Metric adjusted skew information
Hansen, Frank
2008-01-01
We extend the concept of Wigner-Yanase-Dyson skew information to something we call "metric adjusted skew information" (of a state with respect to a conserved observable). This "skew information" is intended to be a non-negative quantity bounded by the variance (of an observable in a state) that...... vanishes for observables commuting with the state. We show that the skew information is a convex function on the manifold of states. It also satisfies other requirements, proposed by Wigner and Yanase, for an effective measure-of-information content of a state relative to a conserved observable. We...... establish a connection between the geometrical formulation of quantum statistics as proposed by Chentsov and Morozova and measures of quantum information as introduced by Wigner and Yanase and extended in this article. We show that the set of normalized Morozova-Chentsov functions describing the possible...
Metric-adjusted skew information
Liang, Cai; Hansen, Frank
2010-01-01
We give a truly elementary proof of the convexity of metric-adjusted skew information following an idea of Effros. We extend earlier results of weak forms of superadditivity to general metric-adjusted skew information. Recently, Luo and Zhang introduced the notion of semi-quantum states on a...... bipartite system and proved superadditivity of the Wigner-Yanase-Dyson skew informations for such states. We extend this result to the general metric-adjusted skew information. We finally show that a recently introduced extension to parameter values 1 < p = 2 of the WYD-information is a special case of...... (unbounded) metric-adjusted skew information....
Inequalities for quantum skew information
Audenaert, Koenraad; Cai, Liang; Hansen, Frank
2008-01-01
We study quantum information inequalities and show that the basic inequality between the quantum variance and the metric adjusted skew information generates all the multi-operator matrix inequalities or Robertson type determinant inequalities studied by a number of authors. We introduce an order...... relation on the set of functions representing quantum Fisher information that renders the set into a lattice with an involution. This order structure generates new inequalities for the metric adjusted skew informations. In particular, the Wigner-Yanase skew information is the maximal skew information with...
Quantum Fisher and Skew information for Unruh accelerated Dirac qubit
Banerjee, Subhashish; Omkar, S
2015-01-01
We develop a Bloch vector representation of Unruh channel for a Dirac field mode. This is used to provide a unified, analytical treatment of quantum Fisher and Skew information for a qubit subjected to the Unruh channel, both in its pure form as well as in the presence of experimentally relevant external noise channels. The time evolution of Fisher and Skew information is studied along with the impact of external environment parameters such as temperature and squeezing. The external noises are modelled by both purely dephasing phase damping as well as the squeezed generalized amplitude damping channels. An interesting interplay between the external reservoir temperature and squeezing on the Fisher and Skew information is observed, in particular, for the action of the squeezed generalized amplitude damping channel. It is seen that for some regimes, squeezing can enhance the quantum information against the deteriorating influence of the ambient environment. Similar features are also observed for the analogous s...
Sum uncertainty relations based on Wigner-Yanase skew information
Chen, Bin; Fei, Shao-Ming; Long, Gui-Lu
2016-06-01
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.
Conserving Capital by Adjusting Deltas for Gamma in the Presence of Skewness
Dilip B. Madan
2010-12-01
Full Text Available An argument for adjusting Black Scholes implied call deltas downwards for a gamma exposure in a left skewed market is presented. It is shown that when the objective for the hedge is the conservation of capital ignoring the gamma for the delta position is expensive. The gamma adjustment factor in the static case is just a function of the risk neutral distribution. In the dynamic case one may precompute at the date of trade initiation a matrix of delta levels as a function of the underlying for the life of the trade and subsequently one just has to look up the matrix for the hedge. Also constructed are matrices for the capital reserve, the pro¯t, leverage and rate of return remaining in the trade as a function of the spot at a future date in the life of the trade. The concepts of pro¯t, capital, leverage and return are as described in Carr, Madan and Vicente Alvarez (2010. The dynamic computations constitute an application of the theory of nonlinear expectations as described in Cohen and Elliott (2010.
Shannon Entropy and Mutual Information for Multivariate Skew-Elliptical Distributions
Arellano-Valle, Reinaldo B.
2012-02-27
The entropy and mutual information index are important concepts developed by Shannon in the context of information theory. They have been widely studied in the case of the multivariate normal distribution. We first extend these tools to the full symmetric class of multivariate elliptical distributions and then to the more flexible families of multivariate skew-elliptical distributions. We study in detail the cases of the multivariate skew-normal and skew-t distributions. We implement our findings to the application of the optimal design of an ozone monitoring station network in Santiago de Chile. © 2012 Board of the Foundation of the Scandinavian Journal of Statistics.
Vision Based Extraction of Nutrition Information from Skewed Nutrition Labels
Zaman, Tanwir
2016-01-01
An important component of a healthy diet is the comprehension and retention of nutritional information and understanding of how different food items and nutritional constituents affect our bodies. In the U.S. and many other countries, nutritional information is primarily conveyed to consumers through nutrition labels (NLs) which can be found in all packaged food products. However, sometimes it becomes really challenging to utilize all this information available in these NLs even for consumers...
The on-momentum description of linear coupling between horizontal and vertical betatron motion is extended to include off-momentum particles, introducing a vector quantity called the ''skew chromaticity''. This vector tends to be long in large superconducting storage rings, where it restricts the available working space in the tune plane, and modifies collective effect stability criteria. Skew chromaticity measurements at the Cornell Electron Storage Ring (CESR) and at the Fermilab Tevatron are reported, as well as tracking results from the Relativistic Heavy Ion Collider (RHIC). The observation of anomalous head-tail beam Iowa new the tune diagonal in the Tevatron are explained in terms of the extended theory, including modified criteria for headtail stability. These results are confirmed in head-tail simulations. Sources of skew chromaticity are investigated
Analyzing Fish Condition Factor Index Through Skew-Gaussian Information Theory Quantifiers
Contreras-Reyes, Javier E.
2016-06-01
Biological-fishery indicators have been widely studied. As such the condition factor (CF) index, which interprets the fatness level of a certain species based on length and weight, has been investigated, too. However, CF has been studied without considering its temporal features and distribution. In this paper, we analyze the CF time series via skew-gaussian distributions that consider the asymmetry produced by extreme events. This index is characterized by a threshold autoregressive model and corresponds to a stationary process depending on the shape parameter of the skew-gaussian distribution. Then we use the Jensen-Shannon (JS) distance to compare CF by length classes. This distance has mathematical advantages over other divergences such as Kullback-Leibler and Jeffrey’s, and the triangular inequality property. Our results are applied to a biological catalogue of anchovy (Engraulis ringens) from the northern coast of Chile, for the period 1990-2010 that consider monthly CF time series by length classes and sex. We find that for high values of shape parameter, JS distance tends to be more sensible to detect discrepancies than Jeffrey’s divergence. In addition, the body condition of male anchovies with higher lengths coincides with the ending of the moderate-strong El Niño event 91-92 and for both males and females, the smaller lengths coincide with the beginning of the strong El Niño event 97-98.
Kinyon, Michael
2012-01-01
Categorical skew lattices are a variety of skew lattices on which the natural partial order is especially well behaved. While most skew lattices of interest are categorical, not all are. They are characterized by a countable family of forbidden subalgebras. We also consider the subclass of strictly categorical skew lattices.
Evaluation of an adjustable epidemiologic information system.
Jiunn-Shyan Julian Wu
Full Text Available BACKGROUND: In order to facilitate public health response and to achieve early control of infectious disease epidemics, an adjustable epidemiologic information system (AEIS was established in the Taiwan public health network in February 2006. METHODOLOGY/PRINCIPAL FINDINGS: The performance of AEIS for the period 2006 through 2008 was evaluated based on a number of response times (RT and the public health impact. After implementation of the system, the apparent overall shortened RT was mainly due to the shortening of personnel response time (PRT and the time needed to draft a new questionnaire that incurred as personnel-system interface (PSI; PRT dropped from a fluctuating range of 9.8 ∼28.8 days in the first four months to <10 days in the following months and remained low till 2008 (0.88±1.52 days. The PSIs for newly emerged infectious diseases were 2.6 and 3.4 person-hours for H5N1 in 2007 and chikungunya in 2008, respectively, a much improvement from 1142.5 person-hours for SARS in 2003. The duration of each rubella epidemic cluster was evaluated as public health impact and showed a shortening trend (p = 0.019 that concurred with the shortening of PRT from 64.8±47.3 to 25.2±38.2 hours per cluster (p<0.0001. CONCLUSIONS/SIGNIFICANCE: The first evaluation of the novel instrument AEIS that had been used to assist Taiwan's multi-level government for infectious diseases control demonstrated that it was well integrated into the existing public health infrastructure. It provided flexible tools and computer algorithms with friendly interface for timely data collection, integration, and analysis; as a result, it shortened RTs, filled in gaps of personnel lacking sufficient experiences, created a more efficient flow of response, and identified asymptomatic/mild cases early to minimize further spreading. With further development, AEIS is anticipated to be useful in the application of other acute public health events needing immediate
Trade, Informal Employment and Labor Adjustment Costs
Arias, Javier; Artuc, Erhan; Lederman, Daniel; Rojas, Diego
2013-01-01
Informal employment is ubiquitous in developing countries, but few studies have estimated workers' switching costs between informal and formal employment. This paper builds on the empirical literature grounded in discrete choice models to estimate these costs. The results suggest that inter-industry labor mobility costs are large, but entry costs into informal employment are significantly ...
Gadi, Manoel Fernando Alonso; Lago, Alair Pereira do; Mehnen, Jorn
2010-01-01
This work provided a brief introduction to pratical problem solving for machine learning with skewed data sets. Classiï¬cation methods are generally not designed to cope with skewed data, thus, various action have to be taken when dealing with imbalanced data sets. For a reader looking for more information about the ï¬eld we can recommend a nice editorial by Chawla et al. ? and three conference proceedings Chawla et al. (2003); Dietterich et al. (2000); Japkowicz (2000). In addition, good a...
Skewness preference across countries
Adam Zaremba
2015-07-01
Full Text Available Prospect theory implies that assets with positively skewed returns should be traded at premium to assets with negative skewness. We hypothesize that in the integrated financial markets this concept should also hold for the entire country equity portfolios. This article examines the linkages between the country-level expected returns and past skewness. We evidence a robust negative relationship between skewness and future returns. The phenomenon is most significant within large, liquid, developed, and open stock markets. Additional sorts on skewness can improve performance of both cross-country value and momentum strategies. The study is based on the sorting and cross-sectional tests conducted within a sample of 78 country equity markets for years 1999-2014.
Harishchandra S. Ramane
2016-03-01
Full Text Available Let $D$ be a digraph with skew-adjacency matrix $S(D$. The skew energy of $D$ is defined as the sum of the norms of all eigenvalues of $S(D$. Two digraphs are said to be skew equienergetic if their skew energies are equal. We establish an expression for the characteristic polynomial of the skew adjacency matrix of the join of two digraphs, and for the respective skew energy, and thereby construct non-cospectral, skew equienergetic digraphs on $n$ vertices, for all $n geq 6$. Thus we arrive at the solution of some open problems proposed in [X. Li, H. Lian, A survey on the skew energy of oriented graphs, arXiv:1304.5707].
Mixtures of skewed Kalman filters
Kim, Hyoungmoon
2014-01-01
Normal state-space models are prevalent, but to increase the applicability of the Kalman filter, we propose mixtures of skewed, and extended skewed, Kalman filters. To do so, the closed skew-normal distribution is extended to a scale mixture class of closed skew-normal distributions. Some basic properties are derived and a class of closed skew. t distributions is obtained. Our suggested family of distributions is skewed and has heavy tails too, so it is appropriate for robust analysis. Our proposed special sequential Monte Carlo methods use a random mixture of the closed skew-normal distributions to approximate a target distribution. Hence it is possible to handle skewed and heavy tailed data simultaneously. These methods are illustrated with numerical experiments. © 2013 Elsevier Inc.
Brodal, Gerth Stølting; Moruz, Gabriel
2006-01-01
It is well-known that to minimize the number of comparisons a binary search tree should be perfectly balanced. Previous work has shown that a dominating factor over the running time for a search is the number of cache faults performed, and that an appropriate memory layout of a binary search tree...... can reduce the number of cache faults by several hundred percent. Motivated by the fact that during a search branching to the left or right at a node does not necessarily have the same cost, e.g. because of branch prediction schemes, we in this paper study the class of skewed binary search trees. For...... all nodes in a skewed binary search tree the ratio between the size of the left subtree and the size of the tree is a fixed constant (a ratio of 1/2 gives perfect balanced trees). In this paper we present an experimental study of various memory layouts of static skewed binary search trees, where each...
ADJUSTMENT OF LEVELING NETWORK BY INFORMATION SPREAD ESTIMATION
无
2001-01-01
In practical parameter estimation,we have always chosen eitherLeast Squares Estimation(LSE) or Robust Estimation.Since the distribution of observations is unknown,to select a correct estimation method is very difficult.It is well known that if observations include gross errors,the result of LSE will be badly containinated.On the other hand,if observations do not include any gross errors,the result of robust estimation is not as good as that of LSE.To solve this problem,Wang (1999) developed an estimation method called Information Spread Estimation (ISE) based on the information spread principle.The ISE is a very good method for estimating one parameter which is very robust.However, most of instances in surveying data processing are multi-parameters' estimation,owing to the inherent restrictions of ISE,it can not be applied to the surveying data processing directly.To apply the good method to the field of surveying data processing widely,the author has done the research deeply.This paper applies ISE successfully to the adjustment of leveling network by using the specialties of leveling.
Measuring Skewness: A Forgotten Statistic?
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…
Einstein manifolds with skew torsion
Agricola, Ilka; Ferreira, Ana Cristina
2012-01-01
This paper is devoted to the first systematic investigation of manifolds that are Einstein for a connection with skew symmetric torsion. We derive the Einstein equation from a variational principle and prove that, for parallel torsion, any Einstein manifold with skew torsion has constant scalar curvature; and if it is complete of positive scalar curvature, it is necessarily compact and it has finite first fundamental group. The longest part of the paper is devoted to the systematic constructi...
2011-12-01
... 2000. See Changes to Implement Patent Term Adjustment Under Twenty- Year Patent ] Term, 65 FR 56366... provide patent term adjustment for certain delays during the patent examination process. See Public Law... Provisions Relating to Appellate Review and Information Disclosure Statements, 76 FR 18990 (Apr. 6,...
$\\alpha $ -Skew $\\pi $ -McCoy Rings
Areej M. Abduldaim; Chen, Sheng
2013-01-01
As a generalization of $\\alpha $ -skew McCoy rings, we introduce the concept of $\\alpha $ -skew $\\pi $ -McCoy rings, and we study the relationships with another two new generalizations, $\\alpha $ -skew ${\\pi }_{1}$ -McCoy rings and $\\alpha $ -skew ${\\pi }_{2}$ -McCoy rings, observing the relations with $\\alpha $ -skew McCoy rings, $\\pi $ -McCoy rings, $\\alpha $ -skew Armendariz rings, $\\pi $ -regular rings, and other kinds of rings. Also, we investigate conditions such that $\\alpha $ -skew ${...
Information bias in health research: definition, pitfalls, and adjustment methods
Althubaiti A
2016-01-01
Alaa Althubaiti Department of Basic Medical Sciences, College of Medicine, King Saud bin Abdulaziz University for Health Sciences, Riyadh, Saudi Arabia Abstract: As with other fields, medical sciences are subject to different sources of bias. While understanding sources of bias is a key element for drawing valid conclusions, bias in health research continues to be a very sensitive issue that can affect the focus and outcome of investigations. Information bias, otherwise known as misclassific...
Information bias in health research: definition, pitfalls, and adjustment methods
Althubaiti, Alaa
2016-01-01
As with other fields, medical sciences are subject to different sources of bias. While understanding sources of bias is a key element for drawing valid conclusions, bias in health research continues to be a very sensitive issue that can affect the focus and outcome of investigations. Information bias, otherwise known as misclassification, is one of the most common sources of bias that affects the validity of health research. It originates from the approach that is utilized to obtain or confir...
Multivariate extended skew-t distributions and related families
Arellano-Valle, Reinaldo B.
2010-12-01
A class of multivariate extended skew-t (EST) distributions is introduced and studied in detail, along with closely related families such as the subclass of extended skew-normal distributions. Besides mathematical tractability and modeling flexibility in terms of both skewness and heavier tails than the normal distribution, the most relevant properties of the EST distribution include closure under conditioning and ability to model lighter tails as well. The first part of the present paper examines probabilistic properties of the EST distribution, such as various stochastic representations, marginal and conditional distributions, linear transformations, moments and in particular Mardia’s measures of multivariate skewness and kurtosis. The second part of the paper studies statistical properties of the EST distribution, such as likelihood inference, behavior of the profile log-likelihood, the score vector and the Fisher information matrix. Especially, unlike the extended skew-normal distribution, the Fisher information matrix of the univariate EST distribution is shown to be non-singular when the skewness is set to zero. Finally, a numerical application of the conditional EST distribution is presented in the context of confidential data perturbation.
Cooperation in a dynamical adjustment of duopoly game with incomplete information
In the output competition of Cournot game, the adjustment of output is considered under the circumstances that participants have incomplete information. In this paper, two strategies with output's adjustment are mainly discussed: the tit-for-tat strategy and the tit-for-tat strategy with cooperative intention and their dynamic systems, respectively. The result shows that the tit-for-tat strategy may lead to the cooperation of them, but the stability of adjustment system is sensitive to the parameters; while the tit-for-tat strategy with cooperative intention can make the Pareto Optimality stable within the parameters' certain scope.
Agrawal, Prateek; Chacko, Zackaria; Fortes, Elaine C. F. S.; Kilic, Can
2015-01-01
We explore a novel flavor structure in the interactions of dark matter with the Standard Model. We consider theories in which both the dark matter candidate, and the particles that mediate its interactions with the Standard Model fields, carry flavor quantum numbers. The interactions are skewed in flavor space, so that a dark matter particle does not directly couple to the Standard Model matter fields of the same flavor, but only to the other two flavors. This framework respects Minimal Flavo...
Optimal Weak Lensing Skewness Measurements
Zhang, T J; Zhang, P; Dubinski, J; Zhang, Tong-Jie; Pen, Ue-Li; Zhang, Pengjie; Dubinski, John
2003-01-01
Weak lensing measurements are entering a precision era to statistically map the distribution of matter in the universe. The most common measurement has been of the variance of the projected surface density of matter, which corresponds to the induced correlation in alignments of background galaxies. This measurement of the fluctuations is insensitive to the total mass content, like using waves on the ocean to measure its depths. But when the depth is shallow as happens near a beach, waves become skewed. Similarly, a measurement of skewness in the projected matter distribution directly measures the total matter content of the universe. While skewness has already been convincingly detected, its constraint on cosmology is still weak. We address optimal analyses for the CFHT Legacy Survey in the presence of noise. We show that a compensated Gaussian filter with a width of 2.5 arc minutes optimizes the cosmological constraint, yielding $\\Delta \\Omega_m/\\Omega_m\\sim 10%$. This is significantly better than other filt...
