Science.gov

Sample records for 50-minute period statistical

  1. The discovery of 50 minute periodic absorption events from 4U1915-05

    NASA Technical Reports Server (NTRS)

    White, N. E.; Swank, J. H.

    1981-01-01

    The steady flux from 4U1916-05 which undergoes periodic absorption dips every 50 minutes was demonstrated. This period represents the underlying orbital period of the system. It is suggested that variations in the depth and duration of these events are caused by a bulge in the edge of the accretion disk, at the point where the gas stream impacts the disk. The mass losing star in this system is probably a low mass white dwarf. The spectrum of the dips indicates that the metallicity of the absorbing material is at least a factor 17 below solar values.

  2. Providing Students with Foundational Field Instruction within a 50 Minute Class Period: A Practical Example

    NASA Astrophysics Data System (ADS)

    Percy, M.

    2014-12-01

    There is a growing recognition among secondary educators and administrators that students need to have a science education that provides connections between familiar classes like biology, chemistry, and physics. Because of this waxing interest in an integrative approach to the sciences, there is a broader push for school districts to offer classes geared towards the earth sciences, a field that incorporates knowledge and skills gleaned from the three core science subjects. Within the contexts of a regular secondary school day on a traditional schedule (45- to 50-minute long classes), it is challenging to engage students in rigorous field-based learning, critical for students to develop a deeper understanding of geosciences content, without requiring extra time outside of the regular schedule. We suggest instruction using common, manmade features like drainage retention ponds to model good field practices and provide students with the opportunity to calculate basic hydrologic budgets, take pH readings, and, if in an area with seasonal rainfall, make observations regarding soils by way of trenching, and near-surface processes, including mass wasting and the effects of vegetation on geomorphology. Gains in student understanding are discussed by analyzing the difference in test scores between exams provided to the students after they had received only in-class instruction, and after they had received field instruction in addition to the in-class lectures. In an advanced setting, students made measurements regarding ion contents and pollution that allowed the classes to practice lab skills while developing a data set that was analyzed after field work was completed. It is posited that similar fieldwork could be an effective approach at an introductory level in post-secondary institutions.

  3. A Single 50-Minute Lunch Hour Fits Everyone

    ERIC Educational Resources Information Center

    Goodman, Carole

    2007-01-01

    Switching from multiple lunch periods to one lunch period for the nearly 2,000 students at James Hubert Blake High School in Silver Spring, Maryland, has contributed more to a positive school climate than any other single factor in the eight years since the school opened. This article presents how Blake has come up with the single 50-minute lunch…

  4. Biomechanical Changes During a 50-minute Run in Different Footwear and on Various Slopes.

    PubMed

    Lussiana, Thibault; Hébert-Losier, Kim; Millet, Grégoire P; Mourot, Laurent

    2016-02-01

    The effects of footwear and inclination on running biomechanics over short intervals are well documented. Although recognized that exercise duration can impact running biomechanics, it remains unclear how biomechanics change over time when running in minimalist shoes and on slopes. Our aims were to describe these biomechanical changes during a 50-minute run and compare them to those observed in standard shoes. Thirteen trained recreational male runners ran 50 minutes at 65% of their maximal aerobic velocity on a treadmill, once in minimalist shoes and once in standard shoes, 1 week apart in a random order. The 50-minute trial was divided into 5-minute segments of running at 0%, +5%, and -5% of treadmill incline sequentially. Data were collected using photocells, high-speed video cameras, and plantar-pressure insoles. At 0% incline, runners exhibited reduced leg stiffness and plantar flexion angles at foot strike and lower plantar pressure at the forefoot and toes in minimalist shoes from minute 34 of the protocol onward. However, only reduced plantar pressure at the toes was observed in standard shoes. Overall, similar biomechanical changes with increased exercise time were observed on the uphill and downhill inclines. The results might be due to the unfamiliarity of subjects to running in minimalist shoes. PMID:26367201

  5. Statistical Transmutation in Periodically Driven Optical Lattices

    NASA Astrophysics Data System (ADS)

    Sedrakyan, Tigran; Galitski, Victor; Kamenev, Alex

    We show that interacting bosons in a periodically driven two dimensional (2D) optical lattice may effectively exhibit fermionic statistics. The phenomenon is similar to the celebrated Tonks-Girardeau regime in 1D. The Floquet band of a driven lattice develops the moat shape, i.e., a minimum along a closed contour in the Brillouin zone. Such degeneracy of the kinetic energy favors fermionic quasiparticles. The statistical transmutation is achieved by the Chern-Simons flux attachment similar to the fractional quantum Hall case. We show that the velocity distribution of the released bosons is a sensitive probe of the fermionic nature of their stationary Floquet state. This work was supported by the PFC-JQI (T.S.), USARO and Simons Foundation (V.G.), and DOE Contract DE-FG02-08ER46482 (A.K.).

  6. The MXB1916-053/4U1915-05: Burst properties and constraints on a 50 minute binary secondary

    NASA Technical Reports Server (NTRS)

    Swank, J. H.; Taam, R. E.; White, N. E.

    1983-01-01

    Results are presented from OSO-8 and HEAO-1 A2 observations of 34 bursts from the X-ray burster MXB1916-053/4U1915-05 recently discovered to show a 50 minute binary period. While 11 burst previously reported all had similar light curves, 22 observed two years later show a factor of 3 range of peak fluxes and decay times between 3 and 20 s. Recurrence times between successive bursts vary between 3 and 6 hours. A ratio of steady flux to average burst flux of equiv 120 is developed. A burst observed with the HEAO-1 A2 experiment showed an initial temperature rise to a peak black body temperature of equiv 3 keV followed by the cooling typical of type I bursts. The burst was unusual in that the apparent projected size of a blackbody source increased by a factor of 3 during the cooling phase.

  7. Gene Identification Algorithms Using Exploratory Statistical Analysis of Periodicity

    NASA Astrophysics Data System (ADS)

    Mukherjee, Shashi Bajaj; Sen, Pradip Kumar

    2010-10-01

    Studying periodic pattern is expected as a standard line of attack for recognizing DNA sequence in identification of gene and similar problems. But peculiarly very little significant work is done in this direction. This paper studies statistical properties of DNA sequences of complete genome using a new technique. A DNA sequence is converted to a numeric sequence using various types of mappings and standard Fourier technique is applied to study the periodicity. Distinct statistical behaviour of periodicity parameters is found in coding and non-coding sequences, which can be used to distinguish between these parts. Here DNA sequences of Drosophila melanogaster were analyzed with significant accuracy.

  8. Statistical methods for detecting periodic fragments in DNA sequence data

    PubMed Central

    2011-01-01

    Background Period 10 dinucleotides are structurally and functionally validated factors that influence the ability of DNA to form nucleosomes, histone core octamers. Robust identification of periodic signals in DNA sequences is therefore required to understand nucleosome organisation in genomes. While various techniques for identifying periodic components in genomic sequences have been proposed or adopted, the requirements for such techniques have not been considered in detail and confirmatory testing for a priori specified periods has not been developed. Results We compared the estimation accuracy and suitability for confirmatory testing of autocorrelation, discrete Fourier transform (DFT), integer period discrete Fourier transform (IPDFT) and a previously proposed Hybrid measure. A number of different statistical significance procedures were evaluated but a blockwise bootstrap proved superior. When applied to synthetic data whose period-10 signal had been eroded, or for which the signal was approximately period-10, the Hybrid technique exhibited superior properties during exploratory period estimation. In contrast, confirmatory testing using the blockwise bootstrap procedure identified IPDFT as having the greatest statistical power. These properties were validated on yeast sequences defined from a ChIP-chip study where the Hybrid metric confirmed the expected dominance of period-10 in nucleosome associated DNA but IPDFT identified more significant occurrences of period-10. Application to the whole genomes of yeast and mouse identified ~ 21% and ~ 19% respectively of these genomes as spanned by period-10 nucleosome positioning sequences (NPS). Conclusions For estimating the dominant period, we find the Hybrid period estimation method empirically to be the most effective for both eroded and approximate periodicity. The blockwise bootstrap was found to be effective as a significance measure, performing particularly well in the problem of period detection in the

  9. Fast and Statistically Optimal Period Search in Uneven Sampled Observations

    NASA Astrophysics Data System (ADS)

    Schwarzenberg-Czerny, A.

    1996-04-01

    The classical methods for searching for a periodicity in uneven sampled observations suffer from a poor match of the model and true signals and/or use of a statistic with poor properties. We present a new method employing periodic orthogonal polynomials to fit the observations and the analysis of variance (ANOVA) statistic to evaluate the quality of the fit. The orthogonal polynomials constitute a flexible and numerically efficient model of the observations. Among all popular statistics, ANOVA has optimum detection properties as the uniformly most powerful test. Our recurrence algorithm for expansion of the observations into the orthogonal polynomials is fast and numerically stable. The expansion is equivalent to an expansion into Fourier series. Aside from its use of an inefficient statistic, the Lomb-Scargle power spectrum can be considered a special case of our method. Tests of our new method on simulated and real light curves of nonsinusoidal pulsators demonstrate its excellent performance. In particular, dramatic improvements are gained in detection sensitivity and in the damping of alias periods.

  10. The 50-Minute Robot.

    ERIC Educational Resources Information Center

    Buckland, Miram R.

    1985-01-01

    Sixth graders built working "robots" (or grasping bars) for remote control use during a unit on simple mechanics. Steps for making a robot are presented, including: cutting the wood, drilling and nailing, assembling the jaws, and making them work. The "jaws," used to pick up objects, illustrate principles of levers. (DH)

  11. Beyond the 50-minute hour: increasing control, choice, and connections in the lives of low-income women.

    PubMed

    Goodman, Lisa A; Smyth, Katya Fels; Banyard, Victoria

    2010-01-01

    Although poverty is associated with a range of mental health difficulties among women in this country, mainstream mental health interventions are not sufficient to meet the complex needs of poor women. This article argues that stress, powerlessness, and social isolation should become primary targets of our interventions, as they are key mediators of the relationship between poverty and emotional distress, particularly for women. Indeed, if ways are not found to address these conditions directly, by increasing women's control, choice, and connections, the capacity to improve the emotional well-being of impoverished women will remain limited at best. This is the first of 5 articles that comprise a special section of the American Journal of Orthopsychiatry, called "Beyond the 50-Minute Hour: Increasing Control, Choice, and Connections in the Lives of Low-Income Women." Together, these articles explore the nature and impact of a range of innovative mental health interventions that are grounded in a deep understanding of the experience of poverty. This introduction: (a) describes briefly how mainstream approaches fail to address the poverty-related mental health needs of low-income women; (b) illuminates the role of stress, powerlessness, and social isolation in women's lives; (c) highlights the ways in which the articles included in this special section address each of these by either adapting traditional mental health practices to attend to poverty's role in participants' lives or adapting community-based, social-justice-oriented interventions to attend to participants' mental health; and (d) discusses the research and evaluation implications of expanding mental health practices to meet the needs of low-income communities. PMID:20397984

  12. Statistical analysis of the ambiguities in the asteroid period determinations

    NASA Astrophysics Data System (ADS)

    Butkiewicz, M.; Kwiatkowski, T.; Bartczak, P.; Dudziński, G.

    2014-07-01

    A synodic period of an asteroid can be derived from its lightcurve by standard methods like Fourier-series fitting. A problem appears when results of observations are based on less than a full coverage of a lightcurve and/or high level of noise. Also, long gaps between individual lightcurves create an ambiguity in the cycle count which leads to aliases. Excluding binary systems and objects with non-principal-axis rotation, the rotation period is usually identical to the period of the second Fourier harmonic of the lightcurve. There are cases, however, where it may be connected with the 1st, 3rd, or 4th harmonic and it is difficult to choose among them when searching for the period. To help remove such uncertainties we analysed asteroid lightcurves for a range of shapes and observing/illuminating geometries. We simulated them using a modified internal code from the ISAM service (Marciniak et al. 2012, A&A 545, A131). In our computations, shapes of asteroids were modeled as Gaussian random spheres (Muinonen 1998, A&A, 332, 1087). A combination of Lommel-Seeliger and Lambert scattering laws was assumed. For each of the 100 shapes, we randomly selected 1000 positions of the spin axis, systematically changing the solar phase angle with a step of 5°. For each lightcurve, we determined its peak-to-peak amplitude, fitted the 6th-order Fourier series and derived the amplitudes of its harmonics. Instead of the number of the lightcurve extrema, which in many cases is subjective, we characterized each lightcurve by the order of the highest-amplitude Fourier harmonic. The goal of our simulations was to derive statistically significant conclusions (based on the underlying assumptions) about the dominance of different harmonics in the lightcurves of the specified amplitude and phase angle. The results, presented in the Figure, can be used in individual cases to estimate the probability that the obtained lightcurve is dominated by a specified Fourier harmonic. Some of the

  13. Conservation Reserve Programs: Enrollment statistics for signup periods 1-11 and fiscal years 1990-92. Statistical bulletin

    SciTech Connect

    Osborn, C.T.; Llacuna, F.; Linsenbigler, M.

    1992-11-01

    The United States Department of Agriculture accepted approximately 33.9 million acres of cropland into the Conservation Reserve Program (CRP) during 1986-89. These acres were enrolled in nine separate signups under the authority of the Food Security Act of 1985. Enrollment was extended through 1995 by the Food, Agriculture, Conservation, and Trade Act of 1990. Two signup periods were held in 1991. The 10th signup was for fiscal year 1991 retirement of land from production, and the 11th signup was for fiscal year 1992. Approximately 1.5 million additional acres were enrolled in these two signup periods under significantly revised program rules. The report presents statistics covering all CRP cropland enrolled in signup periods 1-11 and CRP cropland newly retired in fiscal years 1990-92.

  14. Statistical tests of peaks and periodicities in the observed redshift distribution of quasi-stellar objects

    NASA Astrophysics Data System (ADS)

    Duari, Debiprosad; Gupta, Patrick D.; Narlikar, Jayant V.

    1992-01-01

    An overview of statistical tests of peaks and periodicities in the redshift distribution of quasi-stellar objects is presented. The tests include the power-spectrum analysis carried out by Burbidge and O'Dell (1972), the generalized Rayleigh test, the Kolmogorov-Smirnov test, and the 'comb-tooth' test. The tests reveal moderate to strong evidence for periodicities of 0.0565 and 0.0127-0.0129. The confidence level of the periodicity of 0.0565 in fact marginally increases when redshifts are transformed to the Galactocentric frame. The same periodicity, first noticed in 1968, persists to date with a QSO population that has since grown about 30 times its original size. The prima facie evidence for periodicities in 1n(1 + z) is found to be of no great significance.

  15. On the Helicity in 3D-Periodic Navier-Stokes Equations II: The Statistical Case

    NASA Astrophysics Data System (ADS)

    Foias, Ciprian; Hoang, Luan; Nicolaenko, Basil

    2009-09-01

    We study the asymptotic behavior of the statistical solutions to the Navier-Stokes equations using the normalization map [9]. It is then applied to the study of mean energy, mean dissipation rate of energy, and mean helicity of the spatial periodic flows driven by potential body forces. The statistical distribution of the asymptotic Beltrami flows are also investigated. We connect our mathematical analysis with the empirical theory of decaying turbulence. With appropriate mathematically defined ensemble averages, the Kolmogorov universal features are shown to be transient in time. We provide an estimate for the time interval in which those features may still be present. Our collaborator and friend Basil Nicolaenko passed away in September of 2007, after this work was completed. Honoring his contribution and friendship, we dedicate this article to him.

  16. Mathematics and statistics research progress report, period ending June 30, 1983

    SciTech Connect

    Beauchamp, J. J.; Denson, M. V.; Heath, M. T.; Lever, W. E.; Wilson, D. G.

    1983-08-01

    This report is the twenty-sixth in the series of progress reports of Mathematics and Statistics Research of the Computer Sciences organization, Union Carbide Corporation Nuclear Division. Part A records research progress in analysis of large data sets, applied analysis, biometrics research, computational statistics, materials science applications, numerical linear algebra, and risk analysis. Collaboration and consulting with others throughout the Oak Ridge Department of Energy complex are recorded in Part B. Included are sections on biological sciences, energy, engineering, environmental sciences, health and safety, and safeguards. Part C summarizes the various educational activities in which the staff was engaged. Part D lists the presentations of research results, and Part E records the staff's other professional activities during the report period.

  17. Load Balancing Using Time Series Analysis for Soft Real Time Systems with Statistically Periodic Loads

    NASA Technical Reports Server (NTRS)

    Hailperin, Max

    1993-01-01

    This thesis provides design and analysis of techniques for global load balancing on ensemble architectures running soft-real-time object-oriented applications with statistically periodic loads. It focuses on estimating the instantaneous average load over all the processing elements. The major contribution is the use of explicit stochastic process models for both the loading and the averaging itself. These models are exploited via statistical time-series analysis and Bayesian inference to provide improved average load estimates, and thus to facilitate global load balancing. This thesis explains the distributed algorithms used and provides some optimality results. It also describes the algorithms' implementation and gives performance results from simulation. These results show that our techniques allow more accurate estimation of the global system load ing, resulting in fewer object migration than local methods. Our method is shown to provide superior performance, relative not only to static load-balancing schemes but also to many adaptive methods.

  18. Mathematics and Statistics Research Department progress report, period ending June 30, 1982

    SciTech Connect

    Denson, M.V.; Funderlic, R.E.; Gosslee, D.G.; Lever, W.E.

    1982-08-01

    This report is the twenty-fifth in the series of progress reports of the Mathematics and Statistics Research Department of the Computer Sciences Division, Union Carbide Corporation Nuclear Division (UCC-ND). Part A records research progress in analysis of large data sets, biometrics research, computational statistics, materials science applications, moving boundary problems, numerical linear algebra, and risk analysis. Collaboration and consulting with others throughout the UCC-ND complex are recorded in Part B. Included are sections on biology, chemistry, energy, engineering, environmental sciences, health and safety, materials science, safeguards, surveys, and the waste storage program. Part C summarizes the various educational activities in which the staff was engaged. Part D lists the presentations of research results, and Part E records the staff's other professional activities during the report period.

  19. Statistical analysis of digital images of periodic fibrous structures using generalized Hurst exponent distributions

    NASA Astrophysics Data System (ADS)

    Blachowicz, Tomasz; Ehrmann, Andrea; Domino, Krzysztof

    2016-06-01

    Distinction of diverse two-dimensional periodic structures can be based on a large number of methods and parameters, while the quantitative description of differences between similar samples is usually difficult. This article aims, by the use of statistical random walk in a generalized q-order dimensional space, at introducing a methodology to qualify the networked structures on the basis of exemplary textile samples. The presented results were obtained at 1-bit monochromatic maps obtained from optical microscopic pictures. Significant features of samples were represented by the obtained distributions of Hurst exponents and Shannon entropy calculations.

  20. Statistical characteristics, circulation regimes and unstable periodic orbits of a barotropic atmospheric model.

    PubMed

    Gritsun, A

    2013-05-28

    The theory of chaotic dynamical systems gives many tools that can be used in climate studies. The widely used ones are the Lyapunov exponents, the Kolmogorov entropy and the attractor dimension characterizing global quantities of a system. Another potentially useful tool from dynamical system theory arises from the fact that the local analysis of a system probability distribution function (PDF) can be accomplished by using a procedure that involves an expansion in terms of unstable periodic orbits (UPOs). The system measure (or its statistical characteristics) is approximated as a weighted sum over the orbits. The weights are inversely proportional to the orbit instability characteristics so that the least unstable orbits make larger contributions to the PDF. Consequently, one can expect some relationship between the least unstable orbits and the local maxima of the system PDF. As a result, the most probable system trajectories (or 'circulation regimes' in some sense) may be explained in terms of orbits. For the special classes of chaotic dynamical systems, there is a strict theory guaranteeing the accuracy of this approach. However, a typical atmospheric model may not qualify for these theorems. In our study, we will try to apply the idea of UPO expansion to the simple atmospheric system based on the barotropic vorticity equation of the sphere. We will check how well orbits approximate the system attractor, its statistical characteristics and PDF. The connection of the most probable states of the system with the least unstable periodic orbits will also be analysed. PMID:23588051

  1. The critical period hypothesis in second language acquisition: a statistical critique and a reanalysis.

    PubMed

    Vanhove, Jan

    2013-01-01

    In second language acquisition research, the critical period hypothesis (cph) holds that the function between learners' age and their susceptibility to second language input is non-linear. This paper revisits the indistinctness found in the literature with regard to this hypothesis's scope and predictions. Even when its scope is clearly delineated and its predictions are spelt out, however, empirical studies-with few exceptions-use analytical (statistical) tools that are irrelevant with respect to the predictions made. This paper discusses statistical fallacies common in cph research and illustrates an alternative analytical method (piecewise regression) by means of a reanalysis of two datasets from a 2010 paper purporting to have found cross-linguistic evidence in favour of the cph. This reanalysis reveals that the specific age patterns predicted by the cph are not cross-linguistically robust. Applying the principle of parsimony, it is concluded that age patterns in second language acquisition are not governed by a critical period. To conclude, this paper highlights the role of confirmation bias in the scientific enterprise and appeals to second language acquisition researchers to reanalyse their old datasets using the methods discussed in this paper. The data and R commands that were used for the reanalysis are provided as supplementary materials. PMID:23935947

  2. The Critical Period Hypothesis in Second Language Acquisition: A Statistical Critique and a Reanalysis

    PubMed Central

    Vanhove, Jan

    2013-01-01

    In second language acquisition research, the critical period hypothesis (cph) holds that the function between learners' age and their susceptibility to second language input is non-linear. This paper revisits the indistinctness found in the literature with regard to this hypothesis's scope and predictions. Even when its scope is clearly delineated and its predictions are spelt out, however, empirical studies–with few exceptions–use analytical (statistical) tools that are irrelevant with respect to the predictions made. This paper discusses statistical fallacies common in cph research and illustrates an alternative analytical method (piecewise regression) by means of a reanalysis of two datasets from a 2010 paper purporting to have found cross-linguistic evidence in favour of the cph. This reanalysis reveals that the specific age patterns predicted by the cph are not cross-linguistically robust. Applying the principle of parsimony, it is concluded that age patterns in second language acquisition are not governed by a critical period. To conclude, this paper highlights the role of confirmation bias in the scientific enterprise and appeals to second language acquisition researchers to reanalyse their old datasets using the methods discussed in this paper. The data and R commands that were used for the reanalysis are provided as supplementary materials. PMID:23935947

  3. Downscaling climate variability associated with quasi-periodic climate signals: A new statistical approach using MSSA

    NASA Astrophysics Data System (ADS)

    Cañón, Julio; Domínguez, Francina; Valdés, Juan B.

    2011-02-01

    SummaryA statistical method is introduced to downscale hydroclimatic variables while incorporating the variability associated with quasi-periodic global climate signals. The method extracts statistical information of distributed variables from historic time series available at high resolution and uses Multichannel Singular Spectrum Analysis (MSSA) to reconstruct, on a cell-by-cell basis, specific frequency signatures associated with both the variable at a coarse scale and the global climate signals. Historical information is divided in two sets: a reconstruction set to identify the dominant modes of variability of the series for each cell and a validation set to compare the downscaling relative to the observed patterns. After validation, the coarse projections from Global Climate Models (GCMs) are disaggregated to higher spatial resolutions by using an iterative gap-filling MSSA algorithm to downscale the projected values of the variable, using the distributed series statistics and the MSSA analysis. The method is data adaptive and useful for downscaling short-term forecasts as well as long-term climate projections. The method is applied to the downscaling of temperature and precipitation from observed records and GCM projections over a region located in the US Southwest, taking into account the seasonal variability associated with ENSO.

  4. A statistical model for the timing of earthquakes and volcanic eruptions influenced by periodic processes

    NASA Astrophysics Data System (ADS)

    Jupp, Tim E.; Pyle, David M.; Mason, Ben G.; Dade, W. Brian

    2004-02-01

    Evidence of nonuniformity in the rate of seismicity and volcanicity has been sought on a variety of timescales ranging from ˜12.4 hours (tidal) to 103-104 years (climatic), but the results are mixed. Here, we propose a simple conceptual model for the influence of periodic processes on the frequency of geophysical "failure events" such as earthquakes and volcanic eruptions. In our model a failure event occurs at a "failure time" tF = tI + tR which is controlled by an "initiation event" at the "initiation time" tI and by the "response time" of the system tR. We treat each of the initiation time, the response time, and the failure time as random variables. In physical terms, we define the initiation time to be the time at which a "load function" exceeds a "strength function," and we imagine that the response time tR corresponds to a physical process such as crack propagation or the movement of magma. Assuming that the magnitude and frequency of the periodic process are known, we calculate the statistical distribution of the initiation times on the assumption that the load and strength functions are otherwise linear in time. This allows the distribution of the failure times to be calculated if the distribution of the response times is known also. The quantitative predictions of this simple theory are compared with some examples of observed periodicity in seismic and volcanic activity at tidal and annual timescales.

  5. Mathematics and statistics research department. Progress report, period ending June 30, 1981

    SciTech Connect

    Lever, W.E.; Kane, V.E.; Scott, D.S.; Shepherd, D.E.

    1981-09-01

    This report is the twenty-fourth in the series of progress reports of the Mathematics and Statistics Research Department of the Computer Sciences Division, Union Carbide Corporation - Nuclear Division (UCC-ND). Part A records research progress in biometrics research, materials science applications, model evaluation, moving boundary problems, multivariate analysis, numerical linear algebra, risk analysis, and complementary areas. Collaboration and consulting with others throughout the UCC-ND complex are recorded in Part B. Included are sections on biology and health sciences, chemistry, energy, engineering, environmental sciences, health and safety research, materials sciences, safeguards, surveys, and uranium resource evaluation. Part C summarizes the various educational activities in which the staff was engaged. Part D lists the presentations of research results, and Part E records the staff's other professional activities during the report period.

  6. Load Balancing Using Time Series Analysis for Soft Real Time Systems with Statistically Periodic Loads

    NASA Technical Reports Server (NTRS)

    Hailperin, M.

    1993-01-01

    This thesis provides design and analysis of techniques for global load balancing on ensemble architectures running soft-real-time object-oriented applications with statistically periodic loads. It focuses on estimating the instantaneous average load over all the processing elements. The major contribution is the use of explicit stochastic process models for both the loading and the averaging itself. These models are exploited via statistical time-series analysis and Bayesian inference to provide improved average load estimates, and thus to facilitate global load balancing. This thesis explains the distributed algorithms used and provides some optimality results. It also describes the algorithms' implementation and gives performance results from simulation. These results show that the authors' techniques allow more accurate estimation of the global system loading, resulting in fewer object migrations than local methods. The authors' method is shown to provide superior performance, relative not only to static load-balancing schemes but also to many adaptive load-balancing methods. Results from a preliminary analysis of another system and from simulation with a synthetic load provide some evidence of more general applicability.

  7. An atomic force microscopy statistical analysis of laser-induced azo-polyimide periodic tridimensional nanogrooves.

    PubMed

    Stoica, Iuliana; Epure, Luiza; Sava, Ion; Damian, Victor; Hurduc, Nicolae

    2013-09-01

    The surface morphology of azo-polyimide films was investigated after 355 nm Nd: YAG laser irradiation with two different incident fluencies. Atomic force microscopy (AFM) was employed to correlate the laser-induced tridimensional nanogrooved surface relief with the incident fluence and the number of irradiation pulses. The height images revealed that the grooves depth increased even tens of times by increasing the incident fluence, using the same numbers of irradiation pulses. For low incident fluence, the films were uniformly patterned till 100 pulses of irradiation. Instead, when using higher fluence, after 15 pulses of irradiation the accuracy of the surface relief definition was reduced. This behavior could be explained by means of two different mechanisms, one that suppose the film photo-fluidization due to the cis-trans isomerization processes of the azo-groups and the second one responsible for the directional mass displacement. The dominant surface direction and parameters like isotropy, periodicity, and period were evaluated from the polar representation for texture analysis, revealing the appearance of ordered and directionated nanostructures for most of the experimental conditions. Also, the graphical studies of the functional volume parameters have evidenced the improvement of the relief structuration during surface nanostructuration. The correlation of these statistical texture parameters with the irradiation characteristics is important in controlling the alignment of either the liquid crystals or the cells/tissues on patterned azo-polyimide surfaces for optoelectronic devices and implantable biomaterials, respectively. PMID:23801415

  8. Clusters in the distribution of pulsars in period, pulse-width, and age. [statistical analysis/statistical distributions

    NASA Technical Reports Server (NTRS)

    Baker, K. B.; Sturrock, P. A.

    1975-01-01

    The question of whether pulsars form a single group or whether pulsars come in two or more different groups is discussed. It is proposed that such groups might be related to several factors such as the initial creation of the neutron star, or the orientation of the magnetic field axis with the spin axis. Various statistical models are examined.

  9. Conservation reserve program: Enrollment statistics for signup periods 1-12 and fiscal years 1986-1993. Statistical bulletin (Final)

    SciTech Connect

    Osborn, C.T.; Llacuna, F.; Linsenbigler, M.

    1995-11-01

    The U.S. Department of Agriculture (USDA) accepted about 33.9 million acres of cropland into the Conservation Reserve Program (CPR) during 1986-89. This acreage was enrolled in nine separate signups under authority of the Food Security Act of 1985. CRP enrollment was extended through 1995 with passage of the Food, Agriculture, Conservation, and Trade Act of 1990. Three signup periods (the 10th, 11th, and 12th) were held in 1991 and 1992. About 2.5 million additional acres were enrolled in these signup periods under significantly revised program rules. No funds were appropriated for additional signups in fiscal years 1993-95. This report presents tables covering all CRP cropland enrolled in signup periods 1-12 and CRP cropland newly retired for each of fiscal years 1986-93.

  10. Statistics of Long Period Gas Giant Planets in Known Planetary Systems

    NASA Astrophysics Data System (ADS)

    Bryan, Marta L.; Knutson, Heather A.; Howard, Andrew W.; Ngo, Henry; Batygin, Konstantin; Crepp, Justin R.; Fulton, B. J.; Hinkley, Sasha; Isaacson, Howard; Johnson, John A.; Marcy, Geoffry W.; Wright, Jason T.

    2016-04-01

    We conducted a Doppler survey at Keck combined with NIRC2 K-band adaptive optics (AO) imaging to search for massive, long-period companions to 123 known exoplanet systems with one or two planets detected using the radial velocity (RV) method. Our survey is sensitive to Jupiter-mass planets out to 20 au for a majority of stars in our sample, and we report the discovery of eight new long-period planets, in addition to 20 systems with statistically significant RV trends that indicate the presence of an outer companion beyond 5 au. We combine our RV observations with AO imaging to determine the range of allowed masses and orbital separations for these companions, and account for variations in our sensitivity to companions among stars in our sample. We estimate the total occurrence rate of companions in our sample to be 52 ± 5% over the range 1–20 MJup and 5–20 au. Our data also suggest a declining frequency for gas giant planets in these systems beyond 3–10 au, in contrast to earlier studies that found a rising frequency for giant planets in the range 0.01–3 au. This suggests either that the frequency of gas giant planets peaks between 3 and 10 au, or that outer companions in these systems have a different semi-major axis distribution than the overall population of gas giant planets. Our results also suggest that hot gas giants may be more likely to have an outer companion than cold gas giants. We find that planets with an outer companion have higher average eccentricities than their single counterparts, suggesting that dynamical interactions between planets may play an important role in these systems.

  11. Statistics

    Cancer.gov

    Links to sources of cancer-related statistics, including the Surveillance, Epidemiology and End Results (SEER) Program, SEER-Medicare datasets, cancer survivor prevalence data, and the Cancer Trends Progress Report.

  12. Statistical properties of quasi-periodic pulsations in white-light flares observed with Kepler

    NASA Astrophysics Data System (ADS)

    Pugh, C. E.; Armstrong, D. J.; Nakariakov, V. M.; Broomhall, A.-M.

    2016-07-01

    We embark on a study of quasi-periodic pulsations (QPPs) in the decay phase of white-light stellar flares observed by Kepler. Out of the 1439 flares on 216 different stars detected in the short-cadence data using an automated search, 56 flares are found to have pronounced QPP-like signatures in the light curve, of which 11 have stable decaying oscillations. No correlation is found between the QPP period and the stellar temperature, radius, rotation period and surface gravity, suggesting that the QPPs are independent of global stellar parameters. Hence they are likely to be the result of processes occurring in the local environment. There is also no significant correlation between the QPP period and flare energy, however there is evidence that the period scales with the QPP decay time for the Gaussian damping scenario, but not to a significant degree for the exponentially damped case. This same scaling has been observed for MHD oscillations on the Sun, suggesting that they could be the cause of the QPPs in those flares. Scaling laws of the flare energy are also investigated, supporting previous reports of a strong correlation between the flare energy and stellar temperature/radius. A negative correlation between the flare energy and stellar surface gravity is also found.

  13. Statistical Properties of Quasi-Periodic Pulsations in White-Light Flares Observed With Kepler

    NASA Astrophysics Data System (ADS)

    Pugh, C. E.; Armstrong, D. J.; Nakariakov, V. M.; Broomhall, A.-M.

    2016-04-01

    We embark on a study of quasi-periodic pulsations (QPPs) in the decay phase of white-light stellar flares observed by Kepler. Out of the 1439 flares on 216 different stars detected in the short-cadence data using an automated search, 56 flares are found to have pronounced QPP-like signatures in the light curve, of which 11 have stable decaying oscillations. No correlation is found between the QPP period and the stellar temperature, radius, rotation period and surface gravity, suggesting that the QPPs are independent of global stellar parameters. Hence they are likely to be the result of processes occurring in the local environment. There is also no significant correlation between the QPP period and flare energy, however there is evidence that the period scales with the QPP decay time for the Gaussian damping scenario, but not to a significant degree for the exponentially damped case. This same scaling has been observed for MHD oscillations on the Sun, suggesting that they could be the cause of the QPPs in those flares. Scaling laws of the flare energy are also investigated, supporting previous reports of a strong correlation between the flare energy and stellar temperature/radius. A negative correlation between the flare energy and stellar surface gravity is also found.

  14. The return period analysis of natural disasters with statistical modeling of bivariate joint probability distribution.

    PubMed

    Li, Ning; Liu, Xueqin; Xie, Wei; Wu, Jidong; Zhang, Peng

    2013-01-01

    New features of natural disasters have been observed over the last several years. The factors that influence the disasters' formation mechanisms, regularity of occurrence and main characteristics have been revealed to be more complicated and diverse in nature than previously thought. As the uncertainty involved increases, the variables need to be examined further. This article discusses the importance and the shortage of multivariate analysis of natural disasters and presents a method to estimate the joint probability of the return periods and perform a risk analysis. Severe dust storms from 1990 to 2008 in Inner Mongolia were used as a case study to test this new methodology, as they are normal and recurring climatic phenomena on Earth. Based on the 79 investigated events and according to the dust storm definition with bivariate, the joint probability distribution of severe dust storms was established using the observed data of maximum wind speed and duration. The joint return periods of severe dust storms were calculated, and the relevant risk was analyzed according to the joint probability. The copula function is able to simulate severe dust storm disasters accurately. The joint return periods generated are closer to those observed in reality than the univariate return periods and thus have more value in severe dust storm disaster mitigation, strategy making, program design, and improvement of risk management. This research may prove useful in risk-based decision making. The exploration of multivariate analysis methods can also lay the foundation for further applications in natural disaster risk analysis. PMID:22616629

  15. An integration of statistic method to track droughts periods induced by global change.

    NASA Astrophysics Data System (ADS)

    Djamel, Mimoun; Didier, Graillot

    2013-04-01

    During the last decades, droughts are occurring frequently in France, most notably in 1976, 1988, 1997 and 2003. This culminated in the severe drought of 2003 which affected mainly the south-east of Europe. Global climate models predict a prominent change in rainfall with wetter winters and drier summers over the medium latitude in the Northern Hemisphere. In France, regional climate models (ARPEGE) shows an increasing seasonal climatic variability with (a) hotter, drier summer and (b) an increase in the duration and severity of low-flow periods. The paper focuses on the temperate zone of the south-east of France on the catchment of the Ain river where water resources, consisting mainly of karstic and alluvial groundwater, are already a major concern today. This contribution tried to identify whether any trend in the annual and monthly series of rainfall already appears at the scale of this region and to obtain realistic previsions at 60 years. Two data sources have been used : (a) spatially interpolated historical data for the period 1970-2006 from the French weather service model SAFRAN (NCEP re-analysis for the MSLP field and the Meteo-France SAFRAN mesoscale analysis for the precipitation observations); and (b) the four SRES B2 scenarios namely Arpege_2, Arpege_1, Arpege_A2 and Arpege_B1 have been widely adopted as standard scenarios for the use in climate change impact studies. Scenario runs were taken over two time periods: a) 2010-2040 and b) 2041-2070. Drought characteristics over the study area were revealed by employing the Standardized Precipitation Index (SPI) in different time scales. Negative trends of the SPI drought index were recognized by using the Mann-Kendall non parametric test, which suggested that drought conditions were intensified through time. The trends observed in the 13 sub catchments of interest are consistent with those observed at a larger scale. The results indicated that the drought severity and duration will increase in the future

  16. Statistical study on magnetotail lobe waves with period 40 - 600 s observed by Cluster

    NASA Astrophysics Data System (ADS)

    Wang, Guoqiang; Zhang, Tielong; Volwerk, Martin

    2016-04-01

    Ultra low frequency (ULF) waves play an important role in energy transport and dissipation in the magnetosphere. In this paper, 263 waves with period 40 - 150 s and 161 waves with period 150 - 600 s in the Earth's magnetotail lobe have been studied by using Cluster data from years 2001 to 2009. Our findings are as follows: (1) 90% of the wave amplitudes with period 40 - 150 s are below ~0.25 nT for transverse components, and ~0.16 nT for compressional component; The amplitudes of longer period waves are somewhat larger; For waves with period 150 - 600 s, 90% of the wave amplitudes are below ~0.36 nT and ~0.39 nT for transverse and compressional components, respectively. (2) Waves within 40 - 150 s prefer to occur in the lobe region close to the plasma sheet, while waves within 150 - 600 s can be observed throughout the lobe region; (3) The amplitudes of lobe waves and AE index are weakly correlated; However, we find that amplitudes tend to be larger when the AE index is larger; (4) Amplitudes also tend to be larger when the solar wind velocity, the solar wind dynamic pressure or its variations (∆PSW) is larger; The correlation coefficient between amplitudes of waves within 150 - 600 s and ∆PSW is up to ~0.58. We suggest that both dynamic pressure in the plasma sheet boundary layer or plasma sheet (inner source) and solar wind conditions (outer source) can contribute to the generation of lobe ULF waves; Waves within 40 - 150 s are effected more by inner source; ∆PSW is more associated with compressional waves within 150 - 600 s than that within 40 - 150 s.

  17. Statistic analysis of annual total ozone extremes for the period 1964-1988

    NASA Technical Reports Server (NTRS)

    Krzyscin, Janusz W.

    1994-01-01

    Annual extremes of total column amount of ozone (in the period 1964-1988) from a network of 29 Dobson stations have been examined using the extreme value analysis. The extremes have been calculated as the highest deviation of daily mean total ozone from its long-term monthly mean, normalized by the monthly standard deviations. The extremes have been selected from the direct-Sun total ozone observations only. The extremes resulting from abrupt changes in ozone (day to day changes greater than 20 percent) have not been considered. The ordered extremes (maxima in ascending way, minima in descending way) have been fitted to one of three forms of the Fisher-Tippet extreme value distribution by the nonlinear least square method (Levenberg-Marguard method). We have found that the ordered extremes from a majority of Dobson stations lie close to Fisher-Tippet type III. The extreme value analysis of the composite annual extremes (combined from averages of the annual extremes selected at individual stations) has shown that the composite maxima are fitted by the Fisher-Tippet type III and the composite minima by the Fisher-Tippet type I. The difference between the Fisher-Tippet types of the composite extremes seems to be related to the ozone downward trend. Extreme value prognoses for the period 1964-2014 (derived from the data taken at: all analyzed stations, the North American, and the European stations) have revealed that the prognostic extremes are close to the largest annual extremes in the period 1964-1988 and there are only small regional differences in the prognoses.

  18. Statistics of Long-Period Gas Giant Planets in Known Planetary Systems

    NASA Astrophysics Data System (ADS)

    Levesque Bryan, Marta; Knutson, Heather; Howard, Andrew; Ngo, Henry; Batygin, Konstantin; Crepp, Justin; Fulton, Benjamin; Hinkley, Sasha; Isaacson, Howard T.; Johnson, John Asher; Marcy, Geoffrey W.; Wright, Jason

    2015-12-01

    We conducted a Doppler survey at Keck combined with NIRC2 K-band AO imaging to search for massive, long-period companions to 123 known exoplanet systems with one or two planets detected using the radial velocity (RV) method. Our survey is sensitive to Jupiter mass planets out to 20 AU for a majority of the stars in our sample, and we report the discovery of eight new long-period planets in addition to 20 RV trends at 3 sigma significance indicating the presence of an outer companion beyond 5 AU. We combined our RV observations with AO imaging to determine the range of allowed masses and orbital separations for these companions and fit this population with a power law in mass and semi-major axis. We estimate the total occurrence rate of companions in our sample, and find that hot and warm gas giants inside 1 AU are more likely to have an outer companion than cold gas giants. We also find that planets with an outer companion have higher than average eccentricities than their single counterparts, suggesting that dynamical interactions between planets may play an important role in these systems.

  19. Perinatal statistics of a 15-year period in the Central Region of Saudi Arabia

    PubMed Central

    Sobaih, Badr H; Al-Shebly, Mashael M.

    2013-01-01

    Perinatal statistics are one of the most essential outcome indicators used by many developed countries in order to evaluate perinatal services provided to newborns. In this retrospective study, we collected 15 years of perinatal data at King Khalid University Hospital in Riyadh, Saudi Arabia in order to determine stillbirth and other mortality rates in our institute and compare them with international figures. A total of 58,073 babies were evaluated. Data were collected from maternal and neonatal registry books and from perinatal mortality and morbidity meeting reports between 1994 and 2008. Data were entered and analyzed using Microsoft Office Excel 2007. The stillbirth rate was 11.7/1000, early neonatal death rate was 3.4/1000, perinatal mortality rate (PMR) was 14.9/1000, and corrected PMR was 11.9/1000. Our rates were not significantly different from those of North American and European ones. We noticed a dramatic reduction in the corrected PMR in the last 3 years of the study because of greater advancement in perinatal and neonatal care. Our mortality rates were comparable to the North American and European rates which may reflect the quality of perinatal care provided in our institute. PMID:27493354

  20. On the return period statistics of magnetic storms and their implications.

    NASA Astrophysics Data System (ADS)

    Freeman, M. P.; Horne, R. B.; Daws, M.; Wilson, P. S.

    2003-04-01

    Magnetic storms are globally coherent non-secular variations of the geomagnetic field that have been identified as a natural environmental hazard with adverse effects on radio communications, satellite operations, electrical power distribution, etc. Thus it is desirable to forecast the occurrence of magnetic storms to mitigate their impact. To this end, we have analysed the probability density function (PDF) of magnetic storm duration, non-storm duration, and waiting time between storm onsets, for two objective definitions of a magnetic storm based on historical precedent. In the first definition, a magnetic storm is defined as a classic extreme event - the interval for which a relevant geomagnetic measure (the -Dst index) is above a given threshold, c. The PDF of storm duration, non-storm duration, and waiting time between storm onsets are all found to be truncated power laws, independent of threshold. Thus, under this definition, magnetic storms have no characteristic duration or recurrence time between ˜ 1 h and ˜ 100 h. In the second definition, we show evidence that the extreme events of the first definition are part of a longer coherent structure in the time series such that a magnetic storm can alternatively be defined as the interval for which the -Dst index is above a given threshold b and the maximum -Dst is above a second, higher threshold c. Over a region of the two-threshold parameter space \\{b, c\\}, the PDF of waiting times between storm onsets in 3-year samples is found to be a random stationary (Poisson) process with a Poisson statistic that varies with the solar cycle, and the PDF of storm durations is peaked at 20-30 h. The analysis raises an interesting general question as to the occurrence properties of abstract extrema (e.g., gale force winds) compared to those of physical extreme events (e.g., hurricanes?). Moreover, an interesting similarity between the occurrence pattern of repeatable magnetic storms and of solar flares is noted.

  1. The quasi-periodical VLF/ELF emissions detected onboard the DEMETER spacecraft: statistical and theoretical analysis

    NASA Astrophysics Data System (ADS)

    Pasmanik, Dmitry; Hayosh, Mykhaylo; Demekhov, Andrei; Santolík, Ondřej; Nemec, František; Parrot, Michel

    2015-04-01

    We present a statistical study of the quasi-periodic (QP) ELF/VLF emissions measured by the DEMETER spacecraft. Events with modulation period larger than 10 s and frequency bandwidth more than 200 Hz were visually selected among the six year of measurements. Selected QP-emissions events occur mostly at frequencies from about 750 Hz to 2 kHz, but they may be observed at frequencies as low as 500 Hz and as high as 8 kHz. The statistical analysis clearly shows that QP events with larger modulation periods have lower frequency drift and smaller wave amplitude. Intense QP events have higher frequency drifts and larger values of the frequency bandwiths. Numerical simulation of the QP emissions based on the theoretical model of the flow cyclotron maser is performed. Calculations were made for wide range of plasma parameters (i.e. cold plasma density, L-shell, energetic electron flux and etc.) The numerical results are in good agreement with the observed relationship between different parameters of the QP emissions. The comparison between theoretical results and observations allow us to estimate the typical properties of the source of the QP emissions observed by the DEMETER satellite.

  2. Quantum paradoxes originating from the nonclassical statistics of physical properties related to each other by half-periodic transformations

    NASA Astrophysics Data System (ADS)

    Hofmann, Holger F.

    2015-06-01

    Quantum paradoxes show that quantum statistics can exceed the limits of positive joint probabilities for physical properties that cannot be measured jointly. It is therefore impossible to describe the relations between the different physical properties of a quantum system by assigning joint realities to their observable values. Instead, recent experimental results obtained by weak measurements suggest that nonclassical correlations could be expressed by complex valued quasiprobabilities, where the phases of the complex probabilities express the action of transformations between the noncommuting properties [H. F. Hofmann, New J. Phys. 13, 103009 (2011), 10.1088/1367-2630/13/10/103009]. In these relations, negative probabilities necessarily emerge whenever the physical properties involved are related to each other by half-periodic transformations, since such transformations are characterized by action phases of π in their complex probabilities. It is therefore possible to trace the failure of realist assumptions back to a fundamental and universally valid relation between statistics and dynamics that associates half-periodic transformations with negative probabilities.

  3. Detecting multiple periodicities in observational data with the multifrequency periodogram - I. Analytic assessment of the statistical significance

    NASA Astrophysics Data System (ADS)

    Baluev, Roman V.

