WorldWideScience

Sample records for high bootstrap values

  1. Efficient bootstrap estimates for tail statistics

    Science.gov (United States)

    Breivik, Øyvind; Aarnes, Ole Johan

    2017-03-01

    Bootstrap resamples can be used to investigate the tail of empirical distributions as well as return value estimates from the extremal behaviour of the sample. Specifically, the confidence intervals on return value estimates or bounds on in-sample tail statistics can be obtained using bootstrap techniques. However, non-parametric bootstrapping from the entire sample is expensive. It is shown here that it suffices to bootstrap from a small subset consisting of the highest entries in the sequence to make estimates that are essentially identical to bootstraps from the entire sample. Similarly, bootstrap estimates of confidence intervals of threshold return estimates are found to be well approximated by using a subset consisting of the highest entries. This has practical consequences in fields such as meteorology, oceanography and hydrology where return values are calculated from very large gridded model integrations spanning decades at high temporal resolution or from large ensembles of independent and identically distributed model fields. In such cases the computational savings are substantial.

  2. Aspect Ratio Scaling of Ideal No-wall Stability Limits in High Bootstrap Fraction Tokamak Plasmas

    International Nuclear Information System (INIS)

    Menard, J.E.; Bell, M.G.; Bell, R.E.; Gates, D.A.; Kaye, S.M.; LeBlanc, B.P.; Maingi, R.; Sabbagh, S.A.; Soukhanovskii, V.; Stutman, D.

    2003-01-01

    Recent experiments in the low aspect ratio National Spherical Torus Experiment (NSTX) [M. Ono et al., Nucl. Fusion 40 (2000) 557] have achieved normalized beta values twice the conventional tokamak limit at low internal inductance and with significant bootstrap current. These experimental results have motivated a computational re-examination of the plasma aspect ratio dependence of ideal no-wall magnetohydrodynamic stability limits. These calculations find that the profile-optimized no-wall stability limit in high bootstrap fraction regimes is well described by a nearly aspect ratio invariant normalized beta parameter utilizing the total magnetic field energy density inside the plasma. However, the scaling of normalized beta with internal inductance is found to be strongly aspect ratio dependent at sufficiently low aspect ratio. These calculations and detailed stability analyses of experimental equilibria indicate that the nonrotating plasma no-wall stability limit has been exceeded by as much as 30% in NSTX in a high bootstrap fraction regime

  3. TRANSFORMERLESS OPERATION OF DIII-D WITH HIGH BOOTSTRAP FRACTION

    International Nuclear Information System (INIS)

    POLITZER, PA; HYATT, AW; LUCE, TC; MAHDAVI, MA; MURAKAMI, M; PERKINS, FW; PRATER, R; TURNBULL, AD; CASPER, TA; FERRON, JR; JAYAKUMAR, RJ; LAHAYE, RJ; LAZARUS, EA; PETTY, CC; WADE, MR

    2003-01-01

    OAK-B135 The authors have initiated an experimental program to address some of the questions associated with operation of a tokamak with high bootstrap current fraction under high performance conditions, without assistance from a transformer. In these discharges they have maintained stationary (or slowly improving) conditions for > 2.2 s at β N ∼ β p ∼ 2.8. Significant current overdrive, with dI/dt > 50 kA/s and zero or negative voltage, is sustained for over 0.7 s. The overdrive condition is usually ended with the appearance of MHD activity, which alters the profiles and reduces the bootstrap current. Characteristically these plasmas have 65%-80% bootstrap current, 25%-30% NBCD, and 5%-10% ECCD. Fully noninductive operation is essential for steady-state tokamaks. For efficient operation, the bootstrap current fraction must be close to 100%, allowing for a small additional (∼ 10%) external current drive capability to be used for control. In such plasmas the current and pressure profiles are rightly coupled because J(r) is entirely determined by p(r) (or more accurately by the kinetic profiles). The pressure gradient in turn is determined by transport coefficients which depend on the poloidal field profile

  4. 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...... new resampling method, the local fractional bootstrap, relies on simulating an auxiliary fractional Brownian motion that mimics the fine properties of high frequency differences of the Brownian semistationary process under the null hypothesis. We prove the first order validity of the bootstrap method...... 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...

  5. Progress Toward Steady State Tokamak Operation Exploiting the high bootstrap current fraction regime

    Science.gov (United States)

    Ren, Q.

    2015-11-01

    Recent DIII-D experiments have advanced 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. Fully noninductive plasmas with extremely high values of the poloidal beta, βp >= 4 , have been sustained at βT >= 2 % for long durations with excellent energy confinement quality (H98y,2 >= 1 . 5) and internal transport barriers (ITBs) generated at large minor radius (>= 0 . 6) in all channels (Te, Ti, ne, VTf). Large bootstrap fraction (fBS ~ 80 %) has been obtained with high βp. ITBs have been shown to be compatible with steady state operation. Because of the unusually large ITB radius, normalized pressure is not limited to low βN values by internal ITB-driven modes. βN up to ~4.3 has been obtained by optimizing the plasma-wall distance. The scenario is robust against several variations, including replacing some on-axis with off-axis neutral beam injection (NBI), adding electron cyclotron (EC) heating, and reducing the NBI torque by a factor of 2. This latter observation is particularly promising for extension of the scenario to EAST, where maximum power is obtained with balanced NBI injection, and to a reactor, expected to have low rotation. However, modeling of this regime has provided new challenges to state-of-the-art modeling capabilities: quasilinear models can dramatically underpredict the electron transport, and the Sauter bootstrap current can be insufficient. The analysis shows first-principle NEO is in good agreement with experiments for the bootstrap current calculation and ETG modes with a larger saturated amplitude or EM modes may provide the missing electron transport. Work supported in part by the US DOE under DE-FC02-04ER54698, DE-AC52-07NA

  6. A Phylogeny of the Monocots, as Inferred from rbcL and atpA Sequence Variation, and a Comparison of Methods for Calculating Jackknife and Bootstrap Values

    DEFF Research Database (Denmark)

    Davis, Jerrold I.; Stevenson, Dennis W.; Petersen, Gitte

    2004-01-01

    elements of Xyridaceae. A comparison was conducted of jackknife and bootstrap values, as computed using strict-consensus (SC) and frequency-within-replicates (FWR) approaches. Jackknife values tend to be higher than bootstrap values, and for each of these methods support values obtained with the FWR...

  7. Computerized statistical analysis with bootstrap method in nuclear medicine

    International Nuclear Information System (INIS)

    Zoccarato, O.; Sardina, M.; Zatta, G.; De Agostini, A.; Barbesti, S.; Mana, O.; Tarolo, G.L.

    1988-01-01

    Statistical analysis of data samples involves some hypothesis about the features of data themselves. The accuracy of these hypotheses can influence the results of statistical inference. Among the new methods of computer-aided statistical analysis, the bootstrap method appears to be one of the most powerful, thanks to its ability to reproduce many artificial samples starting from a single original sample and because it works without hypothesis about data distribution. The authors applied the bootstrap method to two typical situation of Nuclear Medicine Department. The determination of the normal range of serum ferritin, as assessed by radioimmunoassay and defined by the mean value ±2 standard deviations, starting from an experimental sample of small dimension, shows an unacceptable lower limit (ferritin plasmatic levels below zero). On the contrary, the results obtained by elaborating 5000 bootstrap samples gives ans interval of values (10.95 ng/ml - 72.87 ng/ml) corresponding to the normal ranges commonly reported. Moreover the authors applied the bootstrap method in evaluating the possible error associated with the correlation coefficient determined between left ventricular ejection fraction (LVEF) values obtained by first pass radionuclide angiocardiography with 99m Tc and 195m Au. The results obtained indicate a high degree of statistical correlation and give the range of r 2 values to be considered acceptable for this type of studies

  8. High beta, Long Pulse, Bootstrap Sustained Scenarios on the National Spherical Torus Experiment (NSTX)

    International Nuclear Information System (INIS)

    Gates, D.A.

    2003-01-01

    Long-pulse, high-beta scenarios have been established on the National Spherical Torus Experiment (NSTX). Beta(sub)t(always equal to 2μ(sub)0· /B 2 (sub)t0) ∼ 35% has been achieved during transient discharges. The machine improvements that lead to these results, including error field reduction and high-temperature bakeout of plasma-facing components are described. The highest Beta(sub)t plasmas have high triangularity (delta = 0.8) and elongation (k = 2.0) at low-aspect ratio A always equal to R/a = 1.4. The strong shaping permits large values of normalized current, I(sub)N(always equal to I(sub)p /(aB(sub)t0)) approximately equal to 6 while maintaining moderate values of q(sub)95 = 4. Long-pulse discharges up to 1 sec in duration have been achieved with substantial bootstrap current. The total noninductive current drive can be as high as 60%, comprised of 50% bootstrap current and ∼10% neutral-beam current drive. The confinement enhancement factor H89P is in excess of 2.7. Beta(sub)N * H(sub)89P approximately or greater than 15 has been maintained for 8 * tau(sub)E ∼ 1.6 * tau(sub)CR, where tau(sub)CR is the relaxation time of the first radial moment of the toroidal current density. The ion temperature for these plasmas is significantly higher than that predicted by neoclassical theory

  9. The bootstrap and Bayesian bootstrap method in assessing bioequivalence

    International Nuclear Information System (INIS)

    Wan Jianping; Zhang Kongsheng; Chen Hui

    2009-01-01

    Parametric method for assessing individual bioequivalence (IBE) may concentrate on the hypothesis that the PK responses are normal. Nonparametric method for evaluating IBE would be bootstrap method. In 2001, the United States Food and Drug Administration (FDA) proposed a draft guidance. The purpose of this article is to evaluate the IBE between test drug and reference drug by bootstrap and Bayesian bootstrap method. We study the power of bootstrap test procedures and the parametric test procedures in FDA (2001). We find that the Bayesian bootstrap method is the most excellent.

  10. 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...

  11. Collisionality dependence of Mercier stability in LHD equilibria with bootstrap currents

    International Nuclear Information System (INIS)

    Ichiguchi, Katsuji.

    1997-02-01

    The Mercier stability of the plasmas carrying bootstrap currents with different plasma collisionality is studied in the Large Helical Device (LHD). In the LHD configuration, the direction of the bootstrap current depends on the collisionality of the plasma through the change in the sign of the geometrical factor. When the beta value is raised by increasing the density of the plasma with a fixed low temperature, the plasma becomes more collisional and the collisionality approaches the plateau regime. In this case, the bootstrap current can flow in the direction so as to decrease the rotational transform. Then, the large Shafranov shift enhances the magnetic well and the magnetic shear, and therefore, the Mercier stability is improved. On the other hand, when the beta value is raised by increasing the temperature of the plasma with a fixed low density, the plasma collisionality becomes reduced to enter the 1/ν collisionality regime and the bootstrap current flows so that the rotational transform should be increased, which is unfavorable for the Mercier stability. Hence, the beta value should be raised by increasing the density rather than the temperature in order to obtain a high beta plasma. (author)

  12. Physics issues of high bootstrap current tokamaks

    International Nuclear Information System (INIS)

    Ozeki, T.; Azumi, M.; Ishii, Y.

    1997-01-01

    Physics issues of a tokamak plasma with a hollow current profile produced by a large bootstrap current are discussed based on experiments in JT-60U. An internal transport barrier for both ions and electrons was obtained just inside the radius of zero magnetic shear in JT-60U. Analysis of the toroidal ITG microinstability by toroidal particle simulation shows that weak and negative shear reduces the toroidal coupling and suppresses the ITG mode. A hard beta limit was observed in JT-60U negative shear experiments. Ideal MHD mode analysis shows that the n = 1 pressure-driven kink mode is a plausible candidate. One of the methods to improve the beta limit against the kink mode is to widen the negative shear region, which can induce a broader pressure profile resulting in a higher beta limit. The TAE mode for the hollow current profile is less unstable than that for the monotonic current profile. The reason is that the continuum gaps near the zero shear region are not aligned when the radius of q min is close to the region of high ∇n e . Finally, a method for stable start-up for a plasma with a hollow current profile is describe, and stable sustainment of a steady-state plasma with high bootstrap current is discussed. (Author)

  13. Extending Bootstrap

    CERN Document Server

    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.

  14. A bootstrap invariance principle for highly nonstationary long memory processes

    OpenAIRE

    Kapetanios, George

    2004-01-01

    This paper presents an invariance principle for highly nonstationary long memory processes, defined as processes with long memory parameter lying in (1, 1.5). This principle provides the tools for showing asymptotic validity of the bootstrap in the context of such processes.

  15. Stationary, high bootstrap fraction plasmas in DIII-D without inductive current control

    International Nuclear Information System (INIS)

    Politzer, P.A.; Hyatt, A.W.; Luce, T.C.; Prater, R.; Turnbull, A.D.; Ferron, J.R.; Greenfield, C.M.; La Haye, R.J.; Petty, C.C.; Perkins, F.W.; Brennan, D.P.; Lazarus, E.A.; Jayakumar, J.; Wade, M.R.

    2005-01-01

    We have initiated an experimental program to address some of the questions associated with operation of a tokamak with high bootstrap current fraction under high performance conditions, without assistance from a transformer. In these discharges stationary (or slowly improving) conditions are maintained for > 3.7 s at β N ∼ β p ≤ 3.3. The achievable current and pressure are limited by a relaxation oscillation, involving growth and collapse of an ITB at ρ ≥ 0.6. The pressure gradually increases and the current profile broadens throughout the discharge. Eventually the plasma reaches a more stable, high confinement (H89P ∼ 3) state. Characteristically these plasmas have 65%-85% bootstrap current, 15%-30% NBCD, and 0%-10% ECCD. (author)

  16. Mobile-first Bootstrap

    CERN Document Server

    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.

  17. Sediment Curve Uncertainty Estimation Using GLUE and Bootstrap Methods

    Directory of Open Access Journals (Sweden)

    aboalhasan fathabadi

    2017-02-01

    Full Text Available Introduction: In order to implement watershed practices to decrease soil erosion effects it needs to estimate output sediment of watershed. Sediment rating curve is used as the most conventional tool to estimate sediment. Regarding to sampling errors and short data, there are some uncertainties in estimating sediment using sediment curve. In this research, bootstrap and the Generalized Likelihood Uncertainty Estimation (GLUE resampling techniques were used to calculate suspended sediment loads by using sediment rating curves. Materials and Methods: The total drainage area of the Sefidrood watershed is about 560000 km2. In this study uncertainty in suspended sediment rating curves was estimated in four stations including Motorkhane, Miyane Tonel Shomare 7, Stor and Glinak constructed on Ayghdamosh, Ghrangho, GHezelOzan and Shahrod rivers, respectively. Data were randomly divided into a training data set (80 percent and a test set (20 percent by Latin hypercube random sampling.Different suspended sediment rating curves equations were fitted to log-transformed values of sediment concentration and discharge and the best fit models were selected based on the lowest root mean square error (RMSE and the highest correlation of coefficient (R2. In the GLUE methodology, different parameter sets were sampled randomly from priori probability distribution. For each station using sampled parameter sets and selected suspended sediment rating curves equation suspended sediment concentration values were estimated several times (100000 to 400000 times. With respect to likelihood function and certain subjective threshold, parameter sets were divided into behavioral and non-behavioral parameter sets. Finally using behavioral parameter sets the 95% confidence intervals for suspended sediment concentration due to parameter uncertainty were estimated. In bootstrap methodology observed suspended sediment and discharge vectors were resampled with replacement B (set to

  18. Stationary high confinement plasmas with large bootstrap current fraction in JT-60U

    International Nuclear Information System (INIS)

    Sakamoto, Y.; Fujita, T.; Ide, S.; Isayama, A.; Takechi, M.; Suzuki, T.; Takenaga, H.; Oyama, N.; Kamada, Y.

    2005-01-01

    This paper reports the results of the progress in stationary discharges with a large bootstrap current fraction in JT-60U towards steady-state tokamak operation. In the weak shear plasma regime, high-β p ELMy H-mode discharges have been optimized under nearly full non-inductive current drive conditions by the large bootstrap current fraction (f BS ∼ 45%) and the beam driven current fraction (f BD ∼ 50%), which was sustained for 5.8 s in the stationary condition. This duration corresponds to ∼26τ E and ∼2.8τ R , which was limited by the pulse length of negative-ion-based neutral beams. The high confinement enhancement factor H 89 ∼ 2.2 (HH 98y2 ∼ 1.0) was obtained and the profiles of current and pressure reached the stationary condition. In the reversed shear plasma regime, a large bootstrap current fraction (f BS ∼ 75%) has been sustained for 7.4 s under nearly full non-inductive current drive conditions. This duration corresponds to ∼16τ E and ∼2.7τ R . The high confinement enhancement factor H 89 ∼ 3.0 (HH 98y2 ∼ 1.7) was also sustained, and the profiles of current and pressure reached the stationary condition. The large bootstrap current and the off-axis beam driven current sustained this reversed q profile. This duration was limited only by the duration of the neutral beam injection

  19. Uncertainty Assessment of Hydrological Frequency Analysis Using Bootstrap Method

    Directory of Open Access Journals (Sweden)

    Yi-Ming Hu

    2013-01-01

    Full Text Available The hydrological frequency analysis (HFA is the foundation for the hydraulic engineering design and water resources management. Hydrological extreme observations or samples are the basis for HFA; the representativeness of a sample series to the population distribution is extremely important for the estimation reliability of the hydrological design value or quantile. However, for most of hydrological extreme data obtained in practical application, the size of the samples is usually small, for example, in China about 40~50 years. Generally, samples with small size cannot completely display the statistical properties of the population distribution, thus leading to uncertainties in the estimation of hydrological design values. In this paper, a new method based on bootstrap is put forward to analyze the impact of sampling uncertainty on the design value. By bootstrap resampling technique, a large number of bootstrap samples are constructed from the original flood extreme observations; the corresponding design value or quantile is estimated for each bootstrap sample, so that the sampling distribution of design value is constructed; based on the sampling distribution, the uncertainty of quantile estimation can be quantified. Compared with the conventional approach, this method provides not only the point estimation of a design value but also quantitative evaluation on uncertainties of the estimation.

  20. Stable equilibria for bootstrap-current-driven low aspect ratio tokamaks

    International Nuclear Information System (INIS)

    Miller, R.L.; Lin-Liu, Y.R.; Turnbull, A.D.; Chan, V.S.; Pearlstein, L.D.; Sauter, O.; Villard, L.

    1997-01-01

    Low aspect ratio tokamaks (LATs) can potentially provide a high ratio of plasma pressure to magnetic pressure β and high plasma current I at a modest size. This opens up the possibility of 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 current, which requires operating at high β p . A high value of the Troyon factor β N and strong shaping is required to allow simultaneous operation at a high-β and high bootstrap fraction. Ideal magnetohydrodynamic stability of a range of equilibria at aspect ratio 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 β N and β are defined in terms of the vacuum toroidal field. Equilibria with β N ≥8 and β∼35%endash 55% exist that are stable to n=∞ ballooning modes. The highest β case is shown to be stable to n=0,1,2,3 kink modes with a conducting wall. copyright 1997 American Institute of Physics

  1. A Simple Counterexample to the Bootstrap

    OpenAIRE

    Donald W.K. Andrews

    1997-01-01

    The bootstrap of the maximum likelihood estimator of the mean of a sample of iid normal random variables with mean mu and variance one is not asymptotically correct to first order when the mean is restricted to be nonnegative. The problem occurs when the true value of the mean mu equals zero. This counterexample to the bootstrap generalizes to a wide variety of estimation problems in which the true parameter may be on the boundary of the parameter space. We provide some alternatives to the bo...

  2. Bootstrap percolation: a renormalisation group approach

    International Nuclear Information System (INIS)

    Branco, N.S.; Santos, Raimundo R. dos; Queiroz, S.L.A. de.

    1984-02-01

    In bootstrap percolation, sites are occupied at random with probability p, but each site is considered active only if at least m of its neighbours are also active. Within an approximate position-space renormalization group framework on a square lattice we obtain the behaviour of the critical concentration p (sub)c and of the critical exponents ν and β for m = 0 (ordinary percolation), 1,2 and 3. We find that the bootstrap percolation problem can be cast into different universality classes, characterized by the values of m. (author) [pt

  3. Bootstrap current of fast ions in neutral beam injection heating

    International Nuclear Information System (INIS)

    Huang Qianhong; Gong Xueyu; Li Xinxia; Yu Jun

    2012-01-01

    The bootstrap current of fast ions produced by neutral beam injection (NBI) is investigated in a large-aspect-ratio tokamak with circular cross-section under specific parameters. The bootstrap current density distribution and the total bootstrap current are reported. In addition, the beam bootstrap current always accompanies the electron return current due to the parallel momentum transfer from fast ions. With the electron return current taken into consideration, the net current density obviously decreases; at the same time, the peak of the current moves towards the central plasma. Numerical results show that the value of the net current depends sensitively not only on the angle of the NBI but also on the ratio of the velocity of fast ions to the critical velocity: the value of the net current is small for neutral beam parallel injection, but increases severalfold for perpendicular injection, and increases with increasing beam energy. (paper)

  4. Bootstrap analysis of designed experiments for reliability improvement with a non-constant scale parameter

    International Nuclear Information System (INIS)

    Wang, Guodong; He, Zhen; Xue, Li; Cui, Qingan; Lv, Shanshan; Zhou, Panpan

    2017-01-01

    Factors which significantly affect product reliability are of great interest to reliability practitioners. This paper proposes a bootstrap-based methodology for identifying significant factors when both location and scale parameters of the smallest extreme value distribution vary over experimental factors. An industrial thermostat experiment is presented, analyzed, and discussed as an illustrative example. The analysis results show that 1) the misspecification of a constant scale parameter may lead to misidentify spurious effects; 2) the important factors identified by different bootstrap methods (i.e., percentile bootstrapping, bias-corrected percentile bootstrapping, and bias-corrected and accelerated percentile bootstrapping) are different; 3) the number of factors affecting 10th percentile lifetime significantly is less than the number of important factors identified at 63.21th percentile. - Highlights: • Product reliability is improved by design of experiments under both scale and location parameters of smallest extreme value distribution vary with experimental factors. • A bootstrap-based methodology is proposed to identify important factors which affect 100pth lifetime percentile significantly. • Bootstrapping confidence intervals associating experimental factors are obtained by using three bootstrap methods (i.e., percentile bootstrapping, bias-corrected percentile bootstrapping, and bias-corrected and accelerated percentile bootstrapping). • The important factors identified by different bootstrap methods are different. • The number of factors affecting 10th percentile significantly is less than the number of important factors identified at 63.21th percentile.

  5. 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

  6. Bootstrapping phylogenies inferred from rearrangement data.

    Science.gov (United States)

    Lin, Yu; Rajan, Vaibhav; Moret, Bernard Me

    2012-08-29

    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. 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. Our method is the first to provide a standard of assessment to match that of the classic phylogenetic bootstrap for aligned sequences. Its support values follow a similar scale and its receiver

  7. Self-consistent ECCD calculations with bootstrap current

    International Nuclear Information System (INIS)

    Decker, J.; Bers, A.; Ram, A. K; Peysson, Y.

    2003-01-01

    To achieve high performance, steady-state operation in tokamaks, it is increasingly important to find the appropriate means for modifying and sustaining the pressure and magnetic shear profiles in the plasma. In such advanced scenarios, especially in the vicinity of internal transport barrier, RF induced currents have to be calculated self-consistently with the bootstrap current, thus taking into account possible synergistic effects resulting from the momentum space distortion of the electron distribution function f e . Since RF waves can cause the distribution of electrons to become non-Maxwellian, the associated changes in parallel diffusion of momentum between trapped and passing particles can be expected to modify the bootstrap current fraction; conversely, the bootstrap current distribution function can enhance the current driven by RF waves. For this purpose, a new, fast and fully implicit solver has been recently developed to carry out computations including new and detailed evaluations of the interactions between bootstrap current (BC) and Electron Cyclotron current drive (ECCD). Moreover, Ohkawa current drive (OKCD) appears to be an efficient method for driving current when the fraction of trapped particles is large. OKCD in the presence of BC is also investigated. Here, results are illustrated around projected tokamak parameters in high performance scenarios of AlcatorC-MOD. It is shown that by increasing n // , the EC wave penetration into the bulk of the electron distribution is greater, and since the resonance extends up to high p // values, this situation is the usual ECCD based on the Fisch-Boozer mechanism concerning passing particles. However, because of the close vicinity of the trapped boundary at r/a=0.7, this process is counterbalanced by the Ohkawa effect, possibly leading to a negative net current. Therefore, by injecting the EC wave in the opposite toroidal direction (n // RF by OKCD may be 70% larger than that of ECCD, with a choice of EC

  8. Bootstrap current of fast ions in neutral beam injection heating

    International Nuclear Information System (INIS)

    Huang Qianhong; Gong Xueyu; Yang Lei; Li Xinxia; Lu Xingqiang; Yu Jun

    2012-01-01

    The bootstrap current of fast ions produced by the neutral beam injection is investigated in a large aspect ratio tokamak with circular cross-section under specific parameters. The bootstrap current density distribution and the total bootstrap current are figured out. In addition, the beam bootstrap current always accompanies the electron return current due to the parallel momentum transfer from fast ions. With the electron return current considered, the net current density obviously decreases due to electron return current, at the same time the peak of current moves towards the centre plasma. Numerical results show that the value of the net current depends sensitively not only on the angle of the neutral beam injection but also on the ratio of the velocity of fast ions to the critical velocity: the value of net current is small for the neutral beam parallel injection but increases multipliedly for perpendicular injection, and increases with beam energy increasing. (authors)

  9. Axisymmetric MHD simulation of ITB crash and following disruption dynamics of Tokamak plasmas with high bootstrap current

    International Nuclear Information System (INIS)

    Takei, Nahoko; Tsutsui, Hiroaki; Tsuji-Iio, Shunji; Shimada, Ryuichi; Nakamura, Yukiharu; Kawano, Yasunori; Ozeki, Takahisa; Tobita, Kenji; Sugihara, Masayoshi

    2004-01-01

    Axisymmetric MHD simulation using the Tokamak Simulation Code demonstrated detailed disruption dynamics triggered by a crash of internal transport barrier in high bootstrap current, high β, reversed shear plasmas. Self-consistent time-evolutions of ohmic current bootstrap current and induced loop voltage profiles inside the disrupting plasma were shown from a view point of disruption characterization and mitigation. In contrast with positive shear plasmas, a particular feature of high bootstrap current reversed shear plasma disruption was computed to be a significant change of plasma current profile, which is normally caused due to resistive diffusion of the electric field induced by the crash of internal transport barrier in a region wider than the internal transport barrier. Discussion based on the simulation results was made on the fastest record of the plasma current quench observed in JT-60U reversed shear plasma disruptions. (author)

  10. 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.

  11. The effective bootstrap

    International Nuclear Information System (INIS)

    Castedo Echeverri, Alejandro; Harling, Benedict von; Serone, Marco

    2016-06-01

    We study the numerical bounds obtained using a conformal-bootstrap method where different points in the plane of conformal cross ratios z and anti z are sampled. In contrast to the most used method based on derivatives evaluated at the symmetric point z= anti 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.

  12. A bootstrap based space-time surveillance model with an application to crime occurrences

    Science.gov (United States)

    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.

  13. Long multiplet bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Cornagliotto, Martina; Lemos, Madalena; Schomerus, Volker [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group

    2017-02-15

    Applications of the bootstrap program to superconformal field theories promise unique new insights into their landscape and could even lead to the discovery of new models. Most existing results of the superconformal bootstrap were obtained form correlation functions of very special fields in short (BPS) representations of the superconformal algebra. Our main goal is to initiate a superconformal bootstrap for long multiplets, one that exploits all constraints from superprimaries and their descendants. To this end, we work out the Casimir equations for four-point correlators of long multiplets of the two-dimensional global N=2 superconformal algebra. After constructing the full set of conformal blocks we discuss two different applications. The first one concerns two-dimensional (2,0) theories. The numerical bootstrap analysis we perform serves a twofold purpose, as a feasibility study of our long multiplet bootstrap and also as an exploration of (2,0) theories. A second line of applications is directed towards four-dimensional N=3 SCFTs. In this context, our results imply a new bound c ≥ (13)/(24) for the central charge of such models. A theory that saturates this bound is not known yet.

  14. Long multiplet bootstrap

    International Nuclear Information System (INIS)

    Cornagliotto, Martina; Lemos, Madalena; Schomerus, Volker

    2017-02-01

    Applications of the bootstrap program to superconformal field theories promise unique new insights into their landscape and could even lead to the discovery of new models. Most existing results of the superconformal bootstrap were obtained form correlation functions of very special fields in short (BPS) representations of the superconformal algebra. Our main goal is to initiate a superconformal bootstrap for long multiplets, one that exploits all constraints from superprimaries and their descendants. To this end, we work out the Casimir equations for four-point correlators of long multiplets of the two-dimensional global N=2 superconformal algebra. After constructing the full set of conformal blocks we discuss two different applications. The first one concerns two-dimensional (2,0) theories. The numerical bootstrap analysis we perform serves a twofold purpose, as a feasibility study of our long multiplet bootstrap and also as an exploration of (2,0) theories. A second line of applications is directed towards four-dimensional N=3 SCFTs. In this context, our results imply a new bound c ≥ (13)/(24) for the central charge of such models. A theory that saturates this bound is not known yet.

  15. Long multiplet bootstrap

    Science.gov (United States)

    Cornagliotto, Martina; Lemos, Madalena; Schomerus, Volker

    2017-10-01

    Applications of the bootstrap program to superconformal field theories promise unique new insights into their landscape and could even lead to the discovery of new models. Most existing results of the superconformal bootstrap were obtained form correlation functions of very special fields in short (BPS) representations of the superconformal algebra. Our main goal is to initiate a superconformal bootstrap for long multiplets, one that exploits all constraints from superprimaries and their descendants. To this end, we work out the Casimir equations for four-point correlators of long multiplets of the two-dimensional global N=2 superconformal algebra. After constructing the full set of conformal blocks we discuss two different applications. The first one concerns two-dimensional (2,0) theories. The numerical bootstrap analysis we perform serves a twofold purpose, as a feasibility study of our long multiplet bootstrap and also as an exploration of (2,0) theories. A second line of applications is directed towards four-dimensional N=3 SCFTs. In this context, our results imply a new bound c≥ 13/24 for the central charge of such models, which we argue cannot be saturated by an interacting SCFT.

  16. The effective bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Castedo Echeverri, Alejandro [SISSA, Trieste (Italy); INFN, Trieste (Italy); Harling, Benedict von [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Serone, Marco [SISSA, Trieste (Italy); INFN, Trieste (Italy); ICTP, Trieste (Italy)

    2016-06-15

    We study the numerical bounds obtained using a conformal-bootstrap method where different points in the plane of conformal cross ratios z and anti z are sampled. In contrast to the most used method based on derivatives evaluated at the symmetric point z= anti 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.

  17. Inference for Local Distributions at High Sampling Frequencies: A Bootstrap Approach

    DEFF Research Database (Denmark)

    Hounyo, Ulrich; Varneskov, Rasmus T.

    of "large" jumps. Our locally dependent wild bootstrap (LDWB) accommodate issues related to the stochastic scale and jumps as well as account for a special block-wise dependence structure induced by sampling errors. We show that the LDWB replicates first and second-order limit theory from the usual...... empirical process and the stochastic scale estimate, respectively, as well as an asymptotic bias. Moreover, we design the LDWB sufficiently general to establish asymptotic equivalence between it and and a nonparametric local block bootstrap, also introduced here, up to second-order distribution theory....... Finally, we introduce LDWB-aided Kolmogorov-Smirnov tests for local Gaussianity as well as local von-Mises statistics, with and without bootstrap inference, and establish their asymptotic validity using the second-order distribution theory. The finite sample performance of CLT and LDWB-aided local...

  18. Bias Correction with Jackknife, Bootstrap, and Taylor Series

    OpenAIRE

    Jiao, Jiantao; Han, Yanjun; Weissman, Tsachy

    2017-01-01

    We analyze the bias correction methods using jackknife, bootstrap, and Taylor series. We focus on the binomial model, and consider the problem of bias correction for estimating $f(p)$, where $f \\in C[0,1]$ is arbitrary. We characterize the supremum norm of the bias of general jackknife and bootstrap estimators for any continuous functions, and demonstrate the in delete-$d$ jackknife, different values of $d$ may lead to drastically different behavior in jackknife. We show that in the binomial ...

  19. 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...... of the series first, the applying the standard wild bootstrap for independent and heteroscedastic distrbuted observations to overlapping tapered blocks in an appropriate way. Its perserves the favorable bias and mean squared error properties of the tapered block bootstrap, which is the state-of-the-art block......-order asymptotic validity of the tapered block bootstrap as well as the wild tapered block bootstrap approximation to the actual distribution of the sample mean is also established when data are assumed to satisfy a near epoch dependent condition. The consistency of the bootstrap variance estimator for the sample...

  20. 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...... context, as recently explained by Mykland and Zhang (2009). Our main contributions are as follows. First, we show that the local Gaussian bootstrap is firstorder consistent when used to estimate the distributions of realized volatility and ealized betas. Second, we show that the local Gaussian bootstrap...... matches accurately the first four cumulants of realized volatility, implying that this method provides third-order refinements. This is in contrast with the wild bootstrap of Gonçalves and Meddahi (2009), which is only second-order correct. Third, we show that the local Gaussian bootstrap is able...

  1. Analytic description of tokamak equilibrium sustained by high fraction bootstrap current

    International Nuclear Information System (INIS)

    Shi Bingren

    2002-01-01

    Recently, to save the current drive power and to obtain more favorable confinement merit for tokamak reactor, large faction bootstrap current sustained equilibrium has attracted great interests both theoretically and experimentally. An powerful expanding technique and the tokamak ordering are used to expand the Grad-Shafranov equation to obtain a series of ordinary differential equations which allow for different sets of input parameters. The fully bootstrap current sustained tokamak equilibria are then solved analytically

  2. Current drive and sustain experiments with the bootstrap current in JT-60

    International Nuclear Information System (INIS)

    Kikuchi, Mitsuru; Azumi, Masafumi; Tani, Keiji; Tsuji, Shunji; Kubo, Hirotaka

    1989-11-01

    The current drive and sustain experiments with the neoclassical bootstrap current are performed in the JT-60 tokamak. It is shown that up to 80% of total plasma current is driven by the bootstrap current in extremely high β p regime (β p = 3.2) and the current drive product I p (bootstrap) n-bar e R p up to 4.4 x 10 19 MAm -2 has been attained with the bootstrap current. The experimental resistive loop voltages are compared with the calculations using the neoclassical resistivity with and without the bootstrap current and the Spitzer resistivity for a wide range of the plasma current (I p = 0.5 -2 MA) and the poloidal beta (β p = 0.1 - 3.2). The calculated resistive loop voltage is consistent with the neoclassical prediction including the bootstrap current. Current sustain with the bootstrap current is tested by terminating the I p feedback control during the high power neutral beam heating. An enhancement of the L/R decay time than those expected from the plasma resistivity with measured T e and Zeff has been confirmed experimentally supporting the large non-inductive current in the plasma and is consistent with the neoclassical prediction. A new technique to calculate the bootstrap current in multi-collisionality regime for finite aspect ratio tokamak has bee developed. The neoclassical bootstrap current is calculated directly through the force balance equations between viscous and friction forces according to the Hirshman-Sigmar theory. The bootstrap current driven by the fast ion component is also included. Ballooning stability of the high β p plasma are analyzed using the current profiles including the bootstrap current. The plasma pressure is close to the ballooning limit in high β p discharges. (author)

  3. Bootstrap currents in stellarators and tokamaks

    International Nuclear Information System (INIS)

    Okamoto, Masao; Nakajima, Noriyoshi.

    1990-09-01

    The remarkable feature of the bootstrap current in stellarators is it's strong dependence on the magnetic field configuration. Neoclassical bootstrap currents in a large helical device of torsatron/heliotron type (L = 2, M = 10, R = 4 m, B = 4 T) is evaluated in the banana (1/ν) and the plateau regime. Various vacuum magnetic field configurations are studied with a view to minimizing the bootstrap current. It is found that in the banana regime, shifting of the magnetic axis and shaping of magnetic surfaces have a remarkable influence on the bootstrap current; a small outward shift of the magnetic axis and vertically elongated magnetic surfaces are favourable for a reduction of the bootstrap current. It is noted, however, that the ripple diffusion in the 1/ν regime has opposite tendency to the bootstrap current; it increases with the outward shift and increases as the plasma cross section is vertically elongated. The comparison will be made between bootstrap currents in stellarators and tokamaks. (author)

  4. Study of the separate exposure method for bootstrap sensitometry on X-ray cine film

    International Nuclear Information System (INIS)

    Matsuda, Eiji; Sanada, Taizo; Hitomi, Go; Kakuba, Koki; Kangai, Yoshiharu; Ishii, Koushi

    1997-01-01

    We developed a new method for bootstrap sensitometry that obtained the characteristic curve from a wide range, with a smaller number of aluminum steps than the conventional bootstrap method. In this method, the density-density curve was obtained from standard and multiplied exposures to the aluminum step wedge and used for bootstrap manipulation. The curve was acquired from two regions separated and added together, e.g., lower and higher photographic density regions. In this study, we evaluated the usefulness of a new cinefluorography method in comparison with N.D. filter sensitometry. The shape of the characteristic curve and the gradient curve obtained with the new method were highly similar to that obtained with N.D. filter sensitometry. Also, the average gradient obtained with the new bootstrap sensitometry method was not significantly different from that obtained by the N.D. filter method. The study revealed that the reliability of the characteristic curve was improved by increasing the measured value used to calculate the density-density curve. This new method was useful for obtaining a characteristic curve with a sufficient density range, and the results suggested that this new method could be applied to specific systems to which the conventional bootstrap method is not applicable. (author)

  5. Bootstrapping pronunciation models

    CSIR Research Space (South Africa)

    Davel, M

    2006-07-01

    Full Text Available -scarce language. During the procedure known as ‘bootstrapping’, a model is improved iteratively via a controlled series of increments, at each stage using the previous model to generate the next. This self- improving circularity distinguishes bootstrapping...-to-phoneme rules (the second representation) can be used to identify possible errors that require re-verification. In contrast, during the bootstrapping of acoustic models for speech recognition, both representations are amenable to automated analysis...

  6. Bootstrapping as a Resource Dependence Management Strategy and its Association with Startup Growth

    OpenAIRE

    T. VANACKER; S. MANIGART; M. MEULEMAN; L. SELS

    2011-01-01

    This paper studies the association between bootstrapping and startup growth. Bootstrapping reduces a startup’s dependence on financial investors, but may create new dependencies. Drawing upon resource dependence theory, we hypothesize that when bootstrapping does not create new strong dependencies it will benefit startup growth, especially when dependence from financial investors is high. However, when bootstrapping creates new strong dependencies it will constrain growth, especially when dep...

  7. Bootstrap consistency for general semiparametric M-estimation

    KAUST Repository

    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.

  8. Estimating negative likelihood ratio confidence when test sensitivity is 100%: A bootstrapping approach.

    Science.gov (United States)

    Marill, Keith A; Chang, Yuchiao; Wong, Kim F; Friedman, Ari B

    2017-08-01

    Objectives Assessing high-sensitivity tests for mortal illness is crucial in emergency and critical care medicine. Estimating the 95% confidence interval (CI) of the likelihood ratio (LR) can be challenging when sample sensitivity is 100%. We aimed to develop, compare, and automate a bootstrapping method to estimate the negative LR CI when sample sensitivity is 100%. Methods The lowest population sensitivity that is most likely to yield sample sensitivity 100% is located using the binomial distribution. Random binomial samples generated using this population sensitivity are then used in the LR bootstrap. A free R program, "bootLR," automates the process. Extensive simulations were performed to determine how often the LR bootstrap and comparator method 95% CIs cover the true population negative LR value. Finally, the 95% CI was compared for theoretical sample sizes and sensitivities approaching and including 100% using: (1) a technique of individual extremes, (2) SAS software based on the technique of Gart and Nam, (3) the Score CI (as implemented in the StatXact, SAS, and R PropCI package), and (4) the bootstrapping technique. Results The bootstrapping approach demonstrates appropriate coverage of the nominal 95% CI over a spectrum of populations and sample sizes. Considering a study of sample size 200 with 100 patients with disease, and specificity 60%, the lowest population sensitivity with median sample sensitivity 100% is 99.31%. When all 100 patients with disease test positive, the negative LR 95% CIs are: individual extremes technique (0,0.073), StatXact (0,0.064), SAS Score method (0,0.057), R PropCI (0,0.062), and bootstrap (0,0.048). Similar trends were observed for other sample sizes. Conclusions When study samples demonstrate 100% sensitivity, available methods may yield inappropriately wide negative LR CIs. An alternative bootstrapping approach and accompanying free open-source R package were developed to yield realistic estimates easily. This

  9. A simulation study on burning profile tailoring of steady state, high bootstrap current tokamaks

    International Nuclear Information System (INIS)

    Nakamura, Y.; Takei, N.; Tobita, K.; Sakamoto, Y.; Fujita, T.; Fukuyama, A.; Jardin, S.C.

    2007-01-01

    From the aspect of fusion burn control in steady state DEMO plant, the significant challenges are to maintain its high power burning state of ∝3-5 GW without burning instability, hitherto well-known as ''thermal stability'', and also to keep its desired burning profile relevant with internal transport barrier (ITB) that generates high bootstrap current. The paper presents a simulation modeling of the burning stability coupled with the self-ignited fusion burn and the structure-formation of the ITB. A self-consistent simulation, including a model for improved core energy confinement, has pointed out that in the high power fusion DEMO plant there is a close, nonlinear interplay between the fusion burnup and the current source of non-inductive, ITB-generated bootstrap current. Consequently, as much distinct from usual plasma controls under simulated burning conditions with lower power (<<1 GW), the selfignited fusion burn at a high power burning state of ∝3-5 GW becomes so strongly selforganized that any of external means except fuelling can not provide the effective control of the stable fusion burn.It is also demonstrated that externally applied, inductive current perturbations can be used to control both the location and strength of ITB in a fully noninductive tokamak discharge. We find that ITB structures formed with broad noninductive current sources such as LHCD are more readily controlled than those formed by localized sources such as ECCD. The physics of the inductive current is well known. Consequently, we believe that the controllability of the ITB is generic, and does not depend on the details of the transport model (as long as they can form an ITB for sufficiently reversed magnetic shear q-profile). Through this external control of the magnetic shear profile, we can maintain the ITB strength that is otherwise prone to deteriorate when the bootstrap current increases. These distinguishing capabilities of inductive current perturbation provide steady

  10. Bootstrapping Relational Affordances of Object Pairs using Transfer

    DEFF Research Database (Denmark)

    Fichtl, Severin; Kraft, Dirk; Krüger, Norbert

    2018-01-01

    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 introduce a novel heuristic, which suggests how a large set of potential affordance categories can be pruned to leave only those categories which are most promising for bootstrapping future affordances. Our results show that both bootstrapping approaches outperform learning without bootstrapping...

  11. Ultrafast Approximation for Phylogenetic Bootstrap

    NARCIS (Netherlands)

    Bui Quang Minh, [No Value; Nguyen, Thi; von Haeseler, Arndt

    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

  12. MPBoot: fast phylogenetic maximum parsimony tree inference and bootstrap approximation.

    Science.gov (United States)

    Hoang, Diep Thi; Vinh, Le Sy; Flouri, Tomáš; Stamatakis, Alexandros; von Haeseler, Arndt; Minh, Bui Quang

    2018-02-02

    The nonparametric bootstrap is widely used to measure the branch support of phylogenetic trees. However, bootstrapping is computationally expensive and remains a bottleneck in phylogenetic analyses. Recently, an ultrafast bootstrap approximation (UFBoot) approach was proposed for maximum likelihood analyses. However, such an approach is still missing for maximum parsimony. To close this gap we present MPBoot, an adaptation and extension of UFBoot to compute branch supports under the maximum parsimony principle. MPBoot works for both uniform and non-uniform cost matrices. Our analyses on biological DNA and protein showed that under uniform cost matrices, MPBoot runs on average 4.7 (DNA) to 7 times (protein data) (range: 1.2-20.7) faster than the standard parsimony bootstrap implemented in PAUP*; but 1.6 (DNA) to 4.1 times (protein data) slower than the standard bootstrap with a fast search routine in TNT (fast-TNT). However, for non-uniform cost matrices MPBoot is 5 (DNA) to 13 times (protein data) (range:0.3-63.9) faster than fast-TNT. We note that MPBoot achieves better scores more frequently than PAUP* and fast-TNT. However, this effect is less pronounced if an intensive but slower search in TNT is invoked. Moreover, experiments on large-scale simulated data show that while both PAUP* and TNT bootstrap estimates are too conservative, MPBoot bootstrap estimates appear more unbiased. MPBoot provides an efficient alternative to the standard maximum parsimony bootstrap procedure. It shows favorable performance in terms of run time, the capability of finding a maximum parsimony tree, and high bootstrap accuracy on simulated as well as empirical data sets. MPBoot is easy-to-use, open-source and available at http://www.cibiv.at/software/mpboot .

  13. Bootstrapping a time series model

    International Nuclear Information System (INIS)

    Son, M.S.

    1984-01-01

    The bootstrap is a methodology for estimating standard errors. The idea is to use a Monte Carlo simulation experiment based on a nonparametric estimate of the error distribution. The main objective of this dissertation was to demonstrate the use of the bootstrap to attach standard errors to coefficient estimates and multi-period forecasts in a second-order autoregressive model fitted by least squares and maximum likelihood estimation. A secondary objective of this article was to present the bootstrap in the context of two econometric equations describing the unemployment rate and individual income tax in the state of Oklahoma. As it turns out, the conventional asymptotic formulae (both the least squares and maximum likelihood estimates) for estimating standard errors appear to overestimate the true standard errors. But there are two problems: 1) the first two observations y 1 and y 2 have been fixed, and 2) the residuals have not been inflated. After these two factors are considered in the trial and bootstrap experiment, both the conventional maximum likelihood and bootstrap estimates of the standard errors appear to be performing quite well. At present, there does not seem to be a good rule of thumb for deciding when the conventional asymptotic formulae will give acceptable results

  14. The bootstrap and edgeworth expansion

    CERN Document Server

    Hall, Peter

    1992-01-01

    This monograph addresses two quite different topics, in the belief that each can shed light on the other. Firstly, it lays the foundation for a particular view of the bootstrap. Secondly, it gives an account of Edgeworth expansion. Chapter 1 is about the bootstrap, witih almost no mention of Edgeworth expansion; Chapter 2 is about Edgeworth expansion, with scarcely a word about the bootstrap; and Chapters 3 and 4 bring these two themes together, using Edgeworth expansion to explore and develop the properites of the bootstrap. The book is aimed a a graduate level audience who has some exposure to the methods of theoretical statistics. However, technical details are delayed until the last chapter (entitled "Details of Mathematical Rogour"), and so a mathematically able reader without knowledge of the rigorous theory of probability will have no trouble understanding the first four-fifths of the book. The book simultaneously fills two gaps in the literature; it provides a very readable graduate level account of t...

  15. Coefficient Omega Bootstrap Confidence Intervals: Nonnormal Distributions

    Science.gov (United States)

    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.…

  16. 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.

  17. The cluster bootstrap consistency in generalized estimating equations

    KAUST Repository

    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.

  18. Considerations on ECFH current drive and bootstrap current for W VII-X

    International Nuclear Information System (INIS)

    Gasparino, U.; Maassberg, H.

    1988-01-01

    Low shear is the characteristic of all proposed Wendelstein VII-X configurations. To avoid low harmonic rational numbers within the rotational transform profile, the current contribution to the rotational transform, Δt a α I/B, should be typically less than 10%. This leads to an upper limit of 50 kA (at B = 2.5 T) for the tolerable net toroidal current. A considerable net toroidal current (bootstrap current) is expected by neoclassical theory in the plateau and the low-collisionality regimes. Both radial transport as well as the bootstrap current densities depend sensitively on the magnetic configuration (see A. Montvai, this workshop). In case of an axisymmetric configuration with dimension and plasma parameters as predicted for the high- regime of WVII-X ( ∼ 5%), this current (∼ 0.5/1 MA) would dominate the rotational transform profile. This requires a reduction of magnitude of the bootstrap current to some % of the value of an equivalent tokamak. This reduction must act on the current profile itself and should not be merely obtained by having two channels of currents of different sign at different radii. Due to the possibility of controlling absorbed power and driven current profiles, electron cyclotron waves are a natural candidate for current profile control. Linear calculations show the possibility to drive a counteracting current with a profile similar to the bootstrap one. For ∼ 5% conditions, however, the optimium current drive efficiency (η ∼ 10 kA per MW) is far too low to make ECF-current drive suitable

  19. 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.

  20. Efficient bootstrap with weakly dependent processes

    NARCIS (Netherlands)

    Bravo, Francesco; Crudu, Federico

    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

  1. Scalar-vector bootstrap

    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.

  2. Transport Barriers in Bootstrap Driven Tokamaks

    Science.gov (United States)

    Staebler, Gary

    2017-10-01

    Maximizing the bootstrap current in a tokamak, so that it drives a high fraction of the total current, reduces the external power required to drive current by other means. Improved energy confinement, relative to empirical scaling laws, enables a reactor to more fully take advantage of the bootstrap driven tokamak. Experiments have demonstrated improved energy confinement due to the spontaneous formation of an internal transport barrier in high bootstrap fraction discharges. Gyrokinetic analysis, and quasilinear predictive modeling, demonstrates that the observed transport barrier is due to the suppression of turbulence primarily due to the large Shafranov shift. ExB velocity shear does not play a significant role in the transport barrier due to the high safety factor. It will be shown, that the Shafranov shift can produce a bifurcation to improved confinement in regions of positive magnetic shear or a continuous reduction in transport for weak or negative magnetic shear. Operation at high safety factor lowers the pressure gradient threshold for the Shafranov shift driven barrier formation. The ion energy transport is reduced to neoclassical and electron energy and particle transport is reduced, but still turbulent, within the barrier. Deeper into the plasma, very large levels of electron transport are observed. The observed electron temperature profile is shown to be close to the threshold for the electron temperature gradient (ETG) mode. A large ETG driven energy transport is qualitatively consistent with recent multi-scale gyrokinetic simulations showing that reducing the ion scale turbulence can lead to large increase in the electron scale transport. A new saturation model for the quasilinear TGLF transport code, that fits these multi-scale gyrokinetic simulations, can match the data if the impact of zonal flow mixing on the ETG modes is reduced at high safety factor. This work was supported by the U.S. Department of Energy under DE-FG02-95ER54309 and DE-FC02

  3. 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.

  4. Bootstrap consistency for general semiparametric M-estimation

    KAUST Repository

    Cheng, Guang; Huang, Jianhua Z.

    2010-01-01

    , 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.

  5. Transport barriers in bootstrap-driven tokamaks

    Science.gov (United States)

    Staebler, G. M.; Garofalo, A. M.; Pan, C.; McClenaghan, J.; Van Zeeland, M. A.; Lao, L. L.

    2018-05-01

    Experiments have demonstrated improved energy confinement due to the spontaneous formation of an internal transport barrier in high bootstrap fraction discharges. Gyrokinetic analysis, and quasilinear predictive modeling, demonstrates that the observed transport barrier is caused by the suppression of turbulence primarily from the large Shafranov shift. It is shown that the Shafranov shift can produce a bifurcation to improved confinement in regions of positive magnetic shear or a continuous reduction in transport for weak or negative magnetic shear. Operation at high safety factor lowers the pressure gradient threshold for the Shafranov shift-driven barrier formation. Two self-organized states of the internal and edge transport barrier are observed. It is shown that these two states are controlled by the interaction of the bootstrap current with magnetic shear, and the kinetic ballooning mode instability boundary. Election scale energy transport is predicted to be dominant in the inner 60% of the profile. Evidence is presented that energetic particle-driven instabilities could be playing a role in the thermal energy transport in this region.

