Deterministic bootstrap percolation in high dimensional grids
Huang, Hao; Lee, Choongbum
2013-01-01
In this paper, we study the k-neighbor bootstrap percolation process on the d-dimensional grid [n]^d, and show that the minimum number of initial vertices that percolate is (1-d/k)n^d + O(n^{d-1})$ when d
On bootstrap sample size in extreme value theory
J.L. Geluk (Jaap); L.F.M. de Haan (Laurens)
2002-01-01
textabstractIt has been known for a long time that for bootstrapping the probability distribution of the maximum of a sample consistently, the bootstrap sample size needs to be of smaller order than the original sample size. See Jun Shao and Dongsheng Tu (1995), Ex. 3.9,p. 123. We show that the same
Fixed-b Subsampling and Block Bootstrap: Improved Confidence Sets Based on P-value Calibration
Shao, Xiaofeng
2012-01-01
Subsampling and block-based bootstrap methods have been used in a wide range of inference problems for time series. To accommodate the dependence, these resampling methods involve a bandwidth parameter, such as subsampling window width and block size in the block-based bootstrap. In empirical work, using different bandwidth parameters could lead to different inference results, but the traditional first order asymptotic theory does not capture the choice of the bandwidth. In this article, we propose to adopt the fixed-b approach, as advocated by Kiefer and Vogelsang (2005) in the heteroscedasticity-autocorrelation robust testing context, to account for the influence of the bandwidth on the inference. Under the fixed-b asymptotic framework, we derive the asymptotic null distribution of the p-values for subsampling and the moving block bootstrap, and further propose a calibration of the traditional small-b based confidence intervals (regions, bands) and tests. Our treatment is fairly general as it includes both ...
Ali, Nur Soffiah Sahubar; Ramli, Ahmad; Rahman, Nuzlinda Abdul
2017-08-01
In Radial Basis Function (RBF), user can define a parameter value,c which adjust the shape and smoothness of a data fitting. A larger parameter values increases the training error and may lead to unpleasant result. Therefore, relying on training error and visual evaluation may be difficult in some cases. Bootstrap estimation method on 2 dimensional data is applied for RBF. Simulated data points are generated with some added noise. In this paper, training error and bootstrap error for various parameter values on selected data is evaluated. Using different parameter value, we compute bootstrap error for the RBF fitting. Bootstrap error gives the optimum parameter value which produces the best fit for a specific data set.
A New Regime for Studying the High Bootstrap Current Fraction Plasma
Institute of Scientific and Technical Information of China (English)
A. Isayama; Y. Kamada; K. Ushigusa; T. Fujita; T. Suzuki; X. Gao
2001-01-01
A new experimental regime has recently been studied for achieving the high fraction of the bootstrap current in the JT-60U hydrogen discharges. The high poloidal beta(βp ～ 3.61) plasma was obtained by high-power neutral beam injection heating at a very high edge safety factor (Ip = 0.3 MA, Bt = 3.65 T, qeff = 25 - 35) region, and the bootstrap current fraction (fBS) was correspondingly about 40% using the ACCOME code calculation. It was observed that there were no magnetohydrodynamic instabilities to retard the increase of the βp and fBS parameters in the new regime.
Progress toward steady-state tokamak operation exploiting the high bootstrap current fraction regime
Ren, Q. L.; Garofalo, A. M.; Gong, X. Z.; Holcomb, C. T.; Lao, L. L.; McKee, G. R.; Meneghini, O.; Staebler, G. M.; Grierson, B. A.; Qian, J. P.; Solomon, W. M.; Turnbull, A. D.; Holland, C.; Guo, W. F.; Ding, S. Y.; Pan, C. K.; Xu, G. S.; Wan, B. N.
2016-06-01
Recent DIII-D experiments have increased the normalized fusion performance of the high bootstrap current fraction tokamak regime toward reactor-relevant steady state operation. The experiments, conducted by a joint team of researchers from the DIII-D and EAST tokamaks, developed a fully noninductive scenario that could be extended on EAST to a demonstration of long pulse steady-state tokamak operation. Improved understanding of scenario stability has led to the achievement of very high values of βp and βN , despite strong internal transport barriers. Good confinement has been achieved with reduced toroidal rotation. These high βp plasmas challenge the energy transport understanding, especially in the electron energy channel. A new turbulent transport model, named TGLF-SAT1, has been developed which improves the transport prediction. Experiments extending results to long pulse on EAST, based on the physics basis developed at DIII-D, have been conducted. More investigations will be carried out on EAST with more additional auxiliary power to come online in the near term.
Niska, Christoffer
2014-01-01
Practical and instruction-based, this concise book will take you from understanding what Bootstrap is, to creating your own Bootstrap theme in no time! If you are an intermediate front-end developer or designer who wants to learn the secrets of Bootstrap, this book is perfect for you.
A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement.
Zhou, Haijun; Yang, Wenhai; Li, Zhixiu; Li, Xuefeng; Zheng, Yaohui
2014-01-01
We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO4 laser at 1064 nm with coherent output. The measured shot noise of 50 μW laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearities for both DC and AC amplifications in the laser power range between 12.5 μW and 1.52 mW.
A bootstrapped, low-noise, and high-gain photodetector for shot noise measurement
Energy Technology Data Exchange (ETDEWEB)
Zhou, Haijun; Yang, Wenhai; Li, Zhixiu; Li, Xuefeng; Zheng, Yaohui, E-mail: yhzheng@sxu.edu.cn [State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 (China)
2014-01-15
We presented a low-noise, high-gain photodetector based on the bootstrap structure and the L-C (inductance and capacitance) combination. Electronic characteristics of the photodetector, including electronic noise, gain and frequency response, and dynamic range, were verified through a single-frequency Nd:YVO{sub 4} laser at 1064 nm with coherent output. The measured shot noise of 50 μW laser was 13 dB above the electronic noise at the analysis frequency of 2 MHz, and 10 dB at 3 MHz. And a maximum clearance of 28 dB at 2 MHz was achieved when 1.52 mW laser was illuminated. In addition, the photodetector showed excellent linearities for both DC and AC amplifications in the laser power range between 12.5 μW and 1.52 mW.
Bhaumik, Snig
2015-01-01
If you are a web developer who designs and develops websites and pages using HTML, CSS, and JavaScript, but have very little familiarity with Bootstrap, this is the book for you. Previous experience with HTML, CSS, and JavaScript will be helpful, while knowledge of jQuery would be an extra advantage.
The use of the bootstrap in the analysis of case-control studies with missing data
DEFF Research Database (Denmark)
Siersma, Volkert Dirk; Johansen, Christoffer
2004-01-01
nonparametric bootstrap, bootstrap confidence intervals, missing values, multiple imputation, matched case-control study......nonparametric bootstrap, bootstrap confidence intervals, missing values, multiple imputation, matched case-control study...
High Bootstrap Current Fraction during the Synergy of LHCD and IBW on the HT-7 Tokamak
Institute of Scientific and Technical Information of China (English)
ZHANG Xian-Mei; WAN Bao-Nian; WU Zhen-Wei; HT-7 Team
2005-01-01
@@ More than 70% of the total plasma current is sustained by the bootstrap current and current drive during the synergy of lower hybrid current driving (LHCD) and ion Berstein wave (IBW) heating on the HT-7 tokamak.The lower hybrid non-inductive current source is off-axis and well localized, and more than 35% bootstrap current plasma has been obtained. The IBW in controlling electron pressure profile can be integrated into the LHCD target plasma. The largest steep gradient of the electron pressure profile in the region ρ～ 0.5-0.7 mostly comes from the electron temperature profile, which may induce the large fraction bootstrap current. The large off-axis bootstrap current can help to create negative magnetic shear, and the good plasma confinement is achieved.
On the Model-Based Bootstrap with Missing Data: Obtaining a "P"-Value for a Test of Exact Fit
Savalei, Victoria; Yuan, Ke-Hai
2009-01-01
Evaluating the fit of a structural equation model via bootstrap requires a transformation of the data so that the null hypothesis holds exactly in the sample. For complete data, such a transformation was proposed by Beran and Srivastava (1985) for general covariance structure models and applied to structural equation modeling by Bollen and Stine…
The Local Fractional Bootstrap
DEFF Research Database (Denmark)
Bennedsen, Mikkel; Hounyo, Ulrich; Lunde, Asger;
We introduce a bootstrap procedure for high-frequency statistics of Brownian semistationary processes. More specifically, we focus on a hypothesis test on the roughness of sample paths of Brownian semistationary processes, which uses an estimator based on a ratio of realized power variations. Our...... to two empirical data sets: we assess the roughness of a time series of high-frequency asset prices and we test the validity of Kolmogorov's scaling law in atmospheric turbulence data.......We introduce a bootstrap procedure for high-frequency statistics of Brownian semistationary processes. More specifically, we focus on a hypothesis test on the roughness of sample paths of Brownian semistationary processes, which uses an estimator based on a ratio of realized power variations. Our...... and in simulations we observe that the bootstrap-based hypothesis test provides considerable finite-sample improvements over an existing test that is based on a central limit theorem. This is important when studying the roughness properties of time series data; we illustrate this by applying the bootstrap method...
Magno, Alexandre
2013-01-01
A practical, step-by-step tutorial on developing websites for mobile using Bootstrap.This book is for anyone who wants to get acquainted with the new features available in Bootstrap 3 and who wants to develop websites with the mobile-first feature of Bootstrap. The reader should have a basic knowledge of Bootstrap as a frontend framework.
Energy Technology Data Exchange (ETDEWEB)
Miller, Douglas J.; Chang, Ching-Feng; Lewis, Irwin C.; Lewis, Richard T.
2014-06-10
A high coking value pitch prepared from coal tar distillate and has a low softening point and a high carbon value while containing substantially no quinoline insolubles is disclosed. The pitch can be used as an impregnant or binder for producing carbon and graphite articles.
Kuznetsov, I A; Kuznetsov, A V
2017-05-01
In this paper, we first develop a model of axonal transport of tubulin-associated unit (tau) protein. We determine the minimum number of parameters necessary to reproduce published experimental results, reducing the number of parameters from 18 in the full model to eight in the simplified model. We then address the following questions: Is it possible to estimate parameter values for this model using the very limited amount of published experimental data? Furthermore, is it possible to estimate confidence intervals for the determined parameters? The idea that is explored in this paper is based on using bootstrapping. Model parameters were estimated by minimizing the objective function that simulates the discrepancy between the model predictions and experimental data. Residuals were then identified by calculating the differences between the experimental data and model predictions. New, surrogate 'experimental' data were generated by randomly resampling residuals. By finding sets of best-fit parameters for a large number of surrogate data the histograms for the model parameters were produced. These histograms were then used to estimate confidence intervals for the model parameters, by using the percentile bootstrap. Once the model was calibrated, we applied it to analysing some features of tau transport that are not accessible to current experimental techniques.
Kiselev, V V
2012-01-01
A huge value of cosmological constant characteristic for the particle physics and the inflation of early Universe are inherently related to each other: one can construct a fine-tuned superpotential, which produces a flat potential of inflaton with a constant density of energy V=\\Lambda^4 after taking into account for leading effects due to the supergravity, so that an introduction of small quantum loop-corrections to parameters of this superpotential naturally results in the dynamical instability relaxing the primary cosmological constant by means of inflationary regime. The model phenomenologically agrees with observational data on the large scale structure of Universe at \\Lambda~10^{16} GeV.
Shimada, Hirohiko; Hikami, Shinobu
2016-12-01
The fractal dimensions of polymer chains and high-temperature graphs in the Ising model both in three dimension are determined using the conformal bootstrap applied for the continuation of the O( N) models from N=1 (Ising model) to N=0 (polymer). Even for non-integer N, the O( N) sum rule allows one to study the unitarity bound formally defined from the positivity, which may be violated in a non-unitary CFT. This unitarity bound of the scaling dimension for the O( N)-symmetric-tensor develops a kink as a function of the fundamental field as in the case of the energy operator dimension in the Z_2 (Ising) sum rule. Although this kink structure becomes less pronounced as N tends to zero, we found instead an emerging asymmetric minimum in the current central charge C_J. Despite the non-unitarity of the O( N) model at non-integer N, we find the C_J-kink along the unitarity bound lies very close to the location of the infrared (IR) O( N) CFT estimated by other methods. It is pointed out that certain level degeneracies at the IR CFT should induce these singular shapes of the unitarity bounds. As an application to the quantum and classical spin systems, we also predict critical exponents associated with the N=1 supersymmetry, which could be relevant for locating the corresponding fixed point in the phase diagram.
Echeverri, Alejandro Castedo; von Harling, Benedict; Serone, Marco
2016-09-01
We study the numerical bounds obtained using a conformal-bootstrap method — advocated in ref. [1] but never implemented so far — where different points in the plane of conformal cross ratios z and overline{z} are sampled. In contrast to the most used method based on derivatives evaluated at the symmetric point z=overline{z}=1/2 , we can consistently "integrate out" higher-dimensional operators and get a reduced simpler, and faster to solve, set of bootstrap equations. We test this "effective" bootstrap by studying the 3D Ising and O( n) vector models and bounds on generic 4D CFTs, for which extensive results are already available in the literature. We also determine the scaling dimensions of certain scalar operators in the O( n) vector models, with n = 2, 3, 4, which have not yet been computed using bootstrap techniques.
Echeverri, Alejandro Castedo; Serone, Marco
2016-01-01
We study the numerical bounds obtained using a conformal-bootstrap method - advocated in ref. [1] but never implemented so far - where different points in the plane of conformal cross ratios $z$ and $\\bar z$ are sampled. In contrast to the most used method based on derivatives evaluated at the symmetric point $z=\\bar z =1/2$, we can consistently "integrate out" higher-dimensional operators and get a reduced simpler, and faster to solve, set of bootstrap equations. We test this "effective" bootstrap by studying the 3D Ising and $O(n)$ vector models and bounds on generic 4D CFTs, for which extensive results are already available in the literature. We also determine the scaling dimensions of certain scalar operators in the $O(n)$ vector models, with $n=2,3,4$, which have not yet been computed using bootstrap techniques.
Pronunciation modelling and bootstrapping
CSIR Research Space (South Africa)
Davel, MH
2005-08-01
Full Text Available and Sepedi) and demonstrate the utility of these dictionaries by incorporating them in speech technology systems. Keywords: bootstrapping, grapheme-to-phoneme conversion, grapheme-to-phoneme alignment, letter-to-sound, pronunciation modelling... ONE INTRODUCTION 1.3 PRONUNCIATION MODELLING WITHIN A BOOTSTRAPPING FRAMEWORK A pronunciation model for a specific language describes the process of letter-to-sound conversion: given the orthography of a word, it provides a prediction...
Dynamics of bootstrap percolation
Indian Academy of Sciences (India)
Prabodh Shukla
2008-08-01
Bootstrap percolation transition may be first order or second order, or it may have a mixed character where a first-order drop in the order parameter is preceded by critical fluctuations. Recent studies have indicated that the mixed transition is characterized by power-law avalanches, while the continuous transition is characterized by truncated avalanches in a related sequential bootstrap process. We explain this behaviour on the basis of an analytical and numerical study of the avalanche distributions on a Bethe lattice.
Conformal Bootstrap in Mellin Space
Gopakumar, Rajesh; Sen, Kallol; Sinha, Aninda
2016-01-01
We propose a new approach towards analytically solving for the dynamical content of Conformal Field Theories (CFTs) using the bootstrap philosophy. This combines the original bootstrap idea of Polyakov with the modern technology of the Mellin representation of CFT amplitudes. We employ exchange Witten diagrams with built in crossing symmetry as our basic building blocks rather than the conventional conformal blocks in a particular channel. Demanding consistency with the operator product expansion (OPE) implies an infinite set of constraints on operator dimensions and OPE coefficients. We illustrate the power of this method in the epsilon expansion of the Wilson-Fisher fixed point by computing operator dimensions and, strikingly, OPE coefficients to higher orders in epsilon than currently available using other analytic techniques (including Feynman diagram calculations). Our results enable us to get a somewhat better agreement of certain observables in the 3d Ising model, with the precise numerical values that...
Conformal Bootstrap in Mellin Space
Gopakumar, Rajesh; Kaviraj, Apratim; Sen, Kallol; Sinha, Aninda
2017-02-01
We propose a new approach towards analytically solving for the dynamical content of conformal field theories (CFTs) using the bootstrap philosophy. This combines the original bootstrap idea of Polyakov with the modern technology of the Mellin representation of CFT amplitudes. We employ exchange Witten diagrams with built-in crossing symmetry as our basic building blocks rather than the conventional conformal blocks in a particular channel. Demanding consistency with the operator product expansion (OPE) implies an infinite set of constraints on operator dimensions and OPE coefficients. We illustrate the power of this method in the ɛ expansion of the Wilson-Fisher fixed point by reproducing anomalous dimensions and, strikingly, obtaining OPE coefficients to higher orders in ɛ than currently available using other analytic techniques (including Feynman diagram calculations). Our results enable us to get a somewhat better agreement between certain observables in the 3D Ising model and the precise numerical values that have been recently obtained.
A comparison of four different block bootstrap methods
Directory of Open Access Journals (Sweden)
Boris Radovanov
2014-12-01
Full Text Available The paper contains a description of four different block bootstrap methods, i.e., non-overlapping block bootstrap, overlapping block bootstrap (moving block bootstrap, stationary block bootstrap and subsampling. Furthermore, the basic goal of this paper is to quantify relative efficiency of each mentioned block bootstrap procedure and then to compare those methods. To achieve the goal, we measure mean square errors of estimation variance returns. The returns are calculated from 1250 daily observations of Serbian stock market index values BELEX15 from April 2009 to April 2014. Thereby, considering the effects of potential changes in decisions according to variations in the sample length and purposes of the use, this paper introduces stability analysis which contains robustness testing of the different sample size and the different block length. Testing results indicate some changes in bootstrap method efficiencies when altering the sample size or the block length.
Bootstrap Dynamical Symmetry Breaking
Directory of Open Access Journals (Sweden)
Wei-Shu Hou
2013-01-01
Full Text Available Despite the emergence of a 125 GeV Higgs-like particle at the LHC, we explore the possibility of dynamical electroweak symmetry breaking by strong Yukawa coupling of very heavy new chiral quarks Q . Taking the 125 GeV object to be a dilaton with suppressed couplings, we note that the Goldstone bosons G exist as longitudinal modes V L of the weak bosons and would couple to Q with Yukawa coupling λ Q . With m Q ≳ 700 GeV from LHC, the strong λ Q ≳ 4 could lead to deeply bound Q Q ¯ states. We postulate that the leading “collapsed state,” the color-singlet (heavy isotriplet, pseudoscalar Q Q ¯ meson π 1 , is G itself, and a gap equation without Higgs is constructed. Dynamical symmetry breaking is affected via strong λ Q , generating m Q while self-consistently justifying treating G as massless in the loop, hence, “bootstrap,” Solving such a gap equation, we find that m Q should be several TeV, or λ Q ≳ 4 π , and would become much heavier if there is a light Higgs boson. For such heavy chiral quarks, we find analogy with the π − N system, by which we conjecture the possible annihilation phenomena of Q Q ¯ → n V L with high multiplicity, the search of which might be aided by Yukawa-bound Q Q ¯ resonances.
Forecasting Value-at-Risk Using High-Frequency Information
Directory of Open Access Journals (Sweden)
Huiyu Huang
2013-06-01
Full Text Available in the prediction of quantiles of daily Standard&Poor’s 500 (S&P 500 returns we consider how to use high-frequency 5-minute data. We examine methods that incorporate the high frequency information either indirectly, through combining forecasts (using forecasts generated from returns sampled at different intraday interval, or directly, through combining high frequency information into one model. We consider subsample averaging, bootstrap averaging, forecast averaging methods for the indirect case, and factor models with principal component approach, for both direct and indirect cases. We show that in forecasting the daily S&P 500 index return quantile (Value-at-Risk or VaR is simply the negative of it, using high-frequency information is beneficial, often substantially and particularly so, in forecasting downside risk. Our empirical results show that the averaging methods (subsample averaging, bootstrap averaging, forecast averaging, which serve as different ways of forming the ensemble average from using high-frequency intraday information, provide an excellent forecasting performance compared to using just low-frequency daily information.
Rejon-Barrera, Fernando
2015-01-01
We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.
Energy Technology Data Exchange (ETDEWEB)
Rejon-Barrera, Fernando [Institute for Theoretical Physics, University of Amsterdam,Science Park 904, Postbus 94485, 1090 GL, Amsterdam (Netherlands); Robbins, Daniel [Department of Physics, Texas A& M University,TAMU 4242, College Station, TX 77843 (United States)
2016-01-22
We work out all of the details required for implementation of the conformal bootstrap program applied to the four-point function of two scalars and two vectors in an abstract conformal field theory in arbitrary dimension. This includes a review of which tensor structures make appearances, a construction of the projectors onto the required mixed symmetry representations, and a computation of the conformal blocks for all possible operators which can be exchanged. These blocks are presented as differential operators acting upon the previously known scalar conformal blocks. Finally, we set up the bootstrap equations which implement crossing symmetry. Special attention is given to the case of conserved vectors, where several simplifications occur.
Bootstrap percolation on spatial networks
Gao, Jian; Zhou, Tao; Hu, Yanqing
2015-10-01
Bootstrap percolation is a general representation of some networked activation process, which has found applications in explaining many important social phenomena, such as the propagation of information. Inspired by some recent findings on spatial structure of online social networks, here we study bootstrap percolation on undirected spatial networks, with the probability density function of long-range links’ lengths being a power law with tunable exponent. Setting the size of the giant active component as the order parameter, we find a parameter-dependent critical value for the power-law exponent, above which there is a double phase transition, mixed of a second-order phase transition and a hybrid phase transition with two varying critical points, otherwise there is only a second-order phase transition. We further find a parameter-independent critical value around -1, about which the two critical points for the double phase transition are almost constant. To our surprise, this critical value -1 is just equal or very close to the values of many real online social networks, including LiveJournal, HP Labs email network, Belgian mobile phone network, etc. This work helps us in better understanding the self-organization of spatial structure of online social networks, in terms of the effective function for information spreading.
Bootstrapping language acquisition.
Abend, Omri; Kwiatkowski, Tom; Smith, Nathaniel J; Goldwater, Sharon; Steedman, Mark
2017-07-01
The semantic bootstrapping hypothesis proposes that children acquire their native language through exposure to sentences of the language paired with structured representations of their meaning, whose component substructures can be associated with words and syntactic structures used to express these concepts. The child's task is then to learn a language-specific grammar and lexicon based on (probably contextually ambiguous, possibly somewhat noisy) pairs of sentences and their meaning representations (logical forms). Starting from these assumptions, we develop a Bayesian probabilistic account of semantically bootstrapped first-language acquisition in the child, based on techniques from computational parsing and interpretation of unrestricted text. Our learner jointly models (a) word learning: the mapping between components of the given sentential meaning and lexical words (or phrases) of the language, and (b) syntax learning: the projection of lexical elements onto sentences by universal construction-free syntactic rules. Using an incremental learning algorithm, we apply the model to a dataset of real syntactically complex child-directed utterances and (pseudo) logical forms, the latter including contextually plausible but irrelevant distractors. Taking the Eve section of the CHILDES corpus as input, the model simulates several well-documented phenomena from the developmental literature. In particular, the model exhibits syntactic bootstrapping effects (in which previously learned constructions facilitate the learning of novel words), sudden jumps in learning without explicit parameter setting, acceleration of word-learning (the "vocabulary spurt"), an initial bias favoring the learning of nouns over verbs, and one-shot learning of words and their meanings. The learner thus demonstrates how statistical learning over structured representations can provide a unified account for these seemingly disparate phenomena. Copyright © 2017 Elsevier B.V. All rights reserved.
Statistical bootstrap model and annihilations
Möhring, H J
1974-01-01
The statistical bootstrap model (SBM) describes the decay of single, high mass, hadronic states (fireballs, clusters) into stable particles. Coupling constants B, one for each isospin multiplet of stable particles, are the only free parameter of the model. They are related to the maximum temperature parameter T/sub 0/. The various versions of the SMB can be classified into two groups: full statistical bootstrap models and linear ones. The main results of the model are the following: i) All momentum spectra are isotropic; especially the exclusive ones are described by invariant phase space. The inclusive and semi-inclusive single-particle distributions are asymptotically of pure exponential shape; the slope is governed by T /sub 0/ only. ii) The model parameter B for pions has been obtained by fitting the multiplicity distribution in pp and pn at rest, and corresponds to T/sub 0/=0.167 GeV in the full SBM with exotics. The average pi /sup -/ multiplicity for the linear and the full SBM (both with exotics) is c...
Alfaro, Michael E; Zoller, Stefan; Lutzoni, François
2003-02-01
Bayesian Markov chain Monte Carlo sampling has become increasingly popular in phylogenetics as a method for both estimating the maximum likelihood topology and for assessing nodal confidence. Despite the growing use of posterior probabilities, the relationship between the Bayesian measure of confidence and the most commonly used confidence measure in phylogenetics, the nonparametric bootstrap proportion, is poorly understood. We used computer simulation to investigate the behavior of three phylogenetic confidence methods: Bayesian posterior probabilities calculated via Markov chain Monte Carlo sampling (BMCMC-PP), maximum likelihood bootstrap proportion (ML-BP), and maximum parsimony bootstrap proportion (MP-BP). We simulated the evolution of DNA sequence on 17-taxon topologies under 18 evolutionary scenarios and examined the performance of these methods in assigning confidence to correct monophyletic and incorrect monophyletic groups, and we examined the effects of increasing character number on support value. BMCMC-PP and ML-BP were often strongly correlated with one another but could provide substantially different estimates of support on short internodes. In contrast, BMCMC-PP correlated poorly with MP-BP across most of the simulation conditions that we examined. For a given threshold value, more correct monophyletic groups were supported by BMCMC-PP than by either ML-BP or MP-BP. When threshold values were chosen that fixed the rate of accepting incorrect monophyletic relationship as true at 5%, all three methods recovered most of the correct relationships on the simulated topologies, although BMCMC-PP and ML-BP performed better than MP-BP. BMCMC-PP was usually a less biased predictor of phylogenetic accuracy than either bootstrapping method. BMCMC-PP provided high support values for correct topological bipartitions with fewer characters than was needed for nonparametric bootstrap.
Ultrafast Approximation for Phylogenetic Bootstrap
Bui Quang Minh, [No Value; Nguyen, Thi; von Haeseler, Arndt
2013-01-01
Nonparametric bootstrap has been a widely used tool in phylogenetic analysis to assess the clade support of phylogenetic trees. However, with the rapidly growing amount of data, this task remains a computational bottleneck. Recently, approximation methods such as the RAxML rapid bootstrap (RBS) and
Collier, Scott; Yin, Xi
2016-01-01
We constrain the spectrum of two-dimensional unitary, compact conformal field theories with central charge c > 1 using modular bootstrap. Upper bounds on the gap in the dimension of primary operators of any spin, as well as in the dimension of scalar primaries, are computed numerically as functions of the central charge using semi-definite programming. Our bounds refine those of Hellerman and Friedan-Keller, and are in some cases saturated by known CFTs. In particular, we show that unitary CFTs with c < 8 must admit relevant deformations, and that a nontrivial bound on the gap of scalar primaries exists for c < 25. We also study bounds on the dimension gap in the presence of twist gaps, bounds on the degeneracy of operators, and demonstrate how "extremal spectra" which maximize the degeneracy at the gap can be determined numerically.
Bootstrapping quarks and gluons
Energy Technology Data Exchange (ETDEWEB)
Chew, G.F.
1979-04-01
Dual topological unitarization (DTU) - the approach to S-matrix causality and unitarity through combinatorial topology - is reviewed. Amplitudes associated with triangulated spheres are shown to constitute the core of particle physics. Each sphere is covered by triangulated disc faces corresponding to hadrons. The leading current candidate for the hadron-face triangulation pattern employs 3-triangle basic subdiscs whose orientations correspond to baryon number and topological color. Additional peripheral triangles lie along the hadron-face perimeter. Certain combinations of peripheral triangles with a basic-disc triangle can be identified as quarks, the flavor of a quark corresponding to the orientation of its edges that lie on the hadron-face perimeter. Both baryon number and flavor are additively conserved. Quark helicity, which can be associated with triangle-interior orientation, is not uniformly conserved and interacts with particle momentum, whereas flavor does not. Three different colors attach to the 3 quarks associated with a single basic subdisc, but there is no additive physical conservation law associated with color. There is interplay between color and quark helicity. In hadron faces with more than one basic subdisc, there may occur pairs of adjacent flavorless but colored triangles with net helicity +-1 that are identifiable as gluons. Broken symmetry is an automatic feature of the bootstrap. T, C and P symmetries, as well as up-down flavor symmetry, persist on all orientable surfaces.
Bootstrapping phylogenies inferred from rearrangement data
Directory of Open Access Journals (Sweden)
Lin Yu
2012-08-01
Full Text Available Abstract Background Large-scale sequencing of genomes has enabled the inference of phylogenies based on the evolution of genomic architecture, under such events as rearrangements, duplications, and losses. Many evolutionary models and associated algorithms have been designed over the last few years and have found use in comparative genomics and phylogenetic inference. However, the assessment of phylogenies built from such data has not been properly addressed to date. The standard method used in sequence-based phylogenetic inference is the bootstrap, but it relies on a large number of homologous characters that can be resampled; yet in the case of rearrangements, the entire genome is a single character. Alternatives such as the jackknife suffer from the same problem, while likelihood tests cannot be applied in the absence of well established probabilistic models. Results We present a new approach to the assessment of distance-based phylogenetic inference from whole-genome data; our approach combines features of the jackknife and the bootstrap and remains nonparametric. For each feature of our method, we give an equivalent feature in the sequence-based framework; we also present the results of extensive experimental testing, in both sequence-based and genome-based frameworks. Through the feature-by-feature comparison and the experimental results, we show that our bootstrapping approach is on par with the classic phylogenetic bootstrap used in sequence-based reconstruction, and we establish the clear superiority of the classic bootstrap for sequence data and of our corresponding new approach for rearrangement data over proposed variants. Finally, we test our approach on a small dataset of mammalian genomes, verifying that the support values match current thinking about the respective branches. Conclusions Our method is the first to provide a standard of assessment to match that of the classic phylogenetic bootstrap for aligned sequences. Its
A Bootstrap Approach to an Affordable Exploration Program
Oeftering, Richard C.
2011-01-01
This paper examines the potential to build an affordable sustainable exploration program by adopting an approach that requires investing in technologies that can be used to build a space infrastructure from very modest initial capabilities. Human exploration has had a history of flight programs that have high development and operational costs. Since Apollo, human exploration has had very constrained budgets and they are expected be constrained in the future. Due to their high operations costs it becomes necessary to consider retiring established space facilities in order to move on to the next exploration challenge. This practice may save cost in the near term but it does so by sacrificing part of the program s future architecture. Human exploration also has a history of sacrificing fully functional flight hardware to achieve mission objectives. An affordable exploration program cannot be built when it involves billions of dollars of discarded space flight hardware, instead, the program must emphasize preserving its high value space assets and building a suitable permanent infrastructure. Further this infrastructure must reduce operational and logistics cost. The paper examines the importance of achieving a high level of logistics independence by minimizing resource consumption, minimizing the dependency on external logistics, and maximizing the utility of resources available. The approach involves the development and deployment of a core suite of technologies that have minimum initial needs yet are able expand upon initial capability in an incremental bootstrap fashion. The bootstrap approach incrementally creates an infrastructure that grows and becomes self sustaining and eventually begins producing the energy, products and consumable propellants that support human exploration. The bootstrap technologies involve new methods of delivering and manipulating energy and materials. These technologies will exploit the space environment, minimize dependencies, and
Bootstrapping quality of Web Services
Directory of Open Access Journals (Sweden)
Zainab Aljazzaf
2015-07-01
Full Text Available A distributed application may be composed of global services provided by different organizations and having different properties. To select a service from many similar services, it is important to distinguish between them. Quality of services (QoS has been used as a distinguishing factor between similar services and plays an important role in service discovery, selection, and composition. Moreover, QoS is an important contributing factor to the evolution of distributed paradigms, such as service-oriented computing and cloud computing. There are many research works that assess services and justify the QoS at the finding, composition, or binding stages of services. However, there is a need to justify the QoS once new services are registered and before any requestors use them; this is called bootstrapping QoS. Bootstrapping QoS is the process of evaluating the QoS of the newly registered services at the time of publishing the services. Thus, this paper proposes a QoS bootstrapping solution for Web Services and builds a QoS bootstrapping framework. In addition, Service Oriented Architecture (SOA is extended and a prototype is built to support QoS bootstrapping. Experiments are conducted and a case study is presented to test the proposed QoS bootstrapping solution.
Extremal bootstrapping: go with the flow
El-Showk, Sheer
2016-01-01
The extremal functional method determines approximate solutions to the constraints of crossing symmetry, which saturate bounds on the space of unitary CFTs. We show that such solutions are characterized by extremality conditions, which may be used to flow continuously along the boundaries of parameter space. Along the flow there is generically no further need for optimization, which dramatically reduces computational requirements, bringing calculations from the realm of computing clusters to laptops. Conceptually, extremality sheds light on possible ways to bootstrap without positivity, extending the method to non-unitary theories, and implies that theories saturating bounds, and especially those sitting at kinks, have unusually sparse spectra. We discuss several applications, including the first high-precision bootstrap of a non-unitary CFT.
The bootstrap in bioequivalence studies.
Pigeot, Iris; Hauschke, Dieter; Shao, Jun
2011-11-01
In 1997, the U.S. Food and Drug Administration (FDA) suggested in its draft guidance the use of new concepts for assessing the bioequivalence of two drug formulations, namely, the concepts of population and individual bioequivalence. Aggregate moment-based and probability-based measures of bioequivalence were introduced to derive criteria in order to decide whether two formulations should be regarded as bioequivalent or not. The statistical decision may be made via a nonparametric bootstrap percentile interval. In this article, we review the history of population and individual bioequivalence with special focus on the role of the bootstrap in this context.
The wild tapered block bootstrap
DEFF Research Database (Denmark)
Hounyo, Ulrich
In this paper, a new resampling procedure, called the wild tapered block bootstrap, is introduced as a means of calculating standard errors of estimators and constructing confidence regions for parameters based on dependent heterogeneous data. The method consists in tapering each overlapping block...
Control of bootstrap current in the pedestal region of tokamaks
Energy Technology Data Exchange (ETDEWEB)
Shaing, K. C. [Institute for Space and Plasma Sciences, National Cheng Kung University, Tainan City 70101, Taiwan (China); Department of Engineering Physics, University of Wisconsin, Madison, Wisconsin 53796 (United States); Lai, A. L. [Institute for Space and Plasma Sciences, National Cheng Kung University, Tainan City 70101, Taiwan (China)
2013-12-15
The high confinement mode (H-mode) plasmas in the pedestal region of tokamaks are characterized by steep gradient of the radial electric field, and sonic poloidal U{sub p,m} flow that consists of poloidal components of the E×B flow and the plasma flow velocity that is parallel to the magnetic field B. Here, E is the electric field. The bootstrap current that is important for the equilibrium, and stability of the pedestal of H-mode plasmas is shown to have an expression different from that in the conventional theory. In the limit where ‖U{sub p,m}‖≫ 1, the bootstrap current is driven by the electron temperature gradient and inductive electric field fundamentally different from that in the conventional theory. The bootstrap current in the pedestal region can be controlled through manipulating U{sub p,m} and the gradient of the radial electric. This, in turn, can control plasma stability such as edge-localized modes. Quantitative evaluations of various coefficients are shown to illustrate that the bootstrap current remains finite when ‖U{sub p,m}‖ approaches infinite and to provide indications how to control the bootstrap current. Approximate analytic expressions for viscous coefficients that join results in the banana and plateau-Pfirsch-Schluter regimes are presented to facilitate bootstrap and neoclassical transport simulations in the pedestal region.
Coefficient Omega Bootstrap Confidence Intervals: Nonnormal Distributions
Padilla, Miguel A.; Divers, Jasmin
2013-01-01
The performance of the normal theory bootstrap (NTB), the percentile bootstrap (PB), and the bias-corrected and accelerated (BCa) bootstrap confidence intervals (CIs) for coefficient omega was assessed through a Monte Carlo simulation under conditions not previously investigated. Of particular interests were nonnormal Likert-type and binary items.…
Bootstrapping the QCD soft anomalous dimension arXiv
Almelid, Øyvind; Gardi, Einan; McLeod, Andrew; White, Chris D.
The soft anomalous dimension governs the infrared singularities of scattering amplitudes to all orders in perturbative quantum field theory, and is a crucial ingredient in both formal and phenomenological applications of non-abelian gauge theories. It has recently been computed at three-loop order for massless partons by explicit evaluation of all relevant Feynman diagrams. In this paper, we show how the same result can be obtained, up to an overall numerical factor, using a bootstrap procedure. We first give a geometrical argument for the fact that the result can be expressed in terms of single-valued harmonic polylogarithms. We then use symmetry considerations as well as known properties of scattering amplitudes in collinear and high-energy (Regge) limits to constrain an ansatz of basis functions. This is a highly non-trivial cross-check of the result, and our methods pave the way for greatly simplified higher-order calculations.
Stable bootstrap-current driven equilibria for low aspect ratio tokamaks
Energy Technology Data Exchange (ETDEWEB)
Miller, R.L.; Lin-Liu, Y.R.; Turnbull, A.D.; Chan, V.S. [General Atomics, San Diego, CA (United States); Pearlstein, L.D. [Lawrence Livermore National Lab., CA (United States); Sauter, O.; Villard, L. [Ecole Polytechnique Federale, Lausanne (Switzerland). Centre de Recherche en Physique des Plasma (CRPP)
1996-09-01
Low aspect ratio tokamaks can potentially provide a high ratio of plasma pressure to magnetic pressure {beta} and high plasma current I at a modest size, ultimately leading to a high power density compact fusion power plant. For the concept to be economically feasible, bootstrap current must be a major component of the plasma. A high value of the Troyon factor {beta}{sub N} and strong shaping are required to allow simultaneous operation at high {beta} and high bootstrap current fraction. Ideal magnetohydrodynamic stability of a range of equilibria at aspect 1.4 is systematically explored by varying the pressure profile and shape. The pressure and current profiles are constrained in such a way as to assure complete bootstrap current alignment. Both {beta}{sub N} and {beta} are defined in terms of the vacuum toroidal field. Equilibria with {beta} {sub N}{>=}8 and {beta} {approx_equal}35% to 55% exist which are stable to n = {infinity} ballooning modes, and stable to n = 0,1,2,3 kink modes with a conducting wall. The dependence of {beta} and {beta}{sub N} with respect to aspect ratio is also considered. (author) 9 figs., 14 refs.
Bootstrap Current in Spherical Tokamaks
Institute of Scientific and Technical Information of China (English)
王中天; 王龙
2003-01-01
Variational principle for the neoclassical theory has been developed by including amomentum restoring term in the electron-electron collisional operator, which gives an additionalfree parameter maximizing the heat production rate. All transport coefficients are obtained in-cluding the bootstrap current. The essential feature of the study is that the aspect ratio affects thefunction of the electron-electron collision operator through a geometrical factor. When the aspectratio approaches to unity, the fraction of circulating particles goes to zero and the contribution toparticle flux from the electron-electron collision vanishes. The resulting diffusion coefficient is inrough agreement with Hazeltine. When the aspect ratio approaches to infinity, the results are inagreement with Rosenbluth. The formalism gives the two extreme cases a connection. The theoryis particularly important for the calculation of bootstrap current in spherical tokamaks and thepresent tokamaks, in which the square root of the inverse aspect ratio, in general, is not small.
Energy Technology Data Exchange (ETDEWEB)
Blandford, Roger; Funk, Stefan; /KIPAC, Menlo Park
2007-10-10
Recent observations with TeV telescopes strongly indicate that young supernova remnants are capable of accelerating cosmic ray protons almost to PeV energies. On quite general grounds, this, in turn, suggests that the magnetic field strength must be enhanced above the standard interstellar value by about two orders of magnitude. It is suggested that protons and electrons are accelerated through diffusive shock acceleration, with the highest energy protons streaming furthest ahead of the shock front. It is then shown that the pressure of the {approx} 300TeV protons dominates that of the ambient thermal particles and magnetic field and is likely to be sufficiently anisotropic to render the pre-shock fluid unstable to resonant and non-resonant instability. A new theory of the non-resonant instabilities is outlined. The nonlinear evolution of these instabilities requires careful numerical simulation but it is conjectured that the magnetic field is amplified in this location and provides the means for efficient acceleration of progressively lower energy particles as it is convected towards the subshock in the thermal plasma. Further possible implications of these ideas are sketched.
Bootstrapping in language resource generation
CSIR Research Space (South Africa)
Davel, MH
2003-11-01
Full Text Available stream_source_info Davel_2003.pdf.txt stream_content_type text/plain stream_size 19070 Content-Encoding ISO-8859-1 stream_name Davel_2003.pdf.txt Content-Type text/plain; charset=ISO-8859-1 Bootstrapping in Language... window version of DEC (DEC-win) outperforms1 this version of DEC (DEC-grow) consistently, as illustrated in Figures 3 and 4. 20 30 40 50 60 70 80 90 100 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 Accuracy...
Microalgae biorefinery: High value products perspectives.
Chew, Kit Wayne; Yap, Jing Ying; Show, Pau Loke; Suan, Ng Hui; Juan, Joon Ching; Ling, Tau Chuan; Lee, Duu-Jong; Chang, Jo-Shu
2017-04-01
Microalgae have received much interest as a biofuel feedstock in response to the uprising energy crisis, climate change and depletion of natural sources. Development of microalgal biofuels from microalgae does not satisfy the economic feasibility of overwhelming capital investments and operations. Hence, high-value co-products have been produced through the extraction of a fraction of algae to improve the economics of a microalgae biorefinery. Examples of these high-value products are pigments, proteins, lipids, carbohydrates, vitamins and anti-oxidants, with applications in cosmetics, nutritional and pharmaceuticals industries. To promote the sustainability of this process, an innovative microalgae biorefinery structure is implemented through the production of multiple products in the form of high value products and biofuel. This review presents the current challenges in the extraction of high value products from microalgae and its integration in the biorefinery. The economic potential assessment of microalgae biorefinery was evaluated to highlight the feasibility of the process.
Efficient bootstrap with weakly dependent processes
Bravo, Francesco; Crudu, Federico
2012-01-01
The efficient bootstrap methodology is developed for overidentified moment conditions models with weakly dependent observation. The resulting bootstrap procedure is shown to be asymptotically valid and can be used to approximate the distributions of t-statistics, the J-statistic for overidentifying
Efficient bootstrap with weakly dependent processes
Bravo, Francesco; Crudu, Federico
2012-01-01
The efficient bootstrap methodology is developed for overidentified moment conditions models with weakly dependent observation. The resulting bootstrap procedure is shown to be asymptotically valid and can be used to approximate the distributions of t-statistics, the J-statistic for overidentifying
Statistical Analysis of Random Simulations : Bootstrap Tutorial
Deflandre, D.; Kleijnen, J.P.C.
2002-01-01
The bootstrap is a simple but versatile technique for the statistical analysis of random simulations.This tutorial explains the basics of that technique, and applies it to the well-known M/M/1 queuing simulation.In that numerical example, different responses are studied.For some responses, bootstrap
Bootstrapping a Semantic Lexicon on Verb Similarities
Syed, S.; Spruit, M.; Borit, M.
2016-01-01
We present a bootstrapping algorithm to create a semantic lexicon from a list of seed words and a corpus that was mined from the web. We exploit extraction patterns to bootstrap the lexicon and use collocation statistics to dynamically score new lexicon entries. Extraction patterns are subsequently
A neural network based reputation bootstrapping approach for service selection
Wu, Quanwang; Zhu, Qingsheng; Li, Peng
2015-10-01
With the concept of service-oriented computing becoming widely accepted in enterprise application integration, more and more computing resources are encapsulated as services and published online. Reputation mechanism has been studied to establish trust on prior unknown services. One of the limitations of current reputation mechanisms is that they cannot assess the reputation of newly deployed services as no record of their previous behaviours exists. Most of the current bootstrapping approaches merely assign default reputation values to newcomers. However, by this kind of methods, either newcomers or existing services will be favoured. In this paper, we present a novel reputation bootstrapping approach, where correlations between features and performance of existing services are learned through an artificial neural network (ANN) and they are then generalised to establish a tentative reputation when evaluating new and unknown services. Reputations of services published previously by the same provider are also incorporated for reputation bootstrapping if available. The proposed reputation bootstrapping approach is seamlessly embedded into an existing reputation model and implemented in the extended service-oriented architecture. Empirical studies of the proposed approach are shown at last.
Analytic bootstrap at large spin
Kaviraj, Apratim; Sinha, Aninda
2015-01-01
We use analytic conformal bootstrap methods to determine the anomalous dimensions and OPE coefficients for large spin operators in general conformal field theories in four dimensions containing a scalar operator of conformal dimension $\\Delta_\\phi$. It is known that such theories will contain an infinite sequence of large spin operators with twists approaching $2\\Delta_\\phi+2n$ for each integer $n$. By considering the case where such operators are separated by a twist gap from other operators at large spin, we analytically determine the $n$, $\\Delta_\\phi$ dependence of the anomalous dimensions. We find that for all $n$, the anomalous dimensions are negative for $\\Delta_\\phi$ satisfying the unitarity bound, thus extending the Nachtmann theorem to non-zero $n$. In the limit when $n$ is large, we find agreement with the AdS/CFT prediction corresponding to the Eikonal limit of a 2-2 scattering with dominant graviton exchange.
How to Bootstrap Anonymous Communication
DEFF Research Database (Denmark)
Jakobsen, Sune K.; Orlandi, Claudio
2015-01-01
We ask whether it is possible to anonymously communicate a large amount of data using only public (non-anonymous) communication together with a small anonymous channel. We think this is a central question in the theory of anonymous communication and to the best of our knowledge this is the first...... formal study in this direction. To solve this problem, we introduce the concept of anonymous steganography: think of a leaker Lea who wants to leak a large document to Joe the journalist. Using anonymous steganography Lea can embed this document in innocent looking communication on some popular website...... defining anonymous steganography, - A construction showing that anonymous steganography is possible (which uses recent results in circuits obfuscation), - A lower bound on the number of bits which are needed to bootstrap anonymous communication....
How to Bootstrap Anonymous Communication
DEFF Research Database (Denmark)
Jakobsen, Sune K.; Orlandi, Claudio
2015-01-01
We ask whether it is possible to anonymously communicate a large amount of data using only public (non-anonymous) communication together with a small anonymous channel. We think this is a central question in the theory of anonymous communication and to the best of our knowledge this is the rst...... formal study in this direction. To solve this problem, we introduce the concept of anonymous steganography: think of a leaker Lea who wants to leak a large document to Joe the journalist. Using anonymous steganography Lea can embed this document in innocent looking communication on some popular website...... anonymous steganography, { A construction showing that anonymous steganography is possible (which uses recent results in circuits obfuscation), { A lower bound on the number of bits which are needed to bootstrap anonymous communication....
High value carbon materials from PET recycling
Parra, J. B.; Ania, C. O.; Arenillas, A.; Rubiera, F.; Pis, J. J.
2004-11-01
Poly(ethylene) terephthalate (PET), has become one of the major post-consumer plastic waste. In this work special attention was paid to minimising PET residues and to obtain a high value carbon material. Pyrolysis and subsequent activation of PET from post-consumer soft-drink bottles was performed. Activation was carried out at 925 °C under CO2 atmosphere to different burn-off degrees. Textural characterisation of the samples was carried out by performing N2 adsorption isotherms at -196 °C. The obtained carbons materials were mainly microporous, presenting low meso and macroporosity, and apparent BET surface areas of upto 2500 m2 g-1. The capacity of these materials for phenol adsorption and PAHs removal from aqueous solutions was measured and compared with that attained with commercial active carbons. Preliminary tests also showed high hydrogen uptake values, as good as the results obtained with high-tech carbon materials.
An analytical high value target acquisition model
Becker, Kevin J.
1986-01-01
Approved for public release; distribution is unlimited An Analytical High Value Target (HVT) acquisition model is developed for a generic anti-ship cruise missile system. the target set is represented as a single HVT within a field of escorts. The HVT's location is described by a bivariate normal probability distribution. the escorts are represented by a spatially homogeneous Poisson random field surrounding the HVT. Model output consists of the probability that at least one missile of...
N=1 Supersymmetric Boundary Bootstrap
Toth, G Z
2004-01-01
We investigate the boundary bootstrap programme for finding exact reflection matrices of integrable boundary quantum field theories with N=1 boundary supersymmetry. The bulk S-matrix and the reflection matrix are assumed to take the form S=S_1S_0, R=R_1R_0, where S_0 and R_0 are the S-matrix and reflection matrix of some integrable non-supersymmetric boundary theory that is assumed to be known, and S_1 and R_1 describe the mixing of supersymmetric indices. Under the assumption that the bulk particles transform in the kink and boson/fermion representations and the ground state is a singlet we present rules by which the supersymmetry representations and reflection factors for excited boundary bound states can be determined. We apply these rules to the boundary sine-Gordon model, to the boundary a_2^(1) and a_4^(1) affine Toda field theories, to the boundary sinh-Gordon model and to the free particle.
Bootstrapping and Maintaining Trust in the Cloud
2016-12-01
without being trusted computing aware. We show that our bootstrapping proto- col can derive a key in less than two seconds, we can detect system...Platform Module (TPM) [40], has long been proposed as the solution for bootstrapping trust, enabling the detection of changes to system state that might...disks. Unlike existing solutions [39, 25], these ser - vices don’t need to be trusted computing aware, they just need to use an identity key and respond
Bootstrapping realized volatility and realized beta under a local Gaussianity assumption
DEFF Research Database (Denmark)
Hounyo, Ulrich
The main contribution of this paper is to propose a new bootstrap method for statistics based on high frequency returns. The new method exploits the local Gaussianity and the local constancy of volatility of high frequency returns, two assumptions that can simplify inference in the high frequency...... simulations and use empirical data to compare the finite sample accuracy of our new bootstrap confidence intervals for integrated volatility and integrated beta with the existing results....
A bootstrap based space-time surveillance model with an application to crime occurrences
Kim, Youngho; O'Kelly, Morton
2008-06-01
This study proposes a bootstrap-based space-time surveillance model. Designed to find emerging hotspots in near-real time, the bootstrap based model is characterized by its use of past occurrence information and bootstrap permutations. Many existing space-time surveillance methods, using population at risk data to generate expected values, have resulting hotspots bounded by administrative area units and are of limited use for near-real time applications because of the population data needed. However, this study generates expected values for local hotspots from past occurrences rather than population at risk. Also, bootstrap permutations of previous occurrences are used for significant tests. Consequently, the bootstrap-based model, without the requirement of population at risk data, (1) is free from administrative area restriction, (2) enables more frequent surveillance for continuously updated registry database, and (3) is readily applicable to criminology and epidemiology surveillance. The bootstrap-based model performs better for space-time surveillance than the space-time scan statistic. This is shown by means of simulations and an application to residential crime occurrences in Columbus, OH, year 2000.
Generalised block bootstrap and its use in meteorology
Varga, László; Zempléni, András
2017-06-01
In an earlier paper, Rakonczai et al.(2014) emphasised the importance of investigating the effective sample size in case of autocorrelated data. The simulations were based on the block bootstrap methodology. However, the discreteness of the usual block size did not allow for exact calculations. In this paper we propose a new generalisation of the block bootstrap methodology, which allows for any positive real number as expected block size. We relate it to the existing optimisation procedures and apply it to a temperature data set. Our other focus is on statistical tests, where quite often the actual sample size plays an important role, even in the case of relatively large samples. This is especially the case for copulas. These are used for investigating the dependencies among data sets. As in quite a few real applications the time dependence cannot be neglected, we investigated the effect of this phenomenon on the used test statistic. The critical value can be computed by the proposed new block bootstrap simulation, where the block size is determined by fitting a VAR model to the observations. The results are illustrated for models of the used temperature data.
Stock Price Simulation Using Bootstrap and Monte Carlo
Directory of Open Access Journals (Sweden)
Pažický Martin
2017-06-01
Full Text Available In this paper, an attempt is made to assessment and comparison of bootstrap experiment and Monte Carlo experiment for stock price simulation. Since the stock price evolution in the future is extremely important for the investors, there is the attempt to find the best method how to determine the future stock price of BNP Paribas′ bank. The aim of the paper is define the value of the European and Asian option on BNP Paribas′ stock at the maturity date. There are employed four different methods for the simulation. First method is bootstrap experiment with homoscedastic error term, second method is blocked bootstrap experiment with heteroscedastic error term, third method is Monte Carlo simulation with heteroscedastic error term and the last method is Monte Carlo simulation with homoscedastic error term. In the last method there is necessary to model the volatility using econometric GARCH model. The main purpose of the paper is to compare the mentioned methods and select the most reliable. The difference between classical European option and exotic Asian option based on the experiment results is the next aim of tis paper.
On Bootstrap Tests of Symmetry About an Unknown Median.
Zheng, Tian; Gastwirth, Joseph L
2010-07-01
It is important to examine the symmetry of an underlying distribution before applying some statistical procedures to a data set. For example, in the Zuni School District case, a formula originally developed by the Department of Education trimmed 5% of the data symmetrically from each end. The validity of this procedure was questioned at the hearing by Chief Justice Roberts. Most tests of symmetry (even nonparametric ones) are not distribution free in finite sample sizes. Hence, using asymptotic distribution may not yield an accurate type I error rate or/and loss of power in small samples. Bootstrap resampling from a symmetric empirical distribution function fitted to the data is proposed to improve the accuracy of the calculated p-value of several tests of symmetry. The results show that the bootstrap method is superior to previously used approaches relying on the asymptotic distribution of the tests that assumed the data come from a normal distribution. Incorporating the bootstrap estimate in a recently proposed test due to Miao, Gel and Gastwirth (2006) preserved its level and shows it has reasonable power properties on the family of distribution evaluated.
Detection of Wideband Signal Number Based on Bootstrap Resampling
Directory of Open Access Journals (Sweden)
Jiaqi Zhen
2016-01-01
Full Text Available Knowing source number correctly is the precondition for most spatial spectrum estimation methods; however, many snapshots are needed when we determine number of wideband signals. Therefore, a new method based on Bootstrap resampling is proposed in this paper. First, signals are divided into some nonoverlapping subbands; apply coherent signal methods (CSM to focus them on the single frequency. Then, fuse the eigenvalues with the corresponding eigenvectors of the focused covariance matrix. Subsequently, use Bootstrap to construct the new resampling matrix. Finally, the number of wideband signals can be calculated with obtained vector sequences according to clustering technique. The method has a high probability of success under low signal to noise ratio (SNR and small number of snapshots.
Model-Consistent Sparse Estimation through the Bootstrap
Bach, Francis
2009-01-01
We consider the least-square linear regression problem with regularization by the $\\ell^1$-norm, a problem usually referred to as the Lasso. In this paper, we first present a detailed asymptotic analysis of model consistency of the Lasso in low-dimensional settings. For various decays of the regularization parameter, we compute asymptotic equivalents of the probability of correct model selection. For a specific rate decay, we show that the Lasso selects all the variables that should enter the model with probability tending to one exponentially fast, while it selects all other variables with strictly positive probability. We show that this property implies that if we run the Lasso for several bootstrapped replications of a given sample, then intersecting the supports of the Lasso bootstrap estimates leads to consistent model selection. This novel variable selection procedure, referred to as the Bolasso, is extended to high-dimensional settings by a provably consistent two-step procedure.
USEFULNESS OF BOOTSTRAPPING IN PORTFOLIO MANAGEMENT
Directory of Open Access Journals (Sweden)
Boris Radovanov
2012-12-01
Full Text Available This paper contains a comparison of in-sample and out-of-sample performances between the resampled efficiency technique, patented by Richard Michaud and Robert Michaud (1999, and traditional Mean-Variance portfolio selection, presented by Harry Markowitz (1952. Based on the Monte Carlo simulation, data (samples generation process determines the algorithms by using both, parametric and nonparametric bootstrap techniques. Resampled efficiency provides the solution to use uncertain information without the need for constrains in portfolio optimization. Parametric bootstrap process starts with a parametric model specification, where we apply Capital Asset Pricing Model. After the estimation of specified model, the series of residuals are used for resampling process. On the other hand, nonparametric bootstrap divides series of price returns into the new series of blocks containing previous determined number of consecutive price returns. This procedure enables smooth resampling process and preserves the original structure of data series.
