Evaluating the performance of skewed prestressed concrete bridge after strengthening
NASA Astrophysics Data System (ADS)
Naser, Ali; Zonglin, Wang
2013-06-01
The objectives of this paper are to explain the application of repairing and strengthening methods on the damaged members of the bridge structure, to analyze the static and dynamic structural response under static and dynamic loads after strengthening, and to evaluate the structural performance after application of strengthening method. The repairing and strengthening methods which are used in this study include treatment of the cracks, thickening the web of box girder along the bridge length and adding internal pre-stressing tendons in the thickening web, and construct reinforced concrete cross beams (diaphragms) between two box girders. The results of theoretical analysis of static and dynamic structural responses after strengthening show that the tensile stresses are decreased and become less than the allowable limit values in the codes. The values of vertical deflection are decreased after strengthening. The values of natural frequencies after strengthening are increased, indicating that the strengthening method is effective to reduce the vibration of the bridge structure. Therefore, the strengthening methods are effective to improve the bearing capacity and elastic working state of the bridge structure and to increase the service life of the bridge structure.
Truck loading positions for maximum live load girder moment in skewed integral bridges
NASA Astrophysics Data System (ADS)
Yalcin, O. Fatih
2015-12-01
In this study, the effect of the longitudinal and transverse truck positions on the distribution of live load moment among the girders of skewed integral abutment bridges (SIBs) is investigated. For this purpose, three dimensional finite element models (FEMs) of several single-span SIBs are built and analyzed. In the analyses, bridges with various skew angles under all possible single and double truck loading positions both in longitudinal and transverse directions are considered. An automated analysis procedure managed by a visual basic program is developed to obtain the structural models and apply the wheel loads of trucks. The finite element analyses (FEA) results are then used to find the most critical loading cases of single truck and adjacent two trucks for the live load moment in the girders of SIBs. The results revealed that, the trucks should be placed nearby the midline of the bridge deck in a diagonal manner.
NASA Astrophysics Data System (ADS)
Ghotbi, Abdoul R.
2014-09-01
The seismic behavior of skewed bridges has not been well studied compared to straight bridges. Skewed bridges have shown extensive damage, especially due to deck rotation, shear keys failure, abutment unseating and column-bent drift. This research, therefore, aims to study the behavior of skewed and straight highway overpass bridges both with and without taking into account the effects of Soil-Structure Interaction (SSI) due to near-fault ground motions. Due to several sources of uncertainty associated with the ground motions, soil and structure, a probabilistic approach is needed. Thus, a probabilistic methodology similar to the one developed by the Pacific Earthquake Engineering Research Center (PEER) has been utilized to assess the probability of damage due to various levels of shaking using appropriate intensity measures with minimum dispersions. The probabilistic analyses were performed for various bridge configurations and site conditions, including sand ranging from loose to dense and clay ranging from soft to stiff, in order to evaluate the effects. The results proved a considerable susceptibility of skewed bridges to deck rotation and shear keys displacement. It was also found that SSI had a decreasing effect on the damage probability for various demands compared to the fixed-base model without including SSI. However, deck rotation for all types of the soil and also abutment unseating for very loose sand and soft clay showed an increase in damage probability compared to the fixed-base model. The damage probability for various demands has also been found to decrease with an increase of soil strength for both sandy and clayey sites. With respect to the variations in the skew angle, an increase in skew angle has had an increasing effect on the amplitude of the seismic response for various demands. Deck rotation has been very sensitive to the increase in the skew angle; therefore, as the skew angle increased, the deck rotation responded accordingly. Furthermore, abutment unseating showed an increasing trend due to an increase in skew angle for both fixed-base and SSI models.
Bridges from top to bottom: Expressway Bridge, Liberty Memorial Bridge, Burlington Northern SantaFe Railway Bridge, and Interstate 94 Grant Marsh Bridge. Photo taken by USGS personnel on a Civil Air Patrol flight....
NASA Astrophysics Data System (ADS)
Audenaert, Koenraad M. R.
2014-11-01
In this paper, we study the quantum generalisation of the skew divergence, which is a dissimilarity measure between distributions introduced by Lee in the context of natural language processing. We provide an in-depth study of the quantum skew divergence, including its relation to other state distinguishability measures. Finally, we present a number of important applications: new continuity inequalities for the quantum Jensen-Shannon divergence and the Holevo information, and a new and short proof of Bravyi's Small Incremental Mixing conjecture.
Audenaert, Koenraad M. R.
2014-11-15
In this paper, we study the quantum generalisation of the skew divergence, which is a dissimilarity measure between distributions introduced by Lee in the context of natural language processing. We provide an in-depth study of the quantum skew divergence, including its relation to other state distinguishability measures. Finally, we present a number of important applications: new continuity inequalities for the quantum Jensen-Shannon divergence and the Holevo information, and a new and short proof of Bravyi's Small Incremental Mixing conjecture.
Skew mapping cataclysmic variables
NASA Astrophysics Data System (ADS)
Smith, R. C.; Vande Putte, D.
2002-01-01
The secondary in CVs is usually detected by correlation of the spectrum with that of a red dwarf template, to produce a radial velocity curve. This method has demonstrated its power, but has limits in case of noisy spectra, as in faint secondaries. To circumvent this difficulty, a method of co-adding spectra, called skew mapping, has been proposed in the past. This paper explores the capabilities of skew mapping in determining the amplitude of the radial velocity for faint secondaries. We record our appreciation to Dr T. R. Marsh for advice on his ``molly'' code. Thanks are due to the observers and data reducers (D. H. P. Jones, N. A. Hawkins, J. Thorstensen, and J. S. Martin).
12. Underside of Skew SpanHot Metal system on right, toward ...
12. Underside of Skew Span-Hot Metal system on right, toward Rocker Bent. - Monongahela Connecting Railroad Company, Hot Metal Bridge, Spanning Monongahela River at mile post 3.1, Pittsburgh, Allegheny County, PA
Measuring Skewness: A Forgotten Statistic?
ERIC Educational Resources Information Center
Doane, David P.; Seward, Lori E.
2011-01-01
This paper discusses common approaches to presenting the topic of skewness in the classroom, and explains why students need to know how to measure it. Two skewness statistics are examined: the Fisher-Pearson standardized third moment coefficient, and the Pearson 2 coefficient that compares the mean and median. The former is reported in statistical…
Skew resisting hydrodynamic seal
Conroy, William T. (Pearland, TX); Dietle, Lannie L. (Sugar Land, TX); Gobeli, Jeffrey D. (Houston, TX); Kalsi, Manmohan S. (Houston, TX)
2001-01-01
A novel hydrodynamically lubricated compression type rotary seal that is suitable for lubricant retention and environmental exclusion. Particularly, the seal geometry ensures constraint of a hydrodynamic seal in a manner preventing skew-induced wear and provides adequate room within the seal gland to accommodate thermal expansion. The seal accommodates large as-manufactured variations in the coefficient of thermal expansion of the sealing material, provides a relatively stiff integral spring effect to minimize pressure-induced shuttling of the seal within the gland, and also maintains interfacial contact pressure within the dynamic sealing interface in an optimum range for efficient hydrodynamic lubrication and environment exclusion. The seal geometry also provides for complete support about the circumference of the seal to receive environmental pressure, as compared the interrupted character of seal support set forth in U.S. Pat. Nos. 5,873,576 and 6,036,192 and provides a hydrodynamic seal which is suitable for use with non-Newtonian lubricants.
Skew chromaticity in large accelerators
Peggs, S.; Dell, G.F.
1995-05-01
The 2-D ``skew chromaticity`` vector k is introduced when the standard on-momentum description of linear coupling is extended to include off-momentum particles. A lattice that is well decoupled on-momentum may be badly decoupled off-momentum, inside the natural momentum spread of the beam. There are two general areas of concern: (1) the free space in the tune plane is decreased; (2) collective phenomena may be destabilized. Two strong new criteria for head-tail stability in the presence of off-momentum coupling are derived, which are consistent with experimental and operational observations at the Tevatron, and with tracking data from RHIC.
Kinematic correction for roller skewing
NASA Technical Reports Server (NTRS)
Savage, M.; Loewenthal, S. H.
1980-01-01
A theory of kinematic stabilization of rolling cylinders is developed for high-speed cylindrical roller bearings. This stabilization requires race and roller crowning to product changes in the rolling geometry as the roller shifts axially. These changes put a reverse skew in the rolling elements by changing the rolling taper. Twelve basic possible bearing modifications are identified in this paper. Four have single transverse convex curvature in the rollers while eight have rollers with compound transverse curvature composed of a central cylindrical band of constant radius surrounded by symmetric bands with both slope and transverse curvature.
Portfolio optimization with skewness and kurtosis
NASA Astrophysics Data System (ADS)
Lam, Weng Hoe; Jaaman, Saiful Hafizah Hj.; Isa, Zaidi
2013-04-01
Mean and variance of return distributions are two important parameters of the mean-variance model in portfolio optimization. However, the mean-variance model will become inadequate if the returns of assets are not normally distributed. Therefore, higher moments such as skewness and kurtosis cannot be ignored. Risk averse investors prefer portfolios with high skewness and low kurtosis so that the probability of getting negative rates of return will be reduced. The objective of this study is to compare the portfolio compositions as well as performances between the mean-variance model and mean-variance-skewness-kurtosis model by using the polynomial goal programming approach. The results show that the incorporation of skewness and kurtosis will change the optimal portfolio compositions. The mean-variance-skewness-kurtosis model outperforms the mean-variance model because the mean-variance-skewness-kurtosis model takes skewness and kurtosis into consideration. Therefore, the mean-variance-skewness-kurtosis model is more appropriate for the investors of Malaysia in portfolio optimization.
Skew deviation after intratympanic gentamicin therapy.
Ng, Diana; Fouladvand, Mohammad; Lalwani, Anil K
2011-03-01
Intratympanic gentamicin therapy for the treatment of episodic vertigo associated with MÃ©niÃ¨re's disease is generally well tolerated. Although auditory and vestibular symptoms following intratympanic gentamicin are well known, visual disturbance has not been previously described. In this report, we describe two patients with MÃ©niÃ¨re's disease who developed sudden onset of binocular vertical diplopia due to skew deviation after intratympanic gentamicin therapy. The skew deviation and diplopia resolved spontaneously and completely within 6 to 8 weeks without therapy. Development of diplopia due to skew deviation should be discussed as a potential complication in patients undergoing intratympanic gentamicin therapy. PMID:21344424
Free Vibration of Symmetrically Laminated Skew Plates
NASA Astrophysics Data System (ADS)
Han, W.; Dickinson, S. M.
1997-12-01
A Ritz approach, developed for the analysis of the vibration of thin, laminated, rectangular plates, is extended to apply to symmetrically laminated, composite, skew plates. There is relatively little information available on the vibration of such skew plates, despite their increasing use in the aerospace industry. A convergence study and comparisons with results available from the literature indicate that the approach presented is reliable and accurate. A fairly extensive set of numerical results is given in graphical form, illustrating the influence of different lamination lay-ups, skew angles and edge conditions on the natural frequencies and nodal patterns of a selection of plates.
HOT METAL BRIDGE (NOTE: BUILDERS: JONES AND LAUGHLIN STEEL CA. ...
HOT METAL BRIDGE (NOTE: BUILDERS: JONES AND LAUGHLIN STEEL CA. 1890), SOUTH PORTAL. THREE PIN CONNECTED CAMELBACK TRUSS SPANS, ONE SKEWED THROUGH TRUSS SPAN ON NORTH SIDE TRUSS BRIDGE, EAST OF HOT METAL BRIDGE BUILT BY AMERICAN BRIDGE COMPANY CA. 1910. (RIVETED MULTI-SPAN TRUSS). - Jones & Laughlin Steel Corporation, Pittsburgh Works, Morgan Billet Mill Engine, 550 feet north of East Carson Street, opposite South Twenty-seventh Street, Pittsburgh, Allegheny County, PA
Skewness and Kurtosis in Statistical Kinetics
NASA Astrophysics Data System (ADS)
Barato, Andre C.; Seifert, Udo
2015-10-01
We obtain lower and upper bounds on the skewness and kurtosis associated with the cycle completion time of unicyclic enzymatic reaction schemes. Analogous to a well-known lower bound on the randomness parameter, the lower bounds on skewness and kurtosis are related to the number of intermediate states in the underlying chemical reaction network. Our results demonstrate that evaluating these higher order moments with single molecule data can lead to information about the enzymatic scheme that is not contained in the randomness parameter.
Skew chicane based betatron eigenmode exchange module
Douglas, David
2010-12-28
A skewed chicane eigenmode exchange module (SCEEM) that combines in a single beamline segment the separate functionalities of a skew quad eigenmode exchange module and a magnetic chicane. This module allows the exchange of independent betatron eigenmodes, alters electron beam orbit geometry, and provides longitudinal parameter control with dispersion management in a single beamline segment with stable betatron behavior. It thus reduces the spatial requirements for multiple beam dynamic functions, reduces required component counts and thus reduces costs, and allows the use of more compact accelerator configurations than prior art design methods.
Bending of skew plates of variable rigidity.
NASA Technical Reports Server (NTRS)
Willems, N.; Mahmood, S. S.
1972-01-01
Description of an analytical procedure for studying the bending of thin skew plates of a thickness varying in one direction, under arbitrary lateral loading. The analysis was programmed for execution on an electronic computer for various conditions and types of loading. The results obtained suggest that the proposed analytical procedure is more accurate than the finite-difference technique used in earlier investigations.
NORMALITY AND SKEWNESS OF GENETIC EVALUATIONS
Technology Transfer Automated Retrieval System (TEKTRAN)
Linear models are used for evaluation of linear, normally distributed traits such as milk yield. Traits (e.g. somatic cell count) with skewed distributions are normalized through log or other simple transformation. Traits with nonlinear, non-normal distributions have gained importance, and alternati...
... Sudden Cardiac Arrest Valve Disease Vulnerable Plaque Myocardial Bridge | Share Related terms: myocardium, coronary arteries, myocardial ischemia ... surface of the heart. What is a myocardial bridge? A myocardial bridge is a band of heart ...
Graf, Darin C.; Warpinski, Norman R.
1996-01-01
A system for single-phase, steady-state permeability measurements of porous rock utilizes a fluid bridge arrangement analogous to a Wheatstone bridge. The arms of the bridge contain the sample and calibrated flow resistors.
Preference patterns for skewed gambles in rhesus monkeys
Strait, Caleb E.; Hayden, Benjamin Y.
2013-01-01
While standard models of risky choice account for the first and second statistical moments of reward outcome distributions (mean and variance, respectively), they often ignore the third moment, skewness. Determining a decision-maker's attitude about skewness is useful because it can help constrain process models of the mental steps involved in risky choice. We measured three rhesus monkeys’ preferences for gambles whose outcome distributions had almost identical means and variances but differed in skewness. We tested five distributions of skewness: strong negative, weak negative, normal, weak positive and strong positive. Monkeys preferred positively skewed gambles to negatively skewed ones and preferred strongly skewed and normal (i.e. unskewed) gambles to weakly skewed ones. This pattern of preferences cannot be explained solely by monotonic deformations of the utility curve or any other popular single account, but can be accounted for by multiple interacting factors. PMID:24335272
Analysis of Parasite and Other Skewed Counts
Alexander, Neal
2012-01-01
Objective To review methods for the statistical analysis of parasite and other skewed count data. Methods Statistical methods for skewed count data are described and compared, with reference to those used over a ten year period of Tropical Medicine and International Health. Two parasitological datasets are used for illustration. Results Ninety papers were identified, 89 with descriptive and 60 with inferential analysis. A lack of clarity is noted in identifying measures of location, in particular the Williams and geometric mean. The different measures are compared, emphasizing the legitimacy of the arithmetic mean for skewed data. In the published papers, the t test and related methods were often used on untransformed data, which is likely to be invalid. Several approaches to inferential analysis are described, emphasizing 1) non-parametric methods, while noting that they are not simply comparisons of medians, and 2) generalized linear modelling, in particular with the negative binomial distribution. Additional methods, such as the bootstrap, with potential for greater use are described. Conclusions Clarity is recommended when describing transformations and measures of location. It is suggested that non-parametric methods and generalized linear models are likely to be sufficient for most analyses. PMID:22943299
Inferring climate variability from skewed proxy records
NASA Astrophysics Data System (ADS)
Emile-Geay, J.; Tingley, M.
2013-12-01
Many paleoclimate analyses assume a linear relationship between the proxy and the target climate variable, and that both the climate quantity and the errors follow normal distributions. An ever-increasing number of proxy records, however, are better modeled using distributions that are heavy-tailed, skewed, or otherwise non-normal, on account of the proxies reflecting non-normally distributed climate variables, or having non-linear relationships with a normally distributed climate variable. The analysis of such proxies requires a different set of tools, and this work serves as a cautionary tale on the danger of making conclusions about the underlying climate from applications of classic statistical procedures to heavily skewed proxy records. Inspired by runoff proxies, we consider an idealized proxy characterized by a nonlinear, thresholded relationship with climate, and describe three approaches to using such a record to infer past climate: (i) applying standard methods commonly used in the paleoclimate literature, without considering the non-linearities inherent to the proxy record; (ii) applying a power transform prior to using these standard methods; (iii) constructing a Bayesian model to invert the mechanistic relationship between the climate and the proxy. We find that neglecting the skewness in the proxy leads to erroneous conclusions and often exaggerates changes in climate variability between different time intervals. In contrast, an explicit treatment of the skewness, using either power transforms or a Bayesian inversion of the mechanistic model for the proxy, yields significantly better estimates of past climate variations. We apply these insights in two paleoclimate settings: (1) a classical sedimentary record from Laguna Pallcacocha, Ecuador (Moy et al., 2002). Our results agree with the qualitative aspects of previous analyses of this record, but quantitative departures are evident and hold implications for how such records are interpreted, and compared to other proxy records. (2) a multiproxy reconstruction of temperature over the Common Era (Mann et al., 2009), where we find that about one third of the records display significant departures from normality. Accordingly, accounting for skewness in proxy predictors has a notable influence on both reconstructed global mean and spatial patterns of temperature change. Inferring climate variability from skewed proxy records thus requires cares, but can be done with relatively simple tools. References - Mann, M. E., Z. Zhang, S. Rutherford, R. S. Bradley, M. K. Hughes, D. Shindell, C. Ammann, G. Faluvegi, and F. Ni (2009), Global signatures and dynamical origins of the little ice age and medieval climate anomaly, Science, 326(5957), 1256-1260, doi:10.1126/science.1177303. - Moy, C., G. Seltzer, D. Rodbell, and D. Anderson (2002), Variability of El Niño/Southern Oscillation activ- ity at millennial timescales during the Holocene epoch, Nature, 420(6912), 162-165.
Skew quad compensation for SPEAR minibeta optics
Wille, K.
1984-06-01
With the new minibeta insertion for SPEAR the betatron coupling and the perturbations of beam optics caused by the solenoid field of the MARK III detector can't be compensated by the simple coils used so far. Therefore another scheme with four skew quads arranged in two families has been chosen. Even though this scheme doesn't compensate the effect of the solenoid on the beam completely, the residual emittance coupling is much less than 1% which should be sufficient under all running conditions. The major advantage of this concept is its simplicity.
Graf, D.C.; Warpinski, N.R.
1996-08-13
A system is described for single-phase, steady-state permeability measurements of porous rock which utilizes a fluid bridge arrangement analogous to a Wheatstone bridge. The arms of the bridge contain the sample and calibrated flow resistors. 8 figs.
Phylogenetic skew: an index of community diversity.
Chen, Hungyen; Shao, Kwang-Tsao; Kishino, Hirohisa
2015-02-01
The distribution of divergence times between member species of a community reflects the pattern of species composition. In this study, we contrast the species composition of a community against the meta-community, which we define as the species composition of a set of target communities. We regard the collection of species that comprise a community as a sample from the set of member species of the meta-community, and interpret the pattern of the community species composition in terms of the type of species sampled from the meta-community. A newly defined effective species sampling proportion explains the amount of the difference between the divergence time distributions of the community and that of the meta-community, assuming random sampling. We propose a new index of phylogenetic skew (PS), as the ratio of the maximum-likelihood estimate of the effective species sampling proportion to the observed sampling proportion. A PS value of 1 is interpreted as random sampling. If the value is >1, the sampling is suspected to be phylogenetically skewed. If it is <1, systematic thinning of species is likely. Unlike other indices, the PS does not depend on species richness as long as the community has more than a few members of a species. Because it is possible to compare partially observed communities, the index may be effectively used in exploratory analysis to detect candidate communities with unique species compositions from a large number of communities. PMID:25580733
Temperature-Compensated Clock Skew Adjustment
Castillo-Secilla, Jose María; Palomares, Jose Manuel; Olivares, Joaquín
2013-01-01
This work analyzes several drift compensation mechanisms in wireless sensor networks (WSN). Temperature is an environmental factor that greatly affects oscillators shipped in every WSN mote. This behavior creates the need of improving drift compensation mechanisms in synchronization protocols. Using the Flooding Time Synchronization Protocol (FTSP), this work demonstrates that crystal oscillators are affected by temperature variations. Thus, the influence of temperature provokes a low performance of FTSP in changing conditions of temperature. This article proposes an innovative correction factor that minimizes the impact of temperature in the clock skew. By means of this factor, two new mechanisms are proposed in this paper: the Adjusted Temperature (AT) and the Advanced Adjusted Temperature (A2T). These mechanisms have been combined with FTSP to produce AT-FTSP and A2T-FTSP Both have been tested in a network of TelosB motes running TinyOS. Results show that both AT-FTSP and A2T-FTSP improve the average synchronization errors compared to FTSP and other temperature-compensated protocols (Environment-Aware Clock Skew Estimation and Synchronization for WSN (EACS) and Temperature Compensated Time Synchronization (TCTS)). PMID:23966192
Modelling Scalar Skewness in Cloudy Boundary Layers
NASA Astrophysics Data System (ADS)
Mironov, Dmitrii; Machulskaya, Ekaterina; Naumann, Ann Kristin; Seifert, Axel; Mellado, Juan Pedro
2015-04-01
Following the pioneering work of Sommeria and Deardorff (1977), statistical cloud schemes are widely used in numerical weather prediction (NWP) and climate models to parameterize the effect of shallow clouds on turbulent mixing and radiation fluxes. Statistical cloud schemes compute the cloud fraction, the amount of cloud condensate and the effect clouds on the buoyancy flux in a given atmospheric-model grid box. This is done with due regard for the sub-grid scale (SGS) fluctuations of temperature and humidity (and possibly the vertical velocity), thus providing an important coupling between cloudiness and the SGS mixing processes. The shape of the PDF of fluctuating fields is assumed, whereas the PDF moments should be provided to the cloud scheme as an input. For non-precipitation clouds, the mixing schemes are usually formulated in terms of quasi-conservative variable, e.g. the liquid (total) water potential temperature and the total water specific humidity. Then, the cloud schemes are conveniently cast in terms of the linearized saturation deficit, referred to as the "s" variable (Mellor 1977), that accounts for the combined effect of the two scalars. If a simple two-parameter single-Gaussian PDF is used, the only "turbulence" parameter to be provided to the cloud scheme is the variance of s. The single-Gaussian PDF ignores the skewed nature of SGS motions and fails to describe many important regimes, e.g. shallow cumuli. A number of more flexible skewed PDFs have been proposed to date. A three-parameter PDF, based on a double-Gaussian distribution and diagnostic relations between some PDF parameters derived from LES and observational data (Naumann et al. 2013), appears to be a good compromise between physical realism and computational economy. A crucial point is that the cloud schemes using non-Gaussian PDFs require the scalar skewness as an input. Using rather mild non-restrictive assumptions, we develop a transport equation for the s-variable triple correlation. That equation contains three terms that require closure. A simple relaxation approximation in terms of the turbulence time (length) scale is used for the dissipation term. The third-order and the fourth-order scalar-velocity correlations are parameterized using an advanced advection-diffusion formulation and a generalized Millionschikov hypothesis (Mironov et al. 1999, Gryanik et al. 2005). These formulations satisfy both the Gaussian limit and, importantly, the limit of strong skewness. The equation for the s triple correlation is coupled to the turbulence kinetic energy (TKE) - scalar variance mixing scheme (Machulskaya and Mironov 2013), where not only the TKE but also the scalar variances and covariance are computed from the prognostic transport equations with due regard for the third-order transport. The coupled scheme is tested through single-column numerical experiments. Results compare favourably with large-eddy simulation data from well-documented shallow cloud cases. Some details of the implementation of the s-skewness formulation into NWP models are discussed.
Skew quadrupole errors in the RHIC IR triplets
Tepikian, S.; Peggs, S.
1993-12-31
From simulation studies of the RHIC lattice, we found that skew quadrupole errors and quadrupole roll misalignments in the IR triplets (where the {beta} function can be large) produce large vertical dispersions. A simple model, using only one triplet, is applied to obtain sensitivities of vertical dispersion to skew quadrupole errors. This study revealed that measuring the vertical dispersion in the triplets is a good tool for the diagnosis of local skew quadrupole correction.
Skew-gradient representation of generalized Birkhoffian system
NASA Astrophysics Data System (ADS)
Mei, Feng-Xiang; Wu, Hui-Bin
2015-10-01
The skew-gradient representation of a generalized Birkhoffian system is studied. A condition under which the generalized Birkhoffian system can be considered as a skew-gradient system is obtained. The properties of the skew-gradient system are used to study the properties, especially the stability, of the generalized Birkhoffian system. Some examples are given to illustrate the application of the result. Project supported by the National Natural Science Foundation of China (Grant No. 11272050).
Cracked shells under skew-symmetric loading
NASA Technical Reports Server (NTRS)
Lelale, F.
1982-01-01
A shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and antiplane elasticity solutions. Extensive results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform inplane shearing, out of plane shearing, and torsion. The effect of orthotropy on the results is also studied.
Analysis of carbon dioxide concentration skewness at a rural site.
Pérez, Isidro A; Sánchez, M Luisa; García, M Ángeles; Ozores, Marta; Pardo, Nuria
2014-04-01
This paper provides evidence that symmetry of CO2 concentration distribution may indicate sources or dispersive processes. Skewness was calculated by different procedures with CO2 measured at a rural site using a Picarro G1301 analyser over a two-year period. The usual skewness coefficient was considered together with fourteen robust estimators. A noticeable contrast was obtained between day and night, and skewness decreased linearly with the logarithm of the height. One coefficient was selected from its satisfactory relationship with the median concentration in daily evolution. Three analyses based on the kernel smoothing method were conducted with this coefficient to investigate its response to yearly and daily evolutions, wind direction, and wind speed. Left-skewed distributions were linked to thermal turbulence during midday, especially in spring-summer, or with high wind speeds. Almost symmetric distributions were associated with sources, such as the Valladolid City plume reinforced with spring emissions and the lack of emissions in summer in the remaining directions. Finally, right-skewed distributions were related to low wind speeds and stable stratification at night, furthered by strong emissions in spring. Skewness intervals were proposed and their average median concentrations were calculated such that the relationship between skewness and concentration depends on the analysis performed. Since some skewness coefficients may also be negative, they provide better information about sources or dispersive processes than concentration. PMID:24463252
Learning a Novel Pattern through Balanced and Skewed Input
ERIC Educational Resources Information Center
McDonough, Kim; Trofimovich, Pavel
2013-01-01
This study compared the effectiveness of balanced and skewed input at facilitating the acquisition of the transitive construction in Esperanto, characterized by the accusative suffix "-n" and variable word order (SVO, OVS). Thai university students (N = 98) listened to 24 sentences under skewed (one noun with high token frequency) or…
Mean, Median, and Skew: Correcting a Textbook Rule
ERIC Educational Resources Information Center
von Hippel, Paul T.
2005-01-01
Many textbooks teach a rule of thumb stating that the mean is right of the median under right skew, and left of the median under left skew. This rule fails with surprising frequency. It can fail in multimodal distributions, or in distributions where one tail is long but the other is heavy. Most commonly, though, the rule fails in discrete…
Learning a Novel Pattern through Balanced and Skewed Input
ERIC Educational Resources Information Center
McDonough, Kim; Trofimovich, Pavel
2013-01-01
This study compared the effectiveness of balanced and skewed input at facilitating the acquisition of the transitive construction in Esperanto, characterized by the accusative suffix "-n" and variable word order (SVO, OVS). Thai university students (N = 98) listened to 24 sentences under skewed (one noun with high token frequency) orâ€¦
ERIC Educational Resources Information Center
Tabor, Josh
2010-01-01
On the 2009 AP[c] Statistics Exam, students were asked to create a statistic to measure skewness in a distribution. This paper explores several of the most popular student responses and evaluates which statistic performs best when sampling from various skewed populations. (Contains 8 figures, 3 tables, and 4 footnotes.)
NASA Technical Reports Server (NTRS)
1977-01-01
Safer bridges are among a number of spinoff benefits from NASA procedures for testing 'cfracture toughness" of a structural part, meaning its ability to -siscracktsh at might cause failure. The New River Bridge in West Virginia, shown under construction, is the world's largest single span bridge. U.S. Steel fracture toughness requirements for such bridges include NASA-developed test procedures. Bridge materials and other metal structures may develop flaws during their service lifetimes. Such flaws can affect the structural integrity of the part. Thus, it is important to know the "fracture toughness" of a structural part, or its ability to resist cracks. NASA has long experience in developing fracture toughness tests for aerospace hardware. Since 1960, NASA-Lewis has worked closely with the American Society for Testing & Materials. Lewis and NASA-funded industrial contractors have made many important contributions to test procedures, now recommended by ASTM, for measuring fracture toughness.
Female reproductive synchrony predicts skewed paternity across primates
Nunn, Charles L.; Schülke, Oliver
2008-01-01
Recent studies have uncovered remarkable variation in paternity within primate groups. To date, however, we lack a general understanding of the factors that drive variation in paternity skew among primate groups and across species. Our study focused on hypotheses from reproductive skew theory involving limited control and the use of paternity “concessions” by investigating how paternity covaries with the number of males, female estrous synchrony, and rates of extragroup paternity. In multivariate and phylogenetically controlled analyses of data from 27 studies on 19 species, we found strong support for a limited control skew model, with reproductive skew within groups declining as female reproductive synchrony and the number of males per group increase. Of these 2 variables, female reproductive synchrony explained more of the variation in paternity distributions. To test whether dominant males provide incentives to subordinates to resist matings by extragroup males, that is, whether dominants make concessions of paternity, we derived a novel prediction that skew is lower within groups when threat from outside the group exists. This prediction was not supported as a primary factor underlying patterns of reproductive skew among primate species. However, our approach revealed that if concessions occur in primates, they are most likely when female synchrony is low, as these conditions provide alpha male control of paternity that is assumed by concessions models. Collectively, our analyses demonstrate that aspects of male reproductive competition are the primary drivers of reproductive skew in primates. PMID:19018288
Multiple linear regression estimators with skew normal errors
NASA Astrophysics Data System (ADS)
Alhamide, A. A.; Ibrahim, K.; Alodat, M. T.
2015-09-01
The idea of skew normal distribution is suitable to be used for the analysis of data which is skewed. The purpose of this paper is to study the estimation of the regression parameters under the extended multivariate skew normal errors. The estimators for the regression parameters found based on the maximum likelihood method are derived. A simulation study is carried out to investigate the performance of the estimators derived and the standard errors associate with the respective parameters estimates are found to be quite small.
Numerical simulation of the Langevin equation for skewed turbulence
Ermak, D. L.; Nasstrom, J. S.
1994-12-01
In this paper the authors present a numerical method for the generalized Langevin equation of motion with skewed random forcing for the case of homogeneous, skewed turbulence. The authors begin by showing how the analytic solution to the Langevin equation for this case can be used to determine the relationship between the particle velocity moments and the properties of the skewed random force. They then present a numerical method that uses simple probability distribution functions to simulate the effect of the random force. The numerical solution is shown to be exact in the limit of infinitesimal time steps, and to be within acceptable error limits when practical time steps are used.
The Affective Impact of Financial Skewness on Neural Activity and Choice
Wu, Charlene C.; Bossaerts, Peter; Knutson, Brian
2011-01-01
Few finance theories consider the influence of “skewness” (or large and asymmetric but unlikely outcomes) on financial choice. We investigated the impact of skewed gambles on subjects' neural activity, self-reported affective responses, and subsequent preferences using functional magnetic resonance imaging (FMRI). Neurally, skewed gambles elicited more anterior insula activation than symmetric gambles equated for expected value and variance, and positively skewed gambles also specifically elicited more nucleus accumbens (NAcc) activation than negatively skewed gambles. Affectively, positively skewed gambles elicited more positive arousal and negatively skewed gambles elicited more negative arousal than symmetric gambles equated for expected value and variance. Subjects also preferred positively skewed gambles more, but negatively skewed gambles less than symmetric gambles of equal expected value. Individual differences in both NAcc activity and positive arousal predicted preferences for positively skewed gambles. These findings support an anticipatory affect account in which statistical properties of gambles—including skewness—can influence neural activity, affective responses, and ultimately, choice. PMID:21347239
PRINCIPLE OF SKEW QUADRUPOLE MODULATION TO MEASURE BETATRON COUPLING.
LUO.Y.PILAT,F.ROSER,T.ET AL.
2004-07-05
The measurement of the residual betatron coupling via skew quadrupole modulation is a new diagnostics technique that has been developed and tested at the Relativistic Heavy Ion Collider (RHIC) as a very promising method for the linear decoupling on the ramp. By modulating the strengths of different skew quadrupole families the two eigentunes are precisely measured with the phase lock loop system. The projections of the residual coupling coefficient onto the skew quadrupole coupling modulation directions are determined. The residual linear coupling could be corrected according to the measurement. An analytical solution for skew quadrupole modulation based on Hamiltonian perturbation approximation is given, and simulation code using smooth accelerator model is also developed. Some issues concerning the practical applications of this technique are discussed.
Bicriterion seriation methods for skew-symmetric matrices.
Brusco, Michael J; Stahl, Stephanie
2005-11-01
The decomposition of an asymmetric proximity matrix into its symmetric and skew-symmetric components is a well-known principle in combinatorial data analysis. The seriation of the skew-symmetric component can emphasize information corresponding to the sign or absolute magnitude of the matrix elements, and the choice of objective criterion can have a profound impact on the ordering. In this research note, we propose a bicriterion approach for seriation of a skew-symmetric matrix incorporating both sign and magnitude information. Two numerical demonstrations reveal that the bicriterion procedure is an effective alternative to direct seriation of the skew-symmetric matrix, facilitating favourable trade-offs among sign and magnitude information. PMID:16293204
Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices
ERIC Educational Resources Information Center
Glaister, P.
2008-01-01
The solution of a system of linear, inhomogeneous differential equations is discussed. The particular class considered is where the coefficient matrix is skew-symmetric and orthogonal, and where the forcing terms are sinusoidal. More general matrices are also considered.
NASA Technical Reports Server (NTRS)
1996-01-01
Crystal Growth in magnetic fields, a float-zone sample, the surface tension of the melt keeps the sample suspended between the sample rods in the furnace forming an actual liquid bridge. Principal Investigator: Dr. Frank Szofran
... practical approach . Blood . 2011 ; 117 : 5044 â€“ 5049 . FREE Full Text Spyropoulos AC . Bridging therapy and oral anticoagulation: current ... doi: 10.1161/CIRCULATIONAHA.111.084517 Extract Free Â» Full Text Free PDF Free Classifications Cardiology Patient Page Services ...
Skewed exponential pairwise velocities from Gaussian initial conditions
Juszkiewicz, R.; Fisher, K. B.; Szapudi, I.
1998-09-01
Using an Eulerian perturbative calculation, we show that the distribution of relative pairwise velocities which arises from gravitational instability of Gaussian density fluctuations has asymmetric (skewed) exponential tails. The negative skewness is induced by the negative mean streaming velocity of pairs (the infall prevails over expansion), while the exponential tails arise because the relative pairwise velocity is a number, not volume weighted statistic. The derived probability distribution is compared with N-body simulations and shown to provide a reasonable fit.
Vibration of skewed cantilever plates and helicoidal shells
NASA Technical Reports Server (NTRS)
Beres, D. P.; Bailey, C. D.
1975-01-01
Theoretical vibration frequencies and mode shapes are obtained for skewed plates and helicoidal shells with a cantilever boundary. Using Hamilton's law of varying action, a power series solution is developed to obtain converged numerical results for the five lowest frequencies. Effects of geometrical variables such as aspect ratio, sweep angle and shell radius to thickness ratio are investigated. Accuracy of the solution method is substantiated by comparison with existing skewed plate spherical cap, and conical shell results.
Extension of EMA to address regional skew and low outliers
Griffis, V.W.; Stedinger, J.R.; Cohn, T.A.
2003-01-01
The recently developed expected moments algorithm [EMA] (Cohn et al. 1997) does as well as MLEs at estimating LP3 flood quantiles using systematic and historical information. Needed extensions include use of a regional skewness estimator and its precision to be consistent with Bulletin 17B and to make use of such hydrologic information. Another issue addressed by Bulletin 17B is the treatment of low outliers. A Monte Carlo study illustrates the performance of an extended EMA estimator compared to estimators that employ the complete data set with and without use of regional skew, conditional probability adjustment from Bulletin 17B, and an estimator that uses probability plot regression to compute substitute values for low outliers. Estimators that use a regional skew all do better than estimators that fail to use an informative regional skewness estimator. For LP3 data, the low outlier rejection procedure results in no loss of overall accuracy, and the differences between the MSEs of the estimators that used an informative regional skew were generally negligible in the skew range of real interest.
Flow in Rotating Serpentine Coolant Passages With Skewed Trip Strips
NASA Technical Reports Server (NTRS)
Tse, David G.N.; Steuber, Gary
1996-01-01
Laser velocimetry was utilized to map the velocity field in serpentine turbine blade cooling passages with skewed trip strips. The measurements were obtained at Reynolds and Rotation numbers of 25,000 and 0.24 to assess the influence of trips, passage curvature and Coriolis force on the flow field. The interaction of the secondary flows induced by skewed trips with the passage rotation produces a swirling vortex and a corner recirculation zone. With trips skewed at +45 deg, the secondary flows remain unaltered as the cross-flow proceeds from the passage to the turn. However, the flow characteristics at these locations differ when trips are skewed at -45 deg. Changes in the flow structure are expected to augment heat transfer, in agreement with the heat transfer measurements of Johnson, et al. The present results show that trips are skewed at -45 deg in the outward flow passage and trips are skewed at +45 deg in the inward flow passage maximize heat transfer. Details of the present measurements were related to the heat transfer measurements of Johnson, et al. to relate fluid flow and heat transfer measurements.
RÃ©nyi entropy and complexity measure for skew-gaussian distributions and related families
NASA Astrophysics Data System (ADS)
Contreras-Reyes, Javier E.
2015-09-01
In this paper, we provide the RÃ©nyi entropy and complexity measure for a novel, flexible class of skew-gaussian distributions and their related families, as a characteristic form of the skew-gaussian Shannon entropy. We give closed expressions considering a more general class of closed skew-gaussian distributions and the weighted moments estimation method. In addition, closed expressions of RÃ©nyi entropy are presented for extended skew-gaussian and truncated skew-gaussian distributions. Finally, additional inequalities for skew-gaussian and extended skew-gaussian RÃ©nyi and Shannon entropies are reported.
Sample Skewness as a Statistical Measurement of Neuronal Tuning Sharpness
Samonds, Jason M.; Potetz, Brian R.; Lee, Tai Sing
2014-01-01
We propose using the statistical measurement of the sample skewness of the distribution of mean firing rates of a tuning curve to quantify sharpness of tuning. For some features, like binocular disparity, tuning curves are best described by relatively complex and sometimes diverse functions, making it difficult to quantify sharpness with a single function and parameter. Skewness provides a robust nonparametric measure of tuning curve sharpness that is invariant with respect to the mean and variance of the tuning curve and is straightforward to apply to a wide range of tuning, including simple orientation tuning curves and complex object tuning curves that often cannot even be described parametrically. Because skewness does not depend on a specific model or function of tuning, it is especially appealing to cases of sharpening where recurrent interactions among neurons produce sharper tuning curves that deviate in a complex manner from the feedforward function of tuning. Since tuning curves for all neurons are not typically well described by a single parametric function, this model independence additionally allows skewness to be applied to all recorded neurons, maximizing the statistical power of a set of data. We also compare skewness with other nonparametric measures of tuning curve sharpness and selectivity. Compared to these other nonparametric measures tested, skewness is best used for capturing the sharpness of multimodal tuning curves defined by narrow peaks (maximum) and broad valleys (minima). Finally, we provide a more formal definition of sharpness using a shape-based information gain measure and derive and show that skewness is correlated with this definition. PMID:24555451
Sample skewness as a statistical measurement of neuronal tuning sharpness.
Samonds, Jason M; Potetz, Brian R; Lee, Tai Sing
2014-05-01
We propose using the statistical measurement of the sample skewness of the distribution of mean firing rates of a tuning curve to quantify sharpness of tuning. For some features, like binocular disparity, tuning curves are best described by relatively complex and sometimes diverse functions, making it difficult to quantify sharpness with a single function and parameter. Skewness provides a robust nonparametric measure of tuning curve sharpness that is invariant with respect to the mean and variance of the tuning curve and is straightforward to apply to a wide range of tuning, including simple orientation tuning curves and complex object tuning curves that often cannot even be described parametrically. Because skewness does not depend on a specific model or function of tuning, it is especially appealing to cases of sharpening where recurrent interactions among neurons produce sharper tuning curves that deviate in a complex manner from the feedforward function of tuning. Since tuning curves for all neurons are not typically well described by a single parametric function, this model independence additionally allows skewness to be applied to all recorded neurons, maximizing the statistical power of a set of data. We also compare skewness with other nonparametric measures of tuning curve sharpness and selectivity. Compared to these other nonparametric measures tested, skewness is best used for capturing the sharpness of multimodal tuning curves defined by narrow peaks (maximum) and broad valleys (minima). Finally, we provide a more formal definition of sharpness using a shape-based information gain measure and derive and show that skewness is correlated with this definition. PMID:24555451
ERIC Educational Resources Information Center
Strunck, Ted
1995-01-01
A teacher at Upland Hills School (Royal Oaks, Michigan) describes how he and groups of seventh and eighth graders built a 175-foot bridge across a gully between the school and an outdoor environmental education area. Students received basic design and engineering instruction at a nearby university, and parents and community provided support and…
ERIC Educational Resources Information Center
Silver, Michael, Ed.; Zito, Michael, Ed.
2002-01-01
This document is comprised of the one issue in volume 7 of "Bridges," a publication produced by the California Head Start-State Collaboration Office to detail the activities of the educational partnership and to provide relevant information to programs participating in the partnership. The Summer 2002 issue focuses on several topics of interest to…
NASA Technical Reports Server (NTRS)
1995-01-01
I-Bridge is a commercial version of software developed by I-Kinetics under a NASA Small Business Innovation Research (SBIR) contract. The software allows users of Windows applications to gain quick, easy access to databases, programs and files on UNIX services. Information goes directly onto spreadsheets and other applications; users need not manually locate, transfer and convert data.
OPERATIONAL MEASUREMENT OF COUPLING BY SKEW QUADRUPOLE MODULATION.
LUO.Y.CAMERON,P.LEE,R.ET AL.
2004-07-05
The measurement and correction of the residual betatron coupling via skew quadrupole modulation is a new diagnostics technique that has been developed and tested at the Relativistic Heavy Ion Collider (RHIC) as a very promising method for the linear decoupling on the ramp. By modulating the strengths of the skew quadrupole families the two eigentune modulations are precisely measured with a high resolution phase lock loop system. The projections of the residual coupling coefficient onto the skew quadrupole coupling modulation direction are determined. The residual linear coupling could be corrected according the measurement. We report the results from the dedicated beam studies carried on at RHIC injection, store and on the ramp. A capability of measuring coupling on the ramp opens possibility of continuous coupling corrections during acceleration.
Determining collective barrier operation skew in a parallel computer
Faraj, Daniel A.
2015-12-24
Determining collective barrier operation skew in a parallel computer that includes a number of compute nodes organized into an operational group includes: for each of the nodes until each node has been selected as a delayed node: selecting one of the nodes as a delayed node; entering, by each node other than the delayed node, a collective barrier operation; entering, after a delay by the delayed node, the collective barrier operation; receiving an exit signal from a root of the collective barrier operation; and measuring, for the delayed node, a barrier completion time. The barrier operation skew is calculated by: identifying, from the compute nodes' barrier completion times, a maximum barrier completion time and a minimum barrier completion time and calculating the barrier operation skew as the difference of the maximum and the minimum barrier completion time.
Determining collective barrier operation skew in a parallel computer
Faraj, Daniel A.
2015-11-24
Determining collective barrier operation skew in a parallel computer that includes a number of compute nodes organized into an operational group includes: for each of the nodes until each node has been selected as a delayed node: selecting one of the nodes as a delayed node; entering, by each node other than the delayed node, a collective barrier operation; entering, after a delay by the delayed node, the collective barrier operation; receiving an exit signal from a root of the collective barrier operation; and measuring, for the delayed node, a barrier completion time. The barrier operation skew is calculated by: identifying, from the compute nodes' barrier completion times, a maximum barrier completion time and a minimum barrier completion time and calculating the barrier operation skew as the difference of the maximum and the minimum barrier completion time.
Bridged graphite oxide materials
NASA Technical Reports Server (NTRS)
Herrera-Alonso, Margarita (Inventor); McAllister, Michael J. (Inventor); Aksay, Ilhan A. (Inventor); Prud'homme, Robert K. (Inventor)
2010-01-01
Bridged graphite oxide material comprising graphite sheets bridged by at least one diamine bridging group. The bridged graphite oxide material may be incorporated in polymer composites or used in adsorption media.
A Longitudinal Twin Study of Skewed X Chromosome-Inactivation
Wong, Chloe Chung Yi; Caspi, Avshalom; Williams, Benjamin; Houts, Renate; Craig, Ian W.; Mill, Jonathan
2011-01-01
X-chromosome inactivation (XCI) is a pivotal epigenetic mechanism involved in the dosage compensation of X-linked genes between males and females. In any given cell, the process of XCI in early female development is thought to be random across alleles and clonally maintained once established. Recent studies, however, suggest that XCI might not always be random and that skewed inactivation may become more prevalent with age. The factors influencing such XCI skewing and its changes over time are largely unknown. To elucidate the influence of stochastic, heritable and environmental factors in longitudinal changes in XCI, we examined X inactivation profiles in a sample of monozygotic (MZ) (n?=?23) and dizygotic (DZ) (n?=?22) female twin-pairs at ages 5 and 10 years. Compared to MZ twins who were highly concordant for allelic XCI ratios, DZ twins showed much lower levels of concordance. Whilst XCI patterns were moderately stable between ages 5 and 10 years, there was some drift over time with an increased prevalence of more extreme XCI skewing at age 10. To our knowledge, this study represents the earliest longitudinal assessment of skewed XCI patterns, and suggests that skewed XCI may already be established in early childhood. Our data also suggest a link between MZ twinning and the establishment of allelic XCI ratios, and demonstrate that acquired skewing in XCI after establishment is primarily mediated by stochastic mechanisms. These data have implications for our understanding about sex differences in complex disease, and the potential causes of phenotypic discordance between MZ female twins. PMID:21445353
Power and Skew Aware Point Diffusion Clock Network
NASA Astrophysics Data System (ADS)
Jung, Gunok; Kim, Chunghee; Chae, Kyoungkuk; Park, Giho; Park, Sung Bae
This letter presents point diffusion clock network (PDCN) with local clock tree synthesis (CTS) scheme. The clock network is implemented with ten times wider metal line space than typical mesh networks for low power and utilized to nine times smaller area CTS execution for minimized clock skew amount. The measurement results show that skew amount of PDCN with local CTS is reduced to 36% and latency is shrunk to 45% of the amount in a 4.81mm2 CortexA-8 core with 65nm Samsung process.