  6. Uncertainty Estimation using Bootstrapped Kriging Predictions for Precipitation Isoscapes

    Science.gov (United States)

    Ma, C.; Bowen, G. J.; Vander Zanden, H.; Wunder, M.

    2017-12-01

    Isoscapes are spatial models representing the distribution of stable isotope values across landscapes. Isoscapes of hydrogen and oxygen in precipitation are now widely used in a diversity of fields, including geology, biology, hydrology, and atmospheric science. To generate isoscapes, geostatistical methods are typically applied to extend predictions from limited data measurements. Kriging is a popular method in isoscape modeling, but quantifying the uncertainty associated with the resulting isoscapes is challenging. Applications that use precipitation isoscapes to determine sample origin require estimation of uncertainty. Here we present a simple bootstrap method (SBM) to estimate the mean and uncertainty of the krigged isoscape and compare these results with a generalized bootstrap method (GBM) applied in previous studies. We used hydrogen isotopic data from IsoMAP to explore these two approaches for estimating uncertainty. We conducted 10 simulations for each bootstrap method and found that SBM results in more kriging predictions (9/10) compared to GBM (4/10). Prediction from SBM was closer to the original prediction generated without bootstrapping and had less variance than GBM. SBM was tested on different datasets from IsoMAP with different numbers of observation sites. We determined that predictions from the datasets with fewer than 40 observation sites using SBM were more variable than the original prediction. The approaches we used for estimating uncertainty will be compiled in an R package that is under development. We expect that these robust estimates of precipitation isoscape uncertainty can be applied in diagnosing the origin of samples ranging from various type of waters to migratory animals, food products, and humans.

  7. Comparison of Bootstrap Confidence Intervals Using Monte Carlo Simulations

    Directory of Open Access Journals (Sweden)

    Roberto S. Flowers-Cano

    2018-02-01

    Full Text Available Design of hydraulic works requires the estimation of design hydrological events by statistical inference from a probability distribution. Using Monte Carlo simulations, we compared coverage of confidence intervals constructed with four bootstrap techniques: percentile bootstrap (BP, bias-corrected bootstrap (BC, accelerated bias-corrected bootstrap (BCA and a modified version of the standard bootstrap (MSB. Different simulation scenarios were analyzed. In some cases, the mother distribution function was fit to the random samples that were generated. In other cases, a distribution function different to the mother distribution was fit to the samples. When the fitted distribution had three parameters, and was the same as the mother distribution, the intervals constructed with the four techniques had acceptable coverage. However, the bootstrap techniques failed in several of the cases in which the fitted distribution had two parameters.

  8. Bootstrap essentials

    CERN Document Server

    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.

  9. The economics of bootstrapping space industries - Development of an analytic computer model

    Science.gov (United States)

    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.

  10. Effect of bootstrap current on MHD equilibrium beta limit in heliotron plasmas

    International Nuclear Information System (INIS)

    Watanabe, K.Y.

    2001-01-01

    The effect of bootstrap current on the beta limit of MHD equilibria is studied systematically by an iterative calculation of MHD equilibrium and the consistent bootstrap current in high beta heliotron plasmas. The LHD machine is treated as a standard configuration heliotron with an L=2 planar axis. The effects of vacuum magnetic configurations, pressure profiles and the vertical field control method are studied. The equilibrium beta limit with consistent bootstrap current is quite sensitive to the magnetic axis location for finite beta, compared with the currentless cases. For a vacuum configuration with the magnetic axis shifted inwards in the torus, even in the high beta regimes, the bootstrap current flows to increase the rotational transform, leading to an increase in the equilibrium beta limit. On the contrary, for a vacuum configuration with the magnetic axis shifted outwards in the torus, even in the low beta regimes, the bootstrap current flows so as to reduce the rotational transform; therefore, there is an acceleration of the Shafranov shift increase as beta increases, leading to a decrease in the equilibrium beta limit. The pressure profiles and vertical field control methods influence the equilibrium beta limit through the location of the magnetic axis for finite beta. These characteristics are independent of both device parameters, such as magnetic field strength, and device size in the low collisional regime. (author)

  11. Generalized Bootstrap Method for Assessment of Uncertainty in Semivariogram Inference

    Science.gov (United States)

    Olea, R.A.; Pardo-Iguzquiza, E.

    2011-01-01

    The semivariogram and its related function, the covariance, play a central role in classical geostatistics for modeling the average continuity of spatially correlated attributes. Whereas all methods are formulated in terms of the true semivariogram, in practice what can be used are estimated semivariograms and models based on samples. A generalized form of the bootstrap method to properly model spatially correlated data is used to advance knowledge about the reliability of empirical semivariograms and semivariogram models based on a single sample. Among several methods available to generate spatially correlated resamples, we selected a method based on the LU decomposition and used several examples to illustrate the approach. The first one is a synthetic, isotropic, exhaustive sample following a normal distribution, the second example is also a synthetic but following a non-Gaussian random field, and a third empirical sample consists of actual raingauge measurements. Results show wider confidence intervals than those found previously by others with inadequate application of the bootstrap. Also, even for the Gaussian example, distributions for estimated semivariogram values and model parameters are positively skewed. In this sense, bootstrap percentile confidence intervals, which are not centered around the empirical semivariogram and do not require distributional assumptions for its construction, provide an achieved coverage similar to the nominal coverage. The latter cannot be achieved by symmetrical confidence intervals based on the standard error, regardless if the standard error is estimated from a parametric equation or from bootstrap. ?? 2010 International Association for Mathematical Geosciences.

  12. 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...... (1989). In many cases validity of bootstrap-based inference procedures is found to depend crucially on whether the bandwidth sequence satisfies a particular (asymptotic linearity) condition. An exception to this rule occurs for inference procedures involving a studentized estimator employing a "robust...

  13. The Bootstrap Current and Neutral Beam Current Drive in DIII-D

    International Nuclear Information System (INIS)

    Politzer, P.A.

    2005-01-01

    Noninductive current drive is an essential part of the implementation of the DIII-D Advanced Tokamak program. For an efficient steady-state tokamak reactor, the plasma must provide close to 100% bootstrap fraction (f bs ). For noninductive operation of DIII-D, current drive by injection of energetic neutral beams [neutral beam current drive (NBCD)] is also important. DIII-D experiments have reached ∼80% bootstrap current in stationary discharges without inductive current drive. The remaining current is ∼20% NBCD. This is achieved at β N [approximately equal to] β p > 3, but at relatively high q 95 (∼10). In lower q 95 Advanced Tokamak plasmas, f bs ∼ 0.6 has been reached in essentially noninductive plasmas. The phenomenology of high β p and β N plasmas without current control is being studied. These plasmas display a relaxation oscillation involving repetitive formation and collapse of an internal transport barrier. The frequency and severity of these events increase with increasing β, limiting the achievable average β and causing modulation of the total current as well as the pressure. Modeling of both bootstrap and NBCD currents is based on neoclassical theory. Measurements of the total bootstrap and NBCD current agree with calculations. A recent experiment based on the evolution of the transient voltage profile after an L-H transition shows that the more recent bootstrap current models accurately describe the plasma behavior. The profiles and the parametric dependences of the local neutral beam-driven current density have not yet been compared with theory

  14. arXiv Bootstrapping the QCD soft anomalous dimension

    CERN Document Server

    Almelid, Øyvind; Gardi, Einan; McLeod, Andrew; White, Chris D.

    2017-09-18

    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.

  15. A Bootstrap Based Measure Robust to the Choice of Normalization Methods for Detecting Rhythmic Features in High Dimensional Data.

    Science.gov (United States)

    Larriba, Yolanda; Rueda, Cristina; Fernández, Miguel A; Peddada, Shyamal D

    2018-01-01

    Motivation: Gene-expression data obtained from high throughput technologies are subject to various sources of noise and accordingly the raw data are pre-processed before formally analyzed. Normalization of the data is a key pre-processing step, since it removes systematic variations across arrays. There are numerous normalization methods available in the literature. Based on our experience, in the context of oscillatory systems, such as cell-cycle, circadian clock, etc., the choice of the normalization method may substantially impact the determination of a gene to be rhythmic. Thus rhythmicity of a gene can purely be an artifact of how the data were normalized. Since the determination of rhythmic genes is an important component of modern toxicological and pharmacological studies, it is important to determine truly rhythmic genes that are robust to the choice of a normalization method. Results: In this paper we introduce a rhythmicity measure and a bootstrap methodology to detect rhythmic genes in an oscillatory system. Although the proposed methodology can be used for any high-throughput gene expression data, in this paper we illustrate the proposed methodology using several publicly available circadian clock microarray gene-expression datasets. We demonstrate that the choice of normalization method has very little effect on the proposed methodology. Specifically, for any pair of normalization methods considered in this paper, the resulting values of the rhythmicity measure are highly correlated. Thus it suggests that the proposed measure is robust to the choice of a normalization method. Consequently, the rhythmicity of a gene is potentially not a mere artifact of the normalization method used. Lastly, as demonstrated in the paper, the proposed bootstrap methodology can also be used for simulating data for genes participating in an oscillatory system using a reference dataset. Availability: A user friendly code implemented in R language can be downloaded from http://www.eio.uva.es/~miguel/robustdetectionprocedure.html.

  16. RANDOM QUADRATIC-FORMS AND THE BOOTSTRAP FOR U-STATISTICS

    NARCIS (Netherlands)

    DEHLING, H; MIKOSCH, T

    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,

  17. 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 inconsistent. Our method restores consistency of the nonparametric bootstrap by altering the shape of the criterion function defining the estimator whose distribution we seek to approximate. This modification leads to a generic and easy-to-implement resampling method for inference that is conceptually distinct...... from other available distributional approximations based on some form of modified bootstrap. We offer simulation evidence showcasing the performance of our inference method in finite samples. An extension of our methodology to general M-estimation problems is also discussed....

  18. Assessing the Uncertainty in QUANTEC's Dose–Response Relation of Lung and Spinal Cord With a Bootstrap Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Wedenberg, Minna, E-mail: minna.wedenberg@raysearchlabs.com

    2013-11-15

    Purpose: To apply a statistical bootstrap analysis to assess the uncertainty in the dose–response relation for the endpoints pneumonitis and myelopathy reported in the QUANTEC review. Methods and Materials: The bootstrap method assesses the uncertainty of the estimated population-based dose-response relation due to sample variability, which reflects the uncertainty due to limited numbers of patients in the studies. A large number of bootstrap replicates of the original incidence data were produced by random sampling with replacement. The analysis requires only the dose, the number of patients, and the number of occurrences of the studied endpoint, for each study. Two dose–response models, a Poisson-based model and the Lyman model, were fitted to each bootstrap replicate using maximum likelihood. Results: The bootstrap analysis generates a family of curves representing the range of plausible dose–response relations, and the 95% bootstrap confidence intervals give an estimated upper and lower toxicity risk. The curve families for the 2 dose–response models overlap for doses included in the studies at hand but diverge beyond that, with the Lyman model suggesting a steeper slope. The resulting distributions of the model parameters indicate correlation and non-Gaussian distribution. For both data sets, the likelihood of the observed data was higher for the Lyman model in >90% of the bootstrap replicates. Conclusions: The bootstrap method provides a statistical analysis of the uncertainty in the estimated dose–response relation for myelopathy and pneumonitis. It suggests likely values of model parameter values, their confidence intervals, and how they interrelate for each model. Finally, it can be used to evaluate to what extent data supports one model over another. For both data sets considered here, the Lyman model was preferred over the Poisson-based model.

  19. The cluster bootstrap consistency in generalized estimating equations

    KAUST Repository

    Cheng, Guang; Yu, Zhuqing; Huang, Jianhua Z.

    2013-01-01

    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

  20. 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...

  1. 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...

  2. 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...

  3. Bootstrapping language acquisition.

    Science.gov (United States)

    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.

  4. Bootstrapping non-commutative gauge theories from L∞ algebras

    Science.gov (United States)

    Blumenhagen, Ralph; Brunner, Ilka; Kupriyanov, Vladislav; Lüst, Dieter

    2018-05-01

    Non-commutative gauge theories with a non-constant NC-parameter are investigated. As a novel approach, we propose that such theories should admit an underlying L∞ algebra, that governs not only the action of the symmetries but also the dynamics of the theory. Our approach is well motivated from string theory. We recall that such field theories arise in the context of branes in WZW models and briefly comment on its appearance for integrable deformations of AdS5 sigma models. For the SU(2) WZW model, we show that the earlier proposed matrix valued gauge theory on the fuzzy 2-sphere can be bootstrapped via an L∞ algebra. We then apply this approach to the construction of non-commutative Chern-Simons and Yang-Mills theories on flat and curved backgrounds with non-constant NC-structure. More concretely, up to the second order, we demonstrate how derivative and curvature corrections to the equations of motion can be bootstrapped in an algebraic way from the L∞ algebra. The appearance of a non-trivial A∞ algebra is discussed, as well.

  5. 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.

  6. Bootstrapping the (A1, A2) Argyres-Douglas theory

    Science.gov (United States)

    Cornagliotto, Martina; Lemos, Madalena; Liendo, Pedro

    2018-03-01

    We apply bootstrap techniques in order to constrain the CFT data of the ( A 1 , A 2) Argyres-Douglas theory, which is arguably the simplest of the Argyres-Douglas models. We study the four-point function of its single Coulomb branch chiral ring generator and put numerical bounds on the low-lying spectrum of the theory. Of particular interest is an infinite family of semi-short multiplets labeled by the spin ℓ. Although the conformal dimensions of these multiplets are protected, their three-point functions are not. Using the numerical bootstrap we impose rigorous upper and lower bounds on their values for spins up to ℓ = 20. Through a recently obtained inversion formula, we also estimate them for sufficiently large ℓ, and the comparison of both approaches shows consistent results. We also give a rigorous numerical range for the OPE coefficient of the next operator in the chiral ring, and estimates for the dimension of the first R-symmetry neutral non-protected multiplet for small spin.

  7. Combined RF current drive and bootstrap current in tokamaks

    International Nuclear Information System (INIS)

    Schultz, S. D.; Bers, A.; Ram, A. K.

    1999-01-01

    By calculating radio frequency current drive (RFCD) and the bootstrap current in a consistent kinetic manner, we find synergistic effects in the total noninductive current density in tokamaks [1]. We include quasilinear diffusion in the Drift Kinetic Equation (DKE) in order to generalize neoclassical theory to highly non-Maxwellian electron distributions due to RFCD. The parallel plasma current is evaluated numerically with the help of the FASTEP Fokker-Planck code [2]. Current drive efficiency is found to be significantly affected by neoclassical effects, even in cases where only circulating electrons interact with the waves. Predictions of the current drive efficiency are made for lower hybrid and electron cyclotron wave current drive scenarios in the presence of bootstrap current

  8. Using the bootstrap in a multivariadte data problem: An example

    International Nuclear Information System (INIS)

    Glosup, J.G.; Axelrod, M.C.

    1995-01-01

    The use of the bootstrap in the multivariate version of the paired t-test is considered and demonstrated through an example. The problem of interest involves comparing two different techniques for measuring the chemical constituents of an sample item. The bootstrap is used to form an empirical significance level for Hotelling's one-sample T-squared statistic. The bootstrap was selected to determine empirical significance levels because the implicit assumption of multivariate normality in the classic Hotelling's one-sample test night not hold. The results of both the classic and bootstrap test are presented and contrasted

  9. Bootstrap Determination of the Co-Integration Rank in Heteroskedastic VAR Models

    DEFF Research Database (Denmark)

    Cavaliere, G.; Rahbek, Anders; Taylor, A.M.R.

    2014-01-01

    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 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......-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...

  10. The nonparametric bootstrap for the current status model

    NARCIS (Netherlands)

    Groeneboom, P.; Hendrickx, K.

    2017-01-01

    It has been proved that direct bootstrapping of the nonparametric maximum likelihood estimator (MLE) of the distribution function in the current status model leads to inconsistent confidence intervals. We show that bootstrapping of functionals of the MLE can however be used to produce valid

  11. Bootstrapping N=2 chiral correlators

    Science.gov (United States)

    Lemos, Madalena; Liendo, Pedro

    2016-01-01

    We apply the numerical bootstrap program to chiral operators in four-dimensional 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 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.

  12. Bootstrapping N=2 chiral correlators

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Madalena [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany); Liendo, Pedro [Humboldt-Univ. Berlin (Germany). IMIP

    2015-12-15

    We apply the numerical bootstrap program to chiral operators in four-dimensional 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 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.

  13. Bootstrapping N=2 chiral correlators

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Madalena [DESY Hamburg, Theory Group,Notkestrasse 85, D-22607 Hamburg (Germany); Liendo, Pedro [IMIP, Humboldt-Universität zu Berlin, IRIS Adlershof,Zum Großen Windkanal 6, 12489 Berlin (Germany)

    2016-01-07

    We apply the numerical bootstrap program to chiral operators in four-dimensional 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 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.

  14. 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}.

  15. Nonparametric bootstrap analysis with applications to demographic effects in demand functions.

    Science.gov (United States)

    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

  16. Bootstrap inference when using multiple imputation.

    Science.gov (United States)

    Schomaker, Michael; Heumann, Christian

    2018-04-16

    Many modern estimators require bootstrapping to calculate confidence intervals because either no analytic standard error is available or the distribution of the parameter of interest is nonsymmetric. It remains however unclear how to obtain valid bootstrap inference when dealing with multiple imputation to address missing data. We present 4 methods that are intuitively appealing, easy to implement, and combine bootstrap estimation with multiple imputation. We show that 3 of the 4 approaches yield valid inference, but that the performance of the methods varies with respect to the number of imputed data sets and the extent of missingness. Simulation studies reveal the behavior of our approaches in finite samples. A topical analysis from HIV treatment research, which determines the optimal timing of antiretroviral treatment initiation in young children, demonstrates the practical implications of the 4 methods in a sophisticated and realistic setting. This analysis suffers from missing data and uses the g-formula for inference, a method for which no standard errors are available. Copyright © 2018 John Wiley & Sons, Ltd.

  17. Learning web development with Bootstrap and AngularJS

    CERN Document Server

    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.

  18. Bootstrap and fast wave current drive for tokamak reactors

    International Nuclear Information System (INIS)

    Ehst, D.A.

    1991-09-01

    Using the multi-species neoclassical treatment of Hirshman and Sigmar we study steady state bootstrap equilibria with seed currents provided by low frequency (ICRF) fast waves and with additional surface current density driven by lower hybrid waves. This study applies to reactor plasmas of arbitrary aspect ratio. IN one limit the bootstrap component can supply nearly the total equilibrium current with minimal driving power ( o = 18 MA needs P FW = 15 MW, P LH = 75 MW). A computational survey of bootstrap fraction and current drive efficiency is presented. 11 refs., 8 figs

  19. On a generalized bootstrap principle

    International Nuclear Information System (INIS)

    Corrigan, E.; Sasaki, R.; Dorey, P.E.

    1993-01-01

    The S-matrices for non-simply-laced affine Toda field theories are considered in the context of a generalized bootstrap principle. The S-matrices, and in particular their poles, depend on a parameter whose range lies between the Coxeter numbers of dual pairs of the corresponding non-simply-laced algebras. It is proposed that only odd order poles in the physical strip with positive coefficients throughout this range should participate in the bootstrap. All other singularities have an explanation in principle in terms of a generalized Coleman-Thun mechanism. Besides the S-matrices introduced by Delius, Grisaru and Zanon, the missing case (F 4 (1) , e 6 (2) ), is also considered and provides many interesting examples of pole generation. (author)

  20. Conference on Bootstrapping and Related Techniques

    CERN Document Server

    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.

  1. Bootstrapping pre-averaged realized volatility under market microstructure noise

    DEFF Research Database (Denmark)

    Hounyo, Ulrich; Goncalves, Sílvia; Meddahi, Nour

    The main contribution of this paper is to propose a bootstrap method for inference on integrated volatility based on the pre-averaging approach of Jacod et al. (2009), where the pre-averaging is done over all possible overlapping blocks of consecutive observations. The overlapping nature of the pre......-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......)) is valid only when volatility is constant. The failure of the blocks of blocks bootstrap is due to the heterogeneity of the squared pre-averaged returns when volatility is stochastic. To preserve both the dependence and the heterogeneity of squared pre-averaged returns, we propose a novel procedure...

  2. A NONPARAMETRIC HYPOTHESIS TEST VIA THE BOOTSTRAP RESAMPLING

    OpenAIRE

    Temel, Tugrul T.

    2001-01-01

    This paper adapts an already existing nonparametric hypothesis test to the bootstrap framework. The test utilizes the nonparametric kernel regression method to estimate a measure of distance between the models stated under the null hypothesis. The bootstraped version of the test allows to approximate errors involved in the asymptotic hypothesis test. The paper also develops a Mathematica Code for the test algorithm.

  3. The PIT-trap-A "model-free" bootstrap procedure for inference about regression models with discrete, multivariate responses.

    Science.gov (United States)

    Warton, David I; Thibaut, Loïc; Wang, Yi Alice

    2017-01-01

    Bootstrap methods are widely used in statistics, and bootstrapping of residuals can be especially useful in the regression context. However, difficulties are encountered extending residual resampling to regression settings where residuals are not identically distributed (thus not amenable to bootstrapping)-common examples including logistic or Poisson regression and generalizations to handle clustered or multivariate data, such as generalised estimating equations. We propose a bootstrap method based on probability integral transform (PIT-) residuals, which we call the PIT-trap, which assumes data come from some marginal distribution F of known parametric form. This method can be understood as a type of "model-free bootstrap", adapted to the problem of discrete and highly multivariate data. PIT-residuals have the key property that they are (asymptotically) pivotal. The PIT-trap thus inherits the key property, not afforded by any other residual resampling approach, that the marginal distribution of data can be preserved under PIT-trapping. This in turn enables the derivation of some standard bootstrap properties, including second-order correctness of pivotal PIT-trap test statistics. In multivariate data, bootstrapping rows of PIT-residuals affords the property that it preserves correlation in data without the need for it to be modelled, a key point of difference as compared to a parametric bootstrap. The proposed method is illustrated on an example involving multivariate abundance data in ecology, and demonstrated via simulation to have improved properties as compared to competing resampling methods.

  4. 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...

  5. EBW-Bootstrap Current Synergy in the National Spherical Torus Experiment (NSTX)

    International Nuclear Information System (INIS)

    Harvey, R.W.; Taylor, G.

    2005-01-01

    Current driven by electron Bernstein waves (EBW) and by the electron bootstrap effect are calculated separately and concurrently with a kinetic code, to determine the degree of synergy between them. A target β = 40% NSTX plasma is examined. A simple bootstrap model in the CQL3D Fokker-Planck code is used in these studies: the transiting electron distributions are connected in velocity-space at the trapped-passing boundary to trapped-electron distributions which are displaced radially by a half-banana width outwards/inwards for the co-/counter-passing regions. This model agrees well with standard bootstrap current calculations, over the outer 60% of the plasma radius. Relatively small synergy net bootstrap current is obtained for EBW power up to 4 MW. Locally, bootstrap current density increases in proportion to increased plasma pressure, and this effect can significantly affect the radial profile of driven current

  6. Bootstrapping pronunciation dictionaries: practical issues

    CSIR Research Space (South Africa)

    Davel, MH

    2005-09-01

    Full Text Available Bootstrapping techniques are an efficient way to develop electronic pronunciation dictionaries, but require fast system response to be practical for medium-to-large lexicons. In addition, user errors are inevitable during this process...

  7. 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.

  8. Integrated modeling of plasma ramp-up in DIII-D ITER-like and high bootstrap current scenario discharges

    Science.gov (United States)

    Wu, M. Q.; Pan, C. K.; Chan, V. S.; Li, G. Q.; Garofalo, A. M.; Jian, X.; Liu, L.; Ren, Q. L.; Chen, J. L.; Gao, X.; Gong, X. Z.; Ding, S. Y.; Qian, J. P.; Cfetr Physics Team

    2018-04-01

    Time-dependent integrated modeling of DIII-D ITER-like and high bootstrap current plasma ramp-up discharges has been performed with the equilibrium code EFIT, and the transport codes TGYRO and ONETWO. Electron and ion temperature profiles are simulated by TGYRO with the TGLF (SAT0 or VX model) turbulent and NEO neoclassical transport models. The VX model is a new empirical extension of the TGLF turbulent model [Jian et al., Nucl. Fusion 58, 016011 (2018)], which captures the physics of multi-scale interaction between low-k and high-k turbulence from nonlinear gyro-kinetic simulation. This model is demonstrated to accurately model low Ip discharges from the EAST tokamak. Time evolution of the plasma current density profile is simulated by ONETWO with the experimental current ramp-up rate. The general trend of the predicted evolution of the current density profile is consistent with that obtained from the equilibrium reconstruction with Motional Stark effect constraints. The predicted evolution of βN , li , and βP also agrees well with the experiments. For the ITER-like cases, the predicted electron and ion temperature profiles using TGLF_Sat0 agree closely with the experimental measured profiles, and are demonstrably better than other proposed transport models. For the high bootstrap current case, the predicted electron and ion temperature profiles perform better in the VX model. It is found that the SAT0 model works well at high IP (>0.76 MA) while the VX model covers a wider range of plasma current ( IP > 0.6 MA). The results reported in this paper suggest that the developed integrated modeling could be a candidate for ITER and CFETR ramp-up engineering design modeling.

  9. Hadronic equation of state in the statistical bootstrap model and linear graph theory

    International Nuclear Information System (INIS)

    Fre, P.; Page, R.

    1976-01-01

    Taking a statistical mechanical point og view, the statistical bootstrap model is discussed and, from a critical analysis of the bootstrap volume comcept, it is reached a physical ipothesis, which leads immediately to the hadronic equation of state provided by the bootstrap integral equation. In this context also the connection between the statistical bootstrap and the linear graph theory approach to interacting gases is analyzed

  10. Solution of the statistical bootstrap with Bose statistics

    International Nuclear Information System (INIS)

    Engels, J.; Fabricius, K.; Schilling, K.

    1977-01-01

    A brief and transparent way to introduce Bose statistics into the statistical bootstrap of Hagedorn and Frautschi is presented. The resulting bootstrap equation is solved by a cluster expansion for the grand canonical partition function. The shift of the ultimate temperature due to Bose statistics is determined through an iteration process. We discuss two-particle spectra of the decaying fireball (with given mass) as obtained from its grand microcanonical level density

  11. 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...

  12. Time evolution of the bootstrap current profile in LHD plasmas

    International Nuclear Information System (INIS)

    Nakamura, Yuji; Kawaoto, K.; Watanabe, K.Y.

    2008-10-01

    The direction of the bootstrap current is inverted in the outward shifted plasmas of the Large Helical Device (LHD). In order to verify the reliability of the theoretical models of the bootstrap current in helical plasmas, the rotational transform profiles are observed by the Motional Stark Effect measurement in the bootstrap current carrying plasmas of the LHD, and they are compared with the numerical simulations of the toroidal current profile including the bootstrap current. Since the toroidal current profile is not in the steady state in these plasmas, taking care of the inversely induced component of the toroidal current and finite duration of the resistive diffusion of the toroidal current are important in the numerical simulations. Reasonable agreement can be obtained between the rotational transform profiles measured in the experiments and those calculated in the numerical simulations. (author)

  13. 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.

  14. Energy confinement of tokamak plasma with consideration of bootstrap current effect

    International Nuclear Information System (INIS)

    Yuan Ying; Gao Qingdi

    1992-01-01

    Based on the η i -mode induced anomalous transport model of Lee et al., the energy confinement of tokamak plasmas with auxiliary heating is investigated with consideration of bootstrap current effect. The results indicate that energy confinement time increases with plasma current and tokamak major radius, and decreases with heating power, toroidal field and minor radius. This is in reasonable agreement with the Kaye-Goldston empirical scaling law. Bootstrap current always leads to an improvement of energy confinement and the contraction of inversion radius. When γ, the ratio between bootstrap current and total plasma current, is small, the part of energy confinement time contributed from bootstrap current will be about γ/2

  15. ELM phenomenon as an interaction between bootstrap-current driven peeling modes and pressure-driven ballooning modes

    International Nuclear Information System (INIS)

    Saarelma, S.; Kurki-Suonio, T.; Guenter, S.; Zehrfeld, H.-P.

    2000-01-01

    An ELMy ASDEX Upgrade plasma equilibrium is reconstructed taking into account the bootstrap current. The peeling mode stability of the equilibrium is numerically analysed using the GATO [1] code, and it is found that the bootstrap current can drive the plasma peeling mode unstable. A high-n ballooning mode stability analysis of the equilibria revealed that, while destabilizing the peeling modes, the bootstrap current has a stabilizing effect on the ballooning modes. A combination of these two instabilities is a possible explanation for the type I ELM phenomenon. A triangularity scan showed that increasing triangularity stabilizes the peeling modes and can produce ELM-free periods observed in the experiments. (author)

  16. Statistical bootstrap approach to hadronic matter and multiparticle reactions

    International Nuclear Information System (INIS)

    Ilgenfritz, E.M.; Kripfganz, J.; Moehring, H.J.

    1977-01-01

    The authors present the main ideas behind the statistical bootstrap model and recent developments within this model related to the description of fireball cascade decay. Mathematical methods developed in this model might be useful in other phenomenological schemes of strong interaction physics; they are described in detail. The present status of applications of the model to various hadronic reactions is discussed. When discussing the relations of the statistical bootstrap model to other models of hadron physics the authors point out possibly fruitful analogies and dynamical mechanisms which are modelled by the bootstrap dynamics under definite conditions. This offers interpretations for the critical temperature typical for the model and indicates futher fields of application. (author)

  17. Bootstrapping in language resource generation

    CSIR Research Space (South Africa)

    Davel, MH

    2003-11-01

    Full Text Available by Schultz [1]. Bootstrapping approaches are applicable to various lan- guage resource development tasks, specifically where an au- tomated mechanism can be defined to convert between vari- ous representations of the data considered. In the above ex...

  18. Bootstrap prediction and Bayesian prediction under misspecified models

    OpenAIRE

    Fushiki, Tadayoshi

    2005-01-01

    We consider a statistical prediction problem under misspecified models. In a sense, Bayesian prediction is an optimal prediction method when an assumed model is true. Bootstrap prediction is obtained by applying Breiman's `bagging' method to a plug-in prediction. Bootstrap prediction can be considered to be an approximation to the Bayesian prediction under the assumption that the model is true. However, in applications, there are frequently deviations from the assumed model. In this paper, bo...

  19. Optical Flow of Small Objects Using Wavelets, Bootstrap Methods, and Synthetic Discriminant Filters

    National Research Council Canada - National Science Library

    Hewer, Gary

    1997-01-01

    ...) targets in highly cluttered and noisy environments. In this paper; we present a novel wavelet detection algorithm which incorporates adaptive CFAR detection statistics using the bootstrap method...

  20. On transport and the bootstrap current in toroidal plasmas

    International Nuclear Information System (INIS)

    Connor, J.W.; Taylor, J.B.

    1987-01-01

    The recently reported observation of the bootstrap current in a tokamak plasma highlights the problem of reconciling this neoclassical effect with the anomalous (i.e., non-neoclassical) electron thermal transport. This Comment reviews the bootstrap current and considers the implications of a self-consistent modification of neoclassical theory based on an enhanced electron-electron interaction. (author)

  1. Modelos alternativos de simulación Bootstrap

    OpenAIRE

    Pino Mejías, Rafael

    1992-01-01

    Se describen las características fundamentales de los métodos Bootstrap. Se analizan diversas problemáticas que presentan tales métodos, por lo que se presentan dos métodos alternativos dentro del método Bootstrap basado en la simulación de muestras (método II de Efron). En el primero se presenta un método, que a partir de un estudio de las propiedades algebraicas y estadísticas del conjunto de posibles muestras, utiliza un criterio probabilístico para detectar muestras "outliers". En el segu...

  2. Bootstrap embedding: An internally consistent fragment-based method

    Energy Technology Data Exchange (ETDEWEB)

    Welborn, Matthew; Tsuchimochi, Takashi; Van Voorhis, Troy [Department of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, Massachusetts 02139 (United States)

    2016-08-21

    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.

  3. 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...... 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....

  4. Bootstrapped efficiency measures of oil blocks in Angola

    International Nuclear Information System (INIS)

    Barros, C.P.; Assaf, A.

    2009-01-01

    This paper investigates the technical efficiency of Angola oil blocks over the period 2002-2007. A double bootstrap data envelopment analysis (DEA) model is adopted composed in the first stage of a DEA-variable returns to scale (VRS) model and then followed in the second stage by a bootstrapped truncated regression. Results showed that on average, the technical efficiency has fluctuated over the period of study, but deep and ultradeep oil blocks have generally maintained a consistent efficiency level. Policy implications are derived.

  5. BootGraph: probabilistic fiber tractography using bootstrap algorithms and graph theory.

    Science.gov (United States)

    Vorburger, Robert S; Reischauer, Carolin; Boesiger, Peter

    2013-02-01

    Bootstrap methods have recently been introduced to diffusion-weighted magnetic resonance imaging to estimate the measurement uncertainty of ensuing diffusion parameters directly from the acquired data without the necessity to assume a noise model. These methods have been previously combined with deterministic streamline tractography algorithms to allow for the assessment of connection probabilities in the human brain. Thereby, the local noise induced disturbance in the diffusion data is accumulated additively due to the incremental progression of streamline tractography algorithms. Graph based approaches have been proposed to overcome this drawback of streamline techniques. For this reason, the bootstrap method is in the present work incorporated into a graph setup to derive a new probabilistic fiber tractography method, called BootGraph. The acquired data set is thereby converted into a weighted, undirected graph by defining a vertex in each voxel and edges between adjacent vertices. By means of the cone of uncertainty, which is derived using the wild bootstrap, a weight is thereafter assigned to each edge. Two path finding algorithms are subsequently applied to derive connection probabilities. While the first algorithm is based on the shortest path approach, the second algorithm takes all existing paths between two vertices into consideration. Tracking results are compared to an established algorithm based on the bootstrap method in combination with streamline fiber tractography and to another graph based algorithm. The BootGraph shows a very good performance in crossing situations with respect to false negatives and permits incorporating additional constraints, such as a curvature threshold. By inheriting the advantages of the bootstrap method and graph theory, the BootGraph method provides a computationally efficient and flexible probabilistic tractography setup to compute connection probability maps and virtual fiber pathways without the drawbacks of

  6. Accidental symmetries and the conformal bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Chester, Shai M.; Giombi, Simone; Iliesiu, Luca V.; Klebanov, Igor R.; Pufu, Silviu S.; Yacoby, Ran [Joseph Henry Laboratories, Princeton University,Princeton, NJ 08544 (United States)

    2016-01-19

    We study an 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{sub 1}X∑{sub i}Z{sub i}{sup 2}+g{sub 2}X{sup 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{sub 2} flowing to zero. This example is special in that the existence of an infrared fixed point with g{sub 1},g{sub 2}≠0, which does not exhibit symmetry enhancement, does not generally lead to any obvious unitarity violations or other inconsistencies. We do show, however, that the F-theorem excludes the models with g{sub 1},g{sub 2}≠0 for N>5. The conformal bootstrap provides a stronger constraint and excludes such models for N>2. We provide evidence that the g{sub 2}=0 models, which have the enhanced O(N)×U(1) symmetry, come close to saturating the bootstrap bounds. We extend our analysis to fractional dimensions where we can motivate the nonexistence of the g{sub 1},g{sub 2}≠0 models by studying them perturbatively in the 4−ϵ expansion.

  7. The efficiency of different search strategies in estimating parsimony jackknife, bootstrap, and Bremer support

    Directory of Open Access Journals (Sweden)

    Müller Kai F

    2005-10-01

    Full Text Available Abstract Background For parsimony analyses, the most common way to estimate confidence is by resampling plans (nonparametric bootstrap, jackknife, and Bremer support (Decay indices. The recent literature reveals that parameter settings that are quite commonly employed are not those that are recommended by theoretical considerations and by previous empirical studies. The optimal search strategy to be applied during resampling was previously addressed solely via standard search strategies available in PAUP*. The question of a compromise between search extensiveness and improved support accuracy for Bremer support received even less attention. A set of experiments was conducted on different datasets to find an empirical cut-off point at which increased search extensiveness does not significantly change Bremer support and jackknife or bootstrap proportions any more. Results For the number of replicates needed for accurate estimates of support in resampling plans, a diagram is provided that helps to address the question whether apparently different support values really differ significantly. It is shown that the use of random addition cycles and parsimony ratchet iterations during bootstrapping does not translate into higher support, nor does any extension of the search extensiveness beyond the rather moderate effort of TBR (tree bisection and reconnection branch swapping plus saving one tree per replicate. Instead, in case of very large matrices, saving more than one shortest tree per iteration and using a strict consensus tree of these yields decreased support compared to saving only one tree. This can be interpreted as a small risk of overestimating support but should be more than compensated by other factors that counteract an enhanced type I error. With regard to Bremer support, a rule of thumb can be derived stating that not much is gained relative to the surplus computational effort when searches are extended beyond 20 ratchet iterations per

  8. Bootstrapping N=3 superconformal theories

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Madalena; Liendo, Pedro [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Meneghelli, Carlo [Stony Brook Univ., Stony Brook, NY (United States). Simons Center for Geometry and Physics; Mitev, Vladimir [Mainz Univ. (Germany). PRISMA Cluster of Excellence

    2016-12-15

    We initiate the bootstrap program for N=3 superconformal field theories (SCFTs) in four dimensions. The problem is considered from two fronts: the protected subsector described by a 2d chiral algebra, and crossing symmetry for half-BPS operators whose superconformal primaries parametrize the Coulomb branch of N=3 theories. With the goal of describing a protected subsector of a family of =3 SCFTs, we propose a new 2d chiral algebra with super Virasoro symmetry that depends on an arbitrary parameter, identified with the central charge of the theory. Turning to the crossing equations, we work out the superconformal block expansion and apply standard numerical bootstrap techniques in order to constrain the CFT data. We obtain bounds valid for any theory but also, thanks to input from the chiral algebra results, we are able to exclude solutions with N=4 supersymmetry, allowing us to zoom in on a specific N=3 SCFT.

  9. Bootstrapping N=3 superconformal theories

    Energy Technology Data Exchange (ETDEWEB)

    Lemos, Madalena; Liendo, Pedro [DESY Hamburg, Theory Group,Notkestrasse 85, D-22607 Hamburg (Germany); Meneghelli, Carlo [Simons Center for Geometry and Physics,Stony Brook University, Stony Brook, NY 11794-3636 (United States); Mitev, Vladimir [PRISMA Cluster of Excellence, Institut für Physik,JGU Mainz, Staudingerweg 7, 55128 Mainz (Germany)

    2017-04-06

    We initiate the bootstrap program for N=3 superconformal field theories (SCFTs) in four dimensions. The problem is considered from two fronts: the protected subsector described by a 2d chiral algebra, and crossing symmetry for half-BPS operators whose superconformal primaries parametrize the Coulomb branch of N=3 theories. With the goal of describing a protected subsector of a family of N=3 SCFTs, we propose a new 2d chiral algebra with super Virasoro symmetry that depends on an arbitrary parameter, identified with the central charge of the theory. Turning to the crossing equations, we work out the superconformal block expansion and apply standard numerical bootstrap techniques in order to constrain the CFT data. We obtain bounds valid for any theory but also, thanks to input from the chiral algebra results, we are able to exclude solutions with N=4 supersymmetry, allowing us to zoom in on a specific N=3 SCFT.

  10. The $(2,0)$ superconformal bootstrap

    CERN Document Server

    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...

  11. Heptagons from the Steinmann cluster bootstrap

    International Nuclear Information System (INIS)

    Dixon, Lance J.; Drummond, James; Papathanasiou, Georgios

    2017-01-01

    We reformulate the heptagon cluster bootstrap to take advantage of the Steinmann relations, which require certain double discontinuities of any amplitude to vanish. These constraints vastly reduce the number of functions needed to bootstrap seven-point amplitudes in planar N = 4 supersymmetric Yang-Mills theory, making higher-loop contributions to these amplitudes more computationally accessible. In particular, dual superconformal symmetry and well-defined collinear limits suffice to determine uniquely the symbols of the three-loop NMHV and four-loop MHV seven-point amplitudes. We also show that at three loops, relaxing the dual superconformal Q̄ relations and imposing dihedral symmetry (and for NMHV the absence of spurious poles) leaves only a single ambiguity in the heptagon amplitudes. These results point to a strong tension between the collinear properties of the amplitudes and the Steinmann relations.

  12. On a linear method in bootstrap confidence intervals

    Directory of Open Access Journals (Sweden)

    Andrea Pallini

    2007-10-01

    Full Text Available A linear method for the construction of asymptotic bootstrap confidence intervals is proposed. We approximate asymptotically pivotal and non-pivotal quantities, which are smooth functions of means of n independent and identically distributed random variables, by using a sum of n independent smooth functions of the same analytical form. Errors are of order Op(n-3/2 and Op(n-2, respectively. The linear method allows a straightforward approximation of bootstrap cumulants, by considering the set of n independent smooth functions as an original random sample to be resampled with replacement.

  13. Comparison of bootstrap current and plasma conductivity models applied in a self-consistent equilibrium calculation for Tokamak plasmas

    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)

  14. Neoclassical bootstrap current and transport in optimized stellarator configurations

    International Nuclear Information System (INIS)

    Maassberg, H.; Lotz, W.; Nuehrenberg, J.

    1993-01-01

    The neoclassical bootstrap current properties of optimized stellarators are analyzed in the relevant mean-free-path regimes and compared with the neoclassical transport properties. Two methods---global Monte Carlo simulation [Phys. Fluids 31, 2984 (1988)], and local analysis with the drift kinetic equation solver code [Phys. Fluids B 1, 563 (1989)]---are employed and good agreement is obtained. Full consistency with the elimination of the bootstrap current and favorable neoclassical transport are found

  15. 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...... when it is non-negligible....

  16. A bootstrap estimation scheme for chemical compositional data with nondetects

    Science.gov (United States)

    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. 

  17. Conformal bootstrap: non-perturbative QFT's under siege

    CERN Multimedia

    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.

  18. Heptagons from the Steinmann cluster bootstrap

    International Nuclear Information System (INIS)

    Dixon, Lance J.; McLeod, Andrew J.; Drummond, James; Harrington, Thomas; Spradlin, Marcus; Papathanasiou, Georgios; Stanford Univ., CA

    2016-12-01

    We reformulate the heptagon cluster bootstrap to take advantage of the Steinmann relations, which require certain double discontinuities of any amplitude to vanish. These constraints vastly reduce the number of functions needed to bootstrap seven-point amplitudes in planar N=4 supersymmetric Yang-Mills theory, making higher-loop contributions to these amplitudes more computationally accessible. In particular, dual superconformal symmetry and well-defined collinear limits suffice to determine uniquely the symbols of the three-loop NMHV and four-loop MHV seven-point amplitudes. We also show that at three loops, relaxing the dual superconformal (anti Q) relations and imposing dihedral symmetry (and for NMHV the absence of spurious poles) leaves only a single ambiguity in the heptagon amplitudes. These results point to a strong tension between the collinear properties of the amplitudes and the Steinmann relations.

  19. Heptagons from the Steinmann cluster bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Dixon, Lance J.; McLeod, Andrew J. [Stanford Univ., CA (United States). SLAC National Accelerator Lab.; Drummond, James [Southampton Univ. (United Kingdom). School of Physics and Astronomy; Harrington, Thomas; Spradlin, Marcus [Brown Univ., Providence, RI (United States). Dept. of Physics; Papathanasiou, Georgios [Deutsches Elektronen-Synchrotron (DESY), Hamburg (Germany). Theory Group; Stanford Univ., CA (United States). SLAC National Accelerator Lab.

    2016-12-15

    We reformulate the heptagon cluster bootstrap to take advantage of the Steinmann relations, which require certain double discontinuities of any amplitude to vanish. These constraints vastly reduce the number of functions needed to bootstrap seven-point amplitudes in planar N=4 supersymmetric Yang-Mills theory, making higher-loop contributions to these amplitudes more computationally accessible. In particular, dual superconformal symmetry and well-defined collinear limits suffice to determine uniquely the symbols of the three-loop NMHV and four-loop MHV seven-point amplitudes. We also show that at three loops, relaxing the dual superconformal (anti Q) relations and imposing dihedral symmetry (and for NMHV the absence of spurious poles) leaves only a single ambiguity in the heptagon amplitudes. These results point to a strong tension between the collinear properties of the amplitudes and the Steinmann relations.

  20. A framework for bootstrapping morphological decomposition

    CSIR Research Space (South Africa)

    Joubert, LJ

    2004-11-01

    Full Text Available The need for a bootstrapping approach to the morphological decomposition of words in agglutinative languages such as isiZulu is motivated, and the complexities of such an approach are described. The authors then introduce a generic framework which...

  1. Point Set Denoising Using Bootstrap-Based Radial Basis Function.

    Science.gov (United States)

    Liew, Khang Jie; 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.

  2. Bootstrap Prediction Intervals in Non-Parametric Regression with Applications to Anomaly Detection

    Science.gov (United States)

    Kumar, Sricharan; Srivistava, Ashok N.

    2012-01-01

    Prediction intervals provide a measure of the probable interval in which the outputs of a regression model can be expected to occur. Subsequently, these prediction intervals can be used to determine if the observed output is anomalous or not, conditioned on the input. In this paper, a procedure for determining prediction intervals for outputs of nonparametric regression models using bootstrap methods is proposed. Bootstrap methods allow for a non-parametric approach to computing prediction intervals with no specific assumptions about the sampling distribution of the noise or the data. The asymptotic fidelity of the proposed prediction intervals is theoretically proved. Subsequently, the validity of the bootstrap based prediction intervals is illustrated via simulations. Finally, the bootstrap prediction intervals are applied to the problem of anomaly detection on aviation data.

  3. Use of Monte Carlo Bootstrap Method in the Analysis of Sample Sufficiency for Radioecological Data

    International Nuclear Information System (INIS)

    Silva, A. N. C. da; Amaral, R. S.; Araujo Santos Jr, J.; Wilson Vieira, J.; Lima, F. R. de A.

    2015-01-01

    There are operational difficulties in obtaining samples for radioecological studies. Population data may no longer be available during the study and obtaining new samples may not be possible. These problems do the researcher sometimes work with a small number of data. Therefore, it is difficult to know whether the number of samples will be sufficient to estimate the desired parameter. Hence, it is critical do the analysis of sample sufficiency. It is not interesting uses the classical methods of statistic to analyze sample sufficiency in Radioecology, because naturally occurring radionuclides have a random distribution in soil, usually arise outliers and gaps with missing values. The present work was developed aiming to apply the Monte Carlo Bootstrap method in the analysis of sample sufficiency with quantitative estimation of a single variable such as specific activity of a natural radioisotope present in plants. The pseudo population was a small sample with 14 values of specific activity of 226 Ra in forage palm (Opuntia spp.). Using the R software was performed a computational procedure to calculate the number of the sample values. The re sampling process with replacement took the 14 values of original sample and produced 10,000 bootstrap samples for each round. Then was calculated the estimated average θ for samples with 2, 5, 8, 11 and 14 values randomly selected. The results showed that if the researcher work with only 11 sample values, the average parameter will be within a confidence interval with 90% probability . (Author)

  4. 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.

  5. Direct measurement of fast transients by using boot-strapped waveform averaging

    Science.gov (United States)

    Olsson, Mattias; Edman, Fredrik; Karki, Khadga Jung

    2018-03-01

    An approximation to coherent sampling, also known as boot-strapped waveform averaging, is presented. The method uses digital cavities to determine the condition for coherent sampling. It can be used to increase the effective sampling rate of a repetitive signal and the signal to noise ratio simultaneously. The method is demonstrated by using it to directly measure the fluorescence lifetime from Rhodamine 6G by digitizing the signal from a fast avalanche photodiode. The obtained lifetime of 4.0 ns is in agreement with the known values.

  6. Bootstrapping: Una teoría explicativa del cambio conceptual Bootstrapping: A theory for conceptual change

    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.

  7. 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.

  8. Lightweight CoAP-Based Bootstrapping Service for the Internet of Things.

    Science.gov (United States)

    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.

  9. Electron Bernstein wave-bootstrap current synergy in the National Spherical Torus Experiment

    International Nuclear Information System (INIS)

    Harvey, R.W.; Taylor, G.

    2005-01-01

    Current driven by electron Bernstein waves (EBW) and by the electron bootstrap effect are calculated separately and concurrently with a kinetic code to determine the degree of synergy between them. A target β=40% NSTX [M. Ono, S. Kaye, M. Peng et al., Proceedings of the 17th IAEA Fusion Energy Conference, edited by M. Spak (IAEA, Vienna, Austria, 1999), Vol. 3, p. 1135] plasma is examined. A simple bootstrap model in the collisional-quasilinear CQL3D Fokker-Planck code (National Technical Information Service document No. DE93002962) is used in these studies: the transiting electron distributions are connected in velocity space at the trapped-passing boundary to trapped-electron distributions that are displaced radially by a half-banana-width outwards/inwards for the co-passing/counter-passing regions. This model agrees well with standard bootstrap current calculations over the outer 60% of the plasma radius. Relatively small synergy net bootstrap current is obtained for EBW power up to 4 MW. Locally, bootstrap current density increases in proportion to increased plasma pressure, and this effect can significantly affect the radial profile of driven current

  10. Point Set Denoising Using Bootstrap-Based Radial Basis Function.

    Directory of Open Access Journals (Sweden)

    Khang Jie Liew

    Full Text Available 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.

  11. Bootstrapping integrated covariance matrix estimators in noisy jump-diffusion models with non-synchronous trading

    DEFF Research Database (Denmark)

    Hounyo, Ulrich

    to a gneral class of estimators of integrated covolatility. We then show the first-order asymptotic validity of this method in the multivariate context with a potential presence of jumps, dependent microsturcture noise, irregularly spaced and non-synchronous data. Due to our focus on non...... covariance estimator. As an application of our results, we also consider the bootstrap for regression coefficients. We show that the wild blocks of bootstrap, appropriately centered, is able to mimic both the dependence and heterogeneity of the scores, thus justifying the construction of bootstrap percentile...... intervals as well as variance estimates in this context. This contrasts with the traditional pairs bootstrap which is not able to mimic the score heterogeneity even in the simple case where no microsturcture noise is present. Our Monte Carlo simulations show that the wild blocks of blocks bootstrap improves...

  12. Application of the bootstrap method to radiolabeled antibody dosimetry from planar images

    International Nuclear Information System (INIS)

    Papenfuss, T.; Saunder, T.H.; Schleyer, P.J.; O'Keefe, G.J.; Scott, A.M.