Bootstrap Percolation on Random Geometric Graphs
Bradonjić, Milan
2012-01-01
Bootstrap percolation has been used effectively to model phenomena as diverse as emergence of magnetism in materials, spread of infection, diffusion of software viruses in computer networks, adoption of new technologies, and emergence of collective action and cultural fads in human societies. It is defined on an (arbitrary) network of interacting agents whose state is determined by the state of their neighbors according to a threshold rule. In a typical setting, bootstrap percolation starts by random and independent "activation" of nodes with a fixed probability $p$, followed by a deterministic process for additional activations based on the density of active nodes in each neighborhood ($\\th$ activated nodes). Here, we study bootstrap percolation on random geometric graphs in the regime when the latter are (almost surely) connected. Random geometric graphs provide an appropriate model in settings where the neighborhood structure of each node is determined by geographical distance, as in wireless {\\it ad hoc} ...
Conference on Bootstrapping and Related Techniques
Rothe, Günter; Sendler, Wolfgang
1992-01-01
This book contains 30 selected, refereed papers from an in- ternational conference on bootstrapping and related techni- ques held in Trier 1990. Thepurpose of the book is to in- form about recent research in the area of bootstrap, jack- knife and Monte Carlo Tests. Addressing the novice and the expert it covers as well theoretical as practical aspects of these statistical techniques. Potential users in different disciplines as biometry, epidemiology, computer science, economics and sociology but also theoretical researchers s- hould consult the book to be informed on the state of the art in this area.
Early Stop Criterion from the Bootstrap Ensemble
DEFF Research Database (Denmark)
Hansen, Lars Kai; Larsen, Jan; Fog, Torben L.
1997-01-01
This paper addresses the problem of generalization error estimation in neural networks. A new early stop criterion based on a Bootstrap estimate of the generalization error is suggested. The estimate does not require the network to be trained to the minimum of the cost function, as required...... by other methods based on asymptotic theory. Moreover, in contrast to methods based on cross-validation which require data left out for testing, and thus biasing the estimate, the Bootstrap technique does not have this disadvantage. The potential of the suggested technique is demonstrated on various time...
BOOTSTRAPPING FOR EXTRACTING RELATIONS FROM LARGE CORPORA
Institute of Scientific and Technical Information of China (English)
无
2008-01-01
A new approach of relation extraction is described in this paper. It adopts a bootstrapping model with a novel iteration strategy, which generates more precise examples of specific relation. Compared with previous methods, the proposed method has three main advantages: first, it needs less manual intervention; second, more abundant and reasonable information are introduced to represent a relation pattern; third, it reduces the risk of circular dependency occurrence in bootstrapping. Scalable evaluation methodology and metrics are developed for our task with comparable techniques over TianWang 100G corpus. The experimental results show that it can get 90% precision and have excellent expansibility.
High perfomance selectable value transportable high dc Voltage standard
Galliana, Flavio; Tet, Luca Roncaglione
2016-01-01
At National Institute of Metrological Research (INRIM), a selectable-value Transportable High dcVoltage Standard (THVS) operating in the range from 10 V to 100 V in steps of 10 V, was developed. This Standard was built to cover the lack of high level dc Voltage Standards at voltages higher than 10 V to employ as laboratory (local) or travelling Standards for Inter-Laboratory Comparisons (ILCs). A ground-mobile electronic technique was used to enhance the accuracy of the THVS at the higher values. The THVS shows better noise, better short-mid-term stability than top level dc Voltage and multifunction calibrators (MFCs) and better suitability and insensibility to be transported than these instruments. The project is extensible to 1000 V.
Bootstrap finance: the art of start-ups.
Bhide, A
1992-01-01
Entrepreneurship is more popular than ever: courses are full, policymakers emphasize new ventures, managers yearn to go off on their own. Would-be founders often misplace their energies, however. Believing in a "big money" model of entrepreneurship, they spend a lot of time trying to attract investors instead of using wits and hustle to get their ideas off the ground. A study of 100 of the 1989 Inc. "500" list of fastest growing U.S. start-ups attests to the value of bootstrapping. In fact, what it takes to start a business often conflicts with what venture capitalists require. Investors prefer solid plans, well-defined markets, and track records. Entrepreneurs are heavy on energy and enthusiasm but may be short on credentials. They thrive in rapidly changing environments where uncertain prospects may scare off established companies. Rolling with the punches is often more important than formal plans. Striving to adhere to investors' criteria can diminish the flexibility--the try-it, fix-it approach--an entrepreneur needs to make a new venture work. Seven principles are basic for successful start-ups: get operational fast; look for quick break-even, cash-generating projects; offer high-value products or services that can sustain direct personal selling; don't try to hire the crack team; keep growth in check; focus on cash; and cultivate banks early. Growth and change are the start-up's natural environment. But change is also the reward for success: just as ventures grow, their founders usually have to take a fresh look at everything again: roles, organization, even the very policies that got the business up and running.
Bootstrapping Density-Weighted Average Derivatives
DEFF Research Database (Denmark)
Cattaneo, Matias D.; Crump, Richard K.; Jansson, Michael
Employing the "small bandwidth" asymptotic framework of Cattaneo, Crump, and Jansson (2009), this paper studies the properties of a variety of bootstrap-based inference procedures associated with the kernel-based density-weighted averaged derivative estimator proposed by Powell, Stock, and Stoker...
Bootstrapping Kernel-Based Semiparametric Estimators
DEFF Research Database (Denmark)
Cattaneo, Matias D.; Jansson, Michael
by accommodating a non-negligible bias. A noteworthy feature of the assumptions under which the result is obtained is that reliance on a commonly employed stochastic equicontinuity condition is avoided. The second main result shows that the bootstrap provides an automatic method of correcting for the bias even...
How to Bootstrap a Human Communication System
Fay, Nicolas; Arbib, Michael; Garrod, Simon
2013-01-01
How might a human communication system be bootstrapped in the absence of conventional language? We argue that motivated signs play an important role (i.e., signs that are linked to meaning by structural resemblance or by natural association). An experimental study is then reported in which participants try to communicate a range of pre-specified…
Pulling Econometrics Students up by Their Bootstraps
O'Hara, Michael E.
2014-01-01
Although the concept of the sampling distribution is at the core of much of what we do in econometrics, it is a concept that is often difficult for students to grasp. The thought process behind bootstrapping provides a way for students to conceptualize the sampling distribution in a way that is intuitive and visual. However, teaching students to…
Bootstrapping pronunciation models: a South African case study
CSIR Research Space (South Africa)
Davel, M
2006-02-27
Full Text Available Bootstrapping techniques can accelerate the development of language technology for new languages. The authors define a framework for the analysis of a general bootstrapping process whereby a model is improved through a controlled series...
Efficient generation of pronunciation dictionaries: human factors factors during bootstrapping
CSIR Research Space (South Africa)
Davel, MH
2004-10-01
Full Text Available Bootstrapping techniques have significant potential for the efficient generation of linguistic resources such as electronic pronunciation dictionaries. The authors describe a system and an approach to bootstrapping for the development...
Bootstrapping Relational Affordances of Object Pairs using Transfer
DEFF Research Database (Denmark)
Fichtl, Severin; Kraft, Dirk; Krüger, Norbert;
2016-01-01
leverage past knowledge to accelerate current learning (which we call bootstrapping). We learn Random Forest based affordance predictors from visual inputs and demonstrate two approaches to knowledge transfer for bootstrapping. In the first approach (direct bootstrapping), the state-space for a new...... affordance predictor is augmented with the output of previously learnt affordances. In the second approach (category based bootstrapping), we form categories that capture underlying commonalities of a pair of existing affordances and augment the state-space with this category classifier’s output. In addition....... We also show that there is no significant difference in performance between direct and category based bootstrapping....
The cluster bootstrap consistency in generalized estimating equations
Cheng, Guang
2013-03-01
The cluster bootstrap resamples clusters or subjects instead of individual observations in order to preserve the dependence within each cluster or subject. In this paper, we provide a theoretical justification of using the cluster bootstrap for the inferences of the generalized estimating equations (GEE) for clustered/longitudinal data. Under the general exchangeable bootstrap weights, we show that the cluster bootstrap yields a consistent approximation of the distribution of the regression estimate, and a consistent approximation of the confidence sets. We also show that a computationally more efficient one-step version of the cluster bootstrap provides asymptotically equivalent inference. © 2012.
Production of High Value Cellulose from Tobacco
Energy Technology Data Exchange (ETDEWEB)
Berson, R Eric; Dvaid, Keith; McGinley, W Mark; Meduri, Praveen; Clark, Ezra; Dayalan, Ethirajulu; Sumanasekera, Gamini; Sunkara, Mahendra; Colliver, Donald
2011-06-15
The Kentucky Rural Energy Supply Program was established in 2005 by a federal direct appropriation to benefit the citizens of the Commonwealth by creating a unified statewide consortium to promote renewable energy and energy efficiency in Kentucky. The U.S. Department of Energy's (DOE) Office of Biomass Programs initially funded the consortium in 2005 with a $2 million operational grant. The Kentucky Rural Energy Consortium (KREC) was formed at the outset of the program to advance energy efficiency and comprehensive research on biomass and bioenergy of importance to Kentucky agriculture, rural communities, and related industries. In recognition of the successful efforts of the program, KREC received an additional $1.96 million federal appropriation in 2008 for renewal of the DOE grant. From the beginning, KREC understood the value of providing a statewide forum for the discussion of Kentucky's long term energy needs and economic development potential. The new funding allowed KREC to continue to serve as a clearinghouse and support new research and development and outreach programs for energy efficiency and renewable energy.
Lopez-Mejia, Mariana; Roldan-Valadez, Ernesto
2016-03-01
There is no consensus about apparent diffusion coefficient (ADC) values in acute stroke regions that could be used by clinicians in a day-to-day clinical practice; regional measures using confidence intervals (CIs) and a graphic representation of means are scarce in the literature. Our aim in this study was to compare ADC values in infarct, penumbra, and normal brain regions in patients with acute ischemic stroke (AIS). This is a retrospective study of 100 magnetic resonance imaging data sets from AIS patients. ADC values were measured in the infarct, penumbra, and normal regions. Three hundred measurements underwent 1-way analysis of variance, analysis of means, and calculation of 95% and 84% CIs. There was a statistically significant difference at the P level less than .025 in ADC values for the 3 regions (F[2, 297] = 168.039, P ≤ .001), with no overlap of the CIs for the means among the regions: normal brain (mean [M] = .847, standard deviation [SD] = .103, 95% CI: .825-.866), infarct (M = .533, SD = .157, 95% CI: .501-.563), and penumbra (M = .764, SD = .110, 95% CI: .740-.787). ADC values might be used as reference data in acute stroke-specific populations; CIs would provide radiologists and clinicians with additional quantitative tools to evaluate penumbra, infarct, and normal brain tissue and to tailor follow-up and treatment options for selected patients. Copyright © 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.
Bootstrapping the Coronal Magnetic Field with STEREO
Aschwanden, Markus J.
2010-05-01
The 3D coronal magnetic field obtained from stereoscopically triangulated loops has been compared with standard photospheric magnetogram extrapolations. We found a large misalignment of 20-40 deg, depending on the complexity of an AR (Sandman et al. 2009; DeRosa et al. 2009). These studies prove that the magnetic field in the photosphere is not force-free and fundamentally cannot reproduce the coronal magnetic field. Bootstrapping with coronal loop 3D geometries are required to improve modeling of the coronal field. Such coronal field bootstrapping methods are currently developed using stereoscopically triangulated loops from STEREO/EUVI and preliminary results show already a significantly reduced misalignment of 10-20 deg.
Bootstrap for the case-cohort design.
Huang, Yijian
2014-06-01
The case-cohort design facilitates economical investigation of risk factors in a large survival study, with covariate data collected only from the cases and a simple random subset of the full cohort. Methods that accommodate the design have been developed for various semiparametric models, but most inference procedures are based on asymptotic distribution theory. Such inference can be cumbersome to derive and implement, and does not permit confidence band construction. While bootstrap is an obvious alternative, how to resample is unclear because of complications from the two-stage sampling design. We establish an equivalent sampling scheme, and propose a novel and versatile nonparametric bootstrap for robust inference with an appealingly simple single-stage resampling. Theoretical justification and numerical assessment are provided for a number of procedures under the proportional hazards model.
The $(2,0)$ superconformal bootstrap
Beem, Christopher; Rastelli, Leonardo; van Rees, Balt C
2016-01-01
We develop the conformal bootstrap program for six-dimensional conformal field theories with $(2,0)$ supersymmetry, focusing on the universal four-point function of stress tensor multiplets. We review the solution of the superconformal Ward identities and describe the superconformal block decomposition of this correlator. We apply numerical bootstrap techniques to derive bounds on OPE coefficients and scaling dimensions from the constraints of crossing symmetry and unitarity. We also derive analytic results for the large spin spectrum using the lightcone expansion of the crossing equation. Our principal result is strong evidence that the $A_1$ theory realizes the minimal allowed central charge $(c=25)$ for any interacting $(2,0)$ theory. This implies that the full stress tensor four-point function of the $A_1$ theory is the unique unitary solution to the crossing symmetry equation at $c=25$. For this theory, we estimate the scaling dimensions of the lightest unprotected operators appearing in the stress tenso...
Bootstrapping ${\\mathcal N}=2$ chiral correlators
Lemos, Madalena
2016-01-01
We apply the numerical bootstrap program to chiral operators in four-dimensional ${\\mathcal N}=2$ SCFTs. In the first part of this work we study four-point functions in which all fields have the same conformal dimension. We give special emphasis to bootstrapping a specific theory: the simplest Argyres-Douglas fixed point with no flavor symmetry. In the second part we generalize our setup and consider correlators of fields with unequal dimension. This is an example of a mixed correlator and allows us to probe new regions in the parameter space of ${\\mathcal N}=2$ SCFTs. In particular, our results put constraints on relations in the Coulomb branch chiral ring and on the curvature of the Zamolodchikov metric.
A tauberian theorem for the conformal bootstrap arXiv
Qiao, Jiaxin
For expansions in one-dimensional conformal blocks, we provide a rigorous link between the asymptotics of the spectral density of exchanged primaries and the leading singularity in the crossed channel. Our result has a direct application to systems of SL(2,R)-invariant correlators (also known as 1d CFTs). It also puts on solid ground a part of the lightcone bootstrap analysis of the spectrum of operators of high spin and bounded twist in CFTs in d>2. In addition, a similar argument controls the spectral density asymptotics in large N gauge theories.
TASI Lectures on the Conformal Bootstrap
Simmons-Duffin, David
2016-01-01
These notes are from courses given at TASI and the Advanced Strings School in summer 2015. Starting from principles of quantum field theory and the assumption of a traceless stress tensor, we develop the basics of conformal field theory, including conformal Ward identities, radial quantization, reflection positivity, the operator product expansion, and conformal blocks. We end with an introduction to numerical bootstrap methods, focusing on the 2d and 3d Ising models.
Bootstrapping Deep Lexical Resources: Resources for Courses
Baldwin, Timothy
2007-01-01
We propose a range of deep lexical acquisition methods which make use of morphological, syntactic and ontological language resources to model word similarity and bootstrap from a seed lexicon. The different methods are deployed in learning lexical items for a precision grammar, and shown to each have strengths and weaknesses over different word classes. A particular focus of this paper is the relative accessibility of different language resource types, and predicted ``bang for the buck'' associated with each in deep lexical acquisition applications.
Bootstrap Estimation for Nonparametric Efficiency Estimates
1995-01-01
This paper develops a consistent bootstrap estimation procedure to obtain confidence intervals for nonparametric measures of productive efficiency. Although the methodology is illustrated in terms of technical efficiency measured by output distance functions, the technique can be easily extended to other consistent nonparametric frontier models. Variation in estimated efficiency scores is assumed to result from variation in empirical approximations to the true boundary of the production set. ...
Bootstrapping pronunciation dictionaries: practical issues
CSIR Research Space (South Africa)
Davel, MH
2005-09-01
Full Text Available by many examples; it therefore is an experimen- tal issue to determine how useful this guideline is in practically detecting transcription errors. Different languages will differ in this regard ? a highly ?regular? language such as Spanish 3... will generally have many examples of each valid rule, whereas the idiosyncrasies of English pronunciation will produce a large number of valid special cases. As a consequence, our approach is expected to be more successful for languages such as Spanish...
Liang, Rong; Zhou, Shu-dong; Li, Li-xia; Zhang, Jun-guo; Gao, Yan-hui
2013-09-01
This paper aims to achieve Bootstraping in hierarchical data and to provide a method for the estimation on confidence interval(CI) of intraclass correlation coefficient(ICC).First, we utilize the mixed-effects model to estimate data from ICC of repeated measurement and from the two-stage sampling. Then, we use Bootstrap method to estimate CI from related ICCs. Finally, the influences of different Bootstraping strategies to ICC's CIs are compared. The repeated measurement instance show that the CI of cluster Bootsraping containing the true ICC value. However, when ignoring the hierarchy characteristics of data, the random Bootsraping method shows that it has the invalid CI. Result from the two-stage instance shows that bias observed between cluster Bootstraping's ICC means while the ICC of the original sample is the smallest, but with wide CI. It is necessary to consider the structure of data as important, when hierarchical data is being resampled. Bootstrapping seems to be better on the higher than that on lower levels.
Application of Robust Regression and Bootstrap in Poductivity Analysis of GERD Variable in EU27
Directory of Open Access Journals (Sweden)
Dagmar Blatná
2014-06-01
Full Text Available The GERD is one of Europe 2020 headline indicators being tracked within the Europe 2020 strategy. The headline indicator is the 3% target for the GERD to be reached within the EU by 2020. Eurostat defi nes “GERD” as total gross domestic expenditure on research and experimental development in a percentage of GDP. GERD depends on numerous factors of a general economic background, namely of employment, innovation and research, science and technology. The values of these indicators vary among the European countries, and consequently the occurrence of outliers can be anticipated in corresponding analyses. In such a case, a classical statistical approach – the least squares method – can be highly unreliable, the robust regression methods representing an acceptable and useful tool. The aim of the present paper is to demonstrate the advantages of robust regression and applicability of the bootstrap approach in regression based on both classical and robust methods.
Degenerate U- and V-statistics under weak dependence: Asymptotic theory and bootstrap consistency
Leucht, Anne
2012-01-01
We devise a general result on the consistency of model-based bootstrap methods for U- and V-statistics under easily verifiable conditions. For that purpose, we derive the limit distributions of degree-2 degenerate U- and V-statistics for weakly dependent $\\mathbb{R}^d$-valued random variables first. To this end, only some moment conditions and smoothness assumptions concerning the kernel are required. Based on this result, we verify that the bootstrap counterparts of these statistics have the same limit distributions. Finally, some applications to hypothesis testing are presented.
The economics of bootstrapping space industries - Development of an analytic computer model
Goldberg, A. H.; Criswell, D. R.
1982-01-01
A simple economic model of 'bootstrapping' industrial growth in space and on the Moon is presented. An initial space manufacturing facility (SMF) is assumed to consume lunar materials to enlarge the productive capacity in space. After reaching a predetermined throughput, the enlarged SMF is devoted to products which generate revenue continuously in proportion to the accumulated output mass (such as space solar power stations). Present discounted value and physical estimates for the general factors of production (transport, capital efficiency, labor, etc.) are combined to explore optimum growth in terms of maximized discounted revenues. It is found that 'bootstrapping' reduces the fractional cost to a space industry of transport off-Earth, permits more efficient use of a given transport fleet. It is concluded that more attention should be given to structuring 'bootstrapping' scenarios in which 'learning while doing' can be more fully incorporated in program analysis.
Bootstrapping One-Loop QCD Amplitudeswith General Helicities
Energy Technology Data Exchange (ETDEWEB)
Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren; Kosower, David A.
2006-04-25
The recently developed on-shell bootstrap for computing one-loop amplitudes in non-supersymmetric theories such as QCD combines the unitarity method with loop-level on-shell recursion. For generic helicity configurations, the recursion relations may involve undetermined contributions from non-standard complex singularities or from large values of the shift parameter. Here we develop a strategy for sidestepping difficulties through use of pairs of recursion relations. To illustrate the strategy, we present sets of recursion relations needed for obtaining n-gluon amplitudes in QCD. We give a recursive solution for the one-loop n-gluon QCD amplitudes with three or four color-adjacent gluons of negative helicity and the remaining ones of positive helicity. We provide an explicit analytic formula for the QCD amplitude A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}), as well as numerical results for A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), A{sub 8;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}, 8{sup +}), and A{sub 8;1}(1{sup -}, 2{sup -}, 3{sup -}, 4{sup -}, 5{sup +}, 6{sup +}, 7{sup +}, 8{sup +}). We expect the on-shell bootstrap approach to have widespread applications to phenomenological studies at colliders.
Shimada, Makoto K; Nishida, Tsunetoshi
2017-02-20
Felsenstein's PHYLIP package of molecular phylogeny tools has been used globally since 1980. The programs are receiving renewed attention because of their character-based user interface, which has the advantage of being scriptable for use with large-scale data studies based on super-computers or massively parallel computing clusters. However, occasionally we found, the PHYLIP Consense program output text file displays two or more divided bootstrap values for the same cluster in its result table, and when this happens the output Newick tree file incorrectly assigns only the last value to that cluster that disturbs correct estimation of a consensus tree. We ascertained the cause of this aberrant behavior in the bootstrapping calculation. Our rewrite of the Consense program source code outputs bootstrap values, without redundancy, in its result table, and a Newick tree file with appropriate, corresponding bootstrap values. Furthermore, we developed an add-on program and shell script, add_bootstrap.pl and fasta2tre_bs.bsh, to generate a Newick tree containing the topology and branch lengths inferred from the original data along with valid bootstrap values, and to actualize the automated inference of a phylogenetic tree containing the originally inferred topology and branch lengths with bootstrap values, from multiple unaligned sequences, respectively. These programs can be downloaded at: https://github.com/ShimadaMK/PHYLIP_enhance/.
Accidental Symmetries and the Conformal Bootstrap
Chester, Shai M; Iliesiu, Luca V; Klebanov, Igor R; Pufu, Silviu S; Yacoby, Ran
2015-01-01
We study an ${\\cal N} = 2$ supersymmetric generalization of the three-dimensional critical $O(N)$ vector model that is described by $N+1$ chiral superfields with superpotential $W = g_1 X \\sum_i Z_i^2 + g_2 X^3$. By combining the tools of the conformal bootstrap with results obtained through supersymmetric localization, we argue that this model exhibits a symmetry enhancement at the infrared superconformal fixed point due to $g_2$ flowing to zero. This example is special in that the existence of an infrared fixed point with $g_1,g_2\
Towards bootstrapping QED{sub 3}
Energy Technology Data Exchange (ETDEWEB)
Chester, Shai M.; Pufu, Silviu S. [Joseph Henry Laboratories, Princeton University,Princeton, NJ 08544 (United States)
2016-08-02
We initiate the conformal bootstrap study of Quantum Electrodynamics in 2+1 space-time dimensions (QED{sub 3}) with N flavors of charged fermions by focusing on the 4-point function of four monopole operators with the lowest unit of topological charge. We obtain upper bounds on the scaling dimension of the doubly-charged monopole operator, with and without assuming other gaps in the operator spectrum. Intriguingly, we find a (gap-dependent) kink in these bounds that comes reasonably close to the large N extrapolation of the scaling dimensions of the singly-charged and doubly-charged monopole operators down to N=4 and N=6.
Mellin space bootstrap for global symmetry
Dey, Parijat; Kaviraj, Apratim; Sinha, Aninda
2017-07-01
We apply analytic conformal bootstrap ideas in Mellin space to conformal field theories with O( N) symmetry and cubic anisotropy. We write down the conditions arising from the consistency between the operator product expansion and crossing symmetry in Mellin space. We solve the constraint equations to compute the anomalous dimension and the OPE coefficients of all operators quadratic in the fields in the epsilon expansion. We reproduce known results and derive new results up to O( ɛ 3). For the O( N) case, we also study the large N limit in general dimensions and reproduce known results at the leading order in 1 /N.
A Parsimonious Bootstrap Method to Model Natural Inflow Energy Series
Directory of Open Access Journals (Sweden)
Fernando Luiz Cyrino Oliveira
2014-01-01
Full Text Available The Brazilian energy generation and transmission system is quite peculiar in its dimension and characteristics. As such, it can be considered unique in the world. It is a high dimension hydrothermal system with huge participation of hydro plants. Such strong dependency on hydrological regimes implies uncertainties related to the energetic planning, requiring adequate modeling of the hydrological time series. This is carried out via stochastic simulations of monthly inflow series using the family of Periodic Autoregressive models, PAR(p, one for each period (month of the year. In this paper it is shown the problems in fitting these models by the current system, particularly the identification of the autoregressive order “p” and the corresponding parameter estimation. It is followed by a proposal of a new approach to set both the model order and the parameters estimation of the PAR(p models, using a nonparametric computational technique, known as Bootstrap. This technique allows the estimation of reliable confidence intervals for the model parameters. The obtained results using the Parsimonious Bootstrap Method of Moments (PBMOM produced not only more parsimonious model orders but also adherent stochastic scenarios and, in the long range, lead to a better use of water resources in the energy operation planning.
Bootstrap embedding: An internally consistent fragment-based method
Welborn, Matthew; Tsuchimochi, Takashi; Van Voorhis, Troy
2016-08-01
Strong correlation poses a difficult problem for electronic structure theory, with computational cost scaling quickly with system size. Fragment embedding is an attractive approach to this problem. By dividing a large complicated system into smaller manageable fragments "embedded" in an approximate description of the rest of the system, we can hope to ameliorate the steep cost of correlated calculations. While appealing, these methods often converge slowly with fragment size because of small errors at the boundary between fragment and bath. We describe a new electronic embedding method, dubbed "Bootstrap Embedding," a self-consistent wavefunction-in-wavefunction embedding theory that uses overlapping fragments to improve the description of fragment edges. We apply this method to the one dimensional Hubbard model and a translationally asymmetric variant, and find that it performs very well for energies and populations. We find Bootstrap Embedding converges rapidly with embedded fragment size, overcoming the surface-area-to-volume-ratio error typical of many embedding methods. We anticipate that this method may lead to a low-scaling, high accuracy treatment of electron correlation in large molecular systems.
On the Impact of Bootstrap in Stratified Random Sampling
Institute of Scientific and Technical Information of China (English)
LIU Cheng; ZHAO Lian-wen
2009-01-01
In general the accuracy of mean estimator can be improved by stratified random sampling. In this paper, we provide an idea different from empirical methods that the accuracy can be more improved through bootstrap resampling method under some conditions. The determination of sample size by bootstrap method is also discussed, and a simulation is made to verify the accuracy of the proposed method. The simulation results show that the sample size based on bootstrapping is smaller than that based on central limit theorem.
Bootstrap-Based Inference for Cube Root Consistent Estimators
DEFF Research Database (Denmark)
Cattaneo, Matias D.; Jansson, Michael; Nagasawa, Kenichi
This note proposes a consistent bootstrap-based distributional approximation for cube root consistent estimators such as the maximum score estimator of Manski (1975) and the isotonic density estimator of Grenander (1956). In both cases, the standard nonparametric bootstrap is known to be inconsis......This note proposes a consistent bootstrap-based distributional approximation for cube root consistent estimators such as the maximum score estimator of Manski (1975) and the isotonic density estimator of Grenander (1956). In both cases, the standard nonparametric bootstrap is known...
Excitons in solids with time-dependent density-functional theory: the bootstrap kernel and beyond
Byun, Young-Moo; Yang, Zeng-Hui; Ullrich, Carsten
Time-dependent density-functional theory (TDDFT) is an efficient method to describe the optical properties of solids. Lately, a series of bootstrap-type exchange-correlation (xc) kernels have been reported to produce accurate excitons in solids, but different bootstrap-type kernels exist in the literature, with mixed results. In this presentation, we reveal the origin of the confusion and show a new empirical TDDFT xc kernel to compute excitonic properties of semiconductors and insulators efficiently and accurately. Our method can be used for high-throughput screening calculations and large unit cell calculations. Work supported by NSF Grant DMR-1408904.
Highly-Valued Reasons Muslim Caregivers Choose Evangelical Christian Schools
Rumbaugh, Andrew E.
2009-01-01
This study investigated what were the most highly-valued reasons among Muslim caregivers for sending their children to Lebanese evangelical Christian schools. Muslim caregivers (N = 1,403) from four Lebanese evangelical Christian schools responded to determine what were the most highly-valued reasons for sending their children to an evangelical…
Directory of Open Access Journals (Sweden)
Ristya Widi Endah Yani
2008-12-01
Full Text Available Background: Bootstrap is a computer simulation-based method that provides estimation accuracy in estimating inferential statistical parameters. Purpose: This article describes a research using secondary data (n = 30 aimed to elucidate bootstrap method as the estimator of linear regression test based on the computer programs MINITAB 13, SPSS 13, and MacroMINITAB. Methods: Bootstrap regression methods determine ˆ β and Yˆ value from OLS (ordinary least square, ε i = Yi −Yˆi value, determine how many repetition for bootstrap (B, take n sample by replacement from ε i to ε (i , Yi = Yˆi + ε (i value, ˆ β value from sample bootstrap at i vector. If the amount of repetition less than, B a recalculation should be back to take n sample by using replacement from ε i . Otherwise, determine ˆ β from “bootstrap” methods as the average ˆ β value from the result of B times sample taken. Result: The result has similar result compared to linear regression equation with OLS method (α = 5%. The resulting regression equation for caries was = 1.90 + 2.02 (OHI-S, indicating that every one increase of OHI-S unit will result in caries increase of 2.02 units. Conclusion: This was conducted with B as many as 10,500 with 10 times iterations.
Seol, Hyunsoo
2016-06-01
The purpose of this study was to apply the bootstrap procedure to evaluate how the bootstrapped confidence intervals (CIs) for polytomous Rasch fit statistics might differ according to sample sizes and test lengths in comparison with the rule-of-thumb critical value of misfit. A total of 25 simulated data sets were generated to fit the Rasch measurement and then a total of 1,000 replications were conducted to compute the bootstrapped CIs under each of 25 testing conditions. The results showed that rule-of-thumb critical values for assessing the magnitude of misfit were not applicable because the infit and outfit mean square error statistics showed different magnitudes of variability over testing conditions and the standardized fit statistics did not exactly follow the standard normal distribution. Further, they also do not share the same critical range for the item and person misfit. Based on the results of the study, the bootstrapped CIs can be used to identify misfitting items or persons as they offer a reasonable alternative solution, especially when the distributions of the infit and outfit statistics are not well known and depend on sample size.
Parametric bootstrap methods for testing multiplicative terms in GGE and AMMI models.
Forkman, Johannes; Piepho, Hans-Peter
2014-09-01
The genotype main effects and genotype-by-environment interaction effects (GGE) model and the additive main effects and multiplicative interaction (AMMI) model are two common models for analysis of genotype-by-environment data. These models are frequently used by agronomists, plant breeders, geneticists and statisticians for analysis of multi-environment trials. In such trials, a set of genotypes, for example, crop cultivars, are compared across a range of environments, for example, locations. The GGE and AMMI models use singular value decomposition to partition genotype-by-environment interaction into an ordered sum of multiplicative terms. This article deals with the problem of testing the significance of these multiplicative terms in order to decide how many terms to retain in the final model. We propose parametric bootstrap methods for this problem. Models with fixed main effects, fixed multiplicative terms and random normally distributed errors are considered. Two methods are derived: a full and a simple parametric bootstrap method. These are compared with the alternatives of using approximate F-tests and cross-validation. In a simulation study based on four multi-environment trials, both bootstrap methods performed well with regard to Type I error rate and power. The simple parametric bootstrap method is particularly easy to use, since it only involves repeated sampling of standard normally distributed values. This method is recommended for selecting the number of multiplicative terms in GGE and AMMI models. The proposed methods can also be used for testing components in principal component analysis.
Bootstrapping Mixed Correlators in the 3D Ising Model
Kos, Filip; Simmons-Duffin, David
2014-01-01
We study the conformal bootstrap for systems of correlators involving non-identical operators. The constraints of crossing symmetry and unitarity for such mixed correlators can be phrased in the language of semidefinite programming. We apply this formalism to the simplest system of mixed correlators in 3D CFTs with a $\\mathbb{Z}_2$ global symmetry. For the leading $\\mathbb{Z}_2$-odd operator $\\sigma$ and $\\mathbb{Z}_2$-even operator $\\epsilon$, we obtain numerical constraints on the allowed dimensions $(\\Delta_\\sigma, \\Delta_\\epsilon)$ assuming that $\\sigma$ and $\\epsilon$ are the only relevant scalars in the theory. These constraints yield a small closed region in $(\\Delta_\\sigma, \\Delta_\\epsilon)$ space compatible with the known values in the 3D Ising CFT.
Spanning Trees and bootstrap reliability estimation in correlation based networks
Tumminello, M; Lillo, F; Micciché, S; Mantegna, R N
2006-01-01
We introduce a new technique to associate a spanning tree to the average linkage cluster analysis. We term this tree as the Average Linkage Minimum Spanning Tree. We also introduce a technique to associate a value of reliability to links of correlation based graphs by using bootstrap replicas of data. Both techniques are applied to the portfolio of the 300 most capitalized stocks traded at New York Stock Exchange during the time period 2001-2003. We show that the Average Linkage Minimum Spanning Tree recognizes economic sectors and sub-sectors as communities in the network slightly better than the Minimum Spanning Tree does. We also show that the average reliability of links in the Minimum Spanning Tree is slightly greater than the average reliability of links in the Average Linkage Minimum Spanning Tree.
Institute of Scientific and Technical Information of China (English)
HALL Peter
2009-01-01
@@ This is a very attractive article. It combines fascinating new methodology with a most interesting dataset, and a highly motivating presentation. However, despite the many opportunities for discussion, I am going to confine attention to the issue of the block bootstrap, ingeniously developed in this paper into the nearest block bootstrap.
Bootstrap and second-order tests of risk difference.
Lloyd, Chris J
2010-09-01
Clinical trials data often come in the form of low-dimensional tables of small counts. Standard approximate tests such as score and likelihood ratio tests are imperfect in several respects. First, they can give quite different answers from the same data. Second, the actual type-1 error can differ significantly from nominal, even for quite large sample sizes. Third, exact inferences based on these can be strongly nonmonotonic functions of the null parameter and lead to confidence sets that are discontiguous. There are two modern approaches to small sample inference. One is to use so-called higher order asymptotics (Reid, 2003, Annal of Statistics 31, 1695-1731) to provide an explicit adjustment to the likelihood ratio statistic. The theory for this is complex but the statistic is quick to compute. The second approach is to perform an exact calculation of significance assuming the nuisance parameters equal their null estimate (Lee and Young, 2005, Statistic and Probability Letters 71, 143-153), which is a kind of parametric bootstrap. The purpose of this article is to explain and evaluate these two methods, for testing whether a difference in probabilities p(2) - p(1) exceeds a prechosen noninferiority margin δ(0) . On the basis of an extensive numerical study, we recommend bootstrap P-values as superior to all other alternatives. First, they produce practically identical answers regardless of the basic test statistic chosen. Second, they have excellent size accuracy and higher power. Third, they vary much less erratically with the null parameter value δ(0) . © 2009, The International Biometric Society.
Bootstrapping pre-averaged realized volatility under market microstructure noise
DEFF Research Database (Denmark)
Hounyo, Ulrich; Goncalves, Sílvia; Meddahi, Nour
-averaged returns implies that these are kn-dependent with kn growing slowly with the sample size n. This motivates the application of a blockwise bootstrap method. We show that the "blocks of blocks" bootstrap method suggested by Politis and Romano (1992) (and further studied by Bühlmann and Künsch (1995...
Learning web development with Bootstrap and AngularJS
Radford, Stephen
2015-01-01
Whether you know a little about Bootstrap or AngularJS, or you're a complete beginner, this book will enhance your capabilities in both frameworks and you'll build a fully functional web app. A working knowledge of HTML, CSS, and JavaScript is required to fully get to grips with Bootstrap and AngularJS.
Schick, Simon; Rössler, Ole; Weingartner, Rolf
2016-10-01
Based on a hindcast experiment for the period 1982-2013 in 66 sub-catchments of the Swiss Rhine, the present study compares two approaches of building a regression model for seasonal streamflow forecasting. The first approach selects a single "best guess" model, which is tested by leave-one-out cross-validation. The second approach implements the idea of bootstrap aggregating, where bootstrap replicates are employed to select several models, and out-of-bag predictions provide model testing. The target value is mean streamflow for durations of 30, 60 and 90 days, starting with the 1st and 16th day of every month. Compared to the best guess model, bootstrap aggregating reduces the mean squared error of the streamflow forecast by seven percent on average. Thus, if resampling is anyway part of the model building procedure, bootstrap aggregating seems to be a useful strategy in statistical seasonal streamflow forecasting. Since the improved accuracy comes at the cost of a less interpretable model, the approach might be best suited for pure prediction tasks, e.g. as in operational applications.
Genetic divergence among cupuaçu accessions by multiscale bootstrap resampling
Directory of Open Access Journals (Sweden)
Vinicius Silva dos Santos
2015-06-01
Full Text Available This study aimed at investigating the genetic divergence of eighteen accessions of cupuaçu trees based on fruit morphometric traits and comparing usual methods of cluster analysis with the proposed multiscale bootstrap resampling methodology. The data were obtained from an experiment conducted in Tomé-Açu city (PA, Brazil, arranged in a completely randomized design with eighteen cupuaçu accessions and 10 repetitions, from 2004 to 2011. Genetic parameters were estimated by restricted maximum likelihood/best linear unbiased prediction (REML/BLUP methodology. The predicted breeding values were used in the study on genetic divergence through Unweighted Pair Cluster Method with Arithmetic Mean (UPGMA hierarchical clustering and Tocher’s optimization method based on standardized Euclidean distance. Clustering consistency and optimal number of clusters in the UPGMA method were verified by the cophenetic correlation coefficient (CCC and Mojena’s criterion, respectively, besides the multiscale bootstrap resampling technique. The use of the clustering UPGMA method in situations with and without multiscale bootstrap resulted in four and five clusters, respectively, while the Tocher’s method resulted in seven clusters. The multiscale bootstrap resampling technique proves to be efficient to assess the consistency of clustering in hierarchical methods and, consequently, the optimal number of clusters.
Conformal bootstrap, universality and gravitational scattering
Directory of Open Access Journals (Sweden)
Steven Jackson
2015-12-01
Full Text Available We use the conformal bootstrap equations to study the non-perturbative gravitational scattering between infalling and outgoing particles in the vicinity of a black hole horizon in AdS. We focus on irrational 2D CFTs with large c and only Virasoro symmetry. The scattering process is described by the matrix element of two light operators (particles between two heavy states (BTZ black holes. We find that the operator algebra in this regime is (i universal and identical to that of Liouville CFT, and (ii takes the form of an exchange algebra, specified by an R-matrix that exactly matches the scattering amplitude of 2+1 gravity. The R-matrix is given by a quantum 6j-symbol and the scattering phase by the volume of a hyperbolic tetrahedron. We comment on the relevance of our results to scrambling and the holographic reconstruction of the bulk physics near black hole horizons.
Conformal Bootstrap, Universality and Gravitational Scattering
Jackson, Steven; Verlinde, Herman
2014-01-01
We use the conformal bootstrap equations to study the non-perturbative gravitational scattering between infalling and outgoing particles in the vicinity of a black hole horizon in AdS. We focus on irrational 2D CFTs with large $c$, a sparse light spectrum and only Virasoro symmetry. The scattering process is described by the matrix element of two light operators (particles) between two heavy states (BTZ black holes). We find that the operator algebra in this regime is (i) universal and identical to that of Liouville CFT, and (ii) takes the form of an exchange algebra, specified by an R-matrix that exactly matches with the scattering amplitude of 2+1 gravity. The R-matrix is given by a quantum 6j-symbol and the scattering phase by the volume of a hyperbolic tetrahedron. We comment on the relevance of our results to scrambling and the holographic reconstruction of the bulk physics near black hole horizons.
Bootstrap determination of the cointegration rank in heteroskedastic VAR models
DEFF Research Database (Denmark)
Cavaliere, Guiseppe; Rahbæk, Anders; Taylor, A.M. Robert
2014-01-01
-integrated VAR model with i.i.d. innovations. In this paper we investigate the properties of their bootstrap procedures, together with analogous procedures based on a wild bootstrap resampling scheme, when time-varying behavior is present in either the conditional or unconditional variance of the innovations. We...... the asymptotic PLR test or an alternative bootstrap method (where the short run dynamics in the VAR model are estimated unrestrictedly) for a variety of conditionally and unconditionally heteroskedastic innovation processes...... of the underlying vector autoregressive (VAR) model which obtain under the reduced rank null hypothesis. They propose methods based on an independent and individual distributed (i.i.d.) bootstrap resampling scheme and establish the validity of their proposed bootstrap procedures in the context of a co...
Effects of magnetic islands on bootstrap current in toroidal plasmas
Dong, G.; Lin, Z.
2017-03-01
The effects of magnetic islands on electron bootstrap current in toroidal plasmas are studied using gyrokinetic simulations. The magnetic islands cause little changes of the bootstrap current level in the banana regime because of trapped electron effects. In the plateau regime, the bootstrap current is completely suppressed at the island centers due to the destruction of trapped electron orbits by collisions and the flattening of pressure profiles by the islands. In the collisional regime, small but finite bootstrap current can exist inside the islands because of the pressure gradients created by large collisional transport across the islands. Finally, simulation results show that the bootstrap current level increases near the island separatrix due to steeper local density gradients.
Uncertainty estimation in diffusion MRI using the nonlocal bootstrap.
Yap, Pew-Thian; An, Hongyu; Chen, Yasheng; Shen, Dinggang
2014-08-01
In this paper, we propose a new bootstrap scheme, called the nonlocal bootstrap (NLB) for uncertainty estimation. In contrast to the residual bootstrap, which relies on a data model, or the repetition bootstrap, which requires repeated signal measurements, NLB is not restricted by the data structure imposed by a data model and obviates the need for time-consuming multiple acquisitions. NLB hinges on the observation that local imaging information recurs in an image. This self-similarity implies that imaging information coming from spatially distant (nonlocal) regions can be exploited for more effective estimation of statistics of interest. Evaluations using in silico data indicate that NLB produces distribution estimates that are in closer agreement with those generated using Monte Carlo simulations, compared with the conventional residual bootstrap. Evaluations using in vivo data demonstrate that NLB produces results that are in agreement with our knowledge on white matter architecture.
Antisocial Behavior and Interpersonal Values in High School Students.
Molero Jurado, María Del Mar; Pérez Fuentes, María Del Carmen; Carrión Martínez, José J; Luque de la Rosa, Antonio; Garzón Fernández, Anabella; Martos Martínez, África; Simón Márquez, Maria Del Mar; Barragán Martín, Ana B; Gázquez Linares, José J
2017-01-01
This article analyzes the characteristics of antisocial behavior and interpersonal values of high school students (Compulsory Secondary Education) (CSE), the profile of students with high levels of antisocial behavior with regard to interpersonal values, and possible protection from antisocial behavior that interpersonal values could provide. The Interpersonal Values Questionnaire was used to assess interpersonal values, and the Antisocial-Delinquent Behaviors Questionnaire was employed to assess antisocial behaviors. The sample was made up of 885 CSE students aged 14-17. The results revealed a greater prevalence of antisocial behaviors among males and fourth-year CSE students. Moreover, antisocial behaviors were more frequent among participants with high scores in Stimulation, Recognition, Independence, and Leadership and low scores in Conformity and Benevolence. Lastly, logistic regression analyses showed that low scores in Conformity and Benevolence and high scores in Independence predicted high scores in antisocial behavior. The possibility of identifying certain interpersonal values which could positively or negatively affect the appearance of antisocial behavior during adolescence is discussed.
High volcanic seismic b-values: Real or artefacts?
Roberts, Nick; Bell, Andrew; Main, Ian G.
2015-04-01
The b-value of the Gutenberg-Richter distribution quantifies the relative proportion of large to small magnitude earthquakes in a catalogue, in turn related to the population of fault rupture areas and the average slip or stress drop. Accordingly the b-value is an important parameter to consider when evaluating seismic catalogues as it has the potential to provide insight into the temporal or spatial evolution of the system, such as fracture development or changes in the local stress regime. The b-value for tectonic seismicity is commonly found to be close to 1, whereas much higher b-values are frequently reported for volcanic and induced seismicity. Understanding these differences is important for understanding the processes controlling earthquake occurrence in different settings. However, it is possible that anomalously high b-values could arise from small sample sizes, under-estimated completeness magnitudes, or other poorly applied methodologies. Therefore, it is important to establish a rigorous workflow for analyzing these datasets. Here we examine the frequency-magnitude distributions of volcanic earthquake catalogues in order to determine the significance of apparently high b-values. We first derive a workflow for computing the completeness magnitude of a seismic catalogue, using synthetic catalogues of varying shape, size, and known b-value. We find the best approach involves a combination of three methods: 'Maximum Curvature', 'b-value stability', and the 'Goodness-of-Fit test'. To calculate a reliable b-value with an error ≤0.25, the maximum curvature method is preferred for a 'sharp-peaked' discrete distribution. For a catalogue with a broader peak the b-value stability method is the most reliable with the Goodness-of-Fit test being an acceptable backup if the b-value stability method fails. We apply this workflow to earthquake catalogues from El Hierro (2011-2013) and Mt Etna (1999-2013) volcanoes. In general, we find the b-value to be equal to or
Value innovation: the strategic logic of high growth.
Kim, W C; Mauborgne, R
1997-01-01
Why are some companies able to sustain high growth in revenues and profits--and others are not? To answer that question, the authors, both of INSEAD, spent five years studying more than 30 companies around the world. They found that the difference between the high-growth companies and their less successful competitors was in each group's assumptions about strategy. Managers of the less successful companies followed conventional strategic logic. Managers of the high-growth companies followed what the authors call the logic of value innovation. Conventional strategic logic and value innovation differ along the basic dimensions of strategy. Many companies take their industry's conditions as given; value innovators don't. Many companies let competitors set the parameters of their strategic thinking; value innovators do not use rivals as benchmarks. Rather than focus on the differences among customers, value innovators look for what customers value in common. Rather than view opportunities through the lens of existing assets and capabilities, value innovators ask, What if we start anew? The authors tell the story of the French hotelier Accor, which discarded the notion of what a hotel is supposed to look like in order to offer what most customers want: a good night's sleep at a low price. And Virgin Atlantic challenged industry conventions by eliminating first-class service and channeling savings into innovations for business-class passengers. Those companies didn't set out to build advantages over the competition, but they ended up achieving the greatest competitive advantages.
Absolute Value Inequalities: High School Students' Solutions and Misconceptions
Almog, Nava; Ilany, Bat-Sheva
2012-01-01
Inequalities are one of the foundational subjects in high school math curricula, but there is a lack of academic research into how students learn certain types of inequalities. This article fills part of the research gap by presenting the findings of a study that examined high school students' methods of approaching absolute value inequalities,…
Bootstrap consistency for general semiparametric M-estimation
Cheng, Guang
2010-10-01
Consider M-estimation in a semiparametric model that is characterized by a Euclidean parameter of interest and an infinite-dimensional nuisance parameter. As a general purpose approach to statistical inferences, the bootstrap has found wide applications in semiparametric M-estimation and, because of its simplicity, provides an attractive alternative to the inference approach based on the asymptotic distribution theory. The purpose of this paper is to provide theoretical justifications for the use of bootstrap as a semiparametric inferential tool. We show that, under general conditions, the bootstrap is asymptotically consistent in estimating the distribution of the M-estimate of Euclidean parameter; that is, the bootstrap distribution asymptotically imitates the distribution of the M-estimate. We also show that the bootstrap confidence set has the asymptotically correct coverage probability. These general onclusions hold, in particular, when the nuisance parameter is not estimable at root-n rate, and apply to a broad class of bootstrap methods with exchangeable ootstrap weights. This paper provides a first general theoretical study of the bootstrap in semiparametric models. © Institute of Mathematical Statistics, 2010.
The High Value CVT Concept--Cost Effective and Powerful
Institute of Scientific and Technical Information of China (English)
A. Englisch,; A. Teubert; A. Gotz; E. Muller; E. Simon; B. Walter; A. Baumgartner
2011-01-01
Based on the comprehensive comparison of vehicle performance in economy,engine power,driving smoothness,and efficiency cost as well as pollutant emission etc,the paper discussed the high value CVT concept from an angle of the cost effective and powerful for vehicle.In the paper,it researched the related technical detail in CVT.By means of realizing the continuous change in transmission ratio,it could obtain the optimal matching between transmission system and engine operating mode,and enhance the characteristic of fuel oil in economy,and also improve the convenience in manipulation for driver and make passenger comfortable.For easy to understand the concept,the paper made the comparison analysis in many aspects such as performance,transmission specification,high value CVT hybrid,orifice torque sensor,hydraulic system,high value CVT em,new chain portfolio and assessment of the high value CVT on the NEDC.Finally it showed the potential advantages of CVT technology development,and proposed future developing trends to realize technical scheme of high value CVT.
A Simple Voltage Controlled Oscillator Using Bootstrap Circuits and NOR-RS Flip Flop
Chaikla, Amphawan; Pongswatd, Sawai; Sasaki, Hirofumi; Fujimoto, Kuniaki; Yahara, Mitsutoshi
This paper presents a simple and successful design for a voltage controlled oscillator. The proposed circuit is based on the use of two identical bootstrap circuits and a NOR-RS Flip Flop to generate wide-tunable sawtooth and square waves. Increasing control voltage linearly increases the output oscillation frequency. Experimental results verifying the performances of the proposed circuit are in agreement with the calculated values.
Boubtane, Ekrame; Rault, C; Coulibaly, Dramane
2013-01-01
This paper examines the causality relationship between immigration, unemployment and economic growth of the host country. We employ the panel Granger causality testing approach of Konya (2006) that is based on SUR systems and Wald tests with country specific bootstrap critical values. This approach allows to test for Granger-causality on each individual panel member separately by taking into account the contemporaneous correlation across countries. Using annual data over the 1980-2005 period ...
Bootstrap Power of Time Series Goodness of fit tests
Directory of Open Access Journals (Sweden)
Sohail Chand
2013-10-01
Full Text Available In this article, we looked at power of various versions of Box and Pierce statistic and Cramer von Mises test. An extensive simulation study has been conducted to compare the power of these tests. Algorithms have been provided for the power calculations and comparison has also been made between the semi parametric bootstrap methods used for time series. Results show that Box-Pierce statistic and its various versions have good power against linear time series models but poor power against non linear models while situation reverses for Cramer von Mises test. Moreover, we found that dynamic bootstrap method is better than xed design bootstrap method.
Moisture Management for High R-Value Walls
Energy Technology Data Exchange (ETDEWEB)
Lepage, R. [Building Science Corporation, Somerville, MA (United States); Schumacher, C. [Building Science Corporation, Somerville, MA (United States); Lukachko, A. [Building Science Corporation, Somerville, MA (United States)
2013-11-01
This report explains the moisture-related concerns for high R-value wall assemblies and discusses past Building America research work that informs this study. In this project, hygrothermal simulations were prepared for several common approaches to High R-value wall construction in six cities (Houston, Atlanta, Seattle, St. Louis, Chicago, and International Falls) representing a range of climate zones. The modeling program assessed the moisture durability of the wall assemblies based on three primary sources of moisture: construction moisture, air leakage condensation, and bulk water leakage; the report presents results of the study.
Bootstrapping Object Coreferencing on the Semantic Web
Institute of Scientific and Technical Information of China (English)
Wei Hu; Yu-Zhong Qu; Xing-Zhi Sun
2011-01-01
An object on the Semantic Web is likely to be denoted with several URIs by different parties.Object coreferencing is a process to identify "equivalent" URIs of objects for achieving a better Data Web.In this paper,we propose a bootstrapping approach for object coreferencing on the Semantic Web.For an object URI,we firstly establish a kernel that consists of semantically equivalent URIs from the same-as,(inverse) functional properties and (max-)cardinalities,and then extend the kernel with respect to the textual descriptions (e.g.,labels and local names) of URIs.We also propose a trustworthiness-based method to rank the coreferent URIs in the kernel as well as a similarity-based method for ranking the URIs in the extension of the kernel.We implement the proposed approach,called ObjectCoref,on a large-scale dataset that contains 76 million URIs collected by the Falcons search engine until 2008.The evaluation on precision,relative recall and response time demonstrates the feasibility of our approach.Additionally,we apply the proposed approach to investigate the popularity of the URI alias phenomenon on the current Semantic Web.
Directory of Open Access Journals (Sweden)
José Antonio Castorina
2005-12-01
Full Text Available El presente artículo expone la teoría explicativa propuesta por Carey para el cambio conceptual. Primeramente, se plantea la cuestión de la reorganización conceptual en la psicología cognitiva y la posición de Carey. En segundo lugar, se ponen de relieve las condiciones epistémica que deben cumplir las "teorías" infantiles para que la reestructuración conceptual sea posible, así como los modos que adopta esta última. En tercer lugar, se muestran los resultados de investigaciones que verifican el cambio conceptual entre teorías infantiles de biología intuitiva. En cuarto lugar, se plantean las dificultades de otras teorías del cambio conceptual, para luego formular los rasgos del mecanismo alternativo de bootstrapping y su pertinencia para interpretrar los datos de las indagaciones mencionadas. Finalmente, se evalúan la originalidad de la teoría del bootstrpping en el escenario de los debates contemporáneos. Muy especialmente, se esboza una posible aproximación con las tesis dialécticas de Piaget.This paper examines the Carey's theory of conceptual change. First, it describes the conceptual reorganization in cognitive psychology and the author position. Second, the epistemic conditions that children "theories" should fulfil to make conceptual restructuring possible, as well as the ways adopted by the latter, are analyzed. In third place, findings of researches testing the conceptual change among biology intuitive children theories are explained. Subsequently, it discusses the difficulties other theories of conceptual change present, in order to state features of bootstrapping as an alternative mechanism and its relevance for the interpretation of abovementioned researches results. Finally, it evaluates the originality of "bootstrapping" theory in the scene of contemporary debates. It particularly outlines a possible approach to Piaget's dialectic theses.
Directory of Open Access Journals (Sweden)
Goddard Mike E
2004-03-01
Full Text Available Abstract The ordinary-, penalized-, and bootstrap t-test, least squares and best linear unbiased prediction were compared for their false discovery rates (FDR, i.e. the fraction of falsely discovered genes, which was empirically estimated in a duplicate of the data set. The bootstrap-t-test yielded up to 80% lower FDRs than the alternative statistics, and its FDR was always as good as or better than any of the alternatives. Generally, the predicted FDR from the bootstrapped P-values agreed well with their empirical estimates, except when the number of mRNA samples is smaller than 16. In a cancer data set, the bootstrap-t-test discovered 200 differentially regulated genes at a FDR of 2.6%, and in a knock-out gene expression experiment 10 genes were discovered at a FDR of 3.2%. It is argued that, in the case of microarray data, control of the FDR takes sufficient account of the multiple testing, whilst being less stringent than Bonferoni-type multiple testing corrections. Extensions of the bootstrap simulations to more complicated test-statistics are discussed.
Energy Technology Data Exchange (ETDEWEB)
Andrade, Maria Celia Ramos; Ludwig, Gerson Otto [Instituto Nacional de Pesquisas Espaciais (INPE), Sao Jose dos Campos, SP (Brazil). Lab. Associado de Plasma]. E-mail: mcr@plasma.inpe.br
2004-07-01
Different bootstrap current formulations are implemented in a self-consistent equilibrium calculation obtained from a direct variational technique in fixed boundary tokamak plasmas. The total plasma current profile is supposed to have contributions of the diamagnetic, Pfirsch-Schlueter, and the neoclassical Ohmic and bootstrap currents. The Ohmic component is calculated in terms of the neoclassical conductivity, compared here among different expressions, and the loop voltage determined consistently in order to give the prescribed value of the total plasma current. A comparison among several bootstrap current models for different viscosity coefficient calculations and distinct forms for the Coulomb collision operator is performed for a variety of plasma parameters of the small aspect ratio tokamak ETE (Experimento Tokamak Esferico) at the Associated Plasma Laboratory of INPE, in Brazil. We have performed this comparison for the ETE tokamak so that the differences among all the models reported here, mainly regarding plasma collisionality, can be better illustrated. The dependence of the bootstrap current ratio upon some plasma parameters in the frame of the self-consistent calculation is also analysed. We emphasize in this paper what we call the Hirshman-Sigmar/Shaing model, valid for all collisionality regimes and aspect ratios, and a fitted formulation proposed by Sauter, which has the same range of validity but is faster to compute than the previous one. The advantages or possible limitations of all these different formulations for the bootstrap current estimate are analysed throughout this work. (author)
Simulation-optimization via Kriging and bootstrapping : A survey
Kleijnen, Jack P.C.