Bicalho, Millena Drumond; Soares, Danielly Botelho; Botoni, Fernando Antonio; Reis, Adriano Max Moreira; Martins, Maria Auxiliadora Parreiras
2015-09-01
: Hospitalized patients require the use of a variety of drugs, many of which individually or in combination have the potential to cause kidney damage. The use of potentially nephrotoxic drugs is often unavoidable, and the need for dose adjustment should be evaluated. This study is aimed at assessing concordance in information on drug-induced nephrotoxicity and dose adjustment recommendations by comparing four drug information sources (DRUGDEX(®), UpToDate(®), Medscape(®) and the Brazilian Therapeutic Formulary) using the formulary of a Brazilian public hospital. A total of 218 drugs were investigated. The global Fleiss' kappa coefficient was 0.265 for nephrotoxicity (p < 0.001; CI 95%, 0.211-0.319) and 0.346 for recommendations (p < 0.001; CI 95%, 0.292-0.401), indicating fair concordance among the sources. Anti-infectives and anti-hypertensives were the main drugs cited as nephrotoxic by the different sources. There were no clear definitions for qualitative data or quantitative values for dose adjustments among the four information sources. There was no advice for dosing for a large number of the drugs in the international databases. The National Therapeutic Formulary offered imprecise dose adjustment recommendations for many nephrotoxic drugs. Discrepancies among information sources may have a clinical impact on patient care and contribute to drug-related morbidity and mortality. PMID:26371029
The skewness of elliptic flow fluctuations
Giacalone, Giuliano; Noronha-Hostler, Jacquelyn; Ollitrault, Jean-Yves
2016-01-01
Using event-by-event hydrodynamic calculations, we find that the fluctuations of the elliptic flow ($v_2$) in the reaction plane have a negative skew. Comparing the skewness of the $v_2$ fluctuations to that of the initial eccentricity fluctuations, we show that skewness is the main effect that separates higher-order cumulants. Furthermore, negative skew corresponds to the hierarchy $v_2\\{4\\}>v_2\\{6\\}$ observed in Pb+Pb collisions at the LHC. We describe how the skewness can be measured experimentally and show that hydrodynamics naturally reproduces its magnitude and centrality dependence.
2012-02-10
... AFFAIRS Agency Information Collection (Survey of Post-Deployment Adjustment Among OEF and OIF Veterans...'' in any correspondence. FOR FURTHER INFORMATION CONTACT: Denise McLamb, Enterprise Records Service....'' SUPPLEMENTARY INFORMATION: Title: Survey of Post-Deployment Adjustment Among OEF and OIF Veterans, VA Form...
The Bootstrap Approach for Testing Skewness Persistence
Krishnamurty Muralidhar
1993-01-01
This study presents a new methodology for testing changes in skewness between time periods (or samples) using the bootstrap method. A Monte Carlo simulation experiment was conducted to compare the effectiveness of the bootstrap method with the method suggested by Lau, Wingender and Lau (1989) to test skewness persistence. The results show the bootstrap method to be more powerful than the other method. The bootstrap method was also used to determine the persistence of skewness in stock returns...
Correcting Quadrupole Roll in Magnetic Lenses with Skew Quadrupoles
Walstrom, Peter Lowell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
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 ×10 lens with so-called ”Russian” 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 “non-local” 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
Agrawal, Prateek; Fortes, Elaine C F S; Kilic, Can
2015-01-01
We explore a novel flavor structure in the interactions of dark matter with the Standard Model. We consider theories in which both the dark matter candidate, and the particles that mediate its interactions with the Standard Model fields, carry flavor quantum numbers. The interactions are skewed in flavor space, so that a dark matter particle does not directly couple to the Standard Model matter fields of the same flavor, but only to the other two flavors. This framework respects Minimal Flavor Violation, and is therefore naturally consistent with flavor constraints. We study the phenomenology of a benchmark model in which dark matter couples to right-handed charged leptons. In large regions of parameter space the dark matter can emerge as a thermal relic, while remaining consistent with the constraints from direct and indirect detection. The collider signatures of this scenario include events with multiple leptons and missing energy. These events exhibit a characteristic flavor pattern that may allow this cla...
Cramer rule over quaternion skew field
Kyrchei, Ivan
2007-01-01
New definitions of determinant functionals over the quaternion skew field are given in this paper. The inverse matrix over the quaternion skew field is represented by analogues of the classical adjoint matrix. Cramer rule for right and left quaternionic systems of linear equations have been obtained.
Angular Distribution of Clustersin Skewed CDM Models
Borgani, S; Plionis, M
1994-01-01
We perform a detailed investigation of the statistical properties of the projected distribution of galaxy clusters obtained in Cold Dark Matter (CDM) models with both Gaussian and skewed primordial density fluctuations. We use N-body simulations to construct a set artificial Lick maps. An objective cluster--finding algorithm is used to identify clusters of different richness. For Gaussian models, the overall number of clusters is too small in the standard CDM case, but a model with higher normalisation fares much better; non--Gaussian models with negative skewness also fit faily well. We apply several statistical tests to compare real and simulated cluster samples, such as the 2-point correlation function, the minimal spanning tree construction, the multifractal analysis and the skewness of cell counts. The emerging picture is that Gaussian models, even with a higher normalization, are in trouble. Skew-positive models are also ruled out, while skew-negative models can reproduce the observed clustering of gala...
Skewed factor models using selection mechanisms
Kim, Hyoung-Moon
2015-12-21
Traditional factor models explicitly or implicitly assume that the factors follow a multivariate normal distribution; that is, only moments up to order two are involved. However, it may happen in real data problems that the first two moments cannot explain the factors. Based on this motivation, here we devise three new skewed factor models, the skew-normal, the skew-tt, and the generalized skew-normal factor models depending on a selection mechanism on the factors. The ECME algorithms are adopted to estimate related parameters for statistical inference. Monte Carlo simulations validate our new models and we demonstrate the need for skewed factor models using the classic open/closed book exam scores dataset.
RGB-D SLAM Based on Extended Bundle Adjustment with 2D and 3D Information.
Di, Kaichang; Zhao, Qiang; Wan, Wenhui; Wang, Yexin; Gao, Yunjun
2016-01-01
In the study of SLAM problem using an RGB-D camera, depth information and visual information as two types of primary measurement data are rarely tightly coupled during refinement of camera pose estimation. In this paper, a new method of RGB-D camera SLAM is proposed based on extended bundle adjustment with integrated 2D and 3D information on the basis of a new projection model. First, the geometric relationship between the image plane coordinates and the depth values is constructed through RGB-D camera calibration. Then, 2D and 3D feature points are automatically extracted and matched between consecutive frames to build a continuous image network. Finally, extended bundle adjustment based on the new projection model, which takes both image and depth measurements into consideration, is applied to the image network for high-precision pose estimation. Field experiments show that the proposed method has a notably better performance than the traditional method, and the experimental results demonstrate the effectiveness of the proposed method in improving localization accuracy. PMID:27529256
RGB-D SLAM Based on Extended Bundle Adjustment with 2D and 3D Information
Kaichang Di
2016-08-01
Full Text Available In the study of SLAM problem using an RGB-D camera, depth information and visual information as two types of primary measurement data are rarely tightly coupled during refinement of camera pose estimation. In this paper, a new method of RGB-D camera SLAM is proposed based on extended bundle adjustment with integrated 2D and 3D information on the basis of a new projection model. First, the geometric relationship between the image plane coordinates and the depth values is constructed through RGB-D camera calibration. Then, 2D and 3D feature points are automatically extracted and matched between consecutive frames to build a continuous image network. Finally, extended bundle adjustment based on the new projection model, which takes both image and depth measurements into consideration, is applied to the image network for high-precision pose estimation. Field experiments show that the proposed method has a notably better performance than the traditional method, and the experimental results demonstrate the effectiveness of the proposed method in improving localization accuracy.
Investment Analysis and the Adjustment of Stock Prices to Common Information.
Brennan, Michael J; Jegadeesh, Narasimhan; Swaminathan, Bhaskaran
1993-01-01
In this article we are concerned with the effect of the number of investment analysts following a firm on the speed of adjustment of the firm's stock price to new information that has common effects across firms. It is found that returns on portfolios of firms that are followed by many analysts tend to lead those of firms that are followed by fewer analysts, even when the firms are of approximately the same size. Many analyst firms also tend to respond more rapidly to market returns than do f...
Agrawal, Prateek; Chacko, Zackaria; Fortes, Elaine C. F. S.; Kilic, Can
2016-05-01
We explore a novel flavor structure in the interactions of dark matter with the Standard Model. We consider theories in which both the dark matter candidate, and the particles that mediate its interactions with the Standard Model fields, carry flavor quantum numbers. The interactions are skewed in flavor space, so that a dark matter particle does not directly couple to the Standard Model matter fields of the same flavor, but only to the other two flavors. This framework respects minimal flavor violation and is, therefore, naturally consistent with flavor constraints. We study the phenomenology of a benchmark model in which dark matter couples to right-handed charged leptons. In large regions of parameter space, the dark matter can emerge as a thermal relic, while remaining consistent with the constraints from direct and indirect detection. The collider signatures of this scenario include events with multiple leptons and missing energy. These events exhibit a characteristic flavor pattern that may allow this class of models to be distinguished from other theories of dark matter.
Skewness of the standard model possible implications
In this paper we consider combinations of gauge algebra and set of rules for quantization of gauge charges. We show that the combination of the algebra of the standard model and the rule satisfied by the electric charges of the quarks and leptons has an exceptional high degree of a kind of asymmetry which we call skewness. Assuming that skewness has physical significance and adding two other rather plausible assumptions, we may conclude that space time must have a non simply connected topology on very small distances. Such topology would allow a kind of symmetry breakdown leading to a more skew combination of gauge algebra and set of quantization rules. (orig.)
KEKB operation with skew sextupole magnets
A new set of magnets, the skew sextupole magnets, were designed, manufactured and installed in the KEKB tunnel during the three month shutdown of January, February and March, 2009. Twenty magnets were installed in the HER and eight magnets were installed in the LER, respectively. The skew sextupole magnets are used to correct for the chromatic x-y coupling at the interaction point (IP). A significant luminosity boost was achieved. The skew magnet outline and operation with these magnets are described in this report. (author)
A Simple Class of Measures of Skewness
ALTINAY, Galip
2016-01-01
In this paper, a simple class of measures for detecting skewness in samples is introduced. The new class of measures is based on a new definition of skewness that takes midrange into consideration. The proposed coefficients of skewness can be computed easily with only three of the summary statistics, i.e., the minimum value, the maximum value and the median (or the mode, or the mean). Another advantage of the new statistics is that they are bounded by -1 and +1, hence, the coefficients of ske...
Automatic Time Skew Detection and Correction
Korchagin, Danil
2011-01-01
In this paper, we propose a new approach for the automatic time skew detection and correction for multisource audiovisual data, recorded by different cameras/recorders during the same event. All recorded data are successfully tested for potential time skew problem and corrected based on ASR-related features. The core of the algorithm is based on perceptual time-quefrency analysis with a precision of 10 ms. The results show correct time skew detection and elimination in 100% of cases for a rea...
A New Method to Minimize the Clock Skew to Enhance Performance of Digital System
N. Suresh Kumar,; J. Anitha; M.S.S. Praveen,; N. Asok Kumar,; R. Ajay Suresh Babu
2010-01-01
A Pipe line technology is used in any digital system to perform multiple tasks simultaneously and to reduce the data losses in data transactions. But the conventional pipeline system is facing problems due to improper synchronization of clock pulses. This is a universal problem in all the digital systems mostly called jitter or skew. Inmost of the digital systems the propagation of information mainly controlled on the basis of clock pulses. In most of the digital systems the clock skew decrea...
Skewed X-inactivation in cloned mice
In female mammals, dosage compensation for X-linked genes is accomplished by inactivation of one of two X chromosomes. The X-inactivation ratio (a percentage of the cells with inactivated maternal X chromosomes in the whole cells) is skewed as a consequence of various genetic mutations, and has been observed in a number of X-linked disorders. We previously reported that phenotypically normal full-term cloned mouse fetuses had loci with inappropriate DNA methylation. Thus, cloned mice are excellent models to study abnormal epigenetic events in mammalian development. In the present study, we analyzed X-inactivation ratios in adult female cloned mice (B6C3F1). Kidneys of eight naturally produced controls and 11 cloned mice were analyzed. Although variations in X-inactivation ratio among the mice were observed in both groups, the distributions were significantly different (Ansary-Bradley test, P < 0.01). In particular, 2 of 11 cloned mice showed skewed X-inactivation ratios (19.2% and 86.8%). Similarly, in intestine, 1 of 10 cloned mice had a skewed ratio (75.7%). Skewed X-inactivation was observed to various degrees in different tissues of different individuals, suggesting that skewed X-inactivation in cloned mice is the result of secondary cell selection in combination with stochastic distortion of primary choice. The present study is the first demonstration that skewed X-inactivation occurs in cloned animals. This finding is important for understanding both nuclear transfer technology and etiology of X-linked disorders
Maternal Differential Treatment and Child Adjustment: A Multi-Informant Approach
Coldwell, Joanne; Pike, Alison; Dunn, Judy
2008-01-01
The study aimed to replicate previous links with children's adjustment as well as using children's reports of maternal differential treatment (MDT) to test whether difference scores or favouritism scores demonstrate stronger links with child outcome. Finally, it tested for a unique prediction of children's adjustment from distinct aspects and…
XU; Puying
2009-01-01
Based on a survey of the circumstances of the information requirements in social science from more than 3,800 library users in 48 libraries of the four major library systems in Zhejiang Province,this paper analyzes the present main characteristics of the users’requirements to the social science document information and puts forward some proposals for adjusting the document information service strategies for the library and information institutions.
Objective Bayesian Analysis of Skew- t Distributions
BRANCO, MARCIA D'ELIA
2012-02-27
We study the Jeffreys prior and its properties for the shape parameter of univariate skew-t distributions with linear and nonlinear Student\\'s t skewing functions. In both cases, we show that the resulting priors for the shape parameter are symmetric around zero and proper. Moreover, we propose a Student\\'s t approximation of the Jeffreys prior that makes an objective Bayesian analysis easy to perform. We carry out a Monte Carlo simulation study that demonstrates an overall better behaviour of the maximum a posteriori estimator compared with the maximum likelihood estimator. We also compare the frequentist coverage of the credible intervals based on the Jeffreys prior and its approximation and show that they are similar. We further discuss location-scale models under scale mixtures of skew-normal distributions and show some conditions for the existence of the posterior distribution and its moments. Finally, we present three numerical examples to illustrate the implications of our results on inference for skew-t distributions. © 2012 Board of the Foundation of the Scandinavian Journal of Statistics.
Cohomology of skew-holomorphic lie algebroids
Bruzzo, U.; Rubtsov, V. N.
2010-12-01
We introduce the notion of a skew-holomorphic Lie algebroid on a complex manifold and explore some cohomology theories that can be associated with it. We present examples and applications of this notion in terms of different types of holomorphic Poisson structures.
Minimal Residual Methods for Complex Symmetric, Skew Symmetric, and Skew Hermitian Systems
Sou-Cheng; Choi
2013-01-01
While there is no lack of efficient Krylov subspace solvers for Hermitian systems, there are few for complex symmetric, skew symmetric, or skew Hermitian systems, which are increasingly important in modern applications including quantum dynamics, electromagnetics, and power systems. For a large consistent complex symmetric system, one may apply a non-Hermitian Krylov subspace method disregarding the symmetry of $A$, or a Hermitian Krylov solver on the equivalent normal equation or an augmente...
Forecasting with Option-Implied Information
Christoffersen, Peter; Jacobs, Kris; Chang, Bo Young
2013-01-01
This chapter surveys the methods available for extracting information from option prices that can be used in forecasting. We consider option-implied volatilities, skewness, kurtosis, and densities. More generally, we discuss how any forecasting object that is a twice differentiable function of the......-implied information in cross-sectional forecasting of equity returns. We discuss how option-implied information can be adjusted for risk premia to remove biases in forecasting regressions....
Maximal Subgroups of Skew Linear Groups
M. Mahdavi-Hezavehi
2002-01-01
Let D be an infinite division algebra of finite dimension over its centre Z(D) = F, and n a positive integer. The structure of maximal subgroups of skew linear groups are investigated. In particular, assume N is a normal subgroup of GLn(D) and M is a maximal subgroup of N containing Z(N). It is shown that if M/Z(N) is finite, then N is central.
Study on the Distribution of Networked Devices’ Clock Skew
Jiao Chengbo
2011-08-01
Full Text Available Clock skews of devices on the Internet are viewed as one way delay noise, but their distribution is unknown. We explore the distribution of clock skews to see the conflict probability. In this paper, we introduce an accurate clock skew estimation algorithm to filter inaccurate clock skew estimation by comparing the results between linear programming method and least square fitting. Delay jitter and other noises affect the estimation result. When the difference of two methods is large, the estimation result is unstable and inaccurate, so the estimation result should be dropped. Based on this algorithm, we use traces of real Internet measurements to collect 1825 accurate clock skews of different devices to establish a fingerprint database. Furthermore, we show the distribution of clock skews and comparing conflict probability with different number of devices. The distribution shows that clock skews are diverse, and most of clock skews are in the region of [-100, 100] PPM. The results indicate that when the number of devices is small (<5, clock skews won’t be conflict with each other, so clock skews are good tools to detect faked devices or NAT; When the number of devices increases, the conflict probability increases linearly, so clock skews of different devices can not distinguish each devices effectively.
Dynamic Modeling from Flight Data with Unknown Time Skews
Morelli, Eugene A.
2016-01-01
A method for estimating dynamic model parameters from flight data with unknown time skews is described and demonstrated. The method combines data reconstruction, nonlinear optimization, and equation-error parameter estimation in the frequency domain to accurately estimate both dynamic model parameters and the relative time skews in the data. Data from a nonlinear F-16 aircraft simulation with realistic noise, instrumentation errors, and arbitrary time skews were used to demonstrate the approach. The approach was further evaluated using flight data from a subscale jet transport aircraft, where the measured data were known to have relative time skews. Comparison of modeling results obtained from time-skewed and time-synchronized data showed that the method accurately estimates both dynamic model parameters and relative time skew parameters from flight data with unknown time skews.
Strategy of image-information-guided dose rate adjustment in digital X-ray television
The experiments were so designed and carried out that it was even possible for extremely overexposed or underexposed displays to be ascertained within the framework of this study. They were based on observations in phantoms suitable to simulate situations encountered in actual practice. These permitted variations in patient volume (using different water volumes) just as well as the creation of any desired organ constellation (by insertion of bone material, etc.). It is one requirement of this experimental procedure that the X-ray unit used can be operated without automatic dose rate adjustment. A computer equipped with Frame-Grabber card may serve as an image memory. (orig.)