    2002-01-01

    Full text: Planar imaging dosimetry of radiolabeled antibody treatment uses the MIRD schema to compute dose to an organ from the calculated activity in that and other organs. The calculated activity in an organ is a function of the average count rates in the organ, a standard and an appropriate background measurement. The geometric mean of conjugate averages, together with an attenuation factor is used to provide an approximate attenuation correction. It is sometimes desirable to know the variance of the activity in an organ in order to apply weighted least squares regression to the data. This is particularly important when incorporating more accurate data from autoradiography of biopsied tissue into the analysis, but is also useful when some data points have low signal. While the geometric mean image can be used to calculate the variance of an organ's count rate. It is difficult to calculate the variance of the activity, since the organ in question, the standard and the background all contribute to it. Bootstrap methods are Monte Carlo techniques that can be used to estimate parameters from data and to determine the accuracy of the estimation. By bootstrapping pixel values in the organ, background and standard ROIs, it is possible to calculate many realisations of the organ activity and calculate its variance. As an example, bootstrapping is applied to the pharmacodynamic analysis of 131 I-huA33 in colon. The data includes planar whole body images, and autoradiographs and planar images of a resected colon. Copyright (2002) The Australian and New Zealand Society of Nuclear Medicine Inc

  13. Robust block bootstrap panel predictability tests

    NARCIS (Netherlands)

    Westerlund, J.; Smeekes, S.

    2013-01-01

    Most panel data studies of the predictability of returns presume that the cross-sectional units are independent, an assumption that is not realistic. As a response to this, the current paper develops block bootstrap-based panel predictability tests that are valid under very general conditions. Some

  14. Financial bootstrapping use in new family ventures and the impact on venture growth

    OpenAIRE

    Helleboogh, David; LAVEREN, Eddy; LYBAERT, Nadine

    2010-01-01

    This paper contributes to the general knowledge of bootstrap financing among new family ventures in two ways. Firstly, this research reveals which human capital characteristics of the owner-manager has an impact on financial bootstrapping use. The empirical results indicate that the use of bootstrapping techniques does not depend upon the family's business founder's education, but that it is a skill which is absorbed from self-employed parents or during the founder's prior work and management...

  15. Financial bootstrapping use in family ventures and the impact on start-up growth

    OpenAIRE

    Helleboogh, D.; Laveren, E.; LYBAERT, Nadine

    2010-01-01

    This paper contributes to the general knowledge of bootstrap financing among new family ventures in two ways. Firstly, this research reveals which human capital characteristics of the owner-manager has an impact on financial bootstrapping use. The empirical results indicate that the use of bootstrapping techniques does not depend upon the family business founder's education, but that it is a skill which is absorbed from self-employed parents or during the founder‟s prior work and management e...

  16. Selfconsistent RF driven and bootstrap currents

    International Nuclear Information System (INIS)

    Peysson, Y.

    2002-01-01

    This important problem selfconsistent calculations of the bootstrap current with RF, taking into account possible synergistic effects, is addressed for the case of lower hybrid (LH) and electron cyclotron (EC) current drive by numerically solving the electron drift kinetic equation. Calculations are performed using a new, fast, and fully implicit code which solves the 3-D relativistic Fokker-Planck equation with quasilinear diffusion. These calculations take into account the perturbations to the electron distribution due to radial drifts induced by magnetic field gradient and curvature. While the synergism between bootstrap and LH-driven current does not seem to exceed 15%, it can reach 30-40% with the EC-driven current for some plasma parameters. In addition, considerable current can be generated by judiciously using ECCD with the Okhawa effect. This is in contrast to the usual ECCD which tries to avoid it. A detailed analysis of the numerical results is presented using a simplified analytical model which incorporates the underlying physical processes. (author)

  17. Bootstrapping mixed correlators in the five dimensional critical O(N) models

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhijin; Su, Ning [George P. and Cynthia W. Mitchell Institute for Fundamental Physics and Astronomy,Texas A& M University, College Station, TX 77843 (United States)

    2017-04-18

    We use the conformal bootstrap approach to explore 5D CFTs with O(N) global symmetry, which contain N scalars ϕ{sub i} transforming as O(N) vector. Specifically, we study multiple four-point correlators of the leading O(N) vector ϕ{sub i} and the O(N) singlet σ. The crossing symmetry of the four-point functions and the unitarity condition provide nontrivial constraints on the scaling dimensions (Δ{sub ϕ}, Δ{sub σ}) of ϕ{sub i} and σ. With reasonable assumptions on the gaps between scaling dimensions of ϕ{sub i} (σ) and the next O(N) vector ϕ{sub i}{sup ′} (singlet σ{sup ′}) scalar, we are able to isolate the scaling dimensions (Δ{sub ϕ}, Δ{sub σ}) 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≤N≤100. Isolated regions on (Δ{sub ϕ},Δ{sub σ}) plane are obtained using conformal bootstrap program with lower order of derivatives Λ; however, they disappear after increasing Λ. For N=100, no solution can be found with Λ=25 under the assumptions on the scaling dimensions of next O(N) vector Δ{sub ϕ{sub i{sup ′}}}≥5.0 (singlet Δ{sub σ{sup ′}}≥3.3). These islands are expected to be corresponding to interacting but nonunitary O(N) CFTs. Our results suggest a lower bound on the critical value N{sub c}>100, below which the interacting O(N) CFTs turn into nonunitary.

  18. Coverage probability of bootstrap confidence intervals in heavy-tailed frequency models, with application to precipitation data

    Czech Academy of Sciences Publication Activity Database

    Kyselý, Jan

    2010-01-01

    Roč. 101, 3-4 (2010), s. 345-361 ISSN 0177-798X R&D Projects: GA AV ČR KJB300420801 Institutional research plan: CEZ:AV0Z30420517 Keywords : bootstrap * extreme value analysis * confidence intervals * heavy-tailed distributions * precipitation amounts Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.684, year: 2010

  19. 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)

  20. A Local Stable Bootstrap for Power Variations of Pure-Jump Semimartingales and Activity Index Estimation

    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 activity...... index of the underlying process, β, as well as a bootstrap test for whether it obeys a jump-diffusion or a pure-jump process, that is, of the null hypothesis H₀: β=2 against the alternative H₁: βbootstrap power variations, activity index...... estimator, and diffusion test for H0. Moreover, the finite sample size and power properties of the proposed diffusion test are compared to those of benchmark tests using Monte Carlo simulations. Unlike existing procedures, our bootstrap test is correctly sized in general settings. Finally, we illustrate use...

  1. Generalized bootstrap equations and possible implications for the NLO Odderon

    Energy Technology Data Exchange (ETDEWEB)

    Bartels, J. [Hamburg Univ. (Germany). 2. Inst. fuer Theoretische Physik; Vacca, G.P. [INFN, Sezione di Bologna (Italy)

    2013-07-15

    We formulate and discuss generalized bootstrap equations in nonabelian gauge theories. They are shown to hold in the leading logarithmic approximation. Since their validity is related to the self-consistency of the Steinmann relations for inelastic production amplitudes they can be expected to be valid also in NLO. Specializing to the N=4 SYM, we show that the validity in NLO of these generalized bootstrap equations allows to find the NLO Odderon solution with intercept exactly at one.

  2. Visuospatial bootstrapping: implicit binding of verbal working memory to visuospatial representations in children and adults.

    Science.gov (United States)

    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. Copyright © 2013 Elsevier Inc. All rights reserved.

  3. Definition of total bootstrap current in tokamaks

    International Nuclear Information System (INIS)

    Ross, D.W.

    1995-01-01

    Alternative definitions of the total bootstrap current are compared. An analogous comparison is given for the ohmic and auxiliary currents. It is argued that different definitions than those usually employed lead to simpler analyses of tokamak operating scenarios

  4. Kepler Planet Detection Metrics: Statistical Bootstrap Test

    Science.gov (United States)

    Jenkins, Jon M.; Burke, Christopher J.

    2016-01-01

    This document describes the data produced by the Statistical Bootstrap Test over the final three Threshold Crossing Event (TCE) deliveries to NExScI: SOC 9.1 (Q1Q16)1 (Tenenbaum et al. 2014), SOC 9.2 (Q1Q17) aka DR242 (Seader et al. 2015), and SOC 9.3 (Q1Q17) aka DR253 (Twicken et al. 2016). The last few years have seen significant improvements in the SOC science data processing pipeline, leading to higher quality light curves and more sensitive transit searches. The statistical bootstrap analysis results presented here and the numerical results archived at NASAs Exoplanet Science Institute (NExScI) bear witness to these software improvements. This document attempts to introduce and describe the main features and differences between these three data sets as a consequence of the software changes.

  5. Comparison of parametric and bootstrap method in bioequivalence test.

    Science.gov (United States)

    Ahn, Byung-Jin; Yim, Dong-Seok

    2009-10-01

    The estimation of 90% parametric confidence intervals (CIs) of mean AUC and Cmax ratios in bioequivalence (BE) tests are based upon the assumption that formulation effects in log-transformed data are normally distributed. To compare the parametric CIs with those obtained from nonparametric methods we performed repeated estimation of bootstrap-resampled datasets. The AUC and Cmax values from 3 archived datasets were used. BE tests on 1,000 resampled datasets from each archived dataset were performed using SAS (Enterprise Guide Ver.3). Bootstrap nonparametric 90% CIs of formulation effects were then compared with the parametric 90% CIs of the original datasets. The 90% CIs of formulation effects estimated from the 3 archived datasets were slightly different from nonparametric 90% CIs obtained from BE tests on resampled datasets. Histograms and density curves of formulation effects obtained from resampled datasets were similar to those of normal distribution. However, in 2 of 3 resampled log (AUC) datasets, the estimates of formulation effects did not follow the Gaussian distribution. Bias-corrected and accelerated (BCa) CIs, one of the nonparametric CIs of formulation effects, shifted outside the parametric 90% CIs of the archived datasets in these 2 non-normally distributed resampled log (AUC) datasets. Currently, the 80~125% rule based upon the parametric 90% CIs is widely accepted under the assumption of normally distributed formulation effects in log-transformed data. However, nonparametric CIs may be a better choice when data do not follow this assumption.

  6. Bootstrap confidence intervals for three-way methods

    NARCIS (Netherlands)

    Kiers, Henk A.L.

    Results from exploratory three-way analysis techniques such as CANDECOMP/PARAFAC and Tucker3 analysis are usually presented without giving insight into uncertainties due to sampling. Here a bootstrap procedure is proposed that produces percentile intervals for all output parameters. Special

  7. Bootstrap-based confidence estimation in PCA and multivariate statistical process control

    DEFF Research Database (Denmark)

    Babamoradi, Hamid

    be used to detect outliers in the data since the outliers can distort the bootstrap estimates. Bootstrap-based confidence limits were suggested as alternative to the asymptotic limits for control charts and contribution plots in MSPC (Paper II). The results showed that in case of the Q-statistic......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....... 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...

  8. Bootstrap finance: the art of start-ups.

    Science.gov (United States)

    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.

  9. Using the Bootstrap Method for a Statistical Significance Test of Differences between Summary Histograms

    Science.gov (United States)

    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.

  10. Internal validation of risk models in clustered data: a comparison of bootstrap schemes

    NARCIS (Netherlands)

    Bouwmeester, W.; Moons, K.G.M.; Kappen, T.H.; van Klei, W.A.; Twisk, J.W.R.; Eijkemans, M.J.C.; Vergouwe, Y.

    2013-01-01

    Internal validity of a risk model can be studied efficiently with bootstrapping to assess possible optimism in model performance. Assumptions of the regular bootstrap are violated when the development data are clustered. We compared alternative resampling schemes in clustered data for the estimation

  11. Computing confidence and prediction intervals of industrial equipment degradation by bootstrapped support vector regression

    International Nuclear Information System (INIS)

    Lins, Isis Didier; Droguett, Enrique López; Moura, Márcio das Chagas; Zio, Enrico; Jacinto, Carlos Magno

    2015-01-01

    Data-driven learning methods for predicting the evolution of the degradation processes affecting equipment are becoming increasingly attractive in reliability and prognostics applications. Among these, we consider here Support Vector Regression (SVR), which has provided promising results in various applications. Nevertheless, the predictions provided by SVR are point estimates whereas in order to take better informed decisions, an uncertainty assessment should be also carried out. For this, we apply bootstrap to SVR so as to obtain confidence and prediction intervals, without having to make any assumption about probability distributions and with good performance even when only a small data set is available. The bootstrapped SVR is first verified on Monte Carlo experiments and then is applied to a real case study concerning the prediction of degradation of a component from the offshore oil industry. The results obtained indicate that the bootstrapped SVR is a promising tool for providing reliable point and interval estimates, which can inform maintenance-related decisions on degrading components. - Highlights: • Bootstrap (pairs/residuals) and SVR are used as an uncertainty analysis framework. • Numerical experiments are performed to assess accuracy and coverage properties. • More bootstrap replications does not significantly improve performance. • Degradation of equipment of offshore oil wells is estimated by bootstrapped SVR. • Estimates about the scale growth rate can support maintenance-related decisions

  12. Analysis of small sample size studies using nonparametric bootstrap test with pooled resampling method.

    Science.gov (United States)

    Dwivedi, Alok Kumar; Mallawaarachchi, Indika; Alvarado, Luis A

    2017-06-30

    Experimental studies in biomedical research frequently pose analytical problems related to small sample size. In such studies, there are conflicting findings regarding the choice of parametric and nonparametric analysis, especially with non-normal data. In such instances, some methodologists questioned the validity of parametric tests and suggested nonparametric tests. In contrast, other methodologists found nonparametric tests to be too conservative and less powerful and thus preferred using parametric tests. Some researchers have recommended using a bootstrap test; however, this method also has small sample size limitation. We used a pooled method in nonparametric bootstrap test that may overcome the problem related with small samples in hypothesis testing. The present study compared nonparametric bootstrap test with pooled resampling method corresponding to parametric, nonparametric, and permutation tests through extensive simulations under various conditions and using real data examples. The nonparametric pooled bootstrap t-test provided equal or greater power for comparing two means as compared with unpaired t-test, Welch t-test, Wilcoxon rank sum test, and permutation test while maintaining type I error probability for any conditions except for Cauchy and extreme variable lognormal distributions. In such cases, we suggest using an exact Wilcoxon rank sum test. Nonparametric bootstrap paired t-test also provided better performance than other alternatives. Nonparametric bootstrap test provided benefit over exact Kruskal-Wallis test. We suggest using nonparametric bootstrap test with pooled resampling method for comparing paired or unpaired means and for validating the one way analysis of variance test results for non-normal data in small sample size studies. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

  13. Speeding Up Non-Parametric Bootstrap Computations for Statistics Based on Sample Moments in Small/Moderate Sample Size Applications.

    Directory of Open Access Journals (Sweden)

    Elias Chaibub Neto

    Full Text Available In this paper we propose a vectorized implementation of the non-parametric bootstrap for statistics based on sample moments. Basically, we adopt the multinomial sampling formulation of the non-parametric bootstrap, and compute bootstrap replications of sample moment statistics by simply weighting the observed data according to multinomial counts instead of evaluating the statistic on a resampled version of the observed data. Using this formulation we can generate a matrix of bootstrap weights and compute the entire vector of bootstrap replications with a few matrix multiplications. Vectorization is particularly important for matrix-oriented programming languages such as R, where matrix/vector calculations tend to be faster than scalar operations implemented in a loop. We illustrate the application of the vectorized implementation in real and simulated data sets, when bootstrapping Pearson's sample correlation coefficient, and compared its performance against two state-of-the-art R implementations of the non-parametric bootstrap, as well as a straightforward one based on a for loop. Our investigations spanned varying sample sizes and number of bootstrap replications. The vectorized bootstrap compared favorably against the state-of-the-art implementations in all cases tested, and was remarkably/considerably faster for small/moderate sample sizes. The same results were observed in the comparison with the straightforward implementation, except for large sample sizes, where the vectorized bootstrap was slightly slower than the straightforward implementation due to increased time expenditures in the generation of weight matrices via multinomial sampling.

  14. arXiv The S-matrix Bootstrap I: QFT in AdS

    CERN Document Server

    Paulos, Miguel F.; Toledo, Jonathan; van Rees, Balt C.; Vieira, Pedro

    2017-11-21

    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.

  15. Nonparametric bootstrap procedures for predictive inference based on recursive estimation schemes

    OpenAIRE

    Corradi, Valentina; Swanson, Norman R.

    2005-01-01

    Our objectives in this paper are twofold. First, we introduce block bootstrap techniques that are (first order) valid in recursive estimation frameworks. Thereafter, we present two examples where predictive accuracy tests are made operational using our new bootstrap procedures. In one application, we outline a consistent test for out-of-sample nonlinear Granger causality, and in the other we outline a test for selecting amongst multiple alternative forecasting models, all of which are possibl...

  16. How to bootstrap a human communication system.

    Science.gov (United States)

    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 items to a partner using repeated non-linguistic vocalization, repeated gesture, or repeated non-linguistic vocalization plus gesture (but without using their existing language system). Gesture proved more effective (measured by communication success) and more efficient (measured by the time taken to communicate) than non-linguistic vocalization across a range of item categories (emotion, object, and action). Combining gesture and vocalization did not improve performance beyond gesture alone. We experimentally demonstrate that gesture is a more effective means of bootstrapping a human communication system. We argue that gesture outperforms non-linguistic vocalization because it lends itself more naturally to the production of motivated signs. © 2013 Cognitive Science Society, Inc.

  17. Application of bootstrap sampling in gamma-ray astronomy: Time variability in pulsed emission from crab pulsar

    International Nuclear Information System (INIS)

    Ozel, M.E.; Mayer-Hasselwander, H.

    1985-01-01

    This paper discusses the bootstrap scheme which fits well for many astronomical applications. It is based on the well-known sampling plan called ''sampling with replacement''. Digital computers make the method very practical for the investigation of various trends present in a limited set of data which is usually a small fraction of the total population. The authors attempt to apply the method and demonstrate its feasibility. The study indicates that the discrete nature of high energy gamma-ray data makes the bootstrap method especially attractive for gamma-ray astronomy. Present analysis shows that the ratio of pulse strengths is variable with a 99.8% confidence

  18. Construction of prediction intervals for Palmer Drought Severity Index using bootstrap

    Science.gov (United States)

    Beyaztas, Ufuk; Bickici Arikan, Bugrayhan; Beyaztas, Beste Hamiye; Kahya, Ercan

    2018-04-01

    In this study, we propose an approach based on the residual-based bootstrap method to obtain valid prediction intervals using monthly, short-term (three-months) and mid-term (six-months) drought observations. The effects of North Atlantic and Arctic Oscillation indexes on the constructed prediction intervals are also examined. Performance of the proposed approach is evaluated for the Palmer Drought Severity Index (PDSI) obtained from Konya closed basin located in Central Anatolia, Turkey. The finite sample properties of the proposed method are further illustrated by an extensive simulation study. Our results revealed that the proposed approach is capable of producing valid prediction intervals for future PDSI values.

  19. A proof of fulfillment of the strong bootstrap condition

    International Nuclear Information System (INIS)

    Fadin, V.S.; Papa, A.

    2002-01-01

    It is shown that the kernel of the BFKL equation for the octet color state of two Reggeized gluons satisfies the strong bootstrap condition in the next-to-leading order. This condition is much more restrictive than the one obtained from the requirement of the Reggeized form for the elastic scattering amplitudes in the next-to-leading approximation. It is necessary, however, for self-consistency of the assumption of the Reggeized form of the production amplitudes in multi-Regge kinematics, which are used in the derivation of the BFKL equation. The fulfillment of the strong bootstrap condition for the kernel opens the way to a rigorous proof of the BFKL equation in the next-to-leading approximation. (author)

  20. Mobile first design : using Bootstrap

    OpenAIRE

    Bhusal, Bipin

    2017-01-01

    The aim of this project was to design and build a website for a company based in Australia. The business offers remedial massage therapy to its clients. It is a small business which works on the basis of calls and message reservation. The business currently has a temporary website designed with Wix, a cloud-based web development platform. The new website was built with responsive design using Bootstrap. This website was intended for the customers using mobile internet browsers. This design is...

  1. How to Bootstrap Anonymous Communication

    DEFF Research Database (Denmark)

    Jakobsen, Sune K.; Orlandi, Claudio

    2015-01-01

    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....

  2. How to Bootstrap Anonymous Communication

    DEFF Research Database (Denmark)

    Jakobsen, Sune K.; Orlandi, Claudio

    2015-01-01

    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....

  3. 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 bias......-overlapping nature of the pre-averaged returns implies that these are asymptotically independent, but possibly heteroskedastic. This motivates the application of the wild bootstrap in this context. We provide a proof of the first order asymptotic validity of this method for percentile and percentile-t intervals. Our...... Monte Carlo simulations show that the wild bootstrap can improve the finite sample properties of the existing first order asymptotic theory provided we choose the external random variable appropriately. We use empirical work to illustrate its use in practice....

  4. 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.

  5. Introduction of Bootstrap Current Reduction in the Stellarator Optimization Using the Algorithm DAB

    International Nuclear Information System (INIS)

    Castejón, F.; Gómez-Iglesias, A.; Velasco, J. L.

    2015-01-01

    This work is devoted to introduce new optimization criterion in the DAB (Distributed Asynchronous Bees) code. With this new criterion, we have now in DAB the equilibrium and Mercier stability criteria, the minimization of Bxgrad(B) criterion, which ensures the reduction of neoclassical transport and the improvement of the confinement of fast particles, and the reduction of bootstrap current. We have started from a neoclassically optimised configuration of the helias type and imposed the reduction of bootstrap current. The obtained configuration only presents a modest reduction of total bootstrap current, but the local current density is reduced along the minor radii. Further investigations are developed to understand the reason of this modest improvement.

  6. Bootstrapping 3D fermions

    Energy Technology Data Exchange (ETDEWEB)

    Iliesiu, Luca [Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (United States); Kos, Filip; Poland, David [Department of Physics, Yale University, New Haven, CT 06520 (United States); Pufu, Silviu S. [Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (United States); Simmons-Duffin, David [School of Natural Sciences, Institute for Advanced Study, Princeton, NJ 08540 (United States); Yacoby, Ran [Joseph Henry Laboratories, Princeton University, Princeton, NJ 08544 (United States)

    2016-03-17

    We study the conformal bootstrap for a 4-point function of fermions 〈ψψψψ〉 in 3D. We first introduce an embedding formalism for 3D spinors and compute the conformal blocks appearing in fermion 4-point functions. Using these results, we find general bounds on the dimensions of operators appearing in the ψ×ψ OPE, and also on the central charge C{sub T}. We observe features in our bounds that coincide with scaling dimensions in the Gross-Neveu models at large N. We also speculate that other features could coincide with a fermionic CFT containing no relevant scalar operators.

  7. Check of the bootstrap conditions for the gluon Reggeization

    International Nuclear Information System (INIS)

    Papa, A.

    2000-01-01

    The property of gluon Reggeization plays an essential role in the derivation of the Balitsky-Fadin-Kuraev-Lipatov (BFKL) equation for the cross sections at high energy √s in perturbative QCD. This property has been proved to all orders of perturbation theory in the leading logarithmic approximation and it is assumed to be valid also in the next-to-leading logarithmic approximation, where it has been checked only to the first three orders of perturbation theory. From s-channel unitarity, however, very stringent 'bootstrap' conditions can be derived which, if fulfilled, leave no doubts that gluon Reggeization holds

  8. A SQUID Bootstrap Circuit with a Large Parameter Tolerance

    International Nuclear Information System (INIS)

    Zhang Guo-Feng; Kong Xiang-Yan; Xie Xiao-Ming; Zhang Yi; Krause Hans-Joachim; Offenhäusser Andreas

    2013-01-01

    The voltage biased (SQUID) bootstrap circuit (SBC) was recently introduced as an effective means to reduce the preamplifier noise contribution. We analyze the tolerances of the SBC noise suppression performance to spreads in SQUID and SBC circuit parameters. It is found that the tolerance to spread mainly caused by the integrated circuit fabrication process could be extended by a one-time adjustable current feedback. A helium-cooled niobium SQUID with a loop inductance of 350 pH is employed to experimentally verify the analysis. From this work, design criteria for fully integrated SBC devices with a high yield can be derived

  9. Model-based bootstrapping when correcting for measurement error with application to logistic regression.

    Science.gov (United States)

    Buonaccorsi, John P; Romeo, Giovanni; Thoresen, Magne

    2018-03-01

    When fitting regression models, measurement error in any of the predictors typically leads to biased coefficients and incorrect inferences. A plethora of methods have been proposed to correct for this. Obtaining standard errors and confidence intervals using the corrected estimators can be challenging and, in addition, there is concern about remaining bias in the corrected estimators. The bootstrap, which is one option to address these problems, has received limited attention in this context. It has usually been employed by simply resampling observations, which, while suitable in some situations, is not always formally justified. In addition, the simple bootstrap does not allow for estimating bias in non-linear models, including logistic regression. Model-based bootstrapping, which can potentially estimate bias in addition to being robust to the original sampling or whether the measurement error variance is constant or not, has received limited attention. However, it faces challenges that are not present in handling regression models with no measurement error. This article develops new methods for model-based bootstrapping when correcting for measurement error in logistic regression with replicate measures. The methodology is illustrated using two examples, and a series of simulations are carried out to assess and compare the simple and model-based bootstrap methods, as well as other standard methods. While not always perfect, the model-based approaches offer some distinct improvements over the other methods. © 2017, The International Biometric Society.

  10. How to Bootstrap a Human Communication System

    Science.gov (United States)

    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…

  11. Integrable deformations of conformal theories and bootstrap trees

    International Nuclear Information System (INIS)

    Mussardo, G.

    1991-01-01

    I present recent results in the study of massive integrable quantum field theories in (1+1) dimensions considered as perturbed conformal minimal models. The on mass-shell properties of such theories, with a particular emphasis on the bootstrap principle, are investigated. (orig.)

  12. More N =4 superconformal bootstrap

    Science.gov (United States)

    Beem, Christopher; Rastelli, Leonardo; van Rees, Balt C.

    2017-08-01

    In this long overdue second installment, we continue to develop the conformal bootstrap program for N =4 superconformal field theories (SCFTs) in four dimensions via an analysis of the correlation function of four stress-tensor supermultiplets. We review analytic results for this correlator and make contact with the SCFT/chiral algebra correspondence of Beem et al. [Commun. Math. Phys. 336, 1359 (2015), 10.1007/s00220-014-2272-x]. We demonstrate that the constraints of unitarity and crossing symmetry require the central charge c to be greater than or equal to 3 /4 in any interacting N =4 SCFT. We apply numerical bootstrap methods to derive upper bounds on scaling dimensions and operator product expansion coefficients for several low-lying, unprotected operators as a function of the central charge. We interpret our bounds in the context of N =4 super Yang-Mills theories, formulating a series of conjectures regarding the embedding of the conformal manifold—parametrized by the complexified gauge coupling—into the space of scaling dimensions and operator product expansion coefficients. Our conjectures assign a distinguished role to points on the conformal manifold that are self-dual under a subgroup of the S -duality group. This paper contains a more detailed exposition of a number of results previously reported in Beem et al. [Phys. Rev. Lett. 111, 071601 (2013), 10.1103/PhysRevLett.111.071601] in addition to new results.

  13. Quadratic mass relations in topological bootstrap theory

    International Nuclear Information System (INIS)

    Jones, C.E.; Uschersohn, J.

    1980-01-01

    From the requirement of reality of discontinuities of scattering amplitudes at the spherical level of the topological bootstrap theory, a large number of mass relations for hadrons is derived. Quadratic mass formulas for the symmetry-breaking pattern of both mesons and baryon is obtained and their relation to conventional models of symmetry breaking is briefly discussed

  14. Pulling Econometrics Students up by Their Bootstraps

    Science.gov (United States)

    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…

  15. 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.

  16. 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.

  17. Finite-Size Effects for Some Bootstrap Percolation Models

    NARCIS (Netherlands)

    Enter, A.C.D. van; Adler, Joan; Duarte, J.A.M.S.

    The consequences of Schonmann's new proof that the critical threshold is unity for certain bootstrap percolation models are explored. It is shown that this proof provides an upper bound for the finite-size scaling in these systems. Comparison with data for one case demonstrates that this scaling

  18. On the Consistency of Bootstrap Testing for a Parameter on the Boundary of the Parameter Space

    DEFF Research Database (Denmark)

    Cavaliere, Giuseppe; Nielsen, Heino Bohn; Rahbek, Anders

    2017-01-01

    It is well known that with a parameter on the boundary of the parameter space, such as in the classic cases of testing for a zero location parameter or no autoregressive conditional heteroskedasticity (ARCH) effects, the classic nonparametric bootstrap – based on unrestricted parameter estimates...... – leads to inconsistent testing. In contrast, we show here that for the two aforementioned cases, a nonparametric bootstrap test based on parameter estimates obtained under the null – referred to as ‘restricted bootstrap’ – is indeed consistent. While the restricted bootstrap is simple to implement...... in practice, novel theoretical arguments are required in order to establish consistency. In particular, since the bootstrap is analysed both under the null hypothesis and under the alternative, non-standard asymptotic expansions are required to deal with parameters on the boundary. Detailed proofs...

  19. How many bootstrap replicates are necessary?

    Science.gov (United States)

    Pattengale, Nicholas D; Alipour, Masoud; Bininda-Emonds, Olaf R P; Moret, Bernard M E; Stamatakis, Alexandros

    2010-03-01

    Phylogenetic bootstrapping (BS) is a standard technique for inferring confidence values on phylogenetic trees that is based on reconstructing many trees from minor variations of the input data, trees called replicates. BS is used with all phylogenetic reconstruction approaches, but we focus here on one of the most popular, maximum likelihood (ML). Because ML inference is so computationally demanding, it has proved too expensive to date to assess the impact of the number of replicates used in BS on the relative accuracy of the support values. For the same reason, a rather small number (typically 100) of BS replicates are computed in real-world studies. Stamatakis et al. recently introduced a BS algorithm that is 1 to 2 orders of magnitude faster than previous techniques, while yielding qualitatively comparable support values, making an experimental study possible. In this article, we propose stopping criteria--that is, thresholds computed at runtime to determine when enough replicates have been generated--and we report on the first large-scale experimental study to assess the effect of the number of replicates on the quality of support values, including the performance of our proposed criteria. We run our tests on 17 diverse real-world DNA--single-gene as well as multi-gene--datasets, which include 125-2,554 taxa. We find that our stopping criteria typically stop computations after 100-500 replicates (although the most conservative criterion may continue for several thousand replicates) while producing support values that correlate at better than 99.5% with the reference values on the best ML trees. Significantly, we also find that the stopping criteria can recommend very different numbers of replicates for different datasets of comparable sizes. Our results are thus twofold: (i) they give the first experimental assessment of the effect of the number of BS replicates on the quality of support values returned through BS, and (ii) they validate our proposals for

  20. Interaction of bootstrap-current-driven magnetic islands

    International Nuclear Information System (INIS)

    Hegna, C.C.; Callen, J.D.

    1991-10-01

    The formation and interaction of fluctuating neoclassical pressure gradient driven magnetic islands is examined. The interaction of magnetic islands produces a stochastic region around the separatrices of the islands. This interaction causes the island pressure profile to be broadened, reducing the island bootstrap current and drive for the magnetic island. A model is presented that describes the magnetic topology as a bath of interacting magnetic islands with low to medium poloidal mode number (m congruent 3-30). The islands grow by the bootstrap current effect and damp due to the flattening of the pressure profile near the island separatrix caused by the interaction of the magnetic islands. The effect of this sporadic growth and decay of the islands (''magnetic bubbling'') is not normally addressed in theories of plasma transport due to magnetic fluctuations. The nature of the transport differs from statistical approaches to magnetic turbulence since the radial step size of the plasma transport is now given by the characteristic island width. This model suggests that tokamak experiments have relatively short-lived, coherent, long wavelength magnetic oscillations present in the steep pressure-gradient regions of the plasma. 42 refs

  1. On the definition of Pfirsch--Schlueter and bootstrap currents in toroidal systems

    International Nuclear Information System (INIS)

    Coronado, M.; Wobig, H.

    1992-01-01

    In the plasma physics literature there appear two different definitions of Pfirsch--Schlueter current. One of them is predominantly used in equilibrium calculations and satisfies the condition I T =0. The other definition appears commonly in transport calculations and requires that the surface average of the dot product of the Pfirsch--Schlueter current density with the magnetic field vanish, i.e., left-angle J PS ·B right-angle=0. The difference between the definitions is a surface function. Within the framework of the moment equation approach, the total parallel current is completely determined through a surface average of Ohm's law; thus different definitions of Pfirsch--Schlueter current imply different expressions for the bootstrap current. Understanding the different implications of these two definitions is of particular importance when designing toroidal devices with minimized Pfirsch--Schlueter current or studying tokamaks with optimized bootstrap current. In this paper the definitions of Pfirsch--Schlueter and bootstrap current, as well as the expressions for the corresponding Pfirsch--Schlueter diffusion flux, are analyzed and discussed for the case of axisymmetric and nonaxisymmetric plasmas. Although in cases like a current-free stellarator or a large-aspect-ratio tokamak both definitions are equivalent, they are in general different, and in order to avoid misunderstandings it is therefore important to use only one. The most appropriate definition is I T =0. In this paper the equations for determining the bootstrap current within the framework of the fluid equations are also analyzed

  2. Semantic Drift in Espresso-style Bootstrapping: Graph-theoretic Analysis and Evaluation in Word Sense Disambiguation

    Science.gov (United States)

    Komachi, Mamoru; Kudo, Taku; Shimbo, Masashi; Matsumoto, Yuji

    Bootstrapping has a tendency, called semantic drift, to select instances unrelated to the seed instances as the iteration proceeds. We demonstrate the semantic drift of Espresso-style bootstrapping has the same root as the topic drift of Kleinberg's HITS, using a simplified graph-based reformulation of bootstrapping. We confirm that two graph-based algorithms, the von Neumann kernels and the regularized Laplacian, can reduce the effect of semantic drift in the task of word sense disambiguation (WSD) on Senseval-3 English Lexical Sample Task. Proposed algorithms achieve superior performance to Espresso and previous graph-based WSD methods, even though the proposed algorithms have less parameters and are easy to calibrate.

  3. Finite-size effects for anisotropic bootstrap percolation : Logarithmic corrections

    NARCIS (Netherlands)

    van Enter, Aernout C. D.; Hulshof, Tim

    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.

  4. 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...

  5. Finite-size effects for anisotropic bootstrap percolation: logerithmic corrections

    NARCIS (Netherlands)

    Enter, van A.C.D.; Hulshof, T.

    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.

  6. Standard Error Computations for Uncertainty Quantification in Inverse Problems: Asymptotic Theory vs. Bootstrapping.

    Science.gov (United States)

    Banks, H T; Holm, Kathleen; Robbins, Danielle

    2010-11-01

    We computationally investigate two approaches for uncertainty quantification in inverse problems for nonlinear parameter dependent dynamical systems. We compare the bootstrapping and asymptotic theory approaches for problems involving data with several noise forms and levels. We consider both constant variance absolute error data and relative error which produces non-constant variance data in our parameter estimation formulations. We compare and contrast parameter estimates, standard errors, confidence intervals, and computational times for both bootstrapping and asymptotic theory methods.

  7. On the optimization of a steady-state bootstrap-reactor

    International Nuclear Information System (INIS)

    Polevoy, A.R.; Martynov, A.A.; Medvedev, S.Yu.

    1993-01-01

    A commercial fusion tokamak-reactor may be economically acceptable only for low recirculating power fraction r 0 ≡ P CD /P α BS ≡I BS /I > 0.9 to sustain the steady-state operation mode for high plasma densities > 1.5 10 20 m -3 , fulfilled the divertor conditions. This paper presents the approximate expressions for the optimal set of reactor parameters for r BS /I∼1, based on the self-consistent plasma simulations by 1.5D ASTRA code. The linear MHD stability analysis for ideal n=1 kink and ballooning modes has been carried out to determine the conditions of stabilization for bootstrap steady state tokamak reactor BSSTR configurations. (author) 10 refs., 1 tab

  8. 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.

  9. Modality specificity and integration in working memory: Insights from visuospatial bootstrapping.

    Science.gov (United States)

    Allen, Richard J; Havelka, Jelena; Falcon, Thomas; Evans, Sally; Darling, Stephen

    2015-05-01

    The question of how meaningful associations between verbal and spatial information might be utilized to facilitate working memory performance is potentially highly instructive for models of memory function. The present study explored how separable processing capacities within specialized domains might each contribute to this, by examining the disruptive impacts of simple verbal and spatial concurrent tasks on young adults' recall of visually presented digit sequences encountered either in a single location or within a meaningful spatial "keypad" configuration. The previously observed advantage for recall in the latter condition (the "visuospatial bootstrapping effect") consistently emerged across 3 experiments, indicating use of familiar spatial information in boosting verbal memory. The magnitude of this effect interacted with concurrent activity; articulatory suppression during encoding disrupted recall to a greater extent when digits were presented in single locations (Experiment 1), while spatial tapping during encoding had a larger impact on the keypad condition and abolished the visuospatial bootstrapping advantage (Experiment 2). When spatial tapping was performed during recall (Experiment 3), no task by display interaction was observed. Outcomes are discussed within the context of the multicomponent model of working memory, with a particular emphasis on cross-domain storage in the episodic buffer (Baddeley, 2000). (c) 2015 APA, all rights reserved).

  10. Statistical error estimation of the Feynman-α method using the bootstrap method

    International Nuclear Information System (INIS)

    Endo, Tomohiro; Yamamoto, Akio; Yagi, Takahiro; Pyeon, Cheol Ho

    2016-01-01

    Applicability of the bootstrap method is investigated to estimate the statistical error of the Feynman-α method, which is one of the subcritical measurement techniques on the basis of reactor noise analysis. In the Feynman-α method, the statistical error can be simply estimated from multiple measurements of reactor noise, however it requires additional measurement time to repeat the multiple times of measurements. Using a resampling technique called 'bootstrap method' standard deviation and confidence interval of measurement results obtained by the Feynman-α method can be estimated as the statistical error, using only a single measurement of reactor noise. In order to validate our proposed technique, we carried out a passive measurement of reactor noise without any external source, i.e. with only inherent neutron source by spontaneous fission and (α,n) reactions in nuclear fuels at the Kyoto University Criticality Assembly. Through the actual measurement, it is confirmed that the bootstrap method is applicable to approximately estimate the statistical error of measurement results obtained by the Feynman-α method. (author)

  11. Bootstrapping the O(N) Archipelago

    CERN Document Server

    Kos, Filip; Simmons-Duffin, David; Vichi, Alessandro

    2015-01-01

    We study 3d CFTs with an $O(N)$ global symmetry using the conformal bootstrap for a system of mixed correlators. Specifically, we consider all nonvanishing scalar four-point functions containing the lowest dimension $O(N)$ vector $\\phi_i$ and the lowest dimension $O(N)$ singlet $s$, assumed to be the only relevant operators in their symmetry representations. The constraints of crossing symmetry and unitarity for these four-point functions force the scaling dimensions $(\\Delta_\\phi, \\Delta_s)$ to lie inside small islands. We also make rigorous determinations of current two-point functions in the $O(2)$ and $O(3)$ models, with applications to transport in condensed matter systems.

  12. 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.

  13. Introduction of Bootstrap Current Reduction in the Stellarator Optimization Using the Algorithm DAB; Introducción de la reducción actual de bootstrap en la optimización de stellarator utilizando el algoritmo DAB

    Energy Technology Data Exchange (ETDEWEB)

    Castejón, F.; Gómez-Iglesias, A.; Velasco, J. L.

    2015-07-01

    This work is devoted to introduce new optimization criterion in the DAB (Distributed Asynchronous Bees) code. With this new criterion, we have now in DAB the equilibrium and Mercier stability criteria, the minimization of Bxgrad(B) criterion, which ensures the reduction of neoclassical transport and the improvement of the confinement of fast particles, and the reduction of bootstrap current. We have started from a neoclassically optimised configuration of the helias type and imposed the reduction of bootstrap current. The obtained configuration only presents a modest reduction of total bootstrap current, but the local current density is reduced along the minor radii. Further investigations are developed to understand the reason of this modest improvement.

  14. Syntactic bootstrapping in children with Down syndrome: the impact of bilingualism.

    Science.gov (United States)

    Cleave, Patricia L; Kay-Raining Bird, Elizabeth; Trudeau, Natacha; Sutton, Ann

    2014-01-01

    The purpose of the study was to add to our knowledge of bilingual learning in children with Down syndrome (DS) using a syntactic bootstrapping task. Four groups of children and youth matched on non-verbal mental age participated. There were 14 bilingual participants with DS (DS-B, mean age 12;5), 12 monolingual participants with DS (DS-M, mean age 10;10), 9 bilingual typically developing children (TD-B; mean age 4;1) and 11 monolingual typically developing children (TD-M; mean age 4;1). The participants completed a computerized syntactic bootstrapping task involving unfamiliar nouns and verbs. The syntactic cues employed were a for the nouns and ing for the verbs. Performance was better on nouns than verbs. There was also a main effect for group. Follow-up t-tests revealed that there were no significant differences between the TD-M and TD-B or between the DS-M and DS-B groups. However, the DS-M group performed more poorly than the TD-M group with a large effect size. Analyses at the individual level revealed a similar pattern of results. There was evidence that Down syndrome impacted performance; there was no evidence that bilingualism negatively affected the syntactic bootstrapping skills of individuals with DS. These results from a dynamic language task are consistent with those of previous studies that used static or product measures. Thus, the results are consistent with the position that parents should be supported in their decision to provide bilingual input to their children with DS. Readers of this article will identify (1) research evidence regarding bilingual development in children with Down syndrome and (2) syntactic bootstrapping skills in monolingual and bilingual children who are typically developing or who have Down syndrome. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. A Bootstrap Neural Network Based Heterogeneous Panel Unit Root Test: Application to Exchange Rates

    OpenAIRE

    Christian de Peretti; Carole Siani; Mario Cerrato

    2010-01-01

    This paper proposes a bootstrap artificial neural network based panel unit root test in a dynamic heterogeneous panel context. An application to a panel of bilateral real exchange rate series with the US Dollar from the 20 major OECD countries is provided to investigate the Purchase Power Parity (PPP). The combination of neural network and bootstrapping significantly changes the findings of the economic study in favour of PPP.

  16. Metastability Thresholds for Anisotropic Bootstrap Percolation in Three Dimensions

    NARCIS (Netherlands)

    Enter, Aernout C.D. van; Fey, Anne

    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

  17. Thermal energy and bootstrap current in fusion reactor plasmas

    International Nuclear Information System (INIS)

    Becker, G.

    1993-01-01

    For DT fusion reactors with prescribed alpha particle heating power P α , plasma volume V and burn temperature i > ∼ 10 keV specific relations for the thermal energy content, bootstrap current, central plasma pressure and other quantities are derived. It is shown that imposing P α and V makes these relations independent of the magnitudes of the density and temperature, i.e. they only depend on P α , V and shape factors or profile parameters. For model density and temperature profiles analytic expressions for these shape factors and for the factor C bs in the bootstrap current formula I bs ∼ C bs (a/R) 1/2 β p I p are given. In the design of next-step devices and fusion reactors, the fusion power is a fixed quantity. Prescription of the alpha particle heating power and plasma volume results in specific relations which can be helpful for interpreting computer simulations and for the design of fusion reactors. (author) 5 refs

  18. The sound symbolism bootstrapping hypothesis for language acquisition and language evolution.

    Science.gov (United States)

    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.

  19. Measurement Uncertainty Evaluation in Dimensional X-ray Computed Tomography Using the Bootstrap Method

    DEFF Research Database (Denmark)

    Hiller, Jochen; Genta, Gianfranco; Barbato, Giulio

    2014-01-01

    measurement processes, e.g., with tactile systems, also due to factors related to systematic errors, mainly caused by specific CT image characteristics. In this paper we propose a simulation-based framework for measurement uncertainty evaluation in dimensional CT using the bootstrap method. In a case study...... the problem concerning measurement uncertainties was addressed with bootstrap and successfully applied to ball-bar CT measurements. Results obtained enabled extension to more complex shapes such as actual industrial components as we show by tests on a hollow cylinder workpiece....

  20. 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.

  1. Bootstrapping the O(N) archipelago

    Energy Technology Data Exchange (ETDEWEB)

    Kos, Filip; Poland, David [Department of Physics, Yale University, New Haven, CT 06520 (United States); Simmons-Duffin, David [School of Natural Sciences, Institute for Advanced Study, Princeton, New Jersey 08540 (United States); Vichi, Alessandro [Theory Division, CERN, Geneva (Switzerland)

    2015-11-17

    We study 3d CFTs with an O(N) global symmetry using the conformal bootstrap for a system of mixed correlators. Specifically, we consider all nonvanishing scalar four-point functions containing the lowest dimension O(N) vector ϕ{sub i} and the lowest dimension O(N) singlet s, assumed to be the only relevant operators in their symmetry representations. The constraints of crossing symmetry and unitarity for these four-point functions force the scaling dimensions (Δ{sub ϕ},Δ{sub s}) to lie inside small islands. We also make rigorous determinations of current two-point functions in the O(2) and O(3) models, with applications to transport in condensed matter systems.

  2. 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

  3. Maximum non-extensive entropy block bootstrap for non-stationary processes

    Czech Academy of Sciences Publication Activity Database

    Bergamelli, M.; Novotný, Jan; Urga, G.

    2015-01-01

    Roč. 91, 1/2 (2015), s. 115-139 ISSN 0001-771X R&D Projects: GA ČR(CZ) GA14-27047S Institutional support: RVO:67985998 Keywords : maximum entropy * bootstrap * Monte Carlo simulations Subject RIV: AH - Economics

  4. Electric conductivity and bootstrap current in tokamak

    International Nuclear Information System (INIS)

    Mao Jianshan; Wang Maoquan

    1996-12-01

    A modified Ohm's law for the electric conductivity calculation is presented, where the modified ohmic current can be compensated by the bootstrap current. A comparison of TEXT tokamak experiment with the theories shows that the modified Ohm's law is a more close approximation to the tokamak experiments than the classical and neoclassical theories and can not lead to the absurd result of Z eff <1, and the extended neoclassical theory would be not necessary. (3 figs.)

  5. Bootstrap equations for N=4 SYM with defects

    Energy Technology Data Exchange (ETDEWEB)

    Liendo, Pedro [IMIP, Humboldt-Universität zu Berlin, IRIS Adlershof,Zum Großen Windkanal 6, 12489 Berlin (Germany); Meneghelli, Carlo [Simons Center for Geometry and Physics, Stony Brook University,Stony Brook, NY 11794-3636 (United States)

    2017-01-27

    This paper focuses on the analysis of 4dN=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 obtain the Ward identities associated to two-point functions of (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 4dN=4 superconformal theories with a boundary, but also to three more systems that have the same symmetry algebra: 4dN=4 superconformal theories with a line defect, 3dN=4 superconformal theories with no defect, and OSP(4{sup ∗}|4) superconformal quantum mechanics. The superconformal algebra implies that all these systems possess a closed subsector of operators in which the bootstrap equations become polynomial constraints on the CFT data. We derive these truncated equations and initiate the study of their solutions.

  6. Bootstrap equations for N=4 SYM with defects

    International Nuclear Information System (INIS)

    Liendo, Pedro; Meneghelli, Carlo

    2017-01-01

    This paper focuses on the analysis of 4dN=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 obtain the Ward identities associated to two-point functions of (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 4dN=4 superconformal theories with a boundary, but also to three more systems that have the same symmetry algebra: 4dN=4 superconformal theories with a line defect, 3dN=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 bootstrap equations become polynomial constraints on the CFT data. We derive these truncated equations and initiate the study of their solutions.

  7. 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.

  8. A bootstrapping method for development of Treebank

    Science.gov (United States)

    Zarei, F.; Basirat, A.; Faili, H.; Mirain, M.

    2017-01-01

    Using statistical approaches beside the traditional methods of natural language processing could significantly improve both the quality and performance of several natural language processing (NLP) tasks. The effective usage of these approaches is subject to the availability of the informative, accurate and detailed corpora on which the learners are trained. This article introduces a bootstrapping method for developing annotated corpora based on a complex and rich linguistically motivated elementary structure called supertag. To this end, a hybrid method for supertagging is proposed that combines both of the generative and discriminative methods of supertagging. The method was applied on a subset of Wall Street Journal (WSJ) in order to annotate its sentences with a set of linguistically motivated elementary structures of the English XTAG grammar that is using a lexicalised tree-adjoining grammar formalism. The empirical results confirm that the bootstrapping method provides a satisfactory way for annotating the English sentences with the mentioned structures. The experiments show that the method could automatically annotate about 20% of WSJ with the accuracy of F-measure about 80% of which is particularly 12% higher than the F-measure of the XTAG Treebank automatically generated from the approach proposed by Basirat and Faili [(2013). Bridge the gap between statistical and hand-crafted grammars. Computer Speech and Language, 27, 1085-1104].

  9. Adaptive Kernel In The Bootstrap Boosting Algorithm In KDE ...

    African Journals Online (AJOL)

    This paper proposes the use of adaptive kernel in a bootstrap boosting algorithm in kernel density estimation. The algorithm is a bias reduction scheme like other existing schemes but uses adaptive kernel instead of the regular fixed kernels. An empirical study for this scheme is conducted and the findings are comparatively ...

  10. Bootstrapping the energy flow in the beginning of life

    NARCIS (Netherlands)

    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

  11. Bootstrapping the energy flow in the beginning of life.

    NARCIS (Netherlands)

    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

  12. 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.

  13. 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...

  14. Determining the significance of associations between two series of discrete events : bootstrap methods /

    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.

  15. GSD: An SPSS extension command for sub-sampling and bootstrapping datasets

    Directory of Open Access Journals (Sweden)

    Harding, Bradley

    2016-09-01

    Full Text Available Statistical analyses have grown immensely since the inception of computational methods. However, many quantitative methods classes teach sampling and sub-sampling at a very abstract level despite the fact that, with the faster computers of today, these notions could be demonstrated live to the students. For this reason, we have created a simple extension module for SPSS that can sub-sample and Bootstrap data, GSD (Generator of Sub-sampled Data. In this paper, we describe and show how to use the GSD module as well as provide short descriptions of both the sub-sampling and Bootstrap methods. In addition, as this article aims to inspire instructors to introduce these concepts in their statistics classes of all levels, we provide three short exercises that are ready for curriculum implementation.

  16. Extended theory of main ion and impurity rotation and bootstrap current in a shear layer

    International Nuclear Information System (INIS)

    Kim, Y.B.; Hinton, F.L.; St. John, H.; Taylor, T.S.; Wroblewski, D.

    1993-11-01

    In this paper, standard neoclassical theory has been extended into the shear layer. Main ion and impurity ion rotation velocity and bootstrap current within shear layer in H-mode are discussed. Inside the H-mode shear layer, standard neoclassical theory is not valid since the ion poloidal gyroradius becomes comparable to pressure gradient and electric field gradient scale length. To allow for arbitrary ratio of ρθi/L n and ρθi/L Er a new kinetic theory of main ion species within electric field shear layer has been developed with the assumption that ρθi/R o is still small. As a consequence, both impurity flows and bootstrap current have to be modified. We present modified expressions of impurity flows and bootstrap current are presented neglecting ion temperature gradient. Comparisons with DIII-D measurements are also discussed

  17. The N=2 superconformal bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Beem, Christopher [Institute for Advanced Study, Einstein Drive,Princeton, NJ 08540 (United States); Lemos, Madalena [C. N. Yang Institute for Theoretical Physics, Stony Brook University,Stony Brook, NY 11794-3840 (United States); Liendo, Pedro [IMIP, Humboldt-Universität zu Berlin, IRIS Adlershof,Zum Großen Windkanal 6, 12489 Berlin (Germany); Rastelli, Leonardo [C. N. Yang Institute for Theoretical Physics, Stony Brook University,Stony Brook, NY 11794-3840 (United States); Rees, Balt C. van [Theory Group, Physics Department, CERN,CH-1211 Geneva 23 (Switzerland)

    2016-03-29

    In this work we initiate the conformal bootstrap program for N=2 superconformal field theories in four dimensions. We promote an abstract operator-algebraic viewpoint in order to unify the description of Lagrangian and non-Lagrangian theories, and formulate various conjectures concerning the landscape of theories. We analyze in detail the four-point functions of flavor symmetry current multiplets and of N=2 chiral operators. For both correlation functions we review the solution of the superconformal Ward identities and describe their superconformal block decompositions. This provides the foundation for an extensive numerical analysis discussed in the second half of the paper. We find a large number of constraints for operator dimensions, OPE coefficients, and central charges that must hold for any N=2 superconformal field theory.