Skew flap for staged below-knee amputation in sepsis.
Matthews, Christopher O; Williams, Ian M; Lewis, Peter; McLain, A David; Twine, Christopher P
2016-04-01
Skew flap amputation was first described in the 1980s but was never as popular as the long posterior flap amputation. This report describes a staged below-knee amputation in sepsis, with pus throughout the leg and a lack of skin coverage. One benefit of skew flaps never previously published is the fact that the suture line is not directly over the tibia. Therefore, an open wound or incomplete skin coverage is not as important as in long posterior flaps where it often leads to bone exposure and revision amputation. These benefits were utilized in this case leading to stump healing. PMID:26002782
ERIC Educational Resources Information Center
Murfin, Brian
2000-01-01
Describes the famous swing bridge in Belize. Students build bridges from a variety of materials and answer the questions, What are different types of bridges?, How do bridges work?, How can you tell if a bridge design will be safe?, and What is the best way to build a bridge over a river while still allowing boat traffic? (SAH)
Bridge Inspector's Training Manual.
ERIC Educational Resources Information Center
Federal Highway Administration (DOT), Washington, DC. Bureau of Public Roads.
A guide for the instruction of bridge inspectors is provided in this manual as well as instructions for conducting and reporting on a bridge inspection. The chapters outline the qualifications necessary to become a bridge inspector. The subject areas covered are: The Bridge Inspector, Bridge Structures, Bridge Inspection Reporting System,â€¦
Critique of the Article, "How Skewed Is 'The Bell Curve'?"
ERIC Educational Resources Information Center
Richard, Harriette W.; Washington, Michael
1995-01-01
Argues that the philosophical context noted in Haynes's "How Skewed Is 'The Bell Curve,'" is incomplete; that the Constitution does not treat blacks the same as whites; and that not enough cultural and social context was addressed. The authors characterize the "The Bell Curve" as a wrecking ball for dismantling social programs and policies…
Sum uncertainty relations based on Wigner-Yanase skew information
NASA Astrophysics Data System (ADS)
Chen, Bin; Fei, Shao-Ming; Long, Gui-Lu
2016-03-01
We study sum uncertainty relations for arbitrary finite N quantum mechanical observables. Some uncertainty inequalities are presented by using skew information introduced by Wigner and Yanase. These uncertainty inequalities are nontrivial as long as the observables are mutually noncommutative. The relations among these new and existing uncertainty inequalities have been investigated. Detailed examples are presented.
Electronic skewing circuit monitors exact position of object underwater
NASA Technical Reports Server (NTRS)
Roller, R.; Yaroshuk, N.
1967-01-01
Linear Variable Differential Transformer /LVDT/ electronic skewing circuit guides a long cylindrical capsule underwater into a larger tube so that it does not contact the tube wall. This device detects movement of the capsule from a reference point and provides a continuous signal that is monitored on an oscilloscope.
An Analytical Approach to Generating Norms for Skewed Normative Distributions.
ERIC Educational Resources Information Center
Wang, Jing-Jen
Approaches for norming skewed test score distributions are reviewed, and an analytical approach is proposed for norming the Behavior Assessment System for Children (BASC). Methods used in constructing norms for several well-known personality instruments that are reviewed include: (1) linear T-scores transformation in the Minnesota Multiphasic…
Root waving and skewing: unexpectedly in micro-g.
Roux, Stanley J
2012-01-01
Gravity has major effects on both the form and overall length of root growth. Numerous papers have documented these effects (over 300 publications in the last 5 years), the most well-studied being gravitropism, which is a growth re-orientation directed by gravity toward the earth's center. Less studied effects of gravity are undulations due to the regular periodic change in the direction root tips grow, called waving, and the slanted angle of growth roots exhibit when they are growing along a nearly-vertical surface, called skewing. Although diverse studies have led to the conclusion that a gravity stimulus is needed for plant roots to show waving and skewing, the novel results just published by Paul et al. (2012) reveal that this conclusion is not correct. In studies carried out in microgravity on the International Space Station, the authors used a new imaging system to collect digital photographs of plants every six hours during 15 days of spaceflight. The imaging system allowed them to observe how roots grew when their orientation was directed not by gravity but by overhead LED lights, which roots grew away from because they are negatively phototropic. Surprisingly, the authors observed both skewing and waving in spaceflight plants, thus demonstrating that both growth phenomena were gravity independent. Touch responses and differential auxin transport would be common features of root waving and skewing at 1-g and micro-g, and the novel results of Paul et al. will focus the attention of cell and molecular biologists more on these features as they try to decipher the signaling pathways that regulate root skewing and waving. PMID:23217095
Development of a baseline model for a steel girder bridge using remote sensing and load tests
NASA Astrophysics Data System (ADS)
Dai, Kaoshan; Chen, Shen-En; Scott, Jeremy; Schmieder, Marcus; Liu, Wanqiu; Hauser, Edd
2011-04-01
A new skewed two span continuous steel girder bridge was constructed and opened to traffic recently. This bridge uses high performance steel (HPS 100W) in the flanges of the negative moment region over the intermediate pier. For construction verification and long-term structural health monitoring purposes, a finite element (FE) model was developed for the bridge superstructure. Various field tests were performed to verify the model: 1) LiDAR scan, 2) static truck load tests, and 3) Laser doppler vibrometer testing. LiDAR scanner was introduced to gain geometrical information of the bridge in the real world. It was also used to measure girder deflections during load tests. The fundamental frequency of the bridge vibration was obtained by using a Laser doppler vibrometer. Both dynamic and static measurements are then used to update the FE model. This valid bridge superstructure FE model was provided to local DOT bridge engineers with the completion of this study.
Arc voltage distribution skewness as an indicator of electrode gap during vacuum arc remelting
Williamson, R.L.; Zanner, F.J.; Grose, S.M.
1998-01-13
The electrode gap of a VAR is monitored by determining the skewness of a distribution of gap voltage measurements. A decrease in skewness indicates an increase in gap and may be used to control the gap. 4 figs.
Arc voltage distribution skewness as an indicator of electrode gap during vacuum arc remelting
Williamson, Rodney L. (Albuquerque, NM); Zanner, Frank J. (Sandia Park, NM); Grose, Stephen M. (Glenwood, WV)
1998-01-01
The electrode gap of a VAR is monitored by determining the skewness of a distribution of gap voltage measurements. A decrease in skewness indicates an increase in gap and may be used to control the gap.
Correcting Quadrupole Roll in Magnetic Lenses with Skew Quadrupoles
Walstrom, Peter Lowell
2014-11-10
Quadrupole rolls (i.e. rotation around the magnet axis) are known to be a significant source of image blurring in magnetic quadrupole lenses. These rolls may be caused by errors in mechanical mounting of quadrupoles, by uneven radiation-induced demagnetization of permanent-magnet quadrupoles, etc. Here a four-quadrupole Ã—10 lens with so-called â€Russianâ€ or A -B B-A symmetry is used as a model problem. Existing SLAC 1/2 in. bore high-gradient quadrupoles are used in the design. The dominant quadrupole roll effect is changes in the first-order part of the transfer map (the R matrix) from the object to the image plane (Note effects on the R matrix can be of first order in rotation angle for some R-matrix elements and second order in rotation angle for other elements, as shown below). It is possible to correct roll-induced image blur by mechanically adjusting the roll angle of one or more of the quadrupoles. Usually, rotation of one quadrupole is sufficient to correct most of the combined effect of rolls in all four quadrupoles. There are drawbacks to this approach, however, since mechanical roll correction requires multiple entries into experimental area to make the adjustments, which are made according to their effect on images. An alternative is to use a single electromagnetic skew quadrupole corrector placed either between two of the quadrupoles or after the fourth quadrupole (so-called â€œnon-localâ€ correction). The basic feasibility of skew quadrupole correction of quadrupole roll effects is demonstrated here. Rolls of the third lens quadrupole of up to about 1 milliradian can be corrected with a 15 cm long skew quadrupole with a gradient of up to 1 T/m. Since the effect of rolls of the remaining three lens quadrupoles are lower, a weaker skew quadrupole can be used to correct them. Non-local correction of quadrupole roll effects by skew quadrupoles is shown to be about one-half as effective as local correction (i.e. rotating individual quadrupoles to zero roll angle or placing skew quadrupole correctors in the bores of main quadrupoles).
Ivanoff, Michael A.; Weber, Matthew A.
1996-01-01
The Town Highway 29 crossing of Locust Creek is a 37-ft-long, one-lane bridge consisting of one 32-foot concrete span (Vermont Agency of Transportation, written communication, August 23, 1994). The bridge is supported by vertical, concrete abutments with wingwalls. The channel is skewed approximately 25 degrees to the opening while the opening-skew-to-roadway is 25 degrees. There was no observable scour protection measure at the site. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E.
Skewed brownian fluctuations in single-molecule magnetic tweezers.
Burnham, Daniel R; De Vlaminck, Iwijn; Henighan, Thomas; Dekker, Cees
2014-01-01
Measurements in magnetic tweezers rely upon precise determination of the position of a magnetic microsphere. Fluctuations in the position due to Brownian motion allows calculation of the applied force, enabling deduction of the force-extension response function for a single DNA molecule that is attached to the microsphere. The standard approach relies upon using the mean of position fluctuations, which is valid when the microsphere axial position fluctuations obey a normal distribution. However, here we demonstrate that nearby surfaces and the non-linear elasticity of DNA can skew the distribution. Through experiment and simulations, we show that such a skewing leads to inaccurate position measurements which significantly affect the extracted DNA extension and mechanical properties, leading to up to two-fold errors in measured DNA persistence length. We develop a simple, robust and easily implemented method to correct for such mismeasurements. PMID:25265383
Skewed Brownian Fluctuations in Single-Molecule Magnetic Tweezers
Burnham, Daniel R.; De Vlaminck, Iwijn; Henighan, Thomas; Dekker, Cees
2014-01-01
Measurements in magnetic tweezers rely upon precise determination of the position of a magnetic microsphere. Fluctuations in the position due to Brownian motion allows calculation of the applied force, enabling deduction of the force-extension response function for a single DNA molecule that is attached to the microsphere. The standard approach relies upon using the mean of position fluctuations, which is valid when the microsphere axial position fluctuations obey a normal distribution. However, here we demonstrate that nearby surfaces and the non-linear elasticity of DNA can skew the distribution. Through experiment and simulations, we show that such a skewing leads to inaccurate position measurements which significantly affect the extracted DNA extension and mechanical properties, leading to up to two-fold errors in measured DNA persistence length. We develop a simple, robust and easily implemented method to correct for such mismeasurements. PMID:25265383
Universal relation between skewness and kurtosis in complex dynamics.
Cristelli, Matthieu; Zaccaria, Andrea; Pietronero, Luciano
2012-06-01
We identify an important correlation between skewness and kurtosis for a broad class of complex dynamic systems and present a specific analysis of earthquake and financial time series. Two regimes of non-Gaussianity can be identified: a parabolic one, which is common in various fields of physics, and a power law one, with exponent 4/3, which at the moment appears to be specific of earthquakes and financial markets. For this property we propose a model and an interpretation in terms of very rare events dominating the statistics independently on the nature of the events considered. The predicted scaling relation between skewness and kurtosis matches very well the experimental pattern of the second regime. Regarding price fluctuations, this situation characterizes a universal stylized fact. PMID:23005163
Universal relation between skewness and kurtosis in complex dynamics
NASA Astrophysics Data System (ADS)
Cristelli, Matthieu; Zaccaria, Andrea; Pietronero, Luciano
2012-06-01
We identify an important correlation between skewness and kurtosis for a broad class of complex dynamic systems and present a specific analysis of earthquake and financial time series. Two regimes of non-Gaussianity can be identified: a parabolic one, which is common in various fields of physics, and a power law one, with exponent 4/3, which at the moment appears to be specific of earthquakes and financial markets. For this property we propose a model and an interpretation in terms of very rare events dominating the statistics independently on the nature of the events considered. The predicted scaling relation between skewness and kurtosis matches very well the experimental pattern of the second regime. Regarding price fluctuations, this situation characterizes a universal stylized fact.
Newspaper Coverage of Intimate Partner Violence: Skewing Representations of Risk
Carlyle, Kellie E.; Slater, Michael D.; Chakroff, Jennifer L.
2011-01-01
How media portray intimate partner violence (IPV) has implications for public perceptions and social policy. Therefore, to better understand these portrayals, this study content analyzes a nationally representative sample of newspaper coverage of IPV over a two-year-period and compares this coverage to epidemiological data in order to examine the implications of the discrepancies between coverage and social reality. Stratified media outlets across the country were used to obtain a representative sample of daily newspapers based on their designated market areas, resulting in 395 IPV-related articles. Results show that newspaper framing of IPV tends to be heavily skewed toward episodic framing. In addition, there are significant differences between our data and epidemiological estimates, particularly in the coverage of homicide and use of alcohol and illegal drugs, which may skew public perceptions of risk. Implications for public perceptions and social policy are discussed. PMID:21297889
Mutual impedance of nonplanar-skew sinusoidal dipoles
NASA Technical Reports Server (NTRS)
Richmond, J. H.; Geary, N. H.
1974-01-01
The mutual impedance of nonplanar-skew sinusoidal dipoles is presented as a summation of several exponential integrals with complex arguments. Mathematical models are developed to show the near-zone field of the sinusoidal dipole. The mutual impedance of coupled dipoles is expressed as the sum of four monopole-mobopole impedances to simplify the analysis procedure. The subroutines for solving the parameters of the dipoles are discussed.
Skew and twist resistant hydrodynamic rotary shaft seal
Dietle, Lannie (Sugar Land, TX); Kalsi, Manmohan Singh (Houston, TX)
1999-01-01
A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which and cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland.
Estimating Incremental Costs with Skew: A Cautionary Note
Polgreen, Linnea A.; Brooks, John M.
2016-01-01
Background Cost data in healthcare are often skewed across patients. Thus researchers have used either a log transformation of the dependent variable or generalized linear models (GLMs) with log links. However, frequently these non-linear approaches produce non-linear incremental effects: the incremental effects differ at different levels of the covariates, and this can cause dramatic effects on predicted cost. Objectives To demonstrate that when modeling skewed data, log link functions or log transformations are not necessary and have unintended effects. Methods We simulated cost data using a linear model with a “treatment”, a covariate, and a specified number of observations with excessive cost (skewed data). We also used actual data from a pain-relief intervention among hip-replacement patients. We then estimated cost models using various functional approaches suggested to handle skew and calculated the incremental cost of treatment at various levels of the covariate(s). Results All of these methods provide unbiased estimates of the incremental effect of treatment on costs at the mean level of the covariate. However, in some log-based models the implied incremental treatment cost doubled between extreme low and high values of the covariate in a manner inconsistent with the underlying linear model. Conclusions Although specification checks are always needed, the potential of misleading incremental estimates resulting from log-based specifications is often ignored. In this era of cost containment and comparisons of treatment effectiveness, it is vital that researchers and policy-makers understand the limitation of the inferences that can be made using log-based models for patients whose characteristics differ from the sample mean. PMID:22762544
Incorporating Skew into RMS Surface Roughness Probability Distribution
NASA Technical Reports Server (NTRS)
Stahl, Mark T.; Stahl, H. Philip.
2013-01-01
The standard treatment of RMS surface roughness data is the application of a Gaussian probability distribution. This handling of surface roughness ignores the skew present in the surface and overestimates the most probable RMS of the surface, the mode. Using experimental data we confirm the Gaussian distribution overestimates the mode and application of an asymmetric distribution provides a better fit. Implementing the proposed asymmetric distribution into the optical manufacturing process would reduce the polishing time required to meet surface roughness specifications.
Skew and twist resistant hydrodynamic rotary shaft seal
Dietle, L.; Kalsi, M.S.
1999-02-23
A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland. 14 figs.
A longitudinal analysis of reproductive skew in male rhesus macaques.
Widdig, Anja; Bercovitch, Fred B.; Streich, Wolf Jürgen; Sauermann, Ulrike; Nürnberg, Peter; Krawczak, Michael
2004-01-01
One of the basic tenets of sexual selection is that male reproductive success should be large in polygynous species. Here, we analysed 6 years of molecular genetic data from a semi-free-ranging population of rhesus macaques (Macaca mulatta), using Nonac's B index, to assess the level of male reproductive skew in the study troop. On average, the top sire in each year produced 24% of the infants, while 71% of troop males sired no offspring at all. Consequently, 74% of infants had at least one paternal half-sibling in their own birth cohort. Reproductive success was greatest for high-ranking males, males who spent the whole mating season in the troop and males of 9-11 years of age. Heterozygosity for major histocompatibility complex (MHC) class II gene DQB1 was the strongest single predictor of male reproductive success. A negative relationship suggestive of female mate choice was noted between the B index and the proportion of extragroup paternities. Reproductive skew was not associated with relatedness among potential sires or with female cycle synchrony. We conclude that reproductive skew in male rhesus macaques is best accounted for by the 'limited-control' model, with multiple factors interacting to regulate individual reproductive output. PMID:15255100
Skew-orthogonal polynomials and random-matrix ensembles.
Ghosh, Saugata; Pandey, Akhilesh
2002-04-01
There is considerable interest in understanding the relation between random-matrix ensembles and quantum chaotic systems in the context of the universality of energy-level correlations. In this connection, while Gaussian ensembles of random matrices have been studied extensively, not much is known about ensembles with non-Gaussian weight functions. Dyson has shown that the n-level correlation functions can be expressed in terms of a kernel function involving orthogonal and skew-orthogonal polynomials--orthogonal for matrix ensembles with unitary invariance and skew orthogonal for ensembles with orthogonal and symplectic invariances. We have obtained the following results. (1) Skew-orthogonal polynomials of both types are derived for the Jacobi class of weight functions including the limiting cases of associated Laguerre and Hermite (or Gaussian). (2) Matrix-integral representations are given for the general weight functions. (3) Asymptotic forms of the polynomials are obtained rigorously for the Jacobi class and in the form of an ansatz for the general case. (4) For the three types of ensembles, the (asymptotic) n-level correlation functions with appropriate scaling are shown to be universal, being independent of the weight function and location in the spectrum, and identical with the well-known Gaussian results. This provides a rigorous justification for the universality of the Gaussian ensemble results observed in quantum chaotic systems. As expected, the level density is not universal. PMID:12005990
Kurtosis, skewness, and non-Gaussian cosmological density perturbations
NASA Technical Reports Server (NTRS)
Luo, Xiaochun; Schramm, David N.
1993-01-01
Cosmological topological defects as well as some nonstandard inflation models can give rise to non-Gaussian density perturbations. Skewness and kurtosis are the third and fourth moments that measure the deviation of a distribution from a Gaussian. Measurement of these moments for the cosmological density field and for the microwave background temperature anisotropy can provide a test of the Gaussian nature of the primordial fluctuation spectrum. In the case of the density field, the importance of measuring the kurtosis is stressed since it will be preserved through the weakly nonlinear gravitational evolution epoch. Current constraints on skewness and kurtosis of primeval perturbations are obtained from the observed density contrast on small scales and from recent COBE observations of temperature anisotropies on large scales. It is also shown how, in principle, future microwave anisotropy experiments might be able to reveal the initial skewness and kurtosis. It is shown that present data argue that if the initial spectrum is adiabatic, then it is probably Gaussian, but non-Gaussian isocurvature fluctuations are still allowed, and these are what topological defects provide.
Validation of an Acoustic Impedance Prediction Model for Skewed Resonators
NASA Technical Reports Server (NTRS)
Howerton, Brian M.; Parrott, Tony L.
2009-01-01
An impedance prediction model was validated experimentally to determine the composite impedance of a series of high-aspect ratio slot resonators incorporating channel skew and sharp bends. Such structures are useful for packaging acoustic liners into constrained spaces for turbofan noise control applications. A formulation of the Zwikker-Kosten Transmission Line (ZKTL) model, incorporating the Richards correction for rectangular channels, is used to calculate the composite normalized impedance of a series of six multi-slot resonator arrays with constant channel length. Experimentally, acoustic data was acquired in the NASA Langley Normal Incidence Tube over the frequency range of 500 to 3500 Hz at 120 and 140 dB OASPL. Normalized impedance was reduced using the Two-Microphone Method for the various combinations of channel skew and sharp 90o and 180o bends. Results show that the presence of skew and/or sharp bends does not significantly alter the impedance of a slot resonator as compared to a straight resonator of the same total channel length. ZKTL predicts the impedance of such resonators very well over the frequency range of interest. The model can be used to design arrays of slot resonators that can be packaged into complex geometries heretofore unsuitable for effective acoustic treatment.
Genomic comparisons between paired bacterial strains with strong and weak GC skews.
Song, Tie-Jun; Wang, Yue; Shen, Jian-Gen; Pan, Jian-Ping; Huang, Jun
2014-02-01
A majority of known eubacterial genomes are characteristic of GC skew, i.e., the leading strand has exceeding number of G over C. The cause of this compositional bias is still not very clear. In this study, we chose five pairs of genomes from distantly related bacterial genera, i.e., Buchnera, Haemophilus, Mycoplasma, Mycobacterium, and Synechococcus, each containing one with strong GC skew and the other with weak GC skew. Through comparison of the orthologous genes in these genera, we found that neither chromosomal rearrangement nor CDS skew has direct relationship with GC skew. PMID:23457112
THE TRUSS BRIDGE SEGMENT OF THE TRIBOROUGH BRIDGE IN FOREGROUND ...
THE TRUSS BRIDGE SEGMENT OF THE TRIBOROUGH BRIDGE IN FOREGROUND AND THE HELL GATE BRIDGE IN THE BACKGROUND ADJACENT TO THE SUSPENSION SEGMENT OF THE TRIBOROUGH BRIDGE. - Triborough Bridge, Passing through Queens, Manhattan & the Bronx, Queens (subdivision), Queens County, NY
Numerical and experimental analyses of an integral bridge
NASA Astrophysics Data System (ADS)
Khodair, Yasser; Hassiotis, Sophia
2013-12-01
In this paper, we present the analysis of a numerical and an experimental study of the Scotch Road integral abutment bridge located in Trenton, NJ, USA. Three-dimensional, nonlinear finite element (FE) model of the full bridge has been developed to study the effect of thermal loading on the bridge substructure. The bridge substructure was fully instrumented. Data analysis was performed to study the effect of several design parameters on axial stress in piles. An analysis of the pile-soil system was performed using the finite difference software LPILE. The maximum displacement of the bridge superstructure obtained from the FE model due to a maximum expected temperature change of ±42°C during the lifetime of the bridge was applied to the substructure model. The effect of bridge skew on the build-up of soil pressure behind the abutment was studied. A significant increase in the soil pressures and axial stresses behind the abutment at the obtuse side versus the acute was observed. The effect of the size of the galvanized steel sleeve on the induced axial stresses in piles was studied. We found that increasing the size of the steel sleeve increases their capacity to resist bending.
Skew And Twist Resistant Hydrodynamic Rotary Shaft Seal
Dietle, Lannie (Sugar Land, TX); Kalsi, Manmohan Singh (Houston, TX)
2000-03-14
A hydrodynamically lubricated squeeze packing type rotary shaft seal suitable for lubricant retention and environmental exclusion which incorporates one or more resilient protuberances which and cooperate with the gland walls to hold the seal straight in its installation groove in unpressurized and low pressure lubricant retention applications thereby preventing skew-induced wear caused by impingement of abrasive contaminants present in the environment, and which also serve as radial bearings to prevent tipping of the seal within its installation gland. Compared to prior art, this invention provides a dramatic reduction of seal and shaft wear in abrasive environments and provides a significant increase in seal life.
Generally astigmatic Gaussian beam representation and optimization using skew rays
NASA Astrophysics Data System (ADS)
Colbourne, Paul D.
2014-12-01
Methods are presented of using skew rays to optimize a generally astigmatic optical system to obtain the desired Gaussian beam focus and minimize aberrations, and to calculate the propagating generally astigmatic Gaussian beam parameters at any point. The optimization method requires very little computation beyond that of a conventional ray optimization, and requires no explicit calculation of the properties of the propagating Gaussian beam. Unlike previous methods, the calculation of beam parameters does not require matrix calculations or the introduction of non-physical concepts such as imaginary rays.
Some applications of symbolic dynamics techniques to toral skew endomorphisms
NASA Astrophysics Data System (ADS)
Siboni, S.
1998-04-01
A class of dynamical systems of the 2-torus 0305-4470/31/15/026/img1 is considered. These systems have the form of a skew product between the Bernoulli endomorphism 0305-4470/31/15/026/img2, 0305-4470/31/15/026/img3, defined on the 1-torus 0305-4470/31/15/026/img4 and a translation on 0305-4470/31/15/026/img5 itself. Symbolic dynamics techniques allow one to single out wide classes of observables which show an exponential decay of correlations. For some observables the rate of correlation decay can be explicitly estimated.
Exponential speed of mixing for skew-products with singularities
NASA Astrophysics Data System (ADS)
Markarian, R.; Pacifico, M. J.; Vieitez, J. L.
2013-01-01
Let f?:?[0, 1]\\{1/2} × [0, 1] ? [0, 1] × [0, 1] be the C? endomorphism given by f(x,y)=( 2x-\\lfloor 2x\\rfloor, \\, y+ \\frac{c}{|x-1/2|}-\\lfloor y+ \\frac{c}{|x-1/2|} \\rfloor ),\\; c\\in I\\!\\!R^+\\, . We prove that f is topologically mixing and if c > 1/4 then f is mixing with respect to the Lebesgue measure. Furthermore the speed of mixing is exponential. This skew-product can be seen as a toy model related to Lorenz-like attractors.
Effect of Resonator Axis Skew on Normal Incidence Impedance
NASA Technical Reports Server (NTRS)
Parrott, Tony L.; Jones, Michael G.; Homeijer, Brian
2003-01-01
High by-pass turbofan engines have fewer fan blades and lower rotation speeds than their predecessors. Consequently, the noise suppression at the low frequency end of the noise spectra has become an increasing concern. This has led to a renewed emphasis on improving noise suppression efficiency of passive, duct liner treatments at the lower frequencies. For a variety of reasons, passive liners are comprised of locally-reacting, resonant absorbers. One reason for this design choice is to satisfy operational and economic requirements. The simplest liner design consists of a single layer of honeycomb core sandwiched between a porous facesheet and an impervious backing plate. These resonant absorbing structures are integrated into the nacelle wall and are very ef- ficient over a limited bandwidth centered on their resonance frequency. Increased noise suppression bandwidth and greater suppression at lower frequencies is typically achieved for conventional liners by increasing the liner depth and incorporating thin porous septa into the honeycomb core. However, constraints on liner depth in modern high by-pass engine nacelles severely limit the suppression bandwidth extension to lower frequencies. Also, current honeycomb core liners may not be suitable for irregular geometric volumes heretofore not considered. It is of interest, therefore, to find ways to circumvent liner depth restrictions and resonator cavity shape constraints. One way to increase effective liner depth is to skew the honeycomb core axis relative to the porous facesheet surface. Other possibilities are to alter resonator cavity shape, e.g. high aspect ratio, narrow channels that possibly include right angle bends, 180. channel fold-backs, and splayed channel walls to conform to irregular geometric constraints. These possibilities constitute the practical motivation for expanding impedance modeling capability to include unconventional resonator orientations and shapes. The work reported in this paper is in the nature of a progress report and is limited to examining the implications of resonator axis skew on the composite normal incidence impedance of an array of resonator channels. Specifically, experimental results are compared with a modified impedance prediction model for highaspect- ratio, rectangular, resonator channels with varying amounts of skew relative to the incident particle velocity. It is shown that for resonator channel widths of 1 to 2 mm, aspect ratios of 25 to 50, and skew angles of zero to sixty degrees, the surface impedance of test models can be predicted with good accuracy. Predicted resistances and reactances are particularly well correlated through the first resonance and first anti-resonance for all six test models investigated. Beyond the first anti-resonance, the impedance prediction model loses the ability to predict details of resistance and reactance but still predicts the mean trends very well.
Statistical properties of skew-endomorphisms with Bernoulli base
NASA Astrophysics Data System (ADS)
Siboni, S.
We analyse numerically the statistical properties of a class of mappings of the 2-torus T2 onto itself, whose investigation is suggested by some models of modulated diffusion. These transformations can be written as a skew-product of the endomorphism Bp( x) = px mod 1, p ? Z ? {-1, 0, 1} , on the 1-torus T1 := [0, 1] and a translation on T1. Under suitable assumptions the skew-product can be proven to be mixing w.r.t. the Lebesgue measure. Central Limit (CL) and Functional Central Limit (FCL) properties are numerically checked for analytic observables. The result is remarkable because the mappings show no hyperbolic or quasi-hyperbolic structure, crucial for the proof of Central Limit Theorem and Donsker's Invariance Principle in all of the dynamical systems where these properties have been established up to now. Moreover, CL and FCL behaviours seem to hold also in the case of purely ergodic endomorphisms and even for observables whose correlations do not decay at infinity.
Skewed sex ratios in India: "physician, heal thyself".
Patel, Archana B; Badhoniya, Neetu; Mamtani, Manju; Kulkarni, Hemant
2013-06-01
Sex selection, a gender discrimination of the worst kind, is highly prevalent across all strata of Indian society. Physicians have a crucial role in this practice and implementation of the Indian Government's Pre-Natal Diagnostic Techniques Act in 1996 to prevent the misuse of ultrasound techniques for the purpose of prenatal sex determination. Little is known about family preferences, let alone preferences among families of physicians. We investigated the sex ratios in 946 nuclear families with 1,624 children, for which either one or both parents were physicians. The overall child sex ratio was more skewed than the national average of 914. The conditional sex ratios decreased with increasing number of previous female births, and a previous birth of a daughter in the family was associated with a 38Â % reduced likelihood of a subsequent female birth. The heavily skewed sex ratios in the families of physicians are indicative of a deeply rooted social malady that could pose a critical challenge in correcting the sex ratios in India. PMID:23322380
Crossover ensembles of random matrices and skew-orthogonal polynomials
Kumar, Santosh; Pandey, Akhilesh
2011-08-15
Highlights: > We study crossover ensembles of Jacobi family of random matrices. > We consider correlations for orthogonal-unitary and symplectic-unitary crossovers. > We use the method of skew-orthogonal polynomials and quaternion determinants. > We prove universality of spectral correlations in crossover ensembles. > We discuss applications to quantum conductance and communication theory problems. - Abstract: In a recent paper (S. Kumar, A. Pandey, Phys. Rev. E, 79, 2009, p. 026211) we considered Jacobi family (including Laguerre and Gaussian cases) of random matrix ensembles and reported exact solutions of crossover problems involving time-reversal symmetry breaking. In the present paper we give details of the work. We start with Dyson's Brownian motion description of random matrix ensembles and obtain universal hierarchic relations among the unfolded correlation functions. For arbitrary dimensions we derive the joint probability density (jpd) of eigenvalues for all transitions leading to unitary ensembles as equilibrium ensembles. We focus on the orthogonal-unitary and symplectic-unitary crossovers and give generic expressions for jpd of eigenvalues, two-point kernels and n-level correlation functions. This involves generalization of the theory of skew-orthogonal polynomials to crossover ensembles. We also consider crossovers in the circular ensembles to show the generality of our method. In the large dimensionality limit, correlations in spectra with arbitrary initial density are shown to be universal when expressed in terms of a rescaled symmetry breaking parameter. Applications of our crossover results to communication theory and quantum conductance problems are also briefly discussed.
Characterising Uncertainty in Expert Assessments: Encoding Heavily Skewed Judgements
Oâ€™Leary, Rebecca A.; Low-Choy, Samantha; Fisher, Rebecca; Mengersen, Kerrie; Caley, M. Julian
2015-01-01
When limited or no observed data are available, it is often useful to obtain expert knowledge about parameters of interest, including point estimates and the uncertainty around these values. However, it is vital to elicit this information appropriately in order to obtain valid estimates. This is particularly important when the expertsâ€™ uncertainty about these estimates is strongly skewed, for instance when their best estimate is the same as the lowest value they consider possible. Also this is important when interest is in the aggregation of elicited values. In this paper, we compare alternative distributions for describing such estimates. The distributions considered include the lognormal, mirror lognormal, Normal and scaled Beta. The case study presented here involves estimation of the number of species in coral reefs, which requires eliciting counts within broader taxonomic groups, with highly skewed uncertainty estimates. This paper shows substantial gain in using the scaled Beta distribution, compared with Normal or lognormal distributions. We demonstrate that, for this case study on counting species, applying the novel encoding methodology developed in this paper can facilitate the acquisition of more rigorous estimates of (hierarchical) count data and credible bounds. The approach can also be applied to the more general case of enumerating a sampling frame via elicitation. PMID:26517835
Severe Skew Foot Deformity in a Patient With Freeman-Sheldon Syndrome
Kaissi, Ali Al; Klaushofer, Klaus; Grill, Franz
2011-01-01
We report on a 3-year-old boy with the full phenotypic features of Freeman Sheldon syndrome (FSS). Severe skew foot deformity has been recognized as additional skeletal abnormality. Parents were first degree cousins, raising the possibility of autosomal recessive pattern of inheritance. To the best of our knowledge this is the first report of severe skew foot deformity in a patient with (FSS). Keywords Freeman-Sheldon syndrome; Skew foot deformity; Metatarsus adductus PMID:22383916
NASA Astrophysics Data System (ADS)
Nakamura, Y.; Osawa, H.; Okamoto, Y.; Kanai, Y.; Muraoaka, H.
2015-05-01
The two-dimensional magnetic recording (TDMR) exploits two-dimensional signal processing using the neighboring read-back waveforms. We allocate dual readers for the intended tracks and evaluate the effects of head skew angle on the bit error rate performance in partial response class-I maximum likelihood system with a two-dimensional finite impulse response filter using two read-back waveforms under TDMR R/W channel specifications of 4 Tbit/in.2. The results show that the effect of positive skew angle is larger than that of negative skew angle, and the center of skew angle should be shifted to minus direction.
Judd, Linda J.; Asquith, William H.; Slade, Raymond M., Jr.
1996-01-01
This report presents two techniques to estimate generalized skew coefficients used for log-Pearson Type III peak-streamflow frequency analysis of natural basins in Texas. A natural basin has less than 10 percent impervious cover, and less than 10 percent of its drainage area is controlled by reservoirs. The estimation of generalized skew coefficients is based on annual peak and historical peak streamflow for all U.S. Geological Survey streamflow-gaging stations having at least 20 years of annual peak-streamflow record from natural basins in Texas. Station skew coefficients calculated for each of 255 Texas stations were used to estimate generalized skew coefficients for Texas. One technique to estimate generalized skew coefficients involved the use of regression equations developed for each of eight regions in Texas, and the other involved development of a statewide map of generalized skew coefficients. The weighted mean of the weighted mean standard errors of the regression equations for the eight regions is 0.36 log10 skew units, and the weighted mean standard error of the map is 0.35 log10 skew units. The technique based on the map is preferred for estimating generalized skew coefficients because of its smooth transition from one region of the State to another.
Liquid bridges with thermocapillarity
NASA Technical Reports Server (NTRS)
Xu, J.-J.; Davis, S. H.
1983-01-01
An axisymmetric liquid bridge is subjected to an axial temperature gradient. Thermal variations in surface tension drive a motion that is described using lubrication theory for slender bridges. At leading order in aspect ratio, a class of similarity solutions is obtained valid in the core region away from the endwalls of the bridge. These solutions describe the flows, temperature fields, and interfacial shapes of bridges that may sustain substantial interfacial deflections.
Cracked shells under skew-symmetric loading. [Reissner theory
NASA Technical Reports Server (NTRS)
Delale, F.
1981-01-01
The general problem of a shell containing a through crack in one of the principal planes of curvature and under general skew-symmetric loading is considered. By employing a Reissner type shell theory which takes into account the effect of transverse shear strains, all boundary conditions on the crack surfaces are satisfied separately. Consequently, unlike those obtained from the classical shell theory, the angular distributions of the stress components around the crack tips are shown to be identical to the distributions obtained from the plane and anti-plane elasticity solutions. Results are given for axially and circumferentially cracked cylindrical shells, spherical shells, and toroidal shells under uniform in-plane shearing, out of plane shearing, and torsion. The problem is formulated for specially orthostropic materials, therefore, the effect of orthotropy on the results is also studied.
Abundant rich phase transitions in step-skew products
NASA Astrophysics Data System (ADS)
Díaz, L. J.; Gelfert, K.; Rams, M.
2014-09-01
We study phase transitions for the topological pressure of geometric potentials of transitive sets. The sets considered are partially hyperbolic having a step-skew product dynamics over a horseshoe with one-dimensional fibres corresponding to the central direction. The sets are genuinely non-hyperbolic, containing intermingled horseshoes of different hyperbolic, behaviour (contracting and expanding centre). We construct for every k ? 1 a diffeomorphism F with a transitive set ? as above such that the pressure map P(t) = P(t ?) of the potential \\varphi= -log \\,\\Vert \\rmd F|_{E^c}\\Vert (Ec the central direction) defined on ? has k rich phase transitions. This means that there are parameters t?, ? = 0, …, k - 1, where P(t) is not differentiable and this lack of differentiability is due to the coexistence of two equilibrium states of t? ? with positive entropy and different Birkhoff averages. Each phase transition is associated with a gap in the central Lyapunov spectrum of F on ?.
Quantum uncertainty of mixed states based on skew information
Luo Shunlong
2006-02-15
The uncertainty of a mixed state has two quite different origins: classical mixing and quantum randomness. While the classical aspect (mixedness) is significantly quantified by the von Neumann entropy, it seems that we still do not have a well accepted measure of quantum uncertainty. In terms of the skew information introduced by Wigner and Yanase in 1963 in the context of quantum measurements, we will propose an intrinsic measure for synthesizing quantum uncertainty of a mixed state and investigate its fundamental properties. We illustrate how it arises naturally from a naive hidden-variable approach to entanglement and how it exhibits a simple relation to the notion of negativity, which is an entanglement monotone introduced quite recently. We further show that it has a dramatic nonextensive feature resembling the probability law relating operations of two events. This measure of quantum uncertainty provides an alternative quantity complementary to the von Neumann entropy for studying mixedness and quantum correlations.
A low nasal bridge is a flattening of the top part of the nose. ... Decreased growth (hypoplasia) of the nasal bridge may due to infections or genetic diseases. A decrease in the height of the nasal bridge is best seen from a side ...
No evidence that skewing of X chromosome inactivation patterns is transmitted to offspring in humans
Bolduc, Véronique; Chagnon, Pierre; Provost, Sylvie; Dubé, Marie-Pierre; Belisle, Claude; Gingras, Marianne; Mollica, Luigina; Busque, Lambert
2007-01-01
Skewing of X chromosome inactivation (XCI) can occur in normal females and increases in tissues with age. The mechanisms underlying skewing in normal females, however, remain controversial. To better understand the phenomenon of XCI in nondisease states, we evaluated XCI patterns in epithelial and hematopoietic cells of over 500 healthy female mother-neonate pairs. The incidence of skewing observed in mothers was twice that observed in neonates, and in both cohorts, the incidence of XCI was lower in epithelial cells than hematopoietic cells. These results suggest that XCI incidence varies by tissue type and that age-dependent mechanisms can influence skewing in both epithelial and hematopoietic cells. In both cohorts, a correlation was identified in the direction of skewing in epithelial and hematopoietic cells, suggesting common underlying skewing mechanisms across tissues. However, there was no correlation between the XCI patterns of mothers and their respective neonates, and skewed mothers gave birth to skewed neonates at the same frequency as nonskewed mothers. Taken together, our data suggest that in humans, the XCI pattern observed at birth does not reflect a single heritable genetic locus, but rather corresponds to a complex trait determined, at least in part, by selection biases occurring after XCI. PMID:18097474
GC skew is a conserved property of unmethylated CpG island promoters across vertebrates
Hartono, Stella R.; Korf, Ian F.; ChÃ©din, FrÃ©dÃ©ric
2015-01-01
GC skew is a measure of the strand asymmetry in the distribution of guanines and cytosines. GC skew favors R-loops, a type of three stranded nucleic acid structures that form upon annealing of an RNA strand to one strand of DNA, creating a persistent RNA:DNA hybrid. Previous studies show that GC skew is prevalent at thousands of human CpG island (CGI) promoters and transcription termination regions, which correspond to hotspots of R-loop formation. Here, we investigated the conservation of GC skew patterns in 60 sequenced chordates genomes. We report that GC skew is a conserved sequence characteristic of the CGI promoter class in vertebrates. Furthermore, we reveal that promoter GC skew peaks at the exon 1/ intron1 junction and that it is highly correlated with gene age and CGI promoter strength. Our data also show that GC skew is predictive of unmethylated CGI promoters in a range of vertebrate species and that it imparts significant DNA hypomethylation for promoters with intermediate CpG densities. Finally, we observed that terminal GC skew is conserved for a subset of vertebrate genes that tend to be located significantly closer to their downstream neighbors, consistent with a role for R-loop formation in transcription termination. PMID:26253743
GC skew is a conserved property of unmethylated CpG island promoters across vertebrates.
Hartono, Stella R; Korf, Ian F; ChÃ©din, FrÃ©dÃ©ric
2015-11-16
GC skew is a measure of the strand asymmetry in the distribution of guanines and cytosines. GC skew favors R-loops, a type of three stranded nucleic acid structures that form upon annealing of an RNA strand to one strand of DNA, creating a persistent RNA:DNA hybrid. Previous studies show that GC skew is prevalent at thousands of human CpG island (CGI) promoters and transcription termination regions, which correspond to hotspots of R-loop formation. Here, we investigated the conservation of GC skew patterns in 60 sequenced chordates genomes. We report that GC skew is a conserved sequence characteristic of the CGI promoter class in vertebrates. Furthermore, we reveal that promoter GC skew peaks at the exon 1/ intron1 junction and that it is highly correlated with gene age and CGI promoter strength. Our data also show that GC skew is predictive of unmethylated CGI promoters in a range of vertebrate species and that it imparts significant DNA hypomethylation for promoters with intermediate CpG densities. Finally, we observed that terminal GC skew is conserved for a subset of vertebrate genes that tend to be located significantly closer to their downstream neighbors, consistent with a role for R-loop formation in transcription termination. PMID:26253743
Bandyopadhyay, Dipankar; Lachos, Victor H.; Abanto-Valle, Carlos A.; Ghosh, Pulak
2010-01-01
Bivariate clustered (correlated) data often encountered in epidemiological and clinical research are routinely analyzed under a linear mixed model framework with underlying normality assumptions of the random effects and within-subject errors. However, such normality assumptions might be questionable if the data-set particularly exhibit skewness and heavy tails. Using a Bayesian paradigm, we use the skew-normal/independent (SNI) distribution as a tool for modeling clustered data with bivariate non-normal responses in a linear mixed model framework. The SNI distribution is an attractive class of asymmetric thick-tailed parametric structure which includes the skew-normal distribution as a special case. We assume that the random effects follows multivariate skew-normal/independent distributions and the random errors follow symmetric normal/independent distributions which provides substantial robustness over the symmetric normal process in a linear mixed model framework. Specific distributions obtained as special cases, viz. the skew-t, the skew-slash and the skew-contaminated normal distributions are compared, along with the default skew-normal density. The methodology is illustrated through an application to a real data which records the periodontal health status of an interesting population using periodontal pocket depth (PPD) and clinical attachment level (CAL). PMID:20740568
Optimization of a magnetic disk drive actuator with small skew actuation
NASA Astrophysics Data System (ADS)
He, Zhimin; Ong, Eng Hong; Guo, Guoxiao
2002-05-01
Currently the utilization of the voice-coil motor for actuating read/write head elements in magnetic hard disk drives results in a skewed actuation, which necessitates an involved microjogging process and thus a complicated servo system. Furthermore, in perpendicular recording systems, a small skew actuation will relax the requirement on pole trimming. This article presents a magnetic hard disk drive actuator and suspension assembly with small skew actuation. In the present study, the distance from the actuator pivot to the read/write head is chosen so that the skew angle variation is minimized. After that, the suspension head is assembled to the actuator arm at a slant angle with respect to the actuator longitudinal direction to achieve an absolute small skew actuation. Finite element modeling and experimental measurements reveal that there are no significant changes of the actuator assembly dynamic performance with and without the slant angle.
Ishido, Naoko; Inoue, Naoya; Watanabe, Mikio; Hidaka, Yoh
2015-01-01
Background: Autoimmune thyroid diseases (AITDs) predominantly develop in females. One of two X chromosomes is randomly inactivated by methylation in each female cell, but it has been reported that skewed X chromosome inactivation (XCI) may be associated with the development of autoimmune diseases. To clarify the significance of skewed XCI in the prognosis and development of AITD, we investigated the proportion of skewed XCI in female patients with AITD. Methods: We analyzed the degree of XCI skewing in 120 female patients with AITD (77 patients with Graves' disease [GD] and 43 patients with Hashimoto's disease [HD]) and 49 female controls in DNA from peripheral blood mononuclear cells (PBMC). We performed XCI analysis by digesting inactive DNA with a methylation-sensitive restriction enzyme (HpaII) followed by a polymerase chain reaction (PCR) assay for the polymorphic CAG repeat of the androgen receptor gene and electrophoresis of the PCR products. Results: The proportion of skewed XCI (?65% skewing) was not significantly different between AITD patients and control subjects but was higher in patients with intractable GD (66.7%) than those with GD in remission (25.0%, p=0.0033) and control subjects (32.6%, p=0.0038). When the cutoff value for XCI skewing was relaxed, the proportion of skewed XCI (?60% skewing) was higher in patients with severe HD (76.5%) than in those with mild HD (41.2%, p=0.0342). Conclusions: Skewed XCI is related to the prognosis of AITD, particularly the intractability of GD. PMID:25338305
NASA Technical Reports Server (NTRS)
Nypan, L. J.
1980-01-01
Measurements of roller skewing in a 118 mm bore roller bearing operating at shaft speeds to 12000 rpm are reported. High speed motion pictures of a modified roller were taken through a derotation prism to record skewing as the roller moved through loaded and unloaded regions of the bearing. Subsequent frame by frame measurement of the photographic film provided information on roller skewing. Radial and tangential skew amplitudes of .4 to .5 degrees were observed with .5 degree misalignment.
Log Pearson type 3 quantile estimators with regional skew information and low outlier adjustments
Griffis, V.W.; Stedinger, J.R.; Cohn, T.A.