Some properties of skew Hurwitz series
A. M. Hassanein
2014-05-01
Full Text Available In this paper we show that, if R is a ring and σ an endomorphism of R, then the skew Hurwitz series ring T = (HR, σ is an n-clean ring if and only if R is an n-clean ring. Moreover, if R is an integral domain and a torsion-free Z-module, then T = (HR, σ is a Prufer domain if and only if R is a field. Also, we investigate when the ring T = (HR, σ is g(x-clean, (n, g(x-clean and a Neat ring.
Bayesian modeling growth curves for quail assuming skewness in errors
Robson Marcelo Rossi
2014-06-01
Full Text Available Bayesian modeling growth curves for quail assuming skewness in errors - To assume normal distributions in the data analysis is common in different areas of the knowledge. However we can make use of the other distributions that are capable to model the skewness parameter in the situations that is needed to model data with tails heavier than the normal. This article intend to present alternatives to the assumption of the normality in the errors, adding asymmetric distributions. A Bayesian approach is proposed to fit nonlinear models when the errors are not normal, thus, the distributions t, skew-normal and skew-t are adopted. The methodology is intended to apply to different growth curves to the quail body weights. It was found that the Gompertz model assuming skew-normal errors and skew-t errors, respectively for male and female, were the best fitted to the data.
Modelling Scalar Skewness in Cloudy Boundary Layers
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
Skewed norms under peer pressure: Formation and collapse
Michaeli, Moti; Spiro, Daniel
2014-01-01
This paper shows that peer pressure may lead to dynamic convergence to a norm that is skewed with respect to preferences in society, yet is endogenously upheld by the population. Moreover, a skewed norm will often be more sustainable than a representative norm. This may explain the skewness of various social and religious norms. By furthermore interpreting a norm as a political regime, we show that biased regimes can be sustained even without the existence of a powerful group with coherent in...
ON SKEW-NORMAL MODEL FOR ECONOMICALLY ACTIVE POPULATION
OLOSUNDE AKINLOLU A
2011-04-01
Full Text Available The literature related to skew-symmetric distribution have grown rapidly in recent years but at the moment no publication on its applications concerning the description of economically active data with this type of probability models. In this paper, we provided an extension to this skew-normal distribution, which is also part of the family of skewed class of normal but with additional shape parameters δ. Some properties of this distribution are presented and finally, we considered fitting it to economically active population data. The model exhibited a better behaviour when compared to normal and skew normal distributions.
Laird, Robert D.; Marrero, Matthew D.; Melching, Jessica A.; Kuhn, Emily S.
2013-01-01
Adolescents use various strategies to manage their parents' access to information. This study tested developmental change in strategy use, longitudinal associations between disclosing and concealing strategies, and longitudinal associations linking disclosing and concealing strategies with antisocial behavior and depressive symptoms. Self-report…
On Nilpotent Elements of Skew Polynomial Rings
J. Esmaeili
2012-09-01
Full Text Available We study the structure of the set of nilpotent elements in skew polynomial ring R[x; α], when R is an α-Armendariz ring. We prove that if R is a nil α-Armendariz ring and α t = IR, then the set of nilpotent elements of R is an α-compatible subrng of R. Also, it is shown that if R is an α-Armendariz ring and α t = IR, then R is nil α-Armendariz. We give some examples of non α-Armendariz rings which are nil α-Armendariz. Moreover, we show that if α t = IR for some positive integer t and R is a nil α-Armendariz ring and nil(R[x][y; α] = nil(R[x][y], then R[x] is nil α-Armendariz. Some results of [3] follow as consequences of our results
Skewness as a probe of baryon acoustic oscillations
Juszkiewicz, Roman; Hellwing, Wojciech A.; van de Weygaert, Rien
2013-01-01
In this study, we show that the skewness S-3 of the cosmic density field contains a significant and potentially detectable and clean imprint of baryonic acoustic oscillations (BAOs). Although the BAO signal in the skewness has a lower amplitude than second-order measures like the two-point correlati
Learning a Novel Pattern through Balanced and Skewed Input
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…
Random skew plane partitions with a piecewise periodic back wall
Boutillier, Cedric; Mkrtchyan, Sevak; Reshetikhin, Nicolai;
Random skew plane partitions of large size distributed according to an appropriately scaled Schur process develop limit shapes. In the present work we consider the limit of large random skew plane partitions where the inner boundary approaches a piecewise linear curve with non-lattice slopes. Much...
Characteristic functions of scale mixtures of multivariate skew-normal distributions
Kim, Hyoung-Moon
2011-08-01
We obtain the characteristic function of scale mixtures of skew-normal distributions both in the univariate and multivariate cases. The derivation uses the simple stochastic relationship between skew-normal distributions and scale mixtures of skew-normal distributions. In particular, we describe the characteristic function of skew-normal, skew-t, and other related distributions. © 2011 Elsevier Inc.
Delivering Left-Skewed Portfolio Payoff Distributions in the Presence of Transaction Costs
Jacek B Krawczyk
2015-08-01
Full Text Available For pension-savers, a low payoff is a financial disaster. Such investors will most likely prefer left-skewed payoff distributions over right-skewed payoff distributions. We explore how such distributions can be delivered. Cautious-relaxed utility measures are cautious in ensuring that payoffs don’t fall much below a reference value, but relaxed about exceeding it. We find that the payoff distribution delivered by a cautious-relaxed utility measure has appealing features which payoff distributions delivered by traditional utility functions don’t. In particular, cautious-relaxed distributions can have the mass concentrated on the left, hence be left-skewed. However, cautious-relaxed strategies prescribe frequent portfolio adjustments which may be expensive if transaction costs are charged. In contrast, more traditional strategies can be time-invariant. Thus we investigate the impact of transaction costs on the appeal of cautious-relaxed strategies. We find that relatively high transaction fees are required for the cautious-relaxed strategy to lose its appeal. This paper contributes to the literature which compares utility measures by the payoff distributions they produce and finds that a cautious-relaxed utility measure will deliver payoffs that many investors will prefer.
ADJUSTMENT FACTORS AND ADJUSTMENT STRUCTURE
Tao Benzao
2003-01-01
In this paper, adjustment factors J and R put forward by professor Zhou Jiangwen are introduced and the nature of the adjustment factors and their role in evaluating adjustment structure is discussed and proved.
Seismic response of skewed RC box-girder bridges
Ahmed Abdel-Mohti; Gokhan Pekcan
2008-01-01
It is critical to ensure the functionality of highway bridges after earthquakes to provide access to important facilities.Since the 1971 San Fernando earthquake,there has been a better understanding of the seismic performance of bridges.Nonetheless,there are no detailed guidelines addressing the performance of skewed highway bridges.Several parameters affect the response of skewed highway bridges under both service and seismic loads which makes their behavior complex.Therefore,there is a need for more research to study the effect of skew angle and other related factors on the performance of highway bridges.This paper examines the seismic performance of a three-span continuous concrete box girder bridge with skew angles from 0 to 60 degrees,analytically.Finite element (FE) and simplified beam-stick (BS) models of the bridge were developed using SAP2000.Different types of analysis were considered on both models such as:nonlinear static pushover,and linear and nonlinear time history analyses.A comparison was conducted between FE and BS,different skew angles,abutment support conditions,and time history and pushover analysis.It is shown that the BS model has the capability to capture the coupling due to skew and the significant modes for moderate skew angles.Boundary conditions and pushover load profile are determined to have a major effect on pushover analysis.Pushover analysis may be used to predict the maximum deformation and hinge formation adequately.
Decomposition of skew-morphisms of cyclic groups
Kovács, István; Nedela, Roman
2013-01-01
A skew-morphism of a group ▫$H$▫ is a permutation ▫$sigma$▫ of its elements fixing the identity such that for every ▫$x, y in H$▫ there exists an integer ▫$k$▫ such that ▫$sigma (xy) = sigma (x)sigma k(y)$▫. It follows that group automorphisms are particular skew-morphisms. Skew-morphisms appear naturally in investigations of maps on surfaces with high degree of symmetry, namely, they are closely related to regular Cayley maps and to regular embeddings of the complete bipartite graphs. The ai...
Boxed skew plane partition and integrable phase model
We study the relation between the boxed skew plane partition and the integrable phase model. We introduce a generalization of a scalar product of the phase model and calculate it in two ways: the first one in terms of the skew Schur functions, and the other one by use of the commutation relations of operators. In both cases, a generalized scalar product is expressed as a determinant. We show that a special choice of the spectral parameters of a generalized scalar product gives the generating function of the boxed skew plane partition
Analysis of gamma-ray burst duration distribution using mixtures of skewed distributions
Tarnopolski, M.
2016-05-01
Two classes of gamma-ray bursts (GRBs) have been confidently identified thus far and are prescribed to different physical scenarios - neutron star-neutron star or neutron star-black hole 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 catalogues, such as Burst Alert and Transient Source Explorer (BATSE) and Swift, based on statistical tests regarding a mixture of two or three lognormal 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.
Systems of Differential Equations with Skew-Symmetric, Orthogonal Matrices
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.
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.
URANS COMPUTATION OF CAVITATING FLOWS AROUND SKEWED PROPELLERS
LIU Yan; ZHAO Peng-fei; WANG Qiang; CHEN Zhao-hui
2012-01-01
Cavitating flows around skewed propellers are investigated numerically by means of the unsteady Reynolds Averaged Navier-Stokes (RANS) Equation method.The standard k-ε turbulence and the modified Z-G-B cavitation models are employed.A measured nominal wake is used for the inlet velocity boundary condition.Predicted cavitating evolution processes and tip cavity patterns are compared with experimental observations.In addition,the influence of the skew angles on the cavitation and unsteadiness performances of propellers operating in a non-uniform wake is also studied Results show that the modified Z-G-B cavitation model performs better to simulate the cavitating flow cases studied in this paper.Comparisons demonstrate that the skewed propeller with a skew angle of 20° is the best choice for a given stern wake with a assigned thrust and the minimum force fluctuations.
Skein Modules from Skew Howe Duality and Affine Extensions
Queffelec, Hoel
2013-01-01
We show that we can release the rigidity of the skew Howe duality process for ${\\mathfrak sl}_n$ knot invariants by rescaling the quantum Weyl group action, and recover skein modules for web-tangles. This skew Howe duality phenomenon can be extended to the affine ${\\mathfrak sl}_m$ case, corresponding to looking at tangles embedded in a solid torus. We investigate the relations between the invariants constructed by evaluation representations (and affinization of them) and usual skein modules,...
Staircase skew Schur functions are Schur P-positive
Ardila, Federico
2011-01-01
We prove Stanley's conjecture that, if delta_n is the staircase shape, then the skew Schur functions s_{delta_n / mu} are non-negative sums of Schur P-functions. We prove that the coefficients in this sum count certain fillings of shifted shapes. In particular, for the skew Schur function s_{delta_n / delta_{n-2}}, we discuss connections with Eulerian numbers and alternating permutations.
Automated Synthesis of Skew-Based Clock Distribution Networks
José Luis Neves; Eby G. Friedman
1998-01-01
In this paper a top-down methodology is presented for synthesizing clock distribution networks based on application-dependent localized clock skew. The methodology is divided into four phases: 1) determination of an optimal clock skew schedule for improving circuit performance and reliability; 2) design of the topology of the clock tree based on the circuit hierarchy and minimum clock path delays; 3) design of circuit structures to implement the delay values associated with the branches of th...
Kumaraswamy Normal and Azzalini's skew Normal modeling asymmetry
Michelle A Correa; Denismar Alves Nogueira; Eric Batista Ferreira
2012-01-01
This paper presents the comparison of two probability distributions with specific parameters for modelling asymmetry. Kum-normal and Azzalini's skew normal distributions were chosen because they turn, in special case, into the normal distribution. The quality of the fit, flexibility and amount of asymmetry parameters were factors used for comparison. Researches state that the Azzalini's skew normal distribution has limitations regarding the flexibility of the tail, presenting certain resistan...
Skew polynomial rings over abelian and idempotent reflexive rings
Louzari, Mohamed
2015-01-01
Let $R$ be a ring and $\\sigma$ an endomorphism of $R$. In this note, we study skew polynomial rings and skew power series rings over idempotent reflexive rings and abelian rings. Also, we introduce the concept of right (resp., left) $\\sigma$-idempotent reflexive rings which generalizes right (resp., left) idempotent reflexive rings and $\\sigma$-abelian rings. Certain results are obtained as corollaries from our results.
M. Gaspar, Raquel; Murgoci, Agatha
2010-01-01
A convexity adjustment (or convexity correction) in fixed income markets arises when one uses prices of standard (plain vanilla) products plus an adjustment to price nonstandard products. We explain the basic and appealing idea behind the use of convexity adjustments and focus on the situations o...
Statistics on cannabis users skew perceptions of cannabis use
Rachel Melissa Burns
2013-11-01
Full Text Available 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 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 Hispanic. Further, data from a survey conducted in several 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.
Skewness and Kurtosis as Indicators of Non-Gaussianity in Sky Maps
Ben-David, Assaf; Jackson, Andrew D
2015-01-01
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 local properties of both maps are predominantly Gaussian. This result was expected...
An Inconvenient Sea Truth: Spread, Steepness, and Skewness of Surface Slopes
Munk, Walter
2009-01-01
Bréon and Henriot (BH) have collected eight million globally distributed satellite images of sunglitter, which yield a few simple, robust rules about the statistics of surface slopes: 1) constant angular spread, 2) linear steepness, and 3) sigmoid (near stepwise) skewness (all with respect to wind speed). Yet the information is sparse because it says nothing about time and space scales. The BH rules are an inconvenient sea truth, too fundamental to be ignored, too incomplete to be understood. With regard to BH rule 1 (BH:1), I suggest that the constant spread is associated with a wake-like geometry of the short gravities. Steepness linearity (BH:2) remains an enigma. Skewness (BH:3) appears to be correlated with a rather sudden onset of breaking for winds above 4 m s-1. I do not think that skewness comes from parasitic capillaries. These are tentative conclusions; I look forward to intensive sea-going experiments over the next few years demolishing the proposed interpretations.
Effect of Phase Response Curve Skew on Synchronization with and without Conduction Delays
Carmen eCanavier
2013-12-01
Full Text Available A central problem in cortical processing including sensory binding and attentional gating is how neurons can synchronize their responses with zero or near-zero time lag. For a spontaneously firing neuron, an input from another neuron can delay or advance the next spike by different amounts depending upon the timing of the input relative to the previous spike. This information constitutes the phase response curve (PRC. We present a simple graphical method for determining the effect of PRC shape on synchronization tendencies and illustrate it using type 1 PRCs, which consist entirely of advances (delays in response to excitation (inhibition. We obtained the following generic solutions for type 1 PRCs, which include the pulse coupled leaky integrate and fire model. For pairs with mutual excitation, exact synchrony can be stable for strong coupling because of the stabilizing effect of the causal limit region of the PRC in which an input triggers a spike immediately upon arrival. However, synchrony is unstable for short delays, because delayed inputs arrive during a refractory period and cannot trigger an immediate spike. Right skew destabilizes antiphase and enables modes with time lags that grow as the conduction delay is increased. Therefore, right skew favors near-synchrony at short conduction delays and a gradual transition between synchrony and antiphase for pairs coupled by mutual excitation. For pairs with mutual inhibition, zero time lag synchrony is stable for conduction delays ranging from zero to a substantial fraction of the period for pairs. However, for right skew there is a preferred antiphase mode at short delays. In contrast to mutual excitation, left skew destabilizes antiphase for mutual inhibition so that synchrony dominates at short delays as well. These pairwise synchronization tendencies constrain the synchronization properties of neurons embedded in larger networks.
Skew quasisymmetric Schur functions and noncommutative Schur functions
Bessenrodt, Christine; van Willigenburg, Stephanie
2010-01-01
Recently a new basis for the Hopf algebra of quasisymmetric functions $QSym$, called quasisymmetric Schur functions, has been introduced by Haglund, Luoto, Mason, van Willigenburg. In this paper we extend the definition of quasisymmetric Schur functions to introduce skew quasisymmetric Schur functions. These functions include both classical skew Schur functions and quasisymmetric Schur functions as examples, and give rise to a new poset $\\mathcal{L}_C$ that is analogous to Young's lattice. We also introduce a new basis for the Hopf algebra of noncommutative symmetric functions $NSym$. This basis of $NSym$ is dual to the basis of quasisymmetric Schur functions and its elements are the pre-image of the Schur functions under the forgetful map $\\chi: NSym \\rightarrow Sym$. We prove that the multiplicative structure constants of the noncommutative Schur functions, equivalently the coefficients of the skew quasisymmetric Schur functions when expanded in the quasisymmetric Schur basis, are nonnegative integers, sati...
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.
Central limit theorem behavior in the skew tent map
In this paper we study and establish central limit theorem behavior in the skew (generalized) tent map transformation T: Y →Y originally considered by Billings and Bollt [Billings L, Bollt EM. Probability density functions of some skew tent maps. Chaos, Solitons and Fractals 2001; 12: 365-376] and Ito et al. [Ito S, Tanaka S, Nakada H. On unimodal linear transformations and chaos. II. Tokyo J Math 1979; 2: 241-59]. When the measure ν is invariant under T, the transfer operator PT:L1(ν)→L1(ν) governing the evolution of densities f under the action of the skew tent map, as well as the unique stationary density, are given explicitly for specific transformation parameters. Then, using this development, we solve the Poisson equation f=PTf+φ for two specific integrable observables φ and explicitly calculate the variance σ(φ)2=∫Yφ2(y)ν(dy)
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.
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.
Uniqueness: skews bit occurrence frequencies in randomly generated fingerprint libraries.
Chen, Nelson G
2016-08-01
Requiring that randomly generated chemical fingerprint libraries have unique fingerprints such that no two fingerprints are identical causes a systematic skew in bit occurrence frequencies, the proportion at which specified bits are set. Observed frequencies (O) at which each bit is set within the resulting libraries systematically differ from frequencies at which bits are set at fingerprint generation (E). Observed frequencies systematically skew toward 0.5, with the effect being more pronounced as library size approaches the compound space, which is the total number of unique possible fingerprints given the number of bit positions each fingerprint contains. The effect is quantified for varying library sizes as a fraction of the overall compound space, and for changes in the specified frequency E. The cause and implications for this systematic skew are subsequently discussed. When generating random libraries of chemical fingerprints, the imposition of a uniqueness requirement should either be avoided or taken into account. PMID:27230477
Skewness of steady-state current fluctuations in nonequilibrium systems
Belousov, Roman; Cohen, E. G. D.; Wong, Chun-Shang; Goree, John A.; Feng, Yan
2016-04-01
A skewness of the probability for instantaneous current fluctuations, in a nonequilibrium steady state, is observed experimentally in a dusty plasma. This skewness is attributed to the spatial asymmetry, which is imminent to the nonequilibrium systems due to the external hydrodynamic gradient. Using the modern framework of the large deviation theory, we extend the Onsager-Machlup ansatz for equilibrium fluctuations to systems with a preferred spatial direction, and provide a modulated Gaussian probability distribution, which is tested by simulations. This probability distribution is also of potential interest for other statistical disciplines. Connections with the principles of statistical mechanics, due to Boltzmann and Gibbs, are discussed as well.