  18. Energy consumption and economic growth nexus for 17 highly developed OECD countries: Further evidence based on bootstrap-corrected causality tests

    International Nuclear Information System (INIS)

    Yildirim, Ertugrul; Aslan, Alper

    2012-01-01

    Unlike previous energy consumption-economic growth studies, this study examines the relationship among energy consumption, economic growth, employment and gross fixed capital formation for 17 highly developed OECD countries by employing both the Toda–Yamamoto procedure which based on asymptotic critical values and the bootstrap-corrected causality test, since non-normality of the error term harms the validity of the Toda–Yamamoto procedure. This study finds that there is very small bias due to the assumption of normality. Furthermore using different information criterions, importance of lag length is tested. Findings indicate that selection of lag length is important for Denmark, Ireland, Norway and Spain. It is concluded that while there exists uni-directional causality running from energy consumption to real GDP for Japan, bi-directional causality is found for Italy, New Zealand, Norway and Spain. On the other hand, uni-directional causality from GDP to energy is found for Australia, Canada and Ireland whereas no causal nexus is found for all of other nine countries. Our analyses covering the sample periods imply that Japan, Italy, New Zealand, Norway and Spain should not follow energy conservation policy at the aggregated level, since the reduction of energy damages the economic growth. - Highlights: ► This study examines energy consumption, economic growth linkage for 17 developed OECD countries. ► Lag length selection is important for Denmark, Ireland, Norway and Spain. ► There exists uni-directional causality running from energy consumption to real GDP for Japan. ► Bi-directional causality is found for Italy, New Zealand, Norway and Spain.

  19. DMSP SSM/I Daily and Monthly Polar Gridded Bootstrap Sea Ice Concentrations

    Data.gov (United States)

    National Aeronautics and Space Administration — DMSP SSM/I Daily and Monthly Polar Gridded Bootstrap Sea Ice Concentrations in polar stereographic projection currently include Defense Meteorological Satellite...

  20. The Impact of Beam Deposition on Bootstrap Current of Fast Ion Produced by Neutral Beam Tangential Injection

    International Nuclear Information System (INIS)

    Huang Qian-Hong; Gong Xue-Yu; Lu Xing-Qiang; Yu Jun; Cao Jin-Jia

    2015-01-01

    The density profile of fast ions arising from a tangentially injected diffuse neutral beam in tokamak plasma is calculated. The effects of mean free paths and beam tangency radius on the density profile are discussed under typical HL-2A plasmas parameters. The results show that the profile of fast ions is strongly peaked at the center of the plasma when the mean free path at the maximum deuteron density is larger than the minor radius, while the peak value decreases when the mean free path at the maximum deuteron density is larger than twice that of the minor radius due to the beam transmission loss. Moreover, the bootstrap current of fast ions for various mean free paths at the maximum deuteron density is calculated and its density is proved to be closely related to the deposition of the neutral beam. With the electron return current considered, the net current density obviously decreases. Meanwhile, the peak central fast ion density increases when the beam tangency radius approaches the major radius, and the net bootstrap current increases rapidly with the increasing beam tangency radius. (paper)

  1. A bootstrapped neural network model applied to prediction of the biodegradation rate of reactive Black 5 dye - doi: 10.4025/actascitechnol.v35i3.16210

    Directory of Open Access Journals (Sweden)

    Kleber Rogério Moreira Prado

    2013-06-01

    Full Text Available Current essay forwards a biodegradation model of a dye, used in the textile industry, based on a neural network propped by bootstrap remodeling. Bootstrapped neural network is set to generate estimates that are close to results obtained in an intrinsic experience in which a chemical process is applied. Pseudomonas oleovorans was used in the biodegradation of reactive Black 5. Results show a brief comparison between the information estimated by the proposed approach and the experimental data, with a coefficient of correlation between real and predicted values for a more than 0.99 biodegradation rate. Dye concentration and the solution’s pH failed to interfere in biodegradation index rates. A value above 90% of dye biodegradation was achieved between 1.000 and 1.841 mL 10 mL-1 of microorganism concentration and between 1.000 and 2.000 g 100 mL-1 of glucose concentration within the experimental conditions under analysis.   

  2. Using the Bootstrap Concept to Build an Adaptable and Compact Subversion Artifice

    National Research Council Canada - National Science Library

    Lack, Lindsey

    2003-01-01

    .... Early tiger teams recognized the possibility of this design and compared it to the two-card bootstrap loader used in mainframes since both exhibit the characteristics of compactness and adaptability...

  3. Coal consumption and economic growth nexus: Evidence from bootstrap panel Granger causality test

    Directory of Open Access Journals (Sweden)

    Anoruo Emmanuel

    2017-01-01

    Full Text Available This paper explores the causal relationship between coal consumption and economic growth for a panel of 15 African countries using bootstrap panel Granger causality test. Specifically, this paper uses the Phillips-Perron unit root test to ascertain the order of integration for the coal consumption and economic growth series. A bootstrap panel Granger causality test is employed to determine the direction of causality between coal consumption and economic growth. The results provide evidence of unidirectional causality from economic growth to coal consumption. This finding implies that coal conservation measures may be implemented with little or no adverse impact on economic growth for the sample countries as a group.

  4. Bootstrap procedure in the quasinuclear quark model

    International Nuclear Information System (INIS)

    Anisovich, V.V.; Gerasyuta, S.M.; Keltuyala, I.V.

    1983-01-01

    The scattering amplitude for quarks (dressed quarks of a single flavour, and three colours) is obtained by means of a bootstrap procedure with introdUction of an initial paint-wise interaction due to a heavy gluon exchange. The obtained quasi-nuclear model (effective short-range interaction in the S-wave states) has reasonable properties: there exist colourless meson states Jsup(p)=0sup(-), 1 - ; there are no bound states in coloured channels, a virtual diquark level Jsup(p)=1sup(+) appears in the coloured state anti 3sub(c)

  5. Y-90 PET imaging for radiation theragnosis using bootstrap event re sampling

    International Nuclear Information System (INIS)

    Nam, Taewon; Woo, Sangkeun; Min, Gyungju; Kim, Jimin; Kang, Joohyun; Lim, Sangmoo; Kim, Kyeongmin

    2013-01-01

    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

  6. Noncritical String Liouville Theory and Geometric Bootstrap Hypothesis

    Science.gov (United States)

    Hadasz, Leszek; Jaskólski, Zbigniew

    The applications of the existing Liouville theories for the description of the longitudinal dynamics of noncritical Nambu-Goto string are analyzed. We show that the recently developed DOZZ solution to the Liouville theory leads to the cut singularities in tree string amplitudes. We propose a new version of the Polyakov geometric approach to Liouville theory and formulate its basic consistency condition — the geometric bootstrap equation. Also in this approach the tree amplitudes develop cut singularities.

  7. A 'bootstrapped' Teaching/Learning Procedure

    Science.gov (United States)

    Odusina Odusote, Olusogo

    1998-04-01

    Erasing preconceived antiphysics ideas by nonscience/nonmajor physics students have elicited diverse teaching methods. Introductory general physics courses at college level have been taught by a 'bootstrap' approach. A concise treatment of the syllabus by the teacher in about 1/2 of the course duration, with brief exercises and examples. Students are then introduced to real life situations - toys, home appliances, sports, disasters, etc, and the embedded physics concepts discussed. Usually this generates a feeling of deja vu, which elicits desire for more. Each application usually encompasses topics in a broad range of the syllabus. The other half of the course is used by students to work individually/groups on assigned and graded home-works and essays, with guidance from the lecture notes and the teacher/supervisor. An end of course examination shows increase in the success rate.

  8. Performance of Bootstrap MCEWMA: Study case of Sukuk Musyarakah data

    Science.gov (United States)

    Safiih, L. Muhamad; Hila, Z. Nurul

    2014-07-01

    Sukuk Musyarakah is one of several instruments of Islamic bond investment in Malaysia, where the form of this sukuk is actually based on restructuring the conventional bond to become a Syariah compliant bond. The Syariah compliant is based on prohibition of any influence of usury, benefit or fixed return. Despite of prohibition, daily returns of sukuk are non-fixed return and in statistic, the data of sukuk returns are said to be a time series data which is dependent and autocorrelation distributed. This kind of data is a crucial problem whether in statistical and financing field. Returns of sukuk can be statistically viewed by its volatility, whether it has high volatility that describing the dramatically change of price and categorized it as risky bond or else. However, this crucial problem doesn't get serious attention among researcher compared to conventional bond. In this study, MCEWMA chart in Statistical Process Control (SPC) is mainly used to monitor autocorrelated data and its application on daily returns of securities investment data has gained widespread attention among statistician. However, this chart has always been influence by inaccurate estimation, whether on base model or its limit, due to produce large error and high of probability of signalling out-of-control process for false alarm study. To overcome this problem, a bootstrap approach used in this study, by hybridise it on MCEWMA base model to construct a new chart, i.e. Bootstrap MCEWMA (BMCEWMA) chart. The hybrid model, BMCEWMA, will be applied to daily returns of sukuk Musyarakah for Rantau Abang Capital Bhd. The performance of BMCEWMA base model showed that its more effective compare to real model, MCEWMA based on smaller error estimation, shorter the confidence interval and smaller false alarm. In other word, hybrid chart reduce the variability which shown by smaller error and false alarm. It concludes that the application of BMCEWMA is better than MCEWMA.

  9. Comparing groups randomization and bootstrap methods using R

    CERN Document Server

    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

  10. Reanalysis of cancer mortality in Japanese A-bomb survivors exposed to low doses of radiation: bootstrap and simulation methods

    Science.gov (United States)

    2009-01-01

    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 latency and risk from 10

  11. Technical and scale efficiency in public and private Irish nursing homes - a bootstrap DEA approach.

    Science.gov (United States)

    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.

  12. A Mellin space approach to the conformal bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Gopakumar, Rajesh [International Centre for Theoretical Sciences (ICTS-TIFR),Survey No. 151, Shivakote, Hesaraghatta Hobli, Bangalore North 560 089 (India); Kaviraj, Apratim [Centre for High Energy Physics, Indian Institute of Science,C.V. Raman Avenue, Bangalore 560012 (India); Sen, Kallol [Centre for High Energy Physics, Indian Institute of Science,C.V. Raman Avenue, Bangalore 560012 (India); Kavli Institute for the Physics and Mathematics of the Universe (WPI),The University of Tokyo Institutes for Advanced Study, Kashiwa, Chiba 277-8583 (Japan); Sinha, Aninda [Centre for High Energy Physics, Indian Institute of Science,C.V. Raman Avenue, Bangalore 560012 (India)

    2017-05-05

    We describe in more detail our approach to the conformal bootstrap which uses the Mellin representation of CFT{sub d} four point functions and expands them in terms of crossing symmetric combinations of AdS{sub 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(ϵ{sup 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 Ising model (at ϵ=1). We will also mention some leading order results for scalar theories near three and six dimensions. The second context is a large spin expansion, in any dimension, where we are able to reproduce and go a bit beyond some of the results recently obtained using the (double) light cone expansion. We also have a preliminary discussion about numerical implementation of the above bootstrap scheme in the absence of a small parameter.

  13. Parameter tolerance of the SQUID bootstrap circuit

    International Nuclear Information System (INIS)

    Zhang Guofeng; Dong Hui; Xie Xiaoming; Jiang Mianheng; Zhang Yi; Krause, Hans-Joachim; Braginski, Alex I; Offenhäusser, Andreas

    2012-01-01

    We recently demonstrated and analysed the voltage-biased SQUID bootstrap circuit (SBC) conceived to suppress the preamplifier noise contribution in the absence of flux modulation readout. Our scheme contains both the additional voltage and current feedbacks. In this study, we analysed the tolerance of the SBC noise suppression performance to spreads in SQUID and SBC circuit parameters. Analytical results were confirmed by experiments. A one-time adjustable current feedback can be used to extend the tolerance to spreads such as those caused by the integrated circuit fabrication process. This should help to improve the fabrication yield of SBC devices integrated on one chip—as required for multi-channel SQUID systems.

  14. Study of neoclassical transport and bootstrap current for W7-X in the 1/upsilon regime, using results from the PIES code

    International Nuclear Information System (INIS)

    Nemov, V V; Kalyuzhnyj, V N; Kasilov, S V; Drevlak, M; Nuehrenberg, J; Kernbichler, W; Reiman, A; Monticello, D

    2004-01-01

    For the magnetic field of the Wendelstein 7-X (W7-X) standard high-mirror configuration, computed by the PIES code, taking into account real coil geometry, neoclassical transport and bootstrap current are analysed in the 1/upsilon regime using methods based on the integration along magnetic field lines in a given magnetic field. The zero beta and (beta) = 1% cases are studied. The results are compared to the corresponding results for the vacuum magnetic field directly produced by modular coils. A significant advantage of W7-X over a conventional stellarator resulting from reduced neoclassical transport and from reduced bootstrap current follows from the computations although the neoclassical transport is somewhat larger than that previously obtained for the ideal W7-X model configuration

  15. How Many Subjects are Needed for a Visual Field Normative Database? A Comparison of Ground Truth and Bootstrapped Statistics.

    Science.gov (United States)

    Phu, Jack; Bui, Bang V; Kalloniatis, Michael; Khuu, Sieu K

    2018-03-01

    The number of subjects needed to establish the normative limits for visual field (VF) testing is not known. Using bootstrap resampling, we determined whether the ground truth mean, distribution limits, and standard deviation (SD) could be approximated using different set size ( x ) levels, in order to provide guidance for the number of healthy subjects required to obtain robust VF normative data. We analyzed the 500 Humphrey Field Analyzer (HFA) SITA-Standard results of 116 healthy subjects and 100 HFA full threshold results of 100 psychophysically experienced healthy subjects. These VFs were resampled (bootstrapped) to determine mean sensitivity, distribution limits (5th and 95th percentiles), and SD for different ' x ' and numbers of resamples. We also used the VF results of 122 glaucoma patients to determine the performance of ground truth and bootstrapped results in identifying and quantifying VF defects. An x of 150 (for SITA-Standard) and 60 (for full threshold) produced bootstrapped descriptive statistics that were no longer different to the original distribution limits and SD. Removing outliers produced similar results. Differences between original and bootstrapped limits in detecting glaucomatous defects were minimized at x = 250. Ground truth statistics of VF sensitivities could be approximated using set sizes that are significantly smaller than the original cohort. Outlier removal facilitates the use of Gaussian statistics and does not significantly affect the distribution limits. We provide guidance for choosing the cohort size for different levels of error when performing normative comparisons with glaucoma patients.

  16. Bootstrapping data envelopment analysis of efficiency and productivity of county public hospitals in Eastern, Central, and Western China after the public hospital reform.

    Science.gov (United States)

    Wang, Man-Li; Fang, Hai-Qing; Tao, Hong-Bing; Cheng, Zhao-Hui; Lin, Xiao-Jun; Cai, Miao; Xu, Chang; Jiang, Shuai

    2017-10-01

    China implemented the public hospital reform in 2012. This study utilized bootstrapping data envelopment analysis (DEA) to evaluate the technical efficiency (TE) and productivity of county public hospitals in Eastern, Central, and Western China after the 2012 public hospital reform. Data from 127 county public hospitals (39, 45, and 43 in Eastern, Central, and Western China, respectively) were collected during 2012-2015. Changes of TE and productivity over time were estimated by bootstrapping DEA and bootstrapping Malmquist. The disparities in TE and productivity among public hospitals in the three regions of China were compared by Kruskal-Wallis H test and Mann-Whitney U test. The average bias-corrected TE values for the four-year period were 0.6442, 0.5785, 0.6099, and 0.6094 in Eastern, Central, and Western China, and the entire country respectively, with average non-technical efficiency, low pure technical efficiency (PTE), and high scale efficiency found. Productivity increased by 8.12%, 0.25%, 12.11%, and 11.58% in China and its three regions during 2012-2015, and such increase in productivity resulted from progressive technological changes by 16.42%, 6.32%, 21.08%, and 21.42%, respectively. The TE and PTE of the county hospitals significantly differed among the three regions of China. Eastern and Western China showed significantly higher TE and PTE than Central China. More than 60% of county public hospitals in China and its three areas operated at decreasing return scales. There was a considerable space for TE improvement in county hospitals in China and its three regions. During 2012-2015, the hospitals experienced progressive productivity; however, the PTE changed adversely. Moreover, Central China continuously achieved a significantly lower efficiency score than Eastern and Western China. Decision makers and administrators in China should identify the causes of the observed inefficiencies and take appropriate measures to increase the efficiency of county

  17. Mirror bootstrap method for testing hypotheses of one mean

    OpenAIRE

    Varvak, Anna

    2012-01-01

    The general philosophy for bootstrap or permutation methods for testing hypotheses is to simulate the variation of the test statistic by generating the sampling distribution which assumes both that the null hypothesis is true, and that the data in the sample is somehow representative of the population. This philosophy is inapplicable for testing hypotheses for a single parameter like the population mean, since the two assumptions are contradictory (e.g., how can we assume both that the mean o...

  18. 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($N$)....

  19. Inverse bootstrapping conformal field theories

    Science.gov (United States)

    Li, Wenliang

    2018-01-01

    We propose a novel approach to study conformal field theories (CFTs) in general dimensions. In the conformal bootstrap program, one usually searches for consistent CFT data that satisfy crossing symmetry. In the new method, we reverse the logic and interpret manifestly crossing-symmetric functions as generating functions of conformal data. Physical CFTs can be obtained by scanning the space of crossing-symmetric functions. By truncating the fusion rules, we are able to concentrate on the low-lying operators and derive some approximate relations for their conformal data. It turns out that the free scalar theory, the 2d minimal model CFTs, the ϕ 4 Wilson-Fisher CFT, the Lee-Yang CFTs and the Ising CFTs are consistent with the universal relations from the minimal fusion rule ϕ 1 × ϕ 1 = I + ϕ 2 + T , where ϕ 1 , ϕ 2 are scalar operators, I is the identity operator and T is the stress tensor.

  20. The ${\\mathcal N}=2$ superconformal bootstrap

    CERN Document Server

    Beem, Christopher; Liendo, Pedro; Rastelli, Leonardo; van Rees, Balt C

    2016-01-01

    In this work we initiate the conformal bootstrap program for ${\\mathcal N}=2$ superconformal field theories in four dimensions. We promote an abstract operator-algebraic viewpoint in order to unify the description of Lagrangian and non-Lagrangian theories, and formulate various conjectures concerning the landscape of theories. We analyze in detail the four-point functions of flavor symmetry current multiplets and of ${\\mathcal N}=2$ chiral operators. For both correlation functions we review the solution of the superconformal Ward identities and describe their superconformal block decompositions. This provides the foundation for an extensive numerical analysis discussed in the second half of the paper. We find a large number of constraints for operator dimensions, OPE coefficients, and central charges that must hold for any ${\\mathcal N}=2$ superconformal field theory.

  1. Bootstrapping Malmquist indices for Danish seiners in the North Sea and Skagerrak

    DEFF Research Database (Denmark)

    Hoff, Ayoe

    2006-01-01

    DEA scores or related parameters. The bootstrap method for estimating confidence intervals of deterministic parameters can however be applied to estimate confidence intervals for DEA scores. This method is applied in the present paper for assessing TFP changes between 1987 and 1999 for the fleet...

  2. Abrupt change in mean using block bootstrap and avoiding variance estimation

    Czech Academy of Sciences Publication Activity Database

    Peštová, Barbora; Pešta, M.

    2018-01-01

    Roč. 33, č. 1 (2018), s. 413-441 ISSN 0943-4062 Grant - others:GA ČR(CZ) GJ15-04774Y Institutional support: RVO:67985807 Keywords : Block bootstrap * Change in mean * Change point * Hypothesis test ing * Ratio type statistics * Robustness Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 0.434, year: 2016

  3. Observation of the bootstrap current reduction at magnetic island in a neoclassical tearing mode plasma

    International Nuclear Information System (INIS)

    Oikawa, T.; Suzuki, T.; Isayama, A.; Hayashi, N.; Fujita, T.; Naito, O.; Tuda, T.; Kurita, G.

    2005-01-01

    Evolution of the current density profile associated with magnetic island formation in a neoclassical tearing mode plasma is measured for the first time in JT-60U by using a motional Stark effect diagnostic. As the island grows, the current density profile turns flat at the radial region of the island and a hollow structure appears at the rational surface. As the island shrinks the deformed region becomes narrower and finally diminishes after the disappearance of the island. In a quiescent plasma without magnetohydrodynamic instabilities, on the other hand, no deformation is observed. The observed deformation in the current density profile associated with the tearing mode is reproduced in a time dependent transport simulation assuming the reduction of the bootstrap current in the radial region of the island. Comparison of the measurement with a calculated steady-state solution also shows that the reduction and recovery of the bootstrap current at the island explains the temporal behaviours of the current density and safety factor profiles. From the experimental observation and simulations, we reach the conclusion that the bootstrap current decreases within the island O-point

  4. Estimation of the limit of detection with a bootstrap-derived standard error by a partly non-parametric approach. Application to HPLC drug assays

    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...

  5. Quantitative functional failure analysis of a thermal-hydraulic passive system by means of bootstrapped Artificial Neural Networks

    International Nuclear Information System (INIS)

    Zio, E.; Apostolakis, G.E.; Pedroni, N.

    2010-01-01

    The estimation of the functional failure probability of a thermal-hydraulic (T-H) passive system can be done by Monte Carlo (MC) sampling of the epistemic uncertainties affecting the system model and the numerical values of its parameters, followed by the computation of the system response by a mechanistic T-H code, for each sample. The computational effort associated to this approach can be prohibitive because a large number of lengthy T-H code simulations must be performed (one for each sample) for accurate quantification of the functional failure probability and the related statistics. In this paper, the computational burden is reduced by replacing the long-running, original T-H code by a fast-running, empirical regression model: in particular, an Artificial Neural Network (ANN) model is considered. It is constructed on the basis of a limited-size set of data representing examples of the input/output nonlinear relationships underlying the original T-H code; once the model is built, it is used for performing, in an acceptable computational time, the numerous system response calculations needed for an accurate failure probability estimation, uncertainty propagation and sensitivity analysis. The empirical approximation of the system response provided by the ANN model introduces an additional source of (model) uncertainty, which needs to be evaluated and accounted for. A bootstrapped ensemble of ANN regression models is here built for quantifying, in terms of confidence intervals, the (model) uncertainties associated with the estimates provided by the ANNs. For demonstration purposes, an application to the functional failure analysis of an emergency passive decay heat removal system in a simple steady-state model of a Gas-cooled Fast Reactor (GFR) is presented. The functional failure probability of the system is estimated together with global Sobol sensitivity indices. The bootstrapped ANN regression model built with low computational time on few (e.g., 100) data

  6. Quantitative functional failure analysis of a thermal-hydraulic passive system by means of bootstrapped Artificial Neural Networks

    Energy Technology Data Exchange (ETDEWEB)

    Zio, E., E-mail: enrico.zio@polimi.i [Energy Department, Politecnico di Milano, Via Ponzio 34/3, 20133 Milan (Italy); Apostolakis, G.E., E-mail: apostola@mit.ed [Department of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139-4307 (United States); Pedroni, N. [Energy Department, Politecnico di Milano, Via Ponzio 34/3, 20133 Milan (Italy)

    2010-05-15

    The estimation of the functional failure probability of a thermal-hydraulic (T-H) passive system can be done by Monte Carlo (MC) sampling of the epistemic uncertainties affecting the system model and the numerical values of its parameters, followed by the computation of the system response by a mechanistic T-H code, for each sample. The computational effort associated to this approach can be prohibitive because a large number of lengthy T-H code simulations must be performed (one for each sample) for accurate quantification of the functional failure probability and the related statistics. In this paper, the computational burden is reduced by replacing the long-running, original T-H code by a fast-running, empirical regression model: in particular, an Artificial Neural Network (ANN) model is considered. It is constructed on the basis of a limited-size set of data representing examples of the input/output nonlinear relationships underlying the original T-H code; once the model is built, it is used for performing, in an acceptable computational time, the numerous system response calculations needed for an accurate failure probability estimation, uncertainty propagation and sensitivity analysis. The empirical approximation of the system response provided by the ANN model introduces an additional source of (model) uncertainty, which needs to be evaluated and accounted for. A bootstrapped ensemble of ANN regression models is here built for quantifying, in terms of confidence intervals, the (model) uncertainties associated with the estimates provided by the ANNs. For demonstration purposes, an application to the functional failure analysis of an emergency passive decay heat removal system in a simple steady-state model of a Gas-cooled Fast Reactor (GFR) is presented. The functional failure probability of the system is estimated together with global Sobol sensitivity indices. The bootstrapped ANN regression model built with low computational time on few (e.g., 100) data

  7. Bootstrap regularity for integro-differential operators and its application to nonlocal minimal surfaces

    OpenAIRE

    Barrera, Begoña Barrios; Figalli, Alessio; Valdinoci, Enrico

    2012-01-01

    We prove that $C^{1,\\alpha}$ $s$-minimal surfaces are automatically $C^\\infty$. For this, we develop a new bootstrap regularity theory for solutions of integro-differential equations of very general type, which we believe is of independent interest.

  8. High coking value pitch

    Science.gov (United States)

    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.

  9. Reanalysis of cancer mortality in Japanese A-bomb survivors exposed to low doses of radiation: bootstrap and simulation methods

    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

  10. Modeling, measurement, and 3-D equilibrium reconstruction of the bootstrap current in the Helically Symmetric Experiment

    Energy Technology Data Exchange (ETDEWEB)

    Schmitt, J. C.; Talmadge, J. N.; Anderson, D. T. [Department of Electrical and Computer Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Hanson, J. D. [Department of Physics, Auburn University, Auburn, Alabama 36849 (United States)

    2014-09-15

    The bootstrap current for three electron cyclotron resonance heated plasma scenarios in a quasihelically symmetric stellarator (the Helically Symmetric Experiment) are analyzed and compared to a neoclassical transport code PENTA. The three conditions correspond to 50 kW input power with a resonance that is off-axis, 50 kW on-axis heating and 100 kW on-axis heating. When the heating location was moved from off-axis to on-axis with 50 kW heating power, the stored energy and the extrapolated steady-state current were both observed to increase. When the on-axis heating power was increased from 50 kW to 100 kW, the stored energy continued to increase while the bootstrap current slightly decreased. This trend is qualitatively in agreement with the calculations which indicate that a large positive electric field for the 100 kW case was driving the current negative in a small region close to the magnetic axis and accounting for the decrease in the total integrated current. This trend in the calculations is only observed to occur when momentum conservation between particle species is included. Without momentum conservation, the calculated bootstrap current increases monotonically. We show that the magnitude of the bootstrap current as calculated by PENTA agrees better with the experiment when momentum conservation between plasma species is included in the calculation. The total current was observed in all cases to flow in a direction to unwind the transform, unlike in a tokamak in which the bootstrap current adds to the transform. The 3-D inductive response of the plasma is simulated to predict the evolution of the current profile during the discharge. The 3-D equilibrium reconstruction code V3FIT is used to reconstruct profiles of the plasma pressure and current constrained by measurements with a set of magnetic diagnostics. The reconstructed profiles are consistent with the measured plasma pressure profile and the simulated current profile when the

  11. Quantifying uncertainty on sediment loads using bootstrap confidence intervals

    Science.gov (United States)

    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.

  12. On Current Drive and Wave Induced Bootstrap Current in Toroidal Plasmas

    International Nuclear Information System (INIS)

    Hellsten, T.; Johnson, T.

    2008-01-01

    A comprehensive treatment of wave-particle interactions in toroidal plasmas including collisional relaxation, applicable to heating or anomalous wave induced transport, has been obtained by using Monte Carlo operators satisfying quasi-neutrality. This approach enables a self-consistent treatment of wave-particle interactions applicable to the banana regime in the neoclassical theory. It allows an extension into a regime with large temperature and density gradients, losses and transport of particles by wave-particle interactions making the method applicable to transport barriers. It is found that at large gradients the relationship between radial electric field, parallel velocity, temperature and density gradient in the neoclassical theory is modified such that coefficient in front of the logarithmic ion temperature gradient, which in the standard neoclassical theory is small and counteracts the electric field caused by the density gradient, now changes sign and contributes to the built up of the radial electric field. The possibility to drive current by absorbing the waves on trapped particles has been studied and how the wave-particle interactions affect the bootstrap current. Two new current drive mechanisms are studied: current drive by wave induced bootstrap current and selective detrapping into passing orbits by directed waves.

  13. Measuring and Benchmarking Technical Efficiency of Public Hospitals in Tianjin, China: A Bootstrap-Data Envelopment Analysis Approach.

    Science.gov (United States)

    Li, Hao; Dong, Siping

    2015-01-01

    China has long been stuck in applying traditional data envelopment analysis (DEA) models to measure technical efficiency of public hospitals without bias correction of efficiency scores. In this article, we have introduced the Bootstrap-DEA approach from the international literature to analyze the technical efficiency of public hospitals in Tianjin (China) and tried to improve the application of this method for benchmarking and inter-organizational learning. It is found that the bias corrected efficiency scores of Bootstrap-DEA differ significantly from those of the traditional Banker, Charnes, and Cooper (BCC) model, which means that Chinese researchers need to update their DEA models for more scientific calculation of hospital efficiency scores. Our research has helped shorten the gap between China and the international world in relative efficiency measurement and improvement of hospitals. It is suggested that Bootstrap-DEA be widely applied into afterward research to measure relative efficiency and productivity of Chinese hospitals so as to better serve for efficiency improvement and related decision making. © The Author(s) 2015.

  14. The Components of Income Inequality in Belgium : Applying the Shorrocks-Decomposition with Bootstrapping

    NARCIS (Netherlands)

    Dekkers, G.J.M.; Nelissen, J.H.M.

    2001-01-01

    We look at the contribution of various income components on income inequality and the changes in this in Belgium.Starting from the Shorrocks decomposition, we apply bootstrapping to construct confidence intervals for both the annual decomposition and the changes over time.It appears that the

  15. The use of vector bootstrapping to improve variable selection precision in Lasso models

    NARCIS (Netherlands)

    Laurin, C.; Boomsma, D.I.; Lubke, G.H.

    2016-01-01

    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.

  16. Benchmarking the efficiency of the Chilean water and sewerage companies: a double-bootstrap approach.

    Science.gov (United States)

    Molinos-Senante, María; Donoso, Guillermo; Sala-Garrido, Ramon; Villegas, Andrés

    2018-03-01

    Benchmarking the efficiency of water companies is essential to set water tariffs and to promote their sustainability. In doing so, most of the previous studies have applied conventional data envelopment analysis (DEA) models. However, it is a deterministic method that does not allow to identify environmental factors influencing efficiency scores. To overcome this limitation, this paper evaluates the efficiency of a sample of Chilean water and sewerage companies applying a double-bootstrap DEA model. Results evidenced that the ranking of water and sewerage companies changes notably whether efficiency scores are computed applying conventional or double-bootstrap DEA models. Moreover, it was found that the percentage of non-revenue water and customer density are factors influencing the efficiency of Chilean water and sewerage companies. This paper illustrates the importance of using a robust and reliable method to increase the relevance of benchmarking tools.

  17. Introduccción al Bootstrap: Desarrollo de un ejemplo acompañado de software de aplicación

    Directory of Open Access Journals (Sweden)

    Rubén Ledesma

    2008-09-01

    Full Text Available El bootstrap es un tipo de técnica de remuestreo de datos que permite resolver problemas relacionados con la estimación de intervalos de confianza o la prueba de significación estadística. Este enfoque puede resultar de interés para los investigadores en Psicología, no solo porque es menos restrictivo que el enfoque estadístico clásico, sino también porque es más general en su formulación y más simple de comprender en lo referente al procedimiento básico que subyace al método. En lugar de fórmulas o modelos matemáticos abstractos, el bootstrap simplemente requiere un ordenador capaz de simular un proceso de muestreo aleatorio de los datos. Sin embargo, y debido quizás a la escasa difusión de la técnica, los investigadores aún no han incorporado el bootstrap al repertorio habitual de herramientas de análisis de datos. En este trabajo realizamos una presentación conceptual del bootstrap, ilustramos la técnica mediante un ejemplo y revisamos algunas opciones disponibles en materia de software estadístico. El trabajo incluye además un programa para correr el ejemplo dentro de ViSta “The Visual Statistics System”, un sistema estadístico gratuito y abierto.

  18. Low mass diffractive dissociation in a simple t-dependent dual bootstrap model

    International Nuclear Information System (INIS)

    Bishari, M.

    1978-08-01

    The smallness of inelastic diffractive dissociation is explicitly demonstrated, in the framework of the '1/N dual unitarization' scheme, by incorporating a Deck type mechanism with the crucial planar bootstrap equation. Although both inelastic and elastic pomeron couplings are of the same order in 1/N, the origin for their smallness, however, is not identical. (author)

  19. 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.

  20. Genomic breeding value estimation using nonparametric additive regression models

    Directory of Open Access Journals (Sweden)

    Solberg Trygve

    2009-01-01

    Full Text Available Abstract Genomic selection refers to the use of genomewide dense markers for breeding value estimation and subsequently for selection. The main challenge of genomic breeding value estimation is the estimation of many effects from a limited number of observations. Bayesian methods have been proposed to successfully cope with these challenges. As an alternative class of models, non- and semiparametric models were recently introduced. The present study investigated the ability of nonparametric additive regression models to predict genomic breeding values. The genotypes were modelled for each marker or pair of flanking markers (i.e. the predictors separately. The nonparametric functions for the predictors were estimated simultaneously using additive model theory, applying a binomial kernel. The optimal degree of smoothing was determined by bootstrapping. A mutation-drift-balance simulation was carried out. The breeding values of the last generation (genotyped was predicted using data from the next last generation (genotyped and phenotyped. The results show moderate to high accuracies of the predicted breeding values. A determination of predictor specific degree of smoothing increased the accuracy.

  1. 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.

  2. Bootstrapping quarks and gluons

    International Nuclear Information System (INIS)

    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

  3. Tolerance limits and tolerance intervals for ratios of normal random variables using a bootstrap calibration.

    Science.gov (United States)

    Flouri, Marilena; Zhai, Shuyan; Mathew, Thomas; Bebu, Ionut

    2017-05-01

    This paper addresses the problem of deriving one-sided tolerance limits and two-sided tolerance intervals for a ratio of two random variables that follow a bivariate normal distribution, or a lognormal/normal distribution. The methodology that is developed uses nonparametric tolerance limits based on a parametric bootstrap sample, coupled with a bootstrap calibration in order to improve accuracy. The methodology is also adopted for computing confidence limits for the median of the ratio random variable. Numerical results are reported to demonstrate the accuracy of the proposed approach. The methodology is illustrated using examples where ratio random variables are of interest: an example on the radioactivity count in reverse transcriptase assays and an example from the area of cost-effectiveness analysis in health economics. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  4. Visuospatial bootstrapping: Binding useful visuospatial information during verbal working memory encoding does not require set-shifting executive resources.

    Science.gov (United States)

    Calia, Clara; Darling, Stephen; Havelka, Jelena; Allen, Richard J

    2018-05-01

    Immediate serial recall of digits is better when the digits are shown by highlighting them in a familiar array, such as a phone keypad, compared with presenting them serially in a single location, a pattern referred to as "visuospatial bootstrapping." This pattern implies the establishment of temporary links between verbal and spatial working memory, alongside access to information in long-term memory. However, the role of working memory control processes like those implied by the "Central Executive" in bootstrapping has not been directly investigated. Here, we report a study addressing this issue, focusing on executive processes of attentional shifting. Tasks in which information has to be sequenced are thought to be heavily dependent on shifting. Memory for digits presented in keypads versus single locations was assessed under two secondary task load conditions, one with and one without a sequencing requirement, and hence differing in the degree to which they invoke shifting. Results provided clear evidence that multimodal binding (visuospatial bootstrapping) can operate independently of this form of executive control process.

  5. ASİMETRİK VE AĞIR KUYRUKLU DAĞILIMLARIN KONUM PARAMETRESİNİN BOOTSTRAP GÜVEN ARALIKLARI İÇİN BİR BENZETİM ÇALIŞMASI

    Directory of Open Access Journals (Sweden)

    Engin YILDIZTEPE

    2015-05-01

    Full Text Available Bootstrap methodology is a modern statistical tool which enables us makin g statistical inference when the sampling distribution of the estimator is not known. Although the underlying idea is the same in all bootstrap methods, one might come across so many variations in tthe literature. In this study, the coverage accuracy of four most commonly used bootstrap confidence interval methods was assessed for various asymmetr c and heavy tailed distributions with an exh austive Monte Carlo simulation. In most of the cases, it has been found that the coverage accuracy of bootstrap percentile method is close to nominal for robust estimators of location.

  6. RETORNOS DE LA EDUCACION PÚBLICA Y PRIVADA: INFERENCIA ASINTOTICA Y BOOTSTRAP EN MEDIDAS DE DESIGUALDAD

    Directory of Open Access Journals (Sweden)

    Milenka Ocampo

    2009-01-01

    Full Text Available El presente trabajo muestra, en base a evidencia empírica, que las diferencias entre la educación pública y privada han acentuado en el tiempo la desigualdad de ingresos existente en Bolivia. Inicialmente, se realiza un análisis descriptivo de las diferencias en calidad, infraestructura y cobertura entre la educación pública y privada. Posteriormente, empleando técnicas microeconométricas y tests de hipótesis bajo Bootstrap, se verifica que las diferencias entre ambos tipos de educación son significativas para explicar una parte de la desigualdad de ingresos generada entre 1999 y 2006 en Bolivia. Adicionalmente, se aplican el método Bootstrap Moon para  asegurar la robustez de los resultados.

  7. Multinomial Logistic Regression & Bootstrapping for Bayesian Estimation of Vertical Facies Prediction in Heterogeneous Sandstone Reservoirs

    Science.gov (United States)

    Al-Mudhafar, W. J.

    2013-12-01

    Precisely prediction of rock facies leads to adequate reservoir characterization by improving the porosity-permeability relationships to estimate the properties in non-cored intervals. It also helps to accurately identify the spatial facies distribution to perform an accurate reservoir model for optimal future reservoir performance. In this paper, the facies estimation has been done through Multinomial logistic regression (MLR) with respect to the well logs and core data in a well in upper sandstone formation of South Rumaila oil field. The entire independent variables are gamma rays, formation density, water saturation, shale volume, log porosity, core porosity, and core permeability. Firstly, Robust Sequential Imputation Algorithm has been considered to impute the missing data. This algorithm starts from a complete subset of the dataset and estimates sequentially the missing values in an incomplete observation by minimizing the determinant of the covariance of the augmented data matrix. Then, the observation is added to the complete data matrix and the algorithm continues with the next observation with missing values. The MLR has been chosen to estimate the maximum likelihood and minimize the standard error for the nonlinear relationships between facies & core and log data. The MLR is used to predict the probabilities of the different possible facies given each independent variable by constructing a linear predictor function having a set of weights that are linearly combined with the independent variables by using a dot product. Beta distribution of facies has been considered as prior knowledge and the resulted predicted probability (posterior) has been estimated from MLR based on Baye's theorem that represents the relationship between predicted probability (posterior) with the conditional probability and the prior knowledge. To assess the statistical accuracy of the model, the bootstrap should be carried out to estimate extra-sample prediction error by randomly

  8. Off-critical statistical models: factorized scattering theories and bootstrap program

    International Nuclear Information System (INIS)

    Mussardo, G.

    1992-01-01

    We analyze those integrable statistical systems which originate from some relevant perturbations of the minimal models of conformal field theories. When only massive excitations are present, the systems can be efficiently characterized in terms of the relativistic scattering data. We review the general properties of the factorizable S-matrix in two dimensions with particular emphasis on the bootstrap principle. The classification program of the allowed spins of conserved currents and of the non-degenerate S-matrices is discussed and illustrated by means of some significant examples. The scattering theories of several massive perturbations of the minimal models are fully discussed. Among them are the Ising model, the tricritical Ising model, the Potts models, the series of the non-unitary minimal models M 2,2n+3 , the non-unitary model M 3,5 and the scaling limit of the polymer system. The ultraviolet limit of these massive integrable theories can be exploited by the thermodynamics Bethe ansatz, in particular the central charge of the original conformal theories can be recovered from the scattering data. We also consider the numerical method based on the so-called conformal space truncated approach which confirms the theoretical results and allows a direct measurement of the scattering data, i.e. the masses and the S-matrix of the particles in bootstrap interaction. The problem of computing the off-critical correlation functions is discussed in terms of the form-factor approach

  9. A symbol of uniqueness: the cluster bootstrap for the 3-loop MHV heptagon

    Energy Technology Data Exchange (ETDEWEB)

    Drummond, J.M. [School of Physics & Astronomy, University of Southampton, Highfield, Southampton, SO17 1BJ (United Kingdom); Theory Division, Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); LAPTh, CNRS, Université de Savoie, F-74941 Annecy-le-Vieux Cedex (France); Papathanasiou, G. [LAPTh, CNRS, Université de Savoie, F-74941 Annecy-le-Vieux Cedex (France); Spradlin, M. [Department of Physics, Brown University, Providence, RI 02912 (United States)

    2015-03-16

    Seven-particle scattering amplitudes in planar super-Yang-Mills theory are believed to belong to a special class of generalised polylogarithm functions called heptagon functions. These are functions with physical branch cuts whose symbols may be written in terms of the 42 cluster A-coordinates on Gr (4,7). Motivated by the success of the hexagon bootstrap programme for constructing six-particle amplitudes we initiate the systematic study of the symbols of heptagon functions. We find that there is exactly one such symbol of weight six which satisfies the MHV last-entry condition and is finite in the 7∥6 collinear limit. This unique symbol is both dihedral and parity-symmetric, and remarkably its collinear limit is exactly the symbol of the three-loop six-particle MHV amplitude, although none of these properties were assumed a priori. It must therefore be the symbol of the three-loop seven-particle MHV amplitude. The simplicity of its construction suggests that the n-gon bootstrap may be surprisingly powerful for n>6.

  10. The use of bootstrap methods for analysing health-related quality of life outcomes (particularly the SF-36

    Directory of Open Access Journals (Sweden)

    Campbell Michael J

    2004-12-01

    Full Text Available Abstract Health-Related Quality of Life (HRQoL measures are becoming increasingly used in clinical trials as primary outcome measures. Investigators are now asking statisticians for advice on how to analyse studies that have used HRQoL outcomes. HRQoL outcomes, like the SF-36, are usually measured on an ordinal scale. However, most investigators assume that there exists an underlying continuous latent variable that measures HRQoL, and that the actual measured outcomes (the ordered categories, reflect contiguous intervals along this continuum. The ordinal scaling of HRQoL measures means they tend to generate data that have discrete, bounded and skewed distributions. Thus, standard methods of analysis such as the t-test and linear regression that assume Normality and constant variance may not be appropriate. For this reason, conventional statistical advice would suggest that non-parametric methods be used to analyse HRQoL data. The bootstrap is one such computer intensive non-parametric method for analysing data. We used the bootstrap for hypothesis testing and the estimation of standard errors and confidence intervals for parameters, in four datasets (which illustrate the different aspects of study design. We then compared and contrasted the bootstrap with standard methods of analysing HRQoL outcomes. The standard methods included t-tests, linear regression, summary measures and General Linear Models. Overall, in the datasets we studied, using the SF-36 outcome, bootstrap methods produce results similar to conventional statistical methods. This is likely because the t-test and linear regression are robust to the violations of assumptions that HRQoL data are likely to cause (i.e. non-Normality. While particular to our datasets, these findings are likely to generalise to other HRQoL outcomes, which have discrete, bounded and skewed distributions. Future research with other HRQoL outcome measures, interventions and populations, is required to

  11. A Computational Tool for Testing Dose-related Trend Using an Age-adjusted Bootstrap-based Poly-k Test

    Directory of Open Access Journals (Sweden)

    Hojin Moon

    2006-08-01

    Full Text Available A computational tool for testing for a dose-related trend and/or a pairwise difference in the incidence of an occult tumor via an age-adjusted bootstrap-based poly-k test and the original poly-k test is presented in this paper. The poly-k test (Bailer and Portier 1988 is a survival-adjusted Cochran-Armitage test, which achieves robustness to effects of differential mortality across dose groups. The original poly-k test is asymptotically standard normal under the null hypothesis. However, the asymptotic normality is not valid if there is a deviation from the tumor onset distribution that is assumed in this test. Our age-adjusted bootstrap-based poly-k test assesses the significance of assumed asymptotic normal tests and investigates an empirical distribution of the original poly-k test statistic using an age-adjusted bootstrap method. A tumor of interest is an occult tumor for which the time to onset is not directly observable. Since most of the animal carcinogenicity studies are designed with a single terminal sacrifice, the present tool is applicable to rodent tumorigenicity assays that have a single terminal sacrifice. The present tool takes input information simply from a user screen and reports testing results back to the screen through a user-interface. The computational tool is implemented in C/C++ and is applied to analyze a real data set as an example. Our tool enables the FDA and the pharmaceutical industry to implement a statistical analysis of tumorigenicity data from animal bioassays via our age-adjusted bootstrap-based poly-k test and the original poly-k test which has been adopted by the National Toxicology Program as its standard statistical test.

  12. arXiv The S-matrix Bootstrap II: Two Dimensional Amplitudes

    CERN Document Server

    Paulos, Miguel F.; Toledo, Jonathan; van Rees, Balt C.; Vieira, Pedro

    2017-11-22

    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.

  13. A neurocomputational theory of how explicit learning bootstraps early procedural learning.

    Science.gov (United States)

    Paul, Erick J; Ashby, F Gregory

    2013-01-01

    It is widely accepted that human learning and memory is mediated by multiple memory systems that are each best suited to different requirements and demands. Within the domain of categorization, at least two systems are thought to facilitate learning: an explicit (declarative) system depending largely on the prefrontal cortex, and a procedural (non-declarative) system depending on the basal ganglia. Substantial evidence suggests that each system is optimally suited to learn particular categorization tasks. However, it remains unknown precisely how these systems interact to produce optimal learning and behavior. In order to investigate this issue, the present research evaluated the progression of learning through simulation of categorization tasks using COVIS, a well-known model of human category learning that includes both explicit and procedural learning systems. Specifically, the model's parameter space was thoroughly explored in procedurally learned categorization tasks across a variety of conditions and architectures to identify plausible interaction architectures. The simulation results support the hypothesis that one-way interaction between the systems occurs such that the explicit system "bootstraps" learning early on in the procedural system. Thus, the procedural system initially learns a suboptimal strategy employed by the explicit system and later refines its strategy. This bootstrapping could be from cortical-striatal projections that originate in premotor or motor regions of cortex, or possibly by the explicit system's control of motor responses through basal ganglia-mediated loops.

  14. Attention! Can choices for low value food over high value food be trained?

    Science.gov (United States)

    Zoltak, Michael J; Veling, Harm; Chen, Zhang; Holland, Rob W

    2018-05-01

    People choose high value food items over low value food items, because food choices are guided by the comparison of values placed upon choice alternatives. This value comparison process is also influenced by the amount of attention people allocate to different items. Recent research shows that choices for food items can be increased by training attention toward these items, with a paradigm named cued-approach training (CAT). However, previous work till now has only examined the influence of CAT on choices between two equally valued items. It has remained unclear whether CAT can increase choices for low value items when people choose between a low and high value food item. To address this question in the current study participants were cued to make rapid responses in CAT to certain low and high value items. Next, they made binary choices between low and high value items, where we systematically varied whether the low and high value items were cued or uncued. In two experiments, we found that participants overall preferred high over low value food items for real consumption. More important, their choices for low value items increased when only the low value item had been cued in CAT compared to when both low and high value items had not been cued. Exploratory analyses revealed that this effect was more pronounced for participants with a relatively small value difference between low and high value items. The present research thus suggests that CAT may be used to boost the choice and consumption of low value items via enhanced attention toward these items, as long as the value difference is not too large. Implications for facilitating choices for healthy food are discussed. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. A Bootstrap Approach to Computing Uncertainty in Inferred Oil and Gas Reserve Estimates

    International Nuclear Information System (INIS)

    Attanasi, Emil D.; Coburn, Timothy C.

    2004-01-01

    This study develops confidence intervals for estimates of inferred oil and gas reserves based on bootstrap procedures. Inferred reserves are expected additions to proved reserves in previously discovered conventional oil and gas fields. Estimates of inferred reserves accounted for 65% of the total oil and 34% of the total gas assessed in the U.S. Geological Survey's 1995 National Assessment of oil and gas in US onshore and State offshore areas. When the same computational methods used in the 1995 Assessment are applied to more recent data, the 80-year (from 1997 through 2076) inferred reserve estimates for pre-1997 discoveries located in the lower 48 onshore and state offshore areas amounted to a total of 39.7 billion barrels of oil (BBO) and 293 trillion cubic feet (TCF) of gas. The 90% confidence interval about the oil estimate derived from the bootstrap approach is 22.4 BBO to 69.5 BBO. The comparable 90% confidence interval for the inferred gas reserve estimate is 217 TCF to 413 TCF. The 90% confidence interval describes the uncertainty that should be attached to the estimates. It also provides a basis for developing scenarios to explore the implications for energy policy analysis

  16. Analytic bounds and emergence of AdS{sub 2} physics from the conformal bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Mazáč, Dalimil [Perimeter Institute for Theoretical Physics,Waterloo, ON N2L 2Y5 (Canada); Department of Physics and Astronomy, University of Waterloo,ON N2L 3G1 (Canada)

    2017-04-26

    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 AdS{sub 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.

  17. Exploration of the factor structure of the Kirton Adaption-Innovation Inventory using bootstrapping estimation.

    Science.gov (United States)

    Im, Subin; Min, Soonhong

    2013-04-01

    Exploratory factor analyses of the Kirton Adaption-Innovation Inventory (KAI), which serves to measure individual cognitive styles, generally indicate three factors: sufficiency of originality, efficiency, and rule/group conformity. In contrast, a 2005 study by Im and Hu using confirmatory factor analysis supported a four-factor structure, dividing the sufficiency of originality dimension into two subdimensions, idea generation and preference for change. This study extends Im and Hu's (2005) study of a derived version of the KAI by providing additional evidence of the four-factor structure. Specifically, the authors test the robustness of the parameter estimates to the violation of normality assumptions in the sample using bootstrap methods. A bias-corrected confidence interval bootstrapping procedure conducted among a sample of 356 participants--members of the Arkansas Household Research Panel, with middle SES and average age of 55.6 yr. (SD = 13.9)--showed that the four-factor model with two subdimensions of sufficiency of originality fits the data significantly better than the three-factor model in non-normality conditions.

