on the grid generated by TURBO.

Stability and predictors of change in salivary cortisol measures over six years: MESA.

PubMed

Wang, Xu; Sánchez, Brisa N; Golden, Sherita Hill; Shrager, Sandi; Kirschbaum, Clemens; Karlamangla, Arun S; Seeman, Teresa E; Roux, Ana V Diez

2014-11-01

A major challenge in characterizing features of the daily cortisol curve is variability in features over time. Few studies have examined the stability of daily features of the cortisol curve over long periods or the predictors of long term changes. Repeated salivary cortisol measures on 580 adults from the MESA Stress study were used to examine the stability of various features of the daily cortisol curve (wakeup value, the cortisol awakening response (CAR), the early and late decline slope and the area under the curve (AUC)), over short periods (several days) and long periods (approximately 6-years) and to investigate the association of demographic factors with the changes. Intraclass correlation coefficients (ICCs) were used to estimate the short and long term stability. Piecewise linear mixed models were used to assess factors associated with changes in features over time. For most features, short term stability (ICCs: 0.17-0.74) was higher than long term stability (ICCs: 0.05-0.42), and long term stability was highest when several days were averaged for each time point. The decline over the day showed the highest long term stability: when several days for each wave were averaged the stability of the daily decline slope across 6 years was similar (or higher) than the stability across short periods. AUC had high stability over short periods (ICCs: 0.65-0.74) but much lower stability across long periods (ICC: 0.05). All features of daily cortisol curve investigated changed significantly over the approximately 6 year follow-up period. The wakeup cortisol became higher; the CAR became smaller; both the early and late decline became flatter; and the AUC became larger. Hispanics experienced significantly larger increases in the wakeup value; and African-Americans and Hispanics showed less flattening over time of the early decline slope than Non-Hispanic Whites. Our findings have implications for characterization of features in studies linking cortisol to health outcomes. The presence of variability over time suggests opportunities for future investigation of the predictors of changes over time as well as the links between these changes and health outcomes. Copyright © 2014 Elsevier Ltd. All rights reserved.

Reduction of leakage current at the gate edge of SDB SOI NMOS transistor

NASA Astrophysics Data System (ADS)

Kang, Sung-Weon; Lyu, Jong-Son; Kang, Jin-Young; Kang, Sang-Won; Lee, Jin-Hyo

1995-06-01

Leakage current through the parasitic channel formed at the sidewall of the SOI active region has been investigated by measuring the subthreshold I-V characteristics. Partially depleted (PD, approximately 2500 Angstrom) and fully depleted (FD, approximately 800 Angstrom) SOI NMOS transistors of enhancement mode have been fabricated using the silicon direct bonding (SDB) technology. Isolation processes for the SOI devices were LOCOS, LOCOS with channel stop ion implantation or fully recessed trench (FRT). The electron concentration of the parasitic channel is calculated by the PISCES Ilb simulation. As a result, leakage current of the FD mode SOI device with FRT isolation at the front and back gate biases of 0 V was reduced to approximately pA and no hump was seen on the drain current curve.

Refractive index investigation of poly(vinyl alcohol) films with TiO2 nanoparticle inclusions.

PubMed

Yovcheva, Temenuzhka; Vlaeva, Ivanka; Bodurov, Ivan; Dragostinova, Violeta; Sainov, Simeon

2012-11-10

The refractive index (RI) of polymer nanocomposite of poly(vinyl alcohol) films with TiO(2) nanoparticle inclusions with low concentration up to 1.2 wt. % was investigated. Accurate refractometric measurements, by a specially designed laser microrefractometer, were performed at wavelengths 532 and 632.8 nm. The influence of TiO(2) concentration on the RI dispersion curves was predicted based on the well-known Sellmeier model. The theoretical analysis, in a small filling factor approximation, was performed, and a relation between the effective RI of the nanocomposite and weight concentrations of the TiO(2) nanofiller was derived. The experimental values were approximated by two different functions (linear and a quadratic polynom). The polynomial approximation yields better result, where R(2)=0.90.

Carbon Nanofibers Synthesized on Selective Substrates for Nonvolatile Memory and 3D Electronics

NASA Technical Reports Server (NTRS)

Kaul, Anupama B.; Khan, Abdur R.

2011-01-01

A plasma-enhanced chemical vapor deposition (PECVD) growth technique has been developed where the choice of starting substrate was found to influence the electrical characteristics of the resulting carbon nanofiber (CNF) tubes. It has been determined that, if the tubes are grown on refractory metallic nitride substrates, then the resulting tubes formed with dc PECVD are also electrically conducting. Individual CNFs were formed by first patterning Ni catalyst islands using ebeam evaporation and liftoff. The CNFs were then synthesized using dc PECVD with C2H2:NH3 = [1:4] at 5 Torr and 700 C, and approximately equal to 200-W plasma power. Tubes were grown directly on degenerately doped silicon <100> substrates with resistivity rho approximately equal to 1-5 meterohm-centimeter, as well as NbTiN. The approximately equal to 200-nanometer thick refractory NbTiN deposited using magnetron sputtering had rho approximately equal to 113 microohm-centimeter and was also chemically compatible with CNF synthesis. The sample was then mounted on a 45 beveled Al holder, and placed inside a SEM (scanning electron microscope). A nanomanipulator probe stage was placed inside the SEM equipped with an electrical feed-through, where tungsten probes were used to make two-terminal electrical measurements with an HP 4156C parameter analyzer. The positive terminal nanoprobe was mechanically manipulated to physically contact an individual CNF grown directly on NbTiN as shown by the SEM image in the inset of figure (a), while the negative terminal was grounded to the substrate. This revealed the tube was electrically conductive, although measureable currents could not be detected until approximately equal to 6 V, after which point current increased sharply until compliance (approximately equal to 50 nA) was reached at approximately equal to 9.5 V. A native oxide on the tungsten probe tips may contribute to a tunnel barrier, which could be the reason for the suppressed transport at low biases. Currents up to approximately 100 nA could be cycled, which are likely to propagate via the tube surface, or sidewalls, rather than the body, which is shown by the I-V in figure (a). Electrical conduction via the sidewalls is a necessity for dc NEMS (nanoelectromechanical system) applications, more so than for the field emission applications of such tubes. During the tests, high conductivity was expected, because both probes were shorted to the substrate, as shown by curve 1 in the I-V characteristic in figure (b). When a tube grown on NbTiN was probed, the response was similar to the approximately equal to 100 nA and is represented by curve 2 in figure (b), which could be cycled and propagated via the tube surface or the sidewalls. However, no measureable currents for the tube grown directly on Si were observed as shown by curve 3 in figure (b), even after testing over a range of samples. This could arise from a dielectric coating on the sidewalls for tubes on Si. As a result of the directional nature of ion bombardment during dc PECVD, Si from the substrate is likely re-sputtered and possibly coats the sidewalls.

Numerical Estimation of the Curvature of Biological Surfaces

NASA Technical Reports Server (NTRS)

Todd, P. H.

1985-01-01

Many biological systems may profitably be studied as surface phenomena. A model consisting of isotropic growth of a curved surface from a flat sheet is assumed. With such a model, the Gaussian curvature of the final surface determines whether growth rate of the surface is subharmonic or superharmonic. These properties correspond to notions of convexity and concavity, and thus to local excess growth and local deficiency of growth. In biological models where the major factors controlling surface growth are intrinsic to the surface, researchers thus gained from geometrical study information on the differential growth undergone by the surface. These ideas were applied to an analysis of the folding of the cerebral cortex, a geometrically rather complex surface growth. A numerical surface curvature technique based on an approximation to the Dupin indicatrix of the surface was developed. A metric for comparing curvature estimates is introduced, and considerable numerical testing indicated the reliability of this technique.

Fatigue resistance of engine-driven rotary nickel-titanium endodontic instruments.

PubMed

Chaves Craveiro de Melo, Marta; Guiomar de Azevedo Bahia, Maria; Lopes Buono, Vicente Tadeu

2002-11-01

A comparative study of the fatigue resistance of engine-driven nickel-titanium endodontic instruments was performed, aiming to access the influence of the cutting flute design and of the size of the files that reach the working length in curved canal shaping. Geometrical conditions similar to those found in practice were used. Series 29 #5 ProFile, together with #6 and #8 Quantec instruments, were tested in artificial canals with a 45-degree angle of curvature and 5-mm radius of curvature. It was observed that the size of the instrument, which determines the maximum strain amplitude during cyclic deformation, is the most important factor controlling fatigue resistance. The effect of heat sterilization on the fatigue resistance of the instruments was also examined. The results obtained indicate that the application of five sterilization procedures in dry heat increases the average number of cycles to failure of unused instruments by approximately 70%.

PharmaSat: drug dose response in microgravity from a free-flying integrated biofluidic/optical culture-and-analysis satellite

NASA Astrophysics Data System (ADS)

Ricco, Antonio J.; Parra, Macarena; Niesel, David; Piccini, Matthew; Ly, Diana; McGinnis, Michael; Kudlicki, Andrzej; Hines, John W.; Timucin, Linda; Beasley, Chris; Ricks, Robert; McIntyre, Michael; Friedericks, Charlie; Henschke, Michael; Leung, Ricky; Diaz-Aguado, Millan; Kitts, Christopher; Mas, Ignacio; Rasay, Mike; Agasid, Elwood; Luzzi, Ed; Ronzano, Karolyn; Squires, David; Yost, Bruce

2011-02-01

We designed, built, tested, space-qualified, launched, and collected telemetered data from low Earth orbit from Pharma- Sat, a 5.1-kg free flying "nanosatellite" that supported microbial growth in 48 microfluidic wells, dosed microbes with multiple concentrations of a pharmaceutical agent, and monitored microbial growth and metabolic activity using a dedicated 3-color optical absorbance system at each microwell. The PharmaSat nanosatellite comprised a structure approximately 10 x 10 x 35 cm, including triple-junction solar cells, bidirectional communications, power-generation and energy- storage system, and a sealed payload 1.2-L containment vessel that housed the biological organisms along with the fluidic, optical, thermal, sensor, and electronic subsystems. Growth curves for S. cerevisiae (Brewer's yeast) were obtained for multiple concentrations of the antifungal drug voriconazole in the microgravity conditions of low Earth orbit. Corresponding terrestrial control experiments were conducted for comparison.