Skew-orthogonal polynomials, differential systems and random matrix theory
We study skew-orthogonal polynomials with respect to the weight function exp[-2V (x)], with V (x) = ΣK=12d (uK/K)xK, u2d > 0, d > 0. A finite subsequence of such skew-orthogonal polynomials arising in the study of Orthogonal and Symplectic ensembles of random matrices, satisfy a system of differential-difference-deformation equation. The vectors formed by such subsequence has the rank equal to the degree of the potential in the quaternion sense. These solutions satisfy certain compatibility condition and hence admit a simultaneous fundamental system of solutions. (author)
Power and Skew Aware Point Diffusion Clock Network
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-orthogonal polynomials, differential systems and random matrix theory
Ghosh, Saugata [Abdus Salam ICTP, Strada Costiera 11, 34100, Trieste (Italy)
2007-01-26
We study skew-orthogonal polynomials with respect to the weight function exp [ - 2V(x)], with V(x) = {sigma}{sup 2d}{sub K=1}(u{sub K}/K)x{sup K}, u{sub 2d} > 0, d > 0. A finite subsequence of such skew-orthogonal polynomials arising in the study of orthogonal and symplectic ensembles of random matrices satisfies a system of differential-difference-deformation equation. The vectors formed by such subsequence have the rank equal to the degree of the potential in the quaternion sense. These solutions satisfy certain compatibility condition and hence admit a simultaneous fundamental system of solutions.
Market skewness risk and the cross section of stock returns
Chang, B.Y.; Christoffersen, Peter; Jacobs, K.
2013-01-01
The cross section of stock returns has substantial exposure to risk captured by higher moments of market returns. We estimate these moments from daily Standard & Poor's 500 index option data. The resulting time series of factors are genuinely conditional and forward-looking. Stocks with high...... exposure to innovations in implied market skewness exhibit low returns on average. The results are robust to various permutations of the empirical setup. The market skewness risk premium is statistically and economically significant and cannot be explained by other common risk factors such as the market...... excess return or the size, book-to-market, momentum, and market volatility factors, or by firm characteristics....
Dagne, Getachew; Huang, Yangxin
2012-01-01
Censored data are characteristics of many bioassays in HIV/AIDS studies where assays may not be sensitive enough to determine gradations in viral load determination among those below a detectable threshold. Not accounting for such left-censoring appropriately can lead to biased parameter estimates in most data analysis. To properly adjust for left-censoring, this paper presents an extension of the Tobit model for fitting nonlinear dynamic mixed-effects models with skew distributions. Such extensions allow one to specify the conditional distributions for viral load response to account for left-censoring, skewness and heaviness in the tails of the distributions of the response variable. A Bayesian modeling approach via Markov Chain Monte Carlo (MCMC) algorithm is used to estimate model parameters. The proposed methods are illustrated using real data from an HIV/AIDS study. PMID:22992288
Dagne, Getachew; Huang, Yangxin
2016-01-01
Censored data are characteristics of many bioassays in HIV/AIDS studies where assays may not be sensitive enough to determine gradations in viral load determination among those below a detectable threshold. Not accounting for such left-censoring appropriately can lead to biased parameter estimates in most data analysis. To properly adjust for left-censoring, this paper presents an extension of the Tobit model for fitting nonlinear dynamic mixed-effects models with skew distributions. Such extensions allow one to specify the conditional distributions for viral load response to account for left-censoring, skewness and heaviness in the tails of the distributions of the response variable. A Bayesian modeling approach via Markov Chain Monte Carlo (MCMC) algorithm is used to estimate model parameters. The proposed methods are illustrated using real data from an HIV/AIDS study. PMID:22992288
A sampling switch with an embedded digital-to-skew converter (DSC) is presented. The proposed switch eliminates time-interleaved ADCs' skews by adjusting the boosted voltage. A similar bridged capacitors' charge sharing structure is used to minimize the area. The circuit is fabricated in a 0.18 μm CMOS process and achieves sub-1 ps resolution and 200 ps timing range at a rate of 100 MS/s. The power consumption is 430 μW at maximum. The measurement result also includes a 2-channel 14-bit 100 MS/s time-interleaved ADCs (TI-ADCs) with the proposed DSC switch's demonstration. This scheme is widely applicable for the clock skew and aperture error calibration demanded in TI-ADCs and SHA-less ADCs. (semiconductor integrated circuits)
Zhu Xiaoshi; Chen Chixiao; Xu Jialiang; Ye Fan; Ren Junyan
2013-01-01
A sampling switch with an embedded digital-to-skew converter (DSC) is presented.The proposed switch eliminates time-interleaved ADCs' skews by adjusting the boosted voltage.A similar bridged capacitors' charge sharing structure is used to minimize the area.The circuit is fabricated in a 0.18μm CMOS process and achieves sub-1 ps resolution and 200 ps timing range at a rate of 100 MS/s.The power consumption is 430 μW at maximum.The measurement result also includes a 2-channel 14-bit 100 MS/s time-interleaved ADCs (TI-ADCs) with the proposed DSC switch's demonstration.This scheme is widely applicable for the clock skew and aperture error calibration demanded in TI-ADCs and SHA-less ADCs.
Modules over Double Crossproducts of Skew-Hopf Pairs
潘庆年; 郝志峰
2002-01-01
The purpose is to study modules of double crossproducts D( X, A ) of Skew-Hopf pairs (X,A). A sufficient and necessary condition for M to be D( X,A )-mod is shown. Relations between D( X, A ) -mod and quantam Yang-Baxter A-mod or X-mod are revealed.
Patterns of paternity skew among polyandrous social insects
Jaffé, Rodolfo; Garcia-Gonzalez, Francisco; den Boer, Susanne;
2012-01-01
species with low paternity frequency. However, species with highly polyandrous queens had low paternity skew, with paternity equalized among potential sires. Equal paternity shares among fathers are expected to maximize fitness benefits derived from genetic diversity among offspring. We discuss the...
Skew category algebras associated with partially defined dynamical systems
Lundström, Patrik; Öinert, Per Johan
2012-01-01
We introduce partially defined dynamical systems defined on a topological space. To each such system we associate a functor s from a category G to Topop and show that it defines what we call a skew category algebra A ⋊σ G. We study the connection between topological freeness of s and, on the one ...
Random skew plane partitions and the Pearcey process
Reshetikhin, Nicolai; Okounkov, Andrei
2007-01-01
We study random skew 3D partitions weighted by q vol and, specifically, the q → 1 asymptotics of local correlations near various points of the limit shape. We obtain sine-kernel asymptotics for correlations in the bulk of the disordered region, Airy kernel asymptotics near a general point of the...
Flow dynamics inside an Urban Intersection: Skewness and Kurtosis characteristics
Kellnerová, Radka; Jaňour, Zbyněk
Liberec: TU Liberec, 2008 - (Dančová, P.; Vít, T.), s. 72-78 ISBN 978-80-7372-417-7. [Experimental Fluid Mechanics 2008. Liberec (CZ), 26.11.2008-28.11.2008] Institutional research plan: CEZ:AV0Z20760514 Keywords : street canyon * urban intersection * skewness * quadrant analysis Subject RIV: DG - Athmosphere Sciences, Meteorology
Asymmetric skew Bessel processes and their applications to finance
M. Decamps; M.J. Goovaerts; W. Schoutens
2006-01-01
In this paper, we extend the Harrison and Shepp's construction of the skew Brownian motion (1981) and we obtain a diffusion similar to the two-dimensional Bessel process with speed and scale densities discontinuous at one point. Natural generalizations to multi-dimensional and fractional order Besse
Parameterizing unconditional skewness in models for financial time series
He, Changli; Silvennoinen, Annastiina; Teräsvirta, Timo
In this paper we consider the third-moment structure of a class of time series models. It is often argued that the marginal distribution of financial time series such as returns is skewed. Therefore it is of importance to know what properties a model should possess if it is to accommodate...
American Psychiatric Association. Diagnostic and statistical manual of mental disorders . 5th ed. Arlington, VA: American Psychiatric Publishing. 2013. Powell AD. Grief, bereavement, and adjustment disorders. In: Stern TA, Fava ...
American Psychiatric Association. Diagnostic and statistical manual of mental disorders. 5th ed. Arlington, Va: American Psychiatric Publishing. 2013. Powell AD. Grief, bereavement, and adjustment disorders. In: Stern TA, Rosenbaum ...
Sugita, M; Fukui, T; Tatemichi, M; Minowa, H; Ikegami, Y; Miyawaki, Y; Ishizuka, Y; Izuno, T
1995-03-01
In 1990, 365 (males: 197, females: 168) freshmen employees at the headquarters of a large corporation were examined just after being hired in order to observe their health status. We collected (1) data of physical examinations and questionnaires for symptoms as an ordinary health checkup, (2) information on work adjustment, life patterns, and personal characteristics through interviews conducted by ten public health nurses, and (3) personal records, e.g. birth year. Statistical analyses revealed some notable findings as follows: (1) subjects with higher blood pressure had higher scores of extrovert personality among males, (2) female subjects with greater body mass index had higher scores in such manifestations of personal characteristics such as aggression and discontent with superiors, (3) higher scores of personal characteristics were noted among female subjects working in technical sections, (4) positive correlation between the scores of work adjustment and personal characteristics, (5) higher scores of undesirable life patterns among males and of work maladjustment among elder females, (6) unbalanced meal quality of subjects from rural areas, (7) higher mental tension among younger males from rural areas, and (8) higher scores of dependency and lower morale among younger female subjects. Information on health problems was collected over the 1.5 yrs that followed. More problems were detected among females than among males and among younger females than among elder females. Longitudinal analysis was carried out from just after entry into the company for approximately 1.5 yrs. Health problems in females could be predicted by the data on personal characteristics and work adjustment just after entry. Risk of health problems in male freshmen employees with hobbies and unhealthy drinking habits over the 1.5 yrs that followed was higher than in others. It was concluded that a health interview for freshmen employees by public health nurses is valuable for health care
Verkuil, Yvonne I; Juillet, Cedric; Lank, David B; Widemo, Fredrik; Piersma, Theunis
2014-09-01
Sex differences in skews of vertebrate lifetime reproductive success are difficult to measure directly. Evolutionary histories of differential skew should be detectable in the genome. For example, male-biased skew should reduce variation in the biparentally inherited genome relative to the maternally inherited genome. We tested this approach in lek-breeding ruff (Class Aves, Philomachus pugnax) by comparing genetic variation of nuclear microsatellites (θ n ; biparental) versus mitochondrial D-loop sequences (θ m ; maternal), and conversion to comparable nuclear (N e ) and female (N ef ) effective population size using published ranges of mutation rates for each marker (μ). We provide a Bayesian method to calculate N e (θ n = 4N e μ n ) and N ef (θ m = 2N ef μ m ) using 95% credible intervals (CI) of θ n and θ m as informative priors, and accounting for uncertainty in μ. In 96 male ruffs from one population, N e was 97% (79-100%) lower than expected under random mating in an ideal population, where N e :N ef = 2. This substantially lower autosomal variation represents the first genomic support of strong male reproductive skew in a lekking species. PMID:25478153
Experimental and Finite Element Studies on Free Vibration of Skew Plates
Srinivasa C.V.; Suresh Y.J.; Prema Kumar W.P.
2014-01-01
The present paper deals with the experimental studies carried out on free vibration of isotropic and laminated composite skew plates. The natural frequencies were also determined using QUAD8 finite element of MSC/NASTRAN and a comparison was made between the experimental values and the finite element solution. The effects of the skew angle and aspect ratio on the natural frequencies of isotropic skew plates were studied. The effects of the skew angle, aspect ratio, fiber orientation angle and...
The equity premium and the volatility spread: The role of risk-neutral skewness
Feunou, Bruno; Fontaine, Jean-Sébastien; Tedongap, Roméo
2009-01-01
We introduce the Homoscedastic Gamma [HG] model where the distribution of returns is characterized by its mean, variance and an independent skewness parameter under both measures. The model predicts that the spread between historical and risk-neutral volatilities is a function of the risk premium and of skewness. In fact, the equity premium is twice the ratio of the volatility spread to skewness. We measure skewness from option prices and test these predictions. We find that conditioning on s...
Dimension theoretical study on skew product maps with coupled-expanding property
Jinhyon Kim
2014-03-01
Full Text Available We discuss on some families of skew product maps on a square. For a kind of skew product maps with coupled-expanding property, we estimate Hausdorff dimension of its attractor. And we prove that there exists an ergodic measure with full Hausdorff dimension for this kind of skew product maps.
Technological Inefficiency and the Skewness of the Error Component in Stochastic Frontier Analysis
M.A. Carree (Martin)
2002-01-01
textabstractThis paper concentrates on negatively skewed one-sided distributions as an explanation of the occurence of positive (negative) skewness in the case of stochastic production (cost) frontier analysis. It takes as example the binomial distribution that can have negative or positive skew and
Regularized multivariate regression models with skew-t error distributions
Chen, Lianfu
2014-06-01
We consider regularization of the parameters in multivariate linear regression models with the errors having a multivariate skew-t distribution. An iterative penalized likelihood procedure is proposed for constructing sparse estimators of both the regression coefficient and inverse scale matrices simultaneously. The sparsity is introduced through penalizing the negative log-likelihood by adding L1-penalties on the entries of the two matrices. Taking advantage of the hierarchical representation of skew-t distributions, and using the expectation conditional maximization (ECM) algorithm, we reduce the problem to penalized normal likelihood and develop a procedure to minimize the ensuing objective function. Using a simulation study the performance of the method is assessed, and the methodology is illustrated using a real data set with a 24-dimensional response vector. © 2014 Elsevier B.V.
A stochastic daily weather generator for skewed data
Flecher, C.; Naveau, P.; Allard, D.; Brisson, N.
2010-07-01
To simulate multivariate daily time series (minimum and maximum temperatures, global radiation, wind speed, and precipitation intensity), we propose a weather state approach with a multivariate closed skew-normal generator, WACS-Gen, that is able to accurately reproduce the statistical properties of these five variables. Our weather generator construction takes advantage of two elements. We first extend the classical wet and dry days dichotomy used in most past weather generators to the definition of multiple weather states using clustering techniques. The transitions among weather states are modeled by a first-order Markov chain. Second, the vector of our five daily variables of interest is sampled, conditionally on these weather states, from a closed skew-normal distribution. This class of distribution allows us to handle nonsymmetric behaviors. Our method is applied to the 20 years of daily weather measurements from Colmar, France. This example illustrates the advantages of our approach, especially improving the simulation of radiation and wind distributions.
Skew Divergence-Based Fuzzy Segmentation of Rock Samples
Digital image segmentation is a process in which one assigns distinct labels to different objects in a digital image. The MOFS (Multi Object Fuzzy Segmentation) algorithm has been successfully applied to the segmentation of images from several modalities. However, the traditional MOFS algorithm fails when applied to images whose composing objects are characterized by textures whose patterns cannot be successfully described by simple statistics computed over a very restricted area. Here, we present an extension of the MOFS algorithm that achieves the segmentation of textures by employing adaptive affinity functions that use the Skew Divergence as a measure of distance between two distributions. These affinity functions are called adaptive because their associated area (neighborhood) changes according to the characteristics of the texture being processed. We performed experiments on mosaic images composed by combining rock sample images which show the effectiveness of the adaptive skew divergence based fuzzy affinity functions
Skew Divergence-Based Fuzzy Segmentation of Rock Samples
Carvalho, Bruno M.; Garduño, Edgar; Santos, Iraçú O.
2014-03-01
Digital image segmentation is a process in which one assigns distinct labels to different objects in a digital image. The MOFS (Multi Object Fuzzy Segmentation) algorithm has been successfully applied to the segmentation of images from several modalities. However, the traditional MOFS algorithm fails when applied to images whose composing objects are characterized by textures whose patterns cannot be successfully described by simple statistics computed over a very restricted area. Here, we present an extension of the MOFS algorithm that achieves the segmentation of textures by employing adaptive affinity functions that use the Skew Divergence as a measure of distance between two distributions. These affinity functions are called adaptive because their associated area (neighborhood) changes according to the characteristics of the texture being processed. We performed experiments on mosaic images composed by combining rock sample images which show the effectiveness of the adaptive skew divergence based fuzzy affinity functions.
Incorporating Skew into RMS Surface Roughness Probability Distribution
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.
Double-dimer pairings and skew Young diagrams
Kenyon, Richard W.; Wilson, David B.
2010-01-01
We study the number of tilings of skew Young diagrams by ribbon tiles shaped like Dyck paths, in which the tiles are "vertically decreasing". We use these quantities to compute pairing probabilities in the double-dimer model: Given a planar bipartite graph $G$ with special vertices, called nodes, on the outer face, the double-dimer model is formed by the superposition of a uniformly random dimer configuration (perfect matching) of $G$ together with a random dimer configuration of the graph fo...
Pricing Kernels with Stochastic Skewness and Volatility Risk
Fousseni Chabi-Yo
2012-01-01
I derive pricing kernels in which the market volatility is endogenously determined. Using the Taylor expansion series of the representative investor's marginal utility, I show that the price of market volatility risk is restricted by the investor's risk aversion and skewness preference. The risk aversion is estimated to be between two and five and is significant. The price of the market volatility is negative. Consistent with economic theory, I find that the pricing kernel decreases in the ma...
Too many skew normal distributions? The practitioner’s perspective
Charemza, W.; Diaz Vela, C.; Makarova, S.
2013-01-01
The paper tackles the issue of possible misspecification in fitting skew normal distributions to empirical data. It is shown, through numerical experiments, that it is easy to choose a distribution which is different from this which actually generated the sample, if the minimum distance criterion is used. It is suggested that, in case of similar values of distance measures obtained for different distributions, the choice should be made on the grounds of parameters’ interpretation rather than ...
Exponential speed of mixing for skew-products with singularities
Let f : [0, 1]/{1/2} × [0, 1] → [0, 1] × [0, 1] be the C∞ endomorphism given. 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. (paper)
"Skew" scattering of cold unpolarized neutrons in ferromagnetic crystal
Udalov, O. G.
2012-01-01
The problem of neutron scattering by the single magnetic atom is theoretically considered in the second order perturbation theory. It is demonstrated that elastic scattering of unpolarized neutron by magnetic atom is skewed, i.e. contains the term with the symmetry of mixed product of the atom magnetic moment and wave vectors of incident and scattered neutrons. The problem of dynamical diffraction of unpolarized neutrons by the perfect ferromagnetic crystal is investigated. The case is consid...
The VAWT in skew: stereo-PIV and vortex modeling
Simao Ferreira, C.J.; Dixon, K.R.; Hofemann, C.; Kuik, G. A. M.; Van Bussel, G.J.W.