  18. A Bootstrap Metropolis-Hastings Algorithm for Bayesian Analysis of Big Data.

    Science.gov (United States)

    Liang, Faming; Kim, Jinsu; Song, Qifan

    2016-01-01

    Markov chain Monte Carlo (MCMC) methods have proven to be a very powerful tool for analyzing data of complex structures. However, their computer-intensive nature, which typically require a large number of iterations and a complete scan of the full dataset for each iteration, precludes their use for big data analysis. In this paper, we propose the so-called bootstrap Metropolis-Hastings (BMH) algorithm, which provides a general framework for how to tame powerful MCMC methods to be used for big data analysis; that is to replace the full data log-likelihood by a Monte Carlo average of the log-likelihoods that are calculated in parallel from multiple bootstrap samples. The BMH algorithm possesses an embarrassingly parallel structure and avoids repeated scans of the full dataset in iterations, and is thus feasible for big data problems. Compared to the popular divide-and-combine method, BMH can be generally more efficient as it can asymptotically integrate the whole data information into a single simulation run. The BMH algorithm is very flexible. Like the Metropolis-Hastings algorithm, it can serve as a basic building block for developing advanced MCMC algorithms that are feasible for big data problems. This is illustrated in the paper by the tempering BMH algorithm, which can be viewed as a combination of parallel tempering and the BMH algorithm. BMH can also be used for model selection and optimization by combining with reversible jump MCMC and simulated annealing, respectively.

  19. A Bootstrap Metropolis–Hastings Algorithm for Bayesian Analysis of Big Data

    Science.gov (United States)

    Kim, Jinsu; Song, Qifan

    2016-01-01

    Markov chain Monte Carlo (MCMC) methods have proven to be a very powerful tool for analyzing data of complex structures. However, their computer-intensive nature, which typically require a large number of iterations and a complete scan of the full dataset for each iteration, precludes their use for big data analysis. In this paper, we propose the so-called bootstrap Metropolis-Hastings (BMH) algorithm, which provides a general framework for how to tame powerful MCMC methods to be used for big data analysis; that is to replace the full data log-likelihood by a Monte Carlo average of the log-likelihoods that are calculated in parallel from multiple bootstrap samples. The BMH algorithm possesses an embarrassingly parallel structure and avoids repeated scans of the full dataset in iterations, and is thus feasible for big data problems. Compared to the popular divide-and-combine method, BMH can be generally more efficient as it can asymptotically integrate the whole data information into a single simulation run. The BMH algorithm is very flexible. Like the Metropolis-Hastings algorithm, it can serve as a basic building block for developing advanced MCMC algorithms that are feasible for big data problems. This is illustrated in the paper by the tempering BMH algorithm, which can be viewed as a combination of parallel tempering and the BMH algorithm. BMH can also be used for model selection and optimization by combining with reversible jump MCMC and simulated annealing, respectively. PMID:29033469

  20. A Neurocomputational Theory of how Explicit Learning Bootstraps Early Procedural Learning

    Directory of Open Access Journals (Sweden)

    Erick Joseph Paul

    2013-12-01

    Full Text Available It is widely accepted that human learning and memory is mediated by multiple memory systems that are each best suited to different requirements and demands. Within the domain of categorization, at least two systems are thought to facilitate learning: an explicit (declarative system depending largely on the prefrontal cortex, and a procedural (non-declarative system depending on the basal ganglia. Substantial evidence suggests that each system is optimally suited to learn particular categorization tasks. However, it remains unknown precisely how these systems interact to produce optimal learning and behavior. In order to investigate this issue, the present research evaluated the progression of learning through simulation of categorization tasks using COVIS, a well-known model of human category learning that includes both explicit and procedural learning systems. Specifically, the model's parameter space was thoroughly explored in procedurally learned categorization tasks across a variety of conditions and architectures to identify plausible interaction architectures. The simulation results support the hypothesis that one-way interaction between the systems occurs such that the explicit system "bootstraps" learning early on in the procedural system. Thus, the procedural system initially learns a suboptimal strategy employed by the explicit system and later refines its strategy. This bootstrapping could be from cortical-striatal projections that originate in premotor or motor regions of cortex, or possibly by the explicit system’s control of motor responses through basal ganglia-mediated loops.

  1. Learning Curves and Bootstrap Estimates for Inference with Gaussian Processes: A Statistical Mechanics Study

    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 Gaussian processes, we discuss Bootstrap estimates for learning curves....

  2. Forecasting Model for IPTV Service in Korea Using Bootstrap Ridge Regression Analysis

    Science.gov (United States)

    Lee, Byoung Chul; Kee, Seho; Kim, Jae Bum; Kim, Yun Bae

    The telecom firms in Korea are taking new step to prepare for the next generation of convergence services, IPTV. In this paper we described our analysis on the effective method for demand forecasting about IPTV broadcasting. We have tried according to 3 types of scenarios based on some aspects of IPTV potential market and made a comparison among the results. The forecasting method used in this paper is the multi generation substitution model with bootstrap ridge regression analysis.

  3. Bootstrapping the economy -- a non-parametric method of generating consistent future scenarios

    OpenAIRE

    Müller, Ulrich A; Bürgi, Roland; Dacorogna, Michel M

    2004-01-01

    The fortune and the risk of a business venture depends on the future course of the economy. There is a strong demand for economic forecasts and scenarios that can be applied to planning and modeling. While there is an ongoing debate on modeling economic scenarios, the bootstrapping (or resampling) approach presented here has several advantages. As a non-parametric method, it directly relies on past market behaviors rather than debatable assumptions on models and parameters. Simultaneous dep...

  4. 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.

  5. Probabilistic sensitivity analysis incorporating the bootstrap: an example comparing treatments for the eradication of Helicobacter pylori.

    Science.gov (United States)

    Pasta, D J; Taylor, J L; Henning, J M

    1999-01-01

    Decision-analytic models are frequently used to evaluate the relative costs and benefits of alternative therapeutic strategies for health care. Various types of sensitivity analysis are used to evaluate the uncertainty inherent in the models. Although probabilistic sensitivity analysis is more difficult theoretically and computationally, the results can be much more powerful and useful than deterministic sensitivity analysis. The authors show how a Monte Carlo simulation can be implemented using standard software to perform a probabilistic sensitivity analysis incorporating the bootstrap. The method is applied to a decision-analytic model evaluating the cost-effectiveness of Helicobacter pylori eradication. The necessary steps are straightforward and are described in detail. The use of the bootstrap avoids certain difficulties encountered with theoretical distributions. The probabilistic sensitivity analysis provided insights into the decision-analytic model beyond the traditional base-case and deterministic sensitivity analyses and should become the standard method for assessing sensitivity.

  6. Bootstrap-DEA analysis of BRICS’ energy efficiency based on small sample data

    International Nuclear Information System (INIS)

    Song, Ma-Lin; Zhang, Lin-Ling; Liu, Wei; Fisher, Ron

    2013-01-01

    Highlights: ► The BRICS’ economies have flourished with increasingly energy consumptions. ► The analyses and comparison of energy efficiency are conducted among the BRICS. ► As a whole, there is low energy efficiency but a growing trend of BRICS. ► The BRICS should adopt relevant energy policies based on their own conditions. - Abstract: As a representative of many emerging economies, BRICS’ economies have been greatly developed in recent years. Meanwhile, the proportion of energy consumption of BRICS to the whole world consumption has increased. Therefore, it is significant to analyze and compare the energy efficiency among them. This paper firstly utilizes a Super-SBM model to measure and calculate the energy efficiency of BRICS, then analyzes their present status and development trend. Further, Bootstrap is applied to modify the values based on DEA derived from small sample data, and finally the relationship between energy efficiency and carbon emissions is measured. Results show that energy efficiency of BRICS as a whole is low but has a quickly increasing trend. Also, the relationship between energy efficiency and carbon emissions vary from country to country because of their different energy structures. The governments of BRICS should make some relevant energy policies according to their own conditions

  7. A bootstrap based analysis pipeline for efficient classification of phylogenetically related animal miRNAs

    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.

  8. Bootstrap resampling: a powerful method of assessing confidence intervals for doses from experimental data

    International Nuclear Information System (INIS)

    Iwi, G.; Millard, R.K.; Palmer, A.M.; Preece, A.W.; Saunders, M.

    1999-01-01

    Bootstrap resampling provides a versatile and reliable statistical method for estimating the accuracy of quantities which are calculated from experimental data. It is an empirically based method, in which large numbers of simulated datasets are generated by computer from existing measurements, so that approximate confidence intervals of the derived quantities may be obtained by direct numerical evaluation. A simple introduction to the method is given via a detailed example of estimating 95% confidence intervals for cumulated activity in the thyroid following injection of 99m Tc-sodium pertechnetate using activity-time data from 23 subjects. The application of the approach to estimating confidence limits for the self-dose to the kidney following injection of 99m Tc-DTPA organ imaging agent based on uptake data from 19 subjects is also illustrated. Results are then given for estimates of doses to the foetus following administration of 99m Tc-sodium pertechnetate for clinical reasons during pregnancy, averaged over 25 subjects. The bootstrap method is well suited for applications in radiation dosimetry including uncertainty, reliability and sensitivity analysis of dose coefficients in biokinetic models, but it can also be applied in a wide range of other biomedical situations. (author)

  9. 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.

  10. Bootstrap current control studies in the Wendelstein 7-X stellarator using the free-plasma-boundary version of the SIESTA MHD equilibrium code

    Science.gov (United States)

    Peraza-Rodriguez, H.; Reynolds-Barredo, J. M.; Sanchez, R.; Tribaldos, V.; Geiger, J.

    2018-02-01

    The recently developed free-plasma-boundary version of the SIESTA MHD equilibrium code (Hirshman et al 2011 Phys. Plasmas 18 062504; Peraza-Rodriguez et al 2017 Phys. Plasmas 24 082516) is used for the first time to study scenarios with considerable bootstrap currents for the Wendelstein 7-X (W7-X) stellarator. Bootstrap currents in the range of tens of kAs can lead to the formation of unwanted magnetic island chains or stochastic regions within the plasma and alter the boundary rotational transform due to the small shear in W7-X. The latter issue is of relevance since the island divertor operation of W7-X relies on a proper positioning of magnetic island chains at the plasma edge to control the particle and energy exhaust towards the divertor plates. Two scenarios are examined with the new free-plasma-boundary capabilities of SIESTA: a freely evolving bootstrap current one that illustrates the difficulties arising from the dislocation of the boundary islands, and a second one in which off-axis electron cyclotron current drive (ECCD) is applied to compensate the effects of the bootstrap current and keep the island divertor configuration intact. SIESTA finds that off-axis ECCD is indeed able to keep the location and phase of the edge magnetic island chain unchanged, but it may also lead to an undesired stochastization of parts of the confined plasma if the EC deposition radial profile becomes too narrow.

  11. An algebraic approach to the analytic bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Alday, Luis F. [Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG (United Kingdom); Zhiboedov, Alexander [Center for the Fundamental Laws of Nature, Harvard University, Cambridge, MA 02138 (United States)

    2017-04-27

    We develop an algebraic approach to the analytic bootstrap in CFTs. By acting with the Casimir operator on the crossing equation we map the problem of doing large spin sums to any desired order to the problem of solving a set of recursion relations. We compute corrections to the anomalous dimension of large spin operators due to the exchange of a primary and its descendants in the crossed channel and show that this leads to a Borel-summable expansion. We analyse higher order corrections to the microscopic CFT data in the direct channel and its matching to infinite towers of operators in the crossed channel. We apply this method to the critical O(N) model. At large N we reproduce the first few terms in the large spin expansion of the known two-loop anomalous dimensions of higher spin currents in the traceless symmetric representation of O(N) and make further predictions. At small N we present the results for the truncated large spin expansion series of anomalous dimensions of higher spin currents.

  12. Academic Carelessness, Bootstrapping, and the Cybernetic Investigator

    Directory of Open Access Journals (Sweden)

    Hannah Drayson

    2017-11-01

    Full Text Available The following discussion is concerned with certain forms of poor practice in academic publishing that give rise to “academic urban legends.” It suggests that rather than simply consider phenomena such as poor citation practices and circular reporting as mistakes, misunderstandings, and evidence of lack of rigor, we might also read them as evidence of a particular kind of creativity—for which misunderstandings, assump-tions, and failures of diligence are mechanisms by which potentially influential ideas manifest. Reflecting particularly on a critique of the debate surrounding pharmaceutical cognitive enhancement and its use by university staff and students, the following will argue that investigators within the disciplines concerned with the effects or development of these technologies are themselves implicated as potential subjects. Alongside reflections from science fiction studies that offer insights into the experiential dimension of reading and misreading, this paper offers some insights regarding how we might think of mistakes and misunderstandings as a form of bootstrapping and a source of creativity in scientific and technological development.

  13. Improved inference in the evaluation of mutual fund performance using panel bootstrap methods

    OpenAIRE

    Blake, David; Caulfield, Tristan; Ioannidis, Christos; Tonks, I P

    2014-01-01

    Two new methodologies are introduced to improve inference in the evaluation of mutual fund performance against benchmarks. First, the benchmark models are estimated using panel methods with both fund and time effects. Second, the non-normality of individual mutual fund returns is accounted for by using panel bootstrap methods. We also augment the standard benchmark factors with fund-specific characteristics, such as fund size. Using a dataset of UK equity mutual fund returns, we find that fun...

  14. The lightcone bootstrap and the spectrum of the 3d Ising CFT

    Energy Technology Data Exchange (ETDEWEB)

    Simmons-Duffin, David [School of Natural Sciences, Institute for Advanced Study, Princeton, New Jersey 08540 (United States); Walter Burke Institute for Theoretical Physics, Caltech, Pasadena, California 91125 (United States)

    2017-03-15

    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 {Δ_σ,Δ_ϵ,f_σ_σ_ϵ,f_ϵ_ϵ_ϵ,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.

  15. VENUS+δf - A bootstrap current calculation module for 3D configurations

    International Nuclear Information System (INIS)

    Isaev, M.Yu.; Brunner, S.; Cooper, W.A.; Tran, T.M.; Bergmann, A.; Beidler, C.D.; Geiger, J.; Maassberg, H.; Nuehrenberg, J.; Schmidt, M.

    2005-01-01

    We present a new 3D code VENUS+δf for neoclassical transport calculations in nonaxisymmetric toroidal systems. Numerical drift orbits from the original VENUS code and the δf method for tokamak transport calculations are combined. The first results obtained with VENUS+δf are compared with neoclassical theory for different collisional regimes in a JT-60 tokamak test case with monoenergetic particles and with a Maxwellian distribution. Benchmarks with DKES code results for the bootstrap current in the W7X configuration as well as further VENUS+δf developments are discussed. (author)

  16. A Bootstrapping Model of Frequency and Context Effects in Word Learning.

    Science.gov (United States)

    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.

  17. Bootstrap-based procedures for inference in nonparametric receiver-operating characteristic curve regression analysis.

    Science.gov (United States)

    Rodríguez-Álvarez, María Xosé; Roca-Pardiñas, Javier; Cadarso-Suárez, Carmen; Tahoces, Pablo G

    2018-03-01

    Prior to using a diagnostic test in a routine clinical setting, the rigorous evaluation of its diagnostic accuracy is essential. The receiver-operating characteristic curve is the measure of accuracy most widely used for continuous diagnostic tests. However, the possible impact of extra information about the patient (or even the environment) on diagnostic accuracy also needs to be assessed. In this paper, we focus on an estimator for the covariate-specific receiver-operating characteristic curve based on direct regression modelling and nonparametric smoothing techniques. This approach defines the class of generalised additive models for the receiver-operating characteristic curve. The main aim of the paper is to offer new inferential procedures for testing the effect of covariates on the conditional receiver-operating characteristic curve within the above-mentioned class. Specifically, two different bootstrap-based tests are suggested to check (a) the possible effect of continuous covariates on the receiver-operating characteristic curve and (b) the presence of factor-by-curve interaction terms. The validity of the proposed bootstrap-based procedures is supported by simulations. To facilitate the application of these new procedures in practice, an R-package, known as npROCRegression, is provided and briefly described. Finally, data derived from a computer-aided diagnostic system for the automatic detection of tumour masses in breast cancer is analysed.

  18. Performance of mutual equity funds in Brazil – A bootstrap analysis

    Directory of Open Access Journals (Sweden)

    Marco Antonio Laes

    2014-09-01

    Full Text Available This article reports a study on the performance of mutual equity funds in Brazil from January 2002 to August 2012. For the analyses, Carhart's four-factor model is used as the benchmark for performance, and bootstrap procedures are applied to separate skill from luck. The results show that returns of the best performers are more due to luck than skill of their managers. For the bottom ranked funds, on the contrary, there is statistical evidence that their poor performance is caused mainly by bad management, rather than by bad luck. It is also showed that the largest funds perform better than the small or middle-sized funds.

  19. How efficient are Greek hospitals? A case study using a double bootstrap DEA approach.

    Science.gov (United States)

    Kounetas, Kostas; Papathanassopoulos, Fotis

    2013-12-01

    The purpose of this study was to measure Greek hospital performance using different input-output combinations, and to identify the factors that influence their efficiency thus providing policy makers with valuable input for the decision-making process. Using a unique dataset, we estimated the productive efficiency of each hospital through a bootstrapped data envelopment analysis (DEA) approach. In a second stage, we explored, using a bootstrapped truncated regression, the impact of environmental factors on hospitals' technical and scale efficiency. Our results reveal that over 80% of the examined hospitals appear to have a technical efficiency lower than 0.8, while the majority appear to be scale efficient. Moreover, efficiency performance differed with inclusion of medical examinations as an additional variable. On the other hand, bed occupancy ratio appeared to affect both technical and scale efficiency in a rather interesting way, while the adoption of advanced medical equipment and the type of hospital improves scale and technical efficiency, correspondingly. The findings of this study on Greek hospitals' performance are not encouraging. Furthermore, our results raise questions regarding the number of hospitals that should operate, and which type of hospital is more efficient. Finally, the results indicate the role of medical equipment in performance, confirming its misallocation in healthcare expenditure.

  20. Integral equations of hadronic correlation functions a functional- bootstrap approach

    CERN Document Server

    Manesis, E K

    1974-01-01

    A reasonable 'microscopic' foundation of the Feynman hadron-liquid analogy is offered, based on a class of models for hadron production. In an external field formalism, the equivalence (complementarity) of the exclusive and inclusive descriptions of hadronic reactions is specifically expressed in a functional-bootstrap form, and integral equations between inclusive and exclusive correlation functions are derived. Using the latest CERN-ISR data on the two-pion inclusive correlation function, and assuming rapidity translational invariance for the exclusive one, the simplest integral equation is solved in the 'central region' and an exclusive correlation length in rapidity predicted. An explanation is also offered for the unexpected similarity observed between pi /sup +/ pi /sup -/ and pi /sup -/ pi /sup -/ inclusive correlations. (31 refs).

  1. Nuclear energy consumption, oil consumption and economic growth in G-6 countries: Bootstrap panel causality test

    International Nuclear Information System (INIS)

    Chu, Hsiao-Ping; Chang Tsangyao

    2012-01-01

    This study applies bootstrap panel Granger causality to test whether energy consumption promotes economic growth using data from G-6 countries over the period of 1971–2010. Both nuclear and oil consumption data are used in this study. Regarding the nuclear consumption-economic growth nexus, nuclear consumption causes economic growth in Japan, the UK, and the US; economic growth causes nuclear consumption in the US; nuclear consumption and economic growth show no causal relation in Canada, France and Germany. Regarding oil consumption-economic growth nexus, we find that there is one-way causality from economic growth to oil consumption only in the US, and that oil consumption does not Granger cause economic growth in G-6 countries except Germany and Japan. Our results have important policy implications for the G-6 countries within the context of economic development. - Highlights: ► Bootstrap panel Granger causality test whether energy consumption promotes economic growth. ► Data from G-6 countries for both nuclear and oil consumption data are used. ► Results have important policy implications within the context of economic development.

  2. Measurement of total angular momentum values of high-lying even ...

    Indian Academy of Sciences (India)

    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 ...

  3. 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.

  4. Quantum bootstrapping via compressed quantum Hamiltonian learning

    International Nuclear Information System (INIS)

    Wiebe, Nathan; Granade, Christopher; Cory, D G

    2015-01-01

    A major problem facing the development of quantum computers or large scale quantum simulators is that general methods for characterizing and controlling are intractable. We provide a new approach to this problem that uses small quantum simulators to efficiently characterize and learn control models for larger devices. Our protocol achieves this by using Bayesian inference in concert with Lieb–Robinson bounds and interactive quantum learning methods to achieve compressed simulations for characterization. We also show that the Lieb–Robinson velocity is epistemic for our protocol, meaning that information propagates at a rate that depends on the uncertainty in the system Hamiltonian. We illustrate the efficiency of our bootstrapping protocol by showing numerically that an 8 qubit Ising model simulator can be used to calibrate and control a 50 qubit Ising simulator while using only about 750 kilobits of experimental data. Finally, we provide upper bounds for the Fisher information that show that the number of experiments needed to characterize a system rapidly diverges as the duration of the experiments used in the characterization shrinks, which motivates the use of methods such as ours that do not require short evolution times. (fast track communication)

  5. A combined approach of generalized additive model and bootstrap with small sample sets for fault diagnosis in fermentation process of glutamate.

    Science.gov (United States)

    Liu, Chunbo; Pan, Feng; Li, Yun

    2016-07-29

    Glutamate is of great importance in food and pharmaceutical industries. There is still lack of effective statistical approaches for fault diagnosis in the fermentation process of glutamate. To date, the statistical approach based on generalized additive model (GAM) and bootstrap has not been used for fault diagnosis in fermentation processes, much less the fermentation process of glutamate with small samples sets. A combined approach of GAM and bootstrap was developed for the online fault diagnosis in the fermentation process of glutamate with small sample sets. GAM was first used to model the relationship between glutamate production and different fermentation parameters using online data from four normal fermentation experiments of glutamate. The fitted GAM with fermentation time, dissolved oxygen, oxygen uptake rate and carbon dioxide evolution rate captured 99.6 % variance of glutamate production during fermentation process. Bootstrap was then used to quantify the uncertainty of the estimated production of glutamate from the fitted GAM using 95 % confidence interval. The proposed approach was then used for the online fault diagnosis in the abnormal fermentation processes of glutamate, and a fault was defined as the estimated production of glutamate fell outside the 95 % confidence interval. The online fault diagnosis based on the proposed approach identified not only the start of the fault in the fermentation process, but also the end of the fault when the fermentation conditions were back to normal. The proposed approach only used a small sample sets from normal fermentations excitements to establish the approach, and then only required online recorded data on fermentation parameters for fault diagnosis in the fermentation process of glutamate. The proposed approach based on GAM and bootstrap provides a new and effective way for the fault diagnosis in the fermentation process of glutamate with small sample sets.

  6. Gyrokinetic neoclassical study of the bootstrap current in the tokamak edge pedestal with fully non-linear Coulomb collisions

    Energy Technology Data Exchange (ETDEWEB)

    Hager, Robert, E-mail: rhager@pppl.gov; Chang, C. S., E-mail: cschang@pppl.gov [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

    2016-04-15

    As a follow-up on the drift-kinetic study of the non-local bootstrap current in the steep edge pedestal of tokamak plasma by Koh et al. [Phys. Plasmas 19, 072505 (2012)], a gyrokinetic neoclassical study is performed with gyrokinetic ions and drift-kinetic electrons. Besides the gyrokinetic improvement of ion physics from the drift-kinetic treatment, a fully non-linear Fokker-Planck collision operator—that conserves mass, momentum, and energy—is used instead of Koh et al.'s linearized collision operator in consideration of the possibility that the ion distribution function is non-Maxwellian in the steep pedestal. An inaccuracy in Koh et al.'s result is found in the steep edge pedestal that originated from a small error in the collisional momentum conservation. The present study concludes that (1) the bootstrap current in the steep edge pedestal is generally smaller than what has been predicted from the small banana-width (local) approximation [e.g., Sauter et al., Phys. Plasmas 6, 2834 (1999) and Belli et al., Plasma Phys. Controlled Fusion 50, 095010 (2008)], (2) the plasma flow evaluated from the local approximation can significantly deviate from the non-local results, and (3) the bootstrap current in the edge pedestal, where the passing particle region is small, can be dominantly carried by the trapped particles in a broad trapped boundary layer. A new analytic formula based on numerous gyrokinetic simulations using various magnetic equilibria and plasma profiles with self-consistent Grad-Shafranov solutions is constructed.

  7. Bootstrap-after-bootstrap model averaging for reducing model uncertainty in model selection for air pollution mortality studies.

    Science.gov (United States)

    Roberts, Steven; Martin, Michael A

    2010-01-01

    Concerns have been raised about findings of associations between particulate matter (PM) air pollution and mortality that have been based on a single "best" model arising from a model selection procedure, because such a strategy may ignore model uncertainty inherently involved in searching through a set of candidate models to find the best model. Model averaging has been proposed as a method of allowing for model uncertainty in this context. To propose an extension (double BOOT) to a previously described bootstrap model-averaging procedure (BOOT) for use in time series studies of the association between PM and mortality. We compared double BOOT and BOOT with Bayesian model averaging (BMA) and a standard method of model selection [standard Akaike's information criterion (AIC)]. Actual time series data from the United States are used to conduct a simulation study to compare and contrast the performance of double BOOT, BOOT, BMA, and standard AIC. Double BOOT produced estimates of the effect of PM on mortality that have had smaller root mean squared error than did those produced by BOOT, BMA, and standard AIC. This performance boost resulted from estimates produced by double BOOT having smaller variance than those produced by BOOT and BMA. Double BOOT is a viable alternative to BOOT and BMA for producing estimates of the mortality effect of PM.

  8. Bootstrapped neural nets versus regression kriging in the digital mapping of pedological attributes: the automatic and time-consuming perspectives

    Science.gov (United States)

    Langella, Giuliano; Basile, Angelo; Bonfante, Antonello; Manna, Piero; Terribile, Fabio

    2013-04-01

    Digital soil mapping procedures are widespread used to build two-dimensional continuous maps about several pedological attributes. Our work addressed a regression kriging (RK) technique and a bootstrapped artificial neural network approach in order to evaluate and compare (i) the accuracy of prediction, (ii) the susceptibility of being included in automatic engines (e.g. to constitute web processing services), and (iii) the time cost needed for calibrating models and for making predictions. Regression kriging is maybe the most widely used geostatistical technique in the digital soil mapping literature. Here we tried to apply the EBLUP regression kriging as it is deemed to be the most statistically sound RK flavor by pedometricians. An unusual multi-parametric and nonlinear machine learning approach was accomplished, called BAGAP (Bootstrap aggregating Artificial neural networks with Genetic Algorithms and Principal component regression). BAGAP combines a selected set of weighted neural nets having specified characteristics to yield an ensemble response. The purpose of applying these two particular models is to ascertain whether and how much a more cumbersome machine learning method could be much promising in making more accurate/precise predictions. Being aware of the difficulty to handle objects based on EBLUP-RK as well as BAGAP when they are embedded in environmental applications, we explore the susceptibility of them in being wrapped within Web Processing Services. Two further kinds of aspects are faced for an exhaustive evaluation and comparison: automaticity and time of calculation with/without high performance computing leverage.

  9. Attention! Can choices for low value food over high value food be trained?

    NARCIS (Netherlands)

    Zoltak, M.J.; Veling, H.P.; Chen, Z.; Holland, R.W.

    2018-01-01

    People choose high value food items over low value food items, because food choices are guided by the comparison of values placed upon choice alternatives. This value comparison process is also influenced by the amount of attention people allocate to different items. Recent research shows that

  10. Causal independence between energy consumption and economic growth in Liberia: Evidence from a non-parametric bootstrapped causality test

    International Nuclear Information System (INIS)

    Wesseh, Presley K.; Zoumara, Babette

    2012-01-01

    This contribution investigates causal interdependence between energy consumption and economic growth in Liberia and proposes application of a bootstrap methodology. To better reflect causality, employment is incorporated as additional variable. The study demonstrates evidence of distinct bidirectional Granger causality between energy consumption and economic growth. Additionally, the results show that employment in Liberia Granger causes economic growth and apply irrespective of the short-run or long-run. Evidence from a Monte Carlo experiment reveals that the asymptotic Granger causality test suffers size distortion problem for Liberian data, suggesting that the bootstrap technique employed in this study is more appropriate. Given the empirical results, implications are that energy expansion policies like energy subsidy or low energy tariff for instance, would be necessary to cope with demand exerted as a result of economic growth in Liberia. Furthermore, Liberia might have the performance of its employment generation on the economy partly determined by adequate energy. Therefore, it seems fully justified that a quick shift towards energy production based on clean energy sources may significantly slow down economic growth in Liberia. Hence, the government’s target to implement a long-term strategy to make Liberia a carbon neutral country, and eventually less carbon dependent by 2050 is understandable. - Highlights: ► Causality between energy consumption and economic growth in Liberia investigated. ► There is bidirectional causality between energy consumption and economic growth. ► Energy expansion policies are necessary to cope with demand from economic growth. ► Asymptotic Granger causality test suffers size distortion problem for Liberian data. ► The bootstrap methodology employed in our study is more appropriate.

  11. MHD stability calculations of high-β quasi-axisymmetric stellarators

    International Nuclear Information System (INIS)

    Fu, G.Y.; Ku, L.P.; Pomphrey, N.; Redi, M.; Kessel, C.; Monticello, D.; Reiman, A.; Hughes, M.; Cooper, W.A.; Nuehrenberg, C.

    2001-01-01

    The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size. (author)

  12. MHD stability calculations of high-β quasi-axisymmetric stellarators

    International Nuclear Information System (INIS)

    Fu, G.Y.; Ku, L.P.; Pomphrey, N.; Redi, M.H.; Kessel, C.; Monticello, D.A.; Reiman, A.; Hughes, M.; Cooper, W.A.; Nuehrenberg, C.

    1999-01-01

    The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size. (author)

  13. MHD Stability Calculations of High-Beta Quasi-Axisymmetric Stellarators

    International Nuclear Information System (INIS)

    Kessel, C.; Fu, G.Y.; Ku, L.P.; Redi, M.H.; Pomphrey, N.

    1999-01-01

    The MHD stability of quasi-axisymmetric compact stellarators is investigated. It is shown that bootstrap current driven external kink modes can be stabilized by a combination of edge magnetic shear and appropriate 3D plasma boundary shaping while maintaining good quasi-axisymmetry. The results demonstrate that there exists a new class of stellarators with quasi-axisymmetry, large bootstrap current, high MHD beta limit, and compact size

  14. The Bootstrap, the Jackknife, and the Randomization Test: A Sampling Taxonomy.

    Science.gov (United States)

    Rodgers, J L

    1999-10-01

    A simple sampling taxonomy is defined that shows the differences between and relationships among the bootstrap, the jackknife, and the randomization test. Each method has as its goal the creation of an empirical sampling distribution that can be used to test statistical hypotheses, estimate standard errors, and/or create confidence intervals. Distinctions between the methods can be made based on the sampling approach (with replacement versus without replacement) and the sample size (replacing the whole original sample versus replacing a subset of the original sample). The taxonomy is useful for teaching the goals and purposes of resampling schemes. An extension of the taxonomy implies other possible resampling approaches that have not previously been considered. Univariate and multivariate examples are presented.

  15. The Bacterial Gene IfpA Influences the Potent Induction of Calcitonin Receptor and Osteoclast-Related Genes in Burkholderia Pseudomallei-Induced TRAP-Positive Multinucleated Giant Cells

    Science.gov (United States)

    2006-06-13

    with arithmetic mean ( UPGMA ) using random tie breaking and uncorrected pairwise distances in MacVector 7.0 (Oxford Molecular). Numbers on branches...denote the UPGMA bootstrap percentage using a highly stringent number (1000) of replications (Felsenstein, 1985). All bootstrap values are 50%, as shown

  16. ϕ 3 theory with F4 flavor symmetry in 6 - 2 ɛ dimensions: 3-loop renormalization and conformal bootstrap

    Science.gov (United States)

    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).

  17. Validation of neoclassical bootstrap current models in the edge of an H-mode plasma.

    Science.gov (United States)

    Wade, M R; Murakami, M; Politzer, P A

    2004-06-11

    Analysis of the parallel electric field E(parallel) evolution following an L-H transition in the DIII-D tokamak indicates the generation of a large negative pulse near the edge which propagates inward, indicative of the generation of a noninductive edge current. Modeling indicates that the observed E(parallel) evolution is consistent with a narrow current density peak generated in the plasma edge. Very good quantitative agreement is found between the measured E(parallel) evolution and that expected from neoclassical theory predictions of the bootstrap current.

  18. Selecting the Most Economic Project under Uncertainty Using Bootstrap Technique and Fuzzy Simulation

    Directory of Open Access Journals (Sweden)

    Kamran Shahanaghi

    2012-01-01

    Full Text Available This article, by leaving pre-determined membership function of a fuzzy set which is a basic assumption for such subject, will try to propose a hybrid technique to select the most economic project among alternative projects in fuzziness interest rates condition. In this way, net present worth (NPW would be the economic indicator. This article tries to challenge the assumption of large sample sizes availability for membership function determination and shows that some other techniques may have less accuracy. To give a robust solution, bootstrapping and fuzzy simulation is suggested and a numerical example is given and analyzed.

  19. Bootstrap and Order Statistics for Quantifying Thermal-Hydraulic Code Uncertainties in the Estimation of Safety Margins

    Directory of Open Access Journals (Sweden)

    Enrico Zio

    2008-01-01

    Full Text Available In the present work, the uncertainties affecting the safety margins estimated from thermal-hydraulic code calculations are captured quantitatively by resorting to the order statistics and the bootstrap technique. The proposed framework of analysis is applied to the estimation of the safety margin, with its confidence interval, of the maximum fuel cladding temperature reached during a complete group distribution blockage scenario in a RBMK-1500 nuclear reactor.

  20. More on analytic bootstrap for O(N) models

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Parijat; Kaviraj, Apratim; Sen, Kallol [Centre for High Energy Physics, Indian Institute of Science,C.V. Raman Avenue, Bangalore 560012 (India)

    2016-06-22

    This note is an extension of a recent work on the analytical bootstrapping of O(N) models. An additonal feature of the O(N) model is that the OPE contains trace and antisymmetric operators apart from the symmetric-traceless objects appearing in the OPE of the singlet sector. This in addition to the stress tensor (T{sub μν}) and the ϕ{sub i}ϕ{sup i} scalar, we also have other minimal twist operators as the spin-1 current J{sub μ} and the symmetric-traceless scalar in the case of O(N). We determine the effect of these additional objects on the anomalous dimensions of the corresponding trace, symmetric-traceless and antisymmetric operators in the large spin sector of the O(N) model, in the limit when the spin is much larger than the twist. As an observation, we also verified that the leading order results for the large spin sector from the ϵ−expansion are an exact match with our n=0 case. A plausible holographic setup for the special case when N=2 is also mentioned which mimics the calculation in the CFT.

  1. A Pilot Investigation of the Relationship between Climate Variability and Milk Compounds under the Bootstrap Technique

    Directory of Open Access Journals (Sweden)

    Mohammad Reza Marami Milani

    2015-09-01

    Full Text Available This study analyzes the linear relationship between climate variables and milk components in Iran by applying bootstrapping to include and assess the uncertainty. The climate parameters, Temperature Humidity Index (THI and Equivalent Temperature Index (ETI are computed from the NASA-Modern Era Retrospective-Analysis for Research and Applications (NASA-MERRA reanalysis (2002–2010. Milk data for fat, protein (measured on fresh matter bases, and milk yield are taken from 936,227 milk records for the same period, using cows fed by natural pasture from April to September. Confidence intervals for the regression model are calculated using the bootstrap technique. This method is applied to the original times series, generating statistically equivalent surrogate samples. As a result, despite the short time data and the related uncertainties, an interesting behavior of the relationships between milk compound and the climate parameters is visible. During spring only, a weak dependency of milk yield and climate variations is obvious, while fat and protein concentrations show reasonable correlations. In summer, milk yield shows a similar level of relationship with ETI, but not with temperature and THI. We suggest this methodology for studies in the field of the impacts of climate change and agriculture, also environment and food with short-term data.

  2. Yeast synthetic biology for high-value metabolites.

    Science.gov (United States)

    Dai, Zhubo; Liu, Yi; Guo, Juan; Huang, Luqi; Zhang, Xueli

    2015-02-01

    Traditionally, high-value metabolites have been produced through direct extraction from natural biological sources which are inefficient, given the low abundance of these compounds. On the other hand, these high-value metabolites are usually difficult to be synthesized chemically, due to their complex structures. In the last few years, the discovery of genes involved in the synthetic pathways of these metabolites, combined with advances in synthetic biology tools, has allowed the construction of increasing numbers of yeast cell factories for production of these metabolites from renewable biomass. This review summarizes recent advances in synthetic biology in terms of the use of yeasts as microbial hosts for the identification of the pathways involved in the synthesis, as well as for the production of high-value metabolites. © FEMS 2015. All rights reserved. For permissions, please e-mail: journals.permission@oup.com.

  3. Uncertainty in decision models analyzing cost-effectiveness : The joint distribution of incremental costs and effectiveness evaluated with a nonparametric bootstrap method

    NARCIS (Netherlands)

    Hunink, Maria; Bult, J.R.; De Vries, J; Weinstein, MC

    1998-01-01

    Purpose. To illustrate the use of a nonparametric bootstrap method in the evaluation of uncertainty in decision models analyzing cost-effectiveness. Methods. The authors reevaluated a previously published cost-effectiveness analysis that used a Markov model comparing initial percutaneous

  4. N=4 Superconformal Bootstrap of the K3 CFT

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    We study two-dimensional (4,4) superconformal field theories of central charge c=6, corresponding to nonlinear σ models on K3 surfaces, using the superconformal bootstrap. This is made possible through a surprising relation between the BPS N=4 superconformal blocks with c=6 and bosonic Virasoro conformal blocks with c=28, and an exact result on the moduli dependence of a certain integrated BPS 4-point function. Nontrivial bounds on the non-BPS spectrum in the K3 CFT are obtained as functions of the CFT moduli, that interpolate between the free orbifold points and singular CFT points. We observe directly from the CFT perspective the signature of a continuous spectrum above a gap at the singular moduli, and find numerically an upper bound on this gap that is saturated by the A1 N=4 cigar CFT. We also derive an analytic upper bound on the first nonzero eigenvalue of the scalar Laplacian on K3 in the large volume regime, that depends on the K3 moduli data. As two byproducts, we find an exact equivalence...

  5. Investigation of major international and Turkish companies via hierarchical methods and bootstrap approach

    Science.gov (United States)

    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.

  6. Bootstrap Score Tests for Fractional Integration in Heteroskedastic ARFIMA Models, with an Application to Price Dynamics in Commodity Spot and Futures Markets

    DEFF Research Database (Denmark)

    Cavaliere, Giuseppe; Nielsen, Morten Ørregaard; Taylor, A.M. Robert

    Empirical evidence from time series methods which assume the usual I(0)/I(1) paradigm suggests that the efficient market hypothesis, stating that spot and futures prices of a commodity should cointegrate with a unit slope on futures prices, does not hold. However, these statistical methods...... fractionally integrated model we are able to find a body of evidence in support of the efficient market hypothesis for a number of commodities. Our new tests are wild bootstrap implementations of score-based tests for the order of integration of a fractionally integrated time series. These tests are designed...... principle do. A Monte Carlo simulation study demonstrates that very significant improvements infinite sample behaviour can be obtained by the bootstrap vis-à-vis the corresponding asymptotic tests in both heteroskedastic and homoskedastic environments....

  7. Acculturation, Income and Vegetable Consumption Behaviors Among Latino Adults in the U.S.: A Mediation Analysis with the Bootstrapping Technique.

    Science.gov (United States)

    López, Erick B; Yamashita, Takashi

    2017-02-01

    This study examined whether household income mediates the relationship between acculturation and vegetable consumption among Latino adults in the U.S. Data from the 2009 to 2010 National Health and Nutrition Examination Survey were analyzed. Vegetable consumption index was created based on the frequencies of five kinds of vegetables intake. Acculturation was measured with the degree of English language use at home. Path model with bootstrapping technique was employed for mediation analysis. A significant partial mediation relationship was identified. Greater acculturation [95 % bias corrected bootstrap confident interval (BCBCI) = (0.02, 0.33)] was associated with the higher income and in turn, greater vegetable consumption. At the same time, greater acculturation was associated with lower vegetable consumption [95 % BCBCI = (-0.88, -0.07)]. Findings regarding the income as a mediator of the acculturation-dietary behavior relationship inform unique intervention programs and policy changes to address health disparities by race/ethnicity.

  8. Spherical bootstrap calculation of qqq-baryon and multiquark-hadron masses

    International Nuclear Information System (INIS)

    Balazs, L.A.P.; Nicolescu, B.

    1979-12-01

    Recently a way of implementing the dual-topological unitarization program has been found, in which baryons and other multiquark hadrons are put on the sphere and appear at the same topological-complexity level as ordinary anti-qq mesons. This permits one to have a lowest-order 'spherical bootstrap', within which unitarity, duality and crossing can be consistently satisfied. In the present paper, this framework to calculate hadron masses has been used by imposing duality on an infinite sum of ladder graphs generated from spherical unitarity. By making a certain simple dynamical approximation, an explicit generic Regge-trajectory formula is derived for any given process. If one then makes certain reasonable dynamical assumptions and requires simultaneous consistency for entire sets of processes, it is possible to calculate the masses of all the lowest states and the Regge trajectories associated with each of them. The only arbitrary parameter is the mass of the rho which merely serves to set the mass scale

  9. Bootstrapping hypercubic and hypertetrahedral theories in three dimensions arXiv

    CERN Document Server

    Stergiou, Andreas

    There are three generalizations of the Platonic solids that exist in all dimensions, namely the hypertetrahedron, the hypercube, and the hyperoctahedron, with the latter two being dual. Conformal field theories with the associated symmetry groups as global symmetries can be argued to exist in $d=3$ spacetime dimensions if the $\\varepsilon=4-d$ expansion is valid when $\\varepsilon\\to1$. In this paper hypercubic and hypertetrahedral theories are studied with the non-perturbative numerical conformal bootstrap. In the $N=3$ cubic case it is found that a bound with a kink is saturated by a solution with properties that cannot be reconciled with the $\\varepsilon$ expansion of the cubic theory. Possible implications for cubic magnets and structural phase transitions are discussed. For the hypertetrahedral theory evidence is found that the non-conformal window that is seen with the $\\varepsilon$ expansion exists in $d=3$ as well, and a rough estimate of its extent is given.

  10. Analysis of Electron Thermal Diffusivity and Bootstrap Current in Ohmically Heated Discharges after Boronization in the HT-7 Tokamak

    International Nuclear Information System (INIS)

    Zhang, X.M.; Wan, B.N.

    2005-01-01

    Significant improvements of plasma performance after ICRF boronization have been achieved in the full range of HT-7 operation parameters. Electron power balance is analyzed in the steady state ohmic discharges of the HT-7 tokamak. The ratio of the total radiation power to ohmic input power increases with increasing the central line-averaged electron density, but decreases with plasma current. It is obviously decreased after wall conditioning. Electron heat diffusivity χ e deduced from the power balance analysis is reduced throughout the main plasma after boronization. χ e decreases with increasing central line-averaged electron density in the parameter range of our study. After boronization, the plasma current profile is broadened and a higher current can be easily obtained on the HT-7 tokamak experiment. It is expected that the fact that the bootstrap current increases after boronization will explain these phenomena. After boronization, the plasma pressure gradient and the electron temperature near the boundary are larger than before, these factors influencing that the ratio of bootstrap current to total plasma current increases from several percent to above 10%

  11. High beta plasma confinement and neoclassical effects in a small aspect ratio reversed field pinch

    International Nuclear Information System (INIS)

    Hayase, K.; Sugimoto, H.; Ashida, H.

    2003-01-01

    The high β equilibrium and stability of a reversed field pinch (RFP) configuration with a small aspect ratio are theoretically studied. The equilibrium profile, high beta limit and the bootstrap current effect on those are calculated. The Mercier stable critical β decreases with 1/A, but β∼0.2 is permissible at A=2 with help of edge current profile modification. The effect of bootstrap current is evaluated for various pressure and current profiles and cross-sectional shapes of plasma by a self-consistent neoclassical PRSM equilibrium formulation. The high bootstrap current fraction (F bs ) increases the shear stabilization effect in the core region, which enhances significantly the stability β limit compared with that for the classical equilibrium. These features of small aspect ratio RFP, high β and high F bs , and a possibly easier access to the quasi-single helicity state beside the intrinsic compact structure are attractive for the feasible economical RFP reactor concept. (author)

  12. Smoothed Bootstrap und seine Anwendung in parametrischen Testverfahren

    Directory of Open Access Journals (Sweden)

    Handschuh, Dmitri

    2015-03-01

    Full Text Available In empirical research, the distribution of observations is usually unknown. This creates a problem if parametric methods are to be employed. The functionality of parametric methods relies on strong parametric assumptions. If these are violated the result of using classical parametric methods is questionable. Therefore, modifications of the parametric methods are required, if the appropriateness of their assumptions is in doubt. In this article, a modification of the smoothed bootstrap is presented (using the linear interpolation to approximate the distribution law suggested by the data. The application of this modification to statistical parametric methods allows taking into account deviations of the observed data distributions from the classical distribution assumptions without changing to other hypotheses, which often is implicit in using nonparametric methods. The approach is based on Monte Carlo method and is presented using one-way ANOVA as an example. The original and the modified statistical methods lead to identical outcomes when the assumptions of the original method are satisfied. For strong violations of the distributional assumptions, the modified version of the method is generally preferable. All procedures have been implemented in SAS. Test characteristics (type 1 error, the operating characteristic curve of the modified ANOVA are calculated.

  13. Non-abelian binding energies from the lightcone bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Li, Daliang [Department of Physics, Yale University,New Haven, CT 06511 (United States); Department of Physics and Astronomy, Johns Hopkins University,Baltimore, MD 21218 (United States); Meltzer, David [Department of Physics, Yale University,New Haven, CT 06511 (United States); Poland, David [Department of Physics, Yale University,New Haven, CT 06511 (United States); School of Natural Sciences, Institute for Advanced Study,Princeton, NJ 08540 (United States)

    2016-02-23

    We analytically study the lightcone limit of the conformal bootstrap for 4-point functions containing scalars charged under global symmetries. We show the existence of large spin double-twist operators in various representations of the global symmetry group. We then compute their anomalous dimensions in terms of the central charge C{sub T}, current central charge C{sub J}, and the OPE coefficients of low dimension scalars. In AdS, these results correspond to the binding energy of two-particle states arising from the exchange of gravitons, gauge bosons, and light scalar fields. Using unitarity and crossing symmetry, we show that gravity is universal and attractive among different types of two-particle states, while the gauge binding energy can have either sign as determined by the representation of the two-particle state, with universal ratios fixed by the symmetry group. We apply our results to 4D N=1 SQCD and the 3D O(N) vector models. We also show that in a unitary CFT, if the current central charge C{sub J} stays finite when the global symmetry group becomes infinitely large, such as the N→∞ limit of the O(N) vector model, then the theory must contain an infinite number of higher spin currents.

  14. 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.

  15. Bootstrapping O(N) vector models with four supercharges in 3≤d≤4

    Energy Technology Data Exchange (ETDEWEB)

    Chester, Shai M.; Iliesiu, Luca V.; Pufu, Silviu S.; Yacoby, Ran [Joseph Henry Laboratories, Princeton University,Washington Road, Princeton, NJ 08544 (United States)

    2016-05-17

    We analyze the conformal bootstrap constraints in theories with four supercharges and a global O(N)×U(1) flavor symmetry in 3≤d≤4 dimensions. In particular, we consider the 4-point function of O(N)-fundamental chiral operators Z{sub i} that have no chiral primary in the O(N)-singlet sector of their OPE. We find features in our numerical bounds that nearly coincide with the theory of N+1 chiral super-fields with superpotential W=X∑{sub i=1}{sup N}Z{sub i}{sup 2}, as well as general bounds on SCFTs where ∑{sub i=1}{sup N}Z{sub i}{sup 2} vanishes in the chiral ring.

  16. Automated modal parameter estimation using correlation analysis and bootstrap sampling

    Science.gov (United States)

    Yaghoubi, Vahid; Vakilzadeh, Majid K.; Abrahamsson, Thomas J. S.

    2018-02-01

    The estimation of modal parameters from a set of noisy measured data is a highly judgmental task, with user expertise playing a significant role in distinguishing between estimated physical and noise modes of a test-piece. Various methods have been developed to automate this procedure. The common approach is to identify models with different orders and cluster similar modes together. However, most proposed methods based on this approach suffer from high-dimensional optimization problems in either the estimation or clustering step. To overcome this problem, this study presents an algorithm for autonomous modal parameter estimation in which the only required optimization is performed in a three-dimensional space. To this end, a subspace-based identification method is employed for the estimation and a non-iterative correlation-based method is used for the clustering. This clustering is at the heart of the paper. The keys to success are correlation metrics that are able to treat the problems of spatial eigenvector aliasing and nonunique eigenvectors of coalescent modes simultaneously. The algorithm commences by the identification of an excessively high-order model from frequency response function test data. The high number of modes of this model provides bases for two subspaces: one for likely physical modes of the tested system and one for its complement dubbed the subspace of noise modes. By employing the bootstrap resampling technique, several subsets are generated from the same basic dataset and for each of them a model is identified to form a set of models. Then, by correlation analysis with the two aforementioned subspaces, highly correlated modes of these models which appear repeatedly are clustered together and the noise modes are collected in a so-called Trashbox cluster. Stray noise modes attracted to the mode clusters are trimmed away in a second step by correlation analysis. The final step of the algorithm is a fuzzy c-means clustering procedure applied to

  17. Value innovation: the strategic logic of high growth.

    Science.gov (United States)

    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.

  18. Fitting statistical distributions the generalized lambda distribution and generalized bootstrap methods

    CERN Document Server

    Karian, Zaven A

    2000-01-01

    Throughout the physical and social sciences, researchers face the challenge of fitting statistical distributions to their data. Although the study of statistical modelling has made great strides in recent years, the number and variety of distributions to choose from-all with their own formulas, tables, diagrams, and general properties-continue to create problems. For a specific application, which of the dozens of distributions should one use? What if none of them fit well?Fitting Statistical Distributions helps answer those questions. Focusing on techniques used successfully across many fields, the authors present all of the relevant results related to the Generalized Lambda Distribution (GLD), the Generalized Bootstrap (GB), and Monte Carlo simulation (MC). They provide the tables, algorithms, and computer programs needed for fitting continuous probability distributions to data in a wide variety of circumstances-covering bivariate as well as univariate distributions, and including situations where moments do...

  19. A voltage biased superconducting quantum interference device bootstrap circuit

    International Nuclear Information System (INIS)

    Xie Xiaoming; Wang Huiwu; Wang Yongliang; Dong Hui; Jiang Mianheng; Zhang Yi; Krause, Hans-Joachim; Braginski, Alex I; Offenhaeusser, Andreas; Mueck, Michael

    2010-01-01

    We present a dc superconducting quantum interference device (SQUID) readout circuit operating in the voltage bias mode and called a SQUID bootstrap circuit (SBC). The SBC is an alternative implementation of two existing methods for suppression of room-temperature amplifier noise: additional voltage feedback and current feedback. Two circuit branches are connected in parallel. In the dc SQUID branch, an inductively coupled coil connected in series provides the bias current feedback for enhancing the flux-to-current coefficient. The circuit branch parallel to the dc SQUID branch contains an inductively coupled voltage feedback coil with a shunt resistor in series for suppressing the preamplifier noise current by increasing the dynamic resistance. We show that the SBC effectively reduces the preamplifier noise to below the SQUID intrinsic noise. For a helium-cooled planar SQUID magnetometer with a SQUID inductance of 350 pH, a flux noise of about 3 μΦ 0 Hz -1/2 and a magnetic field resolution of less than 3 fT Hz -1/2 were obtained. The SBC leads to a convenient direct readout electronics for a dc SQUID with a wider adjustment tolerance than other feedback schemes.