2004-01-01
[1] The recently developed expected moments algorithm (EMA) [Cohn et al., 1997] does as well as maximum likelihood estimations at estimating log-Pearson type 3 (LP3) flood quantiles using systematic and historical flood information. Needed extensions include use of a regional skewness estimator and its precision to be consistent with Bulletin 17B. Another issue addressed by Bulletin 17B is the treatment of low outliers. A Monte Carlo study compares the performance of Bulletin 17B using the entire sample with and without regional skew with estimators that use regional skew and censor low outliers, including an extended EMA estimator, the conditional probability adjustment (CPA) from Bulletin 17B, and an estimator that uses probability plot regression (PPR) to compute substitute values for low outliers. Estimators that neglect regional skew information do much worse than estimators that use an informative regional skewness estimator. For LP3 data the low outlier rejection procedure generally results in no loss of overall accuracy, and the differences between the MSEs of the estimators that used an informative regional skew are generally modest in the skewness range of real interest. Samples contaminated to model actual flood data demonstrate that estimators which give special treatment to low outliers significantly outperform estimators that make no such adjustment.
Modulation of Root Skewing in Arabidopsis by Apyrases and Extracellular ATP.
Yang, Xingyan; Wang, Bochu; Farris, Ben; Clark, Greg; Roux, Stanley J
2015-11-01
When plant primary roots grow along a tilted surface that is impenetrable, they can undergo a slanted deviation from the direction of gravity called skewing. Skewing is induced by touch stimuli which the roots experience as they grow along the surface. Touch stimuli also induce the release of extracellular ATP (eATP) into the plant's extracellular matrix, and two apyrases (NTPDases) in Arabidopsis, APY1 and APY2, can help regulate the concentration of eATP. The primary roots of seedlings overexpressing APY1 show less skewing than wild-type plants. Plants suppressed in their expression of APY1 show more skewing than wild-type plants. Correspondingly, chemical inhibition of apyrase activity increased skewing in mutants and wild-type roots. Exogenous application of ATP or ATPÎ³S also increased skewing in wild-type roots, which could be blocked by co-incubation with a purinergic receptor antagonist. These results suggest a model in which gradients of eATP set up by differential touch stimuli along roots help direct skewing in roots growing along an impenetrable surface. PMID:26412783
Skew redundant MEMS IMU calibration using a Kalman filter
NASA Astrophysics Data System (ADS)
Jafari, M.; Sahebjameyan, M.; Moshiri, B.; Najafabadi, T. A.
2015-10-01
In this paper, a novel calibration procedure for skew redundant inertial measurement units (SRIMUs) based on micro-electro mechanical systems (MEMS) is proposed. A general model of the SRIMU measurements is derived which contains the effects of bias, scale factor error and misalignments. For more accuracy, the effect of lever arms of the accelerometers to the center of the table are modeled and compensated in the calibration procedure. Two separate Kalman filters (KFs) are proposed to perform the estimation of error parameters for gyroscopes and accelerometers. The predictive error minimization (PEM) stochastic modeling method is used to simultaneously model the effect of bias instability and random walk noise on the calibration Kalman filters to diminish the biased estimations. The proposed procedure is simulated numerically and has expected experimental results. The calibration maneuvers are applied using a two-axis angle turntable in a way that the persistency of excitation (PE) condition for parameter estimation is met. For this purpose, a trapezoidal calibration profile is utilized to excite different deterministic error parameters of the accelerometers and a pulse profile is used for the gyroscopes. Furthermore, to evaluate the performance of the proposed KF calibration method, a conventional least squares (LS) calibration procedure is derived for the SRIMUs and the simulation and experimental results compare the functionality of the two proposed methods with each other.
Statistics on Cannabis Users Skew Perceptions of Cannabis Use
Burns, Rachel M.; Caulkins, Jonathan P.; Everingham, Susan S.; Kilmer, Beau
2013-01-01
Collecting information about the prevalence of cannabis use is necessary but not sufficient for understanding the size, dynamics, and outcomes associated with cannabis markets. This paper uses two data sets describing cannabis consumption in the United States and Europe to highlight (1) differences in inferences about sub-populations based on the measure used to quantify cannabis-related activity; (2) how different measures of cannabis-related activity can be used to more accurately describe trends in cannabis usage over time; and (3) the correlation between frequency of use in the past-month and average grams consumed per use-day. Key findings: focusing on days of use instead of prevalence shows substantially greater increases in U.S. cannabis use in recent years; however, the recent increase is mostly among adults, not youth. Relatively more rapid growth in use days also occurred among the college-educated and Hispanics. Further, data from a survey conducted in seven European countries show a strong positive correlation between frequency of use and quantity consumed per day of use, suggesting consumption is even more skewed toward the minority of heavy users than is suggested by days-of-use calculations. PMID:24223560
Regression for skewed biomarker outcomes subject to pooling.
Mitchell, Emily M; Lyles, Robert H; Manatunga, Amita K; Danaher, Michelle; Perkins, Neil J; Schisterman, Enrique F
2014-03-01
Epidemiological studies involving biomarkers are often hindered by prohibitively expensive laboratory tests. Strategically pooling specimens prior to performing these lab assays has been shown to effectively reduce cost with minimal information loss in a logistic regression setting. When the goal is to perform regression with a continuous biomarker as the outcome, regression analysis of pooled specimens may not be straightforward, particularly if the outcome is right-skewed. In such cases, we demonstrate that a slight modification of a standard multiple linear regression model for poolwise data can provide valid and precise coefficient estimates when pools are formed by combining biospecimens from subjects with identical covariate values. When these x-homogeneous pools cannot be formed, we propose a Monte Carlo expectation maximization (MCEM) algorithm to compute maximum likelihood estimates (MLEs). Simulation studies demonstrate that these analytical methods provide essentially unbiased estimates of coefficient parameters as well as their standard errors when appropriate assumptions are met. Furthermore, we show how one can utilize the fully observed covariate data to inform the pooling strategy, yielding a high level of statistical efficiency at a fraction of the total lab cost. PMID:24521420
Regression for Skewed Biomarker Outcomes Subject to Pooling
Mitchell, Emily M.; Lyles, Robert H.; Manatunga, Amita K.; Danaher, Michelle; Perkins, Neil J.; Schisterman, Enrique F.
2014-01-01
Summary Epidemiological studies involving biomarkers are often hindered by prohibitively expensive laboratory tests. Strategically pooling specimens prior to performing these lab assays has been shown to effectively reduce cost with minimal information loss in a logistic regression setting. When the goal is to perform regression with a continuous biomarker as the outcome, regression analysis of pooled specimens may not be straightforward, particularly if the outcome is right-skewed. In such cases, we demonstrate that a slight modification of a standard multiple linear regression model for poolwise data can provide valid and precise coefficient estimates when pools are formed by combining biospecimens from subjects with identical covariate values. When these x-homogeneous pools cannot be formed, we propose a Monte Carlo Expectation Maximization (MCEM) algorithm to compute maximum likelihood estimates (MLEs). Simulation studies demonstrate that these analytical methods provide essentially unbiased estimates of coefficient parameters as well as their standard errors when appropriate assumptions are met. Furthermore, we show how one can utilize the fully observed covariate data to inform the pooling strategy, yielding a high level of statistical efficiency at a fraction of the total lab cost. PMID:24521420
LOOKING WNW, CHEVROLET AVENUE BRIDGE CROSSING FLINT RIVER. BRIDGE CONNECTED ...
LOOKING WNW, CHEVROLET AVENUE BRIDGE CROSSING FLINT RIVER. BRIDGE CONNECTED NORTH AND SOUTH PORTIONS OF FACTORY COMPLEX. DANIEL LUTEN DESIGNED THE BRIDGE, AND ILLINOIS BRIDGE COMPANY BUILT IT IN 1918. THE BRIDGE WAS THE SITE OF THE BATTLE OF RUNNING BULLS IN THE 1936-1937 GM SIT DOWN STRIKE. - Delphi Flint West, 300 Chevrolet Avenue, Flint, Genesee County, MI
Semiconductor bridge (SCB) detonator
Bickes, R.W. Jr.; Grubelich, M.C.
1999-01-19
The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge (SCB) igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length. 3 figs.
Semiconductor bridge (SCB) detonator
Bickes, Jr., Robert W.; Grubelich, Mark C.
1999-01-01
The present invention is a low-energy detonator for high-density secondary-explosive materials initiated by a semiconductor bridge igniter that comprises a pair of electrically conductive lands connected by a semiconductor bridge. The semiconductor bridge is in operational or direct contact with the explosive material, whereby current flowing through the semiconductor bridge causes initiation of the explosive material. Header wires connected to the electrically-conductive lands and electrical feed-throughs of the header posts of explosive devices, are substantially coaxial to the direction of current flow through the SCB, i.e., substantially coaxial to the SCB length.
NASA Astrophysics Data System (ADS)
Thierjung, Brianna; Jorge Moreno, Paul Torrey, Phil Hopkins
2016-01-01
We employ a suite of 75 simulations of galaxies in idealized major mergers to investigate the bridges formed by interactions. These simulations are based on the Feedback in Realistic Environments (FIRE) model (Hopkins et al. 2011). Moreover, unlike past work, we have both the resolution and diversity in merging orbits to make statistically meaningful predictions. We find that very dense, star forming bridges can be characterized as strong bridges. In particular, prograde mergers with high eccentricities and high impact parameters produce the most mass of stars in the bridge.
A novel bridge scour monitoring and prediction system
NASA Astrophysics Data System (ADS)
Valyrakis, Manousos; Michalis, Panagiotis; Zhang, Hanqing
2015-04-01
Earth's surface is continuously shaped due to the action of geophysical flows. Erosion due to the flow of water in river systems has been identified as a key problem in preserving ecological health but also a threat to our built environment and critical infrastructure, worldwide. As an example, it has been estimated that a major reason for bridge failure is due to scour. Even though the flow past bridge piers has been investigated both experimentally and numerically, and the mechanisms of scouring are relatively understood, there still lacks a tool that can offer fast and reliable predictions. Most of the existing formulas for prediction of bridge pier scour depth are empirical in nature, based on a limited range of data or for piers of specific shape. In this work, the use of a novel methodology is proposed for the prediction of bridge scour. Specifically, the use of an Adaptive Neuro-Fuzzy Inference System (ANFIS) is proposed to estimate the scour depth around bridge piers. In particular, various complexity architectures are sequentially built, in order to identify the optimal for scour depth predictions, using appropriate training and validation subsets obtained from the USGS database (and pre-processed to remove incomplete records). The model has five variables, namely the effective pier width (b), the approach velocity (v), the approach depth (y), the mean grain diameter (D50) and the skew to flow. Simulations are conducted with data groups (bed material type, pier type and shape) and different number of input variables, to produce reduced complexity and easily interpretable models. Analysis and comparison of the results indicate that the developed ANFIS model has high accuracy and outstanding generalization ability for prediction of scour parameters. The effective pier width (as opposed to skew to flow) is amongst the most relevant input parameters for the estimation. Training of the system to new bridge geometries and flow conditions can be achieved by obtaining real time data, via novel electromagnetic sensors monitoring scour depth. Once the model is trained with data representative of the new system, bridge scour prediction can be performed for high/design flows or floods.
1. VIEW OF SWING BRIDGE FROM KEDZIE AVENUE BRIDGE, LOOKING ...
1. VIEW OF SWING BRIDGE FROM KEDZIE AVENUE BRIDGE, LOOKING EAST. - Chicago, Madison & Northern Railroad, Sanitary & Ship Canal Bridge, Spanning Sanitary & Ship Canal, east of Kedzie Avenue, Chicago, Cook County, IL
GOETHALS BRIDGE FROM NORTH SIDE OVER ARTHUR KILL. RAILROAD BRIDGE ...
GOETHALS BRIDGE FROM NORTH SIDE OVER ARTHUR KILL. RAILROAD BRIDGE IN FOREGROUND - Goethals Bridge, Spanning Arthur Kill from New Jersey to Staten Island, Staten Island (subdivision), Richmond County, NY
DISTANT ELEVATION, NOTE CREEK BRIDGE FOREGROUND, COVERED BRIDGE OVER DIFFERENT ...
DISTANT ELEVATION, NOTE CREEK BRIDGE FOREGROUND, COVERED BRIDGE OVER DIFFERENT STREAM IN THE BACKGROUND, NORTHEAST PORTAL - Larwood Bridge, Spanning Crabtree Creek, Fish Hatchery Road (CR 648), Lacomb, Linn County, OR
3. OVERALL VIEW OF BRIDGE, WAUBONSIE HIGHWAY BRIDGE, AND MISSOURI ...
3. OVERALL VIEW OF BRIDGE, WAUBONSIE HIGHWAY BRIDGE, AND MISSOURI RIVER; VIEW TO NORTH - Nebraska City Bridge, Spanning Missouri River near Highway 2 between Nebraska & Iowa, Nebraska City, Otoe County, NE
Plans: Poop Deck, Boat Deck, Housetop, Bridge Deck, Upper Bridge ...
Plans: Poop Deck, Boat Deck, Housetop, Bridge Deck, Upper Bridge Deck, Navigating Bridge, Forecastle Deck, Upper Deck, Second Deck and Hold - Saugatuck, James River Reserve Fleet, Newport News, Newport News, VA
2. OVERALL VIEW OF BRIDGE, WAUBONSIE HIGHWAY BRIDGE (1930), AND ...
2. OVERALL VIEW OF BRIDGE, WAUBONSIE HIGHWAY BRIDGE (1930), AND MISSOURI RIVER; VIEW TO NORTHEAST - Nebraska City Bridge, Spanning Missouri River near Highway 2 between Nebraska & Iowa, Nebraska City, Otoe County, NE
APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN ...
APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN FROM ENTRY. VIEW FACING NORTHWEST - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI
APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN ...
APPROACH BRIDGE PORTION OF VALVE TOWER FOOT BRIDGE, AS SEEN FROM BELOW, SHOWING VALVE TOWER TO RIGHT. VIEW FACING NORTH - Schofield Barracks Military Reservation, Ku Tree Reservoir, Valve Tower Foot Bridge, Kalakoa Stream, East Range, Wahiawa, Honolulu County, HI
18. SPRING STREET BRIDGE AND BROADWAY BRIDGE AT CENTER. LOOKING ...
18. SPRING STREET BRIDGE AND BROADWAY BRIDGE AT CENTER. LOOKING NORTHWEST. NOTE ELYSIAN PARK AT CENTER REAR. ARROYO SECO FREEWAY AT RIGHT REAR - Los Angeles River Bridges, Los Angeles, Los Angeles County, CA
Skewed birth sex ratio and premature mortality in elephants.
Saragusty, Joseph; Hermes, Robert; GÃ¶ritz, Frank; Schmitt, Dennis L; Hildebrandt, Thomas B
2009-10-01
Sex allocation theories predict equal offspring number of both sexes unless differential investment is required or some competition exists. Left undisturbed, elephants reproduce well and in approximately even numbers in the wild. We report an excess of males are born and substantial juvenile mortality occurs, perinatally, in captivity. Studbook data on captive births (CB, n=487) and premature deaths (PD, <5 years of age; n=164) in Asian and African elephants in Europe and North America were compared with data on Myanmar timber (Asian) elephants (CB, n=3070; PD, n=738). Growth in CB was found in three of the captive populations. A significant excess of male births occurred in European Asian elephants (ratio: 0.61, P=0.044) and in births following artificial insemination (0.83, P=0.003), and a numerical inclination in North American African elephants (0.6). While juvenile mortality in European African and Myanmar populations was 21-23%, it was almost double (40-45%) in all other captive populations. In zoo populations, 68-91% of PD were within 1 month of birth with stillbirth and infanticide being major causes. In Myanmar, 62% of juvenile deaths were at >6 months with maternal insufficient milk production, natural hazards and accidents being the main causes. European Asian and Myanmar elephants PD was biased towards males (0.71, P=0.024 and 0.56, P<0.001, respectively). The skewed birth sex ratio and high juvenile mortality hinder efforts to help captive populations become self-sustaining. Efforts should be invested to identify the mechanism behind these trends and seek solutions for them. PMID:19058933
Genetic Architecture of Skewed X Inactivation in the Laboratory Mouse
Calaway, John D.; Lenarcic, Alan B.; Didion, John P.; Wang, Jeremy R.; Searle, Jeremy B.; McMillan, Leonard; Valdar, William; Pardo-Manuel de Villena, Fernando
2013-01-01
X chromosome inactivation (XCI) is the mammalian mechanism of dosage compensation that balances X-linked gene expression between the sexes. Early during female development, each cell of the embryo proper independently inactivates one of its two parental X-chromosomes. In mice, the choice of which X chromosome is inactivated is affected by the genotype of a cis-acting locus, the X-chromosome controlling element (Xce). Xce has been localized to a 1.9 Mb interval within the X-inactivation center (Xic), yet its molecular identity and mechanism of action remain unknown. We combined genotype and sequence data for mouse stocks with detailed phenotyping of ten inbred strains and with the development of a statistical model that incorporates phenotyping data from multiple sources to disentangle sources of XCI phenotypic variance in natural female populations on X inactivation. We have reduced the Xce candidate 10-fold to a 176 kb region located approximately 500 kb proximal to Xist. We propose that structural variation in this interval explains the presence of multiple functional Xce alleles in the genus Mus. We have identified a new allele, Xcee present in Mus musculus and a possible sixth functional allele in Mus spicilegus. We have also confirmed a parent-of-origin effect on X inactivation choice and provide evidence that maternal inheritance magnifies the skewing associated with strong Xce alleles. Based on the phylogenetic analysis of 155 laboratory strains and wild mice we conclude that Xcea is either a derived allele that arose concurrently with the domestication of fancy mice but prior the derivation of most classical inbred strains or a rare allele in the wild. Furthermore, we have found that despite the presence of multiple haplotypes in the wild Mus musculus domesticus has only one functional Xce allele, Xceb. Lastly, we conclude that each mouse taxa examined has a different functional Xce allele. PMID:24098153
Intermittency route to strange nonchaotic attractors in a non-skew-product map
NASA Astrophysics Data System (ADS)
Mitsui, Takahito; Aizawa, Yoji
2010-04-01
Whether strange nonchaotic attractors (SNAs) can typically arise in non-skew-product maps has been a crucial question for more than two decades. Recently, it was shown that SNAs arise in a particular non-skew-product map related to quasiperiodically driven continuous dynamical systems [R. Badard, Chaos, Solitons Fractals 28, 1327 (2006); Chaos 18, 023127 (2008)]. In the present paper, we derive Badard’s non-skew-product map from a periodically driven continuous dynamical system with spatially quasiperiodic potential and investigate onset mechanisms of SNAs in the map. In particular, we focus on a transition route to intermittent SNAs, where SNAs appear after pair annihilations of stable and unstable fixed points located on a ring-shaped invariant curve. Then the mean residence time and rotation numbers have a logarithmic singularity. Finally, we discuss the existence of SNAs in a special class of non-skew-product maps.
Oberg, Kevin A.; Mades, Dean M.
1987-01-01
Four techniques for estimating generalized skew in Illinois were evaluated: (1) a generalized skew map of the US; (2) an isoline map; (3) a prediction equation; and (4) a regional-mean skew. Peak-flow records at 730 gaging stations having 10 or more annual peaks were selected for computing station skews. Station skew values ranged from -3.55 to 2.95, with a mean of -0.11. Frequency curves computed for 30 gaging stations in Illinois using the variations of the regional-mean skew technique are similar to frequency curves computed using a skew map developed by the US Water Resources Council (WRC). Estimates of the 50-, 100-, and 500-yr floods computed for 29 of these gaging stations using the regional-mean skew techniques are within the 50% confidence limits of frequency curves computed using the WRC skew map. Although the three variations of the regional-mean skew technique were slightly more accurate than the WRC map, there is no appreciable difference between flood estimates computed using the variations of the regional-mean technique and flood estimates computed using the WRC skew map. (Peters-PTT)
The Bryce Canyon Natural Bridge. Technically, this is not a natural bridge, which forms when running water erodes a tunnel into a rock formation. Instead, this is a natural arch, similar to the ones in nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is...
Wessendorf, Kurt O.
2001-01-01
An active bridge oscillator is formed from a differential amplifier where positive feedback is a function of the impedance of one of the gain elements and a relatively low value common emitter resistance. This use of the nonlinear transistor parameter h stabilizes the output and eliminates the need for ALC circuits common to other bridge oscillators.
NASA Technical Reports Server (NTRS)
White, D. R.
1968-01-01
Prototype precision bolometer calibration bridge is manually balanced device for indicating dc bias and balance with either dc or ac power. An external galvanometer is used with the bridge for null indication, and the circuitry monitors voltage and current simultaneously without adapters in testing 100 and 200 ohm thin film bolometers.
ERIC Educational Resources Information Center
Black, Carolyn B.
This paper outlines a three semester hour undergraduate, core course in Scientific Inquiry that increases student knowledge and advances student skills in understanding science as knowledge, process, and human enterprise. This course was developed as a bridge between science and the humanities and a bridge for entry-level students in the…
Virtual Bridge Design Challenge
ERIC Educational Resources Information Center
Mitts, Charles R.
2013-01-01
This design/problem-solving activity challenges students to design a replacement bridge for one that has been designated as either structurally deficient or functionally obsolete. The Aycock MS Technology/STEM Magnet Program Virtual Bridge Design Challenge is an authentic introduction to the engineering design process. It is a socially relevant…
Virtual Bridge Design Challenge
ERIC Educational Resources Information Center
Mitts, Charles R.
2013-01-01
This design/problem-solving activity challenges students to design a replacement bridge for one that has been designated as either structurally deficient or functionally obsolete. The Aycock MS Technology/STEM Magnet Program Virtual Bridge Design Challenge is an authentic introduction to the engineering design process. It is a socially relevantâ€¦
Support column of bridge across Struve Slough, Highway 1. Enlargement of hole where support enters the ground is an effect of lateral shaking, which caused the concrete to break up where the column joined the bridge and was instrumental in the roadbed collapse....
NASA Astrophysics Data System (ADS)
Wei, Jun; Zhong, Fangyuan
Based on comparative experiment, this paper deals with using tangentially skewed rotor blades in axial-flow fan. It is seen from the comparison of the overall performance of the fan with skewed bladed rotor and radial bladed rotor that the skewed blades operate more efficiently than the radial blades, especially at low volume flows. Meanwhile, decrease in pressure rise and flow rate of axial-flow fan with skewed rotor blades is found. The rotor-stator interaction noise and broadband noise of axial-flow fan are reduced with skewed rotor blades. Forward skewed blades tend to reduce the accumulation of the blade boundary layer in the tip region resulting from the effect of centrifugal forces. The turning of streamlines from the outer radius region into inner radius region in blade passages due to the radial component of blade forces of skewed blades is the main reason for the decrease in pressure rise and flow rate.
LODGEPOLE BRIDGE, FACING SOUTHEAST Generals Highway, Lodge Pole Bridge, ...
LODGEPOLE BRIDGE, FACING SOUTHEAST - Generals Highway, Lodge Pole Bridge, Spanning Marble Fork of Kaweah River, approximately 21 miles northwest of Ash Mountain Entrance, Three Rivers, Tulare County, CA
LODGEPOLE BRIDGE, FACING NORTHWEST Generals Highway, Lodge Pole Bridge, ...
LODGEPOLE BRIDGE, FACING NORTHWEST - Generals Highway, Lodge Pole Bridge, Spanning Marble Fork of Kaweah River, approximately 21 miles northwest of Ash Mountain Entrance, Three Rivers, Tulare County, CA
A study on the effects of a skewed distribution on the EWMA and MA charts
NASA Astrophysics Data System (ADS)
Liew, Jeng Young; Khoo, Michael Boon Chong; Neoh, Siang Gee
2014-07-01
The control chart is the most powerful tool in statistical process control. A control chart is a graphical display used to determine the presence of assignable causes so that prompt corrective actions can be taken to remove such causes before many nonconforming products are produced. The exponentially weighted moving average (EWMA) and moving average (MA) charts are very effective in detecting small and moderate shifts in the process mean. These two charts are constructed based on the properties of the normal distribution. In many practical applications, the validity of the normality assumption is always doubted as the process distribution could be skewed. A skewed distribution can result in a higher incidence of false alarms. This is due to the inconsistencies between the spread of a skewed distribution and the normality assumption employed in setting up a control chart. This paper studies the effects of a skewed distribution on the performances of the EWMA and MA charts, in terms of the charts' false alarm rates. We compare the in-control average run length (ARL0) performance of these two charts when the underlying distributions are normal and skewed. The gamma distribution is selected to represent the skewed distribution. A Monte Carlo simulation using the Statistical Analysis System (SAS) software is carried out to compute the necessary ARL0s. The findings of this study show that the ARL0 performance of the EWMA and MA charts is substantially affected by the skewed distribution. However, the MA chart is not as robust as the EWMA chart, in terms of the ARL0, when the distribution is skewed.
An Adaptive Method for Reducing Clock Skew in an Accumulative Z-Axis Interconnect System
NASA Technical Reports Server (NTRS)
Bolotin, Gary; Boyce, Lee
1997-01-01
This paper will present several methods for adjusting clock skew variations that occur in a n accumulative z-axis interconnect system. In such a system, delay between modules in a function of their distance from one another. Clock distribution in a high-speed system, where clock skew must be kept to a minimum, becomes more challenging when module order is variable before design.
Landfors, Mattias; Philip, Philge; RydÃ©n, Patrik; Stenberg, Per
2011-01-01
Genome-wide analysis of gene expression or protein binding patterns using different array or sequencing based technologies is now routinely performed to compare different populations, such as treatment and reference groups. It is often necessary to normalize the data obtained to remove technical variation introduced in the course of conducting experimental work, but standard normalization techniques are not capable of eliminating technical bias in cases where the distribution of the truly altered variables is skewed, i.e. when a large fraction of the variables are either positively or negatively affected by the treatment. However, several experiments are likely to generate such skewed distributions, including ChIP-chip experiments for the study of chromatin, gene expression experiments for the study of apoptosis, and SNP-studies of copy number variation in normal and tumour tissues. A preliminary study using spike-in array data established that the capacity of an experiment to identify altered variables and generate unbiased estimates of the fold change decreases as the fraction of altered variables and the skewness increases. We propose the following work-flow for analyzing high-dimensional experiments with regions of altered variables: (1) Pre-process raw data using one of the standard normalization techniques. (2) Investigate if the distribution of the altered variables is skewed. (3) If the distribution is not believed to be skewed, no additional normalization is needed. Otherwise, re-normalize the data using a novel HMM-assisted normalization procedure. (4) Perform downstream analysis. Here, ChIP-chip data and simulated data were used to evaluate the performance of the work-flow. It was found that skewed distributions can be detected by using the novel DSE-test (Detection of Skewed Experiments). Furthermore, applying the HMM-assisted normalization to experiments where the distribution of the truly altered variables is skewed results in considerably higher sensitivity and lower bias than can be attained using standard and invariant normalization methods. PMID:22132175
Reproductive skew theory unified: the general bordered tug-of-war model.
Shen, Sheng-Feng; Kern Reeve, H
2010-03-01
Reproductive skew has been identified as a major dimension along which animal societies vary. Two major kinds of reproductive skew models are transactional models, which explain the distribution of reproduction within animal societies as the result of reproductive payments exchanged among group members with differential leverage, and tug-of-war models, in which the reproductive shares are determined by costly 'tugs-of-war'. These two models have recently been synthesized to yield the mutual-pay, bordered tug-of-war model. In this paper, we extend the latter, show its evolutionary stability, and demonstrate that the generalized model yields four sub-models, namely the mutual-pay, alpha-pay, beta-pay, and pure tug-of-war. The alpha-pay sub-model turns out to closely resemble the original "concessions" transactional skew model, and the beta-pay sub-model turns out to have properties similar to the "restraint" transactional skew model. Thus, the general model unifies the four major models of reproductive skew and is rich in its predictions, as each sub-model exhibits different qualitative and quantitative relationships between reproductive skew or intra-group conflict and the ecological and genetic factors that determine skew and conflict. The conditions favoring transitions among these sub-models also are precisely predicted by the general model. The general model accommodates data from acorn woodpeckers and primitively eusocial bees potentially can account for many of the highly varied empirical findings on reproductive skew. We suggest further research that focuses on (1) determining which model is suitable for certain species and (2) understanding why and how various social animals resolve their breeding conflict by different conflict resolution mechanisms. PMID:19932705
Static performance investigation of a skewed-throat multiaxis thrust-vectoring nozzle concept
NASA Technical Reports Server (NTRS)
Wing, David J.
1994-01-01
The static performance of a jet exhaust nozzle which achieves multiaxis thrust vectoring by physically skewing the geometric throat has been characterized in the static test facility of the 16-Foot Transonic Tunnel at NASA Langley Research Center. The nozzle has an asymmetric internal geometry defined by four surfaces: a convergent-divergent upper surface with its ridge perpendicular to the nozzle centerline, a convergent-divergent lower surface with its ridge skewed relative to the nozzle centerline, an outwardly deflected sidewall, and a straight sidewall. The primary goal of the concept is to provide efficient yaw thrust vectoring by forcing the sonic plane (nozzle throat) to form at a yaw angle defined by the skewed ridge of the lower surface contour. A secondary goal is to provide multiaxis thrust vectoring by combining the skewed-throat yaw-vectoring concept with upper and lower pitch flap deflections. The geometric parameters varied in this investigation included lower surface ridge skew angle, nozzle expansion ratio (divergence angle), aspect ratio, pitch flap deflection angle, and sidewall deflection angle. Nozzle pressure ratio was varied from 2 to a high of 11.5 for some configurations. The results of the investigation indicate that efficient, substantial multiaxis thrust vectoring was achieved by the skewed-throat nozzle concept. However, certain control surface deflections destabilized the internal flow field, which resulted in substantial shifts in the position and orientation of the sonic plane and had an adverse effect on thrust-vectoring and weight flow characteristics. By increasing the expansion ratio, the location of the sonic plane was stabilized. The asymmetric design resulted in interdependent pitch and yaw thrust vectoring as well as nonzero thrust-vector angles with undeflected control surfaces. By skewing the ridges of both the upper and lower surface contours, the interdependency between pitch and yaw thrust vectoring may be eliminated and the location of the sonic plane may be further stabilized.
2014-01-01
Background In insect societies, intracolonial genetic variation is predicted to affect both colony efficiency and reproductive skew. However, because the effects of genetic variation on these two colony characteristics have been tested independently, it remains unclear whether they are affected by genetic variation independently or in a related manner. Here we test the effect of genetic variation on colony efficiency and reproductive skew in a rhinotermitid termite, Reticulitermes speratus, a species in which female-female pairs can facultatively found colonies. We established colonies using two types of female-female pairs: colonies founded by sisters (i.e., sister-pair colonies) and those founded by females from different colonies (i.e., unrelated-pair colonies). Colony growth and reproductive skew were then compared between the two types of incipient colonies. Results At 15 months after colony foundation, unrelated-pair colonies were larger than sister-pair colonies, although the caste ratio between workers and nymphs, which were alternatively differentiated from young larvae, did not differ significantly. Microsatellite DNA analyses of both founders and their parthenogenetically produced offspring indicated that, in both sister-pair and unrelated-pair colonies, there was no significant skew in the production of eggs, larvae, workers and soldiers. Nymph production, however, was significantly more skewed in the sister-pair colonies than in unrelated-pair colonies. Because nymphs can develop into winged adults (alates) or nymphoid reproductives, they have a higher chance of direct reproduction than workers in this species. Conclusions Our results support the idea that higher genetic variation among colony members could provide an increase in colony productivity, as shown in hymenopteran social insects. Moreover, this study suggests that low genetic variation (high relatedness) between founding females increases reproductive skew via one female preferentially channeling her relatives along the reproductive track. This study thus demonstrated that, in social insects, intracolonial genetic variation can simultaneously affect both colony efficiency and reproductive skew. PMID:25123355
NASA Astrophysics Data System (ADS)
Leviatan, Talma
2008-09-01
There has been a broad wave of change in tertiary calculus courses in the past decade. However, the much-needed change in tertiary pre-calculus programmesâ€”aimed at bridging the gap between high-school mathematics and tertiary mathematicsâ€”is happening at a far slower pace. Following a discussion on the nature of the gap and the objectives of a potential bridging programme, this paper aims at demonstrating that the gap can be bridged, by presenting an ongoing modular bridging programme especially designed for the diverse types of student populations in teachers training colleges. We also present here some innovative teaching and assessment methods that were judged essential for the success of these programmesâ€”focusing mainly on the "Questionnaire Based Instruction Method". Finally we suggest directions of follow up and research.
ERIC Educational Resources Information Center
West, Edith A.
1993-01-01
Offers a cultural bridge model that would enhance the health care of the American Indian population. Suggests that transcultural nursing should transcend the realm of thought and become an integrated part of daily practice. (Author)
Germ Cell Intercellular Bridges
Greenbaum, Michael P.; Iwamori, Tokuko; Buchold, Gregory M.; Matzuk, Martin M.
2011-01-01
Stable intercellular bridges are a conserved feature of gametogenesis in multicellular animals observed more than 100 years ago, but their function was unknown. Many of the components necessary for this structure have been identified through the study of cytokinesis in Drosophila; however, mammalian intercellular bridges have distinct properties from those of insects. Mammalian germ cell intercellular bridges are composed of general cytokinesis components with additional germ cell–specific factors including TEX14. TEX14 is an inactive kinase essential for the maintenance of stable intercellular bridges in gametes of both sexes but whose loss specifically impairs male meiosis. TEX14 acts to impede the terminal steps of abscission by competing for essential component CEP55, blocking its interaction in nongerm cells with ALIX and TSG101. Additionally, TEX14-interacting protein RBM44, whose localization in stabile intercellular bridges is limited to pachytene and secondary spermatocytes, may participate in processes such as RNA transport but is nonessential to the maintenance of intercellular bridge stability. PMID:21669984
Modeling absolute differences in life expectancy with a censored skew-normal regression approach.
Moser, André; Clough-Gorr, Kerri; Zwahlen, Marcel
2015-01-01
Parameter estimates from commonly used multivariable parametric survival regression models do not directly quantify differences in years of life expectancy. Gaussian linear regression models give results in terms of absolute mean differences, but are not appropriate in modeling life expectancy, because in many situations time to death has a negative skewed distribution. A regression approach using a skew-normal distribution would be an alternative to parametric survival models in the modeling of life expectancy, because parameter estimates can be interpreted in terms of survival time differences while allowing for skewness of the distribution. In this paper we show how to use the skew-normal regression so that censored and left-truncated observations are accounted for. With this we model differences in life expectancy using data from the Swiss National Cohort Study and from official life expectancy estimates and compare the results with those derived from commonly used survival regression models. We conclude that a censored skew-normal survival regression approach for left-truncated observations can be used to model differences in life expectancy across covariates of interest. PMID:26339544
Modeling absolute differences in life expectancy with a censored skew-normal regression approach
Clough-Gorr, Kerri; Zwahlen, Marcel
2015-01-01
Parameter estimates from commonly used multivariable parametric survival regression models do not directly quantify differences in years of life expectancy. Gaussian linear regression models give results in terms of absolute mean differences, but are not appropriate in modeling life expectancy, because in many situations time to death has a negative skewed distribution. A regression approach using a skew-normal distribution would be an alternative to parametric survival models in the modeling of life expectancy, because parameter estimates can be interpreted in terms of survival time differences while allowing for skewness of the distribution. In this paper we show how to use the skew-normal regression so that censored and left-truncated observations are accounted for. With this we model differences in life expectancy using data from the Swiss National Cohort Study and from official life expectancy estimates and compare the results with those derived from commonly used survival regression models. We conclude that a censored skew-normal survival regression approach for left-truncated observations can be used to model differences in life expectancy across covariates of interest. PMID:26339544
Flexible skew-symmetric shape model for shape representation, classification, and sampling.
Baloch, Sajjad H; Krim, Hamid
2007-02-01
Skewness of shape data often arises in applications (e.g., medical image analysis) and is usually overlooked in statistical shape models. In such cases, a Gaussian assumption is unrealistic and a formulation of a general shape model which accounts for skewness is in order. In this paper, we present a novel statistical method for shape modeling, which we refer to as the flexible skew-symmetric shape model (FSSM). The model is sufficiently flexible to accommodate a departure from Gaussianity of the data and is fairly general to learn a "mean shape" (template), with a potential for classification and random generation of new realizations of a given shape. Robustness to skewness results from deriving the FSSM from an extended class of flexible skew-symmetric distributions. In addition, we demonstrate that the model allows us to extract principal curves in a point cloud. The idea is to view a shape as a realization of a spatial random process and to subsequently learn a shape distribution which captures the inherent variability of realizations, provided they remain, with high probability, within a certain neighborhood range around a mean. Specifically, given shape realizations, FSSM is formulated as a joint bimodal distribution of angle and distance from the centroid of an aggregate of random points. Mean shape is recovered from the modes of the distribution, while the maximum likelihood criterion is employed for classification. PMID:17269627
Generalized Skew Coefficients of Annual Peak Flows for Rural, Unregulated Streams in West Virginia
Atkins, John T.; Wiley, Jeffrey B.; Paybins, Katherine S.
2009-01-01
Generalized skew was determined from analysis of records from 147 streamflow-gaging stations in or near West Virginia. The analysis followed guidelines established by the Interagency Advisory Committee on Water Data described in Bulletin 17B, except that stations having 50 or more years of record were used instead of stations with the less restrictive recommendation of 25 or more years of record. The generalized-skew analysis included contouring, averaging, and regression of station skews. The best method was considered the one with the smallest mean square error (MSE). MSE is defined as the following quantity summed and divided by the number of peaks: the square of the difference of an individual logarithm (base 10) of peak flow less the mean of all individual logarithms of peak flow. Contouring of station skews was the best method for determining generalized skew for West Virginia, with a MSE of about 0.2174. This MSE is an improvement over the MSE of about 0.3025 for the national map presented in Bulletin 17B.
Eggert, Anne-Katrin; Otte, Tobias; Müller, Josef K
2008-01-01
Proximate mechanisms underlying reproductive skew are obscure in many animals that breed communally. Here, we address causes of reproductive skew in brood-parasitic associations of burying beetles (Nicrophorus vespilloides). Male and female burying beetles feed and defend their larvae on buried carcasses. When several females locate the same small carcass, they engage in violent physical altercations. The subordinate then acts as an intraspecific brood parasite, laying eggs, but not providing care. The dominant female largely monopolizes access to the carcass; she alone provides parental care and her share of the brood is much larger than the subordinate's. On larger carcasses, subordinates have greater access to the carcass than on small ones, and reproductive skew is reduced. Differential fecundity, ovicide and larvicide have been suggested as causes of skew on small carcasses. Here, we report the results of the experiments pertaining to the first two of these potential mechanisms. Ovicide did not significantly contribute to reproductive skew on small carcasses, but differential fecundity did. Fecundity differences were due to dominance status, not body size per se. Fecundity differences disappeared when supplemental food was available, suggesting that reduced access to the carcass limits fecundity by causing nutritional deficiencies. Supplemental food prevented such nutritional deficiencies and allowed subordinates to produce as many eggs as dominants. Apparently, aggressive behaviour by dominants functions in the context of reproductive competition, limiting subordinate reproduction by preventing food intake on the carcass. PMID:18647719
Analysis of gamma-ray burst duration distribution using mixtures of skewed distributions
NASA Astrophysics Data System (ADS)
Tarnopolski, M.
2016-02-01
Two classes of GRBs have been confidently identified thus far and are prescribed to different physical scenarios - NS-NS or NS-BH mergers, and collapse of massive stars, for short and long GRBs, respectively. A third, intermediate in duration class, was suggested to be present in previous catalogs, such as BATSE and Swift, based on statistical tests regarding a mixture of two or three log-normal distributions of T90. However, this might possibly not be an adequate model. This paper investigates whether the distributions of log T90 from BATSE, Swift, and Fermi are described better by a mixture of skewed distributions rather than standard Gaussians. Mixtures of standard normal, skew-normal, sinh-arcsinh and alpha-skew-normal distributions are fitted using a maximum likelihood method. The preferred model is chosen based on the Akaike information criterion. It is found that mixtures of two skew-normal or two sinh-arcsinh distributions are more likely to describe the observed duration distribution of Fermi than a mixture of three standard Gaussians, and that mixtures of two sinh-arcsinh or two skew-normal distributions are models competing with the conventional three-Gaussian in the case of BATSE and Swift. Based on statistical reasoning, and it is shown that other phenomenological models may describe the observed Fermi, BATSE, and Swift duration distributions at least as well as a mixture of standard normal distributions, and the existence of a third (intermediate) class of GRBs in Fermi data is rejected.
Julià, Olga; Vidal-Mas, Jaume; Panikov, Nicolai S.; Vives-Rego, Josep
2010-01-01
We report a skew-Laplace statistical analysis of both flow cytometry scatters and cell size from microbial strains primarily grown in batch cultures, others in chemostat cultures and bacterial aquatic populations. Cytometry scatters best fit the skew-Laplace distribution while cell size as assessed by an electronic particle analyzer exhibited a moderate fitting. Unlike the cultures, the aquatic bacterial communities clearly do not fit to a skew-Laplace distribution. Due to its versatile nature, the skew-Laplace distribution approach offers an easy, efficient, and powerful tool for distribution of frequency analysis in tandem with the flow cytometric cell sorting. PMID:20592754
Julià, Olga; Vidal-Mas, Jaume; Panikov, Nicolai S; Vives-Rego, Josep
2010-01-01
We report a skew-Laplace statistical analysis of both flow cytometry scatters and cell size from microbial strains primarily grown in batch cultures, others in chemostat cultures and bacterial aquatic populations. Cytometry scatters best fit the skew-Laplace distribution while cell size as assessed by an electronic particle analyzer exhibited a moderate fitting. Unlike the cultures, the aquatic bacterial communities clearly do not fit to a skew-Laplace distribution. Due to its versatile nature, the skew-Laplace distribution approach offers an easy, efficient, and powerful tool for distribution of frequency analysis in tandem with the flow cytometric cell sorting. PMID:20592754
Kazemi, Iraj; Mahdiyeh, Zahra; Mansourian, Marjan; Park, Jongbae J
2013-07-01
Classical multivariate mixed models that acknowledge the correlation of patients through the incorporation of normal error terms are widely used in cohort studies. Violation of the normality assumption can make the statistical inference vague. In this paper, we propose a Bayesian parametric approach by relaxing this assumption and substituting some flexible distributions in fitting multivariate mixed models. This strategy allows for the skewness and the heavy tails of error-term distributions and thus makes inferences robust to the violation. This approach uses flexible skew-elliptical distributions, including skewed, fat, or thin-tailed distributions, and imposes the normal model as a special case. We use real data obtained from a prospective cohort study on the low back pain to illustrate the usefulness of our proposed approach. PMID:23609779
Evolution of Quantitative Traits under a Migration-Selection Balance: When Does Skew Matter?
Débarre, Florence; Yeaman, Sam; Guillaume, Frédéric
2015-10-01
Quantitative-genetic models of differentiation under migration-selection balance often rely on the assumption of normally distributed genotypic and phenotypic values. When a population is subdivided into demes with selection toward different local optima, migration between demes may result in asymmetric, or skewed, local distributions. Using a simplified two-habitat model, we derive formulas without a priori assuming a Gaussian distribution of genotypic values, and we find expressions that naturally incorporate higher moments, such as skew. These formulas yield predictions of the expected divergence under migration-selection balance that are more accurate than models assuming Gaussian distributions, which illustrates the importance of incorporating these higher moments to assess the response to selection in heterogeneous environments. We further show with simulations that traits with loci of large effect display the largest skew in their distribution at migration-selection balance. PMID:26656215
A METHOD TO MEASURE THE SKEW QUADUPOLE STRENGTHS IN THE SIS-18 USING TWO BPMS.
FRANCHI,A.BEIER,T.KIRK,M.MORITZ,P.RUMOLO,G.TOMAS,R.
2004-07-05
In the GSI synchrotron SIS-18 a new set of skew quadrupoles has been installed to improve the multi-turn-injection. Anew method based on the measurement of the resonance driving terms (RDT) has been proposed to cross-check the nominal values and polarities of their gradients. Once a beam is transversely kicked, it experiences oscillations whose spectrum contains both the betatron tune line and secondary lines. The amplitude of each line is proportional to the strength of the multipoles, such as skew quadrupoles and sextupoles, present in the lattice. In this paper, a recursive algorithm to derive the magnet strength from the spectral lines and the application of this method to the eight skew quadrupoles in the SIS-18 are presented.
NASA Astrophysics Data System (ADS)
Sayuri Matsumoto,; Norihide Takeyama,; Takenobu Tsuchiya,; Nobuyuki Endoh,
2010-07-01
In the image formation performance of an underwater acoustic lens, the use of geometrical skew ray analysis for usually use in optical lens design field was examined. We measured acoustic pressure fields through a single lens, from which the acoustic energy distribution was obtained by using encircled energy. On the other hand, the analyzed acoustic energy distribution was evaluated by geometrical skew ray analysis under the measurement condition including the apodization of the source and effect of water temperature. We compared the measured and analyzed convergence positions, which the diameter of 80% of total amount of acoustic energy is the minimum. Then the both convergence positions correspond. As a result, it was shown that the image performance evaluation of a wide-view acoustic lens by geometrical skew ray analysis is useful.
Perceived quality of wood images influenced by the skewness of image histogram
NASA Astrophysics Data System (ADS)
Katsura, Shigehito; Mizokami, Yoko; Yaguchi, Hirohisa
2015-08-01
The shape of image luminance histograms is related to material perception. We investigated how the luminance histogram contributed to improvements in the perceived quality of wood images by examining various natural wood and adhesive vinyl sheets with printed wood grain. In the first experiment, we visually evaluated the perceived quality of wood samples. In addition, we measured the colorimetric parameters of the wood samples and calculated statistics of image luminance. The relationship between visual evaluation scores and image statistics suggested that skewness and kurtosis affected the perceived quality of wood. In the second experiment, we evaluated the perceived quality of wood images with altered luminance skewness and kurtosis using a paired comparison method. Our result suggests that wood images are more realistic if the skewness of the luminance histogram is slightly negative.
Watermann, J.; McNamara, A.G. ); Sofko, G.J.; Koehler, J.A. )
1989-06-01
Some 7,700 radio aurora spectra obtained from a six link 50-MHz CW radar network set up on the Canadian prairies were analyzed with respect to the distributions of mean Doppler shift, spectral width and skewness. A comparison with recently published SABRE results obtained at 153 MHz shows substantial differences in the distributions which are probably due to different experimental and geophysical conditions. The spectra are mostly broad with mean Doppler shifts close to zero (type II spectra). The typical groupings of type I and type III spectra are clearly identified. All types appear to be in general much more symmetric than those recorded with SABRE, and the skewness is only weakly dependent on the sign of the mean Doppler shift. Its distribution peaks near zero and shows a weak positive correlation with the type II Doppler shifts while the mostly positive type I Doppler shifts are slightly negatively correlated with the skewness.
Modeling the effects of wave skewness and beach cusps on littoral sand transport
Haas, K.A.; Check, L.A.; Hanes, D.M.
2008-01-01
A process-based numerical modeling system is utilized for predicting littoral sand transport. The intent is to examine conditions slightly more complex than linear waves impinging upon a plane beach. Two factors that we examine are wave skewness and longshore varying bathymetry. An empirical model is used for calculating the skewed bottom wave orbital velocity. The advection of sediment due to the skewed wave velocity is larger and in the direction of the waves, opposite to the results with sinusoidal wave velocities, due to the increase in the bottom shear stress under the wave crests. The model system is also applied to bathymetry containing beach cusps. When the wave field has relatively weak longshore wave power, the currents and the littoral transport exhibit significant longshore variability, thereby altering the overall mean littoral transport.