2014-01-01
This article surveys optimization of simulated systems. The simulation may be either deterministic or random. The survey reflects the author’s extensive experience with simulation-optimization through Kriging (or Gaussian process) metamodels, analysed through parametric bootstrapping for determinist
Variance estimation in neutron coincidence counting using the bootstrap method
Energy Technology Data Exchange (ETDEWEB)
Dubi, C., E-mail: chendb331@gmail.com [Physics Department, Nuclear Research Center of the Negev, P.O.B. 9001 Beer Sheva (Israel); Ocherashvilli, A.; Ettegui, H. [Physics Department, Nuclear Research Center of the Negev, P.O.B. 9001 Beer Sheva (Israel); Pedersen, B. [Nuclear Security Unit, Institute for Transuranium Elements, Via E. Fermi, 2749 JRC, Ispra (Italy)
2015-09-11
In the study, we demonstrate the implementation of the “bootstrap” method for a reliable estimation of the statistical error in Neutron Multiplicity Counting (NMC) on plutonium samples. The “bootstrap” method estimates the variance of a measurement through a re-sampling process, in which a large number of pseudo-samples are generated, from which the so-called bootstrap distribution is generated. The outline of the present study is to give a full description of the bootstrapping procedure, and to validate, through experimental results, the reliability of the estimated variance. Results indicate both a very good agreement between the measured variance and the variance obtained through the bootstrap method, and a robustness of the method with respect to the duration of the measurement and the bootstrap parameters.
Climate time series analysis classical statistical and bootstrap methods
Mudelsee, Manfred
2014-01-01
Written for climatologists and applied statisticians, this book explains the bootstrap algorithms (including novel adaptions) and methods for confidence interval construction. The accuracy of the algorithms is tested by means of Monte Carlo experiments.
Transcriptional Engineering of Microalgae: Prospects for High-Value Chemicals.
Bajhaiya, Amit K; Ziehe Moreira, Javiera; Pittman, Jon K
2017-02-01
Microalgae are diverse microorganisms that are of interest as novel sources of metabolites for various industrial, nutritional, and pharmaceutical applications. Recent studies have demonstrated transcriptional engineering of some metabolic pathways. We propose here that transcriptional engineering could be a viable means to manipulate the biosynthesis of specific high-value metabolic products.
Bootstrapping the statistical uncertainties of NN scattering data
Perez, R Navarro; Arriola, E Ruiz
2014-01-01
We use the Monte Carlo bootstrap as a method to simulate pp and np scattering data below pion production threshold from an initial set of over 6700 experimental mutually $3\\sigma$ consistent data. We compare the results of the bootstrap, with 1020 statistically generated samples of the full database, with the standard covariance matrix method of error propagation. No significant differences in scattering observables and phase shifts are found. This suggests alternative strategies for propagating errors of nuclear forces in nuclear structure calculations.
Finding confidence limits on population growth rates: bootstrap and analytic methods.
Picard, Nicolas; Chagneau, Pierrette; Mortier, Frédéric; Bar-Hen, Avner
2009-05-01
When predicting population dynamics, the value of the prediction is not enough and should be accompanied by a confidence interval that integrates the whole chain of errors, from observations to predictions via the estimates of the parameters of the model. Matrix models are often used to predict the dynamics of age- or size-structured populations. Their parameters are vital rates. This study aims (1) at assessing the impact of the variability of observations on vital rates, and then on model's predictions, and (2) at comparing three methods for computing confidence intervals for values predicted from the models. The first method is the bootstrap. The second method is analytic and approximates the standard error of predictions by their asymptotic variance as the sample size tends to infinity. The third method combines use of the bootstrap to estimate the standard errors of vital rates with the analytical method to then estimate the errors of predictions from the model. Computations are done for an Usher matrix models that predicts the asymptotic (as time goes to infinity) stock recovery rate for three timber species in French Guiana. Little difference is found between the hybrid and the analytic method. Their estimates of bias and standard error converge towards the bootstrap estimates when the error on vital rates becomes small enough, which corresponds in the present case to a number of observations greater than 5000 trees.
Wetting dynamics at high values of contact line speed
Пономарев, К. О.; Феоктистов, Дмитрий Владимирович; Орлова, Евгения Георгиевна
2015-01-01
Experimental results analyses of dynamic contact angle change under the conditions of substrate wetting by distilled water at high values of the contact line speed was conducted. Three spreading modes for copper substrates with different roughness were selected: drop formation, spreading and equilibrium contact angle formation. Peculiarity of droplet spreading on superhydrophobic surface is found. It consists in a monotonic increase of the advancing dynamic contact angle. The effect of the dr...
Lee, Taesam
2017-02-01
The outputs from general circulation models (GCMs) provide useful information about the rate and magnitude of future climate change. The temperature variable is more reliable than other variables in GCM outputs. However, hydrological variables (e.g., precipitation) from GCM outputs for future climate change possess an uncertainty that is too high for practical use. Therefore, a method called intentionally biased bootstrapping (IBB), which simulates the increase of the temperature variable by a certain level as ascertained from observed global warming data, is proposed. In addition, precipitation data were resampled by employing a block-wise sampling technique associated with the temperature simulation. In summary, a warming temperature scenario is simulated, along with the corresponding precipitation values whose time indices are the same as those of the simulated warming temperature scenario. The proposed method was validated with annual precipitation data by truncating the recent years of the record. The proposed model was also employed to assess the future changes in seasonal precipitation in South Korea within a global warming scenario as well as in weekly timescales. The results illustrate that the proposed method is a good alternative for assessing the variation of hydrological variables such as precipitation under the warming condition.
Institute of Scientific and Technical Information of China (English)
郑蓉建; 周林成; 潘丰
2012-01-01
Fault monitoring of bioprocess is important to ensure safety of a reactor and maintain high quality of products. It is difficult to build an accurate mechanistic model for a bioprocess, so fault monitoring based on rich historical or online database is an effective way. A group of data based on bootstrap method could be resampling stochastically, improving generalization capability of model. In this paper, online fault monitoring of generalized additive models (GAMs) combining with bootstrap is proposed for glutamate fermentation process. GAMs and bootstrap are first used to decide confidence interval based on the online and off-line normal sampled data from glutamate fermentation experiments. Then GAMs are used to online fault monitoring for time, dissolved oxygen, oxygen uptake rate, and carbon dioxide evolution rate. The method can provide accurate fault alarm online and is helpful to provide useful information for removing fault and abnormal phenomena in the fermentation.
Xu, Kuan-Man
2006-01-01
A new method is proposed to compare statistical differences between summary histograms, which are the histograms summed over a large ensemble of individual histograms. It consists of choosing a distance statistic for measuring the difference between summary histograms and using a bootstrap procedure to calculate the statistical significance level. Bootstrapping is an approach to statistical inference that makes few assumptions about the underlying probability distribution that describes the data. Three distance statistics are compared in this study. They are the Euclidean distance, the Jeffries-Matusita distance and the Kuiper distance. The data used in testing the bootstrap method are satellite measurements of cloud systems called cloud objects. Each cloud object is defined as a contiguous region/patch composed of individual footprints or fields of view. A histogram of measured values over footprints is generated for each parameter of each cloud object and then summary histograms are accumulated over all individual histograms in a given cloud-object size category. The results of statistical hypothesis tests using all three distances as test statistics are generally similar, indicating the validity of the proposed method. The Euclidean distance is determined to be most suitable after comparing the statistical tests of several parameters with distinct probability distributions among three cloud-object size categories. Impacts on the statistical significance levels resulting from differences in the total lengths of satellite footprint data between two size categories are also discussed.
Taking High Conservation Value from Forests to Freshwaters
Abell, Robin; Morgan, Siân K.; Morgan, Alexis J.
2015-07-01
The high conservation value (HCV) concept, originally developed by the Forest Stewardship Council, has been widely incorporated outside the forestry sector into companies' supply chain assessments and responsible purchasing policies, financial institutions' investment policies, and numerous voluntary commodity standards. Many, if not most, of these newer applications relate to production practices that are likely to affect freshwater systems directly or indirectly, yet there is little guidance as to whether or how HCV can be applied to water bodies. We focus this paper on commodity standards and begin by exploring how prominent standards currently address both HCVs and freshwaters. We then highlight freshwater features of high conservation importance and examine how well those features are captured by the existing HCV framework. We propose a new set of freshwater `elements' for each of the six values and suggest an approach for identifying HCV Areas that takes out-of-fence line impacts into account, thereby spatially extending the scope of existing methods to define HCVs. We argue that virtually any non-marine HCV assessment, regardless of the production sector, should be expanded to include freshwater values, and we suggest how to put those recommendations into practice.
Estimating uncertainty in respondent-driven sampling using a tree bootstrap method.
Baraff, Aaron J; McCormick, Tyler H; Raftery, Adrian E
2016-12-20
Respondent-driven sampling (RDS) is a network-based form of chain-referral sampling used to estimate attributes of populations that are difficult to access using standard survey tools. Although it has grown quickly in popularity since its introduction, the statistical properties of RDS estimates remain elusive. In particular, the sampling variability of these estimates has been shown to be much higher than previously acknowledged, and even methods designed to account for RDS result in misleadingly narrow confidence intervals. In this paper, we introduce a tree bootstrap method for estimating uncertainty in RDS estimates based on resampling recruitment trees. We use simulations from known social networks to show that the tree bootstrap method not only outperforms existing methods but also captures the high variability of RDS, even in extreme cases with high design effects. We also apply the method to data from injecting drug users in Ukraine. Unlike other methods, the tree bootstrap depends only on the structure of the sampled recruitment trees, not on the attributes being measured on the respondents, so correlations between attributes can be estimated as well as variability. Our results suggest that it is possible to accurately assess the high level of uncertainty inherent in RDS.
Locality, bulk equations of motion and the conformal bootstrap
Kabat, Daniel
2016-01-01
We develop an approach to construct local bulk operators in a CFT to order 1/N^2. Since 4-point functions are not fixed by conformal invariance we use the OPE to categorize possible forms for a bulk operator. Using previous results on 3-point functions we construct a local bulk operator in each OPE channel. We then impose the condition that the bulk operators constructed in different channels agree, and hence give rise to a well-defined bulk operator. We refer to this condition as the "bulk bootstrap." We argue and explicitly show in some examples that the bulk bootstrap leads to some of the same results as the regular conformal bootstrap. In fact the bulk bootstrap provides an easier way to determine some CFT data, since it does not require knowing the form of the conformal blocks. This analysis clarifies previous results on the relation between bulk locality and the bootstrap for theories with a 1/N expansion, and it identifies a simple and direct way in which OPE coefficients and anomalous dimensions deter...
Unbiased bootstrap error estimation for linear discriminant analysis.
Vu, Thang; Sima, Chao; Braga-Neto, Ulisses M; Dougherty, Edward R
2014-12-01
Convex bootstrap error estimation is a popular tool for classifier error estimation in gene expression studies. A basic question is how to determine the weight for the convex combination between the basic bootstrap estimator and the resubstitution estimator such that the resulting estimator is unbiased at finite sample sizes. The well-known 0.632 bootstrap error estimator uses asymptotic arguments to propose a fixed 0.632 weight, whereas the more recent 0.632+ bootstrap error estimator attempts to set the weight adaptively. In this paper, we study the finite sample problem in the case of linear discriminant analysis under Gaussian populations. We derive exact expressions for the weight that guarantee unbiasedness of the convex bootstrap error estimator in the univariate and multivariate cases, without making asymptotic simplifications. Using exact computation in the univariate case and an accurate approximation in the multivariate case, we obtain the required weight and show that it can deviate significantly from the constant 0.632 weight, depending on the sample size and Bayes error for the problem. The methodology is illustrated by application on data from a well-known cancer classification study.
A bootstrap estimation scheme for chemical compositional data with nondetects
Palarea-Albaladejo, J; Martín-Fernández, J.A; Olea, Ricardo A.
2014-01-01
The bootstrap method is commonly used to estimate the distribution of estimators and their associated uncertainty when explicit analytic expressions are not available or are difficult to obtain. It has been widely applied in environmental and geochemical studies, where the data generated often represent parts of whole, typically chemical concentrations. This kind of constrained data is generically called compositional data, and they require specialised statistical methods to properly account for their particular covariance structure. On the other hand, it is not unusual in practice that those data contain labels denoting nondetects, that is, concentrations falling below detection limits. Nondetects impede the implementation of the bootstrap and represent an additional source of uncertainty that must be taken into account. In this work, a bootstrap scheme is devised that handles nondetects by adding an imputation step within the resampling process and conveniently propagates their associated uncertainly. In doing so, it considers the constrained relationships between chemical concentrations originated from their compositional nature. Bootstrap estimates using a range of imputation methods, including new stochastic proposals, are compared across scenarios of increasing difficulty. They are formulated to meet compositional principles following the log-ratio approach, and an adjustment is introduced in the multivariate case to deal with nonclosed samples. Results suggest that nondetect bootstrap based on model-based imputation is generally preferable. A robust approach based on isometric log-ratio transformations appears to be particularly suited in this context. Computer routines in the R statistical programming language are provided.
Locality, bulk equations of motion and the conformal bootstrap
Energy Technology Data Exchange (ETDEWEB)
Kabat, Daniel [Department of Physics and Astronomy, Lehman College, City University of New York,250 Bedford Park Blvd. W, Bronx NY 10468 (United States); Lifschytz, Gilad [Department of Mathematics, Faculty of Natural Science, University of Haifa,199 Aba Khoushy Ave., Haifa 31905 (Israel)
2016-10-18
We develop an approach to construct local bulk operators in a CFT to order 1/N{sup 2}. Since 4-point functions are not fixed by conformal invariance we use the OPE to categorize possible forms for a bulk operator. Using previous results on 3-point functions we construct a local bulk operator in each OPE channel. We then impose the condition that the bulk operators constructed in different channels agree, and hence give rise to a well-defined bulk operator. We refer to this condition as the “bulk bootstrap.” We argue and explicitly show in some examples that the bulk bootstrap leads to some of the same results as the regular conformal bootstrap. In fact the bulk bootstrap provides an easier way to determine some CFT data, since it does not require knowing the form of the conformal blocks. This analysis clarifies previous results on the relation between bulk locality and the bootstrap for theories with a 1/N expansion, and it identifies a simple and direct way in which OPE coefficients and anomalous dimensions determine the bulk equations of motion to order 1/N{sup 2}.
Moisture Management for High R-Value Walls
Energy Technology Data Exchange (ETDEWEB)
Lepage, R.; Schumacher, C.; Lukachko, A.
2013-11-01
The following report explains the moisture-related concerns for High R-value wall assemblies and discusses past Building America research work that informs this study. Hygrothermal simulations were prepared for several common approaches to High R-value wall construction in six cities (Houston, Atlanta, Seattle, St. Louis, Chicago, and International Falls) representing a range of climate zones (2, 3, 4C, 4, 5A, and 7, respectively). The simulations are informed by experience gained from past research in this area and validated by field measurement and forensic experience. The modeling program was developed to assess the moisture durability of the wall assemblies based on three primary sources of moisture: construction moisture, air leakage condensation, and bulk water leakage. The peak annual moisture content of the wood based exterior sheathing was used to comparatively analyze the response to the moisture loads for each of the walls in each given city. Walls which experienced sheathing moisture contents between 20% and 28% were identified as risky, whereas those exceeding 28% were identified as very high risk. All of the wall assemblies perform well under idealized conditions. However, only the walls with exterior insulation, or cavity insulation which provides a hygrothermal function similar to exterior insulation, perform adequately when exposed to moisture loads. Walls with only cavity insulation are particularly susceptible to air leakage condensation. None of the walls performed well when a precipitation based bulk water leak was introduced to the backside of the sheathing, emphasizing the importance of proper flashing details.
Gaussian process regression bootstrapping: exploring the effects of uncertainty in time course data.
Kirk, Paul D W; Stumpf, Michael P H
2009-05-15
Although widely accepted that high-throughput biological data are typically highly noisy, the effects that this uncertainty has upon the conclusions we draw from these data are often overlooked. However, in order to assign any degree of confidence to our conclusions, we must quantify these effects. Bootstrap resampling is one method by which this may be achieved. Here, we present a parametric bootstrapping approach for time-course data, in which Gaussian process regression (GPR) is used to fit a probabilistic model from which replicates may then be drawn. This approach implicitly allows the time dependence of the data to be taken into account, and is applicable to a wide range of problems. We apply GPR bootstrapping to two datasets from the literature. In the first example, we show how the approach may be used to investigate the effects of data uncertainty upon the estimation of parameters in an ordinary differential equations (ODE) model of a cell signalling pathway. Although we find that the parameter estimates inferred from the original dataset are relatively robust to data uncertainty, we also identify a distinct second set of estimates. In the second example, we use our method to show that the topology of networks constructed from time-course gene expression data appears to be sensitive to data uncertainty, although there may be individual edges in the network that are robust in light of present data. Matlab code for performing GPR bootstrapping is available from our web site: http://www3.imperial.ac.uk/theoreticalsystemsbiology/data-software/.
Yang, P.; Ng, T. L.; Yang, W.
2015-12-01
Effective water resources management depends on the reliable estimation of the uncertainty of drought events. Confidence intervals (CIs) are commonly applied to quantify this uncertainty. A CI seeks to be at the minimal length necessary to cover the true value of the estimated variable with the desired probability. In drought analysis where two or more variables (e.g., duration and severity) are often used to describe a drought, copulas have been found suitable for representing the joint probability behavior of these variables. However, the comprehensive assessment of the parameter uncertainties of copulas of droughts has been largely ignored, and the few studies that have recognized this issue have not explicitly compared the various methods to produce the best CIs. Thus, the objective of this study to compare the CIs generated using two widely applied uncertainty estimation methods, bootstrapping and Markov Chain Monte Carlo (MCMC). To achieve this objective, (1) the marginal distributions lognormal, Gamma, and Generalized Extreme Value, and the copula functions Clayton, Frank, and Plackett are selected to construct joint probability functions of two drought related variables. (2) The resulting joint functions are then fitted to 200 sets of simulated realizations of drought events with known distribution and extreme parameters and (3) from there, using bootstrapping and MCMC, CIs of the parameters are generated and compared. The effect of an informative prior on the CIs generated by MCMC is also evaluated. CIs are produced for different sample sizes (50, 100, and 200) of the simulated drought events for fitting the joint probability functions. Preliminary results assuming lognormal marginal distributions and the Clayton copula function suggest that for cases with small or medium sample sizes (~50-100), MCMC to be superior method if an informative prior exists. Where an informative prior is unavailable, for small sample sizes (~50), both bootstrapping and MCMC
Point Set Denoising Using Bootstrap-Based Radial Basis Function
Ramli, Ahmad; Abd. Majid, Ahmad
2016-01-01
This paper examines the application of a bootstrap test error estimation of radial basis functions, specifically thin-plate spline fitting, in surface smoothing. The presence of noisy data is a common issue of the point set model that is generated from 3D scanning devices, and hence, point set denoising is one of the main concerns in point set modelling. Bootstrap test error estimation, which is applied when searching for the smoothing parameters of radial basis functions, is revisited. The main contribution of this paper is a smoothing algorithm that relies on a bootstrap-based radial basis function. The proposed method incorporates a k-nearest neighbour search and then projects the point set to the approximated thin-plate spline surface. Therefore, the denoising process is achieved, and the features are well preserved. A comparison of the proposed method with other smoothing methods is also carried out in this study. PMID:27315105
Design and Implementation of a Bootstrap Trust Chain
Institute of Scientific and Technical Information of China (English)
YU Fajiang; ZHANG Huanguo
2006-01-01
The chain of trust in bootstrap process is the basis of whole system trust in the trusted computing group (TCG) definition. This paper presents a design and implementation of a bootstrap trust chain in PC based on the Windows and today' commodity hardware, merely depends on availability of an embedded security module (ESM). ESM and security enhanced BIOS is the root of trust, PMBR (Pre-MBR) checks the integrity of boot data and Windows kernel, which is a checking agent stored in ESM. In the end, the paper analyzed the mathematic expression of the chain of trust and the runtime performance compared with the common booting process. The trust chain bootstrap greatly strengthens the security of personal computer system, and affects the runtime performance with only adding about 12% booting time.
Benchmark of the bootstrap current simulation in helical plasmas
Huang, Botsz; Kanno, Ryutaro; Sugama, Hideo; Goto, Takuya
2016-01-01
The importance of the parallel momentum conservation on the bootstrap current evaluation in nonaxisymmetric systems is demonstrated by the benchmarks among the local drift-kinetic equation solvers, i.e., the Zero-Orbit-width(ZOW), DKES, and PENTA codes. The ZOW model is extended to include the ion parallel mean flow effect on the electron-ion parallel friction. Compared to the DKES model in which only the pitch-angle-scattering term is included in the collision operator, the PENTA model employs the Sugama-Nishimura method to correct the momentum balance. The ZOW and PENTA models agree each other well on the calculations of the bootstrap current. The DKES results without the parallel momentum conservation deviates significantly from those from the ZOW and PENTA models. This work verifies the reliability of the bootstrap current calculation with the ZOW and PENTA models for the helical plasmas.
Addressing the P2P Bootstrap Problem for Small Networks
Wolinsky, David Isaac; Boykin, P Oscar; Figueiredo, Renato
2010-01-01
P2P overlays provide a framework for building distributed applications consisting of few to many resources with features including self-configuration, scalability, and resilience to node failures. Such systems have been successfully adopted in large-scale services for content delivery networks, file sharing, and data storage. In small-scale systems, they can be useful to address privacy concerns and for network applications that lack dedicated servers. The bootstrap problem, finding an existing peer in the overlay, remains a challenge to enabling these services for small-scale P2P systems. In large networks, the solution to the bootstrap problem has been the use of dedicated services, though creating and maintaining these systems requires expertise and resources, which constrain their usefulness and make them unappealing for small-scale systems. This paper surveys and summarizes requirements that allow peers potentially constrained by network connectivity to bootstrap small-scale overlays through the use of e...
PyCFTBoot: A flexible interface for the conformal bootstrap
Behan, Connor
2016-01-01
We introduce PyCFTBoot, a wrapper designed to reduce the barrier to entry in conformal bootstrap calculations that require semidefinite programming. Symengine and SDPB are used for the most intensive symbolic and numerical steps respectively. After reviewing the built-in algorithms for conformal blocks, we explain how to use the code through a number of examples that verify past results. As an application, we show that the multi-correlator bootstrap still appears to single out the Wilson-Fisher fixed points as special theories in dimensions between 3 and 4 despite the recent proof that they violate unitarity.
Song, Hangke; Liu, Zhi; Du, Huan; Sun, Guangling; Le Meur, Olivier; Ren, Tongwei
2017-09-01
This paper proposes a novel depth-aware salient object detection and segmentation framework via multiscale discriminative saliency fusion (MDSF) and bootstrap learning for RGBD images (RGB color images with corresponding Depth maps) and stereoscopic images. By exploiting low-level feature contrasts, mid-level feature weighted factors and high-level location priors, various saliency measures on four classes of features are calculated based on multiscale region segmentation. A random forest regressor is learned to perform the discriminative saliency fusion (DSF) and generate the DSF saliency map at each scale, and DSF saliency maps across multiple scales are combined to produce the MDSF saliency map. Furthermore, we propose an effective bootstrap learning-based salient object segmentation method, which is bootstrapped with samples based on the MDSF saliency map and learns multiple kernel support vector machines. Experimental results on two large datasets show how various categories of features contribute to the saliency detection performance and demonstrate that the proposed framework achieves the better performance on both saliency detection and salient object segmentation.
Shen, Meiyu; Machado, Stella G
2017-01-01
Bioequivalence studies are an essential part of the evaluation of generic drugs. The most common in vivo bioequivalence study design is the two-period two-treatment crossover design. The observed drug concentration-time profile for each subject from each treatment under each sequence can be obtained. AUC (the area under the concentration-time curve) and Cmax (the maximum concentration) are obtained from the observed drug concentration-time profiles for each subject from each treatment under each sequence. However, such a drug concentration-time profile for each subject from each treatment under each sequence cannot possibly be available during the development of generic ophthalmic products since there is only one-time point measured drug concentration of aqueous humor for each eye. Instead, many subjects will be assigned to each of several prespecified sampling times. Then, the mean concentration at each sampling time can be obtained by the simple average of these subjects' observed concentration. One profile of the mean concentration vs. time can be obtained for one product (either the test or the reference product). One AUC value for one product can be calculated from the mean concentration-time profile using trapezoidal rules. This article develops a novel nonparametric method for obtaining the 90% confidence interval for the ratio of AUCT and AUCR (or CT,max/CR,max) in crossover studies by bootstrapping subjects at each time point with replacement or bootstrapping subjects at all sampling time points with replacement. Here T represents the test product, and R represents the reference product. It also develops a novel nonparametric method for estimating the standard errors (SEs) of AUCh and Ch,max in parallel studies by bootstrapping subjects treated by the hth product at each time point with replacement or bootstrapping subjects treated by the hth product at all sampling time points with replacement, h = T, R. Then, 90% confidence intervals for AUCT/AUCR and CT
Predicting disease risk using bootstrap ranking and classification algorithms.
Manor, Ohad; Segal, Eran
2013-01-01
Genome-wide association studies (GWAS) are widely used to search for genetic loci that underlie human disease. Another goal is to predict disease risk for different individuals given their genetic sequence. Such predictions could either be used as a "black box" in order to promote changes in life-style and screening for early diagnosis, or as a model that can be studied to better understand the mechanism of the disease. Current methods for risk prediction typically rank single nucleotide polymorphisms (SNPs) by the p-value of their association with the disease, and use the top-associated SNPs as input to a classification algorithm. However, the predictive power of such methods is relatively poor. To improve the predictive power, we devised BootRank, which uses bootstrapping in order to obtain a robust prioritization of SNPs for use in predictive models. We show that BootRank improves the ability to predict disease risk of unseen individuals in the Wellcome Trust Case Control Consortium (WTCCC) data and results in a more robust set of SNPs and a larger number of enriched pathways being associated with the different diseases. Finally, we show that combining BootRank with seven different classification algorithms improves performance compared to previous studies that used the WTCCC data. Notably, diseases for which BootRank results in the largest improvements were recently shown to have more heritability than previously thought, likely due to contributions from variants with low minimum allele frequency (MAF), suggesting that BootRank can be beneficial in cases where SNPs affecting the disease are poorly tagged or have low MAF. Overall, our results show that improving disease risk prediction from genotypic information may be a tangible goal, with potential implications for personalized disease screening and treatment.
Predicting disease risk using bootstrap ranking and classification algorithms.
Directory of Open Access Journals (Sweden)
Ohad Manor
Full Text Available Genome-wide association studies (GWAS are widely used to search for genetic loci that underlie human disease. Another goal is to predict disease risk for different individuals given their genetic sequence. Such predictions could either be used as a "black box" in order to promote changes in life-style and screening for early diagnosis, or as a model that can be studied to better understand the mechanism of the disease. Current methods for risk prediction typically rank single nucleotide polymorphisms (SNPs by the p-value of their association with the disease, and use the top-associated SNPs as input to a classification algorithm. However, the predictive power of such methods is relatively poor. To improve the predictive power, we devised BootRank, which uses bootstrapping in order to obtain a robust prioritization of SNPs for use in predictive models. We show that BootRank improves the ability to predict disease risk of unseen individuals in the Wellcome Trust Case Control Consortium (WTCCC data and results in a more robust set of SNPs and a larger number of enriched pathways being associated with the different diseases. Finally, we show that combining BootRank with seven different classification algorithms improves performance compared to previous studies that used the WTCCC data. Notably, diseases for which BootRank results in the largest improvements were recently shown to have more heritability than previously thought, likely due to contributions from variants with low minimum allele frequency (MAF, suggesting that BootRank can be beneficial in cases where SNPs affecting the disease are poorly tagged or have low MAF. Overall, our results show that improving disease risk prediction from genotypic information may be a tangible goal, with potential implications for personalized disease screening and treatment.
Identification, Characterization, and Palynology of High-Valued Medicinal Plants
Directory of Open Access Journals (Sweden)
Hina Fazal
2013-01-01
Full Text Available High-valued medicinal plants Achillea millefolium, Acorus calamus, Arnebia nobilis, Fumaria indica, Gymnema sylvestre, Origanum vulgare, Paeonia emodi, Peganum harmala, Psoralea corylifolia, Rauwolfia serpentina, and Vetiveria zizanioides were identified with the help of taxonomical markers and investigated for characterization and palynological studies. These parameters are used to analyze their quality, safety, and standardization for their safe use. Botanical description and crude drug description is intended for their quality assurance at the time of collection, commerce stages, manufacturing, and production. For this purpose the detailed morphology was studied and compared with the Flora of Pakistan and other available literatures. Here we reported the pollen grain morphology of Origanum vulgare, Paeonia emodi, Psoralea corylifolia, and Rauwolfia serpentina for the first time. Similarly the crude drug study of Gymnema sylvestre (leaf, Origanum vulgare (aerial parts, Paeonia emodi (tubers, and Peganum harmala (seeds was also carried out for the first time.
Continuous downstream processing for high value biological products: A Review.
Zydney, Andrew L
2016-03-01
There is growing interest in the possibility of developing truly continuous processes for the large-scale production of high value biological products. Continuous processing has the potential to provide significant reductions in cost and facility size while improving product quality and facilitating the design of flexible multi-product manufacturing facilities. This paper reviews the current state-of-the-art in separations technology suitable for continuous downstream bioprocessing, focusing on unit operations that would be most appropriate for the production of secreted proteins like monoclonal antibodies. This includes cell separation/recycle from the perfusion bioreactor, initial product recovery (capture), product purification (polishing), and formulation. Of particular importance are the available options, and alternatives, for continuous chromatographic separations. Although there are still significant challenges in developing integrated continuous bioprocesses, recent technological advances have provided process developers with a number of attractive options for development of truly continuous bioprocessing operations.
Bootstrap current for the edge pedestal plasma in a diverted tokamak geometry
Energy Technology Data Exchange (ETDEWEB)
Koh, S.; Choe, W. [Korea Advanced Institute of Science and Technology, Department of Physics, Daejeon 305-701 (Korea, Republic of); Chang, C. S.; Ku, S.; Menard, J. E. [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Weitzner, H. [Courant Institute of Mathematical Sciences, New York University, New York, New York 10012 (United States)
2012-07-15
The edge bootstrap current plays a critical role in the equilibrium and stability of the steep edge pedestal plasma. The pedestal plasma has an unconventional and difficult neoclassical property, as compared with the core plasma. It has a narrow passing particle region in velocity space that can be easily modified or destroyed by Coulomb collisions. At the same time, the edge pedestal plasma has steep pressure and electrostatic potential gradients whose scale-lengths are comparable with the ion banana width, and includes a magnetic separatrix surface, across which the topological properties of the magnetic field and particle orbits change abruptly. A drift-kinetic particle code XGC0, equipped with a mass-momentum-energy conserving collision operator, is used to study the edge bootstrap current in a realistic diverted magnetic field geometry with a self-consistent radial electric field. When the edge electrons are in the weakly collisional banana regime, surprisingly, the present kinetic simulation confirms that the existing analytic expressions [represented by O. Sauter et al., Phys. Plasmas 6, 2834 (1999)] are still valid in this unconventional region, except in a thin radial layer in contact with the magnetic separatrix. The agreement arises from the dominance of the electron contribution to the bootstrap current compared with ion contribution and from a reasonable separation of the trapped-passing dynamics without a strong collisional mixing. However, when the pedestal electrons are in plateau-collisional regime, there is significant deviation of numerical results from the existing analytic formulas, mainly due to large effective collisionality of the passing and the boundary layer trapped particles in edge region. In a conventional aspect ratio tokamak, the edge bootstrap current from kinetic simulation can be significantly less than that from the Sauter formula if the electron collisionality is high. On the other hand, when the aspect ratio is close to unity
Sidecoin: a snapshot mechanism for bootstrapping a blockchain
Krug, Joseph; Peterson, Jack
2015-01-01
Sidecoin is a mechanism that allows a snapshot to be taken of Bitcoin's blockchain. We compile a list of Bitcoin's unspent transaction outputs, then use these outputs and their corresponding balances to bootstrap a new blockchain. This allows the preservation of Bitcoin's economic state in the context of a new blockchain, which may provide new features and technical innovations.
Bootstrapping Rapidity Anomalous Dimensions for Transverse-Momentum Resummation
Energy Technology Data Exchange (ETDEWEB)
Li, Ye; Zhu, Hua Xing
2017-01-01
Soft function relevant for transverse-momentum resummation for Drell-Yan or Higgs production at hadron colliders are computed through to three loops in the expansion of strong coupling, with the help of bootstrap technique and supersymmetric decomposition. The corresponding rapidity anomalous dimension is extracted. An intriguing relation between anomalous dimensions for transverse-momentum resummation and threshold resummation is found.
Bootstrapping Rapidity Anomalous Dimension for Transverse-Momentum Resummation
Energy Technology Data Exchange (ETDEWEB)
Li, Ye [Fermilab; Zhu, Hua Xing [MIT, Cambridge, CTP
2016-04-05
Soft function relevant for transverse-momentum resummation for Drell-Yan or Higgs production at hadron colliders are computed through to three loops in the expansion of strong coupling, with the help of bootstrap technique and supersymmetric decomposition. The corresponding rapidity anomalous dimension is extracted. An intriguing relation between anomalous dimensions for transverse-momentum resummation and threshold resummation is found.
Metastability Thresholds for Anisotropic Bootstrap Percolation in Three Dimensions
Van Enter, A.C.D.; Fey, A.
2012-01-01
In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the orde
A Bootstrap Cointegration Rank Test for Panels of VAR Models
DEFF Research Database (Denmark)
Callot, Laurent
functions of the individual Cointegrated VARs (CVAR) models. A bootstrap based procedure is used to compute empirical distributions of the trace test statistics for these individual models. From these empirical distributions two panel trace test statistics are constructed. The satisfying small sample...
Finite-size effects for anisotropic bootstrap percolation : Logarithmic corrections
van Enter, Aernout C. D.; Hulshof, Tim
2007-01-01
In this note we analyse an anisotropic, two-dimensional bootstrap percolation model introduced by Gravner and Griffeath. We present upper and lower bounds on the finite-size effects. We discuss the similarities with the semi-oriented model introduced by Duarte.
Metastability thresholds for anisotropic bootstrap percolation in three dimensions
Van Enter, A.C.D.; Fey, A.
2012-01-01
In this paper we analyze several anisotropic bootstrap percolation models in three dimensions. We present the order of magnitude for the metastability thresholds for a fairly general class of models. In our proofs, we use an adaptation of the technique of dimensional reduction. We find that the orde
A Statistical Mechanics Approach to Approximate Analytical Bootstrap Averages
DEFF Research Database (Denmark)
Malzahn, Dorthe; Opper, Manfred
2003-01-01
We apply the replica method of Statistical Physics combined with a variational method to the approximate analytical computation of bootstrap averages for estimating the generalization error. We demonstrate our approach on regression with Gaussian processes and compare our results with averages...
Bootstrapping the energy flow in the beginning of life
Hengeveld, R.; Fedonkin, M.A.
2007-01-01
This paper suggests that the energy flow on which all living structures depend only started up slowly, the low-energy, initial phase starting up a second, slightly more energetic phase, and so on. In this way, the build up of the energy flow follows a bootstrapping process similar to that found in t
Bootstrapping the energy flow in the beginning of life
Hengeveld, R.; Fedonkin, M.A.
2007-01-01
This paper suggests that the energy flow on which all living structures depend only started up slowly, the low-energy, initial phase starting up a second, slightly more energetic phase, and so on. In this way, the build up of the energy flow follows a bootstrapping process similar to that found in
C*-Algebras over Topological Spaces: The Bootstrap Class
Meyer, Ralf
2007-01-01
We carefully define and study C*-algebras over topological spaces, possibly non-Hausdorff, and review some relevant results from point-set topology along the way. We explain the triangulated category structure on the bivariant Kasparov theory over a topological space. We introduce and describe an analogue of the bootstrap class for C*-algebras over a finite topological space.
Introducing Statistical Inference to Biology Students through Bootstrapping and Randomization
Lock, Robin H.; Lock, Patti Frazer
2008-01-01
Bootstrap methods and randomization tests are increasingly being used as alternatives to standard statistical procedures in biology. They also serve as an effective introduction to the key ideas of statistical inference in introductory courses for biology students. We discuss the use of such simulation based procedures in an integrated curriculum…
Sidecoin: a snapshot mechanism for bootstrapping a blockchain
Krug, Joseph; Peterson, Jack
2015-01-01
Sidecoin is a mechanism that allows a snapshot to be taken of Bitcoin's blockchain. We compile a list of Bitcoin's unspent transaction outputs, then use these outputs and their corresponding balances to bootstrap a new blockchain. This allows the preservation of Bitcoin's economic state in the context of a new blockchain, which may provide new features and technical innovations.
Dynamic Assessment of Vibration of Tooth Modification Gearbox Using Grey Bootstrap Method
Directory of Open Access Journals (Sweden)
Hui-liang Wang
2015-01-01
Full Text Available The correlation analysis between gear modification and vibration characteristics of transmission system was difficult to quantify; a novel small sample vibration of gearbox prediction method based on grey system theory and bootstrap theory was presented. The method characterized vibration base feature of tooth modification gearbox by developing dynamic uncertainty, estimated true value, and systematic error measure, and these parameters could indirectly dynamically evaluate the effect of tooth modification. The method can evaluate the vibration signal of gearbox with installation of no tooth modification gear and topological modification gear, respectively, considering that 100% reliability is the constraints condition and minimum average uncertainty is the target value. Computer simulation and experiment results showed that vibration amplitude of gearbox was decreased partly due to topological tooth modification, and each value of average dynamic uncertainty, mean true value, and systematic error measure was smaller than the no tooth modification value. The study provided an important guide for tooth modification, dynamic performance optimization.
Mean values of local operators in highly excited Bethe states
Pozsgay, B.
2011-01-01
We consider expectation values of local operators in (continuum) integrable models in a situation when the mean value is calculated in a single Bethe state with a large number of particles. We develop a form factor expansion for the thermodynamic limit of the mean value, which applies whenever the d
RANDOM QUADRATIC-FORMS AND THE BOOTSTRAP FOR U-STATISTICS
DEHLING, H; MIKOSCH, T
1994-01-01
We study the bootstrap distribution for U-statistics with special emphasis on the degenerate case. For the Efron bootstrap we give a short proof of the consistency using Mallows' metrics. We also study the i.i.d. weighted bootstrap [GRAPHICS] where (X(i)) and (xi(i)) are two i.i.d. sequences, indepe
Franco, Glaura C.; Reisen, Valderio A.
2007-03-01
This paper deals with different bootstrap approaches and bootstrap confidence intervals in the fractionally autoregressive moving average (ARFIMA(p,d,q)) process [J. Hosking, Fractional differencing, Biometrika 68(1) (1981) 165-175] using parametric and semi-parametric estimation techniques for the memory parameter d. The bootstrap procedures considered are: the classical bootstrap in the residuals of the fitted model [B. Efron, R. Tibshirani, An Introduction to the Bootstrap, Chapman and Hall, New York, 1993], the bootstrap in the spectral density function [E. Paparoditis, D.N Politis, The local bootstrap for periodogram statistics. J. Time Ser. Anal. 20(2) (1999) 193-222], the bootstrap in the residuals resulting from the regression equation of the semi-parametric estimators [G.C Franco, V.A Reisen, Bootstrap techniques in semiparametric estimation methods for ARFIMA models: a comparison study, Comput. Statist. 19 (2004) 243-259] and the Sieve bootstrap [P. Bühlmann, Sieve bootstrap for time series, Bernoulli 3 (1997) 123-148]. The performance of these procedures and confidence intervals for d in the stationary and non-stationary ranges are empirically obtained through Monte Carlo experiments. The bootstrap confidence intervals here proposed are alternative procedures with some accuracy to obtain confidence intervals for d.
Small scale, high value: Gnetum africanum and buchholzianum value chains in Cameroon
V. Ingram; L.N. Ndumbe; M.E Ewane
2012-01-01
The leaves of these Gnetum spp. lianas have long been harvested from humid forests for consumption and traded as a popular vegetable across the Congo Basin. Recent data on the current environmental, social and economic aspects of this forest product are however sparse. Value chain analysis was used
Small scale, high value: Gnetumafricanum and buchholzianum value chains in Cameroon
Ingram, V.J.; Ndumbe, L.N.; Ewane, M.E.
2012-01-01
The leaves of these Gnetum spp. lianas have long been harvested from humid forests for consumption and traded as a popular vegetable across the Congo Basin. Recent data on the current environmental, social and economic aspects of this forest product are however sparse. Value chain analysis was used
Gray bootstrap method for estimating frequency-varying random vibration signals with small samples
Directory of Open Access Journals (Sweden)
Wang Yanqing
2014-04-01
Full Text Available During environment testing, the estimation of random vibration signals (RVS is an important technique for the airborne platform safety and reliability. However, the available methods including extreme value envelope method (EVEM, statistical tolerances method (STM and improved statistical tolerance method (ISTM require large samples and typical probability distribution. Moreover, the frequency-varying characteristic of RVS is usually not taken into account. Gray bootstrap method (GBM is proposed to solve the problem of estimating frequency-varying RVS with small samples. Firstly, the estimated indexes are obtained including the estimated interval, the estimated uncertainty, the estimated value, the estimated error and estimated reliability. In addition, GBM is applied to estimating the single flight testing of certain aircraft. At last, in order to evaluate the estimated performance, GBM is compared with bootstrap method (BM and gray method (GM in testing analysis. The result shows that GBM has superiority for estimating dynamic signals with small samples and estimated reliability is proved to be 100% at the given confidence level.
BOOTSTRAP WAVELET IN THE NONPARAMETRIC REGRESSION MODEL WITH WEAKLY DEPENDENT PROCESSES
Institute of Scientific and Technical Information of China (English)
林路; 张润楚
2004-01-01
This paper introduces a method of bootstrap wavelet estimation in a nonparametric regression model with weakly dependent processes for both fixed and random designs. The asymptotic bounds for the bias and variance of the bootstrap wavelet estimators are given in the fixed design model. The conditional normality for a modified version of the bootstrap wavelet estimators is obtained in the fixed model. The consistency for the bootstrap wavelet estimator is also proved in the random design model. These results show that the bootstrap wavelet method is valid for the model with weakly dependent processes.
HIgh b-value and high Resolution Integrated Diffusion (HIBRID) imaging.
Fan, Qiuyun; Nummenmaa, Aapo; Polimeni, Jonathan R; Witzel, Thomas; Huang, Susie Y; Wedeen, Van J; Rosen, Bruce R; Wald, Lawrence L
2017-02-07
The parameter selection for diffusion MRI experiments is dominated by the "k-q tradeoff" whereby the Signal to Noise Ratio (SNR) of the images is traded for either high spatial resolution (determined by the maximum k-value collected) or high diffusion sensitivity (effected by b-value or the q vector) but usually not both. Furthermore, different brain regions (such as gray matter and white matter) likely require different tradeoffs between these parameters due to the size of the structures to be visualized or the length-scale of the microstructure being probed. In this case, it might be advantageous to combine information from two scans - a scan with high q but low k (high angular resolution in diffusion but low spatial resolution in the image domain) to provide maximal information about white matter fiber crossing, and one low q but high k (low angular resolution but high spatial resolution) for probing the cortex. In this study, we propose a method, termed HIgh b-value and high Resolution Integrated Diffusion (HIBRID) imaging, for acquiring and combining the information from these two complementary types of scan with the goal of studying diffusion in the cortex without compromising white matter fiber information. The white-gray boundary and pial surface obtained from anatomical scans are incorporated as prior information to guide the fusion. We study the complementary advantages of the fused datasets, and assess the quality of the HIBRID data compared to either alone.
Bootstrapping GEE models for fMRI regional connectivity.
D'Angelo, Gina M; Lazar, Nicole A; Zhou, Gongfu; Eddy, William F; Morris, John C; Sheline, Yvette I
2012-12-01
An Alzheimer's fMRI study has motivated us to evaluate inter-regional correlations during rest between groups. We apply generalized estimating equation (GEE) models to test for differences in regional correlations across groups. Both the GEE marginal model and GEE transition model are evaluated and compared to the standard pooling Fisher-z approach using simulation studies. Standard errors of all methods are estimated both theoretically (model-based) and empirically (bootstrap). Of all the methods, we find that the transition models have the best statistical properties. Overall, the model-based standard errors and bootstrap standard errors perform about the same. We also demonstrate the methods with a functional connectivity study in a healthy cognitively normal population of ApoE4+ participants and ApoE4- participants who are recruited from the Adult Children's Study conducted at the Washington University Knight Alzheimer's Disease Research Center.
Bootstrapping the Coronal Magnetic Field with STEREO/EUVI
Aschwanden, Markus; Sandman, Anne
2010-05-01
The 3D coronal magnetic field obtained from stereoscopically triangulated loops has been compared with standard photospheric magnetogram extrapolations. We found a large misalignment of 20-40 deg, depending on the complexity of an AR (Sandman et al. 2009; DeRosa et al. 2009). These studies prove that the magnetic field in the photosphere is not force-free and fundamentally cannot reproduce the coronal magnetic field. Bootstrapping with coronal loop 3D geometries are required to improve modeling of the coronal field. Such coronal field bootstrapping methods are currently developed using stereoscopically triangulated loops from STEREO/EUVI and preliminary results show already a significantly reduced misalignment of 10-20 deg.
Bootstrap bound for conformal multi-flavor QCD on lattice
Nakayama, Yu
2016-01-01
The recent work by Iha et al shows an upper bound on mass anomalous dimension $\\gamma_m$ of multi-flavor massless QCD at the renormalization group fixed point from the conformal bootstrap in $SU(N_F)_V$ symmetric conformal field theories under the assumption that the fixed point is realizable with the lattice regularization based on staggered fermions. We show that the almost identical but slightly stronger bound applies to the regularization based on Wilson fermions (or domain wall fermions) by studying the conformal bootstrap in $SU(N_f)_L \\times SU(N_f)_R$ symmetric conformal field theories. For $N_f=8$, our bound implies $\\gamma_m < 1.31$ to avoid dangerously irrelevant operators that are not compatible with the lattice symmetry.
Sisvar: a Guide for its Bootstrap procedures in multiple comparisons
Directory of Open Access Journals (Sweden)
Daniel Furtado Ferreira
2014-04-01
Full Text Available Sisvar is a statistical analysis system with a large usage by the scientific community to produce statistical analyses and to produce scientific results and conclusions. The large use of the statistical procedures of Sisvar by the scientific community is due to it being accurate, precise, simple and robust. With many options of analysis, Sisvar has a not so largely used analysis that is the multiple comparison procedures using bootstrap approaches. This paper aims to review this subject and to show some advantages of using Sisvar to perform such analysis to compare treatments means. Tests like Dunnett, Tukey, Student-Newman-Keuls and Scott-Knott are performed alternatively by bootstrap methods and show greater power and better controls of experimentwise type I error rates under non-normal, asymmetric, platykurtic or leptokurtic distributions.
Bootstrap bound for conformal multi-flavor QCD on lattice
Energy Technology Data Exchange (ETDEWEB)
Nakayama, Yu [Department of Physics, Rikkyo University,Toshima, Tokyo 171-8501 (Japan); Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo,5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8583 (Japan)
2016-07-08
The recent work by Iha et al. shows an upper bound on mass anomalous dimension γ{sub m} of multi-flavor massless QCD at the renormalization group fixed point from the conformal bootstrap in SU(N{sub F}){sub V} symmetric conformal field theories under the assumption that the fixed point is realizable with the lattice regularization based on staggered fermions. We show that the almost identical but slightly stronger bound applies to the regularization based on Wilson fermions (or domain wall fermions) by studying the conformal bootstrap in SU(N{sub f}){sub L}×SU(N{sub f}){sub R} symmetric conformal field theories. For N{sub f}=8, our bound implies γ{sub m}<1.31 to avoid dangerously irrelevant operators that are not compatible with the lattice symmetry.
Bolasso: model consistent Lasso estimation through the bootstrap
Bach, Francis
2008-01-01
We consider the least-square linear regression problem with regularization by the l1-norm, a problem usually referred to as the Lasso. In this paper, we present a detailed asymptotic analysis of model consistency of the Lasso. For various decays of the regularization parameter, we compute asymptotic equivalents of the probability of correct model selection (i.e., variable selection). For a specific rate decay, we show that the Lasso selects all the variables that should enter the model with probability tending to one exponentially fast, while it selects all other variables with strictly positive probability. We show that this property implies that if we run the Lasso for several bootstrapped replications of a given sample, then intersecting the supports of the Lasso bootstrap estimates leads to consistent model selection. This novel variable selection algorithm, referred to as the Bolasso, is compared favorably to other linear regression methods on synthetic data and datasets from the UCI machine learning rep...
Conformal bootstrap: non-perturbative QFT's under siege
CERN. Geneva
2016-01-01
[Exceptionally in Council Chamber] Originally formulated in the 70's, the conformal bootstrap is the ambitious idea that one can use internal consistency conditions to carve out, and eventually solve, the space of conformal field theories. In this talk I will review recent developments in the field which have boosted this program to a new level. I will present a method to extract quantitative informations in strongly-interacting theories, such as 3D Ising, O(N) vector model and even systems without a Lagrangian formulation. I will explain how these techniques have led to the world record determination of several critical exponents. Finally, I will review exact analytical results obtained using bootstrap techniques.
On Comparison of Stochastic Reserving Methods with Bootstrapping
Directory of Open Access Journals (Sweden)
Liivika Tee
2017-01-01
Full Text Available We consider the well-known stochastic reserve estimation methods on the basis of generalized linear models, such as the (over-dispersed Poisson model, the gamma model and the log-normal model. For the likely variability of the claims reserve, bootstrap method is considered. In the bootstrapping framework, we discuss the choice of residuals, namely the Pearson residuals, the deviance residuals and the Anscombe residuals. In addition, several possible residual adjustments are discussed and compared in a case study. We carry out a practical implementation and comparison of methods using real-life insurance data to estimate reserves and their prediction errors. We propose to consider proper scoring rules for model validation, and the assessments will be drawn from an extensive case study.
Directory of Open Access Journals (Sweden)
Xintao Xia
2013-07-01
Full Text Available This study proposed the bootstrap maximum-entropy method to evaluate the uncertainty of the starting torque of a slewing bearing. Addressing the variation coefficient of the slewing bearing starting torque under load, the probability density function, estimated true value and variation domain are obtained through experimental investigation of the slewing bearing starting torque under various loads. The probability density function is found to be characterized by variational figure, scale and location. In addition, the estimated true value and the variation domain vary from large to small along with increasing load, indicating better evolution of the stability and reliability of the starting friction torque. Finally, a sensitive spot exists where the estimated true value and the variation domain rise abnormally, showing a fluctuation in the immunity and a degenerative disorder in the stability and reliability of the starting friction torque.
Bootstrap Determination of the Co-Integration Rank in Heteroskedastic VAR Models
DEFF Research Database (Denmark)
Cavaliere, Giuseppe; Rahbek, Anders; Taylor, A. M. Robert
In a recent paper Cavaliere et al. (2012) develop bootstrap implementations of the (pseudo-) likelihood ratio [PLR] co-integration rank test and associated sequential rank determination procedure of Johansen (1996). The bootstrap samples are constructed using the restricted parameter estimates...... of the underlying VAR model which obtain under the reduced rank null hypothesis. They propose methods based on an i.i.d. bootstrap re-sampling scheme and establish the validity of their proposed bootstrap procedures in the context of a co-integrated VAR model with i.i.d. innovations. In this paper we investigate...... the properties of their bootstrap procedures, together with analogous procedures based on a wild bootstrap re-sampling scheme, when time-varying behaviour is present in either the conditional or unconditional variance of the innovations. We show that the bootstrap PLR tests are asymptotically correctly sized and...
Non-critical string, Liouville theory and geometric bootstrap hypothesis
Hadasz, L; Hadasz, Leszek; Jaskolski, Zbigniew
2003-01-01
Basing on the standard construction of critical string amplitudes we analyze properties of the longitudinal sector of the non-critical Nambu-Goto string. We demonstrate that it cannot be described by standard (in the sense of BPZ) conformal field theory. As an alternative we propose a new version of the geometric approach to Liouville theory and formulate its basic consistency condition - the geometric bootstrap equation.
Bootstrapping a Five-Loop Amplitude from Steinmann Relations
Caron-Huot, Simon; McLeod, Andrew; von Hippel, Matt
2016-01-01
The analytic structure of scattering amplitudes is restricted by Steinmann relations, which enforce the vanishing of certain discontinuities of discontinuities. We show that these relations dramatically simplify the function space for the hexagon function bootstrap in planar maximally supersymmetric Yang-Mills theory. Armed with this simplification, along with the constraints of dual conformal symmetry and Regge exponentiation, we obtain the complete five-loop six-particle amplitude.
Higgs Critical Exponents and Conformal Bootstrap in Four Dimensions
DEFF Research Database (Denmark)
Antipin, Oleg; Mølgaard, Esben; Sannino, Francesco
2015-01-01
We investigate relevant properties of composite operators emerging in nonsupersymmetric, four-dimensional gauge-Yukawa theories with interacting conformal fixed points within a precise framework. The theories investigated in this work are structurally similar to the standard model of particle int...... bootstrap results are then compared to precise four dimensional conformal field theoretical results. To accomplish this, it was necessary to calculate explicitly the crossing symmetry relations for the global symmetry group SU($N$)$\\times$SU($N$)....
Efficient generation of pronunciation dictionaries: machine learning factors during bootstrapping
CSIR Research Space (South Africa)
Davel, MH
2004-10-01
Full Text Available significantly. Further work relates to ex- ploring the ways in which the algorithmic requirements change for different phases of the bootstrapping process. 6. Acknowledgements This work was supported by the CSIR Information Society Technologies Centre... automatically,? in Proceedings of the International Conference on Acoustics and Speech Signal Processing (ICASSP), Minneapolis, 1993, vol. 2, pp. 199? 202. [5] T.J. Sejnowski and C.R. Rosenberg, ?Parallel networks that learn to pronounce english text...
A conformal bootstrap approach to critical percolation in two dimensions
Picco, Marco; Santachiara, Raoul
2016-01-01
We study four-point functions of critical percolation in two dimensions, and more generally of the Potts model. We propose an exact ansatz for the spectrum: an infinite, discrete and non-diagonal combination of representations of the Virasoro algebra. Based on this ansatz, we compute four-point functions using a numerical conformal bootstrap approach. The results agree with Monte-Carlo computations of connectivities of random clusters.
Retaining the Value of PV at High Penetration Workshop
Energy Technology Data Exchange (ETDEWEB)
Kurtz, Sarah; Bolen, Michael
2016-10-13
PV prices have dropped and are now attractive without incentives for peaking applications in some locations. Modeling suggests and, empirically, some regions demonstrate that as PV penetration increases its value decreases, predominantly due to a decrease in energy and capacity value. It is not apparent what technologies and price may be needed for PV to supply tens of percent of electricity in the most economically efficient manner. A 1-day workshop was co-sponsored by EPRI and NREL with support from ASU. A dozen presentations and discussions introduced how the interplay of various technologies impact the value of PV, identified technical challenges and gaps impeding implementation, and discussed future R&D needs and opportunities.
Truncatable bootstrap equations in algebraic form and critical surface exponents
Gliozzi, Ferdinando
2016-01-01
We describe examples of drastic truncations of conformal bootstrap equations encoding much more information than that obtained by a direct numerical approach. A three-term truncation of the four point function of a free scalar in any space dimensions provides algebraic identities among conformal block derivatives which generate the exact spectrum of the infinitely many primary operators contributing to it. In boundary conformal field theories, we point out that the appearance of free parameters in the solutions of bootstrap equations is not an artifact of truncations, rather it reflects a physical property of permeable conformal interfaces which are described by the same equations. Surface transitions correspond to isolated points in the parameter space. We are able to locate them in the case of 3d Ising model, thanks to a useful algebraic form of 3d boundary bootstrap equations. It turns out that the low-lying spectra of the surface operators in the ordinary and the special transitions of 3d Ising model form...