  20. High historical values of foEs—Reality or artefact?

    Science.gov (United States)

    Laštovička, J.; Boška, J.; Burešová, D.; Kouba, D.

    2012-01-01

    Very high values of foEs had sometimes been reported in the past. These values, as well as all other ionogram-scaled values, had been derived from ionograms under the assumption of the vertical reflection of ordinary mode of sounding radio waves. In the past it was impossible to check the validity of this assumption. However, modern digisondes determine clearly the oblique or extraordinary mode reflections. To test the assumption of the vertical reflection of ordinary mode for high values of foEs, seven summers (June 2004-August 2010) from a midlatitude station Pruhonice are chosen. All hourly values of foEs≥6.0 MHz are selected from this data set, altogether 282 values. In 90% of cases the “classical” way of evaluation of foEs provides values higher than “true” values from modern digisonde (average difference about 1 MHz). 38% of “classical” foEs are oblique reflections, which however do not occur in direction perpendicular to geomagnetic field. The occurrence of high values of foEs varies very much from year to year between 0 and 130 events per year. As for diurnal variation, a pronounced maximum occurs at ˜10:00LT and 16:00LT (secondary), and a minimum after midnight.

  1. High power ECCD experiments at W7-AS

    International Nuclear Information System (INIS)

    Maassberg, H.; Geiger, J.; Laqua, H.; Marushchenko, N.B.; Wendland, C.; Rome, M.

    2001-01-01

    At the W7-AS stellarator, high power electron cyclotron current drive (ECCD) experiments are analyzed. In these net-current-free discharges, the ECCD as well as the bootstrap current are feedback controlled by an inductive current. Based on measured profiles, the neoclassical predictions for the bootstrap and the inductive current densities as well as the ECCD from the linear adjoint approach with trapped particles included are calculated, and the current balance is checked. Launch-angle scans at fixed density as well as density scans at fixed launch-angle are described. (author)

  2. Confidence ellipses: A variation based on parametric bootstrapping applicable on Multiple Factor Analysis results for rapid graphical evaluation

    DEFF Research Database (Denmark)

    Dehlholm, Christian; Brockhoff, Per B.; Bredie, Wender L. P.

    2012-01-01

    A new way of parametric bootstrapping allows similar construction of confidence ellipses applicable on all results from Multiple Factor Analysis obtained from the FactoMineR package in the statistical program R. With this procedure, a similar approach will be applied to Multiple Factor Analysis r...... in different studies performed on the same set of products. In addition, the graphical display of confidence ellipses eases interpretation and communication of results....

  3. New Strategies to Improve the Accuracy of Predictions based on Monte Carlo and Bootstrap Simulations: An Application to Bulgarian and Romanian Inflation || Nuevas estrategias para mejorar la exactitud de las predicciones de inflación en Rumanía y Bulgaria usando simulaciones Monte Carlo y Bootstrap

    Directory of Open Access Journals (Sweden)

    Simionescu, Mihaela

    2014-12-01

    Full Text Available The necessity of improving the forecasts accuracy grew in the context of actual economic crisis, but few researchers were interested till now in finding out some empirical strategies to improve their predictions. In this article, for the inflation rate forecasts on the horizon 2010-2012, we proved that the one-step-ahead forecasts based on updated AR(2 models for Romania and ARMA(1,1 models for Bulgaria could be substantially improved by generating new predictions using Monte Carlo method and bootstrap technique to simulate the models' coefficients. In this article we introduced a new methodology of constructing the forecasts, by using the limits of the bias-corrected-accelerated bootstrap intervals for the initial data series of the variable to predict. After evaluating the accuracy of the new forecasts, we found out that all the proposed strategies improved the initial AR(2 and ARMA(1,1 forecasts. These techniques also improved the predictions of experts in forecasting made for Romania and the forecasts of the European Commission made for Bulgaria. Our own method based on the lower limits of BCA intervals generated the best forecasts. In the forecasting process based on ARMA models the uncertainty analysis was introduced, by calculating, under the hypothesis of normal distribution, the probability that the predicted value exceeds a critical value. For 2013 in both countries we anticipate a decrease in the degree of uncertainty for annual inflation rate. || La necesidad de mejorar la precisión de las previsiones ha crecido en el contexto de crisis económica actual, pero son pocos los investigadores que se habían interesado hasta ahora por la búsqueda de estrategias empíricas para mejorar sus predicciones. En este artículo, a través de las previsiones de la tasa de inflación en el horizonte 2010-2012, hemos podido comprobar que las previsiones de un solo paso adelante sobre la base de modelos actualizados AR(2 para Rumanía y ARMA(1

  4. ϕ{sup 3} theory with F{sub 4} flavor symmetry in 6−2ϵ dimensions: 3-loop renormalization and conformal bootstrap

    Energy Technology Data Exchange (ETDEWEB)

    Pang, Yi [Max-Planck-Insitut für Gravitationsphysik (Albert-Einstein-Institut),Am Mühlenberg 1, Potsdam, DE-14476 (Germany); Rong, Junchen [Fields, Gravity & Strings, Center for Theoretical Physics of the Universe,Institute for Basic Sciences, Daejeon, 305-811 (Korea, Republic of); Su, Ning [CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics,Chinese Academy of Sciences, Zhong Guan Cun East Street 55 #,P.O. Box 2735, Beijing, 100190 (China)

    2016-12-14

    We consider ϕ{sup 3} theory in 6−2ϵ with F{sub 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{sub ϕ}), we obtain the corresponding upper bound on the scaling dimension of the second lowest scalar primary in the 26 representation (Δ{sub 26}{sup 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{sub 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{sub ϕ},Δ{sub 26}{sup 2nd})=(1.6,4).

  5. Bootstrap calculation of the dynamical quark mass in QCD4 at finite temperature

    International Nuclear Information System (INIS)

    Cabo, A.; Kalashnikov, O.K.; Veliev, E.Kh.

    1988-01-01

    Nonperturbative calculations of the dynamical quark mass m(T) are given in QCD 4 , based on the bootstrap solution of the Schwinger-Dyson equation for the quark Green function at finite temperatures. A closed nonlinear equation is obtained for m(T) whose solution is found under some simplifying assumptions. We used a particular approximation for the effective charge and the nonperturbative expressions of the gluon magnetic and electric masses. The singular behavior of m(T) is established and its parameters are determined numerically. The singularity found is shown to correctly reproduce the chiral phase transition and the temperature limits obtained for m(T) are qualitatively correct. The complete phase diagram of QCD 4 in the (μ,T) plane is briefly discussed. (orig.)

  6. Oil consumption and output: What causes what? Bootstrap panel causality for 49 countries

    International Nuclear Information System (INIS)

    Chu, Hsiao-Ping

    2012-01-01

    This study examines the growth, conservation, neutrality and feedback hypotheses for 49 countries during the period from 1970 to 2010 using panel causality analysis: this technique accounts for both dependence and heterogeneity across the countries. The results provide evidence as to the direction of causality between oil consumption and output and are consistent with the neutrality hypothesis for 24 countries, the growth hypothesis for 5 countries, the conservation hypothesis for 13 countries, and the feedback hypothesis for 7 countries. The findings provide important policy implications for the 49 countries under study. - Highlights: ► Bootstrap panel causality for 49 countries. ► Examines the “growth, conservation, neutrality and feedback” hypotheses for 49 countries during the period from 1970 to 2010.

  7. Electricity consumption-real GDP causality nexus: Evidence from a bootstrapped causality test for 30 OECD countries

    International Nuclear Information System (INIS)

    Narayan, Paresh Kumar; Prasad, Arti

    2008-01-01

    The goal of this paper is to examine any causal effects between electricity consumption and real GDP for 30 OECD countries. We use a bootstrapped causality testing approach and unravel evidence in favour of electricity consumption causing real GDP in Australia, Iceland, Italy, the Slovak Republic, the Czech Republic, Korea, Portugal, and the UK. The implication is that electricity conservation policies will negatively impact real GDP in these countries. However, for the rest of the 22 countries our findings suggest that electricity conversation policies will not affect real GDP

  8. Highly-Valued Reasons Muslim Caregivers Choose Evangelical Christian Schools

    Science.gov (United States)

    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…

  9. High value carbon materials from PET recycling

    International Nuclear Information System (INIS)

    Parra, J.B.; Ania, C.O.; Arenillas, A.; Rubiera, F.; Pis, J.J.

    2004-01-01

    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 deg. C under CO 2 atmosphere to different burn-off degrees. Textural characterisation of the samples was carried out by performing N 2 adsorption isotherms at -196 deg. C. The obtained carbons materials were mainly microporous, presenting low meso and macroporosity, and apparent BET surface areas of upto 2500 m 2 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

  10. A Comparison of Kernel Equating and Traditional Equipercentile Equating Methods and the Parametric Bootstrap Methods for Estimating Standard Errors in Equipercentile Equating

    Science.gov (United States)

    Choi, Sae Il

    2009-01-01

    This study used simulation (a) to compare the kernel equating method to traditional equipercentile equating methods under the equivalent-groups (EG) design and the nonequivalent-groups with anchor test (NEAT) design and (b) to apply the parametric bootstrap method for estimating standard errors of equating. A two-parameter logistic item response…

  11. Bootstrapping in a language of thought: a formal model of numerical concept learning.

    Science.gov (United States)

    Piantadosi, Steven T; Tenenbaum, Joshua B; Goodman, Noah D

    2012-05-01

    In acquiring number words, children exhibit a qualitative leap in which they transition from understanding a few number words, to possessing a rich system of interrelated numerical concepts. We present a computational framework for understanding this inductive leap as the consequence of statistical inference over a sufficiently powerful representational system. We provide an implemented model that is powerful enough to learn number word meanings and other related conceptual systems from naturalistic data. The model shows that bootstrapping can be made computationally and philosophically well-founded as a theory of number learning. Our approach demonstrates how learners may combine core cognitive operations to build sophisticated representations during the course of development, and how this process explains observed developmental patterns in number word learning. Copyright © 2011 Elsevier B.V. All rights reserved.

  12. Using In Vitro High-Throughput Screening Data for Predicting ...

    Science.gov (United States)

    Today there are more than 80,000 chemicals in commerce and the environment. The potential human health risks are unknown for the vast majority of these chemicals as they lack human health risk assessments, toxicity reference values and risk screening values. We aim to use computational toxicology and quantitative high throughput screening (qHTS) technologies to fill these data gaps, and begin to prioritize these chemicals for additional assessment. By coupling qHTS data with adverse outcome pathways (AOPs) we can use ontologies to make predictions about potential hazards and to identify those assays which are sufficient to infer these same hazards. Once those assays are identified, we can use bootstrap natural spline-based metaregression to integrate the evidence across multiple replicates or assays (if a combination of assays are together necessary to be sufficient). In this pilot, we demonstrate how we were able to identify that benzo[k]fluoranthene (B[k]F) may induce DNA damage and steatosis using qHTS data and two separate AOPs. We also demonstrate how bootstrap natural spline-based metaregression can be used to integrate the data across multiple assay replicates to generate a concentration-response curve. We used this analysis to calculate an internal point of departure of 0.751µM and risk-specific concentrations of 0.378µM for both 1:1,000 and 1:10,000 additive risk for B[k]F induced DNA damage based on the p53 assay. Based on the available evidence, we

  13. Improved Correction of Misclassification Bias With Bootstrap Imputation.

    Science.gov (United States)

    van Walraven, Carl

    2018-07-01

    Diagnostic codes used in administrative database research can create bias due to misclassification. Quantitative bias analysis (QBA) can correct for this bias, requires only code sensitivity and specificity, but may return invalid results. Bootstrap imputation (BI) can also address misclassification bias but traditionally requires multivariate models to accurately estimate disease probability. This study compared misclassification bias correction using QBA and BI. Serum creatinine measures were used to determine severe renal failure status in 100,000 hospitalized patients. Prevalence of severe renal failure in 86 patient strata and its association with 43 covariates was determined and compared with results in which renal failure status was determined using diagnostic codes (sensitivity 71.3%, specificity 96.2%). Differences in results (misclassification bias) were then corrected with QBA or BI (using progressively more complex methods to estimate disease probability). In total, 7.4% of patients had severe renal failure. Imputing disease status with diagnostic codes exaggerated prevalence estimates [median relative change (range), 16.6% (0.8%-74.5%)] and its association with covariates [median (range) exponentiated absolute parameter estimate difference, 1.16 (1.01-2.04)]. QBA produced invalid results 9.3% of the time and increased bias in estimates of both disease prevalence and covariate associations. BI decreased misclassification bias with increasingly accurate disease probability estimates. QBA can produce invalid results and increase misclassification bias. BI avoids invalid results and can importantly decrease misclassification bias when accurate disease probability estimates are used.

  14. High value carbon materials from PET recycling

    Energy Technology Data Exchange (ETDEWEB)

    Parra, J.B.; Ania, C.O.; Arenillas, A.; Rubiera, F.; Pis, J.J

    2004-11-15

    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 deg. C under CO{sub 2} atmosphere to different burn-off degrees. Textural characterisation of the samples was carried out by performing N{sub 2} adsorption isotherms at -196 deg. C. The obtained carbons materials were mainly microporous, presenting low meso and macroporosity, and apparent BET surface areas of upto 2500 m{sup 2} g{sup -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.

  15. Dependence between fusion temperatures and chemical components of a certain type of coal using classical, non-parametric and bootstrap techniques

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez-Manteiga, W.; Prada-Sanchez, J.M.; Fiestras-Janeiro, M.G.; Garcia-Jurado, I. (Universidad de Santiago de Compostela, Santiago de Compostela (Spain). Dept. de Estadistica e Investigacion Operativa)

    1990-11-01

    A statistical study of the dependence between various critical fusion temperatures of a certain kind of coal and its chemical components is carried out. As well as using classical dependence techniques (multiple, stepwise and PLS regression, principal components, canonical correlation, etc.) together with the corresponding inference on the parameters of interest, non-parametric regression and bootstrap inference are also performed. 11 refs., 3 figs., 8 tabs.

  16. Efficiency and productivity measurement of rural township hospitals in China: a bootstrapping data envelopment analysis

    Science.gov (United States)

    Cheng, Zhaohui; Cai, Miao; Tao, Hongbing; He, Zhifei; Lin, Xiaojun; Lin, Haifeng; Zuo, Yuling

    2016-01-01

    Objective Township hospitals (THs) are important components of the three-tier rural healthcare system of China. However, the efficiency and productivity of THs have been questioned since the healthcare reform was implemented in 2009. The objective of this study is to analyse the efficiency and productivity changes in THs before and after the reform process. Setting and participants A total of 48 sample THs were selected from the Xiaogan Prefecture in Hubei Province from 2008 to 2014. Outcome measures First, bootstrapping data envelopment analysis (DEA) was performed to estimate the technical efficiency (TE), pure technical efficiency (PTE) and scale efficiency (SE) of the sample THs during the period. Second, the bootstrapping Malmquist productivity index was used to calculate the productivity changes over time. Results The average TE, PTE and SE of the sample THs over the 7-year period were 0.5147, 0.6373 and 0.7080, respectively. The average TE and PTE increased from 2008 to 2012 but declined considerably after 2012. In general, the sample THs experienced a negative shift in productivity from 2008 to 2014. The negative change was 2.14%, which was attributed to a 23.89% decrease in technological changes (TC). The sample THs experienced a positive productivity shift from 2008 to 2012 but experienced deterioration from 2012 to 2014. Conclusions There was considerable space for TE improvement in the sample THs since the average TE was relatively low. From 2008 to 2014, the sample THs experienced a decrease in productivity, and the adverse alteration in TC should be emphasised. In the context of healthcare reform, the factors that influence TE and productivity of THs are complex. Results suggest that numerous quantitative and qualitative studies are necessary to explore the reasons for the changes in TE and productivity. PMID:27836870

  17. Performance of an SOI Boot-Strapped Full-Bridge MOSFET Driver, Type CHT-FBDR, under Extreme Temperatures

    Science.gov (United States)

    Patterson, Richard; Hammoud, Ahmad

    2009-01-01

    Electronic systems designed for use in deep space and planetary exploration missions are expected to encounter extreme temperatures and wide thermal swings. Silicon-based devices are limited in their wide-temperature capability and usually require extra measures, such as cooling or heating mechanisms, to provide adequate ambient temperature for proper operation. Silicon-On-Insulator (SOI) technology, on the other hand, lately has been gaining wide spread use in applications where high temperatures are encountered. Due to their inherent design, SOI-based integrated circuit chips are able to operate at temperatures higher than those of the silicon devices by virtue of reducing leakage currents, eliminating parasitic junctions, and limiting internal heating. In addition, SOI devices provide faster switching, consume less power, and offer improved radiation-tolerance. Very little data, however, exist on the performance of such devices and circuits under cryogenic temperatures. In this work, the performance of an SOI bootstrapped, full-bridge driver integrated circuit was evaluated under extreme temperatures and thermal cycling. The investigations were carried out to establish a baseline on the functionality and to determine suitability of this device for use in space exploration missions under extreme temperature conditions.

  18. N=4 superconformal bootstrap of the K3 CFT

    Energy Technology Data Exchange (ETDEWEB)

    Lin, Ying-Hsuan; Shao, Shu-Heng [Jefferson Physical Laboratory, Harvard University,17 Oxford Street, Cambridge, MA 02138 (United States); Simmons-Duffin, David [School of Natural Sciences, Institute for Advanced Study,1 Einstein Drive, Princeton, NJ 08540 (United States); Wang, Yifan [Center for Theoretical Physics, Massachusetts Institute of Technology,77 Massachusetts Ave, Cambridge, MA 02139 (United States); Yin, Xi [Jefferson Physical Laboratory, Harvard University,17 Oxford Street, Cambridge, MA 02138 (United States)

    2017-05-23

    We study two-dimensional (4,4) superconformal field theories of central charge c=6, corresponding to nonlinear sigma models on K3 surfaces, using the superconformal bootstrap. This is made possible through a surprising relation between the BPS N=4 superconformal blocks with c=6 and bosonic Virasoro conformal blocks with c=28, and an exact result on the moduli dependence of a certain integrated BPS 4-point function. Nontrivial bounds on the non-BPS spectrum in the K3 CFT are obtained as functions of the CFT moduli, that interpolate between the free orbifold points and singular CFT points. We observe directly from the CFT perspective the signature of a continuous spectrum above a gap at the singular moduli, and find numerically an upper bound on this gap that is saturated by the A{sub 1}N=4 cigar CFT. We also derive an analytic upper bound on the first nonzero eigenvalue of the scalar Laplacian on K3 in the large volume regime, that depends on the K3 moduli data. As two byproducts, we find an exact equivalence between a class of BPS N=2 superconformal blocks and Virasoro conformal blocks in two dimensions, and an upper bound on the four-point functions of operators of sufficiently low scaling dimension in three and four dimensional CFTs.

  19. Is the tourism-economic growth nexus time-varying? Bootstrap rolling-window causality analysis for the top ten tourist destinations

    OpenAIRE

    Shahbaz, Muhammad; Ferrer, Román; Hussain Shahzad, Syed Jawad; Haouas, Ilham

    2017-01-01

    This paper explores the time-varying causal nexus between tourism development and economic growth for the top ten tourist destinations in the world, namely China, France, Germany, Italy, Mexico, the Russian Federation, Spain, Turkey, the United Kingdom and the United States of America, over the period 1990-2015. To that end, a bootstrap rolling window Granger causality approach based on the modified Granger causality test developed by Toda and Yamamoto (1995) and Dolado and Lütkepohl (1996), ...

  20. Blueprint for action: steps toward a high-quality, high-value maternity care system.

    Science.gov (United States)

    Angood, Peter B; Armstrong, Elizabeth Mitchell; Ashton, Diane; Burstin, Helen; Corry, Maureen P; Delbanco, Suzanne F; Fildes, Barbara; Fox, Daniel M; Gluck, Paul A; Gullo, Sue Leavitt; Howes, Joanne; Jolivet, R Rima; Laube, Douglas W; Lynne, Donna; Main, Elliott; Markus, Anne Rossier; Mayberry, Linda; Mitchell, Lynn V; Ness, Debra L; Nuzum, Rachel; Quinlan, Jeffrey D; Sakala, Carol; Salganicoff, Alina

    2010-01-01

    Childbirth Connection hosted a 90th Anniversary national policy symposium, Transforming Maternity Care: A High Value Proposition, on April 3, 2009, in Washington, DC. Over 100 leaders from across the range of stakeholder perspectives were actively engaged in the symposium work to improve the quality and value of U.S. maternity care through broad system improvement. A multi-disciplinary symposium steering committee guided the strategy from its inception and contributed to every phase of the project. The "Blueprint for Action: Steps Toward a High Quality, High Value Maternity Care System", issued by the Transforming Maternity Care Symposium Steering Committee, answers the fundamental question, "Who needs to do what, to, for, and with whom to improve the quality of maternity care over the next five years?" Five stakeholder workgroups collaborated to propose actionable strategies in 11 critical focus areas for moving expeditiously toward the realization of the long term "2020 Vision for a High Quality, High Value Maternity Care System", also published in this issue. Following the symposium these workgroup reports and recommendations were synthesized into the current blueprint. For each critical focus area, the "Blueprint for Action" presents a brief problem statement, a set of system goals for improvement in that area, and major recommendations with proposed action steps to achieve them. This process created a clear sightline to action that if enacted could improve the structure, process, experiences of care, and outcomes of the maternity care system in ways that when anchored in the culture can indeed transform maternity care. Copyright 2010 Jacobs Institute of Women

  1. Efficient p-value evaluation for resampling-based tests

    KAUST Repository

    Yu, K.

    2011-01-05

    The resampling-based test, which often relies on permutation or bootstrap procedures, has been widely used for statistical hypothesis testing when the asymptotic distribution of the test statistic is unavailable or unreliable. It requires repeated calculations of the test statistic on a large number of simulated data sets for its significance level assessment, and thus it could become very computationally intensive. Here, we propose an efficient p-value evaluation procedure by adapting the stochastic approximation Markov chain Monte Carlo algorithm. The new procedure can be used easily for estimating the p-value for any resampling-based test. We show through numeric simulations that the proposed procedure can be 100-500 000 times as efficient (in term of computing time) as the standard resampling-based procedure when evaluating a test statistic with a small p-value (e.g. less than 10( - 6)). With its computational burden reduced by this proposed procedure, the versatile resampling-based test would become computationally feasible for a much wider range of applications. We demonstrate the application of the new method by applying it to a large-scale genetic association study of prostate cancer.

  2. Detecting outliers and/or leverage points: a robust two-stage procedure with bootstrap cut-off points

    Directory of Open Access Journals (Sweden)

    Ettore Marubini

    2014-01-01

    Full Text Available This paper presents a robust two-stage procedure for identification of outlying observations in regression analysis. The exploratory stage identifies leverage points and vertical outliers through a robust distance estimator based on Minimum Covariance Determinant (MCD. After deletion of these points, the confirmatory stage carries out an Ordinary Least Squares (OLS analysis on the remaining subset of data and investigates the effect of adding back in the previously deleted observations. Cut-off points pertinent to different diagnostics are generated by bootstrapping and the cases are definitely labelled as good-leverage, bad-leverage, vertical outliers and typical cases. The procedure is applied to four examples.

  3. The Reliability and Stability of an Inferred Phylogenetic Tree from Empirical Data.

    Science.gov (United States)

    Katsura, Yukako; Stanley, Craig E; Kumar, Sudhir; Nei, Masatoshi

    2017-03-01

    The reliability of a phylogenetic tree obtained from empirical data is usually measured by the bootstrap probability (Pb) of interior branches of the tree. If the bootstrap probability is high for most branches, the tree is considered to be reliable. If some interior branches show relatively low bootstrap probabilities, we are not sure that the inferred tree is really reliable. Here, we propose another quantity measuring the reliability of the tree called the stability of a subtree. This quantity refers to the probability of obtaining a subtree (Ps) of an inferred tree obtained. We then show that if the tree is to be reliable, both Pb and Ps must be high. We also show that Ps is given by a bootstrap probability of the subtree with the closest outgroup sequence, and computer program RESTA for computing the Pb and Ps values will be presented. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  4. Integrating Multiple Microarray Data for Cancer Pathway Analysis Using Bootstrapping K-S Test

    Directory of Open Access Journals (Sweden)

    Bing Han

    2009-01-01

    Full Text Available Previous applications of microarray technology for cancer research have mostly focused on identifying genes that are differentially expressed between a particular cancer and normal cells. In a biological system, genes perform different molecular functions and regulate various biological processes via interactions with other genes thus forming a variety of complex networks. Therefore, it is critical to understand the relationship (e.g., interactions between genes across different types of cancer in order to gain insights into the molecular mechanisms of cancer. Here we propose an integrative method based on the bootstrapping Kolmogorov-Smirnov test and a large set of microarray data produced with various types of cancer to discover common molecular changes in cells from normal state to cancerous state. We evaluate our method using three key pathways related to cancer and demonstrate that it is capable of finding meaningful alterations in gene relations.

  5. Are volcanic seismic b-values high, and if so when?

    Science.gov (United States)

    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 forecasting informed by b-value variability, in particular in assessing the significance of b-value variations identified by sample sizes with fewer than 200 events above the completeness threshold.

  6. Bootstrap-based Support of HGT Inferred by Maximum Parsimony

    Directory of Open Access Journals (Sweden)

    Nakhleh Luay

    2010-05-01

    Full Text Available Abstract Background Maximum parsimony is one of the most commonly used criteria for reconstructing phylogenetic trees. Recently, Nakhleh and co-workers extended this criterion to enable reconstruction of phylogenetic networks, and demonstrated its application to detecting reticulate evolutionary relationships. However, one of the major problems with this extension has been that it favors more complex evolutionary relationships over simpler ones, thus having the potential for overestimating the amount of reticulation in the data. An ad hoc solution to this problem that has been used entails inspecting the improvement in the parsimony length as more reticulation events are added to the model, and stopping when the improvement is below a certain threshold. Results In this paper, we address this problem in a more systematic way, by proposing a nonparametric bootstrap-based measure of support of inferred reticulation events, and using it to determine the number of those events, as well as their placements. A number of samples is generated from the given sequence alignment, and reticulation events are inferred based on each sample. Finally, the support of each reticulation event is quantified based on the inferences made over all samples. Conclusions We have implemented our method in the NEPAL software tool (available publicly at http://bioinfo.cs.rice.edu/, and studied its performance on both biological and simulated data sets. While our studies show very promising results, they also highlight issues that are inherently challenging when applying the maximum parsimony criterion to detect reticulate evolution.

  7. Bootstrap-based support of HGT inferred by maximum parsimony.

    Science.gov (United States)

    Park, Hyun Jung; Jin, Guohua; Nakhleh, Luay

    2010-05-05

    Maximum parsimony is one of the most commonly used criteria for reconstructing phylogenetic trees. Recently, Nakhleh and co-workers extended this criterion to enable reconstruction of phylogenetic networks, and demonstrated its application to detecting reticulate evolutionary relationships. However, one of the major problems with this extension has been that it favors more complex evolutionary relationships over simpler ones, thus having the potential for overestimating the amount of reticulation in the data. An ad hoc solution to this problem that has been used entails inspecting the improvement in the parsimony length as more reticulation events are added to the model, and stopping when the improvement is below a certain threshold. In this paper, we address this problem in a more systematic way, by proposing a nonparametric bootstrap-based measure of support of inferred reticulation events, and using it to determine the number of those events, as well as their placements. A number of samples is generated from the given sequence alignment, and reticulation events are inferred based on each sample. Finally, the support of each reticulation event is quantified based on the inferences made over all samples. We have implemented our method in the NEPAL software tool (available publicly at http://bioinfo.cs.rice.edu/), and studied its performance on both biological and simulated data sets. While our studies show very promising results, they also highlight issues that are inherently challenging when applying the maximum parsimony criterion to detect reticulate evolution.

  8. Bootstrapping Development of a Cloud-Based Spoken Dialog System in the Educational Domain from Scratch Using Crowdsourced Data. Research Report. ETS RR-16-16

    Science.gov (United States)

    Ramanarayanan, Vikram; Suendermann-Oeft, David; Lange, Patrick; Ivanov, Alexei V.; Evanini, Keelan; Yu, Zhou; Tsuprun, Eugene; Qian, Yao

    2016-01-01

    We propose a crowdsourcing-based framework to iteratively and rapidly bootstrap a dialog system from scratch for a new domain. We leverage the open-source modular HALEF dialog system to deploy dialog applications. We illustrate the usefulness of this framework using four different prototype dialog items with applications in the educational domain…

  9. Solutions of simple dual bootstrap models satisfying Lee--Veneziano relation and the smallness of cut discontinuities

    International Nuclear Information System (INIS)

    Chiu, C.B.; Hossain, M.; Tow, D.M.

    1977-07-01

    To investigate the t-dependent solutions of simple dual bootstrap models, two general formulations are discussed, one without and one with cut cancellation at the planar level. The possible corresponding production mechanisms are discussed. In contrast to Bishari's formulation, both models recover the Lee-Veneziano relation, i.e., in the peak approximation the Pomeron intercept is unity. The solutions based on an exponential form for the reduced triple-Reggeon vertex for both models are discussed in detail. Also calculated are the cut discontinuities for both models and for Bishari's and it is shown that at both the planar and cylinder levels they are small compared with the corresponding pole residues. Precocious asymptotic planarity is also found in the solutions

  10. Sustainment of high confinement in JT-60U reversed shear plasmas

    International Nuclear Information System (INIS)

    Fujita, T.; Kamada, Y.; Ide, S.; Takeji, S.; Sakamoto, Y.; Isayama, A.; Suzuki, T.; Oikawa, T.; Fukuda, T.

    2001-01-01

    confinement is achieved owing to strong internal transport barriers (ITBs), are reported. In a high current plasma with an L-mode edge, deuterium-tritium-equivalent fusion power gain, Q DT eq =0.5 was sustained for 0.8 s (∼ energy confinement time) by adjusting plasma beta precisely using feedback control of stored energy. In a high triangularity plasma with an ELMy H-mode edge, the shrinkage of reversed shear region was suppressed and quasi steady sustainment of high confinement was achieved by raising the poloidal beta and enhancing the bootstrap current peaked at the ITB layer. High bootstrap current fraction (∼80%) was obtained in a high q regime (q 95 ∼9), which leaded to full non-inductive current drive condition. The normalized beta (β N ) of ∼ 2 and H-factor of H 89 ∼3.5 (HH 98y2 ∼2.2) were sustained for 2.7 s (∼ 6 times energy confinement time). (author)

  11. Uma comparação entre técnicas de propagação de erros em astrofísica: Monte Carlo x Bootstrap

    Science.gov (United States)

    Waelkens, A. H.; Janot Pacheco, E.

    2003-08-01

    Recentemente Dhillon & Watson (2001) criticaram o procedimento de determinação de erros via simulações de Monte Carlo no caso do imageamento indireto de estrelas, por introduzir ruído nos dados e resultar em erros superestimados. Estes autores propuseram a utilização alternativa do método de Bootstrap como uma técnica superior para a estimativa de erros. Neste trabalho apresentamos os resultados de um estudo comparativo da performance das técnicas de simulação por Monte Carlo e por Bootstrap para a determinação de erros em duas situações de interesse: (i) ajuste de modelos a espectros observados e (ii) imageamento indireto de discos de acréscimo com técnicas de mapeamento por eclipse. No caso (i), os dados de entrada são espectros de emissão simples de hidrogênio aos quais é adicionado ruído gaussiano de amplitude selecionada. No caso (ii), são produzidas curvas de luz do eclipse de uma distribuição de brilho seguindo a lei TµR-3/4 para discos estacionários cuja taxa de acréscimo varia ao longo do eclipse segundo uma distribuição gaussiana de amplitude selecionada, simulando o ruído. A avaliação da performance é feita com o auxílio de um diagrama do erro relativo na grandeza ajustada, conforme obtido por cada método, versus o erro relativo (ruído/sinal) dos dados de entrada. O estudo mostra que as duas técnicas produzem resultados semelhantes nos dois casos, e que a suposta superioridade do método de Bootstrap não se confirma.

  12. Service Mediation and Negotiation Bootstrapping as First Achievements Towards Self-adaptable Cloud Services

    Science.gov (United States)

    Brandic, Ivona; Music, Dejan; Dustdar, Schahram

    Nowadays, novel computing paradigms as for example Cloud Computing are gaining more and more on importance. In case of Cloud Computing users pay for the usage of the computing power provided as a service. Beforehand they can negotiate specific functional and non-functional requirements relevant for the application execution. However, providing computing power as a service bears different research challenges. On one hand dynamic, versatile, and adaptable services are required, which can cope with system failures and environmental changes. On the other hand, human interaction with the system should be minimized. In this chapter we present the first results in establishing adaptable, versatile, and dynamic services considering negotiation bootstrapping and service mediation achieved in context of the Foundations of Self-Governing ICT Infrastructures (FoSII) project. We discuss novel meta-negotiation and SLA mapping solutions for Cloud services bridging the gap between current QoS models and Cloud middleware and representing important prerequisites for the establishment of autonomic Cloud services.

  13. Using i2b2 to Bootstrap Rural Health Analytics and Learning Networks.

    Science.gov (United States)

    Harris, Daniel R; Baus, Adam D; Harper, Tamela J; Jarrett, Traci D; Pollard, Cecil R; Talbert, Jeffery C

    2016-08-01

    We demonstrate that the open-source i2b2 (Informatics for Integrating Biology and the Bedside) data model can be used to bootstrap rural health analytics and learning networks. These networks promote communication and research initiatives by providing the infrastructure necessary for sharing data and insights across a group of healthcare and research partners. Data integration remains a crucial challenge in connecting rural healthcare sites with a common data sharing and learning network due to the lack of interoperability and standards within electronic health records. The i2b2 data model acts as a point of convergence for disparate data from multiple healthcare sites. A consistent and natural data model for healthcare data is essential for overcoming integration issues, but challenges such as those caused by weak data standardization must still be addressed. We describe our experience in the context of building the West Virginia/Kentucky Health Analytics and Learning Network, a collaborative, multi-state effort connecting rural healthcare sites.

  14. Monthly water quality forecasting and uncertainty assessment via bootstrapped wavelet neural networks under missing data for Harbin, China.

    Science.gov (United States)

    Wang, Yi; Zheng, Tong; Zhao, Ying; Jiang, Jiping; Wang, Yuanyuan; Guo, Liang; Wang, Peng

    2013-12-01

    In this paper, bootstrapped wavelet neural network (BWNN) was developed for predicting monthly ammonia nitrogen (NH(4+)-N) and dissolved oxygen (DO) in Harbin region, northeast of China. The Morlet wavelet basis function (WBF) was employed as a nonlinear activation function of traditional three-layer artificial neural network (ANN) structure. Prediction intervals (PI) were constructed according to the calculated uncertainties from the model structure and data noise. Performance of BWNN model was also compared with four different models: traditional ANN, WNN, bootstrapped ANN, and autoregressive integrated moving average model. The results showed that BWNN could handle the severely fluctuating and non-seasonal time series data of water quality, and it produced better performance than the other four models. The uncertainty from data noise was smaller than that from the model structure for NH(4+)-N; conversely, the uncertainty from data noise was larger for DO series. Besides, total uncertainties in the low-flow period were the biggest due to complicated processes during the freeze-up period of the Songhua River. Further, a data missing-refilling scheme was designed, and better performances of BWNNs for structural data missing (SD) were observed than incidental data missing (ID). For both ID and SD, temporal method was satisfactory for filling NH(4+)-N series, whereas spatial imputation was fit for DO series. This filling BWNN forecasting method was applied to other areas suffering "real" data missing, and the results demonstrated its efficiency. Thus, the methods introduced here will help managers to obtain informed decisions.

  15. Microprocessor-controlled meter of high Q-values

    International Nuclear Information System (INIS)

    Bun'kov, S.N.; Konstantinov, V.I.; Masalov, V.L.; Sevrukova, L.M.; Tokarev, A.D.; Usiv, Yu.V.

    1990-01-01

    The paper describes the functional model of a high-precision microcomputer-controlled test facility for studying the electric and physical parameters of superconducting cavities. The basic unit of the test facility is high-stability retunable RF oscillator. It is designed following the scheme of the frequency phase tuning using standard equipment. The systematic error in measuring the loaded Q-value of reentrant cavities is not larger than 5%. A dedicated built-in microcomputer is used to control the measuring test facility and to make the commutations required. 2 refs.; 2 figs

  16. Electron Cyclotron Current Drive Compensation of the Bootstrap Current in Quasi-symmetric Reactor Devices

    International Nuclear Information System (INIS)

    Margalet, S. D.; Cooper, W. A.; Volpe, F.; Castejon, F.

    2005-01-01

    In magnetic confinement devices, the inhomogeneity of the confining magnetic field along a magnetic field line generates the trapping of particles within local magnetic wells. One of the consequences of the trapped particles is the generation of a current, known as the bootstrap current (BC), whose direction depends on the nature of the magnetic trapping. The BC provides an extra contribution to the poloidal component of the confining magnetic field. The variation of the poloidal component produces the alteration of the winding of the magnetic field lines around the flux surfaces quantified by the rotational transform. When reaches low rational values, it can trigger the generation of ideal MHD instabilities. Therefore, the BC may be responsible for the destabilisation of the configuration [1]. Having established the potentially dangerous implication of the BC, principally, in reactor prototypes, a method to compensate its harmful effects is proposed. It consists of the modelling of the current driven by externally launched ECWs within the plasma to compensate the effects of the BC. This method is flexible enough to allow the identification of the appropriate scenarios in which to generate the required CD depending on the nature of the confining magnetic field and the specific plasma parameters of the configuration. Both the BC and the CD calculations are included in a self-consistent scheme which leads to the computation of a stable BC+CD-consistent MHD equilibrium. This procedure is applied in this paper to simulate the required CD to stabilise a QAS and a QHS reactor prototypes. The estimation of the input power required and the effect of the driven current on the final equilibrium of the system is performed for several relevant scenarios and wave polarisations providing various options of stabilising driven currents. (Author)

  17. Exact finite volume expectation values of local operators in excited states

    Energy Technology Data Exchange (ETDEWEB)

    Pozsgay, B. [MTA-BME “Momentum” Statistical Field Theory Research Group,Budafoki út 8, 1111 Budapest (Hungary); Szécsényi, I.M. [Department of Mathematical Sciences, Durham University, South Road, Durham, DH1 3LE (United Kingdom); Institute of Theoretical Physics, Eötvös Loránd University,Pázmány Péter sétány 1/A, 1117 Budapest (Hungary); Takács, G. [MTA-BME “Momentum” Statistical Field Theory Research Group,Budafoki út 8, 1111 Budapest (Hungary); Department of Theoretical Physics, Budapest University of Technology and Economics,Budafoki út 8, 1111 Budapest (Hungary)

    2015-04-07

    We present a conjecture for the exact expression of finite volume expectation values in excited states in integrable quantum field theories, which is an extension of an earlier conjecture to the case of general diagonal factorized scattering with bound states and a nontrivial bootstrap structure. The conjectured expression is a spectral expansion which uses the exact form factors and the excited state thermodynamic Bethe Ansatz as building blocks. The conjecture is proven for the case of the trace of the energy-moment tensor. Concerning its validity for more general operators, we provide numerical evidence using the truncated conformal space approach. It is found that the expansion fails to be well-defined for small values of the volume in cases when the singularity structure of the TBA equations undergoes a non-trivial rearrangement under some critical value of the volume. Despite these shortcomings, the conjectured expression is expected to be valid for all volumes for most of the excited states, and as an expansion above the critical volume for the rest.

  18. Exact finite volume expectation values of local operators in excited states

    International Nuclear Information System (INIS)

    Pozsgay, B.; Szécsényi, I.M.; Takács, G.

    2015-01-01

    We present a conjecture for the exact expression of finite volume expectation values in excited states in integrable quantum field theories, which is an extension of an earlier conjecture to the case of general diagonal factorized scattering with bound states and a nontrivial bootstrap structure. The conjectured expression is a spectral expansion which uses the exact form factors and the excited state thermodynamic Bethe Ansatz as building blocks. The conjecture is proven for the case of the trace of the energy-moment tensor. Concerning its validity for more general operators, we provide numerical evidence using the truncated conformal space approach. It is found that the expansion fails to be well-defined for small values of the volume in cases when the singularity structure of the TBA equations undergoes a non-trivial rearrangement under some critical value of the volume. Despite these shortcomings, the conjectured expression is expected to be valid for all volumes for most of the excited states, and as an expansion above the critical volume for the rest.

  19. Value-based insurance design: consumers' views on paying more for high-cost, low-value care.

    Science.gov (United States)

    Ginsburg, Marjorie

    2010-11-01

    Value-based insurance designs frequently lower consumers' cost sharing to motivate healthy behavior, such as adhering to medication regimens. Few health care purchasers have followed the more controversial approach of using increased cost sharing to temper demand for high-cost, low-value medical care. Yet there is evidence that when health care's affordability is at stake, the public may be willing to compromise on coverage of certain medical problems and less effective treatments. Businesses should engage employees in discussions about if and how this type of value-based insurance design should apply to their own insurance coverage. A similar process could also be used for Medicare and other public-sector programs.

  20. Efficient p-value evaluation for resampling-based tests

    KAUST Repository

    Yu, K.; Liang, F.; Ciampa, J.; Chatterjee, N.

    2011-01-01

    The resampling-based test, which often relies on permutation or bootstrap procedures, has been widely used for statistical hypothesis testing when the asymptotic distribution of the test statistic is unavailable or unreliable. It requires repeated

  1. Penning trap mass spectrometry Q-value determinations for highly forbidden β-decays

    Science.gov (United States)

    Sandler, Rachel; Bollen, Georg; Eibach, Martin; Gamage, Nadeesha; Gulyuz, Kerim; Hamaker, Alec; Izzo, Chris; Kandegedara, Rathnayake; Redshaw, Matt; Ringle, Ryan; Valverde, Adrian; Yandow, Isaac; Low Energy Beam Ion Trap Team

    2017-09-01

    Over the last several decades, extremely sensitive, ultra-low background beta and gamma detection techniques have been developed. These techniques have enabled the observation of very rare processes, such as highly forbidden beta decays e.g. of 113Cd, 50V and 138La. Half-life measurements of highly forbidden beta decays provide a testing ground for theoretical nuclear models, and the comparison of calculated and measured energy spectra could enable a determination of the values of the weak coupling constants. Precision Q-value measurements also allow for systematic tests of the beta-particle detection techniques. We will present the results and current status of Q value determinations for highly forbidden beta decays. The Q values, the mass difference between parent and daughter nuclides, are measured using the high precision Penning trap mass spectrometer LEBIT at the National Superconducting Cyclotron Laboratory.

  2. A multimodal high-value curriculum affects drivers of utilization and performance on the high-value care component of the internal medicine in-training exam.

    Science.gov (United States)

    Chau, Tom; Loertscher, Laura

    2018-01-01

    Background : Teaching the practice of high-value care (HVC) is an increasingly important function of graduate medical education but best practices and long-term outcomes remain unknown. Objective : Whether a multimodal curriculum designed to address specific drivers of low-value care would affect resident attitudes, skills, and performance of HVC as tested by the Internal Medicine In-Training Exam (ITE). Methods : In 2012, we performed a baseline needs assessment among internal medicine residents at a community program regarding drivers of healthcare utilization. We then created a multimodal curriculum with online interactive worksheets, lectures, and faculty buy-in to target specific skills, knowledge, and culture deficiencies. Perceived drivers of care and performance on the Internal Medicine ITE were assessed yearly through 2016. Results : Fourteen of 27 (52%) residents completed the initial needs assessment while the curriculum was eventually seen by at least 24 of 27 (89%). The ITE was taken by every resident every year. Long-term, 3-year follow-up demonstrated persistent improvement in many drivers of utilization (patient requests, reliance on subspecialists, defensive medicine, and academic curiosity) and improvement with sustained high performance on the high-value component of the ITE. Conclusion : A multimodal curriculum targeting specific drivers of low-value care can change culture and lead to sustained improvement in the practice of HVC.

  3. 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.

  4. Sistem Advice Planing Online Dengan Framework Codeigniter Berbasis Web Bootstrap (Studi Kasus: Kabupaten Probolinggo

    Directory of Open Access Journals (Sweden)

    Moh Ainol Yaqin

    2018-05-01

    Full Text Available The information system in the form of Integrated Advice Planning by using CodeIgniter Framework and based on  Framework Bootstrap one of system which gives responsive form. The system is a service as one of solution for e-Government. Advice Planning service is the optimization of public services in the licensing sector and the optimization of agency management. The licensing service is in the form of design consultation and the location of the building in accordance with the Spatial and Regional Plan within a Local Government. Licensing process that must be fulfilled by prospective investors either individually or on behalf of the company and supporting infrastructure around the investment location. The services provided by the Information System have provided Advice Planning application submission online. The system is expected to provide convenience for the community in the region and create a friendly, the comfortable, the transparent and cheap of interaction between the government and the community.

  5. Revalidation and rationale for high pKa values of unconjugated bilirubin

    Directory of Open Access Journals (Sweden)

    Ostrow J Donald

    2007-05-01

    Full Text Available Abstract Background Our prior solvent partition analysis, published in 1992, yielded pKa values for unconjugated bilirubin of about 8.1 and 8.4, but these results have been challenged and studies by other methods have suggested pKa values below 5.0. Methods We repeated our published solvent partition studies, using 14C-unconjugated bilirubin highly purified by extraction of residual labeled impurities from CHCl3 into an aqueous buffer, pH 7.0. Partition ratios at six pH values from 5.0 to 9.0 were determined by radioassay and compared with our prior values obtained by diazo assay. Results At pH values ranging from 4.8 to 9.2, stable aqueous/chloroform 14C-partition ratios did not differ significantly from our published partition ratios based on diazo assay. Conclusion These results support the high pKa values of unconjugated bilirubin, above 8.0, derived from our earlier solvent partition study. In both studies, our measurements were based on the rapid analysis of clearly under-saturated solutions of highly-purified bilirubin over a wide pH range, using properly purified and preserved solvents. No previous direct estimate of the aqueous pKa values of unconjugated bilirubin meets all these preconditions. Three theoretical factors acting in combination, each related to the unique, extensive internal H-bonding of the -COOH groups, are proposed to support high pKa values of unconjugated bilirubin in water: a donation of an H-bond from the -OH moiety of the -COOH group, which is broken on ionization; b hindered solvation of the -COO- group after ionization; and c restricted rotation of the -COO- and -COOH groups. Our findings and rationale rebut methodological and theoretical criticisms leveled against our prior work. High pKa values for unconjugated bilirubin dictate that: a bilirubin diacid, which readily diffuses across membranes and can cause neurotoxicity, is the dominant unbound bilirubin species of unconjugated bilirubin in plasma at

  6. Training Physicians to Provide High-Value, Cost-Conscious Care A Systematic Review

    NARCIS (Netherlands)

    Stammen, L.A.; Stalmeijer, R.E.; Paternotte, E.; Pool, A.O.; Driessen, E.W.; Scheele, F.; Stassen, L.P.S.

    2015-01-01

    Importance Increasing health care expenditures are taxing the sustainability of the health care system. Physicians should be prepared to deliver high-value, cost-conscious care. Objective To understand the circumstances in which the delivery of high-value, cost-conscious care is learned, with a goal

  7. Designing messages with high sensation value: when activation meets reactance.

    Science.gov (United States)

    Xu, Jie

    2015-01-01

    Based on two theoretical models--activation model of information exposure and psychological reactance theory--this study examined the individual and combined effects of message sensation value (MSV) and controlling language on young adults' information processing. Two experimental studies on anti-drunken driving and anti-smoking public service announcements were conducted that were conceptual replications of one another. The measures included perceived threat to freedom, sensation seeking, perceived ad effectiveness and state reactance (anger). Across the two studies, MSV was found to advance the perceived ad effectiveness, and controlling language contributed to anger. A consistent interaction was revealed, such that participants responded positively to the high sensation value messages when presented with low controlling language. The effect of high sensation value anti-smoking ads to advance persuasiveness particularly under the condition of low controlling language was more influential to low sensation seekers. This study suggests that increasing MSV coupled with high controlling language can backfire, especially when targeting young adults. The implications for persuasion in general are considered, as well as the specific findings for drunken driving and smoking.

  8. Novel charge sensitive preamplifier without high-value feedback resistor

    International Nuclear Information System (INIS)

    Xi Deming

    1992-01-01

    A novel charge sensitive preamplifier is introduced. The method of removing the high value feedback resistor, the circuit design and analysis are described. A practical circuit and its measured performances are provided

  9. 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.

  10. High b-value diffusion-weighted MR imaging of normal brain at 3 T

    International Nuclear Information System (INIS)

    Cihangiroglu, Mutlu; Ulug, Aziz Muefit; Firat, Zeynep; Bayram, Ali; Kovanlikaya, Arzu; Kovanlikaya, Ilhami

    2009-01-01

    Introduction: The purpose of this study was to determine the normative apparent diffusion coefficient (ADC) values at 3 T using high b-value (3000 s/mm 2 ) diffusion-weighted images (DWI) and compare the signal characteristics of the high b value with standard b-value (1000 s/mm 2 ) DWI. Methods: Institutional review board approval was obtained for this prospective study which included 20 volunteers (10 M, 10 F, mean age: 38.7 ± 14.9) without any known clinical disease or radiological findings. All brain examinations were performed with 3 T MR by using similar parameters of b1000 and b3000 DWI sequences. DWI and ADC maps were obtained. Signal intensity, noise, signal to noise ratio (SNR), contrast to noise (CNR), contrast ratio (CR), and ADC values of bilateral posterior limb of internal capsule, frontal white matter, parietal gray matter, pons, thalamus, splenium of corpus callosum were measured on b1000 and b3000 DW images. Results: In all anatomic locations, MR signal intensity, SNR and ADC values of b3000 images were significantly lower than MR signal intensity, SNR and ADC values of b1000 images (p < 0.001). The CNR and CR values at the posterior limb of internal capsule and pons were significantly increased on b3000 images (p < 0.001) and decreased in the other regions measured. Conclusion: The ADC values calculated from standard b-value DWI were significantly higher than those calculated from high b-value DWI. These results agree with the previous studies. In the regions where CNR values increase with high b value, b3000 DWI images may provide additional clinical information.

  11. Bootstrap rolling window estimation approach to analysis of the Environment Kuznets Curve hypothesis: evidence from the USA.

    Science.gov (United States)

    Aslan, Alper; Destek, Mehmet Akif; Okumus, Ilyas

    2018-01-01

    This study aims to examine the validity of inverted U-shaped Environmental Kuznets Curve by investigating the relationship between economic growth and environmental pollution for the period from 1966 to 2013 in the USA. Previous studies based on the assumption of parameter stability and obtained parameters do not change over the full sample. This study uses bootstrap rolling window estimation method to detect the possible changes in causal relations and also obtain the parameters for sub-sample periods. The results show that the parameter of economic growth has increasing trend in 1982-1996 sub-sample periods, and it has decreasing trend in 1996-2013 sub-sample periods. Therefore, the existence of inverted U-shaped Environmental Kuznets Curve is confirmed in the USA.