    2013-11-01

    We consider the `multifrequency' periodogram, in which the putative signal is modelled as a sum of two or more sinusoidal harmonics with independent frequencies. It is useful in cases when the data may contain several periodic components, especially when their interaction with each other and with the data sampling patterns might produce misleading results. Although the multifrequency statistic itself was constructed earlier, for example by G. Foster in his CLEANest algorithm, its probabilistic properties (the detection significance levels) are still poorly known and much of what is deemed known is not rigorous. These detection levels are nonetheless important for data analysis. We argue that to prove the simultaneous existence of all n components revealed in a multiperiodic variation, it is mandatory to apply at least 2n - 1 significance tests, among which most involve various multifrequency statistics, and only n tests are single-frequency ones. The main result of this paper is an analytic estimation of the statistical significance of the frequency tuples that the multifrequency periodogram can reveal. Using the theory of extreme values of random fields (the generalized Rice method), we find a useful approximation to the relevant false alarm probability. For the double-frequency periodogram, this approximation is given by the elementary formula (π/16)W2e- zz2, where W denotes the normalized width of the settled frequency range, and z is the observed periodogram maximum. We carried out intensive Monte Carlo simulations to show that the practical quality of this approximation is satisfactory. A similar analytic expression for the general multifrequency periodogram is also given, although with less numerical verification.

  4. Statistical learning and the critical period: how a continuous learning mechanism can give rise to discontinuous learning.

    PubMed

    Thiessen, Erik D; Girard, Sandrine; Erickson, Lucy C

    2016-07-01

    Infants and children are generally more successful than adults in learning novel languages, a phenomenon referred to as a critical or sensitive period for language acquisition. One explanation for this critical period is the idea that children have access to a set of language learning processes or mechanisms unavailable to adults. From this perspective, developmental change is explained in terms of a discontinuity of learning processes. We suggest that this is not the only possible explanation for developmental change in language learning outcomes. Instead, we propose that the mechanisms underlying language acquisition (in particular, we highlight statistical learning) are largely continuous across the lifespan. From this perspective, developmental change is explained in terms of experience, differences in the input with age, and maturational changes in the cognitive architecture supporting learning, even while the learning process itself operates continuously across developmental time. WIREs Cogn Sci 2016, 7:276-288. doi: 10.1002/wcs.1394 For further resources related to this article, please visit the WIREs website. PMID:27239798

  5. Statistical analysis and multi-instrument overview of the quasi-periodic 1-hour pulsations in Saturn's outer magnetosphere

    NASA Astrophysics Data System (ADS)

    Palmaerts, B.; Roussos, E.; Krupp, N.; Kurth, W. S.; Mitchell, D. G.; Dougherty, M. K.

    2015-10-01

    The in-situ exploration of the magnetospheres of Jupiter and Saturn has revealed different periodic processes. In particular, in the Saturnian magnetosphere, several studies have reported pulsations in the outer magnetosphere with a periodicity of about 1 hour in the measurements of charged particle fluxes, plasma wave, magnetic field strength and auroral emissions brightness. The Low- Energy Magnetospheric Measurement System detector of the Magnetospheric Imaging Instrument (MIMI/LEMMS) on board Cassini regularly detects 1-hour quasi-periodic enhancements in the intensities of electrons with an energy range from a hundred keV to several MeV. We extend an earlier survey of these relativistic electron injections, using 10 years of LEMMS observations in addition to context measurements by several other Cassini magnetospheric experiments. During this period, we identified 720 pulsed events in the outer magnetosphere over a wide range of latitudes and local times, revealing that this phenomenon is common and frequent in Saturn's magnetosphere. However, the distribution of the injection events presents a strong local time asymmetry with ten times more events in the duskside than in the dawnside. In addition to the study of their topology, we present a first statistical analysis of these pulsed events to investigate their properties. This analysis reveals that the mean interpulse period is 68 ± 10 minutes and that the events are made up of less than 9 pulses in general, but they can include up to 19 pulses. The most common shape of these pulses is a fast rise followed by a slow decay. Moreover, the ratio between the rise rate and the decay rate increases with the energy. We have also investigated the signatures of each electron injection event in the observations acquired by the Radio and Plasma Wave Science (RPWS) instrument and the magnetometer (MAG). Correlated pulsed signatures are observed in the plasma wave emissions, especially in the auroral hiss, for 12% of the

  6. Planetary populations in the mass-period diagram: A statistical treatment of exoplanet formation and the role of planet traps

    SciTech Connect

    Hasegawa, Yasuhiro; Pudritz, Ralph E. E-mail: pudritz@physics.mcmaster.ca

    2013-11-20

    The rapid growth of observed exoplanets has revealed the existence of several distinct planetary populations in the mass-period diagram. Two of the most surprising are (1) the concentration of gas giants around 1 AU and (2) the accumulation of a large number of low-mass planets with tight orbits, also known as super-Earths and hot Neptunes. We have recently shown that protoplanetary disks have multiple planet traps that are characterized by orbital radii in the disks and halt rapid type I planetary migration. By coupling planet traps with the standard core accretion scenario, we showed that one can account for the positions of planets in the mass-period diagram. In this paper, we demonstrate quantitatively that most gas giants formed at planet traps tend to end up around 1 AU, with most of these being contributed by dead zones and ice lines. We also show that a large fraction of super-Earths and hot Neptunes are formed as 'failed' cores of gas giants—this population being constituted by comparable contributions from dead zone and heat transition traps. Our results are based on the evolution of forming planets in an ensemble of disks where we vary only the lifetimes of disks and their mass accretion rates onto the host star. We show that a statistical treatment of the evolution of a large population of planetary cores caught in planet traps accounts for the existence of three distinct exoplanetary populations—the hot Jupiters, the more massive planets around r = 1 AU, and the short-period super-Earths and hot Neptunes. There are very few populations that feed into the large orbital radii characteristic of the imaged Jovian planet, which agrees with recent surveys. Finally, we find that low-mass planets in tight orbits become the dominant planetary population for low-mass stars (M {sub *} ≤ 0.7 M {sub ☉}).

  7. Statistical analysis and multi-instrument overview of the quasi-periodic 1-hour pulsations in Saturn's outer magnetosphere

    NASA Astrophysics Data System (ADS)

    Palmaerts, B.; Roussos, E.; Krupp, N.; Kurth, W. S.; Mitchell, D. G.; Yates, J. N.

    2016-06-01

    The in-situ exploration of the magnetospheres of Jupiter and Saturn has revealed different periodic processes. In particular, in the Saturnian magnetosphere, several studies have reported pulsations in the outer magnetosphere with a periodicity of about 1 h in the measurements of charged particle fluxes, plasma wave, magnetic field strength and auroral emissions brightness. The Low-Energy Magnetospheric Measurement System detector of the Magnetospheric Imaging Instrument (MIMI/LEMMS) on board Cassini regularly detects 1-hour quasi-periodic enhancements in the intensities of electrons with an energy range from a hundred keV to several MeV. We extend an earlier survey of these relativistic electron injections using 10 years of LEMMS observations in addition to context measurements by several other Cassini magnetospheric experiments. The one-year extension of the data and a different method of detection of the injections do not lead to a discrepancy with the results of the previous survey, indicating an absence of a long-term temporal evolution of this phenomenon. We identified 720 pulsed events in the outer magnetosphere over a wide range of latitudes and local times, revealing that this phenomenon is common and frequent in Saturn's magnetosphere. However, the distribution of the injection events presents a strong local time asymmetry with ten times more events in the duskside than in the dawnside. In addition to the study of their topology, we present a first statistical analysis of the pulsed events properties. The morphology of the pulsations shows a weak local time dependence which could imply a high-latitude acceleration source. We provide some clues that the electron population associated with this pulsed phenomenon is distinct from the field-aligned electron beams previously observed in Saturn's magnetosphere, but both populations can be mixed. We have also investigated the signatures of each electron injection event in the observations acquired by the Radio

  8. Statistical methods for detecting and comparing periodic data and their application to the nycthemeral rhythm of bodily harm: A population based study

    PubMed Central

    2010-01-01

    Background Animals, including humans, exhibit a variety of biological rhythms. This article describes a method for the detection and simultaneous comparison of multiple nycthemeral rhythms. Methods A statistical method for detecting periodic patterns in time-related data via harmonic regression is described. The method is particularly capable of detecting nycthemeral rhythms in medical data. Additionally a method for simultaneously comparing two or more periodic patterns is described, which derives from the analysis of variance (ANOVA). This method statistically confirms or rejects equality of periodic patterns. Mathematical descriptions of the detecting method and the comparing method are displayed. Results Nycthemeral rhythms of incidents of bodily harm in Middle Franconia are analyzed in order to demonstrate both methods. Every day of the week showed a significant nycthemeral rhythm of bodily harm. These seven patterns of the week were compared to each other revealing only two different nycthemeral rhythms, one for Friday and Saturday and one for the other weekdays. PMID:21059197

  9. The joint return period analysis of natural disasters based on monitoring and statistical modeling of multidimensional hazard factors.

    PubMed

    Liu, Xueqin; Li, Ning; Yuan, Shuai; Xu, Ning; Shi, Wenqin; Chen, Weibin

    2015-12-15

    As a random event, a natural disaster has the complex occurrence mechanism. The comprehensive analysis of multiple hazard factors is important in disaster risk assessment. In order to improve the accuracy of risk analysis and forecasting, the formation mechanism of a disaster should be considered in the analysis and calculation of multi-factors. Based on the consideration of the importance and deficiencies of multivariate analysis of dust storm disasters, 91 severe dust storm disasters in Inner Mongolia from 1990 to 2013 were selected as study cases in the paper. Main hazard factors from 500-hPa atmospheric circulation system, near-surface meteorological system, and underlying surface conditions were selected to simulate and calculate the multidimensional joint return periods. After comparing the simulation results with actual dust storm events in 54years, we found that the two-dimensional Frank Copula function showed the better fitting results at the lower tail of hazard factors and that three-dimensional Frank Copula function displayed the better fitting results at the middle and upper tails of hazard factors. However, for dust storm disasters with the short return period, three-dimensional joint return period simulation shows no obvious advantage. If the return period is longer than 10years, it shows significant advantages in extreme value fitting. Therefore, we suggest the multivariate analysis method may be adopted in forecasting and risk analysis of serious disasters with the longer return period, such as earthquake and tsunami. Furthermore, the exploration of this method laid the foundation for the prediction and warning of other nature disasters. PMID:26327640

  10. Monitoring Radiofrequency Ablation Using Ultrasound Envelope Statistics and Shear Wave Elastography in the Periablation Period: An In Vitro Feasibility Study.

    PubMed

    Tsui, Po-Hsiang; Wang, Chiao-Yin; Zhou, Zhuhuang; Wan, Yung-Liang

    2016-01-01

    Radiofrequency ablation (RFA) is a minimally invasive method for treating tumors. Shear wave elastography (SWE) has been widely applied in evaluating tissue stiffness and final ablation size after RFA. However, the usefulness of periablation SWE imaging in assessing RFA remains unclear. Therefore, this study investigated the correlation between periablation SWE imaging and final ablation size. An in vitro porcine liver model was used for experimental validation (n = 36). During RFA with a power of 50 W, SWE images were collected using a clinical ultrasound system. To evaluate the effects of tissue temperature and gas bubbles during RFA, changes in the ablation temperature were recorded, and image echo patterns were measured using B-mode and ultrasound statistical parametric images. After RFA, the gross pathology of each tissue sample was compared with the region of change in the corresponding periablation SWE image. The experimental results showed that the tissue temperature at the ablation site varied between 70°C and 100°C. Hyperechoic regions and changes were observed in the echo amplitude distribution induced by gas bubbles. Under this condition, the confounding effects (including the temperature increase, tissue stiffness increase, and presence of gas bubbles) resulted in artifacts in the periablation SWE images, and the corresponding region correlated with the estimated final ablation size obtained from the gross pathology (r = 0.8). The findings confirm the feasibility of using periablation SWE imaging in assessing RFA. PMID:27603012

  11. Climate change scenarios of temperature and precipitation over five Italian regions for the period 2021-2050 obtained by statistical downscaling models

    NASA Astrophysics Data System (ADS)

    Tomozeiu, R.; Tomei, F.; Villani, G.; Pasqui, M.

    2010-09-01

    Climate change scenarios of seasonal maximum, minimum temperature and precipitation in five Italian regions, over the period 2021-2050 against 1961-1990 are assessed. The regions selected by the AGROSCENARI project are important from the local agricultural practises and are situated as follows: in the Northern Italy - Po valley and hilly area of Faenza; in Central part of Italy- Marche, Beneventano and Destra Sele, and in Sardinia Island - Oristano. A statistical downscaling technique applied to the ENSEMBLES global climate simulations, A1B scenario, is used to reach this objective. The method consists of a multivariate regression, based on Canonical Correlation Analysis, using as possible predictors mean sea level pressure, geopotential height at 500hPa and temperature at 850 hPa. The observational data set (predictands) for the selected regions is composed by a reconstruction of minimum, maximum temperature and precipitation daily data on a regular grid with a spatial resolution of 35 km, for 1951-2009 period (managed by the Meteorological and Climatological research unit for agriculture - Agricultural Research Council, CRA - CMA). First, a set-up of statistical model has been made using predictors from ERA40 reanalysis and the seasonal indices of temperature and precipitation from local scale, 1958-2002 period. Then, the statistical downscaling model has been applied to the predictors derived from the ENSEMBLES global climate models, A1B scenario, in order to obtain climate change scenario of temperature and precipitation at local scale, 2021-2050 period. The projections show that increases could be expected to occur under scenario conditions in all seasons, in both minimum and maximum temperature. The magnitude of changes is more intense during summer when the changes could reach values around 2°C for minimum and maximum temperature. In the case of precipitation, the pattern of changes is more complex, different from season to season and over the regions, a

  12. 50-Minute Experiment: Soil Analysis for High School Chemistry Students.

    ERIC Educational Resources Information Center

    Baruch, Gerard, Ed.; And Others

    1980-01-01

    Lists equipment and materials needed and procedures for analyzing soil, in which secondary school students experience practical applications to acid-base reactions, pH, oxidation-reduction, precipitation and solubility. (CS)

  13. Sensing propagation events and fade statistics at C-band for two over-water, line-of-sight propagation paths over a one year period

    NASA Technical Reports Server (NTRS)

    Goldhirsh, Julius; Dockery, G. Daniel; Musiani, Bert H.

    1992-01-01

    We examine signal fading statistics over a year period corresponding to two over-water, line-of-site, propagation links in the mid-Atlantic coast of the US. These links are comprised of a transmitter on a tower at Parramore Island, VA operating at 4.7 GHz sending simultaneous cw signals to two receiver systems located on a lighthouse and a lookout tower on Assateague Beach, VA at distances of 44 and 39 km, respectively. The receiving sites are separated by approximately 5 km. Cumulative fade distributions corresponding to yearly, monthly, and diurnal time scales were derived. Fade duration statistics correspond to sustained attenuation events were also derived. These events, which were arbitrarily defined as having fades relative to free space powers in excess of 20 dB for durations of two hours or more, are believed to be generally due to subrefraction. Analysis of synoptic weather conditions and nearby rawindsonde data during two sustained deep fading periods showed atmospheric conditions consistent with extreme subrefraction, where the refractivity-height profile had a positive lapse rate. The efficacy of employing the links as indicators of real time conditions of atmospheric propagation was also demonstrated by a telephone call-up procedure which enabled displays of time series of the fading at remote locations to be generated.

  14. Cloud fraction statistics in the baltic sea area over a period of ten years determined from Meteosat IR data for validating the climate model BALTIMOS

    NASA Astrophysics Data System (ADS)

    Reuter, M.; Fischer, J.

    2003-04-01

    In the framework of the DEKLIM (German Climate Research Programme) project BALTIMOS (BALTEX-Integral Model System) an algorithm for cloud detection using Meteosat thermal infrared data has been developed. The derived cloud mask was converted in fractional cloud cover of a climate model grid. From these data several statistical quantities have been derived, desigened to validate according climate model parameters of the regional model BALTIMOS (1/6°) driven by reanalyses. The analyzed region covers the whole baltic area, investigating a period of 10 years. The underlying data basis consists of hourly Meteosat thermal infrared, water vapour and visible data in the period from January 1992 to December 2001. Referring to the determination of the cloud mask, a mono spectral method for the Meteosat thermal infrared channel was developed. This method allows a uniform detection quality without discontinuities between day and night. It is based on a recursive algorithm, determining an assumed clear sky brightness temperature for each pixel, that is compared to the actual measurement. Comparisons with one year synoptical observations from 819 stations all over the baltic region has approved the efficiency and quality of the developed method. The detection certainty was 87% for cloud covered and 83% for cloud free cases, while 11% of all data have been classified as undecided. Several statistical quantities of the fractional cloud cover, like the mean diurnal cycles depending on the selected region, the anual cycles depending on the selected daytime or the moving average of the cloud coverage for the whole region over the period of 10 years have already been calculated.

  15. Statistical study of the night-time F-layer dynamics at the magnetic equator in West Africa during the solar minimum period 1995-1997

    NASA Astrophysics Data System (ADS)

    Tanoh, K. S.; Adohi, B. J.-P.; Coulibaly, I. S.; Amory-Mazaudier, C.; Kobea, A. T.; Assamoi, P.

    2015-01-01

    In this paper, we report on the night-time equatorial F-layer height behaviour at Korhogo (9.2° N, 5° W; 2.4° S dip lat), Ivory Coast, in the West African sector during the solar minimum period 1995-1997. The data were collected from quarter-hourly ionograms of an Ionospheric Prediction Service (IPS) 42-type vertical sounder. The main focus of this work was to study the seasonal changes in the F-layer height and to clarify the equinox transition process recently evidenced at Korhogo during 1995, the year of declining solar flux activity. The F-layer height was found to vary strongly with time, with up to three main phases. The night-to-night variability of these morphological phases was then analysed. The early post-sunset slow rise, commonly associated with rapid chemical recombination processes in the bottom part of the F layer, remained featureless and was observed regardless of the date. By contrast, the following event, either presented like the post-sunset height peak associated with the evening E × B drift, or was delayed to the midnight sector, thus involving another mechanism. The statistical analysis of the occurrence of these events throughout the solar minimum period 1995-1997 revealed two main F-layer height patterns, each characteristic of a specific season. The one with the post-sunset height peak was associated with the northern winter period, whereas the other, with the midnight height peak, characterized the northern summer period. The transition process from one pattern to the other took place during the equinox periods and was found to last only a few weeks. We discuss these results in the light of earlier works.

  16. Determination of snow avalanche return periods using a tree-ring based reconstruction in the French Alps: cross validation with the predictions of a statistical-dynamical model

    NASA Astrophysics Data System (ADS)

    Schläppy, Romain; Eckert, Nicolas; Jomelli, Vincent; Grancher, Delphine; Brunstein, Daniel; Stoffel, Markus; Naaim, Mohamed

    2013-04-01

    Documenting past avalanche activity represents an indispensable step in avalanche hazard assessment. Nevertheless, (i) archival records of past avalanche events do not normally yield data with satisfying spatial and temporal resolution and (ii) precision concerning runout distance is generally poorly defined. In addition, historic documentation is most often (iii) biased toward events that caused damage to structure or loss of life on the one hand and (iv) undersampled in unpopulated areas on the other hand. On forested paths dendrogeomorphology has been demonstrated to represent a powerful tool to reconstruct past activity of avalanches with annual resolution and for periods covering the past decades to centuries. This method is based on the fact that living trees may be affected by snow avalanches during their flow and deposition phases. Affected trees will react upon these disturbances with a certain growth response. An analysis of the responses recorded in tree rings coupled with an evaluation of the position of reacting trees within the path allows the dendrogeomorphic expert to identify past snow avalanche events and deduced their minimum runout distance. The objective of the work presented here is firstly to dendrochronogically -reconstruct snow avalanche activity in the Château Jouan path located near Montgenèvre in the French Alps. Minimal runout distances are then determined for each reconstructed event by considering the point of further reach along the topographic profile. Related empirical return intervals are evaluated, combining the extent of each event with the average local frequency of the dendrological record. In a second step, the runout distance distribution derived from dendrochronological reconstruction is compared to the one derived from historical archives and to high return period avalanches predicted by an up-to-date locally calibrated statistical-numerical model. It appears that dendrochronological reconstructions correspond mostly to

  17. Causes of death among detainees: a statistical study on the casework of the Forensic Medicine Institute in Cluj-Napoca during the period 2000–2014

    PubMed Central

    GHERMAN, CRISTIAN; CHIROBAN, OVIDIU

    2015-01-01

    Background and aims The detainees’ right to healthcare is granted by laws, in accordance with EU directives and recommendations to which our country has consented. Prison population is a particularly vulnerable and marginalized group characterized by mortality rates different from the general population. This study aims at providing a picture of the causes of death, quality of healthcare and measures needed to reduce the number of in-prison deaths, including legal medicine expertise in view of sentence postponement/interruption. Methods The present paper is based on the statistical analysis of in-prison deaths casework recorded at the Forensic Medicine Institute of Cluj-Napoca and provided by territorially subordinated counties forensic services. The data collected cover over 15 years (2000–2014), a period long enough for significant retrospective statistical analysis. Results The total number of deaths among the inmates was 113, the majority of male sex (110). Distribution by age groups shows a greater incidence among inmates aged 50 to 59 years (32 cases, 28.31%), followed by those in their 40s’ (30 cases, 26.54%) and 30s’ (25 cases, 22.12%). The most frequent pathological causes of death were cardiovascular (53 cases) followed by tumors (26 cases) and infectious diseases. A significant number of deaths were due to violent causes (14 cases-12,38%). Conclusions Special problems are raised by the high number of deaths among prisoners, especially at a young age, while the high frequency of violent deaths from self- or non-self-inflicted traumatic causes requires supervision, monitoring and continuous analysis. Despite recent improvements, healthcare in prisons still poses some problems, mainly regarding diagnosis and treatment of heart diseases, neurosurgery and cancer. PMID:26609263

  18. Statistical physics of earthquakes: Comparison of distribution exponents for source area and potential energy and the dynamic emergence of log-periodic energy quanta

    NASA Astrophysics Data System (ADS)

    Main, Ian G.; O'Brien, Gareth; Henderson, Jeremy R.

    2000-03-01

    We investigate the relationship between the size distribution of earthquake rupture area and the underlying elastic potential energy distribution in a cellular automaton model for earthquake dynamics. The frequency-rupture area distribution has the form n(S) ˜Sτ exp (-S/So) and the system potential energy distribution from the elastic Hamiltonian has the form n(E) ˜Ev exp (-E/θ), both gamma distributions. Here n(S) reduces to the Gutenberg-Richter frequency-magnitude law, with slope b ˜τ, in the limit that the correlation length ξ, related to the characteristic source size So, tends to infinity. The form of the energy distribution is consistent with a statistical mechanical model with l degrees of freedom, where v = (l-2)/2 and θ is proportional to the mean energy per site ? . We examine the effect of the local energy conservation factor β and the degree of material heterogeneity (quenched disorder) on the distribution parameters, which vary systematically with the controlling variables. The inferred correlation length increases systematically with increasing material homogeneity and with increasing β. The thermal parameter θ varies systematically between the leaf springs and the connecting springs, and is proportional to ? as predicted. For heterogeneous faults, τ ˜1 stays relatively constant, consistent with field observation, and S0 increases with increasing β or decreasing heterogeneity. In contrast, smooth faults produce a systematic decrease in τ with respect to β and So remains relatively constant. For high β approximately log-periodic quanta emerge spontaneously from the dynamics in the form of modulations on the energy distribution. The output energy for both types of fault shows a transition from strongly quasi-periodic temporal fluctuations for strong dissipation, to more chaotic fluctuations for more conservative models. Only strongly heterogeneous faults show the small fluctuations in energy strictly required by models of self

  19. Statistically-averaged rate equations for intense nonneutral beam propagation through a periodic solenoidal focusing field based on the nonlinear Vlasov-Maxwell equations

    SciTech Connect

    Davidson, R.C.; Lee, W.W.; Stoltz, P.

    1997-08-01

    This paper presents a detailed formulation and analysis of the rate equations for statistically-averaged quantities for an intense nonneutral beam propagating through a periodic solenoidal focusing field B{sup sol}(x). The analysis is based on the nonlinear Vlasov-Maxwell equations in the electrostatic approximation, assuming a thin beam with characteristic beam radius r{sub b} {much_lt} S. The results are applied to investigate the nonlinear evolution of the generalized entropy, mean canonical angular momentum {l_angle}P{sub {theta}}{r_angle}, center-of-mass motion for {l_angle}X{r_angle} and {l_angle}Y{r_angle}, mean kinetic energy (1/2) {l_angle}X{sup {prime}2} + Y{sup {prime}2}{r_angle}, mean-square beam radius {l_angle}X{sup 2} + Y{sup 2}{r_angle}, and coupled rate equations for the unnormalized transverse emittance {epsilon}(s) and root-mean-square beam radius R{sub b}(s) = {l_angle}X{sup 2} + Y{sup 2}{r_angle}{sup 1/2}. Global energy balance is discussed, and the coupled rate equations for {epsilon}(s) and R{sub b}(s) are examined for the class of axisymmetric beam distributions F{sub b}.

  20. Analysis of bending wave transmission using beam tracing with advanced statistical energy analysis for periodic box-like structures affected by spatial filtering

    NASA Astrophysics Data System (ADS)

    Wilson, D.; Hopkins, C.

    2015-04-01

    For bending wave transmission across periodic box-like arrangements of plates, the effects of spatial filtering can be significant and this needs to be considered in the choice of prediction model. This paper investigates the errors that can occur with Statistical Energy Analysis (SEA) and the potential of using Advanced SEA (ASEA) to improve predictions. The focus is on the low- and mid-frequency range where plates only support local modes with low mode counts and the in situ modal overlap is relatively high. To increase the computational efficiency when using ASEA on large systems, a beam tracing method is introduced which groups together all rays with the same heading into a single beam. Based on a diffuse field on the source plate, numerical experiments are used to determine the angular distribution of incident power on receiver plate edges on linear and cuboid box-like structures. These show that on receiver plates which do not share a boundary with the source plate, the angular distribution on the receiver plate boundaries differs significantly from a diffuse field. SEA and ASEA predictions are assessed through comparison with finite element models. With rain-on-the-roof excitation on the source plate, the results show that compared to SEA, ASEA provides significantly better estimates of the receiver plate energy, but only where there are at least one or two bending modes in each one-third octave band. Whilst ASEA provides better accuracy than SEA, discrepancies still exist which become more apparent when the direct propagation path crosses more than three nominally identical structural junctions.

  1. An analysis of the AVE-SESAME I period using statistical structure and correlation functions. [Atmospheric Variability Experiment-Severe Environmental Storm and Mesoscale Experiment

    NASA Technical Reports Server (NTRS)

    Fuelberg, H. E.; Meyer, P. J.

    1984-01-01

    Structure and correlation functions are used to describe atmospheric variability during the 10-11 April day of AVE-SESAME 1979 that coincided with the Red River Valley tornado outbreak. The special mesoscale rawinsonde data are employed in calculations involving temperature, geopotential height, horizontal wind speed and mixing ratio. Functional analyses are performed in both the lower and upper troposphere for the composite 24 h experiment period and at individual 3 h observation times. Results show that mesoscale features are prominent during the composite period. Fields of mixing ratio and horizontal wind speed exhibit the greatest amounts of small-scale variance, whereas temperature and geopotential height contain the least. Results for the nine individual times show that small-scale variance is greatest during the convective outbreak. The functions also are used to estimate random errors in the rawinsonde data. Finally, sensitivity analyses are presented to quantify confidence limits of the structure functions.

  2. Cosmic statistics of statistics

    NASA Astrophysics Data System (ADS)

    Szapudi, István; Colombi, Stéphane; Bernardeau, Francis

    1999-12-01

    The errors on statistics measured in finite galaxy catalogues are exhaustively investigated. The theory of errors on factorial moments by Szapudi & Colombi is applied to cumulants via a series expansion method. All results are subsequently extended to the weakly non-linear regime. Together with previous investigations this yields an analytic theory of the errors for moments and connected moments of counts in cells from highly non-linear to weakly non-linear scales. For non-linear functions of unbiased estimators, such as the cumulants, the phenomenon of cosmic bias is identified and computed. Since it is subdued by the cosmic errors in the range of applicability of the theory, correction for it is inconsequential. In addition, the method of Colombi, Szapudi & Szalay concerning sampling effects is generalized, adapting the theory for inhomogeneous galaxy catalogues. While previous work focused on the variance only, the present article calculates the cross-correlations between moments and connected moments as well for a statistically complete description. The final analytic formulae representing the full theory are explicit but somewhat complicated. Therefore we have made available a fortran program capable of calculating the described quantities numerically (for further details e-mail SC at colombi@iap.fr). An important special case is the evaluation of the errors on the two-point correlation function, for which this should be more accurate than any method put forward previously. This tool will be immensely useful in the future for assessing the precision of measurements from existing catalogues, as well as aiding the design of new galaxy surveys. To illustrate the applicability of the results and to explore the numerical aspects of the theory qualitatively and quantitatively, the errors and cross-correlations are predicted under a wide range of assumptions for the future Sloan Digital Sky Survey. The principal results concerning the cumulants ξ, Q3 and Q4 is that

  3. Problem Periods

    MedlinePlus

    ... gov/ Home Body Getting your period Problem periods Problem periods It’s common to have cramps or feel ... doctor Some common period problems Signs of period problems top One way to know if you may ...

  4. Descriptive statistics.

    PubMed

    Shi, Runhua; McLarty, Jerry W

    2009-10-01

    In this article, we introduced basic concepts of statistics, type of distributions, and descriptive statistics. A few examples were also provided. The basic concepts presented herein are only a fraction of the concepts related to descriptive statistics. Also, there are many commonly used distributions not presented herein, such as Poisson distributions for rare events and exponential distributions, F distributions, and logistic distributions. More information can be found in many statistics books and publications. PMID:19891281

  5. Statistical Diversions

    ERIC Educational Resources Information Center

    Petocz, Peter; Sowey, Eric

    2008-01-01

    As a branch of knowledge, Statistics is ubiquitous and its applications can be found in (almost) every field of human endeavour. In this article, the authors track down the possible source of the link between the "Siren song" and applications of Statistics. Answers to their previous five questions and five new questions on Statistics are presented.

  6. Statistical Software.

    ERIC Educational Resources Information Center

    Callamaras, Peter

    1983-01-01

    This buyer's guide to seven major types of statistics software packages for microcomputers reviews Edu-Ware Statistics 3.0; Financial Planning; Speed Stat; Statistics with DAISY; Human Systems Dynamics package of Stats Plus, ANOVA II, and REGRESS II; Maxistat; and Moore-Barnes' MBC Test Construction and MBC Correlation. (MBR)

  7. Bayesian Statistics.

    ERIC Educational Resources Information Center

    Meyer, Donald L.

    Bayesian statistical methodology and its possible uses in the behavioral sciences are discussed in relation to the solution of problems in both the use and teaching of fundamental statistical methods, including confidence intervals, significance tests, and sampling. The Bayesian model explains these statistical methods and offers a consistent…

  8. High-Resolution Dynamical Downscaling of ERA-Interim Using the WRF Regional Climate Model for the Area of Poland. Part 1: Model Configuration and Statistical Evaluation for the 1981-2010 Period

    NASA Astrophysics Data System (ADS)

    Kryza, Maciej; Wałaszek, Kinga; Ojrzyńska, Hanna; Szymanowski, Mariusz; Werner, Małgorzata; Dore, Anthony J.

    2016-03-01

    In this work, we present the results of high-resolution dynamical downscaling of air temperature, relative humidity, wind speed and direction, for the area of Poland, with the Weather Research and Forecasting (WRF) model. The model is configured using three nested domains, with spatial resolution of 45 km × 45 km, 15 km × 15 km and 5 km × 5 km. The ERA-Interim database is used for boundary conditions. The results are evaluated by comparison with station measurements for the period 1981-2010. The model is capable of reproducing the main climatological features of the study area. The results are in very close agreement with the measurements, especially for the air temperature. For all four meteorological variables, the model performance captures seasonal and daily cycles. For the air temperature and winter season, the model underestimates the measurements. For summer, the model shows higher values, compared with the measurements. The opposite is the case for relative humidity. There is a strong diurnal pattern in mean error, which changes seasonally. The agreement with the measurements is worse for the seashore and mountain areas, which suggests that the 5 km × 5 km grid might still have an insufficient spatial resolution. There is no statistically significant temporal trend in the model performance. The larger year-to-year changes in the model performance, e.g. for the years 1982 and 2010 for the air temperature should therefore be linked with the natural variability of meteorological conditions.

  9. Statistical databases

    SciTech Connect

    Kogalovskii, M.R.

    1995-03-01

    This paper presents a review of problems related to statistical database systems, which are wide-spread in various fields of activity. Statistical databases (SDB) are referred to as databases that consist of data and are used for statistical analysis. Topics under consideration are: SDB peculiarities, properties of data models adequate for SDB requirements, metadata functions, null-value problems, SDB compromise protection problems, stored data compression techniques, and statistical data representation means. Also examined is whether the present Database Management Systems (DBMS) satisfy the SDB requirements. Some actual research directions in SDB systems are considered.

  10. Morbidity statistics

    PubMed Central

    Smith, Alwyn

    1969-01-01

    This paper is based on an analysis of questionnaires sent to the health ministries of Member States of WHO asking for information about the extent, nature, and scope of morbidity statistical information. It is clear that most countries collect some statistics of morbidity and many countries collect extensive data. However, few countries relate their collection to the needs of health administrators for information, and many countries collect statistics principally for publication in annual volumes which may appear anything up to 3 years after the year to which they refer. The desiderata of morbidity statistics may be summarized as reliability, representativeness, and relevance to current health problems. PMID:5306722

  11. Life outside the 50-Minute Hour: The Personal Lives of Counsellors

    ERIC Educational Resources Information Center

    Kennedy, Barbara Sampaio Alhanati; Black, Timothy G.

    2010-01-01

    This study investigates the effects that becoming and being a professional counsellor, including training and professional practice, can have on one's personal life. Semi-structured interviews were conducted with six professional counsellors, asking how their training and professional practice has affected their personal lives. Qualitative…

  12. Statistical Diversions

    ERIC Educational Resources Information Center

    Petocz, Peter; Sowey, Eric

    2008-01-01

    In this article, the authors focus on hypothesis testing--that peculiarly statistical way of deciding things. Statistical methods for testing hypotheses were developed in the 1920s and 1930s by some of the most famous statisticians, in particular Ronald Fisher, Jerzy Neyman and Egon Pearson, who laid the foundations of almost all modern methods of…

  13. Statistics Clinic

    NASA Technical Reports Server (NTRS)

    Feiveson, Alan H.; Foy, Millennia; Ploutz-Snyder, Robert; Fiedler, James

    2014-01-01

    Do you have elevated p-values? Is the data analysis process getting you down? Do you experience anxiety when you need to respond to criticism of statistical methods in your manuscript? You may be suffering from Insufficient Statistical Support Syndrome (ISSS). For symptomatic relief of ISSS, come for a free consultation with JSC biostatisticians at our help desk during the poster sessions at the HRP Investigators Workshop. Get answers to common questions about sample size, missing data, multiple testing, when to trust the results of your analyses and more. Side effects may include sudden loss of statistics anxiety, improved interpretation of your data, and increased confidence in your results.

  14. SEER Statistics

    Cancer.gov

    The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute works to provide information on cancer statistics in an effort to reduce the burden of cancer among the U.S. population.

  15. Cancer Statistics

    MedlinePlus

    ... cancer statistics across the world. U.S. Cancer Mortality Trends The best indicator of progress against cancer is ... the number of cancer survivors has increased. These trends show that progress is being made against the ...

  16. Statistical Physics

    NASA Astrophysics Data System (ADS)

    Hermann, Claudine

    Statistical Physics bridges the properties of a macroscopic system and the microscopic behavior of its constituting particles, otherwise impossible due to the giant magnitude of Avogadro's number. Numerous systems of today's key technologies - such as semiconductors or lasers - are macroscopic quantum objects; only statistical physics allows for understanding their fundamentals. Therefore, this graduate text also focuses on particular applications such as the properties of electrons in solids with applications, and radiation thermodynamics and the greenhouse effect.

  17. Education Statistics Quarterly, 2003.

    ERIC Educational Resources Information Center

    Marenus, Barbara; Burns, Shelley; Fowler, William; Greene, Wilma; Knepper, Paula; Kolstad, Andrew; McMillen Seastrom, Marilyn; Scott, Leslie

    2003-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications and data products released in a 3-month period. Each issue also contains a message from the NCES on a timely…

  18. Learning Statistical Concepts

    ERIC Educational Resources Information Center

    Akram, Muhammad; Siddiqui, Asim Jamal; Yasmeen, Farah

    2004-01-01

    In order to learn the concept of statistical techniques one needs to run real experiments that generate reliable data. In practice, the data from some well-defined process or system is very costly and time consuming. It is difficult to run real experiments during the teaching period in the university. To overcome these difficulties, statisticians…

  19. Irregular Periods

    MedlinePlus

    ... number of days after the last one. The Menstrual Cycle Most girls get their first period between the ... to skip periods or to have an irregular menstrual cycle. Illness, rapid weight change, or stress can also ...

  20. Statistical optics

    NASA Astrophysics Data System (ADS)

    Goodman, J. W.

    This book is based on the thesis that some training in the area of statistical optics should be included as a standard part of any advanced optics curriculum. Random variables are discussed, taking into account definitions of probability and random variables, distribution functions and density functions, an extension to two or more random variables, statistical averages, transformations of random variables, sums of real random variables, Gaussian random variables, complex-valued random variables, and random phasor sums. Other subjects examined are related to random processes, some first-order properties of light waves, the coherence of optical waves, some problems involving high-order coherence, effects of partial coherence on imaging systems, imaging in the presence of randomly inhomogeneous media, and fundamental limits in photoelectric detection of light. Attention is given to deterministic versus statistical phenomena and models, the Fourier transform, and the fourth-order moment of the spectrum of a detected speckle image.

  1. Statistics Revelations

    ERIC Educational Resources Information Center

    Chicot, Katie; Holmes, Hilary

    2012-01-01

    The use, and misuse, of statistics is commonplace, yet in the printed format data representations can be either over simplified, supposedly for impact, or so complex as to lead to boredom, supposedly for completeness and accuracy. In this article the link to the video clip shows how dynamic visual representations can enliven and enhance the…

  2. Statistical Fun

    ERIC Educational Resources Information Center

    Catley, Alan

    2007-01-01

    Following the announcement last year that there will be no more math coursework assessment at General Certificate of Secondary Education (GCSE), teachers will in the future be able to devote more time to preparing learners for formal examinations. One of the key things that the author has learned when teaching statistics is that it makes for far…

  3. Statistical Optics

    NASA Astrophysics Data System (ADS)

    Goodman, Joseph W.

    2000-07-01

    The Wiley Classics Library consists of selected books that have become recognized classics in their respective fields. With these new unabridged and inexpensive editions, Wiley hopes to extend the life of these important works by making them available to future generations of mathematicians and scientists. Currently available in the Series: T. W. Anderson The Statistical Analysis of Time Series T. S. Arthanari & Yadolah Dodge Mathematical Programming in Statistics Emil Artin Geometric Algebra Norman T. J. Bailey The Elements of Stochastic Processes with Applications to the Natural Sciences Robert G. Bartle The Elements of Integration and Lebesgue Measure George E. P. Box & Norman R. Draper Evolutionary Operation: A Statistical Method for Process Improvement George E. P. Box & George C. Tiao Bayesian Inference in Statistical Analysis R. W. Carter Finite Groups of Lie Type: Conjugacy Classes and Complex Characters R. W. Carter Simple Groups of Lie Type William G. Cochran & Gertrude M. Cox Experimental Designs, Second Edition Richard Courant Differential and Integral Calculus, Volume I RIchard Courant Differential and Integral Calculus, Volume II Richard Courant & D. Hilbert Methods of Mathematical Physics, Volume I Richard Courant & D. Hilbert Methods of Mathematical Physics, Volume II D. R. Cox Planning of Experiments Harold S. M. Coxeter Introduction to Geometry, Second Edition Charles W. Curtis & Irving Reiner Representation Theory of Finite Groups and Associative Algebras Charles W. Curtis & Irving Reiner Methods of Representation Theory with Applications to Finite Groups and Orders, Volume I Charles W. Curtis & Irving Reiner Methods of Representation Theory with Applications to Finite Groups and Orders, Volume II Cuthbert Daniel Fitting Equations to Data: Computer Analysis of Multifactor Data, Second Edition Bruno de Finetti Theory of Probability, Volume I Bruno de Finetti Theory of Probability, Volume 2 W. Edwards Deming Sample Design in Business Research

  4. Education Statistics Quarterly, Fall 2000.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2000-01-01

    The "Education Statistics Quarterly" gives a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications and data products released during a 3-month period. Each message also contains a message from…

  5. Education Statistics Quarterly, Spring 2001.

    ERIC Educational Resources Information Center

    Education Statistics Quarterly, 2001

    2001-01-01

    The "Education Statistics Quarterly" gives a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications, data products and funding opportunities developed over a 3-month period. Each issue also…

  6. Statistical Sampling of Reference Desk Inquiries.

    ERIC Educational Resources Information Center

    Edinger, Joyce A.; Falk, Steven

    1981-01-01

    Discusses the application of statistical sampling to the compiling of reference-desk statistics, and describes a technique that uses the Pearson correlation procedure of SPSS (Statistical Package for the Social Sciences) to determine appropriate sampling periods for keeping reference desk statistics at the University of Missouri at St. Louis. (FM)

  7. [Statistical materials].

    PubMed

    1986-01-01

    Official population data for the USSR are presented for 1985 and 1986. Part 1 (pp. 65-72) contains data on capitals of union republics and cities with over one million inhabitants, including population estimates for 1986 and vital statistics for 1985. Part 2 (p. 72) presents population estimates by sex and union republic, 1986. Part 3 (pp. 73-6) presents data on population growth, including birth, death, and natural increase rates, 1984-1985; seasonal distribution of births and deaths; birth order; age-specific birth rates in urban and rural areas and by union republic; marriages; age at marriage; and divorces. PMID:12178831

  8. Periodical Vandalism: A Chronic Condition?

    ERIC Educational Resources Information Center

    Sleep, Esther L.

    1982-01-01

    A statistical analysis of the losses due to theft and mutilation in the periodicals collection at Brock University indicates that security needs to be tightened. Nine suggestions for improving security are offered, and six references are cited. (CHC)

  9. Periodized wavelets

    SciTech Connect

    Schlossnagle, G.; Restrepo, J.M.; Leaf, G.K.

    1993-12-01

    The properties of periodized Daubechies wavelets on [0,1] are detailed and contrasted against their counterparts which form a basis for L{sup 2}(R). Numerical examples illustrate the analytical estimates for convergence and demonstrate by comparison with Fourier spectral methods the superiority of wavelet projection methods for approximations. The analytical solution to inner products of periodized wavelets and their derivatives, which are known as connection coefficients, is presented, and several tabulated values are included.

  10. Periodic cages.

    PubMed

    Diudea, Mircea V; Nagy, Csaba L; Silaghi-Dumitrescu, Ioan; Graovac, Ante; Janezic, Dusanka; Vikić-Topić, Drazen

    2005-01-01

    Various cages are constructed by using three types of caps: f-cap (derived from spherical fullerenes by deleting zones of various size), kf-cap (obtainable by cutting off the polar ring, of size k), and t-cap ("tubercule"-cap). Building ways are presented, some of them being possible isomerization routes in the real chemistry of fullerenes. Periodic cages with ((5,7)3) covering are modeled, and their constitutive typing enumeration is given. Spectral data revealed some electronic periodicity in fullerene clusters. Semiempirical and strain energy calculations complete their characterization. PMID:15807490

  11. Periodic Polymers

    NASA Astrophysics Data System (ADS)

    Thomas, Edwin

    2013-03-01

    Periodic polymers can be made by self assembly, directed self assembly and by photolithography. Such materials provide a versatile platform for 1, 2 and 3D periodic nano-micro scale composites with either dielectric or impedance contrast or both, and these can serve for example, as photonic and or phononic crystals for electromagnetic and elastic waves as well as mechanical frames/trusses. Compared to electromagnetic waves, elastic waves are both less complex (longitudinal modes in fluids) and more complex (longitudinal, transverse in-plane and transverse out-of-plane modes in solids). Engineering of the dispersion relation between wave frequency w and wave vector, k enables the opening of band gaps in the density of modes and detailed shaping of w(k). Band gaps can be opened by Bragg scattering, anti-crossing of bands and discrete shape resonances. Current interest is in our group focuses using design - modeling, fabrication and measurement of polymer-based periodic materials for applications as tunable optics and control of phonon flow. Several examples will be described including the design of structures for multispectral band gaps for elastic waves to alter the phonon density of states, the creation of block polymer and bicontinuous metal-carbon nanoframes for structures that are robust against ballistic projectiles and quasi-crystalline solid/fluid structures that can steer shock waves.

  12. Statistical evaluation of forecasts

    NASA Astrophysics Data System (ADS)

    Mader, Malenka; Mader, Wolfgang; Gluckman, Bruce J.; Timmer, Jens; Schelter, Björn

    2014-08-01

    Reliable forecasts of extreme but rare events, such as earthquakes, financial crashes, and epileptic seizures, would render interventions and precautions possible. Therefore, forecasting methods have been developed which intend to raise an alarm if an extreme event is about to occur. In order to statistically validate the performance of a prediction system, it must be compared to the performance of a random predictor, which raises alarms independent of the events. Such a random predictor can be obtained by bootstrapping or analytically. We propose an analytic statistical framework which, in contrast to conventional methods, allows for validating independently the sensitivity and specificity of a forecasting method. Moreover, our method accounts for the periods during which an event has to remain absent or occur after a respective forecast.

  13. Starting Block Performance in Sprinters: A Statistical Method for Identifying Discriminative Parameters of the Performance and an Analysis of the Effect of Providing Feedback over a 6-Week Period

    PubMed Central

    Fortier, Sylvie; Basset, Fabien A.; Mbourou, Ginette A.; Favérial, Jérôme; Teasdale, Normand

    2005-01-01

    The purpose of this study was twofold: (a) to examine if kinetic and kinematic parameters of the sprint start could differentiate elite from sub-elite sprinters and, (b) to investigate whether providing feedback (FB) about selected parameters could improve starting block performance of intermediate sprinters over a 6-week training period. Twelve male sprinters, assigned to an elite or a sub-elite group, participated in Experiment 1. Eight intermediate sprinters participated in Experiment 2. All athletes were required to perform three sprint starts at maximum intensity followed by a 10-m run. To detect differences between elite and sub-elite groups, comparisons were made using t-tests for independent samples. Parameters reaching a significant group difference were retained for the linear discriminant analysis (LDA). The LDA yielded four discriminative kinetic parameters. Feedback about these selected parameters was given to sprinters in Experiment 2. For this experiment, data acquisition was divided into three periods. The first six sessions were without specific FB, whereas the following six sessions were enriched by kinetic FB. Finally, athletes underwent a retention session (without FB) 4 weeks after the twelfth session. Even though differences were found in the time to front peak force, the time to rear peak force, and the front peak force in the retention session, the results of the present study showed that providing FB about selected kinetic parameters differentiating elite from sub-elite sprinters did not improve the starting block performance of intermediate sprinters. Key Points The linear discriminative analysis allows the identification of starting block parameters differentiating elite from sub-elite athletes. 6-week of feedback does not alter starting block performance in training context. The present results failed to confirm previous studies since feedback did not improve targeted kinetic parameters of the complex motor task in real-world context

  14. Cosmetic Plastic Surgery Statistics

    MedlinePlus

    2014 Cosmetic Plastic Surgery Statistics Cosmetic Procedure Trends 2014 Plastic Surgery Statistics Report Please credit the AMERICAN SOCIETY OF PLASTIC SURGEONS when citing statistical data or using ...