2009-01-01
One of the results of the development of wind energy conversion solutions for the built environment is the reappearance of Vertical Axis Wind Turbines (VAWTs). The application of wind turbines in urban environments presents design challenges driven by the complex wind fields experienced in the urban boundary layer. Urban Wind Turbines operate near, on and in the wake of bluff bodies larger than the rotor scale. These flow conditions might result in skewed flow operation. The objective of the ...
Cross-sectional analysis of risk-neutral skewness
Taylor, Stephen J.; Yadav, Pradeep K.; Zhang, Yuanyuan
2009-01-01
We investigate the association of various firm-specific and market-wide factors with the riskneutral skewness (RNS) implied by the prices of individual stock options. Our analysis covers 149 U.S. firms over a four-year period. Our choice of firms is based on adequate liquidity and trading interest across different strike prices in the options market, ensuring economically meaningful RNS estimates. We also incorporate significant methodological enhancements. Consistent with earlier results, we...
Sattin, F; Cavazzana, R; Serianni, G; Scarin, P; Vianello, N
2009-01-01
In this work we investigate the origin of the parabolic relation between skewness and kurtosis often encountered in the analysis of experimental time-series. We argue that the numerical values of the coefficients of the curve may provide informations about the specific physics of the system studied, whereas the analytical curve per se is a fairly general consequence of a few constraints expected to hold for most systems.
HR Department
2008-01-01
In accordance with decisions taken by the Finance Committee and Council in December 2007, salaries are adjusted with effect from 1 January 2008. Scale of basic salaries and scale of stipends paid to fellows (Annex R A 5 and R A 6 respectively): increased by 0.71% with effect from 1 January 2008. As a result of the stability of the Geneva consumer price index, the following elements do not increase: a)\tFamily Allowance, Child Allowance and Infant Allowance (Annex R A 3); b)\tReimbursement of education fees: maximum amounts of reimbursement (Annex R A 4.01) for the academic year 2007/2008. Related adjustments will be applied, wherever applicable, to Paid Associates and Students. As in the past, the actual percentage increase of each salary position may vary, due to the application of a constant step value and rounding effects. Human Resources Department Tel. 73566
HR Department
2008-01-01
In accordance with decisions taken by the Finance Committee and Council in December 2007, salaries are adjusted with effect from 1 January 2008. Scale of basic salaries and scale of stipends paid to fellows (Annex R A 5 and R A 6 respectively): increased by 0.71% with effect from 1 January 2008. As a result of the stability of the Geneva consumer price index, following elements do not increase: a) Family Allowance, Child Allowance and Infant Allowance (Annex R A 3). b) Reimbursement of education fees: maximum amounts of reimbursement (Annex R A 4.01) for the academic year 2007/2008. Related adjustments will be implemented, wherever applicable, to Paid Associates and Students. As in the past, the actual percentage increase of each salary position may vary, due to the application of a constant step value and the rounding effects. Human Resources Department Tel. 73566
A method for generating skewed random numbers using two overlapping uniform distributions
The objective of this work was to implement and evaluate a method for generating skewed random numbers using a combination of uniform random numbers. The method provides a simple and accurate way of generating skewed random numbers from the specified first three moments without an a priori specification of the probability density function. We describe the procedure for generating skewed random numbers from unifon-n random numbers, and show that it accurately produces random numbers with the desired first three moments over a range of skewness values. We also show that in the limit of zero skewness, the distribution of random numbers is an accurate approximation to the Gaussian probability density function. Future work win use this method to provide skewed random numbers for a Langevin equation model for diffusion in skewed turbulence
In a rotating fan beam tomographic scanner there is included an adjustable collimator and shutter assembly. The assembly includes a fan angle collimation cylinder having a plurality of different length slots through which the beam may pass for adjusting the fan angle of the beam. It also includes a beam thickness cylinder having a plurality of slots of different widths for adjusting the thickness of the beam. Further, some of the slots have filter materials mounted therein so that the operator may select from a plurality of filters. Also disclosed is a servo motor system which allows the operator to select the desired fan angle, beam thickness and filter from a remote location. An additional feature is a failsafe shutter assembly which includes a spring biased shutter cylinder mounted in the collimation cylinders. The servo motor control circuit checks several system conditions before the shutter is rendered openable. Further, the circuit cuts off the radiation if the shutter fails to open or close properly. A still further feature is a reference radiation intensity monitor which includes a tuning-fork shaped light conducting element having a scintillation crystal mounted on each tine. The monitor is placed adjacent the collimator between it and the source with the pair of crystals to either side of the fan beam
Malecki, Christine Kerres; Demaray, Michelle Kilpatrick
2003-01-01
Examined specific types of support students perceive from their sources of support; and whether some support sources were more related to students' social, behavioral, and academic outcomes. Results found girls perceive more support of most types from classmates and friends; emotional and informational support were most highly reported support…
A Dixmier-Moeglin equivalence for skew Laurent polynomial rings
Parks, James William Alexander
2009-01-01
The work of Dixmier in 1977 and Moeglin in 1980 show us that for a prime ideal $P$ in the universal enveloping algebra of a complex finite-dimensional Lie algebra the properties of being primitive, rational and locally closed in the Zariski topology are all equivalent. This equivalence is referred to as the Dixmier-Moeglin equivalence. In this thesis we will study skew Laurent polynomial rings of the form ${mathbb{C}}[x_1,ldots,x_d][z,z^{-1};sigma]$ where $sigma$ is a ${mathbb{C}}$-algebra au...
PARAMETRIC STUDY OF SKEW ANGLE ON BOX GIRDER BRIDGE DECK
Shrikant D. Bobade *, Dr. Valsson Varghese
2016-01-01
Box girder bridge deck, is the most common type of bridges in world and India, it consists of several Slab or girders. The span in the direction of the roadway and connected across their tops and bottoms by a thin continuous structural stab, the longitudinal box girders can be made of steel or concrete. The Simple supported single span concrete bridge deck is presented in present study. Skewed bridges are suitable in highway design when the geometry of straight bridges is not possible. The sk...
75 FR 59684 - Trade Adjustment Assistance for Farmers
2010-09-28
... Foreign Agricultural Service Trade Adjustment Assistance for Farmers AGENCY: Foreign Agricultural Service... analyzed by USDA's Economic Research Service and reviewed by the Trade Adjustment Assistance for Farmers... adjustment assistance in FY 2011. FOR FURTHER INFORMATION CONTACT: Trade Adjustment Assistance for...
Pedersen, Poul Ove
2005-01-01
In spite of its growing importance in the African economies, the informal, small-enterprise sector still plays a dubious and little understood role in development. Due to lack of data it is often treated as if it was unrelated to the rest of the economy. However, a number og large surveys carried out in a number of African countries indicate that structure and development of the small-enterprise sector vary greatly both from country to country and over time, depending in a complex way on the ...
Pattern formation of underwater sand ripples with a skewed drive.
Bundgaard, F; Ellegaard, C; Scheibye-Knudsen, K; Bohr, T; Sams, T
2004-12-01
In this paper we present an experimental study of the dynamics of underwater sand ripples when a regular pattern of ripples is subjected to a skewed oscillatory flow, i.e., one not perpendicular to the direction of the ripple crests. Striking patterns with new, superposed ripples on top of the original ones occur very quickly with a characteristic angle, which is, in general, not perpendicular to the flow. A slower, more complex transition then follows, leading to the final state where the ripples are again perpendicular to the flow. We investigate the variation of the superposed pattern as a function of the direction, amplitude, and frequency of the drive, and as a function of the viscosity (by changing the temperature). We quantify the dynamics of the entire transition process and finally study the grain motion around idealized (solid) skewed ripples. This leads to a characteristic mean path of a single particle. The path has a shape close to a parallelogram, with no apparent connection to the pattern of real, superposed ripples. On the other hand, a thin layer of sand sprinkled on the solid ripples leads to qualitatively similar patterns. PMID:15697484
Holder properties of perturbed skew products and Fubini regained
Ilyashenko, Yulij
2010-01-01
In 2006, A. Gorodetski proved that central fibers of perturbed skew products are Holder continuous with respect to the base point. In the present paper we give an explicit estimate of the Holder exponent mentioned above. Moreover, we extend the Gorodetski theorem from the case when the fiber maps are close to the identity to a much wider class that satisfy the so-called modified dominated splitting condition. In many cases (for example, in the case of skew products over the solenoid or over linear Anosov diffeomorphisms of a torus), the Holder exponent is close to 1. This allows us in a sense to overcome the so-called Fubini nightmare. Namely, we prove that the union of central fibers that are strongly atypical from the point of view of the ergodic theory, has Lebesgue measure zero, despite the lack of absolute continuity of the holonomy map for the central foliation. For that we revisit the Hirsch-Pugh-Shub theory, and estimate the contraction constant of the graph transform map.
Tissue-specific patterns of allelically-skewed DNA methylation
Marzi, Sarah J.; Meaburn, Emma L.; Dempster, Emma L.; Lunnon, Katie; Paya-Cano, Jose L.; Smith, Rebecca G.; Volta, Manuela; Troakes, Claire; Schalkwyk, Leonard C.; Mill, Jonathan
2016-01-01
ABSTRACT While DNA methylation is usually thought to be symmetrical across both alleles, there are some notable exceptions. Genomic imprinting and X chromosome inactivation are two well-studied sources of allele-specific methylation (ASM), but recent research has indicated a more complex pattern in which genotypic variation can be associated with allelically-skewed DNA methylation in cis. Given the known heterogeneity of DNA methylation across tissues and cell types we explored inter- and intra-individual variation in ASM across several regions of the human brain and whole blood from multiple individuals. Consistent with previous studies, we find widespread ASM with > 4% of the ∼220,000 loci interrogated showing evidence of allelically-skewed DNA methylation. We identify ASM flanking known imprinted regions, and show that ASM sites are enriched in DNase I hypersensitivity sites and often located in an extended genomic context of intermediate DNA methylation. We also detect examples of genotype-driven ASM, some of which are tissue-specific. These findings contribute to our understanding of the nature of differential DNA methylation across tissues and have important implications for genetic studies of complex disease. As a resource to the community, ASM patterns across each of the tissues studied are available in a searchable online database: http://epigenetics.essex.ac.uk/ASMBrainBlood. PMID:26786711
Crossover ensembles of random matrices and skew-orthogonal polynomials
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.
Male reproductive skew, paternal relatedness, and female social relationships.
Schülke, Oliver; Ostner, Julia
2008-07-01
Female social relationships among primates are thought to be shaped by socio-ecological factors and phylogenetic constraints. We suggest that patterns of paternal relatedness among females influence measures of social tolerance that have been used to classify species into different social relationship categories. As kin support and kin preference have only been measured for matrilineal kin and related individuals exchange less aggression and have a higher conciliatory tendency, the observed low nepotism levels and high tolerance levels may be an artifact of hidden paternal relatedness among the nonkin category. Using comparative data on macaques, we investigate this hypothesis using male reproductive skew as a proxy for paternal relatedness. Within the limitations of the study we show that populations classified as being less nepotistic, and more tolerant exhibit higher levels of reproductive skew. This first result and the reasoning behind may motivate future students of social relationships to take paternal relatedness into consideration. Potential implications of this finding if repeated with larger samples include that variation in aspects of macaque social relationships may be explained without considering phylogeny or the strength of between-group contest competition for food. PMID:18421769
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 38 % 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
Experimental and finite element studies on free vibration of skew plates
Srinivasa, C. V.; Suresh, Y. J.; Prema Kumar, W. P.
2014-03-01
The present paper deals with the experimental and finite element studies carried out on free vibration of isotropic and laminated composite skew plates. The natural frequencies were determined using CQUAD8 finite element of MSC/NASTRAN and comparison made between the experimental values and the finite element solution. The effects of the skew angle and aspect ratio on the natural frequencies of isotropic skew plates were studied. The effects of skew angle, aspect ratio, fiber orientation angle and laminate stacking sequence (keeping total number of layers in the laminate constant) on the natural frequencies of antisymmetric laminated composite skew plates were also studied. The experimental values of the natural frequencies are in good agreement with the finite element solution. The natural frequencies generally increase with an increase in the skew angle for any given value of aspect ratio.
Experimental and Finite Element Studies on Free Vibration of Skew Plates
Srinivasa C.V.
2014-05-01
Full Text Available The present paper deals with the experimental studies carried out on free vibration of isotropic and laminated composite skew plates. The natural frequencies were also determined using QUAD8 finite element of MSC/NASTRAN and a comparison was made between the experimental values and the finite element solution. The effects of the skew angle and aspect ratio on the natural frequencies of isotropic skew plates were studied. The effects of the skew angle, aspect ratio, fiber orientation angle and laminate sequence (keeping the number of layers constant on the natural frequencies of antisymmetric composite laminates were also studied. The experimental values of natural frequencies are in good agreement with the FE solutions. The natural frequencies are found to increase with an increase in the skew angle. The variation of natural frequencies with the aspect ratio is small and negligible both for isotropic and laminated composite skew plates.
Finite element studies on free vibration of laminated composite cylindrical skew panels
Srinivasa C.V.; Suresh Y.J.; Kumar W.P. Prema
2014-01-01
This paper presents the finite element studies on free vibration of isotropic and laminated composite cylindrical skew panels. The analysis is performed using CQUAD4 and CQUAD8 elements of MSC/NASTRAN. The effects of the panel angle, skew angle, aspect ratio and length-to-thickness-ratio on fundamental frequency of isotropic cylindrical skew panels are studied. The effects of additional parameters such as the fiber orientation angle, numbers of layers and stacking sequence on the fundamental ...
Finite Element Studies on Free Vibration of Laminated Composite Cylindrical Skew Panels
Srinivasa Chikkol Venkateshappa; Suresh Yalaburgi Jayadevappa; Premakumar Wooday Puttiah
2014-01-01
This paper presents the finite element studies made on free vibration of isotropic and laminated composite cylindrical skew panels. A finite element analysis is performed using CQUAD4 and CQUAD8 elements of MSC/NASTRAN software. The effects of the panel angle, skew angle, aspect ratio, and length-to-thickness-ratio on fundamental natural frequency of vibration of isotropic cylindrical skew panels are studied. The effects of additional parameters such as fiber orientation angle, numbers of lay...
Skew cyclic codes over F_q+uF_q+vF_q+uvF_q
Ting Yao
2015-09-01
Full Text Available In this paper, we study skew cyclic codes over the ring $R=F_q+uF_q+vF_q+uvF_q$, where $u^{2}=u,v^{2}=v,uv=vu$, $q=p^{m}$ and $p$ is an odd prime. We investigate the structural properties of skew cyclic codes over $R$ through a decomposition theorem. Furthermore, we give a formula for the number of skew cyclic codes of length $n$ over $R.$
Finding the Right Distribution for Highly Skewed Zero-inflated Clinical Data
Resmi Gupta; Marino, Bradley S; Cnota, James F.; Ittenbach, Richard F.
2013-01-01
Discrete, highly skewed distributions with excess numbers of zeros often result in biased estimates and misleading inferences if the zeros are not properly addressed. A clinical example of children with electrophysiologic disorders in which many of the children are treated without surgery is provided. The purpose of the current study was to identify the optimal modeling strategy for highly skewed, zeroinflated data often observed in the clinical setting by: (a) simulating skewed, zero-inflate...
Multivariate log-skew-elliptical distributions with applications to precipitation data
Marchenko, Yulia V.
2009-07-13
We introduce a family of multivariate log-skew-elliptical distributions, extending the list of multivariate distributions with positive support. We investigate their probabilistic properties such as stochastic representations, marginal and conditional distributions, and existence of moments, as well as inferential properties. We demonstrate, for example, that as for the log-t distribution, the positive moments of the log-skew-t distribution do not exist. Our emphasis is on two special cases, the log-skew-normal and log-skew-t distributions, which we use to analyze US national (univariate) and regional (multivariate) monthly precipitation data. © 2009 John Wiley & Sons, Ltd.
Does Realized Skewness Predict the Cross-Section of Equity Returns?
Amaya, Diego; Christoffersen, Peter; Jacobs, Kris; Vasquez, Aurelio
find a very strong negative relationship between realized skewness and next week’'s stock returns. A trading strategy that buys stocks in the lowest realized skewness decile and sells stocks in the highest realized skewness decile generates an average weekly return of 24 basis points with a t......-statistic of 3.65. Our results on realized skewness are robust across a wide variety of implementations, sample periods, portfolio weightings, and firm characteristics, and are not captured by the Fama-French and Carhart factors. We find some evidence that the relationship between realized kurtosis and next...
Adjustment computations spatial data analysis
Ghilani, Charles D
2011-01-01
the complete guide to adjusting for measurement error-expanded and updated no measurement is ever exact. Adjustment Computations updates a classic, definitive text on surveying with the latest methodologies and tools for analyzing and adjusting errors with a focus on least squares adjustments, the most rigorous methodology available and the one on which accuracy standards for surveys are based. This extensively updated Fifth Edition shares new information on advances in modern software and GNSS-acquired data. Expanded sections offer a greater amount of computable problems and their worked solu
Skewed birth sex ratio and premature mortality in elephants.
Saragusty, Joseph; Hermes, Robert; Göritz, 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, 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
Double-dimer pairings and skew Young diagrams
Kenyon, Richard W
2010-01-01
We study the number of tilings of skew Young diagrams by ribbon tiles shaped like Dyck paths, in which the tiles are "vertically decreasing". We use these quantities to compute pairing probabilities in the double-dimer model: Given a planar bipartite graph $G$ with special vertices, called nodes, on the outer face, the double-dimer model is formed by the superposition of a uniformly random dimer configuration (perfect matching) of $G$ together with a random dimer configuration of the graph formed from $G$ by deleting the nodes. The double-dimer configuration consists of loops, doubled edges, and chains that start and end at the boundary nodes. We are interested in how the chains connect the nodes. An interesting special case is when the graph is $\\varepsilon(\\Z\\times\\N)$ and the nodes are at evenly spaced locations on the boundary $\\R$ as the grid spacing $\\varepsilon\\to 0$.
Julia Sets of Skew Products for Class MAp
王升
2004-01-01
Let fj ∈ M (j = 1, 2, …, m; m≥ 1) and （～f） be the skew product associated with the generator system {f1, f2, …, fm}. Then F （～f） is completely invariant under （～f）; J(（～f） is completely invariant under （～f）; J （～f） is perfect; J （～f） has interior points if and only if F （～f） = φ; if fj ∈ MAp (p ≥ 5), j =1, 2, …, m, then the set of the repelling fixed points of （～f） of all orders are dense in J （～f）.
On skew tau-functions in higher spin theory
Melnikov, D; Morozov, A
2016-01-01
Recent studies of higher spin theory in three dimensions concentrate on Wilson loops in Chern-Simons theory, which in the classical limit reduce to peculiar corner matrix elements between the highest and lowest weight states in a given representation of SL(N). Despite these "skew" tau-functions can seem very different from conventional ones, which are the matrix elements between the two highest weight states, they also satisfy the Toda recursion between different fundamental representations. Moreover, in the most popular examples they possess simple representations in terms of matrix models and Schur functions. We provide a brief introduction to this new interesting field, which, after quantization, can serve as an additional bridge between knot and integrability theories.
