Miracle-dz/UniFAR-FTUs huggingface dataset:
On the origin of the tropical Atlantic decadal oscillation based on the analysis of the ICOADS

From an analysis of the International Comprehensive Ocean–Atmosphere Data Set, we were able to confirm salient features of the tropical Atlantic decadal oscillation illustrated in previous works. These features include antisymmetric behaviour of surface air pressure and sea surface temperature with two centres of action residing in the tropical North and South Atlantic Oceans. In addition to the recognized features of the oscillation, we found a new aspect: the principal mechanism regulating the oscillation differs between the north and south centres of action. Decadal components of the relative humidity time series show a maximum value of lag cross‐correlation at a lag of −2 years. Such a temporal evolution was irrespective of the centres of action and the reference time series. The two reference series employed are the sunspot numbers and the southerlies over the western equatorial Atlantic. Associated with this, statistically significant phase shifts between the decadal components of variables exist, especially in the tropical North Atlantic Ocean. For the decadal oscillation, relative humidity change was dominated by specific humidity change over the tropical North Atlantic and by air temperature change over the tropical South Atlantic. For the frequency band of the solar cycle, the variation of relative humidity seemed to amplify the Earth's response to the sun's radiation changes that had previously been considered too small to affect the Earth's climate. By incorporating our new findings with the known features of the oscillation, we can suggest that the variability of solar radiation may be crucial as an originator, or at least as a regulator, of the oscillation in combination with the climate distribution of clouds and water vapour over the tropical Atlantic. Copyright © 2006 Royal Meteorological Society.
A Reanalysis of the Stanford Heart Transplant Data

Abstract This article represents analyses of survival of patients in the Stanford Heart Transplantation Program. We model survival time as a function of patient covariates and transplant status, and compare the results obtained using various parametric representations for survival time, including the Weibull, lognormal, and piecewise exponential distributions. Pretransplant and posttransplant survival are considered separately, and the effect of transplantation on survival is examined by comparison of the separate hazard functions. Comparisons are made with previous analyses. Using the piecewise exponential models, we estimate a generally declining hazard before transplant; after transplant the hazard increases for about 60 days, then declines. The presence of heavy censoring before and after transplant means that many of the other parametric models with differing shapes for the hazard all give equally adequate fits to the data. Inferences about the effect of covariates are also relatively insensitive to .
Least‐squares spectral element method applied to the Euler equations

This paper describes the application of the least‐squares spectral element method to compressible flow problems. Special attention is paid to the imposition of the weak boundary conditions along curved walls and the influence of the time step on the position and resolution of shocks. The method is described and results are presented for a supersonic flow over a wedge and subsonic, transonic and supersonic flow problems over a bump. Copyright © 2008 John Wiley & Sons, Ltd.
Some recent advances in the investigation of shell buckling.

A survey is presented which includes the buckling of shells under loads for which the shell is sensitive to initial imperfections. Results for such cases show that improvements in experiment and theory have produced previously unobtainable agreement. The necessity of the correct (and consistent) theoretical specification of boundary conditions is then demonstrated. Recent stiffened cylinder results are surveyed to expose the large effects on the buckling strength of internal or external stiffening, axial load applied eccentric to the wall neutral surface, and the addition of small meridional curvature.
Extended-range predictions with ecmwf models: Interannual variability in operational model integrations

A set of 30-day integrations made with the operational ECMWF model over a period of three and a half years (from 1985 to 1988) is studied. the impact of model reformulations during this period on the climate drift of the model is assessed, and the level of extended-range forecast skill achieved by the operational model is studied. Diagnostics of zonal average 30-day mean wind and temperature error show a systematic reduction in the extratropics over three years. It is argued that these improvements are consistent with the changes in model formulation. Eddy fluxes of heat and momentum, and levels of eddy kinetic energy are similarly improved. We also show that the ability to simulate blocking activity in the extended range has improved substantially over the three winters. From maps showing the ratio of systematic to total error it is concluded that, by the final winter, the middle-latitude extended-range error is almost entirely associated with random errors. This is supported by the growth of the dispersion, or spread, between forecasts initialized 24 hours apart. In particular, for the extended winter 1987/88, it is shown that the asymptotic level of (internal) spread is comparable with the asymptotic level of (external) skill. By contrast, in the tropics, the total error is dominated by the systematic error for all years. Despite improvements to the model, extended-range forecast skill is modest. Skill has been measured in a spatially-filtered three-dimensional phase space, spanned by rotated EOF (empirical orthogonal function) coefficients of 500 mb height, which contain the principal weather regimes in the atmosphere. On average the skill scores are consistent with those of other major centres studying dynamical extended-range prediction. In particular there is evidence of skill to day 15 and possibly to day 20 in middle latitudes. Beyond day 20 skill is marginal. We demonstrate that in the winter sample of operational-model forecasts, skill is correlated with the observed value of the first rotated EOF, which can be described as a global version of the Pacific/North American mode. By contrast, the ability to predict monthly mean fields in the tropics depends primarily on a knowledge of the boundary forcing, including sea surface temperature. It is shown that some aspects of the interannual variations in the summer monsoon circulation can be predicted, in particular the tropical easterly jet anomalies, African rainfall, and, to a much lesser extent, Indian monsoon rainfall.
A Test of Missing Completely at Random for Multivariate Data with Missing Values