  15. Testing for periodicity of extinction

    NASA Technical Reports Server (NTRS)

    Raup, David M.; Sepkoski, J. J., Jr.

    1988-01-01

    The statistical techniques used by Raup and Sepkoski (1984 and 1986) to identify a 26-Myr periodicity in the biological extinction record for the past 250 Myr are reexamined, responding in detail to the criticisms of Stigler and Wagner (1987). It is argued that evaluation of a much larger set of extinction data using a time scale with 51 sampling intervals supports the finding of periodicity. In a reply by Sigler and Wagner, the preference for a 26-Myr period is attributed to a numerical quirk in the Harland et al. (1982) time scale, in which the subinterval boundaries are not linear interpolations between the stage boundaries but have 25-Myr periodicity. It is stressed that the results of the stringent statistical tests imposed do not disprove periodicity but rather indicate that the evidence and analyses presented so far are inadequate.

  16. Statistical properties of exoplanets

    NASA Astrophysics Data System (ADS)

    Udry, Stéphane

    Since the detection a decade ago of the planetary companion of 51 Peg, more than 165 extrasolar planets have been unveiled by radial-velocity measurements. They present a wide variety of characteristics such as large masses with small orbital separations, high eccentricities, period resonances in multi-planet systems, etc. Meaningful features of the statistical distributions of the orbital parameters or parent stellar properties have emerged. We discuss them in the context of the constraints they provide for planet-formation models and in comparison to Neptune-mass planets in short-period orbits recently detected by radial-velocity surveys, thanks to new instrumental developments and adequate observing strategy. We expect continued improvement in velocity precision and anticipate the detection of Neptune-mass planets in longer-period orbits and even lower-mass planets in short-period orbits, giving us new information on the mass distribution function of exoplanets. Finally, the role of radial-velocity follow-up measurements of transit candidates is emphasized.

  17. Statistical Handbook of Science Education.

    ERIC Educational Resources Information Center

    Petersen, Richard J.

    This publication by the National Science Foundation (NSF) is a compilation of pertinent statistical information on the education and training of scientists and engineers in the United States primarily during the period of 1950-1960. This publication is divided into three parts: (1) human resources data; (2) data that deal with the institutional…

  18. Education Statistics Quarterly, Winter 2001.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2002-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications and data products released in a 3-month period. Each issue also contains a message from the NCES on a timely…

  19. Education Statistics Quarterly, Summer 2001.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2001-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications and data products released during a 3-month period. Each issue also contains a message from the NCES on a…

  20. Education Statistics Quarterly, Winter 2000.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2000-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications and data products released during a 3-month period. Each issue also contains a message from the NCES on a…

  1. Education Statistics Quarterly, Fall 2001.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2001-01-01

    The publication gives a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications, data products, and funding opportunities developed over a 3-month period. Each issue also contains a message from…

  2. Statistical modelling of software reliability

    NASA Technical Reports Server (NTRS)

    Miller, Douglas R.

    1991-01-01

    During the six-month period from 1 April 1991 to 30 September 1991 the following research papers in statistical modeling of software reliability appeared: (1) A Nonparametric Software Reliability Growth Model; (2) On the Use and the Performance of Software Reliability Growth Models; (3) Research and Development Issues in Software Reliability Engineering; (4) Special Issues on Software; and (5) Software Reliability and Safety.

  3. Education Statistics Quarterly, Summer 2002.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2002-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications, data products, and funding opportunities developed over a 3-month period. Each issue also contains a message…

  4. Education Statistics Quarterly, Spring 2002.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2002-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications, data products, and funding opportunities developed over a 3-month period. Each issue also contains a message…

  5. Education Statistics Quarterly, Fall 2002.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2003-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications and data products released in a 3-month period. Each issue also contains a message from the NCES on a timely…

  6. On the Period-Amplitude and Amplitude-Period Relationships

    NASA Technical Reports Server (NTRS)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    Examined are Period-Amplitude and Amplitude-Period relationships based on the cyclic behavior of the 12-month moving averages of monthly mean sunspot numbers for cycles 0.23, both in terms of Fisher's exact tests for 2x2 contingency tables and linear regression analyses. Concerning the Period-Amplitude relationship (same cycle), because cycle 23's maximum amplitude is known to be 120.8, the inferred regressions (90-percent prediction intervals) suggest that its period will be 131 +/- 24 months (using all cycles) or 131 +/- 18 months (ignoring cycles 2 and 4, which have the extremes of period, 108 and 164 months, respectively). Because cycle 23 has already persisted for 142 months (May 1996 through February 2008), based on the latter prediction, it should end before September 2008. Concerning the Amplitude-Period relationship (following cycle maximum amplitude versus preceding cycle period), because cycle 23's period is known to be at least 142 months, the inferred regressions (90-percent prediction intervals) suggest that cycle 24's maximum amplitude will be about less than or equal to 96.1 +/- 55.0 (using all cycle pairs) or less than or equal to 91.0 +/- 36.7 (ignoring statistical outlier cycle pairs). Hence, cycle 24's maximum amplitude is expected to be less than 151, perhaps even less than 128, unless cycle pair 23/24 proves to be a statistical outlier.

  7. Predict! Teaching Statistics Using Informational Statistical Inference

    ERIC Educational Resources Information Center

    Makar, Katie

    2013-01-01

    Statistics is one of the most widely used topics for everyday life in the school mathematics curriculum. Unfortunately, the statistics taught in schools focuses on calculations and procedures before students have a chance to see it as a useful and powerful tool. Researchers have found that a dominant view of statistics is as an assortment of tools…

  8. Statistics Poker: Reinforcing Basic Statistical Concepts

    ERIC Educational Resources Information Center

    Leech, Nancy L.

    2008-01-01

    Learning basic statistical concepts does not need to be tedious or dry; it can be fun and interesting through cooperative learning in the small-group activity of Statistics Poker. This article describes a teaching approach for reinforcing basic statistical concepts that can help students who have high anxiety and makes learning and reinforcing…

  9. Neuroendocrine Tumor: Statistics

    MedlinePlus

    ... Tumor > Neuroendocrine Tumor - Statistics Request Permissions Neuroendocrine Tumor - Statistics Approved by the Cancer.Net Editorial Board , 04/ ... the body. It is important to remember that statistics on how many people survive this type of ...

  10. Asymptotic derivation of T* statistic

    NASA Astrophysics Data System (ADS)

    Sharif, Shamshuritawati; Djauhari, Maman A.

    2014-12-01

    Monitoring the stability of correlation structure becomes an imperative subject in economic development and financial industry. It has been extensively implemented by various researchers to understand the behaviour of a sequence of correlation structures based on independent samples in certain time periods. The existing statistical test can only tackle problems involving pn due to the inversion of covariance matrix. Therefore, in this paper we introduced T* statistics, constructed based on upper-off-diagonal elements to overwhelm that difficulty. The limitation distribution has been investigated to make its application promising.

  11. Australia 31-GHz brightness temperature exceedance statistics

    NASA Technical Reports Server (NTRS)

    Gary, B. L.

    1988-01-01

    Water vapor radiometer measurements were made at DSS 43 during an 18 month period. Brightness temperatures at 31 GHz were subjected to a statistical analysis which included correction for the effects of occasional water on the radiometer radome. An exceedance plot was constructed, and the 1 percent exceedance statistics occurs at 120 K. The 5 percent exceedance statistics occurs at 70 K, compared with 75 K in Spain. These values are valid for all of the three month groupings that were studied.

  12. Statistical Reference Datasets

    National Institute of Standards and Technology Data Gateway

    Statistical Reference Datasets (Web, free access)   The Statistical Reference Datasets is also supported by the Standard Reference Data Program. The purpose of this project is to improve the accuracy of statistical software by providing reference datasets with certified computational results that enable the objective evaluation of statistical software.

  13. On More Sensitive Periodogram Statistics

    NASA Astrophysics Data System (ADS)

    Bélanger, G.

    2016-05-01

    Period searches in event data have traditionally used the Rayleigh statistic, R 2. For X-ray pulsars, the standard has been the Z 2 statistic, which sums over more than one harmonic. For γ-rays, the H-test, which optimizes the number of harmonics to sum, is often used. These periodograms all suffer from the same problem, namely artifacts caused by correlations in the Fourier components that arise from testing frequencies with a non-integer number of cycles. This article addresses this problem. The modified Rayleigh statistic is discussed, its generalization to any harmonic, {{ R }}k2, is formulated, and from the latter, the modified Z 2 statistic, {{ Z }}2, is constructed. Versions of these statistics for binned data and point measurements are derived, and it is shown that the variance in the uncertainties can have an important influence on the periodogram. It is shown how to combine the information about the signal frequency from the different harmonics to estimate its value with maximum accuracy. The methods are applied to an XMM-Newton observation of the Crab pulsar for which a decomposition of the pulse profile is presented, and shows that most of the power is in the second, third, and fifth harmonics. Statistical detection power of the {{ R }}k2 statistic is superior to the FFT and equivalent to the Lomb--Scargle (LS). Response to gaps in the data is assessed, and it is shown that the LS does not protect against the distortions they cause. The main conclusion of this work is that the classical R 2 and Z 2 should be replaced by {{ R }}k2 and {{ Z }}2 in all applications with event data, and the LS should be replaced by the {{ R }}k2 when the uncertainty varies from one point measurement to another.

  14. First-digit law in nonextensive statistics.

    PubMed

    Shao, Lijing; Ma, Bo-Qiang

    2010-10-01

    Nonextensive statistics, characterized by a nonextensive parameter q, is a promising and practically useful generalization of the Boltzmann statistics to describe power-law behaviors from physical and social observations. We here explore the unevenness of the first-digit distribution of nonextensive statistics analytically and numerically. We find that the first-digit distribution follows Benford's law and fluctuates slightly in a periodical manner with respect to the logarithm of the temperature. The fluctuation decreases when q increases, and the result converges to Benford's law exactly as q approaches 2. The relevant regularities between nonextensive statistics and Benford's law are also presented and discussed. PMID:21230241

  15. Periodicity in marine extinction events

    NASA Technical Reports Server (NTRS)

    Sepkoski, J. John, Jr.; Raup, David M.

    1986-01-01

    The periodicity of extinction events is examined in detail. In particular, the temporal distribution of specific, identifiable extinction events is analyzed. The nature and limitations of the data base on the global fossil record is discussed in order to establish limits of resolution in statistical analyses. Peaks in extinction intensity which appear to differ significantly from background levels are considered, and new analyses of the temporal distribution of these peaks are presented. Finally, some possible causes of periodicity and of interdependence among extinction events over the last quarter billion years of earth history are examined.

  16. Uterine Cancer Statistics

    MedlinePlus

    ... Research AMIGAS Fighting Cervical Cancer Worldwide Stay Informed Statistics for Other Kinds of Cancer Breast Cervical Colorectal ( ... Skin Vaginal and Vulvar Cancer Home Uterine Cancer Statistics Language: English Español (Spanish) Recommend on Facebook Tweet ...

  17. Mathematical and statistical analysis

    NASA Technical Reports Server (NTRS)

    Houston, A. Glen

    1988-01-01

    The goal of the mathematical and statistical analysis component of RICIS is to research, develop, and evaluate mathematical and statistical techniques for aerospace technology applications. Specific research areas of interest include modeling, simulation, experiment design, reliability assessment, and numerical analysis.

  18. Minnesota Health Statistics 1988.

    ERIC Educational Resources Information Center

    Minnesota State Dept. of Health, St. Paul.

    This document comprises the 1988 annual statistical report of the Minnesota Center for Health Statistics. After introductory technical notes on changes in format, sources of data, and geographic allocation of vital events, an overview is provided of vital health statistics in all areas. Thereafter, separate sections of the report provide tables…

  19. Ethics in Statistics

    ERIC Educational Resources Information Center

    Lenard, Christopher; McCarthy, Sally; Mills, Terence

    2014-01-01

    There are many different aspects of statistics. Statistics involves mathematics, computing, and applications to almost every field of endeavour. Each aspect provides an opportunity to spark someone's interest in the subject. In this paper we discuss some ethical aspects of statistics, and describe how an introduction to ethics has been…

  20. Avoiding Statistical Mistakes

    ERIC Educational Resources Information Center

    Strasser, Nora

    2007-01-01

    Avoiding statistical mistakes is important for educators at all levels. Basic concepts will help you to avoid making mistakes using statistics and to look at data with a critical eye. Statistical data is used at educational institutions for many purposes. It can be used to support budget requests, changes in educational philosophy, changes to…

  1. Statistical quality management

    NASA Astrophysics Data System (ADS)

    Vanderlaan, Paul

    1992-10-01

    Some aspects of statistical quality management are discussed. Quality has to be defined as a concrete, measurable quantity. The concepts of Total Quality Management (TQM), Statistical Process Control (SPC), and inspection are explained. In most cases SPC is better than inspection. It can be concluded that statistics has great possibilities in the field of TQM.

  2. Explorations in statistics: statistical facets of reproducibility.

    PubMed

    Curran-Everett, Douglas

    2016-06-01

    Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This eleventh installment of Explorations in Statistics explores statistical facets of reproducibility. If we obtain an experimental result that is scientifically meaningful and statistically unusual, we would like to know that our result reflects a general biological phenomenon that another researcher could reproduce if (s)he repeated our experiment. But more often than not, we may learn this researcher cannot replicate our result. The National Institutes of Health and the Federation of American Societies for Experimental Biology have created training modules and outlined strategies to help improve the reproducibility of research. These particular approaches are necessary, but they are not sufficient. The principles of hypothesis testing and estimation are inherent to the notion of reproducibility in science. If we want to improve the reproducibility of our research, then we need to rethink how we apply fundamental concepts of statistics to our science. PMID:27231259

  3. Incorporating Spectra Into Periodic Timing

    NASA Astrophysics Data System (ADS)

    Connors, Alanna; Hong, J.; Protopapas, P.; Kashyap, V.

    2011-09-01

    The Chandra surveys have resulted in a wealth of data on low-luminosity X-ray sources (Lx 1030-34 erg/s) of Galactic scales beyond the local solar neighborhood. Many of these are compact binaries, in particular, cataclysmic variables, often identified by their periodic X-ray variability and spectra. Hong et al. (2009, 2011) have used energy quantiles (Hong, Schlegel & Grindlay, 2004) as a fast, robust indicator of spectral hardness and absorption of the X-ray sources. Energy quantiles also enable a simple but effective illustration of spectral changes with phase in these periodic systems: e.g. absorption by the accreting material is understood to drive the periodic light-curves. An interesting question is how to best make use of the information encapsulated in the periodic change in energy spectrum, along with the periodic change in intensity, especially for cases of ambiguous period determination? And, how to do it computationally efficiently? A first approach is to do the period search in intensity, as is standard; and then use a criterion of spectral variation to verify possible periods. Huijse, Zegers & Protopapas (2011) recently demonstrated a powerful period estimation technique using information potential and correntropy embedded in the light curve. Similar quantities based on energies (or energy quantiles) of X-ray photons can serve as criteria of spectral variation. A different approach treats the spectrum variations and intensity variations completely independently, searching through period-space in each, and then combining the results. A more general method would include both at the same time, looking for statistically significant variations above what is expected for a constant (in intensity and spectrum).

  4. Evolution of periodicity in periodical cicadas

    PubMed Central

    Ito, Hiromu; Kakishima, Satoshi; Uehara, Takashi; Morita, Satoru; Koyama, Takuya; Sota, Teiji; Cooley, John R.; Yoshimura, Jin

    2015-01-01

    Periodical cicadas (Magicicada spp.) in the USA are famous for their unique prime-numbered life cycles of 13 and 17 years and their nearly perfectly synchronized mass emergences. Because almost all known species of cicada are non-periodical, periodicity is assumed to be a derived state. A leading hypothesis for the evolution of periodicity in Magicicada implicates the decline in average temperature during glacial periods. During the evolution of periodicity, the determinant of maturation in ancestral cicadas is hypothesized to have switched from size dependence to time (period) dependence. The selection for the prime-numbered cycles should have taken place only after the fixation of periodicity. Here, we build an individual-based model of cicadas under conditions of climatic cooling to explore the fixation of periodicity. In our model, under cold environments, extremely long juvenile stages lead to extremely low adult densities, limiting mating opportunities and favouring the evolution of synchronized emergence. Our results indicate that these changes, which were triggered by glacial cooling, could have led to the fixation of periodicity in the non-periodical ancestors. PMID:26365061

  5. Quantum Statistical Mechanics

    NASA Astrophysics Data System (ADS)

    Schieve, William C.; Horwitz, Lawrence P.

    2009-04-01

    1. Foundations of quantum statistical mechanics; 2. Elementary examples; 3. Quantum statistical master equation; 4. Quantum kinetic equations; 5. Quantum irreversibility; 6. Entropy and dissipation: the microscopic theory; 7. Global equilibrium: thermostatics and the microcanonical ensemble; 8. Bose-Einstein ideal gas condensation; 9. Scaling, renormalization and the Ising model; 10. Relativistic covariant statistical mechanics of many particles; 11. Quantum optics and damping; 12. Entanglements; 13. Quantum measurement and irreversibility; 14. Quantum Langevin equation: quantum Brownian motion; 15. Linear response: fluctuation and dissipation theorems; 16. Time dependent quantum Green's functions; 17. Decay scattering; 18. Quantum statistical mechanics, extended; 19. Quantum transport with tunneling and reservoir ballistic transport; 20. Black hole thermodynamics; Appendix; Index.

  6. Statistical distribution sampling

    NASA Technical Reports Server (NTRS)

    Johnson, E. S.

    1975-01-01

    Determining the distribution of statistics by sampling was investigated. Characteristic functions, the quadratic regression problem, and the differential equations for the characteristic functions are analyzed.

  7. Statistical Fault Detection & Diagnosis Expert System

    SciTech Connect

    Wegerich, Stephan

    1996-12-18

    STATMON is an expert system that performs real-time fault detection and diagnosis of redundant sensors in any industrial process requiring high reliability. After a training period performed during normal operation, the expert system monitors the statistical properties of the incoming signals using a pattern recognition test. If the test determines that statistical properties of the signals have changed, the expert system performs a sequence of logical steps to determine which sensor or machine component has degraded.

  8. The Development of Wage Statistics in the United States.

    ERIC Educational Resources Information Center

    Douty, H. M.

    This bulletin briefly traces the development of wage statistics in nonfarm employments in the United States, focusing mainly on the work of the Bureau of Labor Statistics. The formative period of wage statistics was the final quarter of the nineteenth century, although some information was assembled and systematic insight into the behavior of…

  9. Familial Periodic Paralyses

    MedlinePlus

    ... NINDS NINDS Familial Periodic Paralyses Information Page Synonym(s): Periodic Paralyses Table of Contents (click to jump to sections) What are Familial Periodic Paralyses? Is there any treatment? What is the ...

  10. 39 CFR 3050.28 - Monthly and pay period reports.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 39 Postal Service 1 2010-07-01 2010-07-01 false Monthly and pay period reports. 3050.28 Section 3050.28 Postal Service POSTAL REGULATORY COMMISSION PERSONNEL PERIODIC REPORTING § 3050.28 Monthly and... electronic form (pay period); (e) On-roll and Paid Employee Statistics (ORPES) (pay period); and (f)...

  11. 39 CFR 3050.28 - Monthly and pay period reports.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 39 Postal Service 1 2013-07-01 2013-07-01 false Monthly and pay period reports. 3050.28 Section 3050.28 Postal Service POSTAL REGULATORY COMMISSION PERSONNEL PERIODIC REPORTING § 3050.28 Monthly and... electronic form (pay period); (e) On-roll and Paid Employee Statistics (ORPES) (pay period); and (f)...

  12. 39 CFR 3050.28 - Monthly and pay period reports.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 39 Postal Service 1 2014-07-01 2014-07-01 false Monthly and pay period reports. 3050.28 Section 3050.28 Postal Service POSTAL REGULATORY COMMISSION PERSONNEL PERIODIC REPORTING § 3050.28 Monthly and... electronic form (pay period); (e) On-roll and Paid Employee Statistics (ORPES) (pay period); and (f)...

  13. Explorations in Statistics: Regression

    ERIC Educational Resources Information Center

    Curran-Everett, Douglas

    2011-01-01

    Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This seventh installment of "Explorations in Statistics" explores regression, a technique that estimates the nature of the relationship between two things for which we may only surmise a mechanistic or predictive connection.…

  14. Multidimensional Visual Statistical Learning

    ERIC Educational Resources Information Center

    Turk-Browne, Nicholas B.; Isola, Phillip J.; Scholl, Brian J.; Treat, Teresa A.

    2008-01-01

    Recent studies of visual statistical learning (VSL) have demonstrated that statistical regularities in sequences of visual stimuli can be automatically extracted, even without intent or awareness. Despite much work on this topic, however, several fundamental questions remain about the nature of VSL. In particular, previous experiments have not…

  15. On Statistical Testing.

    ERIC Educational Resources Information Center

    Huberty, Carl J.

    An approach to statistical testing, which combines Neyman-Pearson hypothesis testing and Fisher significance testing, is recommended. The use of P-values in this approach is discussed in some detail. The author also discusses some problems which are often found in introductory statistics textbooks. The problems involve the definitions of…

  16. Deconstructing Statistical Analysis

    ERIC Educational Resources Information Center

    Snell, Joel

    2014-01-01

    Using a very complex statistical analysis and research method for the sake of enhancing the prestige of an article or making a new product or service legitimate needs to be monitored and questioned for accuracy. 1) The more complicated the statistical analysis, and research the fewer the number of learned readers can understand it. This adds a…

  17. Explorations in Statistics: Power

    ERIC Educational Resources Information Center

    Curran-Everett, Douglas

    2010-01-01

    Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This fifth installment of "Explorations in Statistics" revisits power, a concept fundamental to the test of a null hypothesis. Power is the probability that we reject the null hypothesis when it is false. Four things affect…

  18. Applied Statistics with SPSS

    ERIC Educational Resources Information Center

    Huizingh, Eelko K. R. E.

    2007-01-01

    Accessibly written and easy to use, "Applied Statistics Using SPSS" is an all-in-one self-study guide to SPSS and do-it-yourself guide to statistics. What is unique about Eelko Huizingh's approach is that this book is based around the needs of undergraduate students embarking on their own research project, and its self-help style is designed to…

  19. Overhead Image Statistics

    SciTech Connect

    Vijayaraj, Veeraraghavan; Cheriyadat, Anil M; Bhaduri, Budhendra L; Vatsavai, Raju; Bright, Eddie A

    2008-01-01

    Statistical properties of high-resolution overhead images representing different land use categories are analyzed using various local and global statistical image properties based on the shape of the power spectrum, image gradient distributions, edge co-occurrence, and inter-scale wavelet coefficient distributions. The analysis was performed on a database of high-resolution (1 meter) overhead images representing a multitude of different downtown, suburban, commercial, agricultural and wooded exemplars. Various statistical properties relating to these image categories and their relationship are discussed. The categorical variations in power spectrum contour shapes, the unique gradient distribution characteristics of wooded categories, the similarity in edge co-occurrence statistics for overhead and natural images, and the unique edge co-occurrence statistics of downtown categories are presented in this work. Though previous work on natural image statistics has showed some of the unique characteristics for different categories, the relationships for overhead images are not well understood. The statistical properties of natural images were used in previous studies to develop prior image models, to predict and index objects in a scene and to improve computer vision models. The results from our research findings can be used to augment and adapt computer vision algorithms that rely on prior image statistics to process overhead images, calibrate the performance of overhead image analysis algorithms, and derive features for better discrimination of overhead image categories.

  20. Understanding Undergraduate Statistical Anxiety

    ERIC Educational Resources Information Center

    McKim, Courtney

    2014-01-01

    The purpose of this study was to understand undergraduate students' views of statistics. Results reveal that students with less anxiety have a higher interest in statistics and also believe in their ability to perform well in the course. Also students who have a more positive attitude about the class tend to have a higher belief in their…

  1. Statistics and Measurements

    PubMed Central

    Croarkin, M. Carroll

    2001-01-01

    For more than 50 years, the Statistical Engineering Division (SED) has been instrumental in the success of a broad spectrum of metrology projects at NBS/NIST. This paper highlights fundamental contributions of NBS/NIST statisticians to statistics and to measurement science and technology. Published methods developed by SED staff, especially during the early years, endure as cornerstones of statistics not only in metrology and standards applications, but as data-analytic resources used across all disciplines. The history of statistics at NBS/NIST began with the formation of what is now the SED. Examples from the first five decades of the SED illustrate the critical role of the division in the successful resolution of a few of the highly visible, and sometimes controversial, statistical studies of national importance. A review of the history of major early publications of the division on statistical methods, design of experiments, and error analysis and uncertainty is followed by a survey of several thematic areas. The accompanying examples illustrate the importance of SED in the history of statistics, measurements and standards: calibration and measurement assurance, interlaboratory tests, development of measurement methods, Standard Reference Materials, statistical computing, and dissemination of measurement technology. A brief look forward sketches the expanding opportunity and demand for SED statisticians created by current trends in research and development at NIST.

  2. Water Quality Statistics

    ERIC Educational Resources Information Center

    Hodgson, Ted; Andersen, Lyle; Robison-Cox, Jim; Jones, Clain

    2004-01-01

    Water quality experiments, especially the use of macroinvertebrates as indicators of water quality, offer an ideal context for connecting statistics and science. In the STAR program for secondary students and teachers, water quality experiments were also used as a context for teaching statistics. In this article, we trace one activity that uses…

  3. Application Statistics 1987.

    ERIC Educational Resources Information Center

    Council of Ontario Universities, Toronto.

    Summary statistics on application and registration patterns of applicants wishing to pursue full-time study in first-year places in Ontario universities (for the fall of 1987) are given. Data on registrations were received indirectly from the universities as part of their annual submission of USIS/UAR enrollment data to Statistics Canada and MCU.…

  4. Introduction to Statistical Physics

    NASA Astrophysics Data System (ADS)

    Casquilho, João Paulo; Ivo Cortez Teixeira, Paulo

    2014-12-01

    Preface; 1. Random walks; 2. Review of thermodynamics; 3. The postulates of statistical physics. Thermodynamic equilibrium; 4. Statistical thermodynamics – developments and applications; 5. The classical ideal gas; 6. The quantum ideal gas; 7. Magnetism; 8. The Ising model; 9. Liquid crystals; 10. Phase transitions and critical phenomena; 11. Irreversible processes; Appendixes; Index.

  5. Reform in Statistical Education

    ERIC Educational Resources Information Center

    Huck, Schuyler W.

    2007-01-01

    Two questions are considered in this article: (a) What should professionals in school psychology do in an effort to stay current with developments in applied statistics? (b) What should they do with their existing knowledge to move from surface understanding of statistics to deep understanding? Written for school psychologists who have completed…

  6. Statistical Mapping by Computer.

    ERIC Educational Resources Information Center

    Utano, Jack J.

    The function of a statistical map is to provide readers with a visual impression of the data so that they may be able to identify any geographic characteristics of the displayed phenomena. The increasingly important role played by the computer in the production of statistical maps is manifested by the varied examples of computer maps in recent…

  7. DISABILITY STATISTICS CENTER

    EPA Science Inventory

    The purpose of the Disability Statistics Center is to produce and disseminate statistical information on disability and the status of people with disabilities in American society and to establish and monitor indicators of how conditions are changing over time to meet their health...

  8. Statistics 101 for Radiologists.

    PubMed

    Anvari, Arash; Halpern, Elkan F; Samir, Anthony E

    2015-10-01

    Diagnostic tests have wide clinical applications, including screening, diagnosis, measuring treatment effect, and determining prognosis. Interpreting diagnostic test results requires an understanding of key statistical concepts used to evaluate test efficacy. This review explains descriptive statistics and discusses probability, including mutually exclusive and independent events and conditional probability. In the inferential statistics section, a statistical perspective on study design is provided, together with an explanation of how to select appropriate statistical tests. Key concepts in recruiting study samples are discussed, including representativeness and random sampling. Variable types are defined, including predictor, outcome, and covariate variables, and the relationship of these variables to one another. In the hypothesis testing section, we explain how to determine if observed differences between groups are likely to be due to chance. We explain type I and II errors, statistical significance, and study power, followed by an explanation of effect sizes and how confidence intervals can be used to generalize observed effect sizes to the larger population. Statistical tests are explained in four categories: t tests and analysis of variance, proportion analysis tests, nonparametric tests, and regression techniques. We discuss sensitivity, specificity, accuracy, receiver operating characteristic analysis, and likelihood ratios. Measures of reliability and agreement, including κ statistics, intraclass correlation coefficients, and Bland-Altman graphs and analysis, are introduced. PMID:26466186

  9. Statistics in medicine.

    PubMed

    Januszyk, Michael; Gurtner, Geoffrey C

    2011-01-01

    The scope of biomedical research has expanded rapidly during the past several decades, and statistical analysis has become increasingly necessary to understand the meaning of large and diverse quantities of raw data. As such, a familiarity with this lexicon is essential for critical appraisal of medical literature. This article attempts to provide a practical overview of medical statistics, with an emphasis on the selection, application, and interpretation of specific tests. This includes a brief review of statistical theory and its nomenclature, particularly with regard to the classification of variables. A discussion of descriptive methods for data presentation is then provided, followed by an overview of statistical inference and significance analysis, and detailed treatment of specific statistical tests and guidelines for their interpretation. PMID:21200241

  10. Statistics at a glance.

    PubMed

    Ector, Hugo

    2010-12-01

    I still remember my first book on statistics: "Elementary statistics with applications in medicine and the biological sciences" by Frederick E. Croxton. For me, it has been the start of pursuing understanding statistics in daily life and in medical practice. It was the first volume in a long row of books. In his introduction, Croxton pretends that"nearly everyone involved in any aspect of medicine needs to have some knowledge of statistics". The reality is that for many clinicians, statistics are limited to a "P < 0.05 = ok". I do not blame my colleagues who omit the paragraph on statistical methods. They have never had the opportunity to learn concise and clear descriptions of the key features. I have experienced how some authors can describe difficult methods in a well understandable language. Others fail completely. As a teacher, I tell my students that life is impossible without a basic knowledge of statistics. This feeling has resulted in an annual seminar of 90 minutes. This tutorial is the summary of this seminar. It is a summary and a transcription of the best pages I have detected. PMID:21302664

  11. Statistics: A Brief Overview

    PubMed Central

    Winters, Ryan; Winters, Andrew; Amedee, Ronald G.

    2010-01-01

    The Accreditation Council for Graduate Medical Education sets forth a number of required educational topics that must be addressed in residency and fellowship programs. We sought to provide a primer on some of the important basic statistical concepts to consider when examining the medical literature. It is not essential to understand the exact workings and methodology of every statistical test encountered, but it is necessary to understand selected concepts such as parametric and nonparametric tests, correlation, and numerical versus categorical data. This working knowledge will allow you to spot obvious irregularities in statistical analyses that you encounter. PMID:21603381

  12. Statistics of football dynamics

    NASA Astrophysics Data System (ADS)

    Mendes, R. S.; Malacarne, L. C.; Anteneodo, C.

    2007-06-01

    We investigate the dynamics of football matches. Our goal is to characterize statistically the temporal sequence of ball movements in this collective sport game, searching for traits of complex behavior. Data were collected over a variety of matches in South American, European and World championships throughout 2005 and 2006. We show that the statistics of ball touches presents power-law tails and can be described by q-gamma distributions. To explain such behavior we propose a model that provides information on the characteristics of football dynamics. Furthermore, we discuss the statistics of duration of out-of-play intervals, not directly related to the previous scenario.

  13. Playing at Statistical Mechanics

    ERIC Educational Resources Information Center

    Clark, Paul M.; And Others

    1974-01-01

    Discussed are the applications of counting techniques of a sorting game to distributions and concepts in statistical mechanics. Included are the following distributions: Fermi-Dirac, Bose-Einstein, and most probable. (RH)

  14. Cooperative Learning in Statistics.

    ERIC Educational Resources Information Center

    Keeler, Carolyn M.; And Others

    1994-01-01

    Formal use of cooperative learning techniques proved effective in improving student performance and retention in a freshman level statistics course. Lectures interspersed with group activities proved effective in increasing conceptual understanding and overall class performance. (11 references) (Author)

  15. Understanding Solar Flare Statistics

    NASA Astrophysics Data System (ADS)

    Wheatland, M. S.

    2005-12-01

    A review is presented of work aimed at understanding solar flare statistics, with emphasis on the well known flare power-law size distribution. Although avalanche models are perhaps the favoured model to describe flare statistics, their physical basis is unclear, and they are divorced from developing ideas in large-scale reconnection theory. An alternative model, aimed at reconciling large-scale reconnection models with solar flare statistics, is revisited. The solar flare waiting-time distribution has also attracted recent attention. Observed waiting-time distributions are described, together with what they might tell us about the flare phenomenon. Finally, a practical application of flare statistics to flare prediction is described in detail, including the results of a year of automated (web-based) predictions from the method.

  16. Titanic: A Statistical Exploration.

    ERIC Educational Resources Information Center

    Takis, Sandra L.

    1999-01-01

    Uses the available data about the Titanic's passengers to interest students in exploring categorical data and the chi-square distribution. Describes activities incorporated into a statistics class and gives additional resources for collecting information about the Titanic. (ASK)

  17. Plague Maps and Statistics

    MedlinePlus

    ... and Statistics Recommend on Facebook Tweet Share Compartir Plague in the United States Plague was first introduced ... per year in the United States: 1900-2012. Plague Worldwide Plague epidemics have occurred in Africa, Asia, ...

  18. Elements of Statistics

    NASA Astrophysics Data System (ADS)

    Grégoire, G.

    2016-05-01

    This chapter is devoted to two objectives. The first one is to answer the request expressed by attendees of the first Astrostatistics School (Annecy, October 2013) to be provided with an elementary vademecum of statistics that would facilitate understanding of the given courses. In this spirit we recall very basic notions, that is definitions and properties that we think sufficient to benefit from courses given in the Astrostatistical School. Thus we give briefly definitions and elementary properties on random variables and vectors, distributions, estimation and tests, maximum likelihood methodology. We intend to present basic ideas in a hopefully comprehensible way. We do not try to give a rigorous presentation, and due to the place devoted to this chapter, can cover only a rather limited field of statistics. The second aim is to focus on some statistical tools that are useful in classification: basic introduction to Bayesian statistics, maximum likelihood methodology, Gaussian vectors and Gaussian mixture models.

  19. Tuberculosis Data and Statistics

    MedlinePlus

    ... Organization Chart Advisory Groups Federal TB Task Force Data and Statistics Language: English Español (Spanish) Recommend on ... United States publication. PDF [6 MB] Interactive TB Data Tool Online Tuberculosis Information System (OTIS) OTIS is ...

  20. Statistics of the sagas

    NASA Astrophysics Data System (ADS)

    Richfield, Jon; bookfeller

    2016-07-01

    In reply to Ralph Kenna and Pádraig Mac Carron's feature article “Maths meets myths” in which they describe how they are using techniques from statistical physics to characterize the societies depicted in ancient Icelandic sagas.

  1. Brain Tumor Statistics

    MedlinePlus

    ... facts and statistics here include brain and central nervous system tumors (including spinal cord, pituitary and pineal gland ... U.S. living with a primary brain and central nervous system tumor. This year, nearly 17,000 people will ...

  2. Purposeful Statistical Investigations

    ERIC Educational Resources Information Center

    Day, Lorraine

    2014-01-01

    Lorraine Day provides us with a great range of statistical investigations using various resources such as maths300 and TinkerPlots. Each of the investigations link mathematics to students' lives and provide engaging and meaningful contexts for mathematical inquiry.

  3. Statistical Perspectives on Stratospheric Transport

    NASA Technical Reports Server (NTRS)

    Sparling, L. C.

    1999-01-01

    Long-lived tropospheric source gases, such as nitrous oxide, enter the stratosphere through the tropical tropopause, are transported throughout the stratosphere by the Brewer-Dobson circulation, and are photochemically destroyed in the upper stratosphere. These chemical constituents, or "tracers" can be used to track mixing and transport by the stratospheric winds. Much of our understanding about the stratospheric circulation is based on large scale gradients and other spatial features in tracer fields constructed from satellite measurements. The point of view presented in this paper is different, but complementary, in that transport is described in terms of tracer probability distribution functions (PDFs). The PDF is computed from the measurements, and is proportional to the area occupied by tracer values in a given range. The flavor of this paper is tutorial, and the ideas are illustrated with several examples of transport-related phenomena, annotated with remarks that summarize the main point or suggest new directions. One example shows how the multimodal shape of the PDF gives information about the different branches of the circulation. Another example shows how the statistics of fluctuations from the most probable tracer value give insight into mixing between different regions of the atmosphere. Also included is an analysis of the time-dependence of the PDF during the onset and decline of the winter circulation, and a study of how "bursts" in the circulation are reflected in transient periods of rapid evolution of the PDF. The dependence of the statistics on location and time are also shown to be important for practical problems related to statistical robustness and satellite sampling. The examples illustrate how physically-based statistical analysis can shed some light on aspects of stratospheric transport that may not be obvious or quantifiable with other types of analyses. An important motivation for the work presented here is the need for synthesis of the

  4. Statistical process control

    SciTech Connect

    Oakland, J.S.

    1986-01-01

    Addressing the increasing importance for firms to have a thorough knowledge of statistically based quality control procedures, this book presents the fundamentals of statistical process control (SPC) in a non-mathematical, practical way. It provides real-life examples and data drawn from a wide variety of industries. The foundations of good quality management and process control, and control of conformance and consistency during production are given. Offers clear guidance to those who wish to understand and implement modern SPC techniques.

  5. Statistical Physics of Particles

    NASA Astrophysics Data System (ADS)

    Kardar, Mehran

    2006-06-01

    Statistical physics has its origins in attempts to describe the thermal properties of matter in terms of its constituent particles, and has played a fundamental role in the development of quantum mechanics. Based on lectures for a course in statistical mechanics taught by Professor Kardar at Massachusetts Institute of Technology, this textbook introduces the central concepts and tools of statistical physics. It contains a chapter on probability and related issues such as the central limit theorem and information theory, and covers interacting particles, with an extensive description of the van der Waals equation and its derivation by mean field approximation. It also contains an integrated set of problems, with solutions to selected problems at the end of the book. It will be invaluable for graduate and advanced undergraduate courses in statistical physics. A complete set of solutions is available to lecturers on a password protected website at www.cambridge.org/9780521873420. Based on lecture notes from a course on Statistical Mechanics taught by the author at MIT Contains 89 exercises, with solutions to selected problems Contains chapters on probability and interacting particles Ideal for graduate courses in Statistical Mechanics

  6. Statistical Physics of Fields

    NASA Astrophysics Data System (ADS)

    Kardar, Mehran

    2006-06-01

    While many scientists are familiar with fractals, fewer are familiar with the concepts of scale-invariance and universality which underly the ubiquity of their shapes. These properties may emerge from the collective behaviour of simple fundamental constituents, and are studied using statistical field theories. Based on lectures for a course in statistical mechanics taught by Professor Kardar at Massachusetts Institute of Technology, this textbook demonstrates how such theories are formulated and studied. Perturbation theory, exact solutions, renormalization groups, and other tools are employed to demonstrate the emergence of scale invariance and universality, and the non-equilibrium dynamics of interfaces and directed paths in random media are discussed. Ideal for advanced graduate courses in statistical physics, it contains an integrated set of problems, with solutions to selected problems at the end of the book. A complete set of solutions is available to lecturers on a password protected website at www.cambridge.org/9780521873413. Based on lecture notes from a course on Statistical Mechanics taught by the author at MIT Contains 65 exercises, with solutions to selected problems Features a thorough introduction to the methods of Statistical Field theory Ideal for graduate courses in Statistical Physics

  7. Education Statistics Quarterly. Volume 5, Issue 1.

    ERIC Educational Resources Information Center

    Dillow, Sally, Ed.

    2003-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications, data product, and funding opportunities developed over a 3-month period. Each issue also contains a message…

  8. An Active Learning Approach to Teaching Statistics.

    ERIC Educational Resources Information Center

    Dolinsky, Beverly

    2001-01-01

    Provides suggestions for using active learning as the primary means to teaching statistics in order to create a collaborative environment. Addresses such strategies as using SPSS Base 7.5 for Windows and course periods centered on answering student-generated questions. Discusses various writing intensive assignments. (CMK)

  9. Period meter for reactors

    DOEpatents

    Rusch, Gordon K.

    1976-01-06

    An improved log N amplifier type nuclear reactor period meter with reduced probability for noise-induced scrams is provided. With the reactor at low power levels a sampling circuit is provided to determine the reactor period by measuring the finite change in the amplitude of the log N amplifier output signal for a predetermined time period, while at high power levels, differentiation of the log N amplifier output signal provides an additional measure of the reactor period.

  10. The Periodic Pyramid

    ERIC Educational Resources Information Center

    Hennigan, Jennifer N.; Grubbs, W. Tandy

    2013-01-01

    The chemical elements present in the modern periodic table are arranged in terms of atomic numbers and chemical periodicity. Periodicity arises from quantum mechanical limitations on how many electrons can occupy various shells and subshells of an atom. The shell model of the atom predicts that a maximum of 2, 8, 18, and 32 electrons can occupy…

  11. Statistical Physics of Fracture

    SciTech Connect

    Alava, Mikko; Nukala, Phani K; Zapperi, Stefano

    2006-05-01

    Disorder and long-range interactions are two of the key components that make material failure an interesting playfield for the application of statistical mechanics. The cornerstone in this respect has been lattice models of the fracture in which a network of elastic beams, bonds, or electrical fuses with random failure thresholds are subject to an increasing external load. These models describe on a qualitative level the failure processes of real, brittle, or quasi-brittle materials. This has been particularly important in solving the classical engineering problems of material strength: the size dependence of maximum stress and its sample-to-sample statistical fluctuations. At the same time, lattice models pose many new fundamental questions in statistical physics, such as the relation between fracture and phase transitions. Experimental results point out to the existence of an intriguing crackling noise in the acoustic emission and of self-affine fractals in the crack surface morphology. Recent advances in computer power have enabled considerable progress in the understanding of such models. Among these partly still controversial issues, are the scaling and size-effects in material strength and accumulated damage, the statistics of avalanches or bursts of microfailures, and the morphology of the crack surface. Here we present an overview of the results obtained with lattice models for fracture, highlighting the relations with statistical physics theories and more conventional fracture mechanics approaches.

  12. Statistical Downscaling: Lessons Learned

    NASA Astrophysics Data System (ADS)

    Walton, D.; Hall, A. D.; Sun, F.

    2013-12-01

    In this study, we examine ways to improve statistical downscaling of general circulation model (GCM) output. Why do we downscale GCM output? GCMs have low resolution, so they cannot represent local dynamics and topographic effects that cause spatial heterogeneity in the regional climate change signal. Statistical downscaling recovers fine-scale information by utilizing relationships between the large-scale and fine-scale signals to bridge this gap. In theory, the downscaled climate change signal is more credible and accurate than its GCM counterpart, but in practice, there may be little improvement. Here, we tackle the practical problems that arise in statistical downscaling, using temperature change over the Los Angeles region as a test case. This region is an ideal place to apply downscaling since its complex topography and shoreline are poorly simulated by GCMs. By comparing two popular statistical downscaling methods and one dynamical downscaling method, we identify issues with statistically downscaled climate change signals and develop ways to fix them. We focus on scale mismatch, domain of influence, and other problems - many of which users may be unaware of - and discuss practical solutions.

  13. The period distribution of cataclysmic variables

    NASA Astrophysics Data System (ADS)

    Hameury, J. M.; King, A. R.; Lasota, J. P.; Ritter, H.

    1988-04-01

    In a recent paper, Warner and Livio (1987) claim that the AM Her and SU UMa cataclysmic variables (CVs) with periods P less than 2 hr show a tendency to cluster in disjoint period ranges. It is shown here that the statistical significance of this result is entirely due to the large accumulation of AM Her systems in the range 113.5-114.8 minutes. It has been shown elsewhere that this period spike is probably caused by the resumption of mass transfer after the systems cross the 2-3 hr period gap. It is emphasized that the 'synchronization-induced gap' mechanism of Lamb and Melia (1987) is based on an incorrect assumption about the contraction time scale of a mass-losing secondary star and cannot produce any significant gap in the period distribution of AM Her systems or lead to the formation of ultrashort-period CVs, as claimed by Lamb and Melia.

  14. Flipping the statistics classroom in nursing education.

    PubMed

    Schwartz, Todd A

    2014-04-01

    Flipped classrooms are so named because they substitute the traditional lecture that commonly encompasses the entire class period with active learning techniques, such as small-group work. The lectures are delivered instead by using an alternative mode--video recordings--that are made available for viewing online outside the class period. Due to this inverted approach, students are engaged with the course material during the class period, rather than participating only passively. This flipped approach is gaining popularity in many areas of education due to its enhancement of student learning and represents an opportunity for utilization by instructors of statistics courses in nursing education. This article presents the author's recent experiences with flipping a statistics course for nursing students in a PhD program, including practical considerations and student outcomes and reaction. This transformative experience deepened the level of student learning in a way that may not have occurred using a traditional format. PMID:24654591

  15. Suite versus composite statistics

    USGS Publications Warehouse

    Balsillie, J.H.; Tanner, W.F.

    1999-01-01

    Suite and composite methodologies, two statistically valid approaches for producing statistical descriptive measures, are investigated for sample groups representing a probability distribution where, in addition, each sample is probability distribution. Suite and composite means (first moment measures) are always equivalent. Composite standard deviations (second moment measures) are always larger than suite standard deviations. Suite and composite values for higher moment measures have more complex relationships. Very seldom, however, are they equivalent, and they normally yield statistically significant but different results. Multiple samples are preferable to single samples (including composites) because they permit the investigator to examine sample-to-sample variability. These and other relationships for suite and composite probability distribution analyses are investigated and reported using granulometric data.