Soybean yield modeling using bootstrap methods for small samples
Energy Technology Data Exchange (ETDEWEB)
Dalposso, G.A.; Uribe-Opazo, M.A.; Johann, J.A.
2016-11-01
One of the problems that occur when working with regression models is regarding the sample size; once the statistical methods used in inferential analyzes are asymptotic if the sample is small the analysis may be compromised because the estimates will be biased. An alternative is to use the bootstrap methodology, which in its non-parametric version does not need to guess or know the probability distribution that generated the original sample. In this work we used a set of soybean yield data and physical and chemical soil properties formed with fewer samples to determine a multiple linear regression model. Bootstrap methods were used for variable selection, identification of influential points and for determination of confidence intervals of the model parameters. The results showed that the bootstrap methods enabled us to select the physical and chemical soil properties, which were significant in the construction of the soybean yield regression model, construct the confidence intervals of the parameters and identify the points that had great influence on the estimated parameters. (Author)
Truncatable bootstrap equations in algebraic form and critical surface exponents
Gliozzi, Ferdinando
2016-10-01
We describe examples of drastic truncations of conformal bootstrap equations encoding much more information than that obtained by a direct numerical approach. A three-term truncation of the four point function of a free scalar in any space dimensions provides algebraic identities among conformal block derivatives which generate the exact spectrum of the infinitely many primary operators contributing to it. In boundary conformal field theories, we point out that the appearance of free parameters in the solutions of bootstrap equations is not an artifact of truncations, rather it reflects a physical property of permeable conformal interfaces which are described by the same equations. Surface transitions correspond to isolated points in the parameter space. We are able to locate them in the case of 3d Ising model, thanks to a useful algebraic form of 3d boundary bootstrap equations. It turns out that the low-lying spectra of the surface operators in the ordinary and the special transitions of 3d Ising model form two different solutions of the same polynomial equation. Their interplay yields an estimate of the surface renormalization group exponents, y h = 0 .72558(18) for the ordinary universality class and y h = 1 .646(2) for the special universality class, which compare well with the most recent Monte Carlo calculations. Estimates of other surface exponents as well as OPE coefficients are also obtained.
Truncatable bootstrap equations in algebraic form and critical surface exponents
Energy Technology Data Exchange (ETDEWEB)
Gliozzi, Ferdinando [Dipartimento di Fisica, Università di Torino andIstituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1, Torino, I-10125 (Italy)
2016-10-10
We describe examples of drastic truncations of conformal bootstrap equations encoding much more information than that obtained by a direct numerical approach. A three-term truncation of the four point function of a free scalar in any space dimensions provides algebraic identities among conformal block derivatives which generate the exact spectrum of the infinitely many primary operators contributing to it. In boundary conformal field theories, we point out that the appearance of free parameters in the solutions of bootstrap equations is not an artifact of truncations, rather it reflects a physical property of permeable conformal interfaces which are described by the same equations. Surface transitions correspond to isolated points in the parameter space. We are able to locate them in the case of 3d Ising model, thanks to a useful algebraic form of 3d boundary bootstrap equations. It turns out that the low-lying spectra of the surface operators in the ordinary and the special transitions of 3d Ising model form two different solutions of the same polynomial equation. Their interplay yields an estimate of the surface renormalization group exponents, y{sub h}=0.72558(18) for the ordinary universality class and y{sub h}=1.646(2) for the special universality class, which compare well with the most recent Monte Carlo calculations. Estimates of other surface exponents as well as OPE coefficients are also obtained.
Necessary Condition for Emergent Symmetry from the Conformal Bootstrap
Nakayama, Yu; Ohtsuki, Tomoki
2016-09-01
We use the conformal bootstrap program to derive the necessary conditions for emergent symmetry enhancement from discrete symmetry (e.g., Zn ) to continuous symmetry [e.g., U (1 )] under the renormalization group flow. In three dimensions, in order for Z2 symmetry to be enhanced to U (1 ) symmetry, the conformal bootstrap program predicts that the scaling dimension of the order parameter field at the infrared conformal fixed point must satisfy Δ1>1.08 . We also obtain the similar necessary conditions for Z3 symmetry with Δ1>0.580 and Z4 symmetry with Δ1>0.504 from the simultaneous conformal bootstrap analysis of multiple four-point functions. As applications, we show that our necessary conditions impose severe constraints on the nature of the chiral phase transition in QCD, the deconfinement criticality in Néel valence bond solid transitions, and anisotropic deformations in critical O (n ) models. We prove that some fixed points proposed in the literature are unstable under the perturbation that cannot be forbidden by the discrete symmetry. In these situations, the second-order phase transition with enhanced symmetry cannot happen.
CME Velocity and Acceleration Error Estimates Using the Bootstrap Method
Michalek, Grzegorz; Gopalswamy, Nat; Yashiro, Seiji
2017-08-01
The bootstrap method is used to determine errors of basic attributes of coronal mass ejections (CMEs) visually identified in images obtained by the Solar and Heliospheric Observatory (SOHO) mission's Large Angle and Spectrometric Coronagraph (LASCO) instruments. The basic parameters of CMEs are stored, among others, in a database known as the SOHO/LASCO CME catalog and are widely employed for many research studies. The basic attributes of CMEs ( e.g. velocity and acceleration) are obtained from manually generated height-time plots. The subjective nature of manual measurements introduces random errors that are difficult to quantify. In many studies the impact of such measurement errors is overlooked. In this study we present a new possibility to estimate measurements errors in the basic attributes of CMEs. This approach is a computer-intensive method because it requires repeating the original data analysis procedure several times using replicate datasets. This is also commonly called the bootstrap method in the literature. We show that the bootstrap approach can be used to estimate the errors of the basic attributes of CMEs having moderately large numbers of height-time measurements. The velocity errors are in the vast majority small and depend mostly on the number of height-time points measured for a particular event. In the case of acceleration, the errors are significant, and for more than half of all CMEs, they are larger than the acceleration itself.
Parametric bootstrapping for biological sequence motifs.
O'Neill, Patrick K; Erill, Ivan
2016-10-06
Biological sequence motifs drive the specific interactions of proteins and nucleic acids. Accordingly, the effective computational discovery and analysis of such motifs is a central theme in bioinformatics. Many practical questions about the properties of motifs can be recast as random sampling problems. In this light, the task is to determine for a given motif whether a certain feature of interest is statistically unusual among relevantly similar alternatives. Despite the generality of this framework, its use has been frustrated by the difficulties of defining an appropriate reference class of motifs for comparison and of sampling from it effectively. We define two distributions over the space of all motifs of given dimension. The first is the maximum entropy distribution subject to mean information content, and the second is the truncated uniform distribution over all motifs having information content within a given interval. We derive exact sampling algorithms for each. As a proof of concept, we employ these sampling methods to analyze a broad collection of prokaryotic and eukaryotic transcription factor binding site motifs. In addition to positional information content, we consider the informational Gini coefficient of the motif, a measure of the degree to which information is evenly distributed throughout a motif's positions. We find that both prokaryotic and eukaryotic motifs tend to exhibit higher informational Gini coefficients (IGC) than would be expected by chance under either reference distribution. As a second application, we apply maximum entropy sampling to the motif p-value problem and use it to give elementary derivations of two new estimators. Despite the historical centrality of biological sequence motif analysis, this study constitutes to our knowledge the first use of principled null hypotheses for sequence motifs given information content. Through their use, we are able to characterize for the first time differerences in global motif statistics
Where is the value in high frequency trading?
Álvaro Cartea; José Penalva
2011-01-01
We analyze the impact of high frequency trading in financial markets based on a model with three types of traders: liquidity traders, market makers, and high frequency traders. Our four main findings are: i) The price impact of the liquidity trades is higher in the presence of the high frequency trader and is increasing with the size of the trade. In particular, we show that the high frequency trader reduces (increases) the prices that liquidity traders receive when selling (buying) their equ...
High-value renewable energy from prairie grasses
Energy Technology Data Exchange (ETDEWEB)
McLaughlin Jr, Samuel B [ORNL; De La Torre Ugarte, D. [University of Tennessee; Garten Jr, Charles T [ORNL; Lynd, L. [Dartmouth College; Sanderson, M. [USDA ARS; Tolbert, Virginia R [ORNL; Wolf, D. [Virginia Polytechnic Institute and State University (Virginia Tech)
2002-05-01
Projected economic benefits of renewable energy derived from a native prairie grass, switchgrass, include nonmarket values that can reduce net fuel costs to near zero. At a farm gate price of $44.00/dry Mg, an agricultural sector model predicts higher profits for switchgrass than conventional crops on 16.9 million hectares (ha). Benefits would include an annual increase of $6 billion in net farm returns, a $1.86 billion reduction in government subsidies, and displacement of 44-159 Tg/year (1 Tg = 10{sup 12} g) of greenhouse gas emissions. Incorporating these values into the pricing structure for switchgrass bioenergy could accelerate commercialization and provide net benefits to the U.S. economy.
Bootstrap 方法建立生物参考区间的研究%Estimation of reference intervals by bootstrap methods
Institute of Scientific and Technical Information of China (English)
李小佩; 王建新; 施秀英; 王惠民
2016-01-01
目的：探讨Bootstrap方法建立生物参考区间的可行性及最少样本量。方法选取120例健康者检测血清尿素（BUN），采用美国临床和实验室标准协会（CLSI）C28‐A3推荐参数、非参数方法及Bootstrap方法建立参考区间；计算参考区间上下限值、均方根误差（RMSE）、精密度比值（Id ）等指标，研究Bootstrap方法建立参考区间最少样本量。结果非参数、参数、Bootstrap百分位数、Bootstrap标准方法建立参考区间分别为3．00～7．39 mmol／L、3．05～7．33 mmol／L、3．12～7．18 mmol／L、3．10～7．33 mmol／L ，参考区间覆盖率大于95％，Bootstrap方法与C28‐A3推荐方法结果一致；进一步研究发现随着样本量减少，参考区间增宽、RMSE和Id 逐渐升高，样本量减少到60时结果稳定。结论 Bootstrap方法可应用于各种数据分布类型生物参考区间的建立，在小样本量时有一定优势，为临床实验室制订参考区间提供了新思路。%Objective To research the bootstrap methods for reference intervals calculation are available and the minimum samples .Methods The concentrations of serum ureanitrogen(BUN) levels in 120 healthy reference subjects were determined and the reference intervals of BUN were calculated .Comparisons between results from par‐ametric and nonparametric method which were recommended by Clinical and Laboratory Standards Institute(CLSI) C28‐A3 and bootstrap methods .Reference interval limit and the values of RMSE ,Id were performed using RefValAdv to identify the minimum number of samples .Results The reference intervals calculated by nonparametric and para‐metric methods ,percentile and standard bootstrap methods were 3 .00-7 .39 mmol/L ,3 .05 -7 .33 mmol/L ,3 .12-7 .18 mmol/L ,3 .10 -7 .33 mmol/L respectively ,results were basically consistent .Overlap between reference inter‐vals were greater than 95% .The values of RMSE and Id increased ,the reference
Lenardic, A.; Hoink, T.
2008-12-01
Several studies have highlighted the role of a low viscosity asthenosphere in promoting plate-like behavior in mantle convection models. It has also been argued that the asthenosphere is fed by mantle plumes (Phipps- Morgan et al. 1993; Deffeyes 1972) and that the existence of the specific plume types required for this depends on plate subduction (Lenardic and Kaula 1995; Jellinek et al. 2002). Independent of plumes, plate subduction can generate a non-adiabatic temperature gradient which, together with temperature dependent mantle viscosity, leads to a low viscosity near surface region. The above suggests a conceptual model in which the asthenosphere can not be defined solely in terms of material properties but must also be defined in terms of an active process, plate tectonics, which both maintains it and is maintained by it. The bootstrap aspect of the model is its circular causality between plates and the asthenosphere, neither being more fundamental than the other and the existence of each depending on the other. Several of the feedbacks key to the conceptual model will be quantified. The implications for modeling mantle convection in a plate-tectonic mode will also be discussed: 1) A key is to get numerical simulations into the bootstrap mode of operation and this is dependent on assumed initial conditions; 2) The model implies potentially strong hysteresis effects (e.g., transition between convection states, associated with variable yield stress, will occur at different values depending on whether the yield stress is systematically lowered or raised between successive models).
Bootstrap inversion for Pn wave velocity in North-Western Italy
Directory of Open Access Journals (Sweden)
C. Eva
1997-06-01
Full Text Available An inversion of Pn arrival times from regional distance earthquakes (180-800 km, recorded by 94 seismic stations operating in North-Western Italy and surrounding areas, was carried out to image lateral variations of P-wave velocity at the crust-mantle boundary, and to estimate the static delay time at each station. The reliability of the obtained results was assessed using both synthetic tests and the bootstrap Monte Carlo resampling technique. Numerical simulations demonstrated the existence of a trade-off between cell velocities and estimated station delay times along the edge of the model. Bootstrap inversions were carried out to determine the standard deviation of velocities and time terms. Low Pn velocity anomalies are detected beneath the outer side of the Alps (-6% and the Western Po plain (-4% in correspondence with two regions of strong crustal thickening and negative Bouguer anomaly. In contrast, high Pn velocities are imaged beneath the inner side of the Alps (+4% indicating the presence of high velocity and density lower crust-upper mantle. The Ligurian sea shows high Pn velocities close to the Ligurian coastlines (+3% and low Pn velocities (-1.5% in the middle of the basin in agreement with the upper mantle velocity structure revealed by seismic refraction profiles.
Valuing queer identity in Monster High doll fandom
Directory of Open Access Journals (Sweden)
Sara Mariel Austin
2016-09-01
Full Text Available According to Mattel, Monster High dolls topped $500 million in annual sales in 2014, quickly gaining on Barbie, whose $1.3 billion in annual revenue plummeted for the fourth quarter in a row. Monster High's recent ad campaign claims, "We are monsters. We are proud." Race, ethnicity, and disability are coded into the dolls as selling points. The allure of Monster High is, in part, that political identity and the celebration of difference become consumable. The female body, the racialized body, and the disabled body have long been coded as monstrous. Monster High reclaims this label, queering it. Using Jack Halberstam's work on children's culture and Richard Berger's and Rosalind Hanmer's work on fandom, this article explores the queer potential of Monster High. Fans rewrite the Mattel narrative through fan fiction, repainting the dolls, and embodying them through virtual avatars, makeup, and costume play. These fan practices both queer the dolls' identity politics and create communities of interest that act as safe spaces for expressing queer identity and generating fan activism. These fan practices have also influenced Mattel's branding of the dolls, specifically with the recent inclusion of activism campaigns such as WeStopHate and The Kind Campaign into the Monster High Webisodes and Web site. By exploring the queer politics of Monster High fandom, this paper explains how that queering generates social change.
Valuing queer identity in Monster High doll fandom
Directory of Open Access Journals (Sweden)
Sara Mariel Austin
2016-08-01
Full Text Available According to Mattel, Monster High dolls topped $500 million in annual sales in 2014, quickly gaining on Barbie, whose $1.3 billion in annual revenue plummeted for the fourth quarter in a row. Monster High's recent ad campaign claims, "We are monsters. We are proud." Race, ethnicity, and disability are coded into the dolls as selling points. The allure of Monster High is, in part, that political identity and the celebration of difference become consumable. The female body, the racialized body, and the disabled body have long been coded as monstrous. Monster High reclaims this label, queering it. Using Jack Halberstam's work on children's culture and Richard Berger's and Rosalind Hanmer's work on fandom, this article explores the queer potential of Monster High. Fans rewrite the Mattel narrative through fan fiction, repainting the dolls, and embodying them through virtual avatars, makeup, and costume play. These fan practices both queer the dolls' identity politics and create communities of interest that act as safe spaces for expressing queer identity and generating fan activism. These fan practices have also influenced Mattel's branding of the dolls, specifically with the recent inclusion of activism campaigns such as WeStopHate and The Kind Campaign into the Monster High Webisodes and Web site. By exploring the queer politics of Monster High fandom, this paper explains how that queering generates social change.
Hart Mountain - Protecting High Value Shrub-steppe Habitat
US Fish and Wildlife Service, Department of the Interior — In fiscal year 2012 a high capacity skid-mounted spray system and herbicide was purchased. A contract for herbicide application was awarded to a local non-profit...
Highly Valued Degrees at California State University, Long Beach
Dowell, David A.
2016-01-01
In 2014, California State University, Long Beach (CSULB) received the national award from the American Association of State Colleges and Universities (AASCU) for Excellence and Innovation in Student Success and Completion, recognizing record high graduation rates with a diverse student population, significantly above comparable institutions.…
Two novel applications of bootstrap currents: Snakes and jitter stabilization
Energy Technology Data Exchange (ETDEWEB)
Thyagaraja, A.; Haas, F.A. (AEA Fusion (AEA Fusion/Euratom Fusion Association), Culham Laboratory, Abingdon, OX14 3DB (United Kingdom))
1993-09-01
Both neoclassical theory and certain turbulence theories of particle transport in tokamaks predict the existence of bootstrap (i.e., pressure-driven) currents. Two new applications of this form of noninductive current are considered in this work. In the first, an earlier model of the nonlinearly saturated [ital m]=1 tearing mode is extended to include the stabilizing effect of a bootstrap current [ital inside] the island. This is used to explain several observed features of the so-called snake'' reported in the Joint European Torus (JET) [R. D. Gill, A. W. Edwards, D. Pasini, and A. Weller, Nucl. Fusion [bold 32], 723 (1992)]. The second application involves an alternating current (ac) form of bootstrap current, produced by pressure-gradient fluctuations. It is suggested that a time-dependent (in the plasma frame), radio-frequency (rf) power source can be used to produce localized pressure fluctuations of suitable frequency and amplitude to implement the dynamic stabilization method for suppressing gross modes in tokamaks suggested in a recent paper [A. Thyagaraja, R. D. Hazeltine, and A. Y. Aydemir, Phys. Fluids B [bold 4], 2733 (1992)]. This method works by detuning'' the resonant layer by rapid current/shear fluctuations. Estimates made for the power source requirements both for small machines such as COMPASS and for larger machines like JET suggest that the method could be practically feasible. This jitter'' (i.e., dynamic) stabilization method could provide a useful form of active instability control to avoid both gross/disruptive and fine-scale/transportive instabilities, which may set severe operating/safety constraints in the reactor regime. The results are also capable, in principle, of throwing considerable light on the local properties of current generation and diffusion in tokamaks, which may be enhanced by turbulence, as has been suggested recently by several researchers.
Directory of Open Access Journals (Sweden)
Rohin Anhal
2013-10-01
Full Text Available The aim of this paper is to examine the direction of causality between real GDP on the one hand and final energy and coal consumption on the other in India, for the period from 1970 to 2011. The methodology adopted is the non-parametric bootstrap procedure, which is used to construct the critical values for the hypothesis of causality. The results of the bootstrap tests show that for total energy consumption, there exists no causal relationship in either direction with GDP of India. However, if coal consumption is considered, we find evidence in support of unidirectional causality running from coal consumption to GDP. This clearly has important implications for the Indian economy. The most important implication is that curbing coal consumption in order to reduce carbon emissions would in turn have a limiting effect on economic growth. Our analysis contributes to the literature in three distinct ways. First, this is the first paper to use the bootstrap method to examine the growth-energy connection for the Indian economy. Second, we analyze data for the time period 1970 to 2011, thereby utilizing recently available data that has not been used by others. Finally, in contrast to the recently done studies, we adopt a disaggregated approach for the analysis of the growth-energy nexus by considering not only aggregate energy consumption, but coal consumption as well.
Remuestreo Bootstrap y Jackknife en confiabilidad: Caso Exponencial y Weibull
Directory of Open Access Journals (Sweden)
Javier Ramírez-Montoya
2016-01-01
Full Text Available Se comparan los métodos de remuestreo Bootstrap-t y Jackknife delete I y delete II, utilizando los estimadores no paramétricos de Kaplan-Meier y Nelson-Aalen, que se utilizan con frecuencia en la práctica, teniendo en cuenta diferentes porcentajes de censura, tamaños de muestra y tiempos de interés. La comparación se realiza vía simulación, mediante el error cuadrático medio.
Intervalos de confiança bootstrap e subamostragem
Sebastião, João; Nunes, Sara
2003-01-01
Neste trabalho consideram-se as metodologias de reamostragem e subamostragem. Estas metodologias, computacionalmente intensivas, são hoje amplamente utilizadas na Inferência Estatística no cálculo de intervalos de confiança para um determinado parâmetro de interesse. Num estudo de simulação aplica-se o Bootstrap e a subamostragem a conjuntos de observações provenientes de populações normais com o objectivo de determinar intervalos de confiança para o valor médio.
Two novel applications of bootstrap currents: snakes and jitter stabilization
Energy Technology Data Exchange (ETDEWEB)
Thyagaraja, A. [AEA Technology, Culham (United Kingdom); Haas, F.A. [The Open University, Oxford Research Unit, Oxford (United Kingdom)
1993-12-31
Both neoclassical theory and certain turbulence theories of particle transport in tokamaks predict the existence of bootstrap (i.e., pressure-driven) currents. Two new applications of this form of non-inductive current are considered in this work. The first is an explanation of the `snake` phenomenon observed in JET based on steady-state nonlinear tearing theory. The second is an active method of dynamic stabilization of the m=1 mode using the `jitter` approach suggested by Thyagaraja et al in a recent paper. (author) 11 refs.
Cross-Validation, Bootstrap, and Support Vector Machines
Directory of Open Access Journals (Sweden)
Masaaki Tsujitani
2011-01-01
Full Text Available This paper considers the applications of resampling methods to support vector machines (SVMs. We take into account the leaving-one-out cross-validation (CV when determining the optimum tuning parameters and bootstrapping the deviance in order to summarize the measure of goodness-of-fit in SVMs. The leaving-one-out CV is also adapted in order to provide estimates of the bias of the excess error in a prediction rule constructed with training samples. We analyze the data from a mackerel-egg survey and a liver-disease study.
Comparing groups randomization and bootstrap methods using R
Zieffler, Andrew S; Long, Jeffrey D
2011-01-01
A hands-on guide to using R to carry out key statistical practices in educational and behavioral sciences research Computing has become an essential part of the day-to-day practice of statistical work, broadening the types of questions that can now be addressed by research scientists applying newly derived data analytic techniques. Comparing Groups: Randomization and Bootstrap Methods Using R emphasizes the direct link between scientific research questions and data analysis. Rather than relying on mathematical calculations, this book focus on conceptual explanations and
The S-matrix Bootstrap II: Two Dimensional Amplitudes
Paulos, Miguel F; Toledo, Jonathan; van Rees, Balt C; Vieira, Pedro
2016-01-01
We consider constraints on the S-matrix of any gapped, Lorentz invariant quantum field theory in 1 + 1 dimensions due to crossing symmetry and unitarity. In this way we establish rigorous bounds on the cubic couplings of a given theory with a fixed mass spectrum. In special cases we identify interesting integrable theories saturating these bounds. Our analytic bounds match precisely with numerical bounds obtained in a companion paper where we consider massive QFT in an AdS box and study boundary correlators using the technology of the conformal bootstrap.
Bootstrapping Mixed Correlators in the Five Dimensional Critical O(N) Models
Li, Zhijin
2016-01-01
We use the conformal bootstrap approach to explore $5D$ CFTs with $O(N)$ global symmetry, which contain $N$ scalars $\\phi_i$ transforming as $O(N)$ vector. Specifically, we study multiple four-point correlators of the leading $O(N)$ vector $\\phi_i$ and the $O(N)$ singlet $\\sigma$. The crossing symmetry of the four-point functions and the unitarity condition provide nontrivial constraints on the scaling dimensions ($\\Delta_\\phi$, $\\Delta_\\sigma$) of $\\phi_i$ and $\\sigma$. With reasonable assumptions on the gaps between scaling dimensions of $\\phi_i$ ($\\sigma$) and the next $O(N)$ vector (singlet) scalar, we are able to isolate the scaling dimensions $(\\Delta_\\phi$, $\\Delta_\\sigma)$ in small islands. In particular, for large $N=500$, the isolated region is highly consistent with the result obtained from large $N$ expansion. We also study the interacting $O(N)$ CFTs for $1\\leqslant N\\leqslant100$. Isolated regions on $(\\Delta_\\phi,\\Delta_\\sigma)$ plane are obtained using conformal bootstrap program with lower or...
A bootstrapped switch employing a new clock feed-through compensation technique
Institute of Scientific and Technical Information of China (English)
Wu Xiaofeng; Liu Hongxia; Su Li; Hao Yue; Li Di; Hu Shigang
2009-01-01
Nonlinearity caused by the clock feed-through of a bootstrapped switch and its compensation techniques are analyzed. All kinds of clock feed-through compensation configurations and their drawbacks are also investigated.It is pointed out that the delay path match of the clock boosting circuit is the critical factor that affects the effective-ness of clock feed-through compensation. Based on that, a new clock feed-through compensation configuration and corresponding bootstrapped switch are presented and designed optimally with the UMC mixed-mode/RF 0.18μm 1P6M P-sub twin-well CMOS process by orientating and elaborately designing the switch MOSFETs that influence the delay path match of the clock boosting circuit. HSPICE simulation results show that the proposed clock feed-through compensation configuration can not only enhance the sampling accuracy under variations of process, power supply voltage, temperature and capacitors but also decrease the even harmonic, high-order odd harmonic and THD on the whole effectively.
Impurities in a non-axisymmetric plasma: Transport and effect on bootstrap current
Energy Technology Data Exchange (ETDEWEB)
Mollén, A., E-mail: albertm@chalmers.se [Department of Applied Physics, Chalmers University of Technology, Göteborg (Sweden); Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); Landreman, M. [Institute for Research in Electronics and Applied Physics, University of Maryland, College Park, Maryland 20742 (United States); Smith, H. M.; Helander, P. [Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); Braun, S. [Max-Planck-Institut für Plasmaphysik, 17491 Greifswald (Germany); German Aerospace Center, Institute of Engineering Thermodynamics, Pfaffenwaldring 38-40, D-70569 Stuttgart (Germany)
2015-11-15
Impurities cause radiation losses and plasma dilution, and in stellarator plasmas the neoclassical ambipolar radial electric field is often unfavorable for avoiding strong impurity peaking. In this work we use a new continuum drift-kinetic solver, the SFINCS code (the Stellarator Fokker-Planck Iterative Neoclassical Conservative Solver) [M. Landreman et al., Phys. Plasmas 21, 042503 (2014)] which employs the full linearized Fokker-Planck-Landau operator, to calculate neoclassical impurity transport coefficients for a Wendelstein 7-X (W7-X) magnetic configuration. We compare SFINCS calculations with theoretical asymptotes in the high collisionality limit. We observe and explain a 1/ν-scaling of the inter-species radial transport coefficient at low collisionality, arising due to the field term in the inter-species collision operator, and which is not found with simplified collision models even when momentum correction is applied. However, this type of scaling disappears if a radial electric field is present. We also use SFINCS to analyze how the impurity content affects the neoclassical impurity dynamics and the bootstrap current. We show that a change in plasma effective charge Z{sub eff} of order unity can affect the bootstrap current enough to cause a deviation in the divertor strike point locations.
Production of High Value Fluorine Gases for the Semiconductor Industry
Energy Technology Data Exchange (ETDEWEB)
Bulko, J. B.
2003-10-23
The chemistry to manufacture high purity GeF{sub 4} and WF{sub 6} for use in the semiconductor industry using Starmet's new fluorine extraction technology has been developed. Production of GeF{sub 4} was established using a tube-style reactor system where conversion yields as high as 98.1% were attained for the reaction between and GeO{sub 2}. Collection of the fluoride gas improved to 97.7% when the reactor sweep gas contained a small fraction of dry air (10-12 vol%) along with helium. The lab-synthesized product was shown to contain the least amount of infrared active and elemental impurities when compared with a reference material certified at 99.99% purity. Analysis of the ''as-produced'' gas using ICP-MS showed that uranium could not be detected at a detection limit of 0.019ppm-wt. A process to make WF{sub 6} from WO{sub 2}, and UF{sub 4}, produced a WOF{sub 4} intermediate, which proved difficult to convert to tungsten hexafluoride using titanium fluoride as a fluorinating agent.
Scrap tire recycling: Promising high value applications. Final report
Energy Technology Data Exchange (ETDEWEB)
Bauman, B.D.; Leskovyansky, P.J.; Drela, H.
1993-11-01
Surface modification of scrap tire rubber (rubber particles treated with chlorine gas) show promise for ameliorating the scrap tire problem (the treated rubber can be used as a component in high- performance, expensive polymer systems). The process has been proven in Phase I. Phase II covers market/applications, process development (Forberg-design mixer reactor was chosen), plant design, capital cost estimate, economics environmental/safety/health, and energy impact. Almost of the small amount of chlorine is consumed. The capital costs for a rubber particle treatment facility are attractive, being at least two orders of magnitude less than that of facilities for making new polymer materials. Large volume markets using treated rubber are needed. The amount of scrap rubber available is small compared to the polymers available for replacement. 7 tabs, 16 figs.
Nonparametric bootstrap analysis with applications to demographic effects in demand functions.
Gozalo, P L
1997-12-01
"A new bootstrap proposal, labeled smooth conditional moment (SCM) bootstrap, is introduced for independent but not necessarily identically distributed data, where the classical bootstrap procedure fails.... A good example of the benefits of using nonparametric and bootstrap methods is the area of empirical demand analysis. In particular, we will be concerned with their application to the study of two important topics: what are the most relevant effects of household demographic variables on demand behavior, and to what extent present parametric specifications capture these effects." excerpt
Bootstrap Determination of the Co-Integration Rank in Heteroskedastic VAR Models
DEFF Research Database (Denmark)
Cavaliere, Giuseppe; Rahbek, Anders; Taylor, A. M. Robert
In a recent paper Cavaliere et al. (2012) develop bootstrap implementations of the (pseudo-) likelihood ratio [PLR] co-integration rank test and associated sequential rank determination procedure of Johansen (1996). The bootstrap samples are constructed using the restricted parameter estimates......, moreover, that the probability that the associated bootstrap sequential procedures select a rank smaller than the true rank converges to zero. This result is shown to hold for both the i.i.d. and wild bootstrap variants under conditional heteroskedasticity but only for the latter under unconditional...
Diagnostic value of high resolutional computed tomography of spine
Energy Technology Data Exchange (ETDEWEB)
Yang, S. M.; Im, S. K.; Sohn, M. H.; Lim, K. Y.; Kim, J. K.; Choi, K. C. [Jeonbug National University College of Medicine, Seoul (Korea, Republic of)
1984-03-15
Non-enhanced high resolution computed tomography provide clear visualization of soft tissue in the canal and bony details of spine, particularly of the lumbar spine. We observed 70 cases of spine CT using GE CT/T 8800 scanner during the period from Dec. 1982 to Sep. 1983 at Jeonbug National University Hospital. The results were as follows: 1. The sex distribution of cases were 55 males and 15 females : age was from 17 years to 67 years; sites were 11 cervical spine, 5 thoracic spine and 54 lumbosacral spine. 2. CT diagnosis showed 44 cases of lumbar disc herniation, 7 cases of degenerative disease, 3 cases of spine fracture and each 1 cases of cord tumor, metastatic tumor, spontaneous epidural hemorrhage, epidural abscess, spine tbc., meningocele with diastematomyelia. 3. Sites of herniated nucleus pulposus were 34 cases (59.6%) between L4-5 interspace and 20 cases (35.1%) between L5-S1 interspace. 13 cases (29.5%) of lumbar disc herniation disclosed multiple lesions. Location of herniation were central type in 28 cases(49.1%), right-central type in 12 cases(21.2%), left-central type in 11 cases (19.2%) and far lateral type in 6 cases(10.5%). 4. CT findings of herniated nucleus pulposus were as follows : focal protrusion of posterior disc margin and obliteration of anterior epidural fat in all cases, dural sac indentation in 26 cases(45.6%), soft tissue mass in epidural fat in 21 cases(36.8%), displacement or compression of nerve root sheath in 12 cases(21%). 5. Multiplanar reformatted images and Blink mode provide more effective evaluation about definite level and longitudinal dimension of lesion, such as obscure disc herniation, spine fracture, cord tumor and epidural abscess. 6. Non-enhanced and enhanced high resolutional computed tomography were effectively useful in demonstrating compression or displacement of spinal cord and nerve root, examing congenital anomaly such as meningocele and primary or metastatic spinal lesions.
Electrostatic focusing system with high value of demagnification
Abgaryan, Artush A.; Levi, Eli
2012-10-01
For E-beam transmission and transforming we developed an electrostatic focusing device with extraordinary demagnification and abilities for 100% transmission of an electron beam with uniform distribution of current density. This experimental electrostatic focusing system consists of two sections; the first is field formation and second is field free - for measurement space1. The purpose of this article is to present the experimental results from our electro-optical system. The measurement instrument used in the laboratory set up is an adjustable scanning system, which includes a faraday cup with a 14um diameter tungsten wire, for measuring different cross sections. The measurement of the crossover point is based on a combination of theoretical and experimental processes. The theoretical uses calculations from the "CPO"2 program and the experimental measures different cross sections which are much larger than the diameter of the tungsten wire. Theoretically, from trajectory calculations, the crossover point is approximately 0.446μm. This estimation is obtained by drawing an isosceles triangle from the experimental results and comparing it to another isosceles triangle created from the theoretically calculated trajectories. Both triangles together have a geometrically proportional ratio and differ by about one percent or less. The design of the electrostatic focusing system is achieved utilizing the CGMR (Cone and Golden Mean Ratio) approach 1, 3 and 4. This system is suitable for use in X-ray tubes5, e-beam lithography, SEM, high speed photonic technology, and also for any EOS.
Manufacturing cereal bars with high nutritional value through experimental design
Directory of Open Access Journals (Sweden)
Roberta Covino
2015-01-01
Full Text Available Organizations responsible for public health throughout the world have been increasingly worrying about how to feed populations encouraging a nutritious and balanced diet in order to decrease the occurrence of chronic diseases, which are constantly related to an inadequate diet. Still, due to matters of modern lifestyle consumers are increasingly seeking convenient products. This being so, cereal bars have been an option when the matter is low calorie fast food which is also source of fiber. This study aimed at developing a cereal bar with high dietary fiber, iron, vitamins A and vitamin E, in order to easily enable adult population achieve the daily recommendation for such nutrients. Eight formulations plus the focal point were conducted through experimental planning; sensory analysis with 110 tasters for each block and texture. Afterwards, we conducted centesimal analysis for all three formulations presenting the best sensory results. After statistical analysis and comparison to the means for products available in the market, it was possible to conclude that the product developed presented great acceptance and fiber level more than twice as much as the means for commercial products.
Assessing Uncertainty in LULC Classification Accuracy by Using Bootstrap Resampling
Directory of Open Access Journals (Sweden)
Lin-Hsuan Hsiao
2016-08-01
Full Text Available Supervised land-use/land-cover (LULC classifications are typically conducted using class assignment rules derived from a set of multiclass training samples. Consequently, classification accuracy varies with the training data set and is thus associated with uncertainty. In this study, we propose a bootstrap resampling and reclassification approach that can be applied for assessing not only the uncertainty in classification results of the bootstrap-training data sets, but also the classification uncertainty of individual pixels in the study area. Two measures of pixel-specific classification uncertainty, namely the maximum class probability and Shannon entropy, were derived from the class probability vector of individual pixels and used for the identification of unclassified pixels. Unclassified pixels that are identified using the traditional chi-square threshold technique represent outliers of individual LULC classes, but they are not necessarily associated with higher classification uncertainty. By contrast, unclassified pixels identified using the equal-likelihood technique are associated with higher classification uncertainty and they mostly occur on or near the borders of different land-cover.
Bootstrapping Q Methodology to Improve the Understanding of Human Perspectives.
Zabala, Aiora; Pascual, Unai
2016-01-01
Q is a semi-qualitative methodology to identify typologies of perspectives. It is appropriate to address questions concerning diverse viewpoints, plurality of discourses, or participation processes across disciplines. Perspectives are interpreted based on rankings of a set of statements. These rankings are analysed using multivariate data reduction techniques in order to find similarities between respondents. Discussing the analytical process and looking for progress in Q methodology is becoming increasingly relevant. While its use is growing in social, health and environmental studies, the analytical process has received little attention in the last decades and it has not benefited from recent statistical and computational advances. Specifically, the standard procedure provides overall and arguably simplistic variability measures for perspectives and none of these measures are associated to individual statements, on which the interpretation is based. This paper presents an innovative approach of bootstrapping Q to obtain additional and more detailed measures of variability, which helps researchers understand better their data and the perspectives therein. This approach provides measures of variability that are specific to each statement and perspective, and additional measures that indicate the degree of certainty with which each respondent relates to each perspective. This supplementary information may add or subtract strength to particular arguments used to describe the perspectives. We illustrate and show the usefulness of this approach with an empirical example. The paper provides full details for other researchers to implement the bootstrap in Q studies with any data collection design.
Bootstrap Percolation on Complex Networks with Community Structure
Chong, Wu; Rui, Zhang; Liujun, Chen; Jiawei, Chen; Xiaobin, Li; Yanqing, Hu
2014-01-01
Real complex networks usually involve community structure. How innovation and new products spread on social networks which have internal structure is a practically interesting and fundamental question. In this paper we study the bootstrap percolation on a single network with community structure, in which we initiate the bootstrap process by activating different fraction of nodes in each community. A previously inactive node transfers to active one if it detects at least $k$ active neighbors. The fraction of active nodes in community $i$ in the final state $S_i$ and its giant component size $S_{gci}$ are theoretically obtained as functions of the initial fractions of active nodes $f_i$. We show that such functions undergo multiple discontinuous transitions; The discontinuous jump of $S_i$ or $S_{gci}$ in one community may trigger a simultaneous jump of that in the other, which leads to multiple discontinuous transitions for the total fraction of active nodes $S$ and its associated giant component size $S_{gc}$...
Bootstrap Learning and Visual Processing Management on Mobile Robots
Directory of Open Access Journals (Sweden)
Mohan Sridharan
2010-01-01
Full Text Available A central goal of robotics and AI is to enable a team of robots to operate autonomously in the real world and collaborate with humans over an extended period of time. Though developments in sensor technology have resulted in the deployment of robots in specific applications the ability to accurately sense and interact with the environment is still missing. Key challenges to the widespread deployment of robots include the ability to learn models of environmental features based on sensory inputs, bootstrap off of the learned models to detect and adapt to environmental changes, and autonomously tailor the sensory processing to the task at hand. This paper summarizes a comprehensive effort towards such bootstrap learning, adaptation, and processing management using visual input. We describe probabilistic algorithms that enable a mobile robot to autonomously plan its actions to learn models of color distributions and illuminations. The learned models are used to detect and adapt to illumination changes. Furthermore, we describe a probabilistic sequential decision-making approach that autonomously tailors the visual processing to the task at hand. All algorithms are fully implemented and tested on robot platforms in dynamic environments.
Quantifying uncertainty on sediment loads using bootstrap confidence intervals
Slaets, Johanna I. F.; Piepho, Hans-Peter; Schmitter, Petra; Hilger, Thomas; Cadisch, Georg
2017-01-01
Load estimates are more informative than constituent concentrations alone, as they allow quantification of on- and off-site impacts of environmental processes concerning pollutants, nutrients and sediment, such as soil fertility loss, reservoir sedimentation and irrigation channel siltation. While statistical models used to predict constituent concentrations have been developed considerably over the last few years, measures of uncertainty on constituent loads are rarely reported. Loads are the product of two predictions, constituent concentration and discharge, integrated over a time period, which does not make it straightforward to produce a standard error or a confidence interval. In this paper, a linear mixed model is used to estimate sediment concentrations. A bootstrap method is then developed that accounts for the uncertainty in the concentration and discharge predictions, allowing temporal correlation in the constituent data, and can be used when data transformations are required. The method was tested for a small watershed in Northwest Vietnam for the period 2010-2011. The results showed that confidence intervals were asymmetric, with the highest uncertainty in the upper limit, and that a load of 6262 Mg year-1 had a 95 % confidence interval of (4331, 12 267) in 2010 and a load of 5543 Mg an interval of (3593, 8975) in 2011. Additionally, the approach demonstrated that direct estimates from the data were biased downwards compared to bootstrap median estimates. These results imply that constituent loads predicted from regression-type water quality models could frequently be underestimating sediment yields and their environmental impact.
López, Iago; Alvarez, César; Gil, José L; Revilla, José A
2012-11-30
Data on the 95th and 90th percentiles of bacteriological quality indicators are used to classify bathing waters in Europe, according to the requirements of Directive 2006/7/EC. However, percentile values and consequently, classification of bathing waters depend both on sampling effort and sample-size, which may undermine an appropriate assessment of bathing water classification. To analyse the influence of sampling effort and sample size on water classification, a bootstrap approach was applied to 55 bacteriological quality datasets of several beaches in the Balearic Islands (Spain). Our results show that the probability of failing the regulatory standards of the Directive is high when sample size is low, due to a higher variability in percentile values. In this way, 49% of the bathing waters reaching an "Excellent" classification (95th percentile of Escherichia coli under 250 cfu/100 ml) can fail the "Excellent" regulatory standard due to sampling strategy, when 23 samples per season are considered. This percentage increases to 81% when 4 samples per season are considered. "Good" regulatory standards can also be failed in bathing waters with an "Excellent" classification as a result of these sampling strategies. The variability in percentile values may affect bathing water classification and is critical for the appropriate design and implementation of bathing water Quality Monitoring and Assessment Programs. Hence, variability of percentile values should be taken into account by authorities if an adequate management of these areas is to be achieved. Copyright © 2012 Elsevier Ltd. All rights reserved.
Institute of Scientific and Technical Information of China (English)
2000-01-01
In this paper,the author studies the asymptotic accuracies of the one-term Edgeworth expansions and the bootstrap approximation for the studentized MLE from randomly censored exponential population.It is shown that the Edgeworth expansions and the bootstrap approximation are asymptotically close to the exact distribution of the studentized MLE with a rate.
Timmerman, Marieke E.; Kiers, Henk A.L.; Smilde, Age K.
2007-01-01
Confidence intervals (Cis) in principal component analysis (PCA) can be based on asymptotic standard errors and on the bootstrap methodology. The present paper offers an overview of possible strategies for bootstrapping in PCA. A motivating example shows that Ci estimates for the component loadings
On the M fewer than N bootstrap approximation to the trimmed mean
N. Gribkova; R. Helmers (Roelof)
2008-01-01
htmlabstractWe show that the M fewer than N (N is the real data sample size, M denotes the size of the bootstrap resample; M=N ! 0, as M ! 1) bootstrap approximation to the distribution of the trimmed mean is consistent without any conditions on the population distribution F, whereas Efron's naive (
A Bootstrap Generalization of Modified Parallel Analysis for IRT Dimensionality Assessment
Finch, Holmes; Monahan, Patrick
2008-01-01
This article introduces a bootstrap generalization to the Modified Parallel Analysis (MPA) method of test dimensionality assessment using factor analysis. This methodology, based on the use of Marginal Maximum Likelihood nonlinear factor analysis, provides for the calculation of a test statistic based on a parametric bootstrap using the MPA…
A Primer on Bootstrap Factor Analysis as Applied to Health Studies Research
Lu, Wenhua; Miao, Jingang; McKyer, E. Lisako J.
2014-01-01
Objectives: To demonstrate how the bootstrap method could be conducted in exploratory factor analysis (EFA) with a syntax written in SPSS. Methods: The data obtained from the Texas Childhood Obesity Prevention Policy Evaluation project (T-COPPE project) were used for illustration. A 5-step procedure to conduct bootstrap factor analysis (BFA) was…
DEFF Research Database (Denmark)
Hounyo, Ulrich; Varneskov, Rasmus T.
We provide a new resampling procedure - the local stable bootstrap - that is able to mimic the dependence properties of realized power variations for pure-jump semimartingales observed at different frequencies. This allows us to propose a bootstrap estimator and inference procedure for the activi...
The Inverse Bagging Algorithm: Anomaly Detection by Inverse Bootstrap Aggregating
Vischia, Pietro
2016-01-01
For data sets populated by a very well modeled process and by another process of unknown probability density function (PDF), a desired feature when manipulating the fraction of the unknown process (either for enhancing it or suppressing it) consists in avoiding to modify the kinematic distributions of the well modeled one. A bootstrap technique is used to identify sub-samples rich in the well modeled process, and classify each event according to the frequency of it being part of such sub-samples. Comparisons with general MVA algorithms will be shown, as well as a study of the asymptotic properties of the method, making use of a public domain data set that models a typical search for new physics as performed at hadronic colliders such as the Large Hadron Collider (LHC).
Bootstrapping Pure Quantum Gravity in AdS3
Bae, Jin-Beom; Lee, Sungjay
2016-01-01
The three-dimensional pure quantum gravity with negative cosmological constant is supposed to be dual to the extremal conformal field theory of central charge $c=24k$ in two dimensions. We employ the conformal bootstrap method to analyze the extremal CFTs, and find numerical evidence for the non-existence of the extremal CFTs for sufficiently large central charge ($k \\ge 20$). We also explore near-extremal CFTs, a small modification of extremal ones, and find similar evidence for their non-existence for large central charge. This indicates, under the assumption of holomorphic factorization, the pure gravity in the weakly curved AdS$_3$ do not exist as a consistent quantum theory.
Bootstrapping Inductive and Coinductive Types in HasCASL
Schröder, Lutz
2008-01-01
We discuss the treatment of initial datatypes and final process types in the wide-spectrum language HasCASL. In particular, we present specifications that illustrate how datatypes and process types arise as bootstrapped concepts using HasCASL's type class mechanism, and we describe constructions of types of finite and infinite trees that establish the conservativity of datatype and process type declarations adhering to certain reasonable formats. The latter amounts to modifying known constructions from HOL to avoid unique choice; in categorical terminology, this means that we establish that quasitoposes with an internal natural numbers object support initial algebras and final coalgebras for a range of polynomial functors, thereby partially generalising corresponding results from topos theory. Moreover, we present similar constructions in categories of internal complete partial orders in quasitoposes.
A bootstrap method for estimating uncertainty of water quality trends
Hirsch, Robert M.; Archfield, Stacey A.; DeCicco, Laura
2015-01-01
Estimation of the direction and magnitude of trends in surface water quality remains a problem of great scientific and practical interest. The Weighted Regressions on Time, Discharge, and Season (WRTDS) method was recently introduced as an exploratory data analysis tool to provide flexible and robust estimates of water quality trends. This paper enhances the WRTDS method through the introduction of the WRTDS Bootstrap Test (WBT), an extension of WRTDS that quantifies the uncertainty in WRTDS-estimates of water quality trends and offers various ways to visualize and communicate these uncertainties. Monte Carlo experiments are applied to estimate the Type I error probabilities for this method. WBT is compared to other water-quality trend-testing methods appropriate for data sets of one to three decades in length with sampling frequencies of 6–24 observations per year. The software to conduct the test is in the EGRETci R-package.
Boundary and interface CFTs from the conformal bootstrap
Gliozzi, Ferdinando; Liendo, Pedro; Meineri, Marco; Rago, Antonio
2015-05-01
We explore some consequences of the crossing symmetry for defect conformal field theories, focusing on codimension one defects like flat boundaries or interfaces. We study surface transitions of the 3d Ising and other O( N ) models through numerical solutions to the crossing equations with the method of determinants. In the extraordinary transition, where the low-lying spectrum of the surface operators is known, we use the bootstrap equations to obtain information on the bulk spectrum of the theory. In the ordinary transition the knowledge of the low-lying bulk spectrum allows to calculate the scale dimension of the relevant surface operator, which compares well with known results of two-loop calculations in 3d. Estimates of various OPE coefficients are also obtained. We also analyze in 4-ɛ dimensions the renormalization group interface between the O( N ) model and the free theory and check numerically the results in 3d.
Boundary and interface CFTs from the conformal bootstrap
Energy Technology Data Exchange (ETDEWEB)
Gliozzi, Ferdinando [Dipartimento di Fisica, Università di Torino,Via P. Giuria 1 I-10125 Torino (Italy); Istituto Nazionale di Fisica Nucleare - sezione di Torino,Via P. Giuria 1 I-10125 Torino (Italy); Liendo, Pedro [IMIP, Humboldt-Universität zu Berlin, IRIS Adelershof,Zum Großen Windkanal 6, 12489 Berlin (Germany); Meineri, Marco [Scuola Normale Superiore,Piazza dei Cavalieri 7 I-56126 Pisa (Italy); Istituto Nazionale di Fisica Nucleare - sezione di Pisa,Largo B. Pontecorvo, 3, 56127 Pisa (Italy); Rago, Antonio [Centre for Mathematical Sciences, Plymouth University,Drake Circus, Plymouth, PL4 8AA (United Kingdom)
2015-05-07
We explore some consequences of the crossing symmetry for defect conformal field theories, focusing on codimension one defects like flat boundaries or interfaces. We study surface transitions of the 3d Ising and other O(N) models through numerical solutions to the crossing equations with the method of determinants. In the extraordinary transition, where the low-lying spectrum of the surface operators is known, we use the bootstrap equations to obtain information on the bulk spectrum of the theory. In the ordinary transition the knowledge of the low-lying bulk spectrum allows to calculate the scale dimension of the relevant surface operator, which compares well with known results of two-loop calculations in 3d. Estimates of various OPE coefficients are also obtained. We also analyze in 4-ϵ dimensions the renormalization group interface between the O(N) model and the free theory and check numerically the results in 3d.
Bootstrapping Security Policies for Wearable Apps Using Attributed Structural Graphs.
González-Tablas, Ana I; Tapiador, Juan E
2016-05-11
We address the problem of bootstrapping security and privacy policies for newly-deployed apps in wireless body area networks (WBAN) composed of smartphones, sensors and other wearable devices. We introduce a framework to model such a WBAN as an undirected graph whose vertices correspond to devices, apps and app resources, while edges model structural relationships among them. This graph is then augmented with attributes capturing the features of each entity together with user-defined tags. We then adapt available graph-based similarity metrics to find the closest app to a new one to be deployed, with the aim of reusing, and possibly adapting, its security policy. We illustrate our approach through a detailed smartphone ecosystem case study. Our results suggest that the scheme can provide users with a reasonably good policy that is consistent with the user's security preferences implicitly captured by policies already in place.
Bootstrapping Security Policies for Wearable Apps Using Attributed Structural Graphs
Directory of Open Access Journals (Sweden)
Ana I. González-Tablas
2016-05-01
Full Text Available We address the problem of bootstrapping security and privacy policies for newly-deployed apps in wireless body area networks (WBAN composed of smartphones, sensors and other wearable devices. We introduce a framework to model such a WBAN as an undirected graph whose vertices correspond to devices, apps and app resources, while edges model structural relationships among them. This graph is then augmented with attributes capturing the features of each entity together with user-defined tags. We then adapt available graph-based similarity metrics to find the closest app to a new one to be deployed, with the aim of reusing, and possibly adapting, its security policy. We illustrate our approach through a detailed smartphone ecosystem case study. Our results suggest that the scheme can provide users with a reasonably good policy that is consistent with the user’s security preferences implicitly captured by policies already in place.
Bootstrap Determination of the Co-integration Rank in Heteroskedastic VAR Models
DEFF Research Database (Denmark)
Cavaliere, Giuseppe; Rahbek, Anders; Taylor, A.M.Robert
of the underlying VAR model which obtain under the reduced rank null hypothesis. They propose methods based on an i.i.d. bootstrap re-sampling scheme and establish the validity of their proposed bootstrap procedures in the context of a co-integrated VAR model with i.i.d. innovations. In this paper we investigate...... in the VAR model are estimated unrestrictedly) for a variety of conditionally and unconditionally heteroskedastic innovation processes....... the properties of their bootstrap procedures, together with analogous procedures based on a wild bootstrap re-sampling scheme, when time-varying behaviour is present in either the conditional or unconditional variance of the innovations. We show that the bootstrap PLR tests are asymptotically correctly sized and...
Pismensky, Artem L
2015-01-01
The method of calculation of $\\varepsilon$-expansion in model of scalar field with $\\varphi^3$-interaction based on conformal bootstrap equations is proposed. This technique is based on self-consistent skeleton equations involving full propagator and full triple vertex. Analytical computations of the Fisher's index $\\eta$ are performed in four-loop approximation. The three-loop result coincides with one obtained previously by the renormalization group equations technique based on calculation of a larger number of Feynman diagrams. The four-loop result agrees with its numerical value obtained by other authors.
Gupta, R.(Panjab University, Chandigarh, India); Moriates, C; Harrison, JD; Valencia, V; Ong, M; Clarke, R.; Steers, N; Hays, RD; Braddock, CH; De Wachter, R
2016-01-01
Organisational culture affects physician behaviours. Patient safety culture surveys have previously been used to drive care improvements, but no comparable survey of high-value care culture currently exists. We aimed to develop a High-Value Care Culture Survey (HVCCS) for use by healthcare leaders and training programmes to target future improvements in value-based care.We conducted a two-phase national modified Delphi process among 28 physicians and nurse experts with diverse backgrounds. We...
Directory of Open Access Journals (Sweden)
V.D. Kuteynikova
2013-07-01
Full Text Available We present study results of social and psychological characteristics of group and individual value orientations in older adolescents. We considered the main criteria to be content and orientation of values, and level of value-oriented student group unity. The study involved 86 high school students of IX-XI grades of Moscow schools. We used a set of socio-psychological methods and instructional techniques: sociometry, referentometry, a technique of defining the informal intragroup power structure in a contact community, "Values and orientation of the individual" method by L.N.Silantieva, a method of determining the degree of value-orientation of group unity. The results obtained show that in high school there is a relationship between the student's status in the group and his system of individual and group value orientations. The most significant differences among students with different status position were detected in the content and direction of value orientations.
DEFF Research Database (Denmark)
Hounyo, Ulrich
We propose a bootstrap mehtod for estimating the distribution (and functionals of it such as the variance) of various integrated covariance matrix estimators. In particular, we first adapt the wild blocks of blocks bootsratp method suggested for the pre-averaged realized volatility estimator......-studentized statistics, our results justify using the bootstrap to esitmate the covariance matrix of a broad class of covolatility estimators. The bootstrap variance estimator is positive semi-definite by construction, an appealing feature that is not always shared by existing variance estimators of the integrated...
Bootstrap Sequential Determination of the Co-integration Rank in VAR Models
DEFF Research Database (Denmark)
Cavaliere, Giuseppe; Rahbek, Anders; Taylor, A. M. Robert
with empirical rejection frequencies often very much in excess of the nominal level. As a consequence, bootstrap versions of these tests have been developed. To be useful, however, sequential procedures for determining the co-integrating rank based on these bootstrap tests need to be consistent, in the sense...... in the literature by proposing a bootstrap sequential algorithm which we demonstrate delivers consistent cointegration rank estimation for general I(1) processes. Finite sample Monte Carlo simulations show the proposed procedure performs well in practice....
JuliBootS: a hands-on guide to the conformal bootstrap
Paulos, Miguel F
2014-01-01
We introduce {\\tt JuliBootS}, a package for numerical conformal bootstrap computations coded in {\\tt Julia}. The centre-piece of {\\tt JuliBootS} is an implementation of Dantzig's simplex method capable of handling arbitrary precision linear programming problems with continuous search spaces. Current supported features include conformal dimension bounds, OPE bounds, and bootstrap with or without global symmetries. The code is trivially parallelizable on one or multiple machines. We exemplify usage extensively with several real-world applications. In passing we give a pedagogical introduction to the numerical bootstrap methods.