NASA Astrophysics Data System (ADS)
Yi, Xu; Shuming, Chen; Xiangyuan, Liu
2011-09-01
We propose a hierarchical interconnection network with two-phase bufferless resonant clock distribution, which mixes the advantages of mesh and tree architectures. The problems of skew reduction and variation-tolerance in the mixed interconnection network are studied through a pipelined multiplier under a TSMC 65 nm standard CMOS process. The post-simulation results show that the hierarchical architecture reduces more than 75% and 65% of clock skew compared with pure mesh and pure H-tree networks, respectively. The maximum skew in the proposed clock distribution is less than 7 ps under imbalanced loading and PVT variations, which is no more than 1% of the clock cycle of about 760 ps.
Scaled variance, skewness, and kurtosis near the critical point of nuclear matter
NASA Astrophysics Data System (ADS)
Vovchenko, V.; Anchishkin, D. V.; Gorenstein, M. I.; Poberezhnyuk, R. V.
2015-11-01
The van der Waals (VDW) equation of state predicts the existence of a first-order liquid-gas phase transition and contains a critical point. The VDW equation with Fermi statistics is applied to a description of the nuclear matter. The nucleon number fluctuations near the critical point of nuclear matter are studied. The scaled variance, skewness, and kurtosis diverge at the critical point. It is found that the crossover region of the phase diagram is characterized by the large values of the scaled variance, the almost zero skewness, and the significantly negative kurtosis. The rich structures of the skewness and kurtosis are observed in the phase diagram in the wide region around the critical point; namely, they both may attain large positive or negative values.
Elevated Mortality among Birds in Chernobyl as Judged from Skewed Age and Sex Ratios
MÃ¸ller, Anders Pape; Bonisoli-Alquati, Andrea; Rudolfsen, Geir; Mousseau, Timothy A.
2012-01-01
Background Radiation has negative effects on survival of animals including humans, although the generality of this claim is poorly documented under low-dose field conditions. Because females may suffer disproportionately from the effects of radiation on survival due to differences in sex roles during reproduction, radiation-induced mortality may result in male-skewed adult sex ratios. Methodology/Principal Finding We estimated the effects of low-dose radiation on adult survival rates in birds by determining age ratios of adults captured in mist nets during the breeding season in relation to background radiation levels around Chernobyl and in nearby uncontaminated control areas. Age ratios were skewed towards yearlings, especially in the most contaminated areas, implying that adult survival rates were reduced in contaminated areas, and that populations in such areas could only be maintained through immigration from nearby uncontaminated areas. Differential mortality in females resulted in a strongly male-skewed sex ratio in the most contaminated areas. In addition, males sang disproportionately commonly in the most contaminated areas where the sex ratio was male skewed presumably because males had difficulty finding and acquiring mates when females were rare. The results were not caused by permanent emigration by females from the most contaminated areas because none of the recaptured birds had changed breeding site, and the proportion of individuals with morphological abnormalities did not differ significantly between the sexes for areas with normal and higher levels of contamination. Conclusions/Significance These findings are consistent with the hypothesis that the adult survival rate of female birds is particularly susceptible to the effects of low-dose radiation, resulting in male skewed sex ratios at high levels of radiation. Such skewed age ratios towards yearlings in contaminated areas are consistent with the hypothesis that an area exceeding 30,000 km2 in Chernobylâ€™s surroundings constitutes an ecological trap that causes dramatic excess mortality. PMID:22514722
Skew-Tolerant Key Distribution for Load Balancing in MapReduce
NASA Astrophysics Data System (ADS)
Son, Jihoon; Choi, Hyunsik; Chung, Yon Dohn
MapReduce is a parallel processing framework for large scale data. In the reduce phase, MapReduce employs the hash scheme in order to distribute data sharing the same key across cluster nodes. However, this approach is not robust for the skewed data distribution. In this paper, we propose a skew-tolerant key distribution method for MapReduce. The proposed method assigns keys to cluster nodes balancing their workloads. We implemented our proposed method on Hadoop. Through experiments, we evaluate the performance of the proposed method in comparison with the conventional method.
NASA Astrophysics Data System (ADS)
Singh, B.; Chakraverty, S.
1994-06-01
The first five frequencies have been determined for the transverse vibration of a rectangular or a skew plate under different boundary conditions by using boundary characteristic orthogonal polynomials in two variables. The given plate is first mapped into a square plate over which a set of orthonormal polynomials satisfying the essential boundary conditions is generated by using the Gram-Schmidt process. The Rayleigh-Ritz method is then used to determine the frequencies for all possible combination of the boundary conditions and with different skew angles. Comparison has been made with known results.
Multivariate skew- t approach to the design of accumulation risk scenarios for the flooding hazard
NASA Astrophysics Data System (ADS)
Ghizzoni, Tatiana; Roth, Giorgio; Rudari, Roberto
2010-10-01
The multivariate version of the skew- t distribution provides a powerful analytical description of the joint behavior of multivariate processes. It enjoys valuable properties: from the aptitude to model skewed as well as leptokurtic datasets to the availability of moments and likelihood analytical expressions. Moreover, it offers a wide range of extremal dependence strength, allowing for upper and lower tail dependence. The idea underneath this work is to employ the multivariate skew- t distribution to provide an estimation of the joint probability of flood events in a multi-site multi-basin approach. This constitutes the basis for the design and evaluation of flood hazard scenarios for large areas in terms of their intensity, extension and frequency, i.e. those information required by civil protection agencies to put in action mitigation strategies and by insurance companies to price the flooding risk and to evaluate portfolios. Performances of the skew- t distribution and the corresponding t copula function, introduced to represent the state of the art for multivariate simulations, are discussed with reference to the Tanaro Basin, North-western Italy. To enhance the characteristics of the correlation structure, three nested and non-nested gauging stations are selected with contributing areas from 1500 to 8000 km 2. A dataset of 76 trivariate flood events is extracted from a mean daily discharges database available for the time period from January 1995 to December 2003. Applications include the generation of multivariate skew- t and t copula samples and models' comparison through the principle of minimum cross-entropy, here revised for the application to multivariate samples. Copula and skew- t based scenario return period estimations are provided for the November 1994 flood event, i.e. the worst on record in the 1801-2001 period. Results are encouraging: the skew- t distribution seems able to describe the joint behavior, being close to the observations. Marginal distributions derived from the skew- t multivariate fit are comparable to the observed ones, and the model is also able to describe the tail behavior.
Dog Bridge, view of the deck of the bridge and ...
Dog Bridge, view of the deck of the bridge and rails looking from Linden Lane - National Park Seminary, Bounded by Capitol Beltway (I-495), Linden Lane, Woodstove Avenue, & Smith Drive, Silver Spring, Montgomery County, MD
4. VIEW OF SILVER BRIDGE (ST. MARY'S BRIDGE), CARRYING COUNTY ...
4. VIEW OF SILVER BRIDGE (ST. MARY'S BRIDGE), CARRYING COUNTY ROAD OVER SOURIS RIVER NEAR SOUTH END OF REFUGE, LOOKING NORTHEAST - Upper Souris National Wildlife Refuge Dams, Souris River Basin, Foxholm, Ward County, ND
Shoreham Railroad Bridge, Title Sheet Shoreham Railroad Bridge, Former ...
Shoreham Railroad Bridge, Title Sheet - Shoreham Railroad Bridge, Former Addison County Railroad (later, Rutland Railroad, Addison Branch), spanning Lemon Fair River above Richville Pond, west of East Shoreham Road, Shoreham, Addison County, VT
Axionometric Cutaway of Bridge Structure Shoreham Railroad Bridge, Former ...
Axionometric Cutaway of Bridge Structure - Shoreham Railroad Bridge, Former Addison County Railroad (later, Rutland Railroad, Addison Branch), spanning Lemon Fair River above Richville Pond, west of East Shoreham Road, Shoreham, Addison County, VT
West elevation of lift bridge, with Bollman Bridge in background. ...
West elevation of lift bridge, with Bollman Bridge in background. Note portion of R. Paul Smith Power Station in right background. - Potomac Edison Company, Chesapeake & Ohio Canal Bridge, Spanning C & O Canal South of U.S. 11, Williamsport, Washington County, MD
16. LOG AND PLANK BRIDGE ON ACCESS ROAD NEAR BRIDGE ...
16. LOG AND PLANK BRIDGE ON ACCESS ROAD NEAR BRIDGE SITE; SAME STRUCTURE AS SHOWN IN PHOTO #12. ZION NP NEGATIVE NO. 967 ZIO. - Zion-Mount Carmel Highway, Virgin River Bridge, Spanning North Fork of Virgin River on Zion-Mount Carmel Highway, Springdale, Washington County, UT
1. WESTERN VIEW OF BRIDGE PLAZA, SHOWING MEMORIAL BRIDGE AT ...
1. WESTERN VIEW OF BRIDGE PLAZA, SHOWING MEMORIAL BRIDGE AT LEFT AND THE ROCK CREEK AND POTOMAC PARKWAY RAMP AT RIGHT. VIEW TAKEN FROM THE REAR OF THE LINCOLN MEMORIAL. - Arlington Memorial Bridge, Boundary Channel Extension, Spanning Mount Vernon Memorial Highway & Boundary Channel, Washington, District of Columbia, DC
NASA Technical Reports Server (NTRS)
Deissler, Robert G.
1990-01-01
The variation of the velocity-derivative skewness of a Navier-Stokes flow as the Reynolds number goes toward zero is calculated numerically. The value of the skewness, which has been somewhat controversial, is shown to become small at low Reynolds numbers.
Dagne, Getachew A; Huang, Yangxin
2013-09-30
Common problems to many longitudinal HIV/AIDS, cancer, vaccine, and environmental exposure studies are the presence of a lower limit of quantification of an outcome with skewness and time-varying covariates with measurement errors. There has been relatively little work published simultaneously dealing with these features of longitudinal data. In particular, left-censored data falling below a limit of detection may sometimes have a proportion larger than expected under a usually assumed log-normal distribution. In such cases, alternative models, which can account for a high proportion of censored data, should be considered. In this article, we present an extension of the Tobit model that incorporates a mixture of true undetectable observations and those values from a skew-normal distribution for an outcome with possible left censoring and skewness, and covariates with substantial measurement error. To quantify the covariate process, we offer a flexible nonparametric mixed-effects model within the Tobit framework. A Bayesian modeling approach is used to assess the simultaneous impact of left censoring, skewness, and measurement error in covariates on inference. The proposed methods are illustrated using real data from an AIDS clinical study. . PMID:23553914
Bayesian Two-Part Tobit Models with Left-Censoring, Skewness, and Nonignorable Missingness.
Dagne, Getachew A; Huang, Yangxin
2015-01-01
In a longitudinal HIV/AIDS study with response data, observations may be missing because of patient dropouts due to drug intolerance or other problems, resulting in nonignorable missing data. In addition to nonignorable missingness, there are also problems of skewness and left-censoring in the response variable because of a lower limit of detection (LOD). There has been relatively little work published simultaneously dealing with these features of longitudinal data. In particular, one of the features may sometimes be the existence of a larger proportion of left-censored data falling below LOD than expected under a usually assumed log-normal distribution. When this happens, an alternative model that can account for a high proportion of censored data should be considered. We present an extension of the random effects Tobit model that incorporates a mixture of true undetectable observations and the values from a skew-normal distribution for an outcome with left-censoring, skewness, and nonignorable missingness. A unifying modeling approach is used to assess the impact of left-censoring, skewness, nonignorable missingness and measurement error in covariates on a Bayesian inference. The proposed methods are illustrated using real data from an AIDS clinical study. PMID:24905924
Lu, Xiaosun; Huang, Yangxin
2014-07-20
It is a common practice to analyze complex longitudinal data using nonlinear mixed-effects (NLME) models with normality assumption. The NLME models with normal distributions provide the most popular framework for modeling continuous longitudinal outcomes, assuming individuals are from a homogeneous population and relying on random-effects to accommodate inter-individual variation. However, the following two issues may standout: (i) normality assumption for model errors may cause lack of robustness and subsequently lead to invalid inference and unreasonable estimates, particularly, if the data exhibit skewness and (ii) a homogeneous population assumption may be unrealistically obscuring important features of between-subject and within-subject variations, which may result in unreliable modeling results. There has been relatively few studies concerning longitudinal data with both heterogeneity and skewness features. In the last two decades, the skew distributions have shown beneficial in dealing with asymmetric data in various applications. In this article, our objective is to address the simultaneous impact of both features arisen from longitudinal data by developing a flexible finite mixture of NLME models with skew distributions under Bayesian framework that allows estimates of both model parameters and class membership probabilities for longitudinal data. Simulation studies are conducted to assess the performance of the proposed models and methods, and a real example from an AIDS clinical trial illustrates the methodology by modeling the viral dynamics to compare potential models with different distribution specifications; the analysis results are reported. PMID:24623529
A Monte Carlo Study of Skewed Theta Distributions on DIF Indices.
ERIC Educational Resources Information Center
Monaco, Malina
The effects of skewed theta distributions on indices of differential item functioning (DIF) were studied, comparing Mantel Haenszel (N. Mantel and W. Haenszel, 1959) and DFIT (N. S. Raju, W. J. van der Linden, and P. F. Fleer) (noncompensatory DIF). The significance of the study is that in educational and psychological data, the distributions one…
The curious anomaly of skewed judgment distributions and systematic error in the wisdom of crowds.
Nash, Ulrik W
2014-01-01
Judgment distributions are often skewed and we know little about why. This paper explains the phenomenon of skewed judgment distributions by introducing the augmented quincunx (AQ) model of sequential and probabilistic cue categorization by neurons of judges. In the process of developing inferences about true values, when neurons categorize cues better than chance, and when the particular true value is extreme compared to what is typical and anchored upon, then populations of judges form skewed judgment distributions with high probability. Moreover, the collective error made by these people can be inferred from how skewed their judgment distributions are, and in what direction they tilt. This implies not just that judgment distributions are shaped by cues, but that judgment distributions are cues themselves for the wisdom of crowds. The AQ model also predicts that judgment variance correlates positively with collective error, thereby challenging what is commonly believed about how diversity and collective intelligence relate. Data from 3053 judgment surveys about US macroeconomic variables obtained from the Federal Reserve Bank of Philadelphia and the Wall Street Journal provide strong support, and implications are discussed with reference to three central ideas on collective intelligence, these being Galton's conjecture on the distribution of judgments, Muth's rational expectations hypothesis, and Page's diversity prediction theorem. PMID:25406078
Using social parasitism to test reproductive skew models in a primitively eusocial wasp.
Green, Jonathan P; Cant, Michael A; Field, Jeremy
2014-08-22
Remarkable variation exists in the distribution of reproduction (skew) among members of cooperatively breeding groups, both within and between species. Reproductive skew theory has provided an important framework for understanding this variation. In the primitively eusocial Hymenoptera, two models have been routinely tested: concessions models, which assume complete control of reproduction by a dominant individual, and tug-of-war models, which assume on-going competition among group members over reproduction. Current data provide little support for either model, but uncertainty about the ability of individuals to detect genetic relatedness and difficulties in identifying traits conferring competitive ability mean that the relative importance of concessions versus tug-of-war remains unresolved. Here, we suggest that the use of social parasitism to generate meaningful variation in key social variables represents a valuable opportunity to explore the mechanisms underpinning reproductive skew within the social Hymenoptera. We present a direct test of concessions and tug-of-war models in the paper wasp Polistes dominulus by exploiting pronounced changes in relatedness and power structures that occur following replacement of the dominant by a congeneric social parasite. Comparisons of skew in parasitized and unparasitized colonies are consistent with a tug-of-war over reproduction within P. dominulus groups, but provide no evidence for reproductive concessions. PMID:24990668
On Some Confidence Intervals for Estimating the Mean of a Skewed Population
ERIC Educational Resources Information Center
Shi, W.; Kibria, B. M. Golam
2007-01-01
A number of methods are available in the literature to measure confidence intervals. Here, confidence intervals for estimating the population mean of a skewed distribution are considered. This note proposes two alternative confidence intervals, namely, Median t and Mad t, which are simple adjustments to the Student's t confidence interval. In…
Miller, K A; Nelson, N J; Smith, H G; Moore, J A
2009-09-01
Reduced genetic diversity can result in short-term decreases in fitness and reduced adaptive potential, which may lead to an increased extinction risk. Therefore, maintaining genetic variation is important for the short- and long-term success of reintroduced populations. Here, we evaluate how founder group size and variance in male reproductive success influence the long-term maintenance of genetic diversity after reintroduction. We used microsatellite data to quantify the loss of heterozygosity and allelic diversity in the founder groups from three reintroductions of tuatara (Sphenodon), the sole living representatives of the reptilian order Rhynchocephalia. We then estimated the maintenance of genetic diversity over 400 years (approximately 10 generations) using population viability analyses. Reproduction of tuatara is highly skewed, with as few as 30% of males mating across years. Predicted losses of heterozygosity over 10 generations were low (1-14%), and populations founded with more animals retained a greater proportion of the heterozygosity and allelic diversity of their source populations and founder groups. Greater male reproductive skew led to greater predicted losses of genetic diversity over 10 generations, but only accelerated the loss of genetic diversity at small population size (<250 animals). A reduction in reproductive skew at low density may facilitate the maintenance of genetic diversity in small reintroduced populations. If reproductive skew is high and density-independent, larger founder groups could be released to achieve genetic goals for management. PMID:19732338
Skewness and Kurtosis as Applied to a Portfolio in the Korean Stock Market
NASA Astrophysics Data System (ADS)
Ahn, Tae-Sung
2009-04-01
A well diversified portfolio is critical to prudent investment in a stock market. To lessen risk in a volatile market, portfolios should minimize dispersion. This paper analyzes skewness and kurtosis of businesses listed on Korean stock markets, e.g., KOSPI and KOSDAQ. It looks at distribution using the Gauss function, and examines how mean and variance can be applied in building a portfolio.
Progress in understanding the renormalization group skewness and kappa-epsilon models
NASA Technical Reports Server (NTRS)
Smith, Leslie M.; Reynolds, W. C.
1991-01-01
The immediate goal is to understand and validate the Yakhot-Orszag model of the velocity-derivative skewness and model equation for the rate of energy dissipation epsilon. A summary of a more detailed manuscript in preparation is presented. The purpose is to clarify some limitations of the theory by careful examination of key assumptions and approximations, and thereby to encourage its improvement.
Saltzman, Wendy; Digby, Leslie J; Abbott, David H
2009-02-01
Common marmosets are cooperatively breeding monkeys that exhibit high reproductive skew: most subordinate females fail to reproduce, while others attempt to breed but produce very few surviving infants. An extensive dataset on the mechanisms limiting reproduction in laboratory-housed and free living subordinate females provides unique insights into the causes of reproductive skew. Non-breeding adult females undergo suppression of ovulation and inhibition of sexual behaviour; however, they receive little or no aggression or mating interference by dominants and do not exhibit behavioural or physiological signs of stress. Breeding subordinate females receive comparable amounts of aggression to non-breeding females but are able to conceive, gestate and lactate normally. In groups containing two breeding females,however, both dominant and subordinate breeders kill one another's infants. These findings suggest that preconception reproductive suppression is not imposed on subordinate females by dominants, at a proximate level, but is instead self-imposed by most subordinates, consistent with restraint models of reproductive skew. In contrast to restraint models, however, this self-suppression probably evolved not in response to the threat of eviction by dominant females but in response to the threat of infanticide. Thus,reproductive skew in this species appears to be generated predominantly by subordinate self-restraint, in a proximate sense, but ultimately by dominant control over subordinates' reproductive attempts. PMID:18945663
Large-scale age-dependent skewed sex ratio in a sexually dimorphic avian scavenger.
Lambertucci, Sergio A; Carrete, Martina; Donázar, José Antonio; Hiraldo, Fernando
2012-01-01
Age-dependent skewed sex ratios have been observed in bird populations, with adult males generally outnumbering females. This trend is mainly driven by higher female mortality, sometimes associated with anthropogenic factors. Despite the large amount of work on bird sex ratios, research examining the spatial stability of adult sex ratios is extremely scarce. The Andean condor (Vultur gryphus) is the only bird of prey with strong sexual dimorphism favouring males (males are 30% heavier than females). By examining data from most of its South-American range, we show that while the juvenile sex ratio is balanced, or even female-skewed, the sex ratio becomes increasing male-skewed with age, with adult males outnumbering females by >20%, and, in some cases by four times more. This result is consistent across regions and independent of the nature of field data. Reasons for this are unknown but it can be hypothesized that the progressive disappearance of females may be associated with mortality caused by anthropogenic factors. This idea is supported by the asymmetric habitat use by the two sexes, with females scavenging in more humanized areas. Whatever the cause, male-skewed adult sex ratios imply that populations of this endangered scavenger face higher risks of extinction than previously believed. PMID:23029488
ERIC Educational Resources Information Center
Mills, Candice M.; Grant, Meridith G.
2009-01-01
The current experiment examines if and when children consider the possibility of relationships skewing judgments when evaluating judgments in different contexts. Eighty-seven 6-year-olds, 8-year-olds, 10-year-olds, and adults heard stories about judges who made decisions matching or mismatching possible relationship biases (e.g. a judge choosing aâ€¦
Bayesian Comparison of GARCH Processes with Skewness Mechanism in Conditional Distributions
NASA Astrophysics Data System (ADS)
Pipien, M.
2006-11-01
The main goal of this paper is an application of Bayesian model comparison, based on the posterior probabilities and posterior odds ratios, in testing the explanatory power of a set of competing GARCH (Generalized Autoregressive Conditionally Heteroscedastic) specifications, all with asymmetric and heavy tailed conditional distributions. In building competing volatility models we consider, as an initial specification, conditionally Student-t GARCH process with unknown degrees of freedom parameter. By introducing skewness into Student-t family and incorporating the resulting class as a conditional distribution we generated various GARCH models, which compete in explaining possible asymmetry of both conditional and unconditional distribution of financial data. In order to make Student-t family skewed we consider various alternative mechanisms recently proposed in the literature. In particular, we apply the hidden truncation mechanism, an approach based on the inverse scale factors in the positive and the negative orthant, order statistics concept, Beta distribution transformation and Bernstein density transformation. Additionally, we consider GARCH process with conditional alpha -Stable distribution. Based on the daily returns of hypothetical financial time series, we discuss the results of Bayesian comparison of alternative skewing mechanisms applied in the initial Student-t GARCH framework. Additionally, we present formal Bayesian inference about conditional asymmetry of the distribution of the daily returns in all competing specifications on the basis of the skewness measure defined by Arnold and Groenveld.
The Curious Anomaly of Skewed Judgment Distributions and Systematic Error in the Wisdom of Crowds
Nash, Ulrik W.
2014-01-01
Judgment distributions are often skewed and we know little about why. This paper explains the phenomenon of skewed judgment distributions by introducing the augmented quincunx (AQ) model of sequential and probabilistic cue categorization by neurons of judges. In the process of developing inferences about true values, when neurons categorize cues better than chance, and when the particular true value is extreme compared to what is typical and anchored upon, then populations of judges form skewed judgment distributions with high probability. Moreover, the collective error made by these people can be inferred from how skewed their judgment distributions are, and in what direction they tilt. This implies not just that judgment distributions are shaped by cues, but that judgment distributions are cues themselves for the wisdom of crowds. The AQ model also predicts that judgment variance correlates positively with collective error, thereby challenging what is commonly believed about how diversity and collective intelligence relate. Data from 3053 judgment surveys about US macroeconomic variables obtained from the Federal Reserve Bank of Philadelphia and the Wall Street Journal provide strong support, and implications are discussed with reference to three central ideas on collective intelligence, these being Galton's conjecture on the distribution of judgments, Muth's rational expectations hypothesis, and Page's diversity prediction theorem. PMID:25406078
ERIC Educational Resources Information Center
Mills, Candice M.; Grant, Meridith G.
2009-01-01
The current experiment examines if and when children consider the possibility of relationships skewing judgments when evaluating judgments in different contexts. Eighty-seven 6-year-olds, 8-year-olds, 10-year-olds, and adults heard stories about judges who made decisions matching or mismatching possible relationship biases (e.g. a judge choosing a…
Bryce Canyon's Natural Bridge is technically a natural arch, similar to those in the nearby Arches National Park. Bryce Canyon is a unique sandstone formation in southern Utah. It is home to a large number of hoodoos, which are oddly shaped pillars of rock that formed due to different erosion rates...
ERIC Educational Resources Information Center
Lum, Lydia
2009-01-01
Since its inception in 2000, Pan-Asian American Community House's (PAACH's) education mission has bridged Asian-American studies to student life. PAACH initiatives have helped spread Asian-American diaspora to thousands of students at the University of Pennsylvania. They have also helped students determine for themselves what it means to be a…
ERIC Educational Resources Information Center
Lum, Lydia
2009-01-01
Since its inception in 2000, Pan-Asian American Community House's (PAACH's) education mission has bridged Asian-American studies to student life. PAACH initiatives have helped spread Asian-American diaspora to thousands of students at the University of Pennsylvania. They have also helped students determine for themselves what it means to be aâ€¦
ERIC Educational Resources Information Center
Gohdes, William
1995-01-01
Although tech prep is still in its infancy in Georgia, increasing numbers of students are entering technical institutes after having completed the secondary-level component of tech prep programs. Georgia's technical institutes must begin the process of developing bridge programs to help adult students with no tech prep experience develop academic…
ERIC Educational Resources Information Center
Bisogno, Janet; JeanPierre, Bobby
2008-01-01
The West Point Bridge Design (WPBD) building project engages students in project-based learning by giving them a real-life problem to solve. By using technology, students are able to become involved in solving problems that they normally would not encounter. Involvement with interactive websites, such as WPBD, assists students in using…
ERIC Educational Resources Information Center
Etindi, Diana
2002-01-01
Discusses how easily children accept racial differences, looking at ways that adults can work to bridge the racial gap and promote understanding (e.g., utilize natural opportunities to speak to others in order to break down natural hesitancies, join a relevant discussion group, expand one's reading material, and listen to the hearts of others, not…
NASA Astrophysics Data System (ADS)
Muhammad, Sadiq; Tavakoli, Armin; Kurant, Maciej; Paw?owski, Marcin; ?ukowski, Marek; Bourennane, Mohamed
2014-04-01
Quantum methods allow us to reduce communication complexity of some computational tasks, with several separated partners, beyond classical constraints. Nevertheless, experimental demonstrations of this have thus far been limited to some abstract problems, far away from real-life tasks. We show here, and demonstrate experimentally, that the power of reduction of communication complexity can be harnessed to gain an advantage in a famous, immensely popular, card game—bridge. The essence of a winning strategy in bridge is efficient communication between the partners. The rules of the game allow only a specific form of communication, of very low complexity (effectively, one has strong limitations on the number of exchanged bits). Surprisingly, our quantum technique does not violate the existing rules of the game (as there is no increase in information flow). We show that our quantum bridge auction corresponds to a biased nonlocal Clauser-Horne-Shimony-Holt game, which is equivalent to a 2?1 quantum random access code. Thus, our experiment is also a realization of such protocols. However, this correspondence is not complete, which enables the bridge players to have efficient strategies regardless of the quality of their detectors.
ERIC Educational Resources Information Center
Roy, Michael; Doss, Laurie K.
2007-01-01
The Building Migratory Bridges (BOMB) program--a collaboration between the Marvel wood School and Audubon Sharon in Connecticut and Conservation Research Education Action (CR EA), a U.S. not-for-profit in Panama--uses nontropical migratory bird research in the United States and Panama to demonstrate how negative environmental impacts in one…
ERIC Educational Resources Information Center
Leviatan, Talma
2008-01-01
There has been a broad wave of change in tertiary calculus courses in the past decade. However, the much-needed change in tertiary pre-calculus programmes--aimed at bridging the gap between high-school mathematics and tertiary mathematics--is happening at a far slower pace. Following a discussion on the nature of the gap and the objectives of aâ€¦
ERIC Educational Resources Information Center
Bohnen, Elizabeth; Klie, Judy
This report describes BRIDGES, an employment equity special measures training program developed by the City of Toronto (Ontario, Canada). It was designed to help women employees move from their traditional jobs into trades, technical or operation (TTO) jobs within their own organization. The program is a combination of classroom sessions, shop…
ERIC Educational Resources Information Center
Roy, Michael; Doss, Laurie K.
2007-01-01
The Building Migratory Bridges (BOMB) program--a collaboration between the Marvel wood School and Audubon Sharon in Connecticut and Conservation Research Education Action (CR EA), a U.S. not-for-profit in Panama--uses nontropical migratory bird research in the United States and Panama to demonstrate how negative environmental impacts in oneâ€¦
ERIC Educational Resources Information Center
Salter, Colin
2009-01-01
The political context of the conversion of the Historic Tramway Bridge, adjacent to Sandon Point in Bulli (NSW, Australia), and how this was exploited to serve predetermined ends, illustrates that technologies can be designed to have particular social (and political) effects. Through reflection on this relatively small engineering project, this…
ERIC Educational Resources Information Center
Netzer, Greg
1995-01-01
Discusses a model water quality monitoring project, Project Bridge, established to train minority girls about to enter eighth grade in scientific procedures followed by hands-on experimentation. Students spent a week monitoring water in an urban stream and analyzing results. (LZ)
ERIC Educational Resources Information Center
Johnson, Susan Moore; Kardos, Susan M.
2005-01-01
The lack of instructional continuity in schools negates every effort of principals to provide an environment where all students would be successful. One solution could be to bridge the gap between the professional knowledge and skills of experienced teachers and the energy and fresh ideas of new recruits so that the latter are provided support…
ERIC Educational Resources Information Center
Kroto, Joseph J.
1988-01-01
Describes interdisciplinary activities with real-world applications ranging from science to mathematics to technology. Cites the study and construction of model bridges as a way for students to learn about engineering concepts and some of their relationships. States that the exercise enhanced teacher cooperation between the different fields. (RT)
ERIC Educational Resources Information Center
Bisogno, Janet; JeanPierre, Bobby
2008-01-01
The West Point Bridge Design (WPBD) building project engages students in project-based learning by giving them a real-life problem to solve. By using technology, students are able to become involved in solving problems that they normally would not encounter. Involvement with interactive websites, such as WPBD, assists students in usingâ€¦
ERIC Educational Resources Information Center
Johnson, Susan Moore; Kardos, Susan M.
2005-01-01
The lack of instructional continuity in schools negates every effort of principals to provide an environment where all students would be successful. One solution could be to bridge the gap between the professional knowledge and skills of experienced teachers and the energy and fresh ideas of new recruits so that the latter are provided supportâ€¦
BUILDING "BRIDGES" WITH QUALITY ASSURANCE
The papr describes how, rather than building "bridges" across centuries, quality assurance (QA) personnel have the opportunity to build bridges across technical disciplines, between public and private organizations, and between different QA groups. As reviewers and auditors of a...
Suicide by jumping from bridges.
Lester, David
2005-06-01
The Sunshine Skyway Bridge in St. Petersburg, Florida, has crisis emergency telephones and a police presence. Although the number of suicides from the bridge has declined, it is too soon to test the statistical significance of the decline. PMID:16060421
Reynolds, Pamela L.; Bruno, John F.
2012-01-01
Widespread overharvesting of top consumers of the world’s ecosystems has “skewed” food webs, in terms of biomass and species richness, towards a generally greater domination at lower trophic levels. This skewing is exacerbated in locations where exotic species are predominantly low-trophic level consumers such as benthic macrophytes, detritivores, and filter feeders. However, in some systems where numerous exotic predators have been added, sometimes purposefully as in many freshwater systems, food webs are skewed in the opposite direction toward consumer dominance. Little is known about how such modifications to food web topology, e.g., changes in the ratio of predator to prey species richness, affect ecosystem functioning. We experimentally measured the effects of trophic skew on production in an estuarine food web by manipulating ratios of species richness across three trophic levels in experimental mesocosms. After 24 days, increasing macroalgal richness promoted both plant biomass and grazer abundance, although the positive effect on plant biomass disappeared in the presence of grazers. The strongest trophic cascade on the experimentally stocked macroalgae emerged in communities with a greater ratio of prey to predator richness (bottom-rich food webs), while stronger cascades on the accumulation of naturally colonizing algae (primarily microalgae with some early successional macroalgae that recruited and grew in the mesocosms) generally emerged in communities with greater predator to prey richness (the more top-rich food webs). These results suggest that trophic skewing of species richness and overall changes in food web topology can influence marine community structure and food web dynamics in complex ways, emphasizing the need for multitrophic approaches to understand the consequences of marine extinctions and invasions. PMID:22693549
This photograph shows Lowe's Bridge off ME-15 in Guilford, Maine, spanning the Piscataquis River. USGS gaging station 01031500 is located on the downstream side of the bridge. The original bridge, built in 1857, washed away in the flood of 1987, and was rebuilt on the original abutments in 1990....
Electrical Actuation Technology Bridging
NASA Technical Reports Server (NTRS)
Hammond, Monica (Compiler); Sharkey, John (Compiler)
1993-01-01
This document contains the proceedings of the NASA Electrical Actuation Technology Bridging (ELA-TB) Workshop held in Huntsville, Alabama, September 29-October 1, 1992. The workshop was sponsored by the NASA Office of Space Systems Development and Marshall Space Flight Center (MSFC). The workshop addressed key technologies bridging the entire field of electrical actuation including systems methodology, control electronics, power source systems, reliability, maintainability, and vehicle health management with special emphasis on thrust vector control (TVC) applications on NASA launch vehicles. Speakers were drawn primarily from industry with participation from universities and government. In addition, prototype hardware demonstrations were held at the MSFC Propulsion Laboratory each afternoon. Splinter sessions held on the final day afforded the opportunity to discuss key issues and to provide overall recommendations. Presentations are included in this document.
NASA Astrophysics Data System (ADS)
Sanz, A.; Perales, J. M.
1989-10-01
The formation of a liquid bridge is obviously the first step in the experimentation of the different aspects of the liquid bridge dynamics. Among the several candidate procedures of formation, the so-called 'cylindrical formation' has been selected; liquid is injected inside of the bridge through one of the supporting disks whereas simultaneously one of the disks is moved apart from the other at the proper speed to keep the volume of liquid inside the column, the same as that of the cylinder limited by both disks. Besides its own fluid mechanics interest (interplay between a jet and an interface), the results of this study would be very useful for experimenters in order to reduce the experiment preparation phase, as the total time allowed is scarce in most often used reduced gravity facilities (parabolic flights, sounding rockets and so on). A simplified theoretical model of the problem is presented which is valid in a flow regime limited in range by the Reynolds number of the injection jet. The existence of contiguous regimes and the influence of Ohnesorge number are suggested. This characterization has been deduced from the experiments performed by using the neutral buoyancy technique on earth and helps to explain the behavior observed during experiments performed on microgravity conditions onboard sounding rockets (TEXUS).
Field observations of linear transition ripple migration and wave orbital velocity skewness
NASA Astrophysics Data System (ADS)
Crawford, Anna Morwenna
A new laser illuminated underwater video system has been developed for simultaneously imaging sediment suspension and monitoring bedforms under waves in the nearshore. The system consists of a video camera and diode laser- generated light plane which illuminates suspended material in section and profiles the bed where it intersects the bottom. The system was deployed in the field along with acoustic devices for measurement of nearbed flow velocities and independent bedform observation at Queensland Beach, Nova Scotia. Observations were made in 3 to 4 m water depth of linear transition ripple geometry and migration using the laser- video system and acoustic scanning sensors during both the growth and decay phases of an autumn storm event. Linear transition ripples are long crested, low steepness bedforms in the anorbital ripple class. The transition ripples occurred under relatively high energy waves, just below the flatbed threshold, and had wavelengths of 8.5 +/- 0.5 cm and heights of 0.3 +/- 0.1 cm. The maximum observed migration rate was 0.7 cm/min. Migration was offshore during storm growth, and onshore during storm decay. The observed ripple migration rates were highly correlated with nearbed wave orbital velocity skewness (r2 > 0.7). During storm growth, the incident wave spectrum was bimodal and the orbital velocity skewness was negative. During storm decay, the wave spectrum was unimodal and the velocity skewness was positive. Bispectral analysis shows that the main contribution to negative velocity skewness during storm growth arose from a difference interaction between the two principal components (sea and swell) of the bimodal wave spectrum. Positive velocity skewness during storm decay was due to self-self interaction of the narrowband swell. These observations are shown to be consistent with a second-order wave theory. These observations support a skewness, or u3 , dependence of transition ripple migration on nearbed orbital velocity in a field setting and provide a demonstration of storm modulated off- and on-shore directed ripple migration, thus suggesting a mechanism for the reversible sediment transport cycle during storms.
NASA Astrophysics Data System (ADS)
Boswell, S. M.; Zheng, L.; Gordon, R. G.; Dyment, J.
2010-12-01
In past work, reliable paleomagnetic poles have been determined from skewness data by solving for a single additional adjustable parameter, anomalous skewness, assumed to be independent of spreading rate [Petronotis et al. 1992, 1994; Petronotis & Gordon 1999]. Nonetheless, analysis of anomalies in several ocean basins indicate that anomalous skewness depends on spreading rate for spreading half rates less than ?50 mm/yr [Roest et al., 1992; Dyment et al. 1994]. To facilitate investigation of the influence of spreading-rate dependent anomalous skewness on the determination of paleomagnetic poles determined from skewness, we build on the model for marine magnetic anomalies due to seafloor spreading of Dyment and Arkani-Hamed [1995]. We use this model to estimate anomalous skewness as a function of spreading rate for many anomalies. Synthetic magnetic anomaly profiles for oceanic lithosphere with sloping curving reversal boundaries were produced by forward modeling. Anomalous skewness values for chrons 25n to 33r were visually determined at various spreading rates using two approaches: balancing the shoulders of an anomaly corresponding to a single chron and best matching an anomaly corresponding to a single chron to a synthetic anomaly determined assuming vertical reversal boundaries. The new results may facilitate the determination of paleomagnetic poles from less widely distributed crossings of a magnetic anomaly than were used before. Further implications for determination of paleomagnetic poles for the Pacific plate will be discussed.
Tang, An-Min; Tang, Nian-Sheng
2015-02-28
We propose a semiparametric multivariate skew-normal joint model for multivariate longitudinal and multivariate survival data. One main feature of the posited model is that we relax the commonly used normality assumption for random effects and within-subject error by using a centered Dirichlet process prior to specify the random effects distribution and using a multivariate skew-normal distribution to specify the within-subject error distribution and model trajectory functions of longitudinal responses semiparametrically. A Bayesian approach is proposed to simultaneously obtain Bayesian estimates of unknown parameters, random effects and nonparametric functions by combining the Gibbs sampler and the Metropolis-Hastings algorithm. Particularly, a Bayesian local influence approach is developed to assess the effect of minor perturbations to within-subject measurement error and random effects. Several simulation studies and an example are presented to illustrate the proposed methodologies. PMID:25404574
Optimization Of Mean-Semivariance-Skewness Portfolio Selection Model In Fuzzy Random Environment
NASA Astrophysics Data System (ADS)
Chatterjee, Amitava; Bhattacharyya, Rupak; Mukherjee, Supratim; Kar, Samarjit
2010-10-01
The purpose of the paper is to construct a mean-semivariance-skewness portfolio selection model in fuzzy random environment. The objective is to maximize the skewness with predefined maximum risk tolerance and minimum expected return. Here the security returns in the objectives and constraints are assumed to be fuzzy random variables in nature and then the vagueness of the fuzzy random variables in the objectives and constraints are transformed into fuzzy variables which are similar to trapezoidal numbers. The newly formed fuzzy model is then converted into a deterministic optimization model. The feasibility and effectiveness of the proposed method is verified by numerical example extracted from Bombay Stock Exchange (BSE). The exact parameters of fuzzy membership function and probability density function are obtained through fuzzy random simulating the past dates.
Bauke, W.; Clark, D.A.; Trujillo, P.B.
1985-01-01
Optical Tooling evolved from traditional surveying, and both technologies are sometimes used interchangeably in large industrial installations, since the instruments and their specialized adapters and supports complement each other well. A unique marriage of both technologies was accomplished in a novel application at LAMPF, the Los Alamos Meson Physics Facility. LAMPF consists of a linear accelerator with multiple target systems, one of which had to be altered to accommodate a new beamline for a neutrino experiment. The new line was to be installed into a crowded beam tunnel and had to be skewed and tilted in compound angles to avoid existing equipment. In this paper we describe how Optical Tooling was used in conjunction with simple alignment and reference fixtures to set fiducials on the magnets and other mechanical components of the beamline, and how theodolites and sight levels were then adapted to align these components along the calculated skew planes. Design tolerances are compared with measured alignment results.
Research on the Multi-variable Optimization of Forward-skewed Blade
NASA Astrophysics Data System (ADS)
Yang, Bo; Gu, Chuan Gang
2011-12-01
This is a study of the multi-variable optimization of the forward-skewed blade by means of the Genetic Algorithms combined with an improved Hierarchical Fair Competition model. In this optimization scheme, the Bezier curves were used to describe the airfoil profiles, numerical simulations were adopted to estimate the aerodynamic performance of the axial-flow machine and a specific fitness function was put forwards to evaluate the fitness level of every individual. In order to testify the optimization algorithms and to study the effects of the forward-skewed blades on the fan performance, a series of comparative experiments and calculations were carried out to illustrate the performance difference between the optimized and the other three fans.
Maneuver planning of a rigid spacecraft with two skew control moment gyros
NASA Astrophysics Data System (ADS)
Gui, Haichao; Jin, Lei; Xu, Shijie
2014-11-01
The attitude maneuver planning of a rigid spacecraft using two skew single-gimbal control moment gyros (CMGs) is investigated. First, two types of restrictions are enforced on the gimbal motions of two skew CMGs, with each restriction yielding continuous control torque along a principal axis of the spacecraft. Then, it is proved that any axis fixed to the spacecraft can be pointed along an arbitrary inertial direction by at most two sequent rotations around the two actuated axes. Given this fact, a two-step eigenaxis rotation strategy, executing by the two single-axis torques respectively, is designed to point a given body-fixed axis along a desired direction. Furthermore, a three-step eigenaxis rotation strategy is constructed to achieve an arbitrary rest-to-rest attitude maneuver. The rotation angles required for the single-axis pointing and arbitrary attitude maneuver schemes are all analytically solved. Numerical examples are presented to demonstrate the effectiveness of the proposed algorithms.
Oduro, Kwadwo A; Liu, Fang; Tan, Qing; Kim, Chan-Kyu; Lubman, Olga; Fremont, Daved; Mills, Jason C; Choi, Kyunghee
2012-09-13
Skewing toward myeloid cell production is often observed in chronic inflammation and autoimmune diseases. Herein, we determined whether persistent myeloid activation and proinflammatory output occurring in pathologic conditions is at the level of hematopoietic stem and primitive progenitor cells (HSPPCs). By using a mouse arthritis model, we found that even though HSPPCs in arthritis still retained the capacity to differentiate into different lineages, they acquired enhanced in vitro and in vivo propensity in a disease-dependent manner to generate myeloid cells, the key perpetrators of tissue damage in arthritis. This myeloid skewing was cell intrinsic, as arthritic HSPPCs up-regulate myeloid-specific transcripts including S100a8. Exogenous S100a8 promoted myeloid cell output from wild-type HSPPCs, suggesting mechanistic involvement of this gene in the myeloid priming that occurs in arthritic HSPPCs. Therefore, our results indicate that in arthritic mice, HSPPCs adopt a pathologic state that favors disease persistence. PMID:22855602
Commutative n-ary superalgebras with an invariant skew-symmetric form
NASA Astrophysics Data System (ADS)
Vishnyakova, E. G.
2015-12-01
We study n-ary commutative superalgebras and L?-algebras that possess a skew-symmetric invariant form, using the derived bracket formalism. This class of superalgebras includes for instance Lie algebras and their n-ary generalizations, commutative associative and Jordan algebras with an invariant form. We give a classification of anti-commutative m-dimensional (m - 3) -ary algebras with an invariant form, and a classification of real simple m-dimensional Lie (m - 3) -algebras with a positive definite invariant form up to isometry. Furthermore, we develop the Hodge Theory for L?-algebras with a symmetric invariant form, and we describe quasi-Frobenius structures on skew-symmetric n-ary algebras.
Geometrically nonlinear static and dynamic analysis of functionally graded skew plates
NASA Astrophysics Data System (ADS)
Upadhyay, A. K.; Shukla, K. K.
2013-08-01
The present paper deals with nonlinear static and dynamic behavior of functionally graded skew plates. The equations of motion are derived using higher order shear deformation theory in conjunction with von-Karman's nonlinear kinematics. The physical domain is mapped into computational domain using linear mapping and chain rule of differentiation. The spatial and temporal discretization is based on fast converging finite double Chebyshev series and Houbolt's method. Quadratic extrapolation technique is employed to linearize the governing nonlinear equations. The spatial and temporal convergence and validation studies have been carried out to establish the efficacy of the present solution methodology. In case of dynamic analysis, the results are obtained for uniform step, sine, half sine, triangular and exponential type of loadings. The effect of volume fraction index, skew angle and boundary conditions on nonlinear displacement and moment response are presented.
Muon Tracking Studies in a Skew Parametric Resonance Ionization Cooling Channel
Sy, Amy; Afanaciev, Andre; Derbenev, Yaroslav S.; Johnson, Rolland; Morozov, Vasiliy
2015-09-01
Skew Parametric-resonance Ionization Cooling (SPIC) is an extension of the Parametric-resonance Ionization Cooling (PIC) framework that has previously been explored as the final 6D cooling stage of a high-luminosity muon collider. The addition of skew quadrupoles to the PIC magnetic focusing channel induces coupled dynamic behavior of the beam that is radially periodic. The periodicity of the radial motion allows for the avoidance of unwanted resonances in the horizontal and vertical transverse planes, while still providing periodic locations at which ionization cooling components can be implemented. A first practical implementation of the magnetic field components required in the SPIC channel is modeled in MADX. Dynamic features of the coupled correlated optics with and without induced parametric resonance are presented and discussed.
Olfactory learning skews mushroom body output pathways to steer behavioral choice in Drosophila.
Owald, David; Waddell, Scott
2015-12-01
Learning permits animals to attach meaning and context to sensory stimuli. How this information is coded in neural networks in the brain, and appropriately retrieved and utilized to guide behavior, is poorly understood. In the fruit fly olfactory memories of particular value are represented within sparse populations of odor-activated Kenyon cells (KCs) in the mushroom body ensemble. During learning reinforcing dopaminergic neurons skew the mushroom body network by driving zonally restricted plasticity at synaptic junctions between the KCs and subsets of the overall small collection of mushroom body output neurons. Reactivation of this skewed KC-output neuron network retrieves memory of odor valence and guides appropriate approach or avoidance behavior. PMID:26496148
Skew-Quad Parametric-Resonance Ionization Cooling: Theory and Modeling
Afanaciev, Andre; Derbenev, Yaroslav S.; Morozov, Vasiliy; Sy, Amy; Johnson, Rolland P.