On skew tau-functions in higher spin theory
Melnikov, D.; Mironov, A.; Morozov, A.
2016-05-01
Recent studies of higher spin theory in three dimensions concentrate on Wilson loops in Chern-Simons theory, which in the classical limit reduce to peculiar corner matrix elements between the highest and lowest weight states in a given representation of SL( N ). Despite these "skew" tau-functions can seem very different from conventional ones, which are the matrix elements between the two highest weight states, they also satisfy the Toda recursion between different fundamental representations. Moreover, in the most popular examples they possess simple representations in terms of matrix models and Schur functions. We provide a brief introduction to this new interesting field, which, after quantization, can serve as an additional bridge between knot and integrability theories.
Likelihood Inference of Nonlinear Models Based on a Class of Flexible Skewed Distributions
Xuedong Chen
2014-01-01
Full Text Available This paper deals with the issue of the likelihood inference for nonlinear models with a flexible skew-t-normal (FSTN distribution, which is proposed within a general framework of flexible skew-symmetric (FSS distributions by combining with skew-t-normal (STN distribution. In comparison with the common skewed distributions such as skew normal (SN, and skew-t (ST as well as scale mixtures of skew normal (SMSN, the FSTN distribution can accommodate more flexibility and robustness in the presence of skewed, heavy-tailed, especially multimodal outcomes. However, for this distribution, a usual approach of maximum likelihood estimates based on EM algorithm becomes unavailable and an alternative way is to return to the original Newton-Raphson type method. In order to improve the estimation as well as the way for confidence estimation and hypothesis test for the parameters of interest, a modified Newton-Raphson iterative algorithm is presented in this paper, based on profile likelihood for nonlinear regression models with FSTN distribution, and, then, the confidence interval and hypothesis test are also developed. Furthermore, a real example and simulation are conducted to demonstrate the usefulness and the superiority of our approach.
GC skew is a conserved property of unmethylated CpG island promoters across vertebrates.
Hartono, Stella R; Korf, Ian F; Chédin, Frédéric
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
Assessment of seismic performance of skew reinforced concrete box girder bridges
Abdel-Mohti, Ahmed; Pekcan, Gokhan
2013-12-01
The seismic vulnerability of highway bridges remains an important problem and has received increased attention as a consequence of unprecedented damage observed during several major earthquakes. A significant number of research studies have examined the performance of skew bridges under service and seismic loads. The results of these studies are particularly sensitive to modeling assumptions in view of the interacting parameters. In the present study, three-dimensional improved beam-stick models of two-span highway bridges with skew angles varying from 0° to 60° are developed to investigate the seismic response characteristics of skew box girder bridges. The relative accuracy of beam-stick models is verified against counterpart finite element models. The effect of various parameters and conditions on the overall seismic response was examined such as skew angle, ground motion intensity, soil condition, abutment support conditions, bridge aspect ratio, and foundation-base conditions. The study shows that the improved beam-stick models can be used to conduct accurate nonlinear time history analysis of skew bridges. Skew angle and interacting parameters were found to have significant effect on the behavior of skewed highway bridges. Furthermore, the performance of shear keys may have a predominant effect on the overall seismic response of the skew bridges.
Does Realized Skewness Predict the Cross-Section of Equity Returns?
Amaya, Diego; Christoffersen, Peter; Jacobs, Kris; Vasquez, Aurelio
2015-01-01
We use intraday data to compute weekly realized moments for equity returns and study their time-series and cross-sectional properties. Buying stocks in the lowest realized skewness decile and selling stocks in the highest realized skewness decile generates an average return of 19 basis points the...
Subordinate wasps are more aggressive in colonies with low reproductive skew
Fanelli, D.; Boomsma, Jacobus Jan; Turillazzi, S.
2008-01-01
activity and actual interaction time between a and ß. We showed that (1) more even reproductive partitioning (lower reproductive skew) is associated with higher levels of aggression initiated by the ß subordinate independent of colony activity and (2) none of the currently available reproductive skew...
Skew detection and correction of ancient Tamil documents using particle swarm optimization
Sridevi, N.; Subashini, P.
2012-04-01
When a document is fed to a scanner either mechanically or by a human operator for digitization, it suffers from some degrees of skew or tilt. Skew detection is one of the first operations to be applied to scanned documents when converting data to a digital format. Its aim is to align an image before processing because text segmentation and recognition methods require properly aligned lines. This paper presents a new approach for skew detection and correction of documents. Particle Swarm Optimization (PSO) is used for solving skew optimization. A new objective function based on local maxima and minima of projection profile is formulated and PSO is used to find the best angle that maximizes the objective function. The proposed method is compared with existing methods like Hough transform, Fourier transform. Experimental results show that the proposed method corrects the skew with the maximum error rate of +/- 1° .
Nakajima Jouchi
2013-01-01
A Bayesian analysis of the stochastic volatility model with regime-switching skewness in heavy-tailed errors is proposed using a generalized hyperbolic (GH) skew Student’s t-distribution. The skewness parameter is allowed to shift according to a first-order Markov switching process. We summarize Bayesian methods for model fitting and discuss analyses of exchange rate return time series. Empirical results show that interpretable regime-switching skewness can improve model fit and Value-at-Risk...
Skew redundant MEMS IMU calibration using a Kalman filter
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. (paper)
On Approximating Frequency Moments of Data Streams with Skewed Projections
Li, Ping
2008-01-01
We propose skewed stable random projections for approximating the pth frequency moments of dynamic data streams (01) improves previous methods based on (symmetric) stable random projections. Our proposed method is applicable to data streams that are (a) insertion only (the cash-register model); or (b) always non-negative (the strict Turnstile model), or (c) eventually non-negative at check points. This is only a minor restriction for practical applications. Our method works particularly well when p = 1+/- \\Delta and \\Delta is small, which is a practically important scenario. For example, \\Delta may be the decay rate or interest rate, which are usually small. Of course, when \\Delta = 0, one can compute the 1th frequent moment (i.e., the sum) essentially error-free using a simple couter. Our method may be viewed as a ``genearlized counter'' in that it can count the total value in the future, taking in account of the effect of decaying or interest accruement. In a summary, our contributions are two-fold. (A) Thi...
COMPUTATIONAL AND EXPERIMENTAL STUDY ON TIP LEAKAGE VORTEX OF CIRCUMFERENTIAL SKEWED BLADES
LI Yang; OUYANG Hua; DU Zhaohui
2007-01-01
In the steady operation condition, the experiments and the numerical simulations are used to investigate the tip leakage flow fields in three low pressure axial flow fans with three kinds of circumferential skewed rotors, including the radial rotor, the forward-skewed rotor and the backward-skewed rotor. The three-dimensional viscous flow fields of the fans are computed. In the experiments, the two-dimensional plane particle image velocimetry (PIV) system is used to measure the flow fields in the tip region of three different pitchwise positions of each fan. The results show that the computational results agree well with the experimental data in the flow field of the tip region of each fan. The tip leakage vortex core segments based on method of the eigenmode analysis can display clearly some characteristics of the tip leakage vortex, such as the origination position of tip leakage vortex, the development of vortex strength, and so on. Compared with the radial rotor, the other two skewed rotors can increase the stability of the tip leakage vortex and the increment in the forward-skewed rotor is more than that in the backward-skewed one. Among the tip leakage vortices of the three rotors, the velocity of the vortex in the forward-skewed rotor is the highest in the circumferential direction and the lowest in the axial direction.
Inferences in Linear Mixed Models with Skew-normal Random Eff ects
Ren Dao YE; Tong Hui WANG
2015-01-01
For the linear mixed model with skew-normal random eff ects, this paper gives the density function, moment generating function and independence conditions. The noncentral skew chi-square distribution is defined and its density function is shown. The necessary and suﬃ cient conditions under which a quadratic form is distributed as noncentral skew chi-square distribution are obtained. Also, a version of Cochran’s theorem is given, which modifies the result of Wang et al. (2009) and is used to set up exact tests for fixed eff ects and variance components of the proposed model. For illustration, our main results are applied to a real data problem.
FEM-based Analysis of a Hybrid Synchronous Generator with Skewed Stator Slots
MUNTEANU, A.
2011-11-01
Full Text Available The paper presents a simulation study of a hybrid synchronous generator (dual excitation system - permanent magnets and electromagnets with skewed stator slots. The main goal is to establish if the skewing of the slots brings a significant improvement of the air-gap flux density and of the induced stator voltage. The skewness angle is the parameter in discussion. The study is based on finite element method analysis. Due to the particular geometry of the stator slots, a multilayer approach is employed.
75 FR 59681 - Trade Adjustment Assistance for Farmers
2010-09-28
... Foreign Agricultural Service Trade Adjustment Assistance for Farmers AGENCY: Foreign Agricultural Service... Farmers Program Review Committee, comprised of representatives from USDA's Office of the Chief Economist... adjustment assistance in FY 2011. FOR FURTHER INFORMATION CONTACT: Trade Adjustment Assistance for...
Full Text Available ... to my SCI? How do I deal with depression and adjustment to my SCI? ☷ ▾ Page contents The ... the moment you are injured. Understanding adjustment and depression Adjustment to paralysis is a process of changing ...
Generalized peak skew coefficients for Oklahoma, 1961-1990 base period.
U.S. Geological Survey, Department of the Interior — This digital-map data set consists of a grid of generalized skew coefficients of logarithms of annual maximum streamflow for Oklahoma streams less than or equal to...
LI Yang; LIU Jie; OUYANG Hua; DU Zhao-Hui
2008-01-01
This article presents the flow mechanism analysis and experimental study of a forward-skewed impeller and a radial impeller in low pressure axial fan. The forward-skewed blade was obtained by the optimization design of the radial blade and CFD technique. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the forward-skewed blade has demonstrated the improvements in efficiency, total pressure ratio, Stable Operating Range (SOR) and less aerodynamic noise. Detailed flow measurement and computation were performed for outlet flow field for investigating the responsible flow mechanisms. The results show the forward-skewed blade can cause a spanwise redistribution of flow toward the blade mid-span and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at mid-span.
On nomenclature for, and the relative merits of, two formulations of skew distributions
Azzalini, Adelchi
2015-12-21
We examine some skew distributions used extensively within the model-based clustering literature in recent years, paying special attention to claims that have been made about their relative efficacy. Theoretical arguments are provided as well as real data examples.
CONCEPTS OF DICHOTOMY FOR SKEW-EVOLUTION SEMIFLOWS IN BANACH SPACES
Mihail Megan
2011-01-01
Full Text Available In this paper we investigate some dichotomy concepts for skew-evolution semiflows in Banachspaces.Our main objective is to estab-lish relations between these concepts.We motivate our approach byillustrative examples.
Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades
Li Yang; Ouyang Hua; Du Zhao-Hui
2007-01-01
This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP) neural network and genetic algorithm (GA), the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pres...
Calculation of d- and q-axis inductances of PM brushless ac machines accounting for Skew
Chen, Y. S.; Zhu, Z.Q.; Howe, D.
2005-01-01
A hybrid two-dimensional (2-D) finite-element/analytical technique is described for predicting the d-axis and q-axis inductances of permanent magnet (PM) brushless ac machines, with due account for the influence of skew. Predicted inductances are compared with measured values for two machines having identical stators, which are skewed by one slot-pitch, but which have different rotor topologies, one having surface-mounted magnets and the other having interior magnets.
Nonlinear Seismic Response Analysis of Curved and Skewed Bridge System with Spherical Bearings
Linzell, Daniel G.; Junwon Seo; Jong Wan Hu
2013-01-01
A three-dimensional (3D) modeling approach to investigate nonlinear seismic response of a curved and skewed bridge system is proposed. The approach is applied to a three-span curved and skewed steel girder bridge in the United States. The superstructure is modeled using 3D frame elements for the girders, truss elements for the cross-frames, and equivalent frame elements to represent the deck. Spherical bearings are modeled with zero-length elements coupled with hysteretic material models. Non...
Wheat and corn price skewness and volatility: Risk management implications for farmers and end users
Williams, J.
2013-01-01
Little has been documented as to how price skewness and volatility can influence decision making regarding agribusiness risk taking and managing risk in a dynamic environment. Price volatility introduces opportunities for farmers and end users, but it also introduces new risks, which can then require management. Volatility-skewness matrices are developed using CME wheat and corn prices to tactically determine when pricing and hedging might be more successful for farmers and end users. Volatil...
Coalitions of relatives and reproductive skew in cooperatively breeding white-winged choughs.
R. Heinsohn; Dunn, P; Legge, S; Double, M
2000-01-01
We used DNA fingerprinting to examine reproductive skew in cooperatively breeding white-winged choughs, Corcorax melanorhamphos, which live in groups of up to 20 individuals. Before a severe drought, groups that had been stable for multiple years were characterized by long-term monogamy involving a single breeding pair (high skew). After the drought, new groups formed from the amalgamation of multiple individuals and coalitions of relatives. At most one member of each faction succeeded in bre...
Role of exterior and evolutionary skew-symmetric differential forms in mathematical physics
Petrova, L. I.
2005-01-01
A role of skew-symmetric differential forms in mathematical physics relates to the fact that they reflect the properties of conservation laws. The closed exterior forms correspond to the conservation laws for physical fields, whereas the evolutionary forms correspond to the conservation laws for material media. Skew-symmetric differential forms can describe a conjugacy of any objects (that correspond to the conservation laws). The closed exterior forms describe conjugated objects. And the evo...
Graded Skew Clifford Algebras that are Twists of Graded Clifford Algebras
Nafari, Manizheh; Vancliff, Michaela
2012-01-01
We prove that if $A$ is a regular graded skew Clifford algebra and is a twist of a regular graded Clifford algebra $B$ by an automorphism, then the subalgebra of $A$ generated by a certain normalizing sequence of homogeneous degree-two elements is a twist of a polynomial ring by an automorphism, and is a skew polynomial ring. We also present an example that demonstrates that this can fail when $A$ is not a twist of $B$.
Correction to: "On the Chambers-Mallows-Stuck Method for Simulating Skewed Stable Random Variables"
Weron, Rafal
1996-01-01
In the paper Weron (1996, Statist. Probab. Lett. 28, 165-171), I gave a proof to the equality in law of a skewed stable variable and a nonlinear transformation of two independent uniform and exponential variables. The Chambers et al. (1976, J. Amer. Statist. Assoc. 71, 340–344) method of computer generation of a skewed stable random variable is based on this equality. Unfortunately an error crept into my calculations for alpha=1. This note corrects the error.
Opposite GC skews at the 5' and 3' ends of genes in unicellular fungi
McLean Malcolm A
2011-12-01
Full Text Available Abstract Background GC-skews have previously been linked to transcription in some eukaryotes. They have been associated with transcription start sites, with the coding strand G-biased in mammals and C-biased in fungi and invertebrates. Results We show a consistent and highly significant pattern of GC-skew within genes of almost all unicellular fungi. The pattern of GC-skew is asymmetrical: the coding strand of genes is typically C-biased at the 5' ends but G-biased at the 3' ends, with intermediate skews at the middle of genes. Thus, the initiation, elongation, and termination phases of transcription are associated with different skews. This pattern influences the encoded proteins by generating differential usage of amino acids at the 5' and 3' ends of genes. These biases also affect fourfold-degenerate positions and extend into promoters and 3' UTRs, indicating that skews cannot be accounted by selection for protein function or translation. Conclusions We propose two explanations, the mutational pressure hypothesis, and the adaptive hypothesis. The mutational pressure hypothesis is that different co-factors bind to RNA pol II at different phases of transcription, producing different mutational regimes. The adaptive hypothesis is that cytidine triphosphate deficiency may lead to C-avoidance at the 3' ends of transcripts to control the flow of RNA pol II molecules and reduce their frequency of collisions.
Rubio, Francisco J; Genton, Marc G
2016-06-30
We study Bayesian linear regression models with skew-symmetric scale mixtures of normal error distributions. These kinds of models can be used to capture departures from the usual assumption of normality of the errors in terms of heavy tails and asymmetry. We propose a general noninformative prior structure for these regression models and show that the corresponding posterior distribution is proper under mild conditions. We extend these propriety results to cases where the response variables are censored. The latter scenario is of interest in the context of accelerated failure time models, which are relevant in survival analysis. We present a simulation study that demonstrates good frequentist properties of the posterior credible intervals associated with the proposed priors. This study also sheds some light on the trade-off between increased model flexibility and the risk of over-fitting. We illustrate the performance of the proposed models with real data. Although we focus on models with univariate response variables, we also present some extensions to the multivariate case in the Supporting Information. Copyright © 2016 John Wiley & Sons, Ltd. PMID:26856806
Rubio, Francisco J.
2016-02-09
We study Bayesian linear regression models with skew-symmetric scale mixtures of normal error distributions. These kinds of models can be used to capture departures from the usual assumption of normality of the errors in terms of heavy tails and asymmetry. We propose a general noninformative prior structure for these regression models and show that the corresponding posterior distribution is proper under mild conditions. We extend these propriety results to cases where the response variables are censored. The latter scenario is of interest in the context of accelerated failure time models, which are relevant in survival analysis. We present a simulation study that demonstrates good frequentist properties of the posterior credible intervals associated with the proposed priors. This study also sheds some light on the trade-off between increased model flexibility and the risk of over-fitting. We illustrate the performance of the proposed models with real data. Although we focus on models with univariate response variables, we also present some extensions to the multivariate case in the Supporting Information.
A Skew-t space-varying regression model for the spectral analysis of resting state brain activity.