  16. Candidate Assembly Statistical Evaluation

    1998-07-15

    The Savannah River Site (SRS) receives aluminum clad spent Material Test Reactor (MTR) fuel from all over the world for storage and eventual reprocessing. There are hundreds of different kinds of MTR fuels and these fuels will continue to be received at SRS for approximately ten more years. SRS''s current criticality evaluation methodology requires the modeling of all MTR fuels utilizing Monte Carlo codes, which is extremely time consuming and resource intensive. Now that amore » significant number of MTR calculations have been conducted it is feasible to consider building statistical models that will provide reasonable estimations of MTR behavior. These statistical models can be incorporated into a standardized model homogenization spreadsheet package to provide analysts with a means of performing routine MTR fuel analyses with a minimal commitment of time and resources. This became the purpose for development of the Candidate Assembly Statistical Evaluation (CASE) program at SRS.« less

  17. Perception in statistical graphics

    NASA Astrophysics Data System (ADS)

    VanderPlas, Susan Ruth

    There has been quite a bit of research on statistical graphics and visualization, generally focused on new types of graphics, new software to create graphics, interactivity, and usability studies. Our ability to interpret and use statistical graphics hinges on the interface between the graph itself and the brain that perceives and interprets it, and there is substantially less research on the interplay between graph, eye, brain, and mind than is sufficient to understand the nature of these relationships. The goal of the work presented here is to further explore the interplay between a static graph, the translation of that graph from paper to mental representation (the journey from eye to brain), and the mental processes that operate on that graph once it is transferred into memory (mind). Understanding the perception of statistical graphics should allow researchers to create more effective graphs which produce fewer distortions and viewer errors while reducing the cognitive load necessary to understand the information presented in the graph. Taken together, these experiments should lay a foundation for exploring the perception of statistical graphics. There has been considerable research into the accuracy of numerical judgments viewers make from graphs, and these studies are useful, but it is more effective to understand how errors in these judgments occur so that the root cause of the error can be addressed directly. Understanding how visual reasoning relates to the ability to make judgments from graphs allows us to tailor graphics to particular target audiences. In addition, understanding the hierarchy of salient features in statistical graphics allows us to clearly communicate the important message from data or statistical models by constructing graphics which are designed specifically for the perceptual system.

  18. Substorm statistics: Occurrences and amplitudes

    SciTech Connect

    Borovsky, J.E.; Nemzek, R.J.

    1994-05-01

    The occurrences and amplitudes of substorms are statistically investigated with the use of three data sets: the AL index, the Los Alamos 3-satellite geosynchronous energetic-electron measurements, and the GOES-5 and -6 geosynchronous magnetic-field measurements. The investigation utilizes {approximately} 13,800 substorms in AL, {approximately} 1400 substorms in the energetic-electron flux, and {approximately} 100 substorms in the magnetic field. The rate of occurrence of substorms is determined as a function of the time of day, the time of year, the amount of magnetotail bending, the orientation of the geomagnetic dipole, the toward/away configuration of the IMF, and the parameters of the solar wind. The relative roles of dayside reconnection and viscous coupling in the production of substorms are assessed. Three amplitudes are defined for a substorms: the jump in the AL index, the peak of the >30-keV integral electron flux at geosynchronous orbit near midnight, and the angle of rotation of the geosynchronous magnetic field near midnight. The substorm amplitudes are statistically analyzed, the amplitude measurements are cross correlated with each other, and the substorm amplitudes are determined as functions of the solar-wind parameters. Periodically occurring and randomly occurring substorms are analyzed separately. The energetic-particle-flux amplitudes are consistent with unloading and the AL amplitudes are consistent with direct driving plus unloading.

  19. 39 CFR 3050.28 - Monthly and pay period reports.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 39 Postal Service 1 2011-07-01 2011-07-01 false Monthly and pay period reports. 3050.28 Section 3050.28 Postal Service POSTAL REGULATORY COMMISSION PERSONNEL PERIODIC REPORTING § 3050.28 Monthly and... Service Active Employee Statistical Summary (HAT report) (pay period)....

  20. MESOSCALE STORM AND DRY PERIOD PARAMETERS FROM HOURLY PRECIPITATION DATA

    EPA Science Inventory

    Hourly precipitation data from 89 first-order National Weather Service stations in the Northeastern United States are used to define seasonal storm (wet-period) and dry-period statistics. Mean values of regional storm and dry-period duration and of precipitation rates for storms ...

  1. Analogies for Understanding Statistics

    ERIC Educational Resources Information Center

    Hocquette, Jean-Francois

    2004-01-01

    This article describes a simple way to explain the limitations of statistics to scientists and students to avoid the publication of misleading conclusions. Biologists examine their results extremely critically and carefully choose the appropriate analytic methods depending on their scientific objectives. However, no such close attention is usually…

  2. Statistical methods in microbiology.

    PubMed Central

    Ilstrup, D M

    1990-01-01

    Statistical methodology is viewed by the average laboratory scientist, or physician, sometimes with fear and trepidation, occasionally with loathing, and seldom with fondness. Statistics may never be loved by the medical community, but it does not have to be hated by them. It is true that statistical science is sometimes highly mathematical, always philosophical, and occasionally obtuse, but for the majority of medical studies it can be made palatable. The goal of this article has been to outline a finite set of methods of analysis that investigators should choose based on the nature of the variable being studied and the design of the experiment. The reader is encouraged to seek the advice of a professional statistician when there is any doubt about the appropriate method of analysis. A statistician can also help the investigator with problems that have nothing to do with statistical tests, such as quality control, choice of response variable and comparison groups, randomization, and blinding of assessment of response variables. PMID:2200604

  3. Statistical Energy Analysis Program

    NASA Technical Reports Server (NTRS)

    Ferebee, R. C.; Trudell, R. W.; Yano, L. I.; Nygaard, S. I.

    1985-01-01

    Statistical Energy Analysis (SEA) is powerful tool for estimating highfrequency vibration spectra of complex structural systems and incorporated into computer program. Basic SEA analysis procedure divided into three steps: Idealization, parameter generation, and problem solution. SEA computer program written in FORTRAN V for batch execution.

  4. Statistical Significance Testing.

    ERIC Educational Resources Information Center

    McLean, James E., Ed.; Kaufman, Alan S., Ed.

    1998-01-01

    The controversy about the use or misuse of statistical significance testing has become the major methodological issue in educational research. This special issue contains three articles that explore the controversy, three commentaries on these articles, an overall response, and three rejoinders by the first three authors. They are: (1)…

  5. Spitball Scatterplots in Statistics

    ERIC Educational Resources Information Center

    Wagaman, John C.

    2012-01-01

    This paper describes an active learning idea that I have used in my applied statistics class as a first lesson in correlation and regression. Students propel spitballs from various standing distances from the target and use the recorded data to determine if the spitball accuracy is associated with standing distance and review the algebra of lines…

  6. Lack of Statistical Significance

    ERIC Educational Resources Information Center

    Kehle, Thomas J.; Bray, Melissa A.; Chafouleas, Sandra M.; Kawano, Takuji

    2007-01-01

    Criticism has been leveled against the use of statistical significance testing (SST) in many disciplines. However, the field of school psychology has been largely devoid of critiques of SST. Inspection of the primary journals in school psychology indicated numerous examples of SST with nonrandom samples and/or samples of convenience. In this…

  7. Juvenile Court Statistics - 1972.

    ERIC Educational Resources Information Center

    Office of Youth Development (DHEW), Washington, DC.

    This report is a statistical study of juvenile court cases in 1972. The data demonstrates how the court is frequently utilized in dealing with juvenile delinquency by the police as well as by other community agencies and parents. Excluded from this report are the ordinary traffic cases handled by juvenile court. The data indicate that: (1) in…

  8. Library Research and Statistics.

    ERIC Educational Resources Information Center

    Lynch, Mary Jo; St. Lifer, Evan; Halstead, Kent; Fox, Bette-Lee; Miller, Marilyn L.; Shontz, Marilyn L.

    2001-01-01

    These nine articles discuss research and statistics on libraries and librarianship, including libraries in the United States, Canada, and Mexico; acquisition expenditures in public, academic, special, and government libraries; price indexes; state rankings of public library data; library buildings; expenditures in school library media centers; and…

  9. Foundations of Statistical Seismology

    NASA Astrophysics Data System (ADS)

    Vere-Jones, David

    2010-06-01

    A brief account is given of the principles of stochastic modelling in seismology, with special regard to the role and development of stochastic models for seismicity. Stochastic models are seen as arising in a hierarchy of roles in seismology, as in other scientific disciplines. At their simplest, they provide a convenient descriptive tool for summarizing data patterns; in engineering and other applications, they provide a practical way of bridging the gap between the detailed modelling of a complex system, and the need to fit models to limited data; at the most fundamental level they arise as a basic component in the modelling of earthquake phenomena, analogous to that of stochastic models in statistical mechanics or turbulence theory. As an emerging subdiscipline, statistical seismology includes elements of all of these. The scope for the development of stochastic models depends crucially on the quantity and quality of the available data. The availability of extensive, high-quality catalogues and other relevant data lies behind the recent explosion of interest in statistical seismology. At just such a stage, it seems important to review the underlying principles on which statistical modelling is based, and that is the main purpose of the present paper.

  10. Graduate Statistics: Student Attitudes

    ERIC Educational Resources Information Center

    Kennedy, Robert L.; Broadston, Pamela M.

    2004-01-01

    This study investigated the attitudes toward statistics of graduate students who used a computer program as part of the instruction, which allowed for an individualized, self-paced, student-centered, activity-based course. The twelve sections involved in this study were offered in the spring and fall 2001, spring and fall 2002, spring and fall…

  11. Geopositional Statistical Methods

    NASA Technical Reports Server (NTRS)

    Ross, Kenton

    2006-01-01

    RMSE based methods distort circular error estimates (up to 50% overestimation). The empirical approach is the only statistically unbiased estimator offered. Ager modification to Shultz approach is nearly unbiased, but cumbersome. All methods hover around 20% uncertainty (@ 95% confidence) for low geopositional bias error estimates. This requires careful consideration in assessment of higher accuracy products.

  12. Statistical Reasoning over Lunch

    ERIC Educational Resources Information Center

    Selmer, Sarah J.; Bolyard, Johnna J.; Rye, James A.

    2011-01-01

    Students in the 21st century are exposed daily to a staggering amount of numerically infused media. In this era of abundant numeric data, students must be able to engage in sound statistical reasoning when making life decisions after exposure to varied information. The context of nutrition can be used to engage upper elementary and middle school…

  13. Fractional statistics and confinement

    NASA Astrophysics Data System (ADS)

    Gaete, P.; Wotzasek, C.

    2005-02-01

    It is shown that a pointlike composite having charge and magnetic moment displays a confining potential for the static interaction while simultaneously obeying fractional statistics in a pure gauge theory in three dimensions, without a Chern-Simons term. This result is distinct from the Maxwell-Chern-Simons theory that shows a screening nature for the potential.

  14. Statistics for Learning Genetics

    ERIC Educational Resources Information Center

    Charles, Abigail Sheena

    2012-01-01

    This study investigated the knowledge and skills that biology students may need to help them understand statistics/mathematics as it applies to genetics. The data are based on analyses of current representative genetics texts, practicing genetics professors' perspectives, and more directly, students' perceptions of, and performance in,…

  15. Statistics for Learning Genetics

    NASA Astrophysics Data System (ADS)

    Charles, Abigail Sheena

    This study investigated the knowledge and skills that biology students may need to help them understand statistics/mathematics as it applies to genetics. The data are based on analyses of current representative genetics texts, practicing genetics professors' perspectives, and more directly, students' perceptions of, and performance in, doing statistically-based genetics problems. This issue is at the emerging edge of modern college-level genetics instruction, and this study attempts to identify key theoretical components for creating a specialized biological statistics curriculum. The goal of this curriculum will be to prepare biology students with the skills for assimilating quantitatively-based genetic processes, increasingly at the forefront of modern genetics. To fulfill this, two college level classes at two universities were surveyed. One university was located in the northeastern US and the other in the West Indies. There was a sample size of 42 students and a supplementary interview was administered to a select 9 students. Interviews were also administered to professors in the field in order to gain insight into the teaching of statistics in genetics. Key findings indicated that students had very little to no background in statistics (55%). Although students did perform well on exams with 60% of the population receiving an A or B grade, 77% of them did not offer good explanations on a probability question associated with the normal distribution provided in the survey. The scope and presentation of the applicable statistics/mathematics in some of the most used textbooks in genetics teaching, as well as genetics syllabi used by instructors do not help the issue. It was found that the text books, often times, either did not give effective explanations for students, or completely left out certain topics. The omission of certain statistical/mathematical oriented topics was seen to be also true with the genetics syllabi reviewed for this study. Nonetheless

  16. The Statistical Drake Equation

    NASA Astrophysics Data System (ADS)

    Maccone, Claudio

    2010-12-01

    We provide the statistical generalization of the Drake equation. From a simple product of seven positive numbers, the Drake equation is now turned into the product of seven positive random variables. We call this "the Statistical Drake Equation". The mathematical consequences of this transformation are then derived. The proof of our results is based on the Central Limit Theorem (CLT) of Statistics. In loose terms, the CLT states that the sum of any number of independent random variables, each of which may be ARBITRARILY distributed, approaches a Gaussian (i.e. normal) random variable. This is called the Lyapunov Form of the CLT, or the Lindeberg Form of the CLT, depending on the mathematical constraints assumed on the third moments of the various probability distributions. In conclusion, we show that: The new random variable N, yielding the number of communicating civilizations in the Galaxy, follows the LOGNORMAL distribution. Then, as a consequence, the mean value of this lognormal distribution is the ordinary N in the Drake equation. The standard deviation, mode, and all the moments of this lognormal N are also found. The seven factors in the ordinary Drake equation now become seven positive random variables. The probability distribution of each random variable may be ARBITRARY. The CLT in the so-called Lyapunov or Lindeberg forms (that both do not assume the factors to be identically distributed) allows for that. In other words, the CLT "translates" into our statistical Drake equation by allowing an arbitrary probability distribution for each factor. This is both physically realistic and practically very useful, of course. An application of our statistical Drake equation then follows. The (average) DISTANCE between any two neighboring and communicating civilizations in the Galaxy may be shown to be inversely proportional to the cubic root of N. Then, in our approach, this distance becomes a new random variable. We derive the relevant probability density

  17. The Statistical Fermi Paradox

    NASA Astrophysics Data System (ADS)

    Maccone, C.

    In this paper is provided the statistical generalization of the Fermi paradox. The statistics of habitable planets may be based on a set of ten (and possibly more) astrobiological requirements first pointed out by Stephen H. Dole in his book Habitable planets for man (1964). The statistical generalization of the original and by now too simplistic Dole equation is provided by replacing a product of ten positive numbers by the product of ten positive random variables. This is denoted the SEH, an acronym standing for “Statistical Equation for Habitables”. The proof in this paper is based on the Central Limit Theorem (CLT) of Statistics, stating that the sum of any number of independent random variables, each of which may be ARBITRARILY distributed, approaches a Gaussian (i.e. normal) random variable (Lyapunov form of the CLT). It is then shown that: 1. The new random variable NHab, yielding the number of habitables (i.e. habitable planets) in the Galaxy, follows the log- normal distribution. By construction, the mean value of this log-normal distribution is the total number of habitable planets as given by the statistical Dole equation. 2. The ten (or more) astrobiological factors are now positive random variables. The probability distribution of each random variable may be arbitrary. The CLT in the so-called Lyapunov or Lindeberg forms (that both do not assume the factors to be identically distributed) allows for that. In other words, the CLT "translates" into the SEH by allowing an arbitrary probability distribution for each factor. This is both astrobiologically realistic and useful for any further investigations. 3. By applying the SEH it is shown that the (average) distance between any two nearby habitable planets in the Galaxy may be shown to be inversely proportional to the cubic root of NHab. This distance is denoted by new random variable D. The relevant probability density function is derived, which was named the "Maccone distribution" by Paul Davies in

  18. Information geometry of Bayesian statistics

    NASA Astrophysics Data System (ADS)

    Matsuzoe, Hiroshi

    2015-01-01

    A survey of geometry of Bayesian statistics is given. From the viewpoint of differential geometry, a prior distribution in Bayesian statistics is regarded as a volume element on a statistical model. In this paper, properties of Bayesian estimators are studied by applying equiaffine structures of statistical manifolds. In addition, geometry of anomalous statistics is also studied. Deformed expectations and deformed independeces are important in anomalous statistics. After summarizing geometry of such deformed structues, a generalization of maximum likelihood method is given. A suitable weight on a parameter space is important in Bayesian statistics, whereas a suitable weight on a sample space is important in anomalous statistics.

  19. Statistical Analysis of Refractivity in UAE

    NASA Astrophysics Data System (ADS)

    Al-Ansari, Kifah; Al-Mal, Abdulhadi Abu; Kamel, Rami

    2007-07-01

    This paper presents the results of the refractivity statistics in the UAE (United Arab Emirates) for a period of 14 years (1990-2003). Six sites have been considered using meteorological surface data (Abu Dhabi, Dubai, Sharjah, Al-Ain, Ras Al-Kaimah, and Al-Fujairah). Upper air (radiosonde) data were available at one site only, Abu Dhabi airport, which has been considered for the refractivity gradient statistics. Monthly and yearly averages are obtained for the two parameters, refractivity and refractivity gradient. Cumulative distributions are also provided.

  20. Statistical Transmutation in Floquet Driven Optical Lattices

    NASA Astrophysics Data System (ADS)

    Sedrakyan, Tigran A.; Galitski, Victor M.; Kamenev, Alex

    2015-11-01

    We show that interacting bosons in a periodically driven two dimensional (2D) optical lattice may effectively exhibit fermionic statistics. The phenomenon is similar to the celebrated Tonks-Girardeau regime in 1D. The Floquet band of a driven lattice develops the moat shape, i.e., a minimum along a closed contour in the Brillouin zone. Such degeneracy of the kinetic energy favors fermionic quasiparticles. The statistical transmutation is achieved by the Chern-Simons flux attachment similar to the fractional quantum Hall case. We show that the velocity distribution of the released bosons is a sensitive probe of the fermionic nature of their stationary Floquet state.

  1. Statistical Transmutation in Floquet Driven Optical Lattices.

    PubMed

    Sedrakyan, Tigran A; Galitski, Victor M; Kamenev, Alex

    2015-11-01

    We show that interacting bosons in a periodically driven two dimensional (2D) optical lattice may effectively exhibit fermionic statistics. The phenomenon is similar to the celebrated Tonks-Girardeau regime in 1D. The Floquet band of a driven lattice develops the moat shape, i.e., a minimum along a closed contour in the Brillouin zone. Such degeneracy of the kinetic energy favors fermionic quasiparticles. The statistical transmutation is achieved by the Chern-Simons flux attachment similar to the fractional quantum Hall case. We show that the velocity distribution of the released bosons is a sensitive probe of the fermionic nature of their stationary Floquet state. PMID:26588392

  2. Statistical Fault Detection & Diagnosis Expert System

    1996-12-18

    STATMON is an expert system that performs real-time fault detection and diagnosis of redundant sensors in any industrial process requiring high reliability. After a training period performed during normal operation, the expert system monitors the statistical properties of the incoming signals using a pattern recognition test. If the test determines that statistical properties of the signals have changed, the expert system performs a sequence of logical steps to determine which sensor or machine component hasmore » degraded.« less

  3. Statistical Inference at Work: Statistical Process Control as an Example

    ERIC Educational Resources Information Center

    Bakker, Arthur; Kent, Phillip; Derry, Jan; Noss, Richard; Hoyles, Celia

    2008-01-01

    To characterise statistical inference in the workplace this paper compares a prototypical type of statistical inference at work, statistical process control (SPC), with a type of statistical inference that is better known in educational settings, hypothesis testing. Although there are some similarities between the reasoning structure involved in…

  4. Fermions from classical statistics

    SciTech Connect

    Wetterich, C.

    2010-12-15

    We describe fermions in terms of a classical statistical ensemble. The states {tau} of this ensemble are characterized by a sequence of values one or zero or a corresponding set of two-level observables. Every classical probability distribution can be associated to a quantum state for fermions. If the time evolution of the classical probabilities p{sub {tau}} amounts to a rotation of the wave function q{sub {tau}}(t)={+-}{radical}(p{sub {tau}}(t)), we infer the unitary time evolution of a quantum system of fermions according to a Schroedinger equation. We establish how such classical statistical ensembles can be mapped to Grassmann functional integrals. Quantum field theories for fermions arise for a suitable time evolution of classical probabilities for generalized Ising models.

  5. Statistics in disease ecology

    PubMed Central

    Waller, Lance A.

    2008-01-01

    The three papers included in this special issue represent a set of presentations in an invited session on disease ecology at the 2005 Spring Meeting of the Eastern North American Region of the International Biometric Society. The papers each address statistical estimation and inference for particular components of different disease processes and, taken together, illustrate the breadth of statistical issues arising in the study of the ecology and public health impact of disease. As an introduction, we provide a very brief overview of the area of “disease ecology”, a variety of synonyms addressing different aspects of disease ecology, and present a schematic structure illustrating general components of the underlying disease process, data collection issues, and different disciplinary perspectives ranging from microbiology to public health surveillance. PMID:19081740

  6. Automated Periodical Reference Service.

    ERIC Educational Resources Information Center

    Ellefsen, David

    1985-01-01

    Describes public library reference service which allows patrons to type out search instructions on a computer terminal, review and select references, and receive, by high-speed printer, facsimile copy of selected periodical articles. Development of periodicals center at main county library and use of self-coaching SEARCH HELPER system are…

  7. The Living Periodic Table

    ERIC Educational Resources Information Center

    Nahlik, Mary Schrodt

    2005-01-01

    To help make the abstract world of chemistry more concrete eighth-grade students, the author has them create a living periodic table that can be displayed in the classroom or hallway. This display includes information about the elements arranged in the traditional periodic table format, but also includes visual real-world representations of the…

  8. 1979 DOE statistical symposium

    SciTech Connect

    Gardiner, D.A.; Truett T.

    1980-09-01

    The 1979 DOE Statistical Symposium was the fifth in the series of annual symposia designed to bring together statisticians and other interested parties who are actively engaged in helping to solve the nation's energy problems. The program included presentations of technical papers centered around exploration and disposal of nuclear fuel, general energy-related topics, and health-related issues, and workshops on model evaluation, risk analysis, analysis of large data sets, and resource estimation.

  9. Understanding British addiction statistics.

    PubMed

    Johnson, B D

    1975-01-01

    The statistical data issued by the Home Office and Department of Health and Social Security are quite detailed and generally valid measures of hard core addiction in Great Britain (Judson, 1973). Since 1968, the main basis of these high quality British statistics is the routine reports filed by Drug Treatment Centres. The well-trained, experienced staff of these clinics make knowledgeable dicsions about a cleint's addiction, efficiently regulate dosage, and otherwise exert some degree of control over addicts (Judson, 1973; Johnson, 1974). The co-operation of police, courts, prison physicians, and general practitioners is also valuable in collecting data on drug addiction and convictions. Information presented in the tables above indicates that a rising problem of herion addiction between 1962 and 1967 were arrested by the introduction of the treatment clinics in 1968. Further, legally maintained heroin addiction has been reduced by almost one-third since 1968, since many herion addicts have been transferred to injectable methadone. The decline in herion prescribing and the relatively steady number of narcotics addicts has apparently occurred in the face of a continuing, and perhaps increasing, demand for heroin and other opiates. With few exceptions of a minor nature analysis of various tables suggests that the official statistics are internally consistent. There are apparently few "hidden" addicts, since few unknown addicts die of overdoses or are arrested by police (Lewis, 1973), although Blumberg (1974) indicates that some unknown users may exist. In addition, may opitate usersnot officially notified are known by clinic doctors as friends of addicts receiving prescriptions (Judson, 1973; Home Office, 1974). In brief, offical British drug statistics seem to be generally valid and demonstrate that heroin and perhaps methadone addiction has been well contained by the treatment clinics. PMID:1039283

  10. Statistical Methods in Cosmology

    NASA Astrophysics Data System (ADS)

    Verde, L.

    2010-03-01

    The advent of large data-set in cosmology has meant that in the past 10 or 20 years our knowledge and understanding of the Universe has changed not only quantitatively but also, and most importantly, qualitatively. Cosmologists rely on data where a host of useful information is enclosed, but is encoded in a non-trivial way. The challenges in extracting this information must be overcome to make the most of a large experimental effort. Even after having converged to a standard cosmological model (the LCDM model) we should keep in mind that this model is described by 10 or more physical parameters and if we want to study deviations from it, the number of parameters is even larger. Dealing with such a high dimensional parameter space and finding parameters constraints is a challenge on itself. Cosmologists want to be able to compare and combine different data sets both for testing for possible disagreements (which could indicate new physics) and for improving parameter determinations. Finally, cosmologists in many cases want to find out, before actually doing the experiment, how much one would be able to learn from it. For all these reasons, sophisiticated statistical techniques are being employed in cosmology, and it has become crucial to know some statistical background to understand recent literature in the field. I will introduce some statistical tools that any cosmologist should know about in order to be able to understand recently published results from the analysis of cosmological data sets. I will not present a complete and rigorous introduction to statistics as there are several good books which are reported in the references. The reader should refer to those.

  11. Quantum U-statistics

    SciTech Connect

    Guta, Madalin; Butucea, Cristina

    2010-10-15

    The notion of a U-statistic for an n-tuple of identical quantum systems is introduced in analogy to the classical (commutative) case: given a self-adjoint 'kernel' K acting on (C{sup d}){sup '}x{sup r} with rstatistics converges in moments to a linear combination of Hermite polynomials in canonical variables of a canonical commutation relation algebra defined through the quantum central limit theorem. In the special cases of nondegenerate kernels and kernels of order of 2, it is shown that the convergence holds in the stronger distribution sense. Two types of applications in quantum statistics are described: testing beyond the two simple hypotheses scenario and quantum metrology with interacting Hamiltonians.

  12. Statistics in fusion experiments

    NASA Astrophysics Data System (ADS)

    McNeill, D. H.

    1997-11-01

    Since the reasons for the variability in data from plasma experiments are often unknown or uncontrollable, statistical methods must be applied. Reliable interpretation and public accountability require full data sets. Two examples of data misrepresentation at PPPL are analyzed: Te >100 eV on S-1 spheromak.(M. Yamada, Nucl. Fusion 25, 1327 (1985); reports to DoE; etc.) The reported high values (statistical artifacts of Thomson scattering measurements) were selected from a mass of data with an average of 40 eV or less. ``Correlated'' spectroscopic data were meaningless. (2) Extrapolation to Q >=0.5 for DT in TFTR.(D. Meade et al., IAEA Baltimore (1990), V. 1, p. 9; H. P. Furth, Statements to U. S. Congress (1989).) The DD yield used there was the highest through 1990 (>= 50% above average) and the DT to DD power ratio used was about twice any published value. Average DD yields and published yield ratios scale to Q<0.15 for DT, in accord with the observed performance over the last 3 1/2 years. Press reports of outlier data from TFTR have obscured the fact that the DT behavior follows from trivial scaling of the DD data. Good practice in future fusion research would have confidence intervals and other descriptive statistics accompanying reported numerical values (cf. JAMA).

  13. Fast statistical alignment.

    PubMed

    Bradley, Robert K; Roberts, Adam; Smoot, Michael; Juvekar, Sudeep; Do, Jaeyoung; Dewey, Colin; Holmes, Ian; Pachter, Lior

    2009-05-01

    We describe a new program for the alignment of multiple biological sequences that is both statistically motivated and fast enough for problem sizes that arise in practice. Our Fast Statistical Alignment program is based on pair hidden Markov models which approximate an insertion/deletion process on a tree and uses a sequence annealing algorithm to combine the posterior probabilities estimated from these models into a multiple alignment. FSA uses its explicit statistical model to produce multiple alignments which are accompanied by estimates of the alignment accuracy and uncertainty for every column and character of the alignment--previously available only with alignment programs which use computationally-expensive Markov Chain Monte Carlo approaches--yet can align thousands of long sequences. Moreover, FSA utilizes an unsupervised query-specific learning procedure for parameter estimation which leads to improved accuracy on benchmark reference alignments in comparison to existing programs. The centroid alignment approach taken by FSA, in combination with its learning procedure, drastically reduces the amount of false-positive alignment on biological data in comparison to that given by other methods. The FSA program and a companion visualization tool for exploring uncertainty in alignments can be used via a web interface at http://orangutan.math.berkeley.edu/fsa/, and the source code is available at http://fsa.sourceforge.net/. PMID:19478997

  14. Wavelet periodicity detection algorithms

    NASA Astrophysics Data System (ADS)

    Benedetto, John J.; Pfander, Goetz E.

    1998-10-01

    This paper deals with the analysis of time series with respect to certain known periodicities. In particular, we shall present a fast method aimed at detecting periodic behavior inherent in noise data. The method is composed of three steps: (1) Non-noisy data are analyzed through spectral and wavelet methods to extract specific periodic patterns of interest. (2) Using these patterns, we construct an optimal piecewise constant wavelet designed to detect the underlying periodicities. (3) We introduce a fast discretized version of the continuous wavelet transform, as well as waveletgram averaging techniques, to detect occurrence and period of these periodicities. The algorithm is formulated to provide real time implementation. Our procedure is generally applicable to detect locally periodic components in signals s which can be modeled as s(t) equals A(t)F(h(t)) + N(t) for t in I, where F is a periodic signal, A is a non-negative slowly varying function, and h is strictly increasing with h' slowly varying, N denotes background activity. For example, the method can be applied in the context of epileptic seizure detection. In this case, we try to detect seizure periodics in EEG and ECoG data. In the case of ECoG data, N is essentially 1/f noise. In the case of EEG data and for t in I,N includes noise due to cranial geometry and densities. In both cases N also includes standard low frequency rhythms. Periodicity detection has other applications including ocean wave prediction, cockpit motion sickness prediction, and minefield detection.

  15. Experimental Mathematics and Computational Statistics

    SciTech Connect

    Bailey, David H.; Borwein, Jonathan M.

    2009-04-30

    The field of statistics has long been noted for techniques to detect patterns and regularities in numerical data. In this article we explore connections between statistics and the emerging field of 'experimental mathematics'. These includes both applications of experimental mathematics in statistics, as well as statistical methods applied to computational mathematics.

  16. Truth, Damn Truth, and Statistics

    ERIC Educational Resources Information Center

    Velleman, Paul F.

    2008-01-01

    Statisticians and Statistics teachers often have to push back against the popular impression that Statistics teaches how to lie with data. Those who believe incorrectly that Statistics is solely a branch of Mathematics (and thus algorithmic), often see the use of judgment in Statistics as evidence that we do indeed manipulate our results. In the…

  17. Assessing the statistical significance of periodogram peaks

    NASA Astrophysics Data System (ADS)

    Baluev, R. V.

    2008-04-01

    The least-squares (or Lomb-Scargle) periodogram is a powerful tool that is routinely used in many branches of astronomy to search for periodicities in observational data. The problem of assessing the statistical significance of candidate periodicities for a number of periodograms is considered. Based on results in extreme value theory, improved analytic estimations of false alarm probabilities are given. These include an upper limit to the false alarm probability (or a lower limit to the significance). The estimations are tested numerically in order to establish regions of their practical applicability.

  18. Periodized Daubechies wavelets

    SciTech Connect

    Restrepo, J.M.; Leaf, G.K.; Schlossnagle, G.

    1996-03-01

    The properties of periodized Daubechies wavelets on [0,1] are detailed and counterparts which form a basis for L{sup 2}(R). Numerical examples illustrate the analytical estimates for convergence and demonstrated by comparison with Fourier spectral methods the superiority of wavelet projection methods for approximations. The analytical solution to inner products of periodized wavelets and their derivatives, which are known as connection coefficients, is presented, and their use ius illustrated in the approximation of two commonly used differential operators. The periodization of the connection coefficients in Galerkin schemes is presented in detail.

  19. Genealogy of periodic trajectories

    SciTech Connect

    de Adguiar, M.A.M.; Maldta, C.P.; de Passos, E.J.V.

    1986-05-20

    The periodic solutions of non-integrable classical Hamiltonian systems with two degrees of freedom are numerically investigated. Curves of periodic families are given in plots of energy vs. period. Results are presented for this Hamiltonian: H = 1/2(p/sub x//sup 2/ + p/sub y//sup 2/) + 1/2 x/sup 2/ + 3/2 y/sup 2/ - x/sup 2/y + 1/12 x/sup 4/. Properties of the families of curves are pointed out. (LEW)

  20. The Fast Chi-Squared Period Search For Variable Stars

    NASA Astrophysics Data System (ADS)

    Palmer, D. M.

    2002-05-01

    I present the Fast Chi-Squared method for detecting periodicity in variable sources. This algorithm uses the full statistical power available in the data set to find the optimal fit to a periodic function with an arbitrary number of Fourier components. It automatically compensates for non-uniform errors, sampling periodicity, sampling aperiodicity, and windowing. The result is a statistically meaningful (chi-squared) periodicity detection strength as an arbitrarily dense function of frequency. The algorithm is FFT based, running in order O(N log N) time, and allows large data sets over long time intervals to be trawled with high frequency resolution in a practical amount of CPU time.

  1. NASA Pocket Statistics

    NASA Technical Reports Server (NTRS)

    1994-01-01

    Pocket Statistics is published for the use of NASA managers and their staff. Included herein is Administrative and Organizational information, summaries of Space Flight Activity including the NASA Major Launch Record, and NASA Procurement, Financial, and Manpower data. The NASA Major Launch Record includes all launches of Scout class and larger vehicles. Vehicle and spacecraft development flights are also included in the Major Launch Record. Shuttle missions are counted as one launch and one payload, where free flying payloads are not involved. Satellites deployed from the cargo bay of the Shuttle and placed in a separate orbit or trajectory are counted as an additional payload.

  2. Who Needs Statistics? | Poster

    Cancer.gov

    You may know the feeling. You have collected a lot of new data on an important experiment. Now you are faced with multiple groups of data, a sea of numbers, and a deadline for submitting your paper to a peer-reviewed journal. And you are not sure which data are relevant, or even the best way to present them. The statisticians at Data Management Services (DMS) know how to help. This small group of experts provides a wide array of statistical and mathematical consulting services to the scientific community at NCI at Frederick and NCI-Bethesda.

  3. NASA Pocket Statistics

    NASA Technical Reports Server (NTRS)

    1995-01-01

    NASA Pocket Statistics is published for the use of NASA managers and their staff. Included herein is Administrative and Organizational information, summaries of Space Flight Activity including the NASA Major Launch Record, and NASA Procurement, Financial, and Manpower data. The NASA Major Launch Record includes all launches of Scout class and larger vehicles. Vehicle and spacecraft development flights are also included in the Major Launch Record. Shuttle missions are counted as one launch and one payload, where free flying payloads are not involved. Satellites deployed from the cargo bay of the Shuttle and placed in a separate orbit or trajectory are counted as an additional payload.

  4. NASA Pocket Statistics

    NASA Technical Reports Server (NTRS)

    1996-01-01

    This booklet of pocket statistics includes the 1996 NASA Major Launch Record, NASA Procurement, Financial, and Workforce data. The NASA Major Launch Record includes all launches of Scout class and larger vehicles. Vehicle and spacecraft development flights are also included in the Major Luanch Record. Shuttle missions are counted as one launch and one payload, where free flying payloads are not involved. Satellites deployed from the cargo bay of the Shuttle and placed in a separate orbit or trajectory are counted as an additional payload.

  5. International petroleum statistics report

    SciTech Connect

    1995-10-01

    The International Petroleum Statistics Report is a monthly publication that provides current international oil data. This report presents data on international oil production, demand, imports, exports and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). Section 2 presents an oil supply/demand balance for the world, in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries.

  6. Statistics: are we related?

    PubMed

    Scott, M; Flaherty, D; Currall, J

    2013-03-01

    This short addition to our series on clinical statistics concerns relationships, and answering questions such as "are blood pressure and weight related?" In a later article, we will answer the more interesting question about how they might be related. This article follows on logically from the previous one dealing with categorical data, the major difference being here that we will consider two continuous variables, which naturally leads to the use of a Pearson correlation or occasionally to a Spearman rank correlation coefficient. PMID:23458641

  7. Statistics of atmospheric correlations.

    PubMed

    Santhanam, M S; Patra, P K

    2001-07-01

    For a large class of quantum systems, the statistical properties of their spectrum show remarkable agreement with random matrix predictions. Recent advances show that the scope of random matrix theory is much wider. In this work, we show that the random matrix approach can be beneficially applied to a completely different classical domain, namely, to the empirical correlation matrices obtained from the analysis of the basic atmospheric parameters that characterize the state of atmosphere. We show that the spectrum of atmospheric correlation matrices satisfy the random matrix prescription. In particular, the eigenmodes of the atmospheric empirical correlation matrices that have physical significance are marked by deviations from the eigenvector distribution. PMID:11461326

  8. NASA Pocket Statistics

    NASA Technical Reports Server (NTRS)

    1993-01-01

    Pocket Statistics is published for the use of NASA managers and their staff. Included herein is Administrative and Organizational information, summaries of Space Flight Activity including the NASA Major Launch Record, and NASA Procurement, Financial, and Manpower data. The NASA Major Launch Record includes all launches of Scout class and larger vehicles. Vehicle and spacecraft development flights are also included in the Major Launch Record. Shuttle missions are counted as one launch and one payload, where free flying payloads are not involved. Satellites deployed from the cargo bay of the Shuttle and placed in a separate orbit or trajectory are counted as an additional payload.

  9. Hypokalemic periodic paralysis

    MedlinePlus

    ... that may be due to this condition include: Kidney stones (a side effect of acetazolamide) Irregular heartbeat during ... 2016:chap 99. Read More Breathing difficulty Carbohydrates Kidney stones Potassium test Thyrotoxic periodic paralysis Weakness Update Date ...

  10. Thyrotoxic periodic paralysis

    MedlinePlus

    ... high levels of thyroid hormone in their blood ( hyperthyroidism , thyrotoxicosis). Causes This is a rare condition that ... include a family history of periodic paralysis and hyperthyroidism. Symptoms Symptoms involve attacks of muscle weakness or ...

  11. Vaginal bleeding between periods

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003156.htm Vaginal bleeding between periods To use the sharing features ... this page, please enable JavaScript. This article discusses vaginal bleeding that occurs between a woman's monthly menstrual ...

  12. Painful periods (dysmenorrhea) (image)

    MedlinePlus

    ... may be caused by abnormal conditions such as endometriosis or pelvic inflammatory disease. Unless one of these potentially serious conditions is present, the treatment for painful periods is pain relief. If a ...

  13. Your First Period

    MedlinePlus

    ... severe asthma). Always follow the directions on the bottle about how much to take. Exercise. Place a ... days. Glossary Amenorrhea: The absence of menstrual periods. Egg: The female reproductive cell produced in and released ...

  14. Setting the Periodic Table.

    ERIC Educational Resources Information Center

    Saturnelli, Annette

    1985-01-01

    Examines problems resulting from different forms of the periodic table, indicating that New York State schools use a form reflecting the International Union of Pure and Applied Chemistry's 1984 recommendations. Other formats used and reasons for standardization are discussed. (DH)

  15. The Periodic Table CD.

    ERIC Educational Resources Information Center

    Banks, Alton J.; Holmes, Jon L.

    1995-01-01

    Describes the characteristics of the digitized version of The Periodic Table Videodisc. Provides details about the organization of information and access to the data via Macintosh and Windows computers. (DDR)

  16. Painful periods (dysmenorrhea) (image)

    MedlinePlus

    Primary dysmenorrhea is a normal cramping of the lower abdomen caused by hormone-induced uterine contractions before the period. Secondary dysmenorrhea may be caused by abnormal conditions such as ...

  17. Relationship between Graduate Students' Statistics Self-Efficacy, Statistics Anxiety, Attitude toward Statistics, and Social Support

    ERIC Educational Resources Information Center

    Perepiczka, Michelle; Chandler, Nichelle; Becerra, Michael

    2011-01-01

    Statistics plays an integral role in graduate programs. However, numerous intra- and interpersonal factors may lead to successful completion of needed coursework in this area. The authors examined the extent of the relationship between self-efficacy to learn statistics and statistics anxiety, attitude towards statistics, and social support of 166…

  18. [Comment on] Statistical discrimination

    NASA Astrophysics Data System (ADS)

    Chinn, Douglas

    In the December 8, 1981, issue of Eos, a news item reported the conclusion of a National Research Council study that sexual discrimination against women with Ph.D.'s exists in the field of geophysics. Basically, the item reported that even when allowances are made for motherhood the percentage of female Ph.D.'s holding high university and corporate positions is significantly lower than the percentage of male Ph.D.'s holding the same types of positions. The sexual discrimination conclusion, based only on these statistics, assumes that there are no basic psychological differences between men and women that might cause different populations in the employment group studied. Therefore, the reasoning goes, after taking into account possible effects from differences related to anatomy, such as women stopping their careers in order to bear and raise children, the statistical distributions of positions held by male and female Ph.D.'s ought to be very similar to one another. Any significant differences between the distributions must be caused primarily by sexual discrimination.

  19. International petroleum statistics report

    SciTech Connect

    1997-05-01

    The International Petroleum Statistics Report is a monthly publication that provides current international oil data. This report is published for the use of Members of Congress, Federal agencies, State agencies, industry, and the general public. Publication of this report is in keeping with responsibilities given the Energy Information Administration in Public Law 95-91. The International Petroleum Statistics Report presents data on international oil production, demand, imports, and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). This section contains annual data beginning in 1985, and monthly data for the most recent two years. Section 2 presents an oil supply/demand balance for the world. This balance is presented in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. This section contains annual data for the most recent year, quarterly data for the most recent two quarters, and monthly data for the most recent twelve months. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries. World oil production and OECD demand data are for the years 1970 through 1995; OECD stocks from 1973 through 1995; and OECD trade from 1985 through 1995.

  20. Statistical clumped isotope signatures

    PubMed Central

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  1. Statistical clumped isotope signatures.

    PubMed

    Röckmann, T; Popa, M E; Krol, M C; Hofmann, M E G

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  2. Fragile entanglement statistics

    NASA Astrophysics Data System (ADS)

    Brody, Dorje C.; Hughston, Lane P.; Meier, David M.

    2015-10-01

    If X and Y are independent, Y and Z are independent, and so are X and Z, one might be tempted to conclude that X, Y, and Z are independent. But it has long been known in classical probability theory that, intuitive as it may seem, this is not true in general. In quantum mechanics one can ask whether analogous statistics can emerge for configurations of particles in certain types of entangled states. The explicit construction of such states, along with the specification of suitable sets of observables that have the purported statistical properties, is not entirely straightforward. We show that an example of such a configuration arises in the case of an N-particle GHZ state, and we are able to identify a family of observables with the property that the associated measurement outcomes are independent for any choice of 2,3,\\ldots ,N-1 of the particles, even though the measurement outcomes for all N particles are not independent. Although such states are highly entangled, the entanglement turns out to be ‘fragile’, i.e. the associated density matrix has the property that if one traces out the freedom associated with even a single particle, the resulting reduced density matrix is separable.

  3. Incidental statistical summary representation over time.

    PubMed

    Oriet, Chris; Hozempa, Kadie

    2016-01-01

    Information taken in by the human visual system allows individuals to form statistical representations of sets of items. One's knowledge of natural categories includes statistical information, such as average size of category members and the upper and lower boundaries of the set. Previous research suggests that when subjects attend to a particular dimension of a set of items presented over an extended duration, they quickly learn about the central tendency of the set. However, it is unclear whether such learning can occur incidentally, when subjects are not attending to the relevant dimension of the set. The present study explored whether subjects could reproduce global statistical properties of a set presented over an extended duration when oriented to task-irrelevant properties of the set. Subjects were tested for their memory of its mean, its smallest and largest exemplars, the direction of its skew, and the relative distribution of the items. Subjects were able to accurately recall the average size circle, as well as the upper and lower boundaries of a set of 4,200 circles displayed over an extended period. This suggests that even without intending to do so, they were encoding and updating a statistical summary representation of a task-irrelevant attribute of the circles over time. Such incidental encoding of statistical properties of sets is thus a plausible mechanism for establishing a representation of typicality in category membership. PMID:26830709

  4. Dissociable behavioural outcomes of visual statistical learning

    PubMed Central

    Turk-Browne, Nicholas B.; Seitz, Aaron R.

    2016-01-01

    Statistical learning refers to the extraction of probabilistic relationships between stimuli and is increasingly used as a method to understand learning processes. However, numerous cognitive processes are sensitive to the statistical relationships between stimuli and any one measure of learning may conflate these processes; to date little research has focused on differentiating these processes. To understand how multiple processes underlie statistical learning, here we compared, within the same study, operational measures of learning from different tasks that may be differentially sensitive to these processes. In Experiment 1, participants were visually exposed to temporal regularities embedded in a stream of shapes. Their task was to periodically detect whether a shape, whose contrast was staircased to a threshold level, was present or absent. Afterwards, they completed a search task, where statistically predictable shapes were found more quickly. We used the search task to label shape pairs as “learned” or “non-learned”, and then used these labels to analyse the detection task. We found a dissociation between learning on the search task and the detection task where only non-learned pairs showed learning effects in the detection task. This finding was replicated in further experiments with recognition memory (Experiment 2) and associative learning tasks (Experiment 3). Taken together, these findings are consistent with the view that statistical learning may comprise a family of processes that can produce dissociable effects on different aspects of behaviour.

  5. Statistical Literacy: Developing a Youth and Adult Education Statistical Project

    ERIC Educational Resources Information Center

    Conti, Keli Cristina; Lucchesi de Carvalho, Dione

    2014-01-01

    This article focuses on the notion of literacy--general and statistical--in the analysis of data from a fieldwork research project carried out as part of a master's degree that investigated the teaching and learning of statistics in adult education mathematics classes. We describe the statistical context of the project that involved the…

  6. Understanding Statistics and Statistics Education: A Chinese Perspective

    ERIC Educational Resources Information Center

    Shi, Ning-Zhong; He, Xuming; Tao, Jian

    2009-01-01

    In recent years, statistics education in China has made great strides. However, there still exists a fairly large gap with the advanced levels of statistics education in more developed countries. In this paper, we identify some existing problems in statistics education in Chinese schools and make some proposals as to how they may be overcome. We…

  7. Statistics Anxiety and Business Statistics: The International Student

    ERIC Educational Resources Information Center

    Bell, James A.