The utility of high b-value DWI in evaluation of ischemic stroke at 3 T
Energy Technology Data Exchange (ETDEWEB)
Cihangiroglu, Mutlu, E-mail: mcihangiroglu@yeditepe.edu.tr [Department of Radiology, Yeditepe University Hospital, Istanbul (Turkey); Citci, Beyza, E-mail: bcitci@yeditepe.edu.tr [Department of Neurology, Yeditepe University Hospital, Istanbul (Turkey); Kilickesmez, Ozgur, E-mail: okilickesmez@yeditepe.edu.tr [Department of Radiology, Yeditepe University Hospital, Istanbul (Turkey); Firat, Zeynep, E-mail: zfirat@yeditepe.edu.tr [Department of Radiology, Yeditepe University Hospital, Istanbul (Turkey); Karlikaya, Geysu, E-mail: gkarlikaya@yeditepe.edu.tr [Department of Neurology, Yeditepe University Hospital, Istanbul (Turkey); Ulug, Aziz M., E-mail: ulug@ieee.org [Department of Biomedical Engineering, Yeditepe University, Istanbul (Turkey); The Feinstein Institute for Medical Research, Manhasset, NY (United States); Bingol, Canan A., E-mail: caykutbingol@yeditepe.edu.tr [Department of Neurology, Yeditepe University Hospital, Istanbul (Turkey); Kovanlikaya, Ilhami, E-mail: ilk2002@med.cornell.edu [Department of Radiology, Weill Cornell Medical College, NY (United States)
2011-04-15
Purpose: The utility of DWI with high b-value in ischemic stroke is still unsettled. The purpose of this study is to compare high b-value (3000) and standard b-value (1000) diffusion-weighted images in patients with ischemic stroke at 3 T. Materials and methods: 27 patients with acute stroke who were admitted to the hospital during the first 24 h after symptom onset were included in this study. All patients had a brain MRI study with stroke protocol including standard (b = 1000) DWI and high b-value (b = 3000) DWI sequences at 3 T MR scanner. Number and localization of the lesions were assessed MR signal intensities (SI), signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), contrast ratio (CR) and apparent diffusion coefficient (ADC) values of the lesions and normal parenchyma on DWI with b = 1000 and b = 3000 sequences were measured. Results: All patients with acute stroke revealed hyperintense lesions due to restricted diffusion on DWI with both b-values. However, lesions of restricted diffusion were more conspicuous in b = 3000 value DWI than b = 1000, and additional 4 ischemic lesions were detected on b = 3000 DWI. SNR, CNR, SI and also ADC values in both stroke area and normal parenchyma were lower at b = 3000 than the value at b = 1000. At b = 3000, CR was significantly greater than b = 1000 images. Conclusions: Although quantitative analysis shows higher SI, SNR and CNR values with standard b-value (b = 1000) diffusion-weighted imaging, using higher b-value may still be beneficial in detecting additional subtle lesions in patients whose clinical findings are not correlated with standard b-value DWI in stroke.
Language bootstrapping: learning word meanings from perception-action association.
Salvi, Giampiero; Montesano, Luis; Bernardino, Alexandre; Santos-Victor, José
2012-06-01
We address the problem of bootstrapping language acquisition for an artificial system similarly to what is observed in experiments with human infants. Our method works by associating meanings to words in manipulation tasks, as a robot interacts with objects and listens to verbal descriptions of the interactions. The model is based on an affordance network, i.e., a mapping between robot actions, robot perceptions, and the perceived effects of these actions upon objects. We extend the affordance model to incorporate spoken words, which allows us to ground the verbal symbols to the execution of actions and the perception of the environment. The model takes verbal descriptions of a task as the input and uses temporal co-occurrence to create links between speech utterances and the involved objects, actions, and effects. We show that the robot is able form useful word-to-meaning associations, even without considering grammatical structure in the learning process and in the presence of recognition errors. These word-to-meaning associations are embedded in the robot's own understanding of its actions. Thus, they can be directly used to instruct the robot to perform tasks and also allow to incorporate context in the speech recognition task. We believe that the encouraging results with our approach may afford robots with a capacity to acquire language descriptors in their operation's environment as well as to shed some light as to how this challenging process develops with human infants.
A Mellin space approach to the conformal bootstrap
Gopakumar, Rajesh; Sen, Kallol; Sinha, Aninda
2016-01-01
We describe in more detail our approach to the conformal bootstrap which uses the Mellin representation of $CFT_d$ four point functions and expands them in terms of crossing symmetric combinations of $AdS_{d+1}$ Witten exchange functions. We consider arbitrary external scalar operators and set up the conditions for consistency with the operator product expansion. Namely, we demand cancellation of spurious powers (of the cross ratios, in position space) which translate into spurious poles in Mellin space. We discuss two contexts in which we can immediately apply this method by imposing the simplest set of constraint equations. The first is the epsilon expansion. We mostly focus on the Wilson-Fisher fixed point as studied in an epsilon expansion about $d=4$. We reproduce Feynman diagram results for operator dimensions to $O(\\epsilon^3)$ rather straightforwardly. This approach also yields new analytic predictions for OPE coefficients to the same order which fit nicely with recent numerical estimates for the Isin...
Bootstrapping Multi-Parton Loop Amplitudes in QCD
Energy Technology Data Exchange (ETDEWEB)
Bern, Zvi; /UCLA; Dixon, Lance J.; /SLAC; Kosower, David A.; /Saclay, SPhT
2005-07-06
The authors present a new method for computing complete one-loop amplitudes, including their rational parts, in non-supersymmetric gauge theory. This method merges the unitarity method with on-shell recursion relations. It systematizes a unitarity-factorization bootstrap approach previously applied by the authors to the one-loop amplitudes required for next-to-leading order QCD corrections to the processes e{sup +}e{sup -} {yields} Z, {gamma}* {yields} 4 jets and pp {yields} W + 2 jets. We illustrate the method by reproducing the one-loop color-ordered five-gluon helicity amplitudes in QCD that interfere with the tree amplitude, namely A{sub 5;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}) and A{sub 5;1}(1{sup -}, 2{sup +}, 3{sup -}, 4{sup +}, 5{sup +}). Then we describe the construction of the six- and seven-gluon amplitudes with two adjacent negative-helicity gluons, A{sub 6;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}) and A{sub 7;1}(1{sup -}, 2{sup -}, 3{sup +}, 4{sup +}, 5{sup +}, 6{sup +}, 7{sup +}), which uses the previously-computed logarithmic parts of the amplitudes as input. They present a compact expression for the six-gluon amplitude. No loop integrals are required to obtain the rational parts.
Bootstrap equations for $\\mathcal{N}=4$ SYM with defects
Liendo, Pedro
2016-01-01
This paper focuses on the analysis of $4d$ $\\mathcal{N}=4$ superconformal theories in the presence of a defect from the point of view of the conformal bootstrap. We will concentrate first on the case of codimension one, where the defect is a boundary that preserves half of the supersymmetry. After studying the constraints imposed by supersymmetry, we will write the Ward identities associated to two-point functions of $\\tfrac{1}{2}$-BPS operators and write their solution as a superconformal block expansion. Due to a surprising connection between spacetime and R-symmetry conformal blocks, our results not only apply to $4d$ $\\Nm=4$ superconformal theories with a boundary, but also to three more systems that have the same symmetry algebra: $4d$ $\\Nm=4$ superconformal theories with a line defect, $3d$ $\\Nm=4$ superconformal theories with no defect, and $OSP(4^*|4)$ superconformal quantum mechanics. The superconformal algebra implies that all these systems possess a closed subsector of operators in which the bootst...
THE GROWING MIDDLE CLASS IN DEVELOPING COUNTRIES AND THE MARKET FOR HIGH-VALUE FOOD PRODUCTS
Senauer, Benjamin; Goetz, Linde
2003-01-01
The central hypothesis of this paper is that the largest global growth opportunity for high-value food products is the emerging middle class in many developing countries. Using data for Lima, Peru, 20 percent of households are classified as middle or upper class based on the prevalence of ownership of major durable goods, such as refrigerators and automobiles. Monthly expenditures by the middle class on more expensive foods, such as fresh fruit and red meat, and especially for high value-adde...
Directory of Open Access Journals (Sweden)
Dropkin Greg
2009-12-01
Full Text Available Abstract Background The International Commission on Radiological Protection (ICRP recommended annual occupational dose limit is 20 mSv. Cancer mortality in Japanese A-bomb survivors exposed to less than 20 mSv external radiation in 1945 was analysed previously, using a latency model with non-linear dose response. Questions were raised regarding statistical inference with this model. Methods Cancers with over 100 deaths in the 0 - 20 mSv subcohort of the 1950-1990 Life Span Study are analysed with Poisson regression models incorporating latency, allowing linear and non-linear dose response. Bootstrap percentile and Bias-corrected accelerated (BCa methods and simulation of the Likelihood Ratio Test lead to Confidence Intervals for Excess Relative Risk (ERR and tests against the linear model. Results The linear model shows significant large, positive values of ERR for liver and urinary cancers at latencies from 37 - 43 years. Dose response below 20 mSv is strongly non-linear at the optimal latencies for the stomach (11.89 years, liver (36.9, lung (13.6, leukaemia (23.66, and pancreas (11.86 and across broad latency ranges. Confidence Intervals for ERR are comparable using Bootstrap and Likelihood Ratio Test methods and BCa 95% Confidence Intervals are strictly positive across latency ranges for all 5 cancers. Similar risk estimates for 10 mSv (lagged dose are obtained from the 0 - 20 mSv and 5 - 500 mSv data for the stomach, liver, lung and leukaemia. Dose response for the latter 3 cancers is significantly non-linear in the 5 - 500 mSv range. Conclusion Liver and urinary cancer mortality risk is significantly raised using a latency model with linear dose response. A non-linear model is strongly superior for the stomach, liver, lung, pancreas and leukaemia. Bootstrap and Likelihood-based confidence intervals are broadly comparable and ERR is strictly positive by bootstrap methods for all 5 cancers. Except for the pancreas, similar estimates of
BOOTSTRAP TECHNIQUE FOR ROC ANALYSIS: A STABLE EVALUATION OF FISHER CLASSIFIER PERFORMANCE
Institute of Scientific and Technical Information of China (English)
Xie Jigang; iu Zhengding
2007-01-01
This paper presents a novel bootstrap based method for Receiver Operating Characteristic (ROC) analysis of Fisher classifier. By defining Fisher classifier's output as a statistic, the bootstrap technique is used to obtain the sampling distributions of the outputs for the positive class and the negative class respectively. As a result, the ROC curve is a plot of all the (False Positive Rate (FPR),True Positive Rate (TPR)) pairs by varying the decision threshold over the whole range of the bootstrap sampling distributions. The advantage of this method is, the bootstrap based ROC curves are much stable than those of the holdout or cross-validation, indicating a more stable ROC analysis of Fisher classifier. Experiments on five data sets publicly available demonstrate the effectiveness of the proposed method.
Variable selection under multiple imputation using the bootstrap in a prognostic study
Heymans, M.W.; Buuren, S. van; Knol, D.L.; Mechelen, W. van; Vet, H.C.W. de
2007-01-01
Background. Missing data is a challenging problem in many prognostic studies. Multiple imputation (MI) accounts for imputation uncertainty that allows for adequate statistical testing. We developed and tested a methodology combining MI with bootstrapping techniques for studying prognostic variable s
Calculation of the bootstrap current profile for the TJ-II stellarator
Velasco, J L; Lopez-Fraguas, A; Beidler, C D; Maassberg, H; Kernbichler, W; Castejon, F; Jimenez, J A
2011-01-01
Calculations of the bootstrap current for the TJ-II stellarator are presented. DKES and NEO-MC codes are employed; the latter has allowed, for the first time, the precise computation of the bootstrap transport coefficient in the long mean free path regime of this device. The low error bars allow a precise convolution of the monoenergetic coefficients, which is confirmed by error analysis. The radial profile of the bootstrap current is presented for the fist time for the 100_44_64 configuration of TJ-II for three different collisionality regimes. The bootstrap coefficient is then compared to that of other configurations of TJ-II regularly operated. The results show qualitative agreement with toroidal current measurements; precise comparison with real discharges is ongoing.
Variable selection under multiple imputation using the bootstrap in a prognostic study
Heymans, M.W.; Buuren, S. van; Knol, D.L.; Mechelen, W. van; Vet, H.C.W. de
2007-01-01
Background. Missing data is a challenging problem in many prognostic studies. Multiple imputation (MI) accounts for imputation uncertainty that allows for adequate statistical testing. We developed and tested a methodology combining MI with bootstrapping techniques for studying prognostic variable s
JuliBootS: a hands-on guide to the conformal bootstrap
Paulos, Miguel F.
2014-01-01
We introduce {\\tt JuliBootS}, a package for numerical conformal bootstrap computations coded in {\\tt Julia}. The centre-piece of {\\tt JuliBootS} is an implementation of Dantzig's simplex method capable of handling arbitrary precision linear programming problems with continuous search spaces. Current supported features include conformal dimension bounds, OPE bounds, and bootstrap with or without global symmetries. The code is trivially parallelizable on one or multiple machines. We exemplify u...
Screening for cancer: advice for high-value care from the American College of Physicians.
Wilt, Timothy J; Harris, Russell P; Qaseem, Amir
2015-05-19
Cancer screening is one approach to reducing cancer-related morbidity and mortality rates. Screening strategies vary in intensity. Higher-intensity strategies are not necessarily higher value. High-value strategies provide a degree of benefits that clearly justifies the harms and costs incurred; low-value screening provides limited or no benefits to justify the harms and costs. When cancer screening leads to benefits, an optimal intensity of screening maximizes value. Some aspects of screening practices, especially overuse and underuse, are low value. Screening strategies for asymptomatic, average-risk adults for 5 common types of cancer were evaluated by reviewing clinical guidelines and evidence syntheses from the American College of Physicians (ACP), U.S. Preventive Services Task Force, American Academy of Family Physicians, American Cancer Society, American Congress of Obstetricians and Gynecologists, American Gastroenterological Association, and American Urological Association. "High value" was defined as the lowest screening intensity threshold at which organizations agree about screening recommendations for each type of cancer and "low value" as agreement about not recommending overly intensive screening strategies. This information is supplemented with additional findings from randomized, controlled trials; modeling studies; and studies of costs or resource use, including information found in the National Cancer Institute's Physician Data Query and UpToDate. The ACP provides high-value care screening advice for 5 common types of cancer; the specifics are outlined in this article. The ACP strongly encourages clinicians to adopt a cancer screening strategy that focuses on reaching all eligible persons with these high-value screening options while reducing overly intensive, low-value screening.
Darling, Stephen; Parker, Mary-Jane; Goodall, Karen E; Havelka, Jelena; Allen, Richard J
2014-03-01
When participants carry out visually presented digit serial recall, their performance is better if they are given the opportunity to encode extra visuospatial information at encoding-a phenomenon that has been termed visuospatial bootstrapping. This bootstrapping is the result of integration of information from different modality-specific short-term memory systems and visuospatial knowledge in long term memory, and it can be understood in the context of recent models of working memory that address multimodal binding (e.g., models incorporating an episodic buffer). Here we report a cross-sectional developmental study that demonstrated visuospatial bootstrapping in adults (n=18) and 9-year-old children (n=15) but not in 6-year-old children (n=18). This is the first developmental study addressing visuospatial bootstrapping, and results demonstrate that the developmental trajectory of bootstrapping is different from that of basic verbal and visuospatial working memory. This pattern suggests that bootstrapping (and hence integrative functions such as those associated with the episodic buffer) emerge independent of the development of basic working memory slave systems during childhood.
Attitudes, Values and Background of High School Journalists Compared with the Media Elite.
Johnson, Sammye
To compare attitudes, values, and background of high school journalists with those of the media elite (journalists already working in the media), a survey was administered to 132 public and private high school students attending the Trinity University Journalism Institute during June 5-9, 1983. These students were the editors of their newspapers,…
Kantar, E.; Deviren, B.; Keskin, M.
2011-11-01
We present a study, within the scope of econophysics, of the hierarchical structure of 98 among the largest international companies including 18 among the largest Turkish companies, namely Banks, Automobile, Software-hardware, Telecommunication Services, Energy and the Oil-Gas sectors, viewed as a network of interacting companies. We analyze the daily time series data of the Boerse-Frankfurt and Istanbul Stock Exchange. We examine the topological properties among the companies over the period 2006-2010 by using the concept of hierarchical structure methods (the minimal spanning tree (MST) and the hierarchical tree (HT)). The period is divided into three subperiods, namely 2006-2007, 2008 which was the year of global economic crisis, and 2009-2010, in order to test various time-windows and observe temporal evolution. We carry out bootstrap analyses to associate the value of statistical reliability to the links of the MSTs and HTs. We also use average linkage clustering analysis (ALCA) in order to better observe the cluster structure. From these studies, we find that the interactions among the Banks/Energy sectors and the other sectors were reduced after the global economic crisis; hence the effects of the Banks and Energy sectors on the correlations of all companies were decreased. Telecommunication Services were also greatly affected by the crisis. We also observed that the Automobile and Banks sectors, including Turkish companies as well as some companies from the USA, Japan and Germany were strongly correlated with each other in all periods.
Value Relevance of European High- and Low-Technology Companies' Financial Statements
Gegic, Damir; Lindkvist, Anton
2016-01-01
During the 1990s the increased importance of intangible assets caused concern among practitioners and academics that financial statements were losing their value relevance, i.e. the relation between a firms’ financial statement information and its market value, especially for high-technology firms which were deemed likely to be intangible-intensive. Research conducted on the US market largely show that financial statements were losing their relevance to investors during the build-up of the do...
Energy Technology Data Exchange (ETDEWEB)
Silva, Cleomacio Miguel da; Amaral, Romilton dos Santos; Santos Junior, Jose Araujo dos; Vieira, Jose Wilson; Leoterio, Dilmo Marques da Silva [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Radioecologia (RAE)], E-mail: cleomaciomiguel@yahoo.com.br; Amaral, Ademir [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. de Energia Nuclear. Grupo de Estudos em Radioprotecao e Radioecologia
2007-07-01
The distribution of natural radionuclides in samples from typically anomalous environments has generally a great significant asymmetry, as a result of outlier. For diminishing statistic fluctuation researchers, in radioecology, commonly use geometric mean or median, once the average has no stability under the effect of outliers. As the median is not affected by anomalous values, this parameter of central tendency is the most frequently employed for evaluation of a set of data containing discrepant values. On the other hand, Efron presented a non-parametric method the so-called bootstrap that can be used to decrease the dispersion around the central-tendency value. Generally, in radioecology, statistics procedures are used in order to reduce the effect results of the presence of anomalous values as regards averages. In this context, the present study had as an objective to evaluate the application of the non-parametric bootstrap method (BM) for determining the average concentration of {sup 226}Ra in cultivated forage palms (Opuntia spp.) in soils with uranium anomaly on the dairy milk farms, localized in the cities of Pedra and Venturosa, Pernambuco-Brazil, as well as discussing the utilization of this method in radioecology. The results of {sup 226}Ra in samples of forage palm varied from 1,300 to 25,000 mBq.kg{sup -1} (dry matter), with arithmetic average of 5,965.86 +- 5,903.05 mBq.kg{sup -1}. The result obtained for this average using BM was 5,963.82 +- 1,202.96 mBq.kg{sup -1} (dry matter). The use of BM allowed an automatic filtration of experimental data, without the elimination of outliers, leading to the reduction of dispersion around the average. As a result, the BM permitted reaching a stable arithmetic average of the effects of the outliers. (author)
A multidimensional customer value model for the high fashion retail industry
2015-01-01
Ph.D. (Marketing Management) As more retailers gain access to similar technologies, information and processes, it is becoming increasingly difficult to establish a sustainable competitive advantage in the marketplace, ensure customer satisfaction and encourage repurchase intention. This is especially true for high fashion retailers, since their higher margin customers have greater expectations to receive value from these high fashion retailers. To succeed in a highly competitive marketplac...
Directory of Open Access Journals (Sweden)
Christopher D Golden
Full Text Available Botanical diversity provides value to humans through carbon sequestration, air and water purification, and the provisioning of wild foods and ethnomedicines. Here we calculate the value of botanical ethnomedicines in a rainforest region of Madagascar, the Makira Protected Area, using a substitution method that combines replacement costs and choice modeling. The Makira watershed may comprise approximately 0.8% of global botanical diversity and possesses enormous value both in its ability to provision botanical ethnomedicines to local people and as a source of potentially novel pharmaceutical drugs for society as a whole. Approximately 241 locally-recognized species are used as ethnomedicines, including 113 agricultural or weed species. We equated each ethnomedicinal treatment to the monetary value of a comparable pharmaceutical treatment adjusted by personal preferences in perceived efficacy (rather than from known or assumed medicinal equivalency. The benefit value of these botanical ethnomedicines per individual is $5.40-7.90 per year when using the value of highly subsidized Malagasy pharmaceuticals and $100.60-287.40 when using the value of American pharmaceuticals. Using local pharmaceuticals as substitutes, the value per household is $30.24-44.30 per year, equivalent to 43-63% of median annual household income, demonstrating their local importance. Using the value of American pharmaceuticals, the amount is equivalent to 22-63% of the median annual health care expenditures for American adults under 45 in 2006. The potential for developing novel biomedicines from the Makira watershed's unique flora ranges in untapped benefit value from $0.3-5.7 billion for American pharmaceutical companies, non-inclusive of the importance of providing novel medicines and improved healthcare to society. This study provides evidence of the tremendous current local and prospective global value of botanical ethnomedicines and furthers arguments for the
Parallel sort with a ranged, partitioned key-value store in a high perfomance computing environment
Bent, John M.; Faibish, Sorin; Grider, Gary; Torres, Aaron; Poole, Stephen W.
2016-01-26
Improved sorting techniques are provided that perform a parallel sort using a ranged, partitioned key-value store in a high performance computing (HPC) environment. A plurality of input data files comprising unsorted key-value data in a partitioned key-value store are sorted. The partitioned key-value store comprises a range server for each of a plurality of ranges. Each input data file has an associated reader thread. Each reader thread reads the unsorted key-value data in the corresponding input data file and performs a local sort of the unsorted key-value data to generate sorted key-value data. A plurality of sorted, ranged subsets of each of the sorted key-value data are generated based on the plurality of ranges. Each sorted, ranged subset corresponds to a given one of the ranges and is provided to one of the range servers corresponding to the range of the sorted, ranged subset. Each range server sorts the received sorted, ranged subsets and provides a sorted range. A plurality of the sorted ranges are concatenated to obtain a globally sorted result.
Recovery of high-value metals from geothermal sites by biosorption and bioaccumulation.
Lo, Yung-Chung; Cheng, Chieh-Lun; Han, Yin-Lung; Chen, Bor-Yann; Chang, Jo-Shu
2014-05-01
Generation of geothermal energy is associated with a significant amount of geothermal fluids, which may be abundant in high-value metals, such as lithium, cesium, rubidium, and other precious and rare earth metals. The recovery of high-value metals from geothermal fluids would thus have both economic and environmental benefits. The conventional technologies applied to achieve this are mostly physicochemical, which may be energy intensive, pose the risk of secondary pollution whilst being inefficient in recovering metals from dilute solutions. Biological methods, based on biosorption or bioaccumulation, have recently emerged as alternative approaches, as they are more environmentally friendly, cost effective, and suitable for treating wastewater with dilute metal contents. This article provides a comprehensive review of the related biological technologies used to recover the high-value metals present in geothermal fluids as well as critical discussion on the key issues that are often used to evaluate the effectiveness of those methods.
Priess-Groben, Heather A; Hyde, Janet Shibley
2017-06-01
Mathematics motivation declines for many adolescents, which limits future educational and career options. The present study sought to identify predictors of this decline by examining whether implicit theories assessed in ninth grade (incremental/entity) predicted course-taking behaviors and utility value in college. The study integrated implicit theory with variables from expectancy-value theory to examine potential moderators and mediators of the association of implicit theories with college mathematics outcomes. Implicit theories and expectancy-value variables were assessed in 165 American high school students (47 % female; 92 % White), who were then followed into their college years, at which time mathematics courses taken, course-taking intentions, and utility value were assessed. Implicit theories predicted course-taking intentions and utility value, but only self-concept of ability predicted courses taken, course-taking intentions, and utility value after controlling for prior mathematics achievement and baseline values. Expectancy for success in mathematics mediated associations between self-concept of ability and college outcomes. This research identifies self-concept of ability as a stronger predictor than implicit theories of mathematics motivation and behavior across several years: math self-concept is critical to sustained engagement in mathematics.
Alexander, Jeremy P; Hopkinson, Trent L; Wundersitz, Daniel W T; Serpell, Benjamin G; Mara, Jocelyn K; Ball, Nick B
2016-11-01
Alexander, JP, Hopkinson, TL, Wundersitz, DWT, Serpell, BG, Mara, JK, and Ball, NB. Validity of a wearable accelerometer device to measure average acceleration values during high-speed running. J Strength Cond Res 30(11): 3007-3013, 2016-The aim of this study was to determine the validity of an accelerometer to measure average acceleration values during high-speed running. Thirteen subjects performed three sprint efforts over a 40-m distance (n = 39). Acceleration was measured using a 100-Hz triaxial accelerometer integrated within a wearable tracking device (SPI-HPU; GPSports). To provide a concurrent measure of acceleration, timing gates were positioned at 10-m intervals (0-40 m). Accelerometer data collected during 0-10 m and 10-20 m provided a measure of average acceleration values. Accelerometer data was recorded as the raw output and filtered by applying a 3-point moving average and a 10-point moving average. The accelerometer could not measure average acceleration values during high-speed running. The accelerometer significantly overestimated average acceleration values during both 0-10 m and 10-20 m, regardless of the data filtering technique (p < 0.001). Body mass significantly affected all accelerometer variables (p < 0.10, partial η = 0.091-0.219). Body mass and the absence of a gravity compensation formula affect the accuracy and practicality of accelerometers. Until GPSports-integrated accelerometers incorporate a gravity compensation formula, the usefulness of any accelerometer-derived algorithms is questionable.
Are volcanic seismic b-values high, and if so when?
Roberts, Nick S.; Bell, Andrew F.; Main, Ian G.
2015-12-01
The Gutenberg-Richter exponent b is a measure of the relative proportion of large and small earthquakes. It is commonly used to infer material properties such as heterogeneity, or mechanical properties such as the state of stress from earthquake populations. It is 'well known' that the b-value tends to be high or very high for volcanic earthquake populations relative to b = 1 for those of tectonic earthquakes, and that b varies significantly with time during periods of unrest. We first review the supporting evidence from 34 case studies, and identify weaknesses in this argument due predominantly to small sample size, the narrow bandwidth of magnitude scales available, variability in the methods used to assess the minimum or cutoff magnitude Mc, and to infer b. Informed by this, we use synthetic realisations to quantify the effect of choice of the cutoff magnitude on maximum likelihood estimates of b, and suggest a new work flow for this choice. We present the first quantitative estimate of the error in b introduced by uncertainties in estimating Mc, as a function of the number of events and the b-value itself. This error can significantly exceed the commonly-quoted statistical error in the estimated b-value, especially for the case that the underlying b-value is high. We apply the new methods to data sets from recent periods of unrest in El Hierro and Mount Etna. For El Hierro we confirm significantly high b-values of 1.5-2.5 prior to the 10 October 2011 eruption. For Mount Etna the b-values are indistinguishable from b = 1 within error, except during the flank eruptions at Mount Etna in 2001-2003, when 1.5 < b < 2.0. For the time period analysed, they are rarely lower than b = 1. Our results confirm that these volcano-tectonic earthquake populations can have systematically high b-values, especially when associated with eruptions. At other times they can be indistinguishable from those of tectonic earthquakes within the total error. The results have significant
Dai, Fengzhao; Tang, Feng; Wang, Xiangzhao; Sasaki, Osami; Zhang, Min
2013-06-10
In a recent paper [J. Opt. Soc. Am. A 29, 2038 (2012)], we proposed a generalized high spatial resolution zonal wavefront reconstruction method for lateral shearing interferometry. The test wavefront can be reconstructed with high spatial resolution by using linear interpolation on a subgrid for initial values estimation. In the current paper, we utilize the difference between the Zernike polynomial fitting method and linear interpolation in determining the subgrid initial values. The validity of the proposed method is investigated through comparison with the previous high spatial resolution zonal method. Simulation results show that the proposed method is more accurate and more stable to shear ratios compared with the previous method. A comprehensive comparison of the properties of the proposed method, the previous high spatial resolution zonal method, and the modal method is performed.
Vorburger, Robert S; Habeck, Christian G; Narkhede, Atul; Guzman, Vanessa A; Manly, Jennifer J; Brickman, Adam M
2016-01-01
Diffusion tensor imaging suffers from an intrinsic low signal-to-noise ratio. Bootstrap algorithms have been introduced to provide a non-parametric method to estimate the uncertainty of the measured diffusion parameters. To quantify the variability of the principal diffusion direction, bootstrap-derived metrics such as the cone of uncertainty have been proposed. However, bootstrap-derived metrics are not independent of the underlying diffusion profile. A higher mean diffusivity causes a smaller signal-to-noise ratio and, thus, increases the measurement uncertainty. Moreover, the goodness of the tensor model, which relies strongly on the complexity of the underlying diffusion profile, influences bootstrap-derived metrics as well. The presented simulations clearly depict the cone of uncertainty as a function of the underlying diffusion profile. Since the relationship of the cone of uncertainty and common diffusion parameters, such as the mean diffusivity and the fractional anisotropy, is not linear, the cone of uncertainty has a different sensitivity. In vivo analysis of the fornix reveals the cone of uncertainty to be a predictor of memory function among older adults. No significant correlation occurs with the common diffusion parameters. The present work not only demonstrates the cone of uncertainty as a function of the actual diffusion profile, but also discloses the cone of uncertainty as a sensitive predictor of memory function. Future studies should incorporate bootstrap-derived metrics to provide more comprehensive analysis.
Harvesting Robots for High-value Crops: State-of-the-art Review and Challenges Ahead
Bac, C.W.; Henten, van E.; Hemming, J.; Edan, Y.
2014-01-01
This review article analyzes state-of-the-art and future perspectives for harvesting robots in high-value crops. The objectives were to characterize the crop environment relevant for robotic harvesting, to perform a literature review on the state-of-the-art of harvesting robots using quantitative me
Prognostic value of p53 for high risk superficial bladder cancer with long-term followup.
Moonen, P.M.J.; Balken-Ory, B. van; Kiemeney, L.A.L.M.; Schalken, J.A.; Witjes, J.A.
2007-01-01
PURPOSE: The risk of muscle invasive disease in a high risk patient with superficial bladder cancer is up to 50%. Identifying patients at risk for progression remains an unsolved problem. A suggested prognosticator is mutations in the p53 tumor suppressor gene. We determined the value of p53 mutatio
Prognostic value of high sensitive C-reactive protein in subjects with silent myocardial ischemia
DEFF Research Database (Denmark)
Mouridsen, Mette; Intzilakis, Theodoros; Binici, Zeynep
2012-01-01
OBJECTIVES: The aim of this study was to evaluate the prognostic value of high sensitive C-reactive protein (CRP) in subjects with silent myocardial ischemia (SMI). DESIGN: In total, 678 healthy men and women aged 55 to 75 years with no history of cardiovascular disease or stroke were included...
Guo, Jiesi; Marsh, Herbert W.; Morin, Alexandre J. S.; Parker, Philip D.; Kaur, Gurvinder
2015-01-01
(This study examines the directionality of the associations among cognitive assets (IQ, academic achievement), motivational beliefs (academic self-concept, task values), and educational and occupational aspirations over time from late adolescence (Grade 10) into early adulthood (5 years post high school). Participants were from a nationally…
Assessing the Value of Rural California High School Career Technical Education
Morehead, Coleen Louise
2015-01-01
While empirical studies on rural education have defined many of the socioeconomic factors associated with rural students nationally, there is a lack of definitive and comprehensive research defining the benefit or value of career technical education for rural California high school students. Consequently, this lack of research may in turn…
Diagnostic value of high-resolution sonography in ulnar neuropathy at the elbow
Beekman, R; Schoemaker, MC; van der Plas, JPL; van den Berg, LH; Franssen, H; Wokke, JHJ; Uitdehaag, BMJ; Visser, LH
2004-01-01
Objective: To determine the diagnostic value of high-resolution sonography in ulnar neuropathy at the elbow (UNE). Methods: Sonographic ulnar nerve diameter measurement was compared at three levels around the medial epicondyle with a criterion standard including clinical and electrophysiologic chara
Endophytes as in vitro production platforms of high value plant secondary metabolites.
Venugopalan, Aarthi; Srivastava, Smita
2015-11-01
Many reports have been published on bioprospecting of endophytic fungi capable of producing high value bioactive molecules like, paclitaxel, vincristine, vinblastine, camptothecin and podophyllotoxin. However, commercial exploitation of endophytes for high value-low volume plant secondary metabolites remains elusive due to widely reported genomic instability of endophytes in the axenic culture. While most of the endophyte research focuses on screening endophytes for novel or existing high value biomolecules, very few reports seek to explore the possible mechanisms of production of host-plant associated or novel secondary metabolites in these organisms. With an overview of host-endophyte relationship and its possible impact on the secondary metabolite production potential of endophytes, the review highlights the evidence reported for and against the presence of host-independent biosynthetic machinery in endophytes. The review aims to address the question, why should and how can endophytes be exploited for large scale in vitro production of high value phytochemicals? In this regard, various bioprocess optimization strategies that have been applied to sustain and enhance the product yield from the endophytes have also been described in detail. Further, techniques like mixed fermentation/co-cultivation and use of epigenetic modifiers have also been discussed as potential strategies to activate cryptic gene clusters in endophytes, thereby aiding in novel metabolite discovery and overcoming the limitations associated with axenic culture of endophytes.
Characterization of Paschen Curve Anomolies at High P*D Values
2011-06-01
pulsed power systems often employ gas switches due to their high power and voltage handling capabilities. Vacuum switches such as the thyratrons ... model to higher pd values, which is consistent with published literature from many references. The point divergence of the measured data from
Cyanobacteria as a Platform for the High-Value Chemicals Production
DEFF Research Database (Denmark)
Wlodarczyk, Artur Jacek
consumer demands of an ever growing population. Considering the ability to convert solar energy and carbon dioxide into biomass, cyanobacteria and microalgae have potential for becoming such alternative in the future. Biosynthesis of a great number of plant high-value secondary metabolites requires...
High value co-products from wine byproducts (II): polyphenols and antioxidant activity
Energy Technology Data Exchange (ETDEWEB)
Femenia, A.; Gonzalez-Centeno, M. R.; Garau, M. C.; Sastre-Serrano, G.; Rosello, C.
2009-07-01
The by-products of the grape/wine industry have recently attracted considerable interest as important sources of high-value antioxidants. these can be extracted from stems, such as resveratrol,and from grape pomace which contains polyphenols, procyanidin and antrocyanins. (Author)
Assessing the Value of Rural California High School Career Technical Education
Morehead, Coleen Louise
2015-01-01
While empirical studies on rural education have defined many of the socioeconomic factors associated with rural students nationally, there is a lack of definitive and comprehensive research defining the benefit or value of career technical education for rural California high school students. Consequently, this lack of research may in turn…
Cyanobacteria as a Platform for the High-Value Chemicals Production
DEFF Research Database (Denmark)
Wlodarczyk, Artur Jacek
consumer demands of an ever growing population. Considering the ability to convert solar energy and carbon dioxide into biomass, cyanobacteria and microalgae have potential for becoming such alternative in the future. Biosynthesis of a great number of plant high-value secondary metabolites requires...
A Bootstrapping Model of Frequency and Context Effects in Word Learning.
Kachergis, George; Yu, Chen; Shiffrin, Richard M
2017-04-01
Prior research has shown that people can learn many nouns (i.e., word-object mappings) from a short series of ambiguous situations containing multiple words and objects. For successful cross-situational learning, people must approximately track which words and referents co-occur most frequently. This study investigates the effects of allowing some word-referent pairs to appear more frequently than others, as is true in real-world learning environments. Surprisingly, high-frequency pairs are not always learned better, but can also boost learning of other pairs. Using a recent associative model (Kachergis, Yu, & Shiffrin, 2012), we explain how mixing pairs of different frequencies can bootstrap late learning of the low-frequency pairs based on early learning of higher frequency pairs. We also manipulate contextual diversity, the number of pairs a given pair appears with across training, since it is naturalistically confounded with frequency. The associative model has competing familiarity and uncertainty biases, and their interaction is able to capture the individual and combined effects of frequency and contextual diversity on human learning. Two other recent word-learning models do not account for the behavioral findings. Copyright © 2016 Cognitive Science Society, Inc.
The lightcone bootstrap and the spectrum of the 3d Ising CFT
Simmons-Duffin, David
2017-03-01
We compute numerically the dimensions and OPE coefficients of several operators in the 3d Ising CFT, and then try to reverse-engineer the solution to crossing symmetry analytically. Our key tool is a set of new techniques for computing infinite sums of SL(2, R ) conformal blocks. Using these techniques, we solve the lightcone bootstrap to all orders in an asymptotic expansion in large spin, and suggest a strategy for going beyond the large spin limit. We carry out the first steps of this strategy for the 3d Ising CFT, deriving analytic approximations for the dimensions and OPE coefficients of several infinite families of operators in terms of the initial data {Δσ, Δ ɛ , f σσɛ , f ɛɛɛ , c T }. The analytic results agree with numerics to high precision for about 100 low-twist operators (correctly accounting for O(1) mixing effects between large-spin families). Plugging these results back into the crossing equations, we obtain approximate analytic constraints on the initial data.
2015-09-01
contract for ongoing employment ” (Cohany 1996, 1). According to the BLS February 1995 CPS, 12 million persons or 10 percent of the working U.S. population...and regulations are not followed, the firing may be reversed with penalties assessed to the employer (Langford 2015, personal communication...for personal injury or death) (Kiker 1966). Historically, the value of human beings was measured by two distinct methods: the cost-of-production and
Directory of Open Access Journals (Sweden)
Sembodo Ardi Widodo
2016-06-01
Full Text Available This research aims to determine the cultural education values of Islam Nusantara atIslamic Senior High School of Ali Maksum Krapyak Yogyakarta and how those values are taught through education. This researchuses qualitative approach by usingdata collection technique through observation, interviews, and documentation. The process of analysis data used is qualitative. The results of this study show that Islam Nusantara is an Islamic style of Indonesia, a combination of Islamic theological values with the local traditions, culture and customs. There are three pillars in Islam Nusantara, there arethought, movement, and 'amaliyya (action and there are five signs of Islam Nusantara, namely reform (ishlahiyyah, tawazuniyyah, tathawwu'iyyah, akhlaqiyyah (politeness, and tasamuh;The cultural education values of Islam Nusantara in MA Ali Maksum is the value of nationalism, diversity (pluralism, and the value of NU (tasamuh, tawazun, tawasuth; The madrasah activities consist ofMuludan, grave pilgrimage, halal bi halal, Muharroman, haul of the founder (dies natalis, competitions reading kitab kuning(yellow books, etc., that those are the typical product of Islam Nusantara.
Reynaud-Bouret, Patricia; Laurent, Béatrice
2012-01-01
Considering two independent Poisson processes, we address the question of testing equality of their respective intensities. We construct multiple testing procedures from the aggregation of single tests whose testing statistics come from model selection, thresholding and/or kernel estimation methods. The corresponding critical values are computed through a non-asymptotic wild bootstrap approach. The obtained tests are proved to be exactly of level $\\alpha$, and to satisfy non-asymptotic oracle type inequalities. From these oracle type inequalities, we deduce that our tests are adaptive in the minimax sense over a large variety of classes of alternatives based on classical and weak Besov bodies in the univariate case, but also Sobolev and anisotropic Nikol'skii-Besov balls in the multivariate case. A simulation study furthermore shows that they strongly perform in practice.
Pang, Yi; Rong, Junchen; Su, Ning
2016-12-01
We consider ϕ 3 theory in 6 - 2 ɛ with F 4 global symmetry. The beta function is calculated up to 3 loops, and a stable unitary IR fixed point is observed. The anomalous dimensions of operators quadratic or cubic in ϕ are also computed. We then employ conformal bootstrap technique to study the fixed point predicted from the perturbative approach. For each putative scaling dimension of ϕ (Δ ϕ ), we obtain the corresponding upper bound on the scaling dimension of the second lowest scalar primary in the 26 representation ( Δ 26 2nd ) which appears in the OPE of ϕ × ϕ. In D = 5 .95, we observe a sharp peak on the upper bound curve located at Δ ϕ equal to the value predicted by the 3-loop computation. In D = 5, we observe a weak kink on the upper bound curve at ( Δ ϕ , Δ 26 2nd ) = (1.6, 4).
Evaluating the Value of High Spatial Resolution in National Capacity Expansion Models using ReEDS
Energy Technology Data Exchange (ETDEWEB)
Krishnan, Venkat; Cole, Wesley
2016-11-14
Power sector capacity expansion models (CEMs) have a broad range of spatial resolutions. This paper uses the Regional Energy Deployment System (ReEDS) model, a long-term national scale electric sector CEM, to evaluate the value of high spatial resolution for CEMs. ReEDS models the United States with 134 load balancing areas (BAs) and captures the variability in existing generation parameters, future technology costs, performance, and resource availability using very high spatial resolution data, especially for wind and solar modeled at 356 resource regions. In this paper we perform planning studies at three different spatial resolutions--native resolution (134 BAs), state-level, and NERC region level--and evaluate how results change under different levels of spatial aggregation in terms of renewable capacity deployment and location, associated transmission builds, and system costs. The results are used to ascertain the value of high geographically resolved models in terms of their impact on relative competitiveness among renewable energy resources.
Empirical Analysis of Value-at-Risk Estimation Methods Using Extreme Value Theory
Institute of Scientific and Technical Information of China (English)
无
2001-01-01
This paper investigates methods of value-at-risk (VaR) estimation using extreme value theory (EVT). Itcompares two different estimation methods, 。two-step subsample bootstrap" based on moment estimation and maximumlikelihood estimation (MLE), according to their theoretical bases and computation procedures. Then, the estimationresults are analyzed together with those of normal method and empirical method. The empirical research of foreignexchange data shows that the EVT methods have good characters in estimating VaR under extreme conditions and"two-step subsample bootstrap" method is preferable to MLE.
High Speed Multiple Valued Logic Full Adder Using Carbon Nano Tube Field Effect Transistor
Khatir, Ashkan; Mahmoudi, Iman
2011-01-01
High speed Full-Adder (FA) module is a critical element in designing high performance arithmetic circuits. In this paper, we propose a new high speed multiple-valued logic FA module. The proposed FA is constructed by 14 transistors and 3 capacitors, using carbon nano-tube field effect transistor (CNFET) technology. Furthermore, our proposed technique has been examined in different voltages (i.e., 0.65v and 0.9v). The observed results reveal power consumption and power delay product (PDP) improvements compared to existing FA counterparts
High Speed Multiple Valued Logic Full Adder Using Carbon Nano Field Effect Transistor
Directory of Open Access Journals (Sweden)
Ashkan Khatir
2011-03-01
Full Text Available High speed Full-Adder (FA module is a critical element in designing high performance arithmeticcircuits. In this paper, we propose a new high speed multiple-valued logic FA module. The proposed FAis constructed by 14 transistors and 3 capacitors, using carbon nano-tube field effect transistor (CNFETtechnology. Furthermore, our proposed technique has been examined in different voltages (i.e., 0.65v and0.9v. The observed results reveal power consumption and power delay product (PDP improvementscompared to existing FA counterparts.
Closure of the operator product expansion in the non-unitary bootstrap
Esterlis, Ilya; Fitzpatrick, A. Liam; Ramirez, David M.
2016-11-01
We use the numerical conformal bootstrap in two dimensions to search for finite, closed sub-algebras of the operator product expansion (OPE), without assuming unitarity. We find the minimal models as special cases, as well as additional lines of solutions that can be understood in the Coulomb gas formalism. All the solutions we find that contain the vacuum in the operator algebra are cases where the external operators of the bootstrap equation are degenerate operators, and we argue that this follows analytically from the expressions in arXiv:1202.4698 for the crossing matrices of Virasoro conformal blocks. Our numerical analysis is a special case of the "Gliozzi" bootstrap method, and provides a simpler setting in which to study technical challenges with the method.
Closure of the Operator Product Expansion in the Non-Unitary Bootstrap
Esterlis, Ilya; Ramirez, David
2016-01-01
We use the numerical conformal bootstrap in two dimensions to search for finite, closed sub-algebras of the operator product expansion (OPE), without assuming unitarity. We find the minimal models as special cases, as well as additional lines of solutions that can be understood in the Coulomb gas formalism. All the solutions we find that contain the vacuum in the operator algebra are cases where the external operators of the bootstrap equation are degenerate operators, and we argue that this follows analytically from the expressions in arXiv:1202.4698 for the crossing matrices of Virasoro conformal blocks. Our numerical analysis is a special case of the "Gliozzi" bootstrap method, and provides a simpler setting in which to study technical challenges with the method. In the supplementary material, we provide a Mathematica notebook that automates the calculation of the crossing matrices and OPE coefficients for degenerate operators using the formulae of Dotsenko and Fateev.
Closure of the operator product expansion in the non-unitary bootstrap
Energy Technology Data Exchange (ETDEWEB)
Esterlis, Ilya [Stanford Institute for Theoretical Physics, Stanford University,Via Pueblo, Stanford, CA 94305 (United States); Fitzpatrick, A. Liam [Department of Physics, Boston University,Commonwealth Ave, Boston, MA, 02215 (United States); Ramirez, David M. [Stanford Institute for Theoretical Physics, Stanford University,Via Pueblo, Stanford, CA 94305 (United States)
2016-11-07
We use the numerical conformal bootstrap in two dimensions to search for finite, closed sub-algebras of the operator product expansion (OPE), without assuming unitarity. We find the minimal models as special cases, as well as additional lines of solutions that can be understood in the Coulomb gas formalism. All the solutions we find that contain the vacuum in the operator algebra are cases where the external operators of the bootstrap equation are degenerate operators, and we argue that this follows analytically from the expressions in http://arxiv.org/abs/1202.4698 for the crossing matrices of Virasoro conformal blocks. Our numerical analysis is a special case of the “Gliozzi” bootstrap method, and provides a simpler setting in which to study technical challenges with the method. In the supplementary material, we provide a Mathematica notebook that automates the calculation of the crossing matrices and OPE coefficients for degenerate operators using the formulae of Dotsenko and Fateev.
The S-matrix Bootstrap I: QFT in AdS
Paulos, Miguel F; Toledo, Jonathan; van Rees, Balt C; Vieira, Pedro
2016-01-01
We propose a strategy to study massive Quantum Field Theory (QFT) using conformal bootstrap methods. The idea is to consider QFT in hyperbolic space and study correlation functions of its boundary operators. We show that these are solutions of the crossing equations in one lower dimension. By sending the curvature radius of the background hyperbolic space to infinity we expect to recover flat-space physics. We explain that this regime corresponds to large scaling dimensions of the boundary operators, and discuss how to obtain the flat-space scattering amplitudes from the corresponding limit of the boundary correlators. We implement this strategy to obtain universal bounds on the strength of cubic couplings in 2D flat-space QFTs using 1D conformal bootstrap techniques. Our numerical results match precisely the analytic bounds obtained in our companion paper using S-matrix bootstrap techniques.
Bootstrap confidence intervals in a complex situation: A sequential paired clinical trial
Energy Technology Data Exchange (ETDEWEB)
Morton, S.C.
1988-06-01
This paper considers the problem of determining a confidence interval for the difference between two treatments in a simplified sequential paired clinical trial, which is analogous to setting an interval for the drift of a random walk subject to a parabolic stopping boundary. Three bootstrap methods of construction are applied: Efron's accelerated bias-covered, the DiCiccio-Romano, and the bootstrap-t. The results are compared with a theoretical approximate interval due to Siegmund. Difficulties inherent in the use of these bootstrap methods in a complex situations are illustrated. The DiCiccio-Romano method is shown to be the easiest to apply and to work well. 13 refs.
Lightweight CoAP-Based Bootstrapping Service for the Internet of Things
Directory of Open Access Journals (Sweden)
Dan Garcia-Carrillo
2016-03-01
Full Text Available The Internet of Things (IoT is becoming increasingly important in several fields of industrial applications and personal applications, such as medical e-health, smart cities, etc. The research into protocols and security aspects related to this area is continuously advancing in making these networks more reliable and secure, taking into account these aspects by design. Bootstrapping is a procedure by which a user obtains key material and configuration information, among other parameters, to operate as an authenticated party in a security domain. Until now solutions have focused on re-using security protocols that were not developed for IoT constraints. For this reason, in this work we propose a design and implementation of a lightweight bootstrapping service for IoT networks that leverages one of the application protocols used in IoT : Constrained Application Protocol (CoAP. Additionally, in order to provide flexibility, scalability, support for large scale deployment, accountability and identity federation, our design uses technologies such as the Extensible Authentication Protocol (EAP and Authentication Authorization and Accounting (AAA. We have named this service CoAP-EAP. First, we review the state of the art in the field of bootstrapping and specifically for IoT. Second, we detail the bootstrapping service: the architecture with entities and interfaces and the flow operation. Third, we obtain performance measurements of CoAP-EAP (bootstrapping time, memory footprint, message processing time, message length and energy consumption and compare them with PANATIKI. The most significant and constrained representative of the bootstrapping solutions related with CoAP-EAP. As we will show, our solution provides significant improvements, mainly due to an important reduction of the message length.
Lightweight CoAP-Based Bootstrapping Service for the Internet of Things
Garcia-Carrillo, Dan; Marin-Lopez, Rafael
2016-01-01
The Internet of Things (IoT) is becoming increasingly important in several fields of industrial applications and personal applications, such as medical e-health, smart cities, etc. The research into protocols and security aspects related to this area is continuously advancing in making these networks more reliable and secure, taking into account these aspects by design. Bootstrapping is a procedure by which a user obtains key material and configuration information, among other parameters, to operate as an authenticated party in a security domain. Until now solutions have focused on re-using security protocols that were not developed for IoT constraints. For this reason, in this work we propose a design and implementation of a lightweight bootstrapping service for IoT networks that leverages one of the application protocols used in IoT : Constrained Application Protocol (CoAP). Additionally, in order to provide flexibility, scalability, support for large scale deployment, accountability and identity federation, our design uses technologies such as the Extensible Authentication Protocol (EAP) and Authentication Authorization and Accounting (AAA). We have named this service CoAP-EAP. First, we review the state of the art in the field of bootstrapping and specifically for IoT. Second, we detail the bootstrapping service: the architecture with entities and interfaces and the flow operation. Third, we obtain performance measurements of CoAP-EAP (bootstrapping time, memory footprint, message processing time, message length and energy consumption) and compare them with PANATIKI. The most significant and constrained representative of the bootstrapping solutions related with CoAP-EAP. As we will show, our solution provides significant improvements, mainly due to an important reduction of the message length. PMID:26978362
Lightweight CoAP-Based Bootstrapping Service for the Internet of Things.
Garcia-Carrillo, Dan; Marin-Lopez, Rafael
2016-03-11
The Internet of Things (IoT) is becoming increasingly important in several fields of industrial applications and personal applications, such as medical e-health, smart cities, etc. The research into protocols and security aspects related to this area is continuously advancing in making these networks more reliable and secure, taking into account these aspects by design. Bootstrapping is a procedure by which a user obtains key material and configuration information, among other parameters, to operate as an authenticated party in a security domain. Until now solutions have focused on re-using security protocols that were not developed for IoT constraints. For this reason, in this work we propose a design and implementation of a lightweight bootstrapping service for IoT networks that leverages one of the application protocols used in IoT : Constrained Application Protocol (CoAP). Additionally, in order to provide flexibility, scalability, support for large scale deployment, accountability and identity federation, our design uses technologies such as the Extensible Authentication Protocol (EAP) and Authentication Authorization and Accounting (AAA). We have named this service CoAP-EAP. First, we review the state of the art in the field of bootstrapping and specifically for IoT. Second, we detail the bootstrapping service: the architecture with entities and interfaces and the flow operation. Third, we obtain performance measurements of CoAP-EAP (bootstrapping time, memory footprint, message processing time, message length and energy consumption) and compare them with PANATIKI. The most significant and constrained representative of the bootstrapping solutions related with CoAP-EAP. As we will show, our solution provides significant improvements, mainly due to an important reduction of the message length.
Synthesization of high-capacity auto-associative memories using complex-valued neural networks
Huang, Yu-Jiao; Wang, Xiao-Yan; Long, Hai-Xia; Yang, Xu-Hua
2016-12-01
In this paper, a novel design procedure is proposed for synthesizing high-capacity auto-associative memories based on complex-valued neural networks with real-imaginary-type activation functions and constant delays. Stability criteria dependent on external inputs of neural networks are derived. The designed networks can retrieve the stored patterns by external inputs rather than initial conditions. The derivation can memorize the desired patterns with lower-dimensional neural networks than real-valued neural networks, and eliminate spurious equilibria of complex-valued neural networks. One numerical example is provided to show the effectiveness and superiority of the presented results. Project supported by the National Natural Science Foundation of China (Grant Nos. 61503338, 61573316, 61374152, and 11302195) and the Natural Science Foundation of Zhejiang Province, China (Grant No. LQ15F030005).
Simultaneous QTL detection and genomic breeding value estimation using high density SNP chips
Directory of Open Access Journals (Sweden)
Veerkamp Roel F
2010-03-01
Full Text Available Abstract Background The simulated dataset of the 13th QTL-MAS workshop was analysed to i detect QTL and ii predict breeding values for animals without phenotypic information. Several parameterisations considering all SNP simultaneously were applied using Gibbs sampling. Results Fourteen QTL were detected at the different time points. Correlations between estimated breeding values were high between models, except when the model was used that assumed that all SNP effects came from one distribution. The model that used the selected 14 SNP found associated with QTL, gave close to unity correlations with the full parameterisations. Conclusions Nine out of 18 QTL were detected, however the six QTL for inflection point were missed. Models for genomic selection were indicated to be fairly robust, e.g. with respect to accuracy of estimated breeding values. Still, it is worthwhile to investigate the number QTL underlying the quantitative traits, before choosing the model used for genomic selection.
High-Performance Buildings – Value, Messaging, Financial and Policy Mechanisms
Energy Technology Data Exchange (ETDEWEB)
McCabe, Molly
2011-02-22
At the request of the Pacific Northwest National Laboratory, an in-depth analysis of the rapidly evolving state of real estate investments, high-performance building technology, and interest in efficiency was conducted by HaydenTanner, LLC, for the U.S. Department of Energy (DOE) Building Technologies Program. The analysis objectives were • to evaluate the link between high-performance buildings and their market value • to identify core messaging to motivate owners, investors, financiers, and others in the real estate sector to appropriately value and deploy high-performance strategies and technologies across new and existing buildings • to summarize financial mechanisms that facilitate increased investment in these buildings. To meet these objectives, work consisted of a literature review of relevant writings, examination of existing and emergent financial and policy mechanisms, interviews with industry stakeholders, and an evaluation of the value implications through financial modeling. This report documents the analysis methodology and findings, conclusion and recommendations. Its intent is to support and inform the DOE Building Technologies Program on policy and program planning for the financing of high-performance new buildings and building retrofit projects.
Energy Technology Data Exchange (ETDEWEB)
Niehof, Jonathan T.; Morley, Steven K.
2012-01-01
We review and develop techniques to determine associations between series of discrete events. The bootstrap, a nonparametric statistical method, allows the determination of the significance of associations with minimal assumptions about the underlying processes. We find the key requirement for this method: one of the series must be widely spaced in time to guarantee the theoretical applicability of the bootstrap. If this condition is met, the calculated significance passes a reasonableness test. We conclude with some potential future extensions and caveats on the applicability of these methods. The techniques presented have been implemented in a Python-based software toolkit.
Bootstrap Sequential Determination of the Co-integration Rank in VAR Models
DEFF Research Database (Denmark)
Guiseppe, Cavaliere; Rahbæk, Anders; Taylor, A.M. Robert
with empirical rejection frequencies often very much in excess of the nominal level. As a consequence, bootstrap versions of these tests have been developed. To be useful, however, sequential procedures for determining the co-integrating rank based on these bootstrap tests need to be consistent, in the sense...... that the probability of selecting a rank smaller than (equal to) the true co-integrating rank will converge to zero (one minus the marginal significance level), as the sample size diverges, for general I(1) processes. No such likelihood-based procedure is currently known to be available. In this paper we fill this gap...