Ismail, Salimah; Sun, Wenqi; Nathoo, Farouk S; Babul, Arif; Moiseev, Alexader; Beg, Mirza Faisal; Virji-Babul, Naznin
2013-08-01
It is known that in many neurological disorders such as Down syndrome, main brain rhythms shift their frequencies slightly, and characterizing the spatial distribution of these shifts is of interest. This article reports on the development of a Skew-t mixed model for the spatial analysis of resting state brain activity in healthy controls and individuals with Down syndrome. Time series of oscillatory brain activity are recorded using magnetoencephalography, and spectral summaries are examined at multiple sensor locations across the scalp. We focus on the mean frequency of the power spectral density, and use space-varying regression to examine associations with age, gender and Down syndrome across several scalp regions. Spatial smoothing priors are incorporated based on a multivariate Markov random field, and the markedly non-Gaussian nature of the spectral response variable is accommodated by the use of a Skew-t distribution. A range of models representing different assumptions on the association structure and response distribution are examined, and we conduct model selection using the deviance information criterion. (1) Our analysis suggests region-specific differences between healthy controls and individuals with Down syndrome, particularly in the left and right temporal regions, and produces smoothed maps indicating the scalp topography of the estimated differences. PMID:22614763
Chen Carton W
2007-08-01
Full Text Available Abstract Background Most bacterial chromosomes exhibit asymmetry of base composition with respect to leading vs. lagging strands (GC and AT skews. These skews reflect mainly those in protein coding sequences, which are driven by asymmetric mutation pressures during replication and transcription (notably asymmetric cytosine deamination plus subsequent selection for preferred structures, signals, amino acid or codons. The transcription-associated effects but not the replication-associated effects contribute to the overall skews through the uneven distribution of the coding sequences on the leading and lagging strands. Results Analysis of 185 representative bacterial chromosomes showed diverse and characteristic patterns of skews among different clades. The base composition skews in the coding sequences were used to derive quantitatively the effect of replication-driven mutation plus subsequent selection ('replication-associated pressure', RAP, and the effect of transcription-driven mutation plus subsequent selection at translation level ('transcription-associate pressure', TAP. While different clades exhibit distinct patterns of RAP and TAP, RAP is absent or nearly absent in some bacteria, but TAP is present in all. The selection pressure at the translation level is evident in all bacteria based on the analysis of the skews at the three codon positions. Contribution of asymmetric cytosine deamination was found to be weak to TAP in most phyla, and strong to RAP in all the Proteobacteria but weak in most of the Firmicutes. This possibly reflects the differences in their chromosomal replication machineries. A strong negative correlation between TAP and G+C content and between TAP and chromosomal size were also revealed. Conclusion The study reveals the diverse mutation and selection forces associated with replication and transcription in various groups of bacteria that shape the distinct patterns of base composition skews in the chromosomes during
Cross-Cultural Adjustment of Chinese Students in Japan: School Adjustment and Educational Support
Li, Yuan Xiang; Sano, Hideki; Ahn, Ruth
2013-01-01
This study investigates Chinese immigrant students' cross-cultural and school adjustment issues in Japanese schools. Using a quantitative method, a survey which collected students' demographic information, cross-cultural adjustment, and school adjustment questions was administered to 143 Chinese junior high and high school students in…
Characteristic function-based semiparametric inference for skew-symmetric models
Potgieter, Cornelis J.
2012-12-26
Skew-symmetric models offer a very flexible class of distributions for modelling data. These distributions can also be viewed as selection models for the symmetric component of the specified skew-symmetric distribution. The estimation of the location and scale parameters corresponding to the symmetric component is considered here, with the symmetric component known. Emphasis is placed on using the empirical characteristic function to estimate these parameters. This is made possible by an invariance property of the skew-symmetric family of distributions, namely that even transformations of random variables that are skew-symmetric have a distribution only depending on the symmetric density. A distance metric between the real components of the empirical and true characteristic functions is minimized to obtain the estimators. The method is semiparametric, in that the symmetric component is specified, but the skewing function is assumed unknown. Furthermore, the methodology is extended to hypothesis testing. Two tests for a hypothesis of specific parameter values are considered, as well as a test for the hypothesis that the symmetric component has a specific parametric form. A resampling algorithm is described for practical implementation of these tests. The outcomes of various numerical experiments are presented. © 2012 Board of the Foundation of the Scandinavian Journal of Statistics.
Detection of dark matter Skewness in the VIRMOS-DESCART survey Implications for \\Omega_0
Pen, U L; Van Waerbeke, L; Mellier, Y; Zhang, P; Dubinski, J; Pen, Ue-Li; Zhang, Tongjie; Waerbeke, Ludovic van; Mellier, Yannick; Zhang, Pengjie; Dubinski, John
2003-01-01
Weak gravitational lensing provides a direct statistical measure of the dark matter distribution. The variance is easiest to measure, which constrains the degenerate product \\sigma_8\\Omega^0.6. The degeneracy is broken by measuring the skewness arising from the fact that densities must remain positive, which is not possible when the initially symmetric perturbations become non-linear. Skewness measures the non-linear mass scale, which in combination with the variance measures \\Omega directly. We present the first detection of dark matter skewness from the Virmos-Decart survey. We have measured the full three point function, and its projections onto windowed skewness. We separate the lensing mode and the B mode. The lensing skewness is detected for a compensated Gaussian on scales of 5.37 arc minutes to be \\kappa^3=1.06+/- 0.06x10^-6. The B-modes are consistent with zero at this scale. The variance for the same window function is \\kappa^2= 5.32+/-0.62+/- 0.98x10^-5, resulting in S_3=375^{+342}_{-124}. Comparin...
Sex ratios and skew models: the special case of evolution of cooperation in polistine wasps.
Nonacs, Peter
2002-07-01
Cooperative breeding often involves reproductive dominance hierarchies. Such hierarchies have been proposed to form and to be maintained through an equitable skew in reproduction for both dominants and subordinates. The general form of skew models also predicts that cooperation can be stable only if cooperation greatly increases group reproductive success or subordinates are greatly constrained in their reproductive prospects relative to dominants. Neither, however, seems to be generally present in the colony initiation phase of temperate polistine wasps, although the behaviors of individuals within such groups are often consistent with skew model predictions. This apparent contradiction can be resolved in the context of a special case of the skew models that incorporate mother-offspring conflicts over sex ratios. Data suggest that all the needed preconditions are present for cooperating foundresses to gain an added benefit through producing male-biased investment ratios. Therefore, the special case model predicts that cooperation can evolve in Hymenoptera with both the observed high skews and reduced per capita group productivity. Further predictions of the special case model (e.g., mixed populations of single and multifoundresses) are also supported. Because the special case model is applicable only to haplodiploids, this may explain why cooperation in vertebrates rarely occurs without significant ecological or physiological constraints. Finally, comparisons to other social Hymenoptera taxa suggest that factors stabilizing cooperation between colony-initiating females may simultaneously constrain the evolution of morphologically specialized worker castes. PMID:18707502
Full Text Available ... depression and adjustment to my SCI? How do I deal with depression and adjustment to my SCI? ☷ ▾ ... following an SCI? What are the secondary conditions? I have no health insurance, what are my options? ...
Department of Housing and Urban Development — The Department of Housing and Urban Development establishes the rent adjustment factors - called Annual Adjustment Factors (AAFs) - on the basis of Consumer Price...
Full Text Available ... adjustment and depression Adjustment to paralysis is a process of changing one's thoughts and feelings and is ... stem cell research? What is the clinical trials process? Get support Ask us anything Get a peer ...
Full Text Available ... course an adjustment period as you navigate your new normal. The most important point to remember is ... to rebuild one's identity and to find a new balance in relationships. The stages of adjustment can ...
Verkuil, Yvonne; Juillet, Cedric; Lank, David B.; Widemo, Fredrik; Piersma, Theunis
2014-01-01
Sex differences in skews of vertebrate lifetime reproductive success are difficult to measure directly. Evolutionary histories of differential skew should be detectable in the genome. For example, male-biased skew should reduce variation in the biparentally inherited genome relative to the maternally inherited genome. We tested this approach in lek-breeding ruff (Class Aves, Philomachus pugnax) by comparing genetic variation of nuclear microsatellites (θn; biparental) versus mitochondrial D-l...
Tarnopolski, Mariusz
2015-01-01
Two classes of GRBs have been 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 durations 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 normal distributions. However, this might possibly not be an adequate model. This paper investigates whether the distribution of $\\log T_{90}$ from Fermi shows evidence for a third, intermediate, class of GRBs. Mixtures of standard Gaussians, 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 than a mixture of three standard Gaussians. Based on statistical reasoning, exi...
Kitamura, S. [Kusatsu Electric Co. Ltd., Shiga (Japan); Ishihara, Y.; Todaka, T. [Doshisha University, Kyoto (Japan)
1998-02-01
In this paper, we propose an analytical method for a motor with skewed magnets. In our proposal method, a motor is divided into the some segments, and then the sum of the induced voltage of each segments are coupled with the circuit equation, so that it becomes possible for 2-D FEM to take skewed effects into account. The proposed method has been applied to the analysis of DC Blushless Motor. Calculated results of induced voltage waveforms on no-load show close agreement with measured values. In addition the results of winding current waveforms and average torque vs. speed characteristics in steady state indicate good results. These results confirmed the validity of this method. 9 refs., 19 figs.
Skewed Normal Distribution Of Return Assets In Call European Option Pricing
Evy Sulistianingsih
2011-12-01
Full Text Available Option is one of security derivates. In financial market, option is a contract that gives a right (notthe obligation for its owner to buy or sell a particular asset for a certain price at a certain time.Option can give a guarantee for a risk that can be faced in a market.This paper studies about theuse of Skewed Normal Distribution (SN in call europeanoption pricing. The SN provides aflexible framework that captures the skewness of log return. We obtain aclosed form solution forthe european call option pricing when log return follow the SN. Then, we will compare optionprices that is obtained by the SN and the Black-Scholes model with the option prices of market.Â Keywords: skewed normaldistribution, log return, options.
Perceived quality of wood images influenced by the skewness of image histogram
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.
Effect of PCC Joint Skew on Reflective Cracking in HMA Overlays
Ghauch, By Ziad G
2011-01-01
Reflective cracking is a relatively premature distress that occurs in HMA materials overlaying cracked and jointed underlying pavements. The high concentration of stresses and strains in the vicinity of the discontinuity of the old pavement causes the cracks to reflect into the newly placed HMA overlay. While it is a common practice to use skewed transverse joints in rigid pavements to improve the latter's performance, the impact of such a practice on the cracking of a potential HMA overlay has not been examined so far. In this context, this study investigates the effect of using skewed transverse joints in rigid pavements on reflective cracking development in the HMA overlay. Advanced three-dimensional Finite Element models including viscoelastic material properties for the HMA overlay, 3D beam modeling of dowel bars, non-uniform tire-pavement contact stresses, friction interfaces, and infinite boundary elements were constructed for both normal and skewed transverse joints using ABAQUS v-6.11. The potential ...
Gaudin-type models, non-skew-symmetric classical r-matrices and nested Bethe ansatz
T. Skrypnyk
2015-02-01
Full Text Available We consider quantum integrable systems associated with the Lie algebra gl(n and Cartan-invariant non-dynamical non-skew-symmetric classical r-matrices. We describe the sub-class of Cartan-invariant non-skew-symmetric r-matrices for which exists the standard procedure of the nested Bethe ansatz associated with the chain of embeddings gl(n⊃gl(n−1⊃gl(n−2⊃⋯⊃gl(1. We diagonalize the corresponding quantum integrable systems by its means. We illustrate the obtained results by the examples of the generalized Gaudin systems with and without external magnetic field associated with three classes of non-dynamical non-skew-symmetric classical r-matrices.
许正文; 吴健; 霍文平; 吴振森
2003-01-01
Electromagnetic pulsed waves can be distorted in the propagation through random media, and their energy dis tributions change along the leading and trailing edge of the waveform, which can be presented by the temporal skewness. The skewness presents asymmetry and is treated by the third-order temporal moment, in which an analytic solution for the two-frequency mutual coherence function is obtained recently. Then, transionospheric pulses are discussed in details. Both theoretical analysis and numerical computation indicate that the contri butions from scattering and dispersion of irregularities dominate over those of background, so the latter can be neglected in most cases. Also, the temporal skewness of a transionospheric pulse is negative and energy is shifted to the leading edge.
Finding the Right Distribution for Highly Skewed Zero-inflated Clinical Data
Resmi Gupta
2013-03-01
Full Text Available Discrete, highly skewed distributions with excess numbers of zeros often result in biased estimates and misleading inferences if the zeros are not properly addressed. A clinical example of children with electrophysiologic disorders in which many of the children are treated without surgery is provided. The purpose of the current study was to identify the optimal modeling strategy for highly skewed, zeroinflated data often observed in the clinical setting by: (a simulating skewed, zero-inflated count data; (b fitting simulated data with Poisson, Negative Binomial, Zero-Inflated Poisson (ZIP and Zero-inflated Negative Binomial (ZINB models; and, (c applying the aforementioned models to actual, highlyskewed, clinical data of children with an EP disorder. The ZIP model was observed to be the optimal model based on traditional fit statistics as well as estimates of bias, mean-squared error, and coverage.
Elevated mortality among birds in Chernobyl as judged from skewed age and sex ratios.
Anders Pape Møller
Full Text Available 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
The gestural misinformation effect: skewing eyewitness testimony through gesture.
Gurney, Daniel J; Pine, Karen J; Wiseman, Richard
2013-01-01
The susceptibility of eyewitnesses to verbal suggestion has been well documented, although little attention has been paid to the role of nonverbal communication in misinformation. Three experiments are reported; in each, participants watched footage of a crime scene before being questioned about what they had observed. In Experiments 1 and 2, an on-screen interviewer accompanied identically worded questions with gestures that either conveyed accurate information about the scene or conveyed false, misleading information. The misleading gestures significantly influenced recall, and participants' responses were consistent with the gestured information. In Experiment 3, a live interview was conducted, and the gestural misinformation effect was found to be robust; participants were influenced by misleading gestures performed by the interviewer during questioning. These findings provide compelling evidence for the gestural misinformation effect, whereby subtle hand gestures can implant information and distort the testimony of eyewitnesses. The practical and legal implications of these findings are discussed. PMID:24027944
Castagliola, Philippe; Michael B.C. Khoo
2009-01-01
Abstract In this paper, a synthetic scaled weighted variance Xbar (synthetic SWV-Xbar) control chart is proposed to monitor the process mean of skewed populations. A comparison between the performances of the synthetic SWV-Xbar and synthetic WV-Xbar charts are made in terms of the average run length (ARL) values for the various levels of skewnesses as well as different magnitudes of positive and negative shifts in the mean. A method to construct the synthetic SWV-Xbar chart is exp...
Random and deterministic perturbation of a class of skew-product systems
Broomhead, David S.; Hadjiloucas, Demetris; Nicol, Matthew
1999-01-01
This paper is concerned with the stability properties of skew-products T (,i>x,y) = (f(x), g(x,y)) in which (f,X,mu) is an ergodic map of a compact metric space X and g: X x Rn → Rn is continuous. We assume that the skew-product has a negative maximal Lyapunov exponent in the fibre. We study the orbit stability and stability of mixing of T (,i>x,y) = (f(x), g(x,y)) under deterministic and random perturbation of g. We show that such systems are stable in the sense that for any epsilon ...
X-Y coupling generation with AC/pulsed skew quadrupole and its application
The new method of x-y coupling generation with AC or pulsed skew quadrupole is proposed. With this method, no difference resonance is requested; therefore the horizontal and vertical tunes should not be the same value. The AC skew quadrupole is driven by the difference frequency of horizontal and vertical betatron frequency to convert the horizontal position frequency to the vertical kick frequency and vice versa, therefore the coupling with this method is on resonance and can be driven to full coupling strength. In this report, the principle, simulation result, and possible applications are descried. (author)
FP-Hadoop: Efficient Execution of Parallel Jobs Over Skewed Data
Liroz-Gistau, Miguel; Akbarinia, Reza; Valduriez, Patrick
2015-01-01
Big data parallel frameworks, such as MapReduce or Spark have been praised for their high scalability and performance, but show poor performance in the case of data skew. There are important cases where a high percentage of processing in the reduce side ends up being done by only one node. In this demonstration, we illustrate the use of FP-Hadoop, a system that efficiently deals with data skew in MapReduce jobs. In FP-Hadoop, there is a new phase, called intermediate reduce (IR), in which blo...
Option-Based Estimation of the Price of Co-Skewness and Co-Kurtosis Risk
Christoffersen, Peter; Fournier, Mathieu; Fournier, Mathieu;
We show that the prices of risk for factors that are nonlinear in the market return are readily obtained using index option prices. We apply this insight to the price of co-skewness and co-kurtosis risk. The price of co-skewness risk corresponds to the spread between the physical and the risk-neu......-kurtosis risk indicates that the new estimates of the price of risk improve the models performance. Models with higher-order market moments also robustly outperform standard competitors such as the CAPM and the Fama-French model....
Option-Based Estimation of the Price of Co-Skewness and Co-Kurtosis Risk
Christoffersen, Peter; Fournier, Mathieu; Jacobs, Kris;
We show that the prices of risk for factors that are nonlinear in the market return are readily obtained using index option prices. We apply this insight to the price of co-skewness and co-kurtosis risk. The price of co-skewness risk corresponds to the spread between the physical and the risk-neu......-kurtosis risk indicates that the new estimates of the price of risk improve the models' performance. Models with higher-order market moments also robustly outperform standard competitors such as the CAPM and the Fama-French model....
Mekerov, Dimitar
2009-01-01
In the present work we consider an almost complex manifold with Norden metric (i.e. a metric with respect to which the almost complex structure is an antiisometry). On such a manifold we study a linear connection preserving the almost complex structure and the metric and having a totally skew-symmetric torsion tensor. We consider the case when the manifold admits a connection with parallel totally skew-symmetric torsion and the case when such connection has a Kaehler curvature tensor. We get necessary and sufficient conditions for an isotropic Kaehler manifold with Norden metric.
Large-scale genomic 2D visualization reveals extensive CG-AT skew correlation in bird genomes
Deng Xuemei
2007-11-01
Full Text Available Abstract Background Bird genomes have very different compositional structure compared with other warm-blooded animals. The variation in the base skew rules in the vertebrate genomes remains puzzling, but it must relate somehow to large-scale genome evolution. Current research is inclined to relate base skew with mutations and their fixation. Here we wish to explore base skew correlations in bird genomes, to develop methods for displaying and quantifying such correlations at different scales, and to discuss possible explanations for the peculiarities of the bird genomes in skew correlation. Results We have developed a method called Base Skew Double Triangle (BSDT for exhibiting the genome-scale change of AT/CG skew as a two-dimensional square picture, showing base skews at many scales simultaneously in a single image. By this method we found that most chicken chromosomes have high AT/CG skew correlation (symmetry in 2D picture, except for some microchromosomes. No other organisms studied (18 species show such high skew correlations. This visualized high correlation was validated by three kinds of quantitative calculations with overlapping and non-overlapping windows, all indicating that chicken and birds in general have a special genome structure. Similar features were also found in some of the mammal genomes, but clearly much weaker than in chickens. We presume that the skew correlation feature evolved near the time that birds separated from other vertebrate lineages. When we eliminated the repeat sequences from the genomes, the AT and CG skews correlation increased for some mammal genomes, but were still clearly lower than in chickens. Conclusion Our results suggest that BSDT is an expressive visualization method for AT and CG skew and enabled the discovery of the very high skew correlation in bird genomes; this peculiarity is worth further study. Computational analysis indicated that this correlation might be a compositional characteristic
A Digital Game for International Students' Adjustment
Bisadi, Maryam; Chua, Alton Y. K; Keong, Lee Chu
2013-01-01
Although digital games have been developed for various subject areas, little attention has been focused on using digital games to address international students' adjustment issues. For this reason, this paper endeavors to explore the use of a digital game in facilitating international students acquire adjustment-related information. Specifically,…
The curious anomaly of skewed judgment distributions and systematic error in the wisdom of crowds.
Ulrik W Nash
Full Text Available 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.
Finite element studies on free vibration of laminated composite cylindrical skew panels
Srinivasa C.V.