  12. Creating Value for Customer in Business Networks of High-Tech Goods Manufacturers

    Directory of Open Access Journals (Sweden)

    Joanna Wiechoczek

    2016-01-01

    Full Text Available The main paper goal is to recognize the category of value for customer with respect to high-tech products, and to propose a model of creation of this value in business networks established by manufacturers. The research methods include critical analysis of the literature, documentation method, as well as the case research method and observation method. The results of the research proved that the value offered to buyers is characterized by growing multidimensionality which results in increasing complexity of the creation process of this value by their manufacturers. Due to the fact that they do not have complex skills and resources to create the value independently, they form business networks. These networks include increasingly larger group of entities, in which the importance of individual cooperants is highly diversified.

  13. Engineering biosynthesis of high-value compounds in photosynthetic organisms.

    Science.gov (United States)

    O'Neill, Ellis C; Kelly, Steven

    2017-09-01

    The photosynthetic, autotrophic lifestyle of plants and algae position them as ideal platform organisms for sustainable production of biomolecules. However, their use in industrial biotechnology is limited in comparison to heterotrophic organisms, such as bacteria and yeast. This usage gap is in part due to the challenges in generating genetically modified plants and algae and in part due to the difficulty in the development of synthetic biology tools for manipulating gene expression in these systems. Plant and algal metabolism, pre-installed with multiple biosynthetic modules for precursor compounds, bypasses the requirement to install these pathways in conventional production organisms, and creates new opportunities for the industrial production of complex molecules. This review provides a broad overview of the successes, challenges and future prospects for genetic engineering in plants and algae for enhanced or de novo production of biomolecules. The toolbox of technologies and strategies that have been used to engineer metabolism are discussed, and the potential use of engineered plants for industrial manufacturing of large quantities of high-value compounds is explored. This review also discusses the routes that have been taken to modify the profiles of primary metabolites for increasing the nutritional quality of foods as well as the production of specialized metabolites, cosmetics, pharmaceuticals and industrial chemicals. As the universe of high-value biosynthetic pathways continues to expand, and the tools to engineer these pathways continue to develop, it is likely plants and algae will become increasingly valuable for the biomanufacturing of high-value compounds.

  14. A stable route to high-{beta}{sub p} plasmas with non-monotonic q-profiles

    Energy Technology Data Exchange (ETDEWEB)

    Soeldner, F X; Baranov, Y; Bhatnagar, V P; Bickley, A J; Challis, C D; Fischer, B; Gormezano, C; Huysmans, G T.A.; Kerner, W; Rimini, F; Sips, A C.C.; Springmann, R; Taroni, A [Commission of the European Communities, Abingdon (United Kingdom). JET Joint Undertaking; Goedbloed, J P; Holties, H A [Institute for Plasmas Physics, Nieuwegein (Netherlands); Parail, V V; Pereverzev, G V [Kurchatov Institute of Atomic Energy, Moscow (Russian Federation)

    1994-07-01

    Steady-state operation of tokamak reactors seems feasible in so-called Advanced Scenarios with high bootstrap current in high-beta{sub p} operation. The stabilization of such discharges with noninductive profile control will be attempted on JET in pursuit of previous high bootstrap current studies. Results of modelling studies of full noninductive current drive scenarios in JET and ITER are presented. Fast Waves (FW), Lower Hybrid (LH) Waves and Neutral Beam Injection (NBI) are used for heating and current drive, alternatively or in combination. A stable route to nonmonotonic q-profiles has been found with a specific ramp-up scenario which combines LH-current drive (LHCD) and a fast Ohmic ramp-up. A hollow current profile with deep shear reversal over the whole central region is thereby formed in an early low-beta phase and frozen in by additional heating. (authors). 5 refs., 4 figs.

  15. How high are option values in energy-efficiency investments?

    International Nuclear Information System (INIS)

    Sanstad, A.H.; Blumstein, C.; Stoft, S.E.; California Univ., Berkeley, CA,

    1995-01-01

    High implicit discount rates in consumers' energy-efficiency investments have long been a source of controversy. In several recent papers, Hassett and Metcalf argue that the uncertainty and irreversibility attendant to such investments, and the resulting option value, account for this anomalously high implicit discounting. Using their model and data, we show that, to the contrary, their analysis falls well short of providing an explanation of this pattern. (author)

  16. Estimating the efficiency from Brazilian banks: a bootstrapped Data Envelopment Analysis (DEA

    Directory of Open Access Journals (Sweden)

    Ana Elisa Périco

    2016-01-01

    Full Text Available Abstract The Brazilian banking sector went through several changes in its structure over the past few years. Such changes are related to fusions and acquisitions, as well as the largest market opening to foreign banks. The objective of this paper is to analyze, by applying the bootstrap DEA, the efficiency of banks in Brazil in 2010-2013. The methodology was applied to 30 largest banking organizations in a financial intermediation approach. In that model, the resources entering a bank in the form of deposits and total assets are classified as inputs and besides these manual labor is also considered as a resource capable of generating results. For the output variable, credit operations represent the most appropriate alternative, considering the role of the bank as a financial intermediary. In this work, the matter of the best classification among retail banks and banks specialized in credit has little relevance. The low relevance in this type of comparison is a result of analysis by segments (segments were analyzed separately. The results presented here point to an average level of efficiency for the large Brazilian banks in the period. This scenario requires efforts to reduce expenses but also to increase revenues.

  17. Eficiência dos aeroportos internacionais brasileiros: uma análise envoltória de dados com bootstrap

    Directory of Open Access Journals (Sweden)

    Ana Elisa Périco

    Full Text Available Resumo A eficiência adquiriu maior relevância entre as organizações no cenário de mercados abertos, que teve início no Brasil por volta dos anos 1990. O objetivo deste artigo foi analisar, por envoltória de dados com bootstrap, a eficiência dos aeroportos brasileiros, utilizando as bases de dados da Agência Nacional de Aviação Civil (ANAC e da Empresa Brasileira de Infraestrutura Aeroportuária (INFRAERO de 2010, 2011 e 2012. Uma regressão múltipla foi utilizada para validar as variáveis do modelo proposto. Nesse modelo, a medida utilizada para representar o desempenho dos aeroportos foi a quantidade de passageiros processados (variável dependente; para as variáveis que determinam o desempenho (variáveis independentes foram utilizados: número de pistas, número de balcões de check-in, número de estacionamento de aeronaves e área de passageiros. A partir de então, a técnica Análise Envoltória de Dados foi aplicada para os 16 aeroportos internacionais brasileiros, em abordagem operacional. Para corrigir os valores de eficiência encontrados, tendo em vista o erro aleatório inerente aos dados, aplicou-se uma abordagem da técnica de bootstrap. Os resultados encontrados apontam que a grandeza de um aeroporto não foi determinante para atribuir eficiência, embora seja critério relevante para impulsionar melhorias no seu desempenho. Convém salientar, também, que a utilização dos recursos (inputs para o alcance do produto (output foi o critério mais relevante na busca do bom desempenho e da eficiência aeroportuária no estudo aqui apresentado. Nesse sentido, o aeroporto de Curitiba, na Região Sul do país, foi classificado como o mais eficiente em todos os períodos, e os aeroportos do Galeão (Rio de Janeiro e Manaus (Amazonas como os menos eficientes.

  18. High throughput screening and profiling of high-value carotenoids from a wide diversity of bacteria in surface seawater.

    Science.gov (United States)

    Asker, Dalal

    2018-09-30

    Carotenoids are valuable natural colorants that exhibit numerous health promoting properties, and thus are widely used in food, feeds, pharmaceutical and nutraceuticals industries. In this study, we isolated and identified novel microbial sources that produced high-value carotenoids using high throughput screening (HTS). A total of 701 pigmented microbial strains library including marine bacteria and red yeast was constructed. Carotenoids profiling using HPLC-DAD-MS methods showed 88 marine bacterial strains with potential for the production of high-value carotenoids including astaxanthin (28 strains), zeaxanthin (21 strains), lutein (1 strains) and canthaxanthin (2 strains). A comprehensive 16S rRNA gene based phylogenetic analysis revealed that these strains can be classified into 30 species belonging to five bacterial classes (Flavobacteriia, α-Proteobacteria, γ-Proteobacteria, Actinobacteria and Bacilli). Importantly, we discovered novel producers of zeaxanthin and lutein, and a high diversity in both carotenoids and producing microbial strains, which are promising and highly selective biotechnological sources for high-value carotenoids. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Bootstrap calculation of ultimate strength temperature maxima for neutron irradiated ferritic/martensitic steels

    Science.gov (United States)

    Obraztsov, S. M.; Konobeev, Yu. V.; Birzhevoy, G. A.; Rachkov, V. I.

    2006-12-01

    The dependence of mechanical properties of ferritic/martensitic (F/M) steels on irradiation temperature is of interest because these steels are used as structural materials for fast, fusion reactors and accelerator driven systems. Experimental data demonstrating temperature peaks in physical and mechanical properties of neutron irradiated pure iron, nickel, vanadium, and austenitic stainless steels are available in the literature. A lack of such an information for F/M steels forces one to apply a computational mathematical-statistical modeling methods. The bootstrap procedure is one of such methods that allows us to obtain the necessary statistical characteristics using only a sample of limited size. In the present work this procedure is used for modeling the frequency distribution histograms of ultimate strength temperature peaks in pure iron and Russian F/M steels EP-450 and EP-823. Results of fitting the sums of Lorentz or Gauss functions to the calculated distributions are presented. It is concluded that there are two temperature (at 360 and 390 °C) peaks of the ultimate strength in EP-450 steel and single peak at 390 °C in EP-823.

  20. Confidence limits for contribution plots in multivariate statistical process control using bootstrap estimates.

    Science.gov (United States)

    Babamoradi, Hamid; van den Berg, Frans; Rinnan, Åsmund

    2016-02-18

    In Multivariate Statistical Process Control, when a fault is expected or detected in the process, contribution plots are essential for operators and optimization engineers in identifying those process variables that were affected by or might be the cause of the fault. The traditional way of interpreting a contribution plot is to examine the largest contributing process variables as the most probable faulty ones. This might result in false readings purely due to the differences in natural variation, measurement uncertainties, etc. It is more reasonable to compare variable contributions for new process runs with historical results achieved under Normal Operating Conditions, where confidence limits for contribution plots estimated from training data are used to judge new production runs. Asymptotic methods cannot provide confidence limits for contribution plots, leaving re-sampling methods as the only option. We suggest bootstrap re-sampling to build confidence limits for all contribution plots in online PCA-based MSPC. The new strategy to estimate CLs is compared to the previously reported CLs for contribution plots. An industrial batch process dataset was used to illustrate the concepts. Copyright © 2016 Elsevier B.V. All rights reserved.

  1. Mass transport and the bootstrap current from Ohm's law in steady-state tokamaks

    International Nuclear Information System (INIS)

    Kim, J.-S.; Greene, J.M.

    1989-01-01

    The consequences of mass conservation and Ohm's law are examined for steady state Tokamaks. In a Tokamak, magnetofluid-dynamic waves rapidly equilibrate pressure and toroidal field along magnetic surfaces. As a result, the detailed current distribution is determined by the flux surface averaged poloidal and toroidal currents. The electrons that carry the plasma current are impeded in their motion by interactions with ions, which is resistivity and its generalizations, and by interactions with electrons, which is viscosity and its generalizations. The important viscous terms arise from the interaction between trapped and untrapped electrons, and so viscosity acts by impeding poloidal current. properly chosen, the results of neoclassical theory are The neoclassical viscous coefficient is here regarded as less likely than Spitzer conductivity to be experimentally relevant in a turbulent Tokamak. Thus, the toroidal Ohm's law is regarded as being more reliable than the poloidal Ohm's law. A combination of toroidal and poloidal Ohm's law, namely the component parallel to the magnetic field, eliminates the influence of plasma fueling, and directly relates the bootstrap current and the pressure gradient. The latter is the usual relation, but, since i

  2. Uma Comparação entre Técnicas de Propagação de Erros em Astrofísica: Monte Carlo x Bootstrap

    Science.gov (United States)

    Zabot, Alexandre; Baptista, Raymundo

    2005-07-01

    Neste trabalho é feito um estudo comparativo entre dois algoritmos numéricos usados para propagação de erros em dados experimentais. Um deles é conhecido por Método de Monte carlo e o outro por Método de Bootstrap. Recentemente, Dhullon & Watson argüiram que a aplicação do método de Monte Carlo introduz ruído nos dados, e propuseram então a utilização do Bootstrap como alternativa capaz de produzir resultados superiores. O objetivo deste trabalho é testar a validade dessa afirmação. As duas técnicas foram aplicadas a três problemas diferentes: o ajsute de modelos de emissão LTE simples e atmosfera estelar a espectros estelares observados e o ajuste de curvas de luz de eclipses de Variáveis Cataclísmicas para a detemrinação da distribuição radial de brilho dos seus discos de acréscimo. Os métodos foram testados quanto à sua robusteza, ou seja, a capacidade de prover resultados coerentes enre si. Além disso, as soluções dos métodos foram comparadas. Os resultados indicam que não existe evidência de superioridade de um métodos em relação ao outro.

  3. Quantifying uncertainties in the estimation of safety parameters by using bootstrapped artificial neural networks

    Energy Technology Data Exchange (ETDEWEB)

    Secchi, Piercesare [MOX, Department of Mathematics, Polytechnic of Milan (Italy); Zio, Enrico [Department of Energy, Polytechnic of Milan, Via Ponzio 34/3, 20133 Milano (Italy)], E-mail: enrico.zio@polimi.it; Di Maio, Francesco [Department of Energy, Polytechnic of Milan, Via Ponzio 34/3, 20133 Milano (Italy)

    2008-12-15

    For licensing purposes, safety cases of Nuclear Power Plants (NPPs) must be presented at the Regulatory Authority with the necessary confidence on the models used to describe the plant safety behavior. In principle, this requires the repetition of a large number of model runs to account for the uncertainties inherent in the model description of the true plant behavior. The present paper propounds the use of bootstrapped Artificial Neural Networks (ANNs) for performing the numerous model output calculations needed for estimating safety margins with appropriate confidence intervals. Account is given both to the uncertainties inherent in the plant model and to those introduced by the ANN regression models used for performing the repeated safety parameter evaluations. The proposed framework of analysis is first illustrated with reference to a simple analytical model and then to the estimation of the safety margin on the maximum fuel cladding temperature reached during a complete group distribution header blockage scenario in a RBMK-1500 nuclear reactor. The results are compared with those obtained by a traditional parametric approach.

  4. The "Globularization Hypothesis" of the Language-ready Brain as a Developmental Frame for Prosodic Bootstrapping Theories of Language Acquisition.

    Science.gov (United States)

    Irurtzun, Aritz

    2015-01-01

    In recent research (Boeckx and Benítez-Burraco, 2014a,b) have advanced the hypothesis that our species-specific language-ready brain should be understood as the outcome of developmental changes that occurred in our species after the split from Neanderthals-Denisovans, which resulted in a more globular braincase configuration in comparison to our closest relatives, who had elongated endocasts. According to these authors, the development of a globular brain is an essential ingredient for the language faculty and in particular, it is the centrality occupied by the thalamus in a globular brain that allows its modulatory or regulatory role, essential for syntactico-semantic computations. Their hypothesis is that the syntactico-semantic capacities arise in humans as a consequence of a process of globularization, which significantly takes place postnatally (cf. Neubauer et al., 2010). In this paper, I show that Boeckx and Benítez-Burraco's hypothesis makes an interesting developmental prediction regarding the path of language acquisition: it teases apart the onset of phonological acquisition and the onset of syntactic acquisition (the latter starting significantly later, after globularization). I argue that this hypothesis provides a developmental rationale for the prosodic bootstrapping hypothesis of language acquisition (cf. i.a. Gleitman and Wanner, 1982; Mehler et al., 1988, et seq.; Gervain and Werker, 2013), which claim that prosodic cues are employed for syntactic parsing. The literature converges in the observation that a large amount of such prosodic cues (in particular, rhythmic cues) are already acquired before the completion of the globularization phase, which paves the way for the premises of the prosodic bootstrapping hypothesis, allowing babies to have a rich knowledge of the prosody of their target language before they can start parsing the primary linguistic data syntactically.

  5. The globularization hypothesis of the language-ready brain as a developmental frame for prosodic bootstrapping theories of language acquisition

    Directory of Open Access Journals (Sweden)

    Aritz eIrurtzun

    2015-12-01

    Full Text Available In recent research Boeckx & Benítez-Burraco (2014a,b have advanced the hypothesis that our species-specific language-ready brain should be understood as the outcome of developmental changes that occurred in our species after the split from Neanderthals-Denisovans, which resulted in a more globular braincase configuration in comparison to our closest relatives, who had elongated endocasts. According to these authors, the development of a globular brain is an essential ingredient for the language faculty and in particular, it is the centrality occupied by the thalamus in a globular brain that allows its modulatory or regulatory role, essential for syntactico-semantic computations. Their hypothesis is that the syntactico-semantic capacities arise in humans as a consequence of a process of globularization, which significantly takes place postnatally (cf. Neubauer et al. (2010. In this paper, I show that Boeckx & Benítez-Burraco’s hypothesis makes an interesting developmental prediction regarding the path of language acquisition: it teases apart the onset of phonological acquisition and the onset of syntactic acquisition (the latter starting significantly later, after globularization. I argue that this hypothesis provides a developmental rationale for the prosodic bootstrapping hypothesis of language acquisition (cf. i.a. Gleitman & Wanner (1982; Mehler et al. (1988, et seq.; Gervain & Werker (2013, which claim that prosodic cues are employed for syntactic parsing. The literature converges in the observation that a large amount of such prosodic cues (in particular, rhythmic cues are already acquired before the completion of the globularization phase, which paves the way for the premises of prosodic bootstrapping hypothesis, allowing babies to have a rich knowledge of the prosody of their target language before they can start parsing the primary linguistic data syntactically.

  6. Physics Basis for a Spherical Torus Power Plant

    International Nuclear Information System (INIS)

    Kessel, C.E.; Menard, J.; Jardin, S.C.; Mau, T.K.

    1999-01-01

    The spherical torus, or low-aspect-ratio tokamak, is considered as the basis for a fusion power plant. A special class of wall-stabilized high-beta high-bootstrap fraction low-aspect-ratio tokamak equilibrium are analyzed with respect to MHD stability, bootstrap current and external current drive, poloidal field system requirements, power and particle exhaust and plasma operating regime. Overall systems optimization leads to a choice of aspect ratio A = 1:6, plasma elongation kappa = 3:4, and triangularity delta = 0:64. The design value for the plasma toroidal beta is 50%, corresponding to beta N = 7:4, which is 10% below the ideal stability limit. The bootstrap fraction of 99% greatly alleviates the current drive requirements, which are met by tangential neutral beam injection. The design is such that 45% of the thermal power is radiated in the plasma by Bremsstrahlung and trace Krypton, with Neon in the scrapeoff layer radiating the remainder

  7. Projeção do Custo do Suco de Laranja Pela Aplicação da Simulação Bootstrap

    OpenAIRE

    Joaquim Eduardo de Moura Nicacio

    2014-01-01

    Essa pesquisa teve por objetivo a utilização da técnica Bootstrap na determinação do volume médio populacional de suco de laranja, obtida entre quatro amostras provenientes de produtores dessa fruta denominada Citrus sinensis (L) Osbeck, do município de Primavera do Leste.  A cadeia de produção agroindustrial da laranja, ainda incipiente nesse município, deve ser monitorada em suas operações principalmente a industrialização e, a qualidade da matéria prima deve ser rigorosamente controlada. A...

  8. Solving the 3d Ising Model with the Conformal Bootstrap II. c-Minimization and Precise Critical Exponents

    CERN Document Server

    El-Showk, Sheer; Poland, David; Rychkov, Slava; Simmons-Duffin, David; Vichi, Alessandro

    2014-01-01

    We use the conformal bootstrap to perform a precision study of the operator spectrum of the critical 3d Ising model. We conjecture that the 3d Ising spectrum minimizes the central charge c in the space of unitary solutions to crossing symmetry. Because extremal solutions to crossing symmetry are uniquely determined, we are able to precisely reconstruct the first several Z2-even operator dimensions and their OPE coefficients. We observe that a sharp transition in the operator spectrum occurs at the 3d Ising dimension Delta_sigma=0.518154(15), and find strong numerical evidence that operators decouple from the spectrum as one approaches the 3d Ising point. We compare this behavior to the analogous situation in 2d, where the disappearance of operators can be understood in terms of degenerate Virasoro representations.

  9. Screening for cancer: advice for high-value care from the American College of Physicians.

    Science.gov (United States)

    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.

  10. Cyanobacteria as a Platform for the High-Value Chemicals Production

    DEFF Research Database (Denmark)

    Wlodarczyk, Artur Jacek

    and cheap fertilizer as a medium for the cultivation of engineered cyanobacterial strains is shown. Alternative strategy to engineer Synechocystis sp. PCC 6803 as a universal platform for the sustainable production of diverse range high-value phenylpropanoids which find use as pharmaceuticals, cosmetics......Emerging problems like increasing global warming and depletion of fossil fuels bring serious concerns regarding production of food and various chemicals in the future. Clearly, there is a need for finding alternative and more sustainable ways of producing chemicals in order to satisfy increasing...... 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...

  11. High and ultra-high b-value diffusion-weighted imaging in prostate cancer: a quantitative analysis.

    Science.gov (United States)

    Wetter, Axel; Nensa, Felix; Lipponer, Christine; Guberina, Nika; Olbricht, Tobias; Schenck, Marcus; Schlosser, Thomas W; Gratz, Marcel; Lauenstein, Thomas C

    2015-08-01

    Diffusion-weighted imaging (DWI) is routinely used in magnetic resonance imaging (MRI) of prostate cancer. However, the routine use of b values higher than 1000 s/mm(2) is not clear up to present. Moreover, the complex diffusion behavior of malignant and benign prostate tissues hampers precise predictions of contrast in DWI images and apparent diffusion coefficient (ADC) maps. To quantitatively analyze DWI with different b values in prostate cancer and to identify b values best suitable for cancer detection. Forty-one patients with histologically proven prostate cancer were examined with high resolution T2-weighted imaging and DWI at 3 Tesla. Five different b values (0, 800, 1000, 1500, 2000 s/mm(2)) were applied. ADC values of tumors and reference areas were measured on ADC maps derived from different pairs of b values. Furthermore, signal intensities of DW images of tumors and reference areas were measured. For analysis, contrast ratios of ADC values and signal intensities of DW images were calculated and compared. No significant differences were found between contrast ratios measured on ADC maps of all analyzed b value pairs (P = 0.43). Contrast ratios calculated from signal intensities of DW images were highest at b values of 1500 and 2000 s/mm(2) and differed significantly from contrast ratios at b values of 800 and 1000 s/mm(2) (P values, contrast ratios of DW images are significantly higher at b-values of 1500 and 2000 s/mm(2) in comparison to b values of 800 and 1000 s/mm(2). Therefore, diagnostic performance of DWI in prostate cancer might be increased by application of b values higher than 1000 s/mm(2). © The Foundation Acta Radiologica 2014.

  12. Memory, priority encoding, and overcoming high-value proactive interference in younger and older adults.

    Science.gov (United States)

    Friedman, Michael C; Castel, Alan D

    2013-01-01

    It is often necessary to remember important information while directing attention away from encoding less valuable information. To examine how aging influences the ability to control and update the encoding of high-value information, younger and older adults studied six lists of words that varied in terms of the point values associated with each word. The words were paired with the same high and low point values for three study-test cycles, but on the fourth and subsequent cycles the value-word pairings were switched such that the lowest value pairs became the highest values (and vice versa). For the first three study-test cycles, younger adults outperformed older adults in terms of the number of words recalled and overall point totals, but performance was similar in terms of selectively remembering high-value words. When the values were switched, both groups displayed substantial interference from the previous pairings. Although both groups improved with additional study-test cycles, only younger adults were able to fully recover from the interference effects. A similar, and more pronounced, set of results were obtained when positive and negative point values were paired with the words. The findings are interpreted in a value-directed remembering framework, emphasizing the role of benefits and costs of strategic encoding and age-related differences in the effects of interference on memory.

  13. Optimal high b-value for diffusion weighted MRI in diagnosing high risk prostate cancers in the peripheral zone.

    Science.gov (United States)

    Agarwal, Harsh K; Mertan, Francesca V; Sankineni, Sandeep; Bernardo, Marcelino; Senegas, Julien; Keupp, Jochen; Daar, Dagane; Merino, Maria; Wood, Bradford J; Pinto, Peter A; Choyke, Peter L; Turkbey, Baris

    2017-01-01

    To retrospectively determine the optimal b-value(s) of diffusion-weighted imaging (DWI) associated with intermediate-high risk cancer in the peripheral zone (PZ) of the prostate. Forty-two consecutive patients underwent multi b-value (16 evenly spaced b-values between 0 and 2000 s/mm 2 ) DWI along with multi-parametric MRI (MP-MRI) of the prostate at 3 Tesla followed by trans-rectal ultrasound/MRI fusion guided targeted biopsy of suspicious lesions detected at MP-MRI. Computed DWI images up to a simulated b-value of 4000 s/mm 2 were also obtained using a pair of b-values (b = 133 and 400 or 667 or 933 s/mm 2 ) from the multi b-value DWI. The contrast ratio of average intensity of the targeted lesions and the background PZ was determined. Receiver operator characteristic curves and the area under the curve (AUCs) were obtained for separating patients eligible for active surveillance with low risk prostate cancers from intermediate-high risk prostate cancers as per the cancer of the prostate risk assessment (CAPRA) scoring system. The AUC first increased then decreased with the increase in b-values reaching maximum at b = 1600 s/mm 2 (0.74) with no statistically significant different AUC of DWI with b-values 1067-2000 s/mm 2 . The AUC of computed DWI increased then decreased with the increase in b-values reaching a maximum of 0.75 around b = 2000 s/mm 2 . There was no statistically significant difference between the AUC of optimal acquired DWI and either of optimal computed DWI. The optimal b-value for acquired DWI in differentiating intermediate-high from low risk prostate cancers in the PZ is b = 1600 s/mm 2 . The computed DWI has similar performance as that of acquired DWI with the optimal performance around b = 2000 s/mm 2 . 4 J. Magn. Reson. Imaging 2017;45:125-131. © 2016 International Society for Magnetic Resonance in Medicine.

  14. PCA-based bootstrap confidence interval tests for gene-disease association involving multiple SNPs

    Directory of Open Access Journals (Sweden)

    Xue Fuzhong

    2010-01-01

    Full Text Available Abstract Background Genetic association study is currently the primary vehicle for identification and characterization of disease-predisposing variant(s which usually involves multiple single-nucleotide polymorphisms (SNPs available. However, SNP-wise association tests raise concerns over multiple testing. Haplotype-based methods have the advantage of being able to account for correlations between neighbouring SNPs, yet assuming Hardy-Weinberg equilibrium (HWE and potentially large number degrees of freedom can harm its statistical power and robustness. Approaches based on principal component analysis (PCA are preferable in this regard but their performance varies with methods of extracting principal components (PCs. Results PCA-based bootstrap confidence interval test (PCA-BCIT, which directly uses the PC scores to assess gene-disease association, was developed and evaluated for three ways of extracting PCs, i.e., cases only(CAES, controls only(COES and cases and controls combined(CES. Extraction of PCs with COES is preferred to that with CAES and CES. Performance of the test was examined via simulations as well as analyses on data of rheumatoid arthritis and heroin addiction, which maintains nominal level under null hypothesis and showed comparable performance with permutation test. Conclusions PCA-BCIT is a valid and powerful method for assessing gene-disease association involving multiple SNPs.

  15. Role of high l values in the onset of incomplete fusion

    International Nuclear Information System (INIS)

    Singh, Pushpendra P.; Yadav, Abhishek; Singh, Devendra P.; Gupta, Unnati; Singh, D.; Ansari, M. A.; Singh, B. P.; Prasad, R.; Sharma, Manoj K.; Kumar, R.; Singh, R. P.; Muralithar, S.; Bhowmik, R. K.

    2009-01-01

    A particle-γ-coincidence experiment is performed to investigate the role of high l values in the production of direct-α-emitting channels (associated with incomplete fusion) in 12 C+ 169 Tm system. Spin distributions of various xn/pxn/αxn/2αxn channels are measured at E lab =5.6A and 6.5A MeV. Entirely different de-excitation patterns are observed in direct-α-emitting channels and fusion-evaporation channels. The fusion-evaporation channels are found to be strongly fed over a broad spin range. While narrow range feeding for only high-spin states was observed in the case of direct-α-emitting channels, in the present work, incomplete fusion is shown to be a promising tool to populate high-spin states in final reaction products. To have better insight into the associated l values in different reaction channels, the present data are compared with similar data obtained in 16 O(E lab ≅5.6A MeV) + 169 Tm system. The mean driving angular momenta involved in the production of direct-α-emitting channels are found to be higher than those involved in the production of fusion-evaporation channels. Direct-α multiplicity in the forward cone increases with driving angular momenta, which indicates the origin of direct-α-emitting channels at high l values in noncentral interactions.

  16. Bootstrap confidence intervals and bias correction in the estimation of HIV incidence from surveillance data with testing for recent infection.

    Science.gov (United States)

    Carnegie, Nicole Bohme

    2011-04-15

    The incidence of new infections is a key measure of the status of the HIV epidemic, but accurate measurement of incidence is often constrained by limited data. Karon et al. (Statist. Med. 2008; 27:4617–4633) developed a model to estimate the incidence of HIV infection from surveillance data with biologic testing for recent infection for newly diagnosed cases. This method has been implemented by public health departments across the United States and is behind the new national incidence estimates, which are about 40 per cent higher than previous estimates. We show that the delta method approximation given for the variance of the estimator is incomplete, leading to an inflated variance estimate. This contributes to the generation of overly conservative confidence intervals, potentially obscuring important differences between populations. We demonstrate via simulation that an innovative model-based bootstrap method using the specified model for the infection and surveillance process improves confidence interval coverage and adjusts for the bias in the point estimate. Confidence interval coverage is about 94–97 per cent after correction, compared with 96–99 per cent before. The simulated bias in the estimate of incidence ranges from −6.3 to +14.6 per cent under the original model but is consistently under 1 per cent after correction by the model-based bootstrap. In an application to data from King County, Washington in 2007 we observe correction of 7.2 per cent relative bias in the incidence estimate and a 66 per cent reduction in the width of the 95 per cent confidence interval using this method. We provide open-source software to implement the method that can also be extended for alternate models.

  17. An application of a double bootstrap to investigate the effects of technological progress on total-factor energy consumption performance in China

    International Nuclear Information System (INIS)

    Li, Ke; Lin, Boqiang

    2017-01-01

    This paper proposes a total-factor energy consumption performance index (TEPI) for measuring China's energy efficiency across 30 provinces during the period 1997 to 2012. The TEPI is derived by solving an improved non-radial data envelopment analysis (DEA) model, which is based on an energy distance function. The production possibility set is constructed by combining the super-efficiency and sequential DEA models to avoid “discriminating power problem” and “technical regress”. In order to explore the impacts of technological progress on TEPI and perform statistical inferences on the results, a two-stage double bootstrap approach is adopted. The important findings are that China's energy technology innovation produces a negative effect on TEPI, while technology import and imitative innovation produce positive effects on TEPI. Thus, the main contribution of TEPI improvement is technology import. These conclusions imply that technology import especially foreign direct investment (FDI) is important for imitative innovation and can improve China's energy efficiency. In the long run, as the technical level of China approaches to the frontier, energy technology innovation and its wide adoption become a sustained way to improve energy efficiency. Therefore, it is urgent for China to introduce measures such as technology translation and spillover policies as well as energy pricing reforms to support energy technology innovation. - Highlights: • A total-factor energy consumption performance index (TEPI) is introduced. • Three types of technological progress have various effects on TEPI. • FDI is the main contributor of TEPI improvement. • An improved DEA calculation method is introduced. • A two-stage double-bootstrap non-radial DEA model is used.

  18. Orthogonal projections and bootstrap resampling procedures in the study of infraspecific variation

    Directory of Open Access Journals (Sweden)

    Luiza Carla Duarte

    1998-12-01

    Full Text Available The effect of an increase in quantitative continuous characters resulting from indeterminate growth upon the analysis of population differentiation was investigated using, as an example, a set of continuous characters measured as distance variables in 10 populations of a rodent species. The data before and after correction for allometric size effects using orthogonal projections were analyzed with a parametric bootstrap resampling procedure applied to canonical variate analysis. The variance component of the distance measures attributable to indeterminate growth within the populations was found to be substantial, although the ordination of the populations was not affected, as evidenced by the relative and absolute positions of the centroids. The covariance pattern of the distance variables used to infer the nature of the morphological differences was strongly influenced by indeterminate growth. The uncorrected data produced a misleading picture of morphological differentiation by indicating that groups of populations differed in size. However, the data corrected for allometric effects clearly demonstrated that populations differed morphologically both in size and shape. These results are discussed in terms of the analysis of morphological differentiation among populations and the definition of infraspecific geographic units.A influência do aumento em caracteres quantitativos contínuos devido ao crescimento indeterminado sobre a análise de diferenciação entre populações foi investigado utilizando como exemplo um conjunto de dados de variáveis craniométricas em 10 populações de uma espécie de roedor. Dois conjuntos de dados, um não corrigido para o efeito alométrico do tamanho e um outro corrigido para o efeito alométrico do tamanho utilizando um método de projeção ortogonal, foram analisados por um procedimento "bootstrap" de reamostragem aplicado à análise de variáveis canônicas. O componente de variância devido ao

  19. Co-integration Rank Testing under Conditional Heteroskedasticity

    DEFF Research Database (Denmark)

    Cavaliere, Guiseppe; Rahbæk, Anders; Taylor, A.M. Robert

    null distributions of the rank statistics coincide with those derived by previous authors who assume either i.i.d. or (strict and covariance) stationary martingale difference innovations. We then propose wild bootstrap implementations of the co-integrating rank tests and demonstrate that the associated...... bootstrap rank statistics replicate the first-order asymptotic null distributions of the rank statistics. We show the same is also true of the corresponding rank tests based on the i.i.d. bootstrap of Swensen (2006). The wild bootstrap, however, has the important property that, unlike the i.i.d. bootstrap......, it preserves in the re-sampled data the pattern of heteroskedasticity present in the original shocks. Consistent with this, numerical evidence sug- gests that, relative to tests based on the asymptotic critical values or the i.i.d. bootstrap, the wild bootstrap rank tests perform very well in small samples un...

  20. Using the Bootstrap to Account for Linkage Errors when Analysing Probabilistically Linked Categorical Data

    Directory of Open Access Journals (Sweden)

    Chipperfield James O.

    2015-09-01

    Full Text Available Record linkage is the act of bringing together records that are believed to belong to the same unit (e.g., person or business from two or more files. Record linkage is not an error-free process and can lead to linking a pair of records that do not belong to the same unit. This occurs because linking fields on the files, which ideally would uniquely identify each unit, are often imperfect. There has been an explosion of record linkage applications, particularly involving government agencies and in the field of health, yet there has been little work on making correct inference using such linked files. Naively treating a linked file as if it were linked without errors can lead to biased inferences. This article develops a method of making inferences for cross tabulated variables when record linkage is not an error-free process. In particular, it develops a parametric bootstrap approach to estimation which can accommodate the sophisticated probabilistic record linkage techniques that are widely used in practice (e.g., 1-1 linkage. The article demonstrates the effectiveness of this method in a simulation and in a real application.

  1. Clinical usefulness of diffusion-weighted imaging using low and high b-values to detect rectal cancer

    International Nuclear Information System (INIS)

    Hosonuma, Tomonori; Tozaki, Mitsuhiro; Ichiba, Noriatsu; Sakuma, Tohru; Hayashi, Daichi; Yanaga, Katsuhiko; Fukuda, Kunihiko

    2006-01-01

    The purpose of this study was to assess the potential role of diffusion-weighted imaging (DWI) using low and high b-values to detect rectal cancer. The subjects were 15 patients diagnosed endoscopically with rectal cancer (m in 1 patient, sm in 0, mp in 3, ss in 7, se in 1, a in 3) and 20 patients diagnosed endoscopically with colon cancer and no other lesions (control group). Magnetic resonance imaging was performed using a 1.5T system. DWI was performed in the axial plane using echo planar imaging sequence (repetition time/echo time 1200/66, field of view 306 X 350 mm, reconstruction matrix 156 x 256, pixel size 2.0 x 1.4 x 8.0 mm) and acquired with 2 b-values (50 and 800 s/mm 2 ). Low and high b-value DW images were analyzed visually. A lesion was positive by detection of a focal area of high signal in the rectum in high b-value images. The apparent diffusion coefficient (ADC) values of areas of high signal in high b-value images were calculated from the low and high b-value images. High b-value images enabled visualization of all 15 rectal cancers. In the control group, 13 cases were classified as negative and 7 cases as positive for rectal cancer. Sensitivity for detection of rectal cancer was 100% (15/15), and specificity was 65% (13/20). The mean ADC values in 7 patients with false-positive lesions and in 15 patients with rectal cancer were 1.374 x 10 -3 mm 2 /s (standard deviation [SD]: 0.157) and 1.194 x 10 -3 mm 2 /s (SD: 0.152), respectively (P=0.026). DWI with low and high b-values may be used to screen for rectal cancer. (author)

  2. Progress toward fully noninductive, high beta conditions in DIII-D

    International Nuclear Information System (INIS)

    Murakami, M.; Wade, M.R.; Greenfield, C.M.; Luce, T.C.; Ferron, J.R.; St John, H.E.; DeBoo, J.C.; Osborne, T.H.; Petty, C.C.; Politzer, P.A.; Burrell, K.H.; Gohil, P.; Gorelov, I.A.; Groebner, R.J.; Hyatt, A.W.; Kajiwara, K.; La Haye, R.J.; Lao, L.L.; Leonard, A.W.; Lohr, J.

    2006-01-01

    The DIII-D Advanced Tokamak (AT) program in the DIII-D tokamak [J. L. Luxon, Plasma Physics and Controlled Fusion Research, 1986, Vol. I (International Atomic Energy Agency, Vienna, 1987), p. 159] is aimed at developing a scientific basis for steady-state, high-performance operation in future devices. This requires simultaneously achieving 100% noninductive operation with high self-driven bootstrap current fraction and toroidal beta. Recent progress in this area includes demonstration of 100% noninductive conditions with toroidal beta, β T =3.6%, normalized beta, β N =3.5, and confinement factor, H 89 =2.4 with the plasma current driven completely by bootstrap, neutral beam current drive, and electron cyclotron current drive (ECCD). The equilibrium reconstructions indicate that the noninductive current profile is well aligned, with little inductively driven current remaining anywhere in the plasma. The current balance calculation improved with beam ion redistribution that was supported by recent fast ion diagnostic measurements. The duration of this state is limited by pressure profile evolution, leading to magnetohydrodynamic (MHD) instabilities after about 1 s or half of a current relaxation time (τ CR ). Stationary conditions are maintained in similar discharges (∼90% noninductive), limited only by the 2 s duration (1τ CR ) of the present ECCD systems. By discussing parametric scans in a global parameter and profile databases, the need for low density and high beta are identified to achieve full noninductive operation and good current drive alignment. These experiments achieve the necessary fusion performance and bootstrap fraction to extrapolate to the fusion gain, Q=5 steady-state scenario in the International Thermonuclear Experimental Reactor (ITER) [R. Aymar et al., Fusion Energy Conference on Controlled Fusion and Plasma Physics, Sorrento, Italy (International Atomic Energy Agency, Vienna, 1987), paper IAEA-CN-77/OV-1]. The modeling tools that have

  3. Value-at-Risk Analysis for the Tunisian Currency Market: A comparative study

    Directory of Open Access Journals (Sweden)

    Aymen Ben Rejeb

    2012-01-01

    Full Text Available The main purpose of this paper is to compare empirically four Value-at-Risk simulation methods, namely, the Variance-Covariance, the Historical Simulation, the Bootstrapping and the Monte Carlo. We tried to estimate the VaR associated to three currencies and four currency portfolios in the Tunisian exchange market. Data covers the period between 01-01-1999 and 31-12-2007. Independently of the used technique, the Japanese Yen seems to be the most risky currency. Moreover, the portfolio diversification reduces the exchange rate risk. Lastly, the number of violations, when they exist, does not generally differ between the simulation methods. Recent evaluation tests were applied to select the most appropriate technique predicting precisely the exchange rate risk. Results based on these tests suggest that the traditional Variance-Covariance is the most appropriate method.

  4. A counterfactual p-value approach for benefit-risk assessment in clinical trials.

    Science.gov (United States)

    Zeng, Donglin; Chen, Ming-Hui; Ibrahim, Joseph G; Wei, Rachel; Ding, Beiying; Ke, Chunlei; Jiang, Qi

    2015-01-01

    Clinical trials generally allow various efficacy and safety outcomes to be collected for health interventions. Benefit-risk assessment is an important issue when evaluating a new drug. Currently, there is a lack of standardized and validated benefit-risk assessment approaches in drug development due to various challenges. To quantify benefits and risks, we propose a counterfactual p-value (CP) approach. Our approach considers a spectrum of weights for weighting benefit-risk values and computes the extreme probabilities of observing the weighted benefit-risk value in one treatment group as if patients were treated in the other treatment group. The proposed approach is applicable to single benefit and single risk outcome as well as multiple benefit and risk outcomes assessment. In addition, the prior information in the weight schemes relevant to the importance of outcomes can be incorporated in the approach. The proposed CPs plot is intuitive with a visualized weight pattern. The average area under CP and preferred probability over time are used for overall treatment comparison and a bootstrap approach is applied for statistical inference. We assess the proposed approach using simulated data with multiple efficacy and safety endpoints and compare its performance with a stochastic multi-criteria acceptability analysis approach.

  5. Gasification : converting low value feedstocks to high value products

    International Nuclear Information System (INIS)

    Koppel, P.; Lorden, D.

    2009-01-01

    This presentation provided a historic overview of the gasification process and described the process chemistry of its two primary reactions, notably partial oxidation and steam reforming. The gasification process involves converting low value carbonaceous solid or liquid feeds to a synthetic gas by reacting the feed with oxygen and steam under high pressure and temperature conditions. Since the gasifier operates under a reducing environment instead of an oxidizing environment, mist sulphur is converted to hydrogen sulphide instead of sulphur dioxide. The gasification process also involves cleaning up synthetic gas and acid gas removal; recovery of conventional sulphur; and combustion or further processing of clean synthetic gas. This presentation also outlined secondary reactions such as methanation, water shift, and carbon formation. The negative effects of gasification were also discussed, with particular reference to syngas; metal carbonyls; soot; and slag. Other topics that were presented included world syngas production capacity by primary feedstock; operating IGCC projects; natural gas demand by oil sands supply and demand considerations; reasons for using the gasification process; gasifier feedstocks; and gasification products. The presentation concluded with a discussion of gasification licensors; gasification technologies; gasification experience; and the regulatory situation for greenhouse gas. Gasification has demonstrated excellent environmental performance with sulphur recovery greater than 99 per cent, depending on the the recovery process chosen. The opportunity also exists for carbon dioxide recovery. tabs., figs.

  6. Analysis of high-throughput biological data using their rank values.

    Science.gov (United States)

    Dembélé, Doulaye

    2018-01-01

    High-throughput biological technologies are routinely used to generate gene expression profiling or cytogenetics data. To achieve high performance, methods available in the literature become more specialized and often require high computational resources. Here, we propose a new versatile method based on the data-ordering rank values. We use linear algebra, the Perron-Frobenius theorem and also extend a method presented earlier for searching differentially expressed genes for the detection of recurrent copy number aberration. A result derived from the proposed method is a one-sample Student's t-test based on rank values. The proposed method is to our knowledge the only that applies to gene expression profiling and to cytogenetics data sets. This new method is fast, deterministic, and requires a low computational load. Probabilities are associated with genes to allow a statistically significant subset selection in the data set. Stability scores are also introduced as quality parameters. The performance and comparative analyses were carried out using real data sets. The proposed method can be accessed through an R package available from the CRAN (Comprehensive R Archive Network) website: https://cran.r-project.org/web/packages/fcros .

  7. Attitudes and value orientations of high school students in Serbia

    Directory of Open Access Journals (Sweden)

    Radoman Marija

    2012-01-01

    Full Text Available The analysis of attitudes and value orientations of high school students comes as the result of research based on data collected during April-June 2011 in six towns in Serbia. The main objective of this research was to detect the dominant attitudes and value orientations of high school students on a scale of traditionalism, homophobia, anti-Romism, ethnic stereotypes and attitudes toward abortion. The research was conducted in the following cities: Belgrade, Krusevac, Novi Sad, Zrenjanin, Nis and Novi Pazar. The results showed that high school students in Serbia in regards to their beliefs do not differ much from the general social climate in which they grew up and were educated in. Traditional respondents are represented at the level of 33.9%; 27.9% of them are moderately traditional and 25% of them are non-traditional. On the one side there are extremely radical position of high school students especially in relation to Roma and LGBT people. On the other side, certain number of respondents howed high affinity and positive individual interprets of the lifestyles of those groups (such as the rights of marriage for homosexual population. Attitudes towards women's rights are also bipolar - high school students have a patriarchal attitude towards marriage, family and abortion, but they show sensitivity to the issue of domestic violence. The obtained data should be interpreted in accordance with the changes in Serbian society - economic crisis, privatization, increase of violence in society and family, redefining of gender roles, etc.

  8. The Magnetic Bootstrap

    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.

  9. Computational Study of Anomalous Transport in High Beta DIII-D Discharges with ITBs

    Science.gov (United States)

    Pankin, Alexei; Garofalo, Andrea; Grierson, Brian; Kritz, Arnold; Rafiq, Tariq

    2015-11-01

    The advanced tokamak scenarios require a large bootstrap current fraction and high β. These large values are often outside the range that occurs in ``conventional'' tokamak discharges. The GLF23, TGLF, and MMM transport models have been previously validated for discharges with parameters associated with ``conventional'' tokamak discharges. It has been demonstrated that the TGLF model under-predicts anomalous transport in high β DIII-D discharges [A.M. Garofalo et al. 2015 TTF Workshop]. In this research, the validity of MMM7.1 model [T. Rafiq et al. Phys. Plasmas 20 032506 (2013)] is tested for high β DIII-D discharges with low and high torque. In addition, the sensitivity of the anomalous transport to β is examined. It is shown that the MMM7.1 model over-predicts the anomalous transport in the DIII-D discharge 154406. In particular, a significant level of anomalous transport is found just outside the internal transport barrier. Differences in the anomalous transport predicted using TGLF and MMM7.1 are reviewed. Mechanisms for quenching of anomalous transport in the ITB regions of high-beta discharges are investigated. This research is supported by US Department of Energy.

  10. Going beyond "highly-qualified personnel" to "value-added personnel"

    Science.gov (United States)

    Nantel, Marc; Fox, Bradley; Gelsthorpe, Leanne; Hamilton, Roxy; Marshall, Robert; Williamson, Guida

    2005-10-01

    Employers clamour for more "Highly-Qualified Personnel" (HQP) to hire, and photonics is no exception. The challenge facing all new graduates lies in what actually constitutes a Highly-Qualified Person. Yesterday, an HQP was often understood to be a graduate with a Bachelor's, Master's or Ph.D. degree. Today, industry is demanding that an HQP be either a university or college graduate with strong academic standing AND a sound business and communications skill set. In this paper, we introduce the concept of "Value-Added Personnel" (VAP), which marries both scientific and "soft-skills" aspects, and we present a new program in Ontario to produce VAPs.

  11. 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

  12. Economic policy uncertainty and housing returns in Germany: Evidence from a bootstrap rolling window

    Directory of Open Access Journals (Sweden)

    David Su

    2016-06-01

    Full Text Available The purpose of this investigation is to research the causal link between economic policy uncertainty (EPU and the housing returns (HR in Germany. In the estimated vector autoregressive models, we test its stability and find the short-run relationship between HR and EPU is unstable. As a result, a time-varying approach (bootstrap rolling window causality test is utilized to revisit the dynamic causal link, and we find EPU has no impact on HR due to the stability of the real estate market in Germany. HR does not have significant effects on EPU in most time periods. However, significant feedback in several sub-periods (both positive and negative are found from HR to EPU, which indicates the causal link from HR to EPU varies over time. The empirical results do not support the general equilibrium model of government policy choices that indicate EPU does not play a role in the real estate market. The basic conclusion is that the real estate market shows its stability due to the social welfare nature and the rational institutional arrangement of the real estate in Germany, and the real estate market also shows its importance that it has significant effect on the economic policy choice in some periods when negative external shocks occur.

  13. Quantitative determination of additive Chlorantraniliprole in Abamectin preparation: Investigation of bootstrapping soft shrinkage approach by mid-infrared spectroscopy

    Science.gov (United States)

    Yan, Hong; Song, Xiangzhong; Tian, Kuangda; Chen, Yilin; Xiong, Yanmei; Min, Shungeng

    2018-02-01

    A novel method, mid-infrared (MIR) spectroscopy, which enables the determination of Chlorantraniliprole in Abamectin within minutes, is proposed. We further evaluate the prediction ability of four wavelength selection methods, including bootstrapping soft shrinkage approach (BOSS), Monte Carlo uninformative variable elimination (MCUVE), genetic algorithm partial least squares (GA-PLS) and competitive adaptive reweighted sampling (CARS) respectively. The results showed that BOSS method obtained the lowest root mean squared error of cross validation (RMSECV) (0.0245) and root mean squared error of prediction (RMSEP) (0.0271), as well as the highest coefficient of determination of cross-validation (Qcv2) (0.9998) and the coefficient of determination of test set (Q2test) (0.9989), which demonstrated that the mid infrared spectroscopy can be used to detect Chlorantraniliprole in Abamectin conveniently. Meanwhile, a suitable wavelength selection method (BOSS) is essential to conducting a component spectral analysis.

  14. The efficiency of average linkage hierarchical clustering algorithm associated multi-scale bootstrap resampling in identifying homogeneous precipitation catchments

    Science.gov (United States)

    Chuan, Zun Liang; Ismail, Noriszura; Shinyie, Wendy Ling; Lit Ken, Tan; Fam, Soo-Fen; Senawi, Azlyna; Yusoff, Wan Nur Syahidah Wan

    2018-04-01

    Due to the limited of historical precipitation records, agglomerative hierarchical clustering algorithms widely used to extrapolate information from gauged to ungauged precipitation catchments in yielding a more reliable projection of extreme hydro-meteorological events such as extreme precipitation events. However, identifying the optimum number of homogeneous precipitation catchments accurately based on the dendrogram resulted using agglomerative hierarchical algorithms are very subjective. The main objective of this study is to propose an efficient regionalized algorithm to identify the homogeneous precipitation catchments for non-stationary precipitation time series. The homogeneous precipitation catchments are identified using average linkage hierarchical clustering algorithm associated multi-scale bootstrap resampling, while uncentered correlation coefficient as the similarity measure. The regionalized homogeneous precipitation is consolidated using K-sample Anderson Darling non-parametric test. The analysis result shows the proposed regionalized algorithm performed more better compared to the proposed agglomerative hierarchical clustering algorithm in previous studies.

  15. Wetting dynamics at high values of contact line speed

    OpenAIRE

    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...

  16. Demographic analysis, a comparison of the jackknife and bootstrap methods, and predation projection: a case study of Chrysopa pallens (Neuroptera: Chrysopidae).