Controlling Thermodynamic Properties of Ferromagnetic Group-IV Graphene-Like Nanosheets by Dilute Charged Impurity

NASA Astrophysics Data System (ADS)

Yarmohammadi, Mohsen; Mirabbaszadeh, Kavoos

2017-05-01

Using the Kane-Mele Hamiltonian, Dirac theory and self-consistent Born approximation, we investigate the effect of dilute charged impurity on the electronic heat capacity and magnetic susceptibility of two-dimensional ferromagnetic honeycomb structure of group-IV elements including silicene, germanene and stanene within the Green’s function approach. We also find these quantities in the presence of applied external electric field. Our results show that the silicene (stanene) has the maximum (minimum) heat capacity and magnetic susceptibility at uniform electric fields. From the behavior of theses quantities, the band gap has been changed with impurity concentration, impurity scattering strength and electric field. The analysis on the impurity-dependent magnetic susceptibility curves shows a phase transition from ferromagnetic to paramagnetic and antiferromagnetic phases. Interestingly, electronic heat capacity increases (decreases) with impurity concentration in silicene (germanene and stanene) structure.

Spacecraft attitude control using neuro-fuzzy approximation of the optimal controllers

NASA Astrophysics Data System (ADS)

Kim, Sung-Woo; Park, Sang-Young; Park, Chandeok

2016-01-01

In this study, a neuro-fuzzy controller (NFC) was developed for spacecraft attitude control to mitigate large computational load of the state-dependent Riccati equation (SDRE) controller. The NFC was developed by training a neuro-fuzzy network to approximate the SDRE controller. The stability of the NFC was numerically verified using a Lyapunov-based method, and the performance of the controller was analyzed in terms of approximation ability, steady-state error, cost, and execution time. The simulations and test results indicate that the developed NFC efficiently approximates the SDRE controller, with asymptotic stability in a bounded region of angular velocity encompassing the operational range of rapid-attitude maneuvers. In addition, it was shown that an approximated optimal feedback controller can be designed successfully through neuro-fuzzy approximation of the optimal open-loop controller.

Longitudinal Growth Curves of Brain Function Underlying Inhibitory Control through Adolescence

PubMed Central

Foran, William; Velanova, Katerina; Luna, Beatriz

2013-01-01

Neuroimaging studies suggest that developmental improvements in inhibitory control are primarily supported by changes in prefrontal executive function. However, studies are contradictory with respect to how activation in prefrontal regions changes with age, and they have yet to analyze longitudinal data using growth curve modeling, which allows characterization of dynamic processes of developmental change, individual differences in growth trajectories, and variables that predict any interindividual variability in trajectories. In this study, we present growth curves modeled from longitudinal fMRI data collected over 302 visits (across ages 9 to 26 years) from 123 human participants. Brain regions within circuits known to support motor response control, executive control, and error processing (i.e., aspects of inhibitory control) were investigated. Findings revealed distinct developmental trajectories for regions within each circuit and indicated that a hierarchical pattern of maturation of brain activation supports the gradual emergence of adult-like inhibitory control. Mean growth curves of activation in motor response control regions revealed no changes with age, although interindividual variability decreased with development, indicating equifinality with maturity. Activation in certain executive control regions decreased with age until adolescence, and variability was stable across development. Error-processing activation in the dorsal anterior cingulate cortex showed continued increases into adulthood and no significant interindividual variability across development, and was uniquely associated with task performance. These findings provide evidence that continued maturation of error-processing abilities supports the protracted development of inhibitory control over adolescence, while motor response control regions provide early-maturing foundational capacities and suggest that some executive control regions may buttress immature networks as error processing continues to mature. PMID:24227721

Investigation of Light-Emitting Diode (LED) Point Light Source Color Visibility against Complex Multicolored Backgrounds

DTIC Science & Technology

2017-11-01

sent from light-emitting diodes (LEDs) of 5 colors ( green , red, white, amber, and blue). Experiment 1 involved controlled laboratory measurements of...A-4 Red LED calibration curves and quadratic curve fits with R2 values . 37 Fig. A-5 Green LED calibration curves and quadratic curve fits with R2...36 Table A-4 Red LED calibration measurements ................................................... 36 Table A-5 Green LED

Scalar field as a Bose-Einstein condensate?

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

Castellanos, Elías; Escamilla-Rivera, Celia; Macías, Alfredo

We discuss the analogy between a classical scalar field with a self-interacting potential, in a curved spacetime described by a quasi-bounded state, and a trapped Bose-Einstein condensate. In this context, we compare the Klein-Gordon equation with the Gross-Pitaevskii equation. Moreover, the introduction of a curved background spacetime endows, in a natural way, an equivalence to the Gross-Pitaevskii equation with an explicit confinement potential. The curvature also induces a position dependent self-interaction parameter. We exploit this analogy by means of the Thomas-Fermi approximation, commonly used to describe the Bose-Einstein condensate, in order to analyze the quasi bound scalar field distribution surroundingmore » a black hole.« less

Locally-Based Kernal PLS Smoothing to Non-Parametric Regression Curve Fitting

NASA Technical Reports Server (NTRS)

Rosipal, Roman; Trejo, Leonard J.; Wheeler, Kevin; Korsmeyer, David (Technical Monitor)

2002-01-01

We present a novel smoothing approach to non-parametric regression curve fitting. This is based on kernel partial least squares (PLS) regression in reproducing kernel Hilbert space. It is our concern to apply the methodology for smoothing experimental data where some level of knowledge about the approximate shape, local inhomogeneities or points where the desired function changes its curvature is known a priori or can be derived based on the observed noisy data. We propose locally-based kernel PLS regression that extends the previous kernel PLS methodology by incorporating this knowledge. We compare our approach with existing smoothing splines, hybrid adaptive splines and wavelet shrinkage techniques on two generated data sets.

Speckle interferometry of asteroids. IV - Reconstructed images of 4 Vesta

NASA Technical Reports Server (NTRS)

Drummond, J.; Eckart, A.; Hege, E. K.

1988-01-01

The images of 4 Vesta obtained by means of speckle interferometric observations on November 16 and 17, 1983, support a 5-hr 20.5-min rotational period. The 4 Vesta visible light curve was approximately matched by the placing of circular 'spots' with 135-km diameter over the three dark and three bright features, followed by the assigning of albedos of 0 to the dark spots and 2 to the bright. The light curve is found to be primarily defined by albedo structure, rather than shape; this results in one maximum and one minimum/rotation, rather than the two of each that would be associated with 4 Vesta's triaxial ellipsoid morphology.

Transformation Model Choice in Nonlinear Regression Analysis of Fluorescence-based Serial Dilution Assays

PubMed Central

Fong, Youyi; Yu, Xuesong

2016-01-01

Many modern serial dilution assays are based on fluorescence intensity (FI) readouts. We study optimal transformation model choice for fitting five parameter logistic curves (5PL) to FI-based serial dilution assay data. We first develop a generalized least squares-pseudolikelihood type algorithm for fitting heteroscedastic logistic models. Next we show that the 5PL and log 5PL functions can approximate each other well. We then compare four 5PL models with different choices of log transformation and variance modeling through a Monte Carlo study and real data. Our findings are that the optimal choice depends on the intended use of the fitted curves. PMID:27642502

Alpha-Particle Gas-Pressure Sensor

NASA Technical Reports Server (NTRS)

Buehler, M. C.; Bell, L. D.; Hecht, M. H.

1996-01-01

An approximate model was developed to establish design curves for the saturation region and a more complete model developed to characterize the current-voltage curves for an alpha-particle pressure sensor. A simple two-parameter current-voltage expression was developed to describe the dependence of the ion current on pressure. The parameters are the saturation-current pressure coefficient and mu/D, the ion mobility/diffusion coefficient. The sensor is useful in the pressure range between 0.1 and 1000 mb using a 1 - mu Ci(241) Am source. Experimental results, taken between 1 and up to 200 mb, show the sensor operates with an anode voltage of 5 V and a sensitivity of 20 fA/mb in nitrogen.

Twentieth century light curves and the nucleus of comet P/Tempel 2

NASA Technical Reports Server (NTRS)

Rickman, Hans; Festou, Michel C.; Tancredi, Gonzalo; Kamel, L.

1992-01-01

Observations of P/Tempel 2 from 1899 to 1988 corresponding to 13 apparitions are analyzed in order to estimate the perihelion asymmetry of the gas production curve for different periods of its evolution. Using the correlation found by Festou et al. (1990) between the perihelion asymmetries and the delay in perihelion passage due to the action of nongravitational forces, we estimate the mass of the comet to be M approximately equals 1.6 plus or minus 0.5 x 10(exp 14) kg. Assuming a volume of 500 cu km, based on nuclear observations, a density of 0.3 plus or minus 0.1 g/cu cm is obtained.

Influence of speed on wear and cutting forces in end-milling nickel alloy

NASA Astrophysics Data System (ADS)

Estrems, M.; Sánchez, H. T.; Kurfess, T.; Bunget, C.