Abstract A common concern when faced with multivariate data with missing values is whether the missing data are missing completely at random (MCAR); that is, whether missingness depends on the variables in the data set. One way of assessing this is to compare the means of recorded values of each variable between groups defined by whether other variables in the data set are missing or not. Although informative, this procedure yields potentially many correlated statistics for testing MCAR, resulting in multiple-comparison problems. This article proposes a single global test statistic for MCAR that uses all of the available data. The asymptotic null distribution is given, and the small-sample null distribution is derived for multivariate normal data with a monotone pattern of missing data. The test reduces to a standard t test when the data are bivariate with missing data confined to a single variable. A limited simulation study of empirical sizes for the test applied to normal and nonnormal data suggests th.
Asymptotic properties of algorithms of data compression with fidelity criterion based on string matching

A data compression scheme proposed by Steinberg and Gutman [1993] is essentially an extension of the Ziv-Lempel algorithm [1977]. Their scheme, however, does not achieve the rate-distortion bound in their original form. In the present paper, sufficient conditions that the rate of the scheme achieves the rate-distortion bound are analyzed for discrete memoryless sources and memoryless gaussian sources under the single-letter fidelity criterion and squared-error fidelity criterion, respectively. <<ETX>>
Configural Frequency Analysis: The Search for Extreme Cells

Configural Frequency Analysis (CFA) asks whether a cell in a cross-classification contains more or fewer cases than expected with respect to some base model. This base model is specified such that cells with more cases than expected (also called types) can be interpreted from a substantive perspective. The same applies to cells with fewer cases than expected (antitypes). This article gives an introduction to both frequentist and Bayesian approaches to CFA. Specification of base models, testing, and protection are discussed. In an example, Prediction CFA and two-sample CFA are illustrated. The discussion focuses on the differences between CFA and modelling.
Empirical Localization of Observation Impact in Ensemble Kalman Filters

AbstractLocalization is a method for reducing the impact of sampling errors in ensemble Kalman filters. Here, the regression coefficient, or gain, relating ensemble increments for observed quantity y to increments for state variable x is multiplied by a real number α defined as a localization. Localization of the impact of observations on model state variables is required for good performance when applying ensemble data assimilation to large atmospheric and oceanic problems. Localization also improves performance in idealized low-order ensemble assimilation applications. An algorithm that computes localization from the output of an ensemble observing system simulation experiment (OSSE) is described. The algorithm produces localizations for sets of pairs of observations and state variables: for instance, all state variables that are between 300- and 400-km horizontal distance from an observation. The algorithm is applied in a low-order model to produce localizations from the output of an OSSE and the compu.
Non-Stationary Oscillations About a Simple Bifurcation

Abstract The non-stationary response of a non-linear oscillator that exhibits a simple bifurcation from one stable root to another is discussed. The discussion is motivated by previous work on the coupled pitch and role modes of a ship. Two aspects of the analysis are emphasized: (i) aspects of the response described numerically by others are described analytically; and (ii) analysis of the response using only local stability of the two response solutions is inadequate. A global stability criterion is obtained, and it is shown that what appear to be rapid jumps from one solution to another are in fact smooth transitions on the phase plane.
On edge-corrected probability density function estimators for point processes

FIKSEL (1988) provides an asymptotically unbiased kernel estimator for the density hs (r) of the spherical contact distribution function of stationary and isotropic point processes. This paper proposes alternative estimators of hs (r) for use with regular grid of locations. The existing estimator of hs (r) and the alternatives proposed in this paper are then tested out in a simulation study.
Characterization of first-order optical properties for asymmetric systems

First-order imaging properties are often represented in the form of a derivative matrix. This representation is not always expedient, however, since the elements of the matrix are not all independent; some elements can be written as functions of the others. Ideally, the first-order imaging properties should be represented without any redundant (and, therefore, possibly inconsistent) information. Further, it is convenient to characterize these properties in terms of entities with direct geometric interpretations. Hamilton’s methods are used here to determine a minimal set of geometric entities that is sufficient to characterize the first-order imaging properties of asymmetric systems. Although certain aspects of this problem have been discussed elsewhere, a particular facet has been consistently misinterpreted. This issue is resolved here by establishing that there is no unique first-order image plane for any optical system—regardless of symmetry.
Myosin Heavy Chain Characteristics and Their Relationship to Exercise Performance