    Science.gov (United States)

    Yu, Ling-Yuan; Chen, Zhen-Zhen; Zheng, Fang-Qiang; Shi, Ai-Ju; Guo, Ting-Ting; Yeh, Bao-Hua; Chi, Hsin; Xu, Yong-Yu

    2013-02-01

    The life table of the green lacewing, Chrysopa pallens (Rambur), was studied at 22 degrees C, a photoperiod of 15:9 (L:D) h, and 80% relative humidity in the laboratory. The raw data were analyzed using the age-stage, two-sex life table. The intrinsic rate of increase (r), the finite rate of increase (lambda), the net reproduction rate (R0), and the mean generation time (T) of Ch. pallens were 0.1258 d(-1), 1.1340 d(-1), 241.4 offspring and 43.6 d, respectively. For the estimation of the means, variances, and SEs of the population parameters, we compared the jackknife and bootstrap techniques. Although similar values of the means and SEs were obtained with both techniques, significant differences were observed in the frequency distribution and variances of all parameters. The jackknife technique will result in a zero net reproductive rate upon the omission of a male, an immature death, or a nonreproductive female. This result represents, however, a contradiction because an intrinsic rate of increase exists in this situation. Therefore, we suggest that the jackknife technique should not be used for the estimation of population parameters. In predator-prey interactions, the nonpredatory egg and pupal stages of the predator are time refuges for the prey, and the pest population can grow during these times. In this study, a population projection based on the age-stage, two-sex life table is used to determine the optimal interval between releases to fill the predation gaps and maintain the predatory capacity of the control agent.

  17. Stability Limits of High-Beta Plasmas in DIII-D

    International Nuclear Information System (INIS)

    Strait, E.J.

    2005-01-01

    Stability at high beta is an important requirement for a compact, economically attractive fusion reactor. DIII-D experiments have shown that ideal magnetohydrodynamic (MHD) theory is an accurate predictor of the ultimate stability limits for tokamaks, and the Troyon scaling law has provided a useful approximation of ideal stability limits for discharges with 'conventional' profiles. However, variation of the discharge shape, pressure profile, and current density profile can lead to ideal MHD beta limits that differ significantly from simple Troyon scaling. The need for profiles consistent with steady-state operation places an important additional constraint on plasma stability. Nonideal effects can also be important and must be taken into account. For example, neoclassical tearing modes (NTMs), resulting from plasma resistivity and the nonlinear effects of the bootstrap current, can become unstable at beta values well below the ideal MHD limit. DIII-D experiments are now entering a new era of unprecedented control over plasma stability, including suppression of NTMs by localized current drive at the island location, and direct feedback stabilization of kink modes with a resistive wall. The continuing development of physics understanding and control tools holds the potential for stable, steady-state fusion plasmas at high beta

  18. Oscillometric blood pressure estimation by combining nonparametric bootstrap with Gaussian mixture model.

    Science.gov (United States)

    Lee, Soojeong; Rajan, Sreeraman; Jeon, Gwanggil; Chang, Joon-Hyuk; Dajani, Hilmi R; Groza, Voicu Z

    2017-06-01

    Blood pressure (BP) is one of the most important vital indicators and plays a key role in determining the cardiovascular activity of patients. This paper proposes a hybrid approach consisting of nonparametric bootstrap (NPB) and machine learning techniques to obtain the characteristic ratios (CR) used in the blood pressure estimation algorithm to improve the accuracy of systolic blood pressure (SBP) and diastolic blood pressure (DBP) estimates and obtain confidence intervals (CI). The NPB technique is used to circumvent the requirement for large sample set for obtaining the CI. A mixture of Gaussian densities is assumed for the CRs and Gaussian mixture model (GMM) is chosen to estimate the SBP and DBP ratios. The K-means clustering technique is used to obtain the mixture order of the Gaussian densities. The proposed approach achieves grade "A" under British Society of Hypertension testing protocol and is superior to the conventional approach based on maximum amplitude algorithm (MAA) that uses fixed CR ratios. The proposed approach also yields a lower mean error (ME) and the standard deviation of the error (SDE) in the estimates when compared to the conventional MAA method. In addition, CIs obtained through the proposed hybrid approach are also narrower with a lower SDE. The proposed approach combining the NPB technique with the GMM provides a methodology to derive individualized characteristic ratio. The results exhibit that the proposed approach enhances the accuracy of SBP and DBP estimation and provides narrower confidence intervals for the estimates. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. Is there a difference between the energy and CO_2 emission performance for China’s thermal power industry? A bootstrapped directional distance function approach

    International Nuclear Information System (INIS)

    Duan, Na; Guo, Jun-Peng; Xie, Bai-Chen

    2016-01-01

    Highlights: • Evaluate the energy and CO_2 emission performance of China’s thermal power industry. • Perform statistical inferences for the estimates of efficiency and productivity indexes. • There exist differences between the energy and CO_2 emission performance. • Technological progress is the main driving force for productivity improvement. - Abstract: A scientific evaluation of the energy efficiency and CO_2 emission performance of the thermal power industry could not only provide valuable information for reducing energy consumption and carbon emissions but also serve as a tool to estimate the effectiveness of relevant policy reforms. Considering the opposite effects of energy conservation and carbon emission reduction on generation cost, this study respectively measures the energy and CO_2 emission performance of the thermal power industries in China’s 30 provincial administrative regions during the period 2005–2012 from both static and dynamic perspectives. We implement the bootstrap method for the directional distance function to correct the possible estimate bias and test the significance of productivity changes where the weak disposability of undesirable outputs is also integrated. The empirical analysis leads to the following conclusions. The bootstrapping results could provide us with much valuable information because the initial estimates might result from sampling noise rather than reveal the real variations. In addition, some differences do exist between the energy and CO_2 emission performance of China’s thermal power industry. Furthermore, technological progress is the main driving force for energy and CO_2 emission productivity improvement and it works better for the former.

  20. Simulation-based hypothesis testing of high dimensional means under covariance heterogeneity.

    Science.gov (United States)

    Chang, Jinyuan; Zheng, Chao; Zhou, Wen-Xin; Zhou, Wen

    2017-12-01

    In this article, we study the problem of testing the mean vectors of high dimensional data in both one-sample and two-sample cases. The proposed testing procedures employ maximum-type statistics and the parametric bootstrap techniques to compute the critical values. Different from the existing tests that heavily rely on the structural conditions on the unknown covariance matrices, the proposed tests allow general covariance structures of the data and therefore enjoy wide scope of applicability in practice. To enhance powers of the tests against sparse alternatives, we further propose two-step procedures with a preliminary feature screening step. Theoretical properties of the proposed tests are investigated. Through extensive numerical experiments on synthetic data sets and an human acute lymphoblastic leukemia gene expression data set, we illustrate the performance of the new tests and how they may provide assistance on detecting disease-associated gene-sets. The proposed methods have been implemented in an R-package HDtest and are available on CRAN. © 2017, The International Biometric Society.

  1. Hemoglobin and hematocrit values of Saudi newborns in the high altitude of Abha, Saudi Arabia

    International Nuclear Information System (INIS)

    Bassuni, W.; Asindi, A.A.; Mustafa, F.S.; Hassan, B.; Din, Z.S.; Kumar, R.K.

    1996-01-01

    A study was designed to determine the red cell values (hemoglobin and hematocrit) of neonates born in the high altitude of Abha and to compare these values with known values of other lowland areas of Saudi Arabia. From the cord blood of 587 normal, appropriate for gestational age and term infants born in 1993 in Abha Maternity Hospital, the ranges of Hb and Hct were 130 to 240 g/L and 0.24 to 0.79 L/L respectively. The mean Hb was 187 g/L. There was no significant difference between the male and female values. Also, 17% of the infants in this study were polycythemic, while no polycythemia was recorded in these lowland areas and only 2% to 4% in the general global newborn population. It was therefore revealed that Abha newborns had higher red cell values at the birth when compared to other newborns in the low altitude areas of Riyadh and Jeddah (P<0.001). We postulate that high altitude (2700 meters above sea level) of Abha, and therefore its relative hypoxia, has induced high red cell values in infants born in the city. The phenomenon therefore warrants the adoption of higher red cell reference values and not necessarily those already documented in other Saudi new born populations. (author)

  2. Tablet potency of Tianeptine in coated tablets by near infrared spectroscopy: model optimisation, calibration transfer and confidence intervals.

    Science.gov (United States)

    Boiret, Mathieu; Meunier, Loïc; Ginot, Yves-Michel

    2011-02-20

    A near infrared (NIR) method was developed for determination of tablet potency of active pharmaceutical ingredient (API) in a complex coated tablet matrix. The calibration set contained samples from laboratory and production scale batches. The reference values were obtained by high performance liquid chromatography (HPLC) and partial least squares (PLS) regression was used to establish a model. The model was challenged by calculating tablet potency of two external test sets. Root mean square errors of prediction were respectively equal to 2.0% and 2.7%. To use this model with a second spectrometer from the production field, a calibration transfer method called piecewise direct standardisation (PDS) was used. After the transfer, the root mean square error of prediction of the first test set was 2.4% compared to 4.0% without transferring the spectra. A statistical technique using bootstrap of PLS residuals was used to estimate confidence intervals of tablet potency calculations. This method requires an optimised PLS model, selection of the bootstrap number and determination of the risk. In the case of a chemical analysis, the tablet potency value will be included within the confidence interval calculated by the bootstrap method. An easy to use graphical interface was developed to easily determine if the predictions, surrounded by minimum and maximum values, are within the specifications defined by the regulatory organisation. Copyright © 2010 Elsevier B.V. All rights reserved.

  3. Topics on MHD equilibrium and stability in heliotron / torsatron

    International Nuclear Information System (INIS)

    Ichiguchi, Katsuji; Nakajima, Noriyoshi; Okamoto, Masao.

    1996-10-01

    Recent topics on the MHD properties with and without bootstrap current in Heliotron / Torsatron configurations are presented. In a currentless equilibrium with a large Shafranov shift, a high-n ballooning mode can be unstable even in the region with positive gradient of the rotational transform. This is because the local shear in the field line bending term can be reduced by the fact that the local enhancement of the poloidal field varies in the radial direction. Since the local curvature of the field lines depends on the label of the magnetic field line, α, in Heliotron / Torsatron, the eigenvalue ω 2 also depends on α. In the Mercier stable region, the level surfaces of ω 2 of unstable modes form spheroids in the (ψ, θ k , α) space, where ψ and θ k are the label of the flux surface and the radial wave number, while they form cylinders in tokamaks. Such high-n modes cannot be related to low-n modes in this case. In the LHD configuration, bootstrap current depends on the collisionality of the plasma. When the beta value is raised by increasing the temperature with the density fixed, the plasma becomes less collisional and the bootstrap current grows in the direction where the rotational transform is increased. On the contrary, when the beta value is raised by increasing the density with the temperature fixed, the plasma becomes more collisional. While a small amount of the current flows in the same direction as in the above sequence at low beta in this case, the direction of the current reverses at high beta equilibrium. This is because the geometrical factor in the expression of the bootstrap current in the plateau regime has opposite signature to that in the 1/ν regime. The latter equilibrium sequence is more stable in the Mercier criterion than the former one. Thus, the beta should be raised by increasing the density rather than the temperature to obtain stable high beta plasma. (author)

  4. Protecting high value assets in transit

    International Nuclear Information System (INIS)

    Tennefoss, M.

    1991-01-01

    This paper reports that one of the most daunting tasks facing a security manager is how to protect classified or high value assets such as nuclear materials in transit, especially when the shipment is to be handled by a commercial carrier. There are many opportunities for an adversary to gain access to cargo shipments en route, including situations in which the cargo must be held in storage for weeks or even months. Standard commercial alarm systems are not suitable for use in containers subject to vibration or high and low temperature extremes, or situations in which national assets might be used to gain surreptitious access to the container and to defeat the alarm system. A new alarm monitoring system has been developed to provide a secure auditing system for use in rail cars, Conex containers, and other transportable containers. The system, referred to as the PEL-100, electronically supervises intrusion detection sensors mounted on or within a container, and records all intrusion attempts in a secure, solid state memory storage device. The security archive can be withdrawn and reviewed after the container has completed its travels, and will provide a complete audit trail of intrusion attempts in transit. The PEL-100 includes one of the most comprehensive security tamper systems ever fielded, and is intended to operate reliably and securely in an environment subject to vibration, EMI/RFI emissions, electronic spoofing, and physical manipulation. The unit provides a clear and unambiguous indication of tampering and includes a comprehensive internal security system to detect insider tampering

  5. High CRP values predict poor survival in patients with penile cancer

    International Nuclear Information System (INIS)

    Steffens, Sandra; Kuczyk, Markus A; Schrader, Andres J; Al Ghazal, Andreas; Steinestel, Julie; Lehmann, Rieke; Wegener, Gerd; Schnoeller, Thomas J; Cronauer, Marcus V; Jentzmik, Florian; Schrader, Mark

    2013-01-01

    High levels of circulating C-reactive protein (CRP) have recently been linked to poor clinical outcome in various malignancies. The aim of this study was to evaluate the prognostic significance of the preoperative serum CRP level in patients with squamous cell carcinoma (SCC) of the penis. This retrospective analysis included 79 penile cancer patients with information about their serum CRP value prior to surgery who underwent either radical or partial penectomy at two German high-volume centers (Ulm University Medical Center and Hannover Medical School) between 1990 and 2010. They had a median (mean) follow-up of 23 (32) months. A significantly elevated CRP level (>15 vs. ≤ 15 mg/l) was found more often in patients with an advanced tumor stage (≥pT2) (38.9 vs. 11.6%, p=0.007) and in those with nodal disease at diagnosis (50.0 vs. 14.6%, p=0.007). However, high CRP levels were not associated with tumor differentiation (p=0.53). The Kaplan-Meier 5-year cancer-specific survival (CSS) rate was 38.9% for patients with preoperative CRP levels above 15 mg/l and 84.3% for those with lower levels (p=0.001). Applying multivariate analysis and focusing on the subgroup of patients without metastasis at the time of penile surgery, both advanced local tumor stage (≥pT2; HR 8.8, p=0.041) and an elevated CRP value (>15 mg/l; HR 3.3, p=0.043) were identified as independent predictors of poor clinical outcome in patients with penile cancer. A high preoperative serum CRP level was associated with poor survival in patients with penile cancer. If larger patient populations confirm its prognostic value, its routine use could enable better risk stratification and risk-adjusted follow-up of patients with SCC of the penis

  6. The value of multi ultra high-b-value DWI in grading cerebral astrocytomas and its association with aquaporin-4.

    Science.gov (United States)

    Tan, Yan; Zhang, Hui; Wang, Xiao-Chun; Qin, Jiang-Bo; Wang, Le

    2018-06-01

    To investigate the value of multi-ultrahigh-b-value diffusion-weighted imaging (UHBV-DWI) in differentiating high-grade astrocytomas (HGAs) from low-grade astrocytomas (LGAs), analyze its association with aquaporin (AQP) expression. 40 astrocytomas divided into LGAs (N = 15) and HGAs (N = 25) were studied. Apparent diffusion coefficient (ADC) and UHBV-ADC values in solid parts and peritumoral edema were compared between LGAs and HGAs groups by the t-test. Using receiver operating characteristic curves to identify the better parameter. Using real time polymerase chain reaction to assess AQP messenger ribonucleic acid (mRNA). Using spearman correlation analysis to assess the correlation of AQP mRNA with each parameter. ADC values in solid parts of HGAs were significantly lower than LGAs (p = 0.02), while UHBV-ADC values of HGAs were significantly higher than LGAs (p  0.05); ADC value showed a negative correlation with AQP4 mRNA (r = -0.357; p = 0.024). UHBV-ADC value positively correlated with the AQP4 mRNA (r = 0.646; p value may be related with the AQP4 mRNA levels. UHBV-DWI could be of value in the assessment of astrocytoma. Advances in knowledge: UHBV-DWI generated by multi UHBV could have particular value for astrocytoma grading, and the level of AQP4 mRNA might be potentially linked to the change of UHBV-DWI parameter, and we might find the exact reason for the difference of UHBV-ADC between the LGAs and HGAs.

  7. Meeting the milestones. Strategies for including high-value care education in pulmonary and critical care fellowship training.

    Science.gov (United States)

    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.

  8. Valuing carbon assets for high-tech with application to the wind energy industry

    International Nuclear Information System (INIS)

    Han, Liyan; Liu, Yang; Lin, Qiang; Huang, Gubo

    2015-01-01

    In contrast to the traditional methods for high-tech evaluation, we introduce a new, more active idea for considering the carbon asset effect, in addition to the economic and technological considerations for strategic significance. The method proposed in this paper considers a reduced amount of carbon emissions, less than that of the current industry baseline, to be an asset that is beneficial to a firm that adopts a new technology. The measured carbon asset values vary across different technologies, in different industries and over time. The new method is applied to the valuing of wind energy technology and uses the Weibull distribution to estimate the wind energy capacity and a concrete sensitivity analysis. These applications support the validity of the new method and show that the impact of the fluctuations of carbon sinks on the values of carbon assets is significantly greater than that of volatility in the production output. The paper also presents some policy recommendations based on the results. - Highlights: • Carbon asset dimension for high-tech evaluation. • Valuing wind energy technology by Weibull distribution. • Greater impact of the carbon sink price on the carbon asset value than that of production output. • The environmental risk could be measured based on the carbon asset assessment.

  9. Scanning the horizon for high value-add manufacturing science: Accelerating manufacturing readiness for the next generation of disruptive, high-value curative cell therapeutics.

    Science.gov (United States)

    Hourd, Paul; Williams, David J

    2018-05-01

    Since the regenerative medicine sector entered the second phase of its development (RegenMed 2.0) more than a decade ago, there is increasing recognition that current technology innovation trajectories will drive the next translational phase toward the production of disruptive, high-value curative cell and gene-based regenerative medicines. To identify the manufacturing science problems that must be addressed to permit translation of these next generation therapeutics. In this short report, a long lens look within the pluripotent stem cell therapeutic space, both embryonic and induced, is used to gain early insights on where critical technology and manufacturing challenges may emerge. This report offers a future perspective on the development and innovation that will be needed within manufacturing science to add value in the production and commercialization of the next generation of advanced cell therapies and precision medicines. Copyright © 2018 International Society for Cellular Therapy. Published by Elsevier Inc. All rights reserved.

  10. High value of ecological information for river connectivity restoration

    Science.gov (United States)

    Sethi, Suresh; O'Hanley, Jesse R.; Gerken, Jonathon; Ashline, Joshua; Bradley, Catherine

    2017-01-01

    ContextEfficient restoration of longitudinal river connectivity relies on barrier mitigation prioritization tools that incorporate stream network spatial structure to maximize ecological benefits given limited resources. Typically, ecological benefits of barrier mitigation are measured using proxies such as the amount of accessible riverine habitat.ObjectivesWe developed an optimization approach for barrier mitigation planning which directly incorporates the ecology of managed taxa, and applied it to an urbanizing salmon-bearing watershed in Alaska.MethodsA novel river connectivity metric that exploits information on the distribution and movement of managed taxon was embedded into a barrier prioritization framework to identify optimal mitigation actions given limited restoration budgets. The value of ecological information on managed taxa was estimated by comparing costs to achieve restoration targets across alternative barrier prioritization approaches.ResultsBarrier mitigation solutions informed by life history information outperformed those using only river connectivity proxies, demonstrating high value of ecological information for watershed restoration. In our study area, information on salmon ecology was typically valued at 0.8–1.2 M USD in costs savings to achieve a given benefit level relative to solutions derived only from stream network information, equating to 16–28% of the restoration budget.ConclusionsInvesting in ecological studies may achieve win–win outcomes of improved understanding of aquatic ecology and greater watershed restoration efficiency.

  11. The value of diffusion weighted imaging in differentiating intracranial tuberculomas from high-grade astrocytomas and metastases

    International Nuclear Information System (INIS)

    Peng Juan; Luo Tianyou; Lv Fajin; Fang Weidong; Wu Jingquan; Ouyang Yu; Li Yongmei

    2007-01-01

    Objective: To explore the value of diffusion weighted imaging (DWI) in differentiating intracranial tuberculomas from high-grade astrocytomas and metastases. Methods: The conventional MR imaging and DWI were performed in 50 eases (14 cases with intracranial tuberculomas, 15 cases with high- grade astrocytomas, and 21 cases with metastases) before treatment or operation. The mean apparent diffusion coefficient (ADC) values and relative apparent diffusion coefficient (rADC) values were calculated from the mass as well as from the peripheral edema regions of intracranial lesions. Results: The mean ADC values and rADC values were (1.2±0.2) x 10 -3 mm 2 ·s -1 and 1.6±0.3 in the mass of intracranial tuberculomas respectively; (0.8±0.1) x 10 -3 mm 2 ·s -1 and 1.1±0.1 in the parenehyma of high-grade astrocytomas; (0.8±0.1) x 10 -3 mm 2 ·s -1 and 1.0±0.2 in the parenchyma of metastases. There was significant difference of the mean ADC values (F=33.57, P -3 mm 2 ·s -1 and 2.5±0.2 in the peripheral edema regions of intracranial tuberculomas respectively; (1.4±0.2) x 10 -3 mm 2 ·s -1 and 1.8±0.3 in the peripheral edema regions of high-grade astrocytomas; and (1.9±0.2) x 10 -3 mm 2 ·s -1 and 2.3±0.5 in the peripheral edema regions of metastases. There was also significant difference in the mean ADC values (F23.17, P<0.01) or rADC values (F=5.94, P<0.01) among the peripheral edema regions of the three groups. Conclusion: The ADC values and rADC values are quite effective in differentiating intracranial tuberculoma from high-grade astrocytoma and metastasis. (authors)

  12. 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.

  13. Economic Evaluations for the Carbon Dioxide-involved Production of High-value Chemicals

    International Nuclear Information System (INIS)

    Lee, Ji Hyun; Lee, Dong Woog; Jang, Se Gyu; Kwak, No-Sang; Lee, In Young; Jang, Kyung Ryoung; Shim, Jae-Goo; Choi, Jong Shin

    2014-01-01

    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

  14. Causal nexus between energy consumption and carbon dioxide emission for Malaysia using maximum entropy bootstrap approach.

    Science.gov (United States)

    Gul, Sehrish; Zou, Xiang; Hassan, Che Hashim; Azam, Muhammad; Zaman, Khalid

    2015-12-01

    This study investigates the relationship between energy consumption and carbon dioxide emission in the causal framework, as the direction of causality remains has a significant policy implication for developed and developing countries. The study employed maximum entropy bootstrap (Meboot) approach to examine the causal nexus between energy consumption and carbon dioxide emission using bivariate as well as multivariate framework for Malaysia, over a period of 1975-2013. This is a unified approach without requiring the use of conventional techniques based on asymptotical theory such as testing for possible unit root and cointegration. In addition, it can be applied in the presence of non-stationary of any type including structural breaks without any type of data transformation to achieve stationary. Thus, it provides more reliable and robust inferences which are insensitive to time span as well as lag length used. The empirical results show that there is a unidirectional causality running from energy consumption to carbon emission both in the bivariate model and multivariate framework, while controlling for broad money supply and population density. The results indicate that Malaysia is an energy-dependent country and hence energy is stimulus to carbon emissions.

  15. Projeção do Custo do Suco de Laranja Pela Aplicação da Simulação Bootstrap

    Directory of Open Access Journals (Sweden)

    Joaquim Eduardo de Moura Nicacio

    2014-11-01

    Full Text Available Essa pesquisa teve por objetivo a utilização da técnica Bootstrap na determinação do volume médio populacional de suco de laranja, obtida entre quatro amostras provenientes de produtores dessa fruta denominada Citrus sinensis (L Osbeck, do município de Primavera do Leste.  A cadeia de produção agroindustrial da laranja, ainda incipiente nesse município, deve ser monitorada em suas operações principalmente a industrialização e, a qualidade da matéria prima deve ser rigorosamente controlada. A determinação do custo de produção do suco de laranja é exigida pelo Regulamento do Imposto de Renda/1999 que impõe o sistema de custeio por absorção definido pela equação Custo Total = Custo Direto + Custo Indireto.  O volume médio simulado do suco de laranja foi obtido após 1000 reamostragens com reposição das amostras dos produtores. Dessa forma obteve-se a equação: valor = preço unitário da laranja x volume médio simulado, obtendo dessa forma o custo direto do suco proveniente da melhor amostra. O emprego da Pesquisa Operacional, através da simulação numérica Bootstrap permitiu um resultado positivo na mensuração do volume médio de suco de laranja de forma segura e confiável. Para a pequena agroindústria esse é um critério de controle de qualidade da matéria prima imprescindível para sua sustentabilidade. Para o produtor é a garantia de uma demanda firme. A incerteza de obter um lote de laranjas com menor quantidade de suco é eliminada nessa simulação. A obtenção antecipada do custo variável do suco é estratégica do ponto de vista do planejamento da produção.

  16. High-Value Care in the Evaluation of Stroke.

    Science.gov (United States)

    Urja, Prakrity; Nippoldt, Eric H; Barak, Virginia; Valenta, Carrie

    2017-08-01

    ) evaluation.  Appropriate medical treatment with antiplatelets, as indicated by the acute stroke guidelines, was started. The patient was not eligible for thrombolysis. Value-based care emphasizes the decreased usage in investigations or health care of options that do not contribute to the overall health and well-being of the patient. Given our patient's past medical history and the results of previous investigations, we questioned the value of ordering a hypercoagulable evaluation and TEE in our patient. The need for an evaluation of the hypercoagulable state in an elderly patient with ischemic stroke or TIA remains unknown. Our patient had a complete hypercoagulable evaluation done six years earlier. Repeating the hypercoagulable evaluation would not contribute to the treatment decisions and, as a result, would not satisfy the basic criteria for value-based care.The importance of a repeat TEE is uncertain in the evaluation of embolism for a known cause of stroke. Additionally, no change in management was anticipated regardless of the TEE findings, therefore, repeating TEE in our patient was an inappropriate use of resources. Being mindful of value-based care can reduce overall health care costs, maintain our role of being responsible stewards of our limited resources, and continue to provide high-value care for our patients.

  17. Methodical approaches to value assessment and determination of the capitalization level of high-rise construction

    Science.gov (United States)

    Smirnov, Vitaly; Dashkov, Leonid; Gorshkov, Roman; Burova, Olga; Romanova, Alina

    2018-03-01

    The article presents the analysis of the methodological approaches to cost estimation and determination of the capitalization level of high-rise construction objects. Factors determining the value of real estate were considered, three main approaches for estimating the value of real estate objects are given. The main methods of capitalization estimation were analyzed, the most reasonable method for determining the level of capitalization of high-rise buildings was proposed. In order to increase the value of real estate objects, the author proposes measures that enable to increase significantly the capitalization of the enterprise through more efficient use of intangible assets and goodwill.

  18. The Attitudes of Israeli Arab and Jewish High School Students towards Extrinsic and Intrinsic Values

    Science.gov (United States)

    Gross, Zehavit

    2013-01-01

    The aim of this research was to investigate the attitudes of Israeli Arab (n = 259) and Jewish (n = 259) high school students toward extrinsic and intrinsic values. A questionnaire, which consisted of eight value scales in two groups--extrinsic and intrinsic values--was administered. Participants were asked to state whether they agreed or…

  19. Assessment of ECISS draft standard for derivation of high temperature proof strength values

    Energy Technology Data Exchange (ETDEWEB)

    Linde, L.; Sandstroem, R.

    1996-03-01

    New European material standards are under development and modern data evaluation techniques must be able to supply these standards with accurate design values. A draft standard for the derivation of high temperature proof strength values has been proposed. This standard (EDS) has been used to calculate strength values for six steels; one unalloyed steel, one 12 % Cr steel and four austenitic stainless steels. Although large data sets were available, it was not possible to satisfy the requirement in the EDS of 80 % temperature coverage in the proof strength data for several steels. It suggests that temperature coverage specified in the EDS is unrealistically high. Due to the limited number of heats satisfying the temperature coverage requirements for each steel, the statistical error in the derived values exceeds 10-20 % which must be considered as unacceptably high. Instead it is recommended that the full data sets are used irrespective of temperature coverage. The variation of proof strength values represented by the analysed heats did not cover the corresponding variation in the larger data set available. This was the case even for the steel where 16 heats satisfied the temperature coverage requirement. Thus a limited number of heats can not be expected to be a good representation of more complete data sets. This has the consequence that absolute strength values can not be derived without access to a standardised proof strength at room temperature. Two derivation methods investigated in this report are both based on the ISO 2605/III procedure for proof strength assessments at elevated temperature. Method I and II use an essentially temperature independent and temperature dependent reduction term respectively. The methods have been assessed by the same data sets for the six steels. One or both methods gave satisfactory results for most of the investigated steels. Presented results are based on work carried out in ECISS TC22 WG1. 17 refs, 20 figs, 7 tabs.

  20. Neoclassical current studies in high beta plasmas. Technical progress report, October 1, 1982-September 31, 1983

    International Nuclear Information System (INIS)

    1983-01-01

    During the 12-month period, October 1, 1982 to September 30, 1983 the Levitated Octupole has been dedicated to a study of neoclassical currents. At beta values of a few percent, both the Pfirsch-Schlueter current and the bootstrap current have been observed and compared with theoretical predictions. The spatial variation of the current both radially and poloidally are found to agree with the prediction over a wide range of collisionality. A four megawatt ICRH capability exists for sustaining the current in steady state

  1. Value of CT to predict surgically important bowel and/or mesenteric injury in blunt trauma: performance of a preliminary scoring system

    Energy Technology Data Exchange (ETDEWEB)

    Faget, Claire; Taourel, Patrice; Ruyer, Alban; Alili, Chakib; Millet, Ingrid [CHU Lapeyronie, Department of Medical Imaging, Montpellier (France); Charbit, Jonathan [CHU Lapeyronie, Department of Intensive Care and Anesthesiology, Montpellier (France); Molinari, Nicolas [UMR 729 MISTEA, CHU Montpellier, Department of Medical Information and Statistics, Montpellier (France)

    2015-12-15

    To evaluate the performance of a computed tomography (CT) diagnostic score to predict surgical treatment for blunt bowel and/or mesentery injury (BBMI) in consecutive abdominal trauma. This was a retrospective observational study of 805 consecutive abdominal traumas with 556 patients included and screened by an abdominal radiologist blinded to the patient outcome, to evaluate numerous CT findings and calculate their diagnostic performances. These CT findings were compared using univariate and multivariate analysis between patients who had a laparotomy-confirmed BBMI requiring surgical repair, and those without BBMI requiring surgery. A CT score was obtained with an internal bootstrap validation. Fifty-six patients (10.1 %) had BBMI requiring surgery. Nine CT signs were independently associated with BBMI requiring surgery and were used to develop a CT diagnostic score. The AUC of our model was 0.98 (95 % CI 0.96-100), with a ≥5 cut-off. Its diagnostic performance was determined by internal validation: sensitivity 91.1-100 %, specificity 85.7-97.6 %, positive predictive value 41.4-82.3 % and negative predictive value 98.9-100 %. Bowel wall discontinuity and mesenteric pneumoperitoneum had the strongest association with BBMI requiring surgery (OR = 128.9 and 140.5, respectively). We developed a reliable CT scoring system which is easy to implement and highly predictive of BBMI requiring surgery. (orig.)

  2. Characterisation of transition state structures for protein folding using 'high', 'medium' and 'low' {Phi}-values.

    Science.gov (United States)

    Geierhaas, Christian D; Salvatella, Xavier; Clarke, Jane; Vendruscolo, Michele

    2008-03-01

    It has been suggested that Phi-values, which allow structural information about transition states (TSs) for protein folding to be obtained, are most reliably interpreted when divided into three classes (high, medium and low). High Phi-values indicate almost completely folded regions in the TS, intermediate Phi-values regions with a detectable amount of structure and low Phi-values indicate mostly unstructured regions. To explore the extent to which this classification can be used to characterise in detail the structure of TSs for protein folding, we used Phi-values divided into these classes as restraints in molecular dynamics simulations. This type of procedure is related to that used in NMR spectroscopy to define the structure of native proteins from the measurement of inter-proton distances derived from nuclear Overhauser effects. We illustrate this approach by determining the TS ensembles of five proteins and by showing that the results are similar to those obtained by using as restraints the actual numerical Phi-values measured experimentally. Our results indicate that the simultaneous consideration of a set of low-resolution Phi-values can provide sufficient information for characterising the architecture of a TS for folding of a protein.

  3. Stability of response characteristics of a Delphi panel: application of bootstrap data expansion

    Directory of Open Access Journals (Sweden)

    Cole Bryan R

    2005-12-01

    Full Text Available Abstract Background Delphi surveys with panels of experts in a particular area of interest have been widely utilized in the fields of clinical medicine, nursing practice, medical education and healthcare services. Despite this wide applicability of the Delphi methodology, there is no clear identification of what constitutes a sufficient number of Delphi survey participants to ensure stability of results. Methods The study analyzed the response characteristics from the first round of a Delphi survey conducted with 23 experts in healthcare quality and patient safety. The panel members had similar training and subject matter understanding of the Malcolm Baldrige Criteria for Performance Excellence in Healthcare. The raw data from the first round sampling, which usually contains the largest diversity of responses, were augmented via bootstrap sampling to obtain computer-generated results for two larger samples obtained by sampling with replacement. Response characteristics (mean, trimmed mean, standard deviation and 95% confidence intervals for 54 survey items were compared for the responses of the 23 actual study participants and two computer-generated samples of 1000 and 2000 resampling iterations. Results The results from this study indicate that the response characteristics of a small expert panel in a well-defined knowledge area are stable in light of augmented sampling. Conclusion Panels of similarly trained experts (who possess a general understanding in the field of interest provide effective and reliable utilization of a small sample from a limited number of experts in a field of study to develop reliable criteria that inform judgment and support effective decision-making.

  4. Frequency Analysis Using Bootstrap Method and SIR Algorithm for Prevention of Natural Disasters

    Science.gov (United States)

    Kim, T.; Kim, Y. S.

    2017-12-01

    The frequency analysis of hydrometeorological data is one of the most important factors in response to natural disaster damage, and design standards for a disaster prevention facilities. In case of frequency analysis of hydrometeorological data, it assumes that observation data have statistical stationarity, and a parametric method considering the parameter of probability distribution is applied. For a parametric method, it is necessary to sufficiently collect reliable data; however, snowfall observations are needed to compensate for insufficient data in Korea, because of reducing the number of days for snowfall observations and mean maximum daily snowfall depth due to climate change. In this study, we conducted the frequency analysis for snowfall using the Bootstrap method and SIR algorithm which are the resampling methods that can overcome the problems of insufficient data. For the 58 meteorological stations distributed evenly in Korea, the probability of snowfall depth was estimated by non-parametric frequency analysis using the maximum daily snowfall depth data. The results show that probabilistic daily snowfall depth by frequency analysis is decreased at most stations, and most stations representing the rate of change were found to be consistent in both parametric and non-parametric frequency analysis. This study shows that the resampling methods can do the frequency analysis of the snowfall depth that has insufficient observed samples, which can be applied to interpretation of other natural disasters such as summer typhoons with seasonal characteristics. Acknowledgment.This research was supported by a grant(MPSS-NH-2015-79) from Disaster Prediction and Mitigation Technology Development Program funded by Korean Ministry of Public Safety and Security(MPSS).

  5. Neutrophil CD64 has a high negative predictive value for exclusion ...

    African Journals Online (AJOL)

    Methods and results. In this prospective observational study, patients were classied into categories of infection, namely denite, probable and possible. Of 76 neonates, 1 had denite infection, 5 probable infection, 30 possible infection, and 32 no infection. .e neutrophil CD64 index at a cut-o. value of 1.8 had a high negative ...

  6. Apparent diffusion coefficient maps obtained from high b value diffusion-weighted imaging in the preoperative evaluation of gliomas at 3T: comparison with standard b value diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Zeng, Qiang; Ling, Chenhan; Zhang, Jianmin [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Neurosurgery, Hangzhou, Zhejiang (China); Dong, Fei; Jiang, Biao [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Radiology, Hangzhou, Zhejiang (China); Shi, Feina [Second Affiliated Hospital of Zhejiang University School of Medicine, Department of Neurology, Hangzhou, Zhejiang (China)

    2017-12-15

    To assess whether ADC maps obtained from high b value DWI were more valuable in preoperatively evaluating the grade, Ki-67 index and outcome of gliomas. Sixty-three patients with gliomas, who underwent preoperative multi b value DWI at 3 T, were enrolled. The ADC{sub 1000}, ADC{sub 2000} and ADC{sub 3000} maps were generated. Receiver operating characteristic analyses were conducted to determine the area under the curve (AUC) in differentiating high-grade gliomas (HGG) from low-grade gliomas (LGG). Pearson correlation coefficients (R value) were calculated to investigate the correlation between parameters with the Ki-67 proliferation index. Survival analysis was conducted by using Cox regression. The AUC of the mean ADC{sub 1000} value (0.820) was lower than that of the mean ADC{sub 2000} value (0.847) and mean ADC{sub 3000} value (0.875) in differentiating HGG from LGG. The R value of the mean ADC{sub 1000} value (-0.499) was less negative than that of the mean ADC{sub 2000} value (-0.530) and mean ADC{sub 3000} value (-0.567). The mean ADC{sub 3000} value was an independent prognosis factor for gliomas (p = 0.008), while the mean ADC{sub 1000} and ADC{sub 2000} values were not. ADC maps obtained from high b value DWI might be a better imaging biomarker in the preoperative evaluation of gliomas. (orig.)

  7. The determinants of technical efficiency of a large scale HIV prevention project: application of the DEA double bootstrap using panel data from the Indian Avahan.

    Science.gov (United States)

    Lépine, Aurélia; Vassall, Anna; Chandrashekar, Sudhashree

    2015-01-01

    In 2004, the largest HIV prevention project (Avahan) conducted globally was implemented in India. Avahan was implemented by NGOs supported by state lead partners in order to provide HIV prevention services to high-risk population groups. In 2007, most of the NGOs reached full coverage. Using a panel data set of the NGOs that implemented Avahan, we investigate the level of technical efficiency as well as the drivers of technical inefficiency by using the double bootstrap procedure developed by Simar & Wilson (2007). Unlike the two-stage traditional method, this method allows valid inference in the presence of measurement error and serial correlation. We find that over the 4 years, Avahan NGOs could have reduced the level of inputs by 43% given the level of outputs reached. We find that efficiency of the project has increased over time. Results indicate that main drivers of inefficiency come from the characteristics of the state lead partner, the NGOs and the catchment area. These organisational factors are important to explicitly consider and assess when designing and implementing HIV prevention programmes and in setting benchmarks in order to optimise the use and allocation of resources. C14, I1.

  8. Desserts with a high nutritional value in the industry employees nutrition

    Directory of Open Access Journals (Sweden)

    L. Telegenko

    2017-04-01

    Full Text Available In the article there are considered questions of the sweet foods with a high nutritional value development. Evaluation of the organoleptic and physical-chemical properties of model jelly samples with jost and spirulina showed that the proposed formula and technology gives a product with high consumer properties. There is a theoretically substantiated expediency of a jost and spirulina jelly implementation in such restaurant enterprises as dining rooms in the industrial plants. Using the jost and spirulina nutritional supplements can expand the range of the preventive nutrition foods.

  9. The system of values, motivation and self-attitude: gender features in high school students

    OpenAIRE

    Irina I. Vartanova

    2016-01-01

    The paper presents the results of the value orientation research in high school students, Moscow, Russia. The sample (N=62) included 22 education and universal values and also self-attitude parameters using the four types of emotional attitude to learning. These types of motivation profile were obtained via pre-factorization estimates of the seven values of school life using the method of semantic differential, which allowed to estimate the severity of a positional or status motivation (1), a...

  10. 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)

  11. Attitudes, Values and Background of High School Journalists Compared with the Media Elite.

    Science.gov (United States)

    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,…

  12. Reference interval computation: which method (not) to choose?

    Science.gov (United States)

    Pavlov, Igor Y; Wilson, Andrew R; Delgado, Julio C

    2012-07-11

    When different methods are applied to reference interval (RI) calculation the results can sometimes be substantially different, especially for small reference groups. If there are no reliable RI data available, there is no way to confirm which method generates results closest to the true RI. We randomly drawn samples obtained from a public database for 33 markers. For each sample, RIs were calculated by bootstrapping, parametric, and Box-Cox transformed parametric methods. Results were compared to the values of the population RI. For approximately half of the 33 markers, results of all 3 methods were within 3% of the true reference value. For other markers, parametric results were either unavailable or deviated considerably from the true values. The transformed parametric method was more accurate than bootstrapping for sample size of 60, very close to bootstrapping for sample size 120, but in some cases unavailable. We recommend against using parametric calculations to determine RIs. The transformed parametric method utilizing Box-Cox transformation would be preferable way of RI calculation, if it satisfies normality test. If not, the bootstrapping is always available, and is almost as accurate and precise as the transformed parametric method. Copyright © 2012 Elsevier B.V. All rights reserved.

  13. Neoclassical MHD equilibria with ohmic current

    International Nuclear Information System (INIS)

    Tokuda, Shinji; Takeda, Tatsuoki; Okamoto, Masao.

    1989-01-01

    MHD equilibria of tokamak plasmas with neoclassical current effects (neoclassical conductivity and bootstrap current) were calculated self-consistently. Neoclassical effects on JFT-2M tokamak plasmas, sustained by ohmic currents, were studied. Bootstrap currents flow little for L-mode type equilibria because of low attainable values of poloidal beta, β J . H-mode type equilibria give bootstrap currents of 30% ohmic currents for β J attained by JFT-2M and 100% for β J ≥ 1.5, both of which are sufficient to change the current profiles and the resultant MHD equilibria. Neoclassical conductivity which has roughly half value of the classical Spitzer conductivity brings peaked ohmic current profiles to yield low safety factor at the magnetic axis. Neoclassical conductivity reduces the value of effective Z(Z eff ) which is necessary to give the observed one-turn voltage but it needs impurities accumulating at the center when such peaked current profiles are not observed. (author)

  14. Uncertainty Analysis of the Water Scarcity Footprint Based on the AWARE Model Considering Temporal Variations

    Directory of Open Access Journals (Sweden)

    Jong Seok Lee

    2018-03-01

    Full Text Available The purpose of this paper is to compare the degree of uncertainty of the water scarcity footprint using the Monte Carlo statistical method and block bootstrap method. Using the hydrological data of a water drainage basin in Korea, characterization factors based on the available water remaining (AWARE model were obtained. The uncertainties of the water scarcity footprint considering temporal variations in paddy rice production in Korea were estimated. The block bootstrap method gave five-times smaller percentage uncertainty values of the model output compared to that of the two different Monte Carlo statistical method scenarios. Incorrect estimation of the probability distribution of the AWARE characterization factor model is what causes the higher uncertainty in the water scarcity footprint value calculated by the Monte Carlo statistical method in this study. This is because AWARE characterization factor values partly follows discrete distribution with extreme value on one side. Therefore, this study suggests that the block bootstrap method is a better choice in analyzing uncertainty compared to the Monte Carlo statistical method when using the AWARE model to quantify the water scarcity footprint.

  15. Achieving high fusion reactivity in high poloidal beta discharges in TFTR

    International Nuclear Information System (INIS)

    Manuel, M.E.; Navratil, G.A.; Sabbagh, S.A.; Batha, S.; Bell, M.G.; Bell, R.; Budny, R.V.; Bush, C.E.; Cavallo, A.; Chance, M.S.; Cheng, C.Z.; Efthimion, P.C.; Fredrickson, E.D.; Fu, G.Y.; Hawryluk, R.J.; Janos, A.C.; Jassby, D.L.; Levinton, F.; Mikkelsen, D.R.; Manickam, J.; McCune, D.C.; McGuire, K.M.; Medley, S.S.; Mueller, D.; Nagayama, Y.; Owens, D.K.; Park, H.K.; Ramsey, A.T.; Stratton, B.C.; Synakowski, E.J.; Taylor, G.; Wieland, R.M.; Yamada, M.; Zarnstorff, M.C.: Zweben, S.; Kesner, J.; Marmar, E.; Snipes, J.; Terry, J.

    1993-04-01

    High poloidal beta discharges have been produced in TFTR that achieved high fusion reactivities at low plasma currents. By rapidly decreasing the plasma current just prior to high-power neutral beam injection, relatively peaked current profiles were created having high l i > 2, high Troyon-normalized beta, βN > 3, and high poloidal beta. β p ≥ 0.7 R/a. The global energy confinement time after the current ramp was comparable to supershots, and the combination of improved MHD stability and good confinement produced a new high εβ p high Q DD operating mode for TFTR. Without steady-state current profile control, as the pulse lengths of high βp discharges were extended, l i decreased, and the improved stability produced immediately after by the current ramp deteriorated. In four second, high εβ p discharges, the current profile broadened under the influence of bootstrap and beam-drive currents. When the calculated voltage throughout the plasma nearly vanished, MHD instabilities were observed with β N as low as 1.4. Ideal MHD stability calculations showed this lower beta limit to be consistent with theoretical expectations

  16. Fast and accurate phylogenetic reconstruction from high-resolution whole-genome data and a novel robustness estimator.

    Science.gov (United States)

    Lin, Y; Rajan, V; Moret, B M E

    2011-09-01

    The rapid accumulation of whole-genome data has renewed interest in the study of genomic rearrangements. Comparative genomics, evolutionary biology, and cancer research all require models and algorithms to elucidate the mechanisms, history, and consequences of these rearrangements. However, even simple models lead to NP-hard problems, particularly in the area of phylogenetic analysis. Current approaches are limited to small collections of genomes and low-resolution data (typically a few hundred syntenic blocks). Moreover, whereas phylogenetic analyses from sequence data are deemed incomplete unless bootstrapping scores (a measure of confidence) are given for each tree edge, no equivalent to bootstrapping exists for rearrangement-based phylogenetic analysis. We describe a fast and accurate algorithm for rearrangement analysis that scales up, in both time and accuracy, to modern high-resolution genomic data. We also describe a novel approach to estimate the robustness of results-an equivalent to the bootstrapping analysis used in sequence-based phylogenetic reconstruction. We present the results of extensive testing on both simulated and real data showing that our algorithm returns very accurate results, while scaling linearly with the size of the genomes and cubically with their number. We also present extensive experimental results showing that our approach to robustness testing provides excellent estimates of confidence, which, moreover, can be tuned to trade off thresholds between false positives and false negatives. Together, these two novel approaches enable us to attack heretofore intractable problems, such as phylogenetic inference for high-resolution vertebrate genomes, as we demonstrate on a set of six vertebrate genomes with 8,380 syntenic blocks. A copy of the software is available on demand.

  17. Biological potential of microalgae in China for biorefinery-based production of biofuels and high value compounds.

    Science.gov (United States)

    Li, Jingjing; Liu, Ying; Cheng, Jay J; Mos, Michal; Daroch, Maurycy

    2015-12-25

    Microalgae abundance and diversity in China shows promise for identifying suitable strains for developing algal biorefinery. Numerous strains of microalgae have already been assessed as feedstocks for bioethanol and biodiesel production, but commercial scale algal biofuel production is yet to be demonstrated, most likely due to huge energy costs associated with algae cultivation, harvesting and processing. Biorefining, integrated processes for the conversion of biomass into a variety of products, can improve the prospects of microalgal biofuels by combining them with the production of high value co-products. Numerous microalgal strains in China have been identified as producers of various high value by-products with wide application in the medicine, food, and cosmetics industries. This paper reviews microalgae resources in China and their potential in producing liquid biofuels (bioethanol and biodiesel) and high value products in an integrated biorefinery approach. Implementation of a 'high value product first' principle should make the integrated process of fuels and chemicals production economically feasible and will ensure that public and private interest in the development of microalgal biotechnology is maintained. Copyright © 2015 Elsevier B.V. All rights reserved.

  18. Value of improved lipid control in patients at high risk for adverse cardiac events.

    Science.gov (United States)

    Jena, Anupam B; Blumenthal, Daniel M; Stevens, Warren; Chou, Jacquelyn W; Ton, Thanh G N; Goldman, Dana P

    2016-06-01

    Lipid-lowering therapy (LLT) is suboptimally used in patients with hyperlipidemia in the 2 highest statin benefit groups (SBGs), as categorized by the American College of Cardiology and the American Heart Association. This study estimated the social value of reducing low-density lipoprotein cholesterol (LDL-C) levels by 50% for patients in SBGs 1 and 2 who have been treated with standard LLT but have not reached LDL-C goal, as well as the potential value of PCSK9 inhibitors for patients in these groups. Simulation model. We used National Health and Nutrition Examination Surveys (NHANES) and US Census data to project the population of SBGs 1 and 2 in the time period 2015 to 2035. We used insurance claims data to estimate incidence rates of major adverse cardiac events (MACEs), and NHANES with National Vital Statistics data to estimate cardiovascular disease mortality rates. Using established associations between LDL-C and MACE risk, we estimated the value of reducing LDL-C levels by 50%. We incorporated results from a meta-analysis to estimate the value of PSCK9 inhibitors. Among those treated with LLT with LDL-C > 70 mg/dL in SBGs 1 and 2, the cumulative value of reducing LDL-C levels by 50% would be $2.9 trillion from 2015 to 2035, resulting primarily from 1.6 million deaths averted. The cumulative value of PCSK9 inhibitors would range from $3.4 trillion to $5.1 trillion (1.9-2.8 million deaths averted), or $12,000 to $17,000 per patient-year of treatment. Lowering LDL-C in high-risk patients with hyperlipidemia has enormous potential social value. For patients in these high-risk groups, PCSK9 inhibitors may have considerable net value depending on the final prices payers ultimately select.

  19. Age-adjusted high-sensitivity troponin T cut-off value for risk stratification of pulmonary embolism.

    Science.gov (United States)

    Kaeberich, Anja; Seeber, Valerie; Jiménez, David; Kostrubiec, Maciej; Dellas, Claudia; Hasenfuß, Gerd; Giannitsis, Evangelos; Pruszczyk, Piotr; Konstantinides, Stavros; Lankeit, Mareike

    2015-05-01

    High-sensitivity troponin T (hsTnT) helps in identifying pulmonary embolism patients at low risk of an adverse outcome. In 682 normotensive pulmonary embolism patients we investigate whether an optimised hsTnT cut-off value and adjustment for age improve the identification of patients at elevated risk. Overall, 25 (3.7%) patients had an adverse 30-day outcome. The established hsTnT cut-off value of 14 pg·mL(-1) retained its high prognostic value (OR (95% CI) 16.64 (2.24-123.74); p=0.006) compared with the cut-off value of 33 pg·mL(-1) calculated by receiver operating characteristic analysis (7.14 (2.64-19.26); pvalue of 45 pg·mL(-1) but not the established cut-off value of 14 pg·mL(-1) predicted an adverse outcome. An age-adjusted hsTnT cut-off value (≥14 pg·mL(-1) for patients aged risk (12.4% adverse outcome). Risk assessment of normotensive pulmonary embolism patients was improved by the introduction of an age-adjusted hsTnT cut-off value. A three-step approach helped identify patients at higher risk of an adverse outcome who might benefit from advanced therapy. Copyright ©ERS 2015.

  20. Finansiell Bootstrapping i SME : en kvantitativ studie om hur ett starkt socialt och affärsmässigt nätverk påverkar valet av bootstrappingmetoder

    OpenAIRE

    Nilsson, Ida; Sacic, Zehra

    2016-01-01

    Syftet med denna kandidatuppsats är se hur ett starkt socialt och affärsmässigt nätverk påverkar valet av bootstrappingmetoder i små och medelstora företag (SME). Detta eftersom SME står för 99,9 procent av samtliga företag på den svenska marknaden och därmed är betydelsefulla för landets ekonomiska tillväxt och sysselsättning. Däremot möter SME svårigheter vid extern finansiering av sin verksamhet. SME kompenserar detta genom att engagera sig i olika ”bootstrappingaktiviteter”. Bootstrapping...