    2008-01-01

    Does the international student suffer from statistics anxiety? To investigate this, the Statistics Anxiety Rating Scale (STARS) was administered to sixty-six beginning statistics students, including twelve international students and fifty-four domestic students. Due to the small number of international students, nonparametric methods were used to…

  8. Wide Wide World of Statistics: International Statistics on the Internet.

    ERIC Educational Resources Information Center

    Foudy, Geraldine

    2000-01-01

    Explains how to find statistics on the Internet, especially international statistics. Discusses advantages over print sources, including convenience, currency of information, cost effectiveness, and value-added formatting; sources of international statistics; United Nations agencies; search engines and power searching; and evaluating sources. (LRW)

  9. Improving extreme value statistics.

    PubMed

    Shekhawat, Ashivni

    2014-11-01

    The rate of convergence in extreme value statistics is nonuniversal and can be arbitrarily slow. Further, the relative error can be unbounded in the tail of the approximation, leading to difficulty in extrapolating the extreme value fit beyond the available data. We introduce the T method, and show that by using simple nonlinear transformations the extreme value approximation can be rendered rapidly convergent in the bulk, and asymptotic in the tail, thus fixing both issues. The transformations are often parametrized by just one parameter, which can be estimated numerically. The classical extreme value method is shown to be a special case of the proposed method. We demonstrate that vastly improved results can be obtained with almost no extra cost. PMID:25493780

  10. Statistical test of anarchy

    NASA Astrophysics Data System (ADS)

    de Gouvêa, André; Murayama, Hitoshi

    2003-10-01

    “Anarchy” is the hypothesis that there is no fundamental distinction among the three flavors of neutrinos. It describes the mixing angles as random variables, drawn from well-defined probability distributions dictated by the group Haar measure. We perform a Kolmogorov-Smirnov (KS) statistical test to verify whether anarchy is consistent with all neutrino data, including the new result presented by KamLAND. We find a KS probability for Nature's choice of mixing angles equal to 64%, quite consistent with the anarchical hypothesis. In turn, assuming that anarchy is indeed correct, we compute lower bounds on |Ue3|2, the remaining unknown “angle” of the leptonic mixing matrix.

  11. Statistical physics ""Beyond equilibrium

    SciTech Connect

    Ecke, Robert E

    2009-01-01

    The scientific challenges of the 21st century will increasingly involve competing interactions, geometric frustration, spatial and temporal intrinsic inhomogeneity, nanoscale structures, and interactions spanning many scales. We will focus on a broad class of emerging problems that will require new tools in non-equilibrium statistical physics and that will find application in new material functionality, in predicting complex spatial dynamics, and in understanding novel states of matter. Our work will encompass materials under extreme conditions involving elastic/plastic deformation, competing interactions, intrinsic inhomogeneity, frustration in condensed matter systems, scaling phenomena in disordered materials from glasses to granular matter, quantum chemistry applied to nano-scale materials, soft-matter materials, and spatio-temporal properties of both ordinary and complex fluids.

  12. Why Tsallis statistics?

    NASA Astrophysics Data System (ADS)

    Baranger, Michel

    2002-03-01

    It is a remarkable fact that the traditional teaching of thermodynamics, as reflected in the textbooks and including the long developments about ensembles and thermodynamic functions, is almost entirely about systems in equilibrium. The time variable does not enter. There is one exception, however. The single most important item, the flagship of the thermodynamic navy, the second law, is about the irreversibility of the time evolution of systems out of equilibrium. This is a bizarre situation, to say the least; a glaring case of the drunk man looking for his key under the lamp-post, when he knows that he lost it in the dark part of the street. The moment has come for us to go looking in the dark part, the behavior of systems as a function of time. We have been given a powerful new flashlight, chaos theory. We should use it. There, on the formerly dark pavement, we can find Tsallis statistics.

  13. Statistics of lattice animals

    NASA Astrophysics Data System (ADS)

    Hsu, Hsiao-Ping; Nadler, Walder; Grassberger, Peter

    2005-07-01

    The scaling behavior of randomly branched polymers in a good solvent is studied in two to nine dimensions, modeled by lattice animals on simple hypercubic lattices. For the simulations, we use a biased sequential sampling algorithm with re-sampling, similar to the pruned-enriched Rosenbluth method (PERM) used extensively for linear polymers. We obtain high statistics of animals with up to several thousand sites in all dimension 2⩽d⩽9. The partition sum (number of different animals) and gyration radii are estimated. In all dimensions we verify the Parisi-Sourlas prediction, and we verify all exactly known critical exponents in dimensions 2, 3, 4, and ⩾8. In addition, we present the hitherto most precise estimates for growth constants in d⩾3. For clusters with one site attached to an attractive surface, we verify the superuniversality of the cross-over exponent at the adsorption transition predicted by Janssen and Lyssy.

  14. Fast approximate motif statistics.

    PubMed

    Nicodème, P

    2001-01-01

    We present in this article a fast approximate method for computing the statistics of a number of non-self-overlapping matches of motifs in a random text in the nonuniform Bernoulli model. This method is well suited for protein motifs where the probability of self-overlap of motifs is small. For 96% of the PROSITE motifs, the expectations of occurrences of the motifs in a 7-million-amino-acids random database are computed by the approximate method with less than 1% error when compared with the exact method. Processing of the whole PROSITE takes about 30 seconds with the approximate method. We apply this new method to a comparison of the C. elegans and S. cerevisiae proteomes. PMID:11535175

  15. Statistical design controversy

    SciTech Connect

    Evans, L.S.; Hendrey, G.R.; Thompson, K.H.

    1985-02-01

    This article was in response to criticisms received by Evans, Hendrey, and Thompson that their article was biased because of omissions and misrepresentations. The authors contend that experimental designs having only one plot per treatment ''were, from the outset, not capable of differentiating between treatment effects and field-position effects,'' remains valid and is supported by decades of agronomic research. Several men, Irving, Troiano, and McCune thought of the article as a review of all studies of acidic rain effects on soybeans. It was not. The article was written over the concern of the comparisons which were being made among studies which purport to evaluate effects of acid deposition on field-grown crops, and implicitly assumes that all of the studies are of equal scientific value. They are not. Only experimental approaches that are well-focused and designed with appropriate agronomic and statistical procedures should be used for credible regional and national assessments of crop inventories. 12 references.

  16. Statistical Thermodynamics of Biomembranes

    PubMed Central

    Devireddy, Ram V.

    2010-01-01

    An overview of the major issues involved in the statistical thermodynamic treatment of phospholipid membranes at the atomistic level is summarized: thermodynamic ensembles, initial configuration (or the physical system being modeled), force field representation as well as the representation of long-range interactions. This is followed by a description of the various ways that the simulated ensembles can be analyzed: area of the lipid, mass density profiles, radial distribution functions (RDFs), water orientation profile, Deuteurium order parameter, free energy profiles and void (pore) formation; with particular focus on the results obtained from our recent molecular dynamic (MD) simulations of phospholipids interacting with dimethylsulfoxide (Me2SO), a commonly used cryoprotective agent (CPA). PMID:19460363

  17. Statistical crack mechanics

    SciTech Connect

    Dienes, J.K.

    1983-01-01

    An alternative to the use of plasticity theory to characterize the inelastic behavior of solids is to represent the flaws by statistical methods. We have taken such an approach to study fragmentation because it offers a number of advantages. Foremost among these is that, by considering the effects of flaws, it becomes possible to address the underlying physics directly. For example, we have been able to explain why rocks exhibit large strain-rate effects (a consequence of the finite growth rate of cracks), why a spherical explosive imbedded in oil shale produces a cavity with a nearly square section (opening of bedding cracks) and why propellants may detonate following low-speed impact (a consequence of frictional hot spots).

  18. Thyrotoxic periodic paralysis.

    PubMed

    Balakrishnan, Rojith Karanode; Chandran, Suresh Rama; Thirumalnesan, Geetha; Doraisamy, Nedumaran

    2011-07-01

    This article aims at highlighting the importance of suspecting thyrotoxicosis in cases of recurrent periodic flaccid paralysis; especially in Asian men to facilitate early diagnosis of the former condition. A case report of a 28 year old male patient with recurrent periodic flaccid paralysis has been presented. Hypokalemia secondary to thyrotoxicosis was diagnosed as the cause of the paralysis. The patient was given oral potassium intervention over 24 hours. The patient showed complete recovery after the medical intervention and was discharged after 24 hours with no residual paralysis. Thyrotoxic periodic paralysis (TPP) is a complication of thyrotoxicosis, more common amongst males in Asia. It presents as acute flaccid paralysis in a case of hyperthyroidism with associated hypokalemia. The features of thyrotoxicosis may be subtle or absent. Thus, in cases of recurrent or acute flaccid muscle paralysis, it is important to consider thyrotoxicosis as one of the possible causes, and take measures accordingly. PMID:21966655

  19. Transient period process control for continuous manufacturing

    SciTech Connect

    Nembhard, H.B.; Birge, J.R.

    1994-12-31

    We develop a multiple objective nonlinear control model to optimize decision variables for correlated process characteristics during a transient phase. Given a continuous manufacturing process we show how to use the model to improve operations from startup to the end of the transient period (when steady-state is reached). We also show how to identify the end of the transient period and compare performance using the model during steady-state to traditional SPC techniques that assume the process is in statistical control.

  20. [Periodic abstinence: its possibilities].

    PubMed

    1981-05-01

    Experience with family planning mehods requiring periodic sexual abstinence has been varied. During the last decade interest has centered on 2 methods, the cervical mucus and the sympto-thermal, which are based on identifying the onset of the fertile period. During the 1970s, the Australian physicians John and Evelyn Billings developed the cervical mucus method, in which changes in the quanitity and characteristics of cervical mucus are used to determine the moment of ovulation. The sympto-thermal method depends on identification of the slight rise in basal body temperature that occurs in the latter part of the menstrual cycle as well as cervical mucus changes and sometimes the calendar to determine the fertile period. The Catholic Church has been the main proponent of periodic abstinence methods, but since 1973 the World Health Organization has invested US$3.3 million on research in such methods. The Billings method requires differentiating between dry, wet, and very wet mucus in the vagina and between different consistencies of mucus. The method ususally requires 1-3 months for instruction and sexual abstinence is usually recommended for the 1st month. The average number of days of required abstinence was 9 in a study of 66 women and 15-18 in a study of 870 women. Many women with short menstrual cycles do not experience postmenstrual dry days, in which case abstinence may be required as many as 13 days out of 23. 18.8% of users of periodic abstinence methods in 1 North American study became pregnant in the 1st year, but most were using the calendar method. Women who desired to terminate childbearing had only about 1/2 as many failures with periodic abstinence methods as did women wishing to postpone a birth. PMID:12311397

  1. Periodically kicked turbulence

    PubMed

    Lohse

    2000-10-01

    Periodically kicked turbulence is theoretically analyzed within a mean-field theory. For large enough kicking strength A and kicking frequency f the Reynolds number grows exponentially and then runs into some saturation. The saturation level Re(sat) can be calculated analytically; different regimes can be observed. For large enough Re we find Re(sat) approximately Af, but intermittency can modify this scaling law. We suggest an experimental realization of periodically kicked turbulence to study the different regimes we theoretically predict and thus to better understand the effect of forcing on fully developed turbulence. PMID:11089041

  2. On the Statistics of Macrospicules

    NASA Astrophysics Data System (ADS)

    Bennett, S. M.; Erdélyi, R.

    2015-08-01

    A new generation of solar telescopes has led to an increase in the resolution of localized features seen on the Sun spatially, temporally, and spectrally, enabling a detailed study of macrospicules. Macrospicules are members of a wide variety of solar ejecta and ascertaining where they belong in this family is vitally important, particularly given that they are chromospheric events which penetrate the transition region and lower corona. We examine the overall properties of macrospicules, both temporal and spatial. We also investigate possible relationships between the macrospicule properties and the sample time period itself, which is selected as a proxy for the ramp from solar minimum to solar maximum. Measurements are taken using the Solar Dynamic Observatory to provide the necessary temporal resolution and coverage. At each point in time, the length of the macrospicule is measured from base to tip and the width is recorded at half the length at each step. The measurements were then applied to determine the statistical properties and relationships between them. It is evident that the properties of maximum velocity, maximum length, and lifetime are all related in specific, established terms. We provide appropriate scaling in terms of the physical properties, which would be a useful test bed for modeling. Also, we note that the maximum lengths and lifetimes of the features show some correlation with the sample epoch and, therefore, by proxy the solar minimum to maximum ramp.

  3. Statistical signatures of photon localization

    PubMed

    Chabanov; Stoytchev; Genack

    2000-04-20

    The realization that electron localization in disordered systems (Anderson localization) is ultimately a wave phenomenon has led to the suggestion that photons could be similarly localized by disorder. This conjecture attracted wide interest because the differences between photons and electrons--in their interactions, spin statistics, and methods of injection and detection--may open a new realm of optical and microwave phenomena, and allow a detailed study of the Anderson localization transition undisturbed by the Coulomb interaction. To date, claims of three-dimensional photon localization have been based on observations of the exponential decay of the electromagnetic wave as it propagates through the disordered medium. But these reports have come under close scrutiny because of the possibility that the decay observed may be due to residual absorption, and because absorption itself may suppress localization. Here we show that the extent of photon localization can be determined by a different approach--measurement of the relative size of fluctuations of certain transmission quantities. The variance of relative fluctuations accurately reflects the extent of localization, even in the presence of absorption. Using this approach, we demonstrate photon localization in both weakly and strongly scattering quasi-one-dimensional dielectric samples and in periodic metallic wire meshes containing metallic scatterers, while ruling it out in three-dimensional mixtures of aluminium spheres. PMID:10786786

  4. HPV-Associated Cancers Statistics

    MedlinePlus

    ... What CDC Is Doing Related Links Stay Informed Statistics for Other Kinds of Cancer Breast Cervical Colorectal ( ... Vaginal and Vulvar Cancer Home HPV-Associated Cancer Statistics Language: English Español (Spanish) Recommend on Facebook Tweet ...

  5. Key Statistics for Thyroid Cancer

    MedlinePlus

    ... cancer? Next Topic Thyroid cancer risk factors Key statistics for thyroid cancer How common is thyroid cancer? ... remains very low compared with most other cancers. Statistics on survival rates for thyroid cancer are discussed ...

  6. Muscular Dystrophy: Data and Statistics

    MedlinePlus

    ... Statistics Recommend on Facebook Tweet Share Compartir MD STAR net Data and Statistics The following data and ... research [ Read Article ] For more information on MD STAR net see Research and Tracking . Key Findings Feature ...

  7. Heart Disease and Stroke Statistics

    MedlinePlus

    ... Nutrition (PDF) Obesity (PDF) Peripheral Artery Disease (PDF) ... statistics, please contact the American Heart Association National Center, Office of Science & Medicine at statistics@heart.org . Please direct all ...

  8. Periods of High Intensity Solar Proton Flux

    NASA Technical Reports Server (NTRS)

    Xapsos, Michael A.; Stauffer, Craig A.; Jordan, Thomas M.; Adams, James H.; Dietrich, William F.

    2012-01-01

    Analysis is presented for times during a space mission that specified solar proton flux levels are exceeded. This includes both total time and continuous time periods during missions. Results for the solar maximum and solar minimum phases of the solar cycle are presented and compared for a broad range of proton energies and shielding levels. This type of approach is more amenable to reliability analysis for spacecraft systems and instrumentation than standard statistical models.

  9. REANALYSIS OF F-STATISTIC GRAVITATIONAL-WAVE SEARCHES WITH THE HIGHER CRITICISM STATISTIC

    SciTech Connect

    Bennett, M. F.; Melatos, A.; Delaigle, A.; Hall, P.

    2013-04-01

    We propose a new method of gravitational-wave detection using a modified form of higher criticism, a statistical technique introduced by Donoho and Jin. Higher criticism is designed to detect a group of sparse, weak sources, none of which are strong enough to be reliably estimated or detected individually. We apply higher criticism as a second-pass method to synthetic F-statistic and C-statistic data for a monochromatic periodic source in a binary system and quantify the improvement relative to the first-pass methods. We find that higher criticism on C-statistic data is more sensitive by {approx}6% than the C-statistic alone under optimal conditions (i.e., binary orbit known exactly) and the relative advantage increases as the error in the orbital parameters increases. Higher criticism is robust even when the source is not monochromatic (e.g., phase-wandering in an accreting system). Applying higher criticism to a phase-wandering source over multiple time intervals gives a {approx}> 30% increase in detectability with few assumptions about the frequency evolution. By contrast, in all-sky searches for unknown periodic sources, which are dominated by the brightest source, second-pass higher criticism does not provide any benefits over a first-pass search.

  10. Ayurveda during Abbasid's period.

    PubMed

    Husain, S A; Subhaktha, P K

    2000-01-01

    This is a historical paper which deals with a brief account of Abbasid's period. In this article the existence of Ayurveda in Arab countries, arrival of Ayurvedic physicians to Baghdad, their eminence, authenticity and literary additions in medical field has been studied and presented. PMID:12578013

  11. Getting Your Period

    MedlinePlus

    ... for a woman to have a baby. During sexual intercourse, the egg can get fertilized by a male’s sperm and then attach to the lining of the uterus ( endometrium ) and grow into a baby. ( Read more about reproduction. ) Does your period come each month? top Menstrual ...

  12. Astrophysical implications of periodicity

    NASA Technical Reports Server (NTRS)

    Muller, Richard A.

    1988-01-01

    Two remarkable discoveries of the last decade have profound implications for astrophysics and for geophysics. These are the discovery by Alvarez et al., that certain mass extinctions are caused by the impact on the earth of a large asteroid or comet, and the discovery by Raup and Sepkoski that such extinctions are periodic, with a cycle time of 26 to 30 million years. The validity of both of these discoveries is assumed and the implications are examined. Most of the phenomena described depend not on periodicity, but just on the weaker assumption that the impacts on the earth take place primarily in showers. Proposed explanations for the periodicity include galactic oscillations, the Planet X model, and the possibility of Nemesis, a solar companion star. These hypotheses are critically examined. Results of the search for the solar companion are reported. The Deccan flood basalts of India have been proposed as the impact site for the Cretaceous impact, but this hypotheisis is in contradiction with the conclusion of Courtillot et al., that the magma flow began during a period of normal magnetic field. A possible resolution of this contradiction is proposed.

  13. Periods and Feynman integrals

    SciTech Connect

    Bogner, Christian; Weinzierl, Stefan

    2009-04-15

    We consider multiloop integrals in dimensional regularization and the corresponding Laurent series. We study the integral in the Euclidean region and where all ratios of invariants and masses have rational values. We prove that in this case all coefficients of the Laurent series are periods.

  14. Periodic Table of Students.

    ERIC Educational Resources Information Center

    Johnson, Mike

    1998-01-01

    Presents an exercise in which an eighth-grade science teacher decorated the classroom with a periodic table of students. Student photographs were arranged according to similarities into vertical columns. Students were each assigned an atomic number according to their placement in the table. The table is then used to teach students about…

  15. A Modern Periodic Table.

    ERIC Educational Resources Information Center

    Herrenden-Harker, B. D.

    1997-01-01

    Presents a modern Periodic Table based on the electron distribution in the outermost shell and the order of filling of the sublevels within the shells. Enables a student to read off directly the electronic configuration of the element and the order in which filling occurs. (JRH)

  16. Scheduling: Seven Period Day

    ERIC Educational Resources Information Center

    Williamson, Ronald

    2010-01-01

    Driven by stable or declining financial resources many school districts are considering the costs and benefits of a seven-period day. While there is limited evidence that any particular scheduling model has a greater impact on student learning than any other, it is clear that the school schedule is a tool that can significantly impact teacher…

  17. Oscillations following periodic reinforcement.

    PubMed

    Monteiro, Tiago; Machado, Armando

    2009-06-01

    Three experiments examined behavior in extinction following periodic reinforcement. During the first phase of Experiment 1, four groups of pigeons were exposed to fixed interval (FI 16s or FI 48s) or variable interval (VI 16s or VI 48s) reinforcement schedules. Next, during the second phase, each session started with reinforcement trials and ended with an extinction segment. Experiment 2 was similar except that the extinction segment was considerably longer. Experiment 3 replaced the FI schedules with a peak procedure, with FI trials interspersed with non-food peak interval (PI) trials that were four times longer. One group of pigeons was exposed to FI 20s PI 80s trials, and another to FI 40s PI 160s trials. Results showed that, during the extinction segment, most pigeons trained with FI schedules, but not with VI schedules, displayed pause-peck oscillations with a period close to, but slightly greater than the FI parameter. These oscillations did not start immediately after the onset of extinction. Comparing the oscillations from Experiments 1 and 2 suggested that the alternation of reconditioning and re-extinction increases the reliability and earlier onset of the oscillations. In Experiment 3 the pigeons exhibited well-defined pause-peck cycles since the onset of extinction. These cycles had periods close to twice the value of the FI and lasted for long intervals of time. We discuss some hypotheses concerning the processes underlying behavioral oscillations following periodic reinforcement. PMID:18992793

  18. Statistics Anxiety and Instructor Immediacy

    ERIC Educational Resources Information Center

    Williams, Amanda S.

    2010-01-01

    The purpose of this study was to investigate the relationship between instructor immediacy and statistics anxiety. It was predicted that students receiving immediacy would report lower levels of statistics anxiety. Using a pretest-posttest-control group design, immediacy was measured using the Instructor Immediacy scale. Statistics anxiety was…

  19. Statistics: It's in the Numbers!

    ERIC Educational Resources Information Center

    Deal, Mary M.; Deal, Walter F., III

    2007-01-01

    Mathematics and statistics play important roles in peoples' lives today. A day hardly passes that they are not bombarded with many different kinds of statistics. As consumers they see statistical information as they surf the web, watch television, listen to their satellite radios, or even read the nutrition facts panel on a cereal box in the…

  20. Statistical log analysis made practical

    SciTech Connect

    Mitchell, W.K.; Nelson, R.J. )

    1991-06-01

    This paper discusses the advantages of a statistical approach to log analysis. Statistical techniques use inverse methods to calculate formation parameters. The use of statistical techniques has been limited, however, by the complexity of the mathematics and lengthy computer time required to minimize traditionally used nonlinear equations.

  1. Invention Activities Support Statistical Reasoning

    ERIC Educational Resources Information Center

    Smith, Carmen Petrick; Kenlan, Kris

    2016-01-01

    Students' experiences with statistics and data analysis in middle school are often limited to little more than making and interpreting graphs. Although students may develop fluency in statistical procedures and vocabulary, they frequently lack the skills necessary to apply statistical reasoning in situations other than clear-cut textbook examples.…

  2. Teaching Statistics Online Using "Excel"

    ERIC Educational Resources Information Center

    Jerome, Lawrence

    2011-01-01

    As anyone who has taught or taken a statistics course knows, statistical calculations can be tedious and error-prone, with the details of a calculation sometimes distracting students from understanding the larger concepts. Traditional statistics courses typically use scientific calculators, which can relieve some of the tedium and errors but…

  3. Explorations in Statistics: the Bootstrap

    ERIC Educational Resources Information Center

    Curran-Everett, Douglas

    2009-01-01

    Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This fourth installment of Explorations in Statistics explores the bootstrap. The bootstrap gives us an empirical approach to estimate the theoretical variability among possible values of a sample statistic such as the…

  4. Representative Ensembles in Statistical Mechanics

    NASA Astrophysics Data System (ADS)

    Yukalov, V. I.

    The notion of representative statistical ensembles, correctly representing statistical systems, is strictly formulated. This notion allows for a proper description of statistical systems, avoiding inconsistencies in theory. As an illustration, a Bose-condensed system is considered. It is shown that a self-consistent treatment of the latter, using a representative ensemble, always yields a conserving and gapless theory.

  5. Use of Statistics by Librarians.

    ERIC Educational Resources Information Center

    Christensen, John O.

    1988-01-01

    Description of common errors found in the statistical methodologies of research carried out by librarians, focuses on sampling and generalizability. The discussion covers the need to either adapt library research to the statistical abilities of librarians or to educate librarians in the proper use of statistics. (15 references) (CLB)

  6. Snowfall and avalanche synchronization: beyond observational statistics

    NASA Astrophysics Data System (ADS)

    Crouzy, Benoît; Forclaz, Romain; Sovilla, Betty; Corripio, Javier; Perona, Paolo

    2015-04-01

    We present a methodology for quantifying the synchronization between snowfall and avalanches in relation to slope and terrain properties at the detachment zone. Focusing on a particular field situation (SLF study site, Vallée de la Sionne, Valais, Switzerland), we present a dataset consisting of 549 avalanche events and use a stochastic framework (Perona et al., Proceedings of the Royal Society A, 2012) for capturing the avalanche statistics with a minimal number of ingredients. Over the observation period (7 years), meteorological data was collected and pictures of the slope were taken every 30 minutes. For the avalanche events, slope, aspect, coordinates and altitude of the detachment zone are available from georeferenced images, and the timing of the events can be obtained from selecting the images before and after avalanche events. All model parameters can directly be computed from meteorological data (snow depth evolution), except for one parameter: the state-dependent avalanche release rate, which aggregates the influence of slope and terrain properties. From the timing distribution of the precipitation events and of the avalanche events, we calibrate the model and fix the value of the missing parameter by maximizing the likelihood of the field observations, conditional to the value of the model parameter. We carefully discuss confidence intervals for our parameter estimation. The calibrated model allows us to obtain statistical properties of the avalanches in our study site, beyond observational statistics. We compute the synchronization between snowfall and avalanches for low and high slopes, which in turn allows us to derive the return period of avalanche events (dependent and independent on the release depth). We obtain the critical event magnitude above which the return period of avalanche events with release depth h* is shorter than the return period of snowfall with equal deposited snow depth h*. Finally, using the concept of information entropy, we

  7. Topics in statistical mechanics

    SciTech Connect

    Elser, V.

    1984-05-01

    This thesis deals with four independent topics in statistical mechanics: (1) the dimer problem is solved exactly for a hexagonal lattice with general boundary using a known generating function from the theory of partitions. It is shown that the leading term in the entropy depends on the shape of the boundary; (2) continuum models of percolation and self-avoiding walks are introduced with the property that their series expansions are sums over linear graphs with intrinsic combinatorial weights and explicit dimension dependence; (3) a constrained SOS model is used to describe the edge of a simple cubic crystal. Low and high temperature results are derived as well as the detailed behavior near the crystal facet; (4) the microscopic model of the lambda-transition involving atomic permutation cycles is reexamined. In particular, a new derivation of the two-component field theory model of the critical behavior is presented. Results for a lattice model originally proposed by Kikuchi are extended with a high temperature series expansion and Monte Carlo simulation. 30 references.

  8. International petroleum statistics report

    SciTech Connect

    1996-05-01

    The International Petroleum Statistics Report presents data on international oil production, demand, imports, exports, and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). This section contains annual data beginning in 1985, and monthly data for the most recent two years. Section 2 presents an oil supply/demand balance for the world. This balance is presented in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. This section contains annual data for the most recent year, quarterly data for the most recent two quarters, and monthly data for the most recent twelve months. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries. World oil production and OECD demand data are for the years 1970 through 1995; OECD stocks from 1973 through 1995; and OECD trade from 1084 through 1994.

  9. International petroleum statistics report

    SciTech Connect

    1995-07-27

    The International Petroleum Statistics Report presents data on international oil production, demand, imports, and exports, and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). This section contains annual data beginning in 1985, and monthly data for the most recent two years. Section 2 presents an oil supply/demand balance for the world. This balance is presented in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. This section contains annual data for the most recent year, quarterly data for the most recent two quarters, and monthly data for the most recent twelve months. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries. World oil production and OECD demand data are for the years 1970 through 1994; OECD stocks from 1973 through 1994; and OECD trade from 1984 through 1994.

  10. International petroleum statistics report

    SciTech Connect

    1997-07-01

    The International Petroleum Statistics Report is a monthly publication that provides current international data. The report presents data on international oil production, demand, imports, and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). This section contains annual data beginning in 1985, and monthly data for the most recent two years. Section 2 presents an oil supply/demand balance for the world. This balance is presented in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. This section contains annual data for the most recent year, quarterly data for the most recent two quarters, and monthly data for the most recent 12 months. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries. World oil production and OECD demand data are for the years 1970 through 1996; OECD stocks from 1973 through 1996; and OECD trade from 1986 through 1996.

  11. International petroleum statistics report

    SciTech Connect

    1995-11-01

    The International Petroleum Statistics Report presents data on international oil production, demand, imports, exports, and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). This section contains annual data beginning in 1985, and monthly data for the most recent two years. Section 2 presents an oil supply/demand balance for the world. This balance is presented in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. This section contains annual data for the most recent year, quarterly data for the most recent two quarters, and monthly data for the most recent twelve months. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries. World oil production and OECD demand data are for the years 1970 through 1994; OECD stocks from 1973 through 1994; and OECD trade from 1984 through 1994.

  12. International petroleum statistics report

    SciTech Connect

    1996-10-01

    The International Petroleum Statistics Report presents data on international oil production, demand, imports, and stocks. The report has four sections. Section 1 contains time series data on world oil production, and on oil demand and stocks in the Organization for Economic Cooperation and Development (OECD). This section contains annual data beginning in 1985, and monthly data for the most recent two years. Section 2 presents an oil supply/demand balance for the world. This balance is presented in quarterly intervals for the most recent two years. Section 3 presents data on oil imports by OECD countries. This section contains annual data for the most recent year, quarterly data for the most recent two quarters, and monthly data for the most recent twelve months. Section 4 presents annual time series data on world oil production and oil stocks, demand, and trade in OECD countries. Word oil production and OECD demand data are for the years 1970 through 1995; OECD stocks from 1973 through 1995; and OECD trade from 1985 through 1995.

  13. Statistical Mechanics of Zooplankton

    PubMed Central

    Hinow, Peter; Nihongi, Ai; Strickler, J. Rudi

    2015-01-01

    Statistical mechanics provides the link between microscopic properties of many-particle systems and macroscopic properties such as pressure and temperature. Observations of similar “microscopic” quantities exist for the motion of zooplankton, as well as many species of other social animals. Herein, we propose to take average squared velocities as the definition of the “ecological temperature” of a population under different conditions on nutrients, light, oxygen and others. We test the usefulness of this definition on observations of the crustacean zooplankton Daphnia pulicaria. In one set of experiments, D. pulicaria is infested with the pathogen Vibrio cholerae, the causative agent of cholera. We find that infested D. pulicaria under light exposure have a significantly greater ecological temperature, which puts them at a greater risk of detection by visual predators. In a second set of experiments, we observe D. pulicaria in cold and warm water, and in darkness and under light exposure. Overall, our ecological temperature is a good discriminator of the crustacean’s swimming behavior. PMID:26270537

  14. Statistical mechanics of nucleosomes

    NASA Astrophysics Data System (ADS)

    Chereji, Razvan V.

    Eukaryotic cells contain long DNA molecules (about two meters for a human cell) which are tightly packed inside the micrometric nuclei. Nucleosomes are the basic packaging unit of the DNA which allows this millionfold compactification. A longstanding puzzle is to understand the principles which allow cells to both organize their genomes into chromatin fibers in the crowded space of their nuclei, and also to keep the DNA accessible to many factors and enzymes. With the nucleosomes covering about three quarters of the DNA, their positions are essential because these influence which genes can be regulated by the transcription factors and which cannot. We study physical models which predict the genome-wide organization of the nucleosomes and also the relevant energies which dictate this organization. In the last five years, the study of chromatin knew many important advances. In particular, in the field of nucleosome positioning, new techniques of identifying nucleosomes and the competing DNA-binding factors appeared, as chemical mapping with hydroxyl radicals, ChIP-exo, among others, the resolution of the nucleosome maps increased by using paired-end sequencing, and the price of sequencing an entire genome decreased. We present a rigorous statistical mechanics model which is able to explain the recent experimental results by taking into account nucleosome unwrapping, competition between different DNA-binding proteins, and both the interaction between histones and DNA, and between neighboring histones. We show a series of predictions of our new model, all in agreement with the experimental observations.

  15. Statistical Mechanics of Zooplankton.

    PubMed

    Hinow, Peter; Nihongi, Ai; Strickler, J Rudi

    2015-01-01

    Statistical mechanics provides the link between microscopic properties of many-particle systems and macroscopic properties such as pressure and temperature. Observations of similar "microscopic" quantities exist for the motion of zooplankton, as well as many species of other social animals. Herein, we propose to take average squared velocities as the definition of the "ecological temperature" of a population under different conditions on nutrients, light, oxygen and others. We test the usefulness of this definition on observations of the crustacean zooplankton Daphnia pulicaria. In one set of experiments, D. pulicaria is infested with the pathogen Vibrio cholerae, the causative agent of cholera. We find that infested D. pulicaria under light exposure have a significantly greater ecological temperature, which puts them at a greater risk of detection by visual predators. In a second set of experiments, we observe D. pulicaria in cold and warm water, and in darkness and under light exposure. Overall, our ecological temperature is a good discriminator of the crustacean's swimming behavior. PMID:26270537

  16. Basic statistics in cell biology.

    PubMed

    Vaux, David L

    2014-01-01

    The physicist Ernest Rutherford said, "If your experiment needs statistics, you ought to have done a better experiment." Although this aphorism remains true for much of today's research in cell biology, a basic understanding of statistics can be useful to cell biologists to help in monitoring the conduct of their experiments, in interpreting the results, in presenting them in publications, and when critically evaluating research by others. However, training in statistics is often focused on the sophisticated needs of clinical researchers, psychologists, and epidemiologists, whose conclusions depend wholly on statistics, rather than the practical needs of cell biologists, whose experiments often provide evidence that is not statistical in nature. This review describes some of the basic statistical principles that may be of use to experimental biologists, but it does not cover the sophisticated statistics needed for papers that contain evidence of no other kind. PMID:25000992

  17. Thyrotoxic periodic paralysis

    SciTech Connect

    Ferreiro, J.E.; Arguelles, D.J.; Rams, H. Jr.

    1986-01-01

    A case of thyrotoxic periodic paralysis is reported in a Hispanic man with an unusual recurrence six weeks after radioactive iodine treatment. Thyrotoxic periodic paralysis has now been well characterized in the literature: it occurs primarily in Orientals with an overwhelming male preponderance and a higher association of specific HLA antigens. Clinical manifestations include onset after high carbohydrate ingestion or heavy exertion, with progressive symmetric weakness leading to flaccid paralysis of the extremities and other muscle groups, lasting several hours. If hypokalemia is present, potassium administration may help abort the attack. Although propranolol can be efficacious in preventing further episodes, the only definitive treatment is establishing a euthyroid state. The pathophysiology is still controversial, but reflects altered potassium and calcium dynamics as well as certain morphologic characteristics within the muscle unit itself.

  18. Cells anticipate periodic events

    NASA Astrophysics Data System (ADS)

    Nakagaki, Toshiyuki

    2009-03-01

    We show that an amoeboid organism can anticipate the timing of periodic events. The plasmodium of the true slime mold Physarum polycephalum moves rapidly under favourable conditions, but stops moving when transferred to less-favourable conditions. Plasmodia exposed to unfavourable conditions, presented in three consecutive pulses at constant intervals, reduced their locomotive speed in response to each episode. When subsequently subjected to favourable conditions, the plasmodia spontaneously reduced their locomotive speed at the time point when the next unfavourable episode would have occurred. This implied anticipation of impending environmental change. After this behaviour had been evoked several times, the locomotion of the plasmodia returned to normal; however, the anticipatory response could subsequently be induced by a single unfavourable pulse, implying recall of the memorized periodicity. We explored the mechanisms underlying these behaviours from a dynamical systems perspective. Our results hint at the cellular origins of primitive intelligence and imply that simple dynamics might be sufficient to explain its emergence.

  19. Periodic minimal surfaces

    NASA Astrophysics Data System (ADS)

    Mackay, Alan L.

    1985-04-01

    A minimal surface is one for which, like a soap film with the same pressure on each side, the mean curvature is zero and, thus, is one where the two principal curvatures are equal and opposite at every point. For every closed circuit in the surface, the area is a minimum. Schwarz1 and Neovius2 showed that elements of such surfaces could be put together to give surfaces periodic in three dimensions. These periodic minimal surfaces are geometrical invariants, as are the regular polyhedra, but the former are curved. Minimal surfaces are appropriate for the description of various structures where internal surfaces are prominent and seek to adopt a minimum area or a zero mean curvature subject to their topology; thus they merit more complete numerical characterization. There seem to be at least 18 such surfaces3, with various symmetries and topologies, related to the crystallographic space groups. Recently, glyceryl mono-oleate (GMO) was shown by Longley and McIntosh4 to take the shape of the F-surface. The structure postulated is shown here to be in good agreement with an analysis of the fundamental geometry of periodic minimal surfaces.

  20. Chemists, Access, Statistics

    NASA Astrophysics Data System (ADS)

    Holmes, Jon L.

    2000-06-01

    IP-number access. Current subscriptions can be upgraded to IP-number access at little additional cost. We are pleased to be able to offer to institutions and libraries this convenient mode of access to subscriber only resources at JCE Online. JCE Online Usage Statistics We are continually amazed by the activity at JCE Online. So far, the year 2000 has shown a marked increase. Given the phenomenal overall growth of the Internet, perhaps our surprise is not warranted. However, during the months of January and February 2000, over 38,000 visitors requested over 275,000 pages. This is a monthly increase of over 33% from the October-December 1999 levels. It is good to know that people are visiting, but we would very much like to know what you would most like to see at JCE Online. Please send your suggestions to JCEOnline@chem.wisc.edu. For those who are interested, JCE Online year-to-date statistics are available. Biographical Snapshots of Famous Chemists: Mission Statement Feature Editor: Barbara Burke Chemistry Department, California State Polytechnic University-Pomona, Pomona, CA 91768 phone: 909/869-3664 fax: 909/869-4616 email: baburke@csupomona.edu The primary goal of this JCE Internet column is to provide information about chemists who have made important contributions to chemistry. For each chemist, there is a short biographical "snapshot" that provides basic information about the person's chemical work, gender, ethnicity, and cultural background. Each snapshot includes links to related websites and to a biobibliographic database. The database provides references for the individual and can be searched through key words listed at the end of each snapshot. All students, not just science majors, need to understand science as it really is: an exciting, challenging, human, and creative way of learning about our natural world. Investigating the life experiences of chemists can provide a means for students to gain a more realistic view of chemistry. In addition students

  1. Petroleum statistics in France

    SciTech Connect

    De Saint Germain, H.; Lamiraux, C.

    1995-08-01

    33 oil companies, including Elf, Exxon, Agip, Conoco as well as Coparex, Enron, Hadson, Midland, Hunt, Canyon and Union Texas are present in oil and gas exploration and production in France. The production of oil and gas in France amounts to some 60,000 bopd of oil and 350 MMcfpd of marketed natural gas each year, which still accounts for 3.5% and 10% for French domestic needs, respectively. To date, 166 fields have been discovered, representing a total reserve of 3 billion bbl of crude oil and 13 trillion cf of raw gas. These fields are concentrated in two major onshore sedimentary basins of Mesozoic age, which are the Aquitaine basin and the Paris basin. The Aquitaine basin should be subdivided into two distinct domains: The Parentis basin where the largest field Parentis was discovered in 1954 with still production of about 3700 bopd of oil and where Les Arbouslers field, discovered at the end of 1991, is currently producing about 10,000 bopd of oil. The northern Pyrenees and their foreland, where the Lacq field, discovered in 1951, has produced about 7.7 tcf of gas since 1957, and is still producing 138 MMcfpd. In the Paris basin, the two large oil fields are Villeperclue discovered in 1982 by Triton and Total, and Chaunoy, discovered in 1983 by Essorep, which are still producing about 10,000 and 15,000 bopd, respectively. The last significantly sized discovery occurred in 1990 with Itteville by Elf Aquitaine which is currently producing 4,200 bopd. The poster shows statistical data related to the past 20 years of oil and gas exploration and production in France.

  2. Methods in probability and statistical inference. Final report, June 15, 1975-June 30, 1979. [Dept. of Statistics, Univ. of Chicago

    SciTech Connect

    Wallace, D L; Perlman, M D

    1980-06-01

    This report describes the research activities of the Department of Statistics, University of Chicago, during the period June 15, 1975 to July 30, 1979. Nine research projects are briefly described on the following subjects: statistical computing and approximation techniques in statistics; numerical computation of first passage distributions; probabilities of large deviations; combining independent tests of significance; small-sample efficiencies of tests and estimates; improved procedures for simultaneous estimation and testing of many correlations; statistical computing and improved regression methods; comparison of several populations; and unbiasedness in multivariate statistics. A description of the statistical consultation activities of the Department that are of interest to DOE, in particular, the scientific interactions between the Department and the scientists at Argonne National Laboratories, is given. A list of publications issued during the term of the contract is included.

  3. Periodic or random nanostructures for light scattering control

    NASA Astrophysics Data System (ADS)

    Berginc, Gerard

    2016-04-01

    Our paper mainly focuses on the control of light scattering by periodic or randomly rough structures. First designed with bi-periodical structures, antireflective surfaces can be achieved with random patterns. We present some new structures with periodic or random patterns, which have been designed by rigorous numerical methods (FDTD) or analytical methods. We show that random interfaces offer new degrees of freedom and possibilities by control of their statistical properties.

  4. New statistical downscaling for Canada

    NASA Astrophysics Data System (ADS)

    Murdock, T. Q.; Cannon, A. J.; Sobie, S.

    2013-12-01

    This poster will document the production of a set of statistically downscaled future climate projections for Canada based on the latest available RCM and GCM simulations - the North American Regional Climate Change Assessment Program (NARCCAP; Mearns et al. 2007) and the Coupled Model Intercomparison Project Phase 5 (CMIP5). The main stages of the project included (1) downscaling method evaluation, (2) scenarios selection, (3) production of statistically downscaled results, and (4) applications of results. We build upon a previous downscaling evaluation project (Bürger et al. 2012, Bürger et al. 2013) in which a quantile-based method (Bias Correction/Spatial Disaggregation - BCSD; Werner 2011) provided high skill compared with four other methods representing the majority of types of downscaling used in Canada. Additional quantile-based methods (Bias-Correction/Constructed Analogues; Maurer et al. 2010 and Bias-Correction/Climate Imprint ; Hunter and Meentemeyer 2005) were evaluated. A subset of 12 CMIP5 simulations was chosen based on an objective set of selection criteria. This included hemispheric skill assessment based on the CLIMDEX indices (Sillmann et al. 2013), historical criteria used previously at the Pacific Climate Impacts Consortium (Werner 2011), and refinement based on a modified clustering algorithm (Houle et al. 2012; Katsavounidis et al. 1994). Statistical downscaling was carried out on the NARCCAP ensemble and a subset of the CMIP5 ensemble. We produced downscaled scenarios over Canada at a daily time resolution and 300 arc second (~10 km) spatial resolution from historical runs for 1951-2005 and from RCP 2.6, 4.5, and 8.5 projections for 2006-2100. The ANUSPLIN gridded daily dataset (McKenney et al. 2011) was used as a target. It has national coverage, spans the historical period of interest 1951-2005, and has daily time resolution. It uses interpolation of station data based on thin-plate splines. This type of method has been shown to have

  5. Statistical Analysis of Iberian Peninsula Megaliths Orientations

    NASA Astrophysics Data System (ADS)

    González-García, A. C.

    2009-08-01

    Megalithic monuments have been intensively surveyed and studied from the archaeoastronomical point of view in the past decades. We have orientation measurements for over one thousand megalithic burial monuments in the Iberian Peninsula, from several different periods. These data, however, lack a sound understanding. A way to classify and start to understand such orientations is by means of statistical analysis of the data. A first attempt is done with simple statistical variables and a mere comparison between the different areas. In order to minimise the subjectivity in the process a further more complicated analysis is performed. Some interesting results linking the orientation and the geographical location will be presented. Finally I will present some models comparing the orientation of the megaliths in the Iberian Peninsula with the rising of the sun and the moon at several times of the year.

  6. Attention Reorients Periodically.

    PubMed

    Dugué, Laura; Roberts, Mariel; Carrasco, Marisa

    2016-06-20

    Reorienting of voluntary attention enables the processing of stimuli at previously unattended locations. Although studies have identified a ventral fronto-parietal network underlying attention [1, 2], little is known about whether and how early visual areas are involved in involuntary [3, 4] and even less in voluntary [5] reorienting, and their temporal dynamics are unknown. We used transcranial magnetic stimulation (TMS) over the occipital cortex to interfere with attentional reorienting and study its role and temporal dynamics in this process. Human observers performed an orientation discrimination task, with either valid or invalid attention cueing, across a range of stimulus contrasts. Valid cueing induced a behavioral response gain increase, higher asymptotic performance for attended than unattended locations. During subsequent TMS sessions, observers performed the same task, with high stimulus contrast. Based on phosphene mapping, TMS double pulses were applied at one of various delays to a consistent brain location in retinotopic areas (V1/V2), corresponding to the evoked signal of the target or distractor, in a valid or invalid trial. Thus, the stimulation was identical for the four experimental conditions (valid/invalid cue condition × target/distractor-stimulated). TMS modulation of the target and distractor were both periodic (5 Hz, theta) and out of phase with respect to each other in invalid trials only, when attention had to be disengaged from the distractor and reoriented to the target location. Reorientation of voluntary attention periodically involves V1/V2 at the theta frequency. These results suggest that TMS probes theta phase-reset by attentional reorienting and help link periodic sampling in time and attention reorienting in space. PMID:27265395

  7. Periodic Mesoporous Organosilica Nanorice

    NASA Astrophysics Data System (ADS)

    Mohanty, Paritosh; Landskron, Kai

    2009-02-01

    A periodic mesoporous organosilica (PMO) with nanorice morphology was successfully synthesized by a template assisted sol-gel method using a chain-type precursor. The PMO is composed of D and T sites in the ratio 1:2. The obtained mesoporous nanorice has a surface area of 753 m2 g-1, one-dimensional channels, and a narrow pore size distribution centered at 4.3 nm. The nanorice particles have a length of ca. 600 nm and width of ca. 200 nm.

  8. Controls on geyser periodicity

    USGS Publications Warehouse

    Ingebritsen, S.E.; Rojstaczer, S.A.

    1993-01-01

    Geyser eruption frequency is not constant over time and has been shown to vary with small (???10-6) strains induced by seismic events, atmospheric loading, and Earth tides. The geyser system is approximated as a permeable conduit of intensely fractured rock surrounded by a less permeable rock matrix. Numerical simulation of this conceptual model yields a set of parameters that controls geyser existence and periodicity. Much of the responsiveness to remote seismicity and other small strains in the Earth can be explained in terms of variations in permeability and lateral recharge rates.

  9. Controls on geyser periodicity.

    PubMed

    Ingebritsen, S E; Rojstaczer, S A

    1993-11-01

    Geyser eruption frequency is not constant over time and has been shown to vary with small (periodicity. Much of the responsiveness to remote seismicity and other small strains in the Earth can be explained in terms of variations in permeability and lateral recharge rates. PMID:17757358

  10. Periodate oxidation of dextrans

    SciTech Connect

    Mirgorodskaya, O.A.; Poletaeva, L.V.

    1986-03-01

    The authors estimate the degree of oxidation of the thiol group in dextran with various mol. wt. and make an attempt at a kinetic description of the main parameters of the process. Polyglucin was used. The results are shown of experiments done on the estimation of the amount of products formed in the process of oxidation of polyglucin in which the reaction stopped as a result of complete exhaustion of one of the original reagents. To estimate the reactivity of the thiol group toward oxidation, the authors studied the interaction of potassium periodate with alpha-D-glucose, isolated by the monomer unit of dextran.