There are a large variety of factors that affect performance in physical tasks. One factor is the muscle myosin heavy chain (MHC) composition of the muscle involved in the task. Differences in MHC can affect not just exercise performance, but can be related to general health. Purpose: The purpose of this study was to examine the relationship between exercise performance and MHC composition. Methods: Forty two (n=42) males of a variety of training backgrounds (aerobically trained, resistance trained, recreationally trained, and sedentary) took part in this study (Age = 22.4±3.5 years, Height 1.78±.07m, Weight 78.7±13.3 kg). Subjects were familiarized with vertical jumps, as well as maximal and fatiguing leg extensions during their first visit. A DEXA scan was performed on each subject along with thigh girth and skinfold caliper measurements. The following visit, subjects performed 2 reps of the following jump variations: counter movement jump, with and without arm swing, and depth jumps. Each jump was recorded utilizing a 2 dimensional force plate. Subjects then were tested for leg extension one repetition maximum (1RM). During the final testing session, subjects performed maximal velocity leg extensions at 30, 40, 50, 60, 70, 80, and 90% of their 1RM. Subjects then performed 15 maximal velocity repetitions at 70% of their 1RM on a cadence. Each rep of leg extension performance was recorded for velocity and torque. Immediately afterwards, a muscle biopsy was taken from the vastus lateralis that would be analyzed for MHC content utilizing SDS-PAGE separation (IIX = 13.8±12.9%, IIA =49.5±10.3 %, I = 36.8±11.3%). Data analysis of vertical jump and leg extension performance was analyzed for a number of variables. Results: Significant relationships were found between jump peak and mean power relative to cross sectional area of the thigh with type IIX fiber (r = .429-.459*)(* = significance p <.05). Negative relationships were noted with vertical jump height and type I fiber (r=-.355*), velocity load slope
Adaptive pole placement control for vibration control of a smart cantilevered beam in thermal environment

Piezoelectric actuators used in vibration control and high precision control have been widely used in recent years. In aeronautics and MEMS systems especially, their applications are spread from vibration suppression to position control. In this paper, a finite element model (FEM) of a piezoelectric actuator and cantilever in a thermal environment is presented to suppress vibration effectively. In other words, the FEM is namely a thermal-electrical-mechanical coupled FEM. Based on an eight-node plane finite element, the harmonic analysis and the free vibration analysis have been obtained in the current work. Therefore a transfer function model will be attained through the harmonic analysis by an identification method. In addition, a controller is designed with the adaptive pole placement control (APPC). Finally, through simulation, the thermal influence is considerable for natural frequencies, harmonic response and free vibration. Moreover, the APPC is a significant plan to vibration control in the paper.
Nonthermal effects on the elastic electron–atom collision in generalized Lorentzian semiclassical plasmas: Lorentzian renormalization shielding

The Lorentzian renormalization plasma shielding effects on the elastic electron–atom collision are investigated in generalized Lorentzian semiclassical plasmas. The eikonal analysis and the effective interaction potential are employed to obtain the eikonal scattering phase shift, differential eikonal collision cross section, and total eikonal collision cross section as functions of the collision energy, impact parameter, nonthermal renormalization parameter, and spectral index of the Lorentzian plasma. It is found that the influence of Lorentzian renormalization shielding suppresses the eikonal scattering phase shift and, however, enhances the eikonal collision cross section in Lorentzian semiclassical plasmas. Additionally, the energy dependence on the total collision cross section in nonthermal plasmas is found to be more significant than that in thermal plasmas.
Minimum spatial entropy threshold selection

Many image grey level thresholding methods based on the theory of maximum entropy have been proposed in the past. However, the exact definition of what is meant by 'image entropy' has varied considerably, with measures based on the image itself, its histogram or other related distributions being proposed. Most of these ignore the spatial component of the image, assuming pixels within the image to be independent of each other. While this is convenient, it is counterintuitive. A recent measure of spatial entropy, which attempts to include the spatial information inherent in the image, has been used here as a criterion function for threshold selection. Results indicate an improvement over methods that ignore this information.
Introduction to the Practice of Statistics

PART I: LOOKING AT DATA Looking at Data-Distributions Looking at Data-Relationships Producing Data PART II: PROBABILITY AND INFERENCE Probability: The Study of Randomness Sampling Distributions Introduction to Inference Inference for Distributions Inference for Proportions PART III: TOPICS ON INFERENCE Analysis of Two-Way Tables Inference for Regression Multiple Regression One-Way Analysis of Variance Two-Way Analysis of Variance Additional chapters available on the CD-ROM and the website: Logistic Regression Nonparametric Tests Bootstrap Methods and Permutation Tests Statistics for Quality: Control and Capability
Thermodynamics, A Dynamical Systems Approach