Improving Web Learning through model Optimization using Bootstrap for a Tour-Guide Robot
Directory of Open Access Journals (Sweden)
Rafael León
2012-09-01
Full Text Available We perform a review of Web Mining techniques and we describe a Bootstrap Statistics methodology applied to pattern model classifier optimization and verification for Supervised Learning for Tour-Guide Robot knowledge repository management. It is virtually impossible to test thoroughly Web Page Classifiers and many other Internet Applications with pure empirical data, due to the need for human intervention to generate training sets and test sets. We propose using the computer-based Bootstrap paradigm to design a test environment where they are checked with better reliability
Economic Evaluations for the Carbon Dioxide-involved Production of High-value Chemicals
Energy Technology Data Exchange (ETDEWEB)
Lee, Ji Hyun; Lee, Dong Woog; Jang, Se Gyu; Kwak, No-Sang; Lee, In Young; Jang, Kyung Ryoung; Shim, Jae-Goo [KEPCO Research Institute, Daejon (Korea, Republic of); Choi, Jong Shin [Korea East-West Power Co. LTD, Seoul (Korea, Republic of)
2014-06-15
Economic evaluation of the manufacturing technology of high-value chemicals through the carbonation reaction of carbon dioxide contained in the flue gas was performed, and analysis of the IRR (Internal Rate of Return) and whole profit along the production plan of the final product was conducted. Through a carbonation reaction with sodium hydroxide that is generated from electrolysis and by using carbon dioxide in the combustion gas that is generated in the power plant, it is possible to get a high value products such as sodium bicarbonate compound and also to reduce the carbon dioxide emission simultaneously. The IRR (Internal Rate of Return) and NPV (Net Present Value) methods were used for the economic evaluation of the process which could handle carbon dioxide of 100 tons per day in the period of the 20 years of plant operation. The results of economic evaluation showed that the IRR of baseline case of technology was 67.2% and the profit that obtained during the whole operation period (20 years) was 346,922 million won based on NPV value. When considering ETS due to the emissions trading enforcement that will be activated in 2015, the NPV was improved to a 6,000 million won. Based on this results, it could be concluded that this CO2 carbonation technology is an cost-effective technology option for the reduction of greenhouse gas.
Directory of Open Access Journals (Sweden)
Yustiani Yustiani
2015-06-01
Full Text Available Cases of cheating, promiscuity, making sordid video student in the classroom are the phenomena of decline in character education at the school. In this sense, character education is essential to emphasized. This research uses qualitative approach, by applying design research CIPP model (Context, Input, Process, and Product. In context of building the nation character values at the school will success on condition that it is accompanied with system and climate supported by each school. One of supporting system and climate is the headmaster's policies on the regulation that support the implementation of character education, and this policy should be supported by infrastructure of the school. The input aspect that determines inculcation of nation character values in these both schools is the quality of the school resources including headmaster, teachers, educational staffs, students, and education infrastructures. From the aspects of process, inculcation nation character values on these schools is implemented through the integration of the Islamic religious education subject and culture of the school. Syllabus and RPP on subjects of Islamic religious education in State Senior High School 1 Kudus and State Senior High School 1 Jepara have already been insightful with the education of nation character. The aspects of product from internalization of cultural values and nation character are embodied in attitudes and behaviors of the students at school and society.
Lai, Hong; Orgun, Mehmet A.; Pieprzyk, Josef; Li, Jing; Luo, Mingxing; Xiao, Jinghua; Xiao, Fuyuan
2016-08-01
We propose an approach that achieves high-capacity quantum key distribution using Chebyshev-map values corresponding to Lucas numbers coding. In particular, we encode a key with the Chebyshev-map values corresponding to Lucas numbers and then use k-Chebyshev maps to achieve consecutive and flexible key expansion and apply the pre-shared classical information between Alice and Bob and fountain codes for privacy amplification to solve the security of the exchange of classical information via the classical channel. Consequently, our high-capacity protocol does not have the limitations imposed by orbital angular momentum and down-conversion bandwidths, and it meets the requirements for longer distances and lower error rates simultaneously.
Molecular Imprinting for High-Added Value Metals: An Overview of Recent Environmental Applications
Directory of Open Access Journals (Sweden)
George Z. Kyzas
2014-01-01
Full Text Available One of the most hot topics of recent research is the reuse of some compounds existing as pollutants in environment. These compounds (molecules, ions, complexes, etc. are of high-added value and it will be ideal to selectively bind them with any environmental application and reuse them in their initial or modified form. The latter can be achieved using molecular imprinting. In the present review article, an overview of the recent attempts for the selective binding of some precious metals (i.e., gold, silver, and platinum of high-added value is done using molecular imprinted polymers (MIPs as materials. The simplicity of their use, their relatively low cost, and the broad range of possible guest molecules (small organic molecules, ions, metals, and also biological macromolecules have since led to the important development of molecular imprinting.
Shanmugavadivu, P.; Eliahim Jeevaraj, P. S.
2014-06-01
The Adaptive Iterated Functions Systems (AIFS) Filter presented in this paper has an outstanding potential to attenuate the fixed-value impulse noise in images. This filter has two distinct phases namely noise detection and noise correction which uses Measure of Statistics and Iterated Function Systems (IFS) respectively. The performance of AIFS filter is assessed by three metrics namely, Peak Signal-to-Noise Ratio (PSNR), Mean Structural Similarity Index Matrix (MSSIM) and Human Visual Perception (HVP). The quantitative measures PSNR and MSSIM endorse the merit of this filter in terms of degree of noise suppression and details/edge preservation respectively, in comparison with the high performing filters reported in the recent literature. The qualitative measure HVP confirms the noise suppression ability of the devised filter. This computationally simple noise filter broadly finds application wherein the images are highly degraded by fixed-value impulse noise.
Lai, Hong; Orgun, Mehmet A.; Pieprzyk, Josef; Li, Jing; Luo, Mingxing; Xiao, Jinghua; Xiao, Fuyuan
2016-11-01
We propose an approach that achieves high-capacity quantum key distribution using Chebyshev-map values corresponding to Lucas numbers coding. In particular, we encode a key with the Chebyshev-map values corresponding to Lucas numbers and then use k-Chebyshev maps to achieve consecutive and flexible key expansion and apply the pre-shared classical information between Alice and Bob and fountain codes for privacy amplification to solve the security of the exchange of classical information via the classical channel. Consequently, our high-capacity protocol does not have the limitations imposed by orbital angular momentum and down-conversion bandwidths, and it meets the requirements for longer distances and lower error rates simultaneously.
Indian Academy of Sciences (India)
SHATAKSHEE CHATTERJEE; PARTHA P. MAJUMDER; PRIYANKA PANDEY
2016-09-01
Study of temporal trajectory of gene expression is important. RNA sequencing is popular in genome-scale studies of transcription. Because of high expenses involved, many time-course RNA sequencing studies are challenged by inadequacy of sample sizes. This poses difficulties in conducting formal statistical tests of significance of null hypotheses. We propose a bootstrap algorithm to identify ‘cognizable’ ‘time-trends’ of gene expression. Properties of the proposed algorithm are derived using a simulation study. The proposed algorithm captured known ‘time-trends’ in the simulated data with a high probability of success, even when sample sizes were small (n<10). The proposed statistical method is efficient and robust to capture ‘cognizable’ ‘time-trends’ in RNA sequencing data.
Hardware-based high-performance string lookup with value retrieval using extended Bloom filter
Institute of Scientific and Technical Information of China (English)
LI Qi-yue; QU Yu-gui; ZHAO Bao-hua
2008-01-01
In network packet processing, high-performance string lookup systems are very important. In this article, an extended Bloom filter data structure is introduced to support value retrieval string lookup, and to improve its performance, a weighted extended Bloom filter (WEBF) structure is generalized. The optimal configuration of the WEBF is then derived, and it is shown that it outperforms the traditional Bloom filter. Finally, an application-specific integrated circuit (ASIC)-based technique using WEBF is outlined.
HIGH NATURE VALUE GRASSLANDS FROM ARRHENATHERION ALLIANCE IDENTIFIED IN MUREŞ COUNTY
Silvia Oroian; Mihaela Samarghitan; MARIANA Hiritiu; SANDA Cosarca; CORNELIU Tanase
2016-01-01
Arrhenatherion alliance meadows are recognized to be among the best pastures in our country due to high productivity and good nutrition value. The research was conducted in several areas of Mures County. The studied grasslands were classified into two types of Natura 2000 habitats: 6510 Lowland hay meadows (Alopecurus pratensis, Sanguisorba officinalis) and 6520 Mountain hay meadows. The identified phytocoenosis belong to two plant associations: Arrhenatheretum elatioris Br.-Bl. Ex Scherrer 1...
Resilience-based perspectives to guiding high-nature-value farmland through socioeconomic change
DEFF Research Database (Denmark)
Plieninger, Tobias; Bieling, Claudia
2013-01-01
Global environmental challenges require approaches that integrate biodiversity conservation, food production, and livelihoods at landscape scales. We reviewed the approach of conserving biodiversity on "high-nature-value" (HNV) farmland, covering 75 million ha in Europe, from a resilience...... perspective. Despite growing recognition in natural resource policies, many HNV farmlands have vanished, and the remaining ones are vulnerable to socioeconomic changes. Using landscapelevel cases across Europe, we considered the following social-ecological system properties and components...
Applying cathodically polarised substrata to the restoration of a high value coral
Benedetti, Alessandro; Bramanti, Lorenzo; Tsounis, Gerogios; Faimali, Marco; Pavanello, Giovanni; Rossi, Sergio; Gili, Josep Maria; Santangelo, Giovanni
2011-01-01
Larval settlement of the high value red coral, Corallium rubrum, was studied on three different CaCO3 substrata, viz. lithogenic (marble), electro-accreted calcium carbonate in the presence and in the absence of cathodic polarisation. The last two substrata consisted of stainless steel plates galvanically coupled with Zn anodes. The electrochemical characterization of the settlement device was studied in order to investigate correlations between cathodic parameters (polarisation potential, cu...
Li, Zhaofeng; Alici, Kamil Boratay; Caglayan, Humeyra; Kafesaki, Maria; Soukoulis, Costas M; Ozbay, Ekmel
2012-03-12
A composite chiral metamaterial (CCMM) is designed and studied both numerically and experimentally. The CCMM is constructed by the combination of a continuous metallic wires structure and a purely chiral metamaterial (CMM) that consists of conjugated Rosettes. For the CMM, only very small, useful bands of negative index can be obtained for circularly polarized waves. These bands are all above the chiral resonance frequencies because of the high value of the effective parameter of relative permittivity ε. After the addition of the continuous metallic wires, which provide negative permittivity, the high value of ε can be partially compensated. Thus, a negative index band for the left circularly polarized wave that is below the chiral resonance frequency is obtained for the CCMM. At the same time, a negative index band for the right circularly polarized wave that is above the chiral resonance frequency is also obtained. Furthermore, both negative index bands correspond to the transmission peaks and have high values of the figure of merit. Therefore, the CCMM design that is proposed here is more suitable than the CMM for the construction of chiral metamaterials with a negative index.
Wang, Jiming; Liu, Wei; Xu, Xin; Zhang, Haibo; Xian, Mo
2013-10-01
Confronted with the gradual exhaustion of the earth's fossil energy resources and the grimmer environmental deterioration, the bio-based process to produce high-value added platform chemicals from renewable biomass is attracting growing interest. Escherichia coli has been chosen as a workhouse for the production of many valuable chemicals due to various advantages, such as clear genetic background, convenient to be genetically modified and good growth properties with low nutrient requirements. Rational strain development of E. coli achieved by metabolic engineering strategies has provided new processes for efficiently biotechnological production of various high-value chemical building blocks. This review focuses on recent progresses in metabolic engineering of E. coli that lead to efficient recombinant biocatalysts for production of high-value organic acids such as succinic acid, 3-hydroxypropanoic acid and glucaric acid as well as alcohols like glycerol and xylitol. Besides, this review also discusses several other platform chemicals, including 2,5-furan dicarboxylic acid, aspartic acid, glutamic acid, itaconic acid, levulinic acid, 3-hydroxy-gamma-butyrolactone and sorbitol, which have not been produced by E. coli until now.
Energy Technology Data Exchange (ETDEWEB)
Ramasamy, Karthikeyan K.; Gray, Michel J.; Job, Heather M.; Smith, Colin D.; Wang, Yong
2016-04-10
tA highly versatile ethanol conversion process to selectively generate high value compounds is pre-sented here. By changing the reaction temperature, ethanol can be selectively converted to >C2alcohols/oxygenates or phenolic compounds over hydrotalcite derived bi-functional MgO–Al2O3cata-lyst via complex cascade mechanism. Reaction temperature plays a role in whether aldol condensationor the acetone formation is the path taken in changing the product composition. This article containsthe catalytic activity comparison between the mono-functional and physical mixture counterpart to thehydrotalcite derived mixed oxides and the detailed discussion on the reaction mechanisms.
Kim, Se-Kang
2010-01-01
The aim of the current study is to validate the invariance of major profile patterns derived from multidimensional scaling (MDS) by bootstrapping. Profile Analysis via Multidimensional Scaling (PAMS) was employed to obtain profiles and bootstrapping was used to construct the sampling distributions of the profile coordinates and the empirical…
Application of a New Resampling Method to SEM: A Comparison of S-SMART with the Bootstrap
Bai, Haiyan; Sivo, Stephen A.; Pan, Wei; Fan, Xitao
2016-01-01
Among the commonly used resampling methods of dealing with small-sample problems, the bootstrap enjoys the widest applications because it often outperforms its counterparts. However, the bootstrap still has limitations when its operations are contemplated. Therefore, the purpose of this study is to examine an alternative, new resampling method…
Directory of Open Access Journals (Sweden)
Thawatchai Onjun
2012-02-01
Full Text Available The investigation of bootstrap current formation in ITER is carried out using BALDUR integrated predictive modelingcode. The combination of Mixed B/gB anomalous transport model and NLCASS module together with the pedestal model isused in BALDUR code to simulate the time evolution of temperature, density, and plasma current profiles. It was found inthe simulations that without the presence of ITB, a minimal fraction of bootstrap current (as well as low fusion performancewas achieved. The enhancement due to ITB depends sensitively on the strength of toroidal velocity. A sensitivity study wasalso carried out to optimize the bootstrap current fraction and plasma performance. It was found that the bootstrap currentfraction slightly improved; while the plasma performance greatly improved with increasing of NBI power or pedestal temperature.On the other hand, higher impurity concentration resulted in a significant degradation of fusion performance, buta smaller degradation in bootstrap current.
Hypercellularity Components of Glioblastoma Identified by High b-Value Diffusion-Weighted Imaging
Energy Technology Data Exchange (ETDEWEB)
Pramanik, Priyanka P. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Parmar, Hemant A. [Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Mammoser, Aaron G.; Junck, Larry R. [Department of Neurology, University of Michigan, Ann Arbor, Michigan (United States); Kim, Michelle M.; Tsien, Christina I.; Lawrence, Theodore S. [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Cao, Yue, E-mail: yuecao@med.umich.edu [Department of Radiation Oncology, University of Michigan, Ann Arbor, Michigan (United States); Department of Radiology, University of Michigan, Ann Arbor, Michigan (United States); Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan (United States)
2015-07-15
Purpose: Use of conventional magnetic resonance imaging (MRI) for target definition may expose glioblastomas (GB) to inadequate radiation dose coverage of the nonenhanced hypercellular subvolume. This study aimed to develop a technique to identify the hypercellular components of GB by using high b-value diffusion-weighted imaging (DWI) and to investigate its relationship with the prescribed 95% isodose volume (PDV) and progression-free survival (PFS). Methods and Materials: Twenty-one patients with GB underwent chemoradiation therapy post-resection and biopsy. Radiation therapy (RT) treatment planning was based upon conventional MRI. Pre-RT DWIs were acquired in 3 orthogonal directions with b-values of 0, 1000, and 3000 s/mm{sup 2}. Hypercellularity volume (HCV) was defined on the high b-value (3000 s/mm{sup 2}) DWI by a threshold method. Nonenhanced signified regions not covered by the Gd-enhanced gross tumor volume (GTV-Gd) on T1-weighted images. The PDV was used to evaluate spatial coverage of the HCV by the dose plan. Association between HCV and PFS or other clinical covariates were assessed using univariate proportional hazards regression models. Results: HCVs and nonenhanced HCVs varied from 0.58 to 67 cm{sup 3} (median: 9.8 cm{sup 3}) and 0.15 to 60 cm{sup 3} (median: 2.5 cm{sup 3}), respectively. Fourteen patients had incomplete dose coverage of the HCV, 6 of whom had >1 cm{sup 3} HCV missed by the 95% PDV (range: 1.01-25.4 cm{sup 3}). Of the 15 patients who progressed, 5 progressed earlier, within 6 months post-RT, and 10 patients afterward. Pre-RT HCVs within recurrent GTVs-Gd were 78% (range: 65%-89%) for the 5 earliest progressions but lower, 53% (range: 0%-85%), for the later progressions. HCV and nonenhanced HCV were significant negative prognostic indicators for PFS (P<.002 and P<.01, respectively). The hypercellularity subvolume not covered by the 95% PDV was a significant negative predictor for PFS (P<.05). Conclusions: High b-value DWI
Directory of Open Access Journals (Sweden)
Izabela CHMIEL
2012-03-01
Full Text Available Aim: To determine and analyse an alternative methodology for the analysis of a set of Likert responses measured on a common attitudinal scale when the primary focus of interest is on the relative importance of items in the set - with primary application to health-related quality of life (HRQOL measures. HRQOL questionnaires usually generate data that manifest evident departures from fundamental assumptions of Analysis of Variance (ANOVA approach, not only because of their discrete, bounded and skewed distributions, but also due to significant correlation between mean scores and their variances. Material and Methods: Questionnaire survey with SF-36 has been conducted among 142 convalescents after acute pancreatitis. The estimated scores of HRQOL were compared with use of the multiple comparisons procedures under Bonferroni-like adjustment, and with the bootstrap procedures. Results: In the data set studied, with the SF-36 outcome, the use of the multiple comparisons and bootstrap procedures for analysing HRQOL data provides results quite similar to conventional ANOVA and Rasch methods, suggested at frames of Classical Test Theory and Item Response Theory. Conclusions: These results suggest that the multiple comparisons and bootstrap both are valid methods for analysing HRQOL outcome data, in particular at case of doubts with appropriateness of the standard methods. Moreover, from practical point of view, the processes of the multiple comparisons and bootstrap procedures seems to be much easy to interpret by non-statisticians aimed to practise evidence based health care.
Bootstrap inference for pre-averaged realized volatility based on non-overlapping returns
DEFF Research Database (Denmark)
Gonçalves, Sílvia; Hounyo, Ulrich; Meddahi, Nour
The main contribution of this paper is to propose bootstrap methods for realized volatility-like estimators defined on pre-averaged returns. In particular, we focus on the pre-averaged realized volatility estimator proposed by Podolskij and Vetter (2009). This statistic can be written (up to a bi...
A bootstrap procedure to select hyperspectral wavebands related to tannin content
Ferwerda, J.G.; Skidmore, A.K.; Stein, A.
2006-01-01
Detection of hydrocarbons in plants with hyperspectral remote sensing is hampered by overlapping absorption pits, while the `optimal' wavebands for detecting some surface characteristics (e.g. chlorophyll, lignin, tannin) may shift. We combined a phased regression with a bootstrap procedure to find
Bootstrap-estimated land-to-water coefficients from the CBTN_v4 SPARROW model
Ator, Scott; Brakebill, John W.; Blomquist, Joel D.
2017-01-01
This file contains 200 sets of bootstrap-estimated land-to-water coefficients from the CBTN_v4 SPARROW model, which is documented in USGS Scientific Investigations Report 2011-5167. The coefficients were produced as part of CBTN_v4 model calibration to provide information about the uncertainty in model estimates.
DEFF Research Database (Denmark)
Malzahn, Dorthe; Opper, Manfred
2003-01-01
We employ the replica method of statistical physics to study the average case performance of learning systems. The new feature of our theory is that general distributions of data can be treated, which enables applications to real data. For a class of Bayesian prediction models which are based on ...... on Gaussian processes, we discuss Bootstrap estimates for learning curves....
Inferences of Coordinates in Multidimensional Scaling by a Bootstrapping Procedure in R
Kim, Donghoh; Kim, Se-Kang; Park, Soyeon
2015-01-01
Recently, MDS has been utilized to identify and evaluate cognitive ability latent profiles in a population. However, dimension coordinates do not carry any statistical properties. To cope with statistical incompetence of MDS, we investigated the common aspects of various studies utilizing bootstrapping, and provided an R function for its…
Kleibergen, F.
2011-01-01
We construct higher order expressions of (weak instrument robust) generalized method of moment (GMM) test statistics for iid data. We use them to obtain Edgeworth approximations and to reveal sensitivity to instrument quality. The Edgeworth approximations show that usage of bootstrapped critical
Giving the Boot to the Bootstrap: How Not to Learn the Natural Numbers
Rips, Lance J.; Asmuth, Jennifer; Bloomfield, Amber
2006-01-01
According to one theory about how children learn the concept of natural numbers, they first determine that "one", "two", and "three" denote the size of sets containing the relevant number of items. They then make the following inductive inference (the Bootstrap): The next number word in the counting series denotes the size of the sets you get by…
The use of vector bootstrapping to improve variable selection precision in Lasso models.
Laurin, Charles; Boomsma, Dorret; Lubke, Gitta
2016-08-01
The Lasso is a shrinkage regression method that is widely used for variable selection in statistical genetics. Commonly, K-fold cross-validation is used to fit a Lasso model. This is sometimes followed by using bootstrap confidence intervals to improve precision in the resulting variable selections. Nesting cross-validation within bootstrapping could provide further improvements in precision, but this has not been investigated systematically. We performed simulation studies of Lasso variable selection precision (VSP) with and without nesting cross-validation within bootstrapping. Data were simulated to represent genomic data under a polygenic model as well as under a model with effect sizes representative of typical GWAS results. We compared these approaches to each other as well as to software defaults for the Lasso. Nested cross-validation had the most precise variable selection at small effect sizes. At larger effect sizes, there was no advantage to nesting. We illustrated the nested approach with empirical data comprising SNPs and SNP-SNP interactions from the most significant SNPs in a GWAS of borderline personality symptoms. In the empirical example, we found that the default Lasso selected low-reliability SNPs and interactions which were excluded by bootstrapping.
Bootsie: estimation of coefficient of variation of AFLP data by bootstrap analysis
Bootsie is an English-native replacement for ASG Coelho’s “DBOOT” utility for estimating coefficient of variation of a population of AFLP marker data using bootstrapping. Bootsie improves on DBOOT by supporting batch processing, time-to-completion estimation, built-in graphs, and a suite of export t...
National-scale analysis for the identification of High Conservation Value Forests (HCVFs
Directory of Open Access Journals (Sweden)
Maesano M
2011-02-01
Full Text Available In Italy, forests cover about one third of the national territory. In recent years, sustainability has been applied to forest management through the introduction of the Sustainable Forest Management (SFM concept. Since the Rio Conference, several initiatives at international and governmental level aimed to realize the SFM concept by the establishment of a set of principles with general validity. One of the most successful initiatives is the Forest Stewardship Council (FSC, which has developed a system of voluntary certification specific for the forestry sector, as well as 10 principles and 56 criteria for good forest management. The concept of High Conservation Value Forest concept (HCVFs was defined in 1999 by FSC under Principle 9, and its application requires the identification of six categories of High Conservation Values (HCV. The aim of this study was to define the parameters for the HCVFs Italian forests, A first national mapping for the first level of High Conservation Value was developed focusing on protected areas, threatened and endangered species and the ecosystemic temporal use. Protected areas may constitute the basis of the SFM. This work is the result of data processing and distribution analysis through the intersection of vectorial data of national forests areas in ArcMap, on the basis of available information. Protected forest areas represent 34% of the national forest area. The different categories of protected areas contribute differently to protection, in particular the larger amount of preserved forests (22.96% falls within Sites of Community Importance (SCI. The analysis of highly protected forest types revealed major differences likely linked to site ecological conditions, which are extremely variable over the country. The HCVF concept is applied in the forest certification field and can be used in sustainable forest management, planning and land use, and policy commitments.
Competition between trees, a useful tool in forest management aiming at high present value
Energy Technology Data Exchange (ETDEWEB)
Hagner, Mats
1998-12-31
Competition focuses growth resources into few stems that matures early and this is beneficial if forest value is estimated with consideration to interest rate. Hence, competition can replace thinning. As the natural dynamics of our forest tend to increase the size variation this also increases our possibility to use competition as a tool in forest management. From the same reason this harmonic way of using the natural dynamics also reduces costs as the need for maintenance procedures is lessened. As hampering the growth of small trees is a necessity if high quality timber shall be produced, competition from bigger trees can be used to manifold present values Working papers 140. 4 refs, 3 figs
Casault, Sébastien; Groen, Aard J; Linton, Jonathan D
2014-03-25
This paper presents work toward improving the efficacy of financial models that describe the unique nature of biotechnology firms. We show that using a 'thick tailed' power law distribution to describe the behavior of the value of biotechnology R&D used in a Real Options Pricing model is significantly more accurate than the traditionally used Gaussian approach. A study of 287 North-American biotechnology firms gives insights into common problems faced by investors, managers and other stakeholders when using traditional techniques to calculate the commercial value of R&D. This is important because specific quantitative tools to assess the value of high-risk, high-reward R&D do not currently exist. This often leads to an undervaluation of biotechnology R&D and R&D intensive biotechnology firms. For example, the widely used Net Present Value (NPV) method assumes a fixed risk ignoring management flexibility and the changing environment. However, Real Options Pricing models assume that commercial returns from R&D investments are described by a normal random walk. A normal random walk model eliminates the possibility of drastic changes to the marketplace resulting from the introduction of revolutionary products and/or services. It is possible to better understand and manage biotechnology research projects and portfolios using a model that more accurately considers large non-Gaussian price fluctuations with thick tails, which recognize the unusually large risks and opportunities associated with Biotechnology R&D. Our empirical data show that opportunity overcompensates for the downside risk making biotechnology R&D statistically more valuable than other Gaussian options investments, which may otherwise appear to offer a similar combination of risk and return. Copyright © 2013 Elsevier B.V. All rights reserved.
DEFF Research Database (Denmark)
Linnet, Kristian
2005-01-01
Bootstrap, HPLC, limit of blank, limit of detection, non-parametric statistics, type I and II errors......Bootstrap, HPLC, limit of blank, limit of detection, non-parametric statistics, type I and II errors...
Construction Guidelines for High R-Value Walls without Exterior Rigid Insulation
Energy Technology Data Exchange (ETDEWEB)
Arena, Lois B. [Steven Winter Associates, Inc., Norwalk, CT (United States). Consortium for Advanced Residential Buildings
2016-07-13
High-R wall assemblies (R-40 and above) are gaining popularity in the market due to programs like the DOE's Zero Energy Ready Home program, Passive House (PH), Net Zero Energy Home (NZEH) challenges in several states, and highly incentivized retrofit programs. In response to this demand, several builders have successfully used 'double wall' systems to more practically achieve higher R-values in thicker, framed walls. To builders of conventional stick-framed homes, often one of the most appealing features of double wall systems is that there are very few new exterior details. Exterior sheathing, structural bracing, house wrap or building paper, window and door flashing, and siding attachment are usually identical to good details in conventional framed wall systems. The information presented in this guide is intended to reduce the risk of failure in these types of assemblies, increase durability, and result in a reduction of material brought to landfills due to failures and resulting decay. While this document focuses on double wall framing techniques, the majority of the information on how to properly construct and finish high R-value assemblies is applicable to all wall assemblies that do not have foam insulation installed on the exterior of the structural sheathing. The techniques presented have been shown through field studies to reduce the likelihood of mold growth and moisture related damage and are intended for builders, framing contractors, architects, and consultants involved in designing and building super insulated homes.
Evaluating the Value of High Spatial Resolution in National Capacity Expansion Models using ReEDS
Energy Technology Data Exchange (ETDEWEB)
Krishnan, Venkat; Cole, Wesley
2016-07-18
This poster is based on the paper of the same name, presented at the IEEE Power & Energy Society General Meeting, July18, 2016. Power sector capacity expansion models (CEMs) have a broad range of spatial resolutions. This paper uses the Regional Energy Deployment System (ReEDS) model, a long-term national scale electric sector CEM, to evaluate the value of high spatial resolution for CEMs. ReEDS models the United States with 134 load balancing areas (BAs) and captures the variability in existing generation parameters, future technology costs, performance, and resource availability using very high spatial resolution data, especially for wind and solar modeled at 356 resource regions. In this paper we perform planning studies at three different spatial resolutions - native resolution (134 BAs), state-level, and NERC region level - and evaluate how results change under different levels of spatial aggregation in terms of renewable capacity deployment and location, associated transmission builds, and system costs. The results are used to ascertain the value of high geographically resolved models in terms of their impact on relative competitiveness among renewable energy resources.
Mendonça Costa, Mônica Sarolli Silva de; Lucas, Jorge de; Mendonça Costa, Luiz Antonio de; Orrico, Ana Carolina Amorim
2016-02-01
The increasing demand for animal protein has driven significant changes in cattle breeding systems, mainly in feedlots, with the use of young bulls fed on diets richer in concentrate (C) than in forage (F). These changes are likely to affect animal manure, demanding re-evaluation of the biogas production per kg of TS and VS added, as well as of its agronomic value as a biofertilizer, after anaerobic digestion. Here, we determined the biogas production and agronomic value (i.e., the macronutrient concentration in the final biofertilizer) of the manure of young bulls fed on diets with more (80% C+20% F; 'HighC' diet) or less (65% C+35% F; 'LowC' diet) concentrate, evaluating the effects of temperature (25, 35, and 40°C) and the use of an inoculum, during anaerobic digestion. A total of 24 benchtop reactors were used, operating in a semi-continuous system, with a 40-day hydraulic retention time (HRT). The manure from animals given the HighC diet had the greatest potential for biogas production, when digested with the use of an inoculum and at 35 or 40°C (0.6326 and 0.6207m(3)biogas/kg volatile solids, or VS, respectively). We observed the highest levels of the macronutrients N, P, and K in the biofertilizer from the manure of animals given HighC. Our results show that the manure of young bulls achieves its highest potential for biogas production and agronomic value when animals are fed diets richer in concentrate, and that biogas production increases if digestion is performed at higher temperatures, and with the use of an inoculum.
Cotte, Michel
2015-08-01
Practical approach of Dark Sky places as possible WH sites leads some of us to underline the exceptional role of high mountain observatories as “Windows to the Universe” for the Human being. Till today, such places keep very important dark sky properties and consequently important astronomical functions.We have to take count that quality of the sky at a given place and dark sky conservation policy is something very important, but not enough by itself to justify inscription on the WH List. It must be related to important cultural or/and natural value. That means presence of significant heritage features in the field of astronomy and science for listing as WH cultural property, or with other natural attributes of exceptional significance to be listed as WH natural property. Case of both natural and cultural WH high value place is also possible as “mixt WH site”.The Dark Sky place must also meet to a sufficient integrity/authenticity degree for the today tangible heritage of astronomy and to a very significant contribution to the international history of science and astronomy as intangible attribute of the place. That point must be demonstrated by a serious comparative analysis with similar places in the world and in the region. In case of serial nomination as examined there, each individual site must contribute significantly to the Outstanding Universal Value of the global series.First, we intend to give a short account of the today trend for a possible serial nomination of the most significant high mountain observatory keeping important heritage of their major periods for the sky observation (Western Europe, Chile, North America, etc.).Second, communication will present a case study with Pic du Midi in French Pyrenees, coming from the early origin of mountain scientific stations and observatories (end of 19th C) in Europe, with a long, continuous and important astronomical and scientific history till today with active programs of sky and atmosphere
Construction Guidelines for High R-Value Walls without Exterior Rigid Insulation
Energy Technology Data Exchange (ETDEWEB)
Arena, Lois B. [Steven Winter Associates, Inc., Norwalk, CT (United States). Consortium for Advanced Residential Buildings (CARB)
2016-07-13
High R-value wall assemblies (R-40 and above) are gaining popularity in the market due to programs such as the U.S. Department of Energy Zero Energy Ready Home program, Passive House, Net Zero Energy Home challenges in several states, and highly incentivized retrofit programs. In response to this demand, several builders have successfully used double-wall systems to achieve higher R-values in thicker, framed walls. To builders of conventional stick-framed homes, often one of the most appealing features of double-wall systems is that there are very few new exterior details. Exterior sheathings, structural bracings, house wraps or building paper, window and door flashings, and siding attachments are usually identical to good details in conventional framed-wall systems. However, although the details in double-wall systems are very similar to those in conventional stick framing, there is sometimes less room for error. Several studies have confirmed colder temperatures of exterior sheathing in high R-value wall assemblies that do not have exterior rigid foam insulation. These colder temperatures can lead to increased chances for condensation from air exfiltration, and they have the potential to result in moisture-related problems (Straube and Smegal 2009, Arena 2014, Ueno 2015). The information presented in this guide is intended to reduce the risk of failure in these types of assemblies, increase durability, and reduce material brought to landfills due to failures and resulting decay. Although this document focuses on double-wall framing techniques, the majority of the information about how to properly construct and finish high R-value assemblies is applicable to all wall assemblies that do not have foam insulation installed on the exterior of the structural sheathing. The techniques presented have been shown through field studies to reduce the likelihood of mold growth and moisture-related damage and are intended for builders, framing contractors, architects, and
Overview of the JYFLTRAP mass measurements and high-precision -values for weak interaction studies
Indian Academy of Sciences (India)
T Eronen; Jyfltrap
2010-08-01
The JYFLTRAP Penning trap set-up at the University of Jyväskylä, Finland, is a Penning trap facility that has provided high-precision atomic mass values for short-lived nuclides since 2003. Until now, masses of more than 250 short-lived nuclides have been measured. Since JYFLTRAP is coupled to the chemically insensitive IGISOL mass separator, any element can be accessed. So far, a huge mass surface extending from magnesium ( = 12) to lead ( = 82) has been covered.
High order statistics based blind deconvolution of bi-level images with unknown intensity values.
Kim, Jeongtae; Jang, Soohyun
2010-06-07
We propose a novel linear blind deconvolution method for bi-level images. The proposed method seeks an optimal point spread function and two parameters that maximize a high order statistics based objective function. Unlike existing minimum entropy deconvolution and least squares minimization methods, the proposed method requires neither unrealistic assumption that the pixel values of a bi-level image are independently identically distributed samples of a random variable nor tuning of regularization parameters.We demonstrate the effectiveness of the proposed method in simulations and experiments.
High-value products from plants: the challenges of process optimization.
Fischer, Rainer; Vasilev, Nikolay; Twyman, Richard M; Schillberg, Stefan
2015-04-01
Plants can be used to produce a diverse repertoire of complex small-molecule compounds and recombinant proteins that are valuable as industrial and pharmaceutical products. But as we move from proof-of-principle experiments and begin to consider the realistic prospects of commercial production, the focus must shift from the achievement of target molecule production and move towards quality, purity and yield aspects that determine commercial feasibility. This review describes some of the recent advances that have been implemented to improve the development of integrated production processes for high-value molecules expressed in plants, including the introduction of novel procedures to increase the likelihood of regulatory acceptance.
Dexter, Troy A; Kowalewski, Michał
2013-12-01
Quantitative estimates of growth rates can augment ecological and paleontological applications of body-size data. However, in contrast to body-size estimates, assessing growth rates is often time-consuming, expensive, or unattainable. Here we use an indirect approach, a jackknife-corrected parametric bootstrap, for efficient approximation of growth rates using nearest living relatives with known age-size relationships. The estimate is developed by (1) collecting a sample of published growth rates of closely related species, (2) calculating the average growth curve using those published age-size relationships, (3) resampling iteratively these empirically known growth curves to estimate the standard errors and confidence bands around the average growth curve, and (4) applying the resulting estimate of uncertainty to bracket age-size relationships of the species of interest. This approach was applied to three monophyletic families (Donacidae, Mactridae, and Semelidae) of mollusk bivalves, a group characterized by indeterministic shell growth, but widely used in ecological, paleontological, and geochemical research. The resulting indirect estimates were tested against two previously published geochemical studies and, in both cases, yielded highly congruent age estimates. In addition, a case study in applied fisheries was used to illustrate the potential of the proposed approach for augmenting aquaculture management practices. The resulting estimates of growth rates place body size data in a constrained temporal context and confidence intervals associated with resampling estimates allow for assessing the statistical uncertainty around derived temporal ranges. The indirect approach should allow for improved evaluation of diverse research questions, from sustainability of industrial shellfish harvesting to climatic interpretations of stable isotope proxies extracted from fossil skeletons.
Meta-metallic coils and resonators: Methods for high Q-value resonant geometries
Energy Technology Data Exchange (ETDEWEB)
Mett, R. R. [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States); Department of Physics and Chemistry, Milwaukee School of Engineering, Milwaukee, Wisconsin 53202 (United States); Sidabras, J. W.; Hyde, J. S. [Department of Biophysics, Medical College of Wisconsin, Milwaukee, Wisconsin 53226 (United States)
2016-08-15
A novel method of decreasing ohmic losses and increasing Q-value in metallic resonators at high frequencies is presented. The method overcomes the skin-depth limitation of rf current flow cross section. The method uses layers of conductive foil of thickness less than a skin depth and capacitive gaps between layers. The capacitive gaps can substantially equalize the rf current flowing in each layer, resulting in a total cross-sectional dimension for rf current flow many times larger than a skin depth. Analytic theory and finite-element simulations indicate that, for a variety of structures, the Q-value enhancement over a single thick conductor approaches the ratio of total conductor thickness to skin depth if the total number of layers is greater than one-third the square of the ratio of total conductor thickness to skin depth. The layer number requirement is due to counter-currents in each foil layer caused by the surrounding rf magnetic fields. We call structures that exhibit this type of Q-enhancement “meta-metallic.” In addition, end effects due to rf magnetic fields wrapping around the ends of the foils can substantially reduce the Q-value for some classes of structures. Foil structures with Q-values that are substantially influenced by such end effects are discussed as are five classes of structures that are not. We focus particularly on 400 MHz, which is the resonant frequency of protons at 9.4 T. Simulations at 400 MHz are shown with comparison to measurements on fabricated structures. The methods and geometries described here are general for magnetic resonance and can be used at frequencies much higher than 400 MHz.
Meta-metallic coils and resonators: Methods for high Q-value resonant geometries
Mett, R. R.; Sidabras, J. W.; Hyde, J. S.
2016-08-01
A novel method of decreasing ohmic losses and increasing Q-value in metallic resonators at high frequencies is presented. The method overcomes the skin-depth limitation of rf current flow cross section. The method uses layers of conductive foil of thickness less than a skin depth and capacitive gaps between layers. The capacitive gaps can substantially equalize the rf current flowing in each layer, resulting in a total cross-sectional dimension for rf current flow many times larger than a skin depth. Analytic theory and finite-element simulations indicate that, for a variety of structures, the Q-value enhancement over a single thick conductor approaches the ratio of total conductor thickness to skin depth if the total number of layers is greater than one-third the square of the ratio of total conductor thickness to skin depth. The layer number requirement is due to counter-currents in each foil layer caused by the surrounding rf magnetic fields. We call structures that exhibit this type of Q-enhancement "meta-metallic." In addition, end effects due to rf magnetic fields wrapping around the ends of the foils can substantially reduce the Q-value for some classes of structures. Foil structures with Q-values that are substantially influenced by such end effects are discussed as are five classes of structures that are not. We focus particularly on 400 MHz, which is the resonant frequency of protons at 9.4 T. Simulations at 400 MHz are shown with comparison to measurements on fabricated structures. The methods and geometries described here are general for magnetic resonance and can be used at frequencies much higher than 400 MHz.
Using Behavioral Economics to Design Physician Incentives That Deliver High-Value Care.
Emanuel, Ezekiel J; Ubel, Peter A; Kessler, Judd B; Meyer, Gregg; Muller, Ralph W; Navathe, Amol S; Patel, Pankaj; Pearl, Robert; Rosenthal, Meredith B; Sacks, Lee; Sen, Aditi P; Sherman, Paul; Volpp, Kevin G
2016-01-19
Behavioral economics provides insights about the development of effective incentives for physicians to deliver high-value care. It suggests that the structure and delivery of incentives can shape behavior, as can thoughtful design of the decision-making environment. This article discusses several principles of behavioral economics, including inertia, loss aversion, choice overload, and relative social ranking. Whereas these principles have been applied to motivate personal health decisions, retirement planning, and savings behavior, they have been largely ignored in the design of physician incentive programs. Applying these principles to physician incentives can improve their effectiveness through better alignment with performance goals. Anecdotal examples of successful incentive programs that apply behavioral economics principles are provided, even as the authors recognize that its application to the design of physician incentives is largely untested, and many outstanding questions exist. Application and rigorous evaluation of infrastructure changes and incentives are needed to design payment systems that incentivize high-quality, cost-conscious care.
Directory of Open Access Journals (Sweden)
Wang Lei
2012-10-01
Full Text Available Abstract Background Congenital muscular torticollis (CMT is a relatively common neck deformity in infancy. The aim of our research was to determine the value of high-frequency and color Doppler ultrasonography in diagnosing CMT. Methods Patients with a clinical suspicion of CMT underwent an ultrasound examination before diagnosis, and the sonographic characteristics were analyzed and compared with the clinical findings. Results The sensitivity and specificity of an ultrasound diagnosis for CMT was 95.83% and 83.33%, respectively. The patients were divided into 2 groups based on the stage of the disease: the early-stage group (age Conclusions Different stage of CMT patients had different sonographic characteristics. High-frequency and color Doppler ultrasonography can serve as adjunct confirmation tool for the diagnosis of CMT.
Clinical value of high-sensitivity cardiac troponin assays after acute ischemic stroke
Directory of Open Access Journals (Sweden)
Yi-rui CAO
2016-11-01
Full Text Available In view of a variety of cardiovascular events complicated by acute ischemic stroke, the importance of monitoring myocardial ischemic symptoms and signs, electrocardiogram, echocardiogram and myocardial injury markers has been gradually recognized by clinicians. Cardiac troponin (cTn by conventional assay has been a unique marker of myocardial injury for its extremely high specificity. However, with the utilization of high-sensitivity cardiac troponin (hs-cTn, cTn is no longer exclusive of a disease, but was given more significance in the diagnosis and application value. Therefore, we described the clinical significance of alterations of serum hs-cTn concentration after ischemic stroke. DOI: 10.3969/j.issn.1672-6731.2016.11.015
Development of Low-Noise High Value Chromium Silicide Resistors for Cryogenic Detector Applications
Jhabvala, Murzy; Babu, Sachi; Monroy, Carlos; Darren, C.; Krebs, Carolyn A. (Technical Monitor)
2001-01-01
Extremely high sensitivity detectors, such as silicon bolometers are required in many NASA missions for detection of photons from the x-ray to the far infrared regions. Typically, these detectors are cooled to well below the liquid helium (LHe) temperature (4.2 K) to achieve the maximum detection performance. As photoconductors, they are generally operated with a load resistor and a pre-set bias voltage, which is then coupled to the input gate of a source-follower Field Effect Transistor (FET) circuit. It is imperative that the detector system signal to noise performance be limited by the noise of the detector and not by the noise of the external components. The load resistor value is selected to optimize the detector performance. These two criteria tend to be contradictory in that these detectors require load resistors in the hundreds of megaohms, which leads to a higher Johnson noise. Additionally, the physical size of the resistor must be small for device integration as required by such missions as the NASA High Resolution Airborne Wide-Band Camera (HAWC) instrument and the Submillimeter High Angular Resolution Camera (SHARC) for the Caltech Submillimeter Observatory (CSO). We have designed, fabricated and characterized thin film resistors using a CrSi/TiW/Al metal system on optical quality quartz substrates. The resistor values range from 100 megaohms to over 650 megaohms and are Johnson noise limited at LHe temperatures. The resistor film is sputtered with a sheet resistance ranging from 300 ohms to 1600 ohms and the processing sequence developed for these devices allows for chemically fine tuning the sheet resistance in-situ. The wafer fabrication process was of sufficiently high yield (>80%) providing clusters of good resistors for integrated multiple detector channels, a very important feature in the assembly of these two instruments.
Development of aerated confectionery products of high nutritional value using triticale flour
Directory of Open Access Journals (Sweden)
G. O. Magomedov
2016-01-01
Full Text Available Pastries are very popular among the Russian population. Pastry are the most promising targets for the enrichment of their function ingredients.. One of the most promising feedstocks for the production of flour confectionery products is flour from grain crops ofspring triticale. The different varieties of triticale were studied in particular, triticale flour grade "Ukro" for use in technologies of shortbread-butter cookies with enhanced food value. The first in the history of our country varieties of spring triticale "Ukro" was included in the State Register of selection achievements since 2004. Triticale is characterized by high-protein content. Triticale, protein is higher than in wheat by amino acids lysine and tryptophan, minerals (calcium, potassium, magnesium, iron, B vitamins. It was pointed the choice and ratio of prescription ingredients. Recipe shortbread-butter cookies based on the seeded triticale flour and flour from coarse whole meal grain, grade "Ukro", with high consumer properties was developed. Cake samples prepared on the basis of flour triticale exceed the reference sample of prime grade wheat flour. Biscuits have a high content of complete protein, vitamins, macro - and microelements, dietary fibers, high gustatory qualities. The influence of prescription components on organoleptic and physical-chemical properties of sandy butter cookies was studied. The nutritional and biological value was calculated. It was state the daily needs of the organism in these materials when using 100 g. As a result of the conducted studies proved the feasibility of the use of flour from grain triticale in the production of flour confectionery products of functional purpose.
Aluminum recovery as a product with high added value using aluminum hazardous waste
Energy Technology Data Exchange (ETDEWEB)
David, E., E-mail: david@icsi.ro [National Institute for Research and Development for Cryogenic and Isotopic Technologies, Street Uzinei, No. 4, P.O. Râureni, P.O. Box 7, 240050 Rm. Vâlcea (Romania); Kopac, J. [Faculty of Mechanical Engineering, University of Ljubljana, Askerceva 6, SI-1000 Ljubljana (Slovenia)
2013-10-15
Highlights: • Granular and compact aluminum dross were physically and chemically characterized. • A relationship between density, porosity and metal content from dross was established. • Chemical reactions involving aluminum in landfill and negative consequences are shown. • A processing method for aluminum recovering from aluminum dross was developed. • Aluminum was recovered as an value product with high grade purity such as alumina. -- Abstract: The samples of hazardous aluminum solid waste such as dross were physically and chemically characterized. A relationship between density, porosity and metal content of dross was established. The paper also examines the chemical reactions involving aluminum dross in landfill and the negative consequences. To avoid environmental problems and to recovery the aluminum, a processing method was developed and aluminum was recovered as an added value product such as alumina. This method refers to a process at low temperature, in more stages: acid leaching, purification, precipitation and calcination. At the end of this process aluminum was extracted, first as Al{sup 3+} soluble ions and final as alumina product. The composition of the aluminum dross and alumina powder obtained were measured by applying the leaching tests, using atomic absorption spectrometry (AAS) and chemical analysis. The mineralogical composition of aluminum dross samples and alumina product were determined by X-ray diffraction (XRD) and the morphological characterization was performed by scanning electron microscopy (SEM). The method presented in this work allows the use of hazardous aluminum solid waste as raw material to recover an important fraction from soluble aluminum content as an added value product, alumina, with high grade purity (99.28%)
Ghosh, Purabi R.; Fawcett, Derek; Sharma, Shashi B.; Poinern, Gerrard E. J.
2017-01-01
The quantities of organic waste produced globally by aquacultural and horticulture are extremely large and offer an attractive renewable source of biomolecules and bioactive compounds. The availability of such large and diverse sources of waste materials creates a unique opportunity to develop new recycling and food waste utilisation strategies. The aim of this review is to report the current status of research in the emerging field of producing high-value nanoparticles from food waste. Eco-friendly biogenic processes are quite rapid, and are usually carried out at normal room temperature and pressure. These alternative clean technologies do not rely on the use of the toxic chemicals and solvents commonly associated with traditional nanoparticle manufacturing processes. The relatively small number of research articles in the field have been surveyed and evaluated. Among the diversity of waste types, promising candidates and their ability to produce various high-value nanoparticles are discussed. Experimental parameters, nanoparticle characteristics and potential applications for nanoparticles in pharmaceuticals and biomedical applications are discussed. In spite of the advantages, there are a number of challenges, including nanoparticle reproducibility and understanding the formation mechanisms between different food waste products. Thus, there is considerable scope and opportunity for further research in this emerging field. PMID:28773212
Testing the additional predictive value of high-dimensional molecular data
Directory of Open Access Journals (Sweden)
Boulesteix Anne-Laure
2010-02-01
Full Text Available Abstract Background While high-dimensional molecular data such as microarray gene expression data have been used for disease outcome prediction or diagnosis purposes for about ten years in biomedical research, the question of the additional predictive value of such data given that classical predictors are already available has long been under-considered in the bioinformatics literature. Results We suggest an intuitive permutation-based testing procedure for assessing the additional predictive value of high-dimensional molecular data. Our method combines two well-known statistical tools: logistic regression and boosting regression. We give clear advice for the choice of the only method parameter (the number of boosting iterations. In simulations, our novel approach is found to have very good power in different settings, e.g. few strong predictors or many weak predictors. For illustrative purpose, it is applied to the two publicly available cancer data sets. Conclusions Our simple and computationally efficient approach can be used to globally assess the additional predictive power of a large number of candidate predictors given that a few clinical covariates or a known prognostic index are already available. It is implemented in the R package "globalboosttest" which is publicly available from R-forge and will be sent to the CRAN as soon as possible.
Energy Technology Data Exchange (ETDEWEB)
Yu, Chao; Cao, Yujin; Zou, Huibin; Xian, Mo [Chinese Academy of Sciences, Qingdao (China). Key Lab. of Biofuels
2011-02-15
Confronted with the gradual and inescapable exhaustion of the earth's fossil energy resources, the bio-based process to produce platform chemicals from renewable carbohydrates is attracting growing interest. Escherichia coli has been chosen as a workhouse for the production of many valuable chemicals due to its clear genetic background, convenient to be genetically modified and good growth properties with low nutrient requirements. Rational strain development of E. coli achieved by metabolic engineering strategies has provided new processes for efficiently biotechnological production of various high-value chemical building blocks. Compared to previous reviews, this review focuses on recent advances in metabolic engineering of the industrial model bacteria E. coli that lead to efficient recombinant biocatalysts for the production of high-value organic acids like succinic acid, lactic acid, 3-hydroxypropanoic acid and glucaric acid as well as alcohols like 1,3-propanediol, xylitol, mannitol, and glycerol with the discussion of the future research in this area. Besides, this review also discusses several platform chemicals, including fumaric acid, aspartic acid, glutamic acid, sorbitol, itaconic acid, and 2,5-furan dicarboxylic acid, which have not been produced by E. coli until now. (orig.)
High-Value Components and Bioactives from Sea Cucumbers for Functional Foods—A Review
Directory of Open Access Journals (Sweden)
Nazamid Saari
2011-10-01
Full Text Available Sea cucumbers, belonging to the class Holothuroidea, are marine invertebrates, habitually found in the benthic areas and deep seas across the world. They have high commercial value coupled with increasing global production and trade. Sea cucumbers, informally named as bêche-de-mer, or gamat, have long been used for food and folk medicine in the communities of Asia and Middle East. Nutritionally, sea cucumbers have an impressive profile of valuable nutrients such as Vitamin A, Vitamin B1 (thiamine, Vitamin B2 (riboflavin, Vitamin B3 (niacin, and minerals, especially calcium, magnesium, iron and zinc. A number of unique biological and pharmacological activities including anti-angiogenic, anticancer, anticoagulant, anti-hypertension, anti-inflammatory, antimicrobial, antioxidant, antithrombotic, antitumor and wound healing have been ascribed to various species of sea cucumbers. Therapeutic properties and medicinal benefits of sea cucumbers can be linked to the presence of a wide array of bioactives especially triterpene glycosides (saponins, chondroitin sulfates, glycosaminoglycan (GAGs, sulfated polysaccharides, sterols (glycosides and sulfates, phenolics, cerberosides, lectins, peptides, glycoprotein, glycosphingolipids and essential fatty acids. This review is mainly designed to cover the high-value components and bioactives as well as the multiple biological and therapeutic properties of sea cucumbers with regard to exploring their potential uses for functional foods and nutraceuticals.
Yu, Chao; Cao, Yujin; Zou, Huibin; Xian, Mo
2011-02-01
Confronted with the gradual and inescapable exhaustion of the earth's fossil energy resources, the bio-based process to produce platform chemicals from renewable carbohydrates is attracting growing interest. Escherichia coli has been chosen as a workhouse for the production of many valuable chemicals due to its clear genetic background, convenient to be genetically modified and good growth properties with low nutrient requirements. Rational strain development of E. coli achieved by metabolic engineering strategies has provided new processes for efficiently biotechnological production of various high-value chemical building blocks. Compared to previous reviews, this review focuses on recent advances in metabolic engineering of the industrial model bacteria E. coli that lead to efficient recombinant biocatalysts for the production of high-value organic acids like succinic acid, lactic acid, 3-hydroxypropanoic acid and glucaric acid as well as alcohols like 1,3-propanediol, xylitol, mannitol, and glycerol with the discussion of the future research in this area. Besides, this review also discusses several platform chemicals, including fumaric acid, aspartic acid, glutamic acid, sorbitol, itaconic acid, and 2,5-furan dicarboxylic acid, which have not been produced by E. coli until now.
High-value components and bioactives from sea cucumbers for functional foods--a review.
Bordbar, Sara; Anwar, Farooq; Saari, Nazamid
2011-01-01
Sea cucumbers, belonging to the class Holothuroidea, are marine invertebrates, habitually found in the benthic areas and deep seas across the world. They have high commercial value coupled with increasing global production and trade. Sea cucumbers, informally named as bêche-de-mer, or gamat, have long been used for food and folk medicine in the communities of Asia and Middle East. Nutritionally, sea cucumbers have an impressive profile of valuable nutrients such as Vitamin A, Vitamin B1 (thiamine), Vitamin B2 (riboflavin), Vitamin B3 (niacin), and minerals, especially calcium, magnesium, iron and zinc. A number of unique biological and pharmacological activities including anti-angiogenic, anticancer, anticoagulant, anti-hypertension, anti-inflammatory, antimicrobial, antioxidant, antithrombotic, antitumor and wound healing have been ascribed to various species of sea cucumbers. Therapeutic properties and medicinal benefits of sea cucumbers can be linked to the presence of a wide array of bioactives especially triterpene glycosides (saponins), chondroitin sulfates, glycosaminoglycan (GAGs), sulfated polysaccharides, sterols (glycosides and sulfates), phenolics, cerberosides, lectins, peptides, glycoprotein, glycosphingolipids and essential fatty acids. This review is mainly designed to cover the high-value components and bioactives as well as the multiple biological and therapeutic properties of sea cucumbers with regard to exploring their potential uses for functional foods and nutraceuticals.
High-value compounds from microalgae with industrial exploitability - A review.
Bilal, Muhammad; Rasheed, Tahir; Ahmed, Ishtiaq; Iqbal, Hafiz M N
2017-06-01
From the past several years, algal biotechnology has gained noticeable interests among research-based organizations and industrial sectors. Recent studies have provided considerable evidence that microalgae-derived bioactive compounds could play a vital role in bio- and non-bio sectors of the modern world. Microalgae-based industrial exploitability ranges from basic biomass-based food and feeds nutraceuticals to high-value pharmaceuticals, cosmeceuticals, ecological and biomedical applications. With ever increasing scientific knowledge, social and environmental awareness, bio-inspired synthesis of microalgae-based green products, and recent advancements in algal biotechnology will extend the utilization of microalgae into new areas. Microalgae offer high biodiversity with an enormous potential to produce structurally complex yet bioactive compounds which are either impossible or difficult to produce via synthetic routes. In this paper, a range of value-added bioactive compounds from microalgae with industrial potentialities has been reviewed. The contribution ended with a critical description of the main research gaps and envisioned with future considerations to progress further in this exciting era of research.
Gioe, Terence J; Sharma, Amit; Tatman, Penny; Mehle, Susan
2011-01-01
Numerous joint implant options of varying cost are available to the surgeon, but it is unclear whether more costly implants add value in terms of function or longevity. We evaluated registry survival of higher-cost "premium" knee and hip components compared to lower-priced standard components. Premium TKA components were defined as mobile-bearing designs, high-flexion designs, oxidized-zirconium designs, those including moderately crosslinked polyethylene inserts, or some combination. Premium THAs included ceramic-on-ceramic, metal-on-metal, and ceramic-on-highly crosslinked polyethylene designs. We compared 3462 standard TKAs to 2806 premium TKAs and 868 standard THAs to 1311 premium THAs using standard statistical methods. The cost of the premium implants was on average approximately $1000 higher than the standard implants. There was no difference in the cumulative revision rate at 7-8 years between premium and standard TKAs or THAs. In this time frame, premium implants did not demonstrate better survival than standard implants. Revision indications for TKA did not differ, and infection and instability remained contributors. Longer followup is necessary to demonstrate whether premium implants add value in younger patient groups. Level III, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.