2015-09-01
Muon beam ionization cooling is a key component for the next generation of high-luminosity muon colliders. To reach adequately high luminosity without excessively large muon intensities, it was proposed previously to combine ionization cooling with techniques using a parametric resonance (PIC). Practical implementation of PIC proposal is a subject of this report. We show that an addition of skew quadrupoles to a planar PIC channel gives enough flexibility in the design to avoid unwanted resonances, while meeting the requirements of radially-periodic beam focusing at ionization-cooling plates, large dynamic aperture and an oscillating dispersion needed for aberration corrections. Theoretical arguments are corroborated with models and a detailed numerical analysis, providing step-by-step guidance for the design of Skew-quad PIC (SPIC) beamline.
Permanent Magnet Skew Quadrupoles for the Low Emittance LER Lattice of PEP-II
Decker, F.-J.; Anderson, S.; Kharakh, D.; Sullivan, M.; /SLAC
2011-07-05
The vertical emittance of the low energy ring (LER) in the PEP-II B-Factory was reduced by using skew quadrupoles consisting of permanent magnet material. The advantages over electric quadrupoles or rotating existing normal quadrupoles are discussed. To assure a high field quality, a Biot-Savart calculation was used to cancel the natural 12-pole component by using different size poles over a few layers. A magnetic measurement confirmed the high quality of the magnets. After installation and adjusting the original electric 12 skew and 16 normal quadrupoles the emittance contribution from the region close to the interaction point, which was the biggest part in the original design, was considerably reduced. To strengthen the vertical behavior of the LER beam, a low emittance lattice was developed. It lowered the original vertical design emittance from 0.54 nm-rad to 0.034 nm-rad. In order to achieve this, additional skew quadrupoles were required to bring the coupling correction out of the arcs and closer to the detector solenoid in the straight (Fig. 1). It is important, together with low vertical dispersion, that the low vertical emittance is not coupled into the horizontal, which is what we get if the coupling correction continues into the arcs. Further details of the lattice work is described in another paper; here we concentrate on the development of the permanent skew (PSK) quadrupole solution. Besides the permanent magnets there are two other possibilities, using electric magnets or rotating normal quadrupoles. Electric magnets would have required much more additional equipment like magnets stands, power supply, and new vacuum chamber sections. Rotating existing quadrupoles was also not feasible since they are mostly mounted together with a bending magnet on the same support girder.
Skewness-induced asymmetric modulation of small-scale turbulence by large-scale structures
NASA Astrophysics Data System (ADS)
Agostini, Lionel; Leschziner, Michael; Gaitonde, Datta
2016-01-01
Several recent studies discuss of role of skewness of the turbulent velocity fluctuations in near-wall shear layers, in the context of quantifying the correlation between large-scale motions and amplitude variations of small-scale fluctuationsâ€”referred to as "modulation." The present study is based on the premise that the skewness of the small-scale fluctuations should be accounted for explicitly in the process of defining their envelope, which characterizes their amplitude variations. This leads to the notion of two envelopes, one for positive and the other for negative small-scale fluctuations, and hence also to two corresponding correlation coefficients. Justification for this concept is provided first by an examination of a high-frequency synthetic signal subjected to realistic skewness-inducing modulation. A new formalism is provided for deriving the two envelopes, and its fidelity is demonstrated for the synthetic test case. The method is then applied to a channel flow at a friction Reynolds number of 4200, for which direct numerical simulation (DNS) data are available. The large-scale and small-scale fields are separated by the empirical mode decomposition method, and the modulation of the small-scale fluctuations by the large scales is examined. Separate maps of the correlation coefficient and of two-point correlations, the latter linking the large-scale motions and the envelopes of the small-scale motions, are derived for the two envelopes pertaining to positive and negative small-scale fluctuations, and these demonstrate a significant sensitivity to the envelope-definition process, especially close to the wall where the skewness of the small-scale fluctuations is the dominant contributor to the total value.
Measuring skewness of red blood cell deformability distribution by laser ektacytometry
Nikitin, S Yu; Priezzhev, A V; Lugovtsov, A E; Ustinov, V D
2014-08-31
An algorithm is proposed for measuring the parameters of red blood cell deformability distribution based on laser diffractometry of red blood cells in shear flow (ektacytometry). The algorithm is tested on specially prepared samples of rat blood. In these experiments we succeeded in measuring the mean deformability, deformability variance and skewness of red blood cell deformability distribution with errors of 10%, 15% and 35%, respectively. (laser biophotonics)
Quantum integrable systems, non-skew-symmetric r-matrices and algebraic Bethe ansatz
Skrypnyk, T.
2007-02-15
We prove the integrability of the general quantum Hamiltonian systems governed by an arbitrary non-skew-symmetric, so(3)-valued, nondynamical classical r-matrix with spectral parameters. We consider the most interesting example of these quantum integrable systems, namely, the so(3) 'generalized Gaudin systems' in detail. In the case of an arbitrary r-matrix which is 'diagonal' in the sl(2) basis we calculate the spectrum and the eigenvalues of the corresponding Hamiltonians using the algebraic Bethe ansatz technique.
Townsend, Andrea K.; Clark, Anne B.; McGowan, Kevin J.; Lovette, Irby J.
2009-01-01
Understanding the benefits of cooperative breeding for group members of different social and demographic classes requires knowledge of their reproductive partitioning and genetic relatedness. From 2004-2007, we examined parentage as a function of relatedness and social interactions among members of 21 American crow (Corvus brachyrhynchos) family groups. Paired female breeders monopolized maternity of all offspring in their broods, whereas paired male breeders sired 82.7% of offspring, within-group auxiliary males sired 6.9% of offspring, and extragroup males sired 10.4% of offspring. Although adult females had fewer opportunities for direct reproduction as auxiliaries than males, they appeared to have earlier opportunities for independent breeding. These different opportunities for direct reproduction probably contributed to the male biased adult auxiliary sex ratio. Patterns of reproductive partitioning and conflict among males were most consistent with a synthetic reproductive skew model, in which auxiliaries struggled with breeders for a limited reproductive share, beyond which breeders could evict them. Counter to a frequent assumption of reproductive skew models, female breeders appeared to influence paternity, although their interests might have agreed with the interests of their paired males. Unusual among cooperative breeders, close inbreeding and incest occurred in this population. Incest avoidance between potential breeders did not significantly affect reproductive skew. PMID:20126287
The equilibrium allele frequency distribution for a population with reproductive skew.
Der, Ricky; Plotkin, Joshua B
2014-04-01
We study the population genetics of two neutral alleles under reversible mutation in a model that features a skewed offspring distribution, called the ?-Fleming-Viot process. We describe the shape of the equilibrium allele frequency distribution as a function of the model parameters. We show that the mutation rates can be uniquely identified from this equilibrium distribution, but the form of the offspring distribution cannot itself always be so identified. We introduce an estimator for the mutation rate that is consistent, independent of the form of reproductive skew. We also introduce a two-allele infinite-sites version of the ?-Fleming-Viot process, and we use it to study how reproductive skew influences standing genetic diversity in a population. We derive asymptotic formulas for the expected number of segregating sites as a function of sample size and offspring distribution. We find that the Wright-Fisher model minimizes the equilibrium genetic diversity, for a given mutation rate and variance effective population size, compared to all other ?-processes. PMID:24473932
A Bayesian estimate of the concordance correlation coefficient with skewed data.
Feng, Dai; Baumgartner, Richard; Svetnik, Vladimir
2015-01-01
Concordance correlation coefficient (CCC) is one of the most popular scaled indices used to evaluate agreement. Most commonly, it is used under the assumption that data is normally distributed. This assumption, however, does not apply to skewed data sets. While methods for the estimation of the CCC of skewed data sets have been introduced and studied, the Bayesian approach and its comparison with the previous methods has been lacking. In this study, we propose a Bayesian method for the estimation of the CCC of skewed data sets and compare it with the best method previously investigated. The proposed method has certain advantages. It tends to outperform the best method studied before when the variation of the data is mainly from the random subject effect instead of error. Furthermore, it allows for greater flexibility in application by enabling incorporation of missing data, confounding covariates, and replications, which was not considered previously. The superiority of this new approach is demonstrated using simulation as well as real-life biomarker data sets used in an electroencephalography clinical study. The implementation of the Bayesian method is accessible through the Comprehensive R Archive Network. PMID:26033433
Huang, Yangxin; Dagne, Getachew A; Zhou, Shumin; Wang, Zhongjun
2015-12-01
Studies of human immunodeficiency virus dynamics in acquired immuno deficiency syndrome (AIDS) research are very important in evaluating the effectiveness of antiretroviral (ARV) therapies. The potency of ARV agents in AIDS clinical trials can be assessed on the basis of a viral response such as viral decay rate or viral load change in plasma. Following ARV treatment, the profile of each subject's viral load tends to follow a 'broken stick'-like dynamic trajectory, indicating multiple phases of decline and increase in viral loads. Such multiple-phases (change-points) can be described by a random change-point model with random subject-specific parameters. One usually assumes a normal distribution for model error. However, this assumption may be unrealistic, obscuring important features of within- and among-subject variations. In this article, we propose piecewise linear mixed-effects models with skew-elliptical distributions to describe the time trend of a response variable under a Bayesian framework. This methodology can be widely applied to real problems for longitudinal studies. A real data analysis, using viral load data from an AIDS study, is carried out to illustrate the proposed method by comparing various candidate models. Biologically important findings are reported, and these findings also suggest that it is very important to assume a model with skew distribution in order to achieve reliable results, in particular, when the data exhibit skewness. PMID:22045781
Townsend, Andrea K; Clark, Anne B; McGowan, Kevin J; Lovette, Irby J
2009-02-01
Understanding the benefits of cooperative breeding for group members of different social and demographic classes requires knowledge of their reproductive partitioning and genetic relatedness. From 2004-2007, we examined parentage as a function of relatedness and social interactions among members of 21 American crow (Corvus brachyrhynchos) family groups. Paired female breeders monopolized maternity of all offspring in their broods, whereas paired male breeders sired 82.7% of offspring, within-group auxiliary males sired 6.9% of offspring, and extragroup males sired 10.4% of offspring. Although adult females had fewer opportunities for direct reproduction as auxiliaries than males, they appeared to have earlier opportunities for independent breeding. These different opportunities for direct reproduction probably contributed to the male biased adult auxiliary sex ratio. Patterns of reproductive partitioning and conflict among males were most consistent with a synthetic reproductive skew model, in which auxiliaries struggled with breeders for a limited reproductive share, beyond which breeders could evict them. Counter to a frequent assumption of reproductive skew models, female breeders appeared to influence paternity, although their interests might have agreed with the interests of their paired males. Unusual among cooperative breeders, close inbreeding and incest occurred in this population. Incest avoidance between potential breeders did not significantly affect reproductive skew. PMID:20126287
NASA Astrophysics Data System (ADS)
Aminian, Manuchehr; Bernardi, Francesca; Camassa, Roberto; McLaughlin, Richard M.
2015-10-01
We study the role geometry plays in the emergence of asymmetries in diffusing passive scalars advected by pressure-driven flows in ducts and pipes of different aspect ratios. We uncover nonintuitive, multi-time-scale behavior gauged by a new statistic, which we term "geometric skewness" SG, which measures instantaneously forming asymmetries at short times due to flow geometry. This signature distinguishes elliptical pipes of any aspect ratio, for which SG=0 , from rectangular ducts whose SG is generically nonzero, and, interestingly, shows that a special duct of aspect ratio ?0.533 35 behaves like a circular pipe as its geometric skewness vanishes. Using a combination of exact solutions, novel short-time asymptotics, and Monte Carlo simulations, we establish the relevant time scales for plateaus and extrema in the evolution of the skewness and kurtosis for our class of geometries. For ducts limiting to channel geometries, we present new exact, single-series formulas for the first four moments on slices used to benchmark Monte Carlo simulations.
Free vibration of composite skewed cylindrical shell panel by finite element method
NASA Astrophysics Data System (ADS)
Haldar, Salil
2008-03-01
In this paper a composite triangular shallow shell element has been used for free vibration analysis of laminated composite skewed cylindrical shell panels. In the present element first-order shear deformation theory has been incorporated by taking transverse displacement and bending rotations as independent field variables. The interpolation function used to approximate transverse displacement is one order higher than for bending rotations. This has made the element free from locking in shear. Two types of mass lumping schemes have been recommended. In one of the mass lumping scheme the effect of rotary inertia has been incorporated in the element formulations. Free vibration of skewed composite cylindrical shell panels having different thickness to radius ratios ( h/R=0.01-0.2), length to radius ratios ( L/R), number of layers and fiber orientation angles have been analyzed following the shallow shell method. The results for few examples obtained in the present analysis have compared with the published results. Some new results of composite skewed cylindrical shell panels have been presented which are expected to be useful to future research in this direction.
Reproductive skew drives patterns of sexual dimorphism in sponge-dwelling snapping shrimps.
Chak, Solomon Tin Chi; Duffy, J Emmett; Rubenstein, Dustin R
2015-06-22
Sexual dimorphism is typically a result of strong sexual selection on male traits used in male-male competition and subsequent female choice. However, in social species where reproduction is monopolized by one or a few individuals in a group, selection on secondary sexual characteristics may be strong in both sexes. Indeed, sexual dimorphism is reduced in many cooperatively breeding vertebrates and eusocial insects with totipotent workers, presumably because of increased selection on female traits. Here, we examined the relationship between sexual dimorphism and sociality in eight species of Synalpheus snapping shrimps that vary in social structure and degree of reproductive skew. In species where reproduction was shared more equitably, most members of both sexes were physiologically capable of breeding. However, in species where reproduction was monopolized by a single individual, a large proportion of females--but not males--were reproductively inactive, suggesting stronger reproductive suppression and conflict among females. Moreover, as skew increased across species, proportional size of the major chela--the primary antagonistic weapon in snapping shrimps--increased among females and sexual dimorphism in major chela size declined. Thus, as reproductive skew increases among Synalpheus, female-female competition over reproduction appears to increase, resulting in decreased sexual dimorphism in weapon size. PMID:26041357
Joint Skewness and Its Application in Unsupervised Band Selection for Small Target Detection
Geng, Xiurui; Sun, Kang; Ji, Luyan; Tang, Hairong; Zhao, Yongchao
2015-01-01
Few band selection methods are specially designed for small target detection. It is well known that the information of small targets is most likely contained in non-Gaussian bands, where small targets are more easily separated from the background. On the other hand, correlation of band set also plays an important role in the small target detection. When the selected bands are highly correlated, it will be unbeneficial for the subsequent detection. However, the existing non-Gaussianity-based band selection methods have not taken the correlation of bands into account, which generally result in high correlation of obtained bands. In this paper, combining the third-order (third-order tensor) and second-order (correlation) statistics of bands, we define a new concept, named joint skewness, for multivariate data. Moreover, we also propose an easy-to-implement approach to estimate this index based on high-order singular value decomposition (HOSVD). Based on the definition of joint skewness, we present an unsupervised band selection for small target detection for hyperspectral data, named joint skewness band selection (JSBS). The evaluation results demonstrate that the bands selected by JSBS are very effective in terms of small target detection. PMID:25873018
Bridging biometrics and forensics
NASA Astrophysics Data System (ADS)
Yan, Yanjun; Osadciw, Lisa Ann
2008-02-01
This paper is a survey on biometrics and forensics, especially on the techniques and applications of face recognition in forensics. This paper describes the differences and connections between biometrics and forensics, and bridges each other by formulating the conditions when biometrics can be applied in forensics. Under these conditions, face recognition, as a non-intrusive and non-contact biometrics, is discussed in detail as an illustration of applying biometrics in forensics. The discussion on face recognition covers different approaches, feature extractions, and decision procedures. The advantages and limitations of biometrics in forensic applications are also addressed.
Nasal Bridge Intramuscular Hemangioma
Hamir Basah, Zulkifli; Ramza Ramli, Ramiza; Gayadh, Maha Khadum; Mutum, Samarendra Singh
2015-01-01
Intramuscular haemangioma (IMH) is a benign mesenchymal tumour. It appears as a deep, nontender mass within the soft tissue, particularly in the extremities. This tumour may not be obvious on clinical examination. Head and neck IMHs represent only 13.5% of the total IMHs. The most common site for a head and neck IMH is the masseter muscle, followed by trapezius, sternocleidomastoid, and very rarely temporalis muscle. We present a patient with left nasal bridge swelling which was excised and histologically confirmed as intramuscular hemangioma. PMID:25709848
Prediction of Scour Depth around Bridge Piers using Adaptive Neuro-Fuzzy Inference Systems (ANFIS)
NASA Astrophysics Data System (ADS)
Valyrakis, Manousos; Zhang, Hanqing
2014-05-01
Earth's surface is continuously shaped due to the action of geophysical flows. Erosion due to the flow of water in river systems has been identified as a key problem in preserving ecological health of river systems but also a threat to our built environment and critical infrastructure, worldwide. As an example, it has been estimated that a major reason for bridge failure is due to scour. Even though the flow past bridge piers has been investigated both experimentally and numerically, and the mechanisms of scouring are relatively understood, there still lacks a tool that can offer fast and reliable predictions. Most of the existing formulas for prediction of bridge pier scour depth are empirical in nature, based on a limited range of data or for piers of specific shape. In this work, the application of a Machine Learning model that has been successfully employed in Water Engineering, namely an Adaptive Neuro-Fuzzy Inference System (ANFIS) is proposed to estimate the scour depth around bridge piers. In particular, various complexity architectures are sequentially built, in order to identify the optimal for scour depth predictions, using appropriate training and validation subsets obtained from the USGS database (and pre-processed to remove incomplete records). The model has five variables, namely the effective pier width (b), the approach velocity (v), the approach depth (y), the mean grain diameter (D50) and the skew to flow. Simulations are conducted with data groups (bed material type, pier type and shape) and different number of input variables, to produce reduced complexity and easily interpretable models. Analysis and comparison of the results indicate that the developed ANFIS model has high accuracy and outstanding generalization ability for prediction of scour parameters. The effective pier width (as opposed to skew to flow) is amongst the most relevant input parameters for the estimation.
Ng, Benjamin; Cai, Wenju; Walsh, Kevin
2014-01-01
A positive Indian Ocean Dipole (IOD) tends to have stronger cold sea surface temperature anomalies (SSTAs) over the eastern Indian Ocean with greater impacts than warm SSTAs that occur during its negative phase. Two feedbacks have been suggested as the cause of positive IOD skewness, a positive Bjerknes feedback and a negative SST-cloud-radiation (SCR) feedback, but their relative importance is debated. Using inter-model statistics, we show that the most important process for IOD skewness is an asymmetry in the thermocline feedback, whereby SSTAs respond to thermocline depth anomalies more strongly during the positive phase than negative phase. This asymmetric thermocline feedback drives IOD skewness despite positive IODs receiving greater damping from the SCR feedback. In response to global warming, although the thermocline feedback strengthens, its asymmetry between positive and negative IODs weakens. This behaviour change explains the reduction in IOD skewness that many models display under global warming. PMID:25112717
Using skew-logistic probability density function as a model for age-specific fertility rate pattern.
Asili, Sahar; Rezaei, Sadegh; Najjar, Lotfollah
2014-01-01
Fertility rate is one of the most important global indexes. Past researchers found models which fit to age-specific fertility rates. For example, mixture probability density functions have been proposed for situations with bi-modal fertility patterns. This model is less useful for unimodal age-specific fertility rate patterns, so a model based on skew-symmetric (skew-normal) pdf was proposed by Mazzuco and Scarpa (2011) which was flexible for unimodal and bimodal fertility patterns. In this paper, we introduce skew-logistic probability density function as a better model: its residuals are less than those of the skew-normal model and it can more precisely estimate the parameters of the model. PMID:24967404
Ng, Benjamin; Cai, Wenju; Walsh, Kevin
2014-01-01
A positive Indian Ocean Dipole (IOD) tends to have stronger cold sea surface temperature anomalies (SSTAs) over the eastern Indian Ocean with greater impacts than warm SSTAs that occur during its negative phase. Two feedbacks have been suggested as the cause of positive IOD skewness, a positive Bjerknes feedback and a negative SST-cloud-radiation (SCR) feedback, but their relative importance is debated. Using inter-model statistics, we show that the most important process for IOD skewness is an asymmetry in the thermocline feedback, whereby SSTAs respond to thermocline depth anomalies more strongly during the positive phase than negative phase. This asymmetric thermocline feedback drives IOD skewness despite positive IODs receiving greater damping from the SCR feedback. In response to global warming, although the thermocline feedback strengthens, its asymmetry between positive and negative IODs weakens. This behaviour change explains the reduction in IOD skewness that many models display under global warming. PMID:25112717
NASA Technical Reports Server (NTRS)
Weick, Fred E; Harris, Thomas A
1934-01-01
This report covers the sixth of a series of investigations in which various lateral control devices are compared with particular reference to their effectiveness at high angles of attack. The present report deals with flap-type ailerons hinged about axes having an angle with respect to the leading and trailing edges of the wing. Tests were made on four different skewed ailerons, including two different angles of skew and two sizes of ailerons. At the high angles of attack, all the skewed ailerons tested were slightly inferior with respect to rolling and yawing moments to straight ailerons having the same span and average chord. Computations indicate that the skewed ailerons are also inferior with respect to hinge moments.
A Thouless formula and Aubry duality for long-range SchrÃ¶dinger skew-products
NASA Astrophysics Data System (ADS)
Haro, Alex; Puig, Joaquim
2013-05-01
In this paper, we study the dynamical properties of a class of ergodic linear skew-products which includes the linear skew-products defined by quasi-periodic SchrÃ¶dinger operators and their duals, in Aubry sense, when the potential is a trigonometric polynomial. Notably, these linear skew-products preserve an adapted complex-symplectic structure. We prove a Thouless formula relating the sum of the positive Lyapunov exponents and the logarithmic potential associated with the density of states of the corresponding operator. In particular, for quasi-periodic SchrÃ¶dinger operators and their duals, we prove an identity for the upper Lyapunov exponent of the skew-product and the sum of the positive Lyapunov exponents of their dual, which generalizes the well-known formula for the Almost Mathieu. We illustrate these identities with some numerical illustrations.
NASA Astrophysics Data System (ADS)
Materna, K.; Herring, T.
2013-12-01
Error in modeling atmospheric delay is one of the limiting factors in the accuracy of GPS position determination. In regions with uneven topography, atmospheric delay phenomena can be especially complicated. Current delay models used in analyzing daily GPS data from the Plate Boundary Observatory (PBO) are successful in achieving millimeter-level accuracy at most locations; however, at a subset of stations, the time-series for position estimates contain an unusually large number of outliers. In many cases these outliers are oriented in the same direction. The stations which exhibit asymmetric outliers occur in various places across the PBO network, but they are especially numerous in California's Mammoth Lakes region, which served as a case study for this presentation. The phenomenon was analyzed by removing secular trends and variations with periods longer than 75 days from the signal using a median filter. We subsequently calculated the skewness of the station position residuals in north, east and up directions. In the cases examined, typical position outliers are 5-15 mm. In extreme cases, skewed position residuals, not related to snow on antennas, can be as large as 20 mm. We examine the causes of the skewness through site-by-site comparisons with topographic data and numerical weather models. Analysis suggests that the direction of the skewness is generally parallel to the local topographic gradient at a scale of several kilometers, and that outlier data points occur when certain atmospheric conditions are met. The results suggest that a coupling between the atmosphere and local topography is responsible for the phenomenon of skewed residuals. In this presentation, we examine the characteristics of the sites that we have analyzed in detail. From these analyses, we postulate possible parameterizations of the atmospheric and topographic effects that could be incorporated into geodetic analysis programs, thus allowing the inhomogeneous atmospheric delays to be estimated in the same way that zenith and gradient atmospheric delay parameters are currently estimated. In addition to explicit estimation, we also explore the possibility of incorporating these effects in position error models, so that the uncertainties in the position estimates are reflective of these effects.
Coil Creep and Skew-Quadrupole Field Components in the Tevatron
Annala, G.; Harding, D.J.; Syphers, M.J.; /Fermilab
2011-07-11
During the start-up of Run II of the Tevatron Collider program, several issues surfaced which were not present, or not seen as detrimental, during Run I. These included the repeated deterioration of the closed orbit requiring orbit smoothing every two weeks or so, the inability to correct the closed orbit to desired positions due to various correctors running at maximum limits, regions of systematically strong vertical dipole corrections, and the identification of very strong coupling between the two transverse degrees-of-freedom. It became apparent that many of the problems being experienced operationally were connected to a deterioration of the main dipole magnet alignment, and remedial actions were undertaken. However, the alignment alone was not enough to explain the corrector strengths required to handle transverse coupling. With one exception, strong coupling had generally not been an issue in the Tevatron during Run I. Based on experience with the Main Ring, the Tevatron was designed with a very strong skew quadrupole circuit to compensate any quadrupole alignment and skew quadrupole field errors that might present themselves. The circuit was composed of 48 correctors placed evenly throughout the arcs, 8 per sector, evenly placed in every other cell. Other smaller circuits were installed but not initially needed or commissioned. These smaller circuits were composed of individual skew quadrupole correctors on either side of the long straight sections. These circuits were tuned by first bringing the horizontal and vertical tunes near each other. The skew quadrupoles were then adjusted to minimize tune split, usually to less than 0.003. Initially, the main skew quad circuit (designated T:SQ) could accomplish this global decoupling with only 4% of its possible current, and the smaller circuits were not required at all. The start-up of Run Ib was complicated by what was later discovered to be a rolled triplet quadrupole magnet in one of the Interaction Regions. This led to a reduction in luminosity of nearly 50%, as well as operational confusion until it was uncovered. By the time Collider Run II began, the current needed on the main SQ circuit had increased to 60% of its maximum value. Some of the smaller circuits were also needed to fully decouple the tunes. With this history, several studies were performed early in Run II to search for strong local coupling sources like the triplet quadrupole, but without success. The strong corrector settings were indicative of a much larger problem than a single rolled magnet, and the locality of the error was hard to deduce from the setting of a global correction system. Several possible reasons for the increase in coupling were investigated.
Hutson, Alan D.; Wilding, Gregory E.; Mashtare, Terry L.; Vexler, Albert
2016-01-01
In this note we develop a new multivariate copula model based on epsilon–skew–normal marginal densities for the purpose of examining biomarker dependency structures. We illustrate the flexibility and utility of this model via a variety of graphical tools and a data analysis example pertaining to salivary biomarker. The multivariate normal model is a sub-model of the multivariate epsilon–skew–normal distribution.
5. North side of throughtruss bridge over railroad tracks (bridge ...
5. North side of through-truss bridge over railroad tracks (bridge #U182512605). View to southwest. - South Omaha Union Stock Yards, "O" Street Viaduct, "O" Street Spanning Hog Pens; South Omaha Terminal Railway Company Tracks & Union Pacific Railroad Tracks, Omaha, Douglas County, NE
25. White Plains Road Bridge in foreground; Unionport Road Bridge ...
25. White Plains Road Bridge in foreground; Unionport Road Bridge in background. Van Nest, Bronx Co., NY. Sec. 4207, MP 12.75./78. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY
3. HONEYWELL STREET BRIDGE AND ELEVATED SUBWAY BRIDGE CROSSING SUNNYSIDE ...
3. HONEYWELL STREET BRIDGE AND ELEVATED SUBWAY BRIDGE CROSSING SUNNYSIDE YARDS. LONG ISLAND CITY, QUEENS CO., NY. Sec. 1411, MP 3.55. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY
16. Little Hell Gate Bridge with Big Hell Gate Bridge ...
16. Little Hell Gate Bridge with Big Hell Gate Bridge in background. Wards Island, New York Co., NY. Sec. 4207, MP 8.02. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY
20. Bronx Kill Bridge with Hell Gate Bridge in background. ...
20. Bronx Kill Bridge with Hell Gate Bridge in background. Randalls Island, New York Co., NY. Sec. 4207, MP 8.54. - Northeast Railroad Corridor, Amtrak Route between New Jersey/New York & New York/Connecticut State Lines, New York, New York County, NY
33 CFR 115.40 - Bridge repairs.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES Â§ 115.40 Bridge repairs. Repairs to a bridge which...
33 CFR 115.40 - Bridge repairs.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES Â§ 115.40 Bridge repairs. Repairs to a bridge which...
33 CFR 115.40 - Bridge repairs.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES Â§ 115.40 Bridge repairs. Repairs to a bridge which...
33 CFR 115.40 - Bridge repairs.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES Â§ 115.40 Bridge repairs. Repairs to a bridge which...
33 CFR 115.40 - Bridge repairs.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Bridge repairs. 115.40 Section 115.40 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES Â§ 115.40 Bridge repairs. Repairs to a bridge which...
Huang, Yangxin; Chen, Ren; Dagne, Getachew; Zhu, Yiliang; Chen, Henian
2015-01-01
Bivariate correlated (clustered) data often encountered in epidemiological and clinical research are routinely analyzed under a linear mixed-effected (LME) model with normality assumptions for the random-effects and within-subject errors. However, those analyses might not provide robust inference when the normality assumptions are questionable if the data set particularly exhibits skewness and heavy tails. In this article, we develop a Bayesian approach to bivariate linear mixed-effects (BLME) models replacing the Gaussian assumptions for the random terms with skew-normal/independent (SNI) distributions. The SNI distribution is an attractive class of asymmetric heavy-tailed parametric structure which includes the skew-normal, skew-t, skew-slash, and skew-contaminated normal distributions as special cases. We assume that the random-effects and the within-subject (random) errors, respectively, follow multivariate SNI and normal/independent (NI) distributions, which provide an appealing robust alternative to the symmetric normal distribution in a BLME model framework. The method is exemplified through an application to an AIDS clinical data set to compare potential models with different distribution specifications, and clinically important findings are reported. PMID:24897242
Orstavik, K.H.; Orstavik, R.E.; Eiklid, K.; Tranebjaerg, L.
1996-07-12
A new X-linked recessive deafness syndrome was recently reported and mapped to Xq22 (Mohr-Tranebjaeerg syndrome). In addition to deafness, the patients had visual impairment, dystonia, fractures, and mental deterioration. The female carriers did not have any significant manifestations of the syndrome. We examined X chromosome inactivation in 8 obligate and 12 possible carriers by using a polymerase chain reaction analysis of the methylation-dependent amplification of the polymorphic triplet repeat at the androgen receptor locus. Seven of 8 obligate carriers and 1 of 5 carriers by linkage analysis had an extremely skewed pattern in blood DNA not found in 30 normal females. The X inactivation pattern in fibroblast DNA from 2 of the carriers with the extremely skewed pattern was also skewed but to a lesser degree than in blood DNA. One obligate carrier had a random X inactivation pattern in both blood and fibroblast DNA. A selection mechanism for the skewed pattern is therefore not likely. The extremely skewed X inactivation in 8 females of 3 generations in this family may be caused by a single gene that influences skewing of X chromosome inactivation. 22 refs., 2 figs., 1 tab.
Godler, David E; Inaba, Yoshimi; Schwartz, Charles E; Bui, Quang M; Shi, Elva Z; Li, Xin; Herlihy, Amy S; Skinner, Cindy; Hagerman, Randi J; Francis, David; Amor, David J; Metcalfe, Sylvia A; Hopper, John L; Slater, Howard R
2015-01-01
Methylation of the fragile X mental retardation 1 (FMR1) exon 1/intron 1 boundary positioned fragile X related epigenetic element 2 (FREE2), reveals skewed X-chromosome inactivation (XCI) in fragile X syndrome full mutation (FM: CGG > 200) females. XCI skewing has been also linked to abnormal X-linked gene expression with the broader clinical impact for sex chromosome aneuploidies (SCAs). In this study, 10 FREE2 CpG sites were targeted using methylation specific quantitative melt analysis (MS-QMA), including 3 sites that could not be analysed with previously used EpiTYPER system. The method was applied for detection of skewed XCI in FM females and in different types of SCA. We tested venous blood and saliva DNA collected from 107 controls (CGG < 40), and 148 FM and 90 SCA individuals. MS-QMA identified: (i) most SCAs if combined with a Y chromosome test; (ii) locus-specific XCI skewing towards the hypomethylated state in FM females; and (iii) skewed XCI towards the hypermethylated state in SCA with 3 or more X chromosomes, and in 5% of the 47,XXY individuals. MS-QMA output also showed significant correlation with the EpiTYPER reference method in FM males and females (P < 0.0001) and SCAs (P < 0.05). In conclusion, we demonstrate use of MS-QMA to quantify skewed XCI in two applications with diagnostic utility. PMID:26132880
47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 47 Telecommunication 5 2013-10-01 2013-10-01 false Operator requirements of the Bridge-to-Bridge... Requirements Â§ 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the Bridge-to-Bridge Act must have on board a radio operator who holds a restricted radiotelephone operator permit...
47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 47 Telecommunication 5 2012-10-01 2012-10-01 false Operator requirements of the Bridge-to-Bridge... Requirements Â§ 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the Bridge-to-Bridge Act must have on board a radio operator who holds a restricted radiotelephone operator permit...
47 CFR 80.331 - Bridge-to-bridge communication procedure.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 47 Telecommunication 5 2012-10-01 2012-10-01 false Bridge-to-bridge communication procedure. 80..., Alarm, Urgency and Safety Procedures Â§ 80.331 Bridge-to-bridge communication procedure. (a) Vessels subject to the Bridge-to-Bridge Act transmitting on the designated navigational frequency must...
47 CFR 80.331 - Bridge-to-bridge communication procedure.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 47 Telecommunication 5 2013-10-01 2013-10-01 false Bridge-to-bridge communication procedure. 80..., Alarm, Urgency and Safety Procedures Â§ 80.331 Bridge-to-bridge communication procedure. (a) Vessels subject to the Bridge-to-Bridge Act transmitting on the designated navigational frequency must...
47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section 80.1007 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Bridge-to-Bridge Act Â§ 80.1007 Bridge-to-bridge radiotelephone installation. Use of the...
47 CFR 80.331 - Bridge-to-bridge communication procedure.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 47 Telecommunication 5 2010-10-01 2010-10-01 false Bridge-to-bridge communication procedure. 80..., Alarm, Urgency and Safety Procedures Â§ 80.331 Bridge-to-bridge communication procedure. (a) Vessels subject to the Bridge-to-Bridge Act transmitting on the designated navigational frequency must...
47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 47 Telecommunication 5 2012-10-01 2012-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section 80.1007 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Bridge-to-Bridge Act Â§ 80.1007 Bridge-to-bridge radiotelephone installation. Use of the...
47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 47 Telecommunication 5 2013-10-01 2013-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section 80.1007 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Bridge-to-Bridge Act Â§ 80.1007 Bridge-to-bridge radiotelephone installation. Use of the...
47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 47 Telecommunication 5 2014-10-01 2014-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section 80.1007 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Bridge-to-Bridge Act Â§ 80.1007 Bridge-to-bridge radiotelephone installation. Use of the...
47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 47 Telecommunication 5 2010-10-01 2010-10-01 false Operator requirements of the Bridge-to-Bridge... Requirements Â§ 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the Bridge-to-Bridge Act must have on board a radio operator who holds a restricted radiotelephone operator permit...
47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 47 Telecommunication 5 2011-10-01 2011-10-01 false Operator requirements of the Bridge-to-Bridge... Requirements Â§ 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the Bridge-to-Bridge Act must have on board a radio operator who holds a restricted radiotelephone operator permit...
47 CFR 80.1007 - Bridge-to-bridge radiotelephone installation.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 47 Telecommunication 5 2011-10-01 2011-10-01 false Bridge-to-bridge radiotelephone installation. 80.1007 Section 80.1007 Telecommunication FEDERAL COMMUNICATIONS COMMISSION (CONTINUED) SAFETY AND... Bridge-to-Bridge Act Â§ 80.1007 Bridge-to-bridge radiotelephone installation. Use of the...
47 CFR 80.331 - Bridge-to-bridge communication procedure.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 47 Telecommunication 5 2011-10-01 2011-10-01 false Bridge-to-bridge communication procedure. 80..., Alarm, Urgency and Safety Procedures Â§ 80.331 Bridge-to-bridge communication procedure. (a) Vessels subject to the Bridge-to-Bridge Act transmitting on the designated navigational frequency must...
47 CFR 80.331 - Bridge-to-bridge communication procedure.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 47 Telecommunication 5 2014-10-01 2014-10-01 false Bridge-to-bridge communication procedure. 80..., Alarm, Urgency and Safety Procedures Â§ 80.331 Bridge-to-bridge communication procedure. (a) Vessels subject to the Bridge-to-Bridge Act transmitting on the designated navigational frequency must...
47 CFR 80.163 - Operator requirements of the Bridge-to-Bridge Act.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 47 Telecommunication 5 2014-10-01 2014-10-01 false Operator requirements of the Bridge-to-Bridge... Requirements Â§ 80.163 Operator requirements of the Bridge-to-Bridge Act. Each ship subject to the Bridge-to-Bridge Act must have on board a radio operator who holds a restricted radiotelephone operator permit...
Mathematics in Use: Suspension Bridges.
ERIC Educational Resources Information Center
Ginther, John L.
1992-01-01
Reviews the mathematics utilized in the design and construction of suspension bridges, in general, then illustrates these mathematical concepts by examining data associated with the Mackinac Bridge, which connects the two peninsulas of Michigan. Emphasizes the strong interest factor these gigantic structures have for students by attaching a sense…
Mathematics in Use: Suspension Bridges.
ERIC Educational Resources Information Center
Ginther, John L.
1992-01-01
Reviews the mathematics utilized in the design and construction of suspension bridges, in general, then illustrates these mathematical concepts by examining data associated with the Mackinac Bridge, which connects the two peninsulas of Michigan. Emphasizes the strong interest factor these gigantic structures have for students by attaching a senseâ€¦
Liquid Bridges Between Contacting Balls
NASA Astrophysics Data System (ADS)
Vogel, Thomas I.
2014-07-01
The problem studied is that of a rotationally symmetric liquid bridge between two contacting balls of equal radius, with the same contact angle with both balls, and in the absence of gravity. The bridge surface must be of constant mean curvature, hence a Delaunay surface. If the contact angle is less than {?/2} , existence of a rotationally symmetric bridge is shown for a large range of the relevant parameter, giving unduloidal, catenoidal, and nodoidal bridges. If the contact angle is greater than or equal to {?/2} , it is shown that no stable rotationally symmetric bridge which is symmetric across the perpendicular bisector of the line segment between the two centers of the balls exists. Existence therefore depends discontinuously on contact angle.
NASA Astrophysics Data System (ADS)
Boswell, S. M.; Zheng, L.; Gordon, R. G.; Dyment, J.
2011-12-01
An improved understanding of the spreading-rate dependence of anomalous skewness from magnetic anomalies due to seafloor spreading will allow for better constraints on apparent polar wander paths, plate reconstructions, and the magnetic and thermal structure of oceanic lithosphere. Anomalous skewness, which is the difference between experimentally determined skewness and skewness expected from simple magnetization models with vertical reversal boundaries, has been observed to vary as a function of spreading rate, decreasing with increasing spreading rate and becoming negligible at spreading half-rates exceeding about 55 mm/a [Roest et al. 1992; Dyment et al. 1994]. In our analysis, we determine model-based estimates of anomalous skewness as a function of spreading rate for each anomaly. We do so by creating many synthetic profiles using the model of Dyment and Arkani-Hamed (1995), which was specifically constructed to produce anomalies with anomalous skewness consistent with observed anomalies. We experimentally determine the phase shift that causes the resulting synthetic magnetic anomaly to best match a profile produced from a "standard" model for anomalies due to seafloor spreading that assumes simple vertical reversal boundaries. We present results for those anomalies between 12r and 33r from which reliable paleomagnetic poles may potentially be determined. Differences in anomalous skewness for different anomalies determined at the same spreading rate can be attributed to the sequence effect, that is, the effect on the shape of a magnetic anomaly above seafloor of a single polarity chron of the magnetization of neighboring blocks of lithosphere magnetized during other chrons. We find that the sequence effect is smaller than we expected with the largest difference being between the results for anomaly 25r and those for anomaly 33r, for which the difference is 14 degrees at a 10 mm/a half-rate. Results for other anomalies lie between these two. We also infer a small outward displacement of the magnetic anomalies, which-like anomalous skewness-decreases with increasing spreading rate and vanishes at half rates exceeding 55 mm/a. We find that results obtained trying to find the best match to the synthetic magnetic anomaly profile are generally similar to results obtained when using the balanced-shoulder criterion for when an anomaly has been successfully deskewed. The values of chron-specific (or anomaly-specific) anomalous skewness that we have determined can be used to reduce the number of adjustable parameters in the determination of paleomagnetic poles from skewness data from three to two, to simply the latitude and longitude of the paleomagnetic pole. Implications for the northward motion of the Pacific Plate will be discussed.
NASA Technical Reports Server (NTRS)
Levine, Joel S.
1990-01-01
Most burning of biomass is the result of human activity, and on a global scale it is increasing. Tropospheric concentrations of CO2, CO, CH4, non-methane hydrocarbons, and ozone are all increasing with time; global biomass burning may make an important contribution to this increase and thus to potential global climate change. The nitrogen cycle also can have important climatic effects. Nitrous oxide put into the atmosphere by biomass burning is a greenhouse gas 250 times more powerful (molecule for molecule) than carbon dioxide. Nitric oxide, as well as being a photochemical precursor of ozone, a major pollutant in the troposphere, produces nitric acid, the fastest-growing component of acid rain. Hence, the new bridge in the nitrogen cycle is of more than mere technical interest.
NASA Astrophysics Data System (ADS)
Friebele, Elaine
Journalists who report on scientific discoveries and the scientists who make them are, in many cases, separated by a Grand Canyon-sized gap. A recent U.S. survey revealed that journalists believe that scientists' jargon prevents effective communication. Scientists polled in the same survey, conducted by Today Show host Jim Hartz and NASA scientist Rick Chappell, said that journalists need to do a better job of verifying facts and interpreting scientific results.Panelists representing the scientific and media communities will discuss ways to bridge that gap during the “Science and the Media” episode of Freedom Speaks, to be aired by Public Broadcasting Stations in May and June (check your local listings).
Cascaded resonant bridge converters
NASA Technical Reports Server (NTRS)
Stuart, Thomas A. (Inventor)
1989-01-01
A converter for converting a low voltage direct current power source to a higher voltage, high frequency alternating current output for use in an electrical system where it is desired to use low weight cables and other circuit elements. The converter has a first stage series resonant (Schwarz) converter which converts the direct current power source to an alternating current by means of switching elements that are operated by a variable frequency voltage regulator, a transformer to step up the voltage of the alternating current, and a rectifier bridge to convert the alternating current to a direct current first stage output. The converter further has a second stage series resonant (Schwarz) converter which is connected in series to the first stage converter to receive its direct current output and convert it to a second stage high frequency alternating current output by means of switching elements that are operated by a fixed frequency oscillator. The voltage of the second stage output is controlled at a relatively constant value by controlling the first stage output voltage, which is accomplished by controlling the frequency of the first stage variable frequency voltage controller in response to second stage voltage. Fault tolerance in the event of a load short circuit is provided by making the operation of the first stage variable frequency voltage controller responsive to first and second stage current limiting devices. The second stage output is connected to a rectifier bridge whose output is connected to the input of the second stage to provide good regulation of output voltage wave form at low system loads.
Heat transfer in rotating serpentine passages with trips skewed to the flow
NASA Technical Reports Server (NTRS)
Johnson, B. V.; Wagner, J. H.; Steuber, G. D.; Yeh, F. C.
1992-01-01
Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large scale, multi-pass, heat transfer model with both radially inward and outward flow. Trip strips, skewed at 45 deg to the flow direction, were machined on the leading and trailing surfaces of the radial coolant passages. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature, rotation number, Reynolds number, and radius-to-passage hydraulic diameter ratio. The first three of these four parameters were varied over ranges which are typical of advanced gas turbine engine operating conditions. Results were correlated and compared to previous results from similar stationary and rotating models with smooth walls and with trip strips normal to the flow direction. The heat transfer coefficients on surfaces, where the heat transfer decreased with rotation and buoyancy, decreased to as low as 40 percent of the value without rotation. However, the maximum values of the heat transfer coefficients with high rotation were only slightly above the highest levels previously obtained with the smooth wall models. It was concluded that (1) both Coriolis and buoyancy effects must be considered in turbine blade cooling designs with trip strips, (2) the effects of rotation are markedly different depending upon the flow direction, and (3) the heat transfer with skewed trip strips is less sensitive to buoyancy than the heat transfer in models with either smooth or normal trips. Therefore, skewed trip strips rather than normal trip strips are recommended and geometry-specific tests are required for accurate design information.
Generalized parton distributions for the proton in position space: Nonzero skewness
Manohar, R.; Mukherjee, A.; Chakrabarti, D.
2011-01-01
We investigate the generalized parton distributions for u and d quarks in a proton in transverse and longitudinal position space using a recent phenomenological parametrization. We take nonzero skewness {zeta} and consider the region x>{zeta}. The impact parameter space representation of the generalized parton distribution E is found to depend sharply on the parameters used within the model, in particular, in the low x region. In the longitudinal position space a diffraction pattern is observed, as seen before in several other models.
Measuring skew in average surface roughness as a function of surface preparation
NASA Astrophysics Data System (ADS)
Stahl, Mark T.
2015-08-01
Characterizing surface roughness is important for predicting optical performance. Better measurement of surface roughness reduces polishing time, saves money and allows the science requirements to be better defined. This study characterized statistics of average surface roughness as a function of polishing time. Average surface roughness was measured at 81 locations using a ZygoÂ® white light interferometer at regular intervals during the polishing process. Each data set was fit to a normal and Largest Extreme Value (LEV) distribution; then tested for goodness of fit. We show that the skew in the average data changes as a function of polishing time.
Structure-induced negatively skewed X-ray diffraction pattern of carbon onions
NASA Astrophysics Data System (ADS)
Siklitskaya, Alexandra; Yastrebov, Sergey; Smith, Roger
2013-10-01
The idea is discussed that a gradual change of intershell separation in carbon onions may introduce a negative skewness into the most intense X-ray diffraction band. As an example, the experimental X-ray diffraction pattern of carbon onions is analysed using a weighted Lorentzian X-ray profile broadening model for each intershell separation contributing to the profile. The dependence of the mean radius for carbon onion shells on the intershell spacing between the adjacent shells is derived from the model analysis. Comparison with the internal distribution of atomic density in carbon onions measured with high resolution transmission electron microscopy is discussed.
Measuring Skew in Average Surface Roughness as a Function of Surface Preparation
NASA Technical Reports Server (NTRS)
Stahl, Mark T.
2015-01-01
Characterizing surface roughness is important for predicting optical performance. Better measurement of surface roughness reduces grinding saving both time and money and allows the science requirements to be better defined. In this study various materials are polished from a fine grind to a fine polish. Each sample's RMS surface roughness is measured at 81 locations in a 9x9 square grid using a Zygo white light interferometer at regular intervals during the polishing process. Each data set is fit with various standard distributions and tested for goodness of fit. We show that the skew in the RMS data changes as a function of polishing time.
NASA Astrophysics Data System (ADS)
Zhang, Meirong; Zhou, Zhe
2011-05-01
Motivated by linear Schrödinger equations with almost periodic potentials and phase transitions over almost periodic lattices, we introduce the so-called skew-product quasi-flows (SPQFs), which may admit both temporal and spatial discontinuity. In this paper we establish two basic theorems for SPQFs. One is an extension of the Bogoliubov-Krylov theorem for the existence of invariant Borel probability measures and the other is the uniform ergodic theorems. As applications, it will be shown that such a Schrödinger equation admits a well-defined rotation number.