  11. Thermodynamics of cellular statistical inference

    NASA Astrophysics Data System (ADS)

    Lang, Alex; Fisher, Charles; Mehta, Pankaj

    2014-03-01

    Successful organisms must be capable of accurately sensing the surrounding environment in order to locate nutrients and evade toxins or predators. However, single cell organisms face a multitude of limitations on their accuracy of sensing. Berg and Purcell first examined the canonical example of statistical limitations to cellular learning of a diffusing chemical and established a fundamental limit to statistical accuracy. Recent work has shown that the Berg and Purcell learning limit can be exceeded using Maximum Likelihood Estimation. Here, we recast the cellular sensing problem as a statistical inference problem and discuss the relationship between the efficiency of an estimator and its thermodynamic properties. We explicitly model a single non-equilibrium receptor and examine the constraints on statistical inference imposed by noisy biochemical networks. Our work shows that cells must balance sample number, specificity, and energy consumption when performing statistical inference. These tradeoffs place significant constraints on the practical implementation of statistical estimators in a cell.

  12. Are Mantle Plumes Periodic?

    NASA Astrophysics Data System (ADS)

    Rampino, Michael R.; Prokoph, Andreas

    2013-03-01

    In the past few years, researchers have uncovered evidence that several kinds of geological and biological events seem to show regular cycles of similar lengths. For example, Rohde and Muller [2005] looked at the record of diversity of marine organisms over the past 540 million years and found evidence for two cycles in the data—a roughly 62-million-year cycle and a longer cycle of about 140 million years. This was followed by reports of an approximately 56-million-year cycle in long-term stratigraphic sequences in sedimentary basins [Meyers and Peters, 2011] and a 59-million-year period in the marine strontium-isotope record [Melott et al., 2012]. A similar period may even exist in atmospheric carbon dioxide over the past 542 million years of the Phanerozoic [Franks et al., 2012]. A cycle of about 140 million years was reported by Veizer et al. [2000] and Mayhew et al. [2008] in long-term fluctuations in global climate.

  13. SOCR: Statistics Online Computational Resource

    PubMed Central

    Dinov, Ivo D.

    2011-01-01

    The need for hands-on computer laboratory experience in undergraduate and graduate statistics education has been firmly established in the past decade. As a result a number of attempts have been undertaken to develop novel approaches for problem-driven statistical thinking, data analysis and result interpretation. In this paper we describe an integrated educational web-based framework for: interactive distribution modeling, virtual online probability experimentation, statistical data analysis, visualization and integration. Following years of experience in statistical teaching at all college levels using established licensed statistical software packages, like STATA, S-PLUS, R, SPSS, SAS, Systat, etc., we have attempted to engineer a new statistics education environment, the Statistics Online Computational Resource (SOCR). This resource performs many of the standard types of statistical analysis, much like other classical tools. In addition, it is designed in a plug-in object-oriented architecture and is completely platform independent, web-based, interactive, extensible and secure. Over the past 4 years we have tested, fine-tuned and reanalyzed the SOCR framework in many of our undergraduate and graduate probability and statistics courses and have evidence that SOCR resources build student’s intuition and enhance their learning. PMID:21451741

  14. Statistics without Tears: Complex Statistics with Simple Arithmetic

    ERIC Educational Resources Information Center

    Smith, Brian

    2011-01-01

    One of the often overlooked aspects of modern statistics is the analysis of time series data. Modern introductory statistics courses tend to rush to probabilistic applications involving risk and confidence. Rarely does the first level course linger on such useful and fascinating topics as time series decomposition, with its practical applications…

  15. Measuring Student Learning in Social Statistics: A Pretest-Posttest Study of Knowledge Gain

    ERIC Educational Resources Information Center

    Delucchi, Michael

    2014-01-01

    This study used a pretest-posttest design to measure student learning in undergraduate statistics. Data were derived from 185 students enrolled in six different sections of a social statistics course taught over a seven-year period by the same sociology instructor. The pretest-posttest instrument reveals statistically significant gains in…

  16. Cross-correlation search for periodic gravitational waves

    SciTech Connect

    Dhurandhar, Sanjeev; Mukhopadhyay, Himan; Krishnan, Badri; Whelan, John T.

    2008-04-15

    In this paper we study the use of cross correlations between multiple gravitational wave (GW) data streams for detecting long-lived periodic signals. Cross-correlation searches between data from multiple detectors have traditionally been used to search for stochastic GW signals, but recently they have also been used in directed searches for periodic GWs. Here we further adapt the cross-correlation statistic for periodic GW searches by taking into account both the nonstationarity and the long-term-phase coherence of the signal. We study the statistical properties and sensitivity of this search and its relation to existing periodic wave searches, and describe the precise way in which the cross-correlation statistic interpolates between semicoherent and fully coherent methods. Depending on the maximum duration over which we wish to preserve phase coherence, the cross-correlation statistic can be tuned to go from a standard cross-correlation statistic using data from distinct detectors, to the semicoherent time-frequency methods with increasing coherent time baselines, and all the way to a full coherent search. This leads to a unified framework for studying periodic wave searches and can be used to make informed trade-offs between computational cost, sensitivity, and robustness against signal uncertainties.

  17. Statistical cyclicity of the supercontinent cycle

    NASA Astrophysics Data System (ADS)

    Rolf, T.; Coltice, N.; Tackley, P. J.

    2014-04-01

    Supercontinents like Pangea impose a first-order control on Earth's evolution as they modulate global heat loss, sea level, climate, and biodiversity. In a traditional view, supercontinents form and break up in a regular, perhaps periodic, manner in a cycle lasting several 100 Myr as reflected in the assembly times of Earth's major continental aggregations: Columbia, Rodinia, and Pangea. However, modern views of the supercontinent cycle propose a more irregular evolution on the basis of an improved understanding of the Precambrian geologic record. Here we use fully dynamic spherical mantle convection models featuring plate-like behavior and continental drift to investigate supercontinent formation and breakup. We further dismiss the concept of regularity but suggest a statistical cyclicity in which the supercontinent cycle may have a characteristic period imposed by mantle and lithosphere properties, but this is hidden in immense fluctuations between different cycles that arise from the chaotic nature of mantle flow.

  18. Count-Rate Statistics for Drift Detectors

    PubMed Central

    Pietraski, Philip J.; Furenlid, Lars R.

    2015-01-01

    Synchrotron light sources are low-duty-cycle pulsed X-ray sources, a fact that is often neglected in estimating the count-rate capabilities of photon-counting detectors in synchrotron-based experiments. In this paper, we demonstrate the effect that this has on the pileup statistics of drift detectors. We derive expressions for the cases of continuous and pulsed X-ray sources. We consider a pulsed source with period that is either much less than the shaper support time or much less than the average drift time. We also consider a pulsed source with a period that is long or comparable to both the shaper support and the drift time. These conditions correspond to normal and reduced bunch fill patterns of synchrotrons. PMID:27103751

  19. Digest of Education Statistics, 2000.

    ERIC Educational Resources Information Center

    Snyder, Thomas D.; Hoffman, Charlene M.

    This edition of the "Digest of Education Statistics" is the 36th in a series that provides a compilation of statistical information covering the broad field of U.S. education from kindergarten through graduate school. The Digest includes data from many sources, both government and private, and draws heavily on work done by the National Center for…

  20. Explorations in Statistics: Permutation Methods

    ERIC Educational Resources Information Center

    Curran-Everett, Douglas

    2012-01-01

    Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This eighth installment of "Explorations in Statistics" explores permutation methods, empiric procedures we can use to assess an experimental result--to test a null hypothesis--when we are reluctant to trust statistical…

  1. SOCR: Statistics Online Computational Resource

    ERIC Educational Resources Information Center

    Dinov, Ivo D.

    2006-01-01

    The need for hands-on computer laboratory experience in undergraduate and graduate statistics education has been firmly established in the past decade. As a result a number of attempts have been undertaken to develop novel approaches for problem-driven statistical thinking, data analysis and result interpretation. In this paper we describe an…

  2. Representational Versatility in Learning Statistics

    ERIC Educational Resources Information Center

    Graham, Alan T.; Thomas, Michael O. J.

    2005-01-01

    Statistical data can be represented in a number of qualitatively different ways, the choice depending on the following three conditions: the concepts to be investigated; the nature of the data; and the purpose for which they were collected. This paper begins by setting out frameworks that describe the nature of statistical thinking in schools, and…

  3. Statistics Anxiety among Postgraduate Students

    ERIC Educational Resources Information Center

    Koh, Denise; Zawi, Mohd Khairi

    2014-01-01

    Most postgraduate programmes, that have research components, require students to take at least one course of research statistics. Not all postgraduate programmes are science based, there are a significant number of postgraduate students who are from the social sciences that will be taking statistics courses, as they try to complete their…

  4. Students' Attitudes toward Statistics (STATS).

    ERIC Educational Resources Information Center

    Sutarso, Toto

    The purposes of this study were to develop an instrument to measure students' attitude toward statistics (STATS), and to define the underlying dimensions that comprise the STATS. The instrument consists of 24 items. The sample included 79 male and 97 female students from the statistics classes at the College of Education and the College of…

  5. Motivating Play Using Statistical Reasoning

    ERIC Educational Resources Information Center

    Cross Francis, Dionne I.; Hudson, Rick A.; Lee, Mi Yeon; Rapacki, Lauren; Vesperman, Crystal Marie

    2014-01-01

    Statistical literacy is essential in everyone's personal lives as consumers, citizens, and professionals. To make informed life and professional decisions, students are required to read, understand, and interpret vast amounts of information, much of which is quantitative. To develop statistical literacy so students are able to make sense of…

  6. Explorations in Statistics: Confidence Intervals

    ERIC Educational Resources Information Center

    Curran-Everett, Douglas

    2009-01-01

    Learning about statistics is a lot like learning about science: the learning is more meaningful if you can actively explore. This third installment of "Explorations in Statistics" investigates confidence intervals. A confidence interval is a range that we expect, with some level of confidence, to include the true value of a population parameter…

  7. Statistical Factors in Complexation Reactions.

    ERIC Educational Resources Information Center

    Chung, Chung-Sun

    1985-01-01

    Four cases which illustrate statistical factors in complexation reactions (where two of the reactants are monodentate ligands) are presented. Included are tables showing statistical factors for the reactions of: (1) square-planar complexes; (2) tetrahedral complexes; and (3) octahedral complexes. (JN)

  8. Statistical Methods in Psychology Journals.

    ERIC Educational Resources Information Center

    Willkinson, Leland

    1999-01-01

    Proposes guidelines for revising the American Psychological Association (APA) publication manual or other APA materials to clarify the application of statistics in research reports. The guidelines are intended to induce authors and editors to recognize the thoughtless application of statistical methods. Contains 54 references. (SLD)

  9. Transition from non-periodic to periodic explosions.

    PubMed

    Cartes, Carlos; Descalzi, Orazio

    2015-12-13

    We show the existence of periodic exploding dissipative solitons. These non-chaotic explosions appear when higher-order nonlinear and dispersive effects are added to the complex cubic-quintic Ginzburg-Landau equation modelling soliton transmission lines. This counterintuitive phenomenon is the result of period-halving bifurcations leading to order (periodic explosions), followed by period-doubling bifurcations (or intermittency) leading to chaos (non-periodic explosions). PMID:26527807

  10. Statistical anisotropies in gravitational waves in solid inflation

    SciTech Connect

    Akhshik, Mohammad; Emami, Razieh; Firouzjahi, Hassan; Wang, Yi E-mail: emami@ipm.ir E-mail: yw366@cam.ac.uk

    2014-09-01

    Solid inflation can support a long period of anisotropic inflation. We calculate the statistical anisotropies in the scalar and tensor power spectra and their cross-correlation in anisotropic solid inflation. The tensor-scalar cross-correlation can either be positive or negative, which impacts the statistical anisotropies of the TT and TB spectra in CMB map more significantly compared with the tensor self-correlation. The tensor power spectrum contains potentially comparable contributions from quadrupole and octopole angular patterns, which is different from the power spectra of scalar, the cross-correlation or the scalar bispectrum, where the quadrupole type statistical anisotropy dominates over octopole.

  11. Students' attitudes towards learning statistics

    NASA Astrophysics Data System (ADS)

    Ghulami, Hassan Rahnaward; Hamid, Mohd Rashid Ab; Zakaria, Roslinazairimah

    2015-05-01

    Positive attitude towards learning is vital in order to master the core content of the subject matters under study. This is unexceptional in learning statistics course especially at the university level. Therefore, this study investigates the students' attitude towards learning statistics. Six variables or constructs have been identified such as affect, cognitive competence, value, difficulty, interest, and effort. The instrument used for the study is questionnaire that was adopted and adapted from the reliable instrument of Survey of Attitudes towards Statistics(SATS©). This study is conducted to engineering undergraduate students in one of the university in the East Coast of Malaysia. The respondents consist of students who were taking the applied statistics course from different faculties. The results are analysed in terms of descriptive analysis and it contributes to the descriptive understanding of students' attitude towards the teaching and learning process of statistics.

  12. Probability, Information and Statistical Physics

    NASA Astrophysics Data System (ADS)

    Kuzemsky, A. L.

    2016-03-01

    In this short survey review we discuss foundational issues of the probabilistic approach to information theory and statistical mechanics from a unified standpoint. Emphasis is on the inter-relations between theories. The basic aim is tutorial, i.e. to carry out a basic introduction to the analysis and applications of probabilistic concepts to the description of various aspects of complexity and stochasticity. We consider probability as a foundational concept in statistical mechanics and review selected advances in the theoretical understanding of interrelation of the probability, information and statistical description with regard to basic notions of statistical mechanics of complex systems. It includes also a synthesis of past and present researches and a survey of methodology. The purpose of this terse overview is to discuss and partially describe those probabilistic methods and approaches that are used in statistical mechanics with the purpose of making these ideas easier to understanding and to apply.

  13. Detecting critical periods in larval flatfish populations

    NASA Astrophysics Data System (ADS)

    Chambers, R. Christopher; Witting, David A.; Lewis, Stephen J.

    2001-06-01

    We evaluate the time-course of deaths and evidence of periods of increased mortality (i.e., critical periods) in laboratory populations of larval flatfish. First, we make the distinction between age-at-death and abundance-at-time data for fish larvae, the latter being typical in studies of natural populations. Next, we describe an experimental investigation of age- and temperature-dependent mortality in larval winter flounder, Pseudopleuronectes americanus. The survivorship curves of these populations differed significantly in both the magnitude and time-course of mortality among the four water temperatures evaluated (7, 10, 13, and 16°C). Mortality was highest in the cooler temperatures and concentrated in the third quarter of larval life, largely concurrent with settlement of surviving members of the cohort. Among the statistical methods for analysing survival data, the proportional-hazards model with time-varying covariates proved best at capturing the patterns of age-specific mortalities. We conclude that fair appraisals of recruitment hypotheses which are predicated on periods of high, age-specific mortality that vary with environmental conditions (e.g., Hjort's critical period hypothesis) will require: (1) data that are based on age, not time; (2) data that are of higher temporal resolution than commonly available at present and (3) analytical methods that are sensitive to irregularities in survivorship curves. We suggest four research approaches for evaluating critical periods in nature.

  14. Periodically oscillating plasma sphere

    SciTech Connect

    Park, J.; Nebel, R.A.; Stange, S.; Murali, S. Krupakar

    2005-05-15

    The periodically oscillating plasma sphere, or POPS, is a novel fusion concept first proposed by D. C. Barnes and R. A. Nebel [Fusion Technol. 38, 28 (1998)]. POPS utilizes the self-similar collapse of an oscillating ion cloud in a spherical harmonic oscillator potential well formed by electron injection. Once the ions have been phase-locked, their coherent motion simultaneously produces very high densities and temperatures during the collapse phase of the oscillation. A requirement for POPS is that the electron injection produces a stable harmonic oscillator potential. This has been demonstrated in a gridded inertial electrostatic confinement device and verified by particle simulation. Also, the POPS oscillation has been confirmed experimentally through observation that the ions in the potential well exhibit resonance behavior when driven at the POPS frequency. Excellent agreement between the observed POPS frequencies and the theoretical predictions has been observed for a wide range of potential well depths and three different ion species. Practical applications of POPS require large plasma compressions. These large compressions have been observed in particle simulations, although space charge neutralization remains a major issue.

  15. On detecting and modeling periodic correlation in financial data

    NASA Astrophysics Data System (ADS)

    Broszkiewicz-Suwaj, E.; Makagon, A.; Weron, R.; Wyłomańska, A.

    2004-05-01

    For many economic problems standard statistical analysis, based on the notion of stationarity, is not adequate. These include modeling seasonal decisions of consumers, forecasting business cycles and-as we show in the present article-modeling wholesale power market prices. We apply standard methods and a novel spectral domain technique to conclude that electricity price returns exhibit periodic correlation with daily and weekly periods. As such they should be modeled with periodically correlated processes. We propose to apply periodic autoregression models which are closely related to the standard instruments in econometric analysis-vector autoregression models.

  16. Statistical Downscaling for the Northern Great Plains

    NASA Astrophysics Data System (ADS)

    Coburn, J.

    2014-12-01

    The need for detailed, local scale information about the warming climate has led to the use of ever more complex and geographically realistic computer models as well as the use of regional models capable of capturing much finer details. Another class of methods for ascertaining localized data is known as statistical downscaling, which offers some advantages over regional models, especially in the realm of computational efficiency. Statistical downscaling can be described as the process of linking coarse resolution climate model output to that of fine resolution or even station-level data via statistical relationships with the purpose of correcting model biases at the local scale. The development and application of downscaling has given rise to a plethora of techniques which have been applied to many spatial scales and multiple climate variables. In this study two downscaling processes, bias-corrected statistical downscaling (BCSD) and canonical correlation analysis (CCA), are applied to minimum and maximum temperatures and precipitation for the Northern Great Plains (NGP, 40 - 53°N and 95 - 120°W) region at both daily and monthly time steps. The abilities of the methods were tested by assessing their ability to recreate local variations in a set of both spatial and temporal climate metrics obtained through the analysis of 1/16 degree station data for the period 1950 to 2000. Model data for temperature, precipitation and a set of predictor variables were obtained from CMIP5 for 15 models. BCSD was applied using direct comparison and correction of the variable distributions via quadrant mapping. CCA was calibrated on the data for the period 1950 to 1980 using a series of model-based predictor variables screened for increasing skill, with the derived model being applied to the period 1980 to 2000 so as to verify that it could recreate the overall climate patterns and trends. As in previous studies done on other regions, it was found that the CCA method recreated

  17. [Big data in official statistics].

    PubMed

    Zwick, Markus

    2015-08-01

    The concept of "big data" stands to change the face of official statistics over the coming years, having an impact on almost all aspects of data production. The tasks of future statisticians will not necessarily be to produce new data, but rather to identify and make use of existing data to adequately describe social and economic phenomena. Until big data can be used correctly in official statistics, a lot of questions need to be answered and problems solved: the quality of data, data protection, privacy, and the sustainable availability are some of the more pressing issues to be addressed. The essential skills of official statisticians will undoubtedly change, and this implies a number of challenges to be faced by statistical education systems, in universities, and inside the statistical offices. The national statistical offices of the European Union have concluded a concrete strategy for exploring the possibilities of big data for official statistics, by means of the Big Data Roadmap and Action Plan 1.0. This is an important first step and will have a significant influence on implementing the concept of big data inside the statistical offices of Germany. PMID:26077871

  18. Statistic versus stochastic characterization of persistent droughts

    NASA Astrophysics Data System (ADS)

    Gonzalez-Perez, J.; Valdes, J. B.

    2005-12-01

    Droughts are one of more devastating natural disasters. A drought event is always related with deficiency in precipitation over a time period. As longer are the drought periods, larger are the damages associated with, following a potential relationship. Additionally, the extension covered by an event also increases its impact, because it makes difficult to compensate the deficit from neighbourhood water resources. Therefore, the characterization of a drought by its persistent deficit, and the area over which it extends are main points to be carried on. The Standardized Precipitation Index (SPI) provides a statistical characterization of the deficits. Its computation, for different aggregation time scales, allows a persistence evaluation. Another more recent statistic that may be applied in drought characterization is the extreme persistent probability function (e.p.f.), which characterizes the persistence of extreme realizations in a random sequence. This work presents an analysis of the differences in performance of the SPI and the e.p.f. in the statistical characterization of a drought event. The inclusion of the persistency directly in the statistic gives to the e.p.f. an advantage over the SPI. Furthermore, the relationship between the e.p.f. and its mean frequency of recurrence is known. Thus, the e.p.f. may be applied to provide either statistic or stochastic characterization of a drought event. Both criteria were compared, showing that the stochastic characterization produces a better drought indicator. The stochastic characterization using the e.p.f. as a criterion yields the new Drought Frequency Index (DFI). The index is applicable to any random water related variable to identify drought events. Its main advantages over the SPI are the direct inclusion of persistence, and its larger robustness to the time scale. To incorporate the spatial extension in the characterization of a drought event, the new DFI may also be evaluated to characterize the drought

  19. An introduction to statistical finance

    NASA Astrophysics Data System (ADS)

    Bouchaud, Jean-Philippe

    2002-10-01

    We summarize recent research in a rapid growing field, that of statistical finance, also called ‘econophysics’. There are three main themes in this activity: (i) empirical studies and the discovery of interesting universal features in the statistical texture of financial time series, (ii) the use of these empirical results to devise better models of risk and derivative pricing, of direct interest for the financial industry, and (iii) the study of ‘agent-based models’ in order to unveil the basic mechanisms that are responsible for the statistical ‘anomalies’ observed in financial time series. We give a brief overview of some of the results in these three directions.

  20. MOV reliability evaluation and periodic verification scheduling

    SciTech Connect

    Bunte, B.D.

    1996-12-01

    The purpose of this paper is to establish a periodic verification testing schedule based on the expected long term reliability of gate or globe motor operated valves (MOVs). The methodology in this position paper determines the nominal (best estimate) design margin for any MOV based on the best available information pertaining to the MOVs design requirements, design parameters, existing hardware design, and present setup. The uncertainty in this margin is then determined using statistical means. By comparing the nominal margin to the uncertainty, the reliability of the MOV is estimated. The methodology is appropriate for evaluating the reliability of MOVs in the GL 89-10 program. It may be used following periodic testing to evaluate and trend MOV performance and reliability. It may also be used to evaluate the impact of proposed modifications and maintenance activities such as packing adjustments. In addition, it may be used to assess the impact of new information of a generic nature which impacts safety related MOVs.

  1. Periodically distributed objects with quasicrystalline diffraction pattern

    SciTech Connect

    Wolny, Janusz Strzalka, Radoslaw; Kuczera, Pawel

    2015-03-30

    It is possible to construct fully periodically distributed objects with a diffraction pattern identical to the one obtained for quasicrystals. These objects are probability distributions of distances obtained in the statistical approach to aperiodic structures distributed periodically. The diffraction patterns have been derived by using a two-mode Fourier transform—a very powerful method not used in classical crystallography. It is shown that if scaling is present in the structure, this two-mode Fourier transform can be reduced to a regular Fourier transform with appropriately rescaled scattering vectors and added phases. Detailed case studies for model sets 1D Fibonacci chain and 2D Penrose tiling are discussed. Finally, it is shown that crystalline, quasicrystalline, and approximant structures can be treated in the same way.

  2. Back Pain Facts and Statistics

    MedlinePlus

    ... Pain and Depression Preventing Travel Aches and Strains Back Pain Facts and Statistics Although doctors of chiropractic (DCs) ... time. 1 A few interesting facts about back pain: Low back pain is the single leading cause of disability ...

  3. Statistical description of turbulent dispersion

    NASA Astrophysics Data System (ADS)

    Brouwers, J. J. H.

    2012-12-01

    We derive a comprehensive statistical model for dispersion of passive or almost passive admixture particles such as fine particulate matter, aerosols, smoke, and fumes in turbulent flow. The model rests on the Markov limit for particle velocity. It is in accordance with the asymptotic structure of turbulence at large Reynolds number as described by Kolmogorov. The model consists of Langevin and diffusion equations in which the damping and diffusivity are expressed by expansions in powers of the reciprocal Kolmogorov constant C0. We derive solutions of O(C00) and O(C0-1). We truncate at O(C0-2) which is shown to result in an error of a few percentages in predicted dispersion statistics for representative cases of turbulent flow. We reveal analogies and remarkable differences between the solutions of classical statistical mechanics and those of statistical turbulence.

  4. Statistical characterization of dislocation ensembles

    SciTech Connect

    El-Azab, A; Deng, J; Tang, M

    2006-05-17

    We outline a method to study the spatial and orientation statistics of dynamical dislocation systems by modeling the dislocations as a stochastic fiber process. Statistical measures have been introduced for the density, velocity, and flux of dislocations, and the connection between these measures and the dislocation state and plastic distortion rate in the crystal is explained. A dislocation dynamics simulation model has been used to extract numerical data to study the evolution of these statistical measures numerically in a body-centered cubic crystal under deformation. The orientation distribution of the dislocation density, velocity and dislocation flux, as well as the dislocation correlations have been computed. The importance of the statistical measures introduced here in building continuum models of dislocation systems is highlighted.

  5. Spina Bifida Data and Statistics

    MedlinePlus

    ... Materials About Us Information For... Media Policy Makers Data and Statistics Recommend on Facebook Tweet Share Compartir ... non-Hispanic white and non-Hispanic black women. Data from 12 state-based birth defects tracking programs ...

  6. Birth Defects Data and Statistics

    MedlinePlus

    ... Websites About Us Information For... Media Policy Makers Data & Statistics Language: English Español (Spanish) Recommend on Facebook ... of birth defects in the United States. For data on specific birth defects, please visit the specific ...

  7. Program for standard statistical distributions

    NASA Technical Reports Server (NTRS)

    Falls, L. W.

    1972-01-01

    Development of procedure to describe frequency distributions involved in statistical theory is discussed. Representation of frequency distributions by first order differential equation is presented. Classification of various types of distributions based on Pearson parameters is analyzed.

  8. STATISTICAL SAMPLING AND DATA ANALYSIS

    EPA Science Inventory

    Research is being conducted to develop approaches to improve soil and sediment sampling techniques, measurement design and geostatistics, and data analysis via chemometric, environmetric, and robust statistical methods. Improvements in sampling contaminated soil and other hetero...

  9. FUNSTAT and statistical image representations

    NASA Technical Reports Server (NTRS)

    Parzen, E.

    1983-01-01

    General ideas of functional statistical inference analysis of one sample and two samples, univariate and bivariate are outlined. ONESAM program is applied to analyze the univariate probability distributions of multi-spectral image data.

  10. Lagrangian statistics of light particles in turbulence

    NASA Astrophysics Data System (ADS)

    Mercado, Julián Martínez; Prakash, Vivek N.; Tagawa, Yoshiyuki; Sun, Chao; Lohse, Detlef; (International CollaborationTurbulence Research)

    2012-05-01

    We study the Lagrangian velocity and acceleration statistics of light particles (micro-bubbles in water) in homogeneous isotropic turbulence. Micro-bubbles with a diameter db = 340 μm and Stokes number from 0.02 to 0.09 are dispersed in a turbulent water tunnel operated at Taylor-Reynolds numbers (Reλ) ranging from 160 to 265. We reconstruct the bubble trajectories by employing three-dimensional particle tracking velocimetry. It is found that the probability density functions (PDFs) of the micro-bubble acceleration show a highly non-Gaussian behavior with flatness values in the range 23 to 30. The acceleration flatness values show an increasing trend with Reλ, consistent with previous experiments [G. Voth, A. La Porta, A. M. Crawford, J. Alexander, and E. Bodenschatz, "Measurement of particle accelerations in fully developed turbulence," J. Fluid Mech. 469, 121 (2002)], 10.1017/S0022112002001842 and numerics [T. Ishihara, Y. Kaneda, M. Yokokawa, K. Itakura, and A. Uno, "Small-scale statistics in highresolution direct numerical simulation of turbulence: Reynolds number dependence of one-point velocity gradient statistics," J. Fluid Mech. 592, 335 (2007)], 10.1017/S0022112007008531. These acceleration PDFs show a higher intermittency compared to tracers [S. Ayyalasomayajula, Z. Warhaft, and L. R. Collins, "Modeling inertial particle acceleration statistics in isotropic turbulence," Phys. Fluids. 20, 095104 (2008)], 10.1063/1.2976174 and heavy particles [S. Ayyalasomayajula, A. Gylfason, L. R. Collins, E. Bodenschatz, and Z. Warhaft, "Lagrangian measurements of inertial particle accelerations in grid generated wind tunnel turbulence," Phys. Rev. Lett. 97, 144507 (2006)], 10.1103/PhysRevLett.97.144507 in wind tunnel experiments. In addition, the micro-bubble acceleration autocorrelation function decorrelates slower with increasing Reλ. We also compare our results with experiments in von Kármán flows and point-particle direct numerical simulations with periodic

  11. Hidden Statistics of Schroedinger Equation

    NASA Technical Reports Server (NTRS)

    Zak, Michail

    2011-01-01

    Work was carried out in determination of the mathematical origin of randomness in quantum mechanics and creating a hidden statistics of Schr dinger equation; i.e., to expose the transitional stochastic process as a "bridge" to the quantum world. The governing equations of hidden statistics would preserve such properties of quantum physics as superposition, entanglement, and direct-product decomposability while allowing one to measure its state variables using classical methods.

  12. [Statistical process control in healthcare].

    PubMed

    Anhøj, Jacob; Bjørn, Brian

    2009-05-18

    Statistical process control (SPC) is a branch of statistical science which comprises methods for the study of process variation. Common cause variation is inherent in any process and predictable within limits. Special cause variation is unpredictable and indicates change in the process. The run chart is a simple tool for analysis of process variation. Run chart analysis may reveal anomalies that suggest shifts or unusual patterns that are attributable to special cause variation. PMID:19454196

  13. Period variations in SZ ARIETIS

    NASA Astrophysics Data System (ADS)

    Srivastava, R. K.

    1990-06-01

    Results are presented of a detailed period study of the eclipsing binary system SZ Arietis, based on up-to-date collection of minima. A new period (P = 1.7175405 d) of the SZ Ari was found, and the period changes (with the new period) in different portions of the O-C diagram were estimated. The average period change (leaving out an unusual value) was estimated to be about 0.00006 d. The O-C diagram displayed a sinusoidal variation, indicating that the SZ Ari system may be a three-body system, having a period of nearly 66 years.

  14. Calculating statistical distributions from operator relations: The statistical distributions of various intermediate statistics

    SciTech Connect

    Dai, Wu-Sheng Xie, Mi

    2013-05-15

    In this paper, we give a general discussion on the calculation of the statistical distribution from a given operator relation of creation, annihilation, and number operators. Our result shows that as long as the relation between the number operator and the creation and annihilation operators can be expressed as a{sup †}b=Λ(N) or N=Λ{sup −1}(a{sup †}b), where N, a{sup †}, and b denote the number, creation, and annihilation operators, i.e., N is a function of quadratic product of the creation and annihilation operators, the corresponding statistical distribution is the Gentile distribution, a statistical distribution in which the maximum occupation number is an arbitrary integer. As examples, we discuss the statistical distributions corresponding to various operator relations. In particular, besides the Bose–Einstein and Fermi–Dirac cases, we discuss the statistical distributions for various schemes of intermediate statistics, especially various q-deformation schemes. Our result shows that the statistical distributions corresponding to various q-deformation schemes are various Gentile distributions with different maximum occupation numbers which are determined by the deformation parameter q. This result shows that the results given in much literature on the q-deformation distribution are inaccurate or incomplete. -- Highlights: ► A general discussion on calculating statistical distribution from relations of creation, annihilation, and number operators. ► A systemic study on the statistical distributions corresponding to various q-deformation schemes. ► Arguing that many results of q-deformation distributions in literature are inaccurate or incomplete.

  15. Quantum mechanics from classical statistics

    SciTech Connect

    Wetterich, C.

    2010-04-15

    Quantum mechanics can emerge from classical statistics. A typical quantum system describes an isolated subsystem of a classical statistical ensemble with infinitely many classical states. The state of this subsystem can be characterized by only a few probabilistic observables. Their expectation values define a density matrix if they obey a 'purity constraint'. Then all the usual laws of quantum mechanics follow, including Heisenberg's uncertainty relation, entanglement and a violation of Bell's inequalities. No concepts beyond classical statistics are needed for quantum physics - the differences are only apparent and result from the particularities of those classical statistical systems which admit a quantum mechanical description. Born's rule for quantum mechanical probabilities follows from the probability concept for a classical statistical ensemble. In particular, we show how the non-commuting properties of quantum operators are associated to the use of conditional probabilities within the classical system, and how a unitary time evolution reflects the isolation of the subsystem. As an illustration, we discuss a classical statistical implementation of a quantum computer.

  16. Applied extreme-value statistics

    SciTech Connect

    Kinnison, R.R.

    1983-05-01

    The statistical theory of extreme values is a well established part of theoretical statistics. Unfortunately, it is seldom part of applied statistics and is infrequently a part of statistical curricula except in advanced studies programs. This has resulted in the impression that it is difficult to understand and not of practical value. In recent environmental and pollution literature, several short articles have appeared with the purpose of documenting all that is necessary for the practical application of extreme value theory to field problems (for example, Roberts, 1979). These articles are so concise that only a statistician can recognise all the subtleties and assumptions necessary for the correct use of the material presented. The intent of this text is to expand upon several recent articles, and to provide the necessary statistical background so that the non-statistician scientist can recognize and extreme value problem when it occurs in his work, be confident in handling simple extreme value problems himself, and know when the problem is statistically beyond his capabilities and requires consultation.

  17. [Period-tripling in Multiscale Physical and Biological Events].

    PubMed

    Bondar, A T; Fedorov, M V; Kolombet, V A

    2015-01-01

    A recent paper by S.J. Puetz et al. (Chaos, Solitons -& Fractals, v. 62-63, p. 55, 2014) described a fundamental period-tripled model. It involves periods of different astronomical (quasars, Sun), geophysical (geomagnetic, climatic, volcanic) and some biological processes. This work contains statistics for sixteen pairs of a period-tripled sequence. These periods range from -50 years to 1.5 billion years and no signs of the timescale limitations are found. We believe that the universal scope of the fundamental period-tripled model can be used for the development of new methodology of research data analysis: the main idea is that the spectrum of the periods of the studied event should be tested for the similarity with the spectrum of fundamental period-tripling pattern (because of the fundamental nature of the period-tripled model). Using this method, in this study we complement an already described period-tripled model with periods of human memory performance ranging from one minute to one month also adding seven relevant periods/frequencies of the period-tripled model in the range of human hearing. We make a conclusion that these characteristic frequencies may form the basis for music and singing phenomena. The new methodology is particularly appropriate for being applied in medicine and engineering. PMID:26841519

  18. Education Statistics Quarterly. Volume 4 Issue 4, 2002.

    ERIC Educational Resources Information Center

    National Center for Education Statistics, 2002

    2002-01-01

    This publication provides a comprehensive overview of work done across all parts of the National Center for Education Statistics (NCES). Each issue contains short publications, summaries, and descriptions that cover all NCES publications and data products released in a 3-month period. Each issue also contains a message from the NCES on a timely…

  19. DATA MANAGEMENT, STATISTICS AND COMMUNITY IMPACT MODELING CORE

    EPA Science Inventory

    EPA GRANT NUMBER: R832141C007
    Title: Data Management, Statistics and Community Impact Modeling Core
    Investigator: Frederica P Perera
    Institution: Columbia University
    EPA Project Officer: Nigel Fields
    Project Period: No...

  20. A BAYESIAN STATISTICAL APPROACH FOR THE EVALUATION OF CMAQ

    EPA Science Inventory

    Bayesian statistical methods are used to evaluate Community Multiscale Air Quality (CMAQ) model simulations of sulfate aerosol over a section of the eastern US for 4-week periods in summer and winter 2001. The observed data come from two U.S. Environmental Protection Agency data ...

  1. Statistics.

    PubMed

    1993-02-01

    In 1984, 99% of abortions conducted in Bombay, India, were of female fetuses. In 1986-87, 30,000-50,000 female fetuses were aborted in India. In 1987-88, 7 Delhi clinics conducted 13,000 sex determination tests. Thus, discrimination against females begins before birth in India. Some states (Maharashtra, Goa, and Gujarat) have drafted legislation to prevent the use of prenatal diagnostic tests (e.g., ultrasonography) for sex determination purposes. Families make decisions about an infant's nutrition based on the infant's sex so it is not surprising to see a higher incidence of morbidity among girls than boys (e.g., for respiratory infections in 1985, 55.5% vs. 27.3%). Consequently, they are more likely to die than boys. Even though vasectomy is simpler and safer than tubectomy, the government promotes female sterilizations. The percentage of all sexual sterilizations being tubectomy has increased steadily from 84% to 94% (1986-90). Family planning programs focus on female contraceptive methods, despite the higher incidence of adverse health effects from female methods (e.g., IUD causes pain and heavy bleeding). Some women advocates believe the effects to be so great that India should ban contraceptives and injectable contraceptives. The maternal mortality rate is quite high (460/100,000 live births), equaling a lifetime risk of 1:18 of a pregnancy-related death. 70% of these maternal deaths are preventable. Leading causes of maternal deaths in India are anemia, hemorrhage, eclampsia, sepsis, and abortion. Most pregnant women do not receive prenatal care. Untrained personnel attend about 70% of deliveries in rural areas and 29% in urban areas. Appropriate health services and other interventions would prevent the higher age specific death rates for females between 0 and 35 years old. Even though the government does provide maternal and child health services, it needs to stop decreasing resource allocate for health and start increasing it. PMID:12286355

  2. Doubly Resonant Optical Periodic Structure

    PubMed Central

    Alagappan, G.; Png, C. E.

    2016-01-01

    Periodic structures are well known in various branches of physics for their ability to provide a stopband. In this article, using optical periodic structures we showed that, when a second periodicity – very closed to the original periodicity is introduced, large number of states appears in the stopband corresponding to the first periodicity. In the limit where the two periods matches, we have a continuum of states, and the original stopband completely disappears. This intriguing phenomena is uncovered by noticing that, regardless of the proximities of the two periodicities, there is an array of spatial points where the dielectric functions corresponding to the two periodicities interfere destructively. These spatial points mimic photonic atoms by satisfying the standards equations of quantum harmonic oscillators, and exhibit lossless, atom-like dispersions. PMID:26853945

  3. The redoubtable ecological periodic table

    EPA Science Inventory

    Ecological periodic tables are repositories of reliable information on quantitative, predictably recurring (periodic) habitat–community patterns and their uncertainty, scaling and transferability. Their reliability derives from their grounding in sound ecological principle...

  4. Doubly Resonant Optical Periodic Structure.

    PubMed

    Alagappan, G; Png, C E

    2016-01-01

    Periodic structures are well known in various branches of physics for their ability to provide a stopband. In this article, using optical periodic structures we showed that, when a second periodicity - very closed to the original periodicity is introduced, large number of states appears in the stopband corresponding to the first periodicity. In the limit where the two periods matches, we have a continuum of states, and the original stopband completely disappears. This intriguing phenomena is uncovered by noticing that, regardless of the proximities of the two periodicities, there is an array of spatial points where the dielectric functions corresponding to the two periodicities interfere destructively. These spatial points mimic photonic atoms by satisfying the standards equations of quantum harmonic oscillators, and exhibit lossless, atom-like dispersions. PMID:26853945

  5. 76 FR 8325 - Periodic Reporting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-02-14

    ... certain temporary waivers from periodic reporting of service performance measurement. Establishing this...). SUPPLEMENTARY HISTORY: On February 3, 2011, the Postal Service filed a request for temporary waivers from periodic reporting of service performance measurement for various market dominant postal services,...

  6. Statistical postprocessing for precipitation forecasts during the West African Monsoon

    NASA Astrophysics Data System (ADS)

    Vogel, Peter; Gneiting, Tilmann; Knippertz, Peter; Fink, Andreas; Schlüter, Andreas

    2016-04-01

    Statistical postprocessing for ensemble forecasts has undergone many improvements recently. Commonly used methods are Bayesian Model Averaging (BMA) and Ensemble Model Output Statistics (EMOS), but have predominantly been applied over the midlatitudes (e.g. North America or Europe). The prediction of precipitation events during the wet period of the West African Monsoon (WAM) is highly challenging and ensemble forecasts for precipitation in West Africa during this period have low skill. The present contribution investigates for the first time how statistical postprocessing methods can improve precipitation forecasts to obtain calibrated and sharp predictive distributions. Perhaps surprisingly, the ECMWF ensemble is unable to outperform climatological forecasts. However, BMA and EMOS postprocessed forecasts can cope with the poor quality of the raw ensemble forecasts and yield predictive distributions that are as calibrated as, but sharper than, climatology.

  7. Betelgeuse Period Analysis Using VSTAR

    NASA Astrophysics Data System (ADS)

    Dempsey, F.

    2015-06-01

    (Abstract only) Betelgeuse was studied using the VSTAR software package and analysis of the observations in the AAVSO database. Period analysis derived a period of 376 days, in comparison with literature periods of 420 days using satellite UV data but significantly different from the VSX period of 2,335 days. The unique set of PEP observations of this star is also shown and advantage of PEP Johnson V observations is shown in comparison with the visual observations.

  8. Statistical validation of system models

    SciTech Connect

    Barney, P.; Ferregut, C.; Perez, L.E.; Hunter, N.F.; Paez, T.L.

    1997-01-01

    It is common practice in system analysis to develop mathematical models for system behavior. Frequently, the actual system being modeled is also available for testing and observation, and sometimes the test data are used to help identify the parameters of the mathematical model. However, no general-purpose technique exists for formally, statistically judging the quality of a model. This paper suggests a formal statistical procedure for the validation of mathematical models of systems when data taken during operation of the system are available. The statistical validation procedure is based on the bootstrap, and it seeks to build a framework where a statistical test of hypothesis can be run to determine whether or not a mathematical model is an acceptable model of a system with regard to user-specified measures of system behavior. The approach to model validation developed in this study uses experimental data to estimate the marginal and joint confidence intervals of statistics of interest of the system. These same measures of behavior are estimated for the mathematical model. The statistics of interest from the mathematical model are located relative to the confidence intervals for the statistics obtained from the experimental data. These relative locations are used to judge the accuracy of the mathematical model. An extension of the technique is also suggested, wherein randomness may be included in the mathematical model through the introduction of random variable and random process terms. These terms cause random system behavior that can be compared to the randomness in the bootstrap evaluation of experimental system behavior. In this framework, the stochastic mathematical model can be evaluated. A numerical example is presented to demonstrate the application of the technique.

  9. Assessing the relative effectiveness of statistical downscaling and distribution mapping in reproducing rainfall statistics based on climate model results

    NASA Astrophysics Data System (ADS)

    Langousis, Andreas; Mamalakis, Antonios; Deidda, Roberto; Marrocu, Marino

    2016-01-01

    To improve the level skill of climate models (CMs) in reproducing the statistics of daily rainfall at a basin level, two types of statistical approaches have been suggested. One is statistical correction of CM rainfall outputs based on historical series of precipitation. The other, usually referred to as statistical rainfall downscaling, is the use of stochastic models to conditionally simulate rainfall series, based on large-scale atmospheric forcing from CMs. While promising, the latter approach attracted reduced attention in recent years, since the developed downscaling schemes involved complex weather identification procedures, while demonstrating limited success in reproducing several statistical features of rainfall. In a recent effort, Langousis and Kaleris () developed a statistical framework for simulation of daily rainfall intensities conditional on upper-air variables, which is simpler to implement and more accurately reproduces several statistical properties of actual rainfall records. Here we study the relative performance of: (a) direct statistical correction of CM rainfall outputs using nonparametric distribution mapping, and (b) the statistical downscaling scheme of Langousis and Kaleris (), in reproducing the historical rainfall statistics, including rainfall extremes, at a regional level. This is done for an intermediate-sized catchment in Italy, i.e., the Flumendosa catchment, using rainfall and atmospheric data from four CMs of the ENSEMBLES project. The obtained results are promising, since the proposed downscaling scheme is more accurate and robust in reproducing a number of historical rainfall statistics, independent of the CM used and the characteristics of the calibration period. This is particularly the case for yearly rainfall maxima.

  10. The Relationship between Statistics Self-Efficacy, Statistics Anxiety, and Performance in an Introductory Graduate Statistics Course

    ERIC Educational Resources Information Center

    Schneider, William R.

    2011-01-01

    The purpose of this study was to determine the relationship between statistics self-efficacy, statistics anxiety, and performance in introductory graduate statistics courses. The study design compared two statistics self-efficacy measures developed by Finney and Schraw (2003), a statistics anxiety measure developed by Cruise and Wilkins (1980),…

  11. Thermodynamic Limit in Statistical Physics

    NASA Astrophysics Data System (ADS)

    Kuzemsky, A. L.

    2014-03-01

    The thermodynamic limit in statistical thermodynamics of many-particle systems is an important but often overlooked issue in the various applied studies of condensed matter physics. To settle this issue, we review tersely the past and present disposition of thermodynamic limiting procedure in the structure of the contemporary statistical mechanics and our current understanding of this problem. We pick out the ingenious approach by Bogoliubov, who developed a general formalism for establishing the limiting distribution functions in the form of formal series in powers of the density. In that study, he outlined the method of justification of the thermodynamic limit when he derived the generalized Boltzmann equations. To enrich and to weave our discussion, we take this opportunity to give a brief survey of the closely related problems, such as the equipartition of energy and the equivalence and nonequivalence of statistical ensembles. The validity of the equipartition of energy permits one to decide what are the boundaries of applicability of statistical mechanics. The major aim of this work is to provide a better qualitative understanding of the physical significance of the thermodynamic limit in modern statistical physics of the infinite and "small" many-particle systems.

  12. Ethical Statistics and Statistical Ethics: Making an Interdisciplinary Module

    ERIC Educational Resources Information Center

    Lesser, Lawrence M.; Nordenhaug, Erik

    2004-01-01

    This article describes an innovative curriculum module the first author created on the two-way exchange between statistics and applied ethics. The module, having no particular mathematical prerequisites beyond high school algebra, is part of an undergraduate interdisciplinary ethics course which begins with a 3-week introduction to basic applied…

  13. Statistics for People Who (Think They) Hate Statistics. Third Edition

    ERIC Educational Resources Information Center

    Salkind, Neil J.

    2007-01-01

    This text teaches an often intimidating and difficult subject in a way that is informative, personable, and clear. The author takes students through various statistical procedures, beginning with correlation and graphical representation of data and ending with inferential techniques and analysis of variance. In addition, the text covers SPSS, and…

  14. Michigan Library Statistical Report, 1999 Edition. Reporting 1998 Statistical Data.

    ERIC Educational Resources Information Center

    Krefman, Naomi, Comp.; Dwyer, Molly, Comp.; Krueger, Beth, Comp.

    This statistical report on Michigan's libraries presents data provided by academic libraries, public libraries, public library cooperatives, and those public libraries that that serve as regional or subregional outlets to provide services for blind and physically handicapped patrons. For academic libraries, data are compiled from the 1998 academic…

  15. The Statistical Loop Analyzer (SLA)

    NASA Technical Reports Server (NTRS)

    Lindsey, W. C.