PDF added value of a high resolution climate simulation for precipitation
Soares, Pedro M. M.; Cardoso, Rita M.
2015-04-01
dynamical downscaling, based on simple PDF skill scores. The measure can assess the full quality of the PDFs and at the same time integrates a flexible manner to weight differently the PDF tails. In this study we apply the referred method to characaterize the PDF added value of a high resolution simulation with the WRF model. Results from a WRF climate simulation centred at the Iberian Penisnula with two nested grids, a larger one at 27km and a smaller one at 9km. This simulation is forced by ERA-Interim. The observational data used covers from rain gauges precipitation records to observational regular grids of daily precipitation. Two regular gridded precipitation datasets are used. A Portuguese grid precipitation dataset developed at 0.2°× 0.2°, from observed rain gauges daily precipitation. A second one corresponding to the ENSEMBLES observational gridded dataset for Europe, which includes daily precipitation values at 0.25°. The analisys shows an important PDF added value from the higher resolution simulation, regarding the full PDF and the extremes. This method shows higher potential to be applied to other simulation exercises and to evaluate other variables.
High value added lipids produced by microorganisms: a potential use of sugarcane vinasse.
Fernandes, Bruna Soares; Vieira, João Paulo Fernandes; Contesini, Fabiano Jares; Mantelatto, Paulo Eduardo; Zaiat, Marcelo; Pradella, José Geraldo da Cruz
2017-12-01
This review aims to present an innovative concept of high value added lipids produced by heterotrophic microorganisms, bacteria and fungi, using carbon sources, such as sugars, acids and alcohols that could come from sugarcane vinasse, which is the main byproduct from ethanol production that is released in the distillation step. Vinasse is a rich carbon source and low-cost feedstock produced in large amounts from ethanol production. In 2019, the Brazilian Ministry of Agriculture, Livestock and Food Supply estimates that growth of ethanol domestic consumption will be 58.8 billion liters, more than double the amount in 2008. This represents the annual production of more than 588 billion liters of vinasse, which is currently used as a fertilizer in the sugarcane crop, due to its high concentration of minerals, mainly potassium. However, studies indicate some disadvantages such as the generation of Greenhouse Gas emission during vinasse distribution in the crop, as well as the possibility of contaminating the groundwater and soil. Therefore, the development of programs for sustainable use of vinasse is a priority. One profitable alternative is the fermentation of vinasse, followed by an anaerobic digester, in order to obtain biomaterials such as lipids, other byproducts, and methane. Promising high value added lipids, for instance carotenoids and polyunsaturated fatty acids (PUFAS), with a predicted market of millions of US$, could be produced using vinasse as carbon source, to guide an innovative concept for sustainable production. Example of lipids obtained from the fermentation of compounds present in vinasse are vitamin D, which comes from yeast sucrose fermentation and Omega 3, which can be obtained by bacteria and fungi fermentation. Additionally, several other compounds present in vinasse can be used for this purpose, including sucrose, ethanol, lactate, pyruvate, acetate and other carbon sources. Finally, this paper illustrates the potential market and
Tian, Dong; Hu, Jinguang; Bao, Jie; Chandra, Richard P; Saddler, Jack N; Lu, Canhui
2017-01-01
Although conversion of low value but high-volume lignin by-product to its usable form is one of the determinant factors for building an economically feasible integrated lignocellulose biorefinery, it has been challenged by its structural complexity and inhomogeneity. We and others have shown that uniform lignin nanoparticles can be produced from a wide range of technical lignins, despite the varied lignocellulosic biomass and the pretreatment methods/conditions applied. This value-added nanostructure lignin enriched with multifunctional groups can be a promising versatile material platform for various downstream utilizations especially in the emerging nanocomposite fields. Inspired by the story of successful production and application of nanocellulose biopolymer, two types of uniform lignin nanoparticles (LNPs) were prepared through self-assembling of deep eutectic solvent (DES) and ethanol-organosolv extracted technical lignins derived from a two-stage fractionation pretreatment approach, respectively. Both LPNs exhibited sphere morphology with unique core-shell nanostructure, where the DES-LNPs showed a more uniform particle size distribution. When incorporated into the traditional polymeric matrix such as poly(vinyl alcohol), these LPN products displayed great potential to formulate a transparent nanocomposite film with additional UV-shielding efficacy (reached ~80% at 400 nm with 4 wt% of LNPs) and antioxidant functionalities (reached ~160 μm mol Trolox g(-1) with 4 wt% of LNPs). At the same time, the abundant phenolic hydroxyl groups on the shell of LNPs also provided good interfacial adhesion with PVA matrix through the formation of hydrogen bonding network, which further improved the mechanical and thermal performances of the fabricated LNPs/PVA nanocomposite films. Both LNPs are excellent candidates for producing multifunctional polymer nanocomposites using facile technical route. The prepared transparent and flexible LNPs/PVA composite films with
Loop equations and bootstrap methods in the lattice
Directory of Open Access Journals (Sweden)
Peter D. Anderson
2017-08-01
Full Text Available Pure gauge theories can be formulated in terms of Wilson Loops by means of the loop equation. In the large-N limit this equation closes in the expectation value of single loops. In particular, using the lattice as a regulator, it becomes a well defined equation for a discrete set of loops. In this paper we study different numerical approaches to solving this equation. Previous ideas gave good results in the strong coupling region. Here we propose an alternative method based on the observation that certain matrices ρˆ of Wilson loop expectation values are positive definite. They also have unit trace (ρˆ⪰0,Trρˆ=1, in fact they can be defined as reduced density matrices in the space of open loops after tracing over color indices and can be used to define an entropy associated with the loss of information due to such trace SWL=−Tr[ρˆlnρˆ]. The condition that such matrices are positive definite allows us to study the weak coupling region which is relevant for the continuum limit. In the exactly solvable case of two dimensions this approach gives very good results by considering just a few loops. In four dimensions it gives good results in the weak coupling region and therefore is complementary to the strong coupling expansion. We compare the results with standard Monte Carlo simulations.
Zero-tolerance biosecurity protects high-conservation-value island nature reserve.
Scott, John K; McKirdy, Simon J; van der Merwe, Johann; Green, Roy; Burbidge, Andrew A; Pickles, Greg; Hardie, Darryl C; Morris, Keith; Kendrick, Peter G; Thomas, Melissa L; Horton, Kristin L; O'Connor, Simon M; Downs, Justin; Stoklosa, Richard; Lagdon, Russell; Marks, Barbara; Nairn, Malcolm; Mengersen, Kerrie
2017-04-10
Barrow Island, north-west coast of Australia, is one of the world's significant conservation areas, harboring marsupials that have become extinct or threatened on mainland Australia as well as a rich diversity of plants and animals, some endemic. Access to construct a Liquefied Natural Gas (LNG) plant, Australia's largest infrastructure development, on the island was conditional on no non-indigenous species (NIS) becoming established. We developed a comprehensive biosecurity system to protect the island's biodiversity. From 2009 to 2015 more than 0.5 million passengers and 12.2 million tonnes of freight were transported to the island under the biosecurity system, requiring 1.5 million hrs of inspections. No establishments of NIS were detected. We made four observations that will assist development of biosecurity systems. Firstly, the frequency of detections of organisms corresponded best to a mixture log-normal distribution including the high number of zero inspections and extreme values involving rare incursions. Secondly, comprehensive knowledge of the island's biota allowed estimation of false positive detections (62% native species). Thirdly, detections at the border did not predict incursions on the island. Fourthly, the workforce detected more than half post-border incursions (59%). Similar approaches can and should be implemented for all areas of significant conservation value.
HIGH NATURE VALUE GRASSLANDS FROM ARRHENATHERION ALLIANCE IDENTIFIED IN MUREŞ COUNTY
Directory of Open Access Journals (Sweden)
Silvia Oroian
2016-11-01
Full Text Available Arrhenatherion alliance meadows are recognized to be among the best pastures in our country due to high productivity and good nutrition value. The research was conducted in several areas of Mures County. The studied grasslands were classified into two types of Natura 2000 habitats: 6510 Lowland hay meadows (Alopecurus pratensis, Sanguisorba officinalis and 6520 Mountain hay meadows. The identified phytocoenosis belong to two plant associations: Arrhenatheretum elatioris Br.-Bl. Ex Scherrer 1925 and Poo Trisetetum flavescentis (Knapp 1951 Oberd. 1957. The analysis of data collected in the field reveals that the current state of conservation of the two types of habitat is good and very good. Habitats in a good and very good state of preservation is distinguish by a great floristic composition: approx. 100-150 cormophyte species with good and very good forage value. As habitats are more susceptible to the management applied and any changes to land use can affect habitat quality (eg abandoning mowing and turning the land into pasture, the ecological functions of this habitat will be satisfied as long as they are mowed after Poaceae species matured.
Liguori, Rossana; Ventorino, Valeria; Pepe, Olimpia; Faraco, Vincenza
2016-01-01
Lignocellulosic biomasses derived from dedicated crops and agro-industrial residual materials are promising renewable resources for the production of fuels and other added value bioproducts. Due to the tolerance to a wide range of environments, the dedicated crops can be cultivated on marginal lands, avoiding conflict with food production and having beneficial effects on the environment. Besides, the agro-industrial residual materials represent an abundant, available, and cheap source of bioproducts that completely cut out the economical and environmental issues related to the cultivation of energy crops. Different processing steps like pretreatment, hydrolysis and microbial fermentation are needed to convert biomass into added value bioproducts. The reactor configuration, the operative conditions, and the operation mode of the conversion processes are crucial parameters for a high yield and productivity of the biomass bioconversion process. This review summarizes the last progresses in the bioreactor field, with main attention on the new configurations and the agitation systems, for conversion of dedicated energy crops (Arundo donax) and residual materials (corn stover, wheat straw, mesquite wood, agave bagasse, fruit and citrus peel wastes, sunflower seed hull, switchgrass, poplar sawdust, cogon grass, sugarcane bagasse, sunflower seed hull, and poplar wood) into sugars and ethanol. The main novelty of this review is its focus on reactor components and properties.
Assessing Landscape Scale Wildfire Exposure for Highly Valued Resources in a Mediterranean Area
Alcasena, Fermín J.; Salis, Michele; Ager, Alan A.; Arca, Bachisio; Molina, Domingo; Spano, Donatella
2015-05-01
We used a fire simulation modeling approach to assess landscape scale wildfire exposure for highly valued resources and assets (HVR) on a fire-prone area of 680 km2 located in central Sardinia, Italy. The study area was affected by several wildfires in the last half century: some large and intense fire events threatened wildland urban interfaces as well as other socioeconomic and cultural values. Historical wildfire and weather data were used to inform wildfire simulations, which were based on the minimum travel time algorithm as implemented in FlamMap. We simulated 90,000 fires that replicated recent large fire events in the area spreading under severe weather conditions to generate detailed maps of wildfire likelihood and intensity. Then, we linked fire modeling outputs to a geospatial risk assessment framework focusing on buffer areas around HVR. The results highlighted a large variation in burn probability and fire intensity in the vicinity of HVRs, and allowed us to identify the areas most exposed to wildfires and thus to a higher potential damage. Fire intensity in the HVR buffers was mainly related to fuel types, while wind direction, topographic features, and historically based ignition pattern were the key factors affecting fire likelihood. The methodology presented in this work can have numerous applications, in the study area and elsewhere, particularly to address and inform fire risk management, landscape planning and people safety on the vicinity of HVRs.
Aluminum recovery as a product with high added value using aluminum hazardous waste.
David, E; Kopac, J
2013-10-15
The samples of hazardous aluminum solid waste such as dross were physically and chemically characterized. A relationship between density, porosity and metal content of dross was established. The paper also examines the chemical reactions involving aluminum dross in landfill and the negative consequences. To avoid environmental problems and to recovery the aluminum, a processing method was developed and aluminum was recovered as an added value product such as alumina. This method refers to a process at low temperature, in more stages: acid leaching, purification, precipitation and calcination. At the end of this process aluminum was extracted, first as Al(3+) soluble ions and final as alumina product. The composition of the aluminum dross and alumina powder obtained were measured by applying the leaching tests, using atomic absorption spectrometry (AAS) and chemical analysis. The mineralogical composition of aluminum dross samples and alumina product were determined by X-ray diffraction (XRD) and the morphological characterization was performed by scanning electron microscopy (SEM). The method presented in this work allows the use of hazardous aluminum solid waste as raw material to recover an important fraction from soluble aluminum content as an added value product, alumina, with high grade purity (99.28%). Copyright © 2013 Elsevier B.V. All rights reserved.
Accelerated maturation of white matter in young children with autism: a high b value DWI study.
Ben Bashat, Dafna; Kronfeld-Duenias, Vered; Zachor, Ditza A; Ekstein, Perla M; Hendler, Talma; Tarrasch, Ricardo; Even, Ariela; Levy, Yonata; Ben Sira, Liat
2007-08-01
The goal of this work was to study white matter maturation in young children with autism following previous reports of increased cerebral volume during early development, as well as arguments for abnormal neural growth patterns and regulation at this critical developmental period. We applied diffusion tensor imaging (DTI) and high b value diffusion-weighted imaging (DWI) to young children diagnosed with autism and to a typically developing (TD) control group. Fractional anisotropy (FA), probability and displacement were measured in overall analysis as well as in regions of interest (ROI). Individual data points of children with autism were compared to the developmental curves obtained from typically developing children. Increased restriction, reflected in significantly increased FA and probability along with reduced displacement values, was detected in overall analysis as well as in several brain regions. Increased restriction, suggesting an early and accelerated abnormal maturation of white matter, was more dominant in the left hemisphere and was mainly detected in the frontal lobe. No changes were detected in the occipital lobes. These results support previous claims of abnormal brain overgrowth in young children with autism and are in contrast to the decreased restricted diffusion reported in previous studies in adolescent with autism.
Blood pressure values and depression in hypertensive individuals at high cardiovascular risk.
Mejia-Lancheros, Cilia; Estruch, Ramón; Martínez-González, Miguel Angel; Salas-Salvadó, Jordi; Corella, Dolores; Gómez-Gracia, Enrique; Fiol, Miquel; Santos, José Manuel; Fitó, Montse; Arós, Fernando; Serra-Majem, Lluis; Pintó, Xavier; Basora, Josep; Sorlí, José Vicente; Muñoz, Miguel-Angel
2014-08-26
Hypertension and depression are both important risk factors for cardiovascular diseases. Nevertheless, the association of blood pressure on and depression has not been completely established. This study aims to analyze whether depression may influence the control of blood pressure in hypertensive individuals at high cardiovascular risk. Cross-sectional study, embedded within the PREDIMED clinical trial, of 5954 hypertensive patients with high cardiovascular risk factor profiles. The relationship between blood pressure control and depression was analyzed. A multivariate analysis (logistic and log-linear regression), adjusting for potential confounders (socio-demographic factors, body mass index, lifestyle, diabetes, dyslipidemia, and antihypertensive treatment), was performed. Depressive patients, with and without antidepressant treatment, had better blood pressure control (OR: 1.28, CI 95%: 1.06-1.55, and OR: 1.30, CI 95%: 1.03-1.65, respectively) than non-depressive ones. Regarding blood pressure levels, systolic blood pressure values (mmHg) were found to be lower in both treated and untreated depressive patients (Log coefficient Beta: -1.59, 95% CI: -0.50 to -2.69 and Log coefficient Beta: -3.49, 95% CI: -2.10 to -4.87, respectively). Among hypertensive patients at high cardiovascular risk, the control of blood pressure was better in those diagnosed with depression. Unique identifier: ISRCTN35739639.
High added-value products from the hydrothermal carbonisation of olive stones.
Borrero-López, A M; Fierro, V; Jeder, A; Ouederni, A; Masson, E; Celzard, A
2016-11-21
Olive stones (OS) were submitted to hydrothermal carbonisation (HTC) in order to evaluate the possibility of producing high added-value products, mainly furfural (FU) and 5-hydroxymethylfurfural (5-HMF) on one hand and hydrochars and carbons on the other hand. Temperature (160-240 °C), residence time (1-8 h), initial pH (1-5.5) and liquid/solid ratio (4-48 w/w) were systematically varied in order to study the main products and to optimise FU production. FU production yield up to 19.9 %, based on the hemicellulose content, was obtained. Other minor, but valuable, compounds such as 5-methylfurfural (5-MF) and some phenolic compounds were also produced. The hydrochar was carbonised at 900 °C, and the resultant carbon material was highly ultramicroporous with a peak of pore size distribution centred on 0.5 nm and a surface area as high as 1065 m(2) g(-1), typical of most carbon molecular sieves.
Refining Our Understanding of Value-Based Insurance Design and High Cost Sharing on Children.
Ellis, Randall P; Bachman, Sara S; Tan, Hui Ren
2017-05-01
There is significant concern about the financial burdens of new insurance plan designs on families, particularly families with children and youth with special health care needs (CYSHCN). With value-based insurance design (VBID) plans growing in popularity, this study examined the implications of selected VBID cost-sharing features on children. We studied children's health care spending patterns in 2 data sets that include high deductible and narrow network plans among others. Medical Expenditure Panel Survey data from 2007 to 2013 on 22 392 children were used to study out-of-pocket (OOP) costs according to CYSHCN, family income, and spending. MarketScan large employer insurance claims data from 2007 to 2014 (N = 4 263 452) were used to test for differences in mean total payments and OOP costs across various health plans. Across the data sets, we found that existing health plans place significant financial burdens on families, particularly lower income households and families with CYSHCN; individuals among the top 10% of OOP spending averaged more than $2000 per child. Although high deductible and consumer-driven plans impose substantial OOP costs on children, they do not significantly reduce spending, whereas health maintenance organizations that use network restrictions and tighter management do. Our results do not support the conclusion that high cost-sharing features that are common in VBID plans will significantly reduce health care spending on children. Copyright © 2017 by the American Academy of Pediatrics.
Diagnostic value of thrombocytosis and high CA 125 level in women with adnexal masses.
Atacag, T
2012-01-01
The aim of this study was to determine the diagnostic value of thrombocytosis and high CA 125 levels in women with benign and malign adnexal masses. Thrombocytosis (platelet counts > 400 x 10(9)/l) has been identified as a poor prognostic factor in many cancers including certain gynecologic malignant tumors such as endometrial, cervical, and ovarian cancers. Medical charts of 180 patients with adnexal masses were retrospectively reviewed and analyzed for the association of preoperative thrombocytosis and high CA 125 level with other clinical prognostic factors. Of the 180 participants, 68 (68% of malignant adnexal masses) had thrombocytosis and 74 patients (74% of malignant adnexal masses) had elevated CA 125 levels. The patients with preoperative thrombocytosis were found to have greater elevations of CA 125 levels, more advanced stage disease, and higher grade tumors. Presence of thrombocytosis and high CA 125 alone and in combination may be used as a prognostic factor in the management of women with adnexal masses since they are already used as clinical tests for several purposes.
Cuellar-Bermudez, Sara P; Aguilar-Hernandez, Iris; Cardenas-Chavez, Diana L; Ornelas-Soto, Nancy; Romero-Ogawa, Miguel A; Parra-Saldivar, Roberto
2015-03-01
The marked trend and consumers growing interest in natural and healthy products have forced researches and industry to develop novel products with functional ingredients. Microalgae have been recognized as source of functional ingredients with positive health effects since these microorganisms produce polyunsaturated fatty acids, polysaccharides, natural pigments, essential minerals, vitamins, enzymes and bioactive peptides. For this reason, the manuscript reviews two of the main high-value metabolites which can be obtained from microalgae: pigments and essential lipids. Therefore, the extraction and purification methods for polyunsaturated fatty acids, astaxanthin, phycoerythrin and phycocyanin are described. Also, the effect that environmental growth conditions have in the production of these metabolites is described. This review summarizes the existing methods to extract and purify such metabolites in order to develop a feasible and sustainable algae industry.
Cuellar-Bermudez, Sara P; Aguilar-Hernandez, Iris; Cardenas-Chavez, Diana L; Ornelas-Soto, Nancy; Romero-Ogawa, Miguel A; Parra-Saldivar, Roberto
2015-01-01
The marked trend and consumers growing interest in natural and healthy products have forced researches and industry to develop novel products with functional ingredients. Microalgae have been recognized as source of functional ingredients with positive health effects since these microorganisms produce polyunsaturated fatty acids, polysaccharides, natural pigments, essential minerals, vitamins, enzymes and bioactive peptides. For this reason, the manuscript reviews two of the main high-value metabolites which can be obtained from microalgae: pigments and essential lipids. Therefore, the extraction and purification methods for polyunsaturated fatty acids, astaxanthin, phycoerythrin and phycocyanin are described. Also, the effect that environmental growth conditions have in the production of these metabolites is described. This review summarizes the existing methods to extract and purify such metabolites in order to develop a feasible and sustainable algae industry. PMID:25223877
A commitment to high-value care education from the internal medicine community.
Smith, Cynthia D; Levinson, Wendy S
2015-05-05
The Alliance for Academic Internal Medicine, American Board of Internal Medicine (ABIM), ABIM Foundation, and American College of Physicians are collaborating to enhance the education of physicians in high-value care (HVC) and make its practice an essential competency in undergraduate and postgraduate education by 2017. This article serves as the organizations' formal commitment to providing a foundation of HVC education on which others may build. The 5 key targets for HVC education are experiential learning and curriculum, environment and culture, clinical support, regulatory requirements, and sustainability. The goal is to train future health care professionals for whom HVC is part of normal practice, thus providing patients with improved clinical outcomes at a lower cost.
Penicillium roqueforti: a multifunctional cell factory of high value-added molecules.
Mioso, R; Toledo Marante, F J; Herrera Bravo de Laguna, I
2015-04-01
This is a comprehensive review, with 114 references, of the chemical diversity found in the fungus Penicillium roqueforti. Secondary metabolites of an alkaloidal nature are described, for example, ergot alkaloids such as festuclavine, isofumigaclavines A and B, and diketopiperazine alkaloids such as roquefortines A-D, which are derived from imidazole. Other metabolites are marcfortines A-C, PR-toxin, eremofortines A-E, mycophenolic and penicillic acids, and some γ-lactones. Also, recent developments related to the structural characteristics of botryodiplodin and andrastin are studied-the latter has anticancer properties. Finally, we discuss the enzymes of P. roqueforti, which can participate in the biotechnological production of high value-added molecules, as well as the use of secondary metabolite profiles for taxonomic purposes.
Resilience-Based Perspectives to Guiding High-Nature-Value Farmland through Socioeconomic Change
Directory of Open Access Journals (Sweden)
Tobias Plieninger
2013-12-01
Full Text Available Global environmental challenges require approaches that integrate biodiversity conservation, food production, and livelihoods at landscape scales. We reviewed the approach of conserving biodiversity on "high-nature-value" (HNV farmland, covering 75 million ha in Europe, from a resilience perspective. Despite growing recognition in natural resource policies, many HNV farmlands have vanished, and the remaining ones are vulnerable to socioeconomic changes. Using landscape-level cases across Europe, we considered the following social-ecological system properties and components and their integration into HNV farmland management: (1 coupling of social and ecological systems, (2 key variables, (3 adaptive cycles, (4 regime shifts, (5 cascading effects, (6 ecosystem stewardship and collaboration, (7 social capital, and (8 traditional ecological knowledge. We argue that previous conservation efforts for HNV farmland have focused too much on static, isolated, and monosectoral conservation strategies, and that stimulation of resilience and adaptation is essential for guiding HNV farmland through rapid change.
Opportunity for high value-added chemicals from food supply chain wastes.
Matharu, Avtar S; de Melo, Eduardo M; Houghton, Joseph A
2016-09-01
With approximately 1.3 billion tonnes of food wasted per annum, food supply chain wastes (FSCWs) may be viewed as the contemporary Periodic Table of biobased feedstock chemicals (platform molecules) and functional materials. Herein, the global drivers and case for food waste valorisation within the context of global sustainability, sustainable development goals and the bioeconomy are discussed. The emerging potential of high value added chemicals from certain tropical FSCW is considered as these are grown in three major geographical areas: Brazil, India and China, and likely to increase in volume. FSCW in the context of biorefineries is discussed and two case studies are reported, namely: waste potato, and; orange peel waste. Interestingly, both waste feedstocks, like many others, produce proteins and with the global demand for vegetable proteins on the rise then proteins from FSCW may become a dominant area. Copyright © 2016 Elsevier Ltd. All rights reserved.
Dynamic & Attribute Weighted KNN for Document Classification Using Bootstrap Sampling
Directory of Open Access Journals (Sweden)
Dharmendra S Panwar,
2014-11-01
Full Text Available Although publicly accessible databases containing speech documents. It requires a great deal of time and effort required to keep them up to date is often burdensome. In an effort to help identify speaker of speech if text is available, text-mining tools, from the machine learning discipline, it can be applied to help in this process also. Here, we describe and evaluate document classification algorithms i.e. a combo pack of text mining and classification. This task asked participants to design classifiers for identifying documents containing speech related information in the main literature, and evaluated them against one another. Expected systems utilizes a novel approach of k -nearest neighbour classification and compare its performance by taking different values of k.
Bootstrapping Domain Knowledge Exploration using Conceptual Mapping of Wikipedia
Directory of Open Access Journals (Sweden)
Mai Eldefrawi
2013-09-01
Full Text Available Wikipedia is one of the largest online encyclopedias that exist in a hypertext form. This nature prevents Wikipedia’s potential to be fully discovered. Therefore the focus of this paper is on the role of domain knowledge in supporting the exploration of classical encyclopedic content, which in this case is Wikipedia. A main contribution provided by the author of this work is a methodology for identifying the nature, the form and the role of domain knowledge expressed in conceptual form. It’s also a method of representation and analysis for describing the domain knowledge and for the extraction of the logical representation of a raw form of the domain knowledge. Such logical representation is of limited value in describing the real nature of domain knowledge. Hence we transform it into an adequate graphical representation, mostly of an arc-node form which is called conceptual representation.
SU(2)CMB at high redshifts and the value of H0
Hahn, Steffen; Hofmann, Ralf
2017-07-01
We investigate a high-z cosmological model to compute the comoving sound horizon rs at baryon-velocity freeze-out towards the end of hydrogen recombination. This model assumes a replacement of the conventional cosmic microwave background (CMB) photon gas by deconfining SU(2) Yang-Mills thermodynamics, three flavours of massless neutrinos (Nν = 3) and a purely baryonic matter sector [no cold dark-matter (CDM)]. The according SU(2) temperature-redshift relation of the CMB is contrasted with recent measurements appealing to the thermal Sunyaev-Zel'dovich effect and CMB-photon absorption by molecular rotation bands or atomic hyperfine levels. Relying on a realistic simulation of the ionization history throughout recombination, we obtain z* = 1693.55 ± 6.98 and zdrag = 1812.66 ± 7.01. Due to considerable widths of the visibility functions in the solutions to the associated Boltzmann hierarchy and Euler equation, we conclude that z* and zdrag overestimate the redshifts for the respective photon and baryon-velocity freeze-out. Realistic decoupling values turn out to be zlf,* = 1554.89 ± 5.18 and zlf, drag = 1659.30 ± 5.48. With rs(zlf, drag) = (137.19 ± 0.45) Mpc and the essentially model independent extraction of rsH0 = constant from low-z data in Bernal, Verde & Riess, we obtain a good match with the value H0 = (73.24 ± 1.74) km s-1 Mpc-1 extracted in Riess et al. by appealing to Cepheid-calibrated Type Ia supernovae, new parallax measurements, stronger constraints on the Hubble flow and a refined computation of distance to NGC 4258 from maser data. We briefly comment on a possible interpolation of our high-z model, invoking percolated and unpercolated U(1) topological solitons of a Planck-scale axion field, to the phenomenologically successful low-z ΛCDM cosmology.
Bootstrap-based confidence estimation in PCA and multivariate statistical process control
DEFF Research Database (Denmark)
Babamoradi, Hamid
Traditional/Asymptotic confidence estimation has limited applicability since it needs statistical theories to estimate the confidences, which are not available for all indicators/parameters. Furthermore, in case the theories are available for a specific indicator/parameter, the theories are based...... on assumptions that do not always hold in practice. The aim of this thesis was to illustrate the concept of bootstrap-based confidence estimation in PCA and MSPC. It particularly shows how to build bootstrapbased confidence limits in these areas to be used as alternative to the traditional/asymptotic limits....... The goal was to improve process monitoring by improving the quality of MSPC charts and contribution plots. Bootstrapping algorithm to build confidence limits was illustrated in a case study format (Paper I). The main steps in the algorithm were discussed where a set of sensible choices (plus...
Carving out the end of the world or (superconformal bootstrap in six dimensions)
Chang, Chi-Ming; Lin, Ying-Hsuan
2017-08-01
We bootstrap N=(1,0) superconformal field theories in six dimensions, by analyzing the four-point function of flavor current multiplets. Assuming E 8 flavor group, we present universal bounds on the central charge C T and the flavor central charge C J . Based on the numerical data, we conjecture that the rank-one E-string theory saturates the universal lower bound on C J , and numerically determine the spectrum of long multiplets in the rank-one E-string theory. We comment on the possibility of solving the higher-rank E-string theories by bootstrap and thereby probing M-theory on {AdS}_7× {S}^4/{\\mathrmZ}_2.
Langel, Steven E.; Khanafseh, Samer M.; Pervan, Boris
2016-06-01
Differential carrier phase applications that utilize cycle resolution need the probability density function of the baseline estimate to quantify its region of concentration. For the integer bootstrap estimator, the density function has an analytical definition that enables probability calculations given perfect statistical knowledge of measurement and process noise. This paper derives a method to upper bound the tail probability of the integer bootstrapped GNSS baseline when the measurement and process noise correlation functions are unknown, but can be upper and lower bounded. The tail probability is shown to be a non-convex function of a vector of conditional variances, whose feasible region is a convex polytope. We show how to solve the non-convex optimization problem globally by discretizing the polytope into small hyper-rectangular elements, and demonstrate the method for a static baseline estimation problem.
Langel, Steven E.; Khanafseh, Samer M.; Pervan, Boris
2016-11-01
Differential carrier phase applications that utilize cycle resolution need the probability density function of the baseline estimate to quantify its region of concentration. For the integer bootstrap estimator, the density function has an analytical definition that enables probability calculations given perfect statistical knowledge of measurement and process noise. This paper derives a method to upper bound the tail probability of the integer bootstrapped GNSS baseline when the measurement and process noise correlation functions are unknown, but can be upper and lower bounded. The tail probability is shown to be a non-convex function of a vector of conditional variances, whose feasible region is a convex polytope. We show how to solve the non-convex optimization problem globally by discretizing the polytope into small hyper-rectangular elements, and demonstrate the method for a static baseline estimation problem.
Inference on rare errors using asymptotic expansions and bootstrap calibration
Helmers, R.
1998-01-01
The number of items in error in an audit population is usually quite small, whereas the error distribution is typically highly skewed to the right. For applications in statistical auditing, where line item sampling is appropriate, a new upper confidence limit for the total error amount in an audit p
Technical and scale efficiency in public and private Irish nursing homes - a bootstrap DEA approach.
Ni Luasa, Shiovan; Dineen, Declan; Zieba, Marta
2016-10-27
This article provides methodological and empirical insights into the estimation of technical efficiency in the nursing home sector. Focusing on long-stay care and using primary data, we examine technical and scale efficiency in 39 public and 73 private Irish nursing homes by applying an input-oriented data envelopment analysis (DEA). We employ robust bootstrap methods to validate our nonparametric DEA scores and to integrate the effects of potential determinants in estimating the efficiencies. Both the homogenous and two-stage double bootstrap procedures are used to obtain confidence intervals for the bias-corrected DEA scores. Importantly, the application of the double bootstrap approach affords true DEA technical efficiency scores after adjusting for the effects of ownership, size, case-mix, and other determinants such as location, and quality. Based on our DEA results for variable returns to scale technology, the average technical efficiency score is 62 %, and the mean scale efficiency is 88 %, with nearly all units operating on the increasing returns to scale part of the production frontier. Moreover, based on the double bootstrap results, Irish nursing homes are less technically efficient, and more scale efficient than the conventional DEA estimates suggest. Regarding the efficiency determinants, in terms of ownership, we find that private facilities are less efficient than the public units. Furthermore, the size of the nursing home has a positive effect, and this reinforces our finding that Irish homes produce at increasing returns to scale. Also, notably, we find that a tendency towards quality improvements can lead to poorer technical efficiency performance.
Gap bootstrap methods for massive data sets with an application to transportation engineering
Lahiri, S.N.; Spiegelman, C.; Appiah, J.; Rilett, L.
2013-01-01
In this paper we describe two bootstrap methods for massive data sets. Naive applications of common resampling methodology are often impractical for massive data sets due to computational burden and due to complex patterns of inhomogeneity. In contrast, the proposed methods exploit certain structural properties of a large class of massive data sets to break up the original problem into a set of simpler subproblems, solve each subproblem separately where the data exhibit a...
Austin, Kemen G.; Lee, Michelle E.; Clark, Connie; Forester, Brenna R.; Urban, Dean L.; White, Lee; Kasibhatla, Prasad S.; Poulsen, John R.
2017-01-01
Industrial-scale oil palm cultivation is rapidly expanding in Gabon, where it has the potential to drive economic growth, but also threatens forest, biodiversity and carbon resources. The Gabonese government is promoting an ambitious agricultural expansion strategy, while simultaneously committing to minimize negative environmental impacts of oil palm agriculture. This study estimates the extent and location of suitable land for oil palm cultivation in Gabon, based on an analysis of recent trends in plantation permitting. We use the resulting suitability map to evaluate two proposed approaches to minimizing negative environmental impacts: a High Carbon Stock (HCS) approach, which emphasizes forest protection and climate change mitigation, and a High Conservation Value (HCV) approach, which focuses on safeguarding biodiversity and ecosystems. We quantify the forest area, carbon stock, and biodiversity resources protected under each approach, using newly developed maps of priority species distributions and forest biomass for Gabon. We find 2.7–3.9 Mha of suitable or moderately suitable land that avoid HCS areas, 4.4 million hectares (Mha) that avoid HCV areas, and 1.2–1.7 Mha that avoid both. This suggests that Gabon’s oil palm production target could likely be met without compromising important ecosystem services, if appropriate safeguards are put in place. Our analysis improves understanding of suitability for oil palm in Gabon, determines how conservation strategies align with national targets for oil palm production, and informs national land use planning.
Directory of Open Access Journals (Sweden)
Osmir José Lavoranti
2010-06-01
Full Text Available Reliable evaluation of the stability of genotypes and environment is of prime concern to plant breeders, but the lack of a comprehensive analysis of the structure of the GE interaction has been a stumbling block to the recommendation of varieties. The Additive Main Effects and Multiplicative Interaction (AMMI Model currently offers the good approach to interpretation and understanding of the GE interaction but lacks a way of assessing the stability of its estimates. The present contribution proposes the use of bootstrap resampling
in the AMMI Model, and applies it to obtain both a graphical and a numerical analysis of the phenotypic
stability of 20 Eucalyptus grandis progenies from Australia that were planted in seven environments in the Southern and Southeastern regions of Brazil. The results showed distinct behaviors of genotypes and
environments and the genotype x environment interaction was significant (p value < 0.01. The bootstrap coefficient of stability based on the squared Mahalanobis distance of the scores showed that genotypes and environments can be differentiated in terms of their stabilities. Graphical analysis of the AMMI biplot provided a better understanding of the interpretation of phenotypic stability. The proposed AMMI bootstrap eliminated the uncertainties regarding the identification of low scores in traditional analyses.As posições críticas dos estatísticos, que atuam em programas de melhoramento genético, referem-se à falta de uma análise criteriosa da estrutura da interação do genótipo com o ambiente (GE como um dos principais problemas para a recomendação de cultivares. A metodologia AMMI (additive main effects and multiplicative interaction analysis propõe ser mais eficiente que as análises usuais na interpretação e compreensão da interação GE, entretanto, à dificuldade de se interpretar a interação quando há baixa explicação do primeiro componente principal; à dificuldade de
MGH-USC Human Connectome Project datasets with ultra-high b-value diffusion MRI.
Fan, Qiuyun; Witzel, Thomas; Nummenmaa, Aapo; Van Dijk, Koene R A; Van Horn, John D; Drews, Michelle K; Somerville, Leah H; Sheridan, Margaret A; Santillana, Rosario M; Snyder, Jenna; Hedden, Trey; Shaw, Emily E; Hollinshead, Marisa O; Renvall, Ville; Zanzonico, Roberta; Keil, Boris; Cauley, Stephen; Polimeni, Jonathan R; Tisdall, Dylan; Buckner, Randy L; Wedeen, Van J; Wald, Lawrence L; Toga, Arthur W; Rosen, Bruce R
2016-01-01
The MGH-USC CONNECTOM MRI scanner housed at the Massachusetts General Hospital (MGH) is a major hardware innovation of the Human Connectome Project (HCP). The 3T CONNECTOM scanner is capable of producing a magnetic field gradient of up to 300 mT/m strength for in vivo human brain imaging, which greatly shortens the time spent on diffusion encoding, and decreases the signal loss due to T2 decay. To demonstrate the capability of the novel gradient system, data of healthy adult participants were acquired for this MGH-USC Adult Diffusion Dataset (N=35), minimally preprocessed, and shared through the Laboratory of Neuro Imaging Image Data Archive (LONI IDA) and the WU-Minn Connectome Database (ConnectomeDB). Another purpose of sharing the data is to facilitate methodological studies of diffusion MRI (dMRI) analyses utilizing high diffusion contrast, which perhaps is not easily feasible with standard MR gradient system. In addition, acquisition of the MGH-Harvard-USC Lifespan Dataset is currently underway to include 120 healthy participants ranging from 8 to 90 years old, which will also be shared through LONI IDA and ConnectomeDB. Here we describe the efforts of the MGH-USC HCP consortium in acquiring and sharing the ultra-high b-value diffusion MRI data and provide a report on data preprocessing and access. We conclude with a demonstration of the example data, along with results of standard diffusion analyses, including q-ball Orientation Distribution Function (ODF) reconstruction and tractography.
Spetzler, Vinzent N; Goldaracena, Nicolas; Kaths, Johann M; Marquez, Max; Selzner, Nazia; Cattral, Mark S; Greig, Paul D; Lilly, Les; McGilvray, Ian D; Levy, Gary A; Ghanekar, Anand; Renner, Eberhard L; Grant, David R; Selzner, Markus
2015-11-01
Heme Oxygenase-1 and its product biliverdin/bilirubin have been demonstrated to protect against ischemia/reperfusion injury (IRI). We investigated whether increased preoperative bilirubin values of transplant recipients decrease IRI. Preoperative bilirubin levels of live donor liver recipients were correlated to postoperative liver transaminase as a marker of IRI. Additionally, two recipient groups with pretransplant bilirubin levels >24 μmol/l (n = 348) and ≤24 μmol/l (n = 118) were compared. Post-transplant liver function, complications, length of hospital stay, and patient and graft survival were assessed. Preoperative bilirubin levels were negatively correlated to the postoperative increase in transaminases suggesting a protective effect against IRI. The maximal rise of ALT after transplantation in high versus low bilirubin patients was 288 (-210-2457) U/l vs. 375 (-11-2102) U/l, P = 0.006. Bilirubin remained a significant determining factor in a multivariate linear regression analysis. The MELD score and its individual components as a marker of severity of chronic liver disease were significantly higher in the high versus low bilirubin group (P bilirubin levels of liver recipients before live donor transplantation is associated with decreased postoperative IRI.
Kalathil, Shafeer; Khan, Mohammad Mansoob; Lee, Jintae; Cho, Moo Hwan
2013-11-01
Microorganisms naturally form biofilms on solid surfaces for their mutual benefits including protection from environmental stresses caused by contaminants, nutritional depletion or imbalances. The biofilms are normally dangerous to human health due to their inherited robustness. On the other hand, a recent study suggested that electrochemically active biofilms (EABs) generated by electrically active microorganisms have properties that can be used to catalyze or control the electrochemical reactions in a range of fields, such as bioenergy production, bioremediation, chemical/biological synthesis, bio-corrosion mitigation and biosensor development. EABs have attracted considerable attraction in bioelectrochemical systems (BESs), such as microbial fuel cells and microbial electrolysis cells, where they act as living bioanode or biocathode catalysts. Recently, it was reported that EABs can be used to synthesize metal nanoparticles and metal nanocomposites. The EAB-mediated synthesis of metal and metal-semiconductor nanocomposites is expected to provide a new avenue for the greener synthesis of nanomaterials with high efficiency and speed than other synthetic methods. This review covers the general introduction of EABs, as well as the applications of EABs in BESs, and the production of bio-hydrogen, high value chemicals and bio-inspired nanomaterials.
van Walraven, Carl
2017-04-01
Diagnostic codes used in administrative databases cause bias due to misclassification of patient disease status. It is unclear which methods minimize this bias. Serum creatinine measures were used to determine severe renal failure status in 50,074 hospitalized patients. The true prevalence of severe renal failure and its association with covariates were measured. These were compared to results for which renal failure status was determined using surrogate measures including the following: (1) diagnostic codes; (2) categorization of probability estimates of renal failure determined from a previously validated model; or (3) bootstrap methods imputation of disease status using model-derived probability estimates. Bias in estimates of severe renal failure prevalence and its association with covariates were minimal when bootstrap methods were used to impute renal failure status from model-based probability estimates. In contrast, biases were extensive when renal failure status was determined using codes or methods in which model-based condition probability was categorized. Bias due to misclassification from inaccurate diagnostic codes can be minimized using bootstrap methods to impute condition status using multivariable model-derived probability estimates. Copyright © 2017 Elsevier Inc. All rights reserved.
Economic growth and energy consumption causal nexus viewed through a bootstrap rolling window
Energy Technology Data Exchange (ETDEWEB)
Balcilar, Mehmet [Department of Economics, Eastern Mediterranean University, Famagusta, Turkish Republic of Northern Cyprus, via Mersin 10 (Turkey); Ozdemir, Zeynel Abidin [Department of Economics, Gazi University, Besevler, 06500, Ankara (Turkey); Arslanturk, Yalcin [Gazi University, Teknikokullar, 06500, Ankara (Turkey)
2010-11-15
One puzzling results in the literature on energy consumption-economic growth causality is the variability of results particularly across sample periods, sample sizes, and model specification. In order overcome these issues this paper analyzes the causal links between energy consumption and economic growth for G-7 countries using bootstrap Granger non-causality tests with fixed size rolling subsamples. The data used includes annual total energy consumption and real Gross Domestic Product (GDP) series from 1960 to 2006 for G-7 countries, excluding Germany, for which the sample period starts from 1971. Using the full sample bootstrap Granger causality test, we find that there is predictive power from energy consumption to economic growth only for Canada. However, parameter instability tests show that none of the estimated models have constant parameters and hence the full sample results are not reliable. Analogous to the full sample results, the results obtained from the bootstrap rolling window estimation indicate no consistent causal links between energy consumption and economic growth. We, however, find that causal links are present between the series in various subsamples. Furthermore, these subsample periods correspond to significant economic events, indicating that the findings are not statistical artefacts, but correspond to real economic changes. Our results encompass previous findings and offer an explanation to varying findings. (author)
The sound symbolism bootstrapping hypothesis for language acquisition and language evolution.
Imai, Mutsumi; Kita, Sotaro
2014-09-19
Sound symbolism is a non-arbitrary relationship between speech sounds and meaning. We review evidence that, contrary to the traditional view in linguistics, sound symbolism is an important design feature of language, which affects online processing of language, and most importantly, language acquisition. We propose the sound symbolism bootstrapping hypothesis, claiming that (i) pre-verbal infants are sensitive to sound symbolism, due to a biologically endowed ability to map and integrate multi-modal input, (ii) sound symbolism helps infants gain referential insight for speech sounds, (iii) sound symbolism helps infants and toddlers associate speech sounds with their referents to establish a lexical representation and (iv) sound symbolism helps toddlers learn words by allowing them to focus on referents embedded in a complex scene, alleviating Quine's problem. We further explore the possibility that sound symbolism is deeply related to language evolution, drawing the parallel between historical development of language across generations and ontogenetic development within individuals. Finally, we suggest that sound symbolism bootstrapping is a part of a more general phenomenon of bootstrapping by means of iconic representations, drawing on similarities and close behavioural links between sound symbolism and speech-accompanying iconic gesture. © 2014 The Author(s) Published by the Royal Society. All rights reserved.
Conformal Bootstrap Approach to O(N) Fixed Points in Five Dimensions
Bae, Jin-Beom
2014-01-01
Whether O(N)-invariant conformal field theory exists in five dimensions with its implication to higher-spin holography was much debated. We find an affirmative result on this question by utilizing conformal bootstrap approach. In solving for the crossing symmetry condition, we propose a new approach based on specification for the low-lying spectrum distribution. We find the traditional one-gap bootstrapping is not suited since the nontrivial fixed point expected from large-N expansion sits at deep interior (not at boundary or kink) of allowed solution region. We propose two-gap bootstrapping that specifies scaling dimension of two lowest scalar operators. The approach carves out vast region of lower scaling dimensions and universally features two tips. We find that the sought-for nontrivial fixed point now sits at one of the tips, while the Gaussian fixed point sits at the other tip. The scaling dimensions of scalar operators fit well with expectation based on large-N expansion. We also find indication that t...
Y-90 PET imaging for radiation theragnosis using bootstrap event re sampling
Energy Technology Data Exchange (ETDEWEB)
Nam, Taewon; Woo, Sangkeun; Min, Gyungju; Kim, Jimin; Kang, Joohyun; Lim, Sangmoo; Kim, Kyeongmin [Korea Institute of Radiological and Medical Sciences, Seoul (Korea, Republic of)
2013-05-15
Surgical resection is the most effective method to recover the liver function. However, Yttrium-90 (Y-90) has been used as a new treatment due to the fact that it can be delivered to the tumors and results in greater radiation exposure to the tumors than using external radiation nowadays since most treatment is palliative in case of unresectable stage of hepatocellular carcinoma (HCC). Recently, Y-90 has been received much interest and studied by many researchers. Imaging of Y-90 has been conducted using most commonly gamma camera but PET imaging is required due to low sensitivity and resolution. The purpose of this study was to assess statistical characteristics and to improve count rate of image for enhancing image quality by using nonparametric bootstrap method. PET data was able to be improved using non-parametric bootstrap method and it was verified with showing improved uniformity and SNR. Uniformity showed more improvement under the condition of low count rate, i.e. Y-90, in case of phantom and also uniformity and SNR showed improvement of 15.6% and 33.8% in case of mouse, respectively. Bootstrap method performed in this study for PET data increased count rate of PET image and consequentially time for acquisition time can be reduced. It will be expected to improve performance for diagnosis.
Simulation of bootstrap current in 2D and 3D ideal magnetic fields in tokamaks
Raghunathan, M.; Graves, J. P.; Cooper, W. A.; Pedro, M.; Sauter, O.
2016-09-01
We aim to simulate the bootstrap current for a MAST-like spherical tokamak using two approaches for magnetic equilibria including externally caused 3D effects such as resonant magnetic perturbations (RMPs), the effect of toroidal ripple, and intrinsic 3D effects such as non-resonant internal kink modes. The first approach relies on known neoclassical coefficients in ideal MHD equilibria, using the Sauter (Sauter et al 1999 Phys. Plasmas 6 2834) expression valid for all collisionalities in axisymmetry, and the second approach being the quasi-analytic Shaing-Callen (Shaing and Callen 1983 Phys. Fluids 26 3315) model in the collisionless regime for 3D. Using the ideal free-boundary magnetohydrodynamic code VMEC, we compute the flux-surface averaged bootstrap current density, with the Sauter and Shaing-Callen expressions for 2D and 3D ideal MHD equilibria including an edge pressure barrier with the application of resonant magnetic perturbations, and equilibria possessing a saturated non-resonant 1/1 internal kink mode with a weak internal pressure barrier. We compare the applicability of the self-consistent iterative model on the 3D applications and discuss the limitations and advantages of each bootstrap current model for each type of equilibrium.
Courtright, Katherine R; Weinberger, Steven E; Wagner, Jason
2015-04-01
Physician decision making is partially responsible for the roughly 30% of U.S. healthcare expenditures that are wasted annually on low-value care. In response to both the widespread public demand for higher-quality care and the cost crisis, payers are transitioning toward value-based payment models whereby physicians are rewarded for high-value, cost-conscious care. Furthermore, to target physicians in training to practice with cost awareness, the Accreditation Council for Graduate Medical Education has created both individual objective milestones and institutional requirements to incorporate quality improvement and cost awareness into fellowship training. Subsequently, some professional medical societies have initiated high-value care educational campaigns, but the overwhelming majority target either medical students or residents in training. Currently, there are few resources available to help guide subspecialty fellowship programs to successfully design durable high-value care curricula. The resource-intensive nature of pulmonary and critical care medicine offers unique opportunities for the specialty to lead in modeling and teaching high-value care. To ensure that fellows graduate with the capability to practice high-value care, we recommend that fellowship programs focus on four major educational domains. These include fostering a value-based culture, providing a robust didactic experience, engaging trainees in process improvement projects, and encouraging scholarship. In doing so, pulmonary and critical care educators can strive to train future physicians who are prepared to provide care that is both high quality and informed by cost awareness.
Development of a high-value care subscore on the internal medicine in-training examination.
Ryskina, Kira L; Korenstein, Deborah; Weissman, Arlene; Masters, Philip; Alguire, Patrick; Smith, Cynthia D
2014-11-18
Although high-value care (HVC) that balances benefits of tests or treatments against potential harms and costs has been a recently emphasized competency for internal medicine (IM) residents, few tools to assess residents' knowledge of HVC are available. To describe the development and initial results of an HVC subscore of the Internal Medicine In-Training Examination (IM-ITE). The HVC concepts were introduced to IM-ITE authors during question development. Three physicians independently reviewed each examination question for selection in the HVC subscore according to 6 HVC principles. The final subscore was determined by consensus. Data from the IM-ITE administered in October 2012 were analyzed at the program level. U.S. IM residency programs. 362 U.S. IM residency programs with IM-ITE data for at least 10 residents. Program-level performance on the HVC subscore was compared with performance on the overall IM-ITE, the Dartmouth Atlas hospital care intensity (HCI) index of the program's primary training hospital, and residents' attitudes about HVC assessed with a voluntary survey. The HVC subscore comprised 38 questions, including 21 (55%) on managing conservatively when appropriate and 14 (37%) on identifying low-value care. Of the 362 U.S. IM programs in the sample, 41% were in a different quartile when ranked based on the HVC subscore compared with overall IM-ITE performance. Rankings by HVC subscore and HCI index were modestly inversely associated, with 30% of programs ranked in the same quartile based on both measures. Knowledge of HVC assessed from examination vignettes may not reflect practice of HVC. Although the HVC subscore has face validity and can contribute to evaluation of residents' HVC knowledge, additional tools are needed to accurately measure residents' proficiency in HVC. None.
On-Shell Unitarity Bootstrap for QCD Amplitudes
Energy Technology Data Exchange (ETDEWEB)
Berger, Carola F.; Bern, Zvi; Dixon, Lance J.; Forde, Darren; Kosower, David A.
2006-10-17
Seeking and measuring new physics at the imminent Large Hadron Collider (LHC) will require extensive calculations of high-multiplicity backgrounds in perturbative QCD to next-to-leading order (NLO). The Les Houches 2005 workshop defined a target list, reproduced in table 1, for theorists to attack. In addition to the processes in the table, one would also like to compute processes such as W, Z + 4 jets, which are important backgrounds to searches for supersymmetry and other models of new electroweak physics. Such computations require one-loop amplitudes with seven external particles, including the vector boson, as depicted in figure 1. These are challenging calculations and Feynman-diagrammatic computations have only recently reached six-point amplitudes. Some of this progress has been described in this conference.
Indian Academy of Sciences (India)
A K Pulhani; M L Shah; G P Gupta; B M Suri
2010-12-01
Spectrally resolved laser-induced fluorescence technique was used to uniquely assign total angular momentum () values to high-lying even-parity energy levels of atomic samarium. Unique value assignment was done for seven energy levels in the energy region 34,800–36,200 cm-1 , recently observed and reported in the literature.
Multivariate bootstrapped relative positioning of spacecraft using GPS L1/Galileo E1 signals
Buist, Peter J.; Teunissen, Peter J. G.; Giorgi, Gabriele; Verhagen, Sandra
2011-03-01
GNSS-based precise relative positioning between spacecraft normally requires dual frequency observations, whereas attitude determination of the spacecraft, mainly due to the stronger model given by the a priori knowledge of the length and geometry of the baselines, can be performed precisely using only single frequency observations. When the Galileo signals will come available, the number of observations at the L1 frequency will increase as we will have a GPS and Galileo multi-constellation. Moreover the L1 observations of the Galileo system and modernized GPS are more precise than legacy GPS and this, combined with the increased number of observations, will result in a stronger model for single frequency relative positioning. In this contribution we will develop an even stronger model by combining the attitude determination problem with relative positioning. The attitude determination problem will be solved by the recently developed Multivariate Constrained (MC-) LAMBDA method. We will do this for each spacecraft and use the outcome for an ambiguity constrained solution on the baseline between the spacecraft. In this way the solution for the unconstrained baseline is bootstrapped from the MC-LAMBDA solutions of each spacecraft in what is called: multivariate bootstrapped relative positioning. The developed approach will be compared in simulations with relative positioning using a single antenna at each spacecraft (standard LAMBDA) and a vectorial bootstrapping approach. In the simulations we will analyze single epoch, single frequency success rates as the most challenging application. The difference in performance for the approaches for single epoch solutions, is a good indication of the strength of the underlying models. As the multivariate bootstrapping approach has a stronger model by applying information on the geometry of the constrained baselines, for applications with large observation noise and limited number of observations this will result in a better
Institute of Scientific and Technical Information of China (English)
CHAN Kung-Sik; TONG Howell; STENSETH Nils Chr
2009-01-01
The study of the rodent fluctuations of the North was initiated in its modern form with Elton's pioneering work. Many scientific studies have been designed to collect yearly rodent abundance data, but the resulting time series are generally subject to at least two "problems": being short and non-linear. We explore the use of the continuous threshold autoregressive (TAR) models for analyzing such data. In the simplest case, the continuous TAR models are additive autoregressive models, being piecewise linear in one lag, and linear in all other lags. The location of the slope change is called the threshold parameter. The continuous TAR models for rodent abundance data can be derived from a general prey-predator model under some simplifying assumptions. The lag in which the threshold is located sheds important insights on the structure of the prey-predator system. We propose to assess the uncertainty on the location of the threshold via a new bootstrap called the nearest block bootstrap (NBB) which combines the methods of moving block bootstrap and the nearest neighbor bootstrap.The NBB assumes an underlying finite-order time-homogeneous Markov process. Essentially, the NBB bootstraps blocks of random block sizes, with each block being drawn from a non-parametric estimate of the future distribution given the realized past bootstrap series. We illustrate the methods by simulations and on a particular rodent abundance time series from Kilpisjarvi, Northern Finland.
Karnieli-Miller, Orit; Taylor, Amanda C; Inui, Thomas S; Ivy, Steven S; Frankel, Richard M
2011-10-01
OBJECTIVE—: To understand high-performing frontline employees' values as reflected in their narratives of day-to-day interactions in a large health care organization. METHODS—: A total of 150 employees representing various roles within the organization were interviewed and asked to share work-life narratives (WLNs) about value-affirming situations (i.e. situations in which they believed their actions to be fully aligned with their values) and value-challenging situations (i.e. when their actions or the actions of others were not consistent with their values), using methods based on appreciative inquiry. RESULTS—: The analysis revealed 10 broad values. Most of the value-affirming WLNs were about the story-teller and team providing care for the patient/family. Half of the value-challenging WLNs were about the story-teller or a patient and barriers created by the organization, supervisor, or physician. Almost half of these focused on "treating others with disrespect/respect". Only 15% of the value-challenging WLNs contained a resolution reached by the participants, often leaving them describing unresolved and frequently negative feelings. CONCLUSIONS—: Appreciative inquiry and thematic analysis methods were found to be an effective tool for understanding the important and sometimes competing role personal and institutional values play in day-to-day work. There is remarkable potential in using WLNs as a way to surface and reinforce shared values and, perhaps more importantly, respectfully to identify and discuss conflicting personal and professional values.
Bootstrapping agency: How control-relevant information affects motivation.