Measuring Skew in Average Surface Roughness as a Function of Surface Preparation
NASA Technical Reports Server (NTRS)
Stahl, Mark
2015-01-01
Characterizing surface roughness is important for predicting optical performance. Better measurement of surface roughness reduces polishing time, saves money and allows the science requirements to be better defined. This study characterized statistics of average surface roughness as a function of polishing time. Average surface roughness was measured at 81 locations using a Zygo white light interferometer at regular intervals during the polishing process. Each data set was fit to a normal and Largest Extreme Value (LEV) distribution; then tested for goodness of fit. We show that the skew in the average data changes as a function of polishing time.
Skewness in (1+1)-dimensional Kardar-Parisi-Zhang-type growth.
Singha, Tapas; Nandy, Malay K
2014-12-01
We use the (1+1)-dimensional Kardar-Parisi-Zhang equation driven by a Gaussian white noise and employ the dynamic renormalization-group of Yakhot and Orszag without rescaling [J. Sci. Comput. 1, 3 (1986)]. Hence we calculate the second- and third-order moments of height distribution using the diagrammatic method in the large-scale and long-time limits. The moments so calculated lead to the value S=0.3237 for the skewness. This value is comparable with numerical and experimental estimates. PMID:25615107
A new index (MediSkew) for the assessment of the Cymodocea nodosa (Ucria) Ascherson meadow's status.
Orlando-Bonaca, Martina; Francé, Janja; Mavri?, Borut; Grego, Mateja; Lipej, Lovrenc; Flander-Putrle, Vesna; Šiško, Milijan; Falace, Annalisa
2015-09-01
In the Mediterranean region Cymodocea nodosa is widely distributed throughout shallow sites. Therefore, a correct assessment of the status of its meadows is of great importance for the implementation of the Water Framework Directive (WFD), the Marine Strategy Framework Directive (MSFD), and the Habitat Directive (HD), especially for areas where Posidonia oceanica meadows (the most frequently used indicator in the Mediterranean Sea) are rare or not present. The previously proposed index for the evaluation of the status of C. nodosa meadows (CymoSkew) is based on ln-transformed relative frequencies of photosynthetic leaf lengths, which we believe is statistically questionable. Therefore, we further improved the methodology and developed a new index named MediSkew, where ln-transformation is applied to raw data of leaf lengths. More specifically, the index is a combination of two metrics, both based on C. nodosa leaf length: deviation from the reference median length (Medi-) and skewness of the length frequency distribution (-Skew), though greater importance was assigned to the first. To develop the classification criteria for the assessment of the status, also a Pressure Index for Seagrass Meadows (PISM), for the evaluation of pressure-impact relationships, was developed. The MediSkew is meant to be a rapid screening method for wide areas, therefore the index should be tested for the assessment of the status of C. nodosa meadows throughout Mediterranean coastal waters. PMID:26348885
Gentilini, Davide; Garagnani, Paolo; Pisoni, Serena; Bacalini, Maria Giulia; Calzari, Luciano; Mari, Daniela; Vitale, Giovanni; Franceschi, Claudio; Di Blasio, Anna Maria
2015-01-01
In this study we applied a new analytical strategy to investigate the relations between stochastic epigenetic mutations (SEMs) and aging. We analysed methylation levels through the Infinium HumanMethylation27 and HumanMethylation450 BeadChips in a population of 178 subjects ranging from 3 to 106 years. For each CpG probe, epimutated subjects were identified as the extreme outliers with methylation level exceeding three times interquartile ranges the first quartile (Q1-(3 × IQR)) or the third quartile (Q3+(3 × IQR)). We demonstrated that the number of SEMs was low in childhood and increased exponentially during aging. Using the HUMARA method, skewing of X chromosome inactivation (XCI) was evaluated in heterozygotes women. Multivariate analysis indicated a significant correlation between log(SEMs) and degree of XCI skewing after adjustment for age (? = 0.41; confidence interval: 0.14, 0.68; p-value = 0.0053). The PATH analysis tested the complete model containing the variables: skewing of XCI, age, log(SEMs) and overall CpG methylation. After adjusting for the number of epimutations we failed to confirm the well reported correlation between skewing of XCI and aging. This evidence might suggest that the known correlation between XCI skewing and aging could not be a direct association but mediated by the number of SEMs. PMID:26342808
Weighted skewness and kurtosis unbiased by sample size and Gaussian uncertainties
NASA Astrophysics Data System (ADS)
Rimoldini, Lorenzo
2014-07-01
Central moments and cumulants are often employed to characterize the distribution of data. The skewness and kurtosis are particularly useful for the detection of outliers, the assessment of departures from normally distributed data, automated classification techniques and other applications. Estimators of higher order moments that are robust against outliers are more stable but might miss characteristic features of the data, as in the case of astronomical time series exhibiting brief events like stellar bursts or eclipses of binary systems, while weighting can help identify reliable measurements from uncertain or spurious outliers. Furthermore, noise is an unavoidable part of most measurements and their uncertainties need to be taken properly into account during the data analysis or biases are likely to emerge in the results, including basic descriptive statistics. This work provides unbiased estimates of the weighted skewness and kurtosis moments and cumulants, corrected for biases due to sample size and Gaussian noise, under the assumption of independent data. A comparison of biased and unbiased weighted estimators is illustrated with simulations as a function of sample size and signal-to-noise ratio, employing different data distributions and weighting schemes related to measurement uncertainties and the sampling of the signal. Detailed derivations and figures of simulation results are presented in the Appendices available online.
Accurate Modeling of the Postbuckling Response of Composite Panels with Skewed Stiffeners
NASA Technical Reports Server (NTRS)
Young, Richard D.; Hyer, Michael W.
1998-01-01
Modeling procedures which predict accurately the postbuckling response of composite panels with skewed stiffeners are presented. A particular experimental program is considered and detailed finite element models are created to represent the conditions in the experiment. First, a simple baseline model with minimal detail is defined. Then, a number of modeling refinements that improve the accuracy of the model are identified. These refinements are applied individually to the baseline model to assess the effect of each refinement on the predicted response. The individual refinements are then combined to create an advanced finite element model. In addition to model refinements which affect the overall panel response, a modeling procedure for simulating nonuniform initial load introduction that is specific to an particular experiment is described and demonstrated. By implementing a number of modeling refinements, a finite element model is developed which improves the correlation between the measured and predicted responses. The skewed stiffener detail and anisotropic skin in the selected problem create axial-shear stiffness coupling which makes this problem sensitive to the constraint on the shear displacement. The remainder of the modeling refinements considered are applicable to general structural configurations. The results presented may be used to guide future efforts to improve correlation between predicted and measured responses for post buckled stiffened panels.
Changes of skewness and sharpness of partially coherent decentered annular beams on propagation
NASA Astrophysics Data System (ADS)
Yang, Ting; Ji, Xiaoling; Li, Xiaoqing; Zhang, Hao; Wang, Tao
2016-01-01
Changes of skewness and sharpness of partially coherent decentered annular beams (PCDA beams) on propagation both in free space and in oceanic turbulence are studied. Based on the Wigner distribution function, the analytical expressions for the skewness parameter A and the kurtosis parameter K of PCDA beams are derived. The analytical expression for the oceanic turbulence parameter Tâ€§ related to K is also derived, and characteristics of Tâ€§ are examined. It is found that the behaviors of A and K in oceanic turbulence are quite different from those in free space. In free space, the mass of the intensity distribution may move from one side of the centroid position axis yc to another side at a certain propagation distance z0, and z0 is independent of the correlation parameter Ï„. The mass of the intensity distribution is concentrated on one side of yc on propagation only for a poorly coherent beam in free space, but it is always this situation for different value of Ï„ when oceanic turbulence is not weak. In free space, it takes a leptokurtic profile in the far field, and a Gaussian profile appears only for a poorly coherent beam. However, in oceanic turbulence it always reaches a Gaussian profile for different value of Ï„ in the far field.
Skewness and kurtosis as indicators of non-Gaussianity in galactic foreground maps
NASA Astrophysics Data System (ADS)
Ben-David, Assaf; von Hausegger, Sebastian; Jackson, Andrew D.
2015-11-01
Observational cosmology is entering an era in which high precision will be required in both measurement and data analysis. Accuracy, however, can only be achieved with a thorough understanding of potential sources of contamination from foreground effects. Our primary focus will be on non-Gaussian effects in foregrounds. This issue will be crucial for coming experiments to determine B-mode polarization. We propose a novel method for investigating a data set in terms of skewness and kurtosis in locally defined regions that collectively cover the entire sky. The method is demonstrated on two sky maps: (i) the SMICA map of Cosmic Microwave Background fluctuations provided by the Planck Collaboration and (ii) a version of the Haslam map at 408 MHz that describes synchrotron radiation. We find that skewness and kurtosis can be evaluated in combination to reveal local physical information. In the present case, we demonstrate that the statistical properties of both maps in small local regions are predominantly Gaussian. This result was expected for the SMICA map. It is surprising that it also applies for the Haslam map given its evident large scale non-Gaussianity. The approach described here has a generality and flexibility that should make it useful in a variety of astrophysical and cosmological contexts.
Heat transfer in rotating serpentine passages with trips skewed to the flow
NASA Technical Reports Server (NTRS)
Johnson, B. V.; Wagner, J. H.; Steuber, G. D.; Yeh, F. C.
1992-01-01
Experiments were conducted to determine the effects of buoyancy and Coriolis forces on heat transfer in turbine blade internal coolant passages. The experiments were conducted with a large scale, multi-pass heat transfer model with both radially inward and outward flow. An analysis of the governing flow equations showed that four parameters influence the heat transfer in rotating passages: coolant-to-wall temperature, rotation number, Reynolds number, and radius-to-passage hydraulic diameter ratio. Results were correlated and compared to previous results from similar stationary and rotating models with smooth walls and with trip strips normal to the flow direction. It was concluded that (1) both Coriolis and buoyancy must be considered in turbine blade cooling designs with trip strips, (2) the effects of rotation are markedly different depending upon the flow direction, and (3) the heat transfer with skewed trip strips is less sensitive to buoyancy than the heat transfer models with either smooth or normal trips. Therefore, skewed trip strips rather than normal trip strips are recommended and geometry-specific tests are required for accurate design.
Near and Far Field Acoustic Pressure Skewness in a Heated Supersonic Jet
NASA Astrophysics Data System (ADS)
Gutmark, Ephraim; Mora, Pablo; Kastner, Jeff; Heeb, Nick; Kailasanath, Kailas; Liu, Junhui; University of Cincinnati Collaboration; Naval Research Laboratory Collaboration
2012-11-01
The dominant component of turbulent mixing noise in high speed jets is the Mach wave radiation generated by large turbulent structures in the shear layer The Over-All Sound Pressure Level (OASPL) in the far field peaks in a direction near the Mach wave angle. ``Crackle'' is another important component of high speed jet noise. Crackle cannot be recognized in the spectrum of the acoustic pressure signal, but it appears in the temporal waveform of the pressure as sharply rising peaks. Skewness levels of the pressure and dP/dt have been used as a measure of crackle in high specific thrust engines and rockets. In this paper, we focus on recognizing a technique that identifies the impact of different test conditions on the near-field and far-field statistics of the pressure and dP/dt signals of a supersonic jet with a design Mach number of Md=1.5 produced by a C-D conical nozzle. Cold and hot jets, T0=300K and 600K, are tested at over, design, and under-expanded conditions, with NPRs=2.5, 3.671, 4.5, respectively. Second, Third and Forth order statistics are examined in the near and far fields. Rms, skewness and kurtosis intensity levels and propagation are better identified in the dP/dt than in the pressure signal. Statistics of the dP/dt demonstrate to be a better measure for crackle. Project funded by ONR grant.
Comment on "Universal relation between skewness and kurtosis in complex dynamics"
NASA Astrophysics Data System (ADS)
Celikoglu, Ahmet; Tirnakli, Ugur
2015-12-01
In a recent paper [M. Cristelli, A. Zaccaria, and L. Pietronero, Phys. Rev. E 85, 066108 (2012), 10.1103/PhysRevE.85.066108], the authors analyzed the relation between skewness and kurtosis for complex dynamical systems, and they identified two power-law regimes of non-Gaussianity, one of which scales with an exponent of 2 and the other with 4 /3 . They concluded that the observed relation is a universal fact in complex dynamical systems. In this Comment, we test the proposed universal relation between skewness and kurtosis with a large number of synthetic data, and we show that in fact it is not a universal relation and originates only due to the small number of data points in the datasets considered. The proposed relation is tested using a family of non-Gaussian distribution known as q -Gaussians. We show that this relation disappears for sufficiently large datasets provided that the fourth moment of the distribution is finite. We find that kurtosis saturates to a single value, which is of course different from the Gaussian case (K =3 ), as the number of data is increased, and this indicates that the kurtosis will converge to a finite single value if all moments of the distribution up to fourth are finite. The converged kurtosis value for the finite fourth-moment distributions and the number of data points needed to reach this value depend on the deviation of the original distribution from the Gaussian case.
Chen, Jichun; Bryant, Mark A; Dent, James J; Sun, Yu; Desierto, Marie J; Young, Neal S
2015-12-01
A deletion of a telomerase RNA component (Terc(-/-)) in C57BL/6 (B6) mice resulted in hematopoietic lineage skewing with increased neutrophils and CD11b(+) myeloid cells and decreased red blood cells and CD45R(+) B lymphocytes when animals reach ages older than 12months. There was no decline in bone marrow (BM) c-Kit(+)Sca-1(+)Lin(-) (KSL) cells in old Terc(-/-) mice, and the lineage skewing phenomenon was not transferred when BM cells from old Terc(-/-) donors were transplanted into young B6 recipients. Necropsy and histological examinations found minimal to no change in the lung, spleen and liver but detected severe epithelia degeneration, ulceration and infection in small and large intestines, leading to enteritis, typhlitis and colitis in old Terc(-/-) mice. In a mouse model of dextran-sulfate-sodium-induced typhlitis and colitis, development of intestinal pathology was associated with increases in neutrophils and CD11b(+) myeloid cells and a decrease in CD45R(+) B cells, similar to those observed in old Terc(-/-) mice. Treatment of 11-13month old Terc(-/-) mice with antibiotic trimethoprim-sulfa water reduced neutrophils and myeloid cells and increased B lymphocytes in the blood, indicating that mitigation of intestinal infection and inflammation could alleviate hematological abnormalities in old Terc(-/-) animals. PMID:26523501
Random sampling of skewed distributions implies Taylor's power law of fluctuation scaling.
Cohen, Joel E; Xu, Meng
2015-06-23
Taylor's law (TL), a widely verified quantitative pattern in ecology and other sciences, describes the variance in a species' population density (or other nonnegative quantity) as a power-law function of the mean density (or other nonnegative quantity): Approximately, variance = a(mean)(b), a > 0. Multiple mechanisms have been proposed to explain and interpret TL. Here, we show analytically that observations randomly sampled in blocks from any skewed frequency distribution with four finite moments give rise to TL. We do not claim this is the only way TL arises. We give approximate formulae for the TL parameters and their uncertainty. In computer simulations and an empirical example using basal area densities of red oak trees from Black Rock Forest, our formulae agree with the estimates obtained by least-squares regression. Our results show that the correlated sampling variation of the mean and variance of skewed distributions is statistically sufficient to explain TL under random sampling, without the intervention of any biological or behavioral mechanisms. This finding connects TL with the underlying distribution of population density (or other nonnegative quantity) and provides a baseline against which more complex mechanisms of TL can be compared. PMID:25852144
Random sampling of skewed distributions implies Taylor’s power law of fluctuation scaling
Cohen, Joel E.; Xu, Meng
2015-01-01
Taylor’s law (TL), a widely verified quantitative pattern in ecology and other sciences, describes the variance in a species’ population density (or other nonnegative quantity) as a power-law function of the mean density (or other nonnegative quantity): Approximately, variance = a(mean)b, a > 0. Multiple mechanisms have been proposed to explain and interpret TL. Here, we show analytically that observations randomly sampled in blocks from any skewed frequency distribution with four finite moments give rise to TL. We do not claim this is the only way TL arises. We give approximate formulae for the TL parameters and their uncertainty. In computer simulations and an empirical example using basal area densities of red oak trees from Black Rock Forest, our formulae agree with the estimates obtained by least-squares regression. Our results show that the correlated sampling variation of the mean and variance of skewed distributions is statistically sufficient to explain TL under random sampling, without the intervention of any biological or behavioral mechanisms. This finding connects TL with the underlying distribution of population density (or other nonnegative quantity) and provides a baseline against which more complex mechanisms of TL can be compared. PMID:25852144
Fuel cell plates with skewed process channels for uniform distribution of stack compression load
Granata, Jr., Samuel J. (Greensburg, PA); Woodle, Boyd M. (North Huntingdon Township, Westmoreland County, PA)
1989-01-01
An electrochemical fuel cell includes an anode electrode, a cathode electrode, an electrolyte matrix sandwiched between electrodes, and a pair of plates above and below the electrodes. The plate above the electrodes has a lower surface with a first group of process gas flow channels formed thereon and the plate below the electrodes has an upper surface with a second group of process gas flow channels formed thereon. The channels of each group extend generally parallel to one another. The improvement comprises the process gas flow channels on the lower surface of the plate above the anode electrode and the process gas flow channels on the upper surface of the plate below the cathode electrode being skewed in opposite directions such that contact areas of the surfaces of the plates through the electrodes are formed in crisscross arrangements. Also, the plates have at least one groove in areas of the surfaces thereof where the channels are absent for holding process gas and increasing electrochemical activity of the fuel cell. The groove in each plate surface intersects with the process channels therein. Also, the opposite surfaces of a bipolar plate for a fuel cell contain first and second arrangements of process gas flow channels in the respective surfaces which are skewed the same amount in opposite directions relative to the longitudinal centerline of the plate.
Sardeshmukh, Prashant D.
2015-03-15
The probability distributions of large-scale atmospheric and oceanic variables are generally skewed and heavy-tailed. We argue that their distinctive departures from Gaussianity arise fundamentally from the fact that in a quadratically nonlinear system with a quadratic invariant, the coupling coefficients between system components are not constant but depend linearly on the system state in a distinctive way. In particular, the skewness arises from a tendency of the system trajectory to linger near states of weak coupling. We show that the salient features of the observed non-Gaussianity can be captured in the simplest such nonlinear 2-component system. If the system is stochastically forced and linearly damped, with one component damped much more strongly than the other, then the strongly damped fast component becomes effectively decoupled from the weakly damped slow component, and its impact on the slow component can be approximated as a stochastic noise forcing plus an augmented nonlinear damping. In the limit of large time-scale separation, the nonlinear augmentation of the damping becomes small, and the noise forcing can be approximated as an additive noise plus a correlated additive and multiplicative noise (CAM noise) forcing. Much of the diversity of observed large-scale atmospheric and oceanic probability distributions can be interpreted in this minimal framework.
Using Skewness and the First-Digit Phenomenon to Identify Dynamical Transitions in Cardiac Models
Seenivasan, Pavithraa; Easwaran, Soumya; Sridhar, Seshan; Sinha, Sitabhra
2016-01-01
Disruptions in the normal rhythmic functioning of the heart, termed as arrhythmia, often result from qualitative changes in the excitation dynamics of the organ. The transitions between different types of arrhythmia are accompanied by alterations in the spatiotemporal pattern of electrical activity that can be measured by observing the time-intervals between successive excitations of different regions of the cardiac tissue. Using biophysically detailed models of cardiac activity we show that the distribution of these time-intervals exhibit a systematic change in their skewness during such dynamical transitions. Further, the leading digits of the normalized intervals appear to fit Benford's law better at these transition points. This raises the possibility of using these observations to design a clinical indicator for identifying changes in the nature of arrhythmia. More importantly, our results reveal an intriguing relation between the changing skewness of a distribution and its agreement with Benford's law, both of which have been independently proposed earlier as indicators of regime shift in dynamical systems. PMID:26793114
Bridging the urological divide
2011-01-01
The advanced disease clinical presentations, higher morbidity and mortality rates and lack of available treatment options in prostate cancer care, attest to disparities in the delivery and outcomes of urological services in Black men of African lineage in both the Developed and Developing countries. This gap in health care and services in the global management of prostate cancer denotes the urological divide. Through the experience of a Developing country urologist with a comparative literature review, this presentation defines the determinants of the disparity through deficiencies in human, material and financial resources, as is most prevalent in Developing countries. Solutions to ending health care disparities must take into account the existing development phase of Third World countries and thus determine whether the Developed countries should export a total service delivery system or seek primarily to advance the competence and skills of the existing Developing country resources. Collaboration in prostate cancer research has the greatest promise and sustainability of bridging this urological divide and is of mutual benefit to both entities. PMID:21992183
Radio and Television Bridging Courses
ERIC Educational Resources Information Center
Shaw, John H.
1971-01-01
Describes the multi-media extension program of the University of New South Wales, which provides radio and television courses which help to bridge the transition from secondary to tertiary studies. (AN)
Lumia, Richard; Baevsky, Yvonne Halpern
2000-01-01
Flood-frequency relations that are developed by fitting the logarithms of annual peak discharges to a Pearson Type-III distribution are sensitive to skew coefficients. Estimates of population skew for a site are improved when computed from the weighted average of (1) the sample (station) skew, and (2) an unbiased, generalized skew estimate. A weighting technique based on the number of years of record at each of 226 sites was used to develop a contour map of unbiased, generalized skew coefficients for New York. An attempt was made to group (regionalize) the station skew coefficients into five hydrologically similar areas of New York, but the statewide version proved to be as accurate as the regionalized version and therefore was adopted as the final generalized skew-coefficient map for New York. An error analysis showed the statewide contour map to have lower MSE?s (mean square errors) than those computed from (1) the five regional skewcoefficient contour maps, (2) a previously used (1982) nationwide skew coefficient map, and (3) the weighted mean of skew coefficients for sites within each of five hydrologically uniform, but distinct areas of New York.
77 FR 16784 - General Bridge Regulation; Amendment
Federal Register 2010, 2011, 2012, 2013, 2014
2012-03-22
... SECURITY Coast Guard 33 CFR Part 114, 116, 118 RIN 1625-AB36 General Bridge Regulation; Amendment AGENCY... rulemaking concerning amendments to the general bridge regulations. The rulemaking was initiated to clarify the statutory responsibilities of bridge owners to remove their bridges from navigable waterways...
75 FR 41281 - Bridge Safety Standards
Federal Register 2010, 2011, 2012, 2013, 2014
2010-07-15
...FRA is establishing Federal safety requirements for railroad bridges. This final rule requires track owners to implement bridge management programs, which include annual inspections of railroad bridges, and to audit the programs. This final rule also requires track owners to know the safe load capacity of bridges and to conduct special inspections if the weather or other conditions warrant......
Washed Out Bridge, Snake Creek Near Whitesburg
Tributary to Snake Creek, near Whitesburg, Georgia, showing a washed out bridge. When bridges such as this one collapse during a flood, it is rarely the pressure of the rushing water against the bridge that causes the bridge to fail. Rather, the rushing water erodes the ground underneath and surroun...
Paquette, Yves; Provost, Sylvie; Roy, Denis-Claude; Levine, Ross L.; Mollica, Luigina; Gary Gilliland, D.
2009-01-01
Nonrandom X-chromosome inactivation (XCI), also known as skewing, has been documented in the blood cells of a significant proportion of normal aging women by the use of methylation-based assays at the polymorphic human androgen receptor locus (HUMARA). Recent data obtained with a new transcription-based XCI determination method, termed suppressive polymerase chain reaction (PCR), has shed controversy over the validity of XCI ratio results obtained with HUMARA. To resolve this disparity, we analyzed XCI in polymorphonuclear leukocytes of a large cohort of women aged 43 to 100 years with the use of HUMARA (n = 100), a TaqMan single nucleotide polymorphism (SNP) assay (n = 90), and the suppressive polymerase chain reaction (PCR) assay (n = 67). The 3 methods yielded similar skewing incidences (42%, 38%, and 40%, respectively), and highly concordant XCI ratios. This confirms that the skewing of XCI ratio seen in blood cells of aging women is a bona fide and robust biologic phenomenon. PMID:19202126
Development of inspection robots for bridge cables.
Yun, Hae-Bum; Kim, Se-Hoon; Wu, Liuliu; Lee, Jong-Jae
2013-01-01
This paper presents the bridge cable inspection robot developed in Korea. Two types of the cable inspection robots were developed for cable-suspension bridges and cable-stayed bridge. The design of the robot system and performance of the NDT techniques associated with the cable inspection robot are discussed. A review on recent advances in emerging robot-based inspection technologies for bridge cables and current bridge cable inspection methods is also presented. PMID:24459453
Development of Inspection Robots for Bridge Cables
Kim, Se-Hoon; Lee, Jong-Jae
2013-01-01
This paper presents the bridge cable inspection robot developed in Korea. Two types of the cable inspection robots were developed for cable-suspension bridges and cable-stayed bridge. The design of the robot system and performance of the NDT techniques associated with the cable inspection robot are discussed. A review on recent advances in emerging robot-based inspection technologies for bridge cables and current bridge cable inspection methods is also presented. PMID:24459453
Skart: A skewness- and autoregression-adjusted batch-means procedure for simulation analysis
NASA Astrophysics Data System (ADS)
Tafazzoli Yazdi, Ali
We discuss Skart, an automated batch-means procedure for constructing a skewness- and autoregression-adjusted confidence interval (CI) for the steady-state mean of a simulation output process in either discrete time (i.e., observation-based statistics) or continuous time (i.e., time-persistent statistics). Skart is a sequential procedure designed to deliver a CI that satisfies user-specified requirements concerning not only the CI's coverage probability but also the absolute or relative precision provided by its half-length. Skart exploits separate adjustments to the half-length of the classical batchmeans CI so as to account for the effects on the distribution of the underlying Student's t-statistic that arise from skewness (nonnormality) and autocorrelation of the batch means. The skewness adjustment is based on a modified Cornish-Fisher expansion for the classical batch-means Student's t -ratio, and the autocorrelation adjustment is based on an autoregressive approximation to the batch-means process for sufficiently large batch sizes. Skart also delivers a point estimator for the steady-state mean that is approximately free of initialization bias. The duration of the associated warm-up period (i.e., the statistics clearing time) is based on iteratively applying von Neumann's randomness test to spaced batch means with progressively increasing batch sizes and interbatch spacer sizes. In an experimental performance evaluation involving a wide range of test processes, Skart compared favorably with other simulation analysis methods---namely, its predecessors ASAP3, WASSP, and SBatch as well as ABATCH, LBATCH, the Heidelberger-Welch procedure, and the Law-Carson procedure. Specifically, Skart exhibited competitive sampling efficiency and substantially closer conformance to the given CI coverage probabilities than the other procedures. Also presented is a nonsequential version of Skart, called N-Skart, in which the user supplies a single simulation-generated series of arbitrary length and specifies a coverage probability for a CI based on that series. In the same set of test processes previously mentioned and for a range of data-set sizes, N-Skart also achieved close conformance to the specified CI coverage probabilities.
Flight demonstration of redundancy management algorithms for a skewed array of inertial sensors
NASA Technical Reports Server (NTRS)
Morrell, F. R.; Bailey, M. L.; Motyka, P. R.
1988-01-01
Flight test results for two fault-tolerance algorithms developed for a redundant strapdown inertial measurement unit consisting of four 2-DOF gyros and accelerometers mounted on the faces of a semioctahedron are presented. Although both algorithms provided timely detection and isolation of flight control level failures, the generalized likelihood test algorithm provided more timely detection and isolation of low-level sensor failures than the edge vector test algorithm. The generalized likelihood test produced a false isolation for the case of a dual low-level failure applied to the sensitive axes of an accelerometer. Both of the algorithms were shown to provide dual fail-operational performance for the skewed array of inertial sensors.
Vargas-Madrazo, E; Lara-Ochoa, F; JimÃ©nez-MontaÃ±o, M
1994-01-01
Antibody binding site are formed by six hypervariable regions or complementarity determining regions (CDRs). The CDRs, three from the heavy chain and three from the light chain, are known as hypervariable segments and provide a surface complementary to that of the epitope. In recent work it was found that the amino acids in these positions fulfill different functions: Some play a structural role and others are involved in the specificity-determining function. It is reported here that the frequency of amino acids at hypervariable sites is skewed. By means of an informational algorithm, key physicochemical attributes of the dominant residues were identified for some of those sites. The results for about 1,500 antibodies suggest that approximately 35% of sites involved in the recognition process require only general properties such as composition, volume, and bulk or hydrogen bonding which are satisfied by a small set of amino acids instead of any one particular complementary amino acid. PMID:8151710
A cylindrical shell with an axial crack under skew-symmetric loading.
NASA Technical Reports Server (NTRS)
Yuceoglu, U.; Erdogan, F.
1973-01-01
The skew-symmetric problem for a cylindrical shell containing an axial crack is considered. It is assumed that the material has a special orthotropy - namely, that the shear modulus may be evaluated from the measured Young's moduli and Poisson ratios and is not an independent material constant. The problem is solved within the confines of an eighth-order linearized shallow shell theory. As numerical examples, the torsion of an isotropic cylinder and that of a specially orthotropic cylinder (titanium) are considered. The membrane and bending components of the stress intensity factor are calculated and are given as functions of a dimensionless shell parameter. In the torsion problem for the axially cracked cylinder the bending effects appear to be much more significant than that found for the circumferentially cracked cylindrical shell. Also, as the shell parameter increases, unlike the results found in the pressurized shell, the bending stresses around crack ends do not change sign.
The Modified Concorde Position with an Intraoperative Skew Head Rotation: Technical Note.
Takasuna, Hiroshi; Tanaka, Yuichiro
2015-01-01
The Concorde position was developed to approach pineal and cerebellar lesions with a midline suboccipital craniotomy. The neutral head position is needed to divide the occipital muscles symmetrically. The patient's head is tilted to the right and the face is turned to the right for the microscopic procedure to keep the midline of the patient's head axis straight in the surgical field for comfortable and accurate surgical manipulation. However, intraoperative repositioning of the patient's head is somewhat difficult to release the holding arm of the Sugita head holder in the original method. We found that a skew head rotation by fixing the head asymmetrically in the Sugita head holder is very quick and convenient to obtain the optimal head position both for a craniotomy and a microscopic procedure. PMID:26226983
The Modified Concorde Position with an Intraoperative Skew Head Rotation: Technical Note
TAKASUNA, Hiroshi; TANAKA, Yuichiro
2015-01-01
The Concorde position was developed to approach pineal and cerebellar lesions with a midline suboccipital craniotomy. The neutral head position is needed to divide the occipital muscles symmetrically. The patient’s head is tilted to the right and the face is turned to the right for the microscopic procedure to keep the midline of the patient’s head axis straight in the surgical field for comfortable and accurate surgical manipulation. However, intraoperative repositioning of the patient’s head is somewhat difficult to release the holding arm of the Sugita head holder in the original method. We found that a skew head rotation by fixing the head asymmetrically in the Sugita head holder is very quick and convenient to obtain the optimal head position both for a craniotomy and a microscopic procedure. PMID:26226983
Marks, Steve; Prestemon, Soren; Robin, David; Schlueter, Ross D.; Steier, Christoph; Wolski, Andrew; Jung, Jin-Young; Chubar, Oleg
2005-11-29
Three elliptically polarizing undulators (EPU) are installed and operational at the Advanced Light Source (ALS); the most recent was installed in April 2005. Operational experience has shown a variation in electron beam size which correlates with the EPU's magnetic quadrant shifts used to vary polarization. Storage ring electron dynamics studies pointed to the existence of a shift dependent skew quadrupole (SQ) component generated within the EPUs. Detailed magnetic and mechanical measurements demonstrated that the field errors were the result of systematic individual magnetic block displacements which vary with quadrant shift. This paper will discuss the results of electron dynamics studies, magnetic and mechanical measurements, design modifications planned for future EPUs to eliminate the SQ source, and the design and implementation of SQ compensation coils.
Obliterable of graphics and correction of skew using Hough transform for mobile captured documents
NASA Astrophysics Data System (ADS)
Chethan, H. K.; Kumar, G. Hemantha
2011-10-01
CBDA is an emerging field in Computer Vision and Pattern Recognition. In recent technology camera are incorporated to several electronic equipments and are very interesting and thus playing a vital role by replacing scanner with hand held imaging devices like Digital Cameras, Mobile phones and gaming devices attached with these camera. The goal of the work is to remove graphics from the document which plays a vital role in recognition of characters from the mobile captured documents. In this paper we have proposed a novel method for separating or removal of graphics like logos, animations other than the text from the document and method to reduce noise and finally textual content skew is estimated and corrected using Hough Transform. The experimental results show the efficacy compared to the result of well known existing methods.
Enhanced spin Hall effect by resonant skew scattering in the orbital-dependent Kondo effect.
Guo, Guang-Yu; Maekawa, Sadamichi; Nagaosa, Naoto
2009-01-23
The enhanced spin Hall effect in Au metal due to the resonant skew scattering is studied with first-principles band structure calculations. Especially the gigantic spin Hall angle gammaS congruent with 0.1 observed recently [T. Seki, Nature Mater. 7, 125 (2008)] is attributed to the orbital-dependent Kondo effect of Fe in the Au host metal, where the t2g orbitals are in the mixed-valence region while eg orbitals are in the Kondo limit. The enhanced spin-orbit interaction by the electron correlation in the t2g orbitals leads to the gigantic spin Hall effect. Impurities with 5d orbitals are also discussed. PMID:19257372
BRIDGE BUILDER WILLIAM FLINN?S ?CAMP & BRIDGE BUILDING OUTFIT?. INTERIOR ...
BRIDGE BUILDER WILLIAM FLINN?S ?CAMP & BRIDGE BUILDING OUTFIT?. INTERIOR VIEW SHOWING LABORERS AT MEAL TIME. - Clear Fork of Brazos River Suspension Bridge, Spanning Clear Fork of Brazos River at County Route 179, Albany, Shackelford County, TX
East elevation of lift bridge, with U.S. Rt. 11 bridge ...
East elevation of lift bridge, with U.S. Rt. 11 bridge in background. - Potomac Edison Company, Chesapeake & Ohio Canal Bridge, Spanning C & O Canal South of U.S. 11, Williamsport, Washington County, MD
Low paternity skew and the influence of maternal kin in an egalitarian, patrilocal primate
Strier, Karen B.; Chaves, Paulo B.; Mendes, SÃ©rgio L.; Fagundes, ValÃ©ria; Di Fiore, Anthony
2011-01-01
Levels of reproductive skew vary in wild primates living in multimale groups depending on the degree to which high-ranking males monopolize access to females. Still, the factors affecting paternity in egalitarian societies remain unexplored. We combine unique behavioral, life history, and genetic data to evaluate the distribution of paternity in the northern muriqui (Brachyteles hypoxanthus), a species known for its affiliative, nonhierarchical relationships. We genotyped 67 individuals (22 infants born over a 3-y period, their 21 mothers, and all 24 possible sires) at 17 microsatellite marker loci and assigned paternity to all infants. None of the 13 fathers were close maternal relatives of females with which they sired infants, and the most successful male sired a much lower percentage of infants (18%) than reported for the most successful males in other species. Our findings of inbreeding avoidance and low male reproductive skew are consistent with the muriqui's observed social and sexual behavior, but the long delay (â‰¥2.08 y) between the onset of male sexual behavior and the age at which males first sire young is unexpected. The allocation of paternity implicates individual male life histories and access to maternal kin as key factors influencing variation in paternalâ€”and grandmaternalâ€”fitness. The apparent importance of lifelong maternal investment in coresident sons resonates with other recent examinations of maternal influences on offspring reproduction. This importance also extends the implications of the â€œgrandmother hypothesisâ€ in human evolution to include the possible influence of mothers and other maternal kin on male reproductive success in patrilocal societies. PMID:22065786
Th1-skewed tissue responses to a mycolyl glycolipid in mycobacteria-infected rhesus macaques
Morita, Daisuke; Miyamoto, Ayumi; Hattori, Yuki; Komori, Takaya; Nakamura, Takashi; Igarashi, Tatsuhiko; Harashima, Hideyoshi; Sugita, Masahiko
2013-11-08
Highlights: â€¢Glucose monomycolate (GMM) is a marker glycolipid for active tuberculosis. â€¢Tissue responses to GMM involved up-regulation of Th1-attracting chemokines. â€¢Th1-skewed local responses were mounted at the GMM-injected tissue. -- Abstract: Trehalose 6,6â€²-dimycolate (TDM) is a major glycolipid of the cell wall of mycobacteria with remarkable adjuvant functions. To avoid detection by the host innate immune system, invading mycobacteria down-regulate the expression of TDM by utilizing host-derived glucose as a competitive substrate for their mycolyltransferases; however, this enzymatic reaction results in the concomitant biosynthesis of glucose monomycolate (GMM) which is recognized by the acquired immune system. GMM-specific, CD1-restricted T cell responses have been detected in the peripheral blood of infected human subjects and monkeys as well as in secondary lymphoid organs of small animals, such as guinea pigs and human CD1-transgenic mice. Nevertheless, it remains to be determined how tissues respond at the site where GMM is produced. Here we found that rhesus macaques vaccinated with Mycobacterium bovis bacillus Calmetteâ€“Guerin mounted a chemokine response in GMM-challenged skin that was favorable for recruiting T helper (Th)1 T cells. Indeed, the expression of interferon-Î³, but not Th2 or Th17 cytokines, was prominent in the GMM-injected tissue. The GMM-elicited tissue response was also associated with the expression of monocyte/macrophage-attracting CC chemokines, such as CCL2, CCL4 and CCL8. Furthermore, the skin response to GMM involved the up-regulated expression of granulysin and perforin. Given that GMM is produced primarily by pathogenic mycobacteria proliferating within the host, the Th1-skewed tissue response to GMM may function efficiently at the site of infection.
Ultra-High Energy Cosmic Rays: Composition, Early Air Shower Interactions, and Xmax Skewness
NASA Astrophysics Data System (ADS)
Stapleton, James
The composition of Ultra-High Energy Cosmic Rays (UHECRs) is still not completely understood, and must be inferred from Extended Air Shower (EAS), particle cascades which they initiate upon entering the atmosphere. The atmospheric depth at which the shower contains the maximum number of particles ( Xmax) is the most composition-sensitive property of the air shower, but its interpretation is hindered by intrinsic statistical fluctuations in EAS development which cause distinct compositions to produce overlapping Xmax distributions as well as our limited knowledge at these energies of hadronic physics which strongly impacts the Xmax distribution's shape. These issues ultimately necessitate a variety of complementary approaches to interpreting UHECR composition from Xmax data. The current work advances these approaches by connecting X max skewness to the uncertainties above. The study of X max has historically focused only on the mean and standard deviation of its distribution, but skewness is shown here to be strongly related to both the statistical fluctuations in EAS development as well as the least-understood hadronic cross-sections in the air shower. This leads into a treatment of the Exponentially-Modified Gaussian (EMG) distribution, whose little-known properties make it very useful for Xmax analysis and for data analysis in general. A powerful method emerges which uses only descriptive statistics in a robust check for energy-dependent changes in UHECR mass or EAS development. The application of these analyses to X max data provides tantalizing clues concerning issues of critical importance, such as the relationship between Xmax and the 'ankle' break in the UHECR energy spectrum, or the inferred properties of the UHECR mass distribution and its strong dependence on hadronic model systematics.
Does predation result in adult sex ratio skew in a sexually dimorphic insect genus?
Wehi, P M; Nakagawa, S; Trewick, S A; Morgan-Richards, M
2011-11-01
Theory proposes that sexually dimorphic, polygynous species are at particularly high risk of sex-biased predation, because conspicuous males are more often preyed upon compared to females. We tested the effects of predation on population sex ratio in a highly sexually dimorphic insect genus (Hemideina). In addition, introduction of a suite of novel mammalian predators to New Zealand during the last 800 years is likely to have modified selection pressures on native tree weta. We predicted that the balance between natural and sexual selection would be disrupted by the new predator species. We expected to see a sex ratio skew resulting from higher mortality in males with expensive secondary sexual weaponry; combat occurs outside refuge cavities between male tree weta. We took a meta-analytic approach using generalized linear mixed models to compare sex ratio variation in 58 populations for six of the seven species in Hemideina. We investigated adult sex ratio across these populations to determine how much variation in sex ratio can be attributed to sex-biased predation in populations with either low or high number of invasive mammalian predators. Surprisingly, we did not detect any significant deviation from 1 : 1 parity for adult sex ratio and found little difference between populations or species. We conclude that there is little evidence of sex-biased predation by either native or mammalian predators and observed sex ratio skew in individual populations of tree weta is probably an artefact of sampling error. We argue that sex-biased predation may be less prevalent in sexually dimorphic species than previously suspected and emphasize the usefulness of a meta-analytic approach to robustly analyse disparate and heterogeneous data. PMID:21848984
A missing model in reproductive skew theory: the bordered tug-of-war.
Reeve, Hudson Kern; Shen, Sheng-Feng
2006-05-30
Models of reproductive skew can be classified into two groups: transactional models, in which group members yield shares of reproduction to each other in return for cooperation, and tug-of-war models, in which group members invest group resources in a tug-of-war over their respective reproductive shares. We synthesize these two models to yield a "bordered tug-of-war" model in which the internal tug-of-war is limited ("bordered") by the requirement that group members must achieve a certain amount of reproduction lest they pursue a noncooperative option leading to group breakup. Previous attempts to synthesize these two models did not allow for the fact that the tug-of-war will affect group output, which in turn feeds back on the reproductive payments required by group members to remain cooperative. The bordered tug-of-war model, which does not assume complete reproductive control by any individual and allows for conflict within groups, predicts that the degree of within-group selfishness will increase as the noncooperative options become less attractive, e.g., as ecological constraints on solitary breeding increase. When the noncooperative option involves fighting for the group resource (e.g., territory) and leaving if the fight is lost, the subordinate's overall share of reproduction is predicted to be independent of its relatedness to the dominant and to increase the greater its probability of winning the fight, the less the value of the territory, and the greater its personal payoff for leaving. The unique predictions of the bordered tug-of-war model may fit skew data from a number of species, including meerkats, lions, and wood mice. PMID:16717185
Floating liquid bridge charge dynamics
NASA Astrophysics Data System (ADS)
Teschke, Omar; Soares, David Mendez; Gomes, Whyllerson Evaristo; Valente Filho, Juracyr Ferraz
2016-01-01
The interaction of liquid with electric fields is investigated in a configuration where up to 13 kV are applied between electrodes resulting in a 106 V/m electric field in the capillaries and where there is the formation of a free-standing fluid bridge in the interelectrode gap. The Mott-Gurney equation was fitted to the measured ionization current vs applied voltage curve which indicates that the ionization rate at the high-voltage anode electrode dimethylsulfoxide (DMSO) interface and space charging in the interelectrode gap determine the floating liquid bridge current for a given cathode-to-anode voltage. Space charge effects were measured in the cathode becker and also at the liquid bridge since the ionized charges at the anode migrate to the bridge outer surface and decrease the interfacial tension from 43 mJ/m2 to 29 mJ/m2. Two distinct structural regions then form the bridge, a charged plastic (bulk modulus ˜100 MPa) conducting outer layer with a surface conductivity of ˜10-9 ?-1, which shapes and supports the floating fluid structure, and an inner liquid cylinder, where DMSO molecules flow.
47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 47 Telecommunication 5 2014-10-01 2014-10-01 false Watch required by the Bridge-to-Bridge Act. 80... Safety Watches Â§ 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch requirement contained in Â§ 80.148, all vessels subject to the Bridge-to-Bridge Act must keep a watch on the...
47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 47 Telecommunication 5 2012-10-01 2012-10-01 false Watch required by the Bridge-to-Bridge Act. 80... Safety Watches Â§ 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch requirement contained in Â§ 80.148, all vessels subject to the Bridge-to-Bridge Act must keep a watch on the...
47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 47 Telecommunication 5 2011-10-01 2011-10-01 false Watch required by the Bridge-to-Bridge Act. 80... Safety Watches Â§ 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch requirement contained in Â§ 80.148, all vessels subject to the Bridge-to-Bridge Act must keep a watch on the...
47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 47 Telecommunication 5 2013-10-01 2013-10-01 false Watch required by the Bridge-to-Bridge Act. 80... Safety Watches Â§ 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch requirement contained in Â§ 80.148, all vessels subject to the Bridge-to-Bridge Act must keep a watch on the...
47 CFR 80.309 - Watch required by the Bridge-to-Bridge Act.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 47 Telecommunication 5 2010-10-01 2010-10-01 false Watch required by the Bridge-to-Bridge Act. 80... Safety Watches Â§ 80.309 Watch required by the Bridge-to-Bridge Act. In addition to the watch requirement contained in Â§ 80.148, all vessels subject to the Bridge-to-Bridge Act must keep a watch on the...
NASA Astrophysics Data System (ADS)
Mejia-Ospino, E.; García, G.; Guerrero, A.; Alvarez, I.; Cisneros, C.
2005-01-01
The three-photon resonance four-photon ionization and dissociation spectra of dimethyl ether (DME) are presented in the wavelength range 450-550 nm at 1 nm intervals. The (3+1) REMPI spectra show three prominent bands corresponding to the \\tildeB \\leftarrow \\skew1\\tildeX, {\\skew1\\tildeC} \\leftarrow \\skew1\\tildeX and {\\skew1\\tildeC^{\\prime}} \\leftarrow \\skew1\\tildeX transitions with origins at 61 457 cm-1 (7.615 eV), 59 055 cm-1 (7.322 eV) and 58 010 cm-1 (7.194 eV), respectively. Several ionized species, CH3+, CHnO+ (n = 1-3) and CH3OCH3+, are observed in the region of wavelengths studied here. In order to compare the results, a shorter wavelength multiphoton dissociation and ionization of DME at 355 nm is also presented. At this wavelength, DME undergoes neutral dissociation to CH3 and CH3O and each fragment is then ionized by multiphoton absorption. The fragmentation at 355 nm is very intense and only small fragments such as CH3+, CHO+, CH2+, CH+ and C+ ions are observed. The measurement of photoelectron energy allows us to establish that the DME ionization potential is at least 9.55 ± 0.15 eV. The experiments were performed using a Nd:YAG-OPO (optical parametric oscillator) tunable laser system coupled to a time-of-flight mass spectrometer and a hemispherical electron energy analyser.
Kalkan, E.; Kwong, N.
2012-01-01
The earthquake engineering profession is increasingly utilizing nonlinear response history analyses (RHA) to evaluate seismic performance of existing structures and proposed designs of new structures. One of the main ingredients of nonlinear RHA is a set of ground motion records representing the expected hazard environment for the structure. When recorded motions do not exist (as is the case in the central United States) or when high-intensity records are needed (as is the case in San Francisco and Los Angeles), ground motions from other tectonically similar regions need to be selected and scaled. The modal-pushover-based scaling (MPS) procedure was recently developed to determine scale factors for a small number of records such that the scaled records provide accurate and efficient estimates of â€œtrueâ€ median structural responses. The adjective â€œaccurateâ€ refers to the discrepancy between the benchmark responses and those computed from the MPS procedure. The adjective â€œefficientâ€ refers to the record-to-record variability of responses. In this paper, the accuracy and efficiency of the MPS procedure are evaluated by applying it to four types of existing Ordinary Standard bridges typical of reinforced concrete bridge construction in California. These bridges are the single-bent overpass, multi-span bridge, curved bridge, and skew bridge. As compared with benchmark analyses of unscaled records using a larger catalog of ground motions, it is demonstrated that the MPS procedure provided an accurate estimate of the engineering demand parameters (EDPs) accompanied by significantly reduced record-to-record variability of the EDPs. Thus, it is a useful tool for scaling ground motions as input to nonlinear RHAs of Ordinary Standard bridges.