    1985-01-01

    The statistical loop analyzer (SLA) is designed to automatically measure the acquisition, tracking and frequency stability performance characteristics of symbol synchronizers, code synchronizers, carrier tracking loops, and coherent transponders. Automated phase lock and system level tests can also be made using the SLA. Standard baseband, carrier and spread spectrum modulation techniques can be accomodated. Through the SLA's phase error jitter and cycle slip measurements the acquisition and tracking thresholds of the unit under test are determined; any false phase and frequency lock events are statistically analyzed and reported in the SLA output in probabilistic terms. Automated signal drop out tests can be performed in order to trouble shoot algorithms and evaluate the reacquisition statistics of the unit under test. Cycle slip rates and cycle slip probabilities can be measured using the SLA. These measurements, combined with bit error probability measurements, are all that are needed to fully characterize the acquisition and tracking performance of a digital communication system.

  16. Statistical Mechanics of Inhomogeneous Fluids

    NASA Astrophysics Data System (ADS)

    Schofield, P.; Henderson, J. R.

    1982-01-01

    The nature of the microscopic stress tensor in an inhomogenous fluid is discussed, with emphasis on the statistical mechanics of drops. Changes in free energy for isothermal deformations of a fluid are expressible as volume integrals of the stress tensor 'times' a strain terror. A particular radial distortion of a drop leads to statistical mechanical expressions for the pressure difference across the surface of the drop. We find that the stress tensor is not uniquely defined by the microscopic laws embodying conservation of momentum and angular momentum and that the ambiguity remains in the ensemble average, or pressure tensor, in regions of inhomomogeneity. This leads to difficulties in defining statistical mechanical expressions for the surface tension of a drop.

  17. Statistical prediction of cyclostationary processes

    SciTech Connect

    Kim, K.Y.

    2000-03-15

    Considered in this study is a cyclostationary generalization of an EOF-based prediction method. While linear statistical prediction methods are typically optimal in the sense that prediction error variance is minimal within the assumption of stationarity, there is some room for improved performance since many physical processes are not stationary. For instance, El Nino is known to be strongly phase locked with the seasonal cycle, which suggests nonstationarity of the El Nino statistics. Many geophysical and climatological processes may be termed cyclostationary since their statistics show strong cyclicity instead of stationarity. Therefore, developed in this study is a cyclostationary prediction method. Test results demonstrate that performance of prediction methods can be improved significantly by accounting for the cyclostationarity of underlying processes. The improvement comes from an accurate rendition of covariance structure both in space and time.

  18. Statistical modeling of software reliability

    NASA Technical Reports Server (NTRS)

    Miller, Douglas R.

    1992-01-01

    This working paper discusses the statistical simulation part of a controlled software development experiment being conducted under the direction of the System Validation Methods Branch, Information Systems Division, NASA Langley Research Center. The experiment uses guidance and control software (GCS) aboard a fictitious planetary landing spacecraft: real-time control software operating on a transient mission. Software execution is simulated to study the statistical aspects of reliability and other failure characteristics of the software during development, testing, and random usage. Quantification of software reliability is a major goal. Various reliability concepts are discussed. Experiments are described for performing simulations and collecting appropriate simulated software performance and failure data. This data is then used to make statistical inferences about the quality of the software development and verification processes as well as inferences about the reliability of software versions and reliability growth under random testing and debugging.

  19. A Simple Statistical Thermodynamics Experiment

    NASA Astrophysics Data System (ADS)

    LoPresto, Michael C.

    2010-03-01

    Comparing the predicted and actual rolls of combinations of both two and three dice can help to introduce many of the basic concepts of statistical thermodynamics, including multiplicity, probability, microstates, and macrostates, and demonstrate that entropy is indeed a measure of randomness, that disordered states (those of higher entropy) are more likely than more ordered ones. It can also show that predictions based on statistics are more accurate with larger samples of data. What follows is a simple experiment introducing some of the basic elements of statistical thermodynamics that can be a light and even fun way to end a unit on thermodynamics, often the end of a challenging first semester of introductory physics.

  20. The Genesis Mission Solar Wind Collection: Solar-Wind Statistics over the Period of Collection

    NASA Technical Reports Server (NTRS)

    Barraclough, B. L.; Wiens, R. C.; Steinberg, J. E.; Reisenfeld, D. B.; Neugebauer, M.; Burnett, D. S.; Gosling, J.; Bremmer, R. R.

    2004-01-01

    The NASA Genesis spacecraft was launched August 8, 2001 on a mission to collect samples of solar wind for 2 years and return them to earth September 8, 2004. Detailed analyses of the solar wind ions implanted into high-purity collection substrates will be carried out using various mass spectrometry techniques. These analyses are expected to determine key isotopic ratios and elemental abundances in the solar wind, and by extension, in the solar photosphere. Further, the photospheric composition is thought to be representative of the solar nebula with a few exceptions, so that the Genesis mission will provide a baseline for the average solar nebula composition with which to compare present-day compositions of planets, meteorites, and asteroids. The collection of solar wind samples is almost complete. Collection began for most substrates in early December, 2001, and is scheduled to be complete on April 2 of this year. It is critical to understand the solar-wind conditions during the collection phase of the mission. For this reason, plasma ion and electron spectrometers are continuously monitoring the solar wind proton density, velocity, temperature, the alpha/proton ratio, and angular distribution of suprathermal electrons. Here we report on the solar-wind conditions as observed by these in-situ instruments during the first half of the collection phase of the mission, from December, 2001 to present.

  1. Information capacity and pattern formation in a tent map network featuring statistical periodicity

    NASA Astrophysics Data System (ADS)

    Hauptmann, C.; Touchette, H.; Mackey, M. C.

    2003-02-01

    We provide quantitative support to the observation that lattices of coupled maps are “efficient” information coding devices. It has been suggested recently that lattices of coupled maps may provide a model of information coding in the nervous system because of their ability to create structured and stimulus-dependent activity patterns which have the potential to be used for storing information. In this paper, we give an upper bound to the effective number of patterns that can be used to store information in the lattice by evaluating numerically its information capacity or information rate as a function of the coupling strength between the maps. We also estimate the time taken by the lattice to establish a limiting activity pattern.

  2. Illustrating the practice of statistics

    SciTech Connect

    Hamada, Christina A; Hamada, Michael S

    2009-01-01

    The practice of statistics involves analyzing data and planning data collection schemes to answer scientific questions. Issues often arise with the data that must be dealt with and can lead to new procedures. In analyzing data, these issues can sometimes be addressed through the statistical models that are developed. Simulation can also be helpful in evaluating a new procedure. Moreover, simulation coupled with optimization can be used to plan a data collection scheme. The practice of statistics as just described is much more than just using a statistical package. In analyzing the data, it involves understanding the scientific problem and incorporating the scientist's knowledge. In modeling the data, it involves understanding how the data were collected and accounting for limitations of the data where possible. Moreover, the modeling is likely to be iterative by considering a series of models and evaluating the fit of these models. Designing a data collection scheme involves understanding the scientist's goal and staying within hislher budget in terms of time and the available resources. Consequently, a practicing statistician is faced with such tasks and requires skills and tools to do them quickly. We have written this article for students to provide a glimpse of the practice of statistics. To illustrate the practice of statistics, we consider a problem motivated by some precipitation data that our relative, Masaru Hamada, collected some years ago. We describe his rain gauge observational study in Section 2. We describe modeling and an initial analysis of the precipitation data in Section 3. In Section 4, we consider alternative analyses that address potential issues with the precipitation data. In Section 5, we consider the impact of incorporating additional infonnation. We design a data collection scheme to illustrate the use of simulation and optimization in Section 6. We conclude this article in Section 7 with a discussion.

  3. Statistics of the Bureau Veritas

    NASA Technical Reports Server (NTRS)

    Volmerange, Andre

    1932-01-01

    Statistics are indispensable factors for the amelioration of safety. Through the reconciliation of accidents which may appear isolated to interested parties, they permit tracking of typical causes of accidents; conversely, they can prevent, after a serious accident due to some fortuitous cause, the taking of incautious measures under the pressure of public opinion, which always inclines to gauge the gravity of the causes by that of the results. Lastly, they permit appraisal of the efficacy of rules in force. We should add that statistics provide an agency of prevention for future accidents. A careful inspection of all signs of malfunction of material quite often prevents the occurrence of an accident. In this respect, many pilot's report, perfectly normal in every way as far as operation is concerned, can reveal much more interesting technical data than an accident, although it does not diminish the importance of statistics. Therefore, from the inception of its aeronautical service, at the end of 1922, the Bureau Veritas has kept annual statistics of all accidents which occurred in French civil aviation. In order to correctly perform their proper function, the statistics must be exact and sufficiently explicit and complete. To be exact, they must bear on all pertinent events, and on these alone. It is a matter then, first of all, defining the accident in such a way that no sinister detail bearing on the definition may escape control. The consideration of accidents to personnel only has appeared too limited. One of the essential qualities of statistics is to permit the taking of averages and in consequence to apply them ot a sufficiently large number; such is happily not the case in accidents to personnel.

  4. Directory of Michigan Library Statistics. 1994 Edition. Reporting 1992 and 1993 Statistical Activities including: Public Library Statistics, Library Cooperative Statistics, Regional/Subregional Statistics.

    ERIC Educational Resources Information Center

    Leaf, Donald C., Comp.; Neely, Linda, Comp.

    This edition focuses on statistical data supplied by Michigan public libraries, public library cooperatives, and those public libraries which serve as regional or subregional outlets for blind and physically handicapped services. Since statistics in Michigan academic libraries are typically collected in odd-numbered years, they are not included…

  5. Large minimal period orbits of periodic autonomous systems

    NASA Astrophysics Data System (ADS)

    Campos, Juan; Tarallo, Massimo

    2004-01-01

    We prove the existence of periodic orbits with minimal period greater than any prescribed number for a natural Lagrangian autonomous system in several variables that is analytic and periodic in each variable and whose potential is nonconstant. Work supported by Acción Integrada Italia-España HI2000-0112, Azione Integrata Italia-Spagna IT-117, MCYT BFM2002-01308, Spain.

  6. Positive periodic solutions of delayed periodic Lotka-Volterra systems

    NASA Astrophysics Data System (ADS)

    Lin, Wei; Chen, Tianping

    2005-01-01

    In this Letter, for a general class of delayed periodic Lotka-Volterra systems, we prove some new results on the existence of positive periodic solutions by Schauder's fixed point theorem. The global asymptotical stability of positive periodic solutions is discussed further, and conditions for exponential convergence are given. The conditions we obtained are weaker than the previously known ones and can be easily reduced to several special cases.

  7. Statistical dependency in visual scanning

    NASA Technical Reports Server (NTRS)

    Ellis, Stephen R.; Stark, Lawrence

    1986-01-01

    A method to identify statistical dependencies in the positions of eye fixations is developed and applied to eye movement data from subjects who viewed dynamic displays of air traffic and judged future relative position of aircraft. Analysis of approximately 23,000 fixations on points of interest on the display identified statistical dependencies in scanning that were independent of the physical placement of the points of interest. Identification of these dependencies is inconsistent with random-sampling-based theories used to model visual search and information seeking.

  8. The Statistics of Visual Representation

    NASA Technical Reports Server (NTRS)

    Jobson, Daniel J.; Rahman, Zia-Ur; Woodell, Glenn A.

    2002-01-01

    The experience of retinex image processing has prompted us to reconsider fundamental aspects of imaging and image processing. Foremost is the idea that a good visual representation requires a non-linear transformation of the recorded (approximately linear) image data. Further, this transformation appears to converge on a specific distribution. Here we investigate the connection between numerical and visual phenomena. Specifically the questions explored are: (1) Is there a well-defined consistent statistical character associated with good visual representations? (2) Does there exist an ideal visual image? And (3) what are its statistical properties?

  9. Statistical parameters for gloss evaluation

    SciTech Connect

    Peiponen, Kai-Erik; Juuti, Mikko

    2006-02-13

    The measurement of minute changes in local gloss has not been presented in international standards due to a lack of suitable glossmeters. The development of a diffractive-element-based glossmeter (DOG) made it possible to detect local variation of gloss from planar and complex-shaped surfaces. Hence, a demand for proper statistical gloss parameters for classifying surface quality by gloss, similar to the standardized surface roughness classification, has become necessary. In this letter, we define statistical gloss parameters and utilize them as an example in the characterization of gloss from metal surface roughness standards by the DOG.

  10. Statistical Mechanics of Prion Diseases

    SciTech Connect

    Slepoy, A.; Singh, R. R. P.; Pazmandi, F.; Kulkarni, R. V.; Cox, D. L.

    2001-07-30

    We present a two-dimensional, lattice based, protein-level statistical mechanical model for prion diseases (e.g., mad cow disease) with concomitant prion protein misfolding and aggregation. Our studies lead us to the hypothesis that the observed broad incubation time distribution in epidemiological data reflect fluctuation dominated growth seeded by a few nanometer scale aggregates, while much narrower incubation time distributions for innoculated lab animals arise from statistical self-averaging. We model ''species barriers'' to prion infection and assess a related treatment protocol.

  11. Statistical Mechanics of Prion Diseases

    NASA Astrophysics Data System (ADS)

    Slepoy, A.; Singh, R. R.; Pázmándi, F.; Kulkarni, R. V.; Cox, D. L.

    2001-07-01

    We present a two-dimensional, lattice based, protein-level statistical mechanical model for prion diseases (e.g., mad cow disease) with concomitant prion protein misfolding and aggregation. Our studies lead us to the hypothesis that the observed broad incubation time distribution in epidemiological data reflect fluctuation dominated growth seeded by a few nanometer scale aggregates, while much narrower incubation time distributions for innoculated lab animals arise from statistical self-averaging. We model ``species barriers'' to prion infection and assess a related treatment protocol.

  12. Statistical mechanics of prion diseases.

    PubMed

    Slepoy, A; Singh, R R; Pázmándi, F; Kulkarni, R V; Cox, D L

    2001-07-30

    We present a two-dimensional, lattice based, protein-level statistical mechanical model for prion diseases (e.g., mad cow disease) with concomitant prion protein misfolding and aggregation. Our studies lead us to the hypothesis that the observed broad incubation time distribution in epidemiological data reflect fluctuation dominated growth seeded by a few nanometer scale aggregates, while much narrower incubation time distributions for innoculated lab animals arise from statistical self-averaging. We model "species barriers" to prion infection and assess a related treatment protocol. PMID:11497806

  13. Ranald Macdonald and statistical inference.

    PubMed

    Smith, Philip T

    2009-05-01

    Ranald Roderick Macdonald (1945-2007) was an important contributor to mathematical psychology in the UK, as a referee and action editor for British Journal of Mathematical and Statistical Psychology and as a participant and organizer at the British Psychological Society's Mathematics, statistics and computing section meetings. This appreciation argues that his most important contribution was to the foundations of significance testing, where his concern about what information was relevant in interpreting the results of significance tests led him to be a persuasive advocate for the 'Weak Fisherian' form of hypothesis testing. PMID:19351454

  14. Statistical Analysis in Climate Research

    NASA Astrophysics Data System (ADS)

    von Storch, Hans; Zwiers, Francis W.

    2002-03-01

    The purpose of this book is to help the climatologist understand the basic precepts of the statistician's art and to provide some of the background needed to apply statistical methodology correctly and usefully. The book is self contained: introductory material, standard advanced techniques, and the specialized techniques used specifically by climatologists are all contained within this one source. There are a wealth of real-world examples drawn from the climate literature to demonstrate the need, power and pitfalls of statistical analysis in climate research.

  15. Probability, statistics, and computational science.

    PubMed

    Beerenwinkel, Niko; Siebourg, Juliane

    2012-01-01

    In this chapter, we review basic concepts from probability theory and computational statistics that are fundamental to evolutionary genomics. We provide a very basic introduction to statistical modeling and discuss general principles, including maximum likelihood and Bayesian inference. Markov chains, hidden Markov models, and Bayesian network models are introduced in more detail as they occur frequently and in many variations in genomics applications. In particular, we discuss efficient inference algorithms and methods for learning these models from partially observed data. Several simple examples are given throughout the text, some of which point to models that are discussed in more detail in subsequent chapters. PMID:22407706

  16. Vector statistics of LANDSAT imagery

    NASA Technical Reports Server (NTRS)

    Jayroe, R. R., Jr.; Underwood, D.

    1977-01-01

    A digitized multispectral image, such as LANDSAT data, is composed of numerous four dimensional vectors, which quantitatively describe the ground scene from which the data are acquired. The statistics of unique vectors that occur in LANDSAT imagery are studied to determine if that information can provide some guidance on reducing image processing costs. A second purpose of this report is to investigate how the vector statistics are changed by various types of image processing techniques and determine if that information can be useful in choosing one processing approach over another.

  17. Key China Energy Statistics 2012

    SciTech Connect

    Levine, Mark; Fridley, David; Lu, Hongyou; Fino-Chen, Cecilia

    2012-05-01

    The China Energy Group at Lawrence Berkeley National Laboratory (LBNL) was established in 1988. Over the years the Group has gained recognition as an authoritative source of China energy statistics through the publication of its China Energy Databook (CED). The Group has published seven editions to date of the CED (http://china.lbl.gov/research/chinaenergy-databook). This handbook summarizes key statistics from the CED and is expressly modeled on the International Energy Agency’s “Key World Energy Statistics” series of publications. The handbook contains timely, clearly-presented data on the supply, transformation, and consumption of all major energy sources.

  18. Key China Energy Statistics 2011

    SciTech Connect

    Levine, Mark; Fridley, David; Lu, Hongyou; Fino-Chen, Cecilia

    2012-01-15

    The China Energy Group at Lawrence Berkeley National Laboratory (LBNL) was established in 1988. Over the years the Group has gained recognition as an authoritative source of China energy statistics through the publication of its China Energy Databook (CED). In 2008 the Group published the Seventh Edition of the CED (http://china.lbl.gov/research/chinaenergy-databook). This handbook summarizes key statistics from the CED and is expressly modeled on the International Energy Agency’s “Key World Energy Statistics” series of publications. The handbook contains timely, clearly-presented data on the supply, transformation, and consumption of all major energy sources.

  19. 20 CFR 634.4 - Statistical standards.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 3 2012-04-01 2012-04-01 false Statistical standards. 634.4 Section 634.4... System § 634.4 Statistical standards. Recipients shall agree to provide required data following the statistical standards prescribed by the Bureau of Labor Statistics for cooperative statistical programs....

  20. 20 CFR 634.4 - Statistical standards.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 20 Employees' Benefits 3 2010-04-01 2010-04-01 false Statistical standards. 634.4 Section 634.4... System § 634.4 Statistical standards. Recipients shall agree to provide required data following the statistical standards prescribed by the Bureau of Labor Statistics for cooperative statistical programs....

  1. 20 CFR 634.4 - Statistical standards.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 20 Employees' Benefits 3 2011-04-01 2011-04-01 false Statistical standards. 634.4 Section 634.4... System § 634.4 Statistical standards. Recipients shall agree to provide required data following the statistical standards prescribed by the Bureau of Labor Statistics for cooperative statistical programs....

  2. Teaching Statistics in Integration with Psychology

    ERIC Educational Resources Information Center

    Wiberg, Marie

    2009-01-01

    The aim was to revise a statistics course in order to get the students motivated to learn statistics and to integrate statistics more throughout a psychology course. Further, we wish to make students become more interested in statistics and to help them see the importance of using statistics in psychology research. To achieve this goal, several…

  3. About the Rotational Period of Ry-Tauri

    NASA Astrophysics Data System (ADS)

    Redkina, N. P.; Zausaeva, O. G.

    1987-12-01

    The results of a statistical analysis of photoelectric observations of the T Tauri star RY Tau are given. The computer program is based on the independent algorithms of Jurkevich and Kurochkin and Deeming's function Sν. A probable rotational period of RV Tau (6d.54) is found.

  4. Magnetospheric Periodicities at Saturn Equinox

    NASA Astrophysics Data System (ADS)

    Carbary, J. F.; Mitchell, D. G.; Roelof, E.; Paranicas, C.; Krimigis, S. M.; Krupp, N.; Hamilton, D. C.; Dougherty, M. K.

    2010-12-01

    For several years before equinox, the energetic charged and neutral particles in Saturn’s magnetosphere displayed strong periodicities near 10.8 hours, the same period observed in radio emissions and magnetic fields. These particle periodicities have now been observed at equinox in electrons, protons, oxygen ions, and neutral hydrogen and oxygen atoms at all energies greater than ~3 keV, the lowest energies measured by the Magnetospheric IMaging Instrument (MIMI) on the Cassini spacecraft. The equinoctial electrons exhibit a very strong period at 10.72 hours, while the protons have essentially no periodicity at all. Water group ions display a notable period at 10.73 hours. Both the electrons and the ions have curious overtones in their spectral structure that may be related to solar wind modulation. The energetic neutral hydrogen and oxygen atoms have strong periods of 10.79 hours at equinox. Within the uncertainties of the measurements, the ENA periods are slightly longer than the charged particle periods, although they cover a somewhat different time interval. For comparison, the Cassini magnetometer observed periodicities in Saturn’s magnetic field of 10.65 hours during the same equinoctial interval. These observations will be interpreted in terms of a wavy magnetodisk model.

  5. Credibility of statistical downscaling under nonstationary climate

    NASA Astrophysics Data System (ADS)

    Salvi, Kaustubh; Ghosh, Subimal; Ganguly, Auroop R.

    2016-03-01

    Statistical downscaling (SD) establishes empirical relationships between coarse-resolution climate model simulations with higher-resolution climate variables of interest to stakeholders. These statistical relations are estimated based on historical observations at the finer resolutions and used for future projections. The implicit assumption is that the SD relations, extracted from data are stationary or remain unaltered, despite non-stationary change in climate. The validity of this assumption relates directly to the credibility of SD. Falsifiability of climate projections is a challenging proposition. Calibration and verification, while necessary for SD, are unlikely to be able to reproduce the full range of behavior that could manifest at decadal to century scale lead times. We propose a design-of-experiments (DOE) strategy to assess SD performance under nonstationary climate and evaluate the strategy via a transfer-function based SD approach. The strategy relies on selection of calibration and validation periods such that they represent contrasting climatic conditions like hot-versus-cold and ENSO-versus-non-ENSO years. The underlying assumption is that conditions such as warming or predominance of El Niño may be more prevalent under climate change. In addition, two different historical time periods are identified, which resemble pre-industrial and the most severe future emissions scenarios. The ability of the empirical relations to generalize under these proxy conditions is considered an indicator of their performance under future nonstationarity. Case studies over two climatologically disjoint study regions, specifically India and Northeast United States, reveal robustness of DOE in identifying the locations where nonstationarity prevails as well as the role of effective predictor selection under nonstationarity.

  6. Statistical properties of record-breaking temperatures.

    PubMed

    Newman, William I; Malamud, Bruce D; Turcotte, Donald L

    2010-12-01

    A record-breaking temperature is the highest or lowest temperature at a station since the period of time considered began. The temperatures at a station constitute a time series. After the removal of daily and annual periodicities, the primary considerations are trends (i.e., global warming) and long-range correlations. We first carry out Monte Carlo simulations to determine the influence of trends and long-range correlations on record-breaking statistics. We take a time series that is a Gaussian white noise and give the classic record-breaking theory results for an independent and identically distributed process. We then carry out simulations to determine the influence of long-range correlations and linear temperature trends. For the range of fractional Gaussian noises that are observed to be applicable to temperature time series, the influence on the record-breaking statistics is less than 10%. We next superimpose a linear trend on a Gaussian white noise and extend the theory to include the effect of an additive trend. We determine the ratios of the number of maximum to the number of minimum record-breaking temperatures. We find the single governing parameter to be the ratio of the temperature change per year to the standard deviation of the underlying white noise. To test our approach, we consider a 30 yr record of temperatures at the Mauna Loa Observatory for 1977-2006. We determine the temperature trends by direct measurements and use our simulations to infer trends from the number of record-breaking temperatures. The two approaches give values that are in good agreement. We find that the warming trend is primarily due to an increase in the (overnight) minimum temperatures, while the maximum (daytime) temperatures are approximately constant. PMID:21230709

  7. Molecular clouds and periodic events in the geologic past

    NASA Technical Reports Server (NTRS)

    Thaddeus, P.

    1986-01-01

    The suggestion that a claimed 30 Myr period in the geologic past resulted from cometary impacts following encounters with molecular clouds as the solar system oscillates about the galactic plane poses a well-defined problem in the theory of shot noise. All recent CO surveys of the Galaxy clearly indicate that the concentration of molecular clouds in the galactic plane is not sufficient to allow a statistically significant period to be extracted from the small number of dated events. Of the order of 1000 events is probably required to obtain a credible period.

  8. Comprehensive Flux Occurrence Statistics at Geosynchronous Orbit

    NASA Astrophysics Data System (ADS)

    Thomsen, M. F.; Denton, M. H.; Bodeau, M.

    2005-12-01

    Geosynchronous orbit, the distance at which the orbital period around the Earth is 24 hours, is home to more than 200 satellites. From a space weather perspective, the environment in this orbit is highly variable and far from benign. Satellites exposed to these harsh conditions are subject to episodes of deep dielectric charging, surface charging, solar panel degradation, single event upsets, radiation degradation of optical coatings and paints, and other deleterious effects. Either suddenly or gradually over time, such effects can cause catastrophic or simply lifetime-shortening consequences for satellite systems. To protect against these environmental effects, spacecraft designers need to know quantitatively what the nature of the environment is likely to be over the design lifetime of their satellites. In recent years a number of such statistical analyses have been conducted, demonstrating the systematic dependence of geosynchronous plasma properties on orbital position, geomagnetic activity, and phase of the solar cycle. These studies have helped illuminate the physical processes that govern the nature of the plasma at geosynchronous orbit, but they do not provide a condensed description of the environment that is suitable for use by spacecraft designers. We report here a definitive statistical characterization of the geosynchronous environment that will be more useful for such purposes. The analysis is based on the LANL MPA geosynchronous plasma dataset, which now comprises more than 70 satellite-years of measurements extending well over a full solar cycle. We present the flux occurrence statistics of ions and electrons with energies in the range from ~1 eV to ~45 keV, covering the populations that are responsible for satellite surface charging and radiation damage to surface materials, and that provide the source for the higher-energy ring current and radiation belts. Significant differences have been found in long-term averages compared to the AE-8, AP-8

  9. On the statistics of magnetotelluric rotational invariants

    NASA Astrophysics Data System (ADS)

    Chave, Alan D.

    2014-01-01

    The statistical properties of the Swift skew, the phase-sensitive skew and the WAL invariants I1-I7 and Q are examined through analytic derivation of their probability density functions and/or simulation based on a Gaussian model for the magnetotelluric response tensor. The WAL invariants I1-I2 are shown to be distributed as a folded Gaussian, and are statistically well behaved in the sense that all of their moments are defined. The probability density functions for Swift skew, phase-sensitive skew and the WAL invariants I3-I4, I7 and Q are derived analytically or by simulation, and are shown to have no moments of order 2 or more. Since their support is semi-infinite or infinite, they cannot be represented trigonometrically, and hence are inconsistent with a Mohr circle interpretation. By contrast, the WAL invariants I5-I6 are supported on [ - 1, 1], and are inferred to have a beta distribution based on analysis and simulation. Estimation of rotational invariants from data is described using two approaches: as the ratio of magnetotelluric responses that are themselves averages, and as averages of section-by-section estimates of the invariant. Confidence intervals on the former utilize either Fieller's theorem, which is preferred because it is capable of yielding semi-infinite or infinite confidence intervals, or the less accurate delta method. Because section-by-section averages of most of the rotational invariants are drawn from distributions with infinite variance, the classical central limit theorem does not pertain. Instead, their averaging is accomplished using the median in place of the mean for location and an order statistic model to bound the confidence interval of the median. An example using real data demonstrates that the ratio of averages approach has serious systematic bias issues that render the result physically inconsistent, while the average of ratios result is a smooth, physically interpretable function of period, and is the preferred approach.

  10. Statistical tests for prediction of lignite quality

    SciTech Connect

    C.J. Kolovos

    2007-06-15

    Domestic lignite from large, bucket wheel excavators based open pit mines is the main fuel for electricity generation in Greece. Lignite from one or more mines may arrive at any power plant stockyard. The mixture obtained constitutes the lignite fuel fed to the power plant. The fuel is sampled in regular time intervals. These samples are considered as results of observations of values of spatial random variables. The aim was to form and statistically test many small sample populations. Statistical tests on the values of the humidity content, the ash-water free content, and the lower heating value of the lignite fuel indicated that the sample values form a normal population. The Kolmogorov-Smirnov test was applied for testing goodness-of-fit of sample distribution for a three year period and different power plants of the Kozani-Ptolemais area, western Macedonia, Greece. The normal distribution hypothesis can be widely accepted for forecasting the distribution of values of the basic quality characteristics even for a small number of samples.

  11. Statistics of Plasmaspheric Hiss Poynting Flux

    NASA Astrophysics Data System (ADS)

    Kletzing, C.; Christopher, I.; Santolik, O.; Kurth, W. S.; Hospodarsky, G. B.; Bounds, S. R.

    2015-12-01

    The measured wave properties of plasmaspheric hiss are important to constrain modelsof the generation of hiss as well as its propagation and amplification. For example,the generation mechanism for plasmaspheric hiss has been suggestedto come from one of three possible mechanisms: 1) local generationand amplification, 2) whistlers from lightning, and 3) chorus emissions which have refracted into the plasmasphere. The latter two mechanismsare external sources which produce an incoherent hiss signature as the original waves mix in a stochastic manner, propagating in both directions along the background magnetic field. In contrast, local generation of plasmaspheric hiss within the plasmasphere should produce a signatureof waves propagating away from the source region. For all three mechanismsscattering of energetic particles into the loss cone transfers some energyfrom the particles to the waves. By examining the statistical characteristics of the Poynting flux of plasmaspheric hiss, we can determine the propertiesof wave energy flow in the plasmasphere. We report on the statistics of observations from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) Waves instrument on the Van Allen Probes for periods when the spacecraft is inside the plasmasphere. We find that the Poynting flux associated with plasmaspheric hiss has distinct and unexpectedstructure in the Poynting flux which shows significant, organized variation in the properties of these waves as a function of position and and frequency.

  12. Spectral statistics in the quantized cardioid billiard

    NASA Astrophysics Data System (ADS)

    Bäcker, A.; Steiner, F.; Stifter, P.

    1995-09-01

    The spectral statistics of the strongly chaotic cardioid billiard is studied. The analysis is based on the first 11 000 quantal energy levels for both odd and even symmetry. It is found that the level-spacing distribution is in good agreement with the Gaussian-orthogonal-ensemble distribution of random-matrix theory. In the cases of the number variance and rigidity we observe agreement with the random-matrix model for short-range correlations only, whereas for long-range correlations both statistics saturate in agreement with semiclassical expectations. Furthermore the conjecture that for classically chaotic systems the normalized mode fluctuations have a universal Gaussian distribution with unit variance is tested and found to be in very good agreement for both symmetry classes. By means of the Gutzwiller trace formula the trace of the cosine-modulated heat kernel is studied. Since the billiard boundary is focusing, there are conjugate points that give rise to zeros instead of exclusively at Gaussian peaks at the locations of the periodic orbits.

  13. Statistical Properties of Extreme Solar Activity Intervals

    NASA Astrophysics Data System (ADS)

    Lioznova, A. V.; Blinov, A. V.

    2014-01-01

    A study of long-term solar variability reflected in indirect indices of past solar activity leads to stimulating results. We compare the statistics of intervals of very low and very high solar activity derived from two cosmogenic radionuclide records and look for consistency in their timing and physical interpretation. According to the applied criteria, the numbers of minima and of maxima are 61 and 68, respectively, from the 10Be record, and 42 and 46 from the 14C record. The difference between the enhanced and depressed states of solar activity becomes apparent in the difference in their statistical distributions. We find no correlation between the level or type (minimum or maximum) of an extremum and the level or type of the predecessor. The hypothesis of solar activity as a periodic process on the millennial time scale is not supported by the existing proxies. A new homogeneous series of 10Be measurements in polar ice covering the Holocene would be of great value for eliminating the existing discrepancy in the available solar activity reconstructions.

  14. On the statistical analysis of maximal magnitude

    NASA Astrophysics Data System (ADS)

    Holschneider, M.; Zöller, G.; Hainzl, S.

    2012-04-01

    We show how the maximum expected magnitude within a time horizon [0,T] may be estimated from earthquake catalog data within the context of truncated Gutenberg-Richter statistics. We present the results in a frequentist and in a Bayesian setting. Instead of deriving point estimations of this parameter and reporting its performance in terms of expectation value and variance, we focus on the calculation of confidence intervals based on an imposed level of confidence α. We present an estimate of the maximum magnitude within an observational time interval T in the future, given a complete earthquake catalog for a time period Tc in the past and optionally some paleoseismic events. We argue that from a statistical point of view the maximum magnitude in a time window is a reasonable parameter for probabilistic seismic hazard assessment, while the commonly used maximum possible magnitude for all times does almost certainly not allow the calculation of useful (i.e. non-trivial) confidence intervals. In the context of an unbounded GR law we show, that Jeffreys invariant prior distribtution yields normalizable posteriors. The predictive distribution based on this prior is explicitely computed.

  15. Statistics by Example, Finding Models.

    ERIC Educational Resources Information Center

    Mosteller, Frederick; And Others

    This booklet, part of a series of four which provide problems in probability and statistics for the secondary school level, is aimed at aiding the student in developing models as structure for data and in learning how to change models to fit real-life problems. Twelve different problem situations arising from biology, business, English, physical…

  16. Statistics by Example, Weighing Chances.

    ERIC Educational Resources Information Center

    Mosteller, Frederick; And Others

    Part of a series of four pamphlets providing problems in probability and statistics taken from real-life situations, this booklet develops probability methods through random numbers, simulations, and simple probability models, and presents the idea of scatter and residuals for analyzing complex data. The pamphlet was designed for a student having…

  17. Statistics by Example, Exploring Data.

    ERIC Educational Resources Information Center

    Mosteller, Frederick; And Others

    Part of a series of four pamphlets providing real-life problems in probability and statistics for the secondary school level, this booklet shows how to organize data in tables and graphs in order to get and to exhibit messages. Elementary probability concepts are also introduced. Fourteen different problem situations arising from biology,…

  18. Statistics Poster Challenge for Schools

    ERIC Educational Resources Information Center

    Payne, Brad; Freeman, Jenny; Stillman, Eleanor

    2013-01-01

    The analysis and interpretation of data are important life skills. A poster challenge for schoolchildren provides an innovative outlet for these skills and demonstrates their relevance to daily life. We discuss our Statistics Poster Challenge and the lessons we have learned.

  19. The Statistical Handbook on Technology.

    ERIC Educational Resources Information Center

    Berinstein, Paula

    This volume tells stories about the tools we use, but these narratives are told in numbers rather than in words. Organized by various aspects of society, each chapter uses tables and statistics to examine everything from budgets, costs, sales, trade, employment, patents, prices, usage, access and consumption. In each chapter, each major topic is…

  20. Undergraduate experiments on statistical optics

    NASA Astrophysics Data System (ADS)

    Scholz, Ruediger; Friege, Gunnar; Weber, Kim-Alessandro

    2016-09-01

    Since the pioneering experiments of Forrester et al (1955 Phys. Rev. 99 1691) and Hanbury Brown and Twiss (1956 Nature 177 27; Nature 178 1046), along with the introduction of the laser in the 1960s, the systematic analysis of random fluctuations of optical fields has developed to become an indispensible part of physical optics for gaining insight into features of the fields. In 1985 Joseph W Goodman prefaced his textbook on statistical optics with a strong commitment to the ‘tools of probability and statistics’ (Goodman 2000 Statistical Optics (New York: John Wiley & Sons Inc.)) in the education of advanced optics. Since then a wide range of novel undergraduate optical counting experiments and corresponding pedagogical approaches have been introduced to underpin the rapid growth of the interest in coherence and photon statistics. We propose low cost experimental steps that are a fair way off ‘real’ quantum optics, but that give deep insight into random optical fluctuation phenomena: (1) the introduction of statistical methods into undergraduate university optical lab work, and (2) the connection between the photoelectrical signal and the characteristics of the light source. We describe three experiments and theoretical approaches which may be used to pave the way for a well balanced growth of knowledge, providing students with an opportunity to enhance their abilities to adapt the ‘tools of probability and statistics’.

  1. Teaching Statistics through Learning Projects

    ERIC Educational Resources Information Center

    Moreira da Silva, Mauren Porciúncula; Pinto, Suzi Samá

    2014-01-01

    This paper aims to reflect on the teaching of statistics through student research, in the form of projects carried out by students on self-selected topics. The paper reports on a study carried out with two undergraduate classes using a methodology of teaching that we call "learning projects." Monitoring the development of the various…

  2. STATISTICAL PROCEDURES FOR CORROSION STUDIES

    EPA Science Inventory

    Many utilities will be conducting pipe loop and other experimental studies to optimize corrosion control under the Lead and Copper Rule. his paper presents a discussion of the background and justifications for the selection of different statistical techniques to evaluate experime...

  3. A Simple Statistical Thermodynamics Experiment

    ERIC Educational Resources Information Center

    LoPresto, Michael C.

    2010-01-01

    Comparing the predicted and actual rolls of combinations of both two and three dice can help to introduce many of the basic concepts of statistical thermodynamics, including multiplicity, probability, microstates, and macrostates, and demonstrate that entropy is indeed a measure of randomness, that disordered states (those of higher entropy) are…

  4. STATISTICS AND DATA ANALYSIS WORKSHOP

    EPA Science Inventory

    On Janauary 15 and 16, 2003, a workshop for Tribal water resources staff on Statistics and Data Analysis was held at the Indian Springs Lodge on the Forest County Potowatomi Reservation near Wabeno, WI. The workshop was co-sponsored by the EPA, Sokaogon Chippewa (Mole Lake) Comm...

  5. Tsallis statistics and neurodegenerative disorders

    NASA Astrophysics Data System (ADS)

    Iliopoulos, Aggelos C.; Tsolaki, Magdalini; Aifantis, Elias C.

    2016-08-01

    In this paper, we perform statistical analysis of time series deriving from four neurodegenerative disorders, namely epilepsy, amyotrophic lateral sclerosis (ALS), Parkinson's disease (PD), Huntington's disease (HD). The time series are concerned with electroencephalograms (EEGs) of healthy and epileptic states, as well as gait dynamics (in particular stride intervals) of the ALS, PD and HDs. We study data concerning one subject for each neurodegenerative disorder and one healthy control. The analysis is based on Tsallis non-extensive statistical mechanics and in particular on the estimation of Tsallis q-triplet, namely {qstat, qsen, qrel}. The deviation of Tsallis q-triplet from unity indicates non-Gaussian statistics and long-range dependencies for all time series considered. In addition, the results reveal the efficiency of Tsallis statistics in capturing differences in brain dynamics between healthy and epileptic states, as well as differences between ALS, PD, HDs from healthy control subjects. The results indicate that estimations of Tsallis q-indices could be used as possible biomarkers, along with others, for improving classification and prediction of epileptic seizures, as well as for studying the gait complex dynamics of various diseases providing new insights into severity, medications and fall risk, improving therapeutic interventions.

  6. Inverting an Introductory Statistics Classroom

    ERIC Educational Resources Information Center

    Kraut, Gertrud L.

    2015-01-01

    The inverted classroom allows more in-class time for inquiry-based learning and for working through more advanced problem-solving activities than does the traditional lecture class. The skills acquired in this learning environment offer benefits far beyond the statistics classroom. This paper discusses four ways that can make the inverted…

  7. The ENSEMBLES Statistical Downscaling Portal

    NASA Astrophysics Data System (ADS)

    Cofino, Antonio S.; San-Martín, Daniel; Gutiérrez, Jose M.

    2010-05-01

    The demand for high-resolution seasonal and ACC predictions is continuously increasing due to the multiple end-user applications in a variety of sectors (hydrology, agronomy, energy, etc.) which require regional meteorological inputs. To fill the gap between the coarse-resolution grids used by global weather models and the regional needs of applications, a number of statistical downscaling techniques have been proposed. Statistical downscaling is a complex multi-disciplinary problem which requires a cascade of different scientific tools to access and process different sources of data, from GCM outputs to local observations and to run complex statistical algorithms. Thus, an end-to-end approach is needed in order to link the outputs of the ensemble prediction systems to a range of impact applications. To accomplish this task in an interactive and user-friendly form, a Web portal has been developed within the European ENSEMBLES project, integrating the necessary tools and providing the appropriate technology for distributed data access and computing. In this form, users can obtain their downscaled data testing and validating different statistical methods (from the categories weather typing, regression or weather generators) in a transparent form, not worrying about the details of the downscaling techniques and the data formats and access.

  8. Statistical Methods for Evolutionary Trees

    PubMed Central

    Edwards, A. W. F.

    2009-01-01

    In 1963 and 1964, L. L. Cavalli-Sforza and A. W. F. Edwards introduced novel methods for computing evolutionary trees from genetical data, initially for human populations from blood-group gene frequencies. The most important development was their introduction of statistical methods of estimation applied to stochastic models of evolution. PMID:19797062

  9. China's Statistical System and Resources

    ERIC Educational Resources Information Center

    Xue, Susan

    2004-01-01

    As the People's Republic of China plays an increasingly important role in international politics and trade, countries with economic interests there find they need to know more about this nation. Access to primary information sources, including official statistics from China, however, is very limited, as little exploration has been done into this…

  10. Concept Maps in Introductory Statistics

    ERIC Educational Resources Information Center

    Witmer, Jeffrey A.

    2016-01-01

    Concept maps are tools for organizing thoughts on the main ideas in a course. I present an example of a concept map that was created through the work of students in an introductory class and discuss major topics in statistics and relationships among them.

  11. GPS: Geometry, Probability, and Statistics

    ERIC Educational Resources Information Center

    Field, Mike

    2012-01-01

    It might be said that for most occupations there is now less of a need for mathematics than there was say fifty years ago. But, the author argues, geometry, probability, and statistics constitute essential knowledge for everyone. Maybe not the geometry of Euclid, but certainly geometrical ways of thinking that might enable us to describe the world…

  12. American Youth: A Statistical Snapshot.

    ERIC Educational Resources Information Center

    Wetzel, James R.

    This report presents and analyzes statistical data on the status and condition of American youth, ages 16-24. A brief commentary on the problems of collecting data concerning Hispanic youth precedes the report's seven main sections, which deal with the following topics: population; marriage; childbearing and living arrangements; family income and…

  13. Synthetic aperture sonar image statistics

    NASA Astrophysics Data System (ADS)

    Johnson, Shawn F.

    Synthetic Aperture Sonar (SAS) systems are capable of producing photograph quality seafloor imagery using a lower frequency than other systems of comparable resolution. However, as with other high-resolution sonar systems, SAS imagery is often characterized by heavy-tailed amplitude distributions which may adversely affect target detection systems. The constant cross-range resolution with respect to range that results from the synthetic aperture formation process provides a unique opportunity to improve our understanding of system and environment interactions, which is essential for accurate performance prediction. This research focused on the impact of multipath contamination and the impact of resolution on image statistics, accomplished through analyses of data collected during at-sea experiments, analytical modeling, and development of numerical simulations. Multipath contamination was shown to have an appreciable impact on image statistics at ranges greater than the water depth and when the levels of the contributing multipath are within 10 dB of the direct path, reducing the image amplitude distribution tails while also degrading image clarity. Image statistics were shown to depend strongly upon both system resolution and orientation to seafloor features such as sand ripples. This work contributes to improving detection systems by aiding understanding of the influences of background (i.e. non-target) image statistics.

  14. Statistical comparison of dissolution profiles.

    PubMed

    Wang, Yifan; Snee, Ronald D; Keyvan, Golshid; Muzzio, Fernando J

    2016-05-01

    Statistical methods to assess similarity of dissolution profiles are introduced. Sixteen groups of dissolution profiles from a full factorial design were used to demonstrate implementation details. Variables in the design include drug strength, tablet stability time, and dissolution testing condition. The 16 groups were considered similar when compared using the similarity factor f2 (f2 > 50). However, multivariate ANOVA (MANOVA) repeated measures suggested statistical differences. A modified principal component analysis (PCA) was used to describe the dissolution curves in terms of level and shape. The advantage of the modified PCA approach is that the calculated shape principal components will not be confounded by level effect. Effect size test using omega-squared was also used for dissolution comparisons. Effects indicated by omega-squared are independent of sample size and are a necessary supplement to p value reported from the MANOVA table. Methods to compare multiple groups show that product strength and dissolution testing condition had significant effects on both level and shape. For pairwise analysis, a post-hoc analysis using Tukey's method categorized three similar groups, and was consistent with level-shape analysis. All these methods provide valuable information that is missed using f2 method alone to compare average profiles. The improved statistical analysis approach introduced here enables one to better ascertain both statistical significance and clinical relevance, supporting more objective regulatory decisions. PMID:26294289

  15. Statistical Prediction in Proprietary Rehabilitation.

    ERIC Educational Resources Information Center

    Johnson, Kurt L.; And Others

    1987-01-01

    Applied statistical methods to predict case expenditures for low back pain rehabilitation cases in proprietary rehabilitation. Extracted predictor variables from case records of 175 workers compensation claimants with some degree of permanent disability due to back injury. Performed several multiple regression analyses resulting in a formula that…

  16. Introductory Statistics and Fish Management.

    ERIC Educational Resources Information Center

    Jardine, Dick

    2002-01-01

    Describes how fisheries research and management data (available on a website) have been incorporated into an Introductory Statistics course. In addition to the motivation gained from seeing the practical relevance of the course, some students have participated in the data collection and analysis for the New Hampshire Fish and Game Department. (MM)

  17. Digest of Education Statistics, 1982.

    ERIC Educational Resources Information Center

    Grant, W. Vance; Eiden, Leo J.

    In 6 chapters, 180 tables, and 10 figures, this document provides large amounts of statistical data on most aspects of U.S. education, both public and private. The chapters cover (1) all levels of education, (2) elementary and secondary education, (3) two- and four-year colleges and universities, (4) adult and vocational education, (5) federal…

  18. Statistics of premixed flame cells

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    1991-01-01

    The statistics of random cellular patterns in premixed flames are analyzed. Agreement is found with a variety of topological relations previously found for other networks, namely, Lewis's law and Aboav's law. Despite the diverse underlying physics, flame cells are shown to share a broad class of geometric properties with other random networks-metal grains, soap foams, bioconvection, and Langmuir monolayers.

  19. Control Theory and Statistical Generalizations.

    ERIC Educational Resources Information Center

    Powers, William T.

    1990-01-01

    Contrasts modeling methods in control theory to the methods of statistical generalizations in empirical studies of human or animal behavior. Presents a computer simulation that predicts behavior based on variables (effort and rewards) determined by the invariable (desired reward). Argues that control theory methods better reflect relationships to…

  20. Understanding Statistics Using Computer Demonstrations

    ERIC Educational Resources Information Center

    Dunn, Peter K.