Karsh, Noam; Eitam, Baruch; Mark, Ilya; Higgins, E Tory
2016-10-01
How does information about one's control over the environment (e.g., having an own-action effect) influence motivation? The control-based response selection framework was proposed to predict and explain such findings. Its key tenant is that control relevant information modulates both the frequency and speed of responses by determining whether a perceptual event is an outcome of one's actions or not. To test this framework empirically, the current study examines whether and how temporal and spatial contiguity/predictability-previously established as being important for one's sense of agency-modulate motivation from control. In 5 experiments, participants responded to a cue, potentially triggering a perceptual effect. Temporal (Experiments 1a-c) and spatial (Experiments 2a and b) contiguity/predictability between actions and their potential effects were experimentally manipulated. The influence of these control-relevant factors was measured, both indirectly (through their effect on explicit judgments of agency) and directly on response time and response frequency. The pattern of results was highly consistent with the control-based response selection framework in suggesting that control relevant information reliably modulates the impact of "having an effect" on different levels of action selection. We discuss the implications of this study for the notion of motivation from control and for the empirical work on the sense of agency. (PsycINFO Database Record (c) 2016 APA, all rights reserved).
Chemicals to enhance microalgal growth and accumulation of high-value bioproducts
Directory of Open Access Journals (Sweden)
Xinheng eYu
2015-02-01
Full Text Available Photosynthetic microalgae have attracted significant attention as they can serve as important sources for cosmetic, food and pharmaceutical products, industrial materials and even biofuel biodiesels. However, current productivity of microalga-based processes is still very low, which has restricted their scale-up application. In addition to various efforts in strain improvement and cultivation optimization, it was proposed that the productivity of microalga-based processes can also be increased using various chemicals to trigger or enhance cell growth and accumulation of bioproducts. Herein, we summarized recent progresses in applying chemical triggers or enhancers to improve cell growth and accumulation of bioproducts in algal cultures. Based on their enhancing mechanisms, these chemicals can be classified into four categories：chemicals regulating biosynthetic pathways, chemicals inducing oxidative stress responses, phytohormones and analogues regulating multiple aspects of microalgal metabolism, and chemicals directly as metabolic precursors. Taken together, the early researches demonstrated that the use of chemical stimulants could be a very effective and economical way to improve cell growth and accumulation of high-value bioproducts in large-scale cultivation of microalgae.
Directory of Open Access Journals (Sweden)
Dora Cimini
2013-12-01
Full Text Available A general trend of scrub encroachment and natural forest expansion (old-field succession has been occurring in the past fifty years in Mediterranean mountain areas. While this phenomenon enhances a series of ecological processes and environmental services, it may represent a threat for biodiversity conservation when occurring on high nature value (HNV extensive farmland. These open areas, created by traditional farming systems, have been recognized as a critically important European biodiversity resource. Understanding the drivers of Land Use and Land Cover Change (LUCC and their implications on the dynamics of forest and HNV farmland habitats plays a crucial role in biodiversity conservation in protected areas. In this perspective, the case study here presented aims to model recent (1989-2008 LUCC in a National Park of the Central Apennines (Italy and to produce a mid-term forecast (2008-2020. In the past twenty years, 57% of the land uptake by shrubland and 46% by forest has been occurring on former HNV farmland. Mid-term projections (2008-2020 confirm further HNV farmland decline. Localization of HNV farmland habitats vulnerable to change is a valuable decision-making tool to tradeoff in protected areas the conservation of traditional landscapes with the increase of forest and shrubland areas. In this perspective, concrete socio-economical and silvicultural measures are outlined to preserve these socially and economically-fragile open habitats.
Directory of Open Access Journals (Sweden)
Abebe Ejigu Alemu
2016-09-01
Full Text Available Hybrid coordination systems (marketing cooperatives and contracts are in place in agriculture to link smallholder farmers to the global agri-food value chains. With the framework of transaction cost economics, this study, however, is particularly designed to investigate the key determinants pushing dairy farmers to hybrids (marketing cooperatives and contracts, viz. spot market channels in the local food chains. A household survey of 415 smallholder dairy farmers was designed. Data collection was administered using trained enumerators. A multinomial logistic regression model was employed to analyze data and to identify the signifi cant determinants. The results indicate that high transaction costs and resource constraints were found driving farmers to cooperative engagement and contracts, implying that hybrids were found to be a solution to farmers’ constraints of access to information and institutional absence, as well as resource constraints. Policy makers and development partners are advised to strengthen cooperative societies and contract enforcement mechanisms. Providing information and resources to increase smallholders’ capacity with resources appear to be interventions which will enable the agricultural marketing system to properly function by serving smallholders in linking to the global food chains.
Lipid metabolism and potentials of biofuel and high added-value oil production in red algae.
Sato, Naoki; Moriyama, Takashi; Mori, Natsumi; Toyoshima, Masakazu
2017-04-01
Biomass production is currently explored in microalgae, macroalgae and land plants. Microalgal biofuel development has been performed mostly in green algae. In the Japanese tradition, macrophytic red algae such as Pyropia yezoensis and Gelidium crinale have been utilized as food and industrial materials. Researches on the utilization of unicellular red microalgae such as Cyanidioschyzon merolae and Porphyridium purpureum started only quite recently. Red algae have relatively large plastid genomes harboring more than 200 protein-coding genes that support the biosynthetic capacity of the plastid. Engineering the plastid genome is a unique potential of red microalgae. In addition, large-scale growth facilities of P. purpureum have been developed for industrial production of biofuels. C. merolae has been studied as a model alga for cell and molecular biological analyses with its completely determined genomes and transformation techniques. Its acidic and warm habitat makes it easy to grow this alga axenically in large scales. Its potential as a biofuel producer is recently documented under nitrogen-limited conditions. Metabolic pathways of the accumulation of starch and triacylglycerol and the enzymes involved therein are being elucidated. Engineering these regulatory mechanisms will open a possibility of exploiting the full capability of production of biofuel and high added-value oil. In the present review, we will describe the characteristics and potential of these algae as biotechnological seeds.
Technologies for Real-Time Monitoring and Surveillance of High-Valued Assets
Energy Technology Data Exchange (ETDEWEB)
Pickett, Chris A [ORNL; Richardson, Dave [ORNL; Stinson, Brad J [ORNL; Younkin, James R [ORNL
2007-01-01
The Oak Ridge National Laboratory (ORNL) has been working on technologies that can provide real-time monitoring and surveillance of high-valued assets. It is hoped through effective system design that some of these technologies can be utilized as the technical equivalent for the "two person rule" (required for many domestic safeguards operations). The major efforts associated with this work to date involve the integration and adaptation of commercial-off-the-shelf (COTS) radio frequency-based technologies into basic system elements that can be effectively layered into integrated unobtrusive monitoring systems that are specifically designed to detect unauthorized asset movements. Each system element is designed to provide real-time monitoring and surveillance of both protected assets and the people who have access to them. The goal is to accomplish up-to-the-minute status of monitored assets using site-specific, rules-based algorithms. The overall system concepts focus on early detection (of theft or diversion) at the asset, followed by appropriate alarms or notifications that can be used to initiate appropriate response(s).
Revival of high street retailing – the added value of shopping apps
Directory of Open Access Journals (Sweden)
Jelena Demko-Rihter
2015-05-01
Full Text Available Rapid and constant development of technology and social media drive every-day changes in the retail sector, modifying behaviour and power of consumers, whereby traditional brick and mortar stores are facing the risk to become obsolete. E-commerce and m-commerce offer to customer a more convenient, faster and easier way of shopping and the possibility to customize products and services to the individual needs of customers. There are different business models and tools for enhancing the on-line retail industry, which causes changes in the business of the whole retail sector, as well as in the micro and macro social and economic environment. One of consequences of increasing value of the on-line retail industry is a dropping number of customers shopping for products in brick and mortar stores in high streets and city centers. Brick and mortar retailers are exploring new ways to reach these lost shoppers. In this study an innovative application is researched that tries to bridge online and in-store shopping with an online platform (website and a smart-phone app. The aim of this platform and app is to enhance the local shopping experience by making the physical city centre available for smart-phones and tablets.
Mini-review: In vitro Metabolic Engineering for Biomanufacturing of High-value Products.
Guo, Weihua; Sheng, Jiayuan; Feng, Xueyang
2017-01-01
With the breakthroughs in biomolecular engineering and synthetic biology, many valuable biologically active compound and commodity chemicals have been successfully manufactured using cell-based approaches in the past decade. However, because of the high complexity of cell metabolism, the identification and optimization of rate-limiting metabolic pathways for improving the product yield is often difficult, which represents a significant and unavoidable barrier of traditional in vivo metabolic engineering. Recently, some in vitro engineering approaches were proposed as alternative strategies to solve this problem. In brief, by reconstituting a biosynthetic pathway in a cell-free environment with the supplement of cofactors and substrates, the performance of each biosynthetic pathway could be evaluated and optimized systematically. Several value-added products, including chemicals, nutraceuticals, and drug precursors, have been biosynthesized as proof-of-concept demonstrations of in vitro metabolic engineering. This mini-review summarizes the recent progresses on the emerging topic of in vitro metabolic engineering and comments on the potential application of cell-free technology to speed up the "design-build-test" cycles of biomanufacturing.
Deformation of Cases in High Capacitance Value Wet Tantalum Capacitors under Environmental Stresses
Teverovsky, Alexander
2016-01-01
Internal gas pressure in hermetic wet tantalum capacitors is created by air, electrolyte vapor, and gas generated by electrochemical reactions at the electrodes. This pressure increases substantially with temperature and time of operation due to excessive leakage currents. Deformation of the case occurs when the internal pressure exceeds pressure of the environments and can raise significantly when a part operates in space. Contrary to the cylinder case wet tantalum capacitors that have external sealing by welding and internal sealing provided by the Teflon bushing and crimping of the case, no reliable internal sealing exists in the button case capacitors. Single seal design capacitors are used for high capacitance value wet tantalum capacitors manufactured per DLA L&M drawings #04003, 04005, and 10011, and require additional analysis to assure their reliable application in space systems. In this work, leakage currents and case deformation of button case capacitors were measured during different environmental test conditions. Recommendations for derating, screening and qualification testing are given. This work is a continuation of a series of NEPP reports related to quality and reliability of wet tantalum capacitors.
Simultaneous distillation-extraction of high-value volatile compounds from Cistus ladanifer L.
Teixeira, Salomé; Mendes, Adélio; Alves, Arminda; Santos, Lúcia
2007-02-19
The present paper describes a procedure to isolate volatiles from rock-rose (Cistus ladanifer L.) using simultaneous distillation-extraction (SDE). High-value volatile compounds (HVVC) were selected and the influence of the extraction conditions investigated. The effect of the solvent nature and extraction time on SDE efficiency was studied. The best performance was achieved with pentane in 1 h operation. The extraction efficiencies ranged from 65% to 85% and the repeatability varied between 4% and 6% (as a CV%). The C. ladanifer SDE extracts were analysed by headspace solid phase microextraction (HS-SPME) followed by gas chromatography with flame ionization detection (GC-FID). The HS-SPME sampling conditions such as fiber coating, temperature, ionic strength and exposure time were optimized. The best results were achieved with an 85 microm polyacrylate fiber for a 60 min headspace extraction at 40 degrees C with 20% (w/v) of NaCl. For optimized conditions the recovery was in average higher than 90% for all compounds and the intermediate precision ranged from 4 to 9% (as CV %). The volatiles alpha-pinene (22.2 mg g(-1) of extract), 2,2,6-trimethylcyclohexanone (6.1 mg g(-1) of extract), borneol (3.0 mg g(-1) of extract) and bornyl acetate (3.9 mg g(-1) of extract) were identified in the SDE extracts obtained from the fresh plant material.
Chemicals to enhance microalgal growth and accumulation of high-value bioproducts.
Yu, Xinheng; Chen, Lei; Zhang, Weiwen
2015-01-01
Photosynthetic microalgae have attracted significant attention as they can serve as important sources for cosmetic, food and pharmaceutical products, industrial materials and even biofuel biodiesels. However, current productivity of microalga-based processes is still very low, which has restricted their scale-up application. In addition to various efforts in strain improvement and cultivation optimization, it was proposed that the productivity of microalga-based processes can also be increased using various chemicals to trigger or enhance cell growth and accumulation of bioproducts. Herein, we summarized recent progresses in applying chemical triggers or enhancers to improve cell growth and accumulation of bioproducts in algal cultures. Based on their enhancing mechanisms, these chemicals can be classified into four categories:chemicals regulating biosynthetic pathways, chemicals inducing oxidative stress responses, phytohormones and analogs regulating multiple aspects of microalgal metabolism, and chemicals directly as metabolic precursors. Taken together, the early researches demonstrated that the use of chemical stimulants could be a very effective and economical way to improve cell growth and accumulation of high-value bioproducts in large-scale cultivation of microalgae.
DEFF Research Database (Denmark)
Sriskandarajah, Srishamanthi; Carter-Storch, Rasmus; Frydkjær-Olsen, Ulrik;
2016-01-01
, pancreatitis, deep venous thrombosis (DVT), pyelonephritis and intestinal obstruction. The presumptive diagnoses were compared with the final diagnosis on discharge. Sensitivity, specificity, predictive values and likelihood ratios were calculated. RESULTS: A total of 8,841 patients were enrolled. The highest...... and lowest sensitivities were seen for DVT (90%) and meningitis (36%), respectively; and the highest and lowest values for specificity were observed for meningitis (99%) and ACS (30%), respectively. The positive predictive value had a wide range with the lowest value for ACS (9%) and the highest...
Pang, Yi; Su, Ning
2016-01-01
We consider $\\phi^3$ theory in $6-2\\epsilon$ with $F_4$ global symmetry. The beta function is calculated up to 3 loops, and a stable unitary IR fixed point is observed. The anomalous dimensions of operators quadratic or cubic in $\\phi$ are also computed. We then employ conformal bootstrap technique to study the fixed point predicted from the perturbative approach. For each putative scaling dimension of $\\phi$ ($\\Delta_{\\phi})$, we obtain the corresponding upper bound on the scaling dimension of the second lowest scalar primary in the ${\\mathbf 26}$ representation $(\\Delta^{\\rm 2nd}_{{\\mathbf 26}})$ which appears in the OPE of $\\phi\\times\\phi$. In $D=5.95$, we observe a sharp peak on the upper bound curve located at $\\Delta_{\\phi}$ equal to the value predicted by the 3-loop computation. In $D=5$, we observe a weak kink on the upper bound curve at $(\\Delta_{\\phi},\\Delta^{\\rm 2nd}_{{\\mathbf 26}})$=$(1.6,4)$.
High and low value fish chains in the Mekong Delta: challenges for livelihoods and governance
Vo Thi Thanh Loc,; Bush, S.R.; Xuan Sinh, Le; Nguyen Tri Khiem,
2010-01-01
This paper investigates the structure, function and wealth distribution within the Pangasius hypophthalmus and Henicorhynchus spp./Labiobarbus spp. value chains in the Mekong Delta of Vietnam. The analysis is driven by key questions relating to the form and function of value chains, their contributi
Demand Forecasting: DLA’S Aviation Supply Chain High Value Products
2015-04-09
seems to dominate the pattern of product demand from FY10 to FY13. However, as discussed above, the outlier demand value in FY13 could have zapped out...seems to dominate the pattern of product demand, and on the other, an extreme outlier value that could zap out some of the FY14 product demand. We
Vries, de S.; Buijs, A.E.; Langers, F.; Farjon, F.; Hinsberg, van A.; Sijtsma, F.J.
2013-01-01
In a Cost-Benefit Analysis (CBA) or an Environmental Impact Assessment (EIA), determining the value that the general public attaches to a landscape is often problematic. To aid the inclusion of this social value in such analyses, a Google Maps-based tool, called the HotSpotMonitor (HSM), was develop
Vries, de S.; Buijs, A.E.; Langers, F.; Farjon, F.; Hinsberg, van A.; Sijtsma, F.J.
2013-01-01
In a Cost-Benefit Analysis (CBA) or an Environmental Impact Assessment (EIA), determining the value that the general public attaches to a landscape is often problematic. To aid the inclusion of this social value in such analyses, a Google Maps-based tool, called the HotSpotMonitor (HSM), was develop
High-Intensity Interval Training, Appetite, and Reward Value of Food in the Obese.
Martins, Catia; Aschehoug, Irina; Ludviksen, Marit; Holst, Jens; Finlayson, Graham; Wisloff, Ulrik; Morgan, Linda; King, Neil; Kulseng, Bård
2017-09-01
Studies on the effect of chronic interval training on appetite in the obese population are scarce. The aim of this study was to determine the effect of 12 wk of isocaloric programs of moderate-intensity continuous training (MICT), high-intensity interval training (HIIT), or short-duration HIIT on subjective feelings of appetite, appetite-related hormones, and reward value of food in sedentary obese individuals. Forty-six sedentary obese individuals (30 women and 16 men), with a body mass index of 33.3 ± 2.9 kg·m and age of 34.4 ± 8.8 yr, were randomly assigned to one of the three training groups: MICT (n = 14), HIIT (n = 16), or short-duration HIIT (n = 16). Exercise was performed three times per week for 12 wk. Subjective feelings of appetite and plasma levels of acylated ghrelin, polypeptide YY3-36, and glucagon-like peptide 1 were measured before and after a standard breakfast (every 30 min up to 3 h), before and after the exercise intervention. Fat and sweet taste preferences and food reward were measured using the Leeds Food Preference Questionnaire. A significant increase in fasting and postprandial feelings of hunger was observed with the exercise intervention (P = 0.01 and P = 0.048, respectively), but no effect of group and no interaction. No significant effect of exercise intervention, group, or interaction was found on fasting or postprandial subjective feelings of fullness, desire to eat, and prospective food consumption or plasma concentration of acylated ghrelin, polypeptide YY3-36, and glucagon-like peptide 1. No changes in food preference or reward over time, differences between groups, or interactions were found. This study suggests that chronic HIIT has no independent effect on appetite or food reward when compared with an isocaloric program of MICT in obese individuals.
Shah, Md. Mahfuzur R.; Liang, Yuanmei; Cheng, Jay J.; Daroch, Maurycy
2016-01-01
Many species of microalgae have been used as source of nutrient rich food, feed, and health promoting compounds. Among the commercially important microalgae, Haematococcus pluvialis is the richest source of natural astaxanthin which is considered as “super anti-oxidant.” Natural astaxanthin produced by H. pluvialis has significantly greater antioxidant capacity than the synthetic one. Astaxanthin has important applications in the nutraceuticals, cosmetics, food, and aquaculture industries. It is now evident that, astaxanthin can significantly reduce free radicals and oxidative stress and help human body maintain a healthy state. With extraordinary potency and increase in demand, astaxanthin is one of the high-value microalgal products of the future.This comprehensive review summarizes the most important aspects of the biology, biochemical composition, biosynthesis, and astaxanthin accumulation in the cells of H. pluvialis and its wide range of applications for humans and animals. In this paper, important and recent developments ranging from cultivation, harvest and postharvest bio-processing technologies to metabolic control and genetic engineering are reviewed in detail, focusing on biomass and astaxanthin production from this biotechnologically important microalga. Simultaneously, critical bottlenecks and major challenges in commercial scale production; current and prospective global market of H. pluvialis derived astaxanthin are also presented in a critical manner. A new biorefinery concept for H. pluvialis has been also suggested to guide toward economically sustainable approach for microalgae cultivation and processing. This report could serve as a useful guide to present current status of knowledge in the field and highlight key areas for future development of H. pluvialis astaxanthin technology and its large scale commercial implementation. PMID:27200009
Directory of Open Access Journals (Sweden)
Md. Mahfuzur Rahman Shah
2016-04-01
Full Text Available Many species of microalgae have been used as source of nutrient rich food, feed and health promoting compounds. Among the commercially important microalgae, Haematococcus pluvialis is the richest source of natural astaxanthin which is considered as super anti-oxidant. Natural astaxanthin produced by H. pluvialis has significantly greater antioxidant capacity than the synthetic one. Astaxanthin has important applications in the nutraceuticals, cosmetics, food, and aquaculture industries. Thanks to many researches it is now evident, that astaxanthin can significantly reduce free radicals and oxidative stress and help human body maintain a healthy state. With extraordinary potency and increase in demand, astaxanthin is one of the high-value microalgal products of the future. Thus, this comprehensive review summarizes the most important aspects of the biology, biochemical composition, biosynthesis and astaxanthin accumulation in the cells of H. pluvialis and its wide range of applications for humans and animals. In this paper, important and recent developments ranging from cultivation, harvest and postharvest bio-processing technologies to metabolic control and genetic engineering are reviewed in detail, focusing on biomass and astaxanthin production from this biotechnologically important microalga. Simultaneously, critical bottlenecks and major challenges in commercial scale production; current and prospective global market of H. pluvialis derived astaxanthin are also presented in a critical manner. A new biorefinery concept for H. pluvialis has been also suggested to guide towards economically sustainable approach for microalgae cultivation and processing. This report could serve as a useful guide to present current status of knowledge in the field and highlight key areas for future development of H. pluvialis astaxanthin technology and its large scale commercial implementation.
Shah, Md Mahfuzur R; Liang, Yuanmei; Cheng, Jay J; Daroch, Maurycy
2016-01-01
Many species of microalgae have been used as source of nutrient rich food, feed, and health promoting compounds. Among the commercially important microalgae, Haematococcus pluvialis is the richest source of natural astaxanthin which is considered as "super anti-oxidant." Natural astaxanthin produced by H. pluvialis has significantly greater antioxidant capacity than the synthetic one. Astaxanthin has important applications in the nutraceuticals, cosmetics, food, and aquaculture industries. It is now evident that, astaxanthin can significantly reduce free radicals and oxidative stress and help human body maintain a healthy state. With extraordinary potency and increase in demand, astaxanthin is one of the high-value microalgal products of the future.This comprehensive review summarizes the most important aspects of the biology, biochemical composition, biosynthesis, and astaxanthin accumulation in the cells of H. pluvialis and its wide range of applications for humans and animals. In this paper, important and recent developments ranging from cultivation, harvest and postharvest bio-processing technologies to metabolic control and genetic engineering are reviewed in detail, focusing on biomass and astaxanthin production from this biotechnologically important microalga. Simultaneously, critical bottlenecks and major challenges in commercial scale production; current and prospective global market of H. pluvialis derived astaxanthin are also presented in a critical manner. A new biorefinery concept for H. pluvialis has been also suggested to guide toward economically sustainable approach for microalgae cultivation and processing. This report could serve as a useful guide to present current status of knowledge in the field and highlight key areas for future development of H. pluvialis astaxanthin technology and its large scale commercial implementation.
Upgrading of Bio-Oil into High-Value Hydrocarbons via Hydrodeoxygenation
Directory of Open Access Journals (Sweden)
Murni M. Ahmad
2010-01-01
Full Text Available Problem statement: World energy consumption is forecasted to grow significantly for the foreseeable future with fossil fuel remains the governing energy source. The demand in the need to explore alternative fuel source was further triggered by the overwhelmingly inconsistent cost of gasoline. Bio-oil is an alternative energy source produced from pyrolysis of biomass. However it is undesirable as a ready alternative transportation fuel due to its unfavorable nature i.e., highly oxygenated and low octane number. To overcome these physicochemical issues, hydrodeoxygenation reaction is a possible upgrading method i.e., by partial or total elimination of oxygen and hydrogenation of chemical structures. Hence, this study aimed to investigate feasible routes and to develop the process route to upgrade the pyrolytic bio-oil from biomass into value-added chemicals for the production of transportation fuel, i.e., benzene and cyclohexane, via hydrodeoxygenation process via simulation in PETRONAS iCON software. Approach: In this study, hydrodeoxygenation of phenols and substituted phenols was used to represent the hydrodeoxygenation of the major oxygen compound in bio-oil due to their low reactivity in HDO. Results: By assuming the feedstock used was 1% of the total palm shell available in Malaysia, i.e., 2,587 kg h-1 bio-oil, the simulation predicted the production of 226 kg h-1 benzene, 236 kg h-1 cyclohexane and 7 kg h-1 cyclohexene, with the yield of 34, 81 and 3% respectively. The preliminary economic potential was calculated to be positive. It was also observed that hydrogen was the limiting reactant in the hydrogenation reaction. Conclusion/Recommendations: The simulation study indicated positive technical and economic feasibility of hydrodeoxygenation of pyrolytic bio-oil from biomass into benzene and cyclohexane for the transportation fuel industry. This potential can be explored in more details and further findings can promote the prospect of co
A condition for small bootstrap current in three-dimensional toroidal configurations
Energy Technology Data Exchange (ETDEWEB)
Mikhailov, M. I., E-mail: mikhaylov-mi@nrcki.ru [National Russian Research Center Kurchatov Institute (Russian Federation); Nührenberg, J.; Zille, R. [Max-Planck-Institut für Plasmaphysik (Germany)
2016-11-15
It is shown that, if the maximum of the magnetic field strength on a magnetic surface in a threedimensional magnetic confinement configuration with stellarator symmetry constitutes a line that is orthogonal to the field lines and crosses the symmetry line, then the bootstrap current density is smaller compared to that in quasi-axisymmetric (qa) [J. Nührenberg et al., in Proc. of Joint Varenna−Lausanne Int. Workshop on Theory of Fusion Plasmas, Varenna, 1994, p. 3] and quasi-helically (qh) symmetric [J. Nührenberg and R. Zille, Phys. Lett. A 129, 113 (1988)] configurations.
Alavi, Hamid Reza; Rahimipoor, Tahereh
2010-01-01
The goal of this research was to understand the managers' value system, the students' moral development, and their relationship in the high schools and pre-universities of District One in Kerman City. The research method used was descriptive-correlational. The statistical population was composed of high school and pre-university managers and…
Livestock production is significant in the Southern High Plains of the USA and demand is increasing for greater forage dry matter (DM) yield with increased nutritive value. Forage sorghum (FS)[Sorghum bicolor (L.) Moench] is commonly used, although, it is low in crude protein (CP) and high in fiber....
Institute of Scientific and Technical Information of China (English)
王同科
2002-01-01
In this paper, a high accuracy finite volume element method is presented for two-point boundary value problem of second order ordinary differential equation, which differs fromthe high order generalized difference methods. It is proved that the method has optimal order er-ror estimate O(h3) in H1 norm. Finally, two examples show that the method is effective.
Energy Technology Data Exchange (ETDEWEB)
Mills, Andrew [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Wiser, Ryan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
2012-05-18
We estimate the long-run economic value of variable renewable generation with increasing penetration using a unique investment and dispatch model that captures long-run investment decisions while also incorporating detailed operational constraints and hourly time resolution over a full year. High time resolution and the incorporation of operational constraints are important for estimating the economic value of variable generation, as is the use of a modeling framework that accommodates new investment decisions. The model is herein applied with a case study that is loosely based on California in 2030. Increasing amounts of wind, photovoltaics (PV), and concentrating solar power (CSP) with and without thermal energy storage (TES) are added one at a time. The marginal economic value of these renewable energy sources is estimated and then decomposed into capacity value, energy value, day-ahead forecast error cost, and ancillary services. The marginal economic value, as defined here, is primarily based on the combination of avoided capital investment cost and avoided variable fuel and operations and maintenance costs from other power plants in the power system. Though the model only captures a subset of the benefits and costs of renewable energy, it nonetheless provides unique insights into how the value of that subset changes with technology and penetration level. Specifically, in this case study implementation of the model, the marginal economic value of all three solar options is found to exceed the value of a flat-block of power (as well as wind energy) by \\$20--30/MWh at low penetration levels, largely due to the high capacity value of solar at low penetration. Because the value of CSP per unit of energy is found to be high with or without thermal energy storage at low penetration, we find little apparent incremental value to thermal storage at low solar penetration in the present case study analysis. The marginal economic value of PV and CSP without thermal
Directory of Open Access Journals (Sweden)
Dragoş CIMPOIEŞ
2013-01-01
Full Text Available The key-factors of competitiveness of high value added agriculture of the Republic of Moldova and their great importance in increasing the national wealth of the country are analyzed in this paper. The wealth of a country in terms of competitiveness represents the level in which the country, in conditions of the market economy, produces goods and services to satisfy the global market requirements, thus increasing the real income of the citizens of the country. In this context, factors which have an indispensable contribution in increasing the competitiveness of the high value agriculture are: exports, Foreign Direct Investments, innovations, the role of the state institutions, the business climate and others. By the fact how the state contributes by its agricultural policies to attract FDI, to increase exports, to apply innovations and high technologies in the process of obtaining high value agricultural products depends the competitiveness of the agricultural sector of the country
Acquah Henry de-Graft
2012-01-01
This study addresses the problem of model selection in asymmetric price transmission models by combining the use of bootstrap methods with information theoretic selection criteria. Subsequently, parametric bootstrap technique is used to select the best model according to Akaike’s Information Criteria (AIC) and Bayesian Information Criteria (BIC). Bootstrap simulation results indicated that the performances of AIC and BIC are affected by the size of the data...
Directory of Open Access Journals (Sweden)
Orit Karnieli-Miller
2011-10-01
Full Text Available Objective— To understand high-performing frontline employees’ values as reflected in their narratives of day-to-day interactions in a large health care organization. Methods— A total of 150 employees representing various roles within the organization were interviewed and asked to share work-life narratives (WLNs about value-affirming situations (i.e. situations in which they believed their actions to be fully aligned with their values and value-challenging situations (i.e. when their actions or the actions of others were not consistent with their values, using methods based on appreciative inquiry. Results— The analysis revealed 10 broad values. Most of the value-affirming WLNs were about the story-teller and team providing care for the patient/family. Half of the value-challenging WLNs were about the story-teller or a patient and barriers created by the organization, supervisor, or physician. Almost half of these focused on “treating others with disrespect/respect”. Only 15% of the value-challenging WLNs contained a resolution reached by the participants, often leaving them describing unresolved and frequently negative feelings. Conclusions— Appreciative inquiry and thematic analysis methods were found to be an effective tool for understanding the important and sometimes competing role personal and institutional values play in day-to-day work. There is remarkable potential in using WLNs as a way to surface and reinforce shared values and, perhaps more importantly, respectfully to identify and discuss conflicting personal and professional values.
Mo- and V-catalyzed transformation of biomass into high-value chemicals
DEFF Research Database (Denmark)
Nielsen, Lasse Bo; Dethlefsen, Johannes Rytter; Lupp, Daniel;
2014-01-01
The possibility of converting biomass into higher-value chemicals has received increased attention over the last few years. If biomass could be converted into biofules or platform chemicals, then it could constitute a large source of renewable energy and economy for society.......The possibility of converting biomass into higher-value chemicals has received increased attention over the last few years. If biomass could be converted into biofules or platform chemicals, then it could constitute a large source of renewable energy and economy for society....
Takemoto, Seiji; Yamaoka, Kiyoshi; Nishikawa, Makiya; Takakura, Yoshinobu
2006-12-01
A bootstrap method is proposed for assessing statistical histograms of pharmacokinetic parameters (AUC, MRT, CL and V(ss)) from one-point sampling data in animal experiments. A computer program, MOMENT(BS), written in Visual Basic on Microsoft Excel, was developed for the bootstrap calculation and the construction of histograms. MOMENT(BS) was applied to one-point sampling data of the blood concentration of three physiologically active proteins ((111)In labeled Hsp70, Suc(20)-BSA and Suc(40)-BSA) administered in different doses to mice. The histograms of AUC, MRT, CL and V(ss) were close to a normal (Gaussian) distribution with the bootstrap resampling number (200), or more, considering the skewness and kurtosis of the histograms. A good agreement of means and SD was obtained between the bootstrap and Bailer's approaches. The hypothesis test based on the normal distribution clearly demonstrated that the disposition of (111)In-Hsp70 and Suc(20)-BSA was almost independent of dose, whereas that of (111)In-Suc(40)-BSA was definitely dose-dependent. In conclusion, the bootstrap method was found to be an efficient method for assessing the histogram of pharmacokinetic parameters of blood or tissue disposition data by one-point sampling.
Casault, Sebastien; Groen, Aard; Linton, Jonathan D.
2014-01-01
This paper presents work toward improving the efficacy of financial models that describe the unique nature of biotechnology firms. We show that using a 'thick tailed'power law distribution to describe the behavior of the value of biotechnology R&D used in a Real Options Pricing model is
Casault, Sébastien; Groen, Arend J.; Linton, J.D.; Linton, Jonathan
2014-01-01
This paper presents work toward improving the efficacy of financial models that describe the unique nature of biotechnology firms. We show that using a ‘thick tailed’ power law distribution to describe the behavior of the value of biotechnology R&D used in a Real Options Pricing model is
Directory of Open Access Journals (Sweden)
Acquah Henry de-Graft
2012-01-01
Full Text Available This study addresses the problem of model selection in asymmetric price transmission models by combining the use of bootstrap methods with information theoretic selection criteria. Subsequently, parametric bootstrap technique is used to select the best model according to Akaike’s Information Criteria (AIC and Bayesian Information Criteria (BIC. Bootstrap simulation results indicated that the performances of AIC and BIC are affected by the size of the data, the level of asymmetry and the amount of noise in the model used in the application. This study further establishes that the BIC is consistent and outperforms AIC in selecting the correct asymmetric price relationship when the bootstrap sample size is large.
Fungal Enzymes and Yeasts for Conversion of Plant Biomass to Bioenergy and High-Value Products
DEFF Research Database (Denmark)
Lange, Lene
2017-01-01
in the conversion of plant biomass to value-added products. These products provide a basis for substituting fossil-derived fuels, chemicals, and materials, as well as unlocking the biomass potential of the agricultural harvest to yield more food and feed. This article focuses on the mycological basis for the fungal...
Values as Protective Factors against Violent Behavior in Jewish and Arab High Schools in Israel
Knafo, Ariel; Daniel, Ella; Khoury-Kassabri, Mona
2008-01-01
This study tested the hypothesis that values, abstract goals serving as guiding life principles, become relatively important predictors of adolescents' self-reported violent behavior in school environments in which violence is relatively common. The study employed a students-nested-in-schools design. Arab and Jewish adolescents (N = 907, M age =…
The Dynamic between Work Values and Part-Time Work Experiences across the High School Years
Porfeli, Erik J.
2008-01-01
The work value system, its development, and its relationship with work experiences can be modeled as an adaptive control system [Ford, D. H., & Lerner, R. M. (1992). "Developmental systems theory: An integrative approach". Newbury Park, CA: Sage Publications]. This study employed longitudinal data from 1000 participants (Youth Development Study;…
Zou, Yi; Sang, Weiguo; Warren-Thomas, Eleanor; Axmacher, Jan Christoph
2016-01-01
The widespread destruction of mature forests in China has led to massive ecological degradation, counteracted in recent decades by substantial efforts to promote forest plantations and protect secondary forest ecosystems. The value of the resulting forests for biodiversity conservation is widely
Ferraris, Federico; Diamantopoulou, Sofia; Acunzo, Raffaele; Alcidi, Renato
2014-01-01
To evaluate the influence of thickness on the optical properties of two enamel shade composites, one with a high refractive index and one traditional. A medium value enamel shade was selected from the resin composites Enamel Plus HRi (UE2) and Enamel Plus HFO (GE2). Enamel Plus HRi is a high refractive index composite. Samples were fabricated in five different thicknesses: 0.3, 0.5, 1, 1.5 and 2 mm. Three specimens per material and thickness were fabricated. Three measurements per sample, over white, black and dentin composite background were generated with a spectrophotometer (Spectroshade Micro, MHT). Value, chroma, translucency and color differences (ΔE) of the specimens were calculated. RESULTS were analyzed by the Pearson correlation test, ANOVA and a post-hoc Tukey test. Increasing the thickness of the enamel layers decreased the translucency and the chroma of the substrate for both materials tested. For HRi the increase of the thickness resulted in an increase of the value, whereas for HFO it resulted in a reduction of the value. The two composites showed a significant difference in value for each thickness, but not in translucency and chroma. Color difference between them was perceptible in layers equal or higher than 0.5 mm. The high refractive index enamel (HRi) composite exhibits different optical behavior compared to the traditional one (HFO). HRi enamel composite behaves more like natural enamel as by increasing the thickness of the enamel layer, the value also increases.
Zhu, Feng; Feng, Weiyue; Wang, Huajian; Huang, Shaosen; Lv, Yisong; Chen, Yong
2013-01-01
X-ray spectral imaging provides quantitative imaging of trace elements in biological sample with high sensitivity. We propose a novel algorithm to promote the signal-to-noise ratio (SNR) of X-ray spectral images that have low photon counts. Firstly, we estimate the image data area that belongs to the homogeneous parts through confidence interval testing. Then, we apply the Poisson regression through its maximum likelihood estimation on this area to estimate the true photon counts from the Poisson noise corrupted data. Unlike other denoising methods based on regression analysis, we use the bootstrap resampling methods to ensure the accuracy of regression estimation. Finally, we use a robust local nonparametric regression method to estimate the baseline and subsequently subtract it from the X-ray spectral data to further improve the SNR of the data. Experiments on several real samples show that the proposed method performs better than some state-of-the-art approaches to ensure accuracy and precision for quantit...
Institute of Scientific and Technical Information of China (English)
LIN Jing-fu; WANG Yan-hua; JIANG Bao-guo; ZHANG Pei-xun; LI Yan-ying; ZHANG Dian-ying
2010-01-01
Background Sacral nerve injury is a common complication of pelvic or sacral fractures. As the sacral nerve courser within the sacrum and has a complex relationship with the surrounding tissues, different parts of the sacral plexus injury have similar clinical symptoms and signs. Since lack of specific imaging technique in the diagnosis of sacral nerve injury,especially on multi-segment, multi-site, how to determine the preoperative location and extent of the sacral nerve injury accurately becomes a concem of the general orthopaedic and images practitioners. This study was conducted to gain an insight into the overall anatomical features of the sacral nerve (SN) on the same slice in high resolution computed tomography (HRCT) reconstruction and to determine the value of this information for the clinical diagnosis of related diseases.Methods Fifty healthy volunteers and 30 patients (40 sides) with SN lesions confirmed by surgery were scanned using a 16-slice helical CT scanner (Light Speed, GE, USA). Among the patients, 6 with intervertebral disk hernia (6 sides), 8with spinal stenosis (12 sides), 11 with pelvic trauma (14 sides), 4 with pelvic malignancies (6 sides), and 1 with sacral vertebral tuberculosis (2 sides). The SN multiplanar reconstruction was performed using a UNIX-based SCD4.1workstation where the image was set on the same slice. All images were stored in the Digital Imaging and Communications in Medicine format. The display of nerves in different sections was analyzed using a five-graded scale with coordinate curves of each individual score. The overall anatomic features visible on the slice were analyzed and the abnormalities of the lesions were studied.Results The image of the same slice clearly revealed the shape, running direction, thickness, tension and adjacent anatomy of the S1-S4 nerves. The rank of display rates in different sections was: outward-rotated oblique sagittal ＞outward-rotated oblique coronal ＞ oblique coronal plane ＞ coronal
Directory of Open Access Journals (Sweden)
Gu Xun
2007-03-01
Full Text Available Abstract Background Phylogenetically related miRNAs (miRNA families convey important information of the function and evolution of miRNAs. Due to the special sequence features of miRNAs, pair-wise sequence identity between miRNA precursors alone is often inadequate for unequivocally judging the phylogenetic relationships between miRNAs. Most of the current methods for miRNA classification rely heavily on manual inspection and lack measurements of the reliability of the results. Results In this study, we designed an analysis pipeline (the Phylogeny-Bootstrap-Cluster (PBC pipeline to identify miRNA families based on branch stability in the bootstrap trees derived from overlapping genome-wide miRNA sequence sets. We tested the PBC analysis pipeline with the miRNAs from six animal species, H. sapiens, M. musculus, G. gallus, D. rerio, D. melanogaster, and C. elegans. The resulting classification was compared with the miRNA families defined in miRBase. The two classifications were largely consistent. Conclusion The PBC analysis pipeline is an efficient method for classifying large numbers of heterogeneous miRNA sequences. It requires minimum human involvement and provides measurements of the reliability of the classification results.
Analytic Bounds and Emergence of $\\textrm{AdS}_2$ Physics from the Conformal Bootstrap
Mazac, Dalimil
2016-01-01
We study analytically the constraints of the conformal bootstrap on the low-lying spectrum of operators in field theories with global conformal symmetry in one and two spacetime dimensions. We introduce a new class of linear functionals acting on the conformal bootstrap equation. In 1D, we use the new basis to construct extremal functionals leading to the optimal upper bound on the gap above identity in the OPE of two identical primary operators of integer or half-integer scaling dimension. We also prove an upper bound on the twist gap in 2D theories with global conformal symmetry. When the external scaling dimensions are large, our functionals provide a direct point of contact between crossing in a 1D CFT and scattering of massive particles in large $\\textrm{AdS}_2$. In particular, CFT crossing can be shown to imply that appropriate OPE coefficients exhibit an exponential suppression characteristic of massive bound states, and that the 2D flat-space S-matrix should be analytic away from the real axis.
Directory of Open Access Journals (Sweden)
Tásia Hickmann
2015-11-01
Full Text Available In this paper, an iterative forecasting methodology for time series prediction that integrates wavelet de-noising and decomposition with an Artificial Neural Network (ANN and Bootstrap methods is put forward here. Basically, a given time series to be forecasted is initially decomposed into trend and noise (wavelet components by using a wavelet de-noising algorithm. Both trend and noise components are then further decomposed by means of a wavelet decomposition method producing orthonormal Wavelet Components (WCs for each one. Each WC is separately modelled through an ANN in order to provide both in-sample and out-of-sample forecasts. At each time t, the respective forecasts of the WCs of the trend and noise components are simply added to produce the in-sample and out-of-sample forecasts of the underlying time series. Finally, out-of-sample predictive densities are empirically simulated by the Bootstrap sampler and the confidence intervals are then yielded, considering some level of credibility. The proposed methodology, when applied to the well-known Canadian lynx data that exhibit non-linearity and non-Gaussian properties, has outperformed other methods traditionally used to forecast it.
Application of the bootstrap to the analysis of vibration test data
Energy Technology Data Exchange (ETDEWEB)
Hunter, N.F. [Los Alamos National Lab., NM (United States); Paez, T.L. [Sandia National Labs., Albuquerque, NM (United States)
1995-08-01
Structural dynamic testing is concerned with estimation of system properties, including frequency response functions and modal characteristics. These properties are derived from tests on the structure of interest, during which excitations and responses are measured and Fourier techniques are used to reduce the data. The inputs used in a test are frequently radom and excite random responses in the structure of interest. When these random inputs and responses are analyzed they yield estimates of system properties that are random variable and random process realizations. Of course, such estimates of system properties vary randomly from one test to another, but even when deterministic inputs are used to excite a structure, the estimated properties vary from test to test. When test excitations and responses are normally distributed, classical techniques permit us to statistically analyze inputs, responses, and system parameters. However, when the input excitations are non-normal, the system is nonlinear, and/or the property of interest is anything but the simplest, the classical analyses break down. The bootstrap is a technique for the statistical analysis of data that are not necessarily normally distributed. It can be used to statistically analyze any measure of input excitation on response, or any system property, when data are available to make an estimate. It is designed to estimate the standard error, bias, and confidence intervals of parameter estimates. This paper shows how the bootstrap can be applied to the statistical analysis of modal parameters.
Salleh, Mad Ithnin; Ismail, Shariffah Nur Illiana Syed; Habidin, Nurul Fadly; Latip, Nor Azrin Md; Ishak, Salomawati
2014-12-01
The Malaysian government has put a greater attention on enhancing the productivity in Technical Vocational and Educational Training (TVET) sector to increase the development of a skilled workforce by the year 2020. The implementation of National Higher Education Strategic Plan (NHESP) in 2007 led to the changes in Malaysian Polytechnics sector. Thus, the study of efficiency and productivity make it possible to identify scope of improvement for the institution to perform in more efficient and effective manner. This paper aims to identify the efficiency and productivity of 24 polytechnics main campuses as in 2007. This paper applied bootstrapped Malmquist indices to investigate the effects of NHESP on the technical efficiency and changes in productivity in the Malaysian Polytechnics individually from the year 2007-2010. This method enables a more robust analysis of technical efficiency and productivity changes among polytechnics. The bootstrap simulation method is capable to identify whether or not the computed productivity changes are statistically significant. This paper founds that, the overall mean efficiency score demonstrate a significant growth. In addition, the sector as a whole has undergone positive productivity growth at the frontier during the post-NHESP period except in 2009-2010. The increase in productivity growth during post-NHESP was majorly led by technological growth. The empirical results indicated that during the post-NHESP period, the entire polytechnic showed significant TFP growth. This finding shows NHESP contribution towards the positive growth in the overall performance of the Malaysia's polytechnics sector.
Gotelli, Nicholas J.; Dorazio, Robert M.; Ellison, Aaron M.; Grossman, Gary D.
2010-01-01
Quantifying patterns of temporal trends in species assemblages is an important analytical challenge in community ecology. We describe methods of analysis that can be applied to a matrix of counts of individuals that is organized by species (rows) and time-ordered sampling periods (columns). We first developed a bootstrapping procedure to test the null hypothesis of random sampling from a stationary species abundance distribution with temporally varying sampling probabilities. This procedure can be modified to account for undetected species. We next developed a hierarchical model to estimate species-specific trends in abundance while accounting for species-specific probabilities of detection. We analysed two long-term datasets on stream fishes and grassland insects to demonstrate these methods. For both assemblages, the bootstrap test indicated that temporal trends in abundance were more heterogeneous than expected under the null model. We used the hierarchical model to estimate trends in abundance and identified sets of species in each assemblage that were steadily increasing, decreasing or remaining constant in abundance over more than a decade of standardized annual surveys. Our methods of analysis are broadly applicable to other ecological datasets, and they represent an advance over most existing procedures, which do not incorporate effects of incomplete sampling and imperfect detection.
Simultaneous critical values for $t$-tests in very high dimensions
Cao, Hongyuan; 10.3150/10-BEJ272
2011-01-01
This article considers the problem of multiple hypothesis testing using $t$-tests. The observed data are assumed to be independently generated conditional on an underlying and unknown two-state hidden model. We propose an asymptotically valid data-driven procedure to find critical values for rejection regions controlling the $k$-familywise error rate ($k$-FWER), false discovery rate (FDR) and the tail probability of false discovery proportion (FDTP) by using one-sample and two-sample $t$-statistics. We only require a finite fourth moment plus some very general conditions on the mean and variance of the population by virtue of the moderate deviations properties of $t$-statistics. A new consistent estimator for the proportion of alternative hypotheses is developed. Simulation studies support our theoretical results and demonstrate that the power of a multiple testing procedure can be substantially improved by using critical values directly, as opposed to the conventional $p$-value approach. Our method is applie...
Einecke, Sabrina; Bissantz, Nicolai; Clevermann, Fabian; Rhode, Wolfgang
2016-01-01
Astroparticle experiments such as IceCube or MAGIC require a deconvolution of their measured data with respect to the response function of the detector to provide the distributions of interest, e.g. energy spectra. In this paper, appropriate uncertainty limits that also allow to draw conclusions on the geometric shape of the underlying distribution are determined using bootstrap methods, which are frequently applied in statistical applications. Bootstrap is a collective term for resampling methods that can be employed to approximate unknown probability distributions or features thereof. A clear advantage of bootstrap methods is their wide range of applicability. For instance, they yield reliable results, even if the usual normality assumption is violated. The use, meaning and construction of uncertainty limits to any user-specific confidence level in the form of confidence intervals and levels are discussed. The precise algorithms for the implementation of these methods, applicable for any deconvolution algor...
COMPARISON OF VALUE AT RISK APPROACHES ON A STOCK PORTFOLIO
Directory of Open Access Journals (Sweden)
Šime Čorkalo
2011-02-01
Full Text Available Value at risk is risk management tool for measuring and controlling market risks. Through this paper reader will get to know what value at risk is, how it can be calculated, what are the main characteristics, advantages and disadvantages of value at risk. Author compares the main approaches of calculating VaR and implements Variance-Covariance, Historical and Bootstrapping approach on stock portfolio. Finally results of empirical part are compared and presented using histogram.
Chua, Elvis T; Schenk, Peer M
2017-05-21
Microalgae have been studied as biofactories for almost four decades. Yet, even until today, many aspects of microalgae farming and processing are still considered exploratory because of the uniqueness of each microalgal species. Thus, it is important to develop the entire process of microalgae farming: from culturing to harvesting, and down to extracting the desired high-value products. Based on its rapid growth and high oil productivities, Nannochloropsis sp. is of particular interest to many industries for the production of high-value oil containing omega-3 fatty acids, specifically eicosapentaenoic acid (EPA), but also several other products. This review compares the various techniques for induction, harvesting, and extraction of EPA-rich oil and high-value protein explored by academia and industry to develop a multi-product Nannochloropsis biorefinery. Knowledge gaps and opportunities are discussed for culturing and inducing fatty acid biosynthesis, biomass harvesting, and extracting EPA-rich oil and high-value protein from the biomass of Nannochloropsis sp. Copyright © 2017 Elsevier Ltd. All rights reserved.
Institute of Scientific and Technical Information of China (English)
CHAN; Kung-Sik; TONG; Howell; STENSETH; Nils; Chr
2009-01-01
The study of the rodent fluctuations of the North was initiated in its modern form with Elton’s pioneering work.Many scientific studies have been designed to collect yearly rodent abundance data,but the resulting time series are generally subject to at least two "problems":being short and non-linear.We explore the use of the continuous threshold autoregressive(TAR) models for analyzing such data.In the simplest case,the continuous TAR models are additive autoregressive models,being piecewise linear in one lag,and linear in all other lags.The location of the slope change is called the threshold parameter.The continuous TAR models for rodent abundance data can be derived from a general prey-predator model under some simplifying assumptions.The lag in which the threshold is located sheds important insights on the structure of the prey-predator system.We propose to assess the uncertainty on the location of the threshold via a new bootstrap called the nearest block bootstrap(NBB) which combines the methods of moving block bootstrap and the nearest neighbor bootstrap.The NBB assumes an underlying finite-order time-homogeneous Markov process.Essentially,the NBB bootstraps blocks of random block sizes,with each block being drawn from a non-parametric estimate of the future distribution given the realized past bootstrap series.We illustrate the methods by simulations and on a particular rodent abundance time series from Kilpisjrvi,Northern Finland.
Extending Sociological Theorising on High Ability: The Significance of Values and Lived Experience
Mazzoli Smith, Laura
2014-01-01
Sociological work on high ability is framed by social constructionist theorising and/or takes a social justice approach, and hence particular analytical intellectual traditions are foregrounded. Whilst these approaches have contributed the main critique of essentialist psychological understandings of high ability, they can eclipse normative…
Elhussain, O. A.; Abdel-Magid, T. I. M.
2016-08-01
Mono-Crystalline solar cell module is experimentally conducted in Khartoum, Sudan to study the difference between maximum empirical value of peak Watt and maximum value of thermal power produced in field under highly sufficient solar conditions. Field measurements are recorded for incident solar radiation, produced voltage, current and temperature at several time intervals during sun shine period. The thermal power system has been calculated using fundamental principles of heat transfer. The study shows that solar power for considered module could not attain the empirical peak power irrespective to maximum value of direct incident solar radiation and maximum temperature gained. A loss of about 6% of power can be considered as the difference between field measurements and the manufacturer's indicated empirical value. Solar cell exhibits 94% efficiency in comparison with manufacturer's provided data, and is 3'% more efficient in thermal energy production than in electrical power extraction for hot-dry climate conditions.
Formulation of gluten-free flour culinary products of high nutritional value
Directory of Open Access Journals (Sweden)
Y. P. Dombrovskaya
2016-01-01
Full Text Available The article is devoted to the production of gluten-free foods that are necessary for people suffering from this disease as celiac disease. The article reveals the relevance of developing recipes for gluten-free foods, which are not inferior to traditional in many respects. Classic recipes gluten-free bakery products, mainly based on rice, buckwheat, corn flour, which have little nutritional value. In this regard, the current development of technologies and formulations pastry dishes with use of nonconventional vegetable raw materials rich in dietary fibers, proteins and other beneficial substances that improve the biological and nutritional value of these products. The paper describes the formulation of gluten-free muffins, was based on the recipe of the cake "Capital". The main raw material for the new compositions of selected rice flour, and as enriching additives – flax flour and flour from the eggshell. Was conducted baking tests on the basis of which was chosen percentage of the input substances and the assessment of quality of semifinished and finished products. The quality of semi-finished products was evaluated by such indicators as humidity and the microstructure of the test. The quality of finished products was assessed using organoleptic and physical-chemical parameters, the results presented in the tables. Investigated the antioxidant activity of products. Produced sensometrical evaluation of aroma of control and experimental samples. Calculated chemical composition. The content of protein, vitamins, mineral substances in the experimental sample is significantly increased compared to control. Making flour egg shell has achieved the ratio of Ca-Mg-P as close to a perfect 1:0,39:1,53 Replacement of wheat flour with flaxseed and rice flour and the introduction of egg shell improve the amino acid composition of the product. The biological value increased by 2.3%.
Calibration of Threshold Values of Bubble Detections by High Energy Heavy Ions
Institute of Scientific and Technical Information of China (English)
LILi; T.Doke; J.Kikuchi; T.Murakami; GUOShi-lun
2001-01-01
Calibration of five types of bubble detectors made in China Institute of Atomic Energy has been carried out by heavy ion beams of 150 MeV/u 4He, 490 MeV/u 28Si and 500 MeV/u 56Fe from the HIMAC accelerator in the National Institute of Radiological Sciences in Chiba, Japan. Their threshold values are respectively 8.4 (T-15 type), 1 536±232 (T-34 type), 1 628±4 (T-12 type), 2 335±332
Flexible displays as key for high-value and unique automotive design
Isele, Robert
2011-03-01
Within the last few years' car industry changed very fast. Information and Communication became more important and displays are now standard in nearly every car. But this is not the only trend which could be recognized in this industry. CO2 emission, fuel price as well as the increasing traffic inside the Mega Cities initialized a big change in the behavior of the customers. The big battle for the car industry will enter the interior extremely fast, and the premium cars need ore innovative design icons. Flexible Displays are one big step that enables totally different designs and a new value of the driver experience.
Braun, M
1995-01-01
The bootstrap condition is generalized to n reggeized gluons. As a result it is demonstrated that the intercept generated by n reggeized gluons cannot be lower than the one for n=2. Arguments are presented that in the limit N_{c}\\rightarrow\\infty the bootstrap condition reduces the n gluon chain with interacting neighbours to a single BFKL pomeron. In this limit the leading contribution from n gluons corresponds to n/2 non-interacting BFKL pomerons (the n/2 pomeron cut). The sum over n leads to a unitary \\gamma^{\\ast}\\gamma amplitude of the eikonal form.
Bendavid, Ygal; Boeck, Harold; Philippe, Richard
2012-12-01
This paper presents a case study of a hospital operating room that evaluated a Radio-Frequency Identification (RFID)-enabled traceability system for the management of consignment and high value products requiring item level traceability. Results indicate that the traceability system in conjunction with the redesign of replenishment processes facilitates item level traceability, improves financial controls and case costing, upgrades service levels and reduces inventory shrinkage. Other benefits include time saved from non-value-added activities that can be transferred to patient care activities. The solution can be considered (i) as an alternative to RFID-enabled cabinets used in the replenishment of consignment and high value supplies in certain operating rooms, cardiac catheterization laboratories and interventional radiology departments, or (ii) as a complementary solution facilitating the tracking of medical devices removed from RFID-enabled cabinets. In short, the end-to-end traceability of medical products in the healthcare supply chain can be significantly enhanced.
Qu, Wen-Hui; Xu, Yuan-Yuan; Lu, An-Hui; Zhang, Xiang-Qian; Li, Wen-Cui
2015-08-01
In this report, corncob residue, the main by-product in the furfural industry, is used as a precursor to prepare porous carbon by a simple and direct thermal treatment: one-step activation without pre-carbonization. As a consequence, the corncob residue derived porous carbon achieves a high surface area of 1210 m(2) g(-1) after ash-removal. The carbon material has the advantages of low cost and low environmental impact, with a superior electrochemical performance compared to those polymer-based synthetic carbons as electrode material for a supercapacitor. The carbon electrode exhibits a high capacitance of 314 F g(-1) in 6M KOH electrolyte. The corresponding sample also shows a superb cycling stability. Almost no capacitance decay was observed after 100,000 cycles. The excellent electrochemical performance is due to the combination of a high specific surface area with a fraction of mesopores and highly stable structure.