Kalkan, Erol; Kwong, Neal S.
2010-01-01
The earthquake engineering profession is increasingly utilizing nonlinear response history analyses (RHA) to evaluate seismic performance of existing structures and proposed designs of new structures. One of the main ingredients of nonlinear RHA is a set of ground-motion records representing the expected hazard environment for the structure. When recorded motions do not exist (as is the case for the central United States), or when high-intensity records are needed (as is the case for San Francisco and Los Angeles), ground motions from other tectonically similar regions need to be selected and scaled. The modal-pushover-based scaling (MPS) procedure recently was developed to determine scale factors for a small number of records, such that the scaled records provide accurate and efficient estimates of 'true' median structural responses. The adjective 'accurate' refers to the discrepancy between the benchmark responses and those computed from the MPS procedure. The adjective 'efficient' refers to the record-to-record variability of responses. Herein, the accuracy and efficiency of the MPS procedure are evaluated by applying it to four types of existing 'ordinary standard' bridges typical of reinforced-concrete bridge construction in California. These bridges are the single-bent overpass, multi span bridge, curved-bridge, and skew-bridge. As compared to benchmark analyses of unscaled records using a larger catalog of ground motions, it is demonstrated that the MPS procedure provided an accurate estimate of the engineering demand parameters (EDPs) accompanied by significantly reduced record-to-record variability of the responses. Thus, the MPS procedure is a useful tool for scaling ground motions as input to nonlinear RHAs of 'ordinary standard' bridges.
NASA Astrophysics Data System (ADS)
Pipie?, M.
2008-09-01
We present the results of an application of Bayesian inference in testing the relation between risk and return on the financial instruments. On the basis of the Intertemporal Capital Asset Pricing Model, proposed by Merton we built a general sampling distribution suitable in analysing this relationship. The most important feature of our assumptions is that the skewness of the conditional distribution of returns is used as an alternative source of relation between risk and return. This general specification relates to Skewed Generalized Autoregressive Conditionally Heteroscedastic-in-Mean model. In order to make conditional distribution of financial returns skewed we considered the unified approach based on the inverse probability integral transformation. In particular, we applied hidden truncation mechanism, inverse scale factors, order statistics concept, Beta and Bernstein distribution transformations and also a constructive method. Based on the daily excess returns on the Warsaw Stock Exchange Index we checked the empirical importance of the conditional skewness assumption on the relation between risk and return on the Warsaw Stock Market. We present posterior probabilities of all competing specifications as well as the posterior analysis of the positive sign of the tested relationship.
ERIC Educational Resources Information Center
Cooper, David
2015-01-01
The paper looks closely at student enrolment trends through a case study of South African "race" enrolment data, including some hypotheses about how student social class has influenced these trends. First, data on 1988-1998 enrolments showing a "skewed revolution" in student africanisation are summarised. Then, using 2000-2012…
Balanced bridge feedback control system
NASA Technical Reports Server (NTRS)
Lurie, Boris J. (inventor)
1990-01-01
In a system having a driver, a motor, and a mechanical plant, a multiloop feedback control apparatus for controlling the movement and/or positioning of a mechanical plant, the control apparatus has a first local bridge feedback loop for feeding back a signal representative of a selected ratio of voltage and current at the output driver, and a second bridge feedback loop for feeding back a signal representative of a selected ratio of force and velocity at the output of the motor. The control apparatus may further include an outer loop for feeding back a signal representing the angular velocity and/or position of the mechanical plant.
Bridging the Vector Calculus Gap
NASA Astrophysics Data System (ADS)
Dray, Tevian; Manogue, Corinne
2003-05-01
As with Britain and America, mathematicians and physicists are separated from each other by a common language. In a nutshell, mathematics is about functions, but physics is about things. For the last several years, we have led an NSF-supported effort to "bridge the vector calculus gap" between mathematics and physics. The unifying theme we have discovered is to emphasize geometric reasoning, not (just) algebraic computation. In this talk, we will illustrate the language differences between mathematicians and physicists, and how we are trying reconcile them in the classroom. For further information about the project go to: http://www.physics.orst.edu/bridge
Excitation Methods for Bridge Structures
Farrar, C.R.; Duffy, T.A.; Cornwell, P.J.; Doebling, S.W.
1999-02-08
This paper summarizes the various methods that have been used to excited bridge structures during dynamic testing. The excitation methods fall into the general categories of ambient excitation methods and measured-input excitation methods. During ambient excitation the input to the bridge is not directly measured. In contrast, as the category label implies, measured-input excitations are usually applied at a single location where the force input to the structure can be monitored. Issues associated with using these various types of measurements are discussed along with a general description of the various excitation methods.
27. VIEW SHOWING SOUTH ELEVATION OF NOTRE DAM BRIDGE, LOOKING ...
27. VIEW SHOWING SOUTH ELEVATION OF NOTRE DAM BRIDGE, LOOKING NORTHEAST Ernest Gould, photographer, 1987 - Notre Dame Bridge, Spanning Merrimack River on Bridge Street, Manchester, Hillsborough County, NH
Veilleux, Andrea G.; Stedinger, Jery R.; Eash, David A.
2012-01-01
This paper summarizes methodological advances in regional log-space skewness analyses that support flood-frequency analysis with the log Pearson Type III (LP3) distribution. A Bayesian Weighted Least Squares/Generalized Least Squares (B-WLS/B-GLS) methodology that relates observed skewness coefficient estimators to basin characteristics in conjunction with diagnostic statistics represents an extension of the previously developed B-GLS methodology. B-WLS/B-GLS has been shown to be effective in two California studies. B-WLS/B-GLS uses B-WLS to generate stable estimators of model parameters and B-GLS to estimate the precision of those B-WLS regression parameters, as well as the precision of the model. The study described here employs this methodology to develop a regional skewness model for the State of Iowa. To provide cost effective peak-flow data for smaller drainage basins in Iowa, the U.S. Geological Survey operates a large network of crest stage gages (CSGs) that only record flow values above an identified recording threshold (thus producing a censored data record). CSGs are different from continuous-record gages, which record almost all flow values and have been used in previous B-GLS and B-WLS/B-GLS regional skewness studies. The complexity of analyzing a large CSG network is addressed by using the B-WLS/B-GLS framework along with the Expected Moments Algorithm (EMA). Because EMA allows for the censoring of low outliers, as well as the use of estimated interval discharges for missing, censored, and historic data, it complicates the calculations of effective record length (and effective concurrent record length) used to describe the precision of sample estimators because the peak discharges are no longer solely represented by single values. Thus new record length calculations were developed. The regional skewness analysis for the State of Iowa illustrates the value of the new B-WLS/BGLS methodology with these new extensions.
Intercellular bridges in vertebrate gastrulation.
Caneparo, Luca; Pantazis, Periklis; Dempsey, William; Fraser, Scott E
2011-01-01
The developing zebrafish embryo has been the subject of many studies of regional patterning, stereotypical cell movements and changes in cell shape. To better study the morphological features of cells during gastrulation, we generated mosaic embryos expressing membrane attached Dendra2 to highlight cellular boundaries. We find that intercellular bridges join a significant fraction of epiblast cells in the zebrafish embryo, reaching several cell diameters in length and spanning across different regions of the developing embryos. These intercellular bridges are distinct from the cellular protrusions previously reported as extending from hypoblast cells (1-2 cellular diameters in length) or epiblast cells (which were shorter). Most of the intercellular bridges were formed at pre-gastrula stages by the daughters of a dividing cell maintaining a membrane tether as they move apart after mitosis. These intercellular bridges persist during gastrulation and can mediate the transfer of proteins between distant cells. These findings reveal a surprising feature of the cellular landscape in zebrafish embryos and open new possibilities for cell-cell communication during gastrulation, with implications for modeling, cellular mechanics, and morphogenetic signaling. PMID:21647454
The Bridge to Manufacturing Project
ERIC Educational Resources Information Center
Puchner, Laurel; Taylor, Ann R.; Harris, Valorie K.; Marshall, Rick W.; Powell, Margaret
2010-01-01
A grant project was designed to facilitate the transition of students from a community college adult education program into a community college credit-degree program in manufacturing. Key features of the program included a focus on identifying policy implications; bridging the separation between the adult education segment of the community college…
ERIC Educational Resources Information Center
Anderson, Richard
2008-01-01
Career and technical education (CTE) has a promising future at Darlington (WI) High School. In this article, the author describes how a class bridge project became a real-world, project-based learning opportunity involving higher-level thinking skills that are at the core of CTE at his school. It began when a local citizen approached him at the…
Bridging Traditional and Authentic Assessment.
ERIC Educational Resources Information Center
Cole, Donna J.
With the education reform movement came dissonance over testing as an indicator of classroom learning. This paper examines both formal and informal assessment and relates one institution's attempt to provide a bridge between authentic and traditional assessment. Authentic assessment is defined as a belief that student evaluation should measureâ€¦
ERIC Educational Resources Information Center
Anderson, Richard
2008-01-01
Career and technical education (CTE) has a promising future at Darlington (WI) High School. In this article, the author describes how a class bridge project became a real-world, project-based learning opportunity involving higher-level thinking skills that are at the core of CTE at his school. It began when a local citizen approached him at theâ€¦
Percentage Problems in Bridging Courses
ERIC Educational Resources Information Center
Kachapova, Farida; Kachapov, Ilias
2012-01-01
Research on teaching high school mathematics shows that the topic of percentages often causes learning difficulties. This article describes a method of teaching percentages that the authors used in university bridging courses. In this method, the information from a word problem about percentages is presented in a two-way table. Such a table gives…
Bridging: Locating Critical Connectors in a Network
Valente, Thomas W.; Fujimoto, Kayo
2010-01-01
This paper proposes several measures for bridging in networks derived from Granovetter's (1973) insight that links which reduce distances in a network are important structural bridges. Bridging is calculated by systematically deleting links and calculating the resultant changes in network cohesion (measured as the inverse average path length). The average change for each node's links provides an individual level measure of bridging. We also present a normalized version which controls for network size and a network level bridging index. Bridging properties are demonstrated on hypothetical networks, empirical networks, and a set of 100 randomly generated networks to show how the bridging measure correlates with existing network measures such as degree, personal network density, constraint, closeness centrality, betweenness centrality, and vitality. Bridging and the accompanying methodology provide a family of new network measures useful for studying network structure, network dynamics, and network effects on substantive behavioral phenomenon. PMID:20582157
NPIP: A skew line needle configuration optimization system for HDR brachytherapy
Siauw, Timmy; Cunha, Adam; Berenson, Dmitry; Atamtuerk, Alper; Hsu, I-Chow; Goldberg, Ken; Pouliot, Jean
2012-07-15
Purpose: In this study, the authors introduce skew line needle configurations for high dose rate (HDR) brachytherapy and needle planning by integer program (NPIP), a computational method for generating these configurations. NPIP generates needle configurations that are specific to the anatomy of the patient, avoid critical structures near the penile bulb and other healthy structures, and avoid needle collisions inside the body. Methods: NPIP consisted of three major components: a method for generating a set of candidate needles, a needle selection component that chose a candidate needle subset to be inserted, and a dose planner for verifying that the final needle configuration could meet dose objectives. NPIP was used to compute needle configurations for prostate cancer data sets from patients previously treated at our clinic. NPIP took two user-parameters: a number of candidate needles, and needle coverage radius, {delta}. The candidate needle set consisted of 5000 needles, and a range of {delta} values was used to compute different needle configurations for each patient. Dose plans were computed for each needle configuration. The number of needles generated and dosimetry were analyzed and compared to the physician implant. Results: NPIP computed at least one needle configuration for every patient that met dose objectives, avoided healthy structures and needle collisions, and used as many or fewer needles than standard practice. These needle configurations corresponded to a narrow range of {delta} values, which could be used as default values if this system is used in practice. The average end-to-end runtime for this implementation of NPIP was 286 s, but there was a wide variation from case to case. Conclusions: The authors have shown that NPIP can automatically generate skew line needle configurations with the aforementioned properties, and that given the correct input parameters, NPIP can generate needle configurations which meet dose objectives and use as many or fewer needles than the current HDR brachytherapy workflow. Combined with robot assisted brachytherapy, this system has the potential to reduce side effects associated with treatment. A physical trial should be done to test the implant feasibility of NPIP needle configurations.
Structural Bridges through Fold Space
Edwards, Hannah; Deane, Charlotte M.
2015-01-01
Several protein structure classification schemes exist that partition the protein universe into structural units called folds. Yet these schemes do not discuss how these units sit relative to each other in a global structure space. In this paper we construct networks that describe such global relationships between folds in the form of structural bridges. We generate these networks using four different structural alignment methods across multiple score thresholds. The networks constructed using the different methods remain a similar distance apart regardless of the probability threshold defining a structural bridge. This suggests that at least some structural bridges are method specific and that any attempt to build a picture of structural space should not be reliant on a single structural superposition method. Despite these differences all representations agree on an organisation of fold space into five principal community structures: all-Î±, all-Î² sandwiches, all-Î² barrels, Î±/Î² and Î± + Î². We project estimated fold ages onto the networks and find that not only are the pairings of unconnected folds associated with higher age differences than bridged folds, but this difference increases with the number of networks displaying an edge. We also examine different centrality measures for folds within the networks and how these relate to fold age. While these measures interpret the central core of fold space in varied ways they all identify the disposition of ancestral folds to fall within this core and that of the more recently evolved structures to provide the peripheral landscape. These findings suggest that evolutionary information is encoded along these structural bridges. Finally, we identify four highly central pivotal folds representing dominant topological features which act as key attractors within our landscapes. PMID:26372166
Structural Bridges through Fold Space.
Edwards, Hannah; Deane, Charlotte M
2015-09-01
Several protein structure classification schemes exist that partition the protein universe into structural units called folds. Yet these schemes do not discuss how these units sit relative to each other in a global structure space. In this paper we construct networks that describe such global relationships between folds in the form of structural bridges. We generate these networks using four different structural alignment methods across multiple score thresholds. The networks constructed using the different methods remain a similar distance apart regardless of the probability threshold defining a structural bridge. This suggests that at least some structural bridges are method specific and that any attempt to build a picture of structural space should not be reliant on a single structural superposition method. Despite these differences all representations agree on an organisation of fold space into five principal community structures: all-Î±, all-Î² sandwiches, all-Î² barrels, Î±/Î² and Î± + Î². We project estimated fold ages onto the networks and find that not only are the pairings of unconnected folds associated with higher age differences than bridged folds, but this difference increases with the number of networks displaying an edge. We also examine different centrality measures for folds within the networks and how these relate to fold age. While these measures interpret the central core of fold space in varied ways they all identify the disposition of ancestral folds to fall within this core and that of the more recently evolved structures to provide the peripheral landscape. These findings suggest that evolutionary information is encoded along these structural bridges. Finally, we identify four highly central pivotal folds representing dominant topological features which act as key attractors within our landscapes. PMID:26372166
77 FR 53251 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation
Federal Register 2010, 2011, 2012, 2013, 2014
2012-08-31
... Federal Highway Administration Annual Materials Report on New Bridge Construction and Bridge... Secretary of Transportation to publish in the Federal Register a report describing construction materials used in new Federal-aid bridge construction and bridge rehabilitation projects. As part of the...
Bridge Programs in Illinois: Results of the 2010 Illinois Bridge Status Survey
ERIC Educational Resources Information Center
Taylor, J. L.; Harmon, T.
2010-01-01
This report provides a summary of major results of the Illinois Bridge Status Survey, administered online between April and June 2010. The purpose of the survey was to understand the extent to which bridge programs are being implemented in Illinois, as well as to build an online directory of bridge programs. Bridge programs are an emergingâ€¦
49 CFR 236.713 - Bridge, movable.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Bridge, movable. 236.713 Section 236.713 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Bridge, movable. That section of a structure bridging a navigable waterway so designed that it may...
49 CFR 236.713 - Bridge, movable.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 4 2013-10-01 2013-10-01 false Bridge, movable. 236.713 Section 236.713 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Bridge, movable. That section of a structure bridging a navigable waterway so designed that it may...
49 CFR 236.713 - Bridge, movable.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Bridge, movable. 236.713 Section 236.713 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Bridge, movable. That section of a structure bridging a navigable waterway so designed that it may...
Remediation: Higher Education's Bridge to Nowhere
ERIC Educational Resources Information Center
Complete College America, 2012
2012-01-01
The intentions were noble. It was hoped that remediation programs would be an academic bridge from poor high school preparation to college readiness. Sadly, remediation has become instead higher education's "Bridge to Nowhere." This broken remedial bridge is travelled by some 1.7 million beginning students each year, most of whom will not reachâ€¦
49 CFR 236.713 - Bridge, movable.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 4 2014-10-01 2014-10-01 false Bridge, movable. 236.713 Section 236.713 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Bridge, movable. That section of a structure bridging a navigable waterway so designed that it may...
49 CFR 236.713 - Bridge, movable.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Bridge, movable. 236.713 Section 236.713 Transportation Other Regulations Relating to Transportation (Continued) FEDERAL RAILROAD ADMINISTRATION... Bridge, movable. That section of a structure bridging a navigable waterway so designed that it may...
A Participatory Public Art Project: Community Bridge
ERIC Educational Resources Information Center
Stephens, Pam
2005-01-01
This article introduces Community Bridge, a participatory public art project that brought together artists and residents to address aesthetic needs of an urban environment. The Community Bridge is an exemplary work of art by American artist William Cochran. In addition to creating a natural gathering place for residents of all ages, the bridge is…
Building Bridges One Line at a Time
ERIC Educational Resources Information Center
Grigsby, Cathy Murray
2012-01-01
In this article, first-grade students were taught the different kinds of lines that were part of the construction of various bridges--the curved lines of the arches of stone bridges, straight lines connecting the cables of a suspension bridge, vertical lines, horizontal lines, and so on. They gained practice in drawing structures and in fine brush…
Building Bridges One Line at a Time
ERIC Educational Resources Information Center
Grigsby, Cathy Murray
2012-01-01
In this article, first-grade students were taught the different kinds of lines that were part of the construction of various bridges--the curved lines of the arches of stone bridges, straight lines connecting the cables of a suspension bridge, vertical lines, horizontal lines, and so on. They gained practice in drawing structures and in fine brushâ€¦
12. View of bridge seat at north abutment with expansion ...
12. View of bridge seat at north abutment with expansion bearing, under bridge at northwest corner of bridge, looking from the east - Bridge No. 4900, Spanning Root River at Trunk Highway 16, Rushford, Fillmore County, MN
28. Under ninth bridge, view to concrete dam and eighth ...
28. Under ninth bridge, view to concrete dam and eighth bridge in background during heavy rain, view to the SW. - Vicksburg National Military Park Roads & Bridges, Melan Arch Bridges, Spanning various tributaries at Confederate Avenue, Vicksburg, Warren County, MS
The Impact of male reproductive skew on kin structure and sociality in multi-male groups.
Widdig, Anja
2013-01-01
Patterns of within-group relatedness are expected to affect the prospects for cooperation among group members through kin selection. It has long been established that dispersal patterns determine the availability of kin and there is ample evidence of matrilineal kin biases in social behavior across primate species. However, in 1979, Jeanne Altmann(1) suggested that mating patterns also influence the structure of within-group relatedness; high male reproductive skew and the frequent replacement of breeding males leads to relatively high levels of paternal relatedness and age-structured paternal sibships within groups. As a consequence of frequent replacement of breeding males, relatedness among offspring of a given female will be reduced to the half- rather than full-sibling level. Depending on the number of sires and degree of relatedness among mothers, members of the same birth cohort may be as closely related as maternal siblings. If animals are able to recognize their paternal kin and exhibit biases in favor of them, this may influence the distribution of cooperation and the intensity of competition within groups of primates. Here, I summarize the evidence that serves as the basis for Altmann's predictions and review evidence regarding whether or not the availability of paternal kin also leads to paternal kin bias among primates. PMID:24166924
Dodla, Ramana; Wilson, Charles J
2013-10-01
We investigate why electrically coupled neuronal oscillators synchronize or fail to synchronize using the theory of weakly coupled oscillators. Stability of synchrony and antisynchrony is predicted analytically and verified using numerical bifurcation diagrams. The shape of the phase response curve (PRC), the shape of the voltage time course, and the frequency of spiking are freely varied to map out regions of parameter spaces that hold stable solutions. We find that type 1 and type 2 PRCs can hold both synchronous and antisynchronous solutions, but the shape of the PRC and the voltage determine the extent of their stability. This is achieved by introducing a five-piecewise linear model to the PRC and a three-piecewise linear model to the voltage time course, and then analyzing the resultant eigenvalue equations that determine the stability of the phase-locked solutions. A single time parameter defines the skewness of the PRC, and another single time parameter defines the spike width and frequency. Our approach gives a comprehensive picture of the relation of the PRC shape, voltage time course, and stability of the resultant synchronous and antisynchronous solutions. PMID:23777519
NASA Astrophysics Data System (ADS)
Hirotsuka, Isao; Tsuboi, Kazuo
The capacitor motor (CRM) is widely used to drive industrial equipments and electric home appliances. Recently, the reduction in the vibration and noise of the CRM has become increasingly important from the standpoint of environmental improvement. However, the electromagnetic vibration of the CRM under load has not been analyzed sufficiently. Therefore, we have studied the electromagnetic vibration of CRM for the purpose of reducing it. In a previous paper, the relationships for a backward magnetic field, the equivalent circuit current, and the vibration of the CRM were clarified. The present paper theoretically and experimentally discusses the effect of the slot combination and skewed slot on the electromagnetic vibration of CRM under load. The primary conclusions are as follows: (1) In the case of 4-pole and 6-pole CRMs, the dominant electromagnetic vibration of CRMs was theoretically attributed to three types of electromagnetic force waves. Two types of electromagnetic force waves are generated: one wave is generated by the interaction of two forward magnetic fluxes, such as those of a three-phase squirrel-cage induction motor, and the other wave is generated under the influence of a backward magnetic flux. (2) The characteristics of dominant electromagnetic vibration depending on load and running capacitor were classified theoretically and experimentally into three types based on the characteristics of the electromagnetic force wave and equivalent circuit current. (3) The influences of magnetic saturation in dominant electromagnetic vibration were verified experimentally and their causes were clarified theoretically in relation to electromagnetic force waves.
NASA Astrophysics Data System (ADS)
Alfarano, S.; Lux, T.; Wagner, F.
2007-01-01
The present paper expands on recent attempts at estimating the parameters of simple interacting-agent models of financial markets [S. Alfarano, T. Lux, F. Wagner, Computational Economics 26, 19 (2005); S. Alfarano, T. Lux, F. Wagner, in FunktionsfÃ¤higkeit und StabilitÃ¤t von FinanzmÃ¤rkten, edited by W. Franz, H. Ramser, M. Stadler (Mohr Siebeck, TÃ¼bingen, 2005), pp. 241 254]. Here we provide additional evidence by (i) investigating a large sample of individual stocks from the Tokyo Stock Exchange, and (ii) comparing results from the baseline noise trader/fundamentalist model of [S. Alfarano, T. Lux, F. Wagner, Computational Economics 26, 19 (2005)] with those obtained from an even simpler version with a preponderance of noise trader behaviour. As it turns out, this somewhat more parsimonious â€œmaximally skewedâ€ variant is often not rejected in favor of the more complex version. We also find that all stocks are dominated by noise trader behaviour irrespective of whether the data prefer the skewed or the baseline version of our model.
Mutation skew in genes identified by genome-wide association study of hypertriglyceridemia
Johansen, Christopher T.; Wang, Jian; Lanktree, Matthew B.; Cao, Henian; McIntyre, Adam D.; Ban, Matthew R.; Martins, Rebecca A.; Kennedy, Brooke A.; Hassell, Reina G.; Visser, Maartje E.; Schwartz, Stephen M.; Voight, Benjamin F.; Elosua, Roberto; Salomaa, Veikko; O'Donnell, Christopher J.; Dallinga-Thie, Geesje M.; Anand, Sonia S.; Yusuf, Salim; Huff, Murray W.; Kathiresan, Sekar; Hegele, Robert A.
2010-01-01
Genome-wide association studies (GWAS) have replicably identified multiple loci associated with population-based plasma lipid concentrations1-5. Common genetic variants at these loci together explain <10% of the total variation of each lipid trait4,5. Rare variants of individually large effect may contribute additionally to the “missing heritability” of lipid traits6,7, however it remains to be shown to what extent rare variants will affect lipid phenotypes. Here, we demonstrate a significant accumulation of rare variants in GWAS-identified genes in patients with an extreme phenotype of abnormal plasma triglyceride (TG) metabolism. A GWAS of hypertriglyceridemia (HTG) patients revealed that common variants in APOA5, GCKR, LPL and APOB genes were associated with the HTG phenotype at genome-wide significance. We subsequently resequenced protein coding regions of these genes and found a significant burden of 154 rare missense or nonsense variants in 438 HTG patients, in contrast to 53 variants in 327 controls (P=6.2X10-8); this corresponds to a carrier frequency of 28.1% of HTG patients and 15.3% of controls (P=2.6X10-5). Many rare variants were predicted in silico to have compromised function; additionally some had previously demonstrated dysfunctionality in vitro. Rare variants in these 4 genes explained 1.1% of total variation in HTG diagnoses. Our study demonstrates a marked mutation skew that likely contributes to disease pathophysiology in patients with HTG. PMID:20657596
Dynamics of ferromagnetic spin glass: randomly canted ferromagnet versus skewed spin glass
NASA Astrophysics Data System (ADS)
Janutka, Andrzej
2003-12-01
A ferromagnetic spin glass (FSG) is one of the three isotropic and homogeneous phases of the long-range partially ordered magnets with spin and atomic disorder which are selected by symmetry (Andreev 1978 Sov. Phys.â€”JETP 47 411) (the others are genuine and antiferromagnetic spin glasses). The linear dynamical response to a magnetic field of two sub-phases of a FSG with drastically different dynamics, a randomly canted ferromagnet, in which the component spins create an acute angle with the summary magnetic moment, and a less-ordered skewed spin glass is analysed in the spin-wave approximation in the framework of phenomenological theory. The spin-wave damping coefficients and frequency shifts due to a magnon-magnon interaction are evaluated as functions of temperature and wavevector as well as the spectral-weight functions of the linear response to a magnetic field and the neutron scattering cross section which provides the possibility for experimental verification of the results. Substantial differences in the spin-wave characteristics of the FSG compared to those of the Heisenberg spin glass and the Heisenberg ferromagnet are found to be due to non-linear anisotropy effects in a FSG.
Net-proton-number kurtosis and skewness in nuclear collisions: Influence of deuteron formation
NASA Astrophysics Data System (ADS)
Fecková, Zuzana; Steinheimer, Jan; Tomášik, Boris; Bleicher, Marcus
2015-12-01
We explore the influence of deuteron formation in the late stage of nucleus-nucleus reactions on the fluctuations observed in the final net-proton yields around midrapidity. At each investigated energy, the produced (anti)proton yield at chemical freeze-out is assumed to fluctuate according to a Poisson distribution and in each event the probability for deuteron formation by coalescence is proportional to (dNproton/d y ) 2. The protons that are then clustered in deuterons are usually not included in the experimental measurement of the net-proton fluctuations, therefore, we subtract these clustered protons from the final state proton number for the calculation of the net-proton fluctuations (the same is done in the antiproton sector). Due to the nonlinear deuteron formation probability the resulting distribution is not a Skellam distribution, but shows the interesting feature of a decrease in the kurtosis ? ?2 and a local maximum in the skewness S ? observables as the collision energy decreases.
Dodla, Ramana; Wilson, Charles J.
2013-01-01
We investigate why electrically coupled neuronal oscillators synchronize or fail to synchronize using the theory of weakly coupled oscillators. Stability of synchrony and antisynchrony is predicted analytically and verified using numerical bifurcation diagrams. The shape of the phase response curve (PRC), the shape of the voltage time course, and the frequency of spiking are freely varied to map out regions of parameter spaces that hold stable solutions. We find that type-1 and type-2 PRCs can both hold synchronous and antisynchronous solutions, but the shape of the PRC and the voltage determine the extent of their stability. This is achieved by introducing a five-piecewise linear model to the PRC, and a three-piecewise linear model to the voltage time course, and then analyzing the resultant eigenvalue equations that determine the stability of the phase-locked solutions. A single time parameter defines the skewness of the PRC, and another single time parameter defines the spike width and frequency. Our approach gives a comprehensive picture of the relation between the PRC shape, voltage time course and the stability of the resultant synchronous and antisynchronous solutions. PMID:23777519
DISCOVERY OF RED-SKEWED K {sub {alpha}} IRON LINE IN Cyg X-2 WITH SUZAKU
Shaposhnikov, Nikolai E-mail: Lev.Titarchuk@nrl.navy.mil E-mail: plaurent@cea.fr
2009-07-10
We report on the Suzaku observation of neutron star (NS) low-mass X-ray binary Cygnus X-2 which reveals a presence of the iron K {sub {alpha}} emission line. The line profile shows a significant red wing. This discovery increases the number of NS sources where red-skewed iron lines were observed and strongly suggests that this phenomenon is common not only in black holes but also in other types of accreting compact objects. We examine the line profile in terms of models which attribute its production to the relativistic effects due to reflection of X-ray radiation from a cold accretion disk and also as a result of the line formation in the extended wind/outflow configuration. Both models are able to adequately represent the observed line profile. We consider the results of line modeling in the context of subsecond variability. While we were unable to conclusively disqualify one of the models, we find that the wind paradigm has several advantages over the relativistic disk reflection model.
NASA Astrophysics Data System (ADS)
Nishio, Ryoichi; Watari, Taizan
2014-12-01
The traditional idea of the Pomeron/Reggeon description for hadron scattering is now being given theoretical foundation in gravity dual descriptions, where Pomeron corresponds to an exchange of spin-j âˆˆ2 Z states in the graviton trajectory. Deeply virtual Compton scattering (DVCS) is essentially a two-to-two scattering process of a hadron and a photon, and hence one should be able to study nonperturbative aspects (the generalized parton distribution [GPD]) of this process by the Pomeron/Reggeon process in gravity dual. We find, however, that even one of the most developed formulations of gravity dual, Pomeron [Brower-Polchinski-Strassler-Tan (BPST), 2006], is not able to capture skewness dependence of GPD properly. Therefore, we compute Reggeon wave functions on AdS5 so that the formalism of BPST can be generalized. These wave functions are used to determine the DVCS amplitude, bring it to the form of conformal operator product expansion/collinear factorization, and extract a holographic model of GPD, which naturally fits into the framework known as "dual parametrization," or the "(conformal) collinear factorization approach."
White, Jonah
2011-01-01
Objectives. Few studies have considered the sociohistorical intersection of environmental injustice and gentrification; a gap addressed by this case study of Seattle, Washington. This study explored the advantages of integrating air toxic risk screening with gentrification research to enhance proximity and health equity analysis methodologies. It was hypothesized that Seattle's industrial air toxic exposure risk was unevenly dispersed, that gentrification stratified the city's neighborhoods, and that the inequities of both converged. Methods. Spatial characterizations of air toxic pollution risk exposures from 1990 to 2007 were combined with longitudinal cluster analysis of census block groups in Seattle, Washington, from 1990 to 2000. Results. A cluster of air toxic exposure inequality and socioeconomic inequity converged in 1 area of south central Seattle. Minority and working class residents were more concentrated in the same neighborhoods near Seattle's worst industrial pollution risks. Conclusions. Not all pollution was distributed equally in a dynamic urban landscape. Using techniques to examine skewed riskscapes and socioeconomic urban geographies provided a foundation for future research on the connections among environmental health hazard sources, socially vulnerable neighborhoods, and health inequity. PMID:21836115
NASA Technical Reports Server (NTRS)
Eberlein, A. J.; Lahm, T. G.
1976-01-01
The degree to which flight-critical failures in a strapdown laser gyro tetrad sensor assembly can be isolated in short-haul aircraft after a failure occurrence has been detected by the skewed sensor failure-detection voting logic is investigated along with the degree to which a failure in the tetrad computer can be detected and isolated at the computer level, assuming a dual-redundant computer configuration. The tetrad system was mechanized with two two-axis inertial navigation channels (INCs), each containing two gyro/accelerometer axes, computer, control circuitry, and input/output circuitry. Gyro/accelerometer data is crossfed between the two INCs to enable each computer to independently perform the navigation task. Computer calculations are synchronized between the computers so that calculated quantities are identical and may be compared. Fail-safe performance (identification of the first failure) is accomplished with a probability approaching 100 percent of the time, while fail-operational performance (identification and isolation of the first failure) is achieved 93 to 96 percent of the time.
A Timing Estimation Method Based-on Skewness Analysis in Vehicular Wireless Networks.
Cui, Xuerong; Li, Juan; Wu, Chunlei; Liu, Jian-Hang
2015-01-01
Vehicle positioning technology has drawn more and more attention in vehicular wireless networks to reduce transportation time and traffic accidents. Nowadays, global navigation satellite systems (GNSS) are widely used in land vehicle positioning, but most of them are lack precision and reliability in situations where their signals are blocked. Positioning systems base-on short range wireless communication are another effective way that can be used in vehicle positioning or vehicle ranging. IEEE 802.11p is a new real-time short range wireless communication standard for vehicles, so a new method is proposed to estimate the time delay or ranges between vehicles based on the IEEE 802.11p standard which includes three main steps: cross-correlation between the received signal and the short preamble, summing up the correlated results in groups, and finding the maximum peak using a dynamic threshold based on the skewness analysis. With the range between each vehicle or road-side infrastructure, the position of neighboring vehicles can be estimated correctly. Simulation results were presented in the International Telecommunications Union (ITU) vehicular multipath channel, which show that the proposed method provides better precision than some well-known timing estimation techniques, especially in low signal to noise ratio (SNR) environments. PMID:26580628
SIU-based modification in Kelley's measure of skewness to achieve gains in efficiency
NASA Astrophysics Data System (ADS)
Habibullah, Saleha Naghmi; Shan-E-Fatima, Syeda
2015-02-01
The importance of accurate modeling of life-lengths of components and systems cannot be over-emphasized. Some well-known distributions such as the Birnbaum Saunders distribution extensively used in Reliability Theory are known to fulfill the self-inversion property, the term `Self-Inverse at Unity' (`SIU') implying that, for a random variable X, the distribution of 1/ X is identical to the distribution of X. Very recently, it has been demonstrated the advantage that can be drawn from the SIU property by proposing a modification to the well-known formula of the empirical cumulative distribution function to obtain an estimator of the cumulative distribution function that is more efficient than the empirical cumulative distribution function in situations where the parent population can be assumed to be SIU. Subsequently, a number of papers have appeared proposing SIU-based modifications to the formulae of well-known estimators of central tendency, dispersion and kurtosis that are likely to yield gains in efficiency on account of an approach very similar to the one adopted for the modification of the formula of the empirical cumulative distribution function. In this paper, we propose SIU-based modification to Kelley's Measure of Skewness and, through a simulation study, demonstrate the potential of the proposed formula in improving the efficiency of the estimation process which, obviously, has important implications for accurate modeling of life-data encountered in various branches of engineering.
Numerical analysis of the high skew propeller of an underwater vehicle
NASA Astrophysics Data System (ADS)
Ghasseni, Hassan; Ghadimi, Parviz
2011-09-01
A numerical analysis based on the boundary element method (BEM) was presented for the hydrodynamic performance of a high skew propeller (HSP) which is employed by an underwater vehicle (UV). Since UVs operate at two different working conditions (surface and submerged conditions), the design of such a propeller is a cumbersome task. This is primarily due to the fact that the resistance forces as well as the vessel efficiency under these conditions are significantly different. Therefore, some factors are necessary for the design of the optimum propeller to utilize the power at the mentioned conditions. The design objectives of the optimum propeller are to obtain the highest possible thrust, minimum torque, and efficiency. In the current study, a 5-bladed HSP was chosen for running the UV. This propeller operated at the stern of the UV hull where the inflow velocity to the propeller was non-uniform. Some parameters of the propeller were predicted based on the UV geometrical hull and operating conditions. The computed results include the pressure distribution and the hydrodynamic characteristics of the HSP in open water conditions, and comparison of these results with those of the experimental data indicates good agreement. The propeller efficiency for both submerged and surface conditions was found to be 67% and 64%, respectively, which compared to conventional propellers is a significantly higher efficiency.
GC skew defines distinct RNA polymerase pause sites in CpG island promoters.
Kellner, Wendy A; Bell, Joshua S K; Vertino, Paula M
2015-11-01
CpG islands (CGIs) are associated with over half of human gene promoters and are characterized by a unique chromatin environment and high levels of bidirectional transcriptional activity relative to surrounding genomic regions, suggesting that RNA polymerase (Pol II) progression past the CGI boundaries is restricted. Here we describe a novel transcriptional regulatory step wherein Pol II encounters an additional barrier to elongation distinct from the promoter-proximal pause and occurring at the downstream boundary of the CGI domain. For most CGI-associated promoters, Pol II exhibits a dominant pause at either the promoter-proximal or this distal site that correlates, both in position and in intensity, with local regions of high GC skew, a sequence feature known to form unique secondary structures. Upon signal-induced gene activation, long-range enhancer contacts at the dominant pause site are selectively enhanced, suggesting a new role for enhancers at the downstream pause. These data point to an additional level of control over transcriptional output at a subset of CGI-associated genes that is linked to DNA sequence and the integrity of the CGI domain. PMID:26275623
Bacterial clearance reverses a skewed T-cell repertoire induced by Salmonella infection
Leyva-Rangel, Jessica P; de los Angeles HernÃ¡ndez-Cueto, Maria; Galan-Enriquez, Carlos-Samuel; LÃ³pez-Medina, Marcela; Ortiz-Navarrete, Vianney
2015-01-01
Salmonella typhimurium invades the spleen, liver, and peripheral lymph nodes and has recently been detected in the bone marrow and thymus, resulting in a reduced thymic size and a decline in the total number of thymic cells. A specific deletion of the double-positive cell subset has been characterized, yet the export of mature T cells to the periphery remains normal. We analyzed Salmonella pathogenesis regarding thymic structure and the T-cell maturation process. We demonstrate that, despite alterations in the thymic structure, T-cell development is maintained during Salmonella infection, allowing the selection of single-positive T-cell clones expressing particular T-cell receptor beta chains (TCR-VÎ²). Moreover, the treatment of infected mice with an antibiotic restored the normal thymic architecture and thymocyte subset distribution. Additionally, the frequency of TCR-VÎ² usage after treatment was comparable to that in non-infected mice. However, bacteria were still recovered from the thymus after 1 month of treatment. Our data reveal that a skewed T-cell developmental process is present in the Salmonella-infected thymus that alters the TCR-VÎ² usage frequency. Likewise, the post-treatment persistence of Salmonella reveals a novel function of the thymus as a potential reservoir for this infectious agent. PMID:26417438
Skew of mantle upwelling beneath the East Pacific Rise governs segmentation.
Toomey, Douglas R; Jousselin, David; Dunn, Robert A; Wilcock, William S D; Detrick, R S
2007-03-22
Mantle upwelling is essential to the generation of new oceanic crust at mid-ocean ridges, and it is generally assumed that such upwelling is symmetric beneath active ridges. Here, however, we use seismic imaging to show that the isotropic and anisotropic structure of the mantle is rotated beneath the East Pacific Rise. The isotropic structure defines the pattern of magma delivery from the mantle to the crust. We find that the segmentation of the rise crest between transform faults correlates well with the distribution of mantle melt. The azimuth of seismic anisotropy constrains the direction of mantle flow, which is rotated nearly 10 degrees anticlockwise from the plate-spreading direction. The mismatch between the locus of mantle melt delivery and the morphologic ridge axis results in systematic differences between areas of on-axis and off-axis melt supply. We conclude that the skew of asthenospheric upwelling and transport governs segmentation of the East Pacific Rise and variations in the intensity of ridge crest processes. PMID:17377578
NASA Astrophysics Data System (ADS)
Hamaker, Henry Chris
1995-12-01
Statistical process control (SPC) techniques often use six times the standard deviation sigma to estimate the range of errors within a process. Two assumptions are inherent in this choice of metric for the range: (1) the normal distribution adequately describes the errors, and (2) the fraction of errors falling within plus or minus 3 sigma, about 99.73%, is sufficiently large that we may consider the fraction occurring outside this range to be negligible. In state-of-the-art photomasks, however, the assumption of normality frequently breaks down, and consequently plus or minus 3 sigma is not a good estimate of the range of errors. In this study, we show that improved estimates for the effective maximum error Em, which is defined as the value for which 99.73% of all errors fall within plus or minus Em of the mean mu, may be obtained by quantifying the deviation from normality of the error distributions using the skewness and kurtosis of the error sampling. Data are presented indicating that in laser reticle- writing tools, Em less than or equal to 3 sigma. We also extend this technique for estimating the range of errors to specifications that are usually described by mu plus 3 sigma. The implications for SPC are examined.
A Timing Estimation Method Based-on Skewness Analysis in Vehicular Wireless Networks
Cui, Xuerong; Li, Juan; Wu, Chunlei; Liu, Jian-Hang
2015-01-01
Vehicle positioning technology has drawn more and more attention in vehicular wireless networks to reduce transportation time and traffic accidents. Nowadays, global navigation satellite systems (GNSS) are widely used in land vehicle positioning, but most of them are lack precision and reliability in situations where their signals are blocked. Positioning systems base-on short range wireless communication are another effective way that can be used in vehicle positioning or vehicle ranging. IEEE 802.11p is a new real-time short range wireless communication standard for vehicles, so a new method is proposed to estimate the time delay or ranges between vehicles based on the IEEE 802.11p standard which includes three main steps: cross-correlation between the received signal and the short preamble, summing up the correlated results in groups, and finding the maximum peak using a dynamic threshold based on the skewness analysis. With the range between each vehicle or road-side infrastructure, the position of neighboring vehicles can be estimated correctly. Simulation results were presented in the International Telecommunications Union (ITU) vehicular multipath channel, which show that the proposed method provides better precision than some well-known timing estimation techniques, especially in low signal to noise ratio (SNR) environments. PMID:26580628
33 CFR 118.100 - Retroreflective panels on bridge piers.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Retroreflective panels on bridge... SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.100 Retroreflective panels on bridge piers. The... 12 inches square. (c) To mark bridge piers or channel sides on bridges not required to have...
49 CFR 237.111 - Review of bridge inspection reports.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Review of bridge inspection reports. 237.111... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.111 Review of bridge inspection reports. Bridge inspection reports shall be reviewed by railroad bridge supervisors and...
33 CFR 118.100 - Retroreflective panels on bridge piers.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Retroreflective panels on bridge... SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.100 Retroreflective panels on bridge piers. The... 12 inches square. (c) To mark bridge piers or channel sides on bridges not required to have...
33 CFR 118.100 - Retroreflective panels on bridge piers.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Retroreflective panels on bridge... SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.100 Retroreflective panels on bridge piers. The... 12 inches square. (c) To mark bridge piers or channel sides on bridges not required to have...
49 CFR 237.111 - Review of bridge inspection reports.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 4 2014-10-01 2014-10-01 false Review of bridge inspection reports. 237.111... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.111 Review of bridge inspection reports. Bridge inspection reports shall be reviewed by railroad bridge supervisors and...
49 CFR 237.111 - Review of bridge inspection reports.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Review of bridge inspection reports. 237.111... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.111 Review of bridge inspection reports. Bridge inspection reports shall be reviewed by railroad bridge supervisors and...
49 CFR 237.109 - Bridge inspection records.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 4 2014-10-01 2014-10-01 false Bridge inspection records. 237.109 Section 237.109..., DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.109 Bridge inspection records... performed on those bridges under this part. (b) Each record of an inspection under the bridge...
49 CFR 237.111 - Review of bridge inspection reports.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 4 2013-10-01 2013-10-01 false Review of bridge inspection reports. 237.111... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.111 Review of bridge inspection reports. Bridge inspection reports shall be reviewed by railroad bridge supervisors and...
49 CFR 237.109 - Bridge inspection records.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 4 2013-10-01 2013-10-01 false Bridge inspection records. 237.109 Section 237.109..., DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.109 Bridge inspection records... performed on those bridges under this part. (b) Each record of an inspection under the bridge...
33 CFR 118.100 - Retroreflective panels on bridge piers.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Retroreflective panels on bridge... SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.100 Retroreflective panels on bridge piers. The... 12 inches square. (c) To mark bridge piers or channel sides on bridges not required to have...
49 CFR 237.109 - Bridge inspection records.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Bridge inspection records. 237.109 Section 237.109..., DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.109 Bridge inspection records... performed on those bridges under this part. (b) Each record of an inspection under the bridge...
49 CFR 237.109 - Bridge inspection records.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Bridge inspection records. 237.109 Section 237.109..., DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.109 Bridge inspection records... performed on those bridges under this part. (b) Each record of an inspection under the bridge...
49 CFR 237.109 - Bridge inspection records.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Bridge inspection records. 237.109 Section 237.109..., DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.109 Bridge inspection records... performed on those bridges under this part. (b) Each record of an inspection under the bridge...
33 CFR 118.100 - Retroreflective panels on bridge piers.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Retroreflective panels on bridge... SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.100 Retroreflective panels on bridge piers. The... 12 inches square. (c) To mark bridge piers or channel sides on bridges not required to have...
49 CFR 237.111 - Review of bridge inspection reports.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Review of bridge inspection reports. 237.111... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.111 Review of bridge inspection reports. Bridge inspection reports shall be reviewed by railroad bridge supervisors and...
31. Photographic copy of drawing showing profile of bridge after ...
31. Photographic copy of drawing showing profile of bridge after the 1888-1889 and 1899-1900 reconstructions; also shows profile of bridge before 1888 (Martin Sigvart Grytbak, Wabasha St. Bridge, Formerly St. Paul Bridge, 1919); profile of Wabasha street bridge - Wabasha Street Bridge, Spanning Mississippi River at Wabasha Street, Saint Paul, Ramsey County, MN
Performance analysis of LAN bridges and routers
NASA Technical Reports Server (NTRS)
Hajare, Ankur R.
1991-01-01
Bridges and routers are used to interconnect Local Area Networks (LANs). The performance of these devices is important since they can become bottlenecks in large multi-segment networks. Performance metrics and test methodology for bridges and routers were not standardized. Performance data reported by vendors is not applicable to the actual scenarios encountered in an operational network. However, vendor-provided data can be used to calibrate models of bridges and routers that, along with other models, yield performance data for a network. Several tools are available for modeling bridges and routers - Network II.5 was used. The results of the analysis of some bridges and routers are presented.
Theory of water and charged liquid bridges.