    2004-01-01

    This paper discusses programs that clarify some statistical ideas often discussed yet poorly understood by students. The programs adopt the approach of demonstrating what is happening, rather than using the computer to do the work for the students (and hide the understanding). The programs demonstrate normal probability plots, overfitting of…

  1. Tools for Basic Statistical Analysis

    NASA Technical Reports Server (NTRS)

    Luz, Paul L.

    2005-01-01

    Statistical Analysis Toolset is a collection of eight Microsoft Excel spreadsheet programs, each of which performs calculations pertaining to an aspect of statistical analysis. These programs present input and output data in user-friendly, menu-driven formats, with automatic execution. The following types of calculations are performed: Descriptive statistics are computed for a set of data x(i) (i = 1, 2, 3 . . . ) entered by the user. Normal Distribution Estimates will calculate the statistical value that corresponds to cumulative probability values, given a sample mean and standard deviation of the normal distribution. Normal Distribution from two Data Points will extend and generate a cumulative normal distribution for the user, given two data points and their associated probability values. Two programs perform two-way analysis of variance (ANOVA) with no replication or generalized ANOVA for two factors with four levels and three repetitions. Linear Regression-ANOVA will curvefit data to the linear equation y=f(x) and will do an ANOVA to check its significance.

  2. Basic HIV/AIDS Statistics

    MedlinePlus

    ... Abroad Treatment Basic Statistics Get Tested Find an HIV testing site near you. Enter ZIP code or city Follow HIV/AIDS CDC HIV CDC HIV/AIDS See RSS | ... Collapse All How many people are diagnosed with HIV each year in the United States? In 2014, ...

  3. Statistical description of tectonic motions

    NASA Technical Reports Server (NTRS)

    Agnew, Duncan Carr

    1993-01-01

    This report summarizes investigations regarding tectonic motions. The topics discussed include statistics of crustal deformation, Earth rotation studies, using multitaper spectrum analysis techniques applied to both space-geodetic data and conventional astrometric estimates of the Earth's polar motion, and the development, design, and installation of high-stability geodetic monuments for use with the global positioning system.

  4. Statistics of premixed flame cells

    SciTech Connect

    Noever, D.A. )

    1991-07-15

    The statistics of random cellular patterns in premixed flames are analyzed. Agreement is found with a variety of topological relations previously found for other networks, namely, Lewis's law and Aboav's law. Despite the diverse underlying physics, flame cells are shown to share a broad class of geometric properties with other random networks---metal grains, soap foams, bioconvection, and Langmuir monolayers.

  5. American Youth: A Statistical Snapshot.

    ERIC Educational Resources Information Center

    Wetzel, James R.

    This document presents a statistics snapshot of young people, aged 15 to 24 years. It provides a broad overview of trends documenting the direction of changes in social behavior and economic circumstances. The projected decline in the total number of youth from 43 million in 1980 to 35 million in 1995 will affect marriage and childbearing…

  6. Instructional Theory for Teaching Statistics.

    ERIC Educational Resources Information Center

    Atwood, Jan R.; Dinham, Sarah M.

    Metatheoretical analysis of Ausubel's Theory of Meaningful Verbal Learning and Gagne's Theory of Instruction using the Dickoff and James paradigm produced two instructional systems for basic statistics. The systems were tested with a pretest-posttest control group design utilizing students enrolled in an introductory-level graduate statistics…

  7. Measuring Skewness: A Forgotten Statistic?

    ERIC Educational Resources Information Center

    Doane, David P.; Seward, Lori E.

    2011-01-01

    This paper discusses common approaches to presenting the topic of skewness in the classroom, and explains why students need to know how to measure it. Two skewness statistics are examined: the Fisher-Pearson standardized third moment coefficient, and the Pearson 2 coefficient that compares the mean and median. The former is reported in statistical…

  8. ARL Statistics 2007-2008

    ERIC Educational Resources Information Center

    Kyrillidou, Martha, Comp.; Bland, Les, Comp.

    2009-01-01

    "ARL Statistics 2007-2008" is the latest in a series of annual publications that describe collections, staffing, expenditures, and service activities for the 123 members of the Association of Research Libraries (ARL). Of these, 113 are university libraries; the remaining 10 are public, governmental, and nonprofit research libraries. Data reported…

  9. Fit Indices Versus Test Statistics

    ERIC Educational Resources Information Center

    Yuan, Ke-Hai

    2005-01-01

    Model evaluation is one of the most important aspects of structural equation modeling (SEM). Many model fit indices have been developed. It is not an exaggeration to say that nearly every publication using the SEM methodology has reported at least one fit index. Most fit indices are defined through test statistics. Studies and interpretation of…

  10. Diffusion in periodic, correlated random forcing landscapes

    NASA Astrophysics Data System (ADS)

    Dean, David S.; Gupta, Shamik; Oshanin, Gleb; Rosso, Alberto; Schehr, Grégory

    2014-09-01

    We study the dynamics of a Brownian particle in a strongly correlated quenched random potential defined as a periodically-extended (with period L) finite trajectory of a fractional Brownian motion with arbitrary Hurst exponent H\\in (0,1). While the periodicity ensures that the ultimate long-time behavior is diffusive, the generalized Sinai potential considered here leads to a strong logarithmic confinement of particle trajectories at intermediate times. These two competing trends lead to dynamical frustration and result in a rich statistical behavior of the diffusion coefficient D L : although one has the typical value D_{L}^{typ}\\sim exp (-\\beta {{L}^{H}}), we show via an exact analytical approach that the positive moments (k\\gt 0) scale like \\langle D_{L}^{k}\\rangle \\sim exp [-c^{\\prime} {{(k\\beta {{L}^{H}})}^{1/(1+H)}}], and the negative ones as \\langle D_{L}^{-k}\\rangle \\sim exp (a^{\\prime} {{(k\\beta {{L}^{H}})}^{2}}), c^{\\prime} and a^{\\prime} being numerical constants and β the inverse temperature. These results demonstrate that D L is strongly non-self-averaging. We further show that the probability distribution of D L has a log-normal left tail and a highly singular, one-sided log-stable right tail reminiscent of a Lifshitz singularity.

  11. Periodic cometary showers: Real or imaginary?

    NASA Technical Reports Server (NTRS)

    Grieve, R. A. F.; Sharpton, V. L.; Goodacre, A. K.; Garvin, J. B.

    1985-01-01

    Since the initial reports in 1980, a considerable body of chemical and physical evidence has been accumulated to indicate that a major impact event occurred on earth 65 million years ago. The effects of this event were global in extent and have been suggested as the cause of the sudden demise or mass extinction of a large percentage of life, including the dinosaurs, at the end of the geologic time period known as the Cretaceous. Recent statistical analyses of extinctions in the marine faunal record for the last 250 million years have suggested that mass extinctions may occur with a periodicity of every 26 to 30 million years. Following these results, other workers have attempted to demonstrate that these extinction events, like that at the end of the Cretaceous, are temporally correlated with large impact events. A recent scenario suggests that they are the result of periodic showers of comets produced by either the passage of the solar system through the galactic plane or by perturbations of the cometary cloud in the outer solar system by a, as yet unseen, solar companion. This hypothesized solar companion has been given the name Nemesis.

  12. Dynamical system theory of periodically collapsing bubbles

    NASA Astrophysics Data System (ADS)

    Yukalov, V. I.; Yukalova, E. P.; Sornette, D.

    2015-07-01

    We propose a reduced form set of two coupled continuous time equations linking the price of a representative asset and the price of a bond, the later quantifying the cost of borrowing. The feedbacks between asset prices and bonds are mediated by the dependence of their "fundamental values" on past asset prices and bond themselves. The obtained nonlinear self-referencing price dynamics can induce, in a completely objective deterministic way, the appearance of periodically exploding bubbles ending in crashes. Technically, the periodically explosive bubbles arise due to the proximity of two types of bifurcations as a function of the two key control parameters b and g, which represent, respectively, the sensitivity of the fundamental asset price on past asset and bond prices and of the fundamental bond price on past asset prices. One is a Hopf bifurcation, when a stable focus transforms into an unstable focus and a limit cycle appears. The other is a rather unusual bifurcation, when a stable node and a saddle merge together and disappear, while an unstable focus survives and a limit cycle develops. The lines, where the periodic bubbles arise, are analogous to the critical lines of phase transitions in statistical physics. The amplitude of bubbles and waiting times between them respectively diverge with the critical exponents γ = 1 and ν = 1/2, as the critical lines are approached.

  13. Oral contraceptives in the immediate postpartum period.

    PubMed

    Hume, A L; Hijab, J C

    1991-04-01

    Although there is a critical need for effective contraception in the immediate postpartum period for women who are not breastfeeding, this need must be balanced against the inherent risks. The most effective form of contraceptive protection--oral contraceptives (OCs)--can present an increased risk of thromboembolism in the period after delivery. The thrombotic changes associated with pregnancy, and the statistics and vascular damage following a delivery, can combine to create greater potential for thromboembolism after delivery than during pregnancy. Reported here is the case of a 21-year-old woman who, 4 weeks postpartum, developed pain and swelling in the right lower calf and mottled discoloration extending from the proximal thigh to the toes. A diagnosis of deep venous thrombosis was made and heparin was administered. In the hospital, the patient experienced pleuritic chest pain and diaphoresis. A ventilation-perfusion scan indicated a pulmonary embolism. 1 week after delivery, the patient had initiated use of Triphasil. Although this woman had other risk factors (obesity, light cigarette smoking, and a sedentary life-style), OC use in the immediate postpartum period may have been the final factor precipitating the thromboembolic event. It is recommended that OC use should be delayed until at least 2 weeks postpartum in women without other risk factors for thromboembolism and until 4-6 weeks postpartum in those with such factors. PMID:2010744

  14. From Periodic Properties to a Periodic Table Arrangement

    ERIC Educational Resources Information Center

    Besalú, Emili

    2013-01-01

    A periodic table is constructed from the consideration of periodic properties and the application of the principal components analysis technique. This procedure is useful for objects classification and data reduction and has been used in the field of chemistry for many applications, such as lanthanides, molecules, or conformers classification.…

  15. Scaling limits of periodic monopoles

    NASA Astrophysics Data System (ADS)

    Maldonado, Rafael

    2015-01-01

    The purpose of this note is to explore the structure of singly periodic monopoles for different values of the size to period ratio. The transition between a chain of small monopoles and the approximately two dimensional chain of large monopoles takes us through a region with an unintuitive dependence on the periodic direction. The focus is mainly on the smooth SU(2) monopole of charge 2.

  16. FEDERAL JUSTICE STATISTICS RESOURCE CENTER (FJSRC)

    EPA Science Inventory

    The Bureau of Justice Statistics (BJS), through its Federal Justice Statistics Program (FJSP), compiles comprehensive information describing suspects and defendants processed in the Federal criminal justice system. The goal of FJSP is to provide uniform case processing statistics...

  17. Ideas for Effective Communication of Statistical Results

    DOE PAGESBeta

    Anderson-Cook, Christine M.

    2015-03-01

    Effective presentation of statistical results to those with less statistical training, including managers and decision-makers requires planning, anticipation and thoughtful delivery. Here are several recommendations for effectively presenting statistical results.

  18. Changing Periods of ST Puppis

    NASA Astrophysics Data System (ADS)

    Walker, S.; Butterworth, N.; Pearce, A.

    2015-12-01

    ST Puppis is a reasonably bright W Virginis variable star, a Type 2 Cepheid with a record of substantial and erratic period changes—21 during the interval 1900 to 1985 with a range of magnitude from 17.4 to 19.2. It was observed as part of Variable Stars South's Cepheid project by Butterworth in 2014 and 2015 using DSLR photometry in BGR passbands and visually by Pearce in 2015. The known period changes are shown graphically and doubtful ones examined and discarded if necessary. With its period and amplitude with a frequently changing period it is a suitable and worthwhile object for visual observing.

  19. Societal Statistics by virtue of the Statistical Drake Equation

    NASA Astrophysics Data System (ADS)

    Maccone, Claudio

    2012-09-01

    The Drake equation, first proposed by Frank D. Drake in 1961, is the foundational equation of SETI. It yields an estimate of the number N of extraterrestrial communicating civilizations in the Galaxy given by the product N=Ns×fp×ne×fl×fi×fc×fL, where: Ns is the number of stars in the Milky Way Galaxy; fp is the fraction of stars that have planetary systems; ne is the number of planets in a given system that are ecologically suitable for life; fl is the fraction of otherwise suitable planets on which life actually arises; fi is the fraction of inhabited planets on which an intelligent form of life evolves; fc is the fraction of planets inhabited by intelligent beings on which a communicative technical civilization develops; and fL is the fraction of planetary lifetime graced by a technical civilization. The first three terms may be called "the astrophysical terms" in the Drake equation since their numerical value is provided by astrophysical considerations. The fourth term, fl, may be called "the origin-of-life term" and entails biology. The last three terms may be called "the societal terms" inasmuch as their respective numerical values are provided by anthropology, telecommunication science and "futuristic science", respectively. In this paper, we seek to provide a statistical estimate of the three societal terms in the Drake equation basing our calculations on the Statistical Drake Equation first proposed by this author at the 2008 IAC. In that paper the author extended the simple 7-factor product so as to embody Statistics. He proved that, no matter which probability distribution may be assigned to each factor, if the number of factors tends to infinity, then the random variable N follows the lognormal distribution (central limit theorem of Statistics). This author also proved at the 2009 IAC that the Dole (1964) [7] equation, yielding the number of Habitable Planets for Man in the Galaxy, has the same mathematical structure as the Drake equation. So the

  20. A statistical profile of groundfall injuries

    SciTech Connect

    Randolph, R.F. )

    1993-01-01

    This paper contains statistical analyses of groundfall injuries in the US underground coal mining industry. The analyses are based on data from Mine Safety and Health Administration (MSHA) records of mining accidents. Most of the analyses focus on the most recent 5-year period (1986-90). During this period, groundfalls accounted for 48% of the fatalities and 8% of the lost-time injuries. The total cost of these injuries, based on the US Bureau of Mine's accident cost indicator model (ACIM), was $125 million. Higher rates of groundfall injuries were found for smaller mines and lower seam heights, although these factors are somewhat confounded. As other authors have already recognized, Tennessee, Kentucky, and Virginia had the highest groundfall fatality injury rates. The picture for lost-time injuries is somewhat different, however. Colorado and Illinois were found to have the highest lost-time groundfall injury rates. Differences between States correlated somewhat with differences in mine sizes and seam heights within each State. a comparison of injury experience with a 1986 study of demographics showed that job categories at the highest risk of fatal and lost-time groundfall injury were roof bolter-rock drillers, continuous mining machine operators and helpers, and working managers. These occupations typically perform work near the face and are most likely to be exposed to groundfall hazards.

  1. Quasi-periodicity in relative quasi-periodic tori

    NASA Astrophysics Data System (ADS)

    Fassò, Francesco; García-Naranjo, Luis C.; Giacobbe, Andrea

    2015-10-01

    At variance from the cases of relative equilibria and relative periodic orbits of dynamical systems with symmetry, the dynamics in relative quasi-periodic tori (namely, subsets of the phase space that project to an invariant torus of the reduced system on which the flow is quasi-periodic) is not yet completely understood. Even in the simplest situation of a free action of a compact and abelian connected group, the dynamics in a relative quasi-periodic torus is not necessarily quasi-periodic. It is known that quasi-periodicity of the unreduced dynamics is related to the reducibility of the reconstruction equation, and sufficient conditions for it are virtually known only in a perturbation context. We provide a different, though equivalent, approach to this subject, based on the hypothesis of the existence of commuting, group-invariant lifts of a set of generators of the reduced torus. Under this hypothesis, which is shown to be equivalent to the reducibility of the reconstruction equation, we give a complete description of the structure of the relative quasi-periodic torus, which is a principal torus bundle whose fibers are tori of a dimension which exceeds that of the reduced torus by at most the rank of the group. The construction can always be done in such a way that these tori have minimal dimension and carry ergodic flow.

  2. Streamflow statistics for selected streams in North Dakota, Minnesota, Manitoba, and Saskatchewan

    USGS Publications Warehouse

    Williams-Sether, Tara

    2012-01-01

    Statistical summaries of streamflow data for the periods of record through water year 2009 for selected active and discontinued U.S. Geological Survey streamflow-gaging stations in North Dakota, Minnesota, Manitoba, and Saskatchewan were compiled. The summaries for each streamflow-gaging station include a brief station description, a graph of the annual peak and annual mean discharge for the period of record, statistics of monthly and annual mean discharges, monthly and annual flow durations, probability of occurrence of annual high discharges, annual peak discharge and corresponding gage height for the period of record, and monthly and annual mean discharges for the period of record.

  3. Current North American Indian Periodicals.

    ERIC Educational Resources Information Center

    Blew, Carol Van Antwerp Holliday; And Others

    Approximately 150 newsletters, newspapers, and other periodicals are cited in this bibliography of current sources of information about or directed toward North American Indians. One-sentence descriptions of content, ordering information, and frequency of publication are provided. The majority of the periodicals cited emphasize current events of…

  4. 75 FR 39200 - Periodic Reporting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-08

    ... Counsel, at stephen.sharfman@prc.gov or 202-789-6820. SUPPLEMENTARY INFORMATION: Regulatory History, 75 FR... a proposed change in certain analytical methods used in periodic reporting. This action responds to... rulemaking proceeding to consider a change in the analytical methods approved for use in periodic...

  5. 76 FR 296 - Periodic Reporting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-01-04

    ... consider a proposed change in certain analytical methods used in periodic reporting. The proposed change... rulemaking proceeding to consider changes in the analytical methods approved for use in periodic reporting.\\1... Requesting Initiation of a Proceeding to Consider Proposed Changes in Analytic Principles (Proposals...

  6. Schuler Period in LEO Satellites

    NASA Technical Reports Server (NTRS)

    Carpenter, Russell J.; Bar-Itzhack, Itzhack Y.

    2004-01-01

    This paper generalizes and extends the concept of the Schuler oscillation that occurs in the theory of inertial navigation systems, allowing one to see how the Schuler phenomenon affects inertial navigation systems operating in space. We show why a low earth orbit satellite's orbital period is identical to the period of the Schuler pendulum, which is the period of the errors for terrestrial inertial navigation systems. We also show that the generalized form of the Schuler oscillation takes the same form as the Hill-Clohessy-Wiltshire equations for satellite relative motion and that the period of the out-of-plane motion in neighboring satellite relative trajectories is the same as the Schuler period. Finally, we describe how INS gyro drift manifests itself in different coordinate systems for the orbital case. These results may assist orbital flight dynamics and attitude control systems engineers in the design and analysis of INS-equipped spacecraft

  7. Rationalization of Comet Halley's periods

    NASA Astrophysics Data System (ADS)

    Belton, M. J. S.

    1990-07-01

    The sense of long axis orientation of Comet Halley during the Vega 1 encounter must be reversed from that deduced by Sagdeev et al. (1986) in order to harmonize the comet nucleus' Vega/Giotto-observed orientations with periodicities extracted from time-series brightness data. It is also demonstrated that Vega/Giotto observations can be satisfied by either a 2.2- or 3.7-day long-axis free precession period. A novel Fourier algorithm is used to reanalyze five independent data sets; strong evidence is adduced for periods harmonically related to a 7.4-day period. The preferred candidate models for Halley's nuclear rotation are characterized by a long-axis precession period of 3.7 days.

  8. LYRA Mid-Term Periodicities

    NASA Astrophysics Data System (ADS)

    Wauters, L.; Dominique, M.; Dammasch, I. E.

    2016-08-01

    The spectra of the PROBA2/LYRA data, similarly to every other solar time series, show predominant periodicities that can be of solar or instrumental origin. In this article, we compare the main periodicities characterizing the LYRA spectrum to those found in the sunspot number, in the 10.7 cm flux, in an X-ray flare index, and in the sunspot area evolution. We focused on the 2010 to 2014 time range, for which the LYRA data are available, although we also briefly address the evolution of the main periodicities in the longer range. The mid-term periodicities at {˜} 28, {˜} 44, {˜} 54, {˜} 59, {˜} 100, {˜} 110, and {˜} 150 days appear as highly significant in several analyzed datasets. The consistency of distinct periodicities between datasets provides characteristics for the global Sun. This consistency also strengthens the reliability of LYRA data.

  9. Statistical analysis of barefoot impressions.

    PubMed

    Kennedy, Robert B; Pressman, Irwin S; Chen, Sanping; Petersen, Peter H; Pressman, Ari E

    2003-01-01

    Comparison of the shapes of barefoot impressions from an individual with footprints or shoes linked to a crime may be useful as a means of including or excluding that individual as possibly being at the scene of a crime. The question of the distinguishability of a person's barefoot print arises frequently. This study indicates that measurements taken from the outlines of inked footprint impressions show a great degree of variability between donors and a great degree of similarity for multiple impressions taken from the same donor. The normality of the set of measurements on footprint outlines that we have selected for this study is confirmed. A statistical justification for the use of the product rule on individual statistical precisions is developed. PMID:12570199

  10. Statistical phenomena in particle beams

    SciTech Connect

    Bisognano, J.J.

    1984-09-01

    Particle beams are subject to a variety of apparently distinct statistical phenomena such as intrabeam scattering, stochastic cooling, electron cooling, coherent instabilities, and radiofrequency noise diffusion. In fact, both the physics and mathematical description of these mechanisms are quite similar, with the notion of correlation as a powerful unifying principle. In this presentation we will attempt to provide both a physical and a mathematical basis for understanding the wide range of statistical phenomena that have been discussed. In the course of this study the tools of the trade will be introduced, e.g., the Vlasov and Fokker-Planck equations, noise theory, correlation functions, and beam transfer functions. Although a major concern will be to provide equations for analyzing machine design, the primary goal is to introduce a basic set of physical concepts having a very broad range of applicability.

  11. Statistical learning and selective inference

    PubMed Central

    Taylor, Jonathan; Tibshirani, Robert J.

    2015-01-01

    We describe the problem of “selective inference.” This addresses the following challenge: Having mined a set of data to find potential associations, how do we properly assess the strength of these associations? The fact that we have “cherry-picked”—searched for the strongest associations—means that we must set a higher bar for declaring significant the associations that we see. This challenge becomes more important in the era of big data and complex statistical modeling. The cherry tree (dataset) can be very large and the tools for cherry picking (statistical learning methods) are now very sophisticated. We describe some recent new developments in selective inference and illustrate their use in forward stepwise regression, the lasso, and principal components analysis. PMID:26100887

  12. Parallel contingency statistics with Titan.

    SciTech Connect

    Thompson, David C.; Pebay, Philippe Pierre

    2009-09-01

    This report summarizes existing statistical engines in VTK/Titan and presents the recently parallelized contingency statistics engine. It is a sequel to [PT08] and [BPRT09] which studied the parallel descriptive, correlative, multi-correlative, and principal component analysis engines. The ease of use of this new parallel engines is illustrated by the means of C++ code snippets. Furthermore, this report justifies the design of these engines with parallel scalability in mind; however, the very nature of contingency tables prevent this new engine from exhibiting optimal parallel speed-up as the aforementioned engines do. This report therefore discusses the design trade-offs we made and study performance with up to 200 processors.

  13. Fundamental and statistical characteristics of experimental geyser

    NASA Astrophysics Data System (ADS)

    Maeda, K.; Toramaru, A.

    2009-12-01

    The geyser experiment as an interesting analogue system is useful in order to understand not only the mechanism of natural geyser but also the behavior of volcanoes such as eruption styles, erupted mass, reposed times and so on. We carried out geyser experiments using a simple experimental setup consisting of a heater (hotplate), flask, glass tubes, and water tank to reproduce the periodicity of natural geyser. For convenience, we fist make definition of eruption styles and of key variables;“jet”is an event that water vigorously spouts from the vent,“outflow”is an event that water flows from the vent without splash,“period”is the time interval between onsets of sequential eruptions, “duration”is the time lasting eruptions, and“interval”is the time from the end of eruption to the onset of next one. We automatically (or manually for some cases) measured the mass of erupted water for each eruption and the period by using the electronic balance connected to P.C. with varying experimental parameters; the initial water level (60, 65, 70 cm; total glass tube length is 84 cm), the insertion (the length of supplying tube inserted into the flask; 0, 1, 2, 3, 4 cm) and temperature of the hot plate (280, 340, 395 degrees Celsius). From experiments, we obtained following results; (a) a condition whether jet can occur or not depends on the initial water level and insertion, (b) there is a positive correlation between periods and the mass of water erupted by preceding eruption (i.e., time predictable system), (c) there is a negative correlation between the period and the temperature of hot plate, (d) the relation between elapsed time and accumulated mass of erupted water is roughly linear. In order to understand the cause of result (b), we examined a simple model on the basis of mass and energy conservations with some assumptions. As the result, the period predicted by the model is successfully consistent with measured ones at the first order. Fluctuative

  14. Performance of statistical energy analysis

    NASA Technical Reports Server (NTRS)

    Davis, R. F.; Hines, D. E.

    1973-01-01

    Statistical energy analysis (SEA) methods have been developed for high frequency modal analyses on random vibration environments. These SEA methods are evaluated by comparing analytical predictions to test results. Simple test methods are developed for establishing SEA parameter values. Techniques are presented, based on the comparison of the predictions with test values, for estimating SEA accuracy as a function of frequency for a general structure.

  15. Statistical templates for visual search.

    PubMed

    Ackermann, John F; Landy, Michael S

    2014-01-01

    How do we find a target embedded in a scene? Within the framework of signal detection theory, this task is carried out by comparing each region of the scene with a "template," i.e., an internal representation of the search target. Here we ask what form this representation takes when the search target is a complex image with uncertain orientation. We examine three possible representations. The first is the matched filter. Such a representation cannot account for the ease with which humans can find a complex search target that is rotated relative to the template. A second representation attempts to deal with this by estimating the relative orientation of target and match and rotating the intensity-based template. No intensity-based template, however, can account for the ability to easily locate targets that are defined categorically and not in terms of a specific arrangement of pixels. Thus, we define a third template that represents the target in terms of image statistics rather than pixel intensities. Subjects performed a two-alternative, forced-choice search task in which they had to localize an image that matched a previously viewed target. Target images were texture patches. In one condition, match images were the same image as the target and distractors were a different image of the same textured material. In the second condition, the match image was of the same texture as the target (but different pixels) and the distractor was an image of a different texture. Match and distractor stimuli were randomly rotated relative to the target. We compared human performance to pixel-based, pixel-based with rotation, and statistic-based search models. The statistic-based search model was most successful at matching human performance. We conclude that humans use summary statistics to search for complex visual targets. PMID:24627458

  16. The statistics of vacuum geometry

    NASA Astrophysics Data System (ADS)

    Duncan, Melissa; Gu, Wei; He, Yang-Hui; Zhou, Da

    2014-06-01

    We investigate the vacuum moduli space of supersymmetric gauge theories en masse by probing the space of such vacua from a statistical standpoint. Using quiver gauge theories with = 1 supersymmetry as a testing ground, we sample over a large number of vacua as algebraic varieties, computing explicitly their dimension, degree and Hilbert series. We study the distribution of these geometrical quantities, and also address the question of how likely it is for the moduli space to be Calabi-Yau.

  17. On Astronomical Records of Dangun Chosun Period

    NASA Astrophysics Data System (ADS)

    La, Daile; Park, Changbom

    1993-10-01

    Events of eclipses as well as other major astronomical events observable in the eastern sector of Asian continent are computed and checked with astronomical records of antiquity. Particular attention was given to two types of the events recorded in remaining records of Dangun Chosun Period (DCP): (1) concentration of major planets near the constellation of Nu-Sung (Beta Aries) and (2) a large ebb-tide. We find them most likely to have occurred in real time. i.e., when the positions of the sun, moon, and planets happen to be aligned in the most appropriate position. For solar eclipses data, however, we find among 10 solar eclipse events recorded, only 6 of them are correct up to months, implying its statistical significance is no less insignificant. We therefore conclude that the remaining history books of DCP indeed contains important astronomical records, thereby the real antiquity of the records of DCP cannot be disproved.

  18. Statistically significant relational data mining :

    SciTech Connect

    Berry, Jonathan W.; Leung, Vitus Joseph; Phillips, Cynthia Ann; Pinar, Ali; Robinson, David Gerald; Berger-Wolf, Tanya; Bhowmick, Sanjukta; Casleton, Emily; Kaiser, Mark; Nordman, Daniel J.; Wilson, Alyson G.

    2014-02-01

    This report summarizes the work performed under the project (3z(BStatitically significant relational data mining.(3y (BThe goal of the project was to add more statistical rigor to the fairly ad hoc area of data mining on graphs. Our goal was to develop better algorithms and better ways to evaluate algorithm quality. We concetrated on algorithms for community detection, approximate pattern matching, and graph similarity measures. Approximate pattern matching involves finding an instance of a relatively small pattern, expressed with tolerance, in a large graph of data observed with uncertainty. This report gathers the abstracts and references for the eight refereed publications that have appeared as part of this work. We then archive three pieces of research that have not yet been published. The first is theoretical and experimental evidence that a popular statistical measure for comparison of community assignments favors over-resolved communities over approximations to a ground truth. The second are statistically motivated methods for measuring the quality of an approximate match of a small pattern in a large graph. The third is a new probabilistic random graph model. Statisticians favor these models for graph analysis. The new local structure graph model overcomes some of the issues with popular models such as exponential random graph models and latent variable models.

  19. Environmental statistics and optimal regulation

    NASA Astrophysics Data System (ADS)

    Sivak, David; Thomson, Matt

    2015-03-01

    The precision with which an organism can detect its environment, and the timescale for and statistics of environmental change, will affect the suitability of different strategies for regulating protein levels in response to environmental inputs. We propose a general framework--here applied to the enzymatic regulation of metabolism in response to changing nutrient concentrations--to predict the optimal regulatory strategy given the statistics of fluctuations in the environment and measurement apparatus, and the costs associated with enzyme production. We find: (i) relative convexity of enzyme expression cost and benefit influences the fitness of thresholding or graded responses; (ii) intermediate levels of measurement uncertainty call for a sophisticated Bayesian decision rule; and (iii) in dynamic contexts, intermediate levels of uncertainty call for retaining memory of the past. Statistical properties of the environment, such as variability and correlation times, set optimal biochemical parameters, such as thresholds and decay rates in signaling pathways. Our framework provides a theoretical basis for interpreting molecular signal processing algorithms and a classification scheme that organizes known regulatory strategies and may help conceptualize heretofore unknown ones.

  20. Statistical properties of DNA sequences

    NASA Technical Reports Server (NTRS)

    Peng, C. K.; Buldyrev, S. V.; Goldberger, A. L.; Havlin, S.; Mantegna, R. N.; Simons, M.; Stanley, H. E.

    1995-01-01

    We review evidence supporting the idea that the DNA sequence in genes containing non-coding regions is correlated, and that the correlation is remarkably long range--indeed, nucleotides thousands of base pairs distant are correlated. We do not find such a long-range correlation in the coding regions of the gene. We resolve the problem of the "non-stationarity" feature of the sequence of base pairs by applying a new algorithm called detrended fluctuation analysis (DFA). We address the claim of Voss that there is no difference in the statistical properties of coding and non-coding regions of DNA by systematically applying the DFA algorithm, as well as standard FFT analysis, to every DNA sequence (33301 coding and 29453 non-coding) in the entire GenBank database. Finally, we describe briefly some recent work showing that the non-coding sequences have certain statistical features in common with natural and artificial languages. Specifically, we adapt to DNA the Zipf approach to analyzing linguistic texts. These statistical properties of non-coding sequences support the possibility that non-coding regions of DNA may carry biological information.

  1. The natural statistics of blur

    PubMed Central

    Sprague, William W.; Cooper, Emily A.; Reissier, Sylvain; Yellapragada, Baladitya; Banks, Martin S.

    2016-01-01

    Blur from defocus can be both useful and detrimental for visual perception: It can be useful as a source of depth information and detrimental because it degrades image quality. We examined these aspects of blur by measuring the natural statistics of defocus blur across the visual field. Participants wore an eye-and-scene tracker that measured gaze direction, pupil diameter, and scene distances as they performed everyday tasks. We found that blur magnitude increases with increasing eccentricity. There is a vertical gradient in the distances that generate defocus blur: Blur below the fovea is generally due to scene points nearer than fixation; blur above the fovea is mostly due to points farther than fixation. There is no systematic horizontal gradient. Large blurs are generally caused by points farther rather than nearer than fixation. Consistent with the statistics, participants in a perceptual experiment perceived vertical blur gradients as slanted top-back whereas horizontal gradients were perceived equally as left-back and right-back. The tendency for people to see sharp as near and blurred as far is also consistent with the observed statistics. We calculated how many observations will be perceived as unsharp and found that perceptible blur is rare. Finally, we found that eye shape in ground-dwelling animals conforms to that required to put likely distances in best focus. PMID:27580043

  2. Statistical mechanics of economics I

    NASA Astrophysics Data System (ADS)

    Kusmartsev, F. V.

    2011-02-01

    We show that statistical mechanics is useful in the description of financial crisis and economics. Taking a large amount of instant snapshots of a market over an interval of time we construct their ensembles and study their statistical interference. This results in a probability description of the market and gives capital, money, income, wealth and debt distributions, which in the most cases takes the form of the Bose-Einstein distribution. In addition, statistical mechanics provides the main market equations and laws which govern the correlations between the amount of money, debt, product, prices and number of retailers. We applied the found relations to a study of the evolution of the economics in USA between the years 1996 to 2008 and observe that over that time the income of a major population is well described by the Bose-Einstein distribution which parameters are different for each year. Each financial crisis corresponds to a peak in the absolute activity coefficient. The analysis correctly indicates the past crises and predicts the future one.

  3. Knot theory and statistical mechanics

    SciTech Connect

    Jones, V.F.R. )

    1990-11-01

    Certain algebraic relations used to solve models in statistical mechanics were key to describing a mathematical property of knots known as a polynomial invariant. This connection, tenuous at first, has since developed into a significant flow of ideas. The appearance of such common ground is not atypical of recent developments in mathematics and physics--ideas from different fields interact and produce unexpected results. Indeed, the discovery of the connection between knots and statistical mechanics passed through a theory intimately related to the mathematical structure of quantum physics. This theory, called von Neumann algebras, is distinguished by the idea of continuous dimensionality. Spaces typically have dimensions that are natural numbers, such as 2, 3 or 11, but in von Neumann algebras dimensions such as 2 or {pi} are equally possible. This possibility for continuous dimension played a key role in joining knot theory and statistical mechanics. In another direction, the knot invariants were soon found to occur in quantum field theory. Indeed, Edward Witten of the Institute for Advanced Study in Princeton, N.J., has shown that topological quantum field theory provides a natural way of expressing the new ideas about knots. This advance, in turn, has allowed a beautiful generalization about the invariants of knots in more complicated three-dimensional spaces known as three-manifolds, in which space itself may contain holes and loops.

  4. Statistical mechanics of complex networks

    NASA Astrophysics Data System (ADS)

    Waclaw, B.

    2007-04-01

    The science of complex networks is a new interdisciplinary branch of science which has arisen recently on the interface of physics, biology, social and computer sciences, and others. Its main goal is to discover general laws governing the creation and growth as well as processes taking place on networks, like e.g. the Internet, transportation or neural networks. It turned out that most real-world networks cannot be simply reduced to a compound of some individual components. Fortunately, the statistical mechanics, being one of pillars of modern physics, provides us with a very powerful set of tools and methods for describing and understanding these systems. In this thesis, we would like to present a consistent approach to complex networks based on statistical mechanics, with the central role played by the concept of statistical ensemble of networks. We show how to construct such a theory and present some practical problems where it can be applied. Among them, we pay attention to the problem of finite-size corrections and the dynamics of a simple model of mass transport on networks.

  5. The natural statistics of blur.

    PubMed

    Sprague, William W; Cooper, Emily A; Reissier, Sylvain; Yellapragada, Baladitya; Banks, Martin S

    2016-08-01

    Blur from defocus can be both useful and detrimental for visual perception: It can be useful as a source of depth information and detrimental because it degrades image quality. We examined these aspects of blur by measuring the natural statistics of defocus blur across the visual field. Participants wore an eye-and-scene tracker that measured gaze direction, pupil diameter, and scene distances as they performed everyday tasks. We found that blur magnitude increases with increasing eccentricity. There is a vertical gradient in the distances that generate defocus blur: Blur below the fovea is generally due to scene points nearer than fixation; blur above the fovea is mostly due to points farther than fixation. There is no systematic horizontal gradient. Large blurs are generally caused by points farther rather than nearer than fixation. Consistent with the statistics, participants in a perceptual experiment perceived vertical blur gradients as slanted top-back whereas horizontal gradients were perceived equally as left-back and right-back. The tendency for people to see sharp as near and blurred as far is also consistent with the observed statistics. We calculated how many observations will be perceived as unsharp and found that perceptible blur is rare. Finally, we found that eye shape in ground-dwelling animals conforms to that required to put likely distances in best focus. PMID:27580043

  6. Statistical inference and string theory

    NASA Astrophysics Data System (ADS)

    Heckman, Jonathan J.

    2015-09-01

    In this paper, we expose some surprising connections between string theory and statistical inference. We consider a large collective of agents sweeping out a family of nearby statistical models for an M-dimensional manifold of statistical fitting parameters. When the agents making nearby inferences align along a d-dimensional grid, we find that the pooled probability that the collective reaches a correct inference is the partition function of a nonlinear sigma model in d dimensions. Stability under perturbations to the original inference scheme requires the agents of the collective to distribute along two dimensions. Conformal invariance of the sigma model corresponds to the condition of a stable inference scheme, directly leading to the Einstein field equations for classical gravity. By summing over all possible arrangements of the agents in the collective, we reach a string theory. We also use this perspective to quantify how much an observer can hope to learn about the internal geometry of a superstring compactification. Finally, we present some brief speculative remarks on applications to the AdS/CFT correspondence and Lorentzian signature space-times.

  7. Statistical properties of DNA sequences

    NASA Astrophysics Data System (ADS)

    Peng, C.-K.; Buldyrev, S. V.; Goldberger, A. L.; Havlin, S.; Mantegna, R. N.; Simons, M.; Stanley, H. E.

    1995-02-01

    We review evidence supporting the idea that the DNA sequence in genese containing non-coding regions is correlated, and that the correlation is remarkably long range - indeed, nucleotides thousands of base pairs distant are correlated. We do not find such a long-range correlation in the coding regions of the gene. We resolve the problem of the “non-stationarity” feature of the sequence of base pairs by applying a new algorithm called detrended fluctuation analysis (DFA). We address the claim of Voss that there is no difference in the statistical properties of coding and non-coding regions of DNA by systematically applying the DFA algorithm, as well as standard FFT analysis, to every DNA sequence (33 301 coding and 29 453 non-coding) in the entire GenBank database. Finally, we describe briefly some recent work showing that the non-coding sequences have certain statistical features in common with natural and artificial languages. Specifically, we adapt to DNA the Zipf approach to analyzing linguistic texts. These statistical properties of non-coding sequences support the possibility that non-coding regions of DNA may carry biological information.

  8. Statistical analysis of planetary surfaces

    NASA Astrophysics Data System (ADS)

    Schmidt, Frederic; Landais, Francois; Lovejoy, Shaun

    2015-04-01

    In the last decades, a huge amount of topographic data has been obtained by several techniques (laser and radar altimetry, DTM…) for different bodies in the solar system, including Earth, Mars, the Moon etc.. In each case, topographic fields exhibit an extremely high variability with details at each scale, from millimeter to thousands of kilometers. This complexity seems to prohibit global descriptions or global topography models. Nevertheless, this topographic complexity is well-known to exhibit scaling laws that establish a similarity between scales and permit simpler descriptions and models. Indeed, efficient simulations can be made using the statistical properties of scaling fields (fractals). But realistic simulations of global topographic fields must be multi (not mono) scaling behaviour, reflecting the extreme variability and intermittency observed in real fields that can not be generated by simple scaling models. A multiscaling theory has been developed in order to model high variability and intermittency. This theory is a good statistical candidate to model the topography field with a limited number of parameters (called the multifractal parameters). In our study, we show that statistical properties of the Martian topography is accurately reproduced by this model, leading to new interpretation of geomorphological processes.

  9. Using scientifically and statistically sufficient statistics in comparing image segmentations.

    PubMed

    Chi, Yueh-Yun; Muller, Keith E

    2010-01-01

    Automatic computer segmentation in three dimensions creates opportunity to reduce the cost of three-dimensional treatment planning of radiotherapy for cancer treatment. Comparisons between human and computer accuracy in segmenting kidneys in CT scans generate distance values far larger in number than the number of CT scans. Such high dimension, low sample size (HDLSS) data present a grand challenge to statisticians: how do we find good estimates and make credible inference? We recommend discovering and using scientifically and statistically sufficient statistics as an additional strategy for overcoming the curse of dimensionality. First, we reduced the three-dimensional array of distances for each image comparison to a histogram to be modeled individually. Second, we used non-parametric kernel density estimation to explore distributional patterns and assess multi-modality. Third, a systematic exploratory search for parametric distributions and truncated variations led to choosing a Gaussian form as approximating the distribution of a cube root transformation of distance. Fourth, representing each histogram by an individually estimated distribution eliminated the HDLSS problem by reducing on average 26,000 distances per histogram to just 2 parameter estimates. In the fifth and final step we used classical statistical methods to demonstrate that the two human observers disagreed significantly less with each other than with the computer segmentation. Nevertheless, the size of all disagreements was clinically unimportant relative to the size of a kidney. The hierarchal modeling approach to object-oriented data created response variables deemed sufficient by both the scientists and statisticians. We believe the same strategy provides a useful addition to the imaging toolkit and will succeed with many other high throughput technologies in genetics, metabolomics and chemical analysis. PMID:24967000

  10. Statistical Behavior of Filamentary Plasmas

    NASA Astrophysics Data System (ADS)

    Kinney, Rodney Michael

    This work describes a study of plasmas with highly intermittent filamentary structures. A statistical model of two-dimensional magnetohydrodynamics is presented, based on a representation of the fluid as a collection of discrete current-vorticity concentrations. This approach is modeled after discrete vortex models of hydrodynamical turbulence, which cannot be expected in general to produce results identical to a theory based on a Fourier decomposition of the fields. In a highly intermittent plasma, the induction force is small compared to the convective motion, and when this force is neglected, the plasma vortex system is described by a Hamiltonian. Canonical and micro-canonical statistical calculations show that both the vorticity and the current may exhibit large-scale structure, and the expected states revert to known hydrodynamical states as the magnetic field vanishes. These results differ from previous Fourier-based statistical theories, but it is found that when the filament calculation is expanded to include the inductive force, the results approach the Fourier equilibria in the low -temperature limit, and the previous Hamiltonian plasma vortex results in the high-temperature limit. Numerical simulations of a large number of filaments are carried out and support the theory. A three-dimensional vortex model is outlined as well, which is also Hamiltonian when the inductive force is neglected. A statistical calculation in the canonical ensemble and numerical simulations show that a non-zero large-scale magnetic field is statistically favored, and that the preferred shape of this field is a long, thin tube of flux. In a tokamak, a stochastic magnetic field will give rise to strongly filamented current distributions. An external magnetic field possesses field lines described by a non-linear map, while current fluctuations along these field lines have a toroidal dependence which takes the same form as the time dependence of a system of hydrodynamical vortices

  11. Monitoring Statistics Which Have Increased Power over a Reduced Time Range.

    ERIC Educational Resources Information Center

    Tang, S. M.; MacNeill, I. B.

    1992-01-01

    The problem of monitoring trends for changes at unknown times is considered. Statistics that permit one to focus high power on a segment of the monitored period are studied. Numerical procedures are developed to compute the null distribution of these statistics. (Author)

  12. Rain cell size statistics as a function of rain rate for attenuation modeling

    NASA Technical Reports Server (NTRS)

    Goldhirsh, J.

    1983-01-01

    Rain cell size statistics as a function of rain rate have been deduced by employing a radar data base of rain reflectivity data acquired over a three-year period at Wallops Island, VA. These cell statistics have important applications in slant path rain attenuation modeling and remote sensing of the earth's surface from space at frequencies above 10 GHz.

  13. Statistical and Scientometric Analysis of International Research in Geographical and Environmental Education

    ERIC Educational Resources Information Center

    Papadimitriou, Fivos; Kidman, Gillian

    2012-01-01

    Certain statistic and scientometric features of articles published in the journal "International Research in Geographical and Environmental Education" (IRGEE) are examined in this paper for the period 1992-2009 by applying nonparametric statistics and Shannon's entropy (diversity) formula. The main findings of this analysis are: (a) after 2004,…

  14. 21 CFR 820.250 - Statistical techniques.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Statistical techniques. 820.250 Section 820.250...) MEDICAL DEVICES QUALITY SYSTEM REGULATION Statistical Techniques § 820.250 Statistical techniques. (a... statistical techniques required for establishing, controlling, and verifying the acceptability of...

  15. 42 CFR 402.109 - Statistical sampling.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 42 Public Health 2 2014-10-01 2014-10-01 false Statistical sampling. 402.109 Section 402.109... Statistical sampling. (a) Purpose. CMS or OIG may introduce the results of a statistical sampling study to... or caused to be presented. (b) Prima facie evidence. The results of the statistical sampling...

  16. 42 CFR 402.109 - Statistical sampling.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 42 Public Health 2 2012-10-01 2012-10-01 false Statistical sampling. 402.109 Section 402.109... Statistical sampling. (a) Purpose. CMS or OIG may introduce the results of a statistical sampling study to... or caused to be presented. (b) Prima facie evidence. The results of the statistical sampling...

  17. 21 CFR 820.250 - Statistical techniques.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Statistical techniques. 820.250 Section 820.250...) MEDICAL DEVICES QUALITY SYSTEM REGULATION Statistical Techniques § 820.250 Statistical techniques. (a... statistical techniques required for establishing, controlling, and verifying the acceptability of...

  18. 21 CFR 820.250 - Statistical techniques.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Statistical techniques. 820.250 Section 820.250...) MEDICAL DEVICES QUALITY SYSTEM REGULATION Statistical Techniques § 820.250 Statistical techniques. (a... statistical techniques required for establishing, controlling, and verifying the acceptability of...

  19. 42 CFR 402.109 - Statistical sampling.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 42 Public Health 2 2013-10-01 2013-10-01 false Statistical sampling. 402.109 Section 402.109... Statistical sampling. (a) Purpose. CMS or OIG may introduce the results of a statistical sampling study to... or caused to be presented. (b) Prima facie evidence. The results of the statistical sampling...

  20. Learning Abstract Statistics Concepts Using Simulation

    ERIC Educational Resources Information Center

    Mills, Jamie D.

    2004-01-01

    The teaching and learning of statistics has impacted the curriculum in elementary, secondary, and post-secondary education. Because of this growing movement to expand and include statistics into all levels of education, there is also a considerable interest in how to teach statistics. For statistics concepts that tend to be very difficult or…