2014-02-01
Full Text Available This paper presents the finite element studies on free vibration of isotropic and laminated composite cylindrical skew panels. The analysis is performed using CQUAD4 and CQUAD8 elements of MSC/NASTRAN. The effects of the panel angle, skew angle, aspect ratio and length-to-thickness-ratio on fundamental frequency of isotropic cylindrical skew panels are studied. The effects of additional parameters such as the fiber orientation angle, numbers of layers and stacking sequence on the fundamental frequency of antisymmetric composite laminates are also studied. It is found that the CQUAD8 element yields better results than the CQUAD4 element in the validation and convergence studies. The CQUAD8 element is employed for the remaining part of the studies. The fundamental frequencies are found to increase with the panel angle and skew angle. When the number of layers in the laminate is large, the variation of the fundamental frequency with the number of layers is not appreciable. The boundary conditions are found to have a significant influence on the fundamental frequency
Generalized Christoffel-Darboux formula for skew-orthogonal polynomials and random matrix theory
We obtain a generalized Christoffel-Darboux (GCD) formula for skew-orthogonal polynomials. Using this, we present an alternative derivation of the level density and two-point function for Gaussian orthogonal ensembles and Gaussian symplectic ensembles of random matrices. (author)
Tan, Kun; An, Lei; Miao, Kai; Ren, Likun; Hou, Zhuocheng; Tao, Li; Zhang, Zhenni; Wang, Xiaodong; Xia, Wei; Liu, Jinghao; Wang, Zhuqing; Xi, Guangyin; Gao, Shuai; Sui, Linlin; Zhu, De-Sheng; Wang, Shumin; Wu, Zhonghong; Bach, Ingolf; Chen, Dong-Bao; Tian, Jianhui
2016-03-22
Dynamic epigenetic reprogramming occurs during normal embryonic development at the preimplantation stage. Erroneous epigenetic modifications due to environmental perturbations such as manipulation and culture of embryos during in vitro fertilization (IVF) are linked to various short- or long-term consequences. Among these, the skewed sex ratio, an indicator of reproductive hazards, was reported in bovine and porcine embryos and even human IVF newborns. However, since the first case of sex skewing reported in 1991, the underlying mechanisms remain unclear. We reported herein that sex ratio is skewed in mouse IVF offspring, and this was a result of female-biased peri-implantation developmental defects that were originated from impaired imprinted X chromosome inactivation (iXCI) through reduced ring finger protein 12 (Rnf12)/X-inactive specific transcript (Xist) expression. Compensation of impaired iXCI by overexpression ofRnf12to up-regulateXistsignificantly rescued female-biased developmental defects and corrected sex ratio in IVF offspring. Moreover, supplementation of an epigenetic modulator retinoic acid in embryo culture medium up-regulatedRnf12/Xistexpression, improved iXCI, and successfully redeemed the skewed sex ratio to nearly 50% in mouse IVF offspring. Thus, our data show that iXCI is one of the major epigenetic barriers for the developmental competence of female embryos during preimplantation stage, and targeting erroneous epigenetic modifications may provide a potential approach for preventing IVF-associated complications. PMID:26951653
Influence of Slope and Slenderness Ratio on the Non-Column Volume in Skew Rolling
Yongqiang KANG; Zhenghuan HU; Jinping LIU; Cuiping YANG; Huiping DU
2003-01-01
A definition of non-column volume ratio (NCVR) is brought forward by the authors. It is influenced greatly by the slendernessratio of the cylindrical billet and the slope of the wedge on the tool of skew rolling. Using the numerical simulation, the lawof
Consistent paternity skew through ontogeny in Peron's tree frog (Litoria peronii.
Craig D H Sherman
Full Text Available BACKGROUND: A large number of studies in postcopulatory sexual selection use paternity success as a proxy for fertilization success. However, selective mortality during embryonic development can lead to skews in paternity in situations of polyandry and sperm competition. Thus, when assessment of paternity fails to incorporate mortality skews during early ontogeny, this may interfere with correct interpretation of results and subsequent evolutionary inference. In a previous series of in vitro sperm competition experiments with amphibians (Litoria peronii, we showed skewed paternity patterns towards males more genetically similar to the female. METHODOLOGY/PRINCIPAL FINDINGS: Here we use in vitro fertilizations and sperm competition trials to test if this pattern of paternity of fully developed tadpoles reflects patterns of paternity at fertilization and if paternity skews changes during embryonic development. We show that there is no selective mortality through ontogeny and that patterns of paternity of hatched tadpoles reflects success of competing males in sperm competition at fertilization. CONCLUSIONS/SIGNIFICANCE: While this study shows that previous inferences of fertilization success from paternity data are valid for this species, rigorous testing of these assumptions is required to ensure that differential embryonic mortality does not confound estimations of true fertilization success.
Influence of pressure gradient on streamwise skewness factor in turbulent boundary layer
The paper shows an effect of favourable and adverse pressure gradients on turbulent boundary layer. The skewness factor of streamwise velocity component was chosen as a measure of the pressure gradient impact. It appears that skewness factor is an indicator of convection velocity of coherent structures, which is not always equal to the average flow velocity. The analysis has been performed based upon velocity profiles measured with hot-wire technique in turbulent boundary layer with pressure gradient corresponding to turbomachinery conditions. The results show that the skewness factor decreases in the flow region subjected to FPG and increases in the APG conditions. The changes of convection velocity and skewness factor are caused by influence of large-scale motion through the mechanism called amplitude modulation. The large-scale motion is less active in FPG and more active in APG, therefore in FPG the production of vortices is random (there are no high and low speed regions), while in the APG the large-scale motion drives the production of vortices. Namely, the vortices appear only in the high-speed regions, therefore have convection velocity higher than local mean velocity. The convection velocity affects directly the turbulent sweep and ejection events. The more flow is dominated by large-scale motion the higher values takes both the convection velocity of small-scale structures and sweep events induced by them.
Linear independence of cluster monomials for skew-symmetric cluster algebras
Irelli, Giovanni Cerulli; Keller, Bernhard; Labardini-Fragoso, Daniel; Plamondon, Pierre-Guy
2012-01-01
Fomin-Zelevinsky conjectured that in any cluster algebra, the cluster monomials are linearly independent and that the exchange graph and cluster complex are independent of the choice of coefficients. We confirm these conjectures for all skew-symmetric cluster algebras.
无
2007-01-01
In this article, the low pressure axial flow fan with circumferential skewed rotor blade, including the radial blade, the forward-skewed blade and the backward-skewed blade, was studied with experimental methods. The aerodynamic performance of the rotors was measured. At the design condition at outlet of the rotors, detailed flow measurements were performed with a five-hole probe and a Hot-Wire Anemometer (HWA). The results show that compared to the radial rotor, the forward-skewed rotor demonstrates a wider Stable Operating Range (SOR), is able to reduce the total pressure loss in the hub region and make main loading of blade accumulating in the mid-span region. There is a wider wake in the upper mid-span region of the forward-skewed rotor. Compared to the radial rotor, in the backward-skewed rotor there is higher total pressure loss near the hub and shroud regions and lower loss in the mid-span region. In addition, the velocity deficit in the wake is lower at mid-span of the backward-skewed rotor than the forward-skewed rotor.
Gałkin, A. M.
2007-01-01
Full Text Available The paper discusses the process of hot rolling on skew rolling mills and compares it with other methods of manufacturing rods (shape milling and tubes (pilger rolling. The method and results of calculation of the optimal price of a three-roll skew rolling mill taking into account the benefits for the purchaser and the manufacturer are given.
Repatriation Adjustment: Literature Review
Gamze Arman
2009-12-01
Full Text Available Expatriation is a widely studied area of research in work and organizational psychology. After expatriates accomplish their missions in host countries, they return to their countries and this process is called repatriation. Adjustment constitutes a crucial part in repatriation research. In the present literature review, research about repatriation adjustment was reviewed with the aim of defining the whole picture in this phenomenon. Present research was classified on the basis of a theoretical model of repatriation adjustment. Basic frame consisted of antecedents, adjustment, outcomes as main variables and personal characteristics/coping strategies and organizational strategies as moderating variables.
Weihong Huang
2000-01-01
Full Text Available Conventional adaptive expectation as a mechanism of stabilizing an unstable economic process is reexamined through a generalization to an adaptive adjustment framework. The generic structures of equilibria that can be stabilized through an adaptive adjustment mechanism are identified. The generalization can be applied to a broad class of discrete economic processes where the variables interested can be adjusted or controlled directly by economic agents such as in cobweb dynamics, Cournot games, Oligopoly markets, tatonnement price adjustment, tariff games, population control through immigration etc.
P Shivakumara; G Hemantha Kumar; D S Guru; P Nagabhushan
2005-02-01
When a document is scanned either mechanically or manually for digitization, it often suffers from some degree of skew or tilt. Skew-angle detection plays an important role in the ﬁeld of document analysis systems and OCR in achieving the expected accuracy. In this paper, we consider skew estimation of Roman script. The method uses the boundary growing approach to extract the lowermost and uppermost coordinates of pixels of characters of text lines present in the document, which can be subjected to linear regression analysis (LRA) to determine the skew angle of a skewed document. Further, the proposed technique works ﬁne for scaled text binary documents also. The technique works based on the assumption that the space between the text lines is greater than the space between the words and characters. Finally, in order to evaluate the performance of the proposed methodology we compare the experimental results with those of well-known existing methods.
Pamela L Reynolds
Full Text Available 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.
2009-01-01
An adjustable microchip holder for holding a microchip is provided having a plurality of displaceable interconnection pads for connecting the connection holes of a microchip with one or more external devices or equipment. The adjustable microchip holder can fit different sizes of microchips with ...
75 FR 59683 - Trade Adjustment Assistance for Farmers
2010-09-28
... Foreign Agricultural Service Trade Adjustment Assistance for Farmers AGENCY: Foreign Agricultural Service... for Farmers Program Review Committee, comprised of representatives from USDA's Office of the Chief... assistance in FY 2011. FOR FURTHER INFORMATION, CONTACT: Trade Adjustment Assistance for Farmers...
Boháčová, Ivana; Podliska, J.; Hasil, Jan
Praha: Institute of Archaeology of the CAS, 2015 - (Kuna, M.), s. 99-113 ISBN 978-80-87365-88-5 R&D Projects: GA MK(CZ) DF13P01OVV014 Keywords : information system * archaeology * Prague * heritage Subject RIV: AC - Archeology, Anthropology, Ethnology
Olson, Scott A.; with a section by Veilleux, Andrea G.
2014-01-01
This report provides estimates of flood discharges at selected annual exceedance probabilities (AEPs) for streamgages in and adjacent to Vermont and equations for estimating flood discharges at AEPs of 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent (recurrence intervals of 2-, 5-, 10-, 25-, 50-, 100-, 200-, and 500-years, respectively) for ungaged, unregulated, rural streams in Vermont. The equations were developed using generalized least-squares regression. Flood-frequency and drainage-basin characteristics from 145 streamgages were used in developing the equations. The drainage-basin characteristics used as explanatory variables in the regression equations include drainage area, percentage of wetland area, and the basin-wide mean of the average annual precipitation. The average standard errors of prediction for estimating the flood discharges at the 50-, 20-, 10-, 4-, 2-, 1-, 0.5-, and 0.2-percent AEP with these equations are 34.9, 36.0, 38.7, 42.4, 44.9, 47.3, 50.7, and 55.1 percent, respectively. Flood discharges at selected AEPs for streamgages were computed by using the Expected Moments Algorithm. To improve estimates of the flood discharges for given exceedance probabilities at streamgages in Vermont, a new generalized skew coefficient was developed. The new generalized skew for the region is a constant, 0.44. The mean square error of the generalized skew coefficient is 0.078. This report describes a technique for using results from the regression equations to adjust an AEP discharge computed from a streamgage record. This report also describes a technique for using a drainage-area adjustment to estimate flood discharge at a selected AEP for an ungaged site upstream or downstream from a streamgage. The final regression equations and the flood-discharge frequency data used in this study will be available in StreamStats. StreamStats is a World Wide Web application providing automated regression-equation solutions for user-selected sites on streams.
Construction engineering of steel tub-girder bridge systems for skew effects
Jimenez Chong, Juan Manuel
Closed structural sections, such as those having circular, rectangular or trapezoidal shape, possess high rotational rigidity when compared to open sections such as I-girders. The high torsional rigidity of closed sections makes them ideal for use in highly curved bridges. In this case, the geometry of the bridge results in large torsional forces. Because of structural efficiency and economy reasons, most of these closed-section bridges consist of a trapezoidal cross-section, with a top concrete slab and bottom and side steel plates. The slab is cast after the steel is erected and thus a system of internal diaphragms and braces is necessary to stabilize the system during erection. During the steel erection and the early stages of the concrete deck placement, the section can be considered as quasi-closed as the top concrete flange has not been cast or is not yet effective. During steel erection, undetermined and/or large torsional forces and/or displacements may result in fit-up problems requiring large stresses to overcome. During concrete deck placement, the undetermined displacements can affect the control of the deck thickness and the final deck geometry, such as the alignment of deck joints and the matching of stages in phased constructions projects. Due to the interactions between their various components, the behavior of curved and skewed tub-girder bridges is significantly more complex than that of straight bridges. When skewed supports are used in tub-girders, the interaction of the girder bending rotations and the displacement constraints induced by the skewed support diaphragms causes twisting of the girders at the supports. These twist rotations introduce additional torques into the system. Both curvature and skew can cause design and construction difficulties, especially at the supports, where the corresponding steel dead load deflections and the large torsional stiffness of the girders may lead to large fit-up forces. Currently, the general
Full Text Available ... rebuild one's identity and to find a new balance in relationships. The stages of adjustment can include ... a peer mentor Advocate for change Fundraise with Team Reeve Champions Committee Volunteering About Us Our story ...
... Public / Speech, Language and Swallowing / Disorders and Diseases Family Adjustment to Aphasia Richard S. was a senior manager ... It also presents a great challenge to the family. There may be tension among family members and ...
Full Text Available ... identity and to find a new balance in relationships. The stages of adjustment can include grieving, taking ... treatment options. Related pages What is a complete vs incomplete injury? What emergency procedures occur following an ...
Full Text Available ... thoughts and feelings and is something that takes time. The goal of adjusting is to rebuild one's ... updates about our impact > Get the Reeve newsletter International support > Pages in other languages Made with ♡ in ...
Adjustment to Cancer: Anxiety and Distress (PDQ®)—Health Professional Version
Expert-reviewed information summary about the difficult emotional responses many cancer patients experience. This summary focuses on normal adjustment issues, psychosocial distress, and adjustment disorders.
Occupational Adjustment of Immigrants
Zorlu, Aslan
2011-01-01
This paper examines the speed of the occupational adjustment of immigrants using Labour Force Surveys 2004 and 2005 from Statistics Netherlands. The analysis provides new evidence that immigrants start with jobs at the lower levels of skill distribution. Their occupational achievement improves significantly with the duration of residence. The extent of this initial disadvantage and the rate of adjustment vary across immigrant groups according to the transferability of skills associated with t...
KVA: Capital Valuation Adjustment
Andrew Green; Chris Kenyon
2014-01-01
Credit (CVA), Debit (DVA) and Funding Valuation Adjustments (FVA) are now familiar valuation adjustments made to the value of a portfolio of derivatives to account for credit risks and funding costs. However, recent changes in the regulatory regime and the increases in regulatory capital requirements has led many banks to include the cost of capital in derivative pricing. This paper formalises the addition of cost of capital by extending the Burgard-Kjaer (2013) semi-replication approach to C...
LIU Shi-guang; WANG Xiao-juan; PENG Qun-sheng
2011-01-01
Due to the different lighting environments or other reasons, the pixel colors may be quite different in one image which causes distinct visual discontinuities. It makes the analysis and processing of such an image more difficult and sometime impossible. In this paper, a unified multi-toning image adjustment method is proposed to solve this problem. First, a novel unsupervised clustering method was proposed to partition the source and the target image into a certain number of subsets with similar color statistics. By matching the texture characteristics and luminance distribution between the blocks, it can create optimized correspondence. Then, the color information was transferred from the matched pixels in the source blocks to the target ones. Graph cut method was used to optimize the seams between different subsets in the final step. This method can automatically perform color adjustment of a multi-toning image. It is simple and efficient. Various results show the validity of this method.
Optimization Design and Experimental Study of Low-Pressure Axial Fan with Forward-Skewed Blades
Li Yang
2007-01-01
Full Text Available This paper presents an experimental study of the optimization of blade skew in low pressure axial fan. Using back propagation (BP neural network and genetic algorithm (GA, the optimization was performed for a radial blade. An optimized blade is obtained through blade forward skew. Measurement of the two blades was carried out in aerodynamic and aeroacoustic performance. Compared to the radial blade, the optimized blade demonstrated improvements in efficiency, total pressure ratio, stable operating range, and aerodynamic noise. Detailed flow measurement was performed in outlet flow field for investigating the responsible flow mechanisms. The optimized blade can cause a spanwise redistribution of flow toward the blade midspan and reduce tip loading. This results in reduced significantly total pressure loss near hub and shroud endwall region, despite the slight increase of total pressure loss at midspan. In addition, the measured spectrums show that the broadband noise of the impeller is dominant.
Skew ray tracing in a step-index optical fiber using Geometric Algebra
Ang, Angeleene; McNamara, Daniel J
2015-01-01
We used Geometric Algebra to compute the paths of skew rays in a cylindrical, step-index multimode optical fiber. To do this, we used the vector addition form for the law of propagation, the exponential of an imaginary vector form for the law of refraction, and the juxtaposed vector product form for the law of reflection. In particular, the exponential forms of the vector rotations enables us to take advantage of the addition or subtraction of exponential arguments of two rotated vectors in the derivation of the ray tracing invariants in cylindrical and spherical coordinates. We showed that the light rays inside the optical fiber trace a polygonal helical path characterized by three invariants that relate successive reflections inside the fiber: the ray path distance, the difference in axial distances, and the difference in the azimuthal angles. We also rederived the known generalized formula for the numerical aperture for skew rays, which simplifies to the standard form for meridional rays.
Cavitation Simulation on Conventional and Highly-Skewed Propellers in the Behind Condition
Shin, Keun Woo; Andersen, Poul; Mikkelsen, Robert Flemming
2011-01-01
the study of implementing a HEM cavitation model for computing unsteady cavitation patterns in behind-hull condition with respect to blade angles and cavity extent on the complicated geometry of a conventional/highly-skewed propeller. In the computations, the efficiency of the non-homogeneously loaded......The cavitating flows around conventional and highly-skewed propellers in the behind-hull condition are simulated by an in-house RANS solver, EllipSys (Sørensen 2003), with the cavitation model, based on the homogeneous equilibrium modeling (HEM) approach and a vapor transport equation...... in the propeller plane is applied by using a non-homogenously loaded actuator disk (Mikkelsen et al 2007) placed in a plane upstream of the propeller. The variation of the computed cavitation profile with respect to the blade angle is compared with that from the cavitation tunnel test. The present work describes...
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