Morawetz, K
2012-08-01
The phenomenon of liquid bridge formation due to an applied electric field is investigated. A solution of a charged catenary is presented, which allows one to determine the static and dynamical stability conditions where charged liquid bridges are possible. The creeping height, the bridge radius and length, as well as the shape of the bridge are calculated showing an asymmetric profile, in agreement with observations. The flow profile is calculated from the Navier-Stokes equation leading to a mean velocity, which combines charge transport with neutral mass flow and which describes recent experiments on water bridges. PMID:23005849
Leong, Josiah K; Pestilli, Franco; Wu, Charlene C; Samanez-Larkin, Gregory R; Knutson, Brian
2016-01-01
Individuals sometimes show inconsistent risk preferences, including excessive attraction to gambles featuring small chances of winning large amounts (called "positively skewed" gambles). While functional neuroimaging research indicates that nucleus accumbens (NAcc) and anterior insula (AIns) activity inversely predict risky choice, structural connections between these regions have not been described in humans. By combining diffusion-weighted MRI with tractography, we identified the anatomical trajectory of white-matter tracts projecting from the AIns to the NAcc and statistically validated these tracts using Linear Fascicle Evaluation (LiFE) and virtual lesions. Coherence of the right AIns-NAcc tract correlated with reduced preferences for positively skewed gambles. Further, diminished NAcc activity during gamble presentation mediated the association between tract structure and choice. These results identify an unreported tract connecting the AIns to the NAcc in humans and support the notion that structural connections can alter behavior by influencing brain activity as individuals weigh uncertain gains against uncertain losses. PMID:26748088
Skrypnyk, T.
2009-03-15
We construct quantum integrable systems associated with non-skew-symmetric gl(2)-valued classical r-matrices. We find a new explicit multiparametric family of such the non-skew-symmetric classical r-matrices. We consider two classes of examples of the corresponding integrable systems, namely generalized Gaudin systems with and without an external magnetic field. In the case of arbitrary r-matrices diagonal in a standard gl(2)-basis, we calculate the spectrum of the corresponding quantum integrable systems using the algebraic Bethe ansatz. We apply these results to a construction of integrable fermionic models and obtain a wide class of integrable Bardeen-Cooper-Schrieffer (BCS)-type fermionic Hamiltonians containing the pairing and electrostatic interaction terms. We also consider special cases when the corresponding integrable Hamiltonians contain only pairing interaction term and are exact analogs of the 'reduced BCS Hamiltonian' of Richardson.
Ning, S. A.; Hayman, G.; Damiani, R.; Jonkman, J.
2014-12-01
Blade element momentum methods, though conceptually simple, are highly useful for analyzing wind turbines aerodynamics and are widely used in many design and analysis applications. A new version of AeroDyn is being developed to take advantage of new robust solution methodologies, conform to a new modularization framework for National Renewable Energy Laboratory's FAST, utilize advanced skewed-wake analysis methods, fix limitations with previous implementations, and to enable modeling of highly flexible and nonstraight blades. This paper reviews blade element momentum theory and several of the options available for analyzing skewed inflow. AeroDyn implementation details are described for the benefit of users and developers. These new options are compared to solutions from the previous version of AeroDyn and to experimental data. Finally, recommendations are given on how one might select from the various available solution approaches.
NASA Astrophysics Data System (ADS)
Fan, W. J.; Ma, L.; Zhou, S. M.
2015-03-01
Tuning effects of the band filling and impurity distribution on the anomalous Hall effect are demonstrated in epitaxial face centered cubic NixCo1-x (002) films through the alloy composition. The anomalous Hall resistivity obeys the conventional scaling law, i.e. {?\\text{AH}}=a{?xx}+b? xx2 . It is interesting to find that in addition to the scattering independent parameter b, the skew parameter a also changes sign from negative to positive near the same Ni atomic concentration (x = 0.80) due to the band filling effects. The magnitude of the skew scattering parameter a shows a similar variation trend for the residual resistivity because of effects of the impurity distribution. This work might provide a clue to design and fabrication of high sensitivity Hall sensor.
Strengthening Bridges with Prestressed CFRP Strips
NASA Astrophysics Data System (ADS)
Siwowski, Tomasz; ?ó?towski, Piotr
2012-06-01
Limitation of bridge's carrying bearing capacity due to aging and deterioration is a common problem faced by road administration and drivers. Rehabilitation of bridges including strengthening may be applied in order to maintain or upgrade existing bridge parameters. The case studies of strengthening of two small bridges with high modulus prestressed CFRP strips have been presented in the paper. The first one - reinforced concrete slab bridge - and the other - composite steel-concrete girder bridge - have been successfully upgraded with quite new technology. In both cases the additional CFRP reinforcement let increasing of bridge carrying capacity from 15 till 40 metric tons. The CFRP strip prestressing system named Neoxe Prestressing System (NPS), developed by multi-disciplinary team and tested at full scale in Rzeszow University of Technology, has been also described in the paper.
Panten, Johannes; Surburg, Horst; Hölscher, Bernd
2008-06-01
In creating new aroma molecules, the fragrance chemist can make use of several tools: receptor or combinatorial research as well as lead structure optimization of existing chemicals or substances from the natural pool. Sometimes, it is also possible to discover new structures via another way: the careful analysis of existing products and their production processes. In analyzing the production process of 1-oxacyclohexadecan-2-one (6), we identified at least two new oxa-bridged macrocyclic molecules. In continuation, these results inspired us to synthesize and evaluate more representatives with similar structures. In this contribution, presented at the RSC/SCI conference 'flavours & fragrances 2007' in London, September 24-26, 2007, the synthesis and olfactory properties of several new oxa-bridged macrocycles will be introduced and discussed. PMID:18618411
Deletion Xq27.3q28 in female patient with global developmental delays and skewed X-inactivation
2013-01-01
Background Global developmental delay and mental retardation are associated with X-linked disorders including Hunter syndrome (mucopolysaccharidosis type II) and Fragile X syndrome (FXS). Single nucleotide mutations in the iduronate 2-sulfatase (IDS) gene at Xq28 most commonly cause Hunter syndrome while a CGG expansion in the FMR1 gene at Xq27.3 is associated with Fragile X syndrome. Gene deletions of the Xq27-28 region are less frequently found in either condition with rare reports in females. Additionally, an association between Xq27-28 deletions and skewed X-inactivation of the normal X chromosome observed in previous studies suggested a primary role of the Xq27-28 region in X-inactivation. Case presentation We describe the clinical, molecular and biochemical evaluations of a four year-old female patient with global developmental delay and a hemizygous deletion of Xq27.3q28 (144,270,614-154,845,961 bp), a 10.6 Mb region that contains >100 genes including IDS and FMR1. A literature review revealed rare cases with similar deletions that included IDS and FMR1 in females with developmental delay, variable features of Hunter syndrome, and skewed X-inactivation of the normal X chromosome. In contrast, our patient exhibited skewed X-inactivation of the deleted X chromosome and tested negative for Hunter syndrome. Conclusions This is a report of a female with a 10.6 Mb Xq27-28 deletion with skewed inactivation of the deleted X chromosome. Contrary to previous reports, our observations do not support a primary role of the Xq27-28 region in X-inactivation. A review of the genes in the deletion region revealed several potential genes that may contribute to the patient’s developmental delays, and sequencing of the active X chromosome may provide insight into the etiology of this clinical presentation. PMID:23634718
NASA Technical Reports Server (NTRS)
Hannaman, David J.; Lieneweg, Udo; Buehler, Martin G.; Mantalas, Linda
1991-01-01
Integrated-circuit conductive test pattern intended to provide data on effects of design widths and design spacings upon actual widths of conductive lines. Provides for electrical measurements both on lines of unknown width and on features having known dimensions. Data from measurements on five bridges used to determine four parameters of mathematical model describing system. In principle, pattern determines effects of width and spacing and interaction between them.
Halliburton Composite Bridge Plug Assembly
Starbuck, J.M.; Luttrell, C.R.; Aramayo, G.
2005-01-15
The overall objectives of this CRADA were to assist Halliburton in analyzing a composite bridge plug and to determine why their original design was failing in the field. In Phase 1, finite element analyses were done on the original composite slip design and several alternative designs. The composite slip was the component in the bridge plug that was failing. The finite element code ABAQUS was used for these calculations and I-DEAS was used as the pre- and post-processor in the analyses. Several different designs and materials were analyzed and recommendations were made towards improving the design. In Phase 2, the objective was to develop finite element models that would accurately represent the deformations in the entire all-composite 4-1/2' diameter bridge plug assembly. The finite element code LS-DYNA was used and the results from this effort were intended to expand Halliburton's composite design and analysis capabilities with regard to developing future composite components for downhole tools. In addition to the finite element modeling, this effort involved the utilization of micromechanics to determine the necessary composite material properties that were needed as input for finite element codes.
Li, Ji; He, Siyuan; Yu, Dingfeng; Deng, Fangshun; Yin, Hongcheng; Zhu, Guoqiang
2011-11-21
a numerical matching method (NMM) based on the framework of the uniform geometrical theory of diffraction (UTD) is proposed to build the spectral functions for computing the diffraction field by anisotropic impedance wedge at an arbitrary skew incidence. The NMM starts from the coupled integral equations before they are converted into the coupled difference equations as the classic Maliuzhinets methods. Then, the spectral function in the Sommerfeld integral representation of the longitudinal components of the EM field is expanded by a series about the spectrum and the skew incident angle with unknown coefficients. With respect to the oblique incident angle based on normal to the edge incidence or grazing to the edge incidence, the spectral function is derived numerically by solving a system of algebraic equations constructed from the coupled integral equations, after choosing the numerical matching regions on the wedge faces and setting a Sommerfeld numerical integration path. On the basis of the sampled incidences, the asymptotic waveform evaluation (AWE) technique is employed to deduce the spectral function at any other skew incidence in the whole angle space (0°-90°) rapidly. Finally, the UTD solutions are provided far beyond the applicability of the perturbation approach and the numerical examples provide a uniform behavior of the field with respect to the observation angle. PMID:22109401
Passow, Courtney N.; Delclos, Pablo J.; Kindsvater, Holly K.; Jones, Adam G.; Rosenthal, Gil G.
2015-01-01
Just as mating patterns can promote speciation or hybridization, the presence of hybridization can shape mating patterns within a population. In this study, we characterized patterns of multiple mating and reproductive skew in a naturally hybridizing swordtail fish species, Xiphophorus birchmanni. We quantified multiple mating using microsatellite markers to genotype embryos from 43 females collected from 2 wild populations. We also used a suite of single-nucleotide polymorphism markers to categorize females and their inferred mates as either parental X. birchmanni or as introgressed individuals, which carried alleles from a sister species, X. malinche. We found that parental and introgressed X. birchmanni females mated multiply with both parental and introgressed males. We found no difference in mating patterns or reproductive skew between parental and introgressed X. birchmanni females. However, nonintrogressed X. birchmanni males mated more often with large, fecund females. These females also had the greatest levels of skew in fertilization success of males. Thus, our results show that X. birchmanni has a polygynandrous mating system and that introgression of X. malinche alleles has only subtle effects on mating patterns in this species. PMID:25433083
Huang, Yangxin; Dagne, Getachew
2012-09-01
It is a common practice to analyze complex longitudinal data using semiparametric nonlinear mixed-effects (SNLME) models with a normal distribution. Normality assumption of model errors may unrealistically obscure important features of subject variations. To partially explain between- and within-subject variations, covariates are usually introduced in such models, but some covariates may often be measured with substantial errors. Moreover, the responses may be missing and the missingness may be nonignorable. Inferential procedures can be complicated dramatically when data with skewness, missing values, and measurement error are observed. In the literature, there has been considerable interest in accommodating either skewness, incompleteness or covariate measurement error in such models, but there has been relatively little study concerning all three features simultaneously. In this article, our objective is to address the simultaneous impact of skewness, missingness, and covariate measurement error by jointly modeling the response and covariate processes based on a flexible Bayesian SNLME model. The method is illustrated using a real AIDS data set to compare potential models with various scenarios and different distribution specifications. PMID:22150787
Re-identification of home addresses from spatial locations anonymized by Gaussian skew
Cassa, Christopher A; Wieland, Shannon C; Mandl, Kenneth D
2008-01-01
Background Knowledge of the geographical locations of individuals is fundamental to the practice of spatial epidemiology. One approach to preserving the privacy of individual-level addresses in a data set is to de-identify the data using a non-deterministic blurring algorithm that shifts the geocoded values. We investigate a vulnerability in this approach which enables an adversary to re-identify individuals using multiple anonymized versions of the original data set. If several such versions are available, each can be used to incrementally refine estimates of the original geocoded location. Results We produce multiple anonymized data sets using a single set of addresses and then progressively average the anonymized results related to each address, characterizing the steep decline in distance from the re-identified point to the original location, (and the reduction in privacy). With ten anonymized copies of an original data set, we find a substantial decrease in average distance from 0.7 km to 0.2 km between the estimated, re-identified address and the original address. With fifty anonymized copies of an original data set, we find a decrease in average distance from 0.7 km to 0.1 km. Conclusion We demonstrate that multiple versions of the same data, each anonymized by non-deterministic Gaussian skew, can be used to ascertain original geographic locations. We explore solutions to this problem that include infrastructure to support the safe disclosure of anonymized medical data to prevent inference or re-identification of original address data, and the use of a Markov-process based algorithm to mitigate this risk. PMID:18700031
S1 statistic with Hodges-Lehmann in two groups case for skewed distribution
NASA Astrophysics Data System (ADS)
Yin, Lee Ping; Yahaya, Sharipah Soaad Syed; Ahad, Nor Aishah
2015-12-01
This study is focused on the modification of S1 statistic, a procedure for testing the equality of groups, by replacing median with Hodges-Lehmann estimator as the location measure in two groups case under skewed distribution. The modification is also extended to the default scale estimator of Hodges-Lehmann, S1(HL) and robust scale estimator, MADn, S1(MADn). The purpose of the modifications is to improve the robustness of the statistic. To test the strengths and weaknesses of S1(HL) and S1(MADn), a simulation study was conducted. Several variables such as the shape of distributions, balanced and unbalanced group sizes, equal and unequal variances and nature of pairings were manipulated to create various conditions for the data. Since the distribution of S1 statistic is unknown, bootstrap method was used for data generation. According to Guo and Luh, a test statistic is considered robust if its empirical error rate does not exceed 0.075 when ? = 0.05. Refer to the results obtained, S1(HL) and S1(MADn) can be considered as robust due to all error rates fall below 0.075 for balanced and unbalanced design in each distribution. t-test and Mann-Whitney are the chosen methods for comparison purpose. For balanced design, t-test and Mann-Whitney shown better results compare to S1(HL) and S1(MADn). However, for unbalanced design especially in negative pairing, S1(MADn) is the most appropriate method to be used across three distributions.
Tejada-Simon, Maria V; Hong, Jian; Rivera, Victor M; Zhang, Jingwu Z
2002-01-01
Myelin oligodendrocyte glycoprotein (MOG) is found to induce both autoreactive T-cell and antibody responses associated with demyelinating pathology and is implicated in the pathogenesis of multiple sclerosis (MS). In this study, we addressed the potential association of anti-MOG immune responses with MS by examining, comparatively, both the T-cell and antibody responses to recombinant MOG fragments in MS patients and healthy subjects. T cells recognizing MOG were detected in MS patients as well as in healthy subjects, and their precursor frequency in the blood was not increased in patients with MS. MOG-reactive T cells isolated from both MS patients and healthy subjects exhibited a similar cytokine profile, producing interleukin (IL)-4, IL-10 and tumour necrosis factor (TNF), but not interferon-? (IFN-?), and recognized predominantly the extracellular (residues 1–60) and the transmembrane/cytoplasmic (residues 154–218) domains of MOG. In contrast, anti-MOG antibodies derived from MS patients displayed a skewed reactivity pattern, even though the occurrence and titres of serum anti-MOG antibodies were only slightly elevated in MS patients. MS-derived autoantibodies were predominantly directed at the 1–60 region of MOG, while naturally occurring anti-MOG antibodies derived from healthy individuals reacted selectively to the 154–218 domain. These differences were statistically significant. The findings of this study are consistent with the presence of anti-MOG antibodies within demyelinating lesions of MS and their role in the induction of demyelinating pathology in animal models. The study has important implications in the understanding of the autoimmune processes in MS. PMID:12460184
Assessment of skewed exposure in case-control studies with pooling.
Whitcomb, Brian W; Perkins, Neil J; Zhang, Zhiwei; Ye, Aijun; Lyles, Robert H
2012-09-28
Pooling-based strategies that combine samples from multiple participants for laboratory assays have been proposed for epidemiologic investigations of biomarkers to address issues including cost, efficiency, detection, and when minimal sample volume is available. A modification of the standard logistic regression model has been previously described to allow use with pooled data; however, this model makes assumptions regarding exposure distribution and logit-linearity of risk (i.e., constant odds ratio) that can be violated in practice. We were motivated by a nested case-control study of miscarriage and inflammatory factors with highly skewed distributions to develop a more flexible model for analysis of pooled data. Using characteristics of the gamma distribution and the relation between models of binary outcome conditional on exposure and of exposure conditional on outcome, we use a modified logistic regression to accommodate nonlinearity because of unequal shape parameters in gamma distributed exposure for cases and controls. Using simulations, we compare our approach with existing methods for logistic regression for pooled data considering: (1) constant and dose-dependent effects; (2) gamma and log-normal distributed exposure; (3) effect size; and (4) the proportions of biospecimens pooled. We show that our approach allows estimation of odds ratios that vary with exposure level, yet has minimal loss of efficiency compared with existing approaches when exposure effects are dose-invariant. Our model performed similarly to a maximum likelihood estimation approach in terms of bias and efficiency, and provides an easily implemented approach for estimation with pooled biomarker data when effects may not be constant across exposure. PMID:22437722
Scour assessment at bridges from Flag Point to Million Dollar Bridge, Copper River Highway, Alaska
Brabets, T.P.
1994-01-01
Twelve bridges are located along the Copper River Highway from Flag Point (Mile 27) to lhe Million Dollar Bridge (Mile 48). These bridges cross all or parts of the Copper River. Channel scour at these bridges was assessed by collecting and analyzing discharge and sediment data, analyzing aerial photography for eight different years, surveying and comparing cross sections, and utilizing scour equations. Between 1968 and 1992, scour occurring at Bridge 331 has formed two distinct channels at the bridge. The channel at Bridge 1187 has remained relatively unchanged between 1968 and 1992. During this same time period, the channel at Bridge 332 appears to have gradually filled. However, during the 1992 runoff season, the channel at this bridge scoured significantly, probably because of its unstable nature. The most significant scour has occurred at Bridge 342. A high-water period in 1981 probably shifted much of the flow of the Copper River through this bridge. As a result, severe contraction scour occurred which required major repairs to the bridge. During 1991 and 1992, the approach channel to Bridge 342 has been migrating, causing scour in the left side of the channel. Bed material at the Million Dollar Bridge consists of hard unweathered boulders nested in dense gravel. Because of this type of erosion-resistant material, no significant scour has occurred at this site. Contraction scour equations overestimated the mean depth of flow at Bridge 331 by 2.6 to 5.0 ft, but were within 1.0 ft of the mean depth of flow for Bridge 1187. The local scour equations generally overestimated local scour at both Bridge 331 and Bridge 1187. The accuracy of some equations was probably affected because water velocities could not be obtained upstream from the piers.
Salt Bridges: Geometrically Specific, Designable Interactions
Donald, Jason E.; Kulp, Daniel W.; DeGrado, William F.
2010-01-01
Salt bridges occur frequently in proteins, providing conformational specificity and contributing to molecular recognition and catalysis. We present a comprehensive analysis of these interactions in protein structures by surveying a large database of protein structures. Salt bridges between Asp or Glu and His, Arg, or Lys display extremely well-defined geometric preferences. Several previously observed preferences are confirmed and others that were previously unrecognized are discovered. Salt bridges are explored for their preferences for different separations in sequence and in space, geometric preferences within proteins and at protein-protein interfaces, cooperativity in networked salt bridges, inclusion within metal-binding sites, preference for acidic electrons, apparent conformational side chain entropy reduction upon formation, and degree of burial. Salt bridges occur far more frequently between residues at close than distant sequence separations, but at close distances there remain strong preferences for salt bridges at specific separations. Specific types of complex salt bridges, involving three or more members, are also discovered. As we observe a strong relationship between the propensity to form a salt bridge and the placement of salt-bridging residues in protein sequences, we discuss the role that salt bridges might play in kinetically influencing protein folding and thermodynamically stabilizing the native conformation. We also develop a quantitative method to select appropriate crystal structure resolution and B-factor cutoffs. Detailed knowledge of these geometric and sequence dependences should aid de novo design and prediction algorithms. PMID:21287621
Vehicle bridge interaction dynamics and potential applications
NASA Astrophysics Data System (ADS)
Yang, Y. B.; Lin, C. W.
2005-06-01
The dynamic interaction between a moving vehicle and the sustaining bridge is studied. By the method of modal superposition, closed-form solutions are obtained for the vertical responses of both the bridge and moving vehicle, assuming the vehicle/bridge mass ratio to be small. For both the bridge and vehicle responses, it is confirmed that rather accurate solutions can be obtained by considering only the first mode. The displacement, velocity, and acceleration of the bridge are governed at different extents by two sets of frequencies, i.e., the driving frequency of the vehicle and natural frequencies of the bridge. From the spectrum for the bridge displacement, the vehicle speeds can be shown to be associated with some low-frequency pikes. On the other hand, the vehicle responses are governed by five distinct frequencies that appear as driving frequencies, vehicle frequency, and bridge frequencies with shift. From the vehicle's acceleration spectrum, the first bridge frequency (with shift) is shown to have rather high visibility and can be easily identified. The effects of damping of the vehicle and bridge are evaluated in the numerical studies. Potential applications of the present results, as well as further researches required, are also indicated in the paper.
ERIC Educational Resources Information Center
Kuttner, Donna Holberg, Ed.
This publication presents papers and reprints of articles aimed at family members of persons with mental illnesses. After an introductory chapter, the second chapter reviews definitions of mental illness, and discusses what is known about medicating such conditions as well as the relationship of substance abuse to mental illness. The next chapter…
Network Bridging Potential in Later Life
Cornwell, Benjamin
2009-01-01
Objectives Much work in social gerontology has examined older adults’ social connectedness, but we know little about the extent to which older adults occupy positions of power and independence in their networks. The author uses health and life-course frameworks to understand older adults’ prospects of occupying bridging positions between otherwise unconnected individuals. Methods Egocentric social network data were collected from a nationally representative sample of 3,005 older adults between the ages of 57 and 85 in 2005–2006. A series of multivariate regression analyses was used to examine how health and life-course factors relate to bridging. Results Age is not significantly associated with bridging. However, retirees and people with poor health are less likely to have bridging potential. At the same time, widows are more likely to serve as bridges. Discussion The discusses the need for more dialogue between social network researchers and social gerontologists to help explain older adults’ bridging prospects. PMID:19144972
HERO resistant semiconductor bridge igniter
NASA Astrophysics Data System (ADS)
Bickes, R. W., Jr.; Greenway, D.; Grubelich, M. C.; Meyer, W. J.; Hartman, J. K.; McCampbell, C. B.
1992-10-01
The problem of accidental ignition of explosive components when exposed to radio frequency (RF) environments or radiation from other electromagnetic sources is commonly referred to as Hazards of Electromagnetic Radiation to Ordnance (HERO). One illustration of such a HERO problem is the MK 149 Phalanx ammunition, which is sensitive to RF energy over a broad range of frequencies. We have demonstrated that a potential solution to the Phalanx HERO problem consists of a semiconductor bridge (SCB) igniter that incorporates microcircuitry to protect the SCB from the RF environment. Direct RF injection and ground plane tests have demonstrated the resistance of our designs to severe RF environments.
Research: the bridge to collaboration.
Reeb, R M; Rogers, B P; Richardson, B
1992-01-01
A faculty-staff research fair was used by a school of nursing and university hospital at a large Southern medical center as a way of promoting collaboration between nursing education and service. The end results were these: a nurse-theorist "room" in the school of nursing; development of collaborative studies; subsequent presentation of posters originally prepared for the fair at 12 local, 13 state, six regional, and three national meetings. The overwhelming positive response by participants verified that research could serve as a natural bridge to promote collaboration between research, education, and service. PMID:1589043
Subquantum conductive-bridge memory
NASA Astrophysics Data System (ADS)
Jameson, John R.; Kamalanathan, Deepak
2016-02-01
Resistive memory devices suffer from a tradeoff between operating current and data retention. The key parameter governing this tradeoff is shown to be the 1-atom conductance of the filament material. High 1-atom conductances, comparable to the quantum G 0 = 2 e 2 / h , are shown to make metal filaments unsuitable for low-power applications. Instead by using filaments containing Te, a semiconductor whose 1-atom conductance is deduced to be just 0.03 G 0 , it is shown that operating currents can be reduced by an order of magnitude compared to metals. Such "subquantum" conductive-bridge memory cells are broadly applicable to low-power applications.
Measurement of Deflection Line on Bridges
NASA Astrophysics Data System (ADS)
Urban, Rudolf; Štroner, Martin
2013-12-01
Prestressed concrete bridges are very sensitive to the increase in long-term deflections. Reliable forecasts of deflections of bridge structures during construction and durability are crucial for achieving good durability. The main results of measurements are the changes of the deflection line of the bridge structures, which places special demands on the measurement procedure. Results from measurements are very useful for the improvement of mathematical prediction methods of behaviour of long span prestressed concrete structures.
Boundary Stability of a Nematic Liquid Bridge
NASA Astrophysics Data System (ADS)
Barnes, William; Santangelo, Chris
2014-03-01
We consider a nematic liquid crystal droplet in air confined between two parallel plates with homeotropic boundary conditions. The boundary conditions at the nematic-plate and nematic-air interfaces induce either a hedgehog or planar ring disclination within the nematic bridge, depending on the plate separation and bridge radius. We study the stability of the liquid crystal-air boundary of a nearly cylindrical nematic bridge by minimizing the Frank elastic energy.
76 FR 55160 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation
Federal Register 2010, 2011, 2012, 2013, 2014
2011-09-06
... for bridges that were new or replaced within the defined time period. The FHWA's Financial Management Information System and the 2010 NBI were used to identify the material types for bridges that...
75 FR 62181 - Annual Materials Report on New Bridge Construction and Bridge Rehabilitation
Federal Register 2010, 2011, 2012, 2013, 2014
2010-10-07
... for bridges that were new or replaced within the defined time period. The FHWA's Financial Management Information System and the 2009 NBI were used to identify the material types for bridges that...
The survival rate of bridges. A study of 1674 bridges in 40 Dutch general practices.
Leempoel, P J; Käyser, A F; Van Rossum, G M; De Haan, A F
1995-05-01
The survival rate of 1674 bridges and the influence of several factors on the lifetime of bridges were analysed, based on data from patient records that belonged to a random sample of 40 Dutch general practices. It appears that the 12 year survival rate of the bridges is 87%. There is a significant difference in the survival rate between the bridges that meet and do not meet Ante's law, and only a weak significant difference between the bridges with vital vs. non-vital abutment teeth. Gender and age of the patient, length of the bridge, presence of a post and core build-up, or the construction of the bridge (conventional fixed vs. cantilever pontic) appear to have no influence on the survival rate of the bridges in this sample. PMID:7616341
A data management infrastructure for bridge monitoring
NASA Astrophysics Data System (ADS)
Jeong, Seongwoon; Byun, Jaewook; Kim, Daeyoung; Sohn, Hoon; Bae, In Hwan; Law, Kincho H.
2015-04-01
This paper discusses a data management infrastructure framework for bridge monitoring applications. As sensor technologies mature and become economically affordable, their deployment for bridge monitoring will continue to grow. Data management becomes a critical issue not only for storing the sensor data but also for integrating with the bridge model to support other functions, such as management, maintenance and inspection. The focus of this study is on the effective data management of bridge information and sensor data, which is crucial to structural health monitoring and life cycle management of bridge structures. We review the state-of-the-art of bridge information modeling and sensor data management, and propose a data management framework for bridge monitoring based on NoSQL database technologies that have been shown useful in handling high volume, time-series data and to flexibly deal with unstructured data schema. Specifically, Apache Cassandra and Mongo DB are deployed for the prototype implementation of the framework. This paper describes the database design for an XML-based Bridge Information Modeling (BrIM) schema, and the representation of sensor data using Sensor Model Language (SensorML). The proposed prototype data management framework is validated using data collected from the Yeongjong Bridge in Incheon, Korea.
The breaking of axisymmetric slender liquid bridges
NASA Astrophysics Data System (ADS)
Meseguer, J.
1983-05-01
Liquids held by surface tension forces can bridge the gap between two solid bodies placed not too far apart from each other. The equilibrium conditions and stability criteria for static, cylindrical liquid bridges are well known. However, the behaviour of an unstable liquid bridge, regarding both its transition toward breaking and the resulting configuration, is a matter for discussion. The dynamical problem of axisymmetric rupture of a long liquid bridge anchored at two equal coaxial disks is treated in this paper through the adoption of one-dimensional theories which are widely used in capillary jet problems.
Premalignant lesions skew spleen cell responses to immune modulation by adipocytes.
Vielma, Silvana A; Klein, Richard L; Levingston, Corinne A; Young, M Rita I
2013-05-01
Obesity can promote a chronic inflammatory state and is associated with an increased risk for cancer. Since adipocytes can produce mediators that can regulate conventional immune cells, this study sought to determine if the presence of premalignant oral lesions would skew how immune cells respond to adipocyte-derived mediators to create an environment that may be more favorable for their progression toward cancer. While media conditioned by adipocytes stimulated normal spleen cell production of the T helper (Th) type-1 cytokines interleukin (IL)-2, interferon-? (IFN-?), IL-12 and granulocyte-monocyte colony-stimulating factor (GM CSF), media from premalignant lesion cells either blocked or had no added affect on the adipocyte-stimulated Th1 cytokine production. In contrast, media conditioned by premalignant lesion cells exacerbated adipocyte-stimulated spleen cell production of the Th2 cytokines IL-10 and IL-13, although it did not further enhance the adipocyte-stimulated spleen cell production of IL-4 and TGF-?. The premalignant lesion environment also heightened the adipocyte-stimulated spleen cell production of the inflammatory mediators IL 1?, IL-1?, IL-6 and IL-9, although it did not further increase the adipocyte-stimulated production of tumor necrosis factor-? (TNF-?). IL 17 production was unaffected by the adipocyte-derived mediators, but was synergistically triggered by adding media from premalignant lesion cells. These stimulatory effects on spleen cell production of Th2 and inflammatory mediators were not induced in the absence of media conditioned by adipocytes. In contrast, media conditioned by adipocytes did not stimulate production of predominantly monocyte-derived chemokine C-X-C motif ligand (CXCL)9, chemokine C-C motif ligand (CCL)3 or CCL4, although it stimulated production of CCL2 and the predominantly T cell-derived chemokine CCL5, which was the only chemokine whose production was further increased by media from premalignant lesions. These results suggest that the responsiveness of spleen cells to adipocyte-derived mediators is influenced by mediators from premalignant lesion cells to favor conventional immune cell production of a Th2 and inflammatory cytokines. PMID:23645725
Olson, Scott A.; Weber, Matthew A.
1996-01-01
bridge consisting of four concrete spans. The maximum span length is 57 ft. (Vermont Agency of Transportation, written commun., July 29, 1994). The bridge is supported by vertical, concrete abutments and three concrete piers. The toe of the left abutment is at the channel edge. The toe of the right abutment is set back on the right over-bank. The roadway centerline on the structure has a slight horizontal curve; however, the main channel is skewed approximately 5 degrees to the bridge. Additional details describing conditions at the site are included in the Level II Summary and Appendices D and E. Scour depths and rock rip-rap sizes were computed using the general guidelines described in Hydraulic Engineering Circular 18 (Richardson and others, 1993). Scour depths were calculated assuming an infinite depth of erosive material and a homogeneous particle-size distribution. The scour analysis results are presented in tables 1 and 2 and a graph of the scour depths is presented in figure 8.
Capacitance bridge measurements of magnetostriction
NASA Astrophysics Data System (ADS)
Boley, Mark S.; Shin, Won C.; Rigsbee, David K.; Franklin, Doug A.
2002-05-01
Magnetostriction effects were investigated for three different materials by using a simple, reproducible, and cost-effective method recently developed in our laboratory. The magnetostriction effects were generated by a large oscillating magnetic field produced by a high current 60 Hz ac welder power supply, capable of reaching saturation levels for the material, and then detected by a change in capacitance between a hollow cylindrical sample and a concentric brass ring. This capacitance change was continuously monitored at a high frequency rate by a standard laboratory capacitance bridge meter. The output voltage of the bridge was fed into a storage cathode-ray oscilloscope and its voltage versus time signals were then analyzed by a computer program. Two ferromagnetic rings, constructed of high-speed steels 4620 and 4340, which have proven applicability for use in magnetoelastic torque sensing, were used as the samples for investigating the magnetostriction effects, while a paramagnetic aluminum ring was used for the control sample. Our study showed that the 4340 ring, which had higher nickel, cobalt, and chromium content than that of the 4620 ring, had the largest magnetostriction effect, and that the aluminum ring displayed no magnetostriction effect, as was expected. We have found this experimental method to be both reproducible and sufficient to rank different ferromagnetic materials by their magnetostriction level, which is a significant consideration in producing effective magnetoelastic torque sensors.
Bridge coupled drift tube linacs
Liska, D.; Smith, P.; Carlisle, L.; Larkin, T.
1992-01-01
Modern linac designs for treating radioactive waste achieve high proton currents through funneling at low energy, typically around 20 MeV. The resulting switch to a high-frequency accelerating structure poses severe performance and fabrication difficulties below 100 MeV. Above 100 MeV. proven coupled-cavity linacs (CCLS) am available. However, at 20 MeV one must choose between a high-frequency drift-tube linac (DTL) or a coupled-cavity linac with very short cells. Potential radiation damage from the CW beam, excessive RF power losses, multipactoring, and fabricability all enter into this decision. At Los Alamos, we have developed designs for a bridge-coupled DTL (BCDTL) that. like a CCL, uses lattice focusing elements and bridge couplers, but that unlike a CCL, accelerates the beam in simple. short, large-aperture DTL modules with no internal quadrupole focusing. Thus, the BCDTL consumes less power than the CCL linac without degrading beam performance and is simpler and cheaper to fabricate in the 20 to 100 MeV range.
Bridge coupled drift tube linacs
Liska, D.; Smith, P.; Carlisle, L.; Larkin, T.
1992-12-01
Modern linac designs for treating radioactive waste achieve high proton currents through funneling at low energy, typically around 20 MeV. The resulting switch to a high-frequency accelerating structure poses severe performance and fabrication difficulties below 100 MeV. Above 100 MeV. proven coupled-cavity linacs (CCLS) am available. However, at 20 MeV one must choose between a high-frequency drift-tube linac (DTL) or a coupled-cavity linac with very short cells. Potential radiation damage from the CW beam, excessive RF power losses, multipactoring, and fabricability all enter into this decision. At Los Alamos, we have developed designs for a bridge-coupled DTL (BCDTL) that. like a CCL, uses lattice focusing elements and bridge couplers, but that unlike a CCL, accelerates the beam in simple. short, large-aperture DTL modules with no internal quadrupole focusing. Thus, the BCDTL consumes less power than the CCL linac without degrading beam performance and is simpler and cheaper to fabricate in the 20 to 100 MeV range.
Bridges to sustainable tropical health
Singer, Burton H.; de Castro, Marcia Caldas
2007-01-01
Ensuring sustainable health in the tropics will require bridge building between communities that currently have a limited track record of interaction. It will also require new organizational innovation if much of the negative health consequences of large-scale economic development projects are to be equitably mitigated, if not prevented. We focus attention on three specific contexts: (i) forging linkages between the engineering and health communities to implement clean water and sanitation on a broad scale to prevent reworming, after the current deworming-only programs, of people by diverse intestinal parasites; (ii) building integrated human and animal disease surveillance infrastructure and technical capacity in tropical countries on the reporting and scientific evidence requirements of the sanitary and phytosanitary agreement under the World Trade Organization; and (iii) developing an independent and equitable organizational structure for health impact assessments as well as monitoring and mitigation of health consequences of economic development projects. Effective global disease surveillance and timely early warning of new outbreaks will require a far closer integration of veterinary and human medicine than heretofore. Many of the necessary surveillance components exist within separate animal- and human-oriented organizations. The challenge is to build the necessary bridges between them. PMID:17913894
NASA Astrophysics Data System (ADS)
Lantz, Juliette M.; Feindt, Jenny E.; Lewellyn, Eric P. B.; Walczak, Mary M.
1999-12-01
The Bridge of Mandolin County is a case designed to teach the general chemistry principles of molar mass, ions and aqueous reactions, solubility rules, and inorganic nomenclature. Through the instructor-facilitated class discussion, students consider the options before the Mandolin Town Council regarding deicing the newly constructed bridge connecting Mandolin with a large nearby city. The students must decipher contradictory claims made on behalf of sodium chloride, the traditional deicer, and calcium magnesium acetate, a new environmentally friendly deicer, to arrive at the most cost-effective and environmentally appropriate deicing product. As they work through the analysis they raise questions that can be addressed in a laboratory setting. Four optional role-playing experiments are included, which can be used by the students to gather information helpful to resolution of the case. The case is intended to be used over two class periods, with a laboratory period in between, though suggestions for other models are provided. Laboratory procedures include an EDTA titration for Ca2+ and Mg2+, a gravimetric analysis, a qualitative examination of ions and solubility, an introduction to freezing point depression and measurement, and an experimental design activity. This case can also successfully be used without alteration in non-majors chemistry or environmental chemistry courses, or upper-level analytical or environmental chemistry courses.
49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312 Transportation Other Regulations Relating to... SYSTEMS, DEVICES, AND APPLIANCES Interlocking Standards Â§ 236.312 Movable bridge, interlocking of...
49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 4 2014-10-01 2014-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312 Transportation Other Regulations Relating to... SYSTEMS, DEVICES, AND APPLIANCES Interlocking Standards Â§ 236.312 Movable bridge, interlocking of...
49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 4 2013-10-01 2013-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312 Transportation Other Regulations Relating to... SYSTEMS, DEVICES, AND APPLIANCES Interlocking Standards Â§ 236.312 Movable bridge, interlocking of...
49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312 Transportation Other Regulations Relating to... SYSTEMS, DEVICES, AND APPLIANCES Interlocking Standards Â§ 236.312 Movable bridge, interlocking of...
49 CFR 236.312 - Movable bridge, interlocking of signal appliances with bridge devices.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Movable bridge, interlocking of signal appliances with bridge devices. 236.312 Section 236.312 Transportation Other Regulations Relating to... SYSTEMS, DEVICES, AND APPLIANCES Interlocking Standards Â§ 236.312 Movable bridge, interlocking of...
6. VIEW OF GDOT BRIDGE NO. 02700268X00678N BRIDGE PLATE IDENTIFYING ...
6. VIEW OF GDOT BRIDGE NO. 027-00268X-00678N BRIDGE PLATE IDENTIFYING COUNTY COMMISSIONERS AT THE TIME OF CONSTRUCTION. - GDOT Bridge No. 027-00268X-00678N, County Road 268-Empress Road span Piscola Creek, Quitman, Brooks County, GA
33 CFR 115.50 - Application for bridge permits.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Application for bridge permits... BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES Â§ 115.50 Application for bridge permits. (a) Application. An application for authorization to construct a bridge across navigable waters...
49 CFR 237.103 - Bridge inspection procedures.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 4 2013-10-01 2013-10-01 false Bridge inspection procedures. 237.103 Section 237... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.103 Bridge inspection procedures. (a) Each bridge management program shall specify the procedure to be used...
33 CFR 115.50 - Application for bridge permits.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Application for bridge permits... BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES Â§ 115.50 Application for bridge permits. (a) Application. An application for authorization to construct a bridge across navigable waters...
49 CFR 237.107 - Conduct of bridge inspections.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Conduct of bridge inspections. 237.107 Section 237... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.107 Conduct of bridge inspections. Bridge inspections shall be conducted under the direct supervision of a...
33 CFR 115.50 - Application for bridge permits.
Code of Federal Regulations, 2010 CFR
2010-07-01
... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Application for bridge permits... BRIDGES BRIDGE LOCATIONS AND CLEARANCES; ADMINISTRATIVE PROCEDURES Â§ 115.50 Application for bridge permits. (a) Approval of plans. An application for authorization to construct a bridge across navigable...
33 CFR 118.70 - Lights on swing bridges.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Lights on swing bridges. 118.70 Section 118.70 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.70 Lights on swing bridges. (a) Swing span lights on through bridges....
33 CFR 118.85 - Lights on vertical lift bridges.
Code of Federal Regulations, 2011 CFR
2011-07-01
... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...
23 CFR 650.307 - Bridge inspection organization.
Code of Federal Regulations, 2013 CFR
2013-04-01
... 23 Highways 1 2013-04-01 2013-04-01 false Bridge inspection organization. 650.307 Section 650.307... BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards Â§ 650.307 Bridge inspection... bridges located on public roads that are fully or partially located within the State's boundaries,...
49 CFR 237.33 - Content of bridge management programs.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 4 2014-10-01 2014-10-01 false Content of bridge management programs. 237.33... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Railroad Bridge Safety Assurance Â§ 237.33 Content of bridge management programs. Each bridge management program adopted in compliance with this...
33 CFR 118.85 - Lights on vertical lift bridges.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...
23 CFR 650.307 - Bridge inspection organization.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 23 Highways 1 2012-04-01 2012-04-01 false Bridge inspection organization. 650.307 Section 650.307... BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards Â§ 650.307 Bridge inspection... bridges located on public roads that are fully or partially located within the State's boundaries,...
33 CFR 118.70 - Lights on swing bridges.
Code of Federal Regulations, 2012 CFR
2012-07-01
... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Lights on swing bridges. 118.70 Section 118.70 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.70 Lights on swing bridges. (a) Swing span lights on through bridges....
49 CFR 237.101 - Scheduling of bridge inspections.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 4 2014-10-01 2014-10-01 false Scheduling of bridge inspections. 237.101 Section... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.101 Scheduling of bridge inspections. (a) Each bridge management program shall include a provision for scheduling...
49 CFR 237.33 - Content of bridge management programs.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Content of bridge management programs. 237.33... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Railroad Bridge Safety Assurance Â§ 237.33 Content of bridge management programs. Each bridge management program adopted in compliance with this...
49 CFR 237.103 - Bridge inspection procedures.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Bridge inspection procedures. 237.103 Section 237... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.103 Bridge inspection procedures. (a) Each bridge management program shall specify the procedure to be used...
33 CFR 118.85 - Lights on vertical lift bridges.
Code of Federal Regulations, 2013 CFR
2013-07-01
... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...
49 CFR 237.103 - Bridge inspection procedures.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Bridge inspection procedures. 237.103 Section 237... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.103 Bridge inspection procedures. (a) Each bridge management program shall specify the procedure to be used...
49 CFR 237.101 - Scheduling of bridge inspections.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 4 2013-10-01 2013-10-01 false Scheduling of bridge inspections. 237.101 Section... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.101 Scheduling of bridge inspections. (a) Each bridge management program shall include a provision for scheduling...
23 CFR 650.409 - Evaluation of bridge inventory.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 23 Highways 1 2011-04-01 2011-04-01 false Evaluation of bridge inventory. 650.409 Section 650.409... BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program Â§ 650.409 Evaluation of bridge inventory. (a) Sufficiency rating of bridges. Upon receipt and evaluation of the...
49 CFR 237.31 - Adoption of bridge management programs.
Code of Federal Regulations, 2012 CFR
2012-10-01
... 49 Transportation 4 2012-10-01 2012-10-01 false Adoption of bridge management programs. 237.31... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Railroad Bridge Safety Assurance Â§ 237.31 Adoption of bridge management programs. Each track owner shall adopt a bridge safety management program...
49 CFR 237.31 - Adoption of bridge management programs.
Code of Federal Regulations, 2014 CFR
2014-10-01
... 49 Transportation 4 2014-10-01 2014-10-01 false Adoption of bridge management programs. 237.31... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Railroad Bridge Safety Assurance Â§ 237.31 Adoption of bridge management programs. Each track owner shall adopt a bridge safety management program...
23 CFR 650.307 - Bridge inspection organization.
Code of Federal Regulations, 2011 CFR
2011-04-01
... 23 Highways 1 2011-04-01 2011-04-01 false Bridge inspection organization. 650.307 Section 650.307... BRIDGES, STRUCTURES, AND HYDRAULICS National Bridge Inspection Standards Â§ 650.307 Bridge inspection... bridges located on public roads that are fully or partially located within the State's boundaries,...
23 CFR 650.409 - Evaluation of bridge inventory.
Code of Federal Regulations, 2012 CFR
2012-04-01
... 23 Highways 1 2012-04-01 2012-04-01 false Evaluation of bridge inventory. 650.409 Section 650.409... BRIDGES, STRUCTURES, AND HYDRAULICS Highway Bridge Replacement and Rehabilitation Program Â§ 650.409 Evaluation of bridge inventory. (a) Sufficiency rating of bridges. Upon receipt and evaluation of the...
49 CFR 237.103 - Bridge inspection procedures.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Bridge inspection procedures. 237.103 Section 237... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.103 Bridge inspection procedures. (a) Each bridge management program shall specify the procedure to be used...
33 CFR 118.70 - Lights on swing bridges.
Code of Federal Regulations, 2014 CFR
2014-07-01
... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Lights on swing bridges. 118.70 Section 118.70 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS Â§ 118.70 Lights on swing bridges. (a) Swing span lights on through bridges....
49 CFR 237.33 - Content of bridge management programs.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 4 2013-10-01 2013-10-01 false Content of bridge management programs. 237.33... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Railroad Bridge Safety Assurance Â§ 237.33 Content of bridge management programs. Each bridge management program adopted in compliance with this...
49 CFR 237.101 - Scheduling of bridge inspections.
Code of Federal Regulations, 2010 CFR
2010-10-01
... 49 Transportation 4 2010-10-01 2010-10-01 false Scheduling of bridge inspections. 237.101 Section... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.101 Scheduling of bridge inspections. (a) Each bridge management program shall include a provision for scheduling...
49 CFR 237.101 - Scheduling of bridge inspections.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Scheduling of bridge inspections. 237.101 Section... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.101 Scheduling of bridge inspections. (a) Each bridge management program shall include a provision for scheduling...
49 CFR 237.107 - Conduct of bridge inspections.
Code of Federal Regulations, 2013 CFR
2013-10-01
... 49 Transportation 4 2013-10-01 2013-10-01 false Conduct of bridge inspections. 237.107 Section 237... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Bridge Inspection Â§ 237.107 Conduct of bridge inspections. Bridge inspections shall be conducted under the direct supervision of a...
49 CFR 237.31 - Adoption of bridge management programs.
Code of Federal Regulations, 2011 CFR
2011-10-01
... 49 Transportation 4 2011-10-01 2011-10-01 false Adoption of bridge management programs. 237.31... ADMINISTRATION, DEPARTMENT OF TRANSPORTATION BRIDGE SAFETY STANDARDS Railroad Bridge Safety Assurance Â§ 237.31 Adoption of bridge management programs. Each track owner shall adopt a bridge safety management program...