2012-04-01

The effect of speed on the flank wear of the cutting tool when a nickel alloy is milled is studied. From the analysis of the measured forces, a dynamic semi-experimental model is developed based on the parallelism between the curve of the thrust forces of the unworn tool and the curves when the flank of the tool is worn. Based on the change in the geometry of the contact in the flank worrn face, a theory of indentation of the tool on the workpiece is formulated in such a way that upon applying equations of contact mechanics, a good approximation of the experimental results is obtained.

Triangulation of multistation camera data to locate a curved line in space

NASA Technical Reports Server (NTRS)

Fricke, C. L.

1974-01-01

A method is described for finding the location of a curved line in space from local azimuth as a function of elevation data obtained at several observation sites. A least-squares criterion is used to insure the best fit to the data. The method is applicable to the triangulation of an object having no identifiable structural features, provided its width is very small compared with its length so as to approximate a line in space. The method was implemented with a digital computer program and was successfully applied to data obtained from photographs of a barium ion cloud which traced out the earth's magnetic field line at very high altitudes.

Accuracy of measurement in electrically evoked compound action potentials.

PubMed

Hey, Matthias; Müller-Deile, Joachim

2015-01-15

Electrically evoked compound action potentials (ECAP) in cochlear implant (CI) patients are characterized by the amplitude of the N1P1 complex. The measurement of evoked potentials yields a combination of the measured signal with various noise components but for ECAP procedures performed in the clinical routine, only the averaged curve is accessible. To date no detailed analysis of error dimension has been published. The aim of this study was to determine the error of the N1P1 amplitude and to determine the factors that impact the outcome. Measurements were performed on 32 CI patients with either CI24RE (CA) or CI512 implants using the Software Custom Sound EP (Cochlear). N1P1 error approximation of non-averaged raw data consisting of recorded single-sweeps was compared to methods of error approximation based on mean curves. The error approximation of the N1P1 amplitude using averaged data showed comparable results to single-point error estimation. The error of the N1P1 amplitude depends on the number of averaging steps and amplification; in contrast, the error of the N1P1 amplitude is not dependent on the stimulus intensity. Single-point error showed smaller N1P1 error and better coincidence with 1/√(N) function (N is the number of measured sweeps) compared to the known maximum-minimum criterion. Evaluation of N1P1 amplitude should be accompanied by indication of its error. The retrospective approximation of this measurement error from the averaged data available in clinically used software is possible and best done utilizing the D-trace in forward masking artefact reduction mode (no stimulation applied and recording contains only the switch-on-artefact). Copyright © 2014 Elsevier B.V. All rights reserved.

Simple Decision-Analytic Functions of the AUC for Ruling Out a Risk Prediction Model and an Added Predictor.

PubMed

Baker, Stuart G

2018-02-01

When using risk prediction models, an important consideration is weighing performance against the cost (monetary and harms) of ascertaining predictors. The minimum test tradeoff (MTT) for ruling out a model is the minimum number of all-predictor ascertainments per correct prediction to yield a positive overall expected utility. The MTT for ruling out an added predictor is the minimum number of added-predictor ascertainments per correct prediction to yield a positive overall expected utility. An approximation to the MTT for ruling out a model is 1/[P (H(AUC model )], where H(AUC) = AUC - {½ (1-AUC)} ½ , AUC is the area under the receiver operating characteristic (ROC) curve, and P is the probability of the predicted event in the target population. An approximation to the MTT for ruling out an added predictor is 1 /[P {(H(AUC Model:2 ) - H(AUC Model:1 )], where Model 2 includes an added predictor relative to Model 1. The latter approximation requires the Tangent Condition that the true positive rate at the point on the ROC curve with a slope of 1 is larger for Model 2 than Model 1. These approximations are suitable for back-of-the-envelope calculations. For example, in a study predicting the risk of invasive breast cancer, Model 2 adds to the predictors in Model 1 a set of 7 single nucleotide polymorphisms (SNPs). Based on the AUCs and the Tangent Condition, an MTT of 7200 was computed, which indicates that 7200 sets of SNPs are needed for every correct prediction of breast cancer to yield a positive overall expected utility. If ascertaining the SNPs costs $500, this MTT suggests that SNP ascertainment is not likely worthwhile for this risk prediction.

The 2011 Outburst of Recurrent Nova T Pyx: X-Ray Observations Expose the White Dwarf Mass and Ejection Dynamics

NASA Technical Reports Server (NTRS)

Chomiuk, Laura; Nelson, Thomas; Mukai, Koji; Solokoski, J. L.; Rupen, Michael P.; Page, Kim L.; Osborne, Julian P.; Kuulkers, Erik; Mioduszewski, Amy J.; Roy, Nirupam;

2,3-Diphosphoglycerate Concentrations in Autologous Salvaged Versus Stored Red Blood Cells and in Surgical Patients After Transfusion.

PubMed

Scott, Andrew V; Nagababu, Enika; Johnson, Daniel J; Kebaish, Khaled M; Lipsitz, Joshua A; Dwyer, Ian M; Zuckerberg, Gabriel S; Barodka, Viachaslau M; Berkowitz, Dan E; Frank, Steven M

2016-03-01

Stored red blood cells (RBCs) are deficient in 2,3-diphosphoglycerate (2,3-DPG), but it is unclear how autologous salvaged blood (ASB) compares with stored blood and how rapidly 2,3-DPG levels return to normal after transfusion. Therefore, we compared levels of 2,3-DPG in stored versus ASB RBCs and in patients' blood after transfusion. Twenty-four patients undergoing multilevel spine fusion surgery were enrolled. We measured 2,3-DPG and the oxyhemoglobin dissociation curve (P50) in samples taken from the ASB and stored blood bags before transfusion and in blood samples drawn from patients before and after transfusion. The mean storage duration for stored RBCs was 24 ± 8 days. Compared with fresh RBCs, stored RBCs had decreased 2,3-DPG levels (by approximately 90%; P < 0.0001) and a decreased P50 (by approximately 30%; P < 0.0001). However, ASB RBCs did not exhibit these changes. The mean 2,3-DPG concentration decreased by approximately 20% (P < 0.05) in postoperative blood sampled from patients who received 1 to 3 stored RBC units and by approximately 30% (P < 0.01) in those who received ≥4 stored RBC units. 2,3-DPG was unchanged in patients who received no stored blood or ASB alone. After surgery, 2,3-DPG levels recovered gradually over 3 postoperative days in patients who received stored RBCs. Stored RBCs, but not ASB RBCs, have decreased levels of 2,3-DPG and a left-shift in the oxyhemoglobin dissociation curve. Postoperatively, 2,3-DPG levels remain below preoperative baseline levels for up to 3 postoperative days in patients who receive stored RBCs but are unchanged in those who receive only ASB RBCs.

MHD modelling of the heliospheric interface

NASA Astrophysics Data System (ADS)

Ratkiewicz, R.

The thin layer approximation (TLA) is used to ascertain the effect of the IMF on the heliospheric interface. The TLA approach can be used in considering properties of the solar wind termination shock, since by definition both curves are close to each other. Good agreement is obtained with previous predictions of the solar wind termination shock's shape and distance.

The Moderating Capacity of Racial Identity between Perceived Discrimination and Psychological Well-Being over Time among African American Youth

ERIC Educational Resources Information Center

Seaton, Eleanor K.; Neblett, Enrique W.; Upton, Rachel D.; Hammond, Wizdom Powell; Sellers, Robert M.

2011-01-01

This study examined the influence of racial identity in the longitudinal relation between perceptions of racial discrimination and psychological well-being for approximately 560 African American youth. Latent curve modeling (LCM) and parallel process multiple-indicator LCMs with latent moderators were used to assess whether perceptions of racial…

Comparison of power curve monitoring methods

NASA Astrophysics Data System (ADS)

Cambron, Philippe; Masson, Christian; Tahan, Antoine; Torres, David; Pelletier, Francis

2017-11-01

Performance monitoring is an important aspect of operating wind farms. This can be done through the power curve monitoring (PCM) of wind turbines (WT). In the past years, important work has been conducted on PCM. Various methodologies have been proposed, each one with interesting results. However, it is difficult to compare these methods because they have been developed using their respective data sets. The objective of this actual work is to compare some of the proposed PCM methods using common data sets. The metric used to compare the PCM methods is the time needed to detect a change in the power curve. Two power curve models will be covered to establish the effect the model type has on the monitoring outcomes. Each model was tested with two control charts. Other methodologies and metrics proposed in the literature for power curve monitoring such as areas under the power curve and the use of statistical copulas have also been covered. Results demonstrate that model-based PCM methods are more reliable at the detecting a performance change than other methodologies and that the effectiveness of the control chart depends on the types of shift observed.

Fission yield calculation using toy model based on Monte Carlo simulation

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

Jubaidah, E-mail: jubaidah@student.itb.ac.id; Physics Department, Faculty of Mathematics and Natural Science – State University of Medan. Jl. Willem Iskandar Pasar V Medan Estate – North Sumatera, Indonesia 20221; Kurniadi, Rizal, E-mail: rijalk@fi.itb.ac.id

2015-09-30

Toy model is a new approximation in predicting fission yield distribution. Toy model assumes nucleus as an elastic toy consist of marbles. The number of marbles represents the number of nucleons, A. This toy nucleus is able to imitate the real nucleus properties. In this research, the toy nucleons are only influenced by central force. A heavy toy nucleus induced by a toy nucleon will be split into two fragments. These two fission fragments are called fission yield. In this research, energy entanglement is neglected. Fission process in toy model is illustrated by two Gaussian curves intersecting each other. Theremore » are five Gaussian parameters used in this research. They are scission point of the two curves (R{sub c}), mean of left curve (μ{sub L}) and mean of right curve (μ{sub R}), deviation of left curve (σ{sub L}) and deviation of right curve (σ{sub R}). The fission yields distribution is analyses based on Monte Carlo simulation. The result shows that variation in σ or µ can significanly move the average frequency of asymmetry fission yields. This also varies the range of fission yields distribution probability. In addition, variation in iteration coefficient only change the frequency of fission yields. Monte Carlo simulation for fission yield calculation using toy model successfully indicates the same tendency with experiment results, where average of light fission yield is in the range of 90« less

Fission yield calculation using toy model based on Monte Carlo simulation

NASA Astrophysics Data System (ADS)

Jubaidah, Kurniadi, Rizal

2015-09-01

Toy model is a new approximation in predicting fission yield distribution. Toy model assumes nucleus as an elastic toy consist of marbles. The number of marbles represents the number of nucleons, A. This toy nucleus is able to imitate the real nucleus properties. In this research, the toy nucleons are only influenced by central force. A heavy toy nucleus induced by a toy nucleon will be split into two fragments. These two fission fragments are called fission yield. In this research, energy entanglement is neglected. Fission process in toy model is illustrated by two Gaussian curves intersecting each other. There are five Gaussian parameters used in this research. They are scission point of the two curves (Rc), mean of left curve (μL) and mean of right curve (μR), deviation of left curve (σL) and deviation of right curve (σR). The fission yields distribution is analyses based on Monte Carlo simulation. The result shows that variation in σ or µ can significanly move the average frequency of asymmetry fission yields. This also varies the range of fission yields distribution probability. In addition, variation in iteration coefficient only change the frequency of fission yields. Monte Carlo simulation for fission yield calculation using toy model successfully indicates the same tendency with experiment results, where average of light fission yield is in the range of 90

Minimal-Approximation-Based Distributed Consensus Tracking of a Class of Uncertain Nonlinear Multiagent Systems With Unknown Control Directions.

PubMed

Choi, Yun Ho; Yoo, Sung Jin

2017-03-28

A minimal-approximation-based distributed adaptive consensus tracking approach is presented for strict-feedback multiagent systems with unknown heterogeneous nonlinearities and control directions under a directed network. Existing approximation-based consensus results for uncertain nonlinear multiagent systems in lower-triangular form have used multiple function approximators in each local controller to approximate unmatched nonlinearities of each follower. Thus, as the follower's order increases, the number of the approximators used in its local controller increases. However, the proposed approach employs only one function approximator to construct the local controller of each follower regardless of the order of the follower. The recursive design methodology using a new error transformation is derived for the proposed minimal-approximation-based design. Furthermore, a bounding lemma on parameters of Nussbaum functions is presented to handle the unknown control direction problem in the minimal-approximation-based distributed consensus tracking framework and the stability of the overall closed-loop system is rigorously analyzed in the Lyapunov sense.

Preliminary Investigation of Curved Liner Sample in the NASA LaRC Curved Duct Test Rig

NASA Technical Reports Server (NTRS)

Gerhold, Carl H.; Jones, Michael G.; Brown, Martha C.

2007-01-01

This viewgraph presentation reviews the preliminary investigation of the curved liner sample in the NASA LaRC Curved Duct Test Rig (CDTR). It reviews the purpose of the Curved Duct Test Rig. Its purpose is to develop capability to investigate acoustic and aerodynamic properties in ducts. It has several features to accomplish that purpose: (1) Large scale (2) Flow rate to M = 0.275 (3) Higher order mode control (4) Curved flow path (5) Adaptable test section (6) Flexible test configurations. The liner has minimal effect on turbulence or boundary layer growth in duct. The curved duct sample attenuation is affected by mode scattering. In conclusion, the CDTR is valid tool for aerodynamic and acoustic evaluation of duct treatment

Decision curve analysis revisited: overall net benefit, relationships to ROC curve analysis, and application to case-control studies.

PubMed

Rousson, Valentin; Zumbrunn, Thomas

2011-06-22

Decision curve analysis has been introduced as a method to evaluate prediction models in terms of their clinical consequences if used for a binary classification of subjects into a group who should and into a group who should not be treated. The key concept for this type of evaluation is the "net benefit", a concept borrowed from utility theory. We recall the foundations of decision curve analysis and discuss some new aspects. First, we stress the formal distinction between the net benefit for the treated and for the untreated and define the concept of the "overall net benefit". Next, we revisit the important distinction between the concept of accuracy, as typically assessed using the Youden index and a receiver operating characteristic (ROC) analysis, and the concept of utility of a prediction model, as assessed using decision curve analysis. Finally, we provide an explicit implementation of decision curve analysis to be applied in the context of case-control studies. We show that the overall net benefit, which combines the net benefit for the treated and the untreated, is a natural alternative to the benefit achieved by a model, being invariant with respect to the coding of the outcome, and conveying a more comprehensive picture of the situation. Further, within the framework of decision curve analysis, we illustrate the important difference between the accuracy and the utility of a model, demonstrating how poor an accurate model may be in terms of its net benefit. Eventually, we expose that the application of decision curve analysis to case-control studies, where an accurate estimate of the true prevalence of a disease cannot be obtained from the data, is achieved with a few modifications to the original calculation procedure. We present several interrelated extensions to decision curve analysis that will both facilitate its interpretation and broaden its potential area of application.

Decision curve analysis revisited: overall net benefit, relationships to ROC curve analysis, and application to case-control studies

PubMed Central

2011-01-01

Background Decision curve analysis has been introduced as a method to evaluate prediction models in terms of their clinical consequences if used for a binary classification of subjects into a group who should and into a group who should not be treated. The key concept for this type of evaluation is the "net benefit", a concept borrowed from utility theory. Methods We recall the foundations of decision curve analysis and discuss some new aspects. First, we stress the formal distinction between the net benefit for the treated and for the untreated and define the concept of the "overall net benefit". Next, we revisit the important distinction between the concept of accuracy, as typically assessed using the Youden index and a receiver operating characteristic (ROC) analysis, and the concept of utility of a prediction model, as assessed using decision curve analysis. Finally, we provide an explicit implementation of decision curve analysis to be applied in the context of case-control studies. Results We show that the overall net benefit, which combines the net benefit for the treated and the untreated, is a natural alternative to the benefit achieved by a model, being invariant with respect to the coding of the outcome, and conveying a more comprehensive picture of the situation. Further, within the framework of decision curve analysis, we illustrate the important difference between the accuracy and the utility of a model, demonstrating how poor an accurate model may be in terms of its net benefit. Eventually, we expose that the application of decision curve analysis to case-control studies, where an accurate estimate of the true prevalence of a disease cannot be obtained from the data, is achieved with a few modifications to the original calculation procedure. Conclusions We present several interrelated extensions to decision curve analysis that will both facilitate its interpretation and broaden its potential area of application. PMID:21696604

Automated data processing and radioassays.

PubMed

Samols, E; Barrows, G H

1978-04-01

Radioassays include (1) radioimmunoassays, (2) competitive protein-binding assays based on competition for limited antibody or specific binding protein, (3) immunoradiometric assay, based on competition for excess labeled antibody, and (4) radioreceptor assays. Most mathematical models describing the relationship between labeled ligand binding and unlabeled ligand concentration have been based on the law of mass action or the isotope dilution principle. These models provide useful data reduction programs, but are theoretically unfactory because competitive radioassay usually is not based on classical dilution principles, labeled and unlabeled ligand do not have to be identical, antibodies (or receptors) are frequently heterogenous, equilibrium usually is not reached, and there is probably steric and cooperative influence on binding. An alternative, more flexible mathematical model based on the probability or binding collisions being restricted by the surface area of reactive divalent sites on antibody and on univalent antigen has been derived. Application of these models to automated data reduction allows standard curves to be fitted by a mathematical expression, and unknown values are calculated from binding data. The vitrues and pitfalls are presented of point-to-point data reduction, linear transformations, and curvilinear fitting approaches. A third-order polynomial using the square root of concentration closely approximates the mathematical model based on probability, and in our experience this method provides the most acceptable results with all varieties of radioassays. With this curvilinear system, linear point connection should be used between the zero standard and the beginning of significant dose response, and also towards saturation. The importance is stressed of limiting the range of reported automated assay results to that portion of the standard curve that delivers optimal sensitivity. Published methods for automated data reduction of Scatchard plots for radioreceptor assay are limited by calculation of a single mean K value. The quality of the input data is generally the limiting factor in achieving good precision with automated as it is with manual data reduction. The major advantages of computerized curve fitting include: (1) handling large amounts of data rapidly and without computational error; (2) providing useful quality-control data; (3) indicating within-batch variance of the test results; (4) providing ongoing quality-control charts and between assay variance.

Surgical treatment of double thoracic adolescent idiopathic scoliosis with a rigid proximal thoracic curve.

PubMed

Sudo, Hideki; Abe, Yuichiro; Abumi, Kuniyoshi; Iwasaki, Norimasa; Ito, Manabu

2016-02-01

There is limited consensus on the optimal surgical strategy for double thoracic adolescent idiopathic scoliosis (AIS). Recent studies have reported that pedicle screw constructs to maximize scoliosis correction cause further thoracic spine lordosis. The objective of this study was to apply a new surgical technique for double thoracic AIS with rigid proximal thoracic (PT) curves and assess its clinical outcomes. Twenty one consecutive patients with Lenke 2 AIS and a rigid PT curve (Cobb angle ≥30º on side-bending radiographs, flexibility ≤30 %) treated with the simultaneous double-rod rotation technique (SDRRT) were included. In this technique, a temporary rod is placed at the concave side of the PT curve. Then, distraction force is applied to correct the PT curve, which reforms a sigmoid double thoracic curve into an approximate single thoracic curve. As a result, the PT curve is typically converted from an apex left to an apex right curve before applying the correction rod for PT and main thoracic curve. All patients were followed for at least 2 years (average 2.7 years). The average main thoracic and PT Cobb angle correction rate at the final follow-up was 74.7 and 58.0 %, respectively. The average preoperative T5-T12 thoracic kyphosis was 9.3°, which improved significantly to 19.0° (p < 0.0001) at the final follow-up. Although 71 % patients had preoperative level shoulders or a positive radiographic shoulder height, all patients had mildly imbalanced or balanced shoulders at the final follow-up. The average preoperative main thoracic apical vertebral rotation angle of 20.7° improved significantly after surgery to 16.4° (p = 0.0046), while the average preoperative total SRS questionnaire score of 3.7 improved significantly to 4.4 (p = 0.0012) at the final follow-up. Radiographic findings and patient outcomes were satisfactory. Thoracic kyphosis can be maintained or improved, while coronal and axial deformities can be corrected using SDRRT for Lenke 2 AIS with a rigid PT curve.

Observations from varying the lift and drag inputs to a noise prediction method for supersonic helical tip speed propellers

NASA Technical Reports Server (NTRS)

Dittmar, J. H.

1984-01-01

Previous comparisons between calculated and measured supersonic helical tip speed propeller noise show them to have different trends of peak blade passing tone versus helical tip Mach number. It was postulated that improvements in this comparison could be made first by including the drag force terms in the prediction and then by reducing the blade lift terms at the tip to allow the drag forces to dominate the noise prediction. Propeller hub to tip lift distributions were varied, but they did not yield sufficient change in the predicted lift noise to improve the comparison. This result indicates that some basic changes in the theory may be needed. In addition, the noise predicted by the drag forces did not exhibit the same curve shape as the measured data. So even if the drag force terms were to dominate, the trends with helical tip Mach number for theory and experiment would still not be the same. The effect of the blade shock wave pressure rise was approxmated by increasing the drag coefficient at the blade tip. Predictions using this shock wdave approximation did have a curve shape similar to the measured data. This result indicates that the shock pressure rise probably controls the noise at supersonic tip speed and that the linear prediction method can give the proper noise trend with Mach number.

Non-Faradaic electrochemical detection of protein interactions by integrated neuromorphic CMOS sensors.

PubMed

Jacquot, Blake C; Muñoz, Nini; Branch, Darren W; Kan, Edwin C

2008-05-15

Electronic detection of the binding event between biotinylated bovine serum albumen (BSA) and streptavidin is demonstrated with the chemoreceptive neuron MOS (CnuMOS) device. Differing from the ion-sensitive field-effect transistors (ISFET), CnuMOS, with the potential of the extended floating gate determined by both the sensing and control gates in a neuromorphic style, can provide protein detection without requiring analyte reference electrodes. In comparison with the microelectrode arrays, measurements are gathered through purely capacitive, non-Faradaic interactions across insulating interfaces. By using a (3-glycidoxypropyl)trimethoxysilane (3-GPS) self-assembled monolayer (SAM) as a simple covalent link for attaching proteins to a silicon dioxide sensing surface, a fully integrated, electrochemical detection platform is realized for protein interactions through monotone large-signal measurements or small-signal impedance spectroscopy. Calibration curves were created to coordinate the sensor response with ellipsometric measurements taken on witness samples. By monitoring the film thickness of streptavidin capture, a sensitivity of 25ng/cm2 or 2A of film thickness was demonstrated. With an improved noise floor the sensor can detect down to 2ng/(cm2mV) based on the calibration curve. AC measurements are shown to significantly reduce long-term sensor drift. Finally, a noise analysis of electrochemical data indicates 1/f(alpha) behavior with a noise floor beginning at approximately 1Hz.

Study on the combustion process in a modern diesel engine controlled by pre-injection strategy

NASA Astrophysics Data System (ADS)

Punov, P.; Milkov, N.; Perilhon, C.; Podevin, P.; Evtimov, T.

2017-10-01

The paper aims to study the combustion process in a modern diesel engine over the engine operating map. In order to study the rate of heat release (ROHR), an automotive diesel engine was experimentally tested using the injection parameters factory defined. The experimental test was conducted over the engine operating map as the engine speed was limited to 2400 rpm. Then, an engine simulation model was developed in AVL Boost. By means of that model the ROHR was estimated and approximated by means of double Vibe function. In all engine operating points we found two peaks at the ROHR. The first is a result of the pilot injection as the second corresponds to the main injection. There was not found an overlap between both peaks. It was found that the first peak of ROHR occurs closely before top dead center (BTDC) at partial load than full load. The ROHR peak as a result of main injection begins from 4°BTDC to 18°ATDC. It starts earlier with increasing engine speed and load. The combustion duration varies from 30 ºCA to 70 °CA. In order to verify the results pressure curve was estimated by means of defined Vibe function parameters and combustion duration. As a result, we observed small deviation between measured and simulated pressure curves.

Curvature in Arabidopsis inflorescence stems is limited to the region of amyloplast displacement

NASA Technical Reports Server (NTRS)

Weise, S. E.; Kuznetsov, O. A.; Hasenstein, K. H.; Kiss, J. Z.

2000-01-01

Gravitropic sensing in stems and stem-like organs is hypothesized to occur in the endodermis. However, since the endodermis runs the entire length of the stem, the precise site of gravisensing has been difficult to define. In this investigation of gravisensitivity in inflorescence stems of Arabidopsis, we positioned stems in a high gradient magnetic field (HGMF) on a rotating clinostat. Approximately 40% of the young, wild-type (WT) inflorescences, for all positions tested, curved toward the HGMF in the vicinity of the stem exposed to the field. In contrast, when the wedge was placed in the basal region of older inflorescence stems, no curvature was observed. As a control, the HGMF was applied to a starchless mutant, and 5% of the stems curved toward the field. Microscopy of the endodermis in the WT showed amyloplast displacement in the vicinity of the HGMF. Additional structural studies demonstrated that the basal region of WT stems experienced amyloplast displacement and, therefore, suggest this region is capable of gravity perception. However, increased lignification likely prevented curvature in the basal region. The lack of apical curvature after basal amyloplast displacement indicates that gravity perception in the base is not transmitted to the apex. Thus, these results provide evidence that the signal (and thus, response) resulting from perception in Arabidopsis inflorescence stems is spatially restricted.

Maximized exoEarth candidate yields for starshades

NASA Astrophysics Data System (ADS)

Stark, Christopher C.; Shaklan, Stuart; Lisman, Doug; Cady, Eric; Savransky, Dmitry; Roberge, Aki; Mandell, Avi M.

2016-10-01

The design and scale of a future mission to directly image and characterize potentially Earth-like planets will be impacted, to some degree, by the expected yield of such planets. Recent efforts to increase the estimated yields, by creating observation plans optimized for the detection and characterization of Earth-twins, have focused solely on coronagraphic instruments; starshade-based missions could benefit from a similar analysis. Here we explore how to prioritize observations for a starshade given the limiting resources of both fuel and time, present analytic expressions to estimate fuel use, and provide efficient numerical techniques for maximizing the yield of starshades. We implemented these techniques to create an approximate design reference mission code for starshades and used this code to investigate how exoEarth candidate yield responds to changes in mission, instrument, and astrophysical parameters for missions with a single starshade. We find that a starshade mission operates most efficiently somewhere between the fuel- and exposuretime-limited regimes and, as a result, is less sensitive to photometric noise sources as well as parameters controlling the photon collection rate in comparison to a coronagraph. We produced optimistic yield curves for starshades, assuming our optimized observation plans are schedulable and future starshades are not thrust-limited. Given these yield curves, detecting and characterizing several dozen exoEarth candidates requires either multiple starshades or an η≳0.3.

Effects of high-fiber oat and wheat cereals on postprandial glucose and lipid responses in healthy men.

PubMed

Maki, Kevin C; Davidson, Michael H; Witchger, Mary Sue; Dicklin, Mary R; Subbaiah, Papasani V

2007-09-01

This randomized, crossover study compared the effects of consuming high-fiber oat and wheat cereals on postprandial metabolic profiles in healthy men. Twenty-seven subjects received oat (providing 5.7 g/day beta-glucan) or wheat (control) cereal products, in random order, incorporated into their usual diets for two weeks. Total energy and fiber (approximately 14 g/day) contents of the cereals were matched. A meal tolerance test that included the study cereal and a high-fat milkshake (1240 kcal, 105 g fat) was performed at the end of each treatment period. Postprandial insulin and glucose responses over 10 hours did not differ between treatments. Peak triglyceride concentration was lower after oat vs. wheat cereal consumption [2.3 +/- 1.2 (mean +/- standard deviation) vs. 2.9 +/- 1.3 mmol/L, p = 0.016]. Mean area under the triglyceride curve also tended to be lower (15.1 +/- 8.2 vs. 17.6 +/- 8.6 hours x mmol/L, p = 0.068). The free fatty acid area under the curve was elevated after the oat vs. the wheat products (3.64 +/- 0.91 vs. 3.38 +/- 0.98 hours x mmol/L, p = 0.018). These results suggest that high-fiber oat cereal influenced postprandial triglyceride and free fatty acid levels, which may have implications regarding cardiovascular disease risk.

Schroth Physiotherapeutic Scoliosis-Specific Exercises Added to the Standard of Care Lead to Better Cobb Angle Outcomes in Adolescents with Idiopathic Scoliosis - an Assessor and Statistician Blinded Randomized Controlled Trial.

PubMed

Schreiber, Sanja; Parent, Eric C; Khodayari Moez, Elham; Hedden, Douglas M; Hill, Douglas L; Moreau, Marc; Lou, Edmond; Watkins, Elise M; Southon, Sarah C

2016-01-01

The North American non-surgical standard of care for adolescent idiopathic scoliosis (AIS) includes observation and bracing, but not exercises. Schroth physiotherapeutic scoliosis-specific exercises (PSSE) showed promise in several studies of suboptimal methodology. The Scoliosis Research Society calls for rigorous studies supporting the role of exercises before including it as a treatment recommendation for scoliosis. To determine the effect of a six-month Schroth PSSE intervention added to standard of care (Experimental group) on the Cobb angle compared to standard of care alone (Control group) in patients with AIS. Fifty patients with AIS aged 10-18 years, with curves of 10°-45° and Risser grade 0-5 were recruited from a single pediatric scoliosis clinic and randomized to the Experimental or Control group. Outcomes included the change in the Cobb angles of the Largest Curve and Sum of Curves from baseline to six months. The intervention consisted of a 30-45 minute daily home program and weekly supervised sessions. Intention-to-treat and per protocol linear mixed effects model analyses are reported. In the intention-to-treat analysis, after six months, the Schroth group had significantly smaller Largest Curve than controls (-3.5°, 95% CI -1.1° to -5.9°, p = 0.006). Likewise, the between-group difference in the square root of the Sum of Curves was -0.40°, (95% CI -0.03° to -0.8°, p = 0.046), suggesting that an average patient with 51.2° at baseline, will have a 49.3° Sum of Curves at six months in the Schroth group, and 55.1° in the control group with the difference between groups increasing with severity. Per protocol analyses produced similar, but larger differences: Largest Curve = -4.1° (95% CI -1.7° to -6.5°, p = 0.002) and [Formula: see text] (95% CI -0.8 to 0.2, p = 0.006). Schroth PSSE added to the standard of care were superior compared to standard of care alone for reducing the curve severity in patients with AIS. NCT01610908.

Efficacy of a Fixed Combination of Tetracycline, Chloramphenicol, and Colistimethate Sodium for Treatment of Candida albicans Keratitis.

PubMed

Blanco, Anna R; Nostro, Antonia; D'Angelo, Valeria; D'Arrigo, Manuela; Mazzone, Maria G; Marino, Andreana

2017-08-01

To evaluate the antifungal activity of a fixed antibiotic combination (AC) containing tetracycline (TET), chloramphenicol (CAF), and colistimethate sodium (CS). In vitro: Candida ATCC and clinical strains were used. The minimum inhibitory concentrations (MICs) of AC and of each antibiotic were determined. Fluconazole (FLC) was tested for comparison. Time-killing curves of selected strains were performed. Ex vivo keratitis: corneas were injected intrastromally with the selected strains. After the injection, corneas were divided into groups of treatments: AC, FLC, or saline. Then, the tissues were analyzed for colony-forming units per gram (CFU/g). Propidium iodide (PI) and MitoTracker (MTR) staining were used to investigate the mode of action. Values of MIC required to inhibit the growth of 90% of organisms for the antibiotics alone were higher than FLC. However, their activity was enhanced when used in combination against Candida yeasts. Time-killing curves showed that at 24 hours, AC reduced the load of both strains of approximately 1 Log10 CFU/g compared with the initial inoculum (P < 0.0001). This effect was also significant versus FLC. In ex vivo, AC was effective in decreasing the loads of both strains by 4 Log10 CFU/g with respect to the control. Moreover, it showed higher activity than FLC against Candida albicans ATCC 10231 (1 Log10 CFU/g, P < 0.01 versus control). PI staining demonstrated that CS changed the membrane's permeability, whereas MTR staining demonstrated that TET or CAF altered mitochondrial function. The cells treated with AC and stained showed both effects. In this study, AC showed antifungal efficacy versus Candida spp.; this activity can be due to the synergistic effects of antibiotics in it.

Impact of cardiac hypertrophy on arterial and cardiopulmonary baroreflex control of renal sympathetic nerve activity in anaesthetized rats.

PubMed

Flanagan, Evelyn T; Buckley, Maria M; Aherne, Claire M; Lainis, Fredolin; Sattar, Munavvar; Johns, Edward J

2008-09-01

This study aimed to quantify the effect of cardiac hypertrophy induced with isoprenaline and caffeine on reflex regulation of renal sympathetic nerve activity by the arterial and cardiopulmonary baroreceptors. Male Wistar rats, untreated or given water containing caffeine and subcutaneous (s.c.) isoprenaline every 72 h for 2 weeks or thyroxine s.c. for 7 days, were anaesthetized and prepared for measurement of renal sympathetic nerve activity or cardiac indices. Both isoprenaline-caffeine and thyroxine treatment blunted weight gain but increased heart weight and heart weight to body weight ratio by 40 and 14% (both P<0.01), respectively. In the isoprenaline-caffeine group, the maximal rate of change of left ventricular pressure and the contractility index were higher by 17 and 14% (both P<0.01), respectively, compared with untreated rats. In the isoprenaline-caffeine-treated rats, baroreflex gain curve sensitivity was depressed by approximately 30% (P<0/05), while the mid-point blood pressure was lower, by 15% (P<0/05), and the range of the curve was 60% (P<0.05) greater than in the untreated rats. An acute intravenous infusion of a saline load decreased renal sympathetic nerve activity by 42% (P<0.05) in the untreated rats but had no effect in the isoprenaline-caffeine- or the thyroxine-treated groups. The isoprenaline-caffeine treatment induced cardiac hypertrophy with raised cardiac performance and an associated depression in the reflex regulation of renal sympathetic nerve activity by both high- and low-pressure baroreceptors. The thyroxine-induced cardiac hypertrophy also blunted the low-pressure baroreceptor-mediated renal sympatho-inhibition. These findings demonstrate that in cardiac hypertrophy without impaired cardiac function, there is a blunted baroreceptor control of renal sympathetic outflow.

An Empirical Fitting Method for Type Ia Supernova Light Curves: A Case Study of SN 2011fe

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

Zheng, WeiKang; Filippenko, Alexei V., E-mail: zwk@astro.berkeley.edu

We present a new empirical fitting method for the optical light curves of Type Ia supernovae (SNe Ia). We find that a variant broken-power-law function provides a good fit, with the simple assumption that the optical emission is approximately the blackbody emission of the expanding fireball. This function is mathematically analytic and is derived directly from the photospheric velocity evolution. When deriving the function, we assume that both the blackbody temperature and photospheric velocity are constant, but the final function is able to accommodate these changes during the fitting procedure. Applying it to the case study of SN 2011fe givesmore » a surprisingly good fit that can describe the light curves from the first-light time to a few weeks after peak brightness, as well as over a large range of fluxes (∼5 mag, and even ∼7 mag in the g band). Since SNe Ia share similar light-curve shapes, this fitting method has the potential to fit most other SNe Ia and characterize their properties in large statistical samples such as those already gathered and in the near future as new facilities become available.« less

The Mission Accessible Near-Earth Objects Survey (MANOS): First Photometric Results

NASA Astrophysics Data System (ADS)

Thirouin, A.; Moskovitz, N.; Binzel, R. P.; Christensen, E.; DeMeo, F. E.; Person, M. J.; Polishook, D.; Thomas, C. A.; Trilling, D.; Willman, M.; Hinkle, M.; Burt, B.; Avner, D.; Aceituno, F. J.

2016-12-01

The Mission Accessible Near-Earth Objects Survey aims to physically characterize sub-km near-Earth objects (NEOs). We report the first photometric results from the survey that began in 2013 August. Photometric observations were performed using 1-4 m class telescopes around the world. We present rotational periods and light curve amplitudes for 86 sub-km NEOs, though in some cases only lower limits are provided. Our main goal is to obtain light curves for small NEOs (typically, sub-km objects) and estimate their rotational periods, light curve amplitudes, and shapes. These properties are used for a statistical study to constrain overall properties of the NEO population. A weak correlation seems to indicate that smaller objects are more spherical than larger ones. We also report seven NEOs that are fully characterized (light curve and visible spectra) as the most suitable candidates for a future human or robotic mission. Viable mission targets are objects fully characterized, with Δv NHATS ≤ 12 km s-1, and a rotational period P > 1 hr. Assuming a similar rate of object characterization as reported in this paper, approximately 1230 NEOs need to be characterized in order to find 100 viable mission targets.

Base flow of streams in the outcrop area of southeastern sand aquifer, South Carolina, Georgia, Alabama, and Mississippi

USGS Publications Warehouse

Stricker, Virginia

1983-01-01

The base flow component of streamflow was separated from hydrographs for unregulated streams in the Cretaceous and Tertiary clastic outcrop area of South Carolina, Georgia, Alabama, and Mississippi. The base flow values are used in estimating recharge to the sand aquifer. Relations developed between mean annual base flow and stream discharge at the 60- and 65-percent streamflow duration point can be used to approximate mean annual base flow in lieu of hydrograph separation methods for base flows above 10 cu ft/s. Base flow recession curves were used to derive estimates of hydraulic diffusivity of the aquifer which was converted to transmissivity using estimated specific yield. These base-flow-derived transmissivities are in general agreement with transmissivities derived from well data. The shape of flow duration curves of streams is affected by the lithology of the Coastal Plain sediments. Steep flow duration curves appear to be associated with basins underlain by clay or chalk where a low percentage of the discharge is base flow while flatter curves appear to be associated with basins underlain by sand and gravel where a high percentage of the discharge is base flow. (USGS)

Analyser-based phase contrast image reconstruction using geometrical optics.

PubMed

Kitchen, M J; Pavlov, K M; Siu, K K W; Menk, R H; Tromba, G; Lewis, R A

2007-07-21

Analyser-based phase contrast imaging can provide radiographs of exceptional contrast at high resolution (<100 microm), whilst quantitative phase and attenuation information can be extracted using just two images when the approximations of geometrical optics are satisfied. Analytical phase retrieval can be performed by fitting the analyser rocking curve with a symmetric Pearson type VII function. The Pearson VII function provided at least a 10% better fit to experimentally measured rocking curves than linear or Gaussian functions. A test phantom, a hollow nylon cylinder, was imaged at 20 keV using a Si(1 1 1) analyser at the ELETTRA synchrotron radiation facility. Our phase retrieval method yielded a more accurate object reconstruction than methods based on a linear fit to the rocking curve. Where reconstructions failed to map expected values, calculations of the Takagi number permitted distinction between the violation of the geometrical optics conditions and the failure of curve fitting procedures. The need for synchronized object/detector translation stages was removed by using a large, divergent beam and imaging the object in segments. Our image acquisition and reconstruction procedure enables quantitative phase retrieval for systems with a divergent source and accounts for imperfections in the analyser.

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

Thirouin, A.; Moskovitz, N.; Burt, B.

The Mission Accessible Near-Earth Objects Survey aims to physically characterize sub-km near-Earth objects (NEOs). We report the first photometric results from the survey that began in 2013 August. Photometric observations were performed using 1–4 m class telescopes around the world. We present rotational periods and light curve amplitudes for 86 sub-km NEOs, though in some cases only lower limits are provided. Our main goal is to obtain light curves for small NEOs (typically, sub-km objects) and estimate their rotational periods, light curve amplitudes, and shapes. These properties are used for a statistical study to constrain overall properties of the NEOmore » population. A weak correlation seems to indicate that smaller objects are more spherical than larger ones. We also report seven NEOs that are fully characterized (light curve and visible spectra) as the most suitable candidates for a future human or robotic mission. Viable mission targets are objects fully characterized, with Δ v {sup NHATS} ≤ 12 km s{sup −1}, and a rotational period P  > 1 hr. Assuming a similar rate of object characterization as reported in this paper, approximately 1230 NEOs need to be characterized in order to find 100 viable mission targets.« less

Stability of the body-centred-cubic phase of iron in the Earth's inner core.

PubMed

Belonoshko, Anatoly B; Ahuja, Rajeev; Johansson, Börje

2003-08-28

Iron is thought to be the main constituent of the Earth's core, and considerable efforts have therefore been made to understand its properties at high pressure and temperature. While these efforts have expanded our knowledge of the iron phase diagram, there remain some significant inconsistencies, the most notable being the difference between the 'low' and 'high' melting curves. Here we report the results of molecular dynamics simulations of iron based on embedded atom models fitted to the results of two implementations of density functional theory. We tested two model approximations and found that both point to the stability of the body-centred-cubic (b.c.c.) iron phase at high temperature and pressure. Our calculated melting curve is in agreement with the 'high' melting curve, but our calculated phase boundary between the hexagonal close packed (h.c.p.) and b.c.c. iron phases is in good agreement with the 'low' melting curve. We suggest that the h.c.p.-b.c.c. transition was previously misinterpreted as a melting transition, similar to the case of xenon, and that the b.c.c. phase of iron is the stable phase in the Earth's inner core.

A guidance manual for assessing scour potential using the South Carolina bridge-scour envelope curves

USGS Publications Warehouse

Benedict, Stephen T.; Caldwell, Andral W.; Feaster, Toby D.

2014-01-01

The U.S. Geological Survey, in cooperation with the South Carolina Department of Transportation, conducted a series of three field investigations of bridge scour in order to better understand regional trends of scour within South Carolina. The studies collected historic-scour data at approximately 200 riverine bridges including measurements of clear-water abutment, contraction, and pier scour, as well as live-bed contraction and pier scour. These investigations provided valuable insights for regional scour trends and yielded bridge-scour envelope curves for assessing scour potential associated with all components of scour at riverine bridges in South Carolina. The application and limitations of these envelop cureves were documents in three reports, Each repoort addresses different components of bridge scour and this, there is a need to develop an integrated procedure for applying the South Carolina bridge-scour envelope curves. To address this need, the U.S. Geological Survey and the South Carolina Department of Transportation initiated a cooperative effort to develop an integrated procedure and document the method in a guidance manual. In addition to developing the integrated procedure, field data from other investigations outside of South Carolina were used to verify the South Carolina bridge-source envelope curves.

Protoplast Volume:Water Potential Relationship and Bound Water Fraction in Spinach Leaves 1

PubMed Central

Santakumari, Mane; Berkowitz, Gerald A.

1989-01-01

Methods used to estimate the (nonosmotic) bound water fraction (BWF) (i.e. apoplast water) of spinach (Spinacia oleracea L.) leaves were evaluated. Studies using three different methods of pressure/volume (P/V) curve construction all resulted in a similar calculation of BWF; approximately 40%. The theoretically derived BWF, and the water potential (Ψw)/relative water content relationship established from P/V curves were used to establish the relationship between protoplast (i.e. symplast) volume and Ψw. Another method of establishing the protoplast volume/Ψw relationship in spinach leaves was compared with the results from P/V curve experiments. This second technique involved the vacuum infiltration of solutions at a range of osmotic potentials into discs cut from spinach leaves. These solutions contained radioactively labeled H2O and sorbitol. This dual label infiltration technique allowed for simultaneous measurement of the total and apoplast volumes in leaf tissue; the difference yielded the protoplast volume. The dual label infiltration experiments and the P/V curve constructions both showed that below −1 megapascals, protoplast volume decreases sharply with decreasing water potential; with 50% reduction in protoplast volume occurring at −1.8 megapascals leaf water potential. PMID:16666983

The X-Ray Light Curve of the Very Luminous Supernova SN 1978K in NGC 1313

NASA Astrophysics Data System (ADS)

Schlegel, Eric M.; Petre, R.; Colbert, E. J. M.

1996-01-01

We present the 0.5-2.0 keV light curve of the X-ray luminous supernova SN 1978K in NGC 1313, based on six ROSAT observations spanning 1990 July to t994 July. SN 1978K is one of a few supernovae or supernova remnants that are very luminous (˜1039-1040 ergs s-1) in the X-ray, optical, and radio bands, and the first, at a supernova age of 10-20 yr, for which sufficient data exist to create an X-ray light curve. The X-ray flux is approximately constant over the 4 yr sampled by our observations, which were obtained 12-16 yr after the initial explosion. Three models exist to explain the large X-ray luminosity: pulsar input, a reverse shock running back into the expanding debris of the supernova, and the outgoing shock crushing of cloudlets in the debris field. Based upon calculations of Chevalier & Fransson, a pulsar cannot provide sufficient energy to produce the soft X-ray luminosity. Based upon the models and the light curve to date, it is not possible to discern the evolutionary phase of the supernova.

Meteor stream activity. 2: Meteor outbursts

NASA Technical Reports Server (NTRS)

Jenniskens, P.

1995-01-01

In the past two centuries, alert amateur and professional meteor astronomers have documented 35 outbursts of 17 individual meteor streams well enough to allow the construction of a homogeneous set of activity curves. These curves add to similar profiles of the annual streams in a previous paper (Paper 1). This paper attempts to define the type and range of phenomena that classify as meteor outbursts from which the following is concluded: Outbursts are associated with the return of the comet to perihelion (near-comet type outbursts), but occur also when the parent comet is far from perihelion and far from the Earth (far-comet type). All outbursts of a given type only, depending on encounter geometry. The activity curves, expressed in terms of Zenith Hourly Rates (ZHR), have a shape that is generally well described by: ZHR = ZHR(sub max) 10(sup(-B (the absolute value of lambda (sub dot in a circle) - lambda (sup max) (sub dot in a circle))). The steepness of the slopes varies from an exponent of B = 7 to B = 220 per degree of solar longitude, with a typical value of B = 30. In addition, most near-comet type outbursts have a broader component underlying the main peak with B approximately 1 - 7.The duration Delta t is approximately 1/B of the main peak is almost independent of location near the comet, while the background component varies considerably in duration and relative intensity from one return to another. The two components in the activity curve are due to two distinct structures in the dust distribution near the parent comet, where the main component can be due to a sheet of dust that emanates from the IRAS dust trail. This brings the total number of distinct structures in meteor streams to four, including the two structures from the annual stream activity in Paper 1.

Half a billion surgical cases: Aligning surgical delivery with best-performing health systems.

PubMed

Shrime, Mark G; Daniels, Kimberly M; Meara, John G

2015-07-01

Surgical delivery varies 200-fold across countries. No direct correlation exists, however, between surgical delivery and health outcomes, making it difficult to pinpoint a goal for surgical scale-up. This report determines the amount of surgery that would be delivered worldwide if the world aligned itself with countries providing the best health outcomes. Annual rates of surgical delivery have been published previously for 129 countries. Five health outcomes were plotted against reported surgical delivery. Univariate and multivariate polynomial regression curves were fit, and the optimal point on each regression curve was determined by solving for first-order conditions. The country closest to the optimum for each health outcome was taken as representative of the best-performing health system. Monetary inputs to and surgical procedures provided by these systems were scaled to the global population. For 3 of the 5 health outcomes, optima could be found. Globally, 315 million procedures currently are provided annually. If global delivery mirrored the 3 best-performing countries, between 360 million and 460 million cases would be provided annually. With population growth, this will increase to approximately half a billion cases by 2030. Health systems delivering these outcomes spend approximately 10% of their GDP on health. This is the first study to provide empirical evidence for the surgical output that an ideal health system would provide. Our results project ideal delivery worldwide of approximately 550 million annual surgical cases by 2030. Copyright © 2015 Elsevier Inc. All rights reserved.

Half a billion surgical cases: Aligning surgical delivery with best-performing health systems

PubMed Central

Shrime, Mark G.; Daniels, Kimberly M.; Meara, John G.

2015-01-01

Background Surgical delivery varies 200-fold across countries. No direct correlation exists, however, between surgical delivery and health outcomes, making it difficult to pinpoint a goal for surgical scale-up. This report determines the amount of surgery that would be delivered worldwide if the world aligned itself with countries providing the best health outcomes. Methods Annual rates of surgical delivery have been published previously for 129 countries. Five health outcomes were plotted against reported surgical delivery. Univariate and multivariate polynomial regression curves were fit, and the optimal point on each regression curve was determined by solving for first-order conditions. The country closest to the optimum for each health outcome was taken as representative of the best-performing health system. Monetary inputs to and surgical procedures provided by these systems were scaled to the global population. Results For 3 of the 5 health outcomes, optima could be found. Globally, 315 million procedures currently are provided annually. If global delivery mirrored the 3 best-performing countries, between 360 million and 460 million cases would be provided annually. With population growth, this will increase to approximately half a billion cases by 2030. Health systems delivering these outcomes spend approximately 10% of their GDP on health. Conclusion This is the first study to provide empirical evidence for the surgical output that an ideal health system would provide. Our results project ideal delivery worldwide of approximately 550 million annual surgical cases by 2030. PMID:25934078

Motor-substrate interactions in mycoplasma motility explains non-Arrhenius temperature dependence.

PubMed

Chen, Jing; Neu, John; Miyata, Makoto; Oster, George

2009-12-02

Mycoplasmas exhibit a novel, substrate-dependent gliding motility that is driven by approximately 400 "leg" proteins. The legs interact with the substrate and transmit the forces generated by an assembly of ATPase motors. The velocity of the cell increases linearly by nearly 10-fold over a narrow temperature range of 10-40 degrees C. This corresponds to an Arrhenius factor that decreases from approximately 45 k(B)T at 10 degrees C to approximately 10 k(B)T at 40 degrees C. On the other hand, load-velocity curves at different temperatures extrapolate to nearly the same stall force, suggesting a temperature-insensitive force-generation mechanism near stall. In this article, we propose a leg-substrate interaction mechanism that explains the intriguing temperature sensitivity of this motility. The large Arrhenius factor at low temperature comes about from the addition of many smaller energy barriers arising from many substrate-binding sites at the distal end of the leg protein. The Arrhenius dependence attenuates at high temperature due to two factors: 1), the reduced effective multiplicity of energy barriers intrinsic to the multiple-site binding mechanism; and 2), the temperature-sensitive weakly facilitated leg release that curtails the power stroke. The model suggests an explanation for the similar steep, sub-Arrhenius temperature-velocity curves observed in many molecular motors, such as kinesin and myosin, wherein the temperature behavior is dominated not by the catalytic biochemistry, but by the motor-substrate interaction.

Coupled out of plane vibrations of spiral beams for micro-scale applications

NASA Astrophysics Data System (ADS)

Amin Karami, M.; Yardimoglu, Bulent; Inman, Daniel J.

2010-12-01

An analytical method is proposed to calculate the natural frequencies and the corresponding mode shape functions of an Archimedean spiral beam. The deflection of the beam is due to both bending and torsion, which makes the problem coupled in nature. The governing partial differential equations and the boundary conditions are derived using Hamilton's principle. Two factors make the vibrations of spirals different from oscillations of constant radius arcs. The first is the presence of terms with derivatives of the radius in the governing equations of spirals and the second is the fact that variations of radius of the beam causes the coefficients of the differential equations to be variable. It is demonstrated, using perturbation techniques that the derivative of the radius terms have negligible effect on structure's dynamics. The spiral is then approximated with many merging constant-radius curved sections joined together to approximate the slow change of radius along the spiral. The equations of motion are formulated in non-dimensional form and the effect of all the key parameters on natural frequencies is presented. Non-dimensional curves are used to summarize the results for clarity. We also solve the governing equations using Rayleigh's approximate method. The fundamental frequency results of the exact and Rayleigh's method are in close agreement. This to some extent verifies the exact solutions. The results show that the vibration of spirals is mostly torsional which complicates using the spiral beam as a host for a sensor or energy harvesting device.

Right and left ventricular volumes in vitro by a new nongeometric method

NASA Technical Reports Server (NTRS)

Buckey, J. C.; Beattie, J. M.; Nixon, J. V.; Gaffney, F. A.; Blomqvist, C. G.

1987-01-01

We present an evaluation of a new nongeometric technique for calculating right and left ventricular volumes. This method calculates ventricular chamber volumes from multiple cross-sectional echocardiographic views taken from a single point as the echo beam is tilted progressively through the ventricle. Right and left ventricular volumes are calculated from both the approximate short axis and approximate apical position on 20 in vitro human hearts and compared with the actual chamber volumes. The results for both ventricles from both positions are excellent. Correlation coefficients are > 0.95 for all positions; the standard errors are in the range of 5 to 7 mL and the slopes and intercepts for the regression lines are not significantly different from 1 and 0, respectively (except for the left ventricular short-axis intercept). For all positions, approximately 6 to 8 views are needed for peak accuracy (7.5 degrees to 10 degrees separation). This approach offers several advantages. No geometric assumptions about ventricular shape are made. All images are acquired from a single point (or window), and the digitized points can be used to make a three-dimensional reconstruction of the ventricle. Also, during the calculations a volume distribution curve for the ventricle is produced. The shape of this curve can be characteristic for certain situations (ie, right ventricle, short axis) and can be used to make new simple equations for calculating volume. We conclude that this is an accurate nongeometric method for determining both right and left ventricular volumes in vitro.

Strong shock implosion, approximate solution

NASA Astrophysics Data System (ADS)

Fujimoto, Y.; Mishkin, E. A.; Alejaldre, C.

1983-01-01

The self-similar, center-bound motion of a strong spherical, or cylindrical, shock wave moving through an ideal gas with a constant, γ= cp/ cv, is considered and a linearized, approximate solution is derived. An X, Y phase plane of the self-similar solution is defined and the representative curved of the system behind the shock front is replaced by a straight line connecting the mappings of the shock front with that of its tail. The reduced pressure P(ξ), density R(ξ) and velocity U1(ξ) are found in closed, quite accurate, form. Comparison with numerically obtained results, for γ= {5}/{3} and γ= {7}/{5}, is shown.

Thermodynamic States of the Mixed Spin 1/2 and Spin 1 Hexagonal Nanowire System Obtained from a Seven-Site Cluster Within an Improved Mean Field Approximation

NASA Astrophysics Data System (ADS)

Mendes, R. G. B.; Barreto, F. C. Sá; Santos, J. P.

2018-04-01

The mean field approximation results in the mixedspin 1/2 Ising model and spin 1 Blume-Capel model, in the hexagonal nanowire system, are obtained from the Bogoliubov inequality. The Gibbs free energy, magnetization, and critical frontiers are obtained. Besides the stable branches of the order parameters, we obtain the metastable and unstable parts of these curves and also find phase transitions of the metastable branches of the order parameters. The classification of the stable, metastable, and unstable states is made by comparing the free energy values of these states.

Driver for solar cell I-V characteristic plots

NASA Technical Reports Server (NTRS)

Turner, G. B. (Inventor)

1980-01-01

A bipolar voltage ramp generator which applies a linear voltage through a resistor to a solar cell for plotting its current versus voltage (I-V) characteristic between short circuit and open circuit conditions is disclosed. The generator has automatic stops at the end points. The resistor serves the multiple purpose of providing a current sensing resistor, setting the full-scale current value, and providing a load line with a slope approximately equal to one, such that it will pass through the origin and the approximate center of the I-V curve with about equal distance from that center to each of the end points.

Composite prepreg application device

NASA Technical Reports Server (NTRS)

Sandusky, Donald A. (Inventor); Marchello, Joseph M. (Inventor)

1996-01-01

A heated shoe and cooled pressure roller assembly for composite prepreg application is provided. The shoe assembly includes a heated forward contact surface having a curved pressure surface. The following cooled roller provides a continuous pressure to the thermoplastic while reducing the temperature to approximately 5.degree. C. below glass transition temperature. Electric heating coils inside the forward portion of the shoe heat a thermoplastic workpiece to approximately 100.degree. C. above the glass transition. Immediately following the heated contact surface, a cooled roller cools the work. The end sharpened shape of the heated shoe trailing edge tends to prevent slag buildup and maintain a uniform, relaxed stress fabrication.

Magnetization of the Ising model on the Sierpinski pastry-shell

NASA Astrophysics Data System (ADS)

Chame, Anna; Branco, N. S.

1992-02-01

Using a real-space renormalization group approach, we calculate the approximate magnetization in the Ising model on the Sierpinski Pastry-shell. We consider, as an approximation, only two regions of the fractal: the internal surfaces, or walls (sites on the border of eliminated areas), with coupling constants JS, and the bulk (all other sites), with coupling constants Jv. We obtain the mean magnetization of the two regions as a function of temperature, for different values of α= JS/ JV and different geometric parameters b and l. Curves present a step-like behavior for some values of b and l, as well as different universality classes for the bulk transition.

Another collision for the Coma cluster

NASA Technical Reports Server (NTRS)

Vikhlinin, A.; Forman, W.; Jones, C.

1996-01-01

The wavelet transform analysis of the Rosat position sensitive proportional counter (PSPC) images of the Coma cluster are presented. The analysis shows, on small scales, a substructure dominated by two extended sources surrounding the two bright clusters NGC 4874 and NGC 4889. On scales of about 2 arcmin to 3 arcmin, the analysis reveals a tail of X-ray emission originating near the cluster center, curving to the south and east for approximately 25 arcmin and ending near the galaxy NGC 4911. The results are interpreted in terms of a merger of a group, having a core mass of approximately 10(exp 13) solar mass, with the main body of the Coma cluster.