Thermodynamics is universal;in principle, the subject appliesto everything. Accordingly,everyone is entitled to theirown opinion regarding howthermodynamics relates tohis/her own field of specializa-tion. According to Albert Einstein “thermodynamics is theonly physical theory of a universal nature of which I amconvinced that it will never be overthrown. ” Throughout history, universal principles such as basichuman rights have not always been implemented in prac-tice. Thermodynamics, however, is independent of one’spolitical philosophy. No tyrant or dictator can decide aboutthermodynamics. If someone comes to me with a rheologi-cal law for a non-Newtonian fluid that does not obey thesecond law of thermodynamics, I can say beforehand thatsomething is fishy with that model. What is left to humans,and especially to the scientist, is the explanation of the emer-gence of thermodynamics in its irreversible version from anapparently nondissipative microworld. (Recall that the lawsof physics are time reversible at the microscale.) Moreover,the job of the scientist also entails developing and interpret-ing the most appropriate mathematical framework for ther-modynamics as well as applying its central tenets todisputed fields such as living systems and large-scalephysics, that is, cosmology and the future evolution of theuniverse—and, therefore, the ultimate destiny of humans. It is an agreed fact that mathematics is the common lan-guage of science. The authors claim that “mathematics isthe irrefutable pathway to the truth. ” This statement is notexactly true in general; it is true only insofar as mathemat-ics
AO 0235+164 and Surrounding Field: Surprising HST Results

Results obtained with the Hubble Space Telescope on the highly variable radio, x-ray, and gamma-ray emitting QSO (or BL Lac object) AO 0235 + 164 are presented and analyzed. WFPC2 images were obtained in 1994 June, when AO 0235 + 164 was bright (m approx. 17), and the results are described in Sec. 3. After subtraction of the PSF of the QSO, hereafter called AO following the nomenclature of Yanny et al. (1989), the companion object named A, 2 sec south of AO, is discovered not to be an elliptical galaxy as hypothesized earlier, but to be an AGN object, with a central UV-bright point-source nucleus and faint surrounding nebulosity extending to AO. The second companion object 1.3 sec east of AO discovered by Yanny et al. (1989) and named object Al, appears more like a normal spiral galaxy. We have measured the positions, luminosities, and colors of some 30 faint objects in the field around AO 0235 + 16; most are extended and may be star-forming galaxies in a loose group or cluster. Our most surprising result of the HST observations comes from FOS spectra obtained in 1995 July, discussed in Sec. 4. Because of a positioning error of the telescope and AO's faintness at that time (m approx. 20), object A was observed instead of the intended target AO. Serendipitously, we discovered A to have broad deep BALQSO-type absorptions of C IV, Si IV, N V shortward of broad emissions. A is thus ejecting high velocity, highly ionized gas into the surrounding IGM. We discuss in Sec. 5 the relationship of the objects in the central 10 sec X 1O sec region around AO, where redshifts z(sub e) = 0.94, z(sub a) = 0.524, 0.851 in AO, (sub e) = 0.524 and Z(sub BAL)=0.511 in A, are found. We hypothesize that some of the 30 faint objects in the 77 sec. x 77 sec. field may be part of a large star-forming region at z approx. 0.5, as suggested for a few objects by Yanny et al. (1989). The proximity of two highly active extragalactic objects, AO 0235+164 and its AGN companion A, is remarkable and one of the authors (EMB) suggests it may require consideration of a non-cosmological component of redshift in AO 0235+164.
Statistical Power with Group Mean as the Unit of Analysis

In 1940 Lindquist presented a discussion of an analysis of variance using the group mean as the unit of analysis. Unfortunately, most modern writers on statistical methodology have ignored this important topic and some of the best text-book book writers make the error of using the individual as the unit of analysis when the group mean would be more appropriate. The reluctance to use group mean as the unit of analysis is due in part to the belief that the resultant drop in the number of observations per treatment greatly reduces the probability of detecting a treatment effect. This concern is put in perspective in this paper and equations are presented to facilitate power estimates when the group mean is the unit of analysis.
POLYNOMIAL INVARIANTS OF FOUR-DIMENSIONAL ORTHOGONAL GROUPS

Let Q be a nondegenerate quadratic form over the finite field F q and O n (F q ) be the associated orthogonal group. Let O n (F q ) act linearly on the polynomial ring F q [x 1, …, x n ]. We find the invariant subring of O 4(F q ) with